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Riccardi K, Ryu S, Tess D, Li R, Luo L, Johnson N, Jordan S, Patel R, Di L. Comparison of Fraction Unbound Between Liver Homogenate and Hepatocytes at 4°C. AAPS JOURNAL 2020; 22:91. [DOI: 10.1208/s12248-020-00476-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/26/2020] [Indexed: 01/18/2023]
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Zhang R, Wang Y, Ye K, Picard M, Gu Z. Independent impacts of aging on mitochondrial DNA quantity and quality in humans. BMC Genomics 2017; 18:890. [PMID: 29157198 PMCID: PMC5697406 DOI: 10.1186/s12864-017-4287-0] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 11/08/2017] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND The accumulation of mitochondrial DNA (mtDNA) mutations, and the reduction of mtDNA copy number, both disrupt mitochondrial energetics, and may contribute to aging and age-associated phenotypes. However, there are few genetic and epidemiological studies on the spectra of blood mtDNA heteroplasmies, and the distribution of mtDNA copy numbers in different age groups and their impact on age-related phenotypes. In this work, we used whole-genome sequencing data of isolated peripheral blood mononuclear cells (PBMCs) from the UK10K project to investigate in parallel mtDNA heteroplasmy and copy number in 1511 women, between 17 and 85 years old, recruited in the TwinsUK cohorts. RESULTS We report a high prevalence of pathogenic mtDNA heteroplasmies in this population. We also find an increase in mtDNA heteroplasmies with age (β = 0.011, P = 5.77e-6), and showed that, on average, individuals aged 70-years or older had 58.5% more mtDNA heteroplasmies than those under 40-years old. Conversely, mtDNA copy number decreased by an average of 0.4 copies per year (β = -0.395, P = 0.0097). Multiple regression analyses also showed that age had independent effects on mtDNA copy number decrease and heteroplasmy accumulation. Finally, mtDNA copy number was positively associated with serum bicarbonate level (P = 4.46e-5), and inversely correlated with white blood cell count (P = 0.0006). Moreover, the aggregated heteroplasmy load was associated with blood apolipoprotein B level (P = 1.33e-5), linking the accumulation of mtDNA mutations to age-related physiological markers. CONCLUSIONS Our population-based study indicates that both mtDNA quality and quantity are influenced by age. An open question for the future is whether interventions that would contribute to maintain optimal mtDNA copy number and prevent the expansion of heteroplasmy could promote healthy aging.
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Affiliation(s)
- Ruoyu Zhang
- Division of Nutritional Sciences, Cornell University, Ithaca, NY, 14853, USA
| | - Yiqin Wang
- Division of Nutritional Sciences, Cornell University, Ithaca, NY, 14853, USA
| | - Kaixiong Ye
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Martin Picard
- Department of Psychiatry, Division of Behavioral Medicine, Department of Neurology and Columbia Translational Neuroscience Initiative, Columbia Aging Center, Columbia University Medical Center, New York, NY, 10032, USA
| | - Zhenglong Gu
- Division of Nutritional Sciences, Cornell University, Ithaca, NY, 14853, USA.
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Abstract
Hypothermia, along with acidosis and coagulopathy, is part of the lethal triad that worsen the prognosis of severe trauma patients. While accidental hypothermia is easy to identify by a simple measurement, it is no less pernicious if it is not detected or treated in the initial phase of patient care. It is a multifactorial process and is a factor of mortality in severe trauma cases. The consequences of hypothermia are many: it modifies myocardial contractions and may induce arrhythmias; it contributes to trauma-induced coagulopathy; from an immunological point of view, it diminishes inflammatory response and increases the chance of pneumonia in the patient; it inhibits the elimination of anaesthetic drugs and can complicate the calculation of dosing requirements; and it leads to an over-estimation of coagulation factor activities. This review will detail the pathophysiological consequences of hypothermia, as well as the most recent principle recommendations in dealing with it.
