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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Diabetic nephropathy (DN) is a common complication of diabetes types 1 and 2. One of the hallmarks of DN is the development of mesangial expansion, which occurs through accumulation of extracellular matrix (ECM) components. Altered local gene expression of humoral factors (eg, transforming growth factor-b, connective tissue growth factor, and platelet-derived growth factor) can lead to increased production of ECM components (eg, fibronectin and collagen IV) or decreased degradation through matrix metalloproteinases (eg, MMP-1, MMP-2). In recent years, new techniques for examination of gene expression have been developed. Because of their large scale and high-throughput character, it is now possible to examine differential gene expression in a large number of samples. This paper provides an overview of techniques used and results obtained in studies of DN. Newly developed concepts of how altered gene expression may affect histomorphologic features or clinical symptoms are also discussed.
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PMID:Gene expression in diabetic nephropathy. 1553 12

In the diabetic kidney, clinical as well as experimental observations have shown an upregulation of growth factors such as PDGF. These studies, however, were not designed to address whether upregulation of PDGF is merely a manifestation of diabetic renal injury or whether PDGF plays an active role in the pathophysiology of diabetic nephropathy. The objectives of this study were first to assess whether PDGF-dependent pathways are involved in the development of diabetic nephropathy and second to determine the effects of PDGF receptor antagonism on this disorder and associated molecular and cellular processes. This study used the diabetic apolipoprotein E-knockout (apoE-KO) mouse, a recently described model of accelerated diabetic nephropathy. Diabetes was induced by injection of streptozotocin in 6-wk-old apoE-KO mice. Diabetic animals received treatment with a tyrosine kinase inhibitor that inhibits PDGF action, imatinib (STI-571, 10 mg/kg per d orally) or no treatment for 20 wk. Nondiabetic apoE-KO mice served as controls. This model of accelerated renal disease with albuminuria as well as glomerular and tubulointerstitial injury was associated with increased renal expression of PDGF-B, proliferating cells, and alpha-smooth muscle actin-positive cells. Furthermore, there was increased accumulation of type I and type IV collagen as well as macrophage infiltration. Imatinib treatment ameliorated both renal functional and structural parameters of diabetes as well as overexpression of a number of growth factors, collagens, proliferating cells, alpha-smooth muscle actin-positive cells, and macrophage infiltration within the kidney. Tyrosine kinase inhibition with imatinib seems to retard the development of experimental diabetic nephropathy.
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PMID:Imatinib attenuates diabetic nephropathy in apolipoprotein E-knockout mice. 1562 75

Colorectal cancer is a major public health problem, being the second most common cause of cancer in developed countries. Several epidemiological studies have reported moderately increased risks of colorectal cancer in diabetic patients compared with general population. However, the underlying molecular link between diabetes and colorectal cancer remains to be elucidated. In diabetes mellitus, the formation and accumulation of advanced glycation end products (AGEs) progress. There is a growing body of evidence to show that AGEs-their receptor (RAGE) interactions are involved in the development of atherosclerosis and diabetic microangiopathy. AGEs-RAGE interactions stimulated the growth of human pancreatic cancer cells through the autocrine induction of platelet-derived growth factor-B. Furthermore, we have recently found that AGEs stimulated the growth and migration of cultured human melanoma cells and that anti-RAGE antibodies inhibited tumor formation and lung metastasis of melanoma cell xenografts and subsequently improved survival in athymic mice. These observations let us to hypothesize that AGEs could explain the molecular link between diabetes and colorectal cancer. In this paper, we would like to propose the possible ways of testing our hypotheses. Is elevation of serum AGE levels a risk factor for colorectal cancer in patients with diabetes? Does treatment with metformin, which has a potential effect on the inhibition of glycation reactions in vivo, decrease the risk for colorecetal cancer in diabetic patients? If the answer is yes, is this beneficial effect of metformin superior to that of other anti-diabetic agents with equihypoglycemic properties? Does treatment with pyridoxamine, a post-Amadori inhibitor (so-called Amadorins) of AGE formation, reduce the risk for colorectal cancer as well? Furthermore, are increased levels of AGEs and RAGE in colorectal cancer associated with poor prognosis in patients with diabetes? These clinical studies could clarify whether the AGEs-RAGE interactions serve as a causal link between diabetes and colorectal cancer.
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PMID:Possible participation of advanced glycation end products in the pathogenesis of colorectal cancer in diabetic patients. 1582 19

