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

Clinical and experimental data obtained in the last few years have modified the concept of adipose tissue as one solely directed at energy storage and release. The adipose tissue is a target organ for glucocorticoids and several studies have been carried out on the function of hypothalamic-pituitary-adrenal axis in obese subjects without conclusive results. A recent and innovative finding is that adipose tissue can produce cortisol from its inactive precursor, cortisone. The identification of leptin, a hormone synthesised by fat tissue, has ushered in the modern view of this tissue as a true endocrine organ. Leptin is produced primarily by subcutaneous and to a lesser extent by visceral adipose tissue, and has a central role in controlling body weight and, especially in regulating fat stores. Leptin is also involved in several complex functions, including physiological processes associated with puberty. Another hormone of fat tissue is angiotensinogen, which is produced in larger amounts by visceral than subcutaneous fat. Human and animals adipose tissue express a whole renin-angiotensin system (RAS). Angiotensin II, the final effector of this system is probably produced locally by adipose tissue. The function of adipose RAS is not well known. RAS can participate together with other hormones and substances, in adipocyte differentiation and fat tissue growth, but could be also involved in the pathogenesis of complications of obesity including arterial hypertension.
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PMID:Adipose tissue as an endocrine organ? A review of recent data related to cardiovascular complications of endocrine dysfunctions. 1519 92

Upper body obesity is associated with insulin resistance, hypertension, and endothelial dysfunction. We examined forearm vascular function in response to vasodilator (endothelium-dependent and endothelium-independent) and vasoconstrictor stimuli in 8 normotensive, upper body/viscerally obese men with a positive family history of hypertension and 8 age-matched nonobese men. We also measured body composition and insulin regulation of free fatty acid (FFA) and glucose metabolism. Forearm blood flow was measured before and during brachial artery infusions of acetylcholine (Ach), sodium nitroprusside (NTP), and angiotensin II (+/-nitric oxide synthase [NO]) synthase blockade with N(G)-monomethyl L-arginine [L-NMMA]). On a separate day, baseline and insulin-regulated glucose ([3-3H]glucose) and FFA ([9,10-3H]palmitate) turnover were measured. The vasoconstrictor response to angiotensin II was greater (P<0.05) in obese men than in nonobese men, whereas endothelium-dependent vasodilation was similar. The slope of the angiotensin II dose-response curve correlated significantly with the basal plasma palmitate concentration. Basal and insulin-mediated glucose disposal was significantly reduced and FFA turnover significantly increased in viscerally obese men. No differences in endothelium-independent vasodilation or relationships between vascular responsivity and palmitate and glucose kinetics or body composition were found. Angiotensin II-stimulated forearm vasoconstriction is increased in viscerally obese normotensive men.
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PMID:Vascular response to angiotensin II in upper body obesity. 1533 33

The major cause of morbidity and mortality in persons with diabetes is cardiovascular disease (CVD), the risk of which is increased three- to four-fold versus persons without diabetes. The biology of diabetes is characterized not only by hyperglycemia but also by hypertension, dyslipidemia, microalbuminuria, inflammation, and abnormal thrombolysis. Hypertension is a common feature of diabetes and is the primary contributor to CVD. Recent investigations have revealed a relationship between vascular derangements, insulin resistance, and visceral obesity and have implicated the renin-angiotensin-aldosterone system (RAAS) as a key mediator of cardiovascular dysfunction in diabetes. Angiotensin II has been shown to have direct effects on endothelial dysfunction, oxidative stress, inflammation, skeletal muscle, and adipocyte function. These pathophysiologic considerations have formed the basis for CVD prevention strategies in diabetes. Clinical trials have demonstrated a reduction in cardiovascular events with aspirin, lipid-lowering agents, and antihypertensive agents. Blood pressure (BP) control (<130/80 mm Hg) is a crucial component of risk reduction, and several studies have demonstrated the need for multiple agents to reach therapeutic goals. Clinical trials also demonstrated the benefit of RAAS blocking agents in reducing BP and cardiovascular and renal risk, and suggest clinical benefits beyond BP reduction.
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PMID:Insights into the biology of diabetic vascular disease: what's new? 1553 7

