Search by property

This page provides a simple browsing interface for finding entities described by a property and a named value. Other available search interfaces include the page property search, and the ask query builder.

List of results

Bezuidenhout 2016a Abstract MitoFit Science Camp 2016 + (It has been reported that the oxygen (O< … It has been reported that the oxygen (O2) dependence of mitochondrial respiration in permeabilized fibers (Pfi) is ~100-fold higher compared to isolated mitochondria [1]. Pfi are sensitive to low oxygen supply due to diffusion restrictions that limit the supply of oxygen to the core of the fiber bundle. Therefore, hyperoxic conditions (oxygen range 400-250 μM) have been employed to counteract this limitation. Further studies have shown that the addition of a myosin II-specific inhibitor, blebbistatin (BLEB) in the respiration medium reduces this sensitivity and allows the study of ADP kinetics in Pfi at normoxic oxygen levels (250-200 μM). Moreover, it has been described that the use of BLEB prevents fiber contraction and yields high Km values for ADP [2].In the present study, high-resolution respirometry (HRR) was used to test ADP respiratory kinetics in skeletal muscle Pfi from wild-type C57BL/6 mice under three different oxygen regimens: hypoxia (100-80 μM), normoxia (250-200 μM) and hyperoxia (400 μM) comparing two respiration media: Buffer Z with catalase (Ctl), creatine (Cr) and BLEB (BufferZCtlCr+BLEB) and MiR06+Cr (MiR06Cr) at a physiological temperature of 37 °C. Data were normalized to wet weight (''W''w) (mg of tissue), complex IV (COX) and citrate synthase (CS) activities.In our experiments, we found no differences in O2 flux when comparing rates determined in Buffer ZCtlCr + BLEB and MiR06Cr. However, our results do show that different O2 regimens such as hypoxic and normoxic conditions in the O2k-chamber may lead to a relevant underestimation of OXPHOS capacity due to the oxygen limitation in both media (BufferZCtlCr+BLEB and MiR06Cr). It would therefore appear that, in our hands, the use of BufferZCtlCr with the addition of BLEB does not alleviate O2 dependency in permeabilized skeletal muscle fibers.ot alleviate O2 dependency in permeabilized skeletal muscle fibers.)
Larsen 2014 Biochim Biophys Acta + (It has been suggested that human mitochond … It has been suggested that human mitochondrial variants influence maximal oxygen uptake (VO2max). Whether mitochondrial respiratory capacity per mitochondrion (intrinsic activity) in human skeletal muscle is affected by differences in mitochondrial variants is not known. We recruited 54 males and determined their mitochondrial haplogroup, mitochondrial oxidative phosphorylation capacity (OXPHOS), mitochondrial content (citrate synthase (CS)) and VO2max. Intrinsic mitochondrial function is calculated as mitochondrial OXPHOS capacity divided by mitochondrial content (CS). Haplogroup H showed a 30% higher intrinsic mitochondrial function compared with the other haplo group U. There was no relationship between haplogroups and VO2max. In skeletal muscle from men with mitochondrial haplogroup H, an increased intrinsic mitochondrial function is present.trinsic mitochondrial function is present.)
Yin 2014 J Clin Endocrinol Metab + (It has been suggested that mitochondrial d … It has been suggested that mitochondrial dysfunctional in adipocytes contribute to obesity-related metabolic complications. However, obesity results in adipocyte hypertrophy, large and small adipocytes from the same depot have different characteristics, raising the possibility that obesity-related mitochondrial defects are an inherent function of large adipocytes.Objective:to examine whether obesity, independent of fat cell size and fat depot, is associated with mitochondria dysfunction.Design:cross-sectional comparison.Setting:Academic medical center.Patients or Other Participants:omental (OM) and/or abdominal subcutaneous (SQ) adipose samples were collected from 20, age-matched obese and non-obese non-diabetic men and women undergoing either elective abdominal surgery or research needle biopsy.Intervention:None.Main Outcome Measures:mitochondrial DNA abundance, oxygen consumption rates (OCR) and citrate synthase (CS) activity from populations of large and small adipocytes (separated with differential floatation).Results:For both omental and subcutaneous adipocytes, at the cell and organelle level, OCR and CS activity were significantly reduced in cells from obese compared with non-obese volunteers, even when matched for cell size by comparing large adipocytes from non-obese and small adipocytes from obese. Adipocyte mitochondrial content was not significantly different between obese and non-obese volunteers. Mitochondrial function and content parameters were not different between small and large cells, omental and subcutaneous adipocytes from the same person.Conclusion:Adipocyte mitochondrial oxidative capacity is reduced in obese compared to non-obese adults and this difference is not due to cell size differences. Adipocyte mitochondrial dysfunction in obesity is therefore related to overall adiposity rather than adipocyte hypertrophy.iposity rather than adipocyte hypertrophy.)
Yao 2018 PLoS Biol + (It has been suggested that some cancer cel … It has been suggested that some cancer cells rely upon fatty acid oxidation (FAO) for energy. Here we show that when FAO was reduced approximately 90% by pharmacological inhibition of carnitine palmitoyltransferase I (CPT1) with low concentrations of etomoxir, the proliferation rate of various cancer cells was unaffected. Efforts to pharmacologically inhibit FAO more than 90% revealed that high concentrations of etomoxir (200 μM) have an off-target effect of inhibiting complex I of the electron transport chain. Surprisingly, however, when FAO was reduced further by genetic knockdown of CPT1, the proliferation rate of these same cells decreased nearly 2-fold and could not be restored by acetate or octanoic acid supplementation. Moreover, CPT1 knockdowns had altered mitochondrial morphology and impaired mitochondrial coupling, whereas cells in which CPT1 had been approximately 90% inhibited by etomoxir did not. Lipidomic profiling of mitochondria isolated from CPT1 knockdowns showed depleted concentrations of complex structural and signaling lipids. Additionally, expression of a catalytically dead CPT1 in CPT1 knockdowns did not restore mitochondrial coupling. Taken together, these results suggest that transport of at least some long-chain fatty acids into the mitochondria by CPT1 may be required for anabolic processes that support healthy mitochondrial function and cancer cell proliferation independent of FAO.cer cell proliferation independent of FAO.)
Kluckova 2022 Hemasphere + (It has been unclear what role metabolism i … It has been unclear what role metabolism is playing in the pathophysiology of chronic lymphocytic leukemia (CLL). One reason is that the study of CLL metabolism is challenging due to the resting nature of circulating CLL cells. Also, it is not clear if any of the genomic aberrations observed in this disease have any impact on metabolism. Here, we demonstrate that CLL cells in proliferation centers exhibit upregulation of several molecules involved in glycolysis and mitochondrial metabolism. Comparison of CXCR4/CD5 intraclonal cell subpopulations showed that these changes are paralleled by increases in the metabolic activity of the CXCR4lowCD5high fraction that have recently egressed from the lymph nodes. Notably, anti-IgM stimulation of CLL cells recapitulates many of these metabolic alterations, including increased glucose uptake, increased lactate production, induction of glycolytic enzymes, and increased respiratory reserve. Treatment of CLL cells with inhibitors of B-cell receptor (BCR) signaling blocked these anti-IgM-induced changes ''in vitro'', which was mirrored by decreases in hexokinase 2 expression in CLL cells from ibrutinib-treated patients ''in vivo''. Interestingly, several samples from patients with 17p-deletion manifested increased spontaneous aerobic glycolysis in the unstimulated state suggestive of a BCR-independent metabolic phenotype. We conclude that the proliferative fraction of CLL cells found in lymphoid tissues or the peripheral blood of CLL patients exhibit increased metabolic activity when compared with the bulk CLL-cell population. Although this is due to microenvironmental stimulatory signals such as BCR-engagement in most cases, increases in resting metabolic activity can be observed in cases with 17p-deletion.ing metabolic activity can be observed in cases with 17p-deletion.)
Rocha 2018 Antioxidants (Basel) + (It has long been accepted that mitochondri … It has long been accepted that mitochondrial function and morphology is affected in Parkinson's disease, and that mitochondrial function can be directly related to its morphology. So far, mitochondrial morphological alterations studies, in the context of this neurodegenerative disease, have been performed through microscopic methodologies. The goal of the present work is to address if the modifications in the mitochondrial-shaping proteins occurring in this disorder have implications in other cellular pathways, which might constitute important pathways for the disease progression. To do so, we conducted a novel approach through a thorough exploration of the available proteomics-based studies in the context of Parkinson's disease. The analysis provided insight into the altered biological pathways affected by changes in the expression of mitochondrial-shaping proteins via different bioinformatic tools. Unexpectedly, we observed that the mitochondrial-shaping proteins altered in the context of Parkinson's disease are, in the vast majority, related to the organization of the mitochondrial cristae. Conversely, in the studies that have resorted to microscopy-based techniques, the most widely reported alteration in the context of this disorder is mitochondria fragmentation. Cristae membrane organization is pivotal for mitochondrial ATP production, and changes in their morphology have a direct impact on the organization and function of the oxidative phosphorylation (OXPHOS) complexes. To understand which biological processes are affected by the alteration of these proteins we analyzed the binding partners of the mitochondrial-shaping proteins that were found altered in Parkinson's disease. We showed that the binding partners fall into seven different cellular components, which include mitochondria, proteasome, and endoplasmic reticulum (ER), amongst others. It is noteworthy that, by evaluating the biological process in which these modified proteins are involved, we showed that they are related to the production and metabolism of ATP, immune response, cytoskeleton alteration, and oxidative stress, amongst others. In summary, with our bioinformatics approach using the data on the modified proteins in Parkinson's disease patients, we were able to relate the alteration of mitochondrial-shaping proteins to modifications of crucial cellular pathways affected in this disease.ellular pathways affected in this disease.)
Zeng 2014 Br J Nutr + (It has not been established which specific … It has not been established which specific measures of obesity might be most appropriate for predicting CVD risk in Asians. The objectives of the present study were to determine the associations of BMI, waist circumference (WC) and waist:height ratio (WHtR) with CVD risk factors and to evaluate the optimal cut-off values to define overweight or obesity in Chinese adults. Data collected from seven nationwide health examination centres during 2008 and 2009 were analysed. The BMI, WC and WHtR of 244 266 Chinese adults aged ≥ 20 years included in the study were measured. Logistic regression models were fit to evaluate the OR of each CVD risk factor according to various anthropometric indices. Receiver operating characteristic (ROC) analyses were conducted to assess the optimal cut-off values to predict the risk of diabetes, hypertension, dyslipidaemia and the metabolic syndrome. WHtR had the largest areas under the ROC curve for all CVD risk factors in both sexes, followed by WC and BMI. The optimal cut-off values were approximately 24·0 and 23·0 kg/m2 for BMI, 85·0 and 75·0 cm for WC, and 0·50 and 0·48 for WHtR for men and women, respectively. According to well-established cut-off values, BMI was found to be a more sensitive indicator of hypertension in both men and women, while WC and WHtR were found to be better indicators of diabetes and dyslipidaemia. A combination of BMI and central obesity measures was found to be associated with greater OR of CVD risk factors than either of them alone in both sexes. The present study demonstrated that WHtR and WC may be better indicators of CVD risk factors for Chinese people than BMI. risk factors for Chinese people than BMI.)
Larsen S 2013 Abstract MiP2013 + (It has previously been reported that mitoc … It has previously been reported that mitochondrial ADP sensitivity decreases (higher Km’) with endurance training in human skeletal muscle [1]. This decrease was accompanied by an increased maximal ADP stimulated mt-respiration (Jmax) and an increased maximal oxygen uptake (VO2max). It is not known whether high intensity training (HIT) has the same effect on mitochondria and if these changes also occur in mitochondria from human adipose tissue. The aim of this project was to investigate mitochondrial ADP sensitivity and maximal ADP stimulated respiration in human adipose and skeletal muscle tissue after six weeks of HIT. Twelve healthy overweight subjects (7 F/5 M) (age: 40±2 yrs, BMI: 32±2, VO2max: 2612±166 ml/min) were included in the study. The subjects underwent six weeks (3 times a week) of HIT. VO2max was measured pre and post training. Mitochondrial ADP sensitivity (Km’) and Jmax was measured pre and post HIT in adipose tissue and permeabilized muscle fibers by high-resolution respirometry (Oxygraph-2k, Oroboros, Insbruck, Austria). The adipose tissue was permeabilized with digitonin and the skeletal muscle fibers with saponin. The protocol used for respirometry was as follows: Malate (2 mM), Glutamate (10 mM) and ADP titrated in the following steps (0.05 – 0.10 – 0.25 – 0.50 – 1.00 – 2.50 – 5.00 mM). SigmaPlot was used to determine Km’ for ADP and Jmax.VO2max was significantly improved after HIT. Mitochondrial ADP sensitivity was significantly (P<0.05) decreased after HIT in permeabilized skeletal muscle (0.14±0.02 mM vs. 0.29±0.03 mM), and the same trend was seen in adipose tissue although not significant (P=0.056; 0.11±0.02 mM vs. 0.16±0.04 mM). Jmax was similar after HIT in permeabilized skeletal muscle (21±1 pmol∙s-1∙mg-1 vs. 22±1 pmol∙s-1∙mg-1) as well as in adipose tissue (0.36±0.03 pmol∙s-1∙mg-1 vs. 0.36±0.03 pmol∙s1∙mg-1), before vs. after, respectively.ADP sensitivity decreased in permeabilized human skeletal muscle and the same trend was seen in adipose tissue. This was accompanied by a similar maximal ADP stimulated respiration pre and post training in both skeletal muscle and adipose tissue. This is the first time that ADP sensitivity has been investigated in adipose tissue. Interestingly the HIT training adaptation in mitochondria from adipose tissue is similar to that observed in skeletal muscle although not with the same magnitude. muscle although not with the same magnitude.)
Loew 1961 Biochem Biophys Res Commun + (It has recently been reported from several … It has recently been reported from several laboratories that mitochondrial DPN is reduced by succinate and that this reduction requires the addition of ATP. All of these studies involved intact mitochondria and bound DPN.In the present communication some experiments will be described which deal with the reduction of added DPN by a submitochondrial particle from beef heart muscle, ETPH. This particle enjoys several advantages for the study of DPN reduction; it contains little or no bound DPN, and does not have a functional Krebs cycle (which excludes any reduction of DPN by substrates other than succinate).f DPN by substrates other than succinate).)
Boushel 2014 Acta Physiol (Oxf) + (It is an ongoing discussion the extent to … It is an ongoing discussion the extent to which oxygen delivery and oxygen extraction contribute to an elevated muscle oxygen uptake during dynamic exercise. It has been proposed that local muscle factors including the capillary bed and mitochondrial oxidative capacity play a large role in prolonged low intensity training of a small muscle group when the cardiac output capacity is not directly limiting. The purpose of this study was to investigate the relative roles of circulatory and muscle metabolic mechanisms by which prolonged low-intensity exercise training alters regional muscle ''V''O2.In 9 healthy volunteers (7 male, 2 female), hemodynamic and metabolic responses to incremental arm cycling were measured by the Fick method and biopsy of the deltoid and triceps muscles before and after 42 days of skiing for 6 h.day-1 at 60 % max heart rate.Peak pulmonary ''V''O2 during arm crank was unchanged after training (2.38±0.19 vs. 2.18±0.2 L.min-1 pre-training) yet arm ''V''O2 (1.04±0.08 vs. 0.83±0.1 L.min-1, ''P''<0.05) and power output (137±9 vs. 114±10 W) were increased along with a higher arm blood flow (7.9±0.5 vs. 6.8±0.6 L.min-1, ''P''<0.05) and expanded muscle capillary volume (76±7 vs. 62±4 mL, ''P''<0.05). Muscle O2 diffusion capacity (16.2±1 vs. 12.5 ±0.9 mL.min-1.mmHg-1, ''P''<0.05) and O2 extraction (68±1 vs. 62±1 %, ''P''<0.05) were enhanced at a similar mean capillary transit time (569±43 vs. 564±31 ms) and ''p''50 (35.8±0.7 vs. 35±0.8), whereas mitochondrial O2 flux capacity was unchanged (147±6 mL.min-1.kg-1 vs. 146±8 mL.min-1.kg-1).The mechanisms underlying the increase in peak arm ''V''O2 with prolonged low intensity training in previously untrained subjects are an elevated convective O2 delivery specifically to the muscles of the arm combined with a larger capillary-muscle surface area that enhance diffusional O2 conductance, with no apparent role of mitochondrial respiratory capacity. This article is protected by copyright. All rights reserved. an elevated convective O2 delivery specifically to the muscles of the arm combined with a larger capillary-muscle surface area that enhance diffusional O2 conductance, with no apparent role of mitochondrial respiratory capacity. This article is protected by copyright. All rights reserved. )
Kidane 1997 J Thermal Anal + (It is claimed, though not without dispute, … It is claimed, though not without dispute, that genetically engineered mammalian cells grow more slowly than their progenitor cells because the recombinant gene system causes a metabolic burden. This was found to be the case for CHO cells transfected with expression vectors forcytochrome b5. The slower growth was associated with lower metabolic activity measured by heat flux and mitochondrial activity (rhodamine 123 fluorescence). The calorimetric-respirometric ratio was similar for all cell types, implying that the greater fluxes of glucose and glutamine in the recombinant cells was channelled to biosynthesis. This demand probably restricted the supply of pyruvate to the mitochondria in these cells.ruvate to the mitochondria in these cells.)
