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  • 1
    ISSN: 1432-0428
    Keywords: Intravenous glucose tolerance test ; islet cell antibodies ; prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have followed-up 35 islet cell antibody-positive first degree relatives of patients with Type 1 (insulin-dependent) diabetes mellitus for an average of 1,300 days with sequential intravenous glucose tolerance tests. At the time of analysis and manuscript submission approximately half (18 of 35) had developed diabetes during follow-up. At initial intravenous glucose tolerance test, 11 had a 1+3 min insulin secretion below the first percentile of insulin secretion compared to 225 similarly studied normal control subjects. Six islet cell antibody positive relatives on follow-up developed an intravenous glucose tolerance test less than the first percentile. Fifteen out of 17 (88%) of these islet cell antibody positive relatives with secretion ever found to be below the first percentile are now overtly diabetic (positive predictive value=88%) and insulin-treated, while only 3 of 18 (17%) without an intravenous glucose tolerance test demonstrating loss of first phase insulin secretion have progressed to diabetes (with approximately 1,300 days of follow-up for both groups relative risk or odds ratio with intravenous glucose p〈0.001). tolerance test ever below vs never below the first percentile=38, Intravenous glucose tolerance test response below the first percentile preceded diabetes by an average of 656 days. Even when first phase insulin secretion is below the first percentile, the absolute value of 1+3 min insulin above basal insulin correlates with the time to development of diabetes (r=0.586, p〈0.001). With our current duration of follow-up, the negative predictive value (intravenous glucose tolerance test never below the first percentile) is 83%, and overall accuracy 86%. Incidence rates of diabetes development amongst our islet cell antibody positive relatives with follow-up while intravenous glucose tolerance test is below the first percentile is 0.48 per year (15 conversions to diabetes amongst 17 relatives in 30.8 patient years of follow-up) vs 0.05 per year (three diabetic patients in 55.5 patient years) with intravenous glucose tolerance test greater than the first percentile.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0428
    Keywords: Islet autoantibodies ; offspring ; autoimmunity ; transmission
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To help elucidate the mode of inheritance of insulin-dependent diabetes mellitus (IDDM), we measured GAD (glutamic acid decarboxylase) autoantibodies (GAD65Ab), insulin autoantibodies (IAA), and cytoplasmic islet cell autoantibodies (ICA) in 292 sequentially screened non-diabetic offspring of patients with IDDM. The prevalence of these islet autoantibodies was higher in offspring of diabetic fathers than in offspring of diabetic mothers. The prevalences of GAD65Ab, IAA, and ICA in the offspring of diabetic fathers were 11.5%, 10.8%, and 8.1% vs 2.1%, 1.4%, and 2.8%, respectively in the offspring of diabetic mothers (p〈0.002, p〈0.001, and p=0.06 NS). Amongst autoantibody-positive relatives the IAA and ICA levels were significantly higher in offspring of diabetic fathers than of diabetic mothers (p〈0.002 and p〈0.01, respectively). The frequencies of these autoantibodies were equal in male and female offspring. We conclude that IDDM mothers transmitted islet autoimmunity less frequently to their offspring than IDDM fathers. Given the markedly lower frequency of autoantibodies in offspring of mothers, larger sample sizes will be required to determine whether islet autoantibodies are influenced by age of IDDM onset of mothers, maternal age of pregnancy, and presence of diabetes in these mothers prior to conception.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0428
    Keywords: Gangliosides ; pancreatic islets ; beta-cell autoimmunity ; autoantigen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Recent studies have indicated that GM2-1, a pancreatic islet monosialo-ganglioside, is an islet-specific component whose expression is metabolically regulable and represents one of the target antigens of cytoplasmic islet cell antibodies. In the present study we aimed to biochemically characterize this molecule using a panel of biochemical techniques including gas chromatography, thin layer chromatography, enzymatic digestion and mass spectrometry. GM2-1 ganglioside was extracted from human pancreas and purified by thin-layer chromatography. Fatty acids in the ceramide (the hydrophobic portion of the molecule), identified by gas chromatography ranged from C16:1 to C24:1. The oligosaccharide chain was enzymatically digested by the sequential application of various exoglycosidases (neuraminidase followed by Β-galactosidase, followed by Β-hexosaminidase) and characterized by gas chromatography identification of the liberated sugars. The following structure was deducted from enzymatic studies and confirmed by mass spectrometry analysis: N-acetyl neuraminic acid-galactose-galactosamine-galactosamine-glucose-ceramide. This is a novel ganglioside structure, not yet described, which shares characteristics with a neuronal glycolipid autoantigen: the LM1 ganglioside. Both GM2-1 and LM1 have a single sialic acid residue in the terminal position, the same migration position on thin layer chromatography and the same number of carbohydrate moieties. In conclusion, we have characterized a novel islet-specific ganglioside molecule with unusual characteristics, such as the terminal sialic acid and the galactosamine residues, which may facilitate both its anti-genicity and its involvement in beta-cell autoimmunity.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0428
