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Background: Research has shown the multiple actions of curcumin on different cell systems, including enzymes and mitochondria. The detected effects of curcumin on mitochondria are diverse, ranging from protective to toxic. Objectives: In this present work, the influence of curcumin, as well as cinnamic acid, which is a microbial metabolite and a possible product of the microbial breakdown of curcumin, on isolated mitochondria, was investigated. Methods: Membrane potential, swelling, respiration, and calcium retention capacity were studied using selective electrodes, fluorescence and spectral methods. Results: It was found that curcumin at low concentrations (10–20 μM) activated the opening of the calcium-dependent permeability transition pore (mPTP) and decreased the calcium retention capacity and threshold concentrations necessary for the mPTP opening. Moreover, curcumin caused a concentration-dependent stepwise decrease in the membrane potential, accompanied by the activation of respiration and a decrease in oxidative phosphorylation, which indicates that curcumin is a typical mitochondrial uncoupler. The uncoupling effect strongly depended on the concentration of curcumin, which also increased, stepwise, from weak uncoupling at 25 µM to complete uncoupling at 75–100 µM. Cinnamic acid had similar effects, with the exception of the depolarizing effect, at concentrations that were an order of magnitude higher. Conclusions: Presumably, the uncoupling action of curcumin is a priming event that modulates any energy- and redox-dependent mitochondrial functions, from positive stimulation to toxic disorder. This effect can also underlie the curcumin-induced changes in different cellular processes and be achieved by targeted delivery of curcumin to certain cells, bypassing the microbiota. [ABSTRACT FROM AUTHOR]

Severe burn injuries are defined by a prolonged hypermetabolic response characterized by increases in resting energy expenditure, systemic catabolism, and multi-organ dysfunction. The sustained elevation of catecholamines following a burn injury is thought to significantly contribute to this hypermetabolic response, leading to changes in adipose tissue such as increased lipolysis and the browning of subcutaneous white adipose tissue (WAT). Failure to mitigate these adverse changes within the adipose tissue has been shown to exacerbate the post-burn hypermetabolic response and lead to negative outcomes. Propranolol, a non-selective β-blocker, has been clinically administered to improve outcomes of pediatric and adult burn patients, but there is inadequate knowledge of its effects on the distinct adipose tissue depots. In this study, we investigated the adipose depot-specific alterations that occur in response to burn injury. Moreover, we explored the therapeutic effects of β-adrenoceptor blockade via the drug propranolol in attenuating these burn-induced pathophysiological changes within the different fat depots. Using a murine model of thermal injury, we show that burn injury induces endoplasmic reticulum (ER) stress in the epididymal (eWAT) but not in the inguinal (iWAT) WAT depot. Conversely, burn injury induces the activation of key lipolytic pathways in both eWAT and iWAT depots. Treatment of burn mice with propranolol effectively mitigated adverse burn-induced alterations in the adipose by alleviating ER stress in the eWAT and reducing lipolysis in both depots. Furthermore, propranolol treatment in post-burn mice attenuated UCP1-mediated subcutaneous WAT browning following injury. Overall, our findings suggest that propranolol serves as an effective therapeutic intervention to mitigate the adverse changes induced by burn injury, including ER stress, lipotoxicity, and WAT browning, in both adipose tissue depots. Key messages: Burn injury adversely affects adipose tissue metabolism via distinct changes in both visceral and subcutaneous adipose depots. Propranolol, a non-selective β-adrenergic blocker, attenuates many of the adverse adipose tissue changes mediated by burn injury. [ABSTRACT FROM AUTHOR]

The purpose of this work was to quantitatively characterize the effectiveness of oxidative phosphorylation uncouplers and decoupling agents in functionally active mitochondria, taking into account their content in the hydrophobic region of the inner membrane of these organelles. When conducting theoretical studies, it is accepted that uncouplers and decouplers occupy part of the volume of mitochondria to exhibit their activity, which is defined as the effective volume. The following quantities characterizing the action of these reagents are considered: (1) concentrations of reagents that cause double stimulation of mitochondrial respiration in state 4 ( C 200 ); (2) effective distribution coefficient ( E MW ) - the ratio of the amount of reagents in the effective volume of mitochondria and the water volume; (3) the relative amount of reagents associated with the effective volume of mitochondria ( U M / U T ); (4) specific activity of reagents localized in the effective volume of mitochondria ( A M ). We have developed methods for determining these values, based on an analysis of the dependence of the rate of mitochondrial respiration on the concentration of uncouplers and decoupling agents at two different concentrations of mitochondrial protein in the incubation medium. During experimental studies, we compared the effects of the classical protonophore uncouplers 2,4-dinitrophenol (DNP) and сarbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP), the natural uncouplers lauric and palmitic acids, and the natural decouplers α,ω-tetradecanedioic (TDA) and α,ω-hexadecanedioic (HDA) acids that differ both in the structure of the molecule and in the degree of solubility in lipids. Using the developed methods, we have clarified the dependence of the degree of activity of these uncouplers and decoupling agents on the distribution of their molecules between the effective volume of mitochondria and the water volume. [ABSTRACT FROM AUTHOR]

BACKGROUND: Alzheimer's disease (AD) is the most common cause of dementia worldwide, with apolipoprotein Eε4 (APOEε4) being the strongest genetic risk factor. Current clinical diagnostic imaging focuses on amyloid and tau; however, new methods are needed for earlier detection. METHODS: PET imaging was used to assess metabolism‐perfusion in both sexes of aging C57BL/6J, and hAPOE mice, and were verified by transcriptomics, and immunopathology. RESULTS: All hAPOE strains showed AD phenotype progression by 8 months, with females exhibiting the regional changes, which correlated with GO‐term enrichments for glucose metabolism, perfusion, and immunity. Uncoupling analysis revealed APOEε4/ε4 exhibited significant Type‐1 uncoupling (↓ glucose uptake, ↑ perfusion) at 8 and 12 months, while APOEε3/ε4 demonstrated Type‐2 uncoupling (↑ glucose uptake, ↓ perfusion), while immunopathology confirmed cell specific contributions. DISCUSSION: This work highlights APOEε4 status in AD progression manifests as neurovascular uncoupling driven by immunological activation, and may serve as an early diagnostic biomarker. Highlights: We developed a novel analytical method to analyze PET imaging of 18F‐FDG and 64Cu‐PTSM data in both sexes of aging C57BL/6J, and hAPOEε3/ε3, hAPOEε4/ε4, and hAPOEε3/ε4 mice to assess metabolism‐perfusion profiles termed neurovascular uncoupling.This analysis revealed APOEε4/ε4 exhibited significant Type‐1 uncoupling (decreased glucose uptake, increased perfusion) at 8 and 12 months, while APOEε3/ε4 demonstrated significant Type‐2 uncoupling (increased glucose uptake, decreased perfusion) by 8 months which aligns with immunopathology and transcriptomic signatures.This work highlights that there may be different mechanisms underlying age related changes in APOEε4/ε4 compared with APOEε3/ε4. We predict that these changes may be driven by immunological activation and response, and may serve as an early diagnostic biomarker. [ABSTRACT FROM AUTHOR]

Pancreatic cancer has an exaggerated dependence on mitochondrial metabolism, but methods to specifically target the mitochondria without off target effects in normal tissues that rely on these organelles is a significant challenge. The mitochondrial uncoupling protein 2 (UCP2) has potential as a cancer-specific drug target, and thus, we will review the known biology of UCP2 and discuss its potential role in the pathobiology and future therapy of pancreatic cancer. [ABSTRACT FROM AUTHOR]

