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Renin-angiotensin System (renin-angiotensin + system)
Selected AbstractsHyperkalemia as a Constraint to Therapy With Combination Renin-Angiotensin System Blockade: The Elephant in the RoomJOURNAL OF CLINICAL HYPERTENSION, Issue 2 2009Murray Epstein MD First page of article [source] Renin-Angiotensin System Blockade: Therapeutic Implications Beyond Blood Pressure ControlJOURNAL OF CLINICAL HYPERTENSION, Issue 2007Norman M. Kaplan MD No abstract is available for this article. [source] Renin-angiotensin system revisitedJOURNAL OF INTERNAL MEDICINE, Issue 3 2008F. Fyhrquist Abstract. New components and functions of the renin-angiotensin system (RAS) are still being unravelled. The classical RAS as it looked in the middle 1970s consisted of circulating renin, acting on angiotensinogen to produce angiotensin I, which in turn was converted into angiotensin II (Ang II) by angiotensin-converting enzyme (ACE). Ang II, still considered the main effector of RAS was believed to act only as a circulating hormone via angiotensin receptors, AT1 and AT2. Since then, an expanded view of RAS has gradually emerged. Local tissue RAS systems have been identified in most organs. Recently, evidence for an intracellular RAS has been reported. The new expanded view of RAS therefore covers both endocrine, paracrine and intracrine functions. Other peptides of RAS have been shown to have biological actions; angiotensin 2,8 heptapeptide (Ang III) has actions similar to those of Ang II. Further, the angiotensin 3,8 hexapeptide (Ang IV) exerts its actions via insulin-regulated amino peptidase receptors. Finally, angiotensin 1,7 (Ang 1,7) acts via mas receptors. The discovery of another ACE2 was an important complement to this picture. The recent discovery of renin receptors has made our view of RAS unexpectedly complex and multilayered. The importance of RAS in cardiovascular disease has been demonstrated by the clinical benefits of ACE inhibitors and AT1 receptor blockers. Great expectations are now generated by the introduction of renin inhibitors. Indeed, RAS regulates much more and diverse physiological functions than previously believed. [source] Treatment of diabetic nephropathy in its early stagesDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 2 2003Giacomo Deferrari Abstract Diabetic nephropathy is one of the most frequent causes of end-stage renal disease (ESRD), and, in recent years, the number of diabetic patients entering renal replacement therapy has dramatically increased. The magnitude of the problem has led to numerous efforts to identify preventive and therapeutic strategies. In normoalbuminuric patients, optimal glycemic control (HbA1c lower than 7.5%) plays a fundamental role in the primary prevention of ESRD [weighted mean relative risk reduction (RRR) ,37% for metabolic control versus trivial renoprotection for intensive anti-hypertensive therapy or ACE-inhibitors (ACE-I)]. In the microalbuminuric stage, strict glycemic control probably reduces the incidence of overt nephropathy (weighted mean RRR ,50%), while blood pressure levels below 130/80 mmHg are recommended according to the average blood pressure levels obtained in various studies. In normotensive patients, ACE-I markedly reduce the development of overt nephropathy almost regardless of blood pressure levels; in hypertensive patients, ACE-I are less clearly active (weighted mean RRR ,23% versus other drugs), whereas angiotensin-receptor blockers (ARB) appear strikingly renoprotective. Once overt proteinuria appears, it is uncertain whether glycemic control affects the progression of nephropathy. In type 1 diabetes, various anti-hypertensive treatments, mainly ACE-I, are effective in slowing down the progression of nephropathy; in type 2 diabetes, two recent studies demonstrate that ARB are superior to conventional therapy or calcium channel blockers (CCB). In clinical practice, pharmacological tools are not always used to the best benefit of the patients. Therefore, clinicians and patients need to be educated regarding the renoprotection of drugs inhibiting the renin-angiotensin system (RAS) and the overwhelming importance of achieving target blood pressure. Copyright © 2003 John Wiley & Sons, Ltd. [source] Association analysis of genes in the renin-angiotensin system with subclinical cardiovascular disease in families with Type 2 diabetes mellitus: The Diabetes Heart StudyDIABETIC MEDICINE, Issue 3 2006K. P. Burdon Abstract Aims Cardiovascular disease (CVD) is a major complication of Type 2 diabetes mellitus. The renin-angiotensin system (RAS) and nitric oxide production are both important regulators of vascular function and blood pressure. Genes encoding proteins involved in these pathways are candidates for a contribution to CVD in diabetic patients. We have investigated variants of the angiotensinogen (AGT), angiotensin converting enzyme (ACE), angiotensin type 1 receptor (AT1R) and endothelial nitric oxide synthase (NOS3) genes for association with subclinical measures of CVD in families with Type 2 diabetes mellitus (T2DM). Methods Atherosclerosis was measured by carotid intima-media thickness and calcification of the carotid and coronary arteries in 620 European Americans and 117 African Americans in the Diabetes Heart Study. Because of the role of these systems in blood pressure regulation, blood pressure was also investigated. Results Compelling evidence of association was not detected with any of the SNPs with any outcome measures after adjustments for covariates despite sufficient power to detect relatively small differences in traits for specific genotype combinations. Conclusions Genetic variation of the RAS and NOS3 genes do not appear to strongly influence subclinical cardiovascular disease or blood pressure in this diabetic population. [source] Type 2 diabetes, obesity, and the renal response to blocking the renin system with irbesartanDIABETIC