Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We examined the effect of aldehyde-modified matrix macromolecules on mesangial cell function in vitro, using incubated rat glomerular mesangial cells. Laminin and fibronectin were modified by incubation for 24 h with 50 mM glycolaldehyde (GA), a highly reactive cross-linking glycation product, with or without equimolar aminoguanidine. GA-modified laminin and fibronectin caused marked inhibition of cell adhesion. Cell spreading was reduced on the GA-modified laminin. In contrast, the GA-modified fibronectin had no effect on cell spreading. The study of thymidine incorporation by mesangial cells showed that the GA-modified fibronectin had a diminished mitogenic activity against cells. The content of advanced glycation end-product (AGE), which was determined by fluorescence at 370 nm excitation and 440 nm emission wavelength, increased and intermolecular cross-links appeared in the GA-modified proteins. To a large extent, aminoguanidine restored the structural alterations and functional deteriorations described above. We conclude that GA-modified matrix proteins diminish their functional properties against mesangial cells and affect cellular functions.
Diabetes Res Clin Pract 1994 Feb
PMID:Effects of aldehyde-modified proteins on mesangial cell-matrix interaction. 801 60

To explore the possibility that the excretion of urinary fibronectin degradation products (U-FnDP) can be an indicator of the progression of diabetic nephropathy, U-FnDP and urinary protein(U-P) were determined in 64 diabetic patients and 11 healthy volunteers. Moreover, to determine whether continuous subcutaneous heparin infusion (CSHI) reduces elevated U-FnDP and U-P in diabetic patients with persistent proteinuria, heparin sodium was administered as a bolus subcutaneous injection of 5000 IU, followed by subcutaneous infusion of 250 IU/kg per 24 h heparin sodium for 7 days. U-FnDP excretion rate elevated proportionally to the degree of U-P. CSHI reduced significantly elevated U-FnDP from 172.68 +/- 15.79 to 100.04 +/- 14.93 micrograms/24 h (P < 0.01) and U-P from 1.76 +/- 0.13 to 1.20 +/- 0.12 g/24 h (P < 0.01). No significant changes in blood pressure and diurnal mean plasma glucose levels were found. APTT was prolonged with a decrease of AT-III activity during the treatment. These findings suggest that U-FnDP can be one of the indicators which reflects the degree of progression of diabetic nephropathy, and that CSHI may be useful for the normalization of elevated U-FnDP and reduction in U-P in diabetic nephropathy.
Diabetes Res Clin Pract 1993 Jul
PMID:Relationship between urinary excretion of fibronectin degradation products and proteinuria in diabetic patients, and their suppression after continuous subcutaneous heparin infusion. 825 24

Retinal capillaries are composed of endothelial cells resting on a basement membrane, in which are embedded pericytes. In diabetes mellitus, the basement membrane becomes thickened, and there is a loss of pericytes. The relative contributions of endothelial cells and pericytes to the synthesis of extracellular matrix proteins which are components of the basement membrane are not well-characterized. To determine how a selective loss of pericytes might affect the composition of retinal capillary basement membranes, we used primary cultures of bovine retinal capillary endothelial cells and pericytes to determine the forms and quantify the amounts of laminin and fibronectin synthesized and secreted by these cell types as well as to determine how high glucose concentrations alter these parameters. Results of ELISAs showed that pericyte cell/matrix layers contained nearly ten times more fibronectin than endothelial cells (288 +/- 24 vs. 34 +/- 5 ng micrograms-1 DNA, P < 0.001), but the amounts of laminin were similar. D-glucose (40 mM) tripled the amount of fibronectin incorporated into the endothelial cell/matrix layer (102 +/- 4 vs. 34 +/- 5 ng micrograms-1 DNA, P < 0.05), but had a lesser effect on pericytes. The non-metabolizable analogue L-glucose, also increased the amount of fibronectin incorporated in both pericyte and endothelial cell/matrix layers. The effects of D- and L-glucose on fibronectin secreted into the medium by both cell types were similar to the effects on incorporation of fibronectin into cell/matrix layers. Glucose had no effect on laminin synthesis. [35S]methionine radiolabeling and immunoprecipitation showed that pericytes and endothelial cells synthesize different forms of fibronectin. Both pericytes and endothelial cells synthesized an A and two B chains of laminin which were of similar apparent size, but the two cell types post-translationally modified the subunits differently. We conclude that pericytes and endothelial cells may contribute different forms and amounts of fibronectin and laminin to the retinal capillary basement membrane, so the preferential loss of pericytes in diabetes could result in basement membrane abnormalities which might lead to endothelial cell dysfunction.
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PMID:Regulation of fibronectin and laminin synthesis by retinal capillary endothelial cells and pericytes in vitro. 828 48

