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2016 Spring PaduaMuscleDays: Muscle Decline in Aging and Neuromuscular Disorders - Mechanisms and Countermeasures, Padua, IT +
2020 PaduaMuscleDays - 30 years of translational research, Vitual Event, 2020 +
24th Kalorimetrietage, Braunschweig, Germany, 2021. +
25<sup>th</sup> Krakow Conference on Endothelium, Krakow, Poland. +
28th Congress of the Polish Physiological Society, Virtual, 2021 +
2nd International Munich ROS Meeting, Munich, Germany, 2018 +
2nd Mitochondria Conference, Lisbon, Portugal, 2023. +
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'''Oroboros distributor training'''. Innsbruck, Austria; 2023 Nov 07-09. +
'''2nd Workshop on Mitochondrial Functional Diagnostics - Diagnostic database''' Innsbruck, Austria, 2023 +
3
36th annual international congress of Czech Nutrition Society, Hradec Kralove, Czech Republic, 2020 +
37th Annual Meeting of the ISHR-ES, Porto, Portugal, 2023 +
'Mitochondria, Metabolism and Energetics': [[Media:MiPNet18.14 IOC85 Mahabaleshwar.pdf|'''38th Mahabaleshwar Seminar''']], [http://www.tifr.res.in/~dbsconf/mito2014/Home.html mito2014], including '''[[MiPNet18.14 | 85th OROBOROS O2k-Workshop]]'''. +
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46th annual congres of the International Society of Oncology and Biomarkers, Athens, Greece, 2019 +
The 4th China Symposium on Neuro-Controlled Metabolism, Hangzhou city, China, 2021 +
4th Global Chinese Symposium & The 8th Symposium for Cross-straits on Free Radical Biology and Medicine 2018 Macao CN +
4th Global Chinese Symposium & The 8th Symposium for Cross-straits, Hong Kong and Macao on Free Radical Biology and Medicine, Macao, China, 2018 +
4th edition Metabolism & Cancer, Virtual, 2021
== Program ==
:::: [https://www.metabolism-cancer.com/program/ here]
== Organizers ==
:::: The list of organizers can be found [https://www.metabolism-cancer.com/under-construction/ here]
== Registration ==
:::: [https://www.metabolism-cancer.com/registration/ Registration and more information]
== Oroboros at MetaboCancer 2021==
:::: [[Gnaiger Erich]]: Oroboros Instruments innovations - NextGen-O2k and Bioenergetics Communications, ''May 28th at 11:25''
=== Booth ===
:::: The Oroboros team is looking forward to welcome you at our Oroboros booth which will be available at this conference.
== Support ==
[[File:Template NextGen-O2k.jpg|right|350px|link=NextGen-O2k]]
[[Category:NextGen-O2k]]
:::: Supported by project NextGen-O2k which has received funding from the European Unionâs Horizon 2020 research and innovation programme under grant agreement No. 859770.
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5th Academic Symposium of Metabolic Biology Branch of Chinese Biophysical Society, Zunyi, China, 2022 +
5th International Mitochondrial Medicine Conference Mitochondrial, Online, 2021 +
5th edition Metabolism & Cancer, Nice, France, 2023
== Venue ==
:::: [https://www.metabolism-cancer.com/?utm_source=altemail&utm_medium=email&utm_campaign=2023-01-04%20METABO%202023%201 How to get there]
== Program ==
:::: Program available [https://www.metabolism-cancer.com/?utm_source=altemail&utm_medium=email&utm_campaign=2023-01-04%20METABO%202023%201 here]
== Organizers ==
:::: The list of organizers can be found [https://www.metabolism-cancer.com/?utm_source=altemail&utm_medium=email&utm_campaign=2023-01-04%20METABO%202023%201 here]
== Registration ==
:::: [https://www.metabolism-cancer.com/?utm_source=altemail&utm_medium=email&utm_campaign=2023-01-04%20METABO%202023%201 Registration and more information] +
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6th Annual Conference of Chinese Society for Neurobiological Control of Metabolism 2024 Quanzhou CN +
6<sup>th</sup> Annual Conference of Chinese Society for Neurobiological Control of Metabolism, Quanzhou, China, 2024 +
6th Biannual Meeting on Mitochondria Apoptosis & Cancer, Prague, Czech Republic, 2019 +
6th EU-Cardioprotection WG Meeting CA16625 on mito and metabolism as targets for cardioprotection., Virtual Event, 2021 +
6th International Conference on Tumor Microenvironment and Cellular Stress: Signaling, Metabolism, Imaging and Therapeutic Targets, Chania, Crete, Greece, 2019 +
6th Research Day, Innsbruck, Austria, 2023 +
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77th Annual Meeting of the Japanese Cancer Association at the Osaka International Convention Center and RIHGA, Osaka, Japan, 2018 +
7th European Phycological Congress, Zagreb, Croatia, 2019 +
7th Molecular Mechanisms of Axon Degeneration Meeting, Loch Lomond, Scotland, Great Britain, 2019 +
7th World Congress on Targeting Microbiota, Krakow, Poland, 2019
== Venue ==
:::: Park Inn by Radisson Krakow Hotel
:::: Ul. Monte Cassino 2 PL
:::: 30337 - Krakow - Poland
:::: [https://www.microbiota-site.com/venue.html More information]
== Organizer ==
:::: [https://www.microbiota-site.com/committee.html Information available here]
== Programme ==
:::: [https://www.microbiota-site.com/images/2019/PDF/Targeting_Microbiota_2019_Agenda_-_V7.pdf Agenda]
== Speakers ==
:::: List of speakers can be found [https://www.microbiota-site.com/microbiota-2019-speakers.html here]
== Registration ==
:::: [https://www.microbiota-site.com/registrations.html Registration and more information] +
8
8th SMRM and Mitochondria-Metabolism Network Meeting, Pune, India, 2020
== General information ==
:::: Flyer available for [https://www.mitoeagle.org/images/b/b2/8th_SMRM_and_Mitochondria-Metabolism_Network_Meeting_Poster.pdf download]
== Venue ==
:::: Indian Institute of Science Education and Research (ISER Pune)
:::: Dr. Homi Bhabha Road
:::: Pashan, Pune 411 008
:::: INDIA
::::[http://www.iiserpune.ac.in/facilities/guesthouse-cum-convention-centre Hotel and Travel]
== Programme ==
:::: [https://indico.tifr.res.in/indico/internalPage.py?pageId=12&confId=7288 here]
== Speakers ==
:::: List of speakers can be found [https://indico.tifr.res.in/indico/internalPage.py?pageId=0&confId=7288 here]
== Organizers ==
:::: The list of organizers can be found [https://indico.tifr.res.in/indico/internalPage.py?pageId=9&confId=7288 here]
== Registration ==
:::: [https://indico.tifr.res.in/indico/internalPage.py?pageId=6&confId=7288 Registration and more information] +
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9th ĂGMBT Annual Meeting & 8th Life Science Meeting, Innsbruck, Austria +
A
46<sup>th</sup> All India Cell Biology Conference, Navi Mumbai, India, 2024 +
AlgaEurope 2018, Amsterdam, Netherlands, 2018 +
z-Scores were devised to provide a transparent but widely-applicable scoring system for participants in proficiency tests for analytical laboratories. The essential idea is to provide an appropriate scaling of the difference between a participantâs result and the âassigned valueâ for the concentration of the analyte. Interpretation of a z-score is straightforward but some aspects need careful attention to avoid misconception. Over time several related scores have been devised to cope with a diversified range of applications. The main types of score have recently been codified in ISO 13528 (2015). +
64<sup>th</sup> Annual International Conference of the Associate of Microbiologists of India, Jhansi, India, 2023 +
'''APS Conference: Physiological Bioenergetics: Mitochondria from Bench to Bedside, Bioenergetics17'''. San Diego CA, USA; 2017 August. +
32nd APS Annual Convention, Chicago, USA, 2020 +
AVRO - Association for Research in Vision and Ophthalmology, Honolulu, Hawaii, USA, 2018 +
Joint ASMRM and J-mit Conference, Fukuoka, Japan, 2019 +
9<sup>th</sup> Conference of the Asian Society of Mitochondrial Research and Medicine and 5<sup>th</sup> Conference of Chinese Society of Mitochondrial Research and Medicine (Chinese-Mit), [http://asmrm2012.csp.escience.cn/dct/page/65540 ASMRM 2012], Bejing CN +
10<sup>th</sup> Conference of the Asian Society of Mitochondrial Research and Medicine - [http://asmrm2013.com/common_files/mess.asp ASMRM 2013], Seoul KR +
12<sup>th</sup> Conference of the Asian Society of Mitochondrial Research and Medicine - [http://www.ig.zju.edu.cn/ASMRM/EN/ ASMRM 2015], Hangzhou CN +
[[File:ASMRM2016.jpg|500px|right]]
'''13<sup>th</sup> Conference of the Asian Society of Mitochondrial Research and Medicine and the 16<sup>th</sup> Conference of the Japanese Society of Mitochondrial Research and Medicine (J-mit). The world of mitochondrial diseases: Their diversity and heterogeneity. Shinagawa JP.''' +
'''14<sup>th</sup>Conference of the Asian Society of Mitochondrial Research and Medicine'''. Xi'an, Shaanxi, China; 2017 September. +
15th Conference of the Asian Society of Mitochondrial Research and Medicine, Busan, South Korea, 2018. +
ASMRM 2020, Singapore, SG, 2021 +
ATSPB 2023, Hall in Tirol, Austria, 2023 +
Endurance exercise on a regular basis induces skeletal and cardiac muscle performance adaptation, lower mean arterial blood pressure and metabolic adaptation in a number of organs [1,2]. The latter has been shown to involve mitochondrial biogenesis. Upon injury when training intensity decreases, as well as in aging, these events tend to reverse [2,3]. The aim of the present study was to investigate whether the level of aerobic performance affects mitochondrial respiration in platelets.
