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)

The efficacy and safety profiles of various forms of niacin for treating dyslipidemia are described. Niacin is well recognized for treating dyslipidemia in adults and has been shown to be effective in reducing coronary events. It has a broad range of effects on serum lipids and lipoproteins, including lowering total cholesterol, low-density-lipoprotein (LDL) cholesterol, and triglycerides. Niacin is the most effective lipid-modifying drug for raising high-density-lipoprotein (HDL) cholesterol levels and has been shown to lower Lp(a) lipoprotein. Niacin reduces triglycerides and very-low-density-lipoprotein and LDL cholesterol synthesis, primarily by decreasing fatty acid mobilization from adipose tissue. Niacin appears to raise HDL cholesterol by reducing hepatic apolipoprotein A-l clearance and enhancing reverse cholesterol transport. Niacin is metabolized through a conjugation or nicotinamide pathway. Standard immediate-release niacin is metabolized primarily through the conjugation pathway, which results in a high frequency of flushing. Long-acting niacin is metabolized through the nicotinamide pathway, which results in less flushing but increases the risk of hepatotoxicity. Extended-release niacin has a more balanced metabolism and causes fewer of both types of adverse effects. Improved serum lipid levels during niacin therapy have been associated with clinical and angiographic evidence of reduced coronary artery disease, especially when combined with statins. Niacin is particularly useful for managing high triglyceride and low HDL cholesterol levels as well as the lipid abnormalities associated with metabolic syndrome, including those commonly encountered in patients with diabetes. Several niacin products are available with significant differences in their safety and efficacy profiles. Health care providers must consider the differences between agents when recommending niacin for dyslipidemia treatment.
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PMID:Niacin for dyslipidemia: considerations in product selection. 1278 70

11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) interconverts inactive cortisone and active cortisol. Although bidirectional, in vivo it is believed to function as a reductase generating active glucocorticoid at a prereceptor level, enhancing glucocorticoid receptor activation. In this review, we discuss both the genetic and enzymatic characterization of 11beta-HSD1, as well as describing its role in physiology and pathology in a tissue-specific manner. The molecular basis of cortisone reductase deficiency, the putative "11beta-HSD1 knockout state" in humans, has been defined and is caused by intronic mutations in HSD11B1 that decrease gene transcription together with mutations in hexose-6-phosphate dehydrogenase, an endoluminal enzyme that provides reduced nicotinamide-adenine dinucleotide phosphate as cofactor to 11beta-HSD1 to permit reductase activity. We speculate that hexose-6-phosphate dehydrogenase activity and therefore reduced nicotinamide-adenine dinucleotide phosphate supply may be crucial in determining the directionality of 11beta-HSD1 activity. Therapeutic inhibition of 11beta-HSD1 reductase activity in patients with obesity and the metabolic syndrome, as well as in glaucoma and osteoporosis, remains an exciting prospect.
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PMID:11beta-hydroxysteroid dehydrogenase type 1: a tissue-specific regulator of glucocorticoid response. 1546 42

Hexose-6-phosphate dehydrogenase (H6PDH) is a microsomal enzyme that is able to catalyze the first two reactions of an endoluminal pentose phosphate pathway, thereby generating reduced nicotinamide adenine dinucleotide phosphate (NADPH) within the endoplasmic reticulum. It is distinct from the cytosolic enzyme, glucose-6-phosphate dehydrogenase (G6PDH), using a separate pool of NAD(P)+ and capable of oxidizing several phosphorylated hexoses. It has been proposed to be a NADPH regenerating system for steroid hormone and drug metabolism, specifically in determining the set point of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) activity, the enzyme responsible for the activation and inactivation of glucocorticoids. 11beta-HSD1 is a bidirectional enzyme, but in intact cells displays predominately oxo-reductase activity, a reaction requiring NADPH and leading to activation of glucocorticoids. However, in cellular homogenates or in purified preparations, 11beta-HSD1 is exclusively a dehydrogenase. Because H6PDH and 11beta-HSD1 are coexpressed in the inner microsomal compartment of cells, we hypothesized that H6PDH may provide 11beta-HSD1 with NADPH, thus promoting oxo-reductase activity in vivo. Recently, several studies have confirmed this functional cooperation, indicating the importance of intracellular redox mechanisms for the prereceptor control of glucocorticoid availability. With the increased interest in 11beta-HSD1 oxo-reductase activity in the pathogenesis and treatment of several human diseases including insulin resistance and the metabolic syndrome, H6PDH represents an additional novel candidate for intervention.
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PMID:Minireview: hexose-6-phosphate dehydrogenase and redox control of 11{beta}-hydroxysteroid dehydrogenase type 1 activity. 1577 58