The cofactor of a class A monooxygenase is reduced at an external location of the enzyme and is subsequently pulled back into the active site after the reduction. This observation brings the question; is there any defense mechanism of the active site of a monooxygenase against the formation of the harmful hydrogen peroxide from the reactive C(4a)-(hydro)peroxide intermediate? In this study, the barrier energies of one to three water molecule-mediated uncoupling reaction mechanisms in water exposed reaction conditions were determined. These were found to be facile barriers. Secondly, uncoupling was modeled in the active site of kynurenine 3-monooxygenase complex which was represented with 258 atoms utilizing cluster approach. Comparison of the barrier energy of the cluster model to the models that represent the water exposed conditions revealed that the enzyme does not have an inhibitory reaction site architecture as the compared barrier energies are roughly the same. The main defense mechanism of KMO against the formation of the hydrogen peroxide is deduced to be the insulation, and without this insulation, the monooxygenation would not take place as the barrier height of the hydrogen peroxide formation within the active site is almost half of that of the monooxygenation. [ABSTRACT FROM AUTHOR]

Flavin‐dependent monooxygenases (FMOs) constitute a diverse enzyme family that catalyzes crucial hydroxylation, epoxidation, and Baeyer–Villiger reactions across various metabolic pathways in all domains of life. Due to the intricate nature of this enzyme family's mechanisms, some aspects of their functioning remain unknown. Here, we present the results of molecular dynamics computations, supplemented by a bioinformatics analysis, that clarify the early stages of their catalytic cycle. We have elucidated the intricate binding mechanism of NADPH and L‐Orn to a class B monooxygenase, the ornithine hydroxylase from Aspergillus$$ Aspergillus $$fumigatus$$ fumigatus $$ known as SidA. Our investigation involved a comprehensive characterization of the conformational changes associated with the FAD (Flavin Adenine Dinucleotide) cofactor, transitioning from the out to the in position. Furthermore, we explored the rotational dynamics of the nicotinamide ring of NADPH, shedding light on its role in facilitating FAD reduction, supported by experimental evidence. Finally, we also analyzed the extent of conservation of two Tyr‐loops that play critical roles in the process. [ABSTRACT FROM AUTHOR]

Aortic aneurysms are prevalent and severe vascular diseases with high mortality from unpredicted ruptures, while the only treatment option is surgical correction of large aneurysms with considerable risk. We have shown that folic acid (FA) is highly effective in alleviating development of aneurysms although not sufficient to completely attenuate aneurysm formation. Here, we examined therapeutic effects on aneurysms of combining FA with Nifedipine as novel and potentially more effective oral medication. Oral administration with FA (15 mg/kg/day) significantly reduced incidence of AAA from 85.71% to 18.75% in Ang II-infused apolipoprotein E (apoE) null mice, while combination of FA with Nifedipine (1.5, 5.0 or 20 mg/kg/day) substantially and completely further reduced incidence of AAA to 12.5%, 11.76% and 0.00% respectively in a dose-dependent manner. The combinatory therapy substantially and completely further alleviated enlargement of abdominal aortas defined by ultrasound, vascular remodeling characterized by elastin degradation and adventitial hypertrophy, as well as aortic superoxide production and eNOS uncoupling activity also in a dose-dependent manner, with combination of FA with 20 mg/kg/day Nifedipine attenuating all of these features by 100% to control levels. Aortic NO and H4B bioavailabilities were also dose-dependently further improved by combining FA with Nifedipine. These data establish entirely innovative and robust therapeutic regime of FA combined with Nifedipine for the treatment of aortic aneurysms. The comminatory therapy can serve as a first-in-class and most effective oral medication for aortic aneurysms, which can be rapidly translated into clinical practice to revolutionize management of the devastating vascular diseases of aortic aneurysms known as silent killers.

Limited medical therapies have been implemented for the treatment of the devastating cardiorespiratory disease of pulmonary hypertension (PH) while none of which is sufficiently effective to stop or regress development of PH. We have previously shown that netrin-1, an axon-guiding protein during development, protects against ischemia reperfusion injury induced myocardial infarction via modest and stable production of nitric oxide (NO) and attenuation of oxidative stress. Since NO deficiency and oxidative stress-mediated vascular remodeling play important roles in the pathogenesis of PH, our present study investigated therapeutic effects on PH of netrin-1 and its derived small peptides. Infused into mice for 3 weeks during exposure to hypoxia, netrin-1 and netrin-1 derived small peptides V1, V2 or V3 substantially alleviated pathophysiological and molecular features of PH, as indicated by abrogated increases in mean pulmonary artery pressure (mPAP) and right ventricular systolic pressure (RVSP), attenuated right ventricular hypertrophy, diminished vascular remodeling of medial thickening and upregulation in smooth muscle alpha-actin (SMA) and proliferative cell nuclear antigen (PCNA), and alleviated perivascular and peribronchial fibrosis reflected by collagen deposition. NO bioavailability was substantially improved by treatment with netrin-1 and netrin-1 derived small peptides, while hypoxia induced increases in total superoxide production and eNOS uncoupling activity were all attenuated. These dual mechanisms of increasing NO bioavailability and decreasing oxidative stress at the same time, underlie robust protective effects on PH of netrin-1 and its derived small peptides, which are different from existing medications that primarily target NO signaling alone. Our data for the first time demonstrate intriguing findings that netrin-1 and netrin-1 derived small peptides can be used as novel and robust therapeutics for the treatment of PH.

Worldwide, interest in mitochondria is constantly growing, as evidenced by scientific statistics, and studies of the functioning of these organelles are becoming more prevalent than studies of other cellular structures. In this analytical review, mitochondria are conditionally placed in a certain cellular center, which is responsible for both energy production and other non-energetic functions, without which the existence of not only the eukaryotic cell itself, but also the entire organism is impossible. Taking into account the high multifunctionality of mitochondria, such a fundamentally new scheme of cell functioning organization, including mitochondrial management of processes that determine cell survival and death, may be justified. Considering that this issue is dedicated to the memory of V. P. Skulachev, who can be called mitocentric, due to the history of his scientific activity almost entirely aimed at studying mitochondria, this work examines those aspects of mitochondrial functioning that were directly or indirectly the focus of attention of this outstanding scientist. We list all possible known mitochondrial functions, including membrane potential generation, synthesis of Fe-S clusters, steroid hormones, heme, fatty acids, and CO2. Special attention is paid to the participation of mitochondria in the formation and transport of water, as a powerful biochemical cellular and mitochondrial regulator. The history of research on reactive oxygen species that generate mitochondria is subject to significant analysis. In the section "Mitochondria in the center of death", special emphasis is placed on the analysis of what role and how mitochondria can play and determine the program of death of an organism (phenoptosis) and the contribution made to these studies by V. P. Skulachev. [ABSTRACT FROM AUTHOR]