Diabetes (particularly type 2 diabetes) represents a global health problem of epidemic proportions. Individuals with diabetes are not only more likely to develop hypertension, dyslipidemia, and obesity, but are also at a significantly higher risk for coronary heart disease, peripheral vascular disease, and stroke. Angiotensin II plays a key pathophysiological role in the progression of diabetic renal disease, and blockade of the renin-angiotensin system with angiotensin-converting enzyme inhibitors (ACEi) or angiotensin II antagonists has therefore become an important therapeutic strategy to reduce renal and cardiovascular events in patients with diabetes. Several studies have demonstrated the effects of angiotensin II antagonists on the reduction of albuminuria and the progression of renal disease from microalbuminuria to macroalbuminuria. More importantly, several endpoint trials have shown that the antiproteinuric effects of losartan and irbesartan translate into cardiovascular and renoprotective benefits beyond blood pressure lowering, thereby delaying the need for dialysis or kidney transplantation by several years. These and other studies indicate that angiotensin II antagonists not only improve survival and quality of life of patients with diabetic nephropathy, but also have the potential to reduce the substantial healthcare burden associated with managing these patients. ACEi also appear to exert similar beneficial effects in diabetic patients, but whether clinically significant differences in renoprotection or mortality exist between angiotensin II antagonists and ACEi in patients with type 2 diabetes remains to be fully investigated in appropriate head-to-head studies.
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PMID:Blockade of the renin-angiotensin-aldosterone system: a key therapeutic strategy to reduce renal and cardiovascular events in patients with diabetes. 1633 Oct 93

The metabolic syndrome incorporates into a single entity, insulin resistance and its associated cluster of related cardiovascular metabolic risk factors including type 2 diabetes mellitus, essential hypertension, dyslipidamia and central obesity. Various hypotheses (thrifty genotype/phenotype, limbic-hypothalamic and altered homeostatic mechanisms) have been used to explain the interaction between genetic, intrauterine and environmental factors, leading to this enigmatic concept. Current interest addresses the roles of fat-derived adiponectin, inflammatory markers (C-reactive protein, leucocytes, interleukin and tumour necrosis factor), endothelial dysfunction and disordered haemostasis (plasminogen activator inhibitor-1 and fibrinogen). Angiotensin II, endothelin-1 and increased salt sensitivity contribute to the development of hypertension in metabolic syndrome. The main significance of the syndrome is the heightened risk of cardiovascular morbidity and mortality arising from increased atherogenic potential. Therapeutic interventions are multidimensional in approach, and aimed at enhancing insulin sensitivity and ameliorating the consequences of insulin resistance. Promotion of African native lifestyle characterised by high degree of physical activity and fibre diet is and appropriate tool for primary prevention of metabolic syndrome.
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PMID:The metabolic syndrome: Review of current concepts. 1727 22

Obesity is a major health problem worldwide; it is associated with more than 30 medical conditions and is a leading cause of unnecessary deaths. Adipose tissue not only acts as an energy store, but also behaves like an endocrine organ, synthesising and secreting numerous hormones and cytokines. Angiotensin II (ANG II) is the biologically active component of the renin-angiotensin system (RAS). The RAS is present in adipose tissue and evidence suggests that ANG II is intimately linked to obesity. Indeed, ANG II increases fat cell growth and differentiation, increases synthesis, uptake and storage of fatty acids and triglycerides and possibly inhibits lipolysis. Evidence obtained using genetically modified animals has shown that the amount of body fat is directly related to the amount of ANG II, i.e., animals with low levels of ANG II have reduced fat stores while animals with excessive ANG II have increased fat stores. In humans, epidemiological evidence has shown that body fat is correlated with angiotensinogen, a precursor of ANG II, or other components of the RAS. Furthermore, blocking the production and/or actions of ANG II with drugs or natural substances decreases body fat. The decrease in body fat caused by such treatments predominantly occurs in abdominal fat depots and appears to be independent of energy intake and digestibility. Clearly, ANG II has an important role in the accumulation of body fat and the possibility exists that treatment of obesity will be enhanced by the use of natural or synthetic substances that interfere with ANG II.
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PMID:The problem of obesity: is there a role for antagonists of the renin-angiotensin system? 1739 33