MEDICINE, Issue 10 2002D. A. Price Abstract Aim Our recent studies revealed a striking but variable enhancement of renal vasodilator responses to blockers of the renin-angiotensin system in subjects with diabetes mellitus, possibly reflecting the level of intrarenal activation of the renin-angiotensin system, and thus a risk of nephropathy. As obesity is a common finding in diabetic individuals, and obesity has been linked to an increase in plasma angiotensinogen levels, we enrolled diabetic subjects with a wide range of body mass index (BMI) for this study. Methods Twelve Type 2 diabetic subjects in balance on a low sodium diet participated after baseline renal plasma flow and glomerular filtration measurements were made. Each subject then received 150 mg irbesartan, and renal function was measured every 45 min for 4 h. Results The average vasodilator response to irbesartan was 174 ± 33 ml/min. No correlation was found between renal plasma flow response to irbesartan and duration of diabetes, baseline glucose, or HbA1c level. BMI, our measure of obesity, was highly correlated to the renal response to irbesartan (r = 0.7; P = 0.01). Conclusions Our findings suggest an important role for obesity in activating the intrarenal renin system, perhaps via production of angiotensinogen. BMI may be an indicator of risk of nephropathy. [source] New insights into the pathophysiology of diabetic nephropathy: from haemodynamics to molecular pathologyEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 12 2004G. Wolf Abstract Although debated for many years whether haemodynamic or structural changes are more important in the development of diabetic nephropathy, it is now clear that these processes are interwoven and present two sides of one coin. On a molecular level, hyperglycaemia and proteins altered by high blood glucose such as Amadori products and advanced glycation end-products (AGEs) are key players in the development of diabetic nephropathy. Recent evidence suggests that an increase in reactive oxygen species (ROS) formation induced by high glucose-mediated activation of the mitochondrial electron-transport chain is an early event in the development of diabetic complications. A variety of growth factors and cytokines are then induced through complex signal transduction pathways involving protein kinase C, mitogen-activated protein kinases, and the transcription factor NF-,B. High glucose, AGEs, and ROS act in concert to induce growth factors and cytokines. Particularly, TGF-, is important in the development of renal hypertrophy and accumulation of extracellular matrix components. Activation of the renin-angiotensin system by high glucose, mechanical stress, and proteinuria with an increase in local formation of angiotensin II (ANG II) causes many of the pathophysiological changes associated with diabetic nephropathy. In fact, it has been shown that angiotensin II is involved in almost every pathophysiological process implicated in the development of diabetic nephropathy (haemodynamic changes, hypertrophy, extracellular matrix accumulation, growth factor/cytokine induction, ROS formation, podocyte damage, proteinuria, interstitial inflammation). Consequently, blocking these deleterious effects of ANG II is an essential part of every therapeutic regiment to prevent and treat diabetic nephropathy. Recent evidence suggests that regression of diabetic nephropathy could be achieved under certain circumstances. [source] Migraine prophylaxis with drugs influencing the renin-angiotensin systemEUROPEAN JOURNAL OF NEUROLOGY, Issue 7 2007L. J. Stovner No abstract is available for this article. [source] Angiotensin-Converting Enzyme Genotype Affects the Response of Human Skeletal Muscle to Functional OverloadEXPERIMENTAL PHYSIOLOGY, Issue 5 2000Jonathan Folland The response to strength training varies widely between individuals and is considerably influenced by genetic variables, which until now, have remained unidentified. The deletion (D), rather than the insertion (I), variant of the human angiotensin-converting enzyme (ACE) genotype is an important factor in the hypertrophic response of cardiac muscle to exercise and could also be involved in skeletal muscle hypertrophy , an important factor in the response to functional overload. Subjects were 33 healthy male volunteers with no experience of strength training. We examined the effect of ACE genotype upon changes in strength of quadriceps muscles in response to 9 weeks of specific strength training (isometric or dynamic). There was a significant interaction between ACE genotype and isometric training with greater strength gains shown by subjects with the D allele (mean ± S.E.M.: II, 9.0 ± 1.7%; ID, 17.6 ± 2.2%; DD, 14.9 ± 1.3%, ANOVA, P 0.05). A consistent genotype and training interaction (ID DD II) was observed across all of the strength measures, and both types of training. ACE genotype is the first genetic factor to be identified in the response of skeletal muscle to strength training. The association of the ACE I/D polymorphism with the responses of cardiac and skeletal muscle to functional overload indicates that they may share a common mechanism. These findings suggest a novel mechanism, involving the renin-angiotensin system, in the response of skeletal muscle to functional overload and may have implications for the management of conditions such as muscle wasting disorders, prolonged bed rest, ageing and rehabilitation, where muscle weakness may limit function. [source] Toward better renoprotection: Lessons from angiotensin receptor blockersHEMODIALYSIS INTERNATIONAL, Issue 2 2007Toshio MIYATA Abstract The rising tide of chronic kidney disease (CKD), especially diabetic nephropathy, has become a worldwide catastrophe. However, therapeutic options to prevent or retard the progression of CKD still remain very limited. The understanding of its molecular mechanisms and the delineation of tools able to modify