Endothelial dysfunction (ED) is commonly considered a crucial initiating step in the pathogenesis of numerous cardiovascular diseases. The coupling of endothelial nitric oxide synthase (eNOS) is important in maintaining normal endothelial functions. However, it still remains elusive whether and how eNOS SUMOylation affects the eNOS coupling. In the study, we investigate the roles and possible action mechanisms of protein inhibitor of activated STAT 1 (PIAS1) in ED. Human umbilical vein endothelial cells (HUVECs) treated with palmitate acid (PA) in vitro and ApoE−/− mice fed with high‐fat diet (HFD) in vivo were constructed as the ED models. Our in vivo data show that PIAS1 alleviates the dysfunction of vascular endothelium by increasing nitric oxide (NO) level, reducing malondialdehyde (MDA) level, and activating the phosphatidylinositol 3‐kinase‐protein kinase B‐endothelial nitric oxide synthase (PI3K‐AKT‐eNOS) signaling in ApoE−/− mice. Our in vitro data also show that PIAS1 can SUMOylate eNOS under endogenous conditions; moreover, it antagonizes the eNOS uncoupling induced by PA. The findings demonstrate that PIAS1 alleviates the dysfunction of vascular endothelium by promoting the SUMOylation and inhibiting the uncoupling of eNOS, suggesting that PIAS1 would become an early predictor of atherosclerosis and a new potential target of the hyperlipidemia‐related cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Background: Intrarenal hypoxia has been suggested a unifying pathway to chronic kidney disease (CKD) and increased mitochondria leak respiration, which increases mitochondrial oxygen usage and is one important mechanism contributing to the development of the hypoxia. Previous studies indicate that angiotensin II (Ang II) effects on mitochondria function could be dose dependent. We investigated how moderate and high levels of Ang II affect kidney mitochondria function and pathways of leak respiration. Methods: C57 black 6 mice were treated with either vehicle or Ang II in low dose (400 ng/kg/min) or high dose (1,000 ng/kg/min) for 4 weeks. The function of kidney cortex mitochondria was measured by high-resolution respirometry. Ang II effects on gene expression in kidney tissue were measured by quantitative real-time PCR. Thiobarbituric acids reactive substances were determined as a marker of oxidative stress, and urinary protein excretion was measured as a maker of kidney injury. Results: Low-dose Ang II induced overall mitochondria respiration, without compromising capacity of ATP production. Mitochondrial leak respiration was increased, and levels of oxidative stress were unchanged. However, high-dose Ang II decreased overall mitochondria respiration and reduced mitochondrial capacity for ATP production. Mitochondrial leak respiration was decreased, and oxidative stress increased in kidney tissue. Furthermore, gene expression of mediators that stimulate vasoconstriction and ROS production was increased, while components of counteracting pathways were decreased. Conclusions: In conclusion, Ang II dose-dependently affects mitochondrial function and leak respiration. Thus, Ang II has the potential to directly affect cellular metabolism during conditions of altered Ang II signaling.

Background: Research has shown the multiple actions of curcumin on different cell systems, including enzymes and mitochondria. The detected effects of curcumin on mitochondria are diverse, ranging from protective to toxic. Objectives: In this present work, the influence of curcumin, as well as cinnamic acid, which is a microbial metabolite and a possible product of the microbial breakdown of curcumin, on isolated mitochondria, was investigated. Methods: Membrane potential, swelling, respiration, and calcium retention capacity were studied using selective electrodes, fluorescence and spectral methods. Results: It was found that curcumin at low concentrations (10–20 μM) activated the opening of the calcium-dependent permeability transition pore (mPTP) and decreased the calcium retention capacity and threshold concentrations necessary for the mPTP opening. Moreover, curcumin caused a concentration-dependent stepwise decrease in the membrane potential, accompanied by the activation of respiration and a decrease in oxidative phosphorylation, which indicates that curcumin is a typical mitochondrial uncoupler. The uncoupling effect strongly depended on the concentration of curcumin, which also increased, stepwise, from weak uncoupling at 25 µM to complete uncoupling at 75–100 µM. Cinnamic acid had similar effects, with the exception of the depolarizing effect, at concentrations that were an order of magnitude higher. Conclusions: Presumably, the uncoupling action of curcumin is a priming event that modulates any energy- and redox-dependent mitochondrial functions, from positive stimulation to toxic disorder. This effect can also underlie the curcumin-induced changes in different cellular processes and be achieved by targeted delivery of curcumin to certain cells, bypassing the microbiota.

Pyrazinoic acid is the active form of pyrazinamide, a first-line antibiotic used to treat Mycobacterium tuberculosis infections. However, the mechanism of action of pyrazinoic acid remains a subject of debate, and alternatives to pyrazinamide in cases of resistance are not available. The work presented here demonstrates that pyrazinoic acid and known protonophores including salicylic acid, benzoic acid, and carbonyl cyanide m-chlorophenyl hydrazone all exhibit pH-dependent inhibition of mycobacterial growth activity over a physiologically relevant range of pH values. Other anti-tubercular drugs, including rifampin, isoniazid, bedaquiline, and p-aminosalicylic acid, do not exhibit similar pH-dependent growth-inhibitory activities. The growth inhibition curves of pyrazinoic, salicylic, benzoic, and picolinic acids, as well as carbonyl cyanide m-chlorophenyl hydrazone, all fit a quantitative structure–activity relationship (QSAR) derived from acid–base equilibria with R2 values > 0.95. The QSAR model indicates that growth inhibition relies solely on the concentration of the protonated forms of these weak acids (rather than the deprotonated forms). Moreover, pyrazinoic acid, salicylic acid, and carbonyl cyanide m-chlorophenyl hydrazone all caused acidification of the mycobacterial cytoplasm at concentrations that inhibit bacterial growth. Thus, it is concluded that pyrazinoic acid acts as an uncoupler of oxidative phosphorylation and that disruption of proton motive force is the primary mechanism of action of pyrazinoic acid rather than the inhibition of a classic enzyme activity.

Objective: Enhancing energy turnover via uncoupled mitochondrial respiration in adipose tissue has great potential to improve human obesity and other metabolic complications. However, the amount of human brown adipose tissue and its uncoupling protein 1 (UCP1) is low in obese patients. Recently, a class of endogenous molecules, N-acyl amino acids (NAAs), was identified as mitochondrial uncouplers in murine adipocytes, presumably acting via the adenine nucleotide translocator (ANT). Given the translational potential, we investigated the bioenergetic effects of NAAs in human adipocytes, characterizing beneficial and adverse effects, dose ranges, amino acid derivatives and underlying mechanisms. Method: NAAs with neutral (phenylalanine, leucine, isoleucine) and polar (lysine) residues were synthetized and assessed in intact and permeabilized human adipocytes using plate-based respirometry. The Seahorse technology was applied to measure bioenergetic parameters, dose-dependency, interference with UCP1 and adenine nucleotide translocase (ANT) activity, as well as differences to the established chemical uncouplers niclosamide ethanolamine (NEN) and 2,4-dinitrophenol (DNP). Result: NAAs with neutral amino acid residues potently induce uncoupled respiration in human adipocytes in a dose-dependent manner, even in the presence of the UCP1-inhibitor guanosine diphosphate (GDP) and the ANT-inhibitor carboxyatractylate (CAT). However, neutral NAAs significantly reduce maximal oxidation rates, mitochondrial ATP-production, coupling efficiency and reduce adipocyte viability at concentrations above 25 μM. The in vitro therapeutic index (using induced proton leak and viability as determinants) of NAAs is lower than that of NEN and DNP. Conclusion: NAAs are potent mitochondrial uncouplers in human adipocytes, independent of UCP1 and ANT. However, previously unnoticed adverse effects harm adipocyte functionality, reduce the therapeutic index of NAAs in vitro and therefore question their suitability as anti-obesity agents without further chemical modifications.