Six male and female athletes were subjected to magnetic resonance imaging (MRI) of the heart and blood sampling within three days following an anterior cruciate ligament (ACL) injury. An initial follow-up was performed at the start of rehabilitation training and a late follow up at eight months following injury. The latter exams also included a maximal incremental exercise test with gas analysis. Platelets were isolated by centrifugation and mitochondrial respiration was analyzed using a substrate-uncoupler-inhibitor-protocol.
The total heart volume (THV) was significantly lower following the period of reduced exercise intensity from the time of injury to initial follow-up (p = 0.042, n = 6). There was no significant difference in THV between initial and late follow-up. The maximal ''V''<sub>O2</sub> uptake showed a trend toward increase from initial to late follow-up (p = 0.086, n = 4). There were, however, no significant differences or any discernable trends in respiratory parameters between the time points studied.
In conclusion, there was no difference in platelet mitochondrial respiration in response to alterations in exercise level in this small pilot study. +
[[Image:MITOEAGLE-logo.jpg|left|100px|link=http://www.mitoglobal.org/index.php/MITOEAGLE|COST Action MITOEAGLE]]
Within a drug discovery program derived from a project for a pharmacological treatment of mitochondrial complex I deficiency, we have developed cell-permeable prodrugs of succinate (NV118) and malonate (NV161) suitable for research use in intact cells. Succinate is an intermediate of the Krebsâ cycle and acts as mitochondrial energy substrate by providing reducing equivalents to complex II (succinate dehydrogenase) of the mitochondrial oxidative phosphorylation pathway. As succinate is converted to malate by complex II, electrons are transferred down the pathway leading to proton pumping and ATP-synthesis. Succinate, as a dicarboxylic acid, is not cell-permeable and for exogenous succinate to enter cells the cell membrane requires permeabilization, using e.g. digitonin or perfringolysin. NV118 allows the researcher to deliver succinate to the cytoplasm without disrupting the plasma membrane. Malonate is a competitive inhibitor of complex II that binds to the active site of succinate dehydrogenase, thus preventing succinate from being metabolized. Like succinate, malonate is a dicarboxylic acid that does not readily permeate through the cell membrane. By using the same prodrug strategy as for NV118, the cell-permeable analogue of malonate, NV161, has been synthesized. NV118 and NV161 are rapidly metabolized, likely by the action of carboxyesterases, releasing succinate and malonate respectively.
Cell-permeable succinate and malonate were tested in a range of human cells and tissues, such as blood cells, fibroblasts, immortalized liver cells and human heart fibers either in the Oroboros O2k-FluoRespirometer (Oroboros Instruments, Innsbruck, Austria) or in the Seahorse Bioscience XFe96 Extracellular Flux Analyser (Seahorse Bioscience, North Billerica, USA). Dose-response curves for both prodrugs were obtained in human complex I inhibited platelets and primary fibroblasts.
NV118 and NV161 dose-dependently support and inhibit succinate-linked mitochondrial respiration in intact human platelets and fibroblasts. NV161 completely inhibits succinate-linked mitochondrial respiration at about ten times lower concentration as compared to malonate. Dimethyl succinate and dimethyl malonate have previously been reported to be cell-permeable, but did not show strong evidence of efficient cell penetration in this study.
We believe that NV118 and NV161 may prove valuable as scientific tools in mitochondrial research, enabling evaluation of complex II in intact cells and tissues. Analogues of both the succinate and malonate series optimized for ''in vivo'' use are simultaneously being developed.
::[http://bioblast.at/images/0/0f/Aasander_Frostner_Poster_MiP2017.pdf '''Poster link''']
[[Image:MITOEAGLE-logo.jpg|left|100px|link=http://www.mitoglobal.org/index.php/MITOEAGLE|COST Action MitoEAGLE]] +
Primary mitochondrial diseases are a heterogeneous group of rare genetic disorders affecting approximately 125 persons per million. Mutations underlying these diseases give rise to biological changes (including decrease in cellular energy production and increase in reactive oxygen species), leading to organ failure, and commonly early morbidity. Mitochondrial diseases often present in early childhood and lead to the development of severe symptoms, with severe fatigue and myopathy being some of the most prevalent and debilitating clinical signs.
There are currently no cures for mitochondrial diseases, nor any approved pharmaceutical treatments for multisystemic disorders.
Current drug development in mitochondrial diseases focuses mainly on modulation of oxidative stress, regulation of the expression of genes involved in metabolic pathways, modulation of coenzymes, induction of mitochondrial biogenesis, and energy replacement.
In this short review, we present the current landscape of mitochondrial disease drug development, focusing on small molecules in clinical trials conducted by industrial sponsors. +
[[File:BEC.png|25px|link=https://doi.org/10.26124/bec:2022-0004]] https://doi.org/10.26124/bec:2022-0004
Primary mitochondrial diseases are a heterogeneous group of rare genetic disorders affecting approximately 125 persons per million. Mutations underlying these diseases give rise to biological changes (including decrease in cellular energy production and increase in reactive oxygen species), leading to organ failure, and commonly early morbidity. Mitochondrial diseases often present in early childhood and lead to the development of severe symptoms, with severe fatigue and myopathy being some of the most prevalent and debilitating clinical signs.
There are currently no cures for mitochondrial diseases, nor any approved pharmaceutical treatments for multisystemic disorders.
Current drug development in mitochondrial diseases focuses mainly on modulation of oxidative stress, regulation of the expression of genes involved in metabolic pathways, modulation of coenzymes, induction of mitochondrial biogenesis, and energy replacement.
In this short review, we present the current landscape of mitochondrial disease drug development, focusing on small molecules in clinical trials conducted by industrial sponsors.<br><br> +
[[Aasander Frostner 2022 Abstract Bioblast]]: Primary mitochondrial diseases are a heterogeneous group of rare genetic disorders affecting approximately 125 persons per million. Mutations underlying these diseases give rise to biological changes (including decrease in energy production and increase in reactive oxygen species), leading to organ failure, and commonly early morbidity. Mitochondrial diseases often present in early childhood and lead to the development of severe symptoms, with severe fatigue and myopathy being some of the most prevalent and debilitating ones.
There is currently no cure for primary mitochondrial diseases, nor any approved pharmaceutical treatments for multisystemic disorders.
Present drug development in mitochondrial diseases focuses mainly on modulation of oxidative stress, regulation of the expression of genes involved in metabolic pathways, modulation of coenzymes, induction of mitochondrial biogenesis, and energy replacement.
In this short review, we present the current landscape of mitochondrial disease drug development, focusing on small molecules in clinical trials conducted by industrial sponsor. +
[[Image:MITOEAGLE-logo.jpg|left|100px|link=http://www.mitoglobal.org/index.php/MITOEAGLE|COST Action MITOEAGLE]]
Altered myocardial metabolism and cardiac inefficiency are hallmarks of the diabetic heart, and may play a central role in the pathogenesis of diabetes related cardiac dysfunction (diabetic cardiomyopathy). Although high levels of fatty acids has been demonstrated to have adverse effects in the normal heart, its effect in the obese/diabetic heart is less clear. In the present study we have examined how an acute fat-load on the heart diet-induced obese (DIO) mice (20 week on a high-fat diet) and age-matched controls (CON) will influence mitochondrial respiration.
We found reduced OXPHOS respiration in isolated mitochondrial from DIO as compared to CON hearts. By subjecting CON hearts to a high fat-load (elevated levels of fatty acids prior to mitochondrial isolation), OXPHOS respiration and RCR (respiratory coupling ratio) were reduced. These changes were not observed in mitochondria from DIO hearts, which may suggest that in diabetes, the heart undergoes adaptation to chronic exposure of elevated circulating fatty acids, which protect these hearts from the adverse effects of an acute fat-load. +
Preprints in science are nothing new. They are well established in the physical sciences, and experiments with preprints in medical sciences date back to the 1990s. When scientists imagine the future of scientific communication, preprints are inevitably an important component. The future, in this case, was slow to arrive but it is definitely here now. A preprint is a version of a scientific article that precedes its publication in a peer-reviewed journal. At one extreme, a preprint may be unedited, never peer-reviewed, or never published in a scholarly journal but simply posted on a preprint archive. The intention, however, is that by posting an article on a preprint archive, the article is freely accessible and will receive comments from the scientific community so that it can be improved before submission to a journal. +
Cancer and Metabolism conference, Cambridge, United Kingdom, 2018 +
Abcam Mitochondria Meeting 2014, London, UK; [http://www.abcam.com/index.html?pageconfig=resource&rid=16185&viapagetrap=mitochondriafeb Abcam Mitochondria Meeting 2014] +
NADPH oxidase (Nox) is emerging as one of the major sources of cellular reactive oxygen species (ROS). While controlled ROS generation by Nox is involved in the redox regulation of physiological cellular processes, excessive ROS production leads to tissue damage [1]. Nox over-reactivity has been shown to mediate the pathogenesis of tissue injury in neurodegenerative disorders [2], ischemia-reperfusion and cardiovascular disorders. Because of the short-lived nature of ROS, it is challenging to assess and monitor ROS levels in biological specimens. Thus, the development of a method to measure NADPH oxidase-derived ROS generation would be a valuable research tool to understand mechanisms relevant to neurodegeneration and tissue injury. Furthermore, this approach might be of relevance for screening of novel Nox inhibitors, which may selectively reduce disease-related Nox-mediated ROS generation without modifying ROS physiological signaling function.
