Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0020538 (hypertension)
170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Steroid dehydrogenase enzymes influence mammalian reproduction, hypertension, neoplasia, and digestion. The three-dimensional structures of steroid dehydrogenase enzymes reveal the position of the catalytic triad, a possible mechanism of keto-hydroxyl interconversion, a molecular mechanism of inhibition, and the basis for selectivity. Glycyrrhizic acid, the active ingredient in licorice, and its metabolite carbenoxolone are potent inhibitors of human 11 beta-hydroxysteroid dehydrogenase and bacterial 3 alpha, 20 beta-hydroxysteroid dehydrogenase (3 alpha, 20 beta-HSD). The three-dimensional structure of the 3 alpha, 20 beta-HSD carbenoxolone complex unequivocally verifies the postulated active site of the enzyme, shows that inhibition is a result of direct competition with the substrate for binding, and provides a plausible model for the mechanism of inhibition of 11 beta-hydroxysteroid dehydrogenase by carbenoxolone. The structure of the ternary complex of human 17 beta-hydroxysteroid dehydrogenase type 1 (17 beta-HSD) with the cofactor NADP+ and the antiestrogen equilin reveals the details of binding of an inhibitor in the active site of the enzyme and the possible roles of various amino acids in the catalytic cleft. The short-chain dehydrogenase reductase (SDR) family includes these steroid dehydrogenase enzymes and more than 60 other proteins from human, mammalian, insect, and bacterial sources. Most members of the family contain the tyrosine and lysine of the catalytic triad in a YxxxK sequence. X-ray crystal structures of 13 members of the family have been completed. When the alpha-carbon backbone of the cofactor binding domains of the structures are superimposed, the conserved residues are at the core of the structure and in the cofactor binding domain, but not in the substrate binding pocket.
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PMID:Steroid dehydrogenase structures, mechanism of action, and disease. 1066 97

The clinical benefit of cholesterol-lowering treatment is unknown in the Japanese elderly in whom the prevalence of morbidity and mortality related to coronary artery disease are known to be low. To evaluate the efficacy of cholesterol-lowering treatment with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor in Japanese elderly patients with documented coronary artery disease, 121 patients with serum cholesterol > or = 150 mg/dl prospectively received HMG-CoA reductase inhibitor, and 271 patients undergoing cholesterol-lowering treatment based on dietary therapy alone served as historical controls. The 143 elderly patients age > or = 65 years in the 2 groups had similar baseline serum total cholesterol level (201 +/- 30 vs 202 +/- 31 mg/dl), age (71 +/- 4 vs 70 +/- 4 years), proportion of men (37/53 vs 64/90), number of diseased vessels (1.7 +/- 0.9 vs 1.5 +/- 1.0), and incidences of other classical coronary risk factors, including hypertension, diabetes mellitus, smoking, obesity and family history of coronary artery disease. In all 392 patients, similar trends were observed, including serum total cholesterol level (208 +/- 33 vs 201 +/- 34 mg/dl). With HMG-CoA reductase inhibitors, serum total cholesterol level was reduced by 14% in the elderly subjects and by 13% in all patients. During the follow-up of approximately 3 years, cardiac events occurred in 5 patients (one elderly) in the treatment group and 38 patients (12 elderly) in the control group. Kaplan-Meier survival estimates revealed a higher event-free survival rate with HMG-CoA reductase inhibitors in the elderly subjects (98% vs 85%, p < 0.05) and in all patients (94% vs 86%, p < 0.05). Cox proportional hazard modeling also demonstrated a significant reduction in risk for cardiac events with drug therapy (relative risk 0.32, p < 0.05), in addition to the number of diseased vessels (relative risk 1.8, p < 0.01). In contrast, no additional risk was observed with advancing age. Cholesterol-lowering treatment with HMG-CoA reductase inhibitors is effective to improve the prognosis of Japanese elderly patients, including those with normal serum cholesterol level.
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PMID:Efficacy of cholesterol-lowering treatment in Japanese elderly patients with coronary artery disease and normal cholesterol level using 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor. 1071 30