Dungel 2011 J Biochem Mol Toxicol + (It is commonly accepted that the major eff … It is commonly accepted that the major effect of nitroglycerin (NG) is realized through the release of nitric oxide (NO) catalyzed by aldehyde dehydrogenase-2 (ALDH2). In addition, it has been shown that NG inhibits mitochondrial respiration. The aim of this study was to clarify whether NG-mediated inhibition of mitochondrial respiration is mediated by NO. In rat liver mitochondria, NG inhibited complex-I-dependent respiration and induced reactive oxygen species (ROS) production, preferentially at complex I. Both effects were insensitive to chloral hydrate, an ALDH2 inhibitor. Nitrite, an NG intermediate, had no influence on either mitochondrial respiration or the production of ROS. NO inhibited preferentially complex I but did not elevate ROS production. Hemoglobin, an NO scavenger, and blue light had contrary effects on mitochondria inhibited by NO or NG. In summary, our data suggest that although NG induces vasodilatation via NO release, it causes mitochondrial dysfunction via an NO-independent pathway.dysfunction via an NO-independent pathway.)
Jang 2018 J Med Toxicol + (It is conservatively estimated that 5000 d … It is conservatively estimated that 5000 deaths per year and 20,000 injuries in the USA are due to poisonings caused by chemical exposures (e.g., carbon monoxide, cyanide, hydrogen sulfide, phosphides) that are cellular inhibitors. These chemical agents result in mitochondrial inhibition resulting in cardiac arrest and/or shock. These cellular inhibitors have multi-organ effects, but cardiovascular collapse is the primary cause of death marked by hypotension, lactic acidosis, and cardiac arrest. The mitochondria play a central role in cellular metabolism where oxygen consumption through the electron transport system is tightly coupled to ATP production and regulated by metabolic demands. There has been increasing use of human blood cells such as peripheral blood mononuclear cells and platelets, as surrogate markers of mitochondrial function in organs due to acute care illnesses. We demonstrate the clinical applicability of measuring mitochondrial bioenergetic and dynamic function in blood cells obtained from patients with acute poisoning using carbon monoxide poisoning as an illustration of our technique. Our methods have potential application to guide therapy and gauge severity of disease in poisoning related to cellular inhibitors of public health concern.lular inhibitors of public health concern.)
Kozlov 2010 Abstract IOC60 + (It is difficult to clarify mechanisms unde … It is difficult to clarify mechanisms underlying cellular dysfunction induced by shock in in vivo models, because of their multiple physiological/ pathological regulations. Shock comprises two major pathologic stimuli, namely low levels of oxygen and high levels of inflammatory mediators. In our experiments we used hepatocyte cell line (HEP), liver slices (LS), and liver tissue (LT) to simulate either ischemia or inflammatory response. Confocal and electron microscopy examinations revealed that mitochondria in LS and LT are fragmented while in HEP they built up a network. Hypoxia induced the loss of mitochondrial respiratory activity (in LT & LS), total decrease in ATP levels (LT & LS), the release of ALT/AST, cytoplasmic enzymes, (in LS & HEP), strong degradation of intracellular RNA (in LS & HEP) and an increase in numbers of necrotic, but not apoptotic cells (HC). In LT and LS these changes occurred after 2 h of hypoxia, while HEP required 24 h of ischemia to induce damage to a similar extend. Mitochondrial dysfunction mediated by hypoxia was fully recovered by exogenous cytochrome c (LT). Exposure to naturally generated inflammatory mediators under normoxic conditions resulted in a moderate decrease in ATP levels (LS, LT) and Δψ (HEP), fragmentation of mitochondrial network, and increased levels of mitochondrial ROS (LT & HEP). Experiments with radical scavengers revealed that the major target for mitochondrial ROS are not mitochondria but the expression of specific genes regulating inflammatory and unfolded protein responses. Our data suggest that the lost of cytochrome c and disrupted ATP synthesis are the predominant mitochondrial response to hypoxia but not to inflammatory mediators. The predominant mitochondrial response to inflammatory mediators is increased levels of mitochondrial ROS. Fragmentation of mitochondria is likely of marginal pathological significance in these models. likely of marginal pathological significance in these models.)
Mootha 1997 Am J Physiol + (It is difficult to estimate the maximum in … It is difficult to estimate the maximum in vivo aerobic ATP production rate of the intact heart independent of limitations imposed by blood flow, oxygen delivery, and maximum mechanical power. This value is critical for establishing the kinetic parameters that control oxidative phosphorylation, as well as for providing insights into the limits of myocardial performance. In this study, the maximum ADP-P(i)-driven heart mitochondrial respiratory rate (MV(O2 mito)) was determined with saturating levels of oxygen, substrates, and cofactors at 37 degrees C. These rates were normalized to cytochrome alpha1 alpha3 (cytochrome oxidase; Cyt a) content. To extrapolate this rate to the intact heart, the Cyt a content of the myocardium (nmol Cyt a/g wet wt myocardium) was determined in the same hearts. The maximum ADP-P(i)-driven mitochondrial respiratory rates were 676 +/- 31 and 665 +/- 65 nmol O2 x min(-1) x nmol Cyt a(-1) in the dog and pig, respectively. The Cyt a content in the two species was 43.6 +/- 2.4 and 36.6 +/- 3.1 nmol Cyt a/g wet wt, respectively. With these values, the MV(O2 mito) was calculated to be 29.5 (dog) and 24.3 (pig) micromol O2 x min(-1) x g wet wt myocardium(-1). Comparison with in vivo studies shows that the exercising heart can utilize 80-90 % of its maximum oxidative capacity, implying there is little aerobic ATP production reserve in the mammalian heart.production reserve in the mammalian heart.)
Sullivan 2015 Abstract MiPschool Greenville 2015 + (It is hypothesized that cardiolipin molecu … It is hypothesized that cardiolipin molecules in the inner mitochondrial membrane form spatially distinct lipid microdomains that facilitate the formation of supercomplexes and allow for efficient electron transport and ATP production. Cardiolipin-enriched microdomains from mitochondria can potentially be isolated biochemically in the presence of 1% Triton-X 100 [1]. Previous studies show that the amount and type of detergent are critical variables in the isolation of lipid microdomains in other organelles. Therefore, we first investigated the influence of different detergents at different concentrations on the isolation of biochemical cardiolipin- enriched microdomains [2]. Next, we determined if supercomplexes were associated with the detergent resistant cardiolipin-enriched microdomains. Biochemical isolation of mitochondrial microdomains was adapted from a previous protocol [1]. Briefly, isolated mitochondria were subjected to a range of detergents (Triton X-100, NP-40 or digitonin) at varying concentrations (0.01%, 0.05% or 0.50%). Next, mitochondria were centrifuged at 20,000 x g, which separated the detergent resistant membranes (DRM) microdomains from the non-microdomain fraction, known as detergent soluble membranes (DSM). Both DSM and DRM fractions were subjected to lipid extraction; the lipids were separated via thin layer chromatography (TLC), visualized by phosphoric charring and quantified via densitometry. Blue native PAGE (BN-PAGE) determined whether the DSM or DRM fraction contained supercomplexes. BN-PAGE protocol was adapted from the NativePAGE system from Life Technologies. Briefly, DSM and DRM fractions underwent solubilization with digitonin. Samples were centrifuged at 16,875 x g and the supernatants containing supercomplexes were collected. Protein was loaded onto the native gel as directed and ran until completion. Gels were fixed, and then destained overnight until the desired background was reached.Analysis of TLC plates strikingly revealed that DRM fractions were not just enriched in cardiolipin but also contained phosphatidylcholine and phosphatidylethanolamine. Increasing the concentration of each detergent resulted in a decreased amount of phosphatidylethanolamine, cardiolipin and phosphatidylcholine in the DRMs. This decrease in phospholipids in the DRMs was paralleled by an increase in lipid content of the DSMs with one exception. No decrease in lipids was detected in the DRMs from 0.01% digitonin to 0.05% digitonin. Preliminary data with BN-PAGE results from each detergent at the 0.05% concentration showed supercomplexes to only be present in the DRM fraction.Taken together, our results reveal no differences in the type of detergent used to isolate DRMs. These results also suggest that lipid microdomains formed in the mitochondria are not simply enriched in cardiolipin and likely contain several other lipid species. Although more precise analytical tools may be required for more in-depth mitochondrial membrane analysis, the supercomplexes housed in the inner mitochondrial membrane were associated with DRMs implying supercomplexes may rely on distinct lipid microdomains for optimal function.t lipid microdomains for optimal function.)
Gorbacheva 2016 International Symposium Mitochondrial Motility + (It is known that cardiovascular diseases a … It is known that cardiovascular diseases are the main problem of present medicine. Recently, for the treatment of these diseases have been widely used various modulators of calcium and potassium channels, as well as inhibitors of the renin-angiotensin system [1].With the collaboration of laboratories O.O. Moibenko and L.M. Yagupolskii developed technological scheme of synthesis of a new cardioprotective fluorine-containing pinacidil derivative preparation floсalin [2]. It was shown that this preparation at experimental acute ischemia/reperfusion has pronounced cardioprotective properties in animals and reduces myocardial infarct size relative to control without treatment by 42% [3]. It is assumed that one of the mechanisms cardiopro-tection in this case may be to increase the proportion cNOS/iNOS activity. In addition, it is shown that flocalin promotes normalization of bioenergetic metabolism in the ischemic brain, restoring the content of adenine nucleotides and creatine phosphate against decrease metabolic acidosis and growth of glucose [4].Since flocalin is a fluorine-containing analog of pinacidil - known opener of ATP-sensitive potassium channel both cytoplasmic (sarcKATP) and mitochondrial (mitoKATP) membranes [5], the aim of work was to investigate the effect of this preparation on the functioning of mitochondria, and in particular, on work of mitoKATP channel.n particular, on work of mitoKATP channel.)
Shigaeva 2013 Abstract MiP2013 + (It is known that different people and anim … It is known that different people and animals within the same species have different resistance to the stress damage. It is believed that these differences are largely genetically determined or acquired during the life of the differences in the activity of the stress system implementing the organism's response to stress-factor. Our objective was to determine the role of mitochondrial ATP-dependent potassium channel (mtKATP), which plays a key role in protecting the myocardium from ischemia [1], in protecting of the organism against some types of stress and adaptation to it.The work was carried out on heart and liver mitochondria of rats of different genetic lines. To perform the first part of the study we selected purebred white rats having high and low resistance to acute hypoxic stress. Part of the low resistant animals were then artificially adapted to acute hypobaric hypoxia. The second part of the work was carried out on rats Wistar and August lines, having different resistance to the stress damage of the circulatory system [2] and to hypoxia [3] (August rats are resistant to stress influences, Wistar rats are less resistant).When using outbred rats we have shown that the rate of ATP-dependent potassium transport was higher (by 15% in liver mitochondria and 30% in heart mitochondria) in mitochondria of high resistant to hypoxia rats compared with a low resistance. In adapted to oxygen deficiency rats rate of ATP-dependent potassium transport in mitochondria of both tissues is increased by 45-50%. It is accompanied by a decrease in the amount of K+ in the mitochondria of both tissues by an average of 30%, which may indicate the activation also K+/H+-antiporter in mitochondria. Thus, the potassium cycle is activated in mitochondria. The same effect was observed in the study of potassium transport in mitochondria of rats Wistar and August lines. In more resistant to stress August line rats potassium uptake into the mitochondria via mtKATP and the potassium amount were significantly higher compared to Wistar line rats.A high rate of mitochondrial potassium transport led to a marked reduction (by 25-30%) of the rate of generation of H2O2 in the mitochondria. We presume that the effect of reducing the formation of reactive oxygen species in the mitochondria as a result of the activation mtKATP may mediate the positive effect of hypoxic training as well as genetic resistance to oxidative stress.may mediate the positive effect of hypoxic training as well as genetic resistance to oxidative stress.)
Brierley 1994 J Bioenerg Biomembr + (It is now well established that mitochondr … It is now well established that mitochondria contain three antiporters that transport monovalent cations. A latent, allosterically regulated K+/H+ antiport appears to serve as a cation-extruding device that helps maintain mitochondrial volume homeostasis. An apparently unregulated Na+/H+ antiport keeps matrix [Na+] low and the Na(+)-gradient equal to the H(+)-gradient. A Na+/Ca2+ antiport provides a Ca(2+)-extruding mechanism that permits the mitochondrion to regulate matrix [Ca2+] by balancing Ca2+ efflux against influx on the Ca(2+)-uniport. All three antiports have well-defined physiological roles and their molecular properties and regulatory features are now being determined. Mitochondria also contain monovalent cation uniports, such as the recently described ATP- and glibenclamide-sensitive K+ channel and ruthenium red-sensitive uniports for Na+ and K+. A physiological role of such uniports has not been established and their properties are just beginning to be defined.operties are just beginning to be defined.)
Pham 2016 Sensors (Basel) + (It is now well established that, even with … It is now well established that, even within a single cell, multiple copies of the mitochondrial genome may be present (genetic heteroplasmy). It would be interesting to develop techniques to determine if and to what extent this genetic variation results in functional variation from one mitochondrion to the next (functional heteroplasmy). Measuring mitochondrial respiration can reveal the organelles' functional capacity for Adenosine triphosphate (ATP) production and determine mitochondrial damage that may arise from genetic or age related defects. However, available technologies require significant quantities of mitochondria. Here, we develop a technology to assay the respiration of a single mitochondrion. Our "micro-respirometer" consists of micron sized chambers etched out of borofloat glass substrates and coated with an oxygen sensitive phosphorescent dye Pt(II) meso-tetra(pentafluorophenyl)porphine (PtTFPP) mixed with polystyrene. The chambers are sealed with a polydimethylsiloxane layer coated with oxygen impermeable Viton rubber to prevent diffusion of oxygen from the environment. As the mitochondria consume oxygen in the chamber, the phosphorescence signal increases, allowing direct determination of the respiration rate. Experiments with coupled vs. uncoupled mitochondria showed a substantial difference in respiration, confirming the validity of the microchambers as single mitochondrial respirometers. This demonstration could enable future high-throughput assays of mitochondrial respiration and benefit the study of mitochondrial functional heterogeneity, and its role in health and disease.neity, and its role in health and disease.)
Salin 2015 Proc Biol Sci + (It is often assumed that an animal's metab … It is often assumed that an animal's metabolic rate can be estimated through measuring the whole-organism oxygen consumption rate. However, oxygen consumption alone is unlikely to be a sufficient marker of energy metabolism in many situations. This is due to the inherent variability in the link between oxidation and phosphorylation; that is, the amount of adenosine triphosphate (ATP) generated per molecule of oxygen consumed by mitochondria (P/O ratio). In this article, we describe how the P/O ratio can vary within and among individuals, and in response to a number of environmental parameters, including diet and temperature. As the P/O ratio affects the efficiency of cellular energy production, its variability may have significant consequences for animal performance, such as growth rate and reproductive output. We explore the adaptive significance of such variability and hypothesize that while a reduction in the P/O ratio is energetically costly, it may be associated with advantages in terms of somatic maintenance through reduced production of reactive oxygen species. Finally, we discuss how considering variation in mitochondrial efficiency, together with whole-organism oxygen consumption, can permit a better understanding of the relationship between energy metabolism and life history for studies in evolutionary ecology.story for studies in evolutionary ecology.)
Brown 2012 Mitochondrion + (It is often assumed that mitochondria are … It is often assumed that mitochondria are the main source of reactive oxygen species (ROS) in mammalian cells, but there is no convincing experimental evidence for this in the literature. What evidence there is suggests mitochondria are a significant source for ROS, which may have physiological and pathological effects. But quantitatively, endoplasmic reticulum and peroxisomes have a greater capacity to produce ROS than mitochondria, at least in liver. In most cells and physiological or pathological conditions there is a lack of evidence for or against mitochondria being the main source of cellular ROS. Mitochondria can rapidly degrade ROS and thus are potential sinks for ROS, but whether mitochondria act as net sources or sinks within cells in particular conditions is unknown.cells in particular conditions is unknown.)
Sender 2016 Cell + (It is often presented as common knowledge that, in the human body, bacteria outnumber human cells by a ratio of at least 10:1. Revisiting the question, we find that the ratio is much closer to 1:1.)
Schönfeld 2013 J Cereb Blood Flow Metab + (It is puzzling that hydrogen-rich fatty ac … It is puzzling that hydrogen-rich fatty acids are used only poorly as fuel in the brain. The long-standing belief that a slow passage of fatty acids across the blood-brain barrier might be the reason. However, this has been corrected by experimental results. Otherwise, accumulated nonesterified fatty acids or their activated derivatives could exert detrimental activities on mitochondria, which might trigger the mitochondrial route of apoptosis. Here, we draw attention to three particular problems: (1) ATP generation linked to β-oxidation of fatty acids demands more oxygen than glucose, thereby enhancing the risk for neurons to become hypoxic; (2) β-oxidation of fatty acids generates superoxide, which, taken together with the poor anti-oxidative defense in neurons, causes severe oxidative stress; (3) the rate of ATP generation based on adipose tissue-derived fatty acids is slower than that using blood glucose as fuel. Thus, in periods of extended continuous and rapid neuronal firing, fatty acid oxidation cannot guarantee rapid ATP generation in neurons. We conjecture that the disadvantages connected with using fatty acids as fuel have created evolutionary pressure on lowering the expression of the β-oxidation enzyme equipment in brain mitochondria to avoid extensive fatty acid oxidation and to favor glucose oxidation in brain.n and to favor glucose oxidation in brain.)
Rich 1984 Biochim Biophys Acta + (It is the aim of this article to discuss t … It is the aim of this article to discuss the details of electron and proton transfers through quinones and cytochrome ''bc'' complexes. Emphasis will be placed on the molecular organisation and mobility of components, on the chemistry of the individual redox steps, and on the relation of these factors to overall protonmotive ability.e factors to overall protonmotive ability.)