By using the Oroboros Oxygraph-2k, we applied two different protocols for measuring oxygen consumption in parallel with ROS levels in freshly isolated synaptosomes. In parallel with spin trapping EPR spectroscopy, we employed this protocol to delineate the contribution of NADPH oxidase to ROS production in young female and male C57BL6 mice. The first protocol based on using a polarographic high resolution O2k sensor to measure oxygen consumption and a fluorescence-based module to monitor the rate of NADPH-mediated hydrogen peroxide production. Consistent Nox-dependent oxygen consumption was detected in synaptosomes following activation of Nox by 5 mM NADPH (3 doses). In parallel, we also employed a WPI -electrochemical sensor to determine H2O2 in the same sample. Although we didn't detect sex-dependent discrepancy in the rate of hydrogen peroxide production by Nox in isolated synaptosomes, the HRP/Amplex Red system was associated with greater oxygen consumption and higher rates of hydrogen peroxide generation, suggesting that HRP may be inducing Nox-like activity. We verified the Nox activity using spin trapping EPR spectroscopy. Our study revealed that the Oroboros Oxygraph-2k can be successfully used for assessment of Nox activity through the parallel detection of oxygen consumption and the resulting hydrogen peroxide generation. However, we have also found that HRP exhibit NADPH-dependent, oxygen-consuming, and H<sup>2</sup>O<sup>2</sup> -producing activity. Efforts are currently exerted to test other redox-sensitive dyes for the detection of ROS in the absence of HRP.
Disruption of cellular redox homeostasis is implicated in a wide variety of pathologic conditions and aging. A fundamental factor that dictates such balance is the ratio between mitochondria-mediated complete oxygen reduction into water and incomplete reduction into superoxide radical by mitochondria and NADPH oxidase (NOX) enzymatic activity. Here we determined mitochondrial as well as NOX-dependent rates of oxygen consumption in parallel with H<sub>2</sub>O<sub>2</sub> generation in freshly isolated synaptosomes using high-resolution respirometry combined with fluorescence or electrochemical sensory. Our results indicate that, although synaptic mitochondria exhibit substantially higher respiratory activities (8-82 folds greater than NOX oxygen consumption depending on mitochondrial respiratory state), NADPH-dependent oxygen consumption is associated with greater H<sub>2</sub>O<sub>2</sub> production (6-7 folds higher NOX-H<sub>2</sub>O<sub>2</sub>). We also show that, in terms of the consumed oxygen, while synaptic mitochondria âleakedâ 0.71% ± 0.12 H<sub>2</sub>O<sub>2</sub> during NAD<sup>+</sup>-linked resting, 0.21% ± 0.04 during NAD<sup>+</sup>-linked active, and 0.07% ± 0.02 during FAD<sup>+</sup>-linked active respirations, NOX converted 38% ± 13 of O<sub>2</sub> into H<sub>2</sub>O<sub>2</sub>. Our results indicate that NOX rather than mitochondria is the major source of synaptic H<sub>2</sub>O<sub>2</sub>. The present approach may assist in the identification of redox-modulating synaptic factors that underlie a variety of physiological and pathological processes in neurons. +
[[Image:MITOEAGLE-logo.jpg|left|100px|link=http://www.mitoglobal.org/index.php/MITOEAGLE|COST Action MitoEAGLE]]
At the request of the author, this abstract is not made available online. +
[[Image:MITOEAGLE-logo.jpg|left|100px|link=http://www.mitoeagle.org/index.php/MitoEAGLE|COST Action MitoEAGLE]]
At the request of the authors, this abstract is not made available online. +
[[Image:MITOEAGLE-logo.jpg|left|100px|link=http://www.mitoglobal.org/index.php/MITOEAGLE|COST Action MitoEAGLE]] +
Mitochondrial and immune dysfunctions are often implicated in the aetiology of autism spectrum disorder (ASD). Here, we studied for the first time the relationship between ASD severity measures and mitochondrial respiratory rates in freshly isolated platelets as well as the activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) in isolated neutrophils. We also verified the impact of hyperbaric oxygen therapy (HBOT) on mitochondrial and immune functions as well as on ASD severity measures. Blood samples were collected from three age-matched male groups (Control (Norm-N), autistic (Aut-N), and autistic + HBOT (Aut-H); N = 10 per group). Using high resolution respirometry, we found that routine basal respiration, complex I- and complex I + II-dependent oxidative phosphorylation rate were significantly impaired in Aut-N platelets. Similarly, deficits in immune response of neutrophils were evidenced through lower rates of oxygen consumption and reactive oxygen species (ROS) production by phagocytic NOX. ASD-related behavioural outcomes were found to moderately correlate with platelets' mitochondrial bioenergetic parameters as well as with NOX-mediated activity in neutrophils. HBOT was not able to improve mitochondrial dysfunctions or to counteract ASD-related behavioral deficits. Although HBOT improved one measure of the immune response; namely, NOX-mediated superoxide burst, this was not associated with significant changes in trends of recurrent infections between groups. Taken together, our data suggest that ASD-associated mitochondria and immune deficits are detectable in platelets and neutrophils. We also found no evidence that HBOT confers any significant improvement of ASD-associated physiological or behavioural phenotypes. +
Incidents of myocardial infarction and sudden cardiac arrest vary with time of the day, but the mechanism for this effect is not clear. We hypothesized that diurnal changes in the ability of cardiac mitochondria to control calcium homeostasis dictate vulnerability to cardiovascular events.
Here we investigate mitochondrial calcium dynamics, respiratory function, and reactive oxygen species (ROS) production in mouse heart during different phases of wake versus sleep periods.
We assessed time-of-the-day dependence of calcium retention capacity of isolated heart mitochondria from young male C57BL6 mice. Rhythmicity of mitochondrial-dependent oxygen consumption, ROS production and transmembrane potential in homogenates were explored using the Oroboros O2k Station equipped with a fluorescence detection module. Changes in expression of essential clock and calcium dynamics genes/proteins were also determined at sleep versus wake time points.
Our results demonstrate that cardiac mitochondria exhibit higher calcium retention capacity and higher rates of calcium uptake during sleep period. This was associated with higher expression of clock gene Bmal1, lower expression of per2, greater expression of MICU1 gene (mitochondrial calcium uptake 1), and lower expression of the mitochondrial transition pore regulator gene cyclophilin D. Protein levels of mitochondrial calcium uniporter (MCU), MICU2, and sodium/calcium exchanger (NCLX) were also higher at sleep onset relative to wake period. While complex I and II-dependent oxygen utilization and transmembrane potential of cardiac mitochondria were lower during sleep, ROS production was increased presumably due to mitochondrial calcium sequestration.
Taken together, our results indicate that retaining mitochondrial calcium in the heart during sleep dissipates membrane potential, slows respiratory activities, and increases ROS levels, which may contribute to increased vulnerability to cardiac stress during sleep-wake transition. This pronounced daily oscillations in mitochondrial functions pertaining to stress vulnerability may at least in part explain diurnal prevalence of cardiac pathologies.
Lymphangioleiomyomatosis (LAM) is a rare and progressive systemic disease affecting mainly young women of childbearing age. A deterioration in lung function is driven by neoplastic growth of atypical smooth muscle-like LAM cells in the pulmonary interstitial space that leads to cystic lung destruction and spontaneous pneumothoraces. Therapeutic options for preventing disease progression are limited and often end with lung transplantation temporarily delaying an inevitable decline. To identify new therapeutic strategies for this crippling orphan disease, we have performed array based and metabolic molecular analysis on patient-derived cell lines. Our results point to the conclusion that mitochondrial biogenesis and mitochondrial dysfunction in LAM cells provide a novel target for treatment. +
Researchers in the life sciences are posting their work to preprint servers at an unprecedented and increasing rate, sharing papers online before (or instead of) publication in peer-reviewed journals. Though the popularity and practical benefits of preprints are driving policy changes at journals and funding organizations, there is little bibliometric data available to measure trends in their usage. Here, we collected and analyzed data on all 37,648 preprints that were uploaded to bioRxiv.org, the largest biology-focused preprint server, in its first five years. We find that preprints on bioRxiv are being read more than ever before (1.1 million downloads in October 2018 alone) and that the rate of preprints being posted has increased to a recent high of more than 2,100 per month. We also find that two-thirds of bioRxiv preprints posted in 2016 or earlier were later published in peer-reviewed journals, and that the majority of published preprints appeared in a journal less than six months after being posted. We evaluate which journals have published the most preprints, and find that preprints with more downloads are likely to be published in journals with a higher impact factor. Lastly, we developed Rxivist.org, a website for downloading and interacting programmatically with indexed metadata on bioRxiv preprints. +
Obesity is often associated with abnormalities in cardiac morphology and function. This study tested the hypothesis that obesity-related cardiomyopathy is caused by impaired cardiac energetics. In a mouse model of high-fat diet (HFD)-induced obesity, we applied ''in vivo'' cardiac 31P magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) to investigate cardiac energy status and function, respectively. The measurements were complemented by ex vivo determination of oxygen consumption in isolated cardiac mitochondria, the expression of proteins involved in energy metabolism, and markers of oxidative stress and calcium homeostasis. We also assessed whether HFD induced myocardial lipid accumulation using ''in vivo'' 1H MRS, and if this was associated with apoptosis and fibrosis. Twenty weeks of HFD feeding resulted in early stage cardiomyopathy, as indicated by diastolic dysfunction and increased left ventricular mass, without any effects on systolic function. ''In vivo'' cardiac phosphocreatine-to-ATP ratio and ex vivo oxygen consumption in isolated cardiac mitochondria were not reduced after HFD feeding, suggesting that the diastolic dysfunction was not caused by impaired cardiac energetics. HFD feeding promoted mitochondrial adaptations for increased utilization of fatty acids, which was however not sufficient to prevent the accumulation of myocardial lipids and lipid intermediates. Myocardial lipid accumulation was associated with oxidative stress and fibrosis, but not apoptosis. Furthermore, HFD feeding strongly reduced the phosphorylation of phospholamban, a prominent regulator of cardiac calcium homeostasis and contractility. In conclusion, HFD-induced early stage cardiomyopathy in mice is associated with lipotoxicity-associated oxidative stress, fibrosis, and disturbed calcium homeostasis, rather than impaired cardiac energetics. +
Heart failure is associated with altered myocardial substrate metabolism and impaired cardiac energetics. Comorbidities like diabetes may influence the metabolic adaptations during heart failure development. We quantified to what extent changes in substrate preference, lipid accumulation, and energy status predict the longitudinal development of hypertrophy and failure in the non-diabetic and the diabetic heart.
