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Query: UMLS:C0011854 (type 1 diabetes)
 20,749 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endothelial dysfunction is known to occur in chemically-induced animal models of diabetes. The BB diabetic rat is a genetic diabetes-prone model which more closely resembles Type I diabetes mellitus. In this study, we examined the role of superoxide anion radical and cyclooxygenase activity on endothelial dysfunction in aorta of the spontaneous diabetic BB rat. Vascular endothelial function was studied in vitro in aortic rings from 8-wk diabetic rats and age-matched nondiabetic littermates. There was no alteration in reactivity to norepinephrine as a result of diabetes. Relaxation to acetylcholine (but not nitroglycerin) was impaired in diabetic rings. Relaxation to acetylcholine was abolished by 100 microM L-nitroarginine but unaltered by an equimolar concentration of aminoguanidine (an inducible nitric oxide synthase inhibitor) in both control and diabetic rings. Incubation with 10 microM indomethacin did not alter relaxation to acetylcholine in either control or diabetic rings. In contrast, addition of 20 U/ml superoxide dismutase enhanced relaxation to acetylcholine in diabetic rings but had no effect on relaxation to acetylcholine in control rings. Thus, nitric oxide-mediated, endothelium-dependent relaxation is diminished in aortic rings of the genetic diabetic BB rat. Furthermore, superoxide anion radicals but not cyclooxygenase products play an important role in endothelial dysfunction in this genetic diabetic model.
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PMID:Evaluation of the mechanism of endothelial dysfunction in the genetically-diabetic BB rat. 863 17

Endothelial dysfunction has been implicated in the pathogenesis of diabetic vascular disorders such as diabetic retinopathy. We hypothesized that either local endogenous nitric oxide (NO) synthesis or local reactivity to endogenous NO might be impaired in patients with IDDM and that this may contribute to the development of diabetic retinopathy. Ten otherwise healthy patients with long-standing IDDM and ten healthy control subjects were studied according to an open randomized two-way cross-over design. Subjects received intravenous infusions of either N(G)-monomethyl-L-arginine, an inhibitor of NO-synthase, or L-arginine, the precursor of NO synthesis, on two separate study days. Ocular hemodynamics were assessed by laser interferometric measurement of fundus pulsations and Doppler sonographic measurement of blood flow velocity in the ophthalmic artery. N(G)-monomethyl-L-arginine decreased fundus pulsations and blood flow velocity in the ophthalmic artery and increased blood pressure in healthy subjects. The responses to NO-synthase inhibition were significantly less in diabetic subjects. In contrast, L-arginine caused a comparable increase in fundus pulsations and decrease in blood pressure in both cohorts. These results indicate that systemic and ocular hemodynamic reactivity to NO-synthase inhibition is reduced in patients with long-standing IDDM, compared with healthy control subjects. Thus, this study indicates that either NO-synthase activity is increased or NO sensitivity is decreased in patients with IDDM and supports the concept of an involvement of the L-arginine-NO system in the pathophysiology of diabetic retinopathy.
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PMID:Nitric oxide and ocular blood flow in patients with IDDM. 907 7

Endothelial dysfunction is considered a key early event in atherosclerosis. Using a novel ultrasound method, brachial artery endothelial and smooth muscle physiology were studied in 20 adolescents with IDDM and compared to that in 20 nondiabetic subjects matched for age (13-22 years), gender and vessel size. Endothelium-dependent dilatation (EDD) was assessed in response to flow (EDD) and endothelium-independent vasodilatation after sublingual glyceryl trinitrate (GTN). Both EDD and GTN were reduced in those with IDDM compared with controls: 5% vs 9%, (p = 0.0002) and 14% vs 21% (p = 0.002). Abnormal EDD was found in 12 IDDM adolescents (diabetes duration 3.3-14.9 years). The maximum albumin excretion rate of the diabetic group was 17 micrograms/min. Four adolescents had retinopathy assessed by stereoscopic fundus photography. Three had at least one of four cardiovascular autonomic test abnormalities. There was no significant correlation observed between the test for early large vessel disease and those for diabetic microangiopathy. Large vessel dysfunction was the most common abnormality.
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PMID:Large vessel dysfunction in diabetic adolescents and its relationship to small vessel complications. 946 29

