Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hypertension is the most prevalent, treatable risk factor for diseases of the heart, brain and kidneys. In this review, we discuss advances in understanding of the genetics of blood pressure regulation, the development of hypertensive complications and the pharmacodynamics of antihypertensive drug responses. Discovery of single gene mutations that cause hypertension or hypotension in humans suggests that the common final pathway for regulation of blood pressure level is via alterations in renal sodium handling. Based on a working hypothesis that common genetic variations contributing to blood pressure variation in the population may also act on this same pathway, we summarize supporting evidence emerging from linkage and selected association studies of candidate genes--including those encoding components of the renin-angiotensin-aldosterone system, the epithelial sodium channel, adrenoceptors, G protein subunits, and other cellular signaling mediators and modifiers. We proceed to distinguish ischemic target organ complications due to arteriolosclerotic changes of the microvasculature from those due to atherosclerosis involving larger conduit and capacitance arteries. Using the example of subcortical white matter ischemia of the brain, we propose that interindividual variation in the arteriolosclerotic complications is more likely than atherosclerotic complications to be related to the same genetic (and environmental) mechanisms that contribute to hypertension. We conclude by summarizing the state-of-the-art of antihypertensive pharmacogenetics, which has succeeded in rejecting the null hypothesis that genetic variation does not influence blood pressure or protective target organ responses to drug therapy. In each of the three areas covered in this review, we indicate the many remaining obstacles to the routine clinical use of genetic measurements in the diagnosis, evaluation and treatment of hypertension.
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PMID:Genetics of blood pressure, hypertensive complications, and antihypertensive drug responses. 1251 86

Adrenomedullin (AM) has multi-functional properties, of which the vasodilatory hypotensive effect is the most characteristic. AM and its gene are ubiquitous in a variety of tissues and organs, in the cardiovascular system, as well as the adrenal medulla. AM secretion, especially in cardiovascular tissues, is regulated mainly by mechanical stressors such as shear stress, inflammatory cytokines such as interleukin (IL)-1, tumor necrosis factor (TNF), and lipopolysaccharide (LPS), hormones such as angiotensin (Ang) II and endothelin (ET)-1, and metabolic factors such as hypoxia, ischemia, or hyperglycemia. Elevation of plasma AM due to overproduction in response to one or more of these stimuli in pathological conditions may explain the raised plasma AM levels present in cardiovascular and renal diseases such as congestive heart failure, myocardial infarction, hypertension, chronic renal failure, stroke, diabetes mellitus, and septic shock. In addition to shear stress, stretching of cardiomyocytes may be another mechanical stimulus for AM synthesis and secretion. Our recent studies have shown the importance of aldosterone and additional hormonal factor on AM secretion in vascular wall.
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PMID:Regulation of production and secretion of adrenomedullin in the cardiovascular system. 1266 26

The nonpeptide AT(1) receptor antagonist candesartan is generated from the prodrug candesartan cilexetil during gastrointestinal absorption. In vitro studies have shown that candesartan acts as an insurmountable, tightly bound antagonist at the AT(1) receptor, producing a dose-dependent reduction in the maximal responses to angiotensin II (AII) and virtually an elimination of the AT(1) receptor-mediated effects of AII at high concentrations. The binding of candesartan to the AT(1) receptor is highly selective, and the drug dissociates slowly from the receptor. Candesartan cilexetil produces the expected changes in the parameters of the renin-angiotensin system. Plasma renin activity and plasma AII concentrations were increased and aldosterone levels decreased following drug application. As a consequence, stimulation of AT(2) receptor-mediated actions of AII, such as growth inhibition and vasodilation, may contribute to the overall effects of the AT(1) antagonist, since the AT(2) receptors are left unopposed by candesartan. The antihypertensive efficacy of candesartan cilexetil has been demonstrated in different animal models of hypertension including 2 kidney-1 clip and 1 kidney-1 clip hypertensive rats and spontaneously hypertensive rats (SHR). Candesartan cilexetil produced a slow onset, long-lasting antihypertensive action at a dose range of 0.1-10 mg/kg with no rebound effect upon drug withdrawal. A growing number of studies indicate that candesartan cilexetil can produce end organ protection in addition to lowering blood pressure. In preclinical studies, candesartan cilexetil caused prevention and regression of left ventricular hypertrophy and cardiac fibrosis, protected the heart against ischemia-reperfusion injury and reduced myocardial damage during myocarditis. In different animal models of renal dysfunction, candesartan cilexetil reduced proteinuria and albuminuria, inhibited histopathological renal changes and controlled the renal expression of TGF-beta1 and collagen types I and III. Finally, in stroke prone SHR, candesartan cilexetil markedly attenuated the incidence of stroke even at low doses, with minimal blood pressure lowering effects, and fully protected against stroke at higher doses.
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PMID:Candesartan cilexetil: development and preclinical studies. 1297 13