Transverse aortic constriction (TAC) was performed in non-diabetic (''db''/+) and diabetic (''db''/''db'') mice to induce pressure overload. Magnetic resonance imaging, <sup>31</sup>P magnetic resonance spectroscopy (MRS), <sup>1</sup>H MRS, and <sup>18</sup>F-fluorodeoxyglucose-positron emission tomography (PET) were applied to measure cardiac function, energy status, lipid content, and glucose uptake, respectively. ''In vivo'' measurements were complemented with ''ex vivo'' techniques of high-resolution respirometry, proteomics, and western blotting to elucidate the underlying molecular pathways. In non-diabetic mice, TAC induced progressive cardiac hypertrophy and dysfunction, which correlated with increased protein kinase D-1 (PKD1) phosphorylation and increased glucose uptake. These changes in glucose utilization preceded a reduction in cardiac energy status. At baseline, compared with non-diabetic mice, diabetic mice showed normal cardiac function, higher lipid content and mitochondrial capacity for fatty acid oxidation, and lower PKD1 phosphorylation, glucose uptake, and energetics. Interestingly, TAC affected cardiac function only mildly in diabetic mice, which was accompanied by normalization of phosphorylated PKD1, glucose uptake, and cardiac energy status.
The cardiac metabolic adaptations in diabetic mice seem to prevent the heart from failing upon pressure overload, suggesting that restoring the balance between glucose and fatty acid utilization is beneficial for cardiac function. +
[[File:BEC.png|25px|link=https://doi.org/10.26124/bec:2022-0003]] https://doi.org/10.26124/bec:2022-0003
Mitochondrial ailments are diverse and devastating. Defects in mitochondrial DNA or its products lead to a wide range of deficiencies in the mitochondrial electron transfer system and its ensuing energy transformation. Accessory proteins required for the assembly and function of the respiratory complexes are also required for healthy, coupled, and energy-transforming mitochondria. Recently, the protein nucleotide-binding protein-like (NUBPL or IND1) was identified as an iron-sulfur cluster transfer protein specifically for Complex I. Since the presence of multiple iron-sulfur clusters in Complex I is necessary for its activity, deficiency in NUBPL leads to severely dysfunctional mitochondria, with upregulated compensatory Complex II activity. Here we present a short review of the debilitating disease related to NUBPL deficiency.<br> +
[[Stiban 2022 Abstract Bioblast]]: Mitochondrial ailments are diverse and devastating. Defects in mitochondrial DNA or its products lead to wide range of deficiencies in the mitochondrial electron transfer system and its ensuing energy production. Accessory proteins required for the assembly and function of the respiratory complexes are also required for healthy, coupled, and energy-producing mitochondria. Recently, the protein nucleotide binding protein like (NUBPL or IND1) was identified as an iron-sulfur cluster transfer protein specifically for Complex I. Since the presence of multiple iron-sulfur clusters in Complex I is necessary for its activity, deficiency in NUBPL leads to severely dysfunctional mitochondria, with upregulated compensatory Complex II activity. Here we present a short review of the debilitating disease related to NUBPL deficiency. +
St. John's Wort preparations are used for the treatment of mild to moderate depression. They are usually well tolerated but can cause adverse reactions including liver toxicity in rare cases. To date, the mechanism(s) underlying the hepatotoxicity of St. John's Wort extracts are poorly investigated. We studied the hepatocellular toxicity of hypericin and hyperforin as the two main ingredients of St. John's Wort extracts in HepG2 cells and HepaRG cells and compared the effects to citalopram (a synthetic serotonin uptake inhibitor) with a special focus on mitochondrial toxicity and oxidative stress. In HepG2 cells, hypericin was membrane-toxic at 100”M and depleted ATP at 20”M. In HepaRG cells, ATP depletion started at 5”M. In comparison, hyperforin and citalopram were not toxic up to 100”M. In HepG2 cells, hypericin decreased maximal respiration starting at 2”M and mitochondrial ATP formation starting at 10”M but did not affect glycolytic ATP production. Hypericin inhibited the activity of complex I, II and IV of the electron transfer system and caused mitochondrial superoxide accumulation in cells. The protein expression of mitochondrial superoxide dismutase 2 (SOD2) and thioredoxin 2 (TRX2) and total and reduced glutathione decreased in cells exposed to hypericin. Finally, hypericin diminished the mitochondrial DNA copy number and caused cell necrosis but not apoptosis. In conclusion, hypericin, but not hyperforin or citalopram, is a mitochondrial toxicant at low micromolar concentrations. This mechanism may contribute to the hepatotoxicity occasionally observed in susceptible patients treated with St. John's Wort preparations. +
Hypoxic-ischemic events due to intrapartum complications are the second leading cause of neonatal mortality and initiate an acute brain disorder known as hypoxic-ischemic encephalopathy (HIE). In HIE, the brain undergoes primary and secondary mitochondrial energy failure phases, between there is a latent phase where partial neuronal recovery is observed. At neuronal level, the entry of calcium due to hypoxia-ischemia, activates neuronal nitric oxide synthase (nNOS) resulting in the production of nitric oxide (âąNO). This leads to accumulation of reactive oxygen and nitrogen species, causing mitochondrial damage. Mitochondrial dysfunction exacerbates the injury caused by hypoxia. Pharmacological treatments targeting mitochondria or inhibiting âąNO production plays a key role in improving mitochondrial function, consequently, neuroprotection. 2-iminobiotin (2IB) inhibits nNOS and is currently in study as a neuroprotective agent.
The aim of this study is to investigate the effect of hypoxia on the developing brain in a neonatal piglet model and the pharmacological neuroprotection provided by 2IB as a modulator of neuronal âąNO production.
For this purpose, a 24-48-hour-old newborn piglet (''Sus scrofa domestica'') model is used. The animals are anesthetized and placed on mechanical ventilatory support with FiO2 of 0.21 (normoxia). Throughout the experiment, they are continuously monitored using pulse oximetry and regional cerebral near-infrared spectroscopy (NIRS), invasive blood pressure measurement, integrated amplitude electroencephalogram (aEEG), central temperature, and serial blood gasses analysis. Hypoxia is induced by obstructing the endotracheal tube for 4 minutes, repeating this procedure 3 times every 30 minutes. Between each hypoxia, re ventilation with FiO2. 0.21 The administration of 2IB is done immediately after hypoxia (intravenous 0.2 mg/kg of 2IB). After 4 hours, the animal is sacrificed. Brain biopsies are taken to measure mitochondrial function. Mitochondrial respiration is measured in brain biopsies using an Oroboros Oxygraph at 37°C.
At present, this project is under development. Some experimental procedures have been already done. During hypoxia it was observed hemodynamic affectation shown by bradycardia, increased blood pressure, and decreased oxygen saturation and regional cerebral oxygen saturation, recovering between each hypoxia. On the aEEG, a voltage decrease is observed during hypoxia with subsequent recovery. In blood gasses analysis it is observed a sustained increase in lactate without recovery between hypoxia. Regarding mitochondrial function, a decrease in all respiratory indices was observed in the hypoxia group compared to the control group. We observe significant differences on maximum respiration, reserve capacity and non-mitochondrial consumption. Until now we do not have 2IB results.
The distribution and redox state of ubiquinone in rat and human tissues have been investigated. A rapid extraction procedure and direct injection onto HPLC were employed. It was found in model experiments that in postmortem tissue neither oxidation nor reduction of ubiquinone occurs. In rat the highest concentrations of ubiquinone-9 were found in the heart, kidney, and liver (130-200 micrograms/g). In brain, spleen, and intestine one-third and in other tissues 10-20% of the total ubiquinone contained 10 isoprene units. In human tissues ubiquinone-10 was also present at highest concentrations in heart, kidney, and liver (60-110 micrograms/g), and in all tissues 2-5% of the total ubiquinone contained 9 isoprene units. High levels of reduction, 70-100%, could be observed in human tissues, with the exception of brain and lung. The extent of reduction displayed a similar pattern in rat, but was generally lower. +
In the context of skeletal muscle, IL-6 plays a major role in muscle quality. The goal of this project was to study the influence of systemic IL-6 on skeletal muscle mitochondrial physiology, most notably mitochondrial function (respiration and ROS production) and mitochondrial content.
To determine the influence of interleukin-6 (IL-6) on skeletal muscle mitochondria, high-resolution respirometry was performed to simultaneously measure oxygen consumption (JO2) and ROS production in differentiated myotubes incubated with increasing IL-6 (0, 10, 50, 100 ng/mL) for 18 hours in serum free conditions. To evaluate the impact of IL-6 on mitochondrial content we performed western blots on cell lysates from treated cells, measuring proteins of the mitochondrial electron transport chain (ETC) using a cocktail antibody and PGC-1α/PGC-1Ă for mitochondrial biogenesis. To determine the role of mitochondrial ROS production on JO2 and mitochondrial content, we co-treated differentiated myotubes for 18 hours with 50 and 100ng/mL IL-6 and the mitochondrial specific antioxidant, MitoQ and performed respirometry for mitochondrial functional measurements and western blots for mitochondrial content.Statistical significance was evaluated by using a 2-tailed Studentâs t-test and two-way ANOVA. Post hoc all-group analyses were conducted to determine which groups were different when the model was significant.