Childhood obesity is accompanied by a variety of cardiovascular risk factors (hypertension, insulin resistance, dyslipidaemia) which tend to aggregate (syndrome X). 11beta-hydroxysteroid dehydrogenase (11beta-HSD) is supposed to play a role in the pathogenesis of hypertension and the development of syndrome X. There are two isoforms of 11beta-HSD. 11beta-HSD-2 is responsible for the inactivation of cortisol to inactive cortisone. In the case of impaired enzyme activity the ratio of urinary tetrahydrocortisol (THF)+ its isomer allotetrahydrocortisol (5alpha-THF)/tetrahydrocortisone (THE) is elevated. 11beta-HSD-1 is an oxo-reductase, which type catalyses the conversion of cortisone to cortisol. The aim of the present study was to investigate if there was any alteration in the urinary cortisol metabolites reflecting 11beta-HSD activity in hypertensive obese children (no.=15) as compared to normotensive obese (no.=11) and normotensive non-obese children (no.=15). We found an increased excretion of cortisol metabolites in hypertensive obese children compared to obese and normal - weight children having normal blood pressure. The ratio of THF+5alpha(THF/THE had a significant correlation with systolic blood pressure. On the basis of our study the ratio of THF+5alpha-THF/ THE reflecting on altered enzyme activity seems to be an independent factor influencing especially systolic blood pressure in hypertensive obese children.
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PMID:Urinary cortisol to cortisone metabolites in hypertensive obese children. 1100 67

The syndrome of apparent mineralocorticoid syndrome (AME) results from defective 11beta-hydroxysteroid dehydrogenase 2 (11beta-HSD2). This enzyme is co-expressed with the mineralocorticoid receptor (MR) in the kidney and converts cortisol to its inactive metabolite cortisone. Its deficiency allows the unmetabolized cortisol to bind to the MR inducing sodium retention, suppression of PRA and hypertension. Thus, the syndrome is a disorder of the kidney. We present here the first patient affected by AME cured by kidney transplantation. Formerly, she was considered to have a mild form of the syndrome (Type II), but progressively she developed renal failure which required dialysis and subsequent kidney transplantation. To test the ability of the transplanted kidney to normalise the patient's cortisol metabolism, we gave, in two different experiments, 25 and 50 mg/day of cortisone acetate or 15 and 30 mg/day of cortisol after inhibition of the endogenous cortisol by synthetic glucocorticoid (methylprednisolone and dexamethasone). The AME diagnostic urinary steroid ratios tetrahydrocortisol+5alphatetrahydrocortisol/tetrahydrocortisone and cortisol/cortisone were measured by gas chromatography/mass spectrometry. Transplantation resulted in lowering blood pressure and in normalization of serum K and PRA. After administration of a physiological dose of cortisol (15 mg/day), the urinary free cortisol/cortisone ratio was corrected (in contrast to the A-ring reduced metabolites ratio), confirming that the new kidney had functional 11beta-HSD2. This ratio was abnormally high when the supra-physiological dose of cortisol 30 mg/day was given. After cortisone administration, the tetrahydrocortisol+5alphatetrahydrocortisol/tetrahydrocortisone ratio resulted normalised with both physiological and supra-physiological doses, confirming that the hepatic reductase activity is not affected. As expected, the urinary free cortisol/cortisone ratio was normal with physiological, but increased after supra-physiological doses of cortisone. The described case indicates a normalisation of cortisol metabolism after kidney transplantation in AME patient and confirms the supposed pathophysiology of the syndrome. Moreover, it suggests a new therapeutic strategy in particularly vulnerable cohorts of patients inadequately responsive to drug therapy or with kidney failure.
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PMID:Does kidney transplantation normalise cortisol metabolism in apparent mineralocorticoid excess syndrome? 1100 70

Angiotensin II mediates most of the biological effects of the renin-angiotensin system (RAS), such as vasoconstriction and cell proliferation, via stimulation of the angiotensin II type 1 (AT1) receptor. The AT1 receptor plays a central role in the pathogenesis of atherosclerosis and hypertension. In parallel, hypercholesterolaemia is a major risk factor for the development and progression of cardiovascular diseases. The underlying molecular events, however, are understood only partially. An important mechanism may be the interaction between hypercholesterolaemia and AT1 receptor expression in vascular tissue. Low-density lipoprotein (LDL) cholesterol leads to a profound increase in AT1 receptor expression in cultured vascular smooth muscle cells as well as in hypercholesterolaemic rabbits. This up-regulation is associated with an enhanced functional response upon stimulation with angiotensin II. Over-expression of the vascular AT1 receptor can also be observed in hypercholesterolaemic men and is prevented by treatment with 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors. These findings may explain why hypercholesterolaemia is frequently associated with hypertension and why blockade of the RAS attenuates the progression of atherosclerosis.
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PMID:Angiotensin AT1 receptor over-expression in hypercholesterolaemia. 1102 85