Diabetic retinopathy develops in patients with both type 1 and type 2 diabetes and is the major cause of vision loss and blindness in the working population. In diabetes, damage to the retina occurs in the vasculature, neurons and glia resulting in pathological angiogenesis, vascular leakage and a loss in retinal function. The renin-angiotensin system is a causative factor in diabetic microvascular complications inducing a variety of tissue responses including vasoconstriction, inflammation, oxidative stress, cell hypertrophy and proliferation, angiogenesis and fibrosis. All components of the renin-angiotensin system including the angiotensin type 1 and angiotensin type 2 receptors have been identified in the retina of humans and rodents. There is evidence from both clinical and experimental models of diabetic retinopathy and hypoxic-induced retinal angiogenesis that the renin-angiotensin system is up-regulated. In these situations, retinal dysfunction has been linked to angiotensin-mediated induction of growth factors including vascular endothelial growth factor, platelet-derived growth factor and connective tissue growth factor. Evidence to date indicates that blockade of the renin-angiotensin system can confer retinoprotection in experimental models of diabetic retinopathy and ischemic retinopathy. This review examines the role of the renin-angiotensin system in diabetic retinopathy and the potential of its blockade as a treatment strategy for this vision-threatening disease.
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PMID:Angiotensin and diabetic retinopathy. 1616 93

Leprechaunism features a clinical constellation characterized by extreme insulin resistance, growth retardation, and several distinct developmental abnormalities. One puzzling observation about leprechaunism is that mutations in the insulin receptor gene frequently associated with this syndrome cannot account for the aberrant responses of cultured cells to other growth factors. Here we report that the generation of reactive oxygen species (ROS) is impaired in cells from leprechaunism patients, thus shedding new light on this issue. Stimulation of patients' skin fibroblast cells with platelet-derived growth factor (PDGF) resulted in a lower-level tyrosine phosphorylation of cytosolic proteins compared with that seen in normal cells. In addition, consistent with the hypothesis that ROS mediate the level of tyrosine phosphorylation of cytosolic proteins through inactivation of protein tyrosine phosphatases (PTPases), patient fibroblast cells showed a significantly higher phosphatase activity than normal cells. We further showed that the lower-level tyrosine phosphorylation in response to growth factors results from the downregulation of an NADPH oxidase, Nox4, which in turn results in the reduction of ROS generation. Ectopic expression of Nox4 in the patient fibroblast cells consistently restored PDGF-induced ROS production and regulation of PTPase activities. Taken together, these data provide insight into the mechanisms through which growth retardation is associated with leprechaunism syndrome.
Diabetes 2005 Nov
PMID:Impaired generation of reactive oxygen species in leprechaunism through downregulation of Nox4. 1624 42

Diabetes mellitus is associated with an increased risk of vascular disease, with significant alterations in systemic endothelial progenitor cells (EPCs) and peripheral vascular function. To identify the contribution of the different vascular compartments in the diabetic impairment of vascularization, we employed streptozotocin- and control-treated 3-mo-old C57Bl/6 mice in an isogeneic pinnal cardiac allograft model, revealing a significant delay in vascularization of wild-type cardiac tissue transplanted into diabetic mice. To investigate the basis of this impairment, the function of diabetic bone marrow cells was tested by transplantation of bone marrow cells isolated from diabetic and control mice into intact, unirradiated 18-mo-old C57Bl/6 mice, which have impaired function of both EPCs and peripheral endothelial cells. Importantly, cells derived from control, but not diabetic, bone marrow integrated into transplanted cardiac allografts. To assess the contribution of diabetic changes in the local vasculature, diabetic mice were treated with pinnal injections of platelet-derived growth factor (PDGF)-AB, which promotes cardiac angiogenesis in wild-type mice. However, whereas PDGF-AB enhanced allograft function in control mice, the activity of the cardiac transplants in the PDGF-AB-treated diabetic mice was significantly decreased. To decipher the potential interactions between systemic bone marrow-derived cells and local vascular pathways, diabetic mice were transplanted with wild-type bone marrow cells with or without PDGF-AB pinnal pretreatment, resulting in improved allograft function and donor cell recruitment only in the combination treatment arm. Overall, these studies show that the diabetic impairment in cardiac angiogenesis can be reversed by targeting the synergism between local trophic pathways and systemic cell function.
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PMID:Synergistic targeting with bone marrow-derived cells and PDGF improves diabetic vascular function. 1633 36

