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)

Glutamic acid decarboxylase (GAD) has been shown to exist as two isoforms with molecular weights of 65 kD (GAD65) and 67 kD (GAD67) in the central nervous system as well as in several non-neuronal tissues, including the pancreatic islets. Recently, this enzyme has been proposed as a key beta-cell autoantigen in insulin-dependent diabetes mellitus (IDDM). In the present study, we used double label light and confocal microscopy to examine the expression of the two GAD isoforms in islet cells of fetal, neonatal and adult porcine pancreas. We also aimed to identify the islet cell-type(s) which co-express GAD. In the adult pig, GAD65 was localized exclusively in most of the beta cells, whereas GAD67, in addition to being present in a majority of the beta cells, was also seen in a proportion of glucagon and somatostatin labelled cells. In the 90-day fetus and the 7-day neonate, while GAD65 was also observed in a majority of beta cells, a proportion of glucagon cells also co-expressed this isoform. The cellular expression of GAD67 in the fetal and neonatal stages was similar to that in the adult. Detailed confocal analysis of GAD65 immunoreactive cells showed a granular cytoplasmic staining, with labelled granules often concentrated in specific perinuclear regions, possibly the Golgi apparatus. In contrast, GAD67 positive cells showed more diffuse cytoplasmic staining. The predominant expression of both the isoforms in porcine beta cells suggests that islet cells from this species may act as a suitable cellular model for study of GAD autoreactivity during the early stages of IDDM.
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PMID:Glutamic acid decarboxylase 65 and 67 isoforms in fetal, neonatal and adult porcine islets: predominant beta cell co-localization by light and confocal microscopy. 884 50

A considerable body of data supports the hypothesis that type I diabetes is a chronic progressive autoimmune disorder. Individuals with very high probability of progressing to diabetes can now be readily identified. Assays for autoantibodies reacting with insulin (IAA), glutamic acid decarboxylase (GAD65AA), and the neuroendocrine tyrosine phosphatase ICA512/IA-2 (ICA512AA) allow for the identification of more than 95% of individuals developing type I diabetes. The expression of a single autoantibody does not indicate high risk for diabetes and in general, prediabetic individuals express a series of biochemically defined autoantibodies. Levels of such autoantibodies are usually stable over years of follow-up. Unusual variants of autoantibody expression (e.g. GAD-ICA with high titers of GAD65 autoantibodies as the sole autoantibody) have low prognostic significance. Given the presence of multiple autoantibodies, low first phase insulin secretion (following intravenous glucose) is the best predictor of time to diabetes onset. Measurement of autoantibodies can now be automated and applied to large populations such that screening and prediction in the general population is now feasible. We favor the hypothesis that insulin may be the primary autoantigen for type I diabetes, and therapies which after the immune response to insulin may lead to safe and effective preventive modalities.
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PMID:Chronic autoimmunity of type I diabetes. 885 79

Two large population-based case-control studies are reviewed. The aim is to determine the effects of HLA, other genetic factors and immune markers (ICA, IAA and GAD65Ab) on the age at onset of insulin-dependent diabetes mellitus (IDDM) in 0-34 year olds. The primary HLA risk gene sequence for IDDM was difficult to identify because of the low recombination frequency within the HLA region. The frequency of the DR3-DQA1*0501-DQB1*0201 haplotype and the DR3-DQA1*0501-DQB1*0201 (DQ2)/DR4-DQA1*0301-DQB1*0302 (DQ8) genotype were higher among patients diagnosed before the age of 10 compared with those diagnosed after the age of 30. The negatively associated haplotype, DR15-DQA1*0102-DQB1*0602 was absent before the age of 10, but the frequency increased with increasing age at onset. The IDDM2 gene representing the variable number of tandem repeat (VNTR) sequences and 5' of the insulin gene on chromosome 11 were associated with IDDM since homozygous short VNTR was positive but not homozygous, and heterozygous long VNTR was negatively associated with the disease. The diagnostic sensitivity and specificity of GAD65 (GA65Ab) and insulin (IAA) autoantibodies varied with the age at onset and gender. GAD65Ab had the highest sensitivity (> 80%) in patients older than 20 years of age with no difference in gender. The lowest sensitivity (54%) was in 0-10 year old boys, while age did not affect the sensitivity in girls. In contrast, the sensitivity of IAA was highest (46%) before the age of 15 but decreased thereafter as did the sensitivity for ICA. Classification of patients who develop IDDM above 20-25 years of age was inadequate since many patients classified with NIDDM either had GAD65Ab or ICA or developed these antibodies after 1-2 years of NIDDM. We conclude that not only age but also gender affect the risk for IDDM associated with HLA, other IDDM genes as well as commonly used immunological markers for IDDM.
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PMID:Genetic and immunological findings in patients with newly diagnosed insulin-dependent diabetes mellitus. The Swedish Childhood Diabetes Study Group and The Diabetes Incidence in Sweden Study (DISS) Group. 885 82