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Affiliation(s)
- Fanny Vardon
- Équipe d'accueil « Modélisation de l'agression tissulaire et nociceptive », Toulouse University Teaching Hospital, Université Toulouse III Paul-Sabatier, Hôpital Pierre-Paul-Riquet, CHU de Toulouse, place du Dr-Baylac, 31059 Toulouse cedex 09, France
| | - Ségolène Mrozek
- Équipe d'accueil « Modélisation de l'agression tissulaire et nociceptive », Toulouse University Teaching Hospital, Université Toulouse III Paul-Sabatier, Hôpital Pierre-Paul-Riquet, CHU de Toulouse, place du Dr-Baylac, 31059 Toulouse cedex 09, France
| | - Thomas Geeraerts
- Équipe d'accueil « Modélisation de l'agression tissulaire et nociceptive », Toulouse University Teaching Hospital, Université Toulouse III Paul-Sabatier, Hôpital Pierre-Paul-Riquet, CHU de Toulouse, place du Dr-Baylac, 31059 Toulouse cedex 09, France.
| | - Olivier Fourcade
- Équipe d'accueil « Modélisation de l'agression tissulaire et nociceptive », Toulouse University Teaching Hospital, Université Toulouse III Paul-Sabatier, Hôpital Pierre-Paul-Riquet, CHU de Toulouse, place du Dr-Baylac, 31059 Toulouse cedex 09, France
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Culcasi M, Thétiot-Laurent S, Atteia A, Pietri S. Mitochondrial, acidic, and cytosolic pHs determination by ³¹P NMR spectroscopy: design of new sensitive targeted pH probes. Methods Mol Biol 2015; 1265:135-147. [PMID: 25634273 DOI: 10.1007/978-1-4939-2288-8_11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
(31)P nuclear magnetic resonance (NMR) is a unique technique to monitor noninvasively the energetics of living systems at real time through the detection of a variety of phosphorylated metabolites. Using adequately designed α-aminophosphonates as external probes, we have shown earlier that (31)P NMR can also give access simultaneously to the accurate pH of cytosolic and acidic compartments in normal and stressed cultured cells or isolated perfused organs, a feature that was not possible using endogenous inorganic phosphate as the probe. More recently, we obtained a series of derivatives of these new pH probes that incorporate a triphenylphosphonium cation as a specific vector to the mitochondrion. Here, we describe the synthesis, (31)P NMR pH titrating properties in buffers, and application in cultures of the green alga Chlamydomonas reinhardtii of two of these mitochondria-targeted pH probes in comparison with one nonvectorized, yet still informative α-aminophosphonate.
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Affiliation(s)
- Marcel Culcasi
- UMR 7273, CNRS, Equipe Sondes Moléculaires en Biologie et Stress Oxydant, Centre scientifique de Saint-Jérôme, Institut de Chimie Radicalaire, Aix-Marseille Université, Service 522, Avenue Escadrille Normandie-Niemen, Marseille Cedex 20, 13397, France
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Culcasi M, Casano G, Lucchesi C, Mercier A, Clément JL, Pique V, Michelet L, Krieger-Liszkay A, Robin M, Pietri S. Synthesis and Biological Characterization of New Aminophosphonates for Mitochondrial pH Determination by 31P NMR Spectroscopy. J Med Chem 2013; 56:2487-99. [DOI: 10.1021/jm301866e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Marcel Culcasi
- Aix-Marseille Université, CNRS UMR 7273, Equipe Sondes Moléculaires en Biologie et
Stress Oxydant, Institut de Chimie Radicalaire, Marseille, France
| | - Gilles Casano
- Aix-Marseille Université, CNRS UMR 7273, Equipe Sondes Moléculaires en Biologie et
Stress Oxydant, Institut de Chimie Radicalaire, Marseille, France
| | - Céline Lucchesi
- Aix-Marseille Université, CNRS UMR 7273, Equipe Sondes Moléculaires en Biologie et
Stress Oxydant, Institut de Chimie Radicalaire, Marseille, France
| | - Anne Mercier
- Aix-Marseille Université, CNRS UMR 7273, Equipe Sondes Moléculaires en Biologie et
Stress Oxydant, Institut de Chimie Radicalaire, Marseille, France
| | - Jean-Louis Clément
- Aix-Marseille Université, CNRS UMR 7273, Equipe Sondes Moléculaires en Biologie et
Stress Oxydant, Institut de Chimie Radicalaire, Marseille, France
| | - Valérie Pique
- Aix-Marseille Université, CNRS UMR 7273, Equipe Sondes Moléculaires en Biologie et
Stress Oxydant, Institut de Chimie Radicalaire, Marseille, France
| | - Laure Michelet
- CNRS UMR 8221, Institut de Biologie et de Technologie de Saclay (iBiTec-S),
CEA Saclay, Gif-sur-Yvette, France
| | - Anja Krieger-Liszkay
- CNRS UMR 8221, Institut de Biologie et de Technologie de Saclay (iBiTec-S),
CEA Saclay, Gif-sur-Yvette, France
| | - Maxime Robin
- Aix-Marseille Université, CNRS UMR 7273, Equipe Sondes Moléculaires en Biologie et
Stress Oxydant, Institut de Chimie Radicalaire, Marseille, France
| | - Sylvia Pietri
