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Query: UMLS:C0018801 (heart failure)
 72,216 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

As soon as there is evidence of left ventricular dysfunction, even before clinical signs of chronic cardiac failure (CCF) have developed, intrinsic and extrinsic compensatory mechanisms are brought into play by the body. The majority of these mechanisms are under the influence of neurohumoral systems. When neurohormonal responses persist, as in CCF, they take on a beneficial nature since they participate in adaptation of the cardiovascular system as a whole, but they are also harmful since they worsen the working conditions of the myocardium by their cardiac and peripheral effects. Hyperactivity of the noradrenergic sympathetic nervous system is seen in CCF with levels 2 to 3 times higher as compared with subjects with normal left ventricular function. The circadian rhythm of catecholamines is modified. The increase in circulatory catecholamines is all the greater when cardiac failure is advanced. This release of noradrenaline (NA) is under the control of arterial baroreceptors which normally send to the central nervous system inhibitory inflow from the sympathetic nervous system. Inhibitory tone is released in case of a fall in blood pressure. Noradrenaline acts on beta-predominant myocardial receptors (inotropic and tachycardic) and alpha-predominant vascular receptors, resulting in arteriolar vasoconstriction. There is rapid onset of down regulation of myocardial beta-receptors. This fall essentially concerns beta 1, but beta 2 also, since they may be affected according to the etiology of CCF (ischemia). The Renin Angiotensin System (RAS) is also activated by the fall in systemic blood pressure. This consists of a cascade of reactions leading to the synthesis of angiotensin II responsible for powerful vasoconstriction of all arterial areas, including the coronary vessels.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Metabolic changes in cardiac failure]. 130 Sep 20

The authors report on the case of a 7 week-old boy, in whom a renal mass was discovered after general symptoms were observed. Within 48 h, cardiac failure secondary to systemic arterial hypertension occurred, requiring intensive care. After a few days of mechanical ventilation and alternating elevated and low blood pressure, improvement was obtained with captopril and frusemide enabling further investigations to be carried out which lead to the diagnosis of Wilms tumor. During left-sided nephrectomy, elevated renin from the left renal vein was found. The post surgical course was excellent. Several authors have reported on the association between arterial hypertension and nephroblastoma as being the result of hyperreninism due to hilar compression; however severe hypertension was uncommon. Renin activity determination from the tumoral tissue had led to a different interpretation, ie primary hyperreninism: in the case of mesoblastic nephroma, only the non tumoral but compressed tissue contains a large quantity of renin; in the case of nephroblastomas, only the tumoral tissue contains renin. The question now is whether all or only certain nephroblastomas secrete renin.
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PMID:[Cardiac failure by major arterial hypertension secondary to nephroblastoma]. 133 61

Overall 210 patients aged 60-74 years suffering from coronary heart disease associated with chronic circulatory failure, stages I, IIA and IIB, 53 patients aged 45-59 years and 20 healthy persons aged 45-74 years were examined for the renin-angiotensin-aldosterone system and antidiuretic hormone. Renin activity, the concentration of aldosterone and vasopressin in blood plasma were investigated by radioimmunoassay. In the initial stage of heart failure, the elderly persons showed up more marked renin activation in blood plasma, followed by its lowering as decompensation progressed as well as an increase in the concentration of aldosterone and vasopressin, which resulted in the progress of circulatory failure.
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PMID:[The renin-angiotensin-aldosterone system and antidiuretic hormone in chronic circulatory failure in elderly subjects]. 144 Feb 54

The haemodynamic and neurohumeral response to a novel vasodilator calcitonin gene-related peptide was assessed in 11 patients with severe chronic heart failure. To assess tolerance, a continuous 48-h infusion (n = 6) was compared with a regimen of two successive 8-h infusions (n = 5). Haemodynamic response profiles were similar for both regimens, though the continuous infusion was poorly tolerated. Reductions in afterload reflected by changes in systemic vascular resistance and systemic blood pressure led to increases in cardiac index of at least 24%. Increments in heart rate accounted for much of the increase in cardiac output, there being no significant change in stroke volume index. The response was maintained over the 48-h study period with no tachyphylaxis. Renin and angiotensin levels increased significantly after 24 h. Calcitonin gene-related peptide exerts a favourable haemodynamic response in patients with severe heart failure. The dose used in this study, however, caused troublesome side-effects, particularly when given by continuous infusion. Further studies are required to establish the therapeutic range of this new peptide.
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PMID:Calcitonin gene-related peptide: a haemodynamic study of a novel vasodilator in patients with severe chronic heart failure. 146 27