Autoantibodies against heat shock protein (hsp) 60 have been reported to be detected in sera of non-obese diabetic mice, in an experimental model of IDDM. However, there are only a few studies which have examined IDDM patients for antibodies against mammalian hsp60. We produced murine hsp60 derived from pancreatic beta cells which has high homology to human hsp60 and examined antibodies against the hsp60 in IDDM patients using an enzyme-linked immunosorbent assay. We extended the analysis to patients with other immune-mediated diseases and non-insulin-dependent diabetes mellitus (NIDDM). Positive sera for hsp60 antibody were more frequently detected in 13 out of 84 IDDM (15.5%) and 5 out of 25 rheumatoid arthritis patients (20%), when compared to healthy subjects (1/85; 1.2%, P < 0.001 and P < 0.01, respectively). The levels of hsp60 antibodies of IDDM (0.218 +/- 0.227) and rheumatoid arthritis patients (0.259 +/- 0.191) were significantly higher than those of healthy subjects (0.076 +/- 0.131, P < 0.001, P < 0.01, respectively). Patients with slowly progressive IDDM (n = 26), autoimmune thyroid disease (n = 42), or NIDDM (n = 40) had levels of hsp60 antibodies similar to those in healthy subjects. We found no relationship between the levels of hsp60 antibodies and islet cell antibodies (ICA) or antibodies to glutamic acid decarboxylase (GAD65) in IDDM patients. In conclusion, hsp60 antibodies were detected in Japanese IDDM as well as in rheumatoid arthritis patients. Although the positivity was low, the detection of hsp60 antibodies may be helpful for diagnosis of IDDM especially in GAD65 Ab- or JCA-negative Japanese patients.
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PMID:Detection of autoantibodies to the pancreatic islet heat shock protein 60 in insulin-dependent diabetes mellitus. 886 27

The present study demonstrated that a short-term administration of mAbs against leukocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) at critical periods resulted in complete protection of autoimmune diabetes in non-obese diabetic (NOD) mice. When these mAbs were administered for only 6 days at 2 wk of age, neither diabetes nor insulitis was observed at 30 wk of age. It appears that the tolerance against beta cell Ag(s) was induced by this transient blockade of the LFA-1/ICAM-1 pathway. Protective suppressor activity was not enough to prevent diabetes because co-transfer of splenocytes from female NOD mice, which had received these mAbs at 2 wk of age, resulted in only a short delay of the diabetic onset caused by adoptive transfer of splenocytes from acutely diabetic NOD mice. Transfer of these splenocytes to young NOD mice could not also abrogate the spontaneous diabetes and insulitis. Furthermore, cyclophosphamide treatment could not abrogate the protection. When splenocytes from the treated NOD mice were transferred to NOD-SCID mice, none of the recipient mice developed significant insulitis and subsequent overt diabetes, suggesting the absence or the inactivation of diabetogenic effector T cells. However, splenic T cells from the insulitis-free NOD mice that had received the mAb treatment preserved proliferative responses to both islet cells and 65-kDa glutamic acid decarboxylase (GAD65) in vitro. These results suggest that a unique peripheral tolerance was induced by the transient blockade of the LFA-1/ICAM-1 pathway in an early age of NOD mice.
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PMID:Induction of tolerance in murine autoimmune diabetes by transient blockade of leukocyte function-associated antigen-1/intercellular adhesion molecule-1 pathway. 887 77

Islet cell antibodies (ICA), autoantibodies to glutamic acid decarboxylase (GAD) and HLA genotypes were examined in 31 patients with diabetes and a mitochondrial gene mutation located at base pair 3243 (mtDNA 3243 mutation). ICA was detected in 42% (13/31) of these patients compared to 0 of 90 among healthy control subjects. The ICA showed a "non-restricted" pattern of staining in all 13 ICA-positive patients. In a sensitive radioligand assay only 2 of 31 (6%) diabetic patients with the mutation were positive for both GAD65 autoantibodies and ICA, while the remaining 29 patients were GAD65 antibody negative. The ICA-positive patients had an increased frequency of the HLA-DQA1*0301 allele compared to control subjects (p < 0.05). Of the diabetic patients with the mutation 45% (14/31) had progressive clinical course of beta-cell failure. These results indicate that patients with an mtDNA 3243 mutation may develop islet autoimmunity associated with ICA and GAD autoantibodies. We hypothesize that the presence of HLA-DQA1*0301 in individuals with the mtDNA 3243 mutation increases the risk for diabetes and associated autoantibodies against islet cell antigens.
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PMID:Association between HLA and islet cell antibodies in diabetic patients with a mitochondrial DNA mutation at base pair 3243. 944 61

