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Biomedical subjects

Y Hashimoto

Publications and source records attributed to Y Hashimoto.

At least 1,477 records · Page 82Linked to original sources
PubMed1983

Sequence selective modification of DNA with muta-carcinogenic 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole.

2-Acetoxyamino-6-methyldipyrido[1,2-a:3',2'-d]imidazole binds covalently to the 8 position of guanine residues in DNA. Treatment of the modified DNA with aqueous piperidine causes the liberation of the modified nucleic acid base, 2-(C8-guanyl)amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole, and cleavage of DNA at the sites of the modified guanylic acid residues. By use of 5'-end 32P-labelled DNA and sequence analysing gel electrophoresis, we discovered the base sequence specificity of DNA modification with 2-acetoxyamino-6-methyldipyrido[1,2-a:3',2'-d]imidazole. The guanine residues in G-C cluster-like regions are modified more frequently.

Base Sequence↗
PubMed1983

Coating of liposomes with subunits of monoclonal IgM antibody and targeting of the liposomes.

SH-bearing subunits of IgM antibody were coupled through the Fc portion to sonicated liposomes consisting of N-(m-maleimidobenzoyl)dipalmitoylphosphatidylethanolamine, dipalmitoylphosphatidylcholine and cholesterol. Liposomes coated with subunits of monoclonal IgM antibody against a mouse mammary tumor-associated antigen selectively bound to the antigenic target cells. Assays of the liposomes for complement dependent cytotoxicity and spleen cell binding revealed inactivation of the liposome-coupled antibodies in both assays.

Animals↗
PubMed1983

Rod input to amacrine cells in dace retina.

Intracellular recordings in dace retina demonstrate a type of amacrine cell whose responses to flashes of light were characteristically a transient depolarization at the onset of light, followed by a slow decay toward the dark level, similar to rod-dominated, AII amacrine cells described in cat retina. Electron microscopy of HRP-filled dace AII-like amacrine cells suggested that they receive significant rod inputs through rod-dominated bipolar cells.

Animals↗
PubMed1983

O-methylation of dopamine-o-sulfates with catechol-0-methyltransferase.

[2H2]-dopamine-3-0-sulfate (DM-3-0-S) and [2H2]-dopamine-4-0-sulfate (DM-4-0-S) were synthesized to investigate the possibility of their being substrates for catechol-0-methyltransferase (COMT). [2H5]-3-0-methyldopamine (3-0-Me-DM) and [2H5]-4-0-methyldopamine (4-0-Me-DM) were also synthesized as internal standards for the determination of enzymatic products by gas chromatography-mass spectrometry (GC-MS). [2H2]-DM-3-0-S or [2H2]-DM-4-0-S was incubated at 37 degrees for 60 min in the presence of S-adenosyl-L-methionine with a crude enzyme preparation obtained from rat liver homogenate. The incubation mixture was treated with 0.5N HCl at 100 degrees C for 1h to hydrolyze the remaining sulfate moiety. The reaction products were extracted with an Amberlite XAD-4, derivatized with pentafluoropropionic anhydride and determined by GC-MS. When [2H2]-DM-3-0-S was used as a substrate, [2H2]-3-0-Me-DM was found to be a major product accompanied by [2H2]-4-0-Me-DM as a minor product. The ratio of [2H2]-3-0-Me-DM to [2H2]-4-0-Me-DM was found to be 26:1, while the ratio was 5.4:1 when [2H2]-dopamine was used as a substrate. When [2H2]-DM-4-0-S served as a substrate, [2H2]-3-0-Me-DM was preferentially produced without detectable formation of [2H2]-4-0-Me-DM.

Animals↗
PubMed1983

Aortic fibrous components in exercised rats.

In exercised female rats, the elastin content of the thoracic and abdominal aorta decreased by 4-8% (p less than 0.05). The collagen content in the thoracic aorta, was unchanged but in the abdominal aorta was reduced by 5.2% (p less than 0.05). These results are discussed in connection with physical training.

Animals↗
PubMed1983

Genetic regulation of GM2 expression in liver of mouse.

GM2 containing NeuGc was found to be a major ganglioside in the liver of most inbred strains of mouse we have examined so far. They were DBA/2, C3H/He, C57BL/6, BALB/c, and CBA mice. However, WHT/Ht mouse does not contain a detectable amount of GM2 (NeuGc) but has GM3 containing NeuGc as the major ganglioside in the liver. The positive expression of GM2 (NeuGc) was demonstrated in the liver of F1 hybrids between WHT/Ht and DBA/2 mice, as one of the possible combinations. Moreover, the expression of GM2 (NeuGc) in the liver was proved to be an autosomal dominant trait by ganglioside analysis of 34 individual mice of the F2 and backcross generations. WHT/Ht mouse was demonstrated to be a recessive homozygote lacking GM2 (NeuGc) expression. During the analysis, interestingly enough, the enhanced elongation of the sugar chain in the gangliosides from GM2 (NeuGc) to GM1 (NeuGc) and GD1 was observed in the liver of F1 mice and this elongation was segregated only in half members of F2 and backcross generations.

