Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Vanadate (sodium orthovanadate) is an insulin-mimetic agent and phosphotyrosine phosphatase inhibitor that has been proposed as a potential therapeutic agent for diabetes. We previously reported that vanadate decreased the number of cell-surface insulin receptors but inhibited receptor degradation in cultured lymphocytes (IM-9) (1). To determine whether vanadate affected receptors without intrinsic tyrosine kinase activity, its effects on LDL and transferrin receptors and their ligands were examined. Vanadate exposure resulted in a dose- and time-dependent decrease in LDL binding to cultured human fibroblasts associated with a decrease in cell surface receptor number while total solubilized cell LDL receptors increased. Vanadate also inhibited the LDL-mediated downregulation of total cellular LDL receptors in the absence and presence of cycloheximide consistent with an inhibition of LDL receptor degradation. In the case of the ligand, vanadate augmented the accumulation of intact 125I-LDL associated with an inhibition of up to 80% of the ability of LDL to decrease cholesterol synthesis. Since these actions were similar to the effects of lysosomotropic agents, we examined the effect of vanadate on intraendosomal pH using the fluorescent probe acridine orange. In contrast with chloroquine and NH4Cl, vanadate did not neutralize the pH of the acidic intracellular compartment. Furthermore, after a transient insulin-like effect, chronic exposure to vanadate diminished 125I-diferric transferrin binding to rat adipocytes. In contrast with the inhibitory action of NH4Cl, intracellular 59Fe uptake remained unaffected and was proportional to cell-surface binding capacity in the presence of vanadate. These data demonstrate a chronic effect of vanadate to promote the accumulation of intracellular receptors and to inhibit ligand and receptor degradation. The latter effect is not mediated by pH changes, appears to be localized to a late endosomal/lysosomal compartment, and suggests a possible role for tyrosine dephosphorylation in the regulation of receptor-ligand degradation.
Diabetes 1996 Aug
PMID:The insulin-mimetic agent vanadate promotes receptor endocytosis and inhibits intracellular ligand-receptor degradation by a mechanism distinct from the lysosomotropic agents. 869 Jan 56

In the nonobese diabetic mouse, insulin-dependent diabetes is an autoimmune disease characterized by T cell-mediated invasion and destruction of pancreatic islet beta cells. The importance of insulin receptor (IR) expression in the pathogenesis of diabetes was examined, since it has been shown that the IR is a chemotactic receptor capable of directing cell movement in response to insulin. Using polyclonal antisera to the IR, phenotypic analysis of purified splenic T cells from diabetic mice showed that about 15% of T cells expressed high density IR (IRhigh). In addition, IRhigh T cells were already a dominant phenotype in the insulitis of young prediabetic mice. To determine the ability of IRhigh T cells to transfer diabetes, cells were sorted by flow cytometry before adoptive transfer into young (6- to 8-wk-old) nondiabetic irradiated nonobese mice. Transfer of as few as 3 x 10(6) purified IRhigh T cells alone resulted in rapid onset of insulitis and diabetes, and IRhigh-depleted T cells were essentially unable to passage either insulitis or diabetes. The adoptive transfer of disease was not due to the transfer of activated cells, since removal of IL-2R+ or transferrin R+ cells did not alter diabetes transfer. Therefore, IRhigh T cells are aggressively diabetogenic, suggesting that increased IR expression may provide a mechanism for delivering potentially autoreactive T cells to the islet, regardless of their activation state.
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PMID:High density insulin receptor-positive T lymphocytes from nonobese diabetic mice transfer insulitis and diabetes. 887 75

About 30% of diabetic patients develop progressive renal failure. We studied albumin, IgG, and transferrin excretion during exercise in diabetic children without signs of nephropathy to investigate proteinuria under these conditions: 39 patients with insulin-dependent diabetes mellitus and 21 healthy children undertook a bicycle exercise test. Albuminuria measured by nephelometry was calculated as the albumin excretion rate (AER) and albumin-to-creatinine ratio before and after exercise. The diabetic group was divided into three subgroups according to disease duration (DI < 5 years, DII 5-10 years, DIII > 10 years). No significant difference in metabolic control (hemoglobin A1c was detected between the diabetic groups (median hemoglobin A1c: DI 7.2%, DII 7.6%, DIII 8.6%). There was no increase in AER in the healthy children after exercise. Before exercise the diabetic groups had an AER similar to controls. No significant increase in albuminuria after exercise was seen in group DI. Both groups with a disease duration of more than 5 years had a significant increase in albuminuria [median before/after: DII 7.8/16.7 (P < 0.05), DIII 0/57.9 (P < 0.05) micrograms/min per 1.73 m2). Of these patients, 43% also had a measurable urinary excretion of IgG and transferrin, indicating structural glomerular damage. There was no correlation of albuminuria and parameters of metabolic control or renal function. We conclude that in diabetic children an exercise test unveils albuminuria in certain patients, while their AER may be normal at rest.
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PMID:Postexercise albuminuria in children with different duration of type-1 diabetes mellitus. 889 63