    Keywords: Key words Islet autoantibodies ; offspring ; autoimmunity ; transmission.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To help elucidate the mode of inheritance of insulin-dependent diabetes mellitus (IDDM), we measured GAD (glutamic acid decarboxylase) autoantibodies (GAD65Ab), insulin autoantibodies (IAA), and cytoplasmic islet cell autoantibodies (ICA) in 292 sequentially screened non-diabetic offspring of patients with IDDM. The prevalence of these islet autoantibodies was higher in offspring of diabetic fathers than in offspring of diabetic mothers. The prevalences of GAD65Ab, IAA, and ICA in the offspring of diabetic fathers were 11.5 %, 10.8 %, and 8.1 % vs 2.1 %, 1.4 %, and 2.8 %, respectively in the offspring of diabetic mothers (p 〈 0.002, p 〈 0.001, and p = 0.06 NS). Amongst autoantibodypositive relatives the IAA and ICA levels were significantly higher in offspring of diabetic fathers than of diabetic mothers (p 〈 0.002 and p 〈 0.01, respectively). The frequencies of these autoantibodies were equal in male and female offspring. We conclude that IDDM mothers transmitted islet autoimmunity less frequently to their offspring than IDDM fathers. Given the markedly lower frequency of autoantibodies in offspring of mothers, larger sample sizes will be required to determine whether islet autoantibodies are influenced by age of IDDM onset of mothers, maternal age of pregnancy, and presence of diabetes in these mothers prior to conception. [Diabetologia (1995) 38: 1353–1357]
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0428
    Keywords: Keywords Insulin ; autoantibodies ; autoreactivity ; T-lymphocytes ; insulin-dependent diabetes mellitus.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Insulin-dependent diabetes mellitus (IDDM) is the result of a T-cell mediated autoimmune beta-cell destruction,which is accompanied by autoantibodies. We analysed the cellular and humoral immune response to insulin and insulin peptides in patients with recent-onset IDDM, IDDM patients treated with insulin, non-diabetic first degree relatives and unrelated control subjects. There were no differences in T-cell reactivity to whole insulin or insulin peptides in general between age-matched groups of IDDM patients, relatives or healthy control subjects. In contrast to investigations in NOD mice, no immunodominant or disease-specific insulin peptide could be identified. Surprisingly, a positive correlation of T-cell responses to insulin with age was noted (p 〈 0.005). This resulted in an inverse relation of insulin autoantibodies (IAA) and insulin reactive T-cells (p 〈 0.001) together with the well-described negative correlation of IAA with age. Interestingly, insulin-treated patients differed from age-matched recent-onset IDDM patients: first, simultaneous immune recognition of insulin with T-cells and IAA was only seen in patients treated for 6 months with insulin; second, insulin-treated patients rarely responded to whole insulin; third, they displayed less determinant spreading, and finally, recognition of multiple insulin peptides was not accompanied by crossreactivity to whole insulin. These distinct observations in insulin-treated IDDM patients, together with the inverse correlation between humoral and cellular responses to insulin, may result from activation or modulation of different T-cell subsets, and may be of relevance to insulin therapy trials, in which selective activation of non-destructive T-cell subsets may be a key to successful intervention. [Diabetologia (1997) 40: 564–572]
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0428
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0428
