In 1960, the author started a thiamine research at Department of Hygiene, Faculty of Medicine, Kyoto University, under Professor Fujiwara's guidance. Allithiamine, a lipotropic derivative of thiamine, enters cells in direct proportion to dosage by passive diffusion and then is quickly converted to thiamine intracellularly. The author used allithiamine labeled with S^<35> on sulfur in the S-propyl group [TPD-S^<35>(outer)] and labeled with S^<35> on sulfur in the thiazole group [TPD-S^<35>(inner)]. It was found that allithiamine split in vivo at the -S-S- linkage into the thiamine portion and propylmercapto group. The thiamine part penetrated in large amount into the blood cells, while the majority of S^<35> from propylmercapto group was found in plasma after oral or parenteral administration of allithiamine. From 1967 to 1969, the author conducted some studies on nonenzymatic role of thiamine in nervous function with Professor J. R. Cooper at Yale University, U.S.A. and these results suggested that thiamine played an important role in the function of the sodium channel in nerve membranes. However, a hypothesis that thiamine triphosphate might play a role in this function could not be elucidated. The methodology which we adopted at that time was so primitive to clarify the problems. In 1979, the author was appointed as the professor and chiarman of Department of Hygiene, one of the field of social medicine, and the author had to include some researches with a tinge of social medicine into our research projects besides the biochemical studies. Amyotrophic lateral sclerosis was prevalent in the Muro district in Wakayama Prefecture and magnesium content in drinking water from this area was lower than water from the other districts in Japan. In 1962, we investigated thiamine metabolism of these patients and found that the patients had lost the ability to utilize thiamine. This finding drived me to start the another research project on the clarifica tion of relationship between thiamine and magnesium metabolism. Since then, variety of researches on two major fields, i.e. vitamins and minerals, had been carried out by our research group. The author would be very glad if this article could be helpful for young researchers to develop their future researches on vitamins by learning from our researches including unsuccessful ones, "Hanmenkyoshi" in Japanese.
