Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0948265 (metabolic syndrome)
 24,271 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Japanese-Americans have an increased prevalence of non-insulin-dependent diabetes mellitus and coronary heart disease when compared to native Japanese. This increase has been associated with fasting hyperinsulinemia, hypertriglyceridemia, and low plasma levels of high-density lipoprotein (HDL) cholesterol. The purpose of this study was to examine the relationship of both visceral adiposity and insulin resistance to this metabolic syndrome and to the presence of a predominance of small, dense low-density lipoprotein (LDL) particles (LDL subclass phenotype B) that has been associated with increased atherogenic risk. Six Japanese-American men with non-insulin-dependent diabetes, each receiving an oral sulfonylurea, were selected. One or 2 nondiabetic Japanese-American men, matched by age and body mass index, were selected for each diabetic subject, giving a total of 9 nondiabetic men. Diabetic subjects had significantly higher fasting plasma glucose (p=0.0007) and lower insulin sensitivity (SI, p=0.018) using the minimal model technique than nondiabetic subjects matched for body mass index. Six men (2 with diabetes) had LDL phenotype A and 8 (4 with diabetes) had phenotype B. One nondiabetic subject had an intermediate low-density lipoprotein pattern. Significantly greater amounts of intra-abdominal fat (p=0.045) measured by computed tomography were found in the men with phenotype B while fasting insulin (p=0.070) and triglycerides (p=0.051) tended to be higher. free fatty acids (r=0.677), LDL density (relative flotation rate, r=-0.803), and plasma HDL-cholesterol (r=-0.717). SI was significantly correlated only with plasma free fatty acids (r=-0.546) and tended to be correlated with hepatic lipase activity (r=-0.512, p=0.061). In conclusion, these observations indicate that in non-obese Japanese-American men, the metabolic features of the so-called insulin resistance syndrome, including LDL phenotype B, are more strongly correlated with visceral adiposity than with SI. It may therefore be more appropriate to call this the visceral adiposity syndrome. Although questions concerning mechanisms still remain, we postulate that visceral adiposity plays a central role in the development of many of the metabolic abnormalities, including LDL subclass phenotype B, that occur in this metabolic syndrome.
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PMID:The visceral adiposity syndrome in Japanese-American men. 1635 83

Endothelial lipase (EL) has recently been identified as a new member of the triglyceride lipase gene family. EL shares a relatively high degree of homology with lipoprotein lipase and hepatic lipase, but it appears to be more specific at hydrolyzing phospholipids than lipoprotein lipase and hepatic lipase. EL is also the only identified lipase that is synthesized and expressed by endothelial cells. Data from in vitro and in vivo animal studies have suggested that EL may play a key role in modulating the metabolism of high density lipoproteins. Data are less consistent in clarifying how EL contributes to the metabolism of apolipoprotein B-containing lipoproteins. Investigations in humans are scarce. To date, increased plasma EL concentrations have been associated with a deteriorated lipoprotein-lipid profile along with elevated plasma triglyceride and apolipoprotein B concentrations, as well as with smaller low density lipoprotein particle size. Elevated proinflammatory cytokine concentrations and an increased prevalence of the metabolic syndrome have also been observed among individuals with elevated plasma EL concentrations. Taken together, data suggest that EL is one of several key regulatory enzymes of lipoprotein-lipid metabolism and that a proinflammatory state, such as the metabolic syndrome, may be implicated in the processes relating plasma EL concentrations and lipoprotein concentrations. EL should thus be considered to play an important role in the pathophysiology of cardiovascular disease.
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PMID:Endothelial lipase: its role in cardiovascular disease. 1649 10

