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Biomedical subjects

T Tsumita

Publications and source records attributed to T Tsumita.

At least 19 recordsLinked to original sources
PubMed1990

Deficiency of kallikrein-like enzyme activities in cerebral tissue of patients with Alzheimer's disease.

We examined the changes in the intracerebral activities, at the time of postmortem autopsy, in patients with Alzheimer's disease. When compared with the control group, the activity of kallikrein-like enzyme was significantly decreased, while prolyl endopeptidase activity increased, in the patients group. Aprotinin inhibited 50% of the activity of the former enzyme at 2 x 10(-7) M. Taken together with the results of a multivariate study, the above findings may indicate that intracerebral kallikrein deficiency plays an important role in the pathogenesis of Alzheimer's disease.

Aged↗
PubMed1990

Increased gamma-aminobutyrate aminotransferase activity in brain of patients with Alzheimer's disease.

In order to search for more proximal factors in the pathogenesis of Alzheimer's disease, we studied the activities of various enzyme in the brains of patients, as well as control cases, by postmortem autopsy. In addition to the findings already known, such as the increase in prolyl endopeptidase (post-proline cleaving enzyme, PPCE) activity and the decrease in kallikrein activity, we found, anew, an increase in aminobutyrate aminotransferase (GABA-T) activity in the Alzheimer brain. This may be an important impetus for the reduction of gamma-aminobutyric acid (GABA) in the brain, one of the neurotransmitters. It has to be determined whether the former two abnormalities offer a background for such an abnormality of the neurotransmitter.

4-Aminobutyrate Transaminase↗
PubMed1985

Antiglycolipid antibodies in normal and pathologic human sera and synovial fluids.

Antiglycolipid antibodies were measured in normal and pathologic sera and synovial fluids by means of a modified microplate method of complement-mediated immune lysis of fluorescent dye-trapped liposomes. All sera of normal subjects had antibodies against globopentaosylceramide (IV3 GalNAcGbOse4Cer), ganglioside GM1, gangliotriaosylceramide, gangliotetraosylceramide, and galactosylneolactotetraosylceramide antigens. Most sera of normal subjects had antibodies against lactotriaosylceramide, N-glycolylneuraminosyl-neolactotetraosylceramide (NeuGcnLcOse4Cer), GM3 ganglioside with N-glycolylneuraminic acid (NeuGcGM3) and GD1a antigens. Differences of titers against IV3GalNAcGbOse4Cer, neolactotetraosylceramide, NeuGcGM3 and NeuGcnLcOse4Cer antigens were observed between sera of normal subjects and pathologic sera from cases of leukemias, lymphomas, several autoimmune diseases and liver diseases.

Adult↗
PubMed1985

Analysis of the mode of antigen presentation required for triggering of T cell proliferation by using various azobenzenearsonate-tyrosine derivatives.

Various azobenzenearsonate-tyrosine (ABA-Tyr) derivatives were synthesized by modifying amino and carboxyl groups at the alpha-carbon of tyrosine, with preservation of most of the ABA-Tyr moiety (ABA plus hydroxyphenyl portion of tyrosine). These derivatives were tested for the ability to stimulate ABA-L-Tyr specific T cell lines derived from B10.BR and B10.S mice. ABA-acetyltyramine, ABA-hydroxyphenylpropionic acid (ABA-PPr), and ABA-propylphenol, which lack either the carboxyl or amino group or both, could not induce T cell proliferation. The lack of stimulation by these derivatives was not due to their cytotoxic effects. A similar pattern of proliferation was obtained on stimulating lymph node T cells from B10.BR and B10.S mice primed with ABA-L-Tyr. Some differences were observed, however, between B10.BR and B10.S mice. ABA-L-Tyr-specific T cells from B10.BR mice could not respond well to ABA-D-Tyr in contrast to B10.S T cells. Furthermore, B10.BR mice primed with ABA-acetyltyramine or ABA-PPr in complete Freund's adjuvant could not induce ABA-L-Tyr-reactive T cells, whereas T cells from B10.S mice primed with these derivatives could proliferate in the presence of ABA-L-Tyr. The differences between B10.BR and B10.S mice were further investigated by using (B10.S X B10.BR)F1 mice. T cells from ABA-L-Tyr-immunized F1 mice responded poorly to ABA-D-Tyr when presented with B10.BR antigen-presenting cells (APC), but responded well when presented with B10.S APC. Similarly, T cells from ABA-PPr-primed F1 mice did not proliferate to ABA-L-Tyr in the presence of B10.BR APC, but could proliferate in the presence of B10.S APC. Our results clearly indicate that the presence of charged groups at the alpha-carbon of tyrosine plays a critical role in the triggering of ABA-L-Tyr-specific T cell proliferation. The significance of these results is discussed.

