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

Techniques in the field of coronary artery imaging can be divided into two groups: invasive and non-invasive methods. Apart from the conventional coronary artery angiography, invasive methods include intracoronary ultrasound, intracoronary angioscopy, and optical coherence tomography. Non-invasive methods include magnetic resonance tomography, synchrotron-coronary angiography, and electron beam computed tomography. In the late 1980s, intracoronary ultrasound has come into clinical practice. It offers a real-time, cross-sectional image of the coronary artery in high resolution. Coronary arteries enlarge in the presence of atherosclerotic plaque formation in order to compensate for luminal narrowing caused by plaque formation (remodeling). With coronary angiography, the plaque formation cannot be detected until a lumen reduction of about 40-45%. With intravascular ultrasound, the early stages of atherosclerosis can clearly be demonstrated. In combination with the intracoronary Doppler technique, syndrome X can be differentiated. Another important role of intracoronary ultrasound in the diagnosis of coronary artery disease is to guide coronary interventions and to assess the result of coronary interventions especially to evaluate the result of stent implantation. Due to the clinical use of intracoronary ultrasound and the guidance of high pressure stent implantation, the incidence of acute stent thrombosis has decreased to about 1%. Coronary angioscopy portrays the surface of the vessel lumen. It is helpful to identify the mural thrombus especially to differentiate fresh and chronic thrombus formation. Magnetic resonance tomography is able to image the coronary arterial contour of the proximal segment. With today's gating technique, it is possible to portray the whole coronary tree and avoid disturbances resulting from the heart beat and respiration. Electron beam computed tomography is a very promising technique in screening for coronary artery disease. It is a very sensitive method to identify coronary calcification and, thus, to detect atherosclerotic plaque. Studies have shown that the presence of calcification almost invariably indicates the presence of coronary artery disease and that the absence of calcification can nearly rule out significant coronary artery disease. Moreover, a close correlation exists between the amount of calcification and the severity of coronary artery disease. Additionally, in combination with contrast injection, coronary artery perfusion can be evaluated. This is important to assess the conductance of coronary stent and bypass graft.
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PMID:[New imaging methods for visualizing coronary arteries]. 982 63

Insulin resistance is an early and major feature in the development of non-insulin-dependent diabetes mellitus(NIDDM). It is also associated with hyperlipidemia, hypertension, obesity and cardiovascular disease. It is the clustor of the risk factors for atherosclerosis and recognized as 'insulin-resistance syndrome' (Syndrome X). Central (abdominal) obesity is much more strongly associated with insulin resistance than overall obesity. The increase of both the influx of free fatty acid to liver and the production of TNF-alpha in adipose tissue may play an important role in mechanism of insulin resistance associated with central obesity. Calorie restriction and weight loss improve insulin sensitivity in overweight humans. Exercise training also improves insulin sensitivity via increased oxidative enzymes, glucose transporters (GLUT4) and capillarity in muscle as well as by reducing abdominal fat. The new 'glitazones' (thiazolidinediones) is used clinically to improve insulin sensitivity.
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PMID:[Syndrome X]. 1019 44

Cardiovascular risk factor clustering related to insulin resistance syndrome (Syndrome X) was examined in a community-based sample of 599 genetically unrelated school-aged children (5-17 years) and their parents. Risk factors used as components of Syndrome X included hyperinsulinemia, obesity, dyslipidemia and high blood pressure defined by values above the age-, sex- and race-specific 75th percentiles of fasting insulin, body mass index, triglycerides/high-density lipoprotein cholesterol ratio and mean arterial pressure, respectively. Based on observed to expected ratio there was an excess of parents (father and/or mother) and their offspring with clusters of three or four disorders (P < 0.05-0.001). In contrast, the number of parents and offspring with two disorders was significantly lower than expected by chance alone (P < 0.05-0.01). Based on paternal, maternal, and parental Syndrome X, the odds ratios (95% confidence interval) for offspring having the same cluster were 7.2 (1.9-27.2), 8.6 (3.1-23.6) and 7.9 (3.5-18.1), respectively. In terms of individual risk factors of parents used as predictors, adverse levels of their insulin and BMI significantly increased the risk of offspring having Syndrome X (P < 0.01-0.001), whereas the effect of parental insulin was considerably reduced after parental BMI was adjusted for. In contrast, parental dyslipidemia and high blood pressure were not associated with the occurrence of Syndrome X in their offspring. These results confirm the familial nature of Syndrome X and suggest that conditions of obesity and the attendant hyperinsulinemia in parents may underlie this familial association.
Atherosclerosis 1999 Jul
PMID:The association of cardiovascular risk factor clustering related to insulin resistance syndrome (Syndrome X) between young parents and their offspring: the Bogalusa Heart Study. 1042 11