them are thus of critical importance. The discovery that some antihypertensive agents inhibiting the renin-angiotensin system, such as angiotensin II type 1 receptor blockers, protect the kidney opens new therapeutic perspectives. In this article, we focus on their renoprotective actions beyond blood pressure lowering. [source] Abdominal Obesity Is Associated With Potassium Depletion and Changes in Glucose Homeostasis During Diuretic TherapyJOURNAL OF CLINICAL HYPERTENSION, Issue 6 2008Lydia Sebba Souza Mariosa MD The activation of the renin-angiotensin system (RAS) is an important mechanism that contributes to hypertension in obese individuals. Thiazide diuretics also activate the RAS in response to volume contraction and can lead to a decrease in serum potassium values and glucose metabolism abnormalities. To evaluate the impact of abdominal obesity on potassium depletion and glucose homeostasis in hypertensive patients receiving thiazide therapy, the authors studied 329 hypertensive patients without known diabetes or impaired renal function. Patients were stratified into 2 major groups according to whether they used thiazide diuretic therapy, and each group was further divided in 2 subgroups according to the presence of abdominal obesity. The authors demonstrated that obese patients receiving diuretic therapy had lower plasma potassium levels and higher glucose values compared with nonobese patients receiving diuretic therapy. In conclusion, abdominal obesity predisposes to potassium depletion during diuretic therapy in association with effects on glucose homeostasis. [source] Angiotensin-Converting Enzyme Inhibitors in the Treatment of Hypertension: An UpdateJOURNAL OF CLINICAL HYPERTENSION, Issue 11 2007William B. White MD Angiotensin-converting enzyme inhibitors are an important treatment option for hypertension, especially when elevated blood pressure exists in the presence of diabetes mellitus, chronic kidney disease, or congestive heart failure. This article reviews some of the pathophysiologic mechanisms involved in patients with hypertension and these comorbidities and how they relate to the renin-angiotensin system (RAS). Inhibition of the RAS when utilized along with other antihypertensive medications has been particularly effective in hypertensive patients with type 2 diabetes, chronic kidney disease, and vascular disorders; consensus group guidelines have reflected this in their treatment recommendations. Clinical trial data demonstrate that the effectiveness of RAS blockers is enhanced by maximizing the daily dose and combining these medications with thiazide diuretics. [source] Pathophysiology of Target-Organ Disease: Does Angiotensin II Remain the Key?JOURNAL OF CLINICAL HYPERTENSION, Issue 2007Ronald G. Victor MD Basic research provides an increasingly compelling rationale for renin-angiotensin system (RAS) blockade in hypertension treatment and cardiovascular risk reduction. Clinical trials addressing blood pressure-independent effects of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers, however, have yielded mixed results, in part because of incomplete RAS blockade. Animal studies have shed new light on the complexity of RAS pathways involved in the induction of target-organ damage. New outcomes trials are under way to explore the full potential of more complete RAS blockade with regard to cardiovascular target-organ protection. [source] Your Drug, My Drug, or Our Drugs: How Aggressive Should We Be With Antihypertensive Therapy?JOURNAL OF CLINICAL HYPERTENSION, Issue 2005Joseph L. Izzo Jr. MD In the prevention of hypertensive complications, especially stroke and kidney disease, "lower is better" because for each decrease of 20 mm Hg systolic or 10 mm Hg diastolic pressure in the population, cardiovascular risk is halved. Ideally, the goal for each patient should be to reach the lowest blood pressure that is well tolerated, a value that may be well below the arbitrary threshold value of 140/90 mm Hg. For the majority of "uncomplicated hypertensives," the question of single-drug therapy is essentially moot, because more than one agent is almost always required to optimally control blood pressure. In individuals who already have heart or kidney disease, there are compelling indications for the use of drugs that block the renin-angiotensin system, but the large outcome studies that spawned these recommendations are themselves combination trials. Thus, in virtually all patients, more than one drug is indicated. The best combinations take advantage of long durations of action and complementary mechanisms of action of the component and are not only able to effectively lower blood pressure, but also to favorably affect the natural history of hypertensive complications. Regimens,including fixed-dose combination products,that combine a thiazide diuretic or calcium antagonist with an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker are most efficient. In summary, why would an astute clinician (or informed patient) be satisfied with the relatively limited effects of any single class of antihypertensive agents when better overall protection is possible? [source] Type 2 Diabetes: RENAAL and IDNT,The Emergence of New Treatment OptionsJOURNAL OF CLINICAL HYPERTENSION, Issue 1 2002Domenic A. Sica MD The Reduction in End Points in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) study and the Irbesartan Diabetic Nephropathy Trial (IDNT) are two recently reported trials with hard end points, conducted in patients in advanced stages of diabetic nephropathy. Two other studies,the Irbesartan Microalbuminuria Study (IRMA)-2 and the Microalbuminuria Reduction with Valsartan study (MARVAL),were trials conducted in patients with type 2 diabetes with microalbuminuria, a cardiovascular risk factor associated with early-stage diabetic nephropathy. These trials all had a common theme,that is, does an angiotensin receptor blocker (ARB) interfere with