Noone 2023 J Physiol + (It is unclear how skeletal muscle metaboli … It is unclear how skeletal muscle metabolism and mitochondrial function adapt to long duration bed rest and whether changes can be prevented by nutritional intervention. The present study aimed (1) to assess the effect of prolonged bed rest on skeletal muscle mitochondrial function and dynamics and (2) to determine whether micronutrient supplementation would mitigate the adverse metabolic effect of bed rest. Participants were maintained in energy balance throughout 60 days of bed rest with micronutrient supplementation (INT) (body mass index: 23.747 ± 1.877 kg m-2 ; 34.80 ± 7.451 years; n = 10) or without (control) (body mass index: 24.087 ± 2.088 kg m-2 ; 33.50 ± 8.541 years; n = 10). Indirect calorimetry and dual-energy x-ray absorptiometry were used for measures of energy expenditure, exercise capacity and body composition. Mitochondrial respiration was determined by high-resolution respirometry in permeabilized muscle fibre bundles from ''vastus lateralis'' biopsies. Protein and mRNA analysis further examined the metabolic changes relating to regulators of mitochondrial dynamics induced by bed rest. INT was not sufficient in preserving whole body metabolic changes conducive of a decrease in body mass, fat-free mass and exercise capacity within both groups. Mitochondrial respiration, OPA1 and Drp1 protein expression decreased with bed rest, with an increase pDrp1s616. This reduction in mitochondrial respiration was explained through an observed decrease in mitochondrial content (mtDNA:nDNA). Changes in regulators of mitochondrial dynamics indicate an increase in mitochondrial fission driven by a decrease in inner mitochondrial membrane fusion (OPA1) and increased pDrp1s616.inner mitochondrial membrane fusion (OPA1) and increased pDrp1s616.)
Galli 2021 Front Physiol + (It is well established that adult vertebra … It is well established that adult vertebrates acclimatizing to hypoxic environments undergo mitochondrial remodeling to enhance oxygen delivery, maintain ATP, and limit oxidative stress. However, many vertebrates also encounter oxygen deprivation during embryonic development. The effects of developmental hypoxia on mitochondrial function are likely to be more profound, because environmental stress during early life can permanently alter cellular physiology and morphology. To this end, we investigated the long-term effects of developmental hypoxia on mitochondrial function in a species that regularly encounters hypoxia during development-the common snapping turtle (''Chelydra serpentina''). Turtle eggs were incubated in 21 % or 10 % oxygen from 20 % of embryonic development until hatching, and both cohorts were subsequently reared in 21 % oxygen for 8 months. Ventricular mitochondria were isolated, and mitochondrial respiration and reactive oxygen species (ROS) production were measured with a microrespirometer. Compared to normoxic controls, juvenile turtles from hypoxic incubations had lower LEAK respiration, higher P:O ratios, and reduced rates of ROS production. Interestingly, these same attributes occur in adult vertebrates that acclimatize to hypoxia. We speculate that these adjustments might improve mitochondrial hypoxia tolerance, which would be beneficial for turtles during breath-hold diving and overwintering in anoxic environments. and overwintering in anoxic environments.)
Groennebaek 2018 Front Physiol + (It is well established that high-load resi … It is well established that high-load resistance exercise (HLRE) can stimulate myofibrillar accretion. Additionally, recent studies suggest that HLRE can also stimulate mitochondrial biogenesis and respiratory function. However, in several clinical situations, the use of resistance exercise with high loading may not constitute a viable approach. Low-load blood flow restricted resistance exercise (BFRRE) has emerged as a time-effective low-load alternative to stimulate myofibrillar accretion. It is unknown if BFRRE can also stimulate mitochondrial biogenesis and respiratory function. If so, BFRRE could provide a feasible strategy to stimulate muscle metabolic health. To study this, 34 healthy previously untrained individuals (24 ± 3 years) participated in BFRRE, HLRE, or non-exercise control intervention (CON) 3 times per week for 6 weeks. Skeletal muscle biopsies were collected; (1) before and after the 6-week intervention period to assess mitochondrial biogenesis and respiratory function and; (2) during recovery from single-bout exercise to assess myocellular signaling events involved in transcriptional regulation of mitochondrial biogenesis. During the 6-week intervention period, deuterium oxide (D2O) was continuously administered to the participants to label newly synthesized skeletal muscle mitochondrial proteins. Mitochondrial respiratory function was assessed in permeabilized muscle fibers with high-resolution respirometry. Mitochondrial content was assessed with a citrate synthase activity assay. Myocellular signaling was assessed with immunoblotting. Mitochondrial protein synthesis rate was higher with BFRRE (1.19%/day) and HLRE (1.15%/day) compared to CON (0.92%/day) (P < 0.05) but similar between exercise groups. Mitochondrial respiratory function increased to similar degree with both exercise regimens and did not change with CON. For instance, coupled respiration supported by convergent electron flow from complex I and II increased 38% with BFRRE and 24% with HLRE (P < 0.01). Training did not alter citrate synthase activity compared to CON. BFRRE and HLRE elicited similar myocellular signaling responses.These results support recent findings that resistance exercise can stimulate mitochondrial biogenesis and respiratory function to support healthy skeletal muscle and whole-body metabolism. Intriquingly, BFRRE produces similar mitochondrial adaptations at a markedly lower load, which entail great clinical perspective for populations in whom exercise with high loading is untenable.populations in whom exercise with high loading is untenable.)
Chen 2016 Nat Chem Biol + (It is well established that lactate secret … It is well established that lactate secreted by fermenting cells can be oxidized or used as a gluconeogenic substrate by other cells and tissues. It is generally assumed, however, that within the fermenting cell itself, lactate is produced to replenish NAD+ and then is secreted. Here we explore the possibility that cytosolic lactate is metabolized by the mitochondria of fermenting mammalian cells. We found that fermenting HeLa and H460 cells utilize exogenous lactate carbon to synthesize a large percentage of their lipids. Using high-resolution mass spectrometry, we found that both 13C and 2-2H labels from enriched lactate enter the mitochondria. The lactate dehydrogenase (LDH) inhibitor oxamate decreased respiration of isolated mitochondria incubated in lactate, but not of isolated mitochondria incubated in pyruvate. Additionally, transmission electron microscopy (TEM) showed that LDHB localizes to the mitochondria. Taken together, our results demonstrate a link between lactate metabolism and the mitochondria of fermenting mammalian cells.between lactate metabolism and the mitochondria of fermenting mammalian cells.)
Rodriguez 2013 Int J Mol Sci + (It is well established that melatonin exer … It is well established that melatonin exerts antitumoral effects in many cancer types, mostly decreasing cell proliferation at low concentrations. On the other hand, induction of apoptosis by melatonin has been described in the last few years in some particular cancer types. The cytotoxic effect occurs after its administration at high concentrations, and the molecular pathways involved have been only partially determined. Moreover, a synergistic effect has been found in several cancer types when it is administered in combination with chemotherapeutic agents. In the present review, we will summarize published work on the pro-apoptotic effect of melatonin in cancer cells and the reported mechanisms involved in such action. We will also construct a hypothesis on how different cell signaling pathways may relate each other on account for such effect.ate each other on account for such effect.)
Ferraretti 2023 bioRxiv + (It is well established that several ''Homo … It is well established that several ''Homo sapiens'' populations experienced admixture with extinct human species during their evolutionary history. Sometimes, such a gene flow could have played a role in modulating their capability to cope with a variety of selective pressures, thus resulting in archaic adaptive introgression events. A paradigmatic example of this evolutionary mechanism is offered by the EPAS1 gene, whose most frequent haplotype in Himalayan highlanders was proved to reduce their susceptibility to chronic mountain sickness and to be introduced in the gene pool of their ancestors by admixture with Denisovans. In this study, we aimed at further expanding the investigation of the impact of archaic introgression on more complex adaptive responses to hypobaric hypoxia evolved by populations of Tibetan and Sherpa ancestry, which have been plausibly mediated by soft selective sweeps and/or polygenic adaptations rather than by hard selective sweeps. For this purpose, we used a combination of composite-likelihood and gene network-based methods to detect adaptive loci in introgressed chromosomal segments from Tibetan whole genome sequence data and to shortlist those enriched for Denisovan-like derived alleles that participate to the same functional pathways. According to this approach, we identified multiple genes putatively involved in archaic introgression events and that, especially as regards EP300 and NOS2, have plausibly contributed to shape the adaptive modulation of angiogenesis and nitric oxide induction in high-altitude Himalayan peoples. These findings provided unprecedented evidence about the complexity of the adaptive phenotype evolved by these human groups to cope with challenges imposed by hypobaric hypoxia, offering new insights into the tangled interplay of genetic determinants that mediates the physiological adjustments crucial for human adaptation to the high-altitude environment.aptation to the high-altitude environment.)
Joergensen 2015 J Cereb Blood Flow Metab + (It is well known that few weeks of high fa … It is well known that few weeks of high fat (HF) diet may induce metabolic disturbances and mitochondrial dysfunction in skeletal muscle. However, little is known about the effects of long-term HF exposure and effects on brain mitochondria are unknown. Wistar rats were fed either chow (13E% fat) or HF diet (60E% fat) for 1 year. The HF animals developed obesity, dyslipidemia, insulin resistance, and dysfunction of isolated skeletal muscle mitochondria: state 3 and state 4 were 30% to 50% increased (''p''<0.058) with palmitoyl carnitine (PC), while there was no effect with pyruvate as substrate. Adding also succinate in state 3 resulted in a higher substrate control ratio (SCR) with PC, but a lower SCR with pyruvate (''p''<0.05). The P/O2 ratio was lower with PC (''p''<0.004). However, similar tests on isolated brain mitochondria from the same animal showed no changes with the substrates relevant for brain (pyruvate and 3-hydroxybutyrate). Thus, long-term HF diet was associated with obesity, dyslipidemia, insulin resistance, and significantly altered mitochondrial function in skeletal muscle. Yet, brain mitochondria were unaffected. We suggest that the relative isolation of the brain due to the blood-brain barrier may play a role in this strikingly different phenotype of mitochondria from the two tissues of the same animal.notype of mitochondria from the two tissues of the same animal.)
Dos Santos Escaliante 2021 Int J Biol Macromol + (It is well known that the chemical structu … It is well known that the chemical structure of polysaccharides is important to their final biological effect. In this study we investigated the cytotoxic effect of xyloglucan from ''Copaifera langsdorffii'' seeds (XGC) and its complex with oxovanadium (XGC:VO) on hepatocellular carcinoma cells (HepG2). After 72 h of incubation, XGC and XGC:VO (200 μg/mL) reduced cell viability in ~20% and ~40%, respectively. At same conditions, only XGC:VO increased in ~20% the LDH enzyme release. In permeabilized cells, incubated with XGC and XGC:VO (200 μg/mL) for 72 h, NADH oxidase activity was reduced by ~45% with XGC and XGC:VO. The succinate oxidase activity was reduced by ~35% with XGC and ~65% with XGC:VO, evidencing that polysaccharide complexation with vanadium could intensify its effects on the respiratory chain. According to this result, the mitochondrial membrane potential was also reduced by ~9% for XGC and ~30% for XGC:VO, when compared to the control group. Interestingly, ATP levels were more elevated for XGC:VO in respect to XGC, probably due the enhance in glycolytic flux evidenced by increased levels of lactate. These results show that the xyloglucan complexation with oxovanadium (IV/V) potentiates the cytotoxic effect of the native polysaccharide, possibly by impairment of oxidative phosphorylation.y impairment of oxidative phosphorylation.)
Duicu 2013 Can J Physiol Pharmacol + (It is widely recognized that mitochondrial … It is widely recognized that mitochondrial dysfunction is a key component of the multifactorial process of ageing. The effects of age on individual components of mitochondrial function vary across species and strains. In the present study we investigated and compared oxygen consumption, membrane potential (Δψ), the sensitivity of the mitochondrial permeability transition pore (mPTP) to calcium overload and production of reactive oxygen species (ROS) in heart mitochondria isolated from old vs. adult healthy Sprague-Dawley (SD) rats.Respirometry studies and Δψ measurements were performed with the Oxygraph-2k (Oroboros, Austria) equipped with a tetraphenylphosphonium electrode. ROS production and calcium retention capacity (CRC) were measured spectrofluorimetrically.Our results showed an important decline for all bioenergetic parameters for both Complex I and Complex II supported-respiration, a decreased Δ''ψ'' in mitochondria energized with Complex I substrates and an increased mitochondrial ROS production in old vs. the adult group. Mitochondrial sensitivity to Ca2+-induced mtPTP opening was also increased in the old vs. adult animals. Moreover, the protective effect of cyclosporine A on mtPTP opening was significantly reduced in the old group.Healthy ageing is associated with heart mitochondria dysfunction in Sprague Dawley rats.ondria dysfunction in Sprague Dawley rats.)
Baker 2016b Nature + (It may not be sexy, but quality assurance is becoming a crucial part of lab life. © 2016 Macmillan Publishers Limited. All rights reserved )
Chance 1962 Science + (It now appears to be possible to continuou … It now appears to be possible to continuously record changes in intracellular oxidation-reduction levels in terms of the fluorescence of reduced pyridine nucleotide in mitochondria of various tissues and organs in situ. Studies of kidney and brain cortex in the rat show that changes in fluorescence are not measurably affected by the presence of oxyhemoglobin. Nitrogen, sulfide, cyanide, and carbon monoxide cause increases in fluorescence to very nearly the same levels, and the increases are attributed to larger reduction of mitochondrial diphosphopyridine nucleotide. Amytal at a low blood concentration causes increased reduction in the kidney cortex, and at a high blood concentration, in the brain cortex. The qualitative response of the pyridine nucleotide to low oxygen concentrations shows the brain to be more sensitive than the kidney. The first measurable increase in pyridine nucleotide reduction observed on the brain occurs at a concentration of inspired oxygen of 8 percent. Breathing stops when the percentage increase of pyridine nucleotide reduction on the brain reaches about 90; at this point the percentage increase for the kidney is only about 30. This difference corresponds roughly to a tenfold difference in oxygen tension. Half-maximal increase in pyridine nucleotide reduction on the brain occurs at a concentration of inspired oxygen of about 4 percent and corresponds to an intracellular oxygen tension of about 0.2 mm.racellular oxygen tension of about 0.2 mm.)
Robach 2012 Br J Sports Med + (It remains unclear by which mechanism 'liv … It remains unclear by which mechanism 'live high-train low' (LHTL) altitude training increases exercise performance. Haematological and skeletal muscle adaptations have both been proposed. To test the hypotheses that (i) LHTL improves maximal oxygen uptake (VO2max ) and (ii) this improvement is related to hypoxia-induced increases in total haemoglobin mass (Hb(mass)) and not to improved maximal oxidative capacity of skeletal muscle, we determined VO2max before LHTL and after LHTL, before and after the altitude-induced increases in Hb(mass) (measured by carbon-monoxide rebreathing) had been abolished by isovolumic haemodilution. We obtained skeletal muscle biopsies to quantify mitochondrial oxidative capacity and efficiency. Sixteen endurance-trained athletes were assigned (double-blinded, placebo controlled) to ≥16;h/day over 4;weeks to normoxia (placebo, n=6) or normobaric hypoxia equivalent to 3000;m altitude (LHTL, n=10). Four-week LHTL did not increase VO2max , irrespective of treatment (LHTL: 1.5%; placebo: 2.0%). Hb(mass) was slightly increased (4.6%) in 5 (of 10) LHTL subjects but this was not accompanied by a concurrent increase in VO2max . In the subjects demonstrating an increase in Hb(mass), isovolumic haemodilution elicited a 5.8% decrease in VO2max . Cycling efficiency was altered neither with time nor by LHTL. Neither maximal capacity of oxidative phosphorylation nor mitochondrial efficiency was modified by time or LHTL. The present results suggest that LHTL has no positive effect on VO2max in endurance-trained athletes because (i) muscle maximal oxidative capacity is not improved following LHTL and (ii) erythrocyte volume expansion after LHTL, if any, is too small to alter O2 transport.ing LHTL and (ii) erythrocyte volume expansion after LHTL, if any, is too small to alter O2 transport.)
Trewin 2018 Am J Physiol Regul Integr Comp Physiol + (It remains unclear whether high-intensity … It remains unclear whether high-intensity interval exercise (HIIE) elicits distinct molecular responses to traditional endurance exercise relative to the total work performed. We aimed to investigate the influence of exercise intensity on acute perturbations to skeletal muscle mitochondrial function (respiration and reactive oxygen species), metabolic and redox signaling responses. In a randomized, repeated measures crossover design, eight recreationally active individuals (24 ± 5 years; VO2peak 48 ± 11 mL.kg-1.min-1) undertook continuous moderate-intensity (CMIE: 30 min, 50% peak power output [PPO]), high-intensity interval (HIIE: 5x4 min, 75% PPO, work-matched to CMIE), and low-volume sprint interval (SIE: 4x30 s) exercise, ≥7 days apart. Each session included muscle biopsies at baseline, immediately and 3 h post-exercise for high-resolution mitochondrial respirometry (JO2) and H2O2 emission (JH2O2), gene and protein expression analysis. Immediately post-exercise and irrespective of protocol, JO2 increased during complex I+II leak/state-4 respiration but JH2O2 decreased (p<0.05). AMP-activated protein kinase (AMPK) and acetyl co-A carboxylase (ACC) phosphorylation increased ~1.5 and 2.5-fold respectively, while thioredoxin-reductase-1 protein abundance was ~35% lower after CMIE vs. SIE (p<0.05). At 3 hours post-exercise, regardless of protocol, JO2 was lower during both ADP-stimulated state-3 OXPHOS and uncoupled respiration (p<0.05) but JH2O2 trended higher (p<0.08); PPARGC1A mRNA increased ~13-fold, and peroxiredoxin-1 protein decreased ~35%. In conclusion, intermittent exercise performed at high intensities has similar dynamic effects on muscle mitochondrial function compared with endurance exercise, irrespective of whether total workload is matched. This suggests exercise prescription can accommodate individual preferences while generating comparable molecular signals known to promote beneficial metabolic adaptations.irrespective of whether total workload is matched. This suggests exercise prescription can accommodate individual preferences while generating comparable molecular signals known to promote beneficial metabolic adaptations.)
