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

The establishment of gene delivery systems that result in efficient transfection of the pancreatic beta-cells may generate an important tool for the study of IDDM and may also represent one critical step toward a clinical application of gene transfer for the prevention or early treatment of the disease. Using the reporter gene vectors pCAT and pCMV beta-gal, we have investigated the efficiency of transfection mediated by calcium phosphate precipitation, the monocationic liposome Lipofectin, the polycationic liposome Lipofectamine, and adenovirus-polylysine (AdpL) DNA complexes in human, mouse, rat, and fetal porcine islet cells. In all species studied, calcium phosphate-mediated transfection resulted in lower chloramphenicol acetyl transferase (CAT) activities than the other methods. Intact human, mouse, and rat islets were poorly transfected by Lipofectin, Lipofectamine, and AdpL. When dispersed by trypsin treatment, however, human, mouse, rat, and fetal pig islect cells were efficiently transfected by Lipofectamine. Moreover, transfection of dispersed human and mouse islet cells using AdpL, also resulted in high CAT activities. The percentage of cells staining positively for beta-galactosidase after transfection with Lipofectamine was 49% for mouse, 56% for rat, and 57% for dispersed human islet cells. Transfection of human islet cells using AdpL, however, yielded 70% beta-gal-positive cells. Fluorescence-activated cell sorting-purified rat islet alpha- and beta-cells were transfected with similar efficiency using Lipofectamine. CAT expression in human islet cells transfected with either Lipofectamine or AdpL reached a peak value after 5-7 days, followed by a gradual decline. It is concluded that transfection with AdpL or Lipofectamine are both efficient means to achieve transient expression of gene constructs in human and mouse islet cells, while for rat and fetal porcine islet cells, Lipofectamine is the most efficient of the agents investigated in this study.
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PMID:Efficient gene transfer to dispersed human pancreatic islet cells in vitro using adenovirus-polylysine/DNA complexes or polycationic liposomes. 877 22

The previous observation that urinary IgG excretion is increased in normoalbuminuric insulin-dependent (IDDM) patients is unexplained and could possibly be related to a laboratory phenomenon. When untreated urine samples were stored -20 degrees C for 2 to 4 weeks, the IgG/albumin Index (IgG clearance divided by albumin clearance) was higher in normoalbuminuric IDDM patients than in control subjects (0.91 (0.68-1.54), n = 27 vs 0.72 (0.55-0.79), n = 15 (median (interquartile range)), p < 0.05). In normo- and microalbuminuric IDDM patients the IgG/albumin index was higher in urine samples with glucose than without glucose (1.16 (0.93-1.68), n = 11 vs 0.73 (0.50-0.91), n = 16, p < 0.05, and 0.33 (0.23-0.60), n = 17 vs 0.15 (0.10-0.26), n = 14, p < 0.02 for normo- and microalbuminuric patients, respectively). We, therefore, evaluated the preserving effects of glucose and bovine serum albumin (BSA) on urinary IgG after 1 h to 16 weeks of freezing at -20 degrees C in 4 non-diabetic subjects (proteinuria ranging from 0.05 to 8.0 g 24 h-1). Urine samples were either stored without precautions or treated with addition of phosphate buffer, BSA (1%) and glucose 100 and 300 mM). The weekly decline from 1 to 16 weeks of IgG in the urine aliquots diluted 1:1 with buffered glucose 300 mM and glucose 300 mM + BSA 1% was insignificant, whereas urinary IgG declined with all other storage regimes (p < 0.05). These results suggest that glucose in urinary specimens of IDDM patients prevents at least in part the loss of urinary IgG and may thus explain the higher urinary IgG/albumin index when unprocessed urine is stored frozen before assay. Laboratory precautions are necessary when urinary IgG cannot be measured immediately.
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PMID:Increased urinary IgG/albumin index in normoalbuminuric insulin-dependent diabetic patients: a laboratory artefact. 884 Jan