The activated sludge method is currently the most widely used biological wastewater treatment process in the world. It operates stably, the effluent quality is better, and part of the generated sludge is effectively disposed of in a concentrated form. However, due to the status quo of emphasizing water over sludge and the gradual increase of wastewater treatment rate, residual sludge becomes an unavoidable by-product of the treatment process. This by-product not only significantly increases the total operating cost of wastewater treatment plants, but also carries a large amount of toxic biochemical residues in the environment. The issue of how to treat and dispose of sludge safely and economically has begun to receive attention. The in-situ reduction technology for the simultaneous treatment of wastewater and sludge has many advantages over conventional sludge disposal. Through the analysis and comparison of various treatment technologies of thermal, chemical, mechanical, and other biological processes, their ability to enhance sludge hydrolysis and their advantages and disadvantages are summarized. [ABSTRACT FROM AUTHOR]

Composite laminated plates are made of two or more unidirectional plies (or layers) stacked together at various orientations, the layers are composed of two phases: the fibers and the matrices. The material property and orientation of the fibers inside of the matrix determines the elastic characteristics of the layers. If the conventional layers used to fabricate laminate, there is no elastic coupling between bending and extension, other types of layers (the satins for example) have coupled behaviors. The classical lamination theory (CLT) formulates the elastic behavior of a laminate composed of classical layers, but it should be modified to be able to include these coupled layers that is the aim of the first part of this article. The second aspect of coupled layers must be considered: when they turned over, some of their elastic characteristics change, this phenomenon is studied in a second part and a method is proposed, including the reversal into the CLT equations, give more useful equations describing the laminates made of coupled layers. Finally, some cases of uncoupled and quasi-homogeneous stacking sequences are studied. [ABSTRACT FROM AUTHOR]

The uncoupling protein UCP2 is a mitochondrial carrier for which transport activity remains controversial. The physiological contexts in which UCP2 is expressed have led to the assumption that, like UCP1, it uncouples oxidative phosphorylation and thereby reduces the generation of reactive oxygen species. Other reports have involved UCP2 in the Warburg effect, and results showing that UCP2 catalyzes the export of matrix C4 metabolites to facilitate glutamine utilization suggest that the carrier could be involved in the metabolic adaptations required for cell proliferation. We have examined the role of UCP2 in the energy metabolism of the lung adenocarcinoma cell line A549 and show that UCP2 silencing decreased the basal rate of respiration, although this inhibition was not compensated by an increase in glycolysis. Silencing did not lead to either changes in proton leakage, as determined by the rate of respiration in the absence of ATP synthesis, or changes in the rate of formation of reactive oxygen species. The decrease in energy metabolism did not alter the cellular energy charge. The decreased cell proliferation observed in UCP2-silenced cells would explain the reduced cellular ATP demand. We conclude that UCP2 does not operate as an uncoupling protein, whereas our results are consistent with its activity as a C4-metabolite carrier involved in the metabolic adaptations of proliferating cells. [ABSTRACT FROM AUTHOR]

Highlights: What are the main findings? Hypothesis: Redox, bioenergetic and temperature regulation is critical in maintaining cellular circadian rhythms; wakefulness is mainly "nucleorestorative" and sleep is mainly "mitorestorative". Wakefulness: High metabolic rate induces oxidative stress and redox imbalance. Sleep: Fusion remodels mitochondria and the cellular redox balance is restored. Sleep: Mitochondria aid activation of rapid immune, inflammatory and heat shock responses. What is the implication of the main findings? Sleep-wake cycling: Provides insights into the role of cysteine-mediated redox signaling, uncoupling and substrate cycles. Disorders of human development and aging: Perturbations of circadian tripartite-interactome signaling and mitochondrial-nuclear coregulation are implicated. Although circadian biorhythms of mitochondria and cells are highly conserved and crucial for the well-being of complex animals, there is a paucity of studies on the reciprocal interactions between oxidative stress, redox modifications, metabolism, thermoregulation, and other major oscillatory physiological processes. To address this limitation, we hypothesize that circadian/ultradian interaction of the redoxome, bioenergetics, and temperature signaling strongly determine the differential activities of the sleep–wake cycling of mammalians and birds. Posttranslational modifications of proteins by reversible cysteine oxoforms, S-glutathionylation and S-nitrosylation are shown to play a major role in regulating mitochondrial reactive oxygen species production, protein activity, respiration, and metabolomics. Nuclear DNA repair and cellular protein synthesis are maximized during the wake phase, whereas the redoxome is restored and mitochondrial remodeling is maximized during sleep. Hence, our analysis reveals that wakefulness is more protective and restorative to the nucleus (nucleorestorative), whereas sleep is more protective and restorative to mitochondria (mitorestorative). The "redox–bioenergetics–temperature and differential mitochondrial–nuclear regulatory hypothesis" adds to the understanding of mitochondrial respiratory uncoupling, substrate cycling control and hibernation. Similarly, this hypothesis explains how the oscillatory redox–bioenergetics–temperature–regulated sleep–wake states, when perturbed by mitochondrial interactome disturbances, influence the pathogenesis of aging, cancer, spaceflight health effects, sudden infant death syndrome, and diseases of the metabolism and nervous system. [ABSTRACT FROM AUTHOR]

Toluidine blue O (TBO) is a phenothiazine dye that, due to its photochemical characteristics and high affinity for biomembranes, has been revealed as a new photosensitizer (PS) option for antimicrobial photodynamic therapy (PDT). This points to a possible association with membranous organelles like mitochondrion. Therefore, here we investigated its effects on mitochondrial bioenergetic functions both in the dark and under photostimulation. Two experimental systems were utilized: (a) isolated rat liver mitochondria and (b) isolated perfused rat liver. Our data revealed that, independently of photostimulation, TBO presented affinity for mitochondria. Under photostimulation, TBO increased the protein carbonylation and lipid peroxidation levels (up to 109.40 and 119.87%, respectively) and decreased the reduced glutathione levels (59.72%) in mitochondria. TBO also uncoupled oxidative phosphorylation and photoinactivated the respiratory chain complexes I, II, and IV, as well as the FoF1-ATP synthase complex. Without photostimulation, TBO caused uncoupling of oxidative phosphorylation and loss of inner mitochondrial membrane integrity and inhibited very strongly succinate oxidase activity. TBO's uncoupling effect was clearly seen in intact livers where it stimulated oxygen consumption at concentrations of 20 and 40 μM. Additionally, TBO (40 μM) reduced cellular ATP levels (52.46%) and ATP/ADP (45.98%) and ATP/AMP (74.17%) ratios. Consequently, TBO inhibited gluconeogenesis and ureagenesis whereas it stimulated glycogenolysis and glycolysis. In conclusion, we have revealed for the first time that the efficiency of TBO as a PS may be linked to its ability to photodynamically inhibit oxidative phosphorylation. In contrast, TBO is harmful to mitochondrial energy metabolism even without photostimulation, which may lead to adverse effects when used in PDT. [ABSTRACT FROM AUTHOR]

Background: Intrarenal hypoxia has been suggested a unifying pathway to chronic kidney disease (CKD) and increased mitochondria leak respiration, which increases mitochondrial oxygen usage and is one important mechanism contributing to the development of the hypoxia. Previous studies indicate that angiotensin II (Ang II) effects on mitochondria function could be dose dependent. We investigated how moderate and high levels of Ang II affect kidney mitochondria function and pathways of leak respiration. Methods: C57 black 6 mice were treated with either vehicle or Ang II in low dose (400 ng/kg/min) or high dose (1,000 ng/kg/min) for 4 weeks. The function of kidney cortex mitochondria was measured by high-resolution respirometry. Ang II effects on gene expression in kidney tissue were measured by quantitative real-time PCR. Thiobarbituric acids reactive substances were determined as a marker of oxidative stress, and urinary protein excretion was measured as a maker of kidney injury. Results: Low-dose Ang II induced overall mitochondria respiration, without compromising capacity of ATP production. Mitochondrial leak respiration was increased, and levels of oxidative stress were unchanged. However, high-dose Ang II decreased overall mitochondria respiration and reduced mitochondrial capacity for ATP production. Mitochondrial leak respiration was decreased, and oxidative stress increased in kidney tissue. Furthermore, gene expression of mediators that stimulate vasoconstriction and ROS production was increased, while components of counteracting pathways were decreased. Conclusions: In conclusion, Ang II dose-dependently affects mitochondrial function and leak respiration. Thus, Ang II has the potential to directly affect cellular metabolism during conditions of altered Ang II signaling. [ABSTRACT FROM AUTHOR]

