Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.15 (renin)
 35,795 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pepstatin, a specific inhibitor of pepsin, cathepsin D (E), renin, etc., was used in a new method to demonstrate the sites of enzymes. Pepstatin (Pst) was covalently attached to glutathione (GSH), using a dicyclohexylcarbodiimide, and CH3Hg+ was then put in the residue of SH for electron microscopic observation. Pst-GS-HgCH3 thus obtained was nonisotopical, had a very low molecular weight (about 1,200 daltons), and still almost completely retained its inhibitory activity. Sections of rat liver (less than 1 mm3 thick), prefixed by glutaraldehyde, were incubated in the prepared reaction medium. Cathepsin D, located in the lysosomes, was demonstrated by this compound, but when the sections were preincubated with pepstatin, this was not the case. These results demonstrate that mercury-labeled pepstatin is a useful reagent for the histochemical staining of acid proteases for electron microscope.
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PMID:Electron microscopic visualization of cathepsin D using mercury-labeled pepstatin as an enzyme inhibitor. 715

Glucocorticoid-remediable aldosteronism (GRA) is a hereditary cause of human hypertension in which aldosterone secretion is regulated by adrenocorticotropin (ACTH). A genetic mutation which causes GRA has recently been identified in our laboratory, a hybrid or chimeric gene fusing nucleotide sequences of the 11 beta-hydroxylase and aldosterone synthase genes. The finding that these chimeric gene duplications are sensitive and specific markers for GRA allows for a simple, direct genetic test for this disorder. In preliminary studies, we found a wide range of blood pressure levels (including normotension) in affected GRA subjects. Studies to data indicate that this is not related to environmental factors such as sodium intake. Another possibility is that chimeric gene expression is variable, with low blood pressure subjects having reduced gene expression. However, the data have not demonstrated differences in steroid levels in subjects with severe versus mild hypertension. In fact, it is likely that the wide range in blood pressure levels in affected subjects involves interaction of other systems which control blood pressure. Preliminary data in two kindreds suggest that blood pressure levels are reciprocally related to levels of urinary kallikrein excretion, supporting the notion that GRA is a hypertension-predisposing syndrome, with the resultant blood pressure the interaction of the gene mutation with other blood pressure regulatory systems. Although GRA is a mineralocorticoid excess state, as evidenced by profoundly suppressed levels of plasma renin activity, we have observed (contrary to the reported literature) that normokalemia is a typical finding. In one large normokalemic pedigree, preliminary findings indicate that these subjects have a normal capacity to excrete potassium.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Glucocorticoid-remediable aldosteronism (GRA): diagnosis, variability of phenotype and regulation of potassium homeostasis. 779 15

Organic nitrates are widely used in the treatment of ischemic heart disease. The magnitude and duration of their circulatory and ischemic effects are, however, rapidly reduced during continuous treatment. The specific mechanisms underlying this tolerance development are not clear. According to the most widely accepted theory, tolerance is due to an intracellular depletion of thiol compounds (GSH and/or cysteine) involved in the conversion of nitrates to vasoactive intermediates. This presentation deals with aspects of in vivo thiol/nitrate interactions in different experimental and clinical conditions. The major results and conclusions are: The acute hypotensive effect of NTG is decreased by lowering of intracellular GSH levels. This finding emphasizes that normal intracellular thiol levels are required for optimal conversion of nitrates. Thus, intracellular GSH plays a critical role in the metabolism of NTG. Despite development of tolerance to the hypotensive effect of NTG, arterial and venous thiol levels are similar in nitrate tolerant and non-tolerant animals, suggesting that depletion of vascular thiol compounds may not be the cause of nitrate tolerance in vivo. The effect of exogenous thiol administration on intravascular thiol levels are different in nitrate tolerant and non-tolerant conscious rats. Exogenous thiol compounds (e.g. NAC) augments the hypotensive effect of NTG by a tolerance nonspecific mechanism. This effect is most likely mediated by an extracellular and/or membrane-related nitrate/thiol interaction and formation of NO. N-acetylcysteine inhibits angiotensin converting enzyme and counteracts nitrate-induced stimulation of the renin angiotensin system in vivo. Therefore, in addition to an effect on nitrate metabolism, thiol compounds may modify tolerance development by attenuating nitrate-induced counter-regulatory mechanisms. In the clinical setting, co-administration of NAC and ISDN delays and partially prevents tolerance to the antianginal and antiischemic effects normally seen in patients with stable angina pectoris during treatment with ISDN. N-acetylcysteine treatment in humans, potentiates and preserves nitrate induced venodilation and augments the effect of nitrates on small resistance vessels without affecting the response to nitrates in larger sized arteries. Thus, administration of NAC may change the normal vasodilator profile of nitrates. In conclusion, changes in cellular thiol levels may modify the hemodynamic effect of organic nitrates and the cellular handling of thiols and/or thiol related enzymes is altered after development of nitrate tolerance. In addition, a tolerance unrelated thiol/nitrate interaction, potentiating the effect of nitrates, may occur after administration of exogenous thiol compounds. In the clinical setting administration of thiols results in a characteristic change in the vasodilator profile of nitrates and an attenuation of the nitrate-induced stimulation of the renin-angiotensin system. The combination of these effects probably contributes to the improvement in antianginal and antiischemic parameters which may be seen during continuous and prolonged treatment with nitrates and thiol compounds.
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PMID:Thiol compounds and organic nitrates. 874 3