This study was designed to demonstrate potential beneficial as well as detrimental effects of lisinopril and spironolactone given in combination. In patients with congestive heart failure or myocardial infarction, the use of angiotensin-converting enzyme (ACE) inhibitors may inhibit aldosterone production. Spironolactone, a specific aldosterone receptor antagonist may exert other independent and additive effects to those of ACE inhibitors. Given the consequences of aldosterone on ischemic hearts, we evaluated the protective effects of spironolactone or lisinopril and combined spironolactone-lisinopril therapy during low-flow ischemia and reperfusion in isolated rat hearts. Normal and infarcted (left coronary artery ligature) male Wistar rats were submitted to chronic action of drugs (0.8 mg.kg-1.day-1 for lisinopril and 8 or 50 mg.kg-1.day-1 for spironolactone) for 1 month. Hearts were rapidly excised and perfused (constant pressure) for a 40-min period of stabilization followed by a 25-min period of global low-flow ischemia and a 30-min reperfusion. In normal rats, spironolactone decreased ischemic and reperfusion contracture, reduced ventricular tachycardia, suppressed action-potential duration dispersion, and increased reactive hyperemia leading to an improvement of contractile recovery. Lisinopril also decreased ventricular tachycardia and action-potential duration dispersion concomitantly with increased reactive hyperemia and better contractile recovery. These beneficial effects of the drugs were lost when the two treatments were combined (lisinopril and 50 mg.kg-1.day-1 spironolactone), despite a synergistic effect on plasmatic K+ and Mg2+. However, an interaction between the ACE inhibitor and spironolactone potentiating the effects of either drug alone was observed with a lower dose of spironolactone (lisinopril and 8 mg.kg-1.day-1 spironolactone). Similar beneficial effects have been noted in infarcted rat hearts on reactive hyperemia, ventricular tachycardia, and contractile recovery with the combined treatment and for both spironolactone concentrations (8 or 50 mg). Chronic spironolactone treatment produces similar beneficial effects to ACE inhibitor treatment on normal rat hearts during an ischemia-reperfusion protocol. Synergistic effects have been observed with the combined therapy when a lower dose of spironolactone was utilized in normal and infarcted rats. However, in the case of a high dose of spironolactone, the two effective drugs seem to cancel each other but only in normal rats.
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PMID:Potential beneficial as well as detrimental effects of chronic treatment with lisinopril and (or) spironolactone on isolated hearts following low-flow ischemia in normal and infarcted rats. 1461 22

Sudden cardiac death is mainly caused by arrhythmic events, triggered by ischemia. About half of the affected persons had no previous diagnosis of coronary heart disease, thus rendering them practically unreachable for specific preventive measures. This fact makes it necessary to optimize reanimation conditions. The establishment of international reanimation standards (ILCOR) has stimulated an intensified scientific evaluation of therapeutic options. While the use of vasopressin, adrenaline and reanimation by bystanders is being evaluated at the moment, amiodarone has not fulfilled the expectation of reducing mortality. Secondary prevention of sudden cardiac death after cardiac events is based on betablockers, ACE inhibitors and antilipemic therapy. Guidelines on prevention of sudden cardiac death also recommend aldosterone blockade and n-3-fatty acids. Persons at highest risk gain most from the use of ICDs, yet it has not been shown that their use immediately after myocardial infarction reduces mortality.
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PMID:[Sudden cardiac death (SCD) and guidelines for SCD]. 1502 98

