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Biomedical subjects

T Tsuchiya

Publications and source records attributed to T Tsuchiya.

At least 721 records · Page 40Linked to original sources
PubMed1983

Lithium ion-sugar cotransport via the melibiose transport system in Escherichia coli. Measurement of Li+ transport and specificity.

A lithium ion-selective electrode was constructed using N,N'-diheptyl-N,N'-5,5-tetramethyl-3,7-dioxanonandiamid as a Li+ ionophore. Lithium ion-sugar cotransport via the melibiose transport system was measured with this electrode. Influx of methyl-beta-D-thiogalactoside, methyl-alpha-D-galactoside, methyl-beta-D-galactoside, and D-galactose elicited uptake of Li+. This Li+ uptake was not observed when the melibiose carrier was not present in the cells or the carrier was inactivated. Melibiose caused a small amount of Li+ uptake, indicating that Li+-melibiose cotransport proceeds inefficiently. Raffinose, another substrate, did not cause detectable Li+ transport. In mutant cells which showed altered cation coupling (Niiya, S., Yamasaki, K., Wilson, T. H., and Tsuchiya, T. (1982) J. Biol. Chem. 257, 8902-8906), Li+-melibiose cotransport was clearly demonstrated. Alteration in substrate specificity was also shown in the mutants.

Biological Transport, Active↗
PubMed1983

Isolation of mouse mammary tumor cells showing spontaneous regression.

The tumor cells, TMT-3, was isolated from TMT-2 tumor cells by way of repeated selections of large colonies in soft agar. The cells can grow either in mice or in suspension culture. TD50 of the ascites tumor cells was 1.5 +/- 1.0. Plating efficiencies in soft agar were 40-70% for cells of ascites tumors and 25-30% for cells of solid tumors. The cells showed 4 marker chromosomes common to the parent cells and 6 new marker chromosomes. They also shared MM-antigen, but its quantity was about half of the parent cells. The growth curves of the solid tumors were characterized by temporary decrease in tumor volume followed by regrowth or regression.

Animals↗
PubMed1983

[P-type silicon surface barrier detector used for X-ray dosimetry].

Responses to X-rays of a P-type surface barrier detector fabricated in our laboratory were studied, taking into consideration the dependence on the temperature in order to examine its applicability to dosimetry of short-range radiation. The study was also made in the case of N-type surface barrier detector. At room temperature, the short-circuit current increased linearly with exposure dose rate (15-50 R/min) for N- and P-type detectors. The open-circuit voltage showed a nonlinear dependence. With increasing temperature, the short-circuit current for the N-type detector was approximately constant up to 30 degrees C and then decreased, though the open-circuit voltage decreased linearly. For the P-type detector, both open-circuit voltage and short-circuit current decreased almost linearly with increasing temperature. While a P-type detector is still open to some improvements, these results indicate that it can be used as a dosimeter.

Radiometry↗
PubMed1983

Conformational change of the alpha subunit of Escherichia coli F1 ATPase: ATP changes the trypsin sensitivity of the subunit.

Conformational change in the alpha subunit of Escherichia coli proton-translocating ATPase was studied using trypsin. The subunit was cleaved with a small amount of trypsin (1 microgram/mg subunit) to peptides of less than 8000 daltons. On the other hand, the subunit was cleaved to two main polypeptides (30,000 and 25,000 daltons) in the presence of sufficient ATP (1 mM-0.5 microM) to saturate the high-affinity site of the subunit. Analysis of digests of the subunit combined with fluorescent maleimide suggested that the subunit was digested in the middle of the polypeptide chain in the presence of the nucleotide. ADP and adenylyl imidodiphosphate had the same effect as ATP. These results suggest that the conformation of the subunit changed to form two trypsin-resistant domains upon binding of ATP to the high-affinity site.

Adenosine Triphosphate↗
PubMed1983

Inhibition of aging changes by lyophilized Streptococcus faecalis in diet.

Effects of dietary Streptococcus faecalis (SF) on aging were evaluated using 1-week, 6-month, and 27-month-old Wistar and SHR rats. SF was lyophilized and added to commercial pellets at 1%. SF inhibited hypertension in aging SHR. SF inhibited aging-related changes in a wide variety of tissues. These changes were a disarray of hepatic cords, portal fibrosis; calcification of cartilage matrix, dominance of chondroitin sulfate B, and keratosulfate over chondroitin sulfates A and C; aortic endothelial damage, segmental thickening, calcification, and chondroid cells in the intima; atrophy of epidermis and appendages, and increase in amorphous dermal matrix; waxy degeneration and atrophy of psoas muscles; increase in lipoperoxides in the serum, liver, and brain; and reduction of cyclic AMP and GMP in the serum. Histological changes of the xyphoid cartilage, aorta, mesenteric artery, liver, dorsal skin, and psoas muscles in 27-month-old SF rats were much less severe than those in controls.

Aging↗
PubMed1983

Theoretical description of release, uptake, and pulse chase of labeled subunits of actin or a microtubule that undergoes head-to-tail polymerization.