The glucocorticoid metabolising enzymes, 11beta-hydroxysteroid dehydrogenases (11beta-HSD), play a critical role in determining the availability of glucocorticoids to activate their receptors and hence modulate target gene transcription. There are two isozymes, 11beta-HSD-1 and -2, which act in opposing directions. 11beta-HSD-2 acts as a dehydrogenase, converting active corticosterone (cortisol in humans) to its inactive 11-keto derivative (11-dehydrocorticosterone in rodents and cortisone in humans), whereas 11beta-HSD-1 acts as a reductase, regenerating active glucocorticoids in a tissue-specific manner. Owing to the lack of specific inhibitors of these enzymes, it has been difficult to confirm the roles and determine the importance of these enzymes in vivo. Hence, to address this, we produced transgenic mice with null-mutations in the genes encoding the 11beta-HSD-1 or 11beta-HSD-2 enzymes. 11beta-HSD-2 -/- mice show signs of hypertension, hypotonic polyuria, hypokalemia and hypochloremia. These symptoms arise from illicit activation of mineralocorticoid receptors by glucocorticoids, in the absence of the protective action of 11beta-HSD-2. The phenotype is directly comparable to the Syndrome of Apparent Mineralocorticoid Excess, seen in humans with mutations in the 11beta-HSD-2 gene. Mice lacking 11beta-HSD-1, however, show a more subtle phenotype with reduced activation of glucocorticoid-induced processes. They were unable to convert 11-dehydrocorticosterone to corticosterone in vivo, confirming 11beta-HSD-1 as the sole 11-reductase in the mouse. They have elevated circulating levels of plasma corticosterone levels and adrenal hyperplasia, but they also have attenuated glucocorticoid-induced activation of gluconeogenic enzymes in response to fasting, and lower glucose levels in response to obesity or stress. Overall, these transgenic models have proved very useful for elucidating the roles of 11beta-HSDs in vivo and will be a unique resource for investigating the importance of each enzyme in the diverse actions of glucocorticoids.
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PMID:Phenotypic analysis of mice bearing targeted deletions of 11beta-hydroxysteroid dehydrogenases 1 and 2 genes. 1116 6

We assessed the hepatic antioxidant status of spontaneously (SHR) and desoxicorticosterone acetate (DOCA)-induced hypertensive rats and that of respective normotensive Wistar Kyoto (WKY) and Sprague-Dawley (SPRD) rats. For this we evaluated, ex vivo in liver cytosols, reduced glutathione (GSH) content, glutathione-related enzyme (peroxidase, reductase and transferase) activities as well as the rate of lipid peroxidation in 9-11 week-old rats. The antioxidant status and the cytotoxicity of acetaminophen, a radical- and hydrogen peroxide-mediated hepatotoxic compound, were also assessed in vitro in cultured hepatocytes isolated from hypertensive (SHR, DOCA) and normotensive control (WKY, SPRD) rats. Our results suggest that a difference exists in the hepatic antioxidant status between rat strains, with GSH levels being lower (-15%) and lipid peroxidation rate higher (+30%) in WKY compared to SPRD rats. In hepatocyte cultures from WKY rats, both GSH content and catalase activity were lower (-30 and -70% respectively) compared to hepatocyte cultures from SPRD rats. This was associated with a 35% higher cytotoxicity of acetaminophen in cultured hepatocytes from WKY rats compared to that in hepatocytes from SPRD rats. Hypertension in DOCA rats (mmHg: 221+/-9 vs. 138+/-5 in control SPRD rats) was associated with decreases (about 30%) in both glutathione peroxidase (GSH-Px) and catalase activities, ex vivo in livers and in vitro in hepatocyte cultures. Hypertension in SHR (mmHg: 189+/-7 vs. 130+/-5 in control WKY rats) was also associated with decreases (about 50%) in GSH-Px activity, ex vivo in livers and in vitro in hepatocyte cultures but catalase activity was not modified. The IC50 of acetaminophen was also lower in hepatocytes from hypertensive rats compared to respective controls, which could be related to the weakened antioxidant status in hepatocytes from hypertensive rats. Our data thus suggest that hepatocyte cultures are appropriated tools in which to assess hepatotoxicity and hepatoprotection in hypertension.
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PMID:Strain difference (WKY, SPRD) in the hepatic antioxidant status in rat and effect of hypertension (SHR, DOCA). Ex vivo and in vitro data. 1133 Aug 29