While diabetes mellitus is most often associated with hypertension, dyslipidemia, and obesity, these factors do not fully account for the increased burden of cardiovascular disease in patients with the disease. This strengthens the need for comprehensive studies investigating the underlying mechanisms mediating diabetic cardiovascular disease and, more specifically, diabetes-associated atherosclerosis. In addition to the recognized metabolic abnormalities associated with diabetes mellitus, upregulation of putative pathological pathways such as advanced glycation end products, the renin-angiotensin system, oxidative stress, and increased expression of growth factors and cytokines have been shown to play a causal role in atherosclerotic plaque formation and may explain the increased risk of macrovascular complications. This review discusses the methods used to assess the development of atherosclerosis in the clinic as well as addressing novel biomarkers of atherosclerosis, such as low-density lipoprotein receptor-1. Experimental models of diabetes-associated atherosclerosis are discussed, such as the streptozocin-induced diabetic apolipoprotein E knockout mouse. Results of major clinical trials with inhibitors of putative atherosclerotic pathways are presented. Other topics covered include the role of HMG-CoA reductase inhibitors and fibric acid derivatives with respect to their lipid-altering ability, as well as their emerging pleiotropic anti-atherogenic actions; the effect of inhibiting the renin-angiotensin system by either ACE inhibition or angiotensin II receptor antagonism; the effect of glycemic control and, in particular, the promising role of thiazolidinediones with respect to their direct anti-atherogenic actions; and newly emerging mediators of diabetes-associated atherosclerosis, such as advanced glycation end products, vascular endothelial growth factor and platelet-derived growth factor. Overall, this review aims to highlight the observation that various pathways, both independently and in concert, appear to contribute toward the pathology of diabetes-associated atherosclerosis. Furthermore, it reflects the need for combination therapy to combat this disease.
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PMID:Diabetes mellitus-associated atherosclerosis: mechanisms involved and potential for pharmacological invention. 1648 46

The incidence of diabetes is increasing at an alarming rate to the point where it is becoming an epidemic. An ageing population, sedentary lifestyle and an unhealthy diet are considered to have contributed toward this. What we must now consider is not only the burden of the disease but the complications that arise from diabetes, in particular kidney and heart disease. Foremost, more than half of the diabetic population will die from cardiovascular-related causes. Whilst diabetes is most often associated with hypertension, dyslipidaemia and obesity, these factors do not fully account for the increased burden of cardiovascular disease in people with diabetes. This strengthens the need for comprehensive studies investigating the underlying mechanisms mediating diabetic cardiovascular disease, and more specifically, diabetes-associated atherosclerosis. In addition to the recognised metabolic abnormalities associated with diabetes, upregulation of putative pathological pathways such as advanced glycation endproducts, renin-angiotensin system, oxidative stress and increased expression of growth factors and cytokines have been observed in the setting of diabetes. All of these have been shown to play a causal role in atherosclerotic plaque formation and thus may explain the increased risk of macrovascular complications in those patients with diabetes. In this review the effect of inhibiting the renin-angiotensin system with angiotensin converting enzyme inhibition and a comparison to angiotensin II receptor antagonism is discussed, with the results of clinical trails reflecting the more recently discovered, non-haemodynamic, proatherogenic actions of angiotensin II. The need for experimental models of diabetes-associated atherosclerosis will be covered, with particular emphasis given to the streptozotocin-diabetic apolipoprotein E knockout mouse. Finally, growth factors, including vascular endothelial growth factor and platelet-derived growth factor are discussed in detail.
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PMID:Preventing atherosclerosis with angiotensin-converting enzyme inhibitors: emphasis on diabetic atherosclerosis. 1650 70