In view of the importance of mesangial extracellular matrix (ECM) accumulation in the pathogenesis of diabetic glomerulosclerosis, we investigated 1) the effects of high glucose on ECM production by rat glomerular mesangial cells in culture (study A) and 2) the mechanisms underlying these effects, particularly the role of high sugar levels irrespective of intracellular metabolism (study B1) and of excess glucose disposal via the polyol pathway and associated biochemical alterations (study B2). Cells were cultured for 4 weeks, through six to eight passages, under the experimental conditions indicated below and, at each passage, the levels of fibronectin (FN), laminin (LAM), and collagen types I (C-I), III (C-III), IV (C-IV), and VI (C-VI) in media and cell extracts were quantified by an enzyme immunoassay. In study A, medium and cell content of matrix were assessed, together with [3H]leucine and [3H]thymidine incorporation into monolayers, polyol, fructose, and myo-inositol levels and the cytosolic redox state, in cells grown in high (30 mM) D-glucose or iso-osmolar mannitol versus cells cultured in normal (5.5 mM) D-glucose. FN, LAM, C-IV, and C-VI accumulation, but not C-I and C-III accumulation, was increased by 30 mM glucose, but not by iso-osmolar mannitol, when compared with 5.5 mM glucose, starting at week 2 and, except for C-VI, persisting throughout the remaining 2 weeks, whereas no change was observed in the measured indexes of total protein synthesis and DNA synthesis/cell proliferation. At any time point, polyol levels were increased, whereas myo-inositol was reduced by high glucose; in cells grown under elevated glucose concentrations, the lactate/pyruvate (L/P) ratio, an index of the cytosolic redox state, progressively increased. In study B1, the effects of high D-glucose were compared with those of iso-osmolar concentrations of sugars that are partly or not metabolized but are capable of inducing nonenzymatic glycosylation, such as D-galactose and L-glucose, and of mannitol, which does not enter the cell. Both D-galactose and L-glucose, but not mannitol, partly mimicked D-glucose-induced ECM overproduction. Although D-galactose is metabolized via the polyol pathway and alters the cytosolic redox state, ECM changes induced by high galactose were not prevented by the use of an aldose reductase inhibitor (ARI), Alcon 1576 (14 microM).(ABSTRACT TRUNCATED AT 400 WORDS)
Diabetes 1994 Mar
PMID:Mechanisms of glucose-enhanced extracellular matrix accumulation in rat glomerular mesangial cells. 831 22

Decreased wound healing and increased infection are major problems in patients with diabetes mellitus. Fibronectin plays a fundamental role in wound healing and acts as an opsonin for the phagocytosis of foreign antigens. The aim of this study was to ascertain the functional activity of plasma fibronectin from patients with diabetes mellitus. Initially, a modified Boyden chamber technique was used to measure cell migration on fibronectin purified from patient's plasma and an enzyme-linked immunosorbent assay was used to measure the binding of gelatin. A sandwich assay was developed that enabled the capture of fibronectin directly from patient's plasma without prior purification. With the use of a 96-well format, the binding of two different monoclonal antibodies could be compared simultaneously with the binding of gelatin and cell adhesion. In this way, differences in the function of particular domains of fibronectin from diabetic patients and control subjects could be measured. Results showed no difference between fibronectin from diabetic patients and control subjects with respect to the monoclonal antibodies binding in 1) the cell adhesion domain and 2) the heparin-binding domain. Furthermore, no detectable differences were noted with respect to cell adhesion, cell migration, or gelatin binding. These results suggest that diabetic patients receiving insulin treatment show no modulation of plasma fibronectin function, despite raised levels of circulating glucose.
Diabetes 1993 Nov
PMID:Functional activity of plasma fibronectin in patients with diabetes mellitus. 840 2

