Biomedical subjects
Publications and source records attributed to Atsushi Ohta.
Here we describe a de novo tRNA acylation system, the flexizyme (Fx) system, for the preparation of acyl tRNAs with nearly unlimited selection of amino and hydroxy acids and tRNAs. The combination of the Fx system with an appropriate cell-free translation system allows us to readily perform mRNA-encoded synthesis of proteins and short polypeptides involving multiple non-natural amino acids.
RNAi, a novel strategy of gene-silencing induced by dsRNA, has recently become an important topic of discussion. dsRNAs introduced into a living body are processed by an enzyme known as the Dicer and become fractions of 21-23 nt RNAs (siRNA), after which they form protein complexes known as RNA-induced silencing complexes (RISC). The resulting RISC recognizes cognate mRNAs and cleave them. There are 2 ways to introduce dsRNAs to a living body: direct introduction of synthetic dsRNAs, and introduction of DNA templates into cells, followed by production of dsRNAs by transcription. Now that we can apply RNAi technologies into a living body, RNAi has become a widely used tool due to its great simplicity and high efficiency. However, there are still problems to be solved for more efficient use of RNAi. There are a wide range of applications such as analysis of gene functions and gene therapy. It is suggested that small RNAs, called miRNAs, exist in a living body and bind mRNAs to repress their translations. miRNA plays a great role in gene regulation and control of the differentiation and development of cells.
BACKGROUND/PURPOSE: We analyzed confluence patterns of intrahepatic segmental bile ducts, seeking to relate hepato-lithiasis to anatomic variation. The comparative study was completed patients with hepatolithiasis in Taiwan and Japan. METHODS: Direct cholangiography was performed in 103 hepatolithiasis patients in Taiwan and 77 in Japan. Segmental ducts patterns were classified as type I, normal configuration; type II, "triad" confluence; type III, posterior segmental duct joining left hepatic duct; or type IV, distal confluence of the right posterior segmental duct. RESULTS: Taiwanese patients had only calcium bilirubinate or black stones, and were mostly female. As overall analysis, types I, II, III, and IV were found in 61, 26, 13, and 3 patients, respectively. In Japanese, types I, II, III, and IV were found in 52, 10, 13, and 2, respectively. There was no difference between the two institutes. Since no patients in Taiwan had cholesterol calculi, Japanese patients were reanalyzed including only 58 patients with calcium bilirubinate or black stones. Differences in those populations remained insignificant. CONCLUSION: Anatomic variations in segmental ducts apparently do not contribute to pathogenesis of hepatolithiasis.
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