the natural history of diabetic nephropathy in a blood pressure-independent fashion? Without question, the results of these trials legitimatize the use of the ARB class in forestalling the deterioration in renal function, which is almost inevitable in the patient with untreated diabetic nephropathy. These data can now be added to the vast array of evidence supporting angiotensin-converting enzyme (ACE) inhibitor use in patients with nephropathy associated with type 1 diabetes. It now appears a safe conclusion that the patient with diabetic nephropathy should receive therapy with an agent that interrupts the renin-angiotensin system. These studies have not resolved the question as to whether an ACE inhibitor or an ARB is the preferred agent in people with nephropathy from type 1 diabetes, though the optimal doses of these drugs remain to be determined. Head-to-head studies comparing ACE inhibitors to ARBs in diabetic nephropathy are not likely to occur, so it is unlikely that comparable information will be forthcoming with ACE inhibitors. An evidence-based therapeutic approach derived from these trials would argue for ARBs to be the foundation of therapy in the patient with type 2 diabetes and nephropathy. [source] Renin-angiotensin system revisitedJOURNAL OF INTERNAL MEDICINE, Issue 3 2008F. Fyhrquist Abstract. New components and functions of the renin-angiotensin system (RAS) are still being unravelled. The classical RAS as it looked in the middle 1970s consisted of circulating renin, acting on angiotensinogen to produce angiotensin I, which in turn was converted into angiotensin II (Ang II) by angiotensin-converting enzyme (ACE). Ang II, still considered the main effector of RAS was believed to act only as a circulating hormone via angiotensin receptors, AT1 and AT2. Since then, an expanded view of RAS has gradually emerged. Local tissue RAS systems have been identified in most organs. Recently, evidence for an intracellular RAS has been reported. The new expanded view of RAS therefore covers both endocrine, paracrine and intracrine functions. Other peptides of RAS have been shown to have biological actions; angiotensin 2,8 heptapeptide (Ang III) has actions similar to those of Ang II. Further, the angiotensin 3,8 hexapeptide (Ang IV) exerts its actions via insulin-regulated amino peptidase receptors. Finally, angiotensin 1,7 (Ang 1,7) acts via mas receptors. The discovery of another ACE2 was an important complement to this picture. The recent discovery of renin receptors has made our view of RAS unexpectedly complex and multilayered. The importance of RAS in cardiovascular disease has been demonstrated by the clinical benefits of ACE inhibitors and AT1 receptor blockers. Great expectations are now generated by the introduction of renin inhibitors. Indeed, RAS regulates much more and diverse physiological functions than previously believed. [source] A Rodent Model of Alcoholic Heart Muscle Disease and Its Evaluation by EchocardiographyALCOHOLISM, Issue 3 2001Shann D. Kim Background: Transthoracic echocardiography was used in a rodent animal model to determine whether long-term alcohol consumption (8 and 12 months) was associated with the development of a dilated cardiomyopathy. We also investigated whether alcohol-induced changes in cardiac structure corresponded to activation of the renin-angiotensin system and the natriuretic peptide (NP) system. Methods: Male rats received either the Lieber-DeCarli liquid alcohol diet (EtOH) (9%v/v) (n= 8) or control diet (CON) (n= 8). Echocardiography (echo) was used to determine left-ventricular (LV) dimensions, and isolated heart studies (Langendorff and atrium) were used to assess ex vivo contractility. Plasma and tissue angiotensin-I converting enzyme (ACE) activity was measured. Gene expression, plasma, and tissue levels of the NPs were determined by northern blot analysis and radioimmunoassay, respectively. Results: After 8 months of alcohol consumption, there was a trend for the end diastolic dimension, end systolic dimension, and LV mass to be greater in the 8 month EtOH group compared with the CON group. However, after 12 months of alcohol consumption, significant increases were found between the groups in several echo parameters. Tissue ACE activity (nmoles/min/mg protein) was greater in the 12 month EtOH group compared with the 12 month CON and 8 month EtOH group (p < 0.05). We found no differences between groups in gene expression (messenger RNA), plasma, and tissue levels of the NPs. Conclusions: Echocardiography revealed that 8 to 12 months of alcohol consumption was associated with the development of a dilated cardiomyopathy. However, this was not preceded by an increase in tissue ACE activity, and these changes occurred in the absence of increased plasma and LV tissue levels of the NPs. [source] The angiotensin II receptor blocker candesartan improves survival and mesenteric perfusion in an acute porcine endotoxin modelACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 2 2004M. Laesser Background:, Blockade of the angiotensin II type 1 (AT1) receptor has been demonstrated to ameliorate splanchnic hypoperfusion in acute experimental circulatory failure. This study focused on hemodynamic changes and survival in pigs treated with AT1 blockade prior to or during acute endotoxinemia. Methods:,Escherichia coli lipopolysaccharide endotoxin was infused in anesthetized and mechanically ventilated pigs. Systemic, renal, mesenteric and jejunal mucosal perfusion as well as systemic oxygen and acid-base balance were monitored. The selective AT1 receptor blocker candesartan was administered prior to as well as during endotoxinemia. Control animals received the saline vehicle. Results:, Pre-treatment with candesartan resulted in higher survival rate (83%, 10 out of 12 animals) compared with 50% (6 of 12) in control animals and 27% (3 of 11) in animals treated during endotoxinemia. Pre-treatment with candesartan