For a long time chronic heart failure was seen as a purely myocardial problem, which is characterized by symptoms in consequence of an impaired contractility. Later on it became apparent that chronic heart failure is at least in part characterized by activation of the neuroendocrine system, in particular the sympathetic nervous system and the renin-angiotensin-aldosterone system. This neuroendocrine system is an important system that is not only responsible for symptoms but probably very important for the development and progression of heart failure and therefore relevant to the prognosis of these patients. Apart from this neuroendocrine activation heart failure is characterized by an inflammatory component. The mechanisms of inflammation seem to play an important role in the process of left ventricular remodeling including structural and functional changes of the myocardium which are not only in part responsible for the development of symptoms but also for the progression of disease. It turns out that pathophysiological consequences of activated inflammation are deleterious in the long term, but may provide transient protective effects in the acute stage of ischemia. Regarding clinical trials it can be assumed that general inhibition of the inflammation process by inhibition of tumor necrosis factor-(TNF-)alpha does not necessarily exert favorable effects.
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PMID:[Mechanisms of inflammation in heart failure]. 1559 75

Acute myocardial infarction (AMI) is a highly dynamic event, which is associated with marked neuroendocrinological dysfunction in addition to cardiac damage. The immediate trigger for AMI is not precisely known. Studies conducted by Lown, Braunwald, Halberg, Otsuka and our group have demonstrated a marked increase in sympathetic activity, oxidative stress, and magnesium and potassium deficiency during AMI. Clinical studies have reported an increased incidence of AMI, sudden death and ischemia during first quarter of the day when there is a rapid withdrawal of vagal activity and increase in sympathetic tone. In one case-control study of 202 patients with AMI, there was a significant (P < 0.02) increase in cardiac events in the second quarter of the day compared to other quarters, respectively (16.8%, 41.0%, 13.8%, 28.2% per quarter). This characteristic remained prevalent in both men and women and among patients with and without known AMI (n = 52), diabetes (n = 53) or hypertension (n = 75). Triggers of AMI were noted among 162 (82.2%) of the patients. Neuropsychological mechanisms were observed as follows: emotional stress (45.5%), sleep deprivation (27.7%), cold climate (29.2%), hot climate (24.7%), large meals (47.5%) and physical exertion (31.2%). These triggering factors are known to enhance sympathetic activity and decrease vagal tone, resulting in an increased secretion of plasma cortisol, noradrenaline, aldosterone, angiotension-converting enzyme (ACE), interleukin (IL)-1, -2, -6, -18, and tumor necrosis factor-alpha (TNF-alpha), all of which are are proinflammatory agents. There is also a deficiency in the serum levels of vitamin A, E, and C and magnesium, potassium, melatonin, and IL-10 (an anti-inflammatory agent). In our study, we found a decrease in magnesium, potassium, vitamin A, E, C and beta carotene combined with an increase in thiobarbituric acid-reactive substances (TBARS), MDA and diene conjugates, TNF-alpha and IL-6, all of which are indicators of oxidative damage and proinflammatory activity, respectively.
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PMID:Mechanisms of acute myocardial infarction study (MAMIS). 1575 48