The nature of the process leading to the acellular nonperfused capillaries of diabetic microangiopathy remains unknown. Because these capillaries manifest thickened basement membranes, we asked whether the process causing deposition of excess extracellular matrix in diabetes modifies cell-matrix interactions in a direction that would compromise cell renewal. In 44 individual isolates of human umbilical vein endothelial cells we observed that high glucose concentrations (30 mM) induce coordinate increases in the levels of mRNAs encoding fibronectin and the fibronectin-specific integrin receptor alpha 5 beta 1 as well as in the cognate proteins. Expression of the integrin subunit alpha 3, component of the alpha 3 beta 1 polyspecific receptor for fibronectin, laminin, and collagen, was also up-regulated by high glucose. Overexpression of integrins correlated with increased cell attachment to exogenous fibronectin and laminin as well as to complex matrix. Moreover, cells exhibited firmer steady-state adhesion to their own matrix. To correlate these in vitro observations with events in human diabetic retinopathy we measured integrin levels in retinal trypsin digests prepared from 10 patients with 8.2 +/- 1.6 (mean +/- SE) years of diabetes and 10 age- and sex-matched nondiabetic controls. Microvessels of diabetic patients showed increased immunostaining for beta 1 integrin (P = 0.025) when compared with control microvessels. These data show that high glucose and diabetes increase integrin expression and thus alter the interaction of vascular endothelial cells with their basement membranes in the direction of firmer cell-matrix adhesion. This could compromise the migration and replication critical to the reendothelialization process and contribute to microvascular occlusion.
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PMID:Integrin overexpression induced by high glucose and by human diabetes: potential pathway to cell dysfunction in diabetic microangiopathy. 841 54

The fibronectin content of RMC cultures grown for 8-14 days in medium containing 30 mM (540 mg/dl) D-glucose was increased 30-60% relative to that of control cells cultured in 10 mM (180 mg/dl) glucose. Addition of equiosmolar concentrations (20 mM, 360 mg/dl) of L-glucose, 3-O-methylglucose, or mannitol to 10 mM glucose media did not alter fibronectin accumulation compared with values observed in 10 mM glucose alone. The basal phosphorylation of the 80,000-M(r) MARKS protein, which is a substrate for PKC, and the phosphorylation induced by acute (15-min) exposure of cells to 15% FCS or to 0.1 microM (50 ng/ml) PDBu were all increased in cells grown in 30 mM compared with 10 mM glucose. By contrast, phosphorylation of the 80,000-M(r) protein in response to a maximal concentration of PDBu (1 microM, 500 ng/ml) was not different in cells grown in 30 mM compared with 10 mM glucose. The acute increases in phosphorylation of the 80,000-M(r) protein were blocked by the PKC inhibitor calphostin C. Chronic (7-day) exposure of mesangial cells grown in 10 mM glucose to 0.1 microM of the PKC agonist PDBu also resulted in a sustained 40% increase in 80,000-M(r) phosphorylation and a 20-30% increase in fibronectin accumulation. As assessed by [35S]methionine incorporation, mesangial cell fibronectin synthesis was increased by exposure to PDBu, a finding consistent with earlier observations with 30 mM glucose.(ABSTRACT TRUNCATED AT 250 WORDS)
Diabetes 1993 Jan
PMID:Role for protein kinase C in the mediation of increased fibronectin accumulation by mesangial cells grown in high-glucose medium. 842 Aug 8