Dysregulated production of adipocytokines may be involved in the development of atherosclerotic cardiovascular disease in metabolic syndrome and chronic kidney disease (CKD) associated with metabolic syndrome. The aim of this study was to determine the effects of treatment with angiotensin II (Ang II) type-1 receptor blocker (ARB) on the regulation of adipocytokines. Olmesartan, an ARB, significantly blunted the age- and body weight-associated falls in plasma adiponectin both in genetically and diet-induced obese mice, without affecting body weight, but had no effect on plasma adiponectin levels in lean mice. Olmesartan also ameliorated dysregulation of adipocytokines in obesity, such as tumor necrosis factor-alpha, plasminogen activator inhibitor-1, monocyte chemotactic protein-1, and serum amyloid A3. Olmesartan significantly reduced reactive oxygen species originating from accumulated fat and attenuated the expression of nicotinamide adenine dinucleotide phospho hydrogenase oxidase subunits in adipose tissue. In cultured adipocytes, olmesartan acted as an antioxidant and improved adipocytokine dysregulation. Our results indicate that blockade of Ang II receptor ameliorates adipocytokine dysregulation and that such action is mediated, at least in part, by targeting oxidative stress in obese adipose tissue. Ang II signaling and subsequent oxidative stress in adipose tissue may be potential targets for the prevention of atherosclerotic cardiovascular disease in metabolic syndrome and also in metabolic syndrome-based CKD.
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PMID:Blockade of Angiotensin II type-1 receptor reduces oxidative stress in adipose tissue and ameliorates adipocytokine dysregulation. 1708 Jan 58

Chronic increases in blood flow increase arterial diameter and NO-dependent dilation in resistance arteries. Because endothelial dysfunction accompanies metabolic syndrome, we hypothesized that flow-mediated remodeling might be impaired in obese rat resistance arteries. Obese and lean Zucker rat mesenteric resistance arteries were exposed to chronic flow increases through arterial ligation in vivo: arteries exposed to high flow were compared with normal flow arteries. Diameter was measured in vitro in cannulated arteries using pressure arteriography. After 7 days, outward remodeling (diameter increased from 346+/-9 to 412+/-11 mum at 100 mm Hg) occurred in lean high-flow arteries. Endothelium-dependent tone was reduced in high-flow arteries from obese rats by contrast with lean animals. On the other hand, diameter enlargement occurred similarly in the 2 strains. The involvement of NO in endothelium-dependent dilation (evidenced by NO blockade) and endothelial NO synthase phosphorylation was smaller in obese than in lean rats. Superoxide anion and reduced nicotinamide-adenine dinucleotide phosphate oxidase subunit expression (p67phox and gp91phox) increased in obese rats and were higher in high-flow than in control arteries. Acute Tempol (a catalase mimetic), catalase plus superoxide dismutase, and l-arginine plus tetrahydrobiopterin restored endothelium-dependent dilation in obese rat normal and high-flow arteries to the level found in lean control arteries. Thus, flow-induced remodeling in obese resistance arteries was associated with a reduced endothelium-mediated dilation because of a decreased NO bioavailability and an excessive superoxide production. This dysfunction might have negative consequences in ischemic diseases in patients with obesity or metabolic syndrome.
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PMID:Flow-induced remodeling in resistance arteries from obese Zucker rats is associated with endothelial dysfunction. 1751 52

