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Biomedical subjects

Y Hirota

Publications and source records attributed to Y Hirota.

At least 505 records · Page 28Linked to original sources
PubMed1980

A simple method for detecting cells producing antibodies of specific immunoglobulin classes in the chicken.

A simple plaque method for detecting cells producing antibodies of specific immunoglobulin class in the chicken is described. This method is based upon the inability of chicken antibody to activate guinea-pig complement. IgM- and IgG-specific plaque-forming cells in the spleen of chickens immunized with sheep red blood cells were detected using guinea-pig complement and rabbit anti-chicken-mu- or gamma-chain serum. The specificity of the immunoglobulin class of plaques was confirmed by the abolition of class-specific hemolytic plaques after treatment of the lymphoid cells with rabbit antisera specific for chicken heavy chains in the presence of guinea-pig complement. The method is very simple and rapid, and IgM and IgG specific plaques are reliably detected.

Animals↗
PubMed1980

On the process of cellular division in Escherichia coli: isolation and characterization of penicillin-binding proteins 1a, 1b, and 3.

Multiple mutants of Escherichia coli defective in penicillin-binding proteins (PBPs) were constructed, and into these strains Co1E1 plasmids carrying the genes for PBP-1a, -1b, or -3 were introduced. From these plasmid-carrying strains, PBP-1a and -1b were purified by ampicillin-Sepharose affinity chromatography and PBP-3 by cephalexin-Sepharose affinity chromatography. Improved purification was achieved by differential elution with NH2OH. Purified PBP-1b synthesized murein when added to the membrane fraction of a PBP-1b-defective mutant, which by itself failed to support murein synthesis in vitro. The PBP-1b preparation was able to synthesize murein from the lipid intermediate extracted with chloroform/methanol but was unable to utilize UDP-linked precursors for murein synthesis. Murein synthesis was inhibited by vancomysin, ristocetin, moenomycin, and enduracidin, but not by beta-lactam antibiotics. The synthesized murein was shown to contain crosslinked muropeptides. Their crosslinking was abolished by action of beta-lactam antibiotics. The PBP-1a and -3 preparations showed substantially no activity for murein synthesis in the same reaction system. None of the three PBPs showed D-alanine carboxypeptidase activity with UDP-N-acetylmuramoyl-pentapeptide as substrate or endopeptidase activity with bis(disaccharide-peptide) as substrate.

Bacterial Proteins↗
PubMed1980

A mutant of Escherichia coli defective in penicillin-binding protein 5 and lacking D-alanine carboxypeptidase IA.

A mutant of Escherichia coli defective in penicillin-binding protein 5 activity was isolated. The mutation (pfv) was shown to be located at 14.0 min on the E. coli chromosome map. Loss of penicillin-binding protein 5 in the pfv mutant was associated with the loss of D-alanine carboxypeptidase IA activity and increased sensitivity to beta-lactam antibiotics. We conclude that penicillin-binding protein 5 catalyzes the major D-alanine carboxypeptidase IA activity and that the enzyme activity, in vivo, protects E. coli cells from killing by low inhibitory concentrations of beta-lactam antibiotics.

Bacterial Proteins↗
PubMed1980

A clinical study of left ventricular relaxation.

Left ventricular (LV) relaxation was studied in patients with hypertrophic cardiomyopathy (HCM, n =18), congestive cardiomyopathy (CCM, n = 11), hypertensive heart disease (HHD, n = 8), coronary artery disease (CAD) without left ventricular (LV) asynergy (n = 9) and with LV asynergy (n =17), mitral stenosis (MS, n = 16), and mitral regurgitation (MR, n = 8). The time constant T and peak negative dP/dt were used as indexes of LV relaxation, and 18 normal subjects served as controls. The time constant T was higher in elderly patients among normal contros (r = 0.652, p < 0.01), which suggests that prolongation of relaxation is a phenomenon of aging. The normal value of the time constant T was 33 +/- 8 msec (mean +/- SD), and that of peak negative dp/dt was 1864 +/- 390 mm Hg/sec. The time constant T was significantly higher in HCM (64 +/- 20 msec), CCM (56 +/- 14 msec), CAD without asynergy (53 +/- 16 msec), CAD with asynergy (57 +/- 13 msec) and MS (47 +/- 12 msec). Peak negative dP/dt was significantly lower in HCM (998 +/- 303 mm Hg/sec), CCM (1060 +/- 334 mm Hg/sec), CAD with asynergy (1370 +/- 299 mm Hg/sec), MS (1367 +/- 313 mm Hg/sec) and MR (1139 +/- 305 mm Hg/sec). Although the genesis of LV relaxation abnormality is not clear from this investigation, it seems to have multiple causes. Relaxation abnormality seems to be one of the earliest manifestations of mechanical dysfunction of the human left ventricle.