The isothiourea derivative NT-1505 is known as a neuroprotector and cognition enhancer in animal models of neurodegenerative diseases. Bearing in mind possible relation of the NT-1505-mediated neuroprotection to mitochondrial uncoupling activity, here, we examine NT-1505 effects on mitochondria functioning. At concentrations starting from 10 μM, NT-1505 prevented Ca2+-induced mitochondrial swelling, similar to common uncouplers. Alongside the inhibition of the mitochondrial permeability transition, NT-1505 caused a decrease in mitochondrial membrane potential and an increase in respiration rate in both isolated mammalian mitochondria and cell cultures, which resulted in the reduction of energy-dependent Ca2+ uptake by mitochondria. Based on the oppositely directed effects of bovine serum albumin and palmitate, we suggest the involvement of fatty acids in the NT-1505–mediated mitochondrial uncoupling. In addition, we measured the induction of electrical current across planar bilayer lipid membrane upon the addition of NT-1505 to the bathing solution. Importantly, introduction of the palmitic acid into the lipid bilayer composition led to weak proton selectivity of the NT-1505-mediated BLM current. Thus, the present study revealed an ability of NT-1505 to cause moderate protonophoric uncoupling of mitochondria, which could contribute to the neuroprotective effect of this compound. [Display omitted] • The isothiourea neuroprotector NT-1505 prevents Ca2+-induced mitochondrial swelling. • NT-1505 decreases mitochondrial membrane potential and stimulates oxygen consumption. • Palmitate renders NT-1505-induced electric current across BLM weakly proton-selective. • Fatty acids are probably involved in the NT-1505-mediated mitochondrial uncoupling. • Protonophoric uncoupling of mitochondria may contribute to its neuroprotective effect. [ABSTRACT FROM AUTHOR]

Flavonols are found in plants as aglycones and as glycosides. Antioxidant activity of flavonols may occur via several mechanisms within the cell, and mitochondria as a target may play an important role. There is a lack of information about the influence of the sugar moiety on biological activity of flavonoid glycosides. The aims of study were to investigate the effects of quercetin and its glycosides on mitochondrial respiration rates at various metabolic states, and to evaluate their antioxidant potential using chemical and biological approaches. Mitochondrial function was measured using an oxygraphic method, cytochrome c reduction spectrophotometrically, H2O2 generation in mitochondria fluorimetrically, and antioxidant activity of flavonoids using an HPLC-post column system. Our data revealed that quercetin and its glycosides isoquercitrin, rutin, and hyperoside uncouple kidney mitochondrial respiration (increasing the State 2 respiration rate) and significantly reduce cytochrome c. Moreover, quercetin, and its glycosides decrease the production of mitochondrial H2O2 and possess radical scavenging and ferric reducing capacities. The highest activity was characteristic for quercetin, showing that the sugar moiety significantly diminishes its activity. In conclusion, our results show the efficient radical scavenging, ferric and cytochrome c reducing capacities, and uncoupling properties of quercetin and its glycosides, as well as the importance of the sugar residue and its structure in the regulation of kidney mitochondrial function. [ABSTRACT FROM AUTHOR]

Understanding temperature production and regulation in endotherm organisms becomes a crucial challenge facing the increased frequency and intensity of heat strokes related to global warming. Mitochondria, located at the crossroad of metabolism, respiration, Ca2+ homeostasis, and apoptosis, were recently proposed to further act as cellular radiators, with an estimated inner temperature reaching 50 °C in common cell lines. This inner thermogenesis might be further exacerbated in organs devoted to produce consistent efforts as muscles, or heat as brown adipose tissue, in response to acute solicitations. Consequently, pathways promoting respiratory chain uncoupling and mitochondrial activity, such as Ca2+ fluxes, uncoupling proteins, futile cycling, and substrate supplies, provide the main processes controlling heat production and cell temperature. The mitochondrial thermogenesis might be further amplified by cytoplasmic mechanisms promoting the over-consumption of ATP pools. Considering these new thermic paradigms, we discuss here all conventional wisdoms linking mitochondrial functions to cellular thermogenesis in different physiological conditions. [ABSTRACT FROM AUTHOR]

There has been a previous case report of peri-arrest muscle rigidity in the setting of severe salicylate poisoning (serum salicylate concentration 1,500 mg/L), described as paratonia or rapid rigor mortis. We present an image of rapid rigor mortis in another fatal salicylate poisoning. We report a 42-year-old male with severe salicylate poisoning (peak salicylate concentration 1,600 mg/L). During the peri-arrest period, the patient developed isotonic flexion of the upper and lower extremities, the clinical signs of rapid-occurring rigor mortis. Despite resuscitative efforts, the patient died. Our patient is exhibiting peri-arrest rigidity in the upper extremities. Peri-mortem rigidity is due to depletion of adenosine triphosphate. Severe salicylate poisoning causes uncoupling of oxidative phosphorylation which prevents the production of adenosine triphosphate, which is required to release myosin from actin to allow the muscle to relax. A limitation of our report is that we did not definitively exclude other uncouplers of oxidative phosphorylation, such as 2,4-dinitrophenol. However, the history of aspirin ingestion was provided by the patient and corroborated by his mother, and it was confirmed by measurement of his salicylate concentration. We hypothesize that in our patient, rapid-occurring rigor mortis likely resulted from depletion of adenosine triphosphate. This occurred as a result of uncoupling of oxidative phosphorylation in the mitochondria from severe salicylate poisoning, as adenosine triphosphate is required for muscle relaxation. [ABSTRACT FROM AUTHOR]

The paper considers the issue of evaluating the impact of different types of uncoupling to increase the processing capacity of hump yards to ensure high technical-economic indicators in the conditions of limited capital funds. Moreover it describes the mathematical formulation of the sorting slide. For the mathematical formulation, the sorting slide is taken as a surface that is uniquely projected onto a horizontal plane. Based on the results of calculations, more accurate data on the speeds of movement along the downhill part of the slide are determined. This data is compared with experimental results. [ABSTRACT FROM AUTHOR]

Oxidative stress plays an important role in the formation of abdominal aortic aneurysm (AAA), and we have recently established a causal role of uncoupled eNOS in this severe human disease. We have also shown that activation of NADPH oxidase (NOX) lies upstream of uncoupled eNOS. Therefore, identification of the specific NOX isoforms that are required for eNOS uncoupling and AAA formation would ultimately lead to novel therapies for AAA. In the present study, we used the Ang II infused hph-1 mice to examine the roles of NOX isoforms in the development of AAA. We generated double mutants of hph-1-NOX1, hph-1-NOX2, hph-1-p47phox, and hph-1-NOX4. After two weeks of Ang II infusion, the incidence rate of AAA substantially dropped from 76.5% in Ang II infused hph-1 mice (n=34) to 11.1%, 15.0%, 9.5% and 0% in hph-1-NOX1 (n=27), hph-1-NOX2 (n=40), hph-1-p47phox (n=21), and hph-1-NOX4 (n=33) double mutant mice, respectively. The size of abdominal aortas of the four double mutant mice, determined by ultrasound analyses, was significantly smaller than the hph-1 mice. Aortic nitric oxide and H4B bioavailabilities were markedly improved in the double mutants, while superoxide production and eNOS uncoupling activity were substantially diminished. These effects seemed attributed to an endothelial specific restoration of dihydrofolate reductase expression and activity, deficiency of which has been shown to induce eNOS uncoupling and AAA formation in both Ang II-infused hph-1 and apoE null animals. In addition, over-expression of human NOX4 N129S or T555S mutant newly identified in aneurysm patients increased hydrogen peroxide production, further implicating a relationship between NOX and human aneurysm. Taken together, these data indicate that NOX isoforms 1, 2 or 4 lies upstream of dihydrofolate reductase deficiency and eNOS uncoupling to induce AAA formation. These findings may promote development of novel therapeutics for the treatment of the disease by inhibiting NOX signaling.

