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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Insulin resistance is a key factor in the pathogenesis of type 2 diabetes mellitus and a co-factor in the development of dyslipidaemia, hypertension and atherosclerosis. The causes of insulin resistance include factors such as obesity and physical inactivity, and there may also be genetic factors. The mechanism of obesity-related insulin resistance involves the release of factors from adipocytes which exert a negative effect on glucose metabolism: free fatty acids, tumour necrosis factor-alpha and the recently discovered hormone, resistin. The two resulting abnormalities observed consistently in glucose-intolerant states are impaired suppression of endogenous glucose production, and impaired stimulation of glucose uptake. Among the genetic factors, a polymorphism (Pro12Ala) in the peroxisome proliferator-activated receptor (PPAR) gamma is associated with a reduced risk of type 2 diabetes mellitus and increased insulin sensitivity, primarily that of lipolysis. On the other hand, the association with insulin resistance of a common polymorphism (Gly972Arg) in the insulin receptor substrate 1, long believed to be a plausible candidate gene, is weak at best. This polymorphism may instead be associated with reduced insulin secretion, which, in view of the recent recognition of the insulin signalling system in beta-cells, results in the development of a novel pathogenic concept. Finally, fine-mapping and positional cloning of the susceptibility locus on chromosome 2 resulted in the identification of a polymorphism (UCSNP-43 G/A) in the calpain-10 gene. In non-diabetic Pima Indians, this polymorphism was associated with insulin resistance of glucose disposal. The pharmacological treatment of insulin resistance has recently acquired a novel class of agents: the thiazolidinediones. They act through regulation of PPARgamma-dependent genes and probably interfere favourably with factors released from adipocytes which mediate obesity-associated insulin resistance.
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PMID:Insulin resistance and insulin sensitizers. 1168 68

Obesity, a state of increased adipose tissue mass, is a major cause for type 2 diabetes, hyperlipidemia, and hypertension, resulting in clustering of risk factors for atherosclerosis. Heterozygous PPARgamma knockout mice and KKA(y) mice administered with a PPARgamma antagonist were protected from high-fat diet-induced adipocyte hypertrophy and insulin resistance. Moderate reduction of PPARgamma activity prevented adipocyte hypertrophy, thereby diminution of TNFalpha, resistin, and FFA and upregulation of adiponectin and leptin. These alterations led to reduction of tissue TG content in muscle/liver, thereby ameliorating insulin resistance. Insulin resistance in the lipoatrophic mice and KKA(y) mice were ameliorated by replenishment of adiponectin. Moreover, adiponectin transgenic mice ameliorated insulin resistance and diabetes, but not the obesity of ob/ob mice. Furthermore, targeted disruption of the adiponectin gene caused moderate insulin resistance and glucose intolerance. In muscle, adiponectin activated AMP kinase and PPARgamma pathways, thereby increasing beta-oxidation of lipids, leading to decreased TG content, which ameliorated muscle insulin resistance. In the liver, adiponectin also activated AMPK, thereby downregulating PEPCK and G6Pase, leading to decreased glucose output from the liver. In conclusion, PPARgamma plays a central role in the regulation of adipocyte hypertrophy and insulin sensitivity. The upregulation of the adiponectin pathway by PPARgamma may play a role in the increased insulin sensitivity of heterozygous PPARgamma knockout mice, and activation of adiponectin pathway may provide novel therapeutic strategies for obesity-linked disorders such as type 2 diabetes and metabolic syndrome.
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PMID:[The mechanisms by which PPARgamma and adiponectin regulate glucose and lipid metabolism]. 1450 Nov 64

Normal metabolic balance is maintained by a complex homeostatic system involving multiple tissues and organs. Acquired or inherited defects associated to environmental factors in any part of this system can lead to metabolic disorders such as the syndrome X which is presently a frequent syndrome in industrialized countries. It is characterized by a cluster of risk factors of atherosclerosis including insulin resistance, hyperinsulinemia, impaired glucose tolerance or type 2 diabetes, hypertension, dyslipidemia, and coagulation abnormalities. Its pathophysiology is likely to involve insulin resistance at the level of both skeletal muscle and visceral adipose tissue and altered fluxes of metabolic substrates between these tissues that in turn impair liver metabolism. Therapeutic intervention favours at present diet and exercise prescriptions. In addition, if necessary, specific treatment of the metabolic disorders is required. In the treatment of insulin resistance, new promising drugs are likely to be used in the next future. In this regard, adipose tissue, once thought to function primarily as a passive depot for the storage of excess lipid, is now understood to play a much more active role in metabolic regulation, secreting a variety of metabolic hormones and actively functioning to prevent deleterious lipid accumulation in other tissues and to modulate the insulin resistance. Here, we review new advances in our understanding of mechanisms leading to insulin resistance and type 2 diabetes from the perspective of the role and interactions of recently identified adipocyte-specific chemical messengers, the adipocytokines, such as adiponectin, tumor necrosis factor-alpha, interleukin 6, and resistin.
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PMID:[Adipocytokins, obesity and development of type 2 diabetes]. 1459 11