Diabetic Nephropathy (DN) is the commonest cause of end-stage renal failure (ESRF) in the Western world. Diabetic nephropathy follows a well outline clinical course, starting with microalbuminuria through proteinuria, azotaemia and culminating in ESRF. Before the onset of overt proteinuria, there are various renal functional changes including renal hyperfiltration, hyperperfusion, and increasing capillary permeability to macromolecules. Basement-membrane thickening and mesangial expansion have long been recognized as pathological hallmark of diabetes. It has been postulated that DN occurs as a result of the interplay of metabolic and hemodynamic factors in the renal microcirculation. There is no doubt that there is a positive relationship between hyperglycaemia, which is necessary but not sufficient, and microvascular complications. The accumulation of advanced glycosylated end-products (AGEs), the activation of isoform(s) of protein kinase C (PKC) and the acceleration of the aldose reductase pathway may explain how hyperglycemia damages tissue. PKC is one of the key signaling molecules in the induction of the vascular pathology of diabetes. The balance between extracellular matrix production and degradation is important in this context. Transforming growth factor-beta (TGF-beta) appears to play a pivotal role in accumulation in the diabetic kidney. Hemodynamic disturbances are believed to be directly responsible for the development of glomerulosclerosis and its attendant proteinuria. There is familial clustering of diabetic kidney disease. A number of gene loci have been investigated to try to explain the genetic susceptibility to diabetic nephropathy. The genes coding for components of renin-angiotensin system have drawn special attention, due to the central role that this system plays in the regulation of blood pressure, sodium metabolism, and renal hemodynamics. Endothelial dysfunction is closely associated with the development of diabetic retinopathy, nephropathy and atherosclerosis, both in IDDM and in NIDDM. The pathogenesis of diabetic nephropathy is not clarified completely yet.
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PMID:Pathogenesis of diabetic nephropathy. 1146 May 89

Endothelial dysfunction is defined as the loss of endothelium properties, e.g. alteration of protein synthesis, increased vascular tone and permeability, acquisition of prothrombotic and antifibrinolytic properties. Endothelium, a primary target of unbalanced glycaemic control, is involved in the pathogenesis of vascular complications in patients with type 1 diabetes mellitus (DM). Vascular endothelium damage is characterised by an increase of endothelium-derived regulatory proteins. vWF and t-PA may be useful to investigate early endothelium involvement. However, impaired endothelium-dependent vasodilatation may be a more sensitive marker. Abnormal markers of endothelial cell activation and impaired endothelium-dependent vasodilatation have been observed in young patients with type I DM. Hyperglycaemia may alter normal endothelium functions, either directly or indirectly, by inducing different metabolic pathways. Complete understanding of the pathophysiology of endothelial dysfunction may lead to timely therapeutic intervention to prevent its development and to slow the progression of diabetic complications.
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PMID:Endothelial dysfunction in children with type 1 diabetes mellitus. 1200 80

Endothelial dysfunction occurs early in the development of vascular disease in diabetes. Total plasma homocyst(e)ine (tHcy) is associated with endothelial dysfunction. We therefore aimed to assess endothelial function in children with type 1 diabetes in relation to tHcy and its determinants. Endothelial function was assessed in 36 children with type 1 diabetes aged 13.7 +/- 2.2 years and 20 age- and sex-matched control subjects using ultrasound assessment of flow-mediated dilatation (FMD) and glyceryl trinitrate (GTN)-dependent brachial artery responses. von Willebrand factor (vWF) and thrombomodulin, markers of endothelial activation, were measured in 64 children with type 1 diabetes and 52 control subjects. Fasting glucose, tHcy, serum and red cell folate, vitamin B12, HbA(1c), creatinine, and lipids were also measured. FMD (5.2 +/- 4.7 vs. 9.1 +/- 4.0%, P = 0.002) and the ratio of FMD:GTN-induced dilatation (0.22 +/- 0.39 vs. 0.41 +/- 0.29%, P = 0.008) were significantly lower in diabetic subjects, indicating endothelial dysfunction. In diabetic subjects, red cell folate correlated independently with FMD (beta = 0.42, P = 0.028) and the ratio of FMD:GTN-induced dilatation (beta = 0.59, P < 0.001). Resting vessel diameter correlated independently with tHcy (beta = -0.51, P < 0.001) and height (beta = 0.65, P < 0.001). vWF correlated independently with HbA(1c) (beta = 0.38, P = 0.003), and thrombomodulin correlated independently with red cell folate (beta = -0.38, P = 0.005), tHcy (beta = -0.37, P = 0.004), diastolic blood pressure (beta = -0.28, P = 0.025), and creatinine clearance (beta = 0.26, P = 0.033). Children with type 1 diabetes have early endothelial dysfunction. Better folate status is associated with better endothelial function, as measured by higher FMD, higher FMD:GTN ratio, and lower thrombomodulin. Folate may therefore protect against endothelial dysfunction in children with diabetes.
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PMID:Endothelial dysfunction relates to folate status in children and adolescents with type 1 diabetes. 1208 61