- Aix-Marseille Université, CNRS UMR 7273, Equipe Sondes Moléculaires en Biologie et
Stress Oxydant, Institut de Chimie Radicalaire, Marseille, France
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Poburko D, Demaurex N. Regulation of the mitochondrial proton gradient by cytosolic Ca²⁺ signals. Pflugers Arch 2012; 464:19-26. [PMID: 22526460 DOI: 10.1007/s00424-012-1106-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 04/02/2012] [Indexed: 12/16/2022]
Abstract
Mitochondria convert the energy stored in carbohydrate and fat into ATP molecules that power enzymatic reactions within cells, and this process influences cellular calcium signals in several ways. By providing ATP to calcium pumps at the plasma and intracellular membranes, mitochondria power the calcium gradients that drive the release of Ca²⁺ from stores and the entry of Ca²⁺ across plasma membrane channels. By taking up and subsequently releasing calcium ions, mitochondria determine the spatiotemporal profile of cellular Ca²⁺ signals and the activity of Ca²⁺-regulated proteins, including Ca²⁺ entry channels that are themselves part of the Ca²⁺ circuitry. Ca²⁺ elevations in the mitochondrial matrix, in turn, activate Ca²⁺-dependent enzymes that boost the respiratory chain, increasing the ability of mitochondria to buffer calcium ions. Mitochondria are able to encode and decode Ca²⁺ signals because the respiratory chain generates an electrochemical gradient for protons across the inner mitochondrial membrane. This proton motive force (Δp) drives the activity of the ATP synthase and has both an electrical component, the mitochondrial membrane potential (ΔΨ(m)), and a chemical component, the mitochondrial proton gradient (ΔpH(m)). ΔΨ(m) contributes about 190 mV to Δp and drives the entry of Ca²⁺ across a recently identified Ca²⁺-selective channel known as the mitochondrial Ca²⁺ uniporter. ΔpH(m) contributes ~30 mV to Δp and is usually ignored or considered a minor component of mitochondria respiratory state. However, the mitochondrial proton gradient is an essential component of the chemiosmotic theory formulated by Peter Mitchell in 1961 as ΔpH(m) sustains the entry of substrates and metabolites required for the activity of the respiratory chain and drives the activity of electroneutral ion exchangers that allow mitochondria to maintain their osmolarity and volume. In this review, we summarize the mechanisms that regulate the mitochondrial proton gradient and discuss how thermodynamic concepts derived from measurements in purified mitochondria can be reconciled with our recent findings that mitochondria have high proton permeability in situ and that ΔpH(m) decreases during mitochondrial Ca²⁺ elevations.
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Affiliation(s)
- Damon Poburko
- Department of Biomedical Physiology & Kinesiology, Simon Fraser University, Vancouver, BC, Canada
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Poburko D, Santo-Domingo J, Demaurex N. Dynamic regulation of the mitochondrial proton gradient during cytosolic calcium elevations. J Biol Chem 2011; 286:11672-84. [PMID: 21224385 PMCID: PMC3064219 DOI: 10.1074/jbc.m110.159962] [Citation(s) in RCA: 249] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Mitochondria extrude protons across their inner membrane to generate the mitochondrial membrane potential (ΔΨm) and pH gradient (ΔpHm) that both power ATP synthesis. Mitochondrial uptake and efflux of many ions and metabolites are driven exclusively by ΔpHm, whose in situ regulation is poorly characterized. Here, we report the first dynamic measurements of ΔpHm in living cells, using a mitochondrially targeted, pH-sensitive YFP (SypHer) combined with a cytosolic pH indicator (5-(and 6)-carboxy-SNARF-1). The resting matrix pH (∼7.6) and ΔpHm (∼0.45) of HeLa cells at 37 °C were lower than previously reported. Unexpectedly, mitochondrial pH and ΔpHm decreased during cytosolic Ca2+ elevations. The drop in matrix pH was due to cytosolic acid generated by plasma membrane Ca2+-ATPases and transmitted to mitochondria by Pi/H+ symport and K+/H+ exchange, whereas the decrease in ΔpHm reflected the low H+-buffering power of mitochondria (∼5 mm, pH 7.8) compared with the cytosol (∼20 mm, pH 7.4). Upon agonist washout and restoration of cytosolic Ca2+ and pH, mitochondria alkalinized and ΔpHm increased. In permeabilized cells, a decrease in bath pH from 7.4 to 7.2 rapidly decreased mitochondrial pH, whereas the addition of 10 μm Ca2+ caused a delayed and smaller alkalinization. These findings indicate that the mitochondrial matrix pH and ΔpHm are regulated by opposing Ca2+-dependent processes of stimulated mitochondrial respiration and cytosolic acidification.
