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Biomedical subjects

Y Hirota

Publications and source records attributed to Y Hirota.

At least 595 records · Page 33Linked to original sources
PubMed1975

Diverse effects of bursectomy on humoral immune responses in the chicken.

Chickens bursectomized hormonally or surgically at various ages in embryonic to postembryonic lives were immunized with a mixture of antigens, and the antibodies produced titrated. immune responses to Salmonella pullorum (SP), Brucella abortus (BA). Staphylococcus aureus (Staph) and ovalbumin (OA) were more markedly suppressed by the bursal deprivation than those to heterogenous erythrocytes, viruses and such bacteria as Pasteurella multocida (PM) and Escherichia coli B. The immune response to bovine serum albumin (BSA) was on a level between the two groups. Hormonal bursectomy in embryonic life permitted chickens immunized with sheep red blood cells (SRBC) to produce antibody of the IgM type but not of the IgG type. In surgically bursectomized chickens IgG but not IgM production was inhibited. Chickens hormonally bursectomized on the third day of egg incubation produced IgM to a level higher than the normal chickens in contrast with the suppressed IgG production. Such diversity in the bursal influences on antibody responses was discussed in relation to ontogeny of the humoral immune system.

Animals↗
PubMed1975

Protective effect of coexistent thiamine deficiency upon the experimental cardiomyopathy associated with acute magnesium deficiency in the Syrian golden hamster.

Repeated efforts to induce beriberi heart disease by experimental thiamine deficiency (B1d) have failed in many species. To test the hypothesis that magnesium deficiency (Mgd) might be the cofactor necessary for heart failure, 10-week-old Syrian golden hamsters were divided into four groups-control (C), B1d, Mgd, and combined MgB1d-and were fed the diets ad libitum for 3 weeks. On day 21, animals were studied under intraperitoneal pentobarbital anesthesia (50 mg/kg). Electrocardiograms were taken and right and left ventricular pressures were measured by transthoracic needle puncture. Cardiac output was measured by the direct Fick method. The complete study was performed in 9 C, 13 B1d, 9 Mgd, and 14 MgB1d animals. B1d was proven by low red blood cell transketolate high B1 pyrophosphate effect, and was accompanied by tachycardia and hypercalcemia. B1 did not differ from C in any other parameter. Mgd was characterized by hypomagnesemia, hypercalcemia, prolongation of the PR interval, widening of the QRS interval, low O2 consumption, low cardiac output, and increased heart weight to body weight ratio (HW/BW) as compared to control. No differences were observed in right and left ventricular pressures or peak /dt. MgB1d was characterized by hypomagnesium, hypercalcemia, low red blood cell transkeotlase, and high B1 pyrophosphate effect. MgB1d minimized the deleterious effects of Mgd: animals were more active and the mortality was low, the PR interval remained normal, the QRS interval widened significantly less, cardiac output remained normal, and HW/BW increased significantly less. Although, once again, beriberi heart disease was not produced, B1d appeared to exert a protective effect upon the Mg-deficient myocardium.

Acute Disease↗
PubMed1973

Process of cellular division in Escherichia coli: physiological study on thermosensitive mutants defective in cell division.

Thermosensitive fts mutants of Escherichia coli belonging to seven previously identified genetic classes (ftsA to ftsG) were studied from a physiological standpoint. These mutants immediately stopped dividing and formed multinucleated filaments when the temperature was shifted to 41 C. Macromolecular syntheses (deoxyribonucleic acid), ribonucleic acid, cell mass, and murein) continued exponentially for at least 40 to 120 min. The number of surviving bacteria remained constant during the time of incubation, and this number began to decrease exponentially, as the rate of cell mass increase leveled off from the initial rate. The recovery of cell division at 30 C in these filamentous cells was studied after 60 min of incubation at 41 C. The existence of three types of mutants was shown. The ftsA and ftsE mutants resumed cell division without new protein synthesis; ftsD mutants resumed cell division only if new protein synthesis occured, while ftsB, C, F and G mutants did not resume cell division at all. No alteration in the cell envelope was detected by the method used here, although the ftsA, B, D, F and G mutations, in contrast with ftsC and E, caused an increased resistance to penicillin G. It was also shown that the recA mutation did not suppress the effect of the fts mutations and that none of the lysogenic fts mutants induced prophage multiplication while forming filaments. The effects of osmotic pressure and salts which rescue the mutant phenotype is described.

Bacterial Proteins↗