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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

New possibilities are explored for supporting classical treatment of obesity. There are three main ways for the pharmacotherapy of obesity: (1) inhibition of absorption of nutrients in the intestine; (2) modulation of the activity of hypothalamic centra controlling satiety and food consumption; and (3) induction of energy dissipation in tissues (thermogenesis). The last possibility received more attention due to recent discoveries. The goal would be to affect mitochondrial energy conversion in a way leading to elevated thermogenesis and not to ATP production.
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PMID:[Mitochondrial energy metabolism, uncoupling proteins and adipose tissue accumulation]. 1035 15

Nowadays besides the commonly accepted atherogenic risk factors a special emphasis is laid on the significance of testosterone in atherogenesis in men which physiologic deficit during "andropause" is able to promote this pathology. An elevated estradiol:testosterone ratio seems to be an independent risk factor of atheromatous heart complications. There is a proved positive correlation between free testosterone, total testosterone, dihydrotestosterone and HDL-cholesterol, apoA1 apolipoprotein. The relationship between LDL-cholesterol, VLDL-cholesterol, total cholesterol and total and free testosterone seems to be unanimous, but in certain studies the beneficial influence of testosterone on the mentioned lipids has been observed. The discussed hormone is also functionally connected with coagulation and fibrynolisis; a positive correlation was found between endogenous testosterone and tPA-Fx and a negative correlation between testosterone and PAI-1, fibrinogen, D-dimers, alpha 2-antiplasmin. Testosterone is a functional regulator of the vascular tonus and influences on reological properties of microcirculation (the application of testosterone infusion into canine coronary arteries causes the dilatation of main and the small vessels, through NO syntetase induction and ATP-dependent K(+)- channel activation). A statistically significant positive correlation between testosterone and insulin has been stated (an elevated oestradiol:testosterone ratio is connected with the insulin resistance). Additionally a negative relationship between testosterone and android obesity has been observed. Although nowadays there are more and more facts proving the benefits of the retaining the proper testosterone levels in aging men, the final influence of the testosterone supplementary therapy on atherogenesis is not solved.
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PMID:[Testosterone and atherosclerosis in males during andropause]. 1039 Oct 62

Energy supply from foods and drinks depends upon carbohydrate, protein, lipid and alcohol content. Cells obtain the energy through a complex and integrated system of physico-chemical processes. The energy value of foods is applied for ATP formation, but also for nutrient utilization and turnover. Net energy from foods is expended for basal metabolism, thermic effect of food and physical activity. Total energy expenditure for human beings is displayed in different lists developed by national and international organisms and institutions. Energy balance and body weight are narrowly interrelated as well as body composition, which depends also of age, sex, exercise and neuroendocrine status. Obesity, is known as an excessive deposition of fat for height, and it is associated with cancer, dislipemias, endocrine abnormalities, diabetes, etc. Recent advances suggest that genetic and neuroendocrine factors are more involved in obesity rather than gluttony or sloth as previously reported.
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PMID:[Nutrition, energy balance, and obesity]. 1042 Sep 25

In mitochondria, ATP synthesis is coupled to oxygen consumption by the proton electrochemical gradient established across the mitochondrial inner membrane in a process termed oxidative phosphorylation. It has long been known from stoichiometric studies that ATP synthesis is not perfectly coupled to oxygen consumption. The major inefficiency in the system is leakage of protons across the mitochondrial inner membrane driven by the proton electrochemical gradient. The kinetics of the proton leak can be determined indirectly, by measuring the oxygen consumption of mitochondria under non-phosphorylating conditions (plus oligomycin) as a function of the proton electrochemical gradient. This experimental system provides a convenient means to investigate inner membrane permeability to protons and the effect of factors that may effect that permeability. In this paper we review some results from our laboratory of indirect measurement of mitochondrial proton leak and how it has been applied to investigate the effect of aging, obesity and thyroid status on proton leak. The results show that (i) proton leak in isolated liver mitochondria is not significantly different in a comparison of young and old rats, in contrast (ii) there is an apparent increase in proton leak in in situ mitochondria in hepatocytes from old rats when compared to those from young rats, (iii) proton leak in neuronal mitochondria in situ in synaptosomes is not significantly different in young and old rats, (iv) proton leak is greater in isolated liver mitochondria from ob/ob mice compared to lean controls, (v) acute leptin (OB protein) administration restores the increased leak rate in isolated liver mitochondria from ob/ob mice to that of lean controls, (vi) administration of thyroid hormone (T3) increases proton leak in rat muscle mitochondria, and (vii) proton leak in muscle mitochondria is insensitive to the presence of GDP. It is proposed that the experimental system described here for measuring proton leak, is an ideal functional assay for determining whether the novel uncoupling proteins increase inner membrane permeability to protons.
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PMID:Indirect measurement of mitochondrial proton leak and its application. 1045 15

