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Biomedical subjects

M Tsubota

Publications and source records attributed to M Tsubota.

66 records · Page 4Linked to original sources
PubMed1986

Detection of differences in higher order structure between highly homologous single-stranded DNAs by low-temperature denaturant gradient gel electrophoresis.

Denaturant gradient gel electrophoresis performed at low temperature was shown to be able to detect the mobility change corresponding to the denaturation of the secondary structure of single-stranded(ss)DNA. Mobility transitions observed were determined to correspond to the melting of local structures, since both denaturants and temperature were verified to have similar effects on the mobility transition of single-stranded DNAs as on that of double-stranded DNAs. In this study it was found that point mutations can effectively change the secondary structures of ssDNA and RNA, and that the method adopted here is very sensitive to such alterations. The validity of the method was supported by a computer analysis of the secondary structure of DNA.

DNA, Single-Stranded↗
PubMed1980

Metabolism, 45Ca uptake and insulin releasing capacities of glucose and mannose.

A detailed dose-response study relating mannose and glucose oxidation with the induction of 45Ca uptake and insulin release was performed using in vitro incubation of collagenase digested rat islets of Langerhans. The threshold value for 14C-U-D-glucose oxidation, glucose-stimulation of 45Ca uptake, and insulin release was about 5.5 mM. The half maximal response for these 3 parameters occurred at 13.4 mM, 11.6 mM, and 12.2 mM, respectively. Their maximal responses were obtained at approximately 20 mM. The threshold level for mannose oxidation, induction of 45Ca uptake and insulin release was about 11.0 mM, with half maximal responses obtained at 24.6 mM, 20.5 mM, and 22.2 mM, respectively. The maximum response of the 3 parameters to mannose was obtained at 38.8 mM and appeared to reach the same level obtained for glucose. These results suggest that hexose degradation has a significant role in controlling Ca uptake and subsequent insulin release. A lower rate of mannose oxidation appeared to account for its weaker stimulating efficacy for Ca uptake and insulin release.

Animals↗
PubMedDate not supplied

A muscle powered cardiac assist device for right ventricular support: total assist or partial assist?

A muscle powered cardiac assist device (MCAD) for right ventricular support requires optimized diastolic filling to obtain full stroke and acceptable fluid dynamics. A valved and spring-assembled skeletal muscle ventricle (SMV) was designed as a prototype MCAD, regardless of fluid dynamics. The present study addresses the optimal bypass method for right ventricular support, and predicts the future design for an implantable MCAD. Latissimus dorsi muscle (LDM) of 11 dogs were conditioned electrically for a one year maximum, and transformed into fatigue-resistant muscles (Type I fibers). Superior and inferior vena cavae were anastomosed using one arm of a Y-shaped vascular graft, as an inflow conduit, and the outflow conduit was placed on the main pulmonary artery. SMV was wrapped with transformed LDM and the bypass method was varied by SVC and/or IVC ligation. SMV demonstrated sufficient right ventricular support on total bypass (70% compared with control output), and the maximum pump off-to-on flow ratio (200%) was obtained. Maximum SMV power output was 0.27 X 10(6) erg, which was equivalent to that of canine right ventricle. Right atrial-to-pulmonary artery bypass was also constructed by using SMV in another 14 dogs, and also showed that total bypass was preferable for optimal SMV diastolic filling. In conclusion, specific requirements for a future MCAD include a subsystem assembly such as a spring, magnet, or alternative auxiliary muscle pump assembly for MCAD filling, and total bypass with optimized fluid dynamics and anatomic fitting.

Animals↗