In nondiabetic individuals, a poor response to an endothelium-dependent vasodilator in coronary vessels has been shown to increase the likelihood of a future cardiovascular event. Such prospective data are not as yet available in patients with type 1 or type 2 diabetes. However, consistent with the greatly increased cardiovascular risk in these patients, endothelial dysfunction has been almost universally found to characterize patients with type 2 diabetes particularly. Endothelial dysfunction frequently coexists with features of insulin resistance, such as the presence of small dense low-density lipoprotein (LDL) particles even in nondiabetic individuals. This association is independent of obesity and other causes of endothelial dysfunction, such as LDL cholesterol, hypertension, and smoking. In patients with type 1 diabetes, endothelial dysfunction has been found in approximately half of the studies. In some but not all studies, endothelial dysfunction has been especially severe in patients with poor glycemic control. Reversal or amelioration of endothelial dysfunction has been documented by many commonly used therapeutic agents such as successful insulin therapy, fibrates, and angiotensin-converting enzyme inhibitors, but also with some but not all agents that act as antioxidants. Long-term studies addressing the prognostic significance of endothelial dysfunction and its reversal are urgently needed to determine whether measurement of endothelial function could be used to identify individuals at risk better than can be done at present using classic risk factor assessment among patients with type 2 diabetes especially.
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PMID:Endothelial dysfunction in human diabetes. 1264 20

Coronary vascular disease is one facet of a generalized disturbance of vascular function present throughout the vascular tree. Dysfunction of the endothelium leads to thickening of the intima and media of the vessel wall of large and medium-sized muscular arteries and large elastic arteries, such as the aorta, carotid, and iliac arteries. Flow-mediated dilatation of the brachial artery is one of several tests used to assess dysfunction of the endothelium using high resolution ultrasound. Endothelial dysfunction has been demonstrated in children with heterozygous familial hypercholesterolemia, type 1 diabetes, morbid obesity, and homozygous homocystinuria and in the offspring of a parent with early coronary disease. High resolution ultrasound has also confirmed postmortem findings that atherogenesis has its beginnings in childhood and adolescence, with the demonstration of increased carotid artery intima-medial thickening in children with familial hypercholesterolemia, familial combined hyperlipidemia, and type 1 diabetes and in the offspring of a parent with early coronary disease. In combination with family history and traditional risk factors, ultrasound evaluation of brachial artery flow-mediated vasodilation and carotid artery intima-medial thickening could be used in a clinical setting to assess coronary risk in high risk pediatric patients.
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PMID:Clinical review 168: What vascular ultrasound testing has revealed about pediatric atherogenesis, and a potential clinical role for ultrasound in pediatric risk assessment. 1524 May 74

Noninvasive assessment of vascular dysfunction in the pediatric population has taken advantage of the development of high-resolution ultrasound techniques. The most frequently used methods are the quantification of flow-mediated endothelium-dependent dilation of the brachial artery and measurement of the intima-media thickening of the carotid artery. Both reduced flow-mediated dilation and increased intima-media thickness have been proven to correlate with late cardiovascular events and/or mortality in adults. As these noninvasive methods can easily be applied in children, there have been recent investigations in high-risk pediatric patients harboring classical cardiovascular risk factors. Endothelial dysfunction and increased thickness of the intima media are currently observed in children with familial hypercholesterolemia, obesity, and type 1 diabetes mellitus. The association of early vascular dysfunction with a known risk factor is an important issue as these anomalies precede the formation of atherosclerotic plaques. Therefore, they may help in stratification of the risk for cardiovascular event and to better tailor therapeutic interventions in at risk children. Finally, these methods have been applied in specific pediatric populations, such as children with end-stage renal disease, chronic parenteral nutrition, HIV infection, and coarctation of the aorta. In these conditions, endothelial dysfunction and vascular remodeling are also present early in life and these data raise new possibilities in the understanding of the pathogenesis of atherosclerosis in these populations.
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PMID:Noninvasive assessment of arterial stiffness and risk of atherosclerotic events in children. 1605 29

Endothelial dysfunction is a characteristic finding in both patients with type 1 diabetes and in regular smokers and is an important precursor to atherosclerosis. The urate molecule has antioxidant properties, which could influence endothelial function. The impact of acutely raising uric acid concentrations on endothelial function was studied in eight men with type 1 diabetes, eight healthy regular smokers, and eight age-matched healthy control subjects in a randomized, four-way, double-blind, placebo-controlled study. Subjects received 1,000 mg uric acid i.v. in vehicle, 1,000 mg vitamin C as a control antioxidant, vehicle alone, or 0.9% saline on separate occasions over 1 h. Forearm blood flow responses to intrabrachial acetylcholine and sodium nitroprusside were assessed using venous occlusion plethysmography. Responses to acetylcholine, but not sodium nitroprusside, were impaired in patients with diabetes (P < 0.001) and in smokers (P < 0.005) compared with control subjects. Administration of uric acid and vitamin C selectively improved acetylcholine responses in patients with type 1 diabetes (P < 0.01) and in regular smokers (P < 0.05). Uric acid administration improved endothelial function in the forearm vascular bed of patients with type 1 diabetes and smokers, suggesting that high uric acid concentrations in vivo might serve a protective role in these and other conditions associated with increased cardiovascular risk.
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PMID:Uric acid restores endothelial function in patients with type 1 diabetes and regular smokers. 1706 52


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