The association of several risk factors, obesity, dyslipoproteinemia, hepatic steatosis, insulin resistance and hypertension with Type 2 (non-insulin-dependent) diabetes mellitus and myocardial infarction has long been known and has been termed the "metabolic syndrome". In 1988 Reaven introduced syndrome X as the link between insulin resistance and hypertension. It has been suggested that a critical factor in the association between obesity, Type 2 diabetes and cardiovascular morbidity is the mass of intraabdominal fat. Striking similarities exist between the metabolic syndrome and untreated growth hormone (GH) deficiency in adults. The central findings in both these syndromes are abdominal/visceral obesity and insulin resistance. Other features common to both conditions are premature atherosclerosis and increased mortality from cardiovascular diseases. These similarities indicate that undetectable and low levels of GH may be of importance in the metabolic aberrations observed in both these conditions. Recent investigations have found that abdominal/visceral distribution of adipose tissue is associated with endocrine disturbances including increased activity of the hypothalamic-pituitary-adrenal axis and a blunted secretion of GH and sex steroids. Theoretically, these endocrine perturbations can be a consequence of obesity, but the endocrine aberrations may have causal effects. We studied moderately obese, middle-aged men with a preponderance of abdominal body fat. As a group, they had slight to moderate metabolic changes known to be associated with abdominal/visceral obesity. Nine months of GH treatment reduced their total body fat and resulted in a specific and a marked decrease in both abdominal subcutaneous and visceral adipose tissue. Moreover, insulin sensitivity improved and serum concentrations of total cholesterol and triglyceride decreased. Diastolic blood pressure also decreased. The finding that GH replacement in men with abdominal obesity can diminish the negative metabolic consequences of visceral obesity suggests that low levels of this hormone are of importance for the metabolic aberrations associated with visceral/abdominal obesity.
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PMID:Growth hormone and the metabolic syndrome. 1044 70

Insulin resistance describes an impaired biological response to insulin, which underpins the development of type 2 (non-insulin-dependent) diabetes mellitus (T2DM). Initially, insulin resistance causes a compensatory hyperinsulinaemia, which gives way to pancreatic beta-cell failure. Insulin resistance and hyperinsulinaemia conspire together in the development of a diverse collection of risk factors for coronary heart disease, namely obesity, T2DM, dyslipidaemia, hypertension, atherosclerosis, and a pro-coagulant state. This collection of factors is commonly found in T2DM patients, and is recognised as the Insulin Resistance Syndrome or Syndrome X. By targeting insulin resistance as a treatment strategy for T2DM, it should be possible to broaden the potential benefits, so that improved glycaemic control is complemented with improvements to other components of Syndrome X. At present, metformin and thiazolidinediones are the only therapies for T2DM that directly address aspects of insulin resistance. Increasing awareness of the clinical implications of insulin resistance, and increasing knowledge of the cellular basis of insulin resistance, provide the rationale and a means for developing an anti-insulin resistance approach to the treatment of T2DM.
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PMID:Insulin resistance and antidiabetic drugs. 1053 41

It has been increasingly recognised in recent years that type 2 (non-insulin-dependent) diabetes is part of a cluster of cardiovascular risk factors known as the metabolic syndrome, but also endorsed with such names as the deadly quartet, syndrome X and the insulin resistance syndrome. Atherosclerosis is the most common complication of type 2 diabetes among Europeans, and coronary artery, cerebrovascular and peripheral vascular disease are 2 to 5 times more common in people with this condition than in those without diabetes. These observations indicate that the treatment of type 2 diabetes requires agents that do more than simply lower blood glucose levels, and a therapy with both antihyperglycaemic effects and beneficial effects on dyslipidaemia, hypertension, obesity, hyperinsulinaemia and insulin resistance is likely to be most useful. In this respect, metformin has an important and established role: this drug has been shown to lower blood glucose and triglyceride levels, and to assist with weight reduction and to reduce hyperinsulinaemia and insulin resistance. Studies in the Israeli sand rat, Psammomys obesus, have indicated hyperinsulinaemia/insulin resistance to be the initial and underlying metabolic disorder in obesity and type 2 diabetes. Thus, the well established effect of metformin in reducing insulin resistance makes this drug an excellent candidate for the prevention of progression of impaired glucose tolerance to type 2 diabetes, and for the reduction of mortality associated with cardiovascular disease.
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PMID:Clinical efficacy of metformin against insulin resistance parameters: sinking the iceberg. 1057 21

Type 2 diabetes mellitus has emerged as an important condition of older patients in which both microvascular and macrovascular complications are a common cause of morbidity and mortality. In contrast to type 1 diabetes mellitus, this endocrinopathy is clustered in minority populations and has both strong genetic and environmental factors that influence disease manifestation. A number of physiological alterations of glucose metabolism including hepatic overproduction of glucose, and reduced glucose utilization by peripheral tissues as a result of insulin resistance contribute to the development of the metabolic manifestations of this disease. Ultimately, pancreatic failure and reduced insulin secretion lead to hyperglycemia and the diabetic state. Frequently, many of these metabolic manifestations, or what has been termed Syndrome X, antecede the development of overt diabetes by many years. This syndrome is manifest clinically by such cardiovascular risk factors as hypertension, dyslipidemia, and coagulation abnormalities. This abnormal metabolic milieu contributes to the high prevalence of macrovascular complications including coronary artery disease as well as more generalized atherosclerosis. Microvascular complications have only more recently been recognized as an important and frequent complication of type 2 diabetes. Among the elderly and minority populations, this has become the single most important cause of end-stage renal failure that necessitates renal replacement therapies. The outcome for these patients on hemodialysis, the modality most frequently selected, is poor, with the majority of these patients dying of cardiovascular causes. Unfortunately, interventional strategies to reduce or prevent the microvascular and macrovascular complications have only recently received the needed attention and will require considerable effort and resources to improve the clinical outcomes and life expectancies for these patients.
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PMID:Diabetes in the elderly population. 1067 16