Mitochondrial functional measurements show increased JO2 and increased ROS production in an IL-6 dose-dependent manner. Targeting mitochondrial ROS production with 0.5”m MitoQ attenuated IL-6 induced increases in JO2 and ROS production. Complexes I and II (CI, CII) of the ETC increased significantly in an IL-6 dose-wise fashion, and co-treatment with MitoQ normalized increases at 100ng/mL Il-6. 100ng/mL IL-6 significantly increased protein expression of PGC-1α and PGC-1Ă. Co-treatment with MitoQ normalized IL-6 induced increase in PGC-1α.
Our data suggest that when treated chronically at a high dose, IL-6 increases mitochondrial respiration, ROS production, and content. Targeting mitochondrial ROS production normalizes these mitochondrial adaptations. The present study provides new insights into mitochondrial physiology in the context of inflammation. Therapeutically targeting mitochondrial ROS production may impact skeletal muscle quality in certain populations.
Interleukin-6 (IL-6) is a pleiotropic cytokine that has been shown to be produced acutely by skeletal muscle in response to exercise, yet chronically elevated with obesity and aging. The mechanisms by which IL-6 influences skeletal muscle mitochondria acutely and chronically are unclear. To better understand the influence of extramyocellular IL-6 on skeletal muscle mitochondrial physiology, we treated differentiated myotubes with exogenous IL-6 to evaluate the dose- and duration-dependent effects of IL-6 on salient aspects of mitochondrial biology and the role of canonical IL-6 signaling in muscle cells. Acute exposure of myotubes to IL-6 increased the mitochondrial reactive oxygen species (mtROS) production and oxygen consumption rates (JO<sub>2</sub>) in a manner that was dependent on activation of the JAK/STAT pathway. Furthermore, STAT3 activation by IL-6 was partly attenuated by MitoQ, a mitochondrial-targeted antioxidant, suggesting that mtROS potentiates STAT3 signaling in skeletal muscle in response to IL-6 exposure. In concert with effects on mitochondrial physiology, acute IL-6 exposure induced several mitochondrial adaptations, consistent with the stress-induced mitochondrial hyperfusion. Exposure of myotubes to chronically elevated IL-6 further increased mtROS with eventual loss of respiratory capacity. These data provide new evidence supporting the interplay between cytokine signaling and mitochondrial physiology in skeletal muscle. +
Hydrogen sulfide (H2S) is the third gasotransmitter described in mammals. These gasotransmitters (H2S, CO, and NO) are small molecules able to diffuse freely across membranes and thus susceptible to reach easily intracellular targets, one of which is the respiratory enzyme cytochrome oxidase subject to complete inhibition by low micromolar concentrations of these gases. However in contrast to NO or CO, H2S can be metabolized by a sulfide quinone reductase feeding the mitochondrial respiratory chain with the hydrogen atoms of sulfide. Sulfide is thus a two-sided molecule: substrate or poison according to the concentration. The aim of this chapter is to present a mean to monitor sulfide oxidation by isolated mitochondria or cells and to summarize how the properties of this amazing couple (mitochondria and sulfide) translate into practical and conceptual consequences. +
Accumulating evidence indicates that adipose tissue inflammation and mitochondrial dysfunction in skeletal muscle are inextricably linked to obesity and insulin resistance. Celastrol, a bioactive compound derived from the root of Tripterygium wilfordii exhibits a number of attributive properties to attenuate metabolic dysfunction in various cellular and animal disease models. However, the underlying therapeutic mechanisms of celastrol in the obesogenic environment "in vivo" remain elusive. Therefore, the current study investigated the metabolic effects of celastrol on insulin sensitivity, inflammatory response in adipose tissue and mitochondrial functions in skeletal muscle of the high fat diet (HFD)-induced obese rats. Our study revealed that celastrol supplementation at 3 mg/kg/day for 8 weeks significantly reduced the final body weight and enhanced insulin sensitivity of the HFD-fed rats. Celastrol noticeably improved insulin-stimulated glucose uptake activity and increased expression of plasma membrane GLUT4 protein in skeletal muscle. Moreover, celastrol-treated HFD-fed rats showed attenuated inflammatory responses via decreased NF-ÎșB activity and diminished mRNA expression responsible for classically activated macrophage (M1) polarization in adipose tissues. Significant improvement of muscle mitochondrial functions and enhanced antioxidant defense machinery via restoration of mitochondrial complexes I + III linked activity were effectively exhibited by celastrol treatment. Mechanistically, celastrol stimulated mitochondrial biogenesis attributed by upregulation of the adenosine monophosphate-activated protein kinase (AMPK) and sirtuin 1 (SIRT1) signaling pathways. Together, these results further demonstrate heretofore the conceivable therapeutic mechanisms of celastrol "in vivo" against HFD-induced obesity mediated through attenuation of inflammatory response in adipose tissue and enhanced mitochondrial functions in skeletal muscle. +
Acclimatization and High Altitude Illness - Facts and Myths, Brixen Dolomites, IT +
Recurrent loss-of-function deletions cause frequent inactivation of tumour suppressor genes but often also involve the collateral deletion of essential genes in chromosomal proximity, engendering dependence on paralogues that maintain similar function. Although these paralogues are attractive anticancer targets, no methodology exists to uncover such collateral lethal genes. Here we report a framework for collateral lethal gene identification via metabolic fluxes, CLIM, and use it to reveal MTHFD2 as a collateral lethal gene in UQCR11-deleted ovarian tumours. We show that MTHFD2 has a non-canonical oxidative function to provide mitochondrial NAD+, and demonstrate the regulation of systemic metabolic activity by the paralogue metabolic pathway maintaining metabolic flux compensation. This UQCR11-MTHFD2 collateral lethality is confirmed in vivo, with MTHFD2 inhibition leading to complete remission of UQCR11-deleted ovarian tumours. Using CLIM's machine learning and genome-scale metabolic flux analysis, we elucidate the broad efficacy of targeting MTHFD2 despite distinct cancer genetic profiles co-occurring with UQCR11 deletion and irrespective of stromal compositions of tumours. +
The structural organization of the mitochondrial respiratory complexes as four big independently moving entities connected by the mobile carriers CoQ and cytochrome ''c'' has been challenged recently. Blue native gel electrophoresis reveals the presence of high-molecular-weight bands containing several respiratory complexes and suggesting an in vivo assembly status of these structures (respirasomes). However, no functional evidence of the activity of supercomplexes as true respirasomes has been provided yet. We have observed that (1) supercomplexes are not formed when one of their component complexes is absent; (2) there is a temporal gap between the formation of the individual complexes and that of the supercomplexes; (3) some putative respirasomes contain CoQ and cytochrome ''c''; (4) isolated respirasomes can transfer electrons from NADH to O<sub>2</sub>, that is, they respire. Therefore, we have demonstrated the existence of a functional respirasome and propose a structural organization model that accommodates these findings. +
Mitochondrial bioenergetic function is a central component of cellular metabolism in health and disease. Mitochondrial oxidative phosphorylation is critical for maintaining energetic homeostasis, and impairment of mitochondrial function underlies the development and progression of metabolic diseases and aging. However, measurement of mitochondrial bioenergetic function can be challenging in human samples due to limitations in the size of the collected sample. Furthermore, the collection of samples from human cohorts is often spread over multiple days and locations, which makes immediate sample processing and bioenergetics analysis challenging. Therefore, sample selection and choice of tests should be carefully considered. Basic research, clinical trials, and mitochondrial disease diagnosis rely primarily on skeletal muscle samples. However, obtaining skeletal muscle biopsies requires an appropriate clinical setting and specialized personnel, making skeletal muscle a less suitable tissue for certain research studies. Circulating white blood cells and platelets offer a promising primary tissue alternative to biopsies for the study of mitochondrial bioenergetics. Recent advances in frozen respirometry protocols combined with the utilization of minimally invasive and non-invasive samples may provide promise for future mitochondrial research studies in humans. Here we review the human samples commonly used for the measurement of mitochondrial bioenergetics with a focus on the advantages and limitations of each sample. +
Current concepts of cellular oxygen-sensing include an isoform of the neutrophil NADPH oxidase, different electron carrier units of the mitochondrial electron transport chain (ETC), heme oxygenase-2 (HO-2), and a subfamily of 2-oxoglutarate dependent dioxygenases termed HIF (hypoxia inducible factor) prolyl hydroxylases (PHDs) and HIF asparagyl hydroxylase FIH-1 (factor-inhibiting HIF). Different oxygen sensitivities, cell-specific distribution and subcellular localization of specific oxygen-sensing cascades involving reactive oxygen species (ROS) as second messengers may help to tailor various adaptive responses according to differences in tissue oxygen availability. Herein, we propose an integrated model for these various oxygen-sensing mechanisms that very efficiently regulate HIF-alpha activity and plasma membrane potassium-channel (PMPC) conductivity. +
Environmental hypoxia (low dissolved oxygen) is a significant threat facing fishes. As fishes require oxygen to efficiently produce ATP, hypoxia can significantly limit aerobic capacity. However, some fishes show respiratory flexibility that rescues aerobic performance, including plasticity in mitochondrial performance. This plasticity may result in increased mitochondrial efficiency (e.g., less proton leak), increased oxygen storage capacity (increased myoglobin), and oxidative capacity (e.g., higher citrate synthase activity) under hypoxia. We acclimated a hypoxia-tolerant fish, red drum (''Sciaenops ocellatus''), to 8-days of constant hypoxia to induce a hypoxic phenotype. Fish were terminally sampled for cardiac and red muscle tissue to quantify oxidative phosphorylation, proton leak, and maximum respiration in tissue from both hypoxia-acclimated and control fish. Tissue was also collected to assess the plasticity of citrate synthase enzyme activity and mRNA expression for select oxygen storage and antioxidant pathway transcripts. We found that mitochondrial respiration rates were not affected by hypoxia exposure in cardiac tissue, though citrate synthase activity and myoglobin expression were higher following hypoxia acclimation. Interestingly, measures of mitochondrial efficiency in red muscle significantly improved in hypoxia-acclimated individuals. Hypoxia-acclimated fish had significantly higher OXPHOS Control Efficiency, OXPHOS Capacity and Coupling Control Ratios (i.e., LEAK/OXPHOS). There was no significant change to citrate synthase activity or myoglobin expression in red muscle. Overall, these results suggest that red muscle mitochondria of hypoxia-acclimated fish more efficiently utilize oxygen, which may explain previous reports in red drum of improved aerobic swimming performance in the absence of improved maximum metabolic rate following hypoxia acclimation. +
OBJECTIVE: To examine the association of gene variants of uncoupling proteins (UCP)-2 and -3 with obesity and gastrointestinal (GI) traits.