Holloway 2018 Cell Rep + (It remains unknown if mitochondrial bioene … It remains unknown if mitochondrial bioenergetics are altered with aging in humans. We established an ''in vitro'' method to simultaneously determine mitochondrial respiration and H2O2 emission in skeletal muscle tissue across a range of biologically relevant ADP concentrations. Using this approach, we provide evidence that, although the capacity for mitochondrial H2O2 emission is not increased with aging, mitochondrial ADP sensitivity is impaired. This resulted in an increase in mitochondrial H2O2 and the fraction of electron leak to H2O2, in the presence of virtually all ADP concentrations examined. Moreover, although prolonged resistance training in older individuals increased muscle mass, strength, and maximal mitochondrial respiration, exercise training did not alter H2O2 emission rates in the presence of ADP, the fraction of electron leak to H2O2, or the redox state of the muscle. These data establish that a reduction in mitochondrial ADP sensitivity increases mitochondrial H2O2 emission and contributes to age-associated redox stress.muscle. These data establish that a reduction in mitochondrial ADP sensitivity increases mitochondrial H2O2 emission and contributes to age-associated redox stress.)
Cook 2013 J Exp Biol + (It was hypothesised that chronic hypoxia a … It was hypothesised that chronic hypoxia acclimation (preconditioning) would alter the behavioural low-O2 avoidance strategy of fish as a result of both aerobic and anaerobic physiological adaptations. Avoidance and physiological responses of juvenile snapper (''Pagrus auratus'') were therefore investigated following a 6 week period of moderate hypoxia exposure (10.2–12.1 kPa PO2, 21±1°C) and compared with those of normoxic controls (PO2=20–21 kPa, 21±1°C). The critical oxygen pressure (Pcrit) limit of both groups was unchanged at ~7 kPa, as were standard, routine and maximum metabolic rates. However, hypoxia-acclimated fish showed increased tolerances to hypoxia in behavioural choice chambers by avoiding lower PO2 levels (3.3±0.7 vs 5.3±1.1 kPa) without displaying greater perturbations of lactate or glucose. This behavioural change was associated with unexpected physiological adjustments. For example, a decrease in blood O2 carrying capacity was observed after hypoxia acclimation. Also unexpected was an increase in whole-blood P50 following acclimation to low-O2, perhaps facilitating Hb–O2 off-loading to tissues. In addition, cardiac mitochondria measured ''in situ'' using permeabilised fibres showed improved O2 uptake efficiencies. The proportion of the anaerobic enzyme lactate dehydrogenase, at least relative to the aerobic marker enzyme citrate synthase, also increased in heart and skeletal red muscle, indicating enhanced anaerobic potential, or ''in situ'' lactate metabolism, in these tissues. Overall, these data suggest that a prioritization of O2 delivery and O2 utilisation over O2 uptake during long-term hypoxia may convey a significant survival benefit to snapper in terms of behavioural low-O2 tolerance.;2 delivery and O2 utilisation over O2 uptake during long-term hypoxia may convey a significant survival benefit to snapper in terms of behavioural low-O2 tolerance.)
Galina 2013 Abstract MiP2013 + (It was proposed that the alkylating agent … It was proposed that the alkylating agent 3-bromopyruvate (3-BrPA) could act as an antitumor agent in different cell lines of hepatocellular carcinoma mainly by targeting the mitochondrial hexokinase type 2 that is overexpressed in many tumor cells. Several revisions of drug therapy for cancer treatment have taken this as the main mechanism of action. Despite the potent negative effects of 3-BrPA on cell viability of the tumors, the analogue of pyruvate/lactate alkyl is oxidizing, as expected, other enzymes in energy transducing metabolism in tumor cells. However, little attention has been given to these side effects of 3-BrPA on tumor mitochondria, glycolysis and calcium pump SERCA. A dataset of high-resolution respirometry, analysis of flux, recovery of enzyme activities and metabolomics evaluated by our group in human hepatoma HepG2, isolated liver mitochondria and activities measured of calcium transport in sarcoplasmic reticulum vesicles mediated by SERCA, point to different metabolic targets with significant implications for the mechanism of cell death in tumor. Among the enzymes as targets we list the main ones: monocarboxylate transporter (MCT), glyceraldehyde dehydrogenase (GA3PDH); 3-phosphoglycerate kinase (3PGK); succinate dehydrogenase (SDH); pyruvate dehydrogenase (PDH); glutamate dehydrogenase (GDH); malate dehydrogenase (MDH) and SERCA 2a. Interestingly, mt-HK 1 and 2 are not significantly inhibited by 3-BrPA, but on the contrary contribute to depletion of the cytosolic ATP pool of the ATP-consuming path of glycolysis. Importantly, the mt-HK acts by modulating the rate of oxidative phosphorylation putting succinate dehydrogenase in a state of greater reactivity and inhibition by 3-BrPA. Given these observations we postulate that the mitochondrial hexokinase is not the primary molecular target of tumor cells but a potent depletory agent of cellular ATP and modulator of succinate dehydrogenase inhibition in mitochondrial supported respiration and inducer of permeability transition pore formation involved in cell death in tumor cells.ion involved in cell death in tumor cells.)
Chinopoulos 2011 J Neurosci Res + (It was recently shown that, in progressive … It was recently shown that, in progressively depolarizing mitochondria, the F(0) -F(1) ATP synthase and the adenine nucleotide translocase (ANT) may change directionality independently from each other (Chinopoulos et al. [2010] FASEB J. 24:2405). When the membrane potentials at which these two molecular entities reverse directionality, termed reversal potential (Erev), are plotted as a function of matrix ATP/ADP ratio, an area of the plot is bracketed by the Erev_ATPase and the Erev_ANT, which we call "B space". Both reversal potentials are dynamic, in that they depend on the fluctuating values of the participating reactants; however, Erev_ATPase is almost always more negative than Erev_ANT. Here we review the conditions that define the boundaries of the "B space". Emphasis is placed on the role of matrix substrate-level phosphorylation, because during metabolic compromise this mechanism could maintain mitochondrial membrane potential and prevent the influx of cytosolic ATP destined for hydrolysis by the reversed F(0) -F(1) ATP synthase.s by the reversed F(0) -F(1) ATP synthase.)
West 1996 J Appl Physiol + (It would be valuable to have model atmosph … It would be valuable to have model atmospheres that allow barometric pressures (PB) to be predicted at high altitudes. Attempts to do this in the past using the International Civil Aviation Organizations or United States Standard Atmosphere model have brought such models into disrepute because the predicted pressures at high altitudes are usually much too low. However, other model atmospheres have been developed by geophysicists. The critical variable is the change of air temperature with altitude, and, therefore, model atmospheres have been constructed for different latitudes and seasons of the year. These different models give a large range of pressures at a given altitude. For example, the maximum difference of pressure at an altitude of 9 km is from 206 to 248 Torr, i.e., approximately 20%. However, the mean of the model atmospheres for latitude of 15 degrees (in all seasons) and 30 degrees (in the summer) predicts PB at many locations of interest at high altitude very well, with predictions within 1%. The equation is PB (Torr) = exp (6.63268 - 0.1112 h - 0.00149 h2), were h is the altitude in kilometers. The predictions are good because many high mountain sites are within 30 degrees of the equator and also many studies are made during the summer. Other models should be used for latitudes of 45 degrees and above. Model atmospheres have considerable value in predicting PB at high altitude if proper account is take of latitude and season of the year.er account is take of latitude and season of the year.)
Nemeth 2016 FASEB J + (Itaconate is a nonamino organic acid exhib … Itaconate is a nonamino organic acid exhibiting antimicrobial effects. It has been recently identified in cells of macrophage lineage as a product of an enzyme encoded by immunoresponsive gene 1 (Irg1), acting on the citric acid cycle intermediate cis-aconitate. In mitochondria, itaconate can be converted by succinate-coenzyme A (CoA) ligase to itaconyl-CoA at the expense of ATP (or GTP), and is also a weak competitive inhibitor of complex II. Here, we investigated specific bioenergetic effects of increased itaconate production mediated by LPS-induced stimulation of Irg1 in murine bone marrow-derived macrophages (BMDM) and RAW-264.7 cells. In rotenone-treated macrophage cells, stimulation by LPS led to impairment in substrate-level phosphorylation (SLP) of ''in situ'' mitochondria, deduced by a reversal in the directionality of the adenine nucleotide translocase operation. In RAW-264.7 cells, the LPS-induced impairment in SLP was reversed by short-interfering RNA(siRNA)-but not scrambled siRNA-treatment directed against Irg1. LPS dose-dependently inhibited oxygen consumption rates (61-91%) and elevated glycolysis rates (>21%) in BMDM but not RAW-264.7 cells, studied under various metabolic conditions. In isolated mouse liver mitochondria treated with rotenone, itaconate dose-dependently (0.5-2 mM) reversed the operation of adenine nucleotide translocase, implying impairment in SLP, an effect that was partially mimicked by malonate. However, malonate yielded greater ADP-induced depolarizations (3-19%) than itaconate. We postulate that itaconate abolishes SLP due to 1) a "CoA trap" in the form of itaconyl-CoA that negatively affects the upstream supply of succinyl-CoA from the α-ketoglutarate dehydrogenase complex; 2) depletion of ATP (or GTP), which are required for the thioesterification by succinate-CoA ligase; and 3) inhibition of complex II leading to a buildup of succinate which shifts succinate-CoA ligase equilibrium toward ATP (or GTP) utilization. Our results support the notion that Irg1-expressing cells of macrophage lineage lose the capacity of mitochondrial SLP for producing itaconate during mounting of an immune defense.aconate during mounting of an immune defense.)
Belosludtsev 2020 Biochimie + (Itaconic acid (methylene-succinic acid, It … Itaconic acid (methylene-succinic acid, ItA) is an unsaturated dicarboxylic acid that is secreted by mammalian macrophages in response to a pro-inflammatory stimulus and shows an anti-inflammatory/antibacterial effect. Being a mitochondrial metabolite, it exhibits an inhibitory activity on succinate dehydrogenase and subsequently induces mitochondrial dysfunction. The present study has shown that ItA dose-dependently inhibited ADP- and DNP-stimulated (uncoupled) respiration of rat liver mitochondria energized with succinate. This effect of ItA could be related to the suppression of the activity of complex II and the combined activity of complexes II + III of the respiratory chain. At the same time, ItA had no effect on the activity of the dicarboxylate carrier, which catalyzes the transport of succinate across the inner mitochondrial membrane. It was found that 4 mM ItA diminished the rates of ADP- and DNP-stimulated mitochondrial respiration supported by the substrates of complex I glutamate and malate. A study of the effect of ItA on the activity of complexes of the respiratory chain showed that it significantly decreases the activity of complex IV. It was observed that 4 mM ItA inhibited the rate of H2O2 production by mitochondria. At the same time, ItA promoted the opening of the cyclosporin A-sensitive Ca2+-dependent permeability transition pore. The latter was revealed as the decrease in the calcium retention capacity of mitochondria and the stimulation of release of cytochrome c from the organelles. ItA by itself promotes the cytochrome c release from mitochondria. Possible mechanisms of the effect of ItA on mitochondrial function are discussed.sible mechanisms of the effect of ItA on mitochondrial function are discussed.)
Nemeth 2017 Thesis + (Itaconic acid, matrix substrate-level phos … Itaconic acid, matrix substrate-level phosphorylation (SLP) and macrophages represent the main focus of this thesis. From a more general point of view, it is about immune cell specific metabolism.Usually, metabolism is viewed as the function of cells generating a store of energy by catabolism, and to synthesizing macromolecules for cell maintenance and growth through anabolic pathways. However, today we know that there are some disorders, such as diabetes, atherosclerosis, cancer, inflammatory conditions, in which there are obvious dysfunctions in metabolism....re obvious dysfunctions in metabolism. ...)
Reynolds 2016 Am J Physiol Endocrinol Metab + (Iβ-cell insulin secretion is dependent on … Iβ-cell insulin secretion is dependent on proper mitochondrial function. Various studies have clearly shown that the Nr4a family of orphan nuclear receptors is essential for fuel utilization and mitochondrial function in liver, muscle and adipose. We have previously demonstrated that overexpression of Nr4a1 or Nr4a3 is sufficient to induce proliferation of pancreatic β-cells. In this study we examined whether Nr4a expression impacts pancreatic β-cell mitochondrial function. Here we show that β-cell mitochondrial respiration is dependent on the nuclear receptors Nr4a1 and Nr4a3. Mitochondrial respiration in permeabilized cells was significantly decreased in β-cells lacking Nr4a1 or Nr4a3. Furthermore, respiration rates of intact cells deficient for Nr4a1 or Nr4a3 in the presence of 16mM glucose resulted in decreased glucose mediated oxygen consumption. Consistent with this reduction in respiration, a significant decrease in glucose stimulated insulin secretion rates is observed with deletion of Nr4a1 or Nr4a3. Interestingly, the changes in respiration and insulin secretion occur without a reduction in mitochondrial content, suggesting decreased mitochondrial function. We establish that knockdown of Nr4a1 and Nr4a3 results in decreased expression of the mitochondrial dehydrogenase subunits Idh3g and Sdhb. We demonstrate that loss of Nr4a1 and Nr4a3 impedes production of ATP, and ultimately inhibits glucose stimulated insulin secretion. These data demonstrate for the first time that the orphan nuclear receptors Nr4a1 and Nr4a3 are critical for β-cell mitochondrial function and insulin secretion.Copyright © 2016, American Journal of Physiology - Endocrinology and Metabolism.Physiology - Endocrinology and Metabolism.)
JASIS 2017 Chiba JP + (JASIS - Japan Analytical & Scientific Instruments Show, Chiba, Japan)
Weir 2005 N Engl J Med + (JOSEPH PRIESTLEY, ONE OF THE THREE SCIENTI … JOSEPH PRIESTLEY, ONE OF THE THREE SCIENTISTS CREDITED WITH THEdiscovery of oxygen, described the death of mice that were deprived of oxygen. However, hewas also well aware of the toxicity of too much oxygen, stating, “For as a candle burns muchfaster in dephlogisticated [oxygen-enriched] than in common air, so we might live out too fast,and the animal powers be too soon exhausted in this pure kind of air. A moralist, at least, maysay, that the air which nature has provided for us is as good as we deserve.”1In this review we examine the remarkable mechanisms by which different organs detect andrespond to acute changes in oxygen tension. Specialized tissues that sense the local oxygentension include glomus cells of the carotid body, neuroepithelial bodies in the lungs, chromaffincells of the fetal adrenal medulla, and smooth-muscle cells of the resistance pulmonary arteries,fetoplacental arteries, systemic arteries, and the ductus arteriosus. Together, they constitute aspecialized homeostatic oxygen-sensing system. Although all tissues are sensitive to severehypoxia, these specialized tissues respond rapidly to moderate changes in oxygen tensionwithin the physiologic range (roughly 40 to 100 mm Hg in an adult and 20 to 40 mm Hg in afetus) (Fig. 1).t and 20 to 40 mm Hg in a fetus) (Fig. 1).)
Indian Academy of Pediatrics Growth Charts Committee 2015 Indian Pediatr + (JUSTIFICATION: The need to revise Indian A … JUSTIFICATION: The need to revise Indian Academy of Pediatrics (IAP) growth charts for 5- to 18-year-old Indian children and adolescents was felt as India is in nutrition transition and previous IAP charts are based on data which are over two decades old.PROCESS: The Growth Chart Committee was formed by IAP in January 2014 to design revised growth charts. Consultative meeting was held in November 2014 in Mumbai. Studies performed on Indian children's growth, nutritional assessment and anthropometry from upper and middle socioeconomic classes in last decade were identified. Committee contacted 13 study groups; total number of children in the age group of 5 to 18 years were 87022 (54086 boys). Data from fourteen cities (Agartala, Ahmadabad, Chandigarh, Chennai, Delhi, Hyderabad, Kochi, Kolkata, Madurai, Mumbai, Mysore, Pune, Raipur and Surat) in India were collated. Data of children with weight for height Z scores >2 SD were removed from analyses. Data on 33148 children (18170 males, 14978 females) were used to construct growth charts using Cole's LMS method.OBJECTIVE: To construct revised IAP growth charts for 5-18 year old Indian children based on collated national data from published studies performed on apparently healthy children and adolescents in the last 10 years.RECOMMENDATIONS: The IAP growth chart committee recommends these revised growth charts for height, weight and body mass index (BMI) for assessment of growth of 5-18 year old Indian children to replace the previous IAP charts; rest of the recommendations for monitoring height and weight remain as per the IAP guidelines published in 2007. To define overweight and obesity in children from 5-18 years of age, adult equivalent of 23 and 27 cut-offs presented in BMI charts may be used. IAP recommends use of WHO standards for growth assessment of children below 5 years of age. assessment of children below 5 years of age.)