Nitric oxide (NO) is synthesized from L-arginine by NO synthase in virtually all cell types. Emerging evidence shows that NO regulates the metabolism of glucose, fatty acids and amino acids in mammals. As an oxidant, pathological levels of NO inhibit nearly all enzyme-catalyzed reactions through protein oxidation. However, as a signaling molecule, physiological levels of NO stimulate glucose uptake as well as glucose and fatty acid oxidation in skeletal muscle, heart, liver and adipose tissue; inhibit the synthesis of glucose, glycogen, and fat in target tissues (e.g., liver and adipose); and enhance lipolysis in adipocytes. Thus, an inhibition of NO synthesis causes hyperlipidemia and fat accretion in rats, whereas dietary arginine supplementation reduces fat mass in diabetic fatty rats. The putative underlying mechanisms may involve multiple cyclic guanosine-3',5'-monophosphate-dependent pathways. First, NO stimulates the phosphorylation of adenosine-3',5'-monophosphate-activated protein kinase, resulting in (1) a decreased level of malonyl-CoA via inhibition of acetyl-CoA carboxylase and activation of malonyl-CoA decarboxylase and (2) a decreased expression of genes related to lipogenesis and gluconeogenesis (glycerol-3-phosphate acyltransferase, sterol regulatory element binding protein-1c and phosphoenolpyruvate carboxykinase). Second, NO increases the phosphorylation of hormone-sensitive lipase and perilipins, leading to the translocation of the lipase to the neutral lipid droplets and, hence, the stimulation of lipolysis. Third, NO activates expression of peroxisome proliferator-activated receptor-gamma coactivator-1alpha, thereby enhancing mitochondrial biogenesis and oxidative phosphorylation. Fourth, NO increases blood flow to insulin-sensitive tissues, promoting substrate uptake and product removal via the circulation. Modulation of the arginine-NO pathway through dietary supplementation with L-arginine or L-citrulline may aid in the prevention and treatment of the metabolic syndrome in obese humans and companion animals, and in reducing unfavorable fat mass in animals of agricultural importance.
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PMID:Regulatory role for the arginine-nitric oxide pathway in metabolism of energy substrates. 1652 13

Adipose tissue lipolysis is the catabolic process leading to the breakdown of triglycerides stored in fat cells and release of fatty acids and glycerol. Recent work has revealed that lipolysis is not a simple metabolic pathway stimulated by catecholamines and inhibited by insulin. There have been new discoveries on the endocrine and paracrine regulation of lipolysis and on the molecular mechanisms of triglyceride hydrolysis. Catecholamines modulate lipolysis through lipolytic beta-adrenoceptor and antilipolytic alpha2-adrenoceptor. Recent studies have allowed a better understanding of the relative contribution of the two types of receptors and provided evidence for the in vivo involvement of alpha2-adrenoceptors in the physiological control of subcutaneous adipose tissue lipolysis. A puzzling observation is the characterization of a residual catecholamine-induced lipolysis in mice deficient in beta-adrenoceptors. A novel lipolytic system has been characterized in human fat cells. Natriuretic peptides stimulate lipolysis through a cGMP-dependent pathway. There are other lipolytic pathways active in human fat cells which importance is not fully understood. Forty years after the description of the antilipolytic effect of nicotinic acid, the receptors have been identified. Adrenomedullin which is produced by adipocytes exert an antilipolytic effect through an indirect mechanism involving nitric oxide. The molecular details of the lipolytic reaction are not fully understood. The role of the lipases has been re-evaluated with the cloning of adipose triglyceride lipase. Hormone-sensitive lipase appears as the major lipase for catecholamine and natriuretic peptide-stimulated lipolysis whereas adipose triglyceride lipase mediates the hydrolysis of triglycerides during basal lipolysis. Translocation of hormone-sensitive lipase bound to the adipocyte lipid binding protein to the lipid droplet seems to be an important step during lipolytic activation. Re-organization of the lipid droplet coating by perilipins facilitates the access of the enzyme. The role of other lipid-interacting proteins in lipolysis is still unclear. The proteins involved in the lipolytic process constitute drug targets for the treatment of obesity and the metabolic syndrome. The oldest example is nicotinic acid (niacin) used as a hypolipidaemic drug. A first approach consists in molecules stimulating lipolysis and oxidation of the released fatty acids to decrease fat stores. A second approach is a chronic inhibition of lipolysis to diminish plasma fatty acid level which is a central feature of the metabolic syndrome.
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PMID:Adipose tissue lipolysis as a metabolic pathway to define pharmacological strategies against obesity and the metabolic syndrome. 1664 34

