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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Insulin resistance and hyperinsulinemia have been observed in over 70% of the nonobese, nondiabetic subjects with essential hypertension (HT). Alpha-1 blockers, ACE-antagonists, long-acting Ca blockers including nifedipine CR, some form of beta-blockers, tilisolor, which is reported to increase blood flow, improve insulin sensitivity when blood pressure is better controlled. Decrease of serum potassium during insulin sensitivity test and intraplatelet free Ca2+ concentration is positively and negatively correlated with insulin sensitivity, respectively. Blood pressure is correlated with insulin resistance, which is also observed in secondary HT. The resistance is correlated with salt sensitivity as well as impaired nocturnal fall of blood pressure. These suggest the possible association of insulin resistance with altered intracellular cation metabolism. Insulin resistance and associated hyperinsulinemia have been observed in effort as well as vasospastic angina pectoris (VSAP), atherothrombotic cerebral infarction, and in ASO without obesity, HT, or diabetes, suggesting the resistance resulting from endothelial dysfunction. Insulin resistance has been observed in heart failure and is correlated with angiotensin II. Resistance is also observed in hypertrophic cardiomyopathy and is partially correlated with TNF-alpha. These results indicate that insulin resistance seem to be multifactorial. An effort to normalize insulin sensitivity is crucial to eliminate multiple risk factors as well as to prevent the progression of atherosclerotic vascular lesions.
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PMID:Multifactorial insulin resistance and clinical impact in hypertension and cardiovascular diseases. 1187 61

Oxidative stress in blood vessels and the kidney in hypertension can be induced by diverse vasoconstrictor mechanisms, including blockade of nitric oxide synthase and activation of angiotensin II type I receptors and thromboxane receptors. It can cause vasoconstriction via bioinactivation of nitric oxide, and by nitric oxide synthase independent mechanisms that include increased generation of endothelin-1 and the effects of superoxide anion and hydrogen peroxide on vascular smooth muscle cells. Oxidative stress can accompany hypertension in many models including the spontaneously hypertensive rat, the angiotensin II-infused rat, renovascular hypertension, the deoxycorticosterone acetate-salt model, and obesity-related hypertension. In the kidney, NADPH oxidase-generating superoxide anion is expressed in the vasculature, interstitium, juxtaglomerular apparatus, and the distal nephron. Much progress has been made in defining the pathways that intervene between agonist stimulation of blood vessels and reactive oxygen species-mediated contractile and renal functional responses in animal models in hypertension.
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PMID:Reactive oxygen species: roles in blood pressure and kidney function. 1188 72

Obesity, which has reached epidemic proportions in the United States and other western countries, may be complicated by hypertension, an increased incidence of renal cancer or proteinuria. Patients with obesity-associated proteinuria show focal glomerulosclerosis and glomerulomegaly on biopsy, usually have minimal clinical edema and relatively normal levels of serum albumin, cholesterol and blood pressure, and can progress to end-stage renal disease. Severe obesity may also be an additive risk factor in patients with preexisting nephropathy or reduced renal mass. The pathophysiology of obesity-associated proteinuria is unclear but may include hyperfiltration, increased renal venous pressure, glomerular hypertrophy, hyperlipidemia and increased synthesis of vasoactive and fibrogenic substances, including angiotensin II, insulin, leptin and transforming growth factor-beta1. These substances may individually or interactively affect glomerular hyperfiltration, mesangial cell hypertrophy and matrix production, and the production of collagen, fibronectin, transforming growth factor-beta and other fibrogenic mediators of change. Although angiotensin-converting enzyme inhibition has proven to have an impact, perhaps temporarily, on obesity-associated proteinuria in humans, weight reduction early in the course of the disease would appear the most important therapeutic approach.
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PMID:Obesity and renal disease. 1198 Dec 64

The renin-angiotensin-aldosterone system (RAAS) plays a well-recognized role in the regulation of BP and in salt and water balance. Since hypertension affects a considerable proportion of obese patients, circulating RAAS has been studied in obese subjects with and without hypertension, albeit with conflicting results. Furthermore, attention has recently focused on the expression of the components of the Renin-angiotensin system (RAS) in some organs, including adipose tissue where it seems to be involved in the regulation of growth and differentiation. The aim of our study was to investigate circulating RAAS and adipose tissue RAS in obese patients with and without hypertension and in matched controls. PRA, and plasma and urinary aldosterone levels were measured in 35 obese, 30 hypertensive obese patients and in 20 controls. In addition, the expression of angiotensinogen (AGT) and angiotensin II type 1 receptor (AT1) genes was studied in sc adipose tissue from 8 obese, 6 hypertensive obese and 6 healthy subjects. As previously demonstrated in other studies, there were no significant differences in the levels of circulating RAAS components in the 3 groups. As regards local RAS, interestingly, we found that AT1 gene was significantly more expressed in sc adipose tissue from obese patients with hypertension than in those without hypertension and controls. By contrast, AGT levels were similar in the 3 groups. Our data do not support the hypothesis of an involvement of circulating RAAS in the development of obesity-related hypertension. On the other hand, local RAS seems to be differently regulated in sc adipose tissue from obese patients with hypertension with respect to normotensive obese patients and controls.
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PMID:Comparison of circulating and local adipose tissue renin-angiotensin system in normotensive and hypertensive obese subjects. 1203 Jun