Uncoupling protein-2 (UCP2) and uncoupling protein-3 (UCP3) are mitochondrial proteins that may play a role in the control of energy expenditure by uncoupling respiration from ATP synthesis. The present review focuses on data obtained in humans. UCP2 is widely expressed in the body, whereas UCP3 expression is restricted to skeletal muscle. Positive correlations have been reported between UCP2 mRNA concentrations in adipose tissue, UCP3 mRNA concentrations in skeletal muscle, and components of the metabolic rate. Fasting induces an up-regulation of UCP2 and UCP3 mRNA expression. In vivo and in vitro studies suggest that fatty acids could modulate uncoupling protein gene expression. The putative relationship between obesity, energy expenditure and uncoupling protein expression, and the unexpected rise in UCP2 and UCP3 mRNA concentrations during short-term fasting, are discussed in view of the recent data obtained in rodents and cell lines.
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PMID:Uncoupling protein-2 (UCP2) and uncoupling protein-3 (UCP3) expression in adipose tissue and skeletal muscle in humans. 1045 28

A regulatory role for intracellular Ca2+ ([Ca2+]i) in adipocyte lipogenesis, lipolysis and triglyceride accumulation has been demonstrated. Compounds acting on the pancreatic sulfonylurea receptor (SUR) to increase (e.g., glibenclamide) or decrease (e.g., diazoxide) [Ca2+]i cause corresponding increases and decreases in weight gain. However, these weight gain and loss effects have been attributed to insulin release rather than to the primary effects of these compounds on the adipocyte SUR and its associated K(ATP) channel. Accordingly, we have evaluated the direct role of the human adipocyte SUR in regulating adipocyte metabolism. We used RT-PCR with primers for a highly conserved region of SUR1 to demonstrate that human adipocytes express SUR1. The PCR product was confirmed by sequence analysis and used as a probe to demonstrate adipocyte SUR1 expression by Northern blot analysis. Adipocytes exhibited glibenclamide dose-responsive (0-20 microM) increases in [Ca2+]i (P<0.05). Similarly, glibenclamide (10 microM) caused a 67% increase in adipocyte fatty acid synthase activity (P<0.001), a 48% increase in glycerol-3-phosphate dehydrogenase activity (P<0.01) and a 68% inhibition in lipolysis (P<0.01), whereas diazoxide (10 microM) completely prevented each of these effects. These data demonstrate that human adipocytes express a SUR that regulates [Ca2+]i and, consequently, exerts coordinate control over lipogenesis and lipolysis. Accordingly, the adipocyte SUR1 may represent an important target for the development of therapeutic interventions in obesity.
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PMID:Role of the sulfonylurea receptor in regulating human adipocyte metabolism. 1050 87

In eukaryotic cells ATP is generated by oxidative phosphorylation, an energetic coupling at the mitochondrial level. The oxidative reactions occurring in the respiratory chain generate an electrochemical proton gradient on both sides of the inner membrane. This gradient is used by the ATPsynthase to phosphorylate ADP into ATP. The coupling between respiration and ADP phosphorylation is only partial in brown adipose tissue (BAT) mitochondria, where the uncoupling protein UCP1 causes a reentry of protons into the matrix and abolishes the electrochemical proton gradient. The liberated energy is then dissipated as heat and ATP synthesis is reduced. This property was for a long time considered as an exception and specific to the non-shivering thermogenesis found in BAT. The recent cloning of new UCPs expressed in other tissues revealed the importance of this kind of regulation of respiratory control in metabolism and energy expenditure. The newly characterised UCPs are potential targets for obesity treatment drugs which could favour energy expenditure and diminish the metabolic efficiency. In 1997, we cloned UCP2 and proposed a role for this new uncoupling protein in diet-induced thermogenesis, obesity, hyperinsulinemia, fever and resting metabolic rate. Currently, an abundant literature deals with UCP2, but its biochemical and physiological functions and regulation remain unclear. The present review reports the status of our knowledge of this mitochondrial carrier in terms of sequence, activity, tissue distribution and regulation of expression. The putative physiological roles of UCP2 will be introduced and discussed.
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PMID:The mitochondrial uncoupling protein-2: current status. 1060 19