Resistin is an adipocytokine which plays a role in the development of insulin resistance. In this study, we investigated the direct effect of resistin on vascular endothelial cells. Resistin induced the expression of adhesion molecules such as VCAM-1 and ICAM-1, and long pentraxin 3, a marker of inflammation. The induction of VCAM-1 by resistin was inhibited partially by pitavastatin. Moreover, the induction of VCAM-1 and ICAM-1 by resistin was inhibited by adiponectin, an adipocytokine that improves insulin resistance. Taken together, these results suggest that the balance in the concentrations of adipocytokines such as resistin and adiponectin determines the inflammation status of vasculature, and in turn the progress of atherosclerosis.
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PMID:Direct reciprocal effects of resistin and adiponectin on vascular endothelial cells: a new insight into adipocytokine-endothelial cell interactions. 1473 21

It is now recognized that the white adipose tIssue (WAT) produces a variety of bioactive peptIdes, collectively termed "adipokines". Alteration of WAT mass in obesity or lipoatrophy, affects the production of most adipose secreted factors. Since both conditions are associated with multiple metabolic disorders and increased risk of cardiovascular diseases, the Idea has emerged that WAT could be instrumental in these complications, by virtue of its secreted factors. Several adipokines are increased in the obese state and have been implicated in hypertension (angiotensinogen), impaired fibrinolysis (PAI-1) and insulin resistance (ASP, TNFalpha, IL-6, resistin). Conversely, leptin and adiponectin both exert an insulin-sensitizing effect, at least in part, by favoring tIssue fatty-acId oxIdation through activation of AMP-activated kinase. In obesity, insulin resistance has been linked to leptin resistance and decreased plasma adiponectin. In lipoatrophic mice, where leptin and adiponectin circulating levels are low, administration of the two adipokines synergistically reverses insulin resistance. Leptin and adiponectin also have distinct properties: leptin, as a long-term integrative signal of energy store and adiponectin, as a potent anti-atherogenic agent. The thiazolIdinedione anti-diabetic drugs increase endogenous adiponectin production in rodents and humans, supporting the Idea that the development of new drugs targeting adipokines might represent a promising therapeutic approach to protect obese patients from insulin resistance and atherosclerosis.
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PMID:Adipose tissue and adipokines: for better or worse. 1502 93

Obesity and noninsulin-dependent diabetes mellitus are globally epidemic. Insulin resistance is a major contributor to the pathogenesis of type II diabetes and plays a role in numerous other metabolic disorders including hypertension, dyslipidaemia and atherosclerosis. Obesity, in particular visceral adiposity, is positively correlated with insulin resistance. Although this correlation between adiposity and insulin resistance is well established in human beings as well as in rodent models, the mechanisms involved in obesity-related insulin resistance are not fully defined. One mechanism is that factors secreted from adipocytes can affect peripheral insulin resistance. One candidate for such a factor is resistin, an adipocyte-secreted hormone that impairs glucose homeostasis and insulin action in the mouse. This review will summarize our current understanding of resistin and will attempt to provide a framework for future study of its role in rodent and human physiology.
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PMID:The current biology of resistin. 1504 78

Adipose tissue is a hormonally active tissue, producing adipocytokines which may influence activity of other tissues. Adiponectin, abundantly present in the plasma increases insulin sensitivity by stimulating fatty acid oxidation, decreases plasma triglycerides and improves glucose metabolism. Adiponectin levels are inversely related to the degree of adiposity. Anorexia nervosa and type 1 diabetes are associated with increased plasma adiponectin levels and higher insulin sensitivity. Decreased plasma adiponectin levels were reported in insulin-resistant states, such as obesity and type 2 diabetes and in patients with coronary artery disease. Activity of adiponectin is associated with leptin, resistin and with steroid and thyroid hormones, glucocorticoids, NO and others. Adiponectin suppresses expression of extracellular matrix adhesive proteins in endothelial cells and atherosclerosis potentiating cytokines. Anti-atherogenic and anti-inflammatory properties of adiponectin and the ability to stimulate insulin sensitivity have made adiponectin an important object for physiological and pathophysiological studies with the aim of potential therapeutic applications.
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PMID:Adiponectin, an adipocyte-derived protein. 1554 26