ASMRM & J-mit 2019 Fukuoka JP + (Joint ASMRM and J-mit Conference, Fukuoka, Japan, 2019)

Yamada 2016 J Physiol + (KEY POINTS: Mitochondrial respiration is r … KEY POINTS:Mitochondrial respiration is regulated by multiple elaborate mechanisms. It has been shown that muscle specific O2 binding protein, Myoglobin (Mb), is localized in mitochondria and interacts with respiratory chain complex IV, suggesting that Mb could be a factor that regulates mitochondrial respiration. Here, we demonstrate that muscle mitochondrial respiration is improved by Mb overexpression via up-regulation of complex IV activity in cultured myoblasts; in contrast, suppression of Mb expression induces a decrease in complex IV activity and mitochondrial respiration compared with the overexpression model. The present data are the first to show the biological significance of mitochondrial Mb as a potential modulator of mitochondrial respiratory capacity.ABSTRACT:Mitochondria are important organelles for metabolism, and their respiratory capacity is a primary factor in the regulation of energy expenditure. Deficiencies of cytochrome c oxidase complex IV, which reduces O2 in mitochondria, are linked to several diseases, such as mitochondrial myopathy. Moreover, mitochondrial respiration in skeletal muscle tissue tends to be susceptible to complex IV activity. Recently, we showed that the muscle-specific protein myoglobin (Mb) interacts with complex IV. The precise roles of mitochondrial Mb remain unclear. Here, we demonstrate that Mb facilitates mitochondrial respiratory capacity in skeletal muscles. Although mitochondrial DNA copy numbers were not altered in Mb-overexpressing myotubes, O2 consumption was greater in these myotubes than that in mock cells (Mock vs. Mb-Flag::GFP: state 4, 1.00 ± 0.09 vs. 1.77 ± 0.34; state 3, 1.00 ± 0.29; Mock: 1.60 ± 0.53; complex 2-3-4: 1.00 ± 0.30 vs. 1.50 ± 0.44; complex IV: 1.00 ± 0.14 vs. 1.87 ± 0.27). This improvement in respiratory capacity could be because of the activation of enzymatic activity of respiratory complexes. Moreover, mitochondrial respiration was up-regulated in myoblasts transiently overexpressing Mb; complex IV activity was solely activated in Mb-overexpressing myoblasts, and complex IV activity was decreased in the myoblasts in which Mb expression was suppressed by Mb-siRNA transfection (Mb vector transfected vs. Mb vector, control siRNA transfected vs. Mb vector, Mb siRNA transfected: 0.15 vs. 0.15 vs. 0.06). Therefore, Mb enhances the enzymatic activity of complex IV to ameliorate mitochondrial respiratory capacity, and could play a pivotal role in skeletal muscle metabolism.iratory capacity, and could play a pivotal role in skeletal muscle metabolism.)
Montero 2015 J Physiol + (KEY POINTS: This study assessed the respec … KEY POINTS:This study assessed the respective contributions of haematological and skeletal muscle adaptations to any observed improvement in peak oxygen uptake (VO2 peak ) induced by endurance training (ET). VO2 peak , peak cardiac output (Q̇ peak ), blood volumes and skeletal muscle biopsies were assessed prior (pre) to and after (post) 6 weeks of ET. Following the post-ET assessment, red blood cell volume (RBCV) reverted to the pre-ET level following phlebotomy and VO2 peak and Q̇ peak were determined again. We speculated that the contribution of skeletal muscle adaptations to an ET-induced increase in VO2 peak could be identified when offsetting the ET-induced increase in RBCV. VO2 peak , Q̇ peak , blood volumes, skeletal muscle mitochondrial volume density and capillarization were increased after ET. Following RBCV normalization, VO2 peak and Q̇ peak reverted to pre-ET levels. These results demonstrate the predominant contribution of haematological adaptations to any increase in VO2 peak induced by ET.ABSTRACT:It remains unclear whether improvements in peak oxygen uptake (V̇O2 peak ) following endurance training (ET) are primarily determined by central and/or peripheral adaptations. Herein, we tested the hypothesis that the improvement in V̇O2 peak following 6 weeks of ET is mainly determined by haematological rather than skeletal muscle adaptations. Sixteen untrained healthy male volunteers (age = 25 ± 4 years, V̇O2 peak = 3.5 ± 0.5 l min-1 ) underwent supervised ET (6 weeks, 3-4 sessions per week). V̇O2 peak , peak cardiac output (Q̇ peak ), haemoglobin mass (Hbmass ) and blood volumes were assessed prior to and following ET. Skeletal muscle biopsies were analysed for mitochondrial volume density (MitoVD ), capillarity, fibre types and respiratory capacity (OXPHOS). After the post-ET assessment, red blood cell volume (RBCV) was re-established at the pre-ET level by phlebotomy and V̇O2 peak and Q̇ peak were measured again. We speculated that the contribution of skeletal muscle adaptations to the ET-induced increase in V̇O2 peak would be revealed when controlling for haematological adaptations. V̇O2 peak and Q̇ peak were increased (P < 0.05) following ET (9 ± 8 and 7 ± 6%, respectively) and decreased (P < 0.05) after phlebotomy (-7 ± 7 and -10 ± 7%). RBCV, plasma volume and Hbmass all increased (P < 0.05) after ET (8 ± 4, 4 ± 6 and 6 ± 5%). As for skeletal muscle adaptations, capillary-to-fibre ratio and total MitoVD increased (P < 0.05) following ET (18 ± 16 and 43 ± 30%), but OXPHOS remained unaltered. Through stepwise multiple regression analysis, Q̇ peak , RBCV and Hbmass were found to be independent predictors of V̇O2 peak . In conclusion, the improvement in V̇O2 peak following 6 weeks of ET is primarily attributed to increases in Q̇ peak and oxygen-carrying capacity of blood in untrained healthy young subjects.g 6 weeks of ET is primarily attributed to increases in Q̇ peak and oxygen-carrying capacity of blood in untrained healthy young subjects.)
Airik 2023 Antioxidants (Basel) + (Karyomegalic interstitial nephritis (KIN) … Karyomegalic interstitial nephritis (KIN) is a genetic adult-onset chronic kidney disease (CKD) characterized by genomic instability and mitotic abnormalities in the tubular epithelial cells. KIN is caused by recessive mutations in the FAN1 DNA repair enzyme. However, the endogenous source of DNA damage in FAN1/KIN kidneys has not been identified. Here we show, using FAN1-deficient human renal tubular epithelial cells (hRTECs) and FAN1-null mice as a model of KIN, that FAN1 kidney pathophysiology is triggered by hypersensitivity to endogenous reactive oxygen species (ROS), which cause chronic oxidative and double-strand DNA damage in the kidney tubular epithelial cells, accompanied by an intrinsic failure to repair DNA damage. Furthermore, persistent oxidative stress in FAN1-deficient RTECs and FAN1 kidneys caused mitochondrial deficiencies in oxidative phosphorylation and fatty acid oxidation. The administration of subclinical, low-dose cisplatin increased oxidative stress and aggravated mitochondrial dysfunction in FAN1-deficient kidneys, thereby exacerbating KIN pathophysiology. In contrast, treatment of FAN1 mice with a mitochondria-targeted ROS scavenger, JP4-039, attenuated oxidative stress and accumulation of DNA damage, mitigated tubular injury, and preserved kidney function in cisplatin-treated FAN1-null mice, demonstrating that endogenous oxygen stress is an important source of DNA damage in FAN1-deficient kidneys and a driver of KIN pathogenesis. Our findings indicate that therapeutic modulation of kidney oxidative stress may be a promising avenue to mitigate FAN1/KIN kidney pathophysiology and disease progression in patients.ology and disease progression in patients.)
Frey 2016 Biochim Biophys Acta + (Ketogenic Diet used to treat refractory ep … Ketogenic Diet used to treat refractory epilepsy for almost a century may represent a treatment option for mitochondrial disorders for which effective treatments are still lacking. Mitochondrial complex I deficiencies are involved in a broad spectrum of inherited diseases including Mitochondrial Encephalomyopathy, Lactic Acidosis and Stroke-like episodes syndrome leading to recurrent cerebral insults resembling strokes and associated with a severe complex I deficiency caused by mitochondrial DNA (mtDNA) mutations. The analysis of MELAS neuronal cybrid cells carrying the almost homoplasmic m.3243A>G mutation revealed a metabolic switch towards glycolysis with the production of lactic acid, severe defects in respiratory chain activity and complex I disassembly with an accumulation of assembly intermediates. Metabolites, NADH/NAD+ ratio, mitochondrial enzyme activities, oxygen consumption and BN-PAGE analysis were evaluated in mutant compared to control cells. A severe complex I enzymatic deficiency was identified associated with a major complex I disassembly with an accumulation of assembly intermediates of 400kDa. We showed that Ketone Bodies (KB) exposure for 4weeks associated with glucose deprivation significantly restored complex I stability and activity, increased ATP synthesis and reduced the NADH/NAD+ ratio, a key component of mitochondrial metabolism. In addition, without changing the mutant load, mtDNA copy number was significantly increased with KB, indicating that the absolute amount of wild type mtDNA copy number was higher in treated mutant cells. Therefore KB may constitute an alternative and promising therapy for MELAS syndrome, and could be beneficial for other mitochondrial diseases caused by complex I deficiency.Copyright © 2016 Elsevier B.V. All rights reserved.ex I deficiency. Copyright © 2016 Elsevier B.V. All rights reserved.)
Geffroy 2018 Biochim Biophys Acta + (Ketogenic diet (KD) which combined carbohy … Ketogenic diet (KD) which combined carbohydrate restriction and the addition of ketone bodies has emerged as an alternative metabolic intervention used as an anticonvulsant therapy or to treat different types of neurological or mitochondrial disorders including MELAS syndrome. MELAS syndrome is a severe mitochondrial disease mainly due to the m.3243A > G mitochondrial DNA mutation. The broad success of KD is due to multiple beneficial mechanisms with distinct effects of very low carbohydrates and ketones. To evaluate the metabolic part of carbohydrate restriction, transmitochondrial neuronal-like cybrid cells carrying the m.3243A > G mutation, shown to be associated with a severe complex I deficiency was exposed during 3 weeks to glucose restriction. Mitochondrial enzyme defects were combined with an accumulation of complex I (CI) matrix intermediates in the untreated mutant cells, leading to a drastic reduction in CI driven respiration. The severe reduction of CI was also paralleled in post-mortem brain tissue of a MELAS patient carrying high mutant load. Importantly, lowering significantly glucose concentration in cell culture improved CI assembly with a significant reduction of matrix assembly intermediates and respiration capacities were restored in a sequential manner. In addition, OXPHOS protein expression and mitochondrial DNA copy number were significantly increased in mutant cells exposed to glucose restriction. The accumulation of CI matrix intermediates appeared as a hallmark of MELAS pathophysiology highlighting a critical pathophysiological mechanism involving CI disassembly, which can be alleviated by lowering glucose fuelling and the induction of mitochondrial biogenesis, emphasizing the usefulness of metabolic interventions in MELAS syndrome.ss of metabolic interventions in MELAS syndrome.)
Dilliraj 2022 Nutrients + (Ketone bodies are small compounds derived … Ketone bodies are small compounds derived from fatty acids that behave as an alternative mitochondrial energy source when insulin levels are low, such as during fasting or strenuous exercise. In addition to the metabolic function of ketone bodies, they also have several signaling functions separate from energy production. In this perspective, we review the main current data referring to ketone bodies in correlation with nutrition and metabolic pathways as well as to the signaling functions and the potential impact on clinical conditions. Data were selected following eligibility criteria accordingly to the reviewed topic. We used a set of electronic databases (Medline/PubMed, Scopus, Web of Sciences (WOS), Cochrane Library) for a systematic search until July 2022 using MeSH keywords/terms (i.e., ketone bodies, BHB, acetoacetate, inflammation, antioxidant, etc.). The literature data reported in this review need confirmation with consistent clinical trials that might validate the results obtained in in vitro and in vivo in animal models. However, the data on exogenous ketone consumption and the effect on the ketone bodies' brain uptake and metabolism might spur the research to define the acute and chronic effects of ketone bodies in humans and pursue the possible implication in the prevention and treatment of human diseases. Therefore, additional studies are required to examine the potential systemic and metabolic consequences of ketone bodies.d metabolic consequences of ketone bodies.)
Wojtala 2014 Abstract MiP2014 + (Key mitochondrial energy-providing reactio … Key mitochondrial energy-providing reactions are carried out by the oxidative phosphorylation system (OXPHOS), involving the electron transfer and phosphorylation systems including F1Fo-ATP synthase. The most common OXPHOS disorder in humans is associated with Complex I deficiency, leading to fatal encephalomyopathies of early childhood- Leigh-like syndrome [1]. The growth factor adaptor protein p66Shc has a substantial impact on mitochondrial metabolism through regulation of cellular responses to oxidative stress. A low level of p66Shc protein or its complete ablation protects against numerous age-related disorders and may partially prevent pathologies caused by reactive oxygen species (ROS). On the other hand, a high level of p66Shc phosphorylation is correlated with increased intracellular ROS production [2,3].Organs from NDUFS4-/- mice with Complex I deficiency were used as a model of self-propelling intracellular oxidative stress. The status of the antioxidant defense system, oxidative stress markers and the p66Shc-Ser36 phosphorylation pathway were measured in these tissues. Mass spectrometry analysis was also performed for selected NDUFS4-/- mouse tissues. In our study, mice with defective Complex I were characterized by attenuated intracellular oxidative stress, connected with increased p66Shc phosphorylation. Mass spectrometry revealed aberrations in the level of Complex I proteins and oxidative stress- related proteins, as well as other proteins involved in metabolic processes.ative stress- related proteins, as well as other proteins involved in metabolic processes.)
Ortiz-Jimenez 2019 MethodsX + (Key mitochondrial processes are known to b … Key mitochondrial processes are known to be widely conserved throughout the eukaryotic domain. However, the scarce availability of working materials may restrict the assessment of such mitochondrial activities in several working models. Pollen tube mitochondrial studies represent one example of this, where tests have been often restricted due the physical impossibility of performing experiments with isolated mitochondria in enough quantities. Here we detail a method to measure ''in situ'' mitochondrial respiratory chain activity and calcium transport in tobacco pollen tubes. Digitonin-mediated plasmalemma permeabilization allows efficient assessment of mitochondrial respiration and calcium uptake. This method allows quick, reliable and portable measurements from low to high cellular densities, versus methods requiring intracellular calcium reporters.requiring intracellular calcium reporters.)
Keystone Symposia 2014 + (Keystone Symposia - Mitochondrial Dynamics and Physiology (Q5), Santa Fee, New Mexico, USA [http://www.keystonesymposia.org/index.cfm?e=web.meeting.program&meetingid=1266 Keystone Symposia 2014])
Keystone Symposia 2015 + (Keystone Symposia - Obesity and the Metabolic Syndrome: Mitochondria and Energy Expenditure (X7) Whistler, CA [http://www.keystonesymposia.org/15X7 Keystone Symposia 2015])
Keystone symposium: “Hypoxia: from basic mechanisms to therapeutics” + (Keystone Symposium: “Hypoxia: from basic mechanisms to therapeutics” Dublin, Ireland [http://www.keystonesymposia.org/index.cfm?e=web.Meeting.Program&meetingid=1323 Keystone Symposium: “Hypoxia: from basic mechanisms to therapeutics”])
Kezic 2016 Oxid Med Cell Longev + (Kidney ischemia/reperfusion injury emerges … Kidney ischemia/reperfusion injury emerges in various clinical settings as a great problem complicating the course and outcome. Ischemia/reperfusion injury is still an unsolved puzzle with a great diversity of investigational approaches, putting the focus on oxidative stress and mitochondria. Mitochondria are both sources and targets of ROS. They participate in initiation and progression of kidney ischemia/reperfusion injury linking oxidative stress, inflammation, and cell death. The dependence of kidney proximal tubule cells on oxidative mitochondrial metabolism makes them particularly prone to harmful effects of mitochondrial damage. The administration of antioxidants has been used as a way to prevent and treat kidney ischemia/reperfusion injury for a long time. Recently a new method based on mitochondria-targeted antioxidants has become the focus of interest. Here we review the current status of results achieved in numerous studies investigating these novel compounds in ischemia/reperfusion injury which specifically target mitochondria such as MitoQ, Szeto-Schiller (SS) peptides (Bendavia), SkQ1 and SkQR1, and superoxide dismutase mimics. Based on the favorable results obtained in the studies that have examined myocardial ischemia/reperfusion injury, ongoing clinical trials investigate the efficacy of some novel therapeutics in preventing myocardial infarct. This also implies future strategies in preventing kidney ischemia/reperfusion injury.enting kidney ischemia/reperfusion injury.)
Bugarski 2018 Am J Physiol Renal Physiol + (Kidney proximal tubules (PTs) are densely … Kidney proximal tubules (PTs) are densely packed with mitochondria, and defects in mitochondrial function are implicated in many kidney diseases. However, little is known about intrinsic mitochondrial function within PT cells. Here, using intravital multiphoton microscopy and live slices of mouse kidney cortex, we show that autofluorescence signals provide important functional readouts of redox state and substrate metabolism and that there are striking axial differences in signals along the PT. Mitochondrial NAD(P)H intensity was similar in both PT segment (S)1 and S2 and was sensitive to changes in respiratory chain (RC) redox state, whereas cytosolic NAD(P)H intensity was significantly higher in S2. Mitochondrial NAD(P)H increased in response to lactate and butyrate but decreased in response to glutamine and glutamate. Cytosolic NAD(P)H was sensitive to lactate and pyruvate and decreased dramatically in S2 in response to inhibition of glucose metabolism. Mitochondrial flavoprotein (FP) intensity was markedly higher in S2 than in S1 but was insensitive to changes in RC redox state. Mitochondrial FP signal increased in response to palmitate but decreased in response to glutamine and glutamate. Fluorescence lifetime decays were similar in both S1 and S2, suggesting that intensity differences are explained by differences in abundance of the same molecular species. Expression levels of known fluorescent mitochondrial FPs were higher in S2 than S1. In summary, substantial metabolic information can be obtained in kidney tissue using a label-free live imaging approach, and our findings suggest that metabolism is tailored to the specialized functions of S1 and S2 PT segments.alized functions of S1 and S2 PT segments.)
