Aim: The aim of this study was to clarify the change in cell mass in Japanese obese individuals. Methods: We obtained the pancreas at autopsy from 39 lean and 33 obese Japanese nondiabetic individuals (aged 4713 vs 4712 y, P.83, body mass index 20.41.6 vs 28.53.9 kg/m2, P.01). Pancreatic sectionswerestained for insulin,and-cell area(%BCA)wasmeasuredas the fraction of the -cell area to the total pancreas area. Cell mass was then calculated as the product of %BCA and estimated pancreas weight. -Cell replication and apoptosis were assessed by double staining for insulin and Ki67 and insulin and single-stranded DNA, respectively. The frequencies of insulin-positive duct cells and scattered -cells were assessed as the surrogate markers of -cell neogenesis. The -cell area (%ACA) was also measured, and the %ACA to %BCA ratio was determined. Results: There was no increase in cell mass in obese individuals compared with lean individuals (0.6 0.4 vs 0.7 0.4 g, P .12). -Cell replication, -cell neogenesis, and -cell apoptosis were not significantly increased in the presence of obesity. There was no significant difference in%ACA to %BCA ratio between obese and lean individuals (0.91 1.09 vs 0.75 0.51, P .47). Conclusion: There was no increase in cell mass and no detectable change in -cell turnover in Japanese obese individuals.
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