resulted in higher cardiac output, mixed venous oxygen saturation, arterial standard base-excess, portal venous blood flow during endotoxin infusion compared with controls and animals treated during endotoxinemia. No adverse effects were found on neither systemic nor renal circulation. Conclusion:, The favorable results of AT1 receptor blockade prior to endotoxinemia are lost when blockade is established during endotoxinemia demonstrating the importance of the renin-angiotensin system and its dynamic involvement in acute endotoxinemic shock. [source] Review Article: Review: Endothelial-myofibroblast transition, a new player in diabetic renal fibrosisNEPHROLOGY, Issue 5 2010JINHUA LI ABSTRACT Diabetic nephropathy (DN) is the most common cause of chronic kidney failure and end-stage renal disease in the Western world. Studies from diabetic animal models and clinical trials have shown that inhibition of the renin-angiotensin system delays the progression of advanced DN. However, a recent large-scale clinical trial has revealed that inhibition of renin-angiotensin system in early phases of DN does not slow the decline of renal function or the development of morphological lesions, suggesting that different mechanism(s) may be involved in the different stages of DN. The role of epithelial-mesenchymal transition in renal fibrosis has been intensively investigated. Recently, endothelial-mesenchymal transition, or endothelial-myofibroblast transition (EndoMT) has emerged as another mechanism involved in both developmental and pathological processes. The essential role of EndoMT in cardiac development has been thoroughly studied. EndoMT also exists and contributes to the development and progression of cardiac fibrosis, lung fibrosis, liver fibrosis and corneal fibrosis. EndoMT is a specific form of epithelial-mesenchymal transition. During EndoMT, endothelial cells lose endothelial markers and obtain mesenchymal markers. Recent evidence from our laboratory and others suggests that EndoMT plays an important role in the development of renal fibrosis in several pathological settings, including experimental DN. This review considers the evidence supporting the occurrence of EndoMT in normal development and in pathology, as well as the latest findings suggesting EndoMT contributes to fibrosis in DN. Whether experimental findings of EndoMT will be reproduced in human studies remains to be determined. [source] Diuretics: A modern day treatment option? (Review Article)NEPHROLOGY, Issue 5 2006MARTIN GALLAGHER SUMMARY: The choice of drugs to initiate therapy for the management of hypertension remains contentious and diuretics are central to this controversy. Because most of the major trials involve complex treatment algorithms and allow diverse background treatments, one of the greatest challenges lies in separating out true class-specific effects , for example, separating true class-specific effects of diuretics from those of beta blockers. Despite these difficulties, the evidence confirms that diuretics are at least as effective as the newer first line groups in preventing cardiovascular events. The main area of doubt lies in relation to the risk of renal outcomes and of metabolic outcomes, such as new onset diabetes , where the evidence suggests that drugs that inhibit the renin-angiotensin system may be more protective than all other drug classes. These issues are reflected in the most recent international guidelines, all of which include diuretics among the first-line drugs for the treatment of hypertension, although they do differ on the role of diuretics in the initiation of therapy. Diuretics remain important for treating hypertension, especially in combination with other drug classes. The particular place of diuretics in the rank order of drugs must be tailored to suit the clinical situation in the individual patient. This will vary from a preferred option, as in black patients or elderly patients with systolic hypertension, to a second-line option in patients at high risk of developing new onset diabetes. [source] Angiotensin-converting enzyme polymorphism gene and evolution of nephropathy to end-stage renal diseaseNEPHROLOGY, Issue 4 2003M Angels ORTIZ SUMMARY: Genetic polymorphisms of the renin-angiotensin system (RAS) have been implicated in the pathogenesis of nephropathy and end-stage renal disease (ESRD). The association between angiotensin-converting enzyme (ACE) gene polymorphism and nephropathy evolution was studied. A random sample of 161 subjects from the Nephrology Department (of Hospital de Sant Pau) were divided into two groups: (i) 117 with end-stage renal disease; (ii) 44 with established nephropathy; and (iii) control groups of 129 subjects. The ACE gene polymorphism was performed by using polymerase chain reaction. High DD genotype presentation was observed in the two groups of subjects with nephropathy (46.12 and 61.37%, respectively vs 35.66% in controls; P < 0.0482), and also, a decrease was observed in the II genotype (6.4 and 4.54%, respectively vs 13.17% in controls, P < 0.0404). Glomerular filtration rate (GFR) was evaulated after 44 months of follow up. An important decrease of GFR was observed in patients with DD polymorphism versus other genotypes (initial, 32.3 ± 7.9 and at 44 months, 18.35 ± 3.3 mL/min vs 31.4 ± 11.9 and 11.7 ± 3.2 mL/min; P < 0.039). In a non-longitudinal study of patients in ESRD, patients with an ACE-DD genotype had a lower period of time between diagnosis of nephropathy and ESRD than patients with other genotypes (10.45 ± 9.32 vs 19.5 ± 8.4 years; P < 0.034). In conclusion, the ACE gene that controls RAS response may influence the development and progression of nephropathy to ESRD. Patients who develop several types of nephropathy have a higher risk of severe evolution if they have a profile of ACE-DD genotype. [source] Pathogenesis of diabetic retinopathy and the renin-angiotensin systemOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 