Otsuka Long-Evans Tokushima Fatty (OLETF) rats have been established as an animal model in which non-insulin-dependent diabetes mellitus develops spontaneously. We examined the renal histopathology and the urinary findings serially in OLETF rats and compared these findings with findings in age-matched Long-Evans Tokushima Otsuka (LETO) rats as a control strain. OLETF rats showed higher blood glucose levels than did LETO rats from 18 weeks of age, and hemoglobin A1c levels became higher in OLETF rats than in LETO rats from 22 weeks of age. Accompanying the development of hyperglycemia was an increase in the amount of albuminuria in OLETF rats from 18 weeks of age. The initial histopathologic change found in OLETF rats was an increase in glomerular area, and mesangial expansion started to develop from 22 weeks of age. Mesangial lesions progressed to mesangial sclerosis, and exudative lesions were found in OLETF rats from 36 weeks of age. The anionic charge of glomerular basement membrane (GBM), measured by polyethyleneimine grain density, demonstrated that the lower grain density in OLETF rats when compared with that in LETO rats became more evident with an increase in the amount of albuminuria. Therefore, the defect in the charge-selective property found in OLETF rats might be one of the causes of albuminuria. The GBM became thickened in elderly OLETF rats as compared with that in age-matched LETO rats. Disturbances in the selectivity of urinary protein, as determined by the clearance ratio of immunoglobulin G to transferrin, were found to accompany the thickening of GBM in OLETF rats. We consider that both the loss of the charge-selective property and massive albuminuria might be the causes of GBM thickening, through a clogging mechanism, and that GBM thickening might in turn produce the loss of size selectivity. Given these findings, we consider the OLETF strain of rats to be an interesting animal model for studying the relationship between diabetes and renal involvement, because the glomerular abnormalities and massive albuminuria found in OLETF rats were results of a long-term diabetic state.
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PMID:Evaluation of glomerular lesion and abnormal urinary findings in OLETF rats resulting from a long-term diabetic state. 896 Jun 40

Primary hemochromatosis is characterized by a specific pattern of clinical manifestations. It includes liver disease with hepatomegaly, glucose intolerance, e.g. diabetes, hyperpigmentation oft the skin, impotence/ amenorrhea, arthropathy, cardiomyopathy and fatigue. Laboratory investigation reveals significantly elevated serum ferritin and transferrin saturation with iron. The diagnosis is confirmed by liver biopsy and quantitative determination of elevated liver iron content. Wilson's disease represents a copper storage disease. Prominent clinical features are hepatomegaly and splenomegaly. Neurological alterations and detection of Kayser-Fleischer corneal rings are typical. In the acute initial phase the often young patients present with Coombs-negative hemolysis. Psychiatric alterations, cardiomyopathy, arthropathy, nephropathy, as well as thrombocytopenia and leucopenia are other clinical features. Laboratory parameters of Wilson's disease include low serum ceruloplasmin and serum copper. There is an elevated urinary copper excretion and elevated serum free copper concentration. The diagnosis is confirmed by liver biopsy with quantitative determination of an elevated liver copper content.
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PMID:[Current diagnosis: hereditary metabolic diseases of the liver (primary hemochromatosis, Wilson disease)]. 898 78

Hereditary hemochromatosis (HHC) is an inherited disease transmitted in an autosomal recessive pattern. With homozygosity occurring in up to 0.5% of the population, HHC is the most prevalent genetic disease among the white population worldwide and has the same prevalence as the sickle cell trait in the African-American population. An asymptomatic 50-year-old white man presented at the family practice clinic and stated that HHC had been diagnosed in his mother. Laboratory findings showed markedly elevated transferrin saturation and ferritin levels. The diagnosis of HHC was made on the basis of the laboratory results and family history, and therapy was begun. Clinical manifestations of HHC occur late and include diabetes mellitus, cirrhosis, and cardiomyopathy. As end-organ damage is preventable, optimal management involves early diagnosis and lifelong phlebotomy. Diagnosis is made by an elevated transferrin saturation level and an increased serum ferritin value. Hereditary hemochromatosis is a genetic disorder of iron metabolism that has an excellent prognosis if diagnosed early.
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PMID:Hereditary hemochromatosis. 907 Dec 52

More negatively-charged proteins are harder to pass through the glomerular charge barrier (GCB) and to be reabsorbed by renal tubules. Although the glycation of albumin increases its negative charge compared to non-glycated albumin, the glycation of transferrin does not change its charge. This difference enabled us to examine the charge-dependent renal function in diabetic proteinuria. The percentage of urinary glycated transferrin (serum %G-transferrin) positively correlated with serum fructosamine concentrations and the percentage of serum glycated albumin (serum %G-albumin) in all subjects. Urinary concentrations of transferrin and beta 2-microglobulin strongly correlated in diabetic patients with microproteinuria, while no significant correlation was observed in subjects with diabetic macroproteinuria or non-diabetic proteinuria. Urine/serum (U/S) ratio of %G-albumin in the patients with diabetic proteinuria was significantly lower than that in subjects with non-diabetic proteinuria, while no difference of the U/S ratio of %G-transferrin was observed between any groups. Furthermore, U-%G-transferrin/U-%G-albumin ratio was highest in the diabetic patients with microproteinuria. These results lead to the conclusion that the initial damage in diabetic kidney causing microproteinuria starts with the dysfunction of charge-dependent tubular reabsorption prior to a loss of GCB.
Diabetes Res Clin Pract 1997 Apr
PMID:Damage of charge-dependent renal tubular reabsorption causes diabetic microproteinuria. 918 9