Despite years of investigation our fundamental and clinical knowledge of the major public health problem, obesity-hypertension, is relatively meager and certainly inadequate. We are at a loss to explain why the pathophysiological mechanisms of obesity and hypertension are so inextricably intertwined. Adding to this frustration is the inadequacy of the treatment for obesity. Hemodynamically, we recognize that the expanded plasma volume caused by obesity imparts a significant volume overload on the heart, thereby increasing cardiac output, while the hypertension compounds this ventricular stress by an associated pressure overload. Thus, the ventricle has an eccentric as well as a concentric adaptive hypertrophy. Associated with obesity is an increased burden of pressor (e.g., catecholamine, angiotensin II); peptide (e.g., endothelin, insulin, leptin, natriuretic); hormonal (e.g., growth, steroids, thyroid); and neural mechanisms. Further complicating these alterations are electrolytic, lipid, uric acid, and other metabolic factors. Both diseases (obesity and hypertension) are exacerbated by frequently encountered comorbid pathophysiological disorders including atherosclerosis, ventricular dysfunction, diabetes mellitus, hyperlipidemias, and sleep apnea. To add to these issues, therapy for obesity-hypertension is suboptimal. Behavioral modification (of overweight and obesity) is commonly characterized by recidivism, and pharmacotherapy of obesity is woefully inadequate; the present agents either raise arterial pressure or are fraught with adverse effects. Fortunately, there are no contraindications imparted by obesity that complicate the drug treatment of the associated hypertension. Each of the lifestyle modifications and seven classes of antihypertensive therapy that is discussed herein is done in light of the coexistent hypertension and comorbid diseases.
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PMID:Clinical management of the obese hypertensive patient. 1204 91

Expanded adipose tissue mass increases the risk for many clinical conditions including diabetes, hypertension, coronary atherosclerotic heart disease, and some forms of cancer. Therefore, it is imperative that we understand the mechanisms by which fat pads expand. The enlargement of fat cells during the development of obesity has been previously hypothesized to be a triggering factor for the proliferation of new fat cells. There is now a preponderance of evidence that adipose tissue is a source of growth factors such as IGF-I, IGF binding proteins, TNF alpha, angiotensin II, and MCSF that are capable of stimulating proliferation. The relative importance of these autocrine/paracrine factors in the normal control of preadipocyte proliferation is unknown. In addition, the proliferative response of preadipocytes to the paracrine milieu is undoubtedly modulated by neural inputs to fat tissue and/or serum factors. Together, these multiple regulatory controls orchestrate overall and region-specific adipose tissue cellularity responses associated with the development of hyperplastic obesity. Both in vivo and in vitro studies are needed to understand the complex, interacting physiological mechanisms by which growth of this important organ is regulated.
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PMID:The biology of white adipocyte proliferation. 1211 95

Large-scale trials with angiotensin converting enzyme (ACE) inhibitors and angiotensin II type 1 (AT(1))-receptor blockers have clearly shown that blockade of the renin-angiotensin system reduces the deterioration in renal function associated with diabetes. AT(1)-receptor blockers represent a more rational approach to blockade of this system than ACE inhibitors, due to the presence of non-ACE pathways of angiotensin II formation. Studies in healthy volunteers maintained on a low-salt diet indicate that such pathways account for approximately 30-40% of total angiotensin II formation, and this figure increases to 60-70% in individuals maintained on a high-salt diet (resembling the situation in most human populations). Activation of the renin-angiotensin system is increased in diabetic patients, and comparison of the renal vascular responses to captopril and candesartan shows a strong correlation between the effects of ACE inhibition and AT(1)-receptor blockade, indicating that the deleterious effects of renin-angiotensin system activation in diabetes are mediated largely through angiotensin II. The presence of multiple risk factors, such as genetic predisposition, hyperglycaemia, obesity and tissue damage, places diabetic patients at high risk of disease related to activation of the renin-angiotensin system. Effective and early blockade of this system is therefore an important aspect of management.
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PMID:AT(1)-receptor blockade and the kidney: importance of non-ACE pathways in health and disease. 1214 Jul 30

