Comparison of pancreatic volume and fat amount linked with glucose homeostasis between healthy Caucasians and Koreans.

AIM: To compare pancreatic volume and fat amount, and their associations with glucose homeostasis, in a Korean and a white population. MATERIALS AND METHODS: In 43 healthy Korean and 43 healthy white people, matched for age (±3 years) and body mass index (BMI; ±1 kg/m2 ), we measured pancreatic volume and fat amount in the pancreas and abdomen using computed tomography. Pancreatic ß-cell function and insulin resistance were estimated according to biochemical characteristics and a 75-g oral glucose tolerance test. Body composition and resting energy expenditure (REE) were examined using bioimpedance and indirect calorimetry, respectively. RESULTS: The mean ±SD age of the participants was 29.9 ± 5.9 years and 30.0 ± 5.2 years, and BMI was 24.0 ±3.7 and 24.1 ±3.2 kg/m2 in the white participants and the Korean participants, respectively. Pancreatic volume in the white participants was greater than that in Korean participants (77.8 ±11.6 vs 68.2 ±12.1 cm3 ; P < .001). Pancreatic fat content in Korean participants was 22.8% higher than in white participants (P = .051). Insulinogenic index, disposition index, muscle mass and REE were significantly lower in Korean participants. Pancreatic volume was positively associated with indices linked to ß-cell function; fat content in the pancreas was negatively associated with such indices, and positively with insulin resistance after adjusting for relevant variables including REE. CONCLUSIONS: A smaller pancreas and higher fat deposition might be crucial determinants of vulnerability to diabetes in Korean people compared with white people with similar BMI and body fat levels.

Toxicity of hexavalent chromium to Daphnia magna: influence of reduction reaction by ferrous iron.

The reaction kinetics of hexavalent chromium with ferrous ions were studied to determine the influence of reduction on the toxicity of chromium to aquatic organisms. The changes in chemical forms of the chromate in the presence of ferrous ions were examined in a bioassay system using Daphnia magna as a test organism. This study demonstrated that the reaction kinetics of chromate with ferrous ions showed a significant decrease of chromate concentration with the second-order rate coefficient (k) for the reduction of Cr(VI) being determined as 55.2M(-1)s(-1). The concentration of Cr(VI) remaining in the solution decreased as the ratio of ferrous ion to chromate increased, revealing a non-stoichiometric reaction due to oxygenation and the moderately alkaline pH of the solutions. The toxicity test indicated that the bioavailability of chromate to D. magna was reduced in the presence of Fe(II) and that it decreased further with increasing Fe(II) concentrations. However, the toxic effect of chromate to aquatic organisms was not controlled kinetically in the presence of ferrous ions. It was also found that LC(50) of chromate to D. magna decreased about 1.5-fold as the test period increased from 24 to 48h in the presence of Fe(II).