6 2003Hideharu Funatsu Abstract Despite the beneficial effects of good glycaemic control, loss of vision because of diabetic retinopathy (DR) still occurs. Recent studies have suggested that hypertension is a risk factor for the development and progression of DR and that blood pressure reduction can delay the progression of retinopathy. The renin-angiotensin system is activated by chronic hyperglycaemia, and the vitreous fluid level of angiotensin II (AII) is elevated in patients with proliferative diabetic retinopathy and diabetic macular oedema. AII increases vascular permeability and promotes neovascularization. It has been suggested that an autocrine-paracrine relationship may exist between AII and vascular endothelial growth factor in the ocular tissues. Accordingly, angiotensin-converting enzyme inhibitors or AII Type 1 (AT1) receptor blockers may be useful therapeutic agents for preventing the progression of DR. [source] Latest news and product developmentsPRESCRIBER, Issue 14 2007Article first published online: 19 OCT 200 Studies suggest risk of bone loss with SSRIs Two cross-sectional studies have suggested the SSRI antidepressants may be associated with an increased risk of bone loss (Arch Intern Med 2007;167:1240,5 &1246,51). In 2722 older women (mean age 79) living in the community who were participating in the Study of Osteoporotic Fractures cohort study, use of SSRIs was associated with a significant increase in the rate of loss of hip bone density compared with nonusers(0.82 vs 0.47 per cent per year). The rate of loss among women taking a tricyclic antidepressant was also 0.47 per cent per year. Excluding women with more severe depression did not alter the findings. In 5995 men aged 65 or older taking an SSRI in another study, mean bone density was 3.9 per cent lower at the hip and 5.9 per cent lower in the lumbar spine compared with no use of antidepressants. Use of a tricyclic antidepressant or trazodone was not associated with increased bone loss. The authors comment that the degree of bone loss is comparable with that associated with corticosteroids. Serotonin transporters have been identified in osteoblasts and osteocytes. Risk of rare birth defects with SSRIs Two US case-control studies have found qualified evidence that use of SSRIs during the first trimester may be associated with a small increase in the risk of rare neonatal defects (N Engl J Med 2007;356:2675,83 & 2684,92). The Slone Epidemiology Center Birth Defects Study identified 9849 infants with birth defects and 5860 without and found no significant association between SSRI use overall and defects previously attributed to SSRIs (craniosynostosis, omphalocele or heart defects). There was some evidence that sertraline and paroxetine may cause specific defects, but this was based on few cases and the absolute risk remained low. The National Birth Defects Prevention Study identified 9622 infants with major birth defects and 4092 controls. There was no significant association with heart defects but the odds of anencephaly, craniosynostosis and omphalocele were each significantly increased by a factor of 2,3. The authors say the absolute risk remains small and their findings require confirmation. UK data do not support MI link with rosiglitazone An interim analysis of a UK clinical trial of rosiglitazone (Avandia) has found no evidence that it is associated with an increased risk of myocardial infarction (N Eng J Med 2007;357:28,38). A US meta-analysis (N Engl J Med 2007;356:2457,71) recently suggested that the odds of an MI or cardiovascular (CV) death in patients taking rosiglitazone were increased by 40,60 per cent compared with controls. The UK analysis of an ongoing nonblinded trial comparing rosiglitazone plus a sulphonylurea or metformin with sulphonylurea/metformin found no significant differences in the risk of MI or CV death. The risk of heart failure was doubled in patients taking rosiglitazone. The authors comment that, with a mean follow-up of 3.75 years, they had too few data to reach a conclusive finding. Switch piroxicam users to another NSAID The European Medicines Agency has advised prescribers to switch patients who are taking oral piroxicam to another NSAID. The advice follows a reappraisal of the safety of piroxicam when the 2006 review of all nonselective NSAIDs suggested it may be associated with increased risks of GI adverse effects and serious skin reactions. The advice does not apply to topical formulations. Piroxicam should not be prescribed for acute conditions and should not be first-choice for osteoarthritis, rheumatoid arthritis and ankylosing spondylitis. The maximum dose should be 20mg per day and treatment should be reviewed after 14 days. The MHRA states there is no need for urgent action; long-term treatment should be reviewed at the next routine appointment. OTC azithromycin? The MHRA is consulting on a request by a pharmaceutical company to reschedule azithromycin to pharmacy-only status for the treatment of known or suspected Chlamydia trachomatis infection in individuals aged 16 years or older. The applicant envisages supplies being made only when a nucleic acid amplification test (NAAT) is positive. Responses should be submitted to the MHRA (www.mhra.gov.uk) by 2 August. Computers can reduce prescribing errors Computerised prescribing reduces by two-thirds the rate of medication errors associated with handwritten prescriptions, a new review has found (Health Services Research 2007; online doi:10.1111/j.1475,6773. 