Membrane bioreactor (MBR) technology has been paid extensive attention for wastewater treatment because of its advantages of high effluent quality and minimized occupation space and sludge production. However, the membrane fouling is always an inevitable problem, which causes high operation and maintenance costs and prevents the wide use of MBR technology. The membrane biofouling is the most complicated and has relatively slow progress among all types of fouling. In recent years, many membrane biofouling control methods have been developed. Different from the physical or chemical methods, the biological-based strategies are not only more effective for membrane biofouling control, but also milder and more environment-friendly and, therefore, have been increasingly employed. This paper mainly focuses on the mechanism, unique advantages and development of biological-based control strategies for MBR membrane biofouling such as quorum quenching, uncoupling, flocculants and so on. The paper summarizes the up-to-date development of membrane biofouling control strategies, emphasizes the advantages and promising potential of biological-based ones, and points out the direction for future studies. HIGHLIGHTS Membrane biofouling is the most complicated among all types of membrane fouling.; New physical and chemical methods may hurt membranes and environment.; Cheaper enzyme extraction methods for enzymatic control of membrane biofouling need to be introduced.; Environmental conditions and cost are the main limitations of biological strategies.; The effects of biological methods on the microbial ecology need to be explored.;

Obesity is a global health challenge with limited therapeutic solutions. Here, we demonstrate the engineering of an energy-dissipating hybrid tissue (EDHT) in the body for weight control. EDHT is constructed by implanting a synthetic gel matrix comprising immunomodulatory signals and functional cells into the recipient mouse. The immunomodulatory signals induce the host stromal cells to create an immunosuppressive niche that protects the functional cells, which are overexpressing the uncoupling protein 1 (UCP1), from immune rejection. Consequently, these endogenous and exogenous cells co-develop a hybrid tissue that sustainedly produces UCP1 to accelerate the host's energy expenditure. Systematic experiments in high-fat diet (HFD) and transgenic (ob/ob) mice show that EDHT efficiently reduces body weight and relieves obesity-associated pathological conditions. Importantly, an 18-month observation for safety assessment excludes cell leakage from EDHT and reports no adverse physiological responses. Overall, EDHT demonstrates convincing efficacy and safety in controlling body weight. [Display omitted] • Human A549 cells expressing UCP1 perform uncoupled respiration • KSP in the alginate-gelatin induces immunosuppression and ECM production • A549-UCP1 cells and the matrix form an energy-dissipating hybrid tissue • EDHT reduces fat and relieves obesity-associated pathological conditions Wang et al. show the construction of an energy-dissipating hybrid tissue (EDHT) in vivo. EDHT demonstrates high efficacy in managing body weight and safety in mice, representing another strategy for potential anti-obesity therapy. [ABSTRACT FROM AUTHOR]

The present work shows that the rate of free respiration of liver mitochondria (in the absence of ATP synthesis (state 4) during the oxidation of succinate is 1.7 times higher than during the oxidation of glutamate with malate. In turn, in the case of oxidation of ferrocyanide with ascorbate, this value is 3.1 times greater than in the case of succinate oxidation. A similar pattern is also observed upon stimulation of free respiration by low concentrations (5 and 10 μM) of the protonophore uncoupler 2,4-dinitrophenol (DNP). It is found that the passive leakage rate of protons in state 4 is the same if the H+/O ratios are 10, 6, and 2 upon the oxidation of glutamate with malate, succinate, and ferrocyanide with ascorbate, respectively. At these values of the H+/O ratio, low concentrations of DNP stimulate passive proton leakage equally during the oxidation of these respiration substrates. In the case of succinate oxidation, bypassing complex III by N,N,N′,N′-tetramethyl- p -phenylenediamine (TMPD) to the maximum degree, as well as switching this complex completely to idle mode by α,ω-hexadecanedioic acid (HDA) cause a 3-fold stimulation of respiration in state 4. We conclude that at mitochondrial free respiration the values of the H+/2e− ratio for complexes I, III, and IV of the respiratory chain are 4, 4, and 2, respectively. It is assumed that the free respiration of mitochondria is carried out by simple diffusion of protons through the inner membrane, and the rate of this diffusion depends on the total number of protons released by the complexes of the electron transport chain into the intermembrane space. • Mitochondrial free respiration rate depends on the ETC complexes involved in energy transformation. • TMPD and HDA cause 3-fold stimulation of state 4 respiration of succinate-fueled mitochondria. • At mitochondrial free respiration H+/2e– for complexes I, III, and IV are 4, 4, and 2, respectively. • Free respiration is based on simple diffusion of H+ across the inner membrane. • The diffusion rate depends on the number of H+ released by ETC into the intermembrane space. [ABSTRACT FROM AUTHOR]

Mitochondria of all tissues convert various metabolic substrates into two forms of energy: ATP and heat. Historically, the primary focus of research in mitochondrial bioenergetics was on the mechanisms of ATP production, while mitochondrial thermogenesis received significantly less attention. Nevertheless, mitochondrial heat production is crucial for the maintenance of body temperature, regulation of the pace of metabolism, and prevention of oxidative damage to mitochondria and the cell. In addition, mitochondrial thermogenesis has gained significance as a pharmacological target for treating metabolic disorders. Mitochondria produce heat as the result of H+ leak across their inner membrane. This review provides a critical assessment of the current field of mitochondrial H+ leak and thermogenesis, with a focus on the molecular mechanisms involved in the function and regulation of uncoupling protein 1 and the ADP/ATP carrier, the two proteins that mediate mitochondrial H+ leak. [ABSTRACT FROM AUTHOR]

Background: Alzheimer's disease (AD) is the most common cause of dementia worldwide, with apolipoprotein Eε4 (APOEε4) being the strongest genetic risk factor. Current clinical diagnostic imaging focuses on amyloid and tau; however, new methods are needed for earlier detection., Methods: PET imaging was used to assess metabolism-perfusion in both sexes of aging C57BL/6J, and hAPOE mice, and were verified by transcriptomics, and immunopathology., Results: All hAPOE strains showed AD phenotype progression by 8 months, with females exhibiting the regional changes, which correlated with GO-term enrichments for glucose metabolism, perfusion, and immunity. Uncoupling analysis revealed APOEε4/ε4 exhibited significant Type-1 uncoupling (↓ glucose uptake, ↑ perfusion) at 8 and 12 months, while APOEε3/ε4 demonstrated Type-2 uncoupling (↑ glucose uptake, ↓ perfusion), while immunopathology confirmed cell specific contributions., Discussion: This work highlights APOEε4 status in AD progression manifests as neurovascular uncoupling driven by immunological activation, and may serve as an early diagnostic biomarker., Highlights: We developed a novel analytical method to analyze PET imaging of 18 F-FDG and 64 Cu-PTSM data in both sexes of aging C57BL/6J, and hAPOEε3/ε3, hAPOEε4/ε4, and hAPOEε3/ε4 mice to assess metabolism-perfusion profiles termed neurovascular uncoupling. This analysis revealed APOEε4/ε4 exhibited significant Type-1 uncoupling (decreased glucose uptake, increased perfusion) at 8 and 12 months, while APOEε3/ε4 demonstrated significant Type-2 uncoupling (increased glucose uptake, decreased perfusion) by 8 months which aligns with immunopathology and transcriptomic signatures. This work highlights that there may be different mechanisms underlying age related changes in APOEε4/ε4 compared with APOEε3/ε4. We predict that these changes may be driven by immunological activation and response, and may serve as an early diagnostic biomarker., (© 2024 The Authors. Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.)