11Beta-hydroxysteroid dehydrogenase type 1 regulates glucocorticoid action and inhibition of this enzyme is a viable therapeutic strategy for the treatment of type 2 diabetes and the metabolic syndrome. Here, we report a potent and selective 11beta-hydroxysteroid dehydrogenase type 1 inhibitor with a binding mode elucidated from the co-crystal structure with the human 11beta-hydroxysteroid dehydrogenase type 1. The inhibitor is bound to the steroid-binding pocket making contacts with the catalytic center and the solvent channel. The inhibitor binding is facilitated by two direct hydrogen bond interactions involving Tyrosine183 of the catalytic motif Tyr-X-X-X-Lys and Alanine172. In addition, the inhibitor makes many hydrophobic interactions with both the enzyme and the co-factor nicotinamide adenine dinucleotide phosphate (reduced). In lean C57BL/6 mice, the compound inhibited both the in vivo and ex vivo 11beta-hydroxysteroid dehydrogenase type 1 activities in a dose-dependent manner. The inhibitory effects correlate with the plasma compound concentrations, suggesting that there is a clear pharmacokinetic and pharmacodynamic relationship. Moreover, at the same doses used in the pharmacokinetic/pharmacodynamic studies, the inhibitor did not cause the activation of the hypothalamic-pituitary-adrenal axis in an acute mouse model, suggesting that this compound exhibits biological effects with minimal risk of activating the hypothalamic-pituitary-adrenal axis.
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PMID:Structural characterization and pharmacodynamic effects of an orally active 11beta-hydroxysteroid dehydrogenase type 1 inhibitor. 1806 89

Insulin resistance is a key pathophysiological feature of metabolic syndrome. However, the initial events triggering the development of insulin resistance and its causal relations with dysregulation of glucose and fatty acids metabolism remain unclear. We investigated biological pathways that have the potential to induce insulin resistance in mice fed a high-fat diet (HFD). We demonstrate that the pathways for reactive oxygen species (ROS) production and oxidative stress are coordinately up-regulated in both the liver and adipose tissue of mice fed an HFD before the onset of insulin resistance through discrete mechanism. In the liver, an HFD up-regulated genes involved in sterol regulatory element binding protein 1c-related fatty acid synthesis and peroxisome proliferator-activated receptor alpha-related fatty acid oxidation. In the adipose tissue, however, the HFD down-regulated genes involved in fatty acid synthesis and up-regulated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex. Furthermore, increased ROS production preceded the elevation of tumor necrosis factor-alpha and free fatty acids in the plasma and liver. The ROS may be an initial key event triggering HFD-induced insulin resistance.
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PMID:Increased oxidative stress precedes the onset of high-fat diet-induced insulin resistance and obesity. 1864 Mar 84