GRA is an inherited disorder of aldosterone biosynthesis. To date, all cases have been the result of chimeric gene duplications in which the regulatory region of the 11-beta hydroxylase gene is fused to more distal coding sequences of the aldosterone synthase gene. This results in ectopic expression of aldosterone synthase in fasciculata cells. Genetic testing has been remarkably precise in identifying these individuals with 100% concordance of the presence of the chimeric gene with increases in 18-oxygenated cortisol products. Several implications follow from these findings. First, GRA may be more common in the hypertensive population than had been previously estimated, and second, genetic testing of subsets of the essential hypertensive population (e.g., those who have low plasma renin activity) may allow the identification of GRA patients who could then be treated specifically. We recommend that hypertensive patients with signs of aldosteronism and no radiologic evidence of an aldosteronoma, especially young hypertensive subjects with low renin activity, be genetically screened for GRA. To track the success of this approach and to identify responses to various therapeutic programs, a central international registry for GRA has been established. This registry not only provides access to screening for GRA, but also informational resources for patients and physicians.
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PMID:Glucocorticoid-remediable aldosteronism. 922 Dec 69

Glucocorticoid-remediable aldosteronism (GRA) is a rarely recognised cause of arterial hypertension. We report the features of a 13-year-old boy with hypertension (casual blood pressure (BP) 140-180/95-110 mm Hg) discovered during a routine paediatric check. Ambulatory BP monitoring (ABPM) revealed significant hypertension with an abolished nocturnal BP fall (mean daytime BP 155/108 mm Hg, mean night-time BP 156/104 mm Hg, nocturnal BP fall 0/4%) which was indicative of secondary hypertension. Despite triple antihypertensive drug therapy the hypertensive control was unsatisfactory. Laboratory tests revealed hypokalaemia (3.0 mmol/l), suppressed plasma renin activity (0.012 nmol/l/h) and high plasma aldosterone (1.190 nmol/l). The diagnosis of primary hyperaldosteronism was established and GRA was further confirmed by the presence of the chimaeric GRA-gene and dexamethasone therapy was initiated. During the next 2 months of dexamethasone therapy all three antihypertensive drugs were discontinued and BP remained under control with restoration to a normal nocturnal BP fall (mean daytime BP 129/77 mm Hg, mean night-time BP 113/64, nocturnal BP fall 12/17%). A change of therapy from dexamethasone to spironolactone was necessary due to the side effects of corticosteroids after 3 months. Spironolactone alone (0.8-2 mg/kg/day) was able to control the BP sufficiently. In conclusion, to our knowledge, this is the first reported case of abolished nocturnal BP fall in a patient with genetically proven GRA. This study indicates that GRA can cause severe hypertension even in children, associated with an abolished nocturnal BP fall. GRA thus should be excluded in all hypertensive patients with circadian BP rhythm disturbances.
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PMID:Abolished nocturnal blood pressure fall in a boy with glucocorticoid-remediable aldosteronism. 1061 71