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Affiliation(s)
- Damon Poburko
- Department of Cell Physiology and Metabolism, University of Geneva Medical School, Geneva, Switzerland
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Garcia J, Shea J, Alvarez-Vasquez F, Qureshi A, Luberto C, Voit EO, Del Poeta M. Mathematical modeling of pathogenicity of Cryptococcus neoformans. Mol Syst Biol 2008; 4:183. [PMID: 18414484 PMCID: PMC2387229 DOI: 10.1038/msb.2008.17] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Accepted: 02/20/2008] [Indexed: 01/06/2023] Open
Abstract
Cryptococcus neoformans (Cn) is the most common cause of fungal meningitis worldwide. In infected patients, growth of the fungus can occur within the phagolysosome of phagocytic cells, especially in non-activated macrophages of immunocompromised subjects. Since this environment is characteristically acidic, Cn must adapt to low pH to survive and efficiently cause disease. In the present work, we designed, tested, and experimentally validated a theoretical model of the sphingolipid biochemical pathway in Cn under acidic conditions. Simulations of metabolic fluxes and enzyme deletions or downregulation led to predictions that show good agreement with experimental results generated post hoc and reconcile intuitively puzzling results. This study demonstrates how biochemical modeling can yield testable predictions and aid our understanding of fungal pathogenesis through the design and computational simulation of hypothetical experiments.
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Affiliation(s)
- Jacqueline Garcia
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA
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Tremey B, Vigué B. Les variations thermiques modifient les paramètres des gaz du sang : quelles conséquences en pratique clinique ? ACTA ACUST UNITED AC 2004; 23:474-81. [PMID: 15158238 DOI: 10.1016/j.annfar.2004.01.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2003] [Accepted: 01/20/2004] [Indexed: 10/26/2022]
Abstract
OBJECTIVE To understand changes in blood gases results with core temperature. METHODS Analysis from two case reports. RESULTS Hypothermia induces a decrease in PaCO(2) with a related increase in pH, thus a physiologic alkalosis. Decrease in PaCO(2) is due to an increase of gas solubility and a decrease of peripheral consumption that can be estimated from comparison between corrected and non-corrected for temperature blood gases. For O(2), variations of temperature induce variations of solubility but also of haemoglobin affinity for O(2). During hyperthermia, haemoglobin affinity for O(2) is decreased with a decreased SvO(2) for a same PvO(2). SvO(2) ischemic or therapeutic thresholds are thus modified with core temperature. CONCLUSION Blood gases cannot be understood without patient core temperature. Physiologic variations of PaCO(2) and pH must probably be tolerated. Ischemic threshold should be estimated on PvO(2), not only on PvO(2).
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Affiliation(s)
- B Tremey
- Département d'anesthésie-réanimation, CHU de Bicêtre, 94275, Le Kremlin-Bicêtre, cedex, France
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Abstract
Metabolic acidosis is a common occurrence in critically ill patients. Understanding the pathological mechanisms underlying the generation of protons will enable the clinician to quickly recognize these disorders and establish an acceptable treatment strategy. This article presents a logical approach to metabolic acidosis.
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Affiliation(s)
- Philippe M Gauthier
- Section of Nephrology, Tulane University Health Sciences Center, New Orleans, LA 70131, USA
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