NOD mice develop spontaneous IDDM as a result of T-cell-mediated autoimmune destruction of pancreatic beta-cells. It is not known why these T-cells become autoreactive, nor is it clear whether the breakdown in self-tolerance reflects a general problem in T-cell development or a selective defect in an as yet undefined regulatory cell population. In this study, we showed that NOD mice, although relatively normal with regard to most thymocyte subsets, exhibit a marked deficiency in alphabetaTCR+CD4-CD8- (alphabeta+DN) T-cells in the thymus and, to a lesser extent, in the periphery. These T-cells have been termed NKT cells (NK1.1+-like T-cells) because they share some cell surface markers with conventional natural killer (NK) cells. To examine the role of these cells in the pathogenesis of IDDM, semiallogeneic or syngeneic double-negative (DN) thymocytes, enriched for NKT cells, were transferred into intact 4-week-old NOD recipients; the onset of diabetes was then monitored over the ensuing 30 weeks. Mice receiving NKT-enriched thymocytes did not develop diabetes, whereas mice receiving unfractionated thymocytes or phosphate-buffered saline developed diabetes at the normal rate. NKT cells represent a distinct T-cell lineage that has been shown to play a role in immunoregulation in vivo. The deficiency of these cells observed in NOD mice may therefore contribute to destruction of pancreatic islet cells by conventional T-cells.
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PMID:Association between alphabetaTCR+CD4-CD8- T-cell deficiency and IDDM in NOD/Lt mice. 907 96

An elevation in intracellular calcium ([Ca2+]i) in rats with chronic renal failure and elevated blood levels of PTH is associated with down-regulation of the mRNA of many proteins. Similarly, in phosphate depleted animals that have normal renal function and low blood levels of PTH, [Ca2+]i is elevated and the mRNA of PTH-PTHrP receptor is down-regulated. The effect of elevation in [Ca2+]i on molecular machinery of many proteins may represent a generalized phenomenon. Diabetes mellitus may also be associated with a rise in [Ca2+]i and therefore down-regulation of the mRNA of proteins may also occur. The present study examined the effect of streptozotocin-induced diabetes mellitus in rats on the [Ca2+]i of the renal proximal tubular cells and on their mRNAs of the PTH-PTHrP, V1a and AT1 receptors. The basal levels of [Ca2+]i of these cells increased significantly (P < 0.01) after one day of diabetes and remained elevated thereafter. There was a significant (r = 0.67, P < 0.01) direct correlation between the [Ca2+]i of the cells and blood levels of glucose up to 350 mg/dl, and the value of [Ca2+]i plateaued with higher concentrations of glucose. Three days of amlodipine therapy prevented and reversed the elevated levels of [Ca2+]i despite marked hyperglycemia. The mRNA of all three receptors in the kidney were down-regulated and this defect was prevented by amlodipine which normalized the [Ca2+]i of the cells. The results show that: (1) the hyperglycemia of IDDM in rats causes a significant elevation in the basal levels of [Ca2+]i of the renal proximal tubular cells and down-regulation of their mRNA of PTH-PTHrP, V1a and AT1 receptors; (2) normalization of the [Ca2+]i of these cells by treatment of the diabetic rats with amlodipine prevented the elevation of [Ca2+]i and the down-regulation of the mRNA of these receptors; (3) these effects occurred in the presence of normal renal function and normal blood of PTH and phosphorus.
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PMID:Elevation of [Ca2+]i of renal proximal tubular cells and down-regulation of mRNA of PTH-PTHrP, V1a and AT1 receptors in kidney of diabetic rats. 918 88

In order to reveal sequel of events responsible for increase in red cell cytosolic glucose-6 phosphate (G-6P) content of diabetic patients the enzyme producing and transforming G-6P were assayed. Increase in the activity of hexokinase and decrease in phosphoglucoisomerase activity was observed in mild insulin dependent diabetes mellitus (mIDDM) rat erythrocytes. Increase and decrease in activity of hexokinase and phosphoglucoisomerase respectively will increase the cytosolic glucose-6 phosphate content. Thus any substance which autoregulate the activity of hexokinase and maintains critical level of G-6P necessary for generation of ATP and coenzymes (NADPH & NAD+) in the prevailing hyperglycemic state can be a potential therapeutic agent for diabetic patients.
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PMID:Activation of hexokinase by mild insulin dependent diabetes mellitus in rat erythrocytes. 937 21