    Keywords: Key words Gangliosides ; pancreatic islets ; beta-cell autoimmunity ; autoantigen.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Recent studies have indicated that GM2-1, a pancreatic islet monosialo-ganglioside, is an islet-specific component whose expression is metabolically regulable and represents one of the target antigens of cytoplasmic islet cell antibodies. In the present study we aimed to biochemically characterize this molecule using a panel of biochemical techniques including gas chromatography, thin layer chromatography, enzymatic digestion and mass spectrometry. GM2-1 ganglioside was extracted from human pancreas and purified by thin-layer chromatography. Fatty acids in the ceramide (the hydrophobic portion of the molecule), identified by gas chromatography ranged from C16:1 to C24:1. The oligosaccharide chain was enzymatically digested by the sequential application of various exoglycosidases (neuraminidase followed by β -galactosidase, followed by β -hexosaminidase) and characterized by gas chromatography identification of the liberated sugars. The following structure was deducted from enzymatic studies and confirmed by mass spectrometry analysis: N-acetyl neuraminic acid-galactose-galactosamine-galactosamine-glucose-ceramide. This is a novel ganglioside structure, not yet described, which shares characteristics with a neuronal glycolipid autoantigen: the LM1 ganglioside. Both GM2-1 and LM1 have a single sialic acid residue in the terminal position, the same migration position on thin layer chromatography and the same number of carbohydrate moieties. In conclusion, we have characterized a novel islet-specific ganglioside molecule with unusual characteristics, such as the terminal sialic acid and the galactosamine residues, which may facilitate both its antigenicity and its involvement in beta-cell autoimmunity. [Diabetologia (1995) 38: 1117–1121]
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-0428
    Keywords: Keywords Insulin-dependent diabetes mellitus, alternative splicing variant, ICA512/IA-2.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aims/hypothesis. The receptor tyrosine phosphatase like-protein ICA512/IA-2 occurs as a proteolytically-processed 65,000 Mr type 1 transmembrane glycoprotein in beta cells and is a major autoantigen of Type I (insulin-dependent) diabetes mellitus. We investigated whether alternative splicing could affect humoral autoreactivity to the molecule.¶Methods. Genomic and cDNA sequence analysis showed the presence of a ICA512 variant in islets and lymphoid tissues with an in-frame deletion of exon 13 which produces a secreted form lacking aa 557–629 including the transmembrane domain (aa 577 to 600). The alternatively spliced protein is detectable by western blotting in normal islets and translated into a protein that is processed to a series of soluble forms of 25,000–35,000 Mr. Radioimmunoprecipitation assays for anti-ICA512 autoantibodies were developed with the widely used ICA512.bdc construct (which has exon 13 deleted) and a series of full-length and modified ICA512/IA-2 molecules. ¶Results. The assays showed that ICA512.bdc and ICA512604–979 gave the best discrimination between diabetic and control sera. With ICA512604–979 a somewhat greater proportion of patients expressing antibodies were detected than with ICA512.bdc in the groups studied (70.5 % vs 63.2 % of prediabetic/new-onset and 25.0 vs 13.9 % in patients with diabetes 〉 20 years). Conversely, a small proportion (3 % recent-onset and 6 % 〉 20 years) had antibodies to ICA512.bdc but not ICA512604–979.¶Conclusion/interpretation. Important epitopes lie within the exon 13 region and others can be generated by the alternative splicing. As the Δexon 13 variant is probably secreted by the beta cell, it could be recognized by the cellular and humoral arm of the immune system in the absence of cellular damage. [Diabetologia (2000) 43: 1293–1301]
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  • 10
    ISSN: 1432-0428
    Keywords: Keywords Insulin-dependent diabetes mellitus ; HLA class II alleles ; newborn screening ; autoimmunity.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Autoimmunity causing insulin-dependent diabetes mellitus (IDDM) begins in early childhood due to interactions between genes and unknown environmental factors that may be identified through follow-up of a large cohort of genetically susceptible children. Such a cohort has been established using a simple and rapid cord blood screening for HLA alleles. The DRB1 and DQB1 second exon sequences were co-amplified using the polymerase chain reaction and hybridized with single and pooled sequence-specific oligonucleotide probes. Four individual probes were used to detect the susceptibility alleles DRB1*03, DRB1*04, and DQB1*0302 as well as the usually protective DRB1*15/16 (DR2) alleles. In addition, pooled probes allow the distinction of DR3/3 from the DR3/x genotype (where x is neither DR2, 3, nor 4) and DR4/4 from DR4/x. Among 5000 newborns from the general Denver population, we have found the high-risk genotype (DRB1*03/DRB1*04, DQB1*0302) to be present in 2.4 % of non-Hispanic whites, 2.8 % of Hispanics, and 1.6 % of African Americans. The moderate-risk genotypes (DRB1*04, DQB1*0302/DRB1*04, DQB1*0302, DRB1*04, DQB1*0302/x, or DRB1*03/DRB1*03) are present in 17 % of American non-Hispanic whites, 24 % of Hispanics and in 10 % of African Americans. These results demonstrate the feasibility of a large-scale newborn screening for genes associated with IDDM. The ultimate role for such a screening in future routine prediction and prevention of IDDM will depend on the availability of an effective and acceptable form of clinical intervention. [Diabetologia 1996) 39: 807–812]
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