2007.00751.x). There was some evidence that the risk of all errors, dose errors and adverse effects were reduced by computerisation. The greatest impact was seen in settings with very high error rates (>12 per cent) associated with handwritten prescriptions. However, the studies included produced heterogeneous results and the reduction in errors in prescribing for children was not statistically significant. Furthermore, computerisation did not reduce the rate of prescribing the wrong drug. Echinacea works for colds, new study finds The herbal remedy Echinacea does reduce the risk of catching a cold, according to a new metaanalysis (Lancet Infect Dis 2007;7:473,80). In 2006, a Cochrane review found insufficient evidence to support the benefits claimed for Echinacea. The new study, which additionally included experimentally-induced infections among the 14 trials analysed, found that Echinacea reduced the odds of catching a cold by about half and reduced the average duration of a cold by 1.4 days. Though inconclusive, the possibility of publication bias and heterogeneity between the trials could not be excluded. HRT may reduce cardiovascular risk after all A subgroup analysis of the Women's Health Initiative (WHI) suggests that HRT may reduce the risk of coronary heart disease if started soon after the menopause (N Engl J Med 2007;356:2591,602). The main analysis of WHI showed no cardiovascular benefit for HRT, a finding attributed to the relatively old mean age of participants (59). In the new analysis of 1064 women aged 50,59, HRT use was associated with a significant reduction in coronary artery calcification compared with nonuse, with greater effect associated with greater adherence. Reducing BP key to avoiding heart failure An angiotensin,II receptor blocker (ARB) is no better than other antihypertensives at avoiding the development of heart failure in individuals with hypertension, say US investigators (Lancet 2007;369:2079,87). Drugs that affect the renin-angiotensin system can reduce ventricular hypertrophy and may therefore prevent the development of heart failure in patients with hypertension. This study found similar improvements in diastolic function in 384 patients with hypertension and left ventricular dysfunction randomised to valsartan (Diovan) or placebo in addition to standard antihypertensive treatment for 38 weeks. The authors conclude that blood pressure reduction, not choice of drug, is the most important factor. Copyright © 2007 Wiley Interface Ltd [source] The Renin-Angiotensin System in the Bovine Utero-Placental UnitREPRODUCTION IN DOMESTIC ANIMALS, Issue 3-4 2000AH Nielsen Contents Renin, angiotensin converting enzyme, and angiotensin II receptors are expressed in the bovine utero-placental unit, indicating the presence of a local renin-angiotensin system (RAS). Angiotensin II receptors of type AT1 and AT2 as well as non-AT1/non-AT2 binding sites were identified. The expression of both renin and the angiotensin II receptor types in the bovine utero-placental unit differs from that in humans. This fact is probably related to differences in placental architecture. The RAS in the bovine utero-placental unit might be important for growth processes in the endometrium and for placentation. It might also participate in the regulation of the utero-placental blood flow and secretion of hormones. Disturbances in the utero-placental RAS might cause a reduced utero-placental blood flow, intrauterine growth retarda_tion and intrauterine death. [source] Inhibition of the formation or action of angiotensin II reverses attenuated K+ currents in type 1 and type 2 diabetesTHE JOURNAL OF PHYSIOLOGY, Issue 1 2001Yakhin Shimoni 1Transient and sustained calcium-independent outward K+ currents (It and ISS) as well as action potentials were recorded in cardiac ventricular myocytes isolated from two models of diabetes mellitus. 2Rats injected (i.v.) with streptozotocin (STZ, 100 mg kg,1) 6,10 days before cell isolation developed insulin-dependent (type 1) diabetes. It and ISS were attenuated and the action potential prolonged. Incubation of myocytes (6-9 h) with the angiotensin II (ATII) receptor blockers saralasin or valsartan (1 ,m) significantly augmented these currents. Inclusion of valsartan (1 g l,1) in the drinking water for 5,10 days prior to and following STZ injection partially prevented current attenuation. 3Incubation of myocytes from STZ-treated rats (6-9 h) with 1 ,m quinapril, an angiotensin-converting enzyme (ACE) inhibitor, significantly augmented It and ISS and shortened the ventricular action potential. It augmentation was not due to changes in steady-state inactivation or in recovery from inactivation. No acute effects of quinapril were observed. 4The effects of quinapril and valsartan were abolished by 2 ,m cycloheximide. 5Myocytes were isolated from the db/db mouse, a leptin receptor mutant that develops symptoms of non-insulin-dependent (type 2) diabetes. K+ currents in these cells were also attenuated, and the action potentials prolonged. Incubation of these cells (> 6 h) with valsartan (1 ,m) significantly enhanced the transient and sustained outward currents. 6These results confirm recent suggestions that cardiac myocytes contain a renin-angiotensin system, which is activated in diabetes. It is proposed that chronic release of ATII leads to changes in ionic currents and action potentials, which can be reversed by blocking the formation or action of ATII. This may underlie the proven benefits of ATII receptor blockade or ACE inhibition in diabetes, by providing protection against cardiac arrhythmias. [source] Association of a polymorphism at the 5,-region of the angiotensin II type 1 receptor with hypertensionANNALS OF HUMAN GENETICS, Issue 3 2000N. TAKAHASHI Molecular variants of individual components of the renin-angiotensin system are thought to contribute to inherited predisposition towards essential hypertension. Using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and sequence analysis, we identified seven polymorphisms in the 5,-flanking region of the angiotensin II type 1 receptor (AGTR1/AT1) gene. We conducted a case-control study in a sample from the Japanese population to determine whether polymorphic markers in the 5,-flanking region of the AT1gene were associated with essential hypertension. The study compared 149 hypertensive