Shrum 2019 Biomolecules + (Kidneys from deceased donors used for tran … Kidneys from deceased donors used for transplantation are placed in cold storage (CS) solution during the search for a matched recipient. However, CS causes mitochondrial injury, which may exacerbate renal graft dysfunction. Here, we explored whether adding NS11021, an activator of the mitochondrial big-conductance calcium-activated K+ (mitoBK) channel, to CS solution can mitigate CS-induced mitochondrial injury. We used normal rat kidney proximal tubular epithelial (NRK) cells as an ''in vitro'' model of renal cold storage (18 h) and rewarming (2 h) (CS + RW). Western blots detected the pore-forming α subunit of the BK channel in mitochondrial fractions from NRK cells. The fluorescent K+-binding probe, PBFI-AM, revealed that isolated mitochondria from NRK cells exhibited mitoBK-mediated K+ uptake, which was impaired ~70% in NRK cells subjected to CS + RW compared to control NRK cells maintained at 37 °C. Importantly, the addition of 1 M NS11021 to CS solution prevented CS + RW-induced impairment of mitoBK-mediated K+ uptake. The NS11021-treated NRK cells also exhibited less cell death and mitochondrial injury after CS + RW, including mitigated mitochondrial respiratory dysfunction, depolarization, and superoxide production. In summary, these new data show for the first time that mitoBK channels may represent a therapeutic target to prevent renal CS-induced injury.hat mitoBK channels may represent a therapeutic target to prevent renal CS-induced injury.)
Stefan 2022 Abstract Bioblast + (Kinases function as molecular switches for … Kinases function as molecular switches for coordinating spatiotemporal signal transmission. Genomic alterations affect kinase abundance and/or their activities which contribute to the etiology and progression of diseases such as distinct cancers and Parkinson’s disease (PD). Thus, major drug discovery efforts aim to identify lead molecules targeting the clinically relevant kinase entity. The concept of personalized medicine aims to apply the therapeutic agent with the highest efficacy towards a patient-specific target protein mutation. We have recently implemented a cell-based reporter system which fosters the decision-making process for identifying and selecting efficient lead molecules. We have engineered a modular kinase conformation (KinCon) biosensor platform for live-cell analyses of kinase activity states. This biosensor facilitates the recording of kinase activity conformations of the wild-type and the respective mutated kinase upon lead-molecule or approved-drug exposure. First, in proof-of-principle studies we have demonstrated that this technology is suitable for the systematic determination of melanoma drug efficacies using the full-length KinCon reporters for BRAF and MEK which harbor distinct cancer patient mutations (Röck et al., Science Advances 2019, Mayrhofer et al., PNAS 2020, Fleischmann et al., Biomolecules 2021). Second, we have extended KinCon reporters to quantify the activity-relevant formation of multimeric kinase complexes, involving members of the RIPK [inflammation] or CDK [cancer] kinase families. Third, recently we have engineered mitochondria associated biosensors to analyze and categorize PD kinase mutations. Thus, with new KinCon reporters we are setting out to characterize PD causing kinase gain-of-function mutations and to reactivate a PD kinase displaying a collection of loss-of-function mutations, directly in an intact cell setting. Finally, we would like to underline that this precision-medicine-oriented KinCon biosensor concept is not restricted to recordings of kinase drug efficacies/specificities. We have first evidence that such conformation reporter can extended to other (pseudo)enzyme categories.tended to other (pseudo)enzyme categories.)
Klinische Mitochondrienmedizin und Umweltmedizin 2017 Heidelberg DE + (Klinische Mitochondrienmedizin und Umweltmedizin 2017, Heidelberg, Germany.)
Ernster 1981 J Cell Biol + (Known for over a century, mitochondria hav … Known for over a century, mitochondria have become during the last three decades an important subject of research within several disciplines of experimental biology. For the cytologist, they represented the ideal test objects for applying electron microscopy to the exploration of cellular ultrastructure and for the elaboration of tissue-fractionation techniques with the aim of isolating cytoplasmic organelles. For the biochemist, the identification of mitochondria as the site of cell respiration and respiration-linked phosphorylation implied a decisive step towards the resolution and reconstitution of these processes at a molecular level and the elucidation of their relationship to cellular membranes. For the physiologist, mitochondria afforded the first opportunity for an experimental approach to structure-function relationships, in particular those involved in active transport, vectorial metabolism, and metabolic control mechanisms on a subcellular level. And for the molecular biologist, the discovery of mitochondrial DNA and protein synthesis and the study of mitochondrial biogenesis opened up a new chapter of eukaryotic gene expression. The purpose of this review is to give a brief account of these developments by selecting some of the highlights of the long and eventful history of mitochondrial research.ventful history of mitochondrial research.)
MiPNet20.06 IsolationMouseHeart-mt + (Komlodi T, Cardoso LHD, Gnaiger E (2021) … Komlodi T, Cardoso LHD, Gnaiger E (2021) Laboratory protocol: Isolation of mouse heart mitochondria. Mitochondr Physiol Network 20.06(02):1-4. <div style="padding:0px;border: 1px solid #aaaaaa;margin-bottom:0px;margin-right:10px"><div style="font-size:100%;font-weight:bold;padding:0.2em;padding-right: 0.4em;padding-left: 0.4em;background-color:#eeeeee;border-bottom:1px solid #aaaaaa;text-align:left;">[[Image:O2k-support system.jpg|right|150px|link=http://wiki.oroboros.at/index.php/O2k-technical_support_and_open_innovation|O2k-technical support and open innovation]]: <big>Open the '''pdf document''' above.</big></div><div style="background-color:#ffffff;padding-top:0.2em;padding-right: 0.4em;padding-bottom: 0.2em;padding-left: 0.4em;">::::» Current O2k-series: '''[https://www.oroboros.at/index.php/product-category/products/o2k-packages/ NextGen-O2k Series XB and O2k Series J]'''::::» Current software versions DatLab 8.0: [[MitoPedia: DatLab]]::::* ''Further details:'' '''» [[MitoPedia: O2k-Open Support]]'''</div></div>:» Product: [[Oroboros O2k]], [[O2k-Catalogue]]k-Catalogue]])
MiPNet24.10 H2O2 flux analysis + (Komlodi T, Cardoso LHD, Gnaiger E (2021) H … Komlodi T, Cardoso LHD, Gnaiger E (2021) Hydrogen peroxide flux analysis using Amplex UltraRed assay in MiR05-Kit with DatLab 7.4. Mitochondr Physiol Network 24.10(03):1-5. <div style="padding:0px;border: 1px solid #aaaaaa;margin-bottom:0px;margin-right:10px"><div style="font-size:100%;font-weight:bold;padding:0.2em;padding-right: 0.4em;padding-left: 0.4em;background-color:#eeeeee;border-bottom:1px solid #aaaaaa;text-align:left;">[[Image:O2k-support system.jpg|right|150px|link=http://wiki.oroboros.at/index.php/O2k-technical_support_and_open_innovation|O2k-technical support and open innovation]]: <big>Open the '''pdf document''' above.</big></div><div style="background-color:#ffffff;padding-top:0.2em;padding-right: 0.4em;padding-bottom: 0.2em;padding-left: 0.4em;">::::» Current O2k-series: '''[https://www.oroboros.at/index.php/product-category/products/o2k-packages/ NextGen-O2k Series XB and O2k Series J]'''::::» Current software versions DatLab 8.0: [[MitoPedia: DatLab]]::::* ''Further details:'' '''» [[MitoPedia: O2k-Open Support]]'''</div></div>itoPedia: O2k-Open Support]]''' </div> </div>)
MiPNet24.09 Data analysis of mt-membrane potential + (Komlodi T, Cardoso LHD, Gnaiger E (2021) D … Komlodi T, Cardoso LHD, Gnaiger E (2021) Data analysis of mitochondrial membrane potential estimation using various fluorescence dyes. Mitochondr Physiol Network 24.09(03):1-6. <div style="padding:0px;border: 1px solid #aaaaaa;margin-bottom:0px;margin-right:10px"><div style="font-size:100%;font-weight:bold;padding:0.2em;padding-right: 0.4em;padding-left: 0.4em;background-color:#eeeeee;border-bottom:1px solid #aaaaaa;text-align:left;">[[Image:O2k-support system.jpg|right|150px|link=http://wiki.oroboros.at/index.php/O2k-technical_support_and_open_innovation|O2k-technical support and open innovation]]: <big>Open the '''pdf document''' above.</big></div><div style="background-color:#ffffff;padding-top:0.2em;padding-right: 0.4em;padding-bottom: 0.2em;padding-left: 0.4em;">::::» Current O2k-series: '''[https://www.oroboros.at/index.php/product-category/products/o2k-packages/ NextGen-O2k Series XB and O2k Series J]'''::::» Current software versions DatLab 8.0: [[MitoPedia: DatLab]]::::* ''Further details:'' '''» [[MitoPedia: O2k-Open Support]]'''</div></div>:» Product: [[DatLab]], [[Oroboros O2k]], [[Oroboros O2k-Catalogue |O2k-Catalogue]]oboros O2k-Catalogue |O2k-Catalogue]])
MiPNet24.12 NextGen-O2k: Q-Module + (Komlodi T, Cardoso LHD, Gollner M, Merth A, Niedenzu W, Haider M, Doerrier C, Tindle-Solomon L, Schwaninger H, Walter-Vracevic M, Gradl P, Moore AL, Rich P, Gnaiger E (2021) Mitochondr Physiol Network 24.12(04):1-20.)
MiPNet24.08 Safranin Analysis Template + (Komlodi T, Gnaiger E (2020) Excel template … Komlodi T, Gnaiger E (2020) Excel template for safranin data analysis. Mitochondr Physiol Network 24.08(02):1-8. <div style="padding:0px;border: 1px solid #aaaaaa;margin-bottom:0px;margin-right:10px"><div style="font-size:100%;font-weight:bold;padding:0.2em;padding-right: 0.4em;padding-left: 0.4em;background-color:#eeeeee;border-bottom:1px solid #aaaaaa;text-align:left;">[[Image:O2k-support system.jpg|right|150px|link=http://wiki.oroboros.at/index.php/O2k-technical_support_and_open_innovation|O2k-technical support and open innovation]]: <big>Open the '''pdf document''' above.</big></div><div style="background-color:#ffffff;padding-top:0.2em;padding-right: 0.4em;padding-bottom: 0.2em;padding-left: 0.4em;">::::» Current O2k-series: '''[https://www.oroboros.at/index.php/product-category/products/o2k-packages/ NextGen-O2k Series XB and O2k Series J]'''::::» Current software versions DatLab 8.0: [[MitoPedia: DatLab]]::::* ''Further details:'' '''» [[MitoPedia: O2k-Open Support]]'''</div></div>:» Product: [[DatLab]], [[Oroboros O2k]], [[Oroboros O2k-Catalogue |O2k-Catalogue]]oboros O2k-Catalogue |O2k-Catalogue]])
MiPNet24.16 DatLab8.0: CV-Module + (Komlodi T, Niedenzu W, Haider M, Cardoso L … Komlodi T, Niedenzu W, Haider M, Cardoso LHD, Tindle-Solomon L, Gnaiger E (2021) DatLab8.0:Cyclic voltammetry manual. Mitochondr Physiol Network 24.16(03):1-4. <div style="padding:0px;border: 1px solid #aaaaaa;margin-bottom:0px;margin-right:10px"><div style="font-size:100%;font-weight:bold;padding:0.2em;padding-right: 0.4em;padding-left: 0.4em;background-color:#eeeeee;border-bottom:1px solid #aaaaaa;text-align:left;">[[Image:O2k-support system.jpg|right|150px|link=http://wiki.oroboros.at/index.php/O2k-technical_support_and_open_innovation|O2k-technical support and open innovation]]: <big>Open the '''pdf document''' above.</big></div><div style="background-color:#ffffff;padding-top:0.2em;padding-right: 0.4em;padding-bottom: 0.2em;padding-left: 0.4em;">::::» For O2k-series: '''[https://wiki.oroboros.at/index.php/NextGen-O2k NextGen-O2k]'''::::» For software version: [[MitoPedia: DatLab |'''DatLab 8''']]::::* ''Further details:'' '''» [[MitoPedia: O2k-Open Support]]'''</div></div>:>> Product: [[Oroboros O2k]], [[NextGen-O2k]]extGen-O2k]])
MiPNet15.03 O2k-MultiSensor-ISE + (Komlodi T, Schmitt S, Gnaiger E (2021) O2k … Komlodi T, Schmitt S, Gnaiger E (2021) O2k-MultiSensor system with ion selective electrodes (ISE). Mitochondr Physiol Network 15.03(09): 1-21. <div style="padding:0px;border: 1px solid #aaaaaa;margin-bottom:0px;margin-right:10px"><div style="font-size:100%;font-weight:bold;padding:0.2em;padding-right: 0.4em;padding-left: 0.4em;background-color:#eeeeee;border-bottom:1px solid #aaaaaa;text-align:left;">[[Image:O2k-support system.jpg|right|150px|link=http://wiki.oroboros.at/index.php/O2k-technical_support_and_open_innovation|O2k-technical support and open innovation]]: <big>Open the '''pdf document''' above.</big></div><div style="background-color:#ffffff;padding-top:0.2em;padding-right: 0.4em;padding-bottom: 0.2em;padding-left: 0.4em;">::::» Current O2k-series: '''[https://www.oroboros.at/index.php/product-category/products/o2k-packages/ NextGen-O2k Series XB and O2k Series J]'''::::» Current software versions DatLab 8.0: [[MitoPedia: DatLab]]::::* ''Further details:'' '''» [[MitoPedia: O2k-Open Support]]'''</div></div>:» Product: [[O2k-TPP+ ISE-Module]], [[Oroboros O2k-Catalogue]]oboros O2k-Catalogue]])
Murphy 2018 Cell + (Krebs cycle intermediates traditionally li … Krebs cycle intermediates traditionally link to oxidative phosphorylation whilst also making key cell components. It is now clear that some of these metabolites also act as signals. Succinate plays an important role in inflammatory, hypoxic, and metabolic signaling, while itaconate (from another Krebs cycle intermediate, cis-aconitate) has an anti-inflammatory role.-aconitate) has an anti-inflammatory role.)
MiPNet20.13 Safranin mt-membranepotential + (Krumschnabel G, Fasching M, Gnaiger E (201 … Krumschnabel G, Fasching M, Gnaiger E (2019) O2k-FluoRespirometry: HRR and simultaneous determination of mt-membrane potential with [[safranin]] or [[TMRM]]. Mitochondr Physiol Network 20.13(03):1-5. <div style="padding:0px;border: 1px solid #aaaaaa;margin-bottom:0px;margin-right:10px"><div style="font-size:100%;font-weight:bold;padding:0.2em;padding-right: 0.4em;padding-left: 0.4em;background-color:#eeeeee;border-bottom:1px solid #aaaaaa;text-align:left;">[[Image:O2k-support system.jpg|right|150px|link=http://wiki.oroboros.at/index.php/O2k-technical_support_and_open_innovation|O2k-technical support and open innovation]]: <big>Open the '''pdf document''' above.</big></div><div style="background-color:#ffffff;padding-top:0.2em;padding-right: 0.4em;padding-bottom: 0.2em;padding-left: 0.4em;">::::» Current O2k-series: '''[https://www.oroboros.at/index.php/product-category/products/o2k-packages/ NextGen-O2k Series XB and O2k Series J]'''::::» Current software versions DatLab 8.0: [[MitoPedia: DatLab]]::::* ''Further details:'' '''» [[MitoPedia: O2k-Open Support]]'''</div></div>itoPedia: O2k-Open Support]]''' </div> </div>)
MiPNet20.14 AmplexRed H2O2-production + (Krumschnabel G, Fontana-Ayoub M, Fasching … Krumschnabel G, Fontana-Ayoub M, Fasching M, Gnaiger E (2019) O2k-FluoRespirometry: HRR and simultaneous determination of H2O2 production with Amplex UltraRed. Mitochondr Physiol Network 20.14(04):1-6. <div style="padding:0px;border: 1px solid #aaaaaa;margin-bottom:0px;margin-right:10px"><div style="font-size:100%;font-weight:bold;padding:0.2em;padding-right: 0.4em;padding-left: 0.4em;background-color:#eeeeee;border-bottom:1px solid #aaaaaa;text-align:left;">[[Image:O2k-support system.jpg|right|150px|link=http://wiki.oroboros.at/index.php/O2k-technical_support_and_open_innovation|O2k-technical support and open innovation]]: <big>Open the '''pdf document''' above.</big></div><div style="background-color:#ffffff;padding-top:0.2em;padding-right: 0.4em;padding-bottom: 0.2em;padding-left: 0.4em;">::::» Current O2k-series: '''[https://www.oroboros.at/index.php/product-category/products/o2k-packages/ NextGen-O2k Series XB and O2k Series J]'''::::» Current software versions DatLab 8.0: [[MitoPedia: DatLab]]::::* ''Further details:'' '''» [[MitoPedia: O2k-Open Support]]'''</div></div>itoPedia: O2k-Open Support]]''' </div> </div>)
MiPNet21.12 Comparison mt respiration media + (Krumschnabel G, Hiller E, Gnaiger E (2016) … Krumschnabel G, Hiller E, Gnaiger E (2016) O2k-MultiSensor: Mitochondrial respiration media for HRR and simultaneous O2k-Fluorometry. Mitochondr Physiol Network 21.12(01):1-11. <div style="padding:0px;border: 1px solid #aaaaaa;margin-bottom:0px;margin-right:10px"><div style="font-size:100%;font-weight:bold;padding:0.2em;padding-right: 0.4em;padding-left: 0.4em;background-color:#eeeeee;border-bottom:1px solid #aaaaaa;text-align:left;">[[Image:O2k-support system.jpg|right|150px|link=http://wiki.oroboros.at/index.php/O2k-technical_support_and_open_innovation|O2k-technical support and open innovation]]: <big>Open the '''pdf document''' above.</big></div><div style="background-color:#ffffff;padding-top:0.2em;padding-right: 0.4em;padding-bottom: 0.2em;padding-left: 0.4em;">::::» Current O2k-series: '''[https://www.oroboros.at/index.php/product-category/products/o2k-packages/ NextGen-O2k Series XB and O2k Series J]'''::::» Current software versions DatLab 8.0: [[MitoPedia: DatLab]]::::* ''Further details:'' '''» [[MitoPedia: O2k-Open Support]]'''</div></div>itoPedia: O2k-Open Support]]''' </div> </div>)
MiPNet21.14 Reference sample HRR + (Krumschnabel G, Lamberti G, Hiller E, Hans … Krumschnabel G, Lamberti G, Hiller E, Hansl M, Gnaiger E (2016) Development of a reference sample for HRR. Mitochondr Physiol Network 21.14(02):1-10. <div style="padding:0px;border: 1px solid #aaaaaa;margin-bottom:0px;margin-right:10px"><div style="font-size:100%;font-weight:bold;padding:0.2em;padding-right: 0.4em;padding-left: 0.4em;background-color:#eeeeee;border-bottom:1px solid #aaaaaa;text-align:left;">[[Image:O2k-support system.jpg|right|150px|link=http://wiki.oroboros.at/index.php/O2k-technical_support_and_open_innovation|O2k-technical support and open innovation]]: <big>Open the '''pdf document''' above.</big></div><div style="background-color:#ffffff;padding-top:0.2em;padding-right: 0.4em;padding-bottom: 0.2em;padding-left: 0.4em;">::::» Current O2k-series: '''[https://www.oroboros.at/index.php/product-category/products/o2k-packages/ NextGen-O2k Series XB and O2k Series J]'''::::» Current software versions DatLab 8.0: [[MitoPedia: DatLab]]::::* ''Further details:'' '''» [[MitoPedia: O2k-Open Support]]'''</div></div>itoPedia: O2k-Open Support]]''' </div> </div>)
MiPNet06.06 Chemical O2 background + (Kuznetsov AV, Gnaiger E (2010) Oxygraph assay of cytochrome ''c'' oxidase activity: chemical background correction. Mitochondr Physiol Network 06.06(07):1-4. :» Product: O2k-Catalogue: [[O2k-MultiSensor]], [[O2k-Core]], [[O2k-Catalogue]])
Boyle 2015 Abstract MiP2015 + (Kv1.3 is a member of the delayed rectifier … Kv1.3 is a member of the delayed rectifier family of voltage-activated potassium channels and has become a major therapeutic target because of its role in autoimmune diseases, in leukaemia, atherosclerosis and obesity and type 2 diabetes. Kv1.3 is not only expressed on the plasma membrane but also on the inner mitochondrial membrane [1] suggesting that some of its actions might be via modulation of mitochondrial function.This was investigated in HEK293/Kv1.3 cells and human saphenous vein smooth muscle cells (HSVSMCs), using proliferation assays, immunocytochemistry and high resolution respirometry.HEK293/Kv1.3 cells had significantly increased rates of proliferation compared to WT HEK293 cells. PAP-1, a selective, cell permeant Kv1.3 inhibitor, reduced proliferation in both HEK293/Kv1.3 and HSVSMCs. Channel expression in both the plasma membrane and mitochondria was confirmed using mitotracker in conjunction with immunocytochemical detection of Kv1.3. Mitochondrial expression of the channel was confirmed in both cell types. In addition, the functional expression of the Kv1.3 channel in the plasma membrane was confirmed using patch clamp electrophysiology. High resolution respirometry demonstrated that HEK293/Kv1.3 cells were significantly more metabolically active than WT HEK cells with both increased OXPHOS and glycolytic activity.Thus mitochondrial Kv1.3 may contribute to increased mitochondrial respiration. This will be further investigated using additional permeant and impermeant inhibitors of the Kv1.3 channel.mpermeant inhibitors of the Kv1.3 channel.)