Angiotensin II (Ang II) is able to induce free radical generation in neutrophils, which is more elevated in neutrophils of patients with hypercholesterolemia (HC). In addition, the signal processing through angiotensin I (Ang I) receptors is altered. In present study, we compared the Ang II-triggered free radical generation of neutrophils obtained from patients with relatively isolated forms of metabolic syndrome (MS) with membrane-bound cholesterol content and membrane fluidity. We determined the enhancement of Ang II-induced superoxide anion and leukotriene C(4) (LTC(4)) generation, membrane fluidity and cell-bound cholesterol content of neutrophils obtained from 12 control subjects, 11 patients with obesity (Ob), 10 patients with type 2 diabetes mellitus (t2-DM) and 12 patients with HC. The alteration of signal processing was studied after preincubation with different inhibiting drugs. Superoxide anion, LTC(4) production and membrane rigidity were increased in the following order: control < Ob < t2-DM < HC. Both Ang II-induced superoxide anion and LTC(4) generation were decreased in control cells by pertussis toxin and fluvastatin (Flu), whereas in each patient group, mepacrin, verapamil and Flu were effective, suggesting alterations in signal pathways, which may be attributed to isoprenylation. The enhancement of superoxide anion and LTC(4) generation correlated significantly with membrane rigidity, independently from the experimental groups and membrane-bound cholesterol content. Membrane rigidity of neutrophils, obtained from patients with MS, plays a role in Ang II-induced free radical generation independent of intracellular cholesterol homeostasis.
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PMID:The association between angiotensin II-induced free radical generation and membrane fluidity in neutrophils of patients with metabolic syndrome. 1754 12

Abdominal obesity is a risk factor for cardiovascular disease worldwide, and it is becoming a dramatic issue for national health systems. Overweight and obesity are highly associated with multiple comorbidities, elevated blood pressure values, dyslipidaemia, reduced insulin sensitivity and alterations of large and minor vessels. Activation of the renin-angiotensin system (RAS) in adipose tissue may represent an important link between obesity and hypertension. Angiotensin II has been shown to play a role in adipocyte growth and differentiation. Adipocytes also secrete adiponectin, enhancing insulin sensitivity and preventing atherosclerosis. Blockade of the RAS with either an angiotensin-converting enzyme inhibitor or an angiotensin II receptor blocker results in a substantial increase in adiponectin levels and improved insulin sensitivity. Obesity-related hypertension needs a comprehensive approach to treatment including both weight loss and pharmacological therapies. Antihypertensive drugs prescription should be based on guidelines recommendations for management of hypertension, taking into account the growing evidences about the relationship between some antihypertensive drugs and the development of new-onset diabetes. This review discusses the role of RAS in the relationship between obesity, essential hypertension and insulin resistance.
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PMID:Obesity, essential hypertension and renin-angiotensin system. 1790 24

High dietary fat intake is a major risk factor for the development of obesity, which is frequently associated with diseases such as hypertension and diabetes and thus accelerated atherosclerosis. Angiotensin II and endothelin-1 are powerful growth factors and vasoconstrictors implicated in regulating vascular tone, vascular structure, and inflammation. Reduced bioactivity of nitric oxide and increased formation of reactive oxygen species (ROS) have been associated with obesity and high dietary fat intake. This article reviews the effects of high-fat diet on vascular functional changes in rodents and humans. Changes include alterations in vasoconstrictor function and receptor expression, and modulators of endothelium-dependent vascular tone (eg, nitric oxide- or endothelium-dependent contracting factor-mediated responses). Novel vasodilator effects of ROS and the anatomic heterogeneity of vascular responses are discussed. The beneficial effects of vasoactive mediators on vascular function could play a role for susceptibility to obesity-dependent hypertension, which is present in many, but not all, obese patients.
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PMID:Fat intake and cardiovascular response. 1836 23

A local renin-angiotensin system (RAS) has been proposed in adipocytes. Adipocytes are a suggested source of components of the RAS, with regulation of their production related to obesity-hypertension. Both angiotensin type 1 and 2 receptors have been localized to adipocytes. Angiotensin II has been demonstrated to regulate adipocyte growth and differentiation, lipid metabolism, and expression and release of adipokines and RAS components, and to promote oxidative stress. Differences in regional expression of RAS components in visceral versus subcutaneous adipose tissue have been suggested as a link between abdominal obesity and cardiovascular disease. Finally, several studies support antihypertensive efficacy of RAS blockade in patients with type 2 diabetes and obesity. Future studies should address the role of adipocyte-specific deficiency of RAS components to definitively determine the relevance of the adipose RAS to normal physiology and to the development of hypertension.
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PMID:Local adipose tissue renin-angiotensin system. 1847 74


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