| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1993: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1992: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
I supposed that the accumulation of glyceraldehyde in pancreatic islets might be involved in the pathogenesis and/or development of non-insulin-dependent diabetes mellitus. This led me to intend to determine the amount of glyceraldehyde in pancreatic isltets. Triokinase was necessary for the assay of glyceraldehyde and was purified to homogeneity from porcine kindey. It had the molecular weight of 122,000 and was a homodimer. The Km of the enzyme for D-glyceraldehyde was 11 muM, the optimal pH was 7.5, and the enzyme was rather stable, indicating that the enzyme has properties suitable for the assay of glyceraldehyde. I developed an enzymatic microassay for islet glyceraldehyde. In the first step of the assay, NADH was produced through phosphorylation of glycelaldehyde by triokinase and subsequent oxidation of glyceraldehyde 3-phosphate by glyceraldehyde-3-phosphate dehydrogenase. In the second step, the NADH thus formed was amplified by the enzymatic cycling method. The amount of glyceraldehyde was estimated by measuring the fluorescence intensity of NADH.The amounts of glyceraldehyde in pancreatic islets cultured in the presence of 20 mM glucose for 1 and 5 hr were 70 and 270 fmol/islet, respectively. This indicated that glyceraldehyde certainly existed in pancreatic islets and that glyceraldehyde dramatically increased when pancreatic islets were exposed to high glucose. The results, taken together with the fact that glyceraldehyde relative to glucose has a potent ability to impair cells and tissues through glycation and autoxidation, suggest that the accumulation of glyceraldehyde may cause the pathogenesis and/or development of NIDDM through the damage of islet B cells.
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