METHODS: In 255 overweight or obese adults, the associations of gene variants in UCP-2 (-3474, rs659366) and UCP-3 (rs1626521, rs2075577, rs15763) with body weight (BW) and GI traits were studied. Gene variants were genotyped by TaqManÂź assay. The associations of genotypes with BW and GI traits (gastric emptying, gastric volume, satiety by buffet meal, satiation by nutrient drink test and GI hormones) were assessed using ANOVA corrected for false detection rate (FDR).
RESULTS: A novel UCP-3 gene variant, rs1626521, was identified; it was associated with BW (''P''â=â0.039), waist circumference (''P''â=â0.035), and significantly higher postprandial gastric volume (''P''â=â0.003) and calories ingested at buffet meal (''P''â=â0.006, both significant with FDR). In a subgroup of 11 participants, rs1626521 was also associated with reduced mitochondrial bioenergetics efficiency in skeletal muscle (''P''â=â0.051). In an ''in vitro'' study in HEK293 cells, rs1626521 reduced UCP-3 protein expression (''P''â=â0.049). Associations detected between other genotypes and GI traits were nonsignificant with FDR.
CONCLUSIONS: A newly identified functional variant (rs1626521) in UCP-3 affects postprandial gastric functions and satiety and may contribute to weight gain and alter human mitochondrial function. +
Coenzyme Q (CoQ, or ubiquinone) is a remarkable lipid that plays an essential role in mitochondria as an electron shuttle between complexes I and II of the respiratory chain, and complex III. It is also a cofactor of other dehydrogenases, a modulator of the permeability transition pore and an essential antioxidant. CoQ is synthesized in mitochondria by a set of at least 12 proteins that form a multiprotein complex. The exact composition of this complex is still unclear. Most of the genes involved in CoQ biosynthesis (COQ genes) have been studied in yeast and have mammalian orthologues. Some of them encode enzymes involved in the modification of the quinone ring of CoQ, but for others the precise function is unknown. Two genes appear to have a regulatory role: COQ8 (and its human counterparts ADCK3 and ADCK4) encodes a putative kinase, while PTC7 encodes a phosphatase required for the activation of Coq7. Mutations in human COQ genes cause primary CoQ<sub>10</sub> deficiency, a clinically heterogeneous mitochondrial disorder with onset from birth to the seventh decade, and with clinical manifestation ranging from fatal multisystem disorders, to isolated encephalopathy or nephropathy. The pathogenesis of CoQ<sub>10</sub> deficiency involves deficient ATP production and excessive ROS formation, but possibly other aspects of CoQ<sub>10</sub> function are implicated. CoQ<sub>10</sub> deficiency is unique among mitochondrial disorders since an effective treatment is available. Many patients respond to oral CoQ<sub>10</sub> supplementation. Nevertheless, treatment is still problematic because of the low bioavailability of the compound, and novel pharmacological approaches are currently being investigated. +
[[File:Dario.JPG|right|200px|Dario Acuna-Castroviejo]]
The first relationship between melatonin and mitochondria came from histological studies showing changes in mitochondrial density and morphology after pinealectomy or melatonin administration to experimental animals. After the discovery of the antioxidant activity of melatonin in 1993, the possibility that melatonin exerts its effects on the mitochondria, the main ROS-producing organelle, was hypothesized. The first experiments demonstrated a highly efficient ability of melatonin to counteract the mitochondrial oxidative stress ''in vitro'' and ''in vivo''. In parallel, melatonin increases the respiratory chain activity, reduces the oxygen consumption, and increases the ATP production. In some of these experiments we could demonstrated that the mitochondria take up melatonin in a time- and concentration-dependent manner. To further analyze the ability of melatonin to prevent and/or counteract mitochondrial dysfunction, different experimental models of aging and disease, including sepsis, Parkinsonâs disease, and Alzheimerâs disease, was evaluated. In all of them, melatonin administration restored the full bioenergetic capacity of the mitochondria, restoring or even increasing their ATP production. Along this time, it was shown that most of the tissues and organs produce melatonin independently of the pineal gland. An important feature of this extrapineal source of melatonin is that its synthetizing enzymes, AANAT and ASMT, are inducible, i.e., the cells produce melatonin when they require it for protective purposes. This melatonin does not exit to the extracellular fluid. To further analyze the dynamics of the extrapineal melatonin, we recently studied the subcellular distribution of the indoleamine in liver and brain. These studies showed that melatonin is produced in considerably higher amounts in these tissues than in the pineal gland, it is not uniformly distributed in the cell, and is mainly located in the membrane, mitochondria and nucleus. Interestingly, membrane content of melatonin increased in a dose-dependent manner after administration of melatonin to rats, but the content of the indoleamine in the nucleus and mitochondria is saturated. There are now evidences of the ability of mitochondria (and chloroplasts) to synthesize melatonin, which explains the high levels of the indoleamine in this organelle. The phylogenetic origins of the mitochondria, and the presence of melatonin in ancient one cell organisms, speak in favor of a melatonin-mitochondrion connection along the evolution, and the role of melatonin in mitochondrial homeostasis.
# [http://www.ncbi.nlm.nih.gov/pubmed/21244359 Acuna Castroviejo D, Lopez LC, Escames G, Lopez A, Garcia JA, Reiter RJ (2011) Melatonin-mitochondria interplay in health and disease. Curr Top Med Chem 11: 221-240.]
# [http://www.ncbi.nlm.nih.gov/pubmed?term=Mitochondria%20and%20chloroplasts%20as%20the%20original%20sites%20of%20melatonin%20synthesis%3A%20a%20hypothesis%20related%20to%20melatonin's%20primary%20function%20and%20evolution%20in%20eukaryotes Tan DX, Manchester LC, Liu X, Rosales-Corral SA, Acuna-Castroviejo D, Reiter RJ (2012) Mitochondria and chloroplasts as the original sites of melatonin synthesis: a hypothesis related to melatonin's primary function and evolution in eukaryotes. J Pineal Res. doi: 10.1111/jpi.12026]
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Melatonin is synthetized by the mitochondria, which in turn are the main intracellular targets of the indoleamine [1,2]. Due to the impairment of mitochondria in Parkinson's disease (PD), and its relationship with neuroinflammation, we analyzed the mitochondrial bioenergetics and melatonin effects in two models of parkinsonism, mouse and zebrafish. The participation of inflammation on mitochondria disfunction was analyzed in iNOS and nNOS deficient mice. Mitochondria were prepared from substantia nigra and striatum of control and MPTP-treated mice, and bioenergetics analyzed in an Oxygraph-2K respirometer [3]. Our results showed that MPTP increased iNOS activity in substantia nigra and striatum, whereas it sharply reduced complex I activity and mitochondrial bioenergetics in all strains. In the presence of MPTP, mice lacking iNOS showed similar restricted mitochondrial function than wild type or mice lacking nNOS. Therefore, neuroinflammation and mitochondrial dysregulation seem to act in parallel in the MPTP model of PD. Melatonin administration counteracted these effects, preventing from the drastic changes in mitochondrial oxygen consumption, and neuroinflammation, recovering normal locomotor activity of mice. The protective effects of melatonin on mitochondria are also independent of its anti-inflammatory properties, but both effects are required for an effective anti-parkinsonian activity of the indoleamine as reported in this study.
In the second study, we studied the capacity of melatonin to recover from a parkinsonian phenotype [4]. Here, 24 to 72 hpf zebrafish were treated with MPTP and ''in vivo'' respiration was measured in a Seahorse respirometer. A reduction in electron transfer system capacity, ATP turnover, and increased proton leak, were observed at 72 hpf in MPTP-treated embryos. These changes were followed by neuroinflammation and autophagy impairment. After removing MPTP from the treatment at 72 hpf, these bioenergetic deficiencies persisted up to 120 hpf. The administration of melatonin to zebrafish embryos at 72 hpf, when mitochondrial dysfunction is already present, restored the respiratory capacity and ATP production, reduced neuroinflammation, and normalized autophagy. Melatonin, added together with MPTP or added once MPTP was removed, prevented and recovered, respectively, the parkinsonian phenotype once it was established, restoring gene expression and normal function of the parkin/PINK1/DJ-1/MUL1 loop and also the normal motor activity of the embryos.