Imidapril is an angiotensin I converting enzyme inhibitor, a class of drugs with known cardioprotective activity. It is now known that this is due not only to their antihypertensive activity, but also to the fact that they decrease cellular and tissue levels of angiotensin II, a potent vasoconstrictor and inducer of myocardial fibrosis. These mechanisms may explain the good clinical results of this class of drugs in the treatment of coronary artery disease and heart failure, two diseases whose etiopathogenesis is closely related to the activation of the renin-angiotensin-aldosterone system. However, the impact of this class of drugs on cardiac mitochondrial function during acute myocardial ischemia is still largely unknown. With the aim of studying the effect of imidapril on cardiac mitochondrial function during acute ischemia, we used an ex-vivo animal model, perfused in a Langerdorff system and then subjected to ischemia in the presence or absence of imidapril. We evaluated mitochondrial membrane electrical potential, respiratory chain O2 consumption, and rate and amplitude of mitochondrial swelling. We conclude that imidapril did not significantly change oxygen consumption by cardiac mitochondria, as assessed by the rate of respiratory state 3 (the state that corresponds to the active phosphorylation phase). However, imidapril significantly increased transmembrane electrical potential and, in ischemic cardiac mitochondria, was able to prevent the calcium-induced increase in the rate and amplitude of mitochondrial swelling, thus enabling better preservation of mitochondrial membrane structure, with consequent improvement of electrical potential after the phosphorylation cycle. These findings enabled a better understanding of the mechanisms behind the cytoprotection provided by imidapril during ischemic cardiomyopathy, clearly highlighting, at a cellular biology level, the importance of pharmacological modulation of cardiac mitochondrial function during acute ischemia.
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PMID:Impact of imidapril on cardiac mitochondrial function in an ex-vivo animal model of global myocardial ischemia. 1577 66

Growth hormone (GH)-releasing peptides (GHRP), a class of synthetic peptidyl GH secretagogues, have been reported to exert a cardioprotective effect on cardiac ischemia. However, whether GHRP have a beneficial effect on chronic heart failure (CHF) is unclear, and the present work aims to clarify this issue. At 9 wk after pressure-overload CHF was created by abdominal aortic banding in rats, one of four variants of GHRP (GHRP-1, -2, and -6 and hexarelin, 100 mug/kg) or saline was injected subcutaneously twice a day for 3 wk. Echocardiography and cardiac catheterization were performed to monitor cardiac function and obtain blood samples for hormone assay. GHRP treatment significantly improved left ventricular (LV) function and remodeling in CHF rats, as indicated by increased LV ejection fraction, LV end-systolic pressure, and diastolic posterior wall thickness and decreased LV end-diastolic pressure and LV end-diastolic dimension. GHRP also significantly alleviated development of cardiac cachexia, as shown by increases in body weight and tibial length in CHF rats. Plasma CA, renin, ANG II, aldosterone, endothelin-1, and atrial natriuretic peptide were significantly elevated in CHF rats but were significantly decreased in GHRP-treated CHF rats. GHRP suppressed cardiomyocyte apoptosis and increased cardiac GH secretagogue receptor mRNA expression in CHF rats. GHRP also decreased myocardial creatine kinase release in hypophysectomized rats subjected to acute myocardial ischemia. We conclude that chronic administration of GHRP alleviates LV dysfunction, pathological remodeling, and cardiac cachexia in CHF rats, at least in part by suppressing stress-induced neurohormonal activations and cardiomyocyte apoptosis.
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PMID:GH-releasing peptides improve cardiac dysfunction and cachexia and suppress stress-related hormones and cardiomyocyte apoptosis in rats with heart failure. 1595 41

Necrotizing enterocolitis (NEC) is a common, life-threatening neonatal gastrointestinal disease; it affects approximately 11% of extremely premature neonates. The etiology of NEC is multifactorial. Risk factors may roughly be grouped into four main categories: prematurity; transient ischemia of the intestine; local/systemic inflammation predisposing the bowel to injury, and therapeutic interventions. Recent studies have shown that carrier state of genetic polymorphisms may be associated with perinatal morbidity, including NEC. In perinatal disorders, the significance of genetic variants of cytokines, the renin-angiotensin-aldosterone system, and surfactant proteins have been investigated most widely. Positive findings indicate the implication of genetic polymorphisms of proinflammatory cytokines in premature birth; angiotensin converting enzyme in perinatal adaptation and angiotensin type 1 receptor in the closure of ductus arteriosus; surfactant proteins A and B in respiratory distress syndrome; interleukin (IL)-6 in sepsis, and IL-4-receptor alpha chain and IL-18 in NEC. This review provides an insight into the genetics of NEC and summarizes genetic data in light of pathologic processes leading to NEC.
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PMID:Genetic basis for necrotizing enterocolitis--risk factors and their relations to genetic polymorphisms. 1614 53


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