| Co-Investigator(Kenkyū-buntansha) |
SHIBUYA Norio NIIGATA COLLEGE OF MEDICAL TECHNOLOGY, ASSOCIATE PROFESSOR, 助教授
TSUCHIYA Yasuo GRADUATE SCHOOL OF MEDICAL AND DENTAL SCIENCES, ASSISTANT, 大学院・医歯学総合研究科, 助手 (60334679)
NAKAMURA Kazutoshi GRADUATE SCHOOL OF MEDICAL AND DENTAL SCIENCES, LECTURER, 大学院・医歯学総合研究科, 講師 (70207869)
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| Research Abstract |
From more than 10 years, we have been conducting epidemiological studies on gallbladder cancer in Chile, where the mortality for gallbladder cancer was reportedly the highest in the world. We have found that the mutagenic activity of Chilean bile collected from the cholecyst ectomized patients with gallstones was strong in terms of the numbers of revertant colonies in the Ames assay, as compared with those of biles collected from the patients with gallstones in Niigata and Kochi in Japan. Along with the studies in Chile, we discovered that free fatty acids (FFA), such as palmitoleic acid, oleic acid, linoleic acid, linolenic acid and arachidonic acid, inhibited the mutagenic activity of bile, when the mutagenicity of blue rayon adsorbate was tested by the Ames test. Inhibiting effects of mutagenicity were found among unsaturated free fatty acids and we designated them as inhibitory free fatty acids (IFFA). Based on these findings, we conducted the studies on the concentrations of FFA a
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nd IFFA in Chilean human bile collected from the patients with gallstones in order to know whether the concentrations of IFFA is lower in the prevalent area of gallbladder cancer in the world.
During the period between 2001 and 2002, we collected the bile samples from the patients who were surgically operated on for gallstones in Chile. Informed consents, which form had been approved by the Ethics Committee in Chile were obtained prior to the operation. We collected 21 and 129 samples of human bile from the male and female patients, respectively. The bile samples were stored at -20 degrees in Centigrade until use. FFA analysis was made by using an HPLC method.
Of 150 samples of human bile as a total, the concentrations of FFA were 6498.7±7686.1μ mol/l and those of IFFA were 4117.4±5719.6μ mol/l and the ratio of IFFA/FFA was 0.569±0.170. It was found that the concentrations of FFA and IFFA were significantly higher than those in Japanese samples, but the proportion of IFFA/FFA was almost equal to that of Japan (Japanese data not shown here). The proportions of palmitoleic and linoleic acids, however, were 1.9±3.9% and 1.8±5.6% respectively and they were found to be lower than 3.9±2.3 and 5.3±2.9 in Niigata, Japan. Further studies should be conducted to test how the low proportion of IFFA, such as palmitoleic and linoleic acids were observed in Chile. Less
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