The exact mechanisms by which NO mediates its neuromodulatory effects within the central control of cardiovascular functions are still unclear. Both excitatory and inhibitory actions of NO in different regions of the brainstem have been reported, and that it could be caused by direct actions of NO on neurones and/or by NO-mediated changes in local cerebral blood flow. Microinjection studies suggest that direct modulation of neuronal activity by NO through cyclic 3'-5' guanosine monophosphate (cGMP)-dependent mechanisms predominates. In contrast, endogenous NO produces. only minor changes in local cerebral blood flow, and potentiation of NO-dependent vasodilation with an inhibitor of phosphodiesterase V (PDE5i) has no significant effect on sympathetic activity. Activation of the NO-system in the lower brain stem modulates various central and reflex-activated neuronal pathways. To a large extent, this appears to be mediated by NO-induced GABA- and glutamate-release within the ventrolateral medulla (VLM) and the nucleus of the solitary tract (NTS). In addition, NO has been shown to reduce local generation of angiotensin II (AII) in all areas. Recent studies suggest that the NO-mediated modulation of autonomic function is severely impaired in cardiovascular diseases. Possibly in conjunction with AII, which triggers and promotes superoxide radical generation, chronic oxidative stress (COS) could act as a key mediator of this process. Evidence supporting this hypothesis comes from studies on pigs that were chronically treated with organic nitrates to pharmacologically induce COS. In these animals, microinjection of superoxide dismutase into the rostral VLM (RVLM) diminished sympathetic activity by up to 70%, whereas peroxynitrite, a key mediator of NO-related oxidative stress, had excitotoxic effects. Antagonism of neuronal COS may therefore represent a novel approach to counteract neurohumoral activation in diseases such hypertension, obesity and heart failure.
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PMID:Mechanisms of action of nitric oxide in the brain stem: role of oxidative stress. 1214 34

Pathogenesis of the atherosclerotic process is deemed as multifactorial. To the most important risk factors, besides certain family predisposition, there belongs hypercholesterolemia, arterial hypertension, obesity, diabetes mellitus, smoking and others. In the last years there are more and more data about the role of inflammation and infection in the whole development of atherosclerosis. The witness for this hypothesis is the findings of high parameters of inflammation in involved vessels as well as in the blood of atherosclerosis suffering persons. Opinions about the inflammation theory appear from the 90th. Local sterile inflammation in the subendotelium of the middle and big arteries has been proved to consist of specific immune reaction (activation of the T-lymphocytes) as well as nonspecific characteristic by elevated monocytes in the artery wall during the whole process of atherogenesis. Inflammation in the plaque can trigger and hold several factors engaged in the atherosclerotic process, such as oxidized LDL cholesterol, elevated production of various superoxides, activated macrophages, activated T-lymphocytes, cytokines (IL-1, IL-6, interferon gamma) and lipoprotein Lp (a). In this inflammation process levels of CRP (acute phase protein), fibrinogen and erythrocyte sedimentation are elevated as a reaction of the organism to nonspecific chronic infections. Because of this it is thought that elevated fibrinogen and erythrocyte sedimentation are markers of the cardiovascular risk. Some papers deal with antiinflammatory effects of statins, because these lower CRP levels so they also lower atherosclerotic risk through not only lowering of cholesterol levels. Also asprine, as an antiinflammation agent, changing the CRP levels, would be of benefit for patients with vascular disease because its antiaggregation and antiinflammatory effects. ACE inhibitors are also antiinflamatory through blocking of tissue production of angiotensin II (artery wall and atherosclerotic plaque). Enzymatic inhibitors changing angiotensin can also have a partial antiinflammatory effect. The infection theory is supported also by tracing of some microorganisms in the atherosclerotic plaque or in the blood, as e.g. Helicobacter pylori or Chlamydia pneumoniae; to the autoimmune origin is indicated the presence of the specific immunity reaction against heat shock proteins (HSP) or oxidized LDL. This infection theory offers new therapy possibilities. Therefore eradication for example by antibiotics can lead to stabilization of the atherosclerotic plaque with positive consequences, as it was discovered by many studies.
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PMID:[The role of infection and inflammation in the pathogenesis of atherosclerosis]. 1219 10

Obesity is the prime risk factor for the development of type 2 diabetes. Recent clinical trials have shown that blockade of the renin-angiotensin system, either by inhibiting the angiotensin-converting enzyme or blocking the angiotensin type 1 receptor, may substantially lower the risk for type 2 diabetes. The mechanism underlying this effect is unknown. Based on our recent observation that angiotensin II markedly inhibits adipogenic differentiation of human adipocytes via the angiotensin type I receptor and that expression of angiotensin II-forming enzymes in adipose tissue is inversely correlated with insulin sensitivity, we propose the hypothesis that blockade of the renin-angiotensin system prevents diabetes by promoting the recruitment and differentiation of adipocytes. Increased formation of adipocytes would counteract the ectopic deposition of lipids in other tissues (muscle, liver, pancreas), thereby improving insulin sensitivity and preventing the development of type 2 diabetes.
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PMID:Angiotensin blockade prevents type 2 diabetes by formation of fat cells. 1241 51


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