Certain management practices tend to promote the development of obesity (metabolic syndrome) in mature horses as they enter their teenage years. These management practices include the provision of starch-rich (high glycemic index) and fat-supplemented rations to healthy horses that are relatively inactive. Some horse breeds and ponies appear to be genetically predisposed to metabolic syndrome. The accretion of intra-abdominal adiposity by equids is associated with the development of insulin insensitivity (hyperinsulinemia), glucose intolerance, dyslipidemia, hypertension, and insidious-onset laminitis. Omental adipocytes are metabolically active, secreting free fatty acids and hormonally active mediators including cortisol, leptin, and resistin that might contribute to persistence and worsening of insulin refractoriness and the obese phenotype. We have hypothesized that obesity-associated laminitis arises as a consequence of vascular changes and a hypercoagulable state, similar to the development of atherosclerosis in human type 2 diabetes. Several molecular mechanisms that might serve to explain the development of insulin insensitivity as a result of excessive adiposity have been incriminated. Little investigation into the relationship between obesity, insulin insensitivity, and laminitis in horses has been reported to date. Insulin sensitivity and glucose tolerance can be improved by dietary restriction and exercise aimed at reversing omental obesity. Management practices that promote the development of obesity are likely initiated during the first 10 years of the horse's life. Veterinarians and horse owners must recognize that mature-onset obesity in adult horses is associated with a risk for development of laminitis. Obesity and insulin insensitivity might be prevented if horse owners can be educated to feed rations with a relatively lower glycemic index to inactive horses. Investigative research pertaining to the development of antiobesity drugs for human patients is continuing. Greater than 30 new pharmaceuticals are in various stages of research. However, it will likely take many years before any of these drugs are shown to be useful and safe in horses. Lifestyle changes in the form of diet and exercise patterns are still the crux of therapy for both human and equine patients.
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PMID:The equine metabolic syndrome peripheral Cushing's syndrome. 1563 8

An activated inflammatory response is a common feature of end-stage renal disease (ESRD) patients and predicts outcome. Although various factors related to the dialysis procedure may contribute to inflammation in ESRD, a number of nondialysis-related factors also are of importance. Adipose tissue is a complex organ with functions far beyond the mere storage of energy and secretes a number of proinflammatory adipokines, such as leptin, resistin, tumor necrosis factor-alpha and interleukin-6, as well as one anti-inflammatory adipokine, adiponectin. It has been proposed that adipose tissue may be a significant contributor to increased systemic inflammation in nonrenal patients. In this review, we put forward the hypothesis that a reduction of renal mass will contribute to retention of proinflammatory adipokines, thus generating adipokine imbalance. Such an imbalance may, via effects on the central nervous system and the vasculature, contribute to wasting, atherosclerosis, and insulin resistance--all common features of ESRD.
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PMID:Adipose tissue and its relation to inflammation: the role of adipokines. 1564 22

Obesity alone is the cause of 11% of cases of cardiac failure in men and 14% of cases in women in the United States. The frequency of obesity continues to rise in our country, 41% of our compatriots being obese or overweight. It is expected that obesity will become an important cause of cardiac failure in the coming years. The Framingham study showed that, after correction for other risk factors, for every point increase in body mass index, the increase in risk of developing cardiac failure was 5% in men and 7% in women. There are three physiopathological mechanisms to explain the adverse effects of obesity on left ventricular function: an increase in ventricular preload secondary to increased plasma volume induced by the high fatty mass; an increase in left ventricular afterload due to the common association of hypertension generated by activation of the sympathetic nervous system by hyperinsulinism; and systolic and diastolic dysfunction due to changes in the myocardial genome and coronary artery disease induced by risk factors of atherosclerosis aggravated by obesity. The adipocyte also secretes a number of hormones which act directly or indirectly on the myocardium: angiotensin II, leptin, resistin, adrenomedulin, cytokines. These haemodynamic and hormonal changes profoundly modify the genetic expression of the myocardium in obesity, favourising hypertrophy of the myocyte and the development of interstitial fibrosis. Whether it be eccentric in the absence of hypertension or concentric when hypertension is associated with obesity, left ventricular hypertrophy, although normalising left ventricular wall stress, has adverse consequences causing abnormal relaxation and decreased left ventricular compliance. Therefore, in obese patients, two forms of cardiac failure may be observed. The more common is due to diastolic dysfunction, obesity being one of the principal causes of cardiac failure with preserved systolic function. Cardiac failure due to systolic dysfunction is less common and may be observed in cases with inappropriate left ventricular hypertrophy which does not normalise abnormal left ventricular wall stress leading to cardiomyopathy, and in cases with associated coronary artery disease. Whatever the underlying mechanism, the diagnosis of cardiac failure is made more difficult by obesity. From the prognostic point of view, in the global population of patients with cardiac failure, obesity improves survival because it counteracts the adverse effect of cachexia; however, obesity increases the risk of sudden death. In fact, obesity is associated with dynamic change in QT interval. In cases of cardiac failure secondary to obesity-related cardiomyopathy, loss of weight leads to an improved functional status and a reduction of left ventricular remodelling and an increase of the ejection fraction.
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PMID:[Obesity and cardiac failure]. 1572 18


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