Aldosterone, the major circulating mineralocorticoid, participates in blood volume and serum potassium homeostasis. Primary aldosteronism is a disorder characterised by hypertension and hypokalaemia due to autonomous aldosterone secretion from the adrenocortical zona glomerulosa. Improved screening techniques, particularly application of the plasma aldosterone:plasma renin activity ratio, have led to a suggestion that primary aldosteronism may be more common than previously appreciated among adults with hypertension. Glucocorticoid-remediable aldosteronism (GRA) was the first described familial form of hyperaldosteronism. The disorder is characterised by aldosterone secretory function regulated chronically by ACTH. Hence, aldosterone hypersecretion can be suppressed, on a sustained basis, by exogenous glucocorticoids such as dexamethasone in physiologic range doses. This autosomal dominant disorder has been shown to be caused by a hybrid gene mutation formed by a crossover of genetic material between the ACTH-responsive regulatory portion of the 11ss-hydroxylase (CYP11B1) gene and the coding region of the aldosterone synthase (CYP11B2) gene. Familial hyperaldosteronism type II (FH-II), so named to distinguish the disorder from GRA or familial hyperaldosteronism type I (FH-I), is characterised by autosomal dominant inheritance of autonomous aldosterone hypersecretion which is not suppressible by dexamethasone. Linkage analysis in a single large kindred, and direct mutation screening, has shown that this disorder is unrelated to mutations in the genes for aldosterone synthase or the angiotensin II receptor. The precise genetic cause of FH-II remains to be elucidated.
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PMID:Familial hyperaldosteronism. 1100 15

Monogenic or Mendelian forms of hypertension have ushered in a revolution in our knowledge. If we add information on syndromes involving low blood pressure, this knowledge base is doubled. Glucocorticoid-remediable aldosteronism, apparent mineralocorticoid excess, and mutations in the mineralocorticoid receptor gene have given us brilliant insights into mineralocorticoid-induced hypertension. The latter discovery has elucidated how mutations may modify the receptor sufficiently to allow erstwhile antagonists to have an agonistic action. The epithelial sodium channel (ENaC) has been elucidated. Gain-of-function mutations in the beta and gamma subunits of ENaC cause Liddle's syndrome. Loss-of-function mutations in all 3 subunits of ENaC cause hypotension (pseudohypoaldosteronism type I). Thus, all 3 subunits can be mutated, causing either hyper- or hypotension. Three loci have been described for Gordon's syndrome, pseudohypoaldosteronism type II; 2 members of the WNK (with no ly sine K) serine-threonine kinase family have recently been found to be responsible. Autosomal-dominant hypertension with brachydactyly features normal sodium and renin-angiotensin-aldosterone responses. The gene has been mapped to chromosome 12p. The condition is interesting because it may represent a novel neural form of hypertension. The elucidation of Mendelian blood pressure-regulatory disorders has been a resounding success.
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PMID:Monogenic forms of human hypertension. 1189 1

Aldosterone, the major circulating mineralocorticoid, particiates in blood volume and serum potassium homeostasis. Primary aldosteronism is a disorder characterized by hypertension and, in more severe form, hypokalemia, due to autonomous aldosterone secretion from the adrenocortical zona glomerulosa. Improved screening techniques, particularly application of the plasma aldosterone: plasma renin activity ratio, has led to renewed interest in Conn's original proposal that primary aldosteronism may be the cause of increased blood pressure in about 10% of adults with hypertension. Glucocorticoid-remediable aldosteronism (GRA) was the first described familial form of hyperaldosteronism. The disorder is characterized by aldosterone secretory function regulated chronically by ACTH. Hence, aldosterone hypersecretion can be chronically suppressed by exogenous glucocorticoids such as dexamethasone in physiologic-range doses. This autosomal dominant disorder has been shown to be caused by a hybrid gene mutation formed by a cross-over of genetic material between the ACTH-responsive regulatory portion of the 11b-hydroxylase (CYP11B1) gene and the coding region of the aldosterone synthase (CYP11B2) gene. Familial hyperaldosteronism type II (FH-II), so named to distinguish the disorder from GRA or familial hyperaldosteronism type I (FH-I), is characterized by inheritance consistent with an autosomal dominant pattern of autonomous aldosterone hypersecretion which is not suppressible by dexamethasone. Linkage analysis in a single large kindred, and direct mutation screening, has shown that this disorder is unrelated to mutations in the genes for aldosterone synthase or the angiotensin II receptor. A recent genome-wide search has identified a genetic linkage between FH-II in this single large kindred and polymorphic gene markers on chromosome 7 in a region that corresponds to cytogenetic band 7p22. This is the first identified locus for FH-II. Several possible candidate genes have been localized to the 7p22 region. The precise genetic cause of FH-II remains to be elucidated.
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PMID:New genetic insights in familial hyperaldosteronism. 1238 43