Traufeller 2004 Biochim Biophys Acta + (L-Aminocarnitine (L-AC) has been shown to … L-Aminocarnitine (L-AC) has been shown to inhibit carnitine palmitoyltransferases (CPT) in rat muscle and in rat liver. However, there are no reports on interactions of L-AC with CPT II and CPT I of human muscle. Therefore, the aim of the present work was to characterize the inhibition of human muscle CPT I and CPT II by L-AC in muscle mitochondria, skinned fibers and muscle homogenates in comparison to the established action of malonyl-CoA. Both isoenzymes were inhibited by L-AC, but sensitivity was different (CPT I, Kd=3.8 mM L-AC; CPT II, Kd=21.3 μM L-AC). A mixed inhibition type in respect to carnitine was detected (Ki=3.5 μM L-AC). At 0.5 mM L-AC, CPT II was completely inhibited without affection of CPT I. In contrast, CPT I was completely inhibited by 0.4 mM malonyl-CoA (Kd=0.5 μM), whereas CPT II was nearly not affected by this inhibitor. Using these inhibitors in muscle homogenates, activities of CPT II and CPT I were detected to be 38±10% and 63±10% of total, respectively (n=21). In intact mitochondria and different fractions of muscle homogenates after selective solubilization of CPT II by Tween 20, the extent of specific CPT inhibition changed in relation to the accessible isoenzyme pattern. Palmitoyl-carnitine-dependent respiration in skinned fibers was inhibited by high concentrations of L-AC, indicating that the inhibitor can be transported via the acyl-carnitine transporter, too. The combined use of both inhibitors (L-AC and malonyl-CoA) allows the kinetic characterization of CPT I and CPT II in human muscle homogenates. In addition, it has been shown that L-AC can be used for the study of metabolic consequences of CPT II deficiency on function of intact mitochondria.ciency on function of intact mitochondria.)
Pecina 2015 Abstract MiP2015 + (L-asparaginase (ASNase), a key component i … L-asparaginase (ASNase), a key component in the treatment of childhood acute lymphoblastic leukemia (ALL), hydrolyzes plasma asparagine and glutamine and thereby disturbs metabolic homeostasis of leukemic cells. The efﬁcacy of such therapeutic strategy will depend on the capacity of cancer cells to adapt to the metabolic challenge, which could relate to the activation of compensatory metabolic routes. Therefore, we studied the impact of ASNase on the main metabolic pathways in leukemic cells. Treating leukemic cells with ASNase increased fatty-acid oxidation (FAO) and cell respiration and inhibited glycolysis. FAO, together with the decrease in protein translation and pyrimidine synthesis, was positively regulated through inhibition of the RagB-mTORC1 pathway, whereas the effect on glycolysis was RagB-mTORC1 independent. As FAO has been suggested to have a pro-survival function in leukemic cells, we tested its contribution to cell survival following ASNase treatment. Pharmacological inhibition of FAO signiﬁcantly increased the sensitivity of ALL cells to ASNase. Moreover, constitutive activation of the mammalian target of rapamycin pathway increased apoptosis in leukemic cells treated with ASNase but did not increase FAO. Our study uncovers a novel therapeutic option based on the combination of ASNase and FAO inhibitors. combination of ASNase and FAO inhibitors.)
Volska 2013 Abstract MiP2013 + (L-carnitine takes part in the regulation o … L-carnitine takes part in the regulation of cellular energy metabolism. Recently it has been shown that mildronate, an inhibitor of L-carnitine biosynthesis, improves the neurological outcome after ischemic damage of brain tissue [1]. The aim of the present study was to investigate the effects of mildronate treatment on brain mitochondrial function using an in vitro model of anoxia-reoxygenation.Wistar rats were treated daily with mildronate (per os; 100 mg/kg) for 14 days. Control animals received water. The mitochondrial respiration measurements were performed in isolated brain mitochondria with a Clark-type oxygen sensor. OXPHOS capacity was measured using ADP and various substrates to evaluate respiration of all respiratory complexes. In order to investigate anoxia-reoxygenation damage, brain mitochondria were subjected to 5 min anoxia, followed by 5 min reoxygenation. In parallel, isolated mitochondria were treated under the same conditions but without 5 min anoxia to obtain control (normoxic) measurements. Respiratory parameters were determined: LEAK respiration in the absence of ADP (LN); OXPHOS capacity (P); LEAK respiration after phosphorylation of ADP to ATP (LT); respiratory control ratio (P/LT, RCR).Under normoxic conditions, mildronate treatment did not affect LN and P. However, LT was increased by 30%, resulting in a 28% decreased RCR. Anoxia-reoxygenation induced a significant 2.8-fold decrease in P and a 1.6-fold increase LT. These effects of anoxia-reoxygenation resulted in 4-fold reduction of the RCR. The mildronate treatment significantly diminished the anoxia-reoxygenation-induced decrease in P and increase in LT by 20% and 36%, respectively. After anoxia-reoxygenation the RCR was almost 2 times higher in the mildronate treated group compared to controls.These results demonstrate that mildronate treatment induces uncoupling preconditioning-like effect and improves tolerance against anoxia-reoxygenation.es tolerance against anoxia-reoxygenation.)
De Bari 2015 Abstract MiPschool London 2015 + (L-lactate (L-LAC) and D-lactate (D-LAC) ha … L-lactate (L-LAC) and D-lactate (D-LAC) have been often considered waste products of anaerobic glycolysis and methylglyoxal pathway, respectively. Contrarily, mammalian mitochondria have been shown to metabolize both lactate isomers, due to the existence of isomer specific mitochondrial carriers and enzymes [1,2]. Nothing is known on the possible role of lactate isomers in the overall metabolism of cancer cells, in which both lactate isomers are endogenously formed and considered to be exclusively released to the extracellular phase. Then we examined whether and how the mitochondrial metabolism of L-LAC and D-LAC occurs in human cancer cells, as compared to normal cells.At this aim we used human cultured androgen-insensitive, aggressive prostate cancer (PC-3) cells and normal immortalized prostate (PNT1A) cells, used as a control, grown and handled as described in [3]. Isolation of mitochondria from cultured cells and preparation of cell homogenates, mitochondrial membrane-enriched and cell soluble fractions were carried out as in [3,4 and refs therein]. Polarographic measurements of oxygen consumption, fluorimetric detection of mitochondrial membrane potential (ΔΨ) generation and photometric measurements of mitochondrial ATP production by OXPHOS were carried out as in [3,4 and refs therein]. Both L- and D-lactate dehydrogenase activity and protein level were monitored by kinetic and immunological analysis, respectively, as described in [3,4 and refs therein].We found that mitochondria from both prostate cancer and normal cells metabolize both L-LAC and D-LAC [3,4]. Both the isomers can enter mitochondria in a carrier-mediated manner, probably in symport with protons. Moreover, externally added D-LAC causes the efflux of malate from prostate mitochondria, at a higher rate in PC-3 than in PNT1A cells, probably due to the existence of the D-LAC/malate antiporter, already shown in rat liver mitochondria [2,4]. L-LAC and D-LAC are oxidized inside mitochondria by the mitochondrial L-lactate dehydrogenase (mL-LDH) located in the matrix [1,3] and the flavoprotein D-lactate dehydrogenase (D-LDH), associated to the inner face of the inner mitochondrial membrane [2,4], respectively. The mitochondrial metabolism of both lactate isomers was found to be more active in cancer than in normal cells, likely due to the higher mL-LDH and D-LDH expression and activity found in the former. We propose that the mitochondrial metabolism of lactate isomers in prostate cancer cells could account for anaplerosis of Krebs cycle intermediates in the case of L-LAC, and for energy production and export of malate, this ultimately supporting cytosolic NADPH-dependent processes crucial for cell viability and proliferation, in the case of D-LAC.y and proliferation, in the case of D-LAC.)
Garcia-Corzo 2014 Thesis + (La Coenzima (ubiquinona o CoQ) fue aislada por primera vez en 1955 a partir de fraccion insaponificable de mucosa intestinal de caballo y cerdo (Federstein et a., 1955). Dos anos mas tarde, Crane y colbs....)
Geyer 1951 J Biol Chem + (Labeled carbon dioxide and acetoacetate ar … Labeled carbon dioxide and acetoacetate are two of the chief products formed during the incubation of radioactive fatty acids with rat tissue slices (1, 2). The quantitative aspects of the distribution of radiocarbon in these products can be affected by (a) the kind of tissue, (b) the length of the carbon chain of the substrate, and (c) the odd or even character of the substrate carbon chain (1). In addition, it has been shown that the amount of C1402 produced can be altered by a number of inhibitors (3). In the case of malonic acid, it was found that the decrease in total C1402 which resulted was accompanied by an increase in the Cl4 content of the carboxyl group of the acetoacetic acid formed. This finding suggested that the breakdown of fatty acids to the 2-carbon fragment stage did not depend on the operation of the intact tricarboxylic acid cycle, and, furthermore, supported the concept that the 2-carbon fragments formed were capable of following several different metabolic pathways. The nature of the data available, however, made it impossible to deduce whether one or both species of acetic acid radicals (CHSCO- and -CH&O-) were subject to this choice of pathways. Since the degree of asymmetry in the labeling of the acetoacetic acid formed involves the relative numbers of each of these species present (4, 5), information concerning the flexibility of the pathway of each type of fragment can be gained by the simultaneous study of the respired carbon dioxide and acetoacetic acid formed in the presence and absence of various inhibitors. Such studies are reported in the present paper. The experiments involved the incubation of rat liver with various labeled fatty acids in the presence of various inhibitors. Of the latter compounds, malonic acid was studied the most intensively.malonic acid was studied the most intensively.)
Liang 2016 J Biol Chem + (Lactate dehydrogenase (LDH) catalyzes the … Lactate dehydrogenase (LDH) catalyzes the interconversion of pyruvate and lactate, which are critical fuel metabolites of skeletal muscle particularly during exercise. However, the physiological relevance of LDH remains poorly understood. Here we show that Ldhb expression is induced by exercise in human muscle and negatively correlated with changes in intramuscular pH levels, a marker of lactate production, during isometric exercise. We found that the expression of Ldhb is regulated by exercise-induced peroxisome proliferator-activated receptor-g coactivator 1α (PGC-1α). Ldhb gene promoter reporter studies demonstrated that PGC-1α activates Ldhb gene expression through multiple conserved estrogen-related receptor (ERR) and myocyte enhancer factor 2 (MEF2) binding sites. Transgenic mice overexpressing Ldhb in muscle (muscle creatine kinase [MCK]-Ldhb) exhibited increased exercise performance and enhanced oxygen consumption during exercise. MCK-Ldhb muscle was shown to have enhanced mitochondrial enzyme activity and increased mitochondrial gene expression, suggesting an adaptive oxidative muscle transformation. In addition, mitochondrial respiration capacity was increased and lactate production decreased in MCK-Ldhb skeletal myotubes in culture. Together, these results identified a previously unrecognized Ldhb-driven alteration in muscle mitochondrial function and suggested a mechanism for the adaptive metabolic response induced by exercise training.Copyright © 2016, The American Society for Biochemistry and Molecular Biology.ty for Biochemistry and Molecular Biology.)
George 2015 BA Thesis + (Lactate has been considered a “dead-end” w … Lactate has been considered a “dead-end” waste product of anaerobic metabolism. However, research continually demonstrates that lactate serves as an important metabolic fuel for many tissues, including skeletal and cardiac muscles, liver and brain. The intracellular lactate shuttle hypothesis posits that lactate generated in the cytosol is oxidized by mitochondrial lactate dehydrogenase (LDH) of the same cell. The details of the shuttle have not been made entirely clear. It has been proposed that such a shuttle operates similarly to the malate-aspartate shuttle; it has also been proposed that the two shuttles are necessarily interconnected in a lactate-malate-aspartate shuttle. We hypothesized that experimental support for robust mitochondrial lactate oxidation requires detailed attention to methodological detail. More specifically, an optimal malate concentration was expected to elicit maximal lactate oxidation in skeletal muscle mitochondria ''in vitro''. To test this hypothesis, rates of mitochondrial respiratory oxygen flux (JO2) were continuously monitored during titration of increasing concentrations of lactate (5-30 mM) atop 5 mM ADP, 1 mM NAD+ and either 0.5 mM or 4 mM malate in saponin-permeabilized red gastrocnemius muscle fibres from Sprague-Dawley (N = 3) and Wistar rats (N = 3). Net lactate-supported JO2 was significantly greater with 0.5 mM malate (two-way ANOVA with repeated measures; main effect for malate concentration, P = .0156). The results of this study suggest that mitochondrial lactate oxidation may indeed depend on multi-dehydrogenase activity outside of the mitochondrial matrix. These results also highlight malate concentration as an important variable to consider when interpreting ''in vitro'' phenomena in the context of muscle physiology ''in vivo''.vitro'' phenomena in the context of muscle physiology ''in vivo''.)
Jacobs 2013 Am J Physiol Endocrinol Metab + (Lactate is an important intermediate metab … Lactate is an important intermediate metabolite in human bioenergetics and is oxidized in many different tissues including the heart, brain, kidney, adipose tissue, liver and skeletal muscle. The mechanism(s) explaining the metabolism of lactate in these tissues, however, remains unclear. Here, we analyze the ability of skeletal muscle to respire lactate using an in situ mitochondrial preparation that leaves the native tubular reticulum and subcellular interactions of the organelle unaltered. Skeletal muscle biopsies were obtained from the m. vastus lateralis in 16 human subjects. Samples were chemically permeabilized with saponin, which selectively perforates the sarcolemma and facilitates the loss of cytosolic content without altering mitochondrial membranes, structure, and subcellular interactions. High-resolution respirometry was performed on permeabilized muscle biopsy preparations. Using four separate and specific substrate titration protocols the respirometric analysis revealed that mitochondria were capable of oxidizing lactate in the absence of exogenous LDH. The titration of lactate and NAD(+) into the respiration medium stimulated respiration (p ≤ 0.003). The addition of exogenous LDH failed to increase lactate-stimulated respiration (p = 1.0). The results further demonstrate that human skeletal muscle mitochondria cannot directly oxidize lactate within the mitochondrial matrix. Alternately, these data support previous claims that lactate is converted to pyruvate within the mitochondrial intermembrane space with the pyruvate subsequently taken into the mitochondrial matrix where it enters the TCA cycle and is ultimately oxidized. the TCA cycle and is ultimately oxidized.)