Immunochemical and metabolic radiolabeling procedures revealed that homogeneous cultures of calf glomerular epithelial, endothelial, and mesangial cells actively synthesize type IV collagen (primarily as alpha 1 (IV)3) which is secreted into the medium and incorporated into the extracellular matrix. Exposure of confluent cultures of the three cell types to a high glucose concentration (30 mM) for 60 h resulted in a pronounced increase (two- to threefold) in type IV collagen production over that observed at a physiological level (5 mM) of this sugar, as determined by either immunoblotting or fluorography of electrophoretically separated media or cell-matrix components. The elevated glucose did not bring about a change in the rate of cell proliferation or fibronectin production. Moreover, studies with mannitol indicated that the stimulation of type IV collagen synthesis was not a function of hyperosmolarity. In contrast to the glomerular cells, glucose-induced enhancement of formation of this collagen was not observed in 3T3 cells despite a substantial acceleration in the consumption of this sugar. Time studies indicated that the response of the glomerular cells to high glucose occurs over an extended period (maximal at approximately 78 h) and, furthermore, that the stimulatory effect on type IV collagen production is only slowly reversed after restoration of the glucose to a normal level. We believe that these findings are relevant to an understanding of the sequence of events that lead to the development of diabetic glomerular lesions.
Diabetes 1993 Jan
PMID:Effect of high glucose on type IV collagen production by cultured glomerular epithelial, endothelial, and mesangial cells. 842 Aug 14

Like the renal glomerular mesangium in patients with diabetic nephropathy, glomerular mesangial cell cultures grown in 30 mM glucose accumulate increased amounts of the extracellular matrix (ECM) proteins fibronectin, laminin, and type IV collagen. This is due to increased ECM protein synthesis and mRNA levels. Similar to other cells types that are affected by the diabetic state (such as, vascular cells and peripheral nerve), mesangial cells transport glucose by an insulin-independent, facilitated diffusion transport system. Kinetic studies reveal that intracellular glucose levels may reach the ambient glucose concentrations achieved in diabetes. Growth studies reveal that glucose does not exert its effect on mesangial cell ECM accumulation by affecting cell growth, but rather it causes an increase in diacylglycerol (DAG) mass and activates protein kinase C. Agents such as phorbol myristate acetate (PMA) and the cell permeable DAG analogue, oleoyl acetyl glycerol (OAG) which activate protein kinase C also increase ECM mRNAs. These results implicate protein kinase C activation in the increased ECM accumulation observed in mesangial cell cultures grown in high glucose.
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PMID:The glomerular mesangium in diabetes mellitus. 843 49

Diabetic cardiomyopathy, a condition characterized by the accumulation of carbohydrate-containing material surrounding the myocardial small blood vessels, has been studied in alloxan-diabetic normotensive and hypertensive rats. Immunochemical techniques were used to monitor several extracellular matrix constituents present in extracts of cardiac tissue, namely types I, IV and VI collagen, laminin and fibronectin, as well as myosin. These studies have indicated that after induction of diabetes, type VI collagen but none of the other matrix components studied, was significantly increased (from 2.29 +/- 0.04 mg/g in normal to 2.85 +/- 0.18 mg/g in diabetic ventricles, p < 0.01). Hypertension, whether induced by the clipping of one renal artery or genetically determined (spontaneously hypertensive rats), resulted in a similar elevation in type VI collagen (2.71 +/- 0.12 mg/g, p < 0.005 compared to normal rats). In the presence of diabetes plus hypertension the effect was not additive, the type VI collagen level being 2.93 +/- 0.15 (p < 0.001 compared to normal rats). Basement membrane collagen (type IV) in the myocardium appeared to be unaffected by diabetes or hypertension and the myosin contents of the hearts of the four experimental groups were similar. Quantitative determinations indicate that compared to type IV collagen, laminin or fibronectin, type VI collagen represents the major periodic acid-Schiff-reactive extracellular constituent of the rat ventricle. Its preferential increase in the heart in diabetes may provide insight into the molecular mechanisms of the diabetic microvascular disease.
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PMID:Increased rat myocardial type VI collagen in diabetes mellitus and hypertension. 845 34


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