Primary aldosteronism (PA) is the most common cause of mineralocorticoid hypertension. Different studies, using the plasma aldosterone concentration to plasma renin activity ratio (PAC/PRA) for the screening of patients with hypertension, have shown a marked increase in the detection rate of PA. Idiopathic bilateral adrenal hyperplasia (IHA) and aldosterone-producing adrenal adenoma (APA), are the leading causes of primary aldosteronism. Glucocorticoid-remediable aldosteronism (GRA), also called familial hyperaldosteronism type I, familial hyperaldosteronism type II and carcinomas are rare causes of PA. Patients with hypertension and hypokalemia, those with a family history of hypertension and stroke at an early age, or patients with medication-resistant hypertension should be screened for PA using the PAC/PRA ratio. If a high ratio is found, a sodium loading test or a captopril test is warranted to confirm the diagnosis. Adrenal gland imaging is important in subtype differentiation (APA vs IHA). Adrenal venous sampling should be used when other tests prove inconclusive. Genetic testing has facilitated detection of GRA. Surgery is considered the treatment of choice for patients with APA, while bilateral hyperplasia subtypes are treated medically. Normalization of aldosterone levels or aldosterone receptor blockade are necessary to prevent the morbidity and mortality associated with hypertension, hypokalemia, and cardiovascular damage.
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PMID:Detecting and treating primary aldosteronism: primary aldosteronism. 1742 5

Primary aldosteronism is one of the most common causes of secondary hypertension. In recent years the prevalence has risen dramatically, from 1% to 14% of all hypertensive patients. This has been largely attributed to an increase in diagnosis. Primary aldosteronism is characterized by hypertension with or without hypokalemia and a high plasma aldosterone concentration (PAC) with a concurrent low plasma renin activity (PRA). The most common subtypes of primary aldosteronism are aldosterone-producing adenoma (42%) and bilateral idiopathic hyperaldosteronism (58%). Other less common subtypes (<1%) are glucocorticoid-remediable aldosteronism, and unilateral primary hyperplasia. Current treatment for primary aldosteronism relies on accurate subtype distinction and assessment of unilateral versus bilateral disease. Bilateral idiopathic hyperaldosteronism is best managed pharmacologically and improves with the use of aldosterone receptor antagonists. Combined treatment with sodium-channel blockers and calcium-channel blockers has also shown satisfactory results. Glucocorticoid-remediable aldosteronism responds well to treatment with low-dose glucocorticoids. Aldosterone producing adenoma and unilateral adrenal hyperplasia are appropriately treated with laparoscopic adrenalectomy. Following adrenalectomy blood pressure improves in 98% of these patients, but only about 33% require no further antihypertensive medication. Identifying the subgroups that will most benefit from adrenalectomy is paramount to formulating individual treatment strategies. In the past, treatment focused mainly on the correction of hypertension and electrolyte disturbances. Now, with accumulating evidence of the detrimental effects of aldosterone to the myocardium, vascular endothelium and kidneys, treatment also focuses on normalizing aldosterone levels or blocking aldosterone action at the receptor level. Therefore, it is essential to accurately identify the specific subtype of primary aldosteronism in order to select optimal treatment and to achieve successful patient outcomes.
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PMID:Prediction of successful outcome in patients with primary aldosteronism. 1805 76


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