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) significantly reduce cardiovascular mortality associated with hypercholesterolemia. There is evidence that statins exert beneficial effects in part through direct effects on vascular cells independent of lowering plasma cholesterol. We characterized the effect of a 30-day treatment with atorvastatin in normocholesterolemic, spontaneously hypertensive rats (SHR). Systolic blood pressure was significantly decreased in atorvastatin-treated rats (184+/-5 versus 204+/-6 mm Hg for control). Statin therapy improved endothelial dysfunction, as assessed by carbachol-induced vasorelaxation in aortic segments, and profoundly reduced angiotensin II-induced vasoconstriction. Angiotensin type 1 (AT(1)) receptor, endothelial cell NO synthase (ecNOS), and p22phox mRNA expression were determined with quantitative reverse transcription-polymerase chain reaction. Atorvastatin treatment downregulated aortic AT(1) receptor mRNA expression to 44+/-12% of control and reduced mRNA expression of the essential NAD(P)H oxidase subunit p22phox to 63+/-7% of control. Aortic AT(1) receptor protein expression was consistently decreased. Vascular production of reactive oxygen species was reduced to 62+/-12% of control in statin-treated SHR, as measured with lucigenin chemiluminescence assays. Accordingly, treatment of SHR with the AT(1) receptor antagonist fonsartan improved endothelial dysfunction and reduced vascular free-radical release. Moreover, atorvastatin caused an upregulation of ecNOS mRNA expression (138+/-7% of control) and an enhanced ecNOS activity in the vessel wall (209+/-46% of control). Treatment of SHR with atorvastatin causes a significant reduction of systolic blood pressure and a profound improvement of endothelial dysfunction mediated by a reduction of free radical release in the vasculature. The underlying mechanism could in part be based on the statin-induced downregulation of AT(1) receptor expression and decreased expression of the NAD(P)H oxidase subunit p22phox, because AT(1) receptor activation plays a pivotal role for the induction of this redox system in the vessel wall.
Hypertension 2001 Jun
PMID:HMG-CoA reductase inhibitors improve endothelial dysfunction in normocholesterolemic hypertension via reduced production of reactive oxygen species. 1140 94

The benefits of blood pressure lowering, lipid lowering, and glycemic control on morbidity and mortality have been established in major long-term clinical trials. The most extensive information is available for diuretics or beta-blockers in hypertension, hepatic hydroxymethyl glutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) in dyslipidemia, and insulin or sulfonylureas in diabetes. Other drug classes provide similar improvements in blood pressure, lipid profile, and glycemic control, and thereby might be expected to provide comparable long-term benefits. As a result, national guidelines advocate treating patients aggressively in order to achieve control of blood pressure low-density lipoprotein (LDL) cholesterol, and blood glucose. The risks associated with drug treatment are generally class-specific. Among antidiabetic agents, sulfonylureas and insulin are associated with risk for severe hypoglycemia, metformin with risk for lactic acidosis, and troglitazone with risk for idiosyncratic hepatocellular injury. Similarly, widely used antihypertensive and lipid-lowering agents are associated with risk for serious complications, such as angioedema with angiotensin-converting enzyme inhibitors, possible increased risk for myocardial infarction and cancer with calcium antagonists, and myositis and liver dysfunction with statins. Physicians must take an aggressive approach to patient management in order to achieve a level of disease control that optimally reduces risk for morbidity and mortality. Serious adverse events may occur rarely with most drug classes; these events can be minimized by appropriately monitoring or selecting patients for treatment.
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PMID:Safety of drugs commonly used to treat hypertension, dyslipidemia, and type 2 diabetes (the metabolic syndrome): part 1. 1146 7

Two isoforms of the enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD) interconvert the active glucocorticoid, cortisol, and inactive cortisone. 11beta-HSD1 is believed to act in vivo predominantly as an oxo-reductase using NADP(H) as a cofactor to generate cortisol. In contrast, 11beta-HSD2 acts exclusively as an NAD-dependent dehydrogenase inactivating cortisol to cortisone, thereby protecting the mineralocorticoid receptor from occupation by cortisol. In peripheral tissues, both enzymes serve to control the availability of cortisol to bind to the corticosteroid receptors. Defective expression of 11beta-HSD2 is implicated in patients with hypertension and intra-uterine growth retardation, while 11beta-HSD1 appears to be intricately involved in the conditions of apparent cortisone reductase deficiency, insulin resistance and visceral obesity. The ability of peripheral tissues to regulate corticosteroid concentrations through 11beta-HSD isozymes is established as an important mechanism in the pathogenesis of diverse human diseases. Modulation of enzyme activity may offer a novel therapeutic approach to treating human disease while circumventing the consequences of systemic glucocorticoid excess or deficiency.
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PMID:Cortisol metabolism and the role of 11beta-hydroxysteroid dehydrogenase. 1146 11


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