Although two main hypotheses of mitochondrial origin have been proposed, i.e., the autogenous and the endosymbiotic, only the second is being seriously considered currently. The 'hydrogen hypothesis' invokes metabolic symbiosis as the driving force for a symbiotic association between an anaerobic, strictly hydrogen-dependent (the host) and an eubacterium (the symbiont) that was able to respire, but which generated molecular hydrogen as an end product of anaerobic metabolism. The resulting proto-eukaryotic cell would have acquired the essentials of eukaryotic energy metabolism, evolving not only aerobic respiration, but also the physiological cost of the oxygen consumption, i.e., generation of reactive oxygen species (ROS) and the associated oxidative damage. This is not the only price to pay for respiring oxygen: mitochondria possess nitric oxide (NO·) for regulatory purposes but, in some instances it may react with superoxide anion radical to produce the toxic reactive nitrogen species (RNS), i.e. peroxynitrite anion, and the subsequent nitrosative damage. New mitochondria contain their own genome with a modified genetic code that is highly conserved among mammals. The transcription of certain mitochondrial genes may depend on the redox potential of the mitochondrial membrane. Mitochondria are related to the life and death of cells. They are involved in energy production and conservation, having an uncoupling mechanism to produce heat instead of ATP, but they are also involved in programmed cell death. Increasing evidence suggest the participation of mitochondria in neurodegenerative and neuromuscular diseases involving alterations in both nuclear (nDNA) and mitochondrial (mtDNA) DNA. Melatonin is a known powerful antioxidant and anti-inflammatory and increasing experimental and clinical evidence shows its beneficial effects against oxidative/nitrosative stress status, including that involving mitochondrial dysfunction. This review summarizes the data and mechanisms of action of melatonin in relation to mitochondrial pathologies.
We assessed whether melatonin administration would prevent the hyperoxidative status that occurs in lung mitochondria with age. Mitochondria from lungs of male and female senescent prone mice at 5 and 10 months of age were studied. Age-dependent mitochondrial oxidative stress was evaluated by measuring the levels of lipid peroxidation and nitrite, glutathione/glutathione disulfide ratio, and glutathione peroxidase and reductase activities. Mitochondrial respiratory chain and oxidative phosphorylation capability were also measured. Age induces a significant oxidative/nitrosative status in lung mitochondria, which exhibited a significantly reduced activity of the respiratory chain and ATP production. These manifestations of age were more pronounced in males than in females. After 9 months of melatonin administration in the drinking water, the hyperoxidative status and functional deficiency of aged lung mitochondria were totally counteracted, and had increased ATP production. The beneficial effects of melatonin were generally similar in both mice genders. Thus, melatonin administration, as a single therapy, maintained fully functioning lung mitochondria during aging, a finding with important consequences in the pathophysiology of lung aging. In view of these data melatonin, the production of which decreases with age, should be considered a preventive therapy against the hyperoxidative status of the aged lungs, and its use may lead to the avoidance of respiratory complications in the elderly. +
Endogenous melatonin is synthesized from tryptophan via 5-hydroxytryptamine. It is considered an indoleamine from a biochemical point of view because the melatonin molecule contains a substituted indolic ring with an amino group. The circadian production of melatonin by the pineal gland explains its chronobiotic influence on organismal activity, including the endocrine and non-endocrine rhythms. Other functions of melatonin, including its antioxidant and anti-inflammatory properties, its genomic effects, and its capacity to modulate mitochondrial homeostasis, are linked to the redox status of cells and tissues. With the aid of specific melatonin antibodies, the presence of melatonin has been detected in multiple extrapineal tissues including the brain, retina, lens, cochlea, Harderian gland, airway epithelium, skin, gastrointestinal tract, liver, kidney, thyroid, pancreas, thymus, spleen, immune system cells, carotid body, reproductive tract, and endothelial cells. In most of these tissues, the melatonin-synthesizing enzymes have been identified. Melatonin is present in essentially all biological fluids including cerebrospinal fluid, saliva, bile, synovial fluid, amniotic fluid, and breast milk. In several of these fluids, melatonin concentrations exceed those in the blood. The importance of the continual availability of melatonin at the cellular level is important for its physiological regulation of cell homeostasis, and may be relevant to its therapeutic applications. Because of this, it is essential to compile information related to its peripheral production and regulation of this ubiquitously acting indoleamine. Thus, this review emphasizes the presence of melatonin in extrapineal organs, tissues, and fluids of mammals including humans. +
Our laboratory has previously demonstrated the presence of constitutively expressed mitochondrial uncoupling protein 1 in mouse thymocytes. In our endeavours to understand the role of mitochondrial uncoupling protein 1 in thymocyte function, we compared cell profiles in thymus and spleen of wild-type
with those of UCP 1 knock-out mice, which in turn led to comparative investigations of apoptotic potential in thymocytes from these mice. We demonstrate that spleen cell numbers were reduced âŒ3-fold in UCP 1 knock-out mice compared to wild-type mice. We record a halving of CD8 single positive cell numbers in thymus with a significant incremental increase in CD4/CD8 double positives cell numbers in the thymus of UCP 1 knock-out mice compared to wild-type mice. These data are mirrored by an approximate halving of CD8 single positive cell numbers and a doubling of CD4/CD8 double positive cell numbers in the spleen of UCP 1 knock-out mice compared to wild-type mice. These differences are most probably explained by our observations of decreased apoptotic potential and higher ATP levels in thymocytes of UCP 1 knock-out mice
when compared to wild-type controls. We conclude that constitutively expressed UCP 1 is a factor in determining T-cell population selection in mice. +
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Long-chain fatty acids (LCFAs) are an important fuel for heart, skeletal muscle (especially type 1, myoglobin-rich, âslow-twitchâ muscle), and liver. Combustion of LCFAs is facilitated by conversion of LCFA-CoAs to long-chain acylcarnitines (LCACs) by carnitine palmitoyltransferase 1 (CPT1) on the outer aspect of the mitochondrial membrane, followed by transport into the mitochondrion and retroconversion to LCFA-CoA by CPT2; the LCFA-CoA is then available for ÎČ-oxidation. The match between LCFA availability, conversion to LCACs, and ÎČ-oxidation is not perfect, leading in some cases to accumulation of LCACs in muscleâfor instance, during exercise or type 2 diabetes. Inborn errors of ÎČ-oxidation enzymes can also lead to accumulation of LCACs and other lipids in tissues. A major question in the field of metabolic (patho)physiology is whether or not lipids such as LCACs serve as signaling molecules or âlipotoxinsâ under certain conditions. Several years ago, we made the proposal that some acylcarnitines activate inflammation in macrophages (and perhaps other tissues) and contribute to insulin resistance. Follow up research supported this assertion when LCACs were used to treat immune and muscle cells in culture, and others have shown that blockade of CPT1 in culture alleviates fat-induced insulin resistance. Other studies in our lab and those of others support the idea that LCACs have bioactivities including increasing intracellular calcium, neuronal activation, and mitochondrial dysfunction, possibly by acting through interaction with membranes. This talk will provide a retrospective overview of LCAC-associated cell stress responses, and will also highlight an emerging role for myoglobin as a LCFA/LCAC binding protein. We speculate that this interaction is important to control intracellular free concentrations and trafficking of LCACs and LCFAs, hence possibly playing a role in pathological and physiological actions of these lipids in skeletal muscle and cardiac myocytes.
Primary mitochondrial diseases (PMD) are a large, heterogeneous group of genetic disorders affecting mitochondrial function, mostly by disrupting the oxidative phosphorylation (OXPHOS) system. Understanding the cellular metabolic re-wiring occurring in PMD is crucial for the development of novel diagnostic tools and treatments, as PMD are often complex to diagnose and most of them currently have no effective therapy.
To characterize the cellular metabolic consequences of OXPHOS dysfunction and based on the metabolic signature, to design new diagnostic and therapeutic strategies.
''In vitro'' assays were performed in skin-derived fibroblasts obtained from patients with diverse PMD and validated in pharmacological models of OXPHOS dysfunction. Proliferation was assessed using the Incucyte technology. Steady-state glucose and glutamine tracing studies were performed with LC-MS quantification of cellular metabolites. The therapeutic potential of nutritional supplements was evaluated by assessing their effect on proliferation and on the metabolomics profile. Successful therapies were then tested in a ''in vivo'' lethal rotenone model in zebrafish.
OXPHOS dysfunction has a unique metabolic signature linked to an NAD+/NADH imbalance including depletion of TCA intermediates and aspartate, and increased levels of glycerol-3-phosphate. Supplementation with pyruvate and uridine fully rescues this altered metabolic profile and the subsequent proliferation deficit. Additionally, in zebrafish, the same nutritional treatment increases the survival after rotenone exposure.
Our findings reinforce the importance of the NAD+/NADH imbalance following OXPHOS dysfunction in PMD and open the door to new diagnostic and therapeutic tools for PMD. +
Objective
Pulmonary hypertension (PH) is characterized by increased pulmonary vascular remodeling, resistance, and pressures. Reactive oxygen species (ROS) contribute to PH-associated vascular dysfunction. NADPH oxidases (Nox) and mitochondria are major sources of superoxide (O2âąâ) and hydrogen peroxide (H2O2) in pulmonary vascular cells. Hypoxia, a common stimulus of PH, increases Nox expression and mitochondrial ROS (mtROS) production. The interactions between these two sources of ROS generation continue to be defined. We hypothesized that mitochondria-derived O2âąâ (mtO2âąâ) and H2O2 (mtH2O2) increases Nox expression to promote PH pathogenesis and that mitochondria-targeted antioxidants can reduce mtROS, Nox expression, and hypoxia-induced PH.
Approach and Results
Exposure of human pulmonary artery endothelial cells to hypoxia for 72 hours increased mtO2âąâ and mtH2O2. To assess the contribution of mtO2âąâ and mtH2O2 to hypoxia-induced PH, mice that overexpress superoxide dismutase 2 (TghSOD2) or mitochondria-targeted catalase (MCAT) were exposed to normoxia (21% O2) or hypoxia (10% O2) for 3 weeks. Compared to hypoxic control mice, MCAT mice developed less hypoxia-induced increases in RVSP, α-SMA staining, extracellular H2O2 (Amplex Red), Nox2 and Nox4 (qRT-PCR and western blot), or cyclinD1 and PCNA (western blot). In contrast, TghSOD2 mice experienced exacerbated responses to hypoxia.