Insulin resistance syndrome (IRS), also termed syndrome X, is a distinctive constellation of risk factors for the development of type 2 diabetes mellitus and cardiovascular disease. The syndrome's hallmarks are glucose intolerance, hyperinsulinemia, a characteristic dyslipidemia (high triglycerides; low high-density lipoprotein cholesterol, and small, dense low-density lipoprotein cholesterol), obesity, upper-body fat distribution, hypertension, and increased prothrombotic and antifibrinolytic factors. Insulin resistance, caused by a complex of genetic and environmental influences, is now recognized not just as a mechanism contributing to hyperglycemia in type 2 diabetes, but also as an early metabolic abnormality that precedes the development of overt diabetes. The clinical definition of insulin resistance is the impaired ability of insulin (either endogenous or exogenous) to lower blood glucose. In some insulin-resistant individuals, insulin secretion will begin to deteriorate under chronic stress (glucose toxicity) and overt diabetes will result. If not, individuals will remain hyperinsulinemic, with perhaps some degree of glucose intolerance, together with other hallmarks of the IRS. The statistical correlation between hypertension and impaired glucose tolerance is clear, although the mechanism is not yet fully understood. Epidemiologic evidence of insulin resistance as an independent risk factor for atherosclerosis and coronary heart disease (CHD) completed the evolving concept of IRS as the common soil for the development of both diabetes and CHD. No single laboratory test exists for diagnosis of IRS. Rather, IRS remains a clinically evident syndrome that can be suspected on the basis of physical and laboratory findings. This identifies individual patients whom the clinician should screen for associated comorbid conditions, aggressively control cardiovascular risk factors, and tailor drug therapy for optimal benefit. This article provides practical guidelines to achieve these goals and specific strategies to ameliorate cardiovascular and metabolic risk in the IRS.
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PMID:Clinical implications of the insulin resistance syndrome. 1068 70

Endothelins (ET) comprise a group of substances which are produced and have a regulatory function in different systems of the organism. The main cardiovascular ET is ET-1 which is so far the most potent vasoconstrictor substance. ET is important in the early stages of atherosclerosis as it is a strong chemical attractant of monocytes and macrophages and causes endothelial and vasomotor dysfunction. In later stages of atherosclerosis it can affect the firmness and integrity of the fibrous part of the atherosclerotic plaque. During myocardial infarction the ET level rises and this leads to vasoconstriction and reduction of the fibrillation threshold. In coronary angioplasty (PTCA) the ET-1 level rises depending on the applied mechanical stress. ET can participate in the formation of the neointima and the development of restenosis. ET increases also immediately after an aortocoronary bypass (CABG) and after reperfusion. Higher ET levels were found in patients with a positive ECG and echocardiographic loading test. In the latter after CABG normalization of ET was found. Raised ET levels were recorded also in patients where a coronary vasospasm can be provoked, in Prinzmetal's angina pectoris, coronary syndrome X, atrial tachystimulation. In unstable angina pectoris big-ET is elevated, the increase of the ET-1 level is not unequivocal. Stable angina pectoris does not affect ET-1. In the treatment of atherosclerosis for the selective ETA blocker reduction of the number and size of macrophage and foam cells was proved. In acute myocardial infarction a favourable effect for the non-selective ETA/ETB blocker and for the selective ETA blocker was found. In the treatment of restenosis after PTCA blockers of selective ETB receptors and inhibitors of endothelin converting enzyme seem hopeful. Th non-selective ETA/ETB blocker bosentan is in the stage of clinical tests and seems to be safe and perspective.
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PMID:[Endothelins and ischemic heart disease]. 1095 65

Intravascular ultrasound (IVUS) is a clinically useful tool that provides cross-sectional images of the coronary arterial lumen and wall. Diagnostic applications of IVUS include the evaluation of ambiguous lesions on angiography particularly at the bifurcations. IVUS is also useful in the assessment of coronary vasculopathy in cardiac transplant patients or it can help to diagnose abnormalities such as syndrome X or coronary artery spasm. IVUS can optimize the performing of percutaneous coronary interventions, especially stent implantation. It represents as well an optimal tool for assessing regression of atherosclerosis. Three-dimensional reconstruction, elastography and imaging guide wires are some of the recent advances in the field of intravascular ultrasound.
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PMID:[Intravascular ultrasound in cardiology]. 1104 4


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