This paper examines the uncoupling effect of ω-hydroxypalmitic acid (HPA) on liver mitochondria energized by oxidation of succinate. It was shown that HPA more effectively stimulates respiration of mitochondria in the case of incubation in a medium containing potassium chloride, which indicates the ability of HPA to exert an ionophore effect on mitochondria associated with the transport of potassium and/or Tris ions into the matrix of organelles. It was suggested that the phosphate carrier of the inner mitochondrial membrane can be involved in the ionophore action of HPA. We have shown that inorganic phosphate (Pi), a phosphate carrier substrate, has a significant inhibitory effect on HPA-induced stimulation of respiration in liver mitochondria. In addition, Pi inhibits HPA-induced swelling of organelles caused by the transport of potassium and/or Tris ions into the mitochondrial matrix and also reduces the efficiency of HPA as an inducer of a decrease in the transmembrane potential (Δψ) of liver mitochondria. The inhibitors of the phosphate carrier, N-ethylmaleimide (NEM) and iminodi(methylene)phosphonate (IDMP), have a similar effect. It was shown that, upon stimulation of mitochondrial respiration by 30 μM HPA, the recoupling effects of Pi, NEM, and IDMP are 71 ± 8.3%, 56 ± 6.1%, and 34 ± 2.7%, respectively. Noteworthy, these ligands of the phosphate carrier have no effect on the protonophore effect of HPA. Thus, we conclude that the phosphate carrier of liver mitochondria takes part in the ionophore action of HPA, possibly facilitating the transfer of the HPA anion from the inner monolayer of the inner membrane to its outer monolayer. [ABSTRACT FROM AUTHOR]

Hydrophobic molecules may be toxic when present in excess. When dissolved in membranes, hydrophobic molecules disrupt membrane function. Studies on the effects of free fatty acids (FFA) on cultured cells contradict each other. Here we describe the effects of FFA on various human cells in culture. The addition of long-chain FFA (oleic, palmitic, linoleic, linolenic, etc.) to cultured cells led to lipid accumulation in hepatocytes and muscle cells, initiation of autophagy, and uncoupling of oxidative phosphorylation. Although treated cells increase their oxygen consumption, metabolic shifts in favor of glycolysis were observed. All these effects were expressed to varying degrees in different cells and with the addition of different FFAs. The mechanisms of these FFA effects are discussed, as well their practical implications. [ABSTRACT FROM AUTHOR]

In this paper we use simulation methods to study a hypothetical uncoupling agent as a therapy for dementia. We simulate the proliferation of mitochondrial deletion mutants amongst a population of wild-type in human neurons. Mitochondria play a key role in ATP generation. Clonal expansion can lead to the wild-type being overwhelmed by deletions such that a diminished population can no longer fulfil a cell's energy requirement, eventually leading to its demise. The intention of uncoupling is to reduce the formation of deletion mutants by reducing mutation rate. However, a consequence of uncoupling is that the energy production efficacy is also reduced which in turn increases wild-type copy number in order to compensate for the energy deficit. The results of this paper showed that uncoupling reduced the severity of dementia, however, there was some increase in cognitive dysfunction pre-onset of dementia. The effectiveness of uncoupling was dependent upon the timing of intervention relative to the onset of dementia and would necessitate predicting its onset many years in advance. [ABSTRACT FROM AUTHOR]

Cytochrome P450 mediated substrate metabolism is generally characterized by the formation of reactive intermediates. In vitro and in vivo reaction uncoupling, results in the accumulation and dissociation of reactive intermediates, leading to increased ROS formation. The susceptibility towards uncoupling and altered metabolic activity is partly modulated by pharmacogenomic alleles resulting in amino acid substitutions. A large variability in the prevalence of these alleles has been demonstrated in CYP2B6, with some being predominantly unique to African populations. The aim of this study is to characterize the uncoupling potential of recombinant CYP2B6*1, CYP2B6*6 and CYP2B6*34 metabolism of specific substrates. Therefore, functional effects of these alterations on enzyme activity were determined by quantification of bupropion, efavirenz and ketamine biotransformation using HPLC-MS/MS. Determination of H 2 O 2 levels was performed by the AmplexRed/horseradish peroxidase assay. Our studies of the amino acid substitutions Q172H, K262R and R487S revealed an exclusive use of the peroxide shunt for the metabolism of bupropion and ketamine by CYP2B6*K262R. Ketamine was also identified as a trigger for the peroxide shunt in CYP2B6*1 and all variants. Concurrently, ketamine acted as an uncoupler for all enzymes. We further showed that the expressed CYP2B6*34 allele results in the highest H 2 O 2 formation. We therefore conclude that the reaction uncoupling and peroxide shunt are directly linked and can be substrate specifically induced with K262R carriers being most likely to use the peroxide shunt and R487S carrier being most prone to reaction uncoupling. This elucidates the functional diversity of pharmacogenomics in drug metabolism and safety. [Display omitted] • CYP2B6*6 enzyme shows greater bupropion metabolism in vitro compared to CYP2B6*1. • CYP2B6*6 and CYP2B6*34 enzymes show higher H2O2 production in vitro. • H 2 O 2 production is reduced in presence of bupropion and ketamine, not efavirenz. • K262R and R487S subsitutions are more prone to use the H 2 O 2 -shunt. • Ketamine induces the metabolism via the H2O2-shunt in CYP2B6*1 and CYP2B6 variants. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSCs) are multipotent adult stem cells which have become popular research targets for their use in cellular therapy for tissue repair. While recent advancements in research have shown the MSCs have immunomodulatory functions which are altered in response to host inflammatory molecules, how these stimuli produce different functional outcomes is not understood. Here, we evaluate research examining how the proinflammatory cytokine interferon-γ (IFN-γ) affects the immunomodulatory functions of MSCs by altering their metabolism. This study indicates that IFN-γ causes an increase in glycolytic activity and uncoupling of glycolysis to tricarboxylic acid cycle and hence, the glycolytic metabolites and intermediates can be funneled toward the production of anti-inflammatory modulators indoleamine-2,3-dioxygenase and PGE2. A complete understanding of how MSCs' cellular metabolism affects their function is necessary for their employment in cellular therapy, as MSCs have been demonstrated to have pro- and anti-inflammatory functions. These findings are a large step forward in the understanding of the regulation of MSCs and toward their eventual use in cellular therapy, specifically for stroke recovery, in which MSCs have been shown to have powerful neuroprotective and neurogenerative effects.