In order to understand the molecular mechanism of reduced life span of diabetic erythrocyte, polypeptides and glycopeptides were analyzed by disc gel preparative sodium dodecyl sulphate polyacrylamide gel electrophoresis. An additional glycopeptide (244.5 kDa) and two additional polypeptides (39.81 and 144.5 kDa) were observed on glycopeptide and polypeptide gel profiles of mild insulin dependent diabetes mellitus (mIDDM) sample as compared to control. On the basis of molecular weight, their position on gel profile and their widely accepted nomenclature they were termed as glycosylated-ankyrin, membrane accreted glyceraldehyde-3-phosphate dehydrogenease (G 3-PD) and stress induced band 2.3 peptide. Earlier we have reported an increase in heterogeneity associated with increase in the population of aged fragile cells having altered membrane bound cation dependent ATPases, cytosolic dehydrogenase and hexokinase activities of mIDDM simulating rat erythrocyte sample. Significance of above observation in view of our earlier observation is discussed to explain the molecular mechanism of reduced life span of diabetic erythrocytes.
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PMID:Electrophoretic analysis of polypeptides and glycopeptides of erythrocyte membrane sampled from rats simulating mild insulin dependent diabetes mellitus. 985 34

A mechanism of autoimmune destruction of islet beta-cells in type 1 diabetes has been proposed to be the binding of Fas ligand (FasL) on T-cells to Fas receptors on beta-cells. We investigated this proposal by examining the expression of FasL and Fas on islet-infiltrating T-cells and beta-cells in relation to beta-cell destruction in a syngeneic islet transplant model in NOD mice. Diabetic NOD mice were transplanted with syngeneic islets and injected with complete Freund's adjuvant, which prevented diabetes recurrence (nondestructive insulitis), and with phosphate-buffered saline, which did not (beta-cell destructive insulitis). Two-color immunohistochemical assays revealed that FasL was expressed on CD4+ T-cells, CD8+ T-cells, and beta-cells in islet grafts from both diabetic and normoglycemic mice, and the percentage of each type of cell that expressed FasL was greater in islet grafts from normoglycemic compared with diabetic mice. In contrast, Fas was expressed on CD4+ T-cells, CD8+ T-cells, and beta-cells in islet grafts from diabetic mice, but it was nearly or totally absent on these cells in islet grafts from normoglycemic mice. Similarly, polymerase chain reaction analysis of islet grafts revealed that Fas mRNA expression was significantly lower in islet grafts from normoglycemic compared with diabetic mice. Also, mRNA levels of interleukin (IL)-1alpha, tumor necrosis factor (TNF)-alpha, and interferon (IFN)-gamma were significantly lower in islet grafts from normoglycemic mice. Finally, Fas was induced on NOD islet cells by incubation with IL-1beta, IFN-gamma, and the combination of IL-1beta, TNF-alpha, and IFN-gamma. These findings support the concept that cytokine-induced Fas receptor expression on islet beta-cells is a mechanism for their destruction by FasL-expressing CD4+ and CD8+ T-cells and, possibly, by FasL-expressing beta-cells themselves.
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PMID:Beta-cell destruction in NOD mice correlates with Fas (CD95) expression on beta-cells and proinflammatory cytokine expression in islets. 989 18

Intracerebral inoculation of susceptible strains of mice with Theiler's murine encephalomyelitis virus (TMEV) results in immune-mediated demyelinating disease. We examined the pathogenic roles of nitric oxide (NO) and inducible NO synthase (iNOS) in TMEV-induced demyelinating disease (TMEV-IDD). The presence of iNOS was confirmed in the spinal cords of TMEV-infected mice using immunohistochemical staining with anti-iNOS antibody on day 0 (control) and days 15, 30, 60, and 120. Aminoguanidine (AG), a specific inhibitor of iNOS, was injected intraperitoneally (ip) on 1, 3, 5, 8, 10, and 12 days post-TMEV inoculation as induction phase or 15, 17, 19, 22, 24, and 26 days as effector phase. Control animals in each experiment received phosphate-buffered saline (PBS) ip at similar time intervals. Few iNOS-positive cells were observed in the spinal cords of naive SJL/J mice. In the early phase (day 15) of TMEV-IDD, an increase of iNOS-positive cells was detected in the leptomeninges and perivascular space of the spinal cords. The number of iNOS-positive cells was increased and reached its peak on day 60, when histology of the animals showed peak infiltration with inflammatory cells. The clinical course of TMEV-IDD on each day postintracerebral infection was significantly reduced in mice treated with AG in the effector phase, and there was no significant difference between mice treated with AG in induction phase versus those administered PBS. Thus, NO production via iNOS appears to be a pathogenic factor in the effector phase of TMEV-IDD.
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PMID:Expression and potential role of inducible nitric oxide synthase in the central nervous system of Theiler's murine encephalomyelitis virus-induced demyelinating disease. 1038 21