The notion of the number of once-visited sites by a one-dimensional random walker is used to describe the amount of release, uptake, and pulse chase of labeled subunits of actin, or a microtubule that undergoes head-to-tail polymerization or treadmilling. Exact formulae for any number of steps are given as well as all the possible asymptotic forms of these quantities. Numerical calculations are carried out using hypothetical and experimentally measured values of rate constants.

Actins↗
PubMed1983

The production of mutagens in the intestine of mice fed on a diet containing 15% sorbic acid (I).

When mice were fed on a diet containing 15% sorbic acid for a period up to 6 months, ether extracts of the intestinal contents of the mice were not mutagenic with Salmonella typhimurium TA98, but the acidic components obtained by fractionating the ether extracts, showed slightly mutagenic activity with S. typhimurium TA98, and they required the addition of liver 9,000 xg supernatant fraction for mutagenic activation. These results suggested that mutagens were gradually produced in the intestine and moved into the liver where they were metabolically activated. It is possible to presume that liver carcinoma might be attributable to the production of these mutagens.

Animals↗
PubMed1983

Urinary excretion of mutagens and the effects of sorbic acid on the lipid peroxide level in the mice fed on a 15% sorbic acid diet.

The urine of the mice fed on a 15% sorbic acid diet was treated with or without beta-glucuronidase and was fractionated by XAD-2 column chromatography. The non-polar urine fraction was slightly mutagenic towards TA 98 when metabolically activated, but not towards TA 100. From the comparison of thin-layer chromatograms between the intestinal and urinary samples, it was suggested that a part of the mutagens produced in the intestine was excreted in the urine. As for the lipid peroxidation, the levels of lipid peroxide in the liver of the mice fed on a 15% sorbic acid diet were lower than those in the control over the feeding period of 15 months. Moreover, there was a correlation between the concentration of sorbic acid (X) in the diet and the lipid peroxide level (Y) in mice fed on potassium sorbate diets, obeying the linear equation, Y=-8.39X+ 341 (p less than 0.01). However, the lipid peroxide levels of 15% sorbic acid group did not fit with the above equation, and was higher than those of 20.1% potassium sorbate group, which was equivalent to 15% sorbic acid group in respect of sorbic acid concentration. Accordingly, the difference of lipid peroxide levels between the two groups (15% sorbic acid and 20.1% potassium sorbate group) might reflect productive difference of the mutagens.

Administration, Oral↗
PubMed1983

Evidence for cytostatic T cell activity in the effector mechanism against syngeneic TMT mammary tumor cells in mice.

The effector mechanism of immune spleen cells against syngeneic TMT mammary tumor cells was analyzed in vitro. C3H/He mice were first inoculated with TMT tumor cells, and then the tumors were x-irradiated with 2000 rad 1 wk after the inoculation. Spleen cells from these treated mice inhibited the growth of tumor cells in vitro when assessed by (3H)-TdR incorporation by tumor cells (cytostatic activity). The same spleen cells did not have any cytotoxic activity on TMT tumor cells detected by a 51Cr-release assay. The cytostatic activity was mediated by Lyt-1+23- T cells. The purified T cells alone could not inhibit the growth of tumor cells, but accessory cells were required for the induction of cytostatic T cell activity. The accessory cells were Ia-positive, macrophage-like adherent cells. Furthermore, both T cells and macrophages were also required for the inhibition of tumor growth even after the spleen cells were activated in vitro. These results suggest T cells and macrophages play an important role in the effector mechanism against TMT mammary tumor cells. The mechanism of cytostasis by T cells and macrophages was discussed from the standpoint of the cellular interaction.

Animals↗
PubMed1983

[Role of immunologic activity of host in radiotherapy].

The results of our studies on immunologic activity of host following irradiation to tumor in mice were summarized in this paper. The spleen cells from tumor irradiated mice inhibited growth of tumor in mice inoculated tumor cells with these spleen cells. These spleen cells also inhibited the colony formation and tumor growth in vitro system. The cytostatic activity of these spleen cells were enhanced after tumor irradiation. These results suggest that the specific anti-tumor cell-mediated immunity in host is enhanced by local irradiation to tumor, and that these immunologic effects depend on the presence of both T cells and macrophages.

Animals↗
PubMed1983

[A system for decontamination of liquid radioactive waste produced in in vitro tests in nuclear medicine].

It is well known that very large storage tanks for radioactive liquids are necessary for the disposal of liquid radioactive waste. In vitro tests in radioimmunoassay in nuclear medicine are rapidly increasing for clinical examination causing marked increase in the volume of liquid radioactive waste. Thus we have developed a system for decontaminating radioactivity from liquid waste. In the first step, the liquid waste is boiled by a sterilizer and, in the second step, this sterilised liquid is filtered by a cylindrical filter (Toyo filter No. 84). After filtration, the liquid waste is passed into a beaded charcoal column and an ion exchange resin (Amberlite IRA 402) column. After these treatments, the radioactivity level of liquid waste is lowered to less than 1% of the original radioactivity. We are now in the planning stages of building an apparatus for practical use.

Filtration↗