Obesity is associated with an increased risk of diabetes type 2, dyslipidemia, and atherosclerosis. These cardiovascular and metabolic abnormalities are exacerbated by excessive dietary fat, particularly cholesterol and its metabolites. High adipose tissue glucocorticoid levels, generated by the intracellular enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), are also implicated in the pathogenesis of obesity, metabolic syndrome, and atherosclerosis. 11beta-HSD1 also interconverts the atherogenic oxysterols 7-ketocholesterol (7KC) and 7beta-hydroxycholesterol (7beta-HC). Here, we report that 11beta-HSD1 catalyzes the reduction of 7KC to 7beta-HC in mature 3T3-L1 and 3T3-F442A adipocytes, leading to cellular accumulation of 7beta-HC. Approximately 73% of added 7KC was reduced to 7beta-HC within 24 h; this conversion was prevented by selective inhibition of 11beta-HSD1. Oxysterol and glucocorticoid conversion by 11beta-HSD1 was competitive and occurred with a physiologically relevant IC(50) range of 450 nm for 7KC inhibition of glucocorticoid metabolism. Working as an inhibitor of 11beta-reductase activity, 7KC decreased the regeneration of active glucocorticoid and limited the process of differentiation of 3T3-L1 preadipocytes. 7KC and 7beta-HC did not activate liver X receptor in a transactivation assay, nor did they display intrinsic activation of the glucocorticoid receptor. However, when coincubated with glucocorticoid (10 nm), 7KC repressed, and 7beta-HC enhanced, glucocorticoid receptor transcriptional activity. The effect of 7-oxysterols resulted from the modulation of 11beta-HSD1 reaction direction, and could be ameliorated by overexpression of hexose 6-phosphate dehydrogenase, which supplies reduced nicotinamide adenine dinucleotide phosphate to 11beta-HSD1. Thus, the activity and reaction direction of adipose 11beta-HSD1 is altered under conditions of oxysterol excess, and could impact upon the pathophysiology of obesity and its complications.
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PMID:7-oxysterols modulate glucocorticoid activity in adipocytes through competition for 11beta-hydroxysteroid dehydrogenase type. 1902 97

This study was undertaken on the basis of several reports in the literature that pancreatic beta cells are capable of replication/regeneration and also being afforded protection against damage induced by streptozotocin. Nicotinamide was reported to give protection against streptozotocin-induced damage in rats. In the present study, two thiazolidine-4-ones with nicotinamide substitution were administered to Swiss albino mice with streptozotocin diabetes for 15 days. Concurrently, one group received nicotinic acid. Both the test compounds reversed the hyperglycaemia diabetic mice. Damage to pancreatic islets was also reduced in these groups compared to diabetic control and nicotinic acid treated groups. Since these compounds have been earlier found have antioxidant activity, one of the possible mechanisms of action could be by reducing oxidative stress in pancreas. Further, possibly by releasing nicotinamide in vivo, the molecules could have contributed to the NAD pool in pancreas and afforded protection. It is concluded that the test compounds have potential to be developed for multiple beneficial action in conditions like metabolic syndrome.
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PMID:Antidiabetic effect through islet cell protection in streptozotocin diabetes: a preliminary assessment of two thiazolidin-4-ones in Swiss albino mice. 1903 38

Excessive secretion of adrenal hormones, such as glucocorticoid and mineralocorticoid, leads to metabolic syndrome, including insulin resistance, obesity, and hypertension. These metabolic abnormalities are ameliorated by adrenalectomy (ADX). To identify pituitary mediators for ADX-induced physiological alterations, such as weight loss and hypotension, we investigated the effect of ADX on the pituitary transcriptome using serial analysis of gene expression (SAGE). SAGE method is based on isolation of short sequence tags, which usually correspond to unique mRNA species. The SAGE libraries were constructed from pituitary gland of intact (n = 51) and ADX (n = 12) mice. Thirty-one transcripts were differentially expressed between intact and ADX. Three transcripts encoding for proopiomelanocortin and three other transcripts involved in regulation of hormone secretion (neuromedin B, proprotein convertase subtilisin/kexin type 2, and IA-2) were induced by ADX. In addition, ADX increased the expression levels of genes encoding for cation extracellular matrix (matrix gamma-carboxyglutamate protein) and transport (solute carrier family 22 member 17). Conversely, ADX downregulated two transcripts involved in mitochondrial oxidative phosphorylation (nicotinamide adenine dinucleotide (NADH) dehydrogenase 3 and cytochrome c oxidase 3). Moreover, ADX significantly modulated the expression levels of one gene with uncharacterized function and 20 novel transcripts. This study reveals alterations of pituitary gene expressions that may be associated with ADX-induced physiological changes including weight loss.
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PMID:Regulation of pituitary gene expression by adrenalectomy. 1910 26


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