Conclusions
These studies demonstrate that hypoxia increases mtO2âąâ and mtH2O2. Targeting mtH2O2 attenuates PH pathogenesis, whereas, targeting mtO2âąâ exacerbates PH. These differences in PH pathogenesis were mirrored by RVSP, vessel muscularization, levels of Nox2 and Nox4, proliferation, and H2O2 release. These studies suggest that targeted reductions in mtH2O2 generation may be particularly effective at preventing hypoxia-induced PH. +
The increasing application of nanomaterials in various fields such as drug delivery, cosmetics, disease detection, cancer treatment, food preservation etc. has resulted in high levels of engineered nanoparticles in the environment, thus leading to higher possibility of direct or indirect interactions between these particles and biological systems. In this study, the toxic effects of three commercially available nanomaterials; copper oxide nanoparticles, copper-iron oxide nanopowders and carbon nanopowders were determined in the human hepatoma HepG2 cells using various toxicological assays which are indicative of cytotoxicity (MTT and neutral red assays), mutagenicity (cytokinesis-block micronucleus assay), oxidative stress (total reactive oxygen species and superoxide anion production) and mitochondrial impairment (cellular oxygen consumption). There was increased cytotoxicity, mutagenicity, and mitochondrial impairment in the cells treated with higher concentrations of the nanomaterials, especially the copper oxide nanoparticles. The fold production of reactive oxygen species was similar at the concentrations tested in this study but longer exposure duration resulted in production of more superoxide anions. The results of this study showed that copper oxide nanoparticles are highly toxic to the human HepG2 cells, thus implying that the liver is a target organ in human for copper oxide nanoparticles toxicity.
<small>Copyright © 2019 Elsevier Inc. All rights reserved.</small> +
The soil-dwelling nematode ''Caenorhabditis elegans'' is a bacteriovorous animal, excreting the vast majority of its nitrogenous waste as ammonia (25.3±1.2â
”mol gFW<sup>-1</sup> day<sup>-1</sup>) and very little urea (0.21±0.004â
”mol gFW<sup>-1</sup> day<sup>-1</sup>). Although these roundworms have been used for decades as genetic model systems, very little is known about their strategy to eliminate the toxic waste product ammonia from their bodies into the environment. The current study provides evidence that ammonia is at least partially excreted via the hypodermis. Starvation reduced the ammonia excretion rates by more than half, whereas mRNA expression levels of the Rhesus protein CeRhr-2, V-type H<sup>+</sup>-ATPase (subunit A) and Na<sup>+</sup>/K<sup>+</sup>-ATPase (α-subunit) decreased correspondingly. Moreover, ammonia excretion rates were enhanced in media buffered to pH 5 and decreased at pH 9.5. Inhibitor experiments, combined with enzyme activity measurements and mRNA expression analyses, further suggested that the excretion mechanism involves the participation of the V-type H<sup>+</sup>-ATPase, carbonic anhydrase, Na<sup>+</sup>/K<sup>+</sup>-ATPase, and a functional microtubule network. These findings indicate that ammonia is excreted, not only by apical ammonia trapping, but also via vesicular transport and exocytosis. Exposure to 1â
mmol l<sup>-1</sup> NH4Cl caused a 10-fold increase in body ammonia and a tripling of ammonia excretion rates. Gene expression levels of CeRhr-1 and CeRhr-2, V-ATPase and Na<sup>+</sup>/K<sup>+</sup>-ATPase also increased significantly in response to 1â
mmol l<sup>-1</sup> NH4Cl. Importantly, a functional expression analysis showed, for the first time, ammonia transport capabilities for CeRhr-1 in a phylogenetically ancient invertebrate system, identifying these proteins as potential functional precursors to the vertebrate ammonia-transporting Rh-glycoproteins. +
We have investigated the extent to which functional expression of the plant alternative oxidase (from Sauromatum guttatum) in Schizosaccharomyces pombe affects yeast growth. When cells are cultured on glycerol, the maximum specific growth rate is decreased from 0.13 to 0.11 h-1 while growth yield is lowered by 20% (from 1. 14 x 10(8) to 9.12 x 10(7) cells ml-1). Kinetic studies suggest that the effect on growth is mitochondrial in origin. In isolated mitochondria we found that the alternative oxidase actively competes with the cytochrome pathway for reducing equivalents and contributes up to 24% to the overall respiratory activity. Metabolic control analysis reveals that the alternative oxidase exerts a considerable degree of control (22%) on total electron flux. Furthermore, the negative control exerted by the alternative oxidase on the flux ratio of electrons through the cytochrome and alternative pathways is comparable with the positive control exerted on this flux-ratio by the cytochrome pathway. To our knowledge, this is the first paper to report a phenotypic effect because of plant alternative oxidase expression. We suggest that the effect on growth is the result of high engagement of the non-protonmotive alternative oxidase in yeast respiration that, consequently, lowers the efficiency of energy conservation and hence growth. +
We have investigated the extent to which functional expression of the plant alternative oxidase (from ''Sauromatum guttatum'') in ''Schizosaccharomyces pombe'' affects yeast growth. When cells are cultured on glycerol, the maximum specific growth rate is decreased from 0.13 to 0.11 h<sup>-1</sup> while growth yield is lowered by 20% (from 1. 14 x 10<sup>8</sup> to 9.12 x 10<sup>7</sup> cells ml<sup>-1</sup>). Kinetic studies suggest that the effect on growth is mitochondrial in origin. In isolated mitochondria we found that the alternative oxidase actively competes with the cytochrome pathway for reducing equivalents and contributes up to 24% to the overall respiratory activity. Metabolic control analysis reveals that the alternative oxidase exerts a considerable degree of control (22%) on total electron flux. Furthermore, the negative control exerted by the alternative oxidase on the flux ratio of electrons through the cytochrome and alternative pathways is comparable with the positive control exerted on this flux-ratio by the cytochrome pathway. To our knowledge, this is the first paper to report a phenotypic effect because of plant alternative oxidase expression. We suggest that the effect on growth is the result of high engagement of the non-protonmotive alternative oxidase in yeast respiration that, consequently, lowers the efficiency of energy conservation and hence growth. +
Regulation of succinate dehydrogenase was investigated using tightly coupled potato tuber mitochondria in a novel fashion by simultaneously measuring the oxygen uptake rate and the ubiquinone (Q) reduction level. We found that the activation level of the enzyme is unambiguously reflected by the kinetic dependence of the succinate oxidation rate upon the Q-redox poise. Kinetic results indicated that succinate dehydrogenase is activated by both ATP (K<sub>1/2</sub>) approximately 3 microm) and ADP. The carboxyatractyloside insensitivity of these stimulatory effects indicated that they occur at the cytoplasmic side of the mitochondrial inner membrane. Importantly, our novel approach revealed that the enzyme is also activated by oligomycin (K<sub>1/2</sub>) approximately 16 nm). Time-resolved kinetic measurements of succinate dehydrogenase activation by succinate furthermore revealed that the activity of the enzyme is negatively affected by potassium. The succinate-induced activation (+/-K<sup>+</sup>) is prevented by the presence of an uncoupler. Together these results demonstrate that ''in vitro'' activity of succinate dehydrogenase is modulated by the protonmotive force. We speculate that the widely recognized activation of the enzyme by adenine nucleotides in plants is mediated in this manner. A mechanism that could account for such regulation is suggested and ramifications for its ''in vivo'' relevance are discussed. +
Oxidative phosphorylation is an important energy-conserving mechanism coupling mitochondrial electron transfer to ATP synthesis. Coupling between respiration and phosphorylation is not fully efficient due to proton and electron leaks. In this chapter, methods are presented to measure proton and electron leak activities in isolated mitochondria. The relative strength of a modular kinetic approach to probe oxidative phosphorylation is emphasised. +
The studies aimed at determine the effect of body mass index (BMI) on aerobic power (VO2max) and energy expenditure (EE) during manual operation in primary agro-processing. Selected physiological and anthropometry properties of voluntary group of thirteen subjects were measured with respect to manual lifting of loads through the vertical distance of 0.92m from ankle level to inlet opening of thresher during threshing operation. The measured properties showed that height and weight ranged from 1.65m to 1.83m and 53g to 78g respectively, the calculated BMI ranged from 18.38kg/m2 to 28.65kg/m2. Heart rate at rest (HRrest) and maximum heart rate (HRmax) were measured with maximum; minimum values of 56beat/min; 89beat/min and 191beat/min; 200beat/min corresponded to mean ± SD of 72.5 ± 11.7 and 195.8 ± 3.0 respectively. The calculated EE and VO2max have minimum; maximum values of 94kj/min; 396kj/min and 32.2ml/min/kg; 52.5ml/min/kg corresponded to mean ± SD of 238.7 ± 92.5 and 41.5 ± 6.9. Results on relational effects showed that increase in EE relate positively to BMI, while increase in VO2max relate negatively to BMI. Also, it was found that heights of the subjects relate directly to lifted loads, while body weights relate inversely to the lifted loads. Regression models that could be used to express the relationship existing between independent variables EE (e) and VO2max (a), and dependent variable BMI (yB) are; yB = 6.2792e + 106.9 (R2 = 0.0361) and yB = - 0.4858 a + 51.689 (R2 = 0.039) respectively. Also, the regression models for relationship that occurred between independent variables height (h) and weight (w) and dependent variable load quantity (yL)are; yL= 0.2465h +164.58 (R2 = 0.091) and yL = -0 .4018w +78.592 (R2 = 0.1389)respectively. Environmental conditions such as relative humidity, air temperature and atmospheric pressure were noted, and has the values of 84.57%, 21.79oC and 765mmHg respectively. The relationship existing between the physiological factors and BMI were found to be adequately expressed by regression equations.
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