Adult↗
PubMed1980

Chemical carcinogen-induced transplantable fibrosarcomas in histocompatible chickens. II. Effect of age and thymectomy on tumor incidence.

The incidence of primary fibrosarcoma 2-4 months after im injection of 7,12-dimethylbenz[a]anthracene (DMBA) was studied in normal, neonatally thymectomized and bursectomized SC (B2/B2) chickens. The tumor incidence was not significantly increased in thymectomized chickens inoculated at 1 week of age, but thymectomized animals inoculated at 4 weeks of age developed a higher incidence of tumors than did controls. Bursectomy did not affect tumor induction. Whereas thymectomy and bursectomy clearly reduced T- and B-cell immune responses, respectively, neither the carcinogen nor the presence of tumor had a detectable effect on the immune response. The effect of varying the age of chickens at the time of carcinogen injection was also studied. DMBA injected into chickens at 8-12 weeks of age produced a significantly lower incidence of tumors than did a similar dose of DMBA injected into chickens at 1-4 weeks of age. Thus DMBA-induced tumors in the chicken may present an interesting model for studies on immune surveillance.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1980

The development of unusual B-cell functions in the testosterone-propionate-treated chicken.

Chickens were treated with 4 mg of testosterone propionate on the twelfth day of embryonic life. Bursal remnants of testosterone-treated chickens were very small in size and had very few or no bursal follicles: the lymphoid tissue was replaced substantially by fibrosis. Testosterone-treated chickens formed almost exclusively IgM antibodies to sheep red blood cells and influenza virus, whereas no IgM or IgG response to Brucella abortus or Salmonella pullorum, and no IgG response to sheep red blood cells was demonstrable. Surgical removal of bursal remnants of testosterone-treated chickens at hatching did not significantly affect IgM response to sheep red blood cells. These B-cell functions of testosterone-treated chickens were not improved by addition of T cells, as shown by adoptive cell transfer experiments. Thus, there appears to be an unusual type B-cell development which is independent of the bursa of Fabricius.

Animals↗
PubMed1980

The B-cell development independent of the bursa of Fabricius but dependent upon the thymus in chickens treated with testosterone propionate.

Spleen cells taken from chickens treated with testosterone propionate, surgically bursectomized and immunized, were treated with anti-bursa-cell antiserum in the presence of complement, and transferred together with the mixed antigens into immunodeficient chickens. The recipient chickens showed restored capacity for antibody response to sheep red blood cells. In contrast, adoptive immune responses by spleen cells from normal chickens were abolished by treating with anti-bursa-cell antiserum in the presence of complement. These findings indicate that antibody-forming cells in TP-treated chickens do not bear cell-surface antigens specific for bursa cells; Testosterone-treated chickens were thymectomized at 7 days of age and immunized with the mixed antigens; the chickens thus treated were not able to produce antibodies. Thymocytes and thymus-derived cells taken from normal chickens were transferred into the testosterone-treated and surgically thymectomized chickens; but the antibody responses were not restored, indicating that absence of antibody formation in testosterone-treated, thymectomized birds is not due to lack of T cells as such. This result was confirmed by using adoptive transfer of B cells taken from testosterone-treated chickens together with T cells.

Animals↗
PubMed1980

[Vaginal smears of malignant ovarian tumors: comparison with cervical canal, aspirate uterine corpus, ascites, imprint smears and cytomorphology of histological specimens (author's transl)].

Vaginal smears of 21 patients with malignant ovarian tumors were examined. In 5 cases malignant cells were present: 1 mucinous cystadenocarcinoma, 2 poorly differentiated adenocarcinomas, 1 clear cell carcinoma, and 1 adenoid squamous cell carcinoma arising in a dermoid cyst. Cytomorphology of tumor cells in tissue specimens and imprint, ascites, aspirate uterine corpus, cervical canal and vaginal smears were examined. The ovarian malignant cells of the vaginal smears were grouped, round or oval with eccentric round or oval nuclei having a finely granular chromatin pattern regularly distributed, and with vesicular or vacuolated cytoplasm. Tumor diathesis appeared in 1 of 5 cases. Two post-menopausal patients showed an increase of superficial cells in the maturation index. In the comparison of malignant cells taken from different locations, vaginal tumor cells were similar to those in ascites. Since ascites smears were reported to be useful for the diagnosis of some kinds of ovarian tumors, it was expected that vaginal smears might also have this potentiality.

Adult↗