Search PubMed⌕ Search

Biomedical subjects

Y Murakami

Publications and source records attributed to Y Murakami.

At least 1,027 records · Page 57Linked to original sources
PubMed1979

Effect of diaminobutene and diaminopropane on diet-stimulated polyamine synthesis and cell proliferation in rat liver.

The effect of two putrescine analogs were studied on hepatic polyamine synthesis and cell proliferation, both of which were stimulated by food intake. Trans-1, 4-diamino-2-butene (diaminobutene), which is a potent competitive inhibitor of ornithine decarboxylase [EC 4.1.1.17] (ODC), repressed the induction of ODC and effectively inhibited the accumulation of putrescine in rat liver which was induced by the feeding of dietary protein. Unexpectedly, diaminobutene did not suppress DNA synthesis and mitotic activity in rat liver, suggesting that it can mimic the role of putrescine in cell proliferation. 1,3-Diaminopropane effectively repressed the induction of ODC caused by food intake and also suppressed DNA synthesis and mitotic activity without affecting the accumulation of RNA or protein. The suppression of mitotic activity by 1,3-diaminopropane was reversed by a single injection of putrescine, spermidine, spermine, or diaminobutene. It was concluded that rapid accumulation of polyamines, especially putrescine, was a prerequisite for the later enhancement of DNA synthesis and cell proliferation in rat liver caused by food intake.

Animals↗
PubMed1978

Electrical resistance of the cochlear partition.

The relationship between the calculated value of the effective electrical resistance of the cochlear partition and the distance between the electrode for measuring the EP and the stimulating electrodes has been studied. The calculated value of the effective electrical resistance of the cochlear partition declines linearly with increasing distance between these electrodes. The correlation coefficient (r) is -0.806. In calculations of the effective electrical resistance of the cochlear partition, attention must be paid to the distance between the microelectrodes.

Animals↗
PubMed1978

[Production of 67Ga, 68Ga by bombardment of natural zinc target with alpha and 3He particles (author's transl)].

In order to determine the optimum irradiation condition for the production of 67Ga and 68Ga, used in nuclear medicine, excitation function and thick-target yield curves were obtained for alpha and helium-3 reactions of natural zinc. With the initial alpha energy of 25 MeV, the thick-target yield of 67Ga was found to be 165 muCi/muA.hr at the end of bombardment and the 66Ga contamination could be reduced to less than 1% after about 3 days of cooling. 68Ga could be obtained by milking from 68Ge. With the alpha energy range of 17-40 MeV, the thick-target yield of 68Ga was 1.2 muCi/muA.hr at the end of bombardment.

Alpha Particles↗
PubMed1978

[Production of 61Cu, 62Zn by alpha and 3He particle bombardment of natural nickel (author's transl)].

The optimum irradiation conditions were investigated for the production of 61Cu and 62Zn by alpha and 3He particle bombardment of natural nickel. Formation cross sections and thick-target yields were obtained for reaction products in the energy range of 10 to 40 MeV. For the production of 61Cu and 62Zn, the alpha particle bombardment was found superior to the 3He particle bombardment in so far as the yield was concerned. When the incident alpha energy of 21 MeV was chosen, after 2.4 hours of cooling, 2.1 mCi/muA.h of 61Cu could be produced with less than 1% of 60Cu contamination. For the production of 62Zn, when the incident alpha energy of 35 MeV and the target thickness of 57 mg /cm2 were chosen, 97.5 muCi/muA.h of 62Zn could be produced. Radiochemical purity of 62Zn was the highest at 12 hours after the end of bombardment.

Alpha Particles↗
PubMed1978

A biomathematical study on implant design and stress distribution.

Three types of implant were simulated by the two-dimensional finite element method using the mechanical properties of human mandible and implant material as input data. Type 1 was a blade implant, type 2 was blade implant with subperiosteal wings in buccolingual direction, and type 3 was subperiosteal implant with no blade. The effect of bucco-lingual subperiosteal wings in decreasing the stress concentration around the neck portion of the blade implant was investigated under three kinds of occlusal force. In conclusion, the greatest stress concentration was observed at the cortical bone around the neck portion of T-1 blade implant. It was effective in decreasing the stress concentration at this neck portion to change the implant design from T-1 to T-2 or T-3.

Blade Implantation↗