Obese individuals often suffer from negative self-image. Many, even those with a normal body mass index, resort to pharmacotherapy (lipase inhibitors or appetite suppressants), mesotherapy and surgery (gastric volume reduction, liposuction or apronectomy) in a bid to remove excess adipose tissue. These treatments are associated with inherent morbidity and even mortality, and hence should not be undertaken lightly. The observation that denervation of adipose tissue results in lipoatrophy leads us to postulate that chemodenervation using botulinum toxin may achieve the same result, i.e. fat loss, and we explore the methods by which selective fat loss may be achieved. We concede that removal of subcutaneous fat does not, however, reduce the risks associated with the metabolic syndrome, as visceral (intra-abdominal) fat is not reduced by the removal of subcutaneous fat.
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PMID:Botulinum toxin injections to reduce adiposity: possibility, or fat chance? 1671 33

Postprandial hypertriglyceridemia and low plasma HDL levels, which are principal features of the metabolic syndrome, are displayed by transgenic mice expressing human apolipoprotein A-II (hapoA-II). In these mice, hypertriglyceridemia results from the inhibition of lipoprotein lipase and hepatic lipase activities by hapoA-II carried on VLDL. This study aimed to determine whether the association of hapoA-II with triglyceride-rich lipoproteins (TRLs) is sufficient to impair their catabolism. To measure plasma TRL residence time, intestinal TRL production was induced by a radioactive oral lipid bolus. Radioactive and total triglyceride (TG) were rapidly cleared in control mice but accumulated in plasma of transgenic mice, in relation to hapoA-II concentration. Similar plasma TG accumulations were measured in transgenic mice with or without endogenous apoA-II expression. HapoA-II (synthesized in liver) was detected in chylomicrons (produced by intestine). The association of hapoA-II with TRL in plasma was further confirmed by the absence of hapoA-II in chylomicrons and VLDL of transgenic mice injected with Triton WR 1339, which prevents apolipoprotein exchanges. We show that the association of hapoA-II with TRL occurs in the circulation and induces postprandial hypertriglyceridemia.
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PMID:Human apolipoprotein A-II associates with triglyceride-rich lipoproteins in plasma and impairs their catabolism. 1699 Jun 46

An excess of fat mass excess predisposes to multiple complications such as type 2 diabetes, cardiovascular diseases or cancer. A dysregulation of lipid metabolism contributes to the development of obesity and the metabolic syndrome. Recent data on lipid mobilization in adipose tissue have revealed a complex pathway involving a human specific hormonal control of lipolysis via the natriuretic peptides and a new triglyceride lipase, ATGL. Activation of fatty acid reesterification and oxidation can lead to an increase in fatty acid utilization. Targeting these key steps of lipid metabolism (adipose tissue lipolysis and fatty acid oxidation) constitutes a potential strategy for the treatment of obesity and associated metabolic disorders.
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PMID:[Fatty acid mobilization and their use in adipose tissue]. 1714 66