Previous physiological and biochemical studies suggest the existence of an endogenous renin-angiotensin system (RAS) in the kidney. However, these data cannot exclude the contribution of the circulating RAS. Proof of the local synthesis of RAS components in the kidney has been obtained recently through the use of molecular biological techniques. Using Northern blot analysis, we have demonstrated the intrarenal expression of renin, angiotensinogen, and angiotensin-converting enzyme messenger RNAs. Employing in situ hybridization histochemistry, we have localized the intrarenal tissue sites of renin and angiotensinogen messenger RNA synthesis. Renin gene expression was found in cells of the juxtaglomerular apparatus. Angiotensinogen mRNA was primarily produced in the proximal convoluted tubule with lesser amounts in glomerular tufts and vasculature. These findings led us to hypothesize that the proximal tubule is a major site of renal Ang II synthesis and that locally synthesized Ang II might directly modulate tubular function. Both genes are subject to feedback regulation. Our studies showed that Ang II exerted a stimulatory effect on angiotensinogen but a negative feedback effect on renin gene expression. Dietary NaCl restriction stimulated the expression of both genes, although the onset of renin gene activation required more prolonged sodium chloride restriction. Furthermore, our data indicated that the sodium cation, irrespective of the anion, was primarily important in regulating renal angiotensinogen mRNA levels. Our studies also showed altered intrarenal renin or angiotensinogen expressions in pathophysiological states, e.g. in experimental heart failure and the spontaneously hypertensive rat. Taken together, these data support the existence of a intrarenal RAS and suggest its potential roles in the regulation of renal function in health and disease.
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PMID:Evolving concepts of the intrarenal renin-angiotensin system in health and disease: contributions of molecular biology. 170 1

This article describes investigations of several aspects of the molecular biology of the human renin gene and the three-dimensional structure of renin and its precursor, prorenin. Because of the importance of the RAS in hypertension, heart failure, renal failure, and possibly other disorders such as atherosclerosis, it is critical to understand the detailed control of this system. This control involves regulation at the transcriptional level, folding of prorenin, sorting of prorenin to a regulated pathway where it is proteolytically cleaved to renin and released in response to secretogogues, constitutive release of uncleaved prorenin, and nonproteolytic activation of prorenin. Currently there is great interest not only in the control of renin in the kidney, the sole source of circulating renin, but also at extrarenal sites where RAS activity may regulate cardiovascular functions. The renin gene was found to be expressed significantly in the renal juxtaglomerular cells and several other cell types. Most tissue culture cells did not express the gene; exceptions were cultured SK-LMS-1 cells and cAMP-stimulated human lung fibroblasts. Cultured human uterine-placental cells expressed the human renin gene at levels higher than in other cell types assessed. Renin mRNA had the same start site in the placental cells as the kidney and was regulated by calcium ionophores and cAMP. Thus, these cells provide primary nontransformed human cells to study the homologous human promoter. Transfected renin promoters showed cell type-specific expression and cAMP responsiveness in these cells in constructs containing as few as 102 bp of 5'-flanking DNA. DNA upstream from this appears to contain an inhibitory element(s) that may have some tissue specificity in its distribution. The cAMP response is not due to cAMP induction of a transcription factor that secondarily affects the renin promoter. A novel element may be involved, since the promoter does not contain a CRE element that mediates many cAMP responses, and the cells do not appear to respond to another known cAMP-responsive transcription factor, AP-2. Studies with transfected vectors expressing a mutant cAMP-responsive protein kinase A regulatory subunit suggest that cAMP is not responsible for basal renin promoter activity in the placental cells. By contrast, cAMP induces in essence gene activation in WI26VA4 transformed human lung fibroblasts in which renin mRNA levels increase by up to 150-fold in response to forskolin. Thus, cAMP may activate renin gene expression under certain circumstances and tissue-specific renin gene expression may be directed by more than one mechanism.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Molecular biology of human renin and its gene. 174 21