Normal blood microvessels are lined by pericytes, which contribute to microvessel development and stability through mechanisms that are poorly understood. Pericyte deficiency has been implicated in the pathogenesis of microvascular abnormalities associated with diabetes and tumors. However, the unambiguous identification of pericytes is still a problem because of cellular heterogeneity and few available molecular markers. Here we describe an approach to identify pericyte markers based on transcription profiling of pericyte-deficient brain microvessels isolated from platelet-derived growth factor (PDGF-B)-/- and PDGF beta receptor (PDGFRbeta)-/- mouse mutants. The approach was validated by the identification of known pericyte markers among the most down-regulated genes in PDGF-B-/- and PDGFRbeta-/- microvessels. Of candidates for novel pericyte markers, we selected ATP-sensitive potassium-channel Kir6.1 (also known as Kcnj8) and sulfonylurea receptor 2, (SUR2, also known as Abcc9), both part of the same channel complex, as well as delta homologue 1 (DLK1) for in situ hybridization, which demonstrated their specific expression in brain pericytes of mouse embryos. We also show that Kir6.1 is highly expressed in pericytes in brain but undetectable in pericytes in skin and heart. The three new brain pericyte markers are signaling molecules implicated in ion transport and intercellular signaling, potentially opening new windows on pericyte function in brain microvessels.
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PMID:Microarray analysis of blood microvessels from PDGF-B and PDGF-Rbeta mutant mice identifies novel markers for brain pericytes. 1680 74

Angiogenesis impairment in hyperglycemic patients represents a leading cause of severe vascular complications of both type-1 and -2 diabetes mellitus (DM). Angiogenesis dysfunction in DM is related to glycemic control; however, molecular mechanisms involved are still unclear. Fibroblast growth factor-2 (FGF-2) is a potent angiogenic factor and, according to previous evidence, may represent a key target of molecular modifications triggered by high-sugar exposure. Therefore, the purpose of this study was to investigate whether short incubation with hyperglycemic levels of glucose affected FGF-2 and whether glucose-modified FGF-2 was detectable in vivo. Biochemical analyses carried out with SDS-PAGE, fluorescence emission, mass-spectrometry, immunoblot, and competitive ELISA experiments demonstrated that human FGF-2 undergoes a rapid and specific glycation upon 12.5-50 mm glucose exposure. In addition, FGF-2 exposed for 30 min to 12.5 mm glucose lost mitogenic and chemotactic activity in a time- and dose-dependent manner. Under similar conditions, binding affinity to FGF receptor 1 was dramatically reduced by 20-fold, as well as FGF receptor 1 and ERK-1/2 phosphorylation, and FGF-2 lost about 45% of angiogenic activity in two different in vivo angiogenic (Matrigel and chorioallantoic-membrane) assays. Such glucose-induced modification was specific, because other angiogenic growth factors, namely platelet-derived growth factor BB and placental-derived growth factor were not significantly or markedly less modified. Finally, for the first time, glycated-FGF-2 was detected in vivo, in tissues from hyperglycemic nonobese diabetic mice, in significantly higher amounts than in normoglycemic mice. In conclusion, hyperglycemic levels of glucose may strongly affect FGF-2 structure and impair its angiogenic features, and endogenous glycated-FGF-2 is present in diabetic mice, indicating a novel pathogenetic mechanism underlying angiogenesis defects in DM.
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PMID:Glycated fibroblast growth factor-2 is quickly produced in vitro upon low-millimolar glucose treatment and detected in vivo in diabetic mice. 1684 May 37


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