Adipose tissue is an active and complex endocrine organ that secretes numerous bioactive substances, including hormones, growth factors, and cytokines. Central obesity, one of the components of metabolic syndrome, is a cardiometabolic risk factor associated with a state of chronic inflammation and coagulation, one in which the expression of certain adipocytokines, including tumor necrosis factor-alpha (TNF-(alpha), interleukin (IL)-6, and plasminogen activator inhibitor-1 (PAI-1) is more abundantly increased, while adiponectin expression is decreased. TNF-alpha initiates and organizes inflammatory changes in vascular tissue. IL-6, an inflammatory cytokine directly implicated in atherogenesis, exerts pleiotropic effects on a variety of tissues. An increased concentration of PAI-1, an important regulator of the endogenous fibrinolytic system, promotes continued clotting. Adiponectin, on the other hand, has potent vasculoprotective, angiogenic, anti-inflammatory, and antiatherogenic properties. Adiponectin levels are low in obese individuals and increase when weight is lost, thereby serving as a marker for cardioprotection. Weight loss has long been promoted as a means to reduce the risk of type 2 diabetes and cardiovascular disease; for example, exercise and a hypocaloric diet have been shown to decrease PAI-1 levels. Weight loss drugs, such as orlistat, a lipase inhibitor, and sibutramine, a serotonin and norepinephrine reuptake inhibitor, have both been shown to produce a decrease in C-reactive protein levels and an increase in serum adiponectin. Rimonabant, a selective cannabinoid 1 receptor antagonist in Phase III studies, also has been shown to increase adiponectin levels. These agents may play a role in the regulation of adipocytokines, which may directly affect the risk for cardiometabolic disease.
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PMID:The relation of adipose tissue to cardiometabolic risk. 1720 62

Hypertriglyceridemia is a hallmark of many disorders, including metabolic syndrome, diabetes, atherosclerosis and obesity. A well-known cause is the deficiency of lipoprotein lipase (LPL), a key enzyme in plasma triglyceride hydrolysis. Mice carrying the combined lipase deficiency (cld) mutation show severe hypertriglyceridemia owing to a decrease in the activity of LPL and a related enzyme, hepatic lipase (HL), caused by impaired maturation of nascent LPL and hepatic lipase polypeptides in the endoplasmic reticulum (ER). Here we identify the gene containing the cld mutation as Tmem112 and rename it Lmf1 (Lipase maturation factor 1). Lmf1 encodes a transmembrane protein with an evolutionarily conserved domain of unknown function that localizes to the ER. A human subject homozygous for a deleterious mutation in LMF1 also shows combined lipase deficiency with concomitant hypertriglyceridemia and associated disorders. Thus, through its profound effect on lipase activity, LMF1 emerges as an important candidate gene in hypertriglyceridemia.
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PMID:Mutations in LMF1 cause combined lipase deficiency and severe hypertriglyceridemia. 1804 26

Evidence has been provided that increased levels of non esterified fatty acids (NEFA) in the portal flow would produce insulin resistance and would also stimulate the hepatic protein synthesis, thereby explaining the increased plasma levels not only of apolipoprotein B, but also of other liver-derived enzymes and proteins occurring in overweight and hypertriglyceridemic patients. The high plasma concentration of triglyceride-rich lipoprotein would facilitate the transfer of cholesteryl esters from HDL and LDL to VLDL in exchange for triglycerides, a process mediated by liver-derived cholesteryl ester transfer protein (CETP). The triglyceride thereby acquired in HDL and LDL would then be hydrolyzed by hepatic lipase. The resulting association of increased triglycerides, low HDL cholesterol and small dense LDL is considered to be an atherogenic profile. The prothrombotic state, another feature of the metabolic syndrome, may also be explained by an enhanced hepatic synthesis of clotting factors and of the inhibitors of fibrinolysis. It was recently shown that adipocyte synthesized adiponectin reduces the release of fatty acids from the adipose tissue and would also enhance their uptake and oxidation in the muscle, thereby limiting their uptake in the liver. Decreased adiponectin production in obesity would therefore promote the development of insulin resistance, of atherogenic dyslipidemia and of the prothrombotic state. Because adiponectin also exerts an antiinflammatory activity by antagonizing TNFalpha, hypoadiponectinemia may be involved in atherogenesis and in the progression of hepatic steatosis to steatohepatitis.
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PMID:Pathogenic role of abnormal fatty acids and adipokines in the portal flow. Relevance for metabolic syndrome, hepatic steatosis and steatohepatitis. 1833 68


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