The J-7 total artificial heart (TAH) can restore normal vascular hemodynamics in humans treated for end-stage heart failure, but less is known regarding its effect on hormones elevated under these conditions. A 49-year-old man with NYHA Class IV end-stage heart failure received a J-7-70 TAH as a bridge to transplantation. Pre-TAH cardiac index was less than 2 L/min/m2 with end organ dysfunction, increased venous and pulmonary pressures, and a low arterial pressure. The TAH provided an immediate cardiac index greater than 3 L/min/m2 with normal hemodynamics and organ function. Pre-TAH renin, aldosterone, and atrial natriuretic factor (ANF) levels were markedly elevated: 147 ng/dl, 29.4 ng/dl, and 380 pg/ml, respectively. All values declined dramatically by the fifth postoperative day, with the aldosterone and ANF values returning to normal at 11.5 ng/dl and 37 pg/ml, respectively. Renin levels reached normal values by the fourth postoperative week. Once normal values were obtained, they remained in this range for the 57 days of TAH function. The TAH, used in end-stage heart failure, restores normal hemodynamics and compensatory hormonal levels. These hormones can be used as indicators of proper TAH function in such patients.
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PMID:Effect of a total artificial heart on adaptive hormonal responses in humans with end-stage heart failure. 253 27

There has been considerable interest in the existence of an intrarenal renin-angiotensin system and its physiological implications. Recent demonstrations of renin, angiotensinogen and angiotensin converting enzyme messenger (m)RNAs in the kidney have provided strong evidence for the presence of an independent local system. This has been further supported by the demonstration of tissue-specific regulation of renin and angiotensinogen mRNA expression which may lead to differential systemic and intrarenal angiotensin activities. Using in situ hybridization, we have localized the intrarenal sites of gene expression and possible angiotensin production. One major site appears to be the proximal tubule, where local angiotensin can regulate sodium reabsorption and urine pH. Renin and angiotensinogen mRNA expressions are regulated by several common factors. In particular, sodium depletion stimulates the expression of both genes in the kidney, increasing the production of intrarenal angiotensin that is important in maintaining sodium homeostasis. Renal renin and angiotensinogen mRNA levels are altered in experimental heart failure and the spontaneously hypertensive rat (SHR). These changes in intrarenal renin and angiotensinogen mRNA expression may be important in the renal pathophysiology of these diseases.
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PMID:Molecular biology and pathophysiology of the intrarenal renin-angiotensin system. 255 71

Renin plays a major role in the control of blood pressure and water and electrolyte metabolism and it is clear that blocking of this system is particularly effective in the treatment of essential hypertension and heart failure. A large number of converting enzyme inhibitors have been synthesized. Converting enzyme inhibitors are remarkably active in heart failure and they reduce microalbuminuria and possibly maintain glomerular function. Blocking of the renin-angiotensin system by converting enzyme inhibitors is not accompanied by hypotension or reflex stimulation of the sympathetic nervous system. Converting enzyme inhibitors represent a major therapeutic advance in the field of cardiovascular and renal disease but the long-term effects of decreased angiotensin II levels are unknown. There are other ways to inhibit the renin-angiotensin system. The recent discovery of orally-active non-peptide angiotensin II antagonists opens a range of fascinating prospects. Another approach consists in inhibiting the reaction of renin on angiotensinogen, which is remarkably selective. Although it is too early to know whether these new approaches will be less active, more active or as active as current converting enzyme inhibitors, they may constitute a progress in relation to currently available treatments.
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PMID:New therapeutic prospects of renin-angiotensin system inhibition. 269 Nov 25

The renin angiotensin system is activated in the majority of patients with chronic congestive heart failure of moderate to severe symptomatology. Renin release may result from one of several different stimuli: renal tubular sodium delivery and sensing by the macula densa, sympathetic nervous system activity, and baroreceptor to changes in renal blood flow. Difficulties arise with an analysis of renin angiotensin system activity due to the necessity for diuretic therapy in the majority of these patients. Despite the presence of diuretic therapy, however, there is a wide range of renin angiotensin system activity. In evaluating this activity the administration of a converting enzyme inhibitor will block the contribution of angiotensin mediated vasoconstriction, thereby confirming the importance of the renin angiotensin system activity as a mediator of the long-term consequences of heart failure. In situations of low plasma renin activity, vasoconstriction is mediated by an alternate mechanism. The mechanisms of this non-renin mediated vasoconstriction are less apparent, but may include calcium mediated vasoconstriction, and the effects of increased cytosolic content. This low renin group of patients appear to be very sensitive to reversal of vasoconstriction by calcium channel antagonists, especially when converting enzyme inhibitors are ineffective. In an analysis of the factors that may result in renin release, tubular delivery of sodium to the macula densa may emerge as the most important regulator of renin release.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The renin system and atrial natriuretic hormone in congestive heart failure. 294 42


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