Animals↗
PubMed1983

Expression of GM1 and GD1a in mouse liver is linked to the H-2 complex on chromosome 17.

GM2 containing NeuGc was a major ganglioside in the liver of most inbred strains of mouse; A/J (H-2a), C57BL/10 (H-2b), BALB/c (H-2d), C3H/He (H-2k), etc., but GM1(NeuGc) and GD1a(NeuGc) in addition to GM2(NeuGc) were detected in the liver of several strains such as SWM/Ms, SJL/J (H-2s), SL/QDJ (H-2s), SWR/J (H-2s), PL/J (H-2u), and RFM/Ms (H-2f) and a wild-derived strain as well, M. Cas-Qzn (H-2wc1, tentative designation). GM1(NeuGc) and GD1a(NeuGc) were also expressed in the liver of several strains of H-2 congenic mouse; B10. Cas-Qzn (H-2wc1), B10.S (H-2s), B10.G (H-2q), A.SW/Sn (H-2s), and C3H.JK (H-2j), although the respective inbred-partner strains had only GM2(NeuGc) as a major component. This difference of the ganglioside composition between H-2 congenic and inbred-partner strains suggests that a gene for expression of GM1(NeuGc) and GD1a(NeuGc) is closely linked to the H-2 complex. The locus was mapped at the left outside the H-2 complex on chromosome 17 by analysis of H-2 recombinant mice.

Animals↗
PubMed1983

Monoclonal antibodies to various morphologic components of human skin.

Somatic cell hybrids were established from the mouse myeloma, P3x63Ag8.653 cells, and the spleen cells of a mouse hyperimmune to human epidermal cells. Indirect immunofluorescence test with hybridoma culture fluids displayed that 253 out of 263 hybridoma cultures secreted antibodies reactive with the frozen sections of human skin. The hybridomas secreting unique antibodies to skin components were cloned and designated as AHS-1 to -8. Monoclonal antibodies (MoAb) from AHS-1, AHS-2, and AHS-3 hybridomas did detect cytoplasmic antigens present in the epidermal layer, eccrine ducts and glands (except MoAb AHS-1), and hair follicles. Enzyme-linked immunosorbent assay showed that the antigen recognized by either MoAb AHS-1 or MoAb AHS-2, but not by MoAb AHS-3, shares the antigenic determinant with antigen(s) present in keratin polypeptides isolated from human callus. MoAb AHS-4 to -8 distinctly stained each morphologic component of the skin tissues: cell membranes of epidermal cells by MoAb AHS-4, cytoplasms in upper layer cells of epidermis by MoAb AHS-5, dermis by MoAb AHS-6, basement membrane zone by MoAb AHS-7, and eccrine ducts by MoAb AHS-8.

Adolescent↗
PubMed1983

Serum erythropoietin titres in the anaemia of premature infants.

Erythropoietin (EPO) titres in the serum of premature infants were determined by an in vitro method using radioiron incorporation into haem in fetal mouse liver cells in culture. The serum EPO titres in 12 premature infants at birth were significantly lower than those of normal adults. In those premature infants who developed anaemia the serum EPO titres increased significantly by 4-6 weeks after birth, confirming that EPO production increases in premature infants in early days of life.

Adult↗
PubMed1983

Stimulation of rat autologous mixed lymphocyte reaction with xenogeneic sera and their protein preparations.

Autologous mixed lymphocyte cultures were set up from nylon non-adherent T-enriched lymphocytes and mitomycin C-treated spleen cells of individual ACI/N rats and the effect on the reaction (AMLR) of sera in the culture medium was studied with regard to the xenogeneic nature of the sera. Not only foetal calf serum, but also sera of adult human, horse and swine stimulated the AMLR response, but autologous or rat serum did not. Albumin fractions of these sera were also effective in inducing the AMLR response. Furthermore, the presence of xenogeneic serum in the culture medium was also required for the blastogenic response of AMLR-primed lymphocytes against the secondary stimulation with syngeneic spleen cells. Both autologous and xenogeneic sera, however, supported the Con-A response of the same responder cell population as used in the AMLR. These results substantiated our previous finding (Endho & Hashimoto, 1981) and suggest that two signals, one from autologous non-T cells and another from the xenogeneic factor in culture medium, are required to cause AMLR, at least in the rat system.

Animals↗