Animals↗
PubMed1979

A defect of the myo-inositol maintenance mechanism in the lens of hereditary cataract mice.

The myo-inositol uptake system was studied in lenses of normal and hereditary cataract mouse. The normal mouse was able to accumulate myo-inositol continuously from medium and keep it in a high concentration. The specific myo-inositol uptake was dependent on temperature and it decreased in Ca(2+)-free medium. In contrast, specific uptake of myo-inositol reached a plateau after 15 min in the cataract mouse lens although initial incorporation was more rapid than that in normal mouse lens. This uptake system was not affected by temperature or Ca(2+) in the medium. The rate of myo-inositol efflux into the medium was more rapid in the cataract lens than that of the normal lens. It was shown that the low level of myo-inositol in the lens of hereditary cataract mouse was due to the defect of myo-inositol transport system and the enhanced efflux rate. These results suggest a dysfunction of the lens membrane.

Animals↗
PubMed1977

myo-Inositol binding and transport in brush border membranes of rat kidney.

Using hypotonically treated brush border membranes, binding and transport of myo-inositol were examined. By hypotonic treatment, both total and non-specific uptake decreased significantly, but specific uptake was not affected. myo-Inositol release from membranes preloaded by incubation for 2 min was very rapid and about 98% of preloaded myo-inositol was released in 5 min of incubation. However, myo-inositol release from membranes preloaded by incubation for 20 min was fairly slow and 50% of myo-inositol remained in the membranes even after 10 min of incubation. Uptake of myo-inositol decreased by the increase of osmolarity in the medium. However, effect of osmolarity on the uptake was less significant when myo-inositol concentration was lower. Under conditions in which mainly binding occurred, myo-inositol binding to the membranes was measured. Two binding systems were demonstrated and high affinity site could bind 22 pmol/mg protein at most and the apparent Km value was 8.3 muM. Both binding and transport processes were dependent on Na+ and enhanced by Na+-gradient.

Animals↗
PubMed1975

Enhancement of encephalitogenic activity by the formation of myelin basic protein-brain acidic protein complex.

Encephalitogenic protein fraction (BEC) was isolated from bovine brain tissue by extraction with salt-ethanol mixture at neutral pH, instead of employing dilute mineral acid. The fraction BEC was separated into two fractions. An acid-soluble protein was encephalitogenic and the major component was very alike to the basic protein of myelin (Al). The other was acid-insoluble acidic protein that was not encephalitogenic even at a dose of 100 mug. The acidic protein formed an insoluble complex with Al rotein which was purified by Eylar's method. Encephalitogenic activity of the complex was higher than Al protein in young guinea pigs when injected with complete Freund's adjuvant.However, this enhancement of encephalitogenic activity was not observed in aged guinea pigs. The complex showed higher blastogenic activity than Al protein alone with peripheral blood lymphocytes from guinea pigs immunized with Al protein and complete Freund's adjuvant. These results show that an adjuvant-like acidic protein is present in brain tissue and the complex with Al protein enhances the induction of experimental allergic encephalomyelitis (EAE).

Age Factors↗
PubMed1975

Experimental allergic encephalomyelitis (EAE) in mice. I. Induction of EAE with mouse spinal cord homogenate and myelin basic protein.

The condition of experimental allergic encephalomyelitis (EAE) induction was investigated in several mice strains. SJL and C3H/He strains were found to be susceptible. A single immunization with mouse spinal cord, complete Freund's adjuvant (CFA) and pertussis vaccine produced clinical signs of EAE in SJL and C3H/He strains after 11 to 18 days. Isogenic spinal cord produced EAE in C3H/He strain. A single immunization with myelin basic protein from bovine spinal cord in CFA and pertussis vaccine produced EAE in SJL strain. EAE susceptibility of SJL strain correlated with the amount of mycobacteria used for sensitization. It was necessary to give pertussis vaccine intravenously in all cases.

Animals↗