Kane 2014 Abstract MiP2014 + (Lactate serves as an important metabolic i … Lactate serves as an important metabolic intermediate for many tissues including skeletal and cardiac muscles, liver and brain. It is thought that a primary purpose of cytosolic lactate production from pyruvate by lactate dehydrogenase (LDH) is to regenerate NAD+ for continued glycolytic ATP production [1]. Considered in isolation, the NAD+ recycling afforded by cytosolic lactate production does not reconcile with the traditional view of aerobic glycolysis in which pyruvate, generated by glycolysis, enters the mitochondria directly for subsequent oxidation in the TCA cycle. The intracellular lactate shuttle hypothesis posits that lactate, generated in the cytosol, is oxidized by mitochondrial LDH of the same cell [2]. The details of the shuttle, however, are not entirely clear. Evidence is presented which supports that in skeletal muscle, extra-matrix LDH is strategically positioned within the cell to functionally interact with mitochondria [3]. A model incorporating mitochondrial lactate oxidation makes sense of aerobic glycolysis by permitting, among other things, cytosolic NAD+ regeneration, locally. However, experimental support requires attention to methodological detail. Important experimental conditions for assessing mitochondrial lactate oxidation in permeabilized fibers are discussed. Proper malate concentration [4] is necessary for robust NAD+-dependent lactate oxidation, suggesting that a functional malate-aspartate shuttle is essential to the assay. The cytochrome ''c'' test, a convenient means of confirming the integrity of the mitochondrial outer membrane [5], may not accurately reflect the integrity of mitochondrial preparations when assessing lactate oxidation. Indeed, parallel experiments in high-resolution respirometry reveal that in permeabilized rat skeletal muscle fibers, exogenous cytochrome ''c'' stimulates respiration with lactate but not with pyruvate as substrate. These findings highlight the importance of optimizing seemingly trivial experimental variables. findings highlight the importance of optimizing seemingly trivial experimental variables.)
Chang 2021 J Fungi (Basel) + (Lactoferricin (Lfcin) is an amphipathic, c … Lactoferricin (Lfcin) is an amphipathic, cationic peptide derived from proteolytic cleavage of the N-lobe of lactoferrin (Lf). Lfcin and its derivatives possess broad-spectrum antibacterial and antifungal activities. However, unlike their antibacterial functions, the modes of action of Lfcin and its derivatives against pathogenic fungi are less well understood. In this study, the mechanisms of LfcinB15, a derivative of bovine Lfcin, against ''Candida albicans'' were, therefore, extensively investigated. LfcinB15 exhibited inhibitory activity against planktonic cells, biofilm cells, and clinical isolates of ''C. albicans'' and non-''albicans Candida'' species. We further demonstrated that LfcinB15 is localized on the cell surface and vacuoles of ''C. albicans'' cells. Moreover, LfcinB15 uses several different methods to kill ''C. albicans'', including disturbing the cell membrane, inducing reactive oxygen species (ROS) generation, and causing mitochondrial dysfunction. Finally, the Hog1 and Mkc1 mitogen-activated protein kinases were both activated in ''C. albicans'' cells in response to LfcinB15. These findings help us to obtain more insight into the complex mechanisms used by LfcinB15 and other Lfcin-derived peptides to fight fungal pathogens.erived peptides to fight fungal pathogens.)
Rubio-Villena 2018 Hum Mol Genet + (Lafora disease (LD) is a fatal form of pro … Lafora disease (LD) is a fatal form of progressive myoclonus epilepsy characterized by the accumulation of insoluble poorly branched glycogen-like inclusions named Lafora bodies (LBs) in the brain and peripheral tissues. In the brain, since its first discovery in 1911, it was assumed that these glycogen inclusions were only present in affected neurons. Mouse models of LD have been obtained recently, and we and others have been able to report the accumulation of glycogen inclusions in the brain of LD animals, what recapitulates the hallmark of the disease. In this work we present evidence indicating that, although in mouse models of LD glycogen inclusions co-localize with neurons, as originally established, most of them co-localize with astrocytic markers such as glial fibrillary acidic protein (GFAP) and glutamine synthase. In addition, we have observed that primary cultures of astrocytes from LD mouse models accumulate higher levels of glycogen than controls. These results suggest that astrocytes may play a crucial role in the pathophysiology of Lafora disease, as the accumulation of glycogen inclusions in these cells may affect their regular functionality leading then to a possible neuronal dysfunction.g then to a possible neuronal dysfunction.)
Ballot 2010 Apoptosis + (Lamellarin D (Lam D), a marine alkaloid, e … Lamellarin D (Lam D), a marine alkaloid, exhibits a potent cytotoxicity against many different tumors. The pro-apoptotic function of Lam D has been attributed to its direct induction of mitochondrial permeability transition (MPT). This study was undertaken to explore the mechanisms through which Lam D promotes changes in mitochondrial function and as a result apoptosis. The use of eight Lam derivatives provides useful structure-apoptosis relationships. We demonstrate that Lam D and structural analogues induce apoptosis of cancer cells by acting directly on mitochondria inducing reduction of mitochondrial membrane potential, swelling and cytochrome c release. Cyclosporin A, a well-known inhibitor of MPT, completely prevents mitochondrial signs of apoptosis. The drug decreases calcium uptake by mitochondria but not by microsomes indicating that Lam D-dependent permeability is specific to mitochondrial membranes. In addition, upon Lam D exposure, a rapid decline of mitochondrial respiration and ATP synthesis occurs in isolated mitochondria as well as in intact cells. Evaluation of the site of action of Lam D on the electron-transport chain revealed that the activity of respiratory chain complex III is reduced by a half. To determine whether Lam D could induce MPT-dependent apoptosis by inhibiting mitochondrial respiration, we generated respiration-deficient cells (rho0) derived from human melanoma cells. In comparison to parental cells, rho0 cells are totally resistant to the induction of MPT-dependent apoptosis by Lam D. Our results indicate that functional mitochondria are required for Lam D-induced apoptosis. Inhibition of mitochondrial respiration is responsible for MPT-dependent apoptosis of cancer cells induced by Lam-D.poptosis of cancer cells induced by Lam-D.)
Serteyn 2014 Bioenergetics + (Laminitis is a common and debilitating dis … Laminitis is a common and debilitating disease affecting horses and ponies. It often leads to the demise of theanimal. Energy deficiency is suspected to entrain the disruption of the hemidesmosomes leading to the failure of thedermal-epidermal interface. The aim of this study was to measure the muscle mitochondrial function by highresolution respirometry. Muscle micro-biopsies were obtained from 11 horses affected by acute metabolic laminitis,6 horses affected by acute laminitis resulting from a systemic inflammation response syndrome and 28 healthyhorses distributed in 2 control groups: 17 horses with a body condition score [BSC, ranging from 0 (emaciated) to 5(obese)] of 2 to 3 and 11 horses with a BSC of 4 to 5. During the acute phase of laminitis, a significant reduction ofthe muscle mitochondrial respiration was observed. The muscle mitochondrial dysfunction occurred independently ofthe etiology (metabolic disorder or systemic inflammation) leading to laminitis. The reduction of the oxidativephosphorylation and of the maximal respiratory capacity (after uncoupling) may induce depletion of the cell’s ATPcontent. If the same mitochondrial alteration occurs in the foot lamina, mitochondria targeting should be consideredfor the future, not only to better understand the physiopathology of the disease but also to maintain and to supportthe mitochondrial function before reaching the « mitochondrial dysfunction threshold » that may lead to the failure ofthe dermal-epidermal interface.failure of the dermal-epidermal interface.)
MiPNet19.14 SOP Hamilton microsyringes + (Laner V, Timón-Gómez A, Baglivo E, Gnaiger … Laner V, Timón-Gómez A, Baglivo E, Gnaiger E (2023) SOP for manual O2k-titrations with Hamilton microsyringes. Mitochondr Physiol Network 19.14(07):1-4. <div style="padding:0px;border: 1px solid #aaaaaa;margin-bottom:0px;margin-right:10px"><div style="font-size:100%;font-weight:bold;padding:0.2em;padding-right: 0.4em;padding-left: 0.4em;background-color:#eeeeee;border-bottom:1px solid #aaaaaa;text-align:left;">[[Image:O2k-support system.jpg|right|150px|link=http://wiki.oroboros.at/index.php/O2k-technical_support_and_open_innovation|O2k-technical support and open innovation]]: <big>Open the '''pdf document''' above.</big></div><div style="background-color:#ffffff;padding-top:0.2em;padding-right: 0.4em;padding-bottom: 0.2em;padding-left: 0.4em;">::::» Current O2k-series: '''[https://www.oroboros.at/index.php/product-category/products/o2k-packages/ NextGen-O2k Series XB and O2k Series J]'''::::» Current software versions DatLab 8.0: [[MitoPedia: DatLab]]::::* ''Further details:'' '''» [[MitoPedia: O2k-Open Support]]'''</div></div>:» Product: [[O2k-Titration Set]], [[OROBOROS O2k-Catalogue | O2k-Catalogue]]OROS O2k-Catalogue | O2k-Catalogue]])
Welker 2013 Comp Biochem Physiol A Mol Integr Physiol + (Large changes in oxygen availability in aq … Large changes in oxygen availability in aquatic environments, ranging from anoxia through to hyperoxia, can lead to corresponding wide variation in the production of reactive oxygen species (ROS) by animals with aquatic respiration. Therefore, animals living in marine, estuarine and freshwater environments have developed efficient antioxidant defenses to minimize oxidative stress and to regulate the cellular actions of ROS. Changes in oxygen levels may lead to bursts of ROS generation that can be particularly harmful. This situation is commonly experienced by aquatic animals during abrupt transitions from periods of hypoxia/anoxia back to oxygenated conditions (e.g. intertidal cycles). The strategies developed differ significantly among aquatic species and are (i) improvement of their endogenous antioxidant system under hyperoxia (that leads to increased ROS formation) or other similar ROS-related stresses, (ii) increase in antioxidant levels when displaying higher metabolic rates, (iii) presence of constitutively high levels of antioxidants, that attenuates oxidative stress derived from fluctuations in oxygen availability, or (iv) increase in the activity of antioxidant enzymes (and/or the levels of their mRNAs) during hypometabolic states associated with anoxia/hypoxia. This enhancement of the antioxidant system - coined over a decade ago as "preparation for oxidative stress" - controls the possible harmful effects of increased ROS formation during hypoxia/reoxygenation. The present article proposes a novel explanation for the biochemical and molecular mechanisms involved in this phenomenon that could be triggered by hypoxia-induced ROS formation. We also discuss the connections among oxygen sensing, oxidative damage and regulation of the endogenous antioxidant defense apparatus in animals adapted to many natural or man-made challenges of the aquatic environment.ade challenges of the aquatic environment.)
Remor 2011 Biochim Biophys Acta + (Large scale clinical trials have demonstra … Large scale clinical trials have demonstrated that an intensive antihyperglycemic treatment in diabetes mellitus (DM) in individuals reduces the incidence of micro- and macrovascular complications, e.g. nephropathy, retinopathy, DM-accelerated atherosclerosis, myocardial infarction, or limb amputations. Here, we investigated the effect of short- and long-term insulin administration on mitochondrial function in peripheral tissues of streptozotocin (STZ)-induced hyperglycemic rats. In addition, the ''in vitro'' effect of methylglyoxal (MG), advanced glycation end products (AGEs) and human diabetic plasma on mitochondrial activity was investigated in skeletal muscle and liver mitochondria and in rat skin primary fibroblasts. Hyperglycemic STZ rats showed tissue-specific patterns of energy deficiency, evidenced by reduced activities of complexes I, II and/or IV after 30 days of hyperglycemia in heart, skeletal muscle and liver; moreover, cardiac tissue was found to be the most sensitive to the diabetic condition, since energy metabolism was impaired after 10 days of the hyperglycemia. Insulin-induced tight glycemic control was effective in protecting against the hyperglycemia-induced inhibition of mitochondrial enzyme activities. Furthermore, the long-term hormone replacement (30 days) also increased these activities in kidney from STZ-treated animals, where the hyperglycemic state did not modify the electron transport activity. Results from ''in vitro'' experiments indicate that mitochondrial impairment could result from oxidative stress-induced accumulation of MG and/or AGEs. Further investigations demonstrated that human plasma AGE accumulation elicits reduced mitochondrial function in skin fibroblast. These data suggest that persistent hyperglycemia results in tissue-specific patterns of energy deficiency and that early and continuous insulin therapy is necessary to maintain proper mitochondrial metabolism. maintain proper mitochondrial metabolism.)
Herledan 2017 Thesis + (Le muscle squelettique est un tissu plasti … Le muscle squelettique est un tissu plastique ayant la capacité d’adapter sa taille suivant les demandes fonctionnelles extérieures. Il peut s’atrophier (perte de volume musculaire), ou s’hypertrophier (gain de volume musculaire) par une augmentation de la synthèse protéique ou par l’intervention des cellules satellites (SC). Les mécanismes moléculaires de réarrangement de la taille des fibres musculaires demeurent encore peu connus. Les cellules souches du muscle adulte, appelées les cellules satellites, sont quiescentes et sont localisées le long des fibres musculaires. Elles sont amenées à s’activer lors d’une lésion, d’une surcharge de travail ou d’une pathologie. Les SC activées (myoblastes), prolifèrent puis se différencient et fusionnent entre elles ou avec les myofibres préexistantes. Ce processus est appelé la myogenèse adulte. D’une part, nous avons étudié l’implication du facteur de transcription SRF dans l’atrophie du muscle squelettique par arrêt d’activité mécanique induite par dénervation. Se basant sur un modèle murin d’inactivation conditionnelle et inductible de SRF dans les fibres musculaires, nous montrons le rôle de SRF dans la régulation de voies cataboliques comme l’autophagie. De plus, nos données suggèrent l’intervention de SRF dans la régulation énergétique mitochondriale via l’activité des complexes de la chaîne respiratoire. D’autre part, un modèle conditionnel et inductible d’inactivation de SRF dans les SC, nous a permis d’évaluer le rôle de SRF dans les SC. Des travaux réalisés dans l’équipe ont montré que la perte de SRF perturbe fortement les processus de régénération musculaire et d’hypertrophie par surcharge de travail, deux situations au cours desquelles les SC sont mobilisées. Au niveau cellulaire nous avons montré que la perte de SRF dans les SC n’altère ni la prolifération, ni l’entrée en différenciation des myoblastes ; cependant elle entraîne un défaut de motilité et de fusion. Se basant sur une analyse transcriptionnelle, l’équipe a identifié plusieurs gènes cibles de SRF susceptibles d’être responsables du défaut de motilité et/ou de fusion, dont l’alpha-actine. Par une approche de diminution de l’expression de gènes par transfection de siRNA dans les myoblastes, nous avons identifié quelques gènes dont la diminution d’expression phénocopie le défaut de motilité et/ou de fusion des SC. Dans cette étude, nous avons retenu les gènes codant pour FHL2 et HIC5. Une approche « gain de fonction », par surexpression d’actine dans les SC dépourvues de SRF, nous permet d’améliorer le phénotype de fusion hétérotypique/asymétrique, suggérant que la restauration seule du cytosquelette d’actine est suffisante pour rétablir ce type de fusion et l’hypertrophie du muscle. Cependant la fusion homotypique/symétrique et la régénération ne sont pas restaurées ; ainsi nous émettons l’hypothèse de l’intervention d’autres acteurs, tels que FHL2 ou HIC5.n d’autres acteurs, tels que FHL2 ou HIC5.)
Yu-Wai-Man 2011 Prog Retin Eye Res + (Leber hereditary optic neuropathy (LHON) a … Leber hereditary optic neuropathy (LHON) and autosomal-dominant optic atrophy (DOA) are the two most common inherited optic neuropathies in the general population. Both disorders share striking pathological similarities, marked by the selective loss of retinal ganglion cells (RGCs) and the early involvement of the papillomacular bundle. Three mitochondrial DNA (mtDNA) point mutations; m.3460G>A, m.11778G>A, and m.14484T>C account for over 90% of LHON cases, and in DOA, the majority of affected families harbour mutations in the OPA1 gene, which codes for a mitochondrial inner membrane protein. Optic nerve degeneration in LHON and DOA is therefore due to disturbed mitochondrial function and a predominantly complex I respiratory chain defect has been identified using both in vitro and in vivo biochemical assays. However, the trigger for RGC loss is much more complex than a simple bioenergetic crisis and other important disease mechanisms have emerged relating to mitochondrial network dynamics, mtDNA maintenance, axonal transport, and the involvement of the cytoskeleton in maintaining a differential mitochondrial gradient at sites such as the lamina cribosa. The downstream consequences of these mitochondrial disturbances are likely to be influenced by the local cellular milieu. The vulnerability of RGCs in LHON and DOA could derive not only from tissue-specific, genetically-determined biological factors, but also from an increased susceptibility to exogenous influences such as light exposure, smoking, and pharmacological agents with putative mitochondrial toxic effects. Our concept of inherited mitochondrial optic neuropathies has evolved over the past decade, with the observation that patients with LHON and DOA can manifest a much broader phenotypic spectrum than pure optic nerve involvement. Interestingly, these phenotypes are sometimes clinically indistinguishable from other neurodegenerative disorders such as Charcot-Marie-Tooth disease, hereditary spastic paraplegia, and multiple sclerosis, where mitochondrial dysfunction is also thought to be an important pathophysiological player. A number of vertebrate and invertebrate disease models has recently been established to circumvent the lack of human tissues, and these have already provided considerable insight by allowing direct RGC experimentation. The ultimate goal is to translate these research advances into clinical practice and new treatment strategies are currently being investigated to improve the visual prognosis for patients with mitochondrial optic neuropathies.for patients with mitochondrial optic neuropathies.)