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Biomedical subjects

K Yabu

Publications and source records attributed to K Yabu.

At least 37 records · Page 2Linked to original sources
PubMed1991

Cyclosporine enhances the growth of carcinogen-induced enzyme-altered foci in rat liver.

Cyclosporine, a powerful immunosuppressant, has been used successfully for organ transplantation. Its efficacy on liver transplants of patients with primary hepatic tumors remains controversial because of a high rate of recurrence of the original tumors in the transplanted livers. In this study, we experimentally tested whether cyclosporine exerts any effects on the growth of carcinogen-initiated liver cells using the short-term assays of rat liver carcinogenesis. Dietary cyclosporine, which maintained sufficient levels of blood cyclosporine and suppressed host immune functions, enhanced the development of the glutathione S-transferase, placental form-positive hepatocyte foci in the liver of male F-344 rats treated with a single weekly dose of diethylnitrosamine (75 mg/kg) for 3 wk. Dietary cyclosporine also accelerated the growth of preformed glutathione S-transferase, placental form-positive foci induced by a single dose of diethylnitrosamine (250 mg/kg) followed by the promoting regimen of a choline-deficient diet. It is possible that the enhancement of the size of hepatocyte foci by cyclosporine could be due to stimulation of growth or inhibition of regression. The mechanisms by which cyclosporine modifies the growth of preneoplastic lesions in the liver are not yet fully understood. Possible involvement of immunologically relevant cells in the liver, Kupffer cells and pit cells in the process is suggested.

Animals↗
PubMed1987

Familial dilated cardiomyopathy and human leucocyte antigen. A report of two family cases.

Two familial cases of dilated cardiomyopathy were evaluated by HL-A typing. In the case of the first family, the mode of inheritance is likely to be an autosomal dominant trait. Only the affected individuals carried the identical HL-A haplotype (A2, Bw54, Cw1, DR4, DQw3), while the unaffected members do not share this pattern. In the second family case, the disease is probably inherited by autosomal recessive traits. All of the family members examined shared the identical HL-A haplotype (A24, Bw52, DR2, DQw1), but only the affected individuals were homozygous for this haplotype.

Adult↗
PubMed1986

Cellular FITC-linked immunospecific assay (cell-FLISA) for detection of monoclonal antibodies against cell-surface antigens.

A cellular fluorescein isothiocyanate (FITC)-linked immunospecific assay (Cell-FLISA) has been established using the recently developed fluorophotometer for microplates. In the Cell-FLISA system, monoclonal antibodies specific for the surface antigens of live cells are detected by measuring the fluorescence intensity of an FITC-labeled second antibody: goat anti-mouse immunoglobulin antibody. It takes only 2 min to count 96 samples in microplate wells using the fluorophotometer for microplates. Moreover, by this system, the analysis is finished within 2 hr. Thus, the Cell-FLISA system has advantages in screening a large number of samples, such as hybridoma cell lines secreting monoclonal antibodies against cell-surface antigens.

Animals↗
PubMed1986

Antigen presentation by human antigen-presenting cells to antigen-specific xenogeneic murine T cells.

Successful antigen presentation by xenogeneic human antigen-presenting cells (APC) to stimulate the proliferation of antigen-specific, keyhole limpet hemocyanin (KLH)-specific, ovalbumin (OVA)-specific, and purified protein derivative of Mycobacterium tuberculosis (PPD)-specific murine T cells was observed. Evidence indicating a direct cell interaction between antigen-specific murine T cells and xenogeneic human APC was given by experiments using antigen-specific murine T cell clones. The OVA-specific B10.S(9R) T cell line (9-0-A1) and PPD-specific B10.A(4R) T cell line (4-P-1) were stimulated by both xenogeneic human APC and murine APC from syngeneic or I-A compatible strains, while the PPD-specific human T cell line (Y-P-5) was stimulated by autologous human APC but not by murine APC. Anti-HLA-DR monoclonal antibodies (MoAb) blocked the xenogeneic human APC-antigen-specific murine T cell clone interaction. Thus, human xenogeneic APC can stimulate antigen-specific murine T cells through HLA-DR molecules in the same manner as syngeneic murine APC do through Ia molecules coded for by the I region of the H-2 complex, while murine APC failed to present antigen to stimulate human antigen-specific T cells.

Animals↗
PubMed1985

Phylogenetic hierarchy of antigen-presenting ability in antigen-specific T cell activation.