Recent studies have suggested that elevated cellular lipid peroxidation may play a role in the development of cellular dysfunction and other complications of diabetes. People with type 1 diabetes frequently encounter elevated levels of the ketone bodies acetoacetate (AA), beta-hydroxybutyrate (BHB), and acetone (ACE). This study was undertaken to test the hypothesis that ketosis might increase lipid peroxidation and lower glutathione (GSH) levels of red blood cells (RBCs) in diabetic patients. This study demonstrates that incubation of AA with normal RBCs in phosphate-buffered saline (37 degrees C for 24 h) resulted in marked GSH depletion, oxidized glutathione accumulation, hydroxyl radical generation, and increased membrane lipid peroxidation. Increases in oxygen radicals and lipid peroxidation and depletion of GSH in RBCs were not observed with BHB or ACE treatments. Similarly, there was a significant generation of superoxide ion radicals even in a cell-free buffer solution of AA, but not in that of BHB. The presence of BHB together with AA did not influence the capacity of AA to generate oxygen radicals in a cell-free solution or the increase in lipid peroxidation of RBCs incubated with AA. The antioxidants vitamin E and N-acetylcysteine (NAC) blocked increase in lipid peroxidation in AA-treated RBCs. To examine the effects of ketone bodies in vivo, studies were performed that showed a significant decrease in GSH and an increase in lipid peroxidation levels in RBCs of hyperketonemic diabetic patients, but not in normoketonemic type 1 diabetic patients, when compared with age-matched normal subjects. This study demonstrates that elevated levels of the ketone body AA can increase lipid peroxidation and lower GSH levels of RBCs in people with type 1 diabetes.
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PMID:Hyperketonemia can increase lipid peroxidation and lower glutathione levels in human erythrocytes in vitro and in type 1 diabetic patients. 1048 Jun 18

Mutations in the hepatocyte nuclear factor-1alpha (HNF-1alpha) gene are the cause of maturity-onset diabetes of the young type 3 (MODY 3), which is characterized by a severe impairment of insulin secretion and early onset of the disease. Although the majority of patients with type 1 diabetes have type 1A, immune-mediated diabetes, there is a significant percentage of the patients who have no evidence of an autoimmune disorder at the onset of disease. The aim of this study was to estimate the prevalence of MODY 3 in antiislet autoantibody negative patients with type 1 diabetes. From a large population-based sample of unrelated Japanese patients with type 1 diabetes, 28 patients who lacked autoantibodies to glutamic acid decarboxylase, islet cell antigen 512/insulinoma-associated antigen-2, phogrin (phosphate homolog of granules of insulinoma)/insulinoma-associated antigen-2beta, and insulin at the onset of type 1 diabetes were examined by PCR-based direct sequencing of the 10 exons, flanking introns, and the promoter region of the HNF-1alpha gene. Two (7.1%) of 28 autoantibody-negative patients with type 1 diabetes were identified as carrying mutations in the HNF-1alpha gene. One patient carried a frameshift mutation (Pro379fsdelCT) in exon 6, and another patient carried a novel 2-bp substitution at nucleotides +45 (G to A) and +46 (C to A) from the transcriptional site of the promoter region. These mutations were identified in heterozygous form and were not identified in 64 unrelated healthy control subjects or 54 unrelated islet autoantibody-positive patients with type 1 diabetes. Functional analysis of the mutant HNF-1alpha gene indicated that the Pro379fsdelCT mutation had no transcriptional trans-activation activity and acted in a dominant negative manner. The +45/46 GC to AA mutation in the promoter region showed reduced promoter activity by 10-20% compared to the wild-type sequence. In conclusion, about 7% of Japanese diabetic patients lacking antiislet autoantibodies initially classified as having type 1 diabetes could have diabetes caused by mutations in the HNF-1alpha gene.
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PMID:Identification and functional analysis of mutations in the hepatocyte nuclear factor-1alpha gene in anti-islet autoantibody-negative Japanese patients with type 1 diabetes. 1063 7


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