Human uncoupling protein 3 (UCP3) has two RNA transcripts that arise from the differential processing of the same gene product. One encodes the full length protein (UCP3L) while the other encodes a truncated version (UCP3S) lacking the sixth membrane spanning domain. The roles of the two isoforms are not known, but a mutation that decreases the proportion of UCP3L decreases fat oxidation and increases susceptibility to obesity. In the ADP/ATP carrier, a protein closely related to UCP3, the sixth membrane spanning domain is required for insertion into the inner membrane. Therefore, defective membrane insertion of UCP3S may account for the different effects of the two isoforms in vivo. We investigated mitochondrial import of the two UCP3 isoforms. When epitope-tagged versions of UCP3S and UCP3L were expressed in COS7 cells, both were inserted into the mitochondrial inner membrane. Translation in vitro followed by incubation with isolated mitochondria showed that both isoforms were inserted into the inner membrane, however, the insertion of UCP3S was significantly slower.
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PMID:Mitochondrial import of the long and short isoforms of human uncoupling protein 3. 1063 20

We used (31)P magnetic resonance spectroscopy to measure maximal mitochondrial function in 12 obesity-prone women before and after diet-induced weight reduction and in 12 matched, never-obese, and 7 endurance-trained controls. Mitochondrial function was modeled after maximum-effort plantar flexion from the phosphocreatine recovery time constant (TC(PCr)), the ADP recovery time constant (TC(ADP)), and the rate of change in PCr during the first 14 s of recovery (OxPhos). Weight reduction was not associated with a significant change in mitochondrial function by TC(PCr), TC(ADP), or OxPhos. Mitochondrial function was not different between postobese and never-obese controls by TC(PCr) [35.1 +/- 2.5 (SE) vs. 34.6 +/- 2.5 s], TC(ADP) (22.9 +/- 1.8 vs. 21.2 +/- 1.8 s), or OxPhos (0.26 +/- 0. 03 vs. 0.25 +/- 0.03 mM ATP/s), postobese vs. never-obese, respectively. However, TC(ADP) was significantly faster (14.5 +/- 2. 3 s), and OxPhos was significantly higher (0.38 +/- 0.04 mM ATP/s) in the endurance-trained group. These results suggest that maximal mitochondrial function is not impaired in normal-weight obesity-prone women relative to their never-obese counterparts but is increased in endurance-trained women.
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PMID:Effect of weight reduction, obesity predisposition, and aerobic fitness on skeletal muscle mitochondrial function. 1064 50

Leptin, the product of the obesity (ob) gene, controls energy intake and expenditure primarily by actions on the central nervous system. However, recently it has become apparent that leptin also elicits a growing and diverse array of effects on peripheral tissues. The Na,K-pump is an electrogenic plasma membrane protein which actively extrudes 3Na+ ions and imports 2K+ ions per molecule of ATP hydrolysed. The pump is responsible for the maintenance of the electrochemical potential of all cells, which in turn drives all ion-coupled transport mechanisms. In this study we use 3T3-L1 fibroblasts to show that leptin inhibits Na,K-pump activity, as assessed by ouabain-sensitive 86Rb+ uptake. Inhibition of the Na,K-pump correlated with increased serine phosphorylation of the catalytic Na,K-pump alpha1 subunit. Upon investigation of leptin-stimulated signalling pathways using specific pharmacological inhibitors, only wortmannin prevented inhibition of the Na,K-pump by leptin. Moreover, leptin stimulated phosphotyrosine-associated PI 3-kinase activity in these cells. In summary, leptin was found to inhibit Na,K-pump activity, likely via PI 3-kinase. We propose that this effect may have wide ranging cardiovascular and metabolic implications and perhaps explain physiological effects of the hormone such as natriuresis.
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PMID:Regulation of the Na,K-pump by leptin in 3T3-L1 fibroblasts. 1069 6


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