subjects to 156 normotensive control subjects. A significantly higher frequency of the AT1(,535)*T allele was observed in hypertensive subjects. Evidence was obtained that the AT1(,535)*T allele showed a synergistic effect on risk of hypertension with angiotensin I converting enzyme D allele (ACE*D). [source] Angiotensin I-converting enzyme and potential substrates in human testis and testicular tumoursAPMIS, Issue 1 2003Review article The angiotensin I-converting enzyme (ACE, kininase II, CD143) shows a broad specificity for various oligopeptides. Besides the well-known conversion of angiotensin I to II, ACE degrades efficiently kinins and the tetrapeptide AcSDKP (goralatide) and thus equally participates in the renin-angiotensin system, the kallikrein-kinin system, and the regulation of stem cell proliferation. In the mammalian testis, ACE occurs in two isoforms. The testicular isoform (tACE) is exclusively expressed during spermatogenesis and is generally thought to represent the germ cell-specific isozyme. However, we have previously demonstrated that, in addition to tACE, the somatic isoform (sACE) is also present in human germ cells. Similar to other oncofoetal markers, sACE exhibits a transient expression during foetal germ cell development and appears to be a constant feature of intratubular germ cell neoplasm, the so-called carcinoma-in-situ (CIS) and, in particular, of classic seminoma. This demands the existence of specific paracrine functions during male germ cell differentiation and development of male germ cell tumours, which are mediated by either of the two ACE isoforms. Considering the complexity of current data about ACE, a logical connection is required between () the precise localisation of ACE isoforms, (I) the local access to potential substrates and (II) functional data obtained by knockout mice models. The present article summarises the current knowledge about ACE and its potential substrates with special emphasis on the differentiation-restricted ACE expression during human spermatogenesis and prespermatogenesis, the latter being closely linked to the pathogenesis of human germ cell tumours. [source] CARDIOVASCULAR AND METABOLIC EFFECTS OF OBESITYCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 4 2008Margaret J Morris SUMMARY 1Obesity is an important risk factor for hypertension and its incidence is increasing around the world. 2The mechanisms underlying obesity-related hypertension include sympathetic activation, altered vascular responses, hormonal changes, enhanced inflammatory markers and structural changes. 3This review summarizes recent evidence of the underlying impact of obesity on blood pressure. A number of candidate mechanisms include increased sympathetic activity, activation of the renin-angiotensin system, altered vasoconstrictor or dilator responses and the attendant systemic inflammatory state. 4While adult lifestyle factors undoubtedly contribute to the incidence of obesity and its attendant hypertension, evidence suggests that the programming of obesity may occur following over-nutrition during development. A growing body of evidence links maternal obesity, offspring obesity and hypertension. 5Finally, epigenetic modification of genes relevant to hypertension may contribute to the development of hypertension following a suboptimal intrauterine environment. To date the cardiovascular effects of early nutritional changes have been largely investigated following maternal under-nutrition or protein restriction; further work is necessary to determine the impact of maternal obesity. [source] Metabolic Syndrome and Cardiovascular Disease: Challenges and OpportunitiesCLINICAL CARDIOLOGY, Issue 12 2007Pharm D, Rhonda M. Cooper-DeHoff Abstract Metabolic syndrome (MetS) has been defined in different ways. However, key components common to most definitions are a constellation of risk factors including abdominal adiposity, impaired fasting glucose, hypertension, and dyslipidemia. A major mediator of MetS appears to be insulin resistance, which relates to the development of the vascular and metabolic dysfunctions that precede overt cardiovascular disease and type 2 diabetes. Evidence suggests that the mechanisms underlying the elevated cardiovascular risk associated with MetS begin with subclinical organ damage. Therapy for MetS targets individual components of the syndrome and includes lifestyle interventions, lipid-modifying therapy, and antihypertensive agents, particularly those that inhibit the renin-angiotensin system. Results of trials of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers have demonstrated reductions in new-onset diabetes and cardiovascular events in a wide range of patients. Clinical trials to investigate further the role of these drugs in the primary prevention of type 2 diabetes in patients with MetS are currently under way. The purpose of this paper is to review the MetS from the perspective of the cardiology workforce with the hope that a better understanding of the links between MetS and cardiovascular disease could lead to improved management of persons at risk. Copyright © 2007 Wiley Periodicals, Inc. [source] Gene,environment interactions and the response to exerciseINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 5 2000Hugh Montgomery Many of the symptoms of heart failure (breathlessness and fatigue) are not primarily due to reduced cardiac output, but relate to an impairment of peripheral muscle performance and metabolic efficiency. With regular training it is possible to increase skeletal muscle performance through improvements in muscle efficiency. Recent data suggest that such improvements may be modulated by local tissue renin-angiotensin systems and, in particular, by the local activity of angiotensin-converting enzyme (ACE). These findings might explain the remarkable benefits of ACE inhibition in the treatment of heart failure. [source] | |||||||||||||||||||||||||||||||