To study the immune response to glutamic acid decarboxylase (GAD) in insulin-dependent diabetes mellitus, monoclonal GAD antibodies after fusion of splenocytes from a nondiabetes-susceptible BALB/c mouse immunized with human recombinant GAD65 were generated. Of the 44 monoclonals, 35 are specific for the GAD65 isoform, whereas 9 also react with GAD67. Some 37 monoclonals, including all GAD65/67 reactive antibodies, react with GAD by Western blot analysis. The remaining 7 GAD65 monoclonals bind GAD only in an immunoprecipitation assay, which implies that they target epitopes dependent on the conformation of the GAD molecule. The 125I-GAD binding of the GAD65 monoclonals reactive on Western blotting was significantly diminished by all 3 sera from Stiff-man syndrome patients but only by 3/30 (10%) sera from type 1 diabetic patients. In contrast, the 7 monoclonal antibodies reactive with a conformation-dependent GAD epitope were competitive with 83% of GAD-autoantibody-positive sera from these diabetic patients. Using chimeric GAD65/67 proteins, the epitope region targeted by these monoclonals was mapped to the middle of GAD65 (amino acids 221-442). This central conformation-dependent GAD region was also targeted by sera from patients with type 1 diabetes. In conclusion, our data show that even after common immunization of a nondiabetes-susceptible mouse strain, monoclonal were obtained which preferentially react with the GAD65 linear amino-terminus (amino acids 4-17) and a conformation-dependent region located in the middle of GAD targeted by autoantibodies, indicating that this GAD region is not restricted to the autoimmune response associated with the Stiff-man syndrome and the beta-cell destruction in type 1 diabetes mellitus.
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PMID:Murine monoclonal glutamic acid decarboxylase (GAD)65 antibodies recognize autoimmune-associated GAD epitope regions targeted in patients with type 1 diabetes mellitus and stiff-man syndrome. 890 30

Virus infection has been proposed as an initiating factor in the aetiology of insulin-dependent diabetes mellitus (IDDM). We have examined lymphocyte proliferation to virus proteins which demonstrate sequence similarity to the beta-cell autoantigen glutamic acid decarboxylase (GAD)65. The magnitude and frequency of response to coxsackie B viruses and adenovirus in a T-cell proliferation assay was significantly higher in a group of recently diagnosed IDDM subjects than in non-diabetic control subjects. The frequency of positive response to the coxsackie B viruses was also significantly higher in IDDM subjects expressing the DRB 1*04 major histocompatibility complex (MHC) haplotype than the DRB 1*03 haplotype. There was no evidence that non-aspartate residue at position 57 of DQB 1 genes influenced virus responses in the IDDM group. The coxsackie homology was in amino acids 258-266 and the adenovirus homology was in amino acids 509-524 of GAD65. Both these regions are suspected to be T-cell epitopes in IDDM. These results indicate a disease and MHC class II association between coxsackie B virus infection and IDDM and an association between adenovirus infection and IDDM.
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PMID:Proliferative lymphocyte responses to virus antigens homologous to GAD65 in IDDM. 893 98

We have studied the presence of GAD65 autoantibodies in women with insulin-dependent diabetes mellitus (IDDM) (n = 28) or gestational diabetes (GDM) (n = 139) diagnosed during pregnancy and investigated the temporal relationship between these autoantibodies and the subsequent recurrence or development of IDDM. Among the GDM patients, 4.3% (6 of 139) developed true IDDM during a median follow-up period of 6.3 years (range 4.0-11.0). Of these, 2.2% (3 of 139) were positive for GAD65 autoantibodies at diagnosis of GDM compared to 0% (0 of 27) of healthy pregnant women. All 3 GAD65 autoantibody positive GDM patients subsequently developed IDDM after a median of 14 months (range 4-34). GAD65 autoantibodies were present in 50% (14 of 28) of sera from women with IDDM diagnosed during pregnancy. The non-insulin-requiring remission period was significantly shorter in GAD65 autoantibody positive patients (median 0.5 years [range 0-6.0 years]) than in GAD65 antibody negative patients (median 2.6 years; range 0-9.7 years; p < 0.05). The results suggest that screening for GAD65 autoantibodies in women with GDM or IDDM diagnosed during pregnancy may be useful for predicting the clinical course of the disease.
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PMID:GAD65 autoantibodies in women with gestational or insulin dependent diabetes mellitus diagnosed during pregnancy. 893

By subtraction strategy and polymerase chain reaction amplification, two novel cDNAs, designated IA-2 and IA-2 beta, were cloned, sequenced and expressed. Both are transmembrane proteins belonging to the protein tyrosine phosphatase family and are expressed in pancreatic islets. Serological studies revealed that a high percentage of patients with IDDM have autoantibodies to IA-2/IA-2 beta and that the presence of these autoantibodies in otherwise normal individuals is highly predictive in identifying those at risk of ultimately developing clinical diabetes. Moreover, many patients who are ICA positive, but who do not have Abs to GAD65, have Abs to IA-2/IA-2 beta. Enzymatic cleavage of IA-2/IA-2 beta and serological analysis showed that IA-2 is the precursor of the 40 kDa tryptic fragment and IA-2 beta is the precursor of the 37 kDa tryptic fragment, both previously shown to be autoantigens. It is concluded that IA-2/IA-2 beta are major autoantigens in IDDM and together with GAD65 are responsible for much of the reactivity of ICA with pancreatic islets. Tests for the detection of autoantibodies to recombinant IA-2/IA-2 beta and recombinant GAD65 are likely to replace the ICA immunofluorescence test for population screening.
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PMID:IA-2 and IA-2 beta are major autoantigens in IDDM and the precursors of the 40 kDa and 37 kDa tryptic fragments. 893 84


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