- Mesurement of GAD Antibodies using Radioligand Binding Assay, IRMA and RIA in Patients with Tye 1 Diabetes Mellitus.
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In Kyu Lee, Hyoung Woo Lee, Kyu Chang Won, Hyun Dae Yoon, In Ho Cho, Ji Sung Yoon, Sang Yiup Nam, Jung Hyun Oh, Jin Cheol Park, Jae Hong Kim
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Korean Diabetes J. 1999;23(3):278-287. Published online January 1, 2001
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 Abstract
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- BACKGROUND
Type 1 diabetes mellitus is an autoimmune disease in which serum antibodies against islet antigens have been recognized. These antibodies include insulin autoantibodies (IAAs), cytoplasmic islet cell antibodies (ICA) and GAD antibodies. Recently, there has been increasing interest in the use of glutamic acid decarboxylase antibodies (GADA) for the identification of subjects with increased risk of developing type 1 diabetes. GAD antibodies were first discovered in 1982 and is detected persistently after long duration of type 1 diabetes, whereas ICA is transient. However, because the classic immunoprecipitation assays of GAD antibodies is still rather time-consuming, a more simple and reproducible radiolignad binding assay (RBA) is has been widely used recently. The RIA (radioimmunoassay) and IRMA (immunoradiome- tricassay) for GAD antibodies using (125)I-labelled human GAD has been developed, The aim of the present study is to evaluate the usefulness of each methods. METHODS: We measured GAD antibodies by RBA with in vitro spathesized recombinani S-methio- nine-labelled GAD65, and protein A-sepharose to separate free from antibody-bound ligand and radioimmunoassay and immunoradiometric assay using 'I-labelled human GAD kit, in addition to measurement of ICAs by standard indirect immunofluorescence technique in 26 patients with type 1 diabetes(male 10, female 16, mean age 14 years) and 10 normal controls(male 5, female 5, mean age 15 years). RESULTS: The overall prevalence of GAD antibodies by RBA and RIA in patients with type 1 diabetes was 38% (10/26), respectively. The prevalence of GAD antibodies by IRMA in patients with type 1 diabetes was 31% (8/26). The frequency of GAD antibodies by RBA,IRMA and RIA increased as the JDF unit of ICA increased. There is a significant correlation between the GAD index (by RBA) and GAD concentration (by RIAand IRMA). CONCLUSION: These results suggest that GAD antibodies (by RIA or RBA or IRMA) is useful for screening and diagnosis of type 1 diabetes in Korean, but long-term prospective studies on large cohorts of patients is necessary.
- Upregulation of Aldose Reductase mRNA by Hyperglycemia in Claf Pulmonary Artery Endothelial Cells.
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Sang Yiup Nam, Jung Hyun Oh, Jin Chul Park, Ji Sung Yoon, Kyu Chang Won, Chan Woo Lee, Ihn Ho Cho, Choong Ki Lee, In Kyu Lee, Hyoung Woo Lee
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Korean Diabetes J. 1998;22(3):290-298. Published online January 1, 2001
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Abstract
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- BACKGROUND
Hyperglycemia is thought to be an important etiologic factor in the development of diabetic macro- and microangiopathies. Several theories have been proposed to explain why diabetic patients are at an increased risk for such vascular disorders. In uncontrolled diabetes, excess glucose causes a glycation of various proteins, an increase in oxidative stress, an increase in DAG or PKC and an increase in polyol pathway. And, it has been proposed that hyperglycemia leads to the dysfunction or damage of endothelial cells through the activation of cellular aldose reductase(polyol pathway). METHODS: To verify this hypothesis, we quantitated AR(Aldose reductase) activity and mRNA in CPAE(Calf pulmonary artery endothelial) cell under normal and high ambient glucose levels in the culture medium. The time course of AR mRNA expression after exposure of CPAE cells to 22mM glucose was determined using PCR quantitative analysis. RESULTS: AR mRNA levels began to increase at 6h after glucose exposure, reached a maximum at 24h (about 2.3 fold increase), and then gradually decreased. Aldose reductase activity was found to strongly correlate with aldose reductase mRNA expression after cells were exposed to 22mM glucose. In contrast, aldose reductase mRNA expression at 24h after glucose exposure decreased following exposure to 50mM glucose. By testing other osmolytes, we also examined whether the AR activity is specific for glucose. There was an increase in AR activity only after the addition of 20mM mannitol to the medium. CONCLUSION: These observations suggest that hyperglycemia could induce the overexpression of aldose reductase mRNA in cultured CPAE cells and this could be an important step in the pathogenesis of diabetic complications.
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