The phylogenetic hierarchy of antigen-presenting ability was shown to exist in xenogeneic mouse, rat and human T cell-antigen-presenting cell (APC) interaction. The antigen-presenting ability of human APC is dominant over that of rat APC and the ability of rat APC is dominant over that of mouse APC. The HLA-DR molecule was shown to function for antigen presentation to PPD-specific autologous human and xenogeneic murine T cells.

Animals↗
PubMed1985

Relationship between beta-lactamase activity and resistance to beta-lactam antibiotics in Mycobacterium smegmatis.

Penicillin-susceptible mutants and beta-lactamase-negative mutants were isolated from Mycobacterium smegmatis after nitrosoguanidine mutagenesis. Both the mutants were found to be susceptible to low levels of penicillin and cephalosporins by twofold dilution testing. Clavulanic acid reduced the minimal inhibitory concentrations of beta-lactamase-labile beta-lactams for the penicillin-susceptible mutants and the parent strain, but had no effect on the susceptibility of the beta-lactamase-negative mutants. Comparison of the beta-lactamase activities found in these mutants and the parent strain indicated that there was a rough correlation between the beta-lactamase level in these organisms and their susceptibility to beta-lactams.

Anti-Bacterial Agents↗
PubMed1984

Interspecies cross-reactivity of Class II antigen of MHC determined by syngeneic, allogeneic and xenogeneic B and T cells.

Although this chapter ought to summarize the role of MHC antigens in T cell activation, the immunobiological meaning of the polymorphism of Class II antigens, as well as that of Class I antigens, is still unresolved. The antigen-presenting ability of human APC is dominant over that of murine APC in the stimulation of antigen-specific xenogeneic T cells. In addition, xenoreactive murine T cells specific for human PBL failed to recognize the polymorphic determinant of Class II antigens of human MHC. On the basis of the data, Class II antigens may be seen to have some role as antigen-presenting molecules rather than as restricting molecules, at least, in the xenogeneic APC-T cell interaction or the xenogeneic MLR responses. These data together with the fact that the linkage disequilibrium found among the various groups of alleles encoding Class I and II antigens making up an MHC haplotypes suggest that the MHC may play a key role during evolution. These studies using xenogeneic cell interaction may shed some light on the immunobiological function of polymorphism of MHC antigens in the mechanisms of T cell activation, and the evolutional history of the polymorphism of the NHC in self or not-self recognition by T cells.

Animals↗
PubMed1983

A case of asymptomatic primary biliary cirrhosis with an initial presenting feature of localized gastric varices.

A case of asymptomatic primary biliary cirrhosis (PBC) with an initial presenting feature of localized gastric varices is reported. The patient, 64 years old female, underwent a barium meal examination because of ill-defined abdominal complaints and was found to have gastric varices localized at the cardia but no esophageal varices. Her blood chemistry showed high values of biliary tract enzymes such as alkaline phosphatase and gamma-glutamyl transpeptidase, but the serum bilirubin level was almost normal. Serum anti-mitochondrial antibody was positive. Histological findings of the surgically biopsied liver specimen were compatible with PBC. The clinical implication of gastric varices in PBC is discussed.

Female↗
PubMed1974

Inhibition of growth of Mycobacterium smegmatis and of cell wall synthesis by D-serine.

d-Serine inhibited the growth of Mycobacterium smegmatis and induced the morphological alteration of the bacilli. The growth inhibitory action of d-serine was partially reduced by an equimolecular concentration of d-alanine. The combination of glycine with d-alanine reversed the growth inhibition produced by d-serine more than did d-alanine alone. In cells cultured in the presence of d-serine, the amounts of alanine, diaminopimelic acid, and glycine inserted into the cell wall mucopeptide were reduced, and serine was increased. The intracellular accumulation of a precursor of cell wall mucopeptide was increased by d-serine, and this accumulation was reduced by d-alanine. d-Serine competed with glycine for incorporation into the cell wall mucopeptide. The incorporation of l-aspartic acid into diaminopimelic acid residues in the cell wall mucopeptide was markedly inhibited by d-serine. Three mutants resistant to d-serine were isolated by nitrosoguanidine treatment. In these mutants the effects of d-serine on the sites of cell wall mucopeptide synthesis were all reduced. Thus, d-serine inhibition of the growth is due to replacement of glycine residues of the cell wall mucopeptide with d-serine and inhibition of the cell wall synthesis by blocking the formation of d-alanine and diaminopimelic acid.

Amino Acids↗