Hypermetabolism following severe burn injuries is associated with adipocyte dysfunction, elevated beige adipocyte formation, and increased energy expenditure. The resulting catabolism of adipose leads to detrimental sequelae such as fatty liver, increased risk of infections, sepsis, and even death. While the phenomenon of pathological white adipose tissue (WAT) browning is well‐documented in cachexia and burn models, the molecular mechanisms are essentially unknown. Here, we report that adipose triglyceride lipase (ATGL) plays a central role in burn‐induced WAT dysfunction and systemic outcomes. Targeting adipose‐specific ATGL in a murine (AKO) model resulted in diminished browning, decreased circulating fatty acids, and mitigation of burn‐induced hepatomegaly. To assess the clinical applicability of targeting ATGL, we demonstrate that the selective ATGL inhibitor atglistatin mimics the AKO results, suggesting a path forward for improving patient outcomes. [ABSTRACT FROM AUTHOR]

Exercise often causes skeletal muscle hyperthermia, likely resulting in decreased efficiency of mitochondrial respiration. We hypothesized that athletic conditioning would improve mitochondrial tolerance to hyperthermia. Skeletal muscle biopsies were obtained from six Alaskan sled dogs under light general anesthesia before and after a full season of conditioning and racing, and respiration of permeabilized muscle fibers was measured at 38, 40, 42, and 44 °C. There was no effect of temperature on phosphorylating respiration, and athletic conditioning increased maximal phosphorylating respiration by 19%. Leak respiration increased and calculated efficiency of oxidative phosphorylation decreased with increasing incubation temperature, and athletic conditioning resulted in higher leak respiration and lower calculated oxidative phosphorylation efficiency at all temperatures. Conditioning increased skeletal muscle expression of putative mitochondrial leak pathways adenine nucleotide transporter 1 and uncoupling protein 3, both of which were correlated with the magnitude of leak respiration. We conclude that athletic conditioning in elite canine endurance athletes results in increased capacity for mitochondrial proton leak that potentially reduces maximal mitochondrial membrane potential during periods of high oxidative phosphorylation. This effect may provide a mechanistic explanation for previously reported decreases in exercise-induced muscle damage in well-conditioned subjects. [ABSTRACT FROM AUTHOR]

It has been assumed that at the whole organismal level, the mitochondrial reactive oxygen species (ROS) production is proportional to the oxygen consumption. Recently, a number of researchers have challenged this assumption, based on the observation that the ROS production per unit oxygen consumed in the resting state of mitochondrial respiration is much higher than that in the active state. Here, we develop a simple model to investigate the validity of the assumption and the challenge of it. The model highlights the significance of the time budget that mitochondria operate in the different respiration states. The model suggests that under three physiologically possible conditions, the difference in ROS production per unit oxygen consumed between the respiration states does not upset the proportionality between the whole animal ROS production and oxygen consumption. The model also shows that mitochondrial uncoupling generally enhances the proportionality. [ABSTRACT FROM AUTHOR]

Aims Ketones have been proposed to be a 'thrifty' fuel for the heart and increasing cardiac ketone oxidation can be cardioprotective. However, it is unclear how much ketone oxidation can contribute to energy production in the heart, nor whether increasing ketone oxidation increases cardiac efficiency. Therefore, our goal was to determine to what extent high levels of the ketone body, β-hydroxybutyrate (βOHB), contributes to cardiac energy production, and whether this influences cardiac efficiency. Methods and results Isolated working mice hearts were aerobically perfused with palmitate (0.8 mM or 1.2 mM), glucose (5 mM) and increasing concentrations of βOHB (0, 0.6, 2.0 mM). Subsequently, oxidation of these substrates, cardiac function, and cardiac efficiency were assessed. Increasing βOHB concentrations increased myocardial ketone oxidation rates without affecting glucose or fatty acid oxidation rates where normal physiological levels of glucose (5 mM) and fatty acid (0.8 mM) are present. Notably, ketones became the major fuel source for the heart at 2.0 mM βOHB (at both low or high fatty acid concentrations), with the elevated ketone oxidation rates markedly increasing tricarboxylic acid (TCA) cycle activity, producing a large amount of reducing equivalents and finally, increasing myocardial oxygen consumption. However, the marked increase in ketone oxidation at high concentrations of βOHB was not accompanied by an increase in cardiac work, suggesting that a mismatch between excess reduced equivalents production from ketone oxidation and cardiac adenosine triphosphate production. Consequently, cardiac efficiency decreased when the heart was exposed to higher ketone levels. Conclusions We demonstrate that while ketones can become the major fuel source for the heart, they do not increase cardiac efficiency, which also underscores the importance of recognizing ketones as a major fuel source for the heart in times of starvation, consumption of a ketogenic diet or poorly controlled diabetes. [ABSTRACT FROM AUTHOR]

Key points: The oxygen cost of high‐intensity exercise at power outputs above an individual's lactate threshold (LT) is greater than would be predicted by the linear oxygen consumption‐power relationship observed below the LT. However, whether these augmentations are caused by an increased ATP cost of force generation (ATPCOST) or an increased oxygen cost of ATP synthesis is unclear.We used 31P‐MRS to measure changes in cytosolic [ADP] (intramyocellular marker of oxidative metabolism), oxidative ATP synthesis (ATPOX) and ATPCOST during a 6‐stage, stepwise knee extension protocol.ATPCOST was unchanged across stages. The relationship between [ADP] and muscle power output was augmented at workloads above the pH threshold (pHT; proxy for LT), whereas increases in ATPOX were attenuated.These results suggest the greater oxygen cost of contractions at workloads beyond the pHT is not caused by mechanisms that increase ATPCOST, but rather mechanisms that alter intrinsic mitochondrial function or capacity. Increases in skeletal muscle metabolism and oxygen consumption are linearly related to muscle power output for workloads below the lactate threshold (LT), but are augmented (i.e. greater rate of increase relative to workload) thereafter. Presently, it is unclear whether these metabolic augmentations are caused by increases in the ATP cost of force generation (ATPCOST) or changes in the efficiency of mitochondrial oxygen consumption and oxidative ATP synthesis (ATPOX). To partition these two hypotheses in vivo, we used 31P‐MRS to calculate slopes relating step‐changes in muscle work to concurrent changes in cytosolic phosphates and ATPOX before and after the pH threshold (pHT; used here as a proxy for LT) within the vastus lateralis muscle of eight young adults during a stepwise knee extension test. Changes in muscle phosphates and ATPOX were linearly related to workload below the pHT. However, slopes above the pHT were greater for muscle phosphates (P < 0.05) and lower for ATPOX (P < 0.05) than were the slopes observed below the pHT. The maximal capacity for ATPOX (V̇max) and ADP‐specific ATPOX also declined beyond the pHT (P < 0.05), whereas ATPCOST was unchanged (P = 0.10). These results oppose the hypothesis that high‐intensity contractions increase ATPCOST and suggest that greater oxidative metabolism at workloads beyond the pHT is caused by mechanisms that affect intrinsic mitochondrial function or capacity, such as alterations in substrate selection or electron entry into the electron transport chain, temperature‐mediated changes in mitochondrial permeability to protons, or stimulation of mitochondrial uncoupling by reactive oxygen species generation. Key points: The oxygen cost of high‐intensity exercise at power outputs above an individual's lactate threshold (LT) is greater than would be predicted by the linear oxygen consumption‐power relationship observed below the LT. However, whether these augmentations are caused by an increased ATP cost of force generation (ATPCOST) or an increased oxygen cost of ATP synthesis is unclear.We used 31P‐MRS to measure changes in cytosolic [ADP] (intramyocellular marker of oxidative metabolism), oxidative ATP synthesis (ATPOX) and ATPCOST during a 6‐stage, stepwise knee extension protocol.ATPCOST was unchanged across stages. The relationship between [ADP] and muscle power output was augmented at workloads above the pH threshold (pHT; proxy for LT), whereas increases in ATPOX were attenuated.These results suggest the greater oxygen cost of contractions at workloads beyond the pHT is not caused by mechanisms that increase ATPCOST, but rather mechanisms that alter intrinsic mitochondrial function or capacity. [ABSTRACT FROM AUTHOR]