Transplantation of pancreatic islets in alginate polylysine microcapsules is a potential useful method for treating type I diabetes. In this study, the permeability for alginate-polylysine microcapsules to cytokines an immunoglobulines has been investigated by a newly developed method. Magnetic monodisperse polymer particles (Dynabeads) coated with antibodies against selected proteins were encapsulated in 0.7 mm alginate polylysine microcapsules. The capsule membrane permeability to IgG (150 kDa), Transferrin (81 kDa), Tumor necrosis factor (TNF, 51 kDa), Interleukin-1 beta (IL-1 beta, 17.5 kDa), and insulin (5.8 kDa) was estimated by measuring the binding of 125I-labeled proteins to the encapsulated antibody coated Dynabeads. Capsules with an inhomogeneous solid gel core were made of alginates with high guluronic or high mannuronic acid content and poly-L (PLL)- or poly-D-lysine (PDL) of concentrations varied from 0.05-0.2%. The various capsules examined were all impermeable to IgG. The capsules made with a PLL-, but not PDL-membranes were permeable for transferrin. IL-1 beta was found to penetrate all of the different capsule types. The high-G capsules, however, could be made impermeable to TNF and still allowed transferrin to pass. The permeability of these capsules to IL-1 beta, but not to TNF was confirmed in an assay where mouse islets of Langerhans were incubated with TNF and IL-1 beta, and comparing the IL-6 for encapsulated and non-encapsulated islets.
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PMID:Alginate polylysine microcapsules as immune barrier: permeability of cytokines and immunoglobulins over the capsule membrane. 925 12

Chronic mild liver enzyme abnormalities are attributable to hereditary hemochromatosis in at least 3% of cases. Hemochromatosis formerly was diagnosed late with diabetes and hepatic and cardiac failure. Only recently have the autosomal recessive inheritance and subtle early presentations been understood. However, patients still wait many years and see many physicians before receiving a correct diagnosis. Increased serum transferrin saturation is currently the best test for detection of those likely to accumulate iron. Serum ferritin identifies those requiring treatment. When liver biopsy (controversial in asymptomatic individuals) is indicated, chemical measurement of liver iron content is helpful and therapeutic phlebotomy is the only effective treatment. Caucasian-type hemochromatosis (prevalence of 0.005) is associated with genetic abnormalities in HLA-H but also occurs in other ethnic groups. Those of African descent may have a different but also heritable iron-loading disease. Caucasian-type and to a lesser extent African iron loading are detectable early by laboratory testing. Early treatment restores normal expectations of length and quality of life in the Caucasian disease. Long-term treatment data are not yet available in African iron loading. Laboratory-initiated screening programs using unsaturated iron-binding capacity can eliminate symptomatic hemochromatosis.
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PMID:Mild liver enzyme abnormalities: eliminating hemochromatosis as cause. 926 5

The effect of Tri-iodothyronine (T3) administration leading to the precocius differentiation of Sertoli cell in prepuberal rats has been previously shown. The functional maturation of Sertoli cells is associated with changes in androgen metabolism. We have recently demonstrated that T3 influences androgen metabolism in Sertoli cells by inhibiting aromatase activity and reduces drastically the ER contents in peripubertal hypothyroid rats. To better understand the role of T3 in modulating steroid action on Sertoli cells, we performed a time course study evaluating the in vitro effects of T3 and testosterone (T) on androgen (ARs) and estrogen (ERs) receptor content in Sertoli cells isolated from two weeks old Wistar rats. ARs and ERs basal levels did not change during the time course study indicating that the exposure to culture medium per se did not affect either receptor type. After 24 hrs of incubation with either T3 or T, a decrease of ERs in both nucleus and cytosol was observed. Such a decrease was augmented by the simultaneous administration of both hormones. ARs displayed a different temporal pattern in the two cellular compartments and exhibited an earlier rise in the cytosol induced by either T3 or T. At 36 hrs, ARs were significantly enhanced in both compartments in response to either T or T3 exposure while combined hormonal treatment caused an additive increase compared with the single treatment group. As a consequence of the opposite behaviour pattern displayed by ARs and ERs, the ratio between total ARs and ERs contents was increased after 24 hrs of exposure to hormonal treatment. To evaluate if treatments performed induced a functional maturation of Sertoli cells, transferrin levels in culture medium were measured. The increase of this protein paralleled that of ARs content as well as that of ARs/ERs ratio. This study demonstrates that thyroid hormone induces a progressive increase of (AR)/(ER) ratio in the differentiating Sertoli cells bringing them to a prevalent androgen dependency along their functional maturation.
Exp Clin Endocrinol Diabetes 1997
PMID:A time course study on the "in vitro" effects of T3 and testosterone on androgen and estrogen receptors in peripuberal primary rat Sertoli cells. 928 9


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