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Biomedical subjects

N Osawa

Publications and source records attributed to N Osawa.

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

Use of cycloheximide on intracellular growth of Mycobacterium leprae in cultured murine macrophages.

Mycobacterium leprae is an obligate intracellular parasite and grows within mononuclear phagocytes. When murine macrophages derived from the peritoneal cavities of CBA mice were infected in vitro with M. leprae (Thai-53 strain), intracellular multiplication was observed three weeks after infection. On the other hand, there was no increase in the number of heat-killed M. leprae at the same times after infection. Morphological studies showed that the growth rate of the bacteria increased by about 20-30% in medium supplemented with cycloheximide. With the addition of cycloheximide to the culture medium, metabolic activity of macrophages was decreased but infected cells were maintained in good condition and seldom floated off from the culture flask.

Animals↗
PubMed1991

Intracellular fate of Mycobacterium leprae in cultured murine macrophages in 24-well trays.

Mycobacterium leprae is an obligate intracellular parasite which grows within mononuclear phagocytes. In clinical cases, M. leprae reaches enormous numbers in the macrophage-rich granulomas of leprosy. Peritoneal macrophages from CBA mice were cultured in Waymouth medium containing fresh horse serum in Costar 3424 trays (24 wells, 16 mm in diameter) each containing 9 x 12 mm cover slips. This medium was supplemented with 0.5 micrograms/ml of cycloheximide. These cells were infected with M. leprae Thai-53 strain obtained by nude mice inoculation. Significant multiplication of the acid-fast bacilli in the macrophages was observed three weeks after inoculation. This experiment showed M. leprae mainly multiplied in cells and not by rephagocytization of M. leprae derived from destroyed cells.

Animals↗
PubMed1989

Functional difference in monoamine transmitters in the behaviorally abnormal mouse mutant (wriggle mouse sagami).

A mutant mouse (wriggle mouse sagami, WMS) with neurological disorders was found in a colony of the BALB/c strain. The clinical signs included tremor, dystonia and involuntary movements. The concentrations of the neurotransmitter substances, noradrenaline (NA), dopamine (DA), 5-hydroxytryptamine (5-HT) and acetylcholine (ACh), were measured simultaneously with their metabolites in dissected brain regions by high-performance liquid chromatography with electrochemical detection. The turnover of 5-HT was significantly higher in the cerebral cortex, hippocampus, hypothalamus, midbrain and pons-medulla of WMS than of the genetic control, BALB/c. The intrastriatal DA and its metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid were increased. However, there was no evidence to suggest an increase in turnover rate of this neurotransmitter. An increase in concentration of and decrease in turnover rate of NA were observed in the cerebellum of this mutant. These findings suggest that multiple disturbance of the neurotransmitter system was largely responsible for the manifestation of the clinical signs of WMS.

Acetylcholine↗
PubMed1989

Possible role of Streptococcus pyogenes in mucocutaneous lymph node syndrome. VIII. Immunological tolerance to S. pyogenes-associated antigens seems essential to induction of MCLS.

In our previous studies, we attempted to show that new-born mice infected with an attenuated strain of Streptococcus pyogenes, and exposed to streptococcal antigens approximately one month later, failed to develop a humoral response to those antigens but were able to respond normally to other unrelated antigens. Since such immunological characteristics are identical to those of patients with the mucocutaneous lymph node syndrome (MCLS), the present studies were performed with the aim of assessing the antibody-forming activities of peripheral blood lymphocytes collected from MCLS patients. These lymphocytes were cultured in the presence of pokeweed mitogen, streptolysin-O and streptococcal C-polysaccharide, leading to their refractoriness to S. pyogenes-associated antigens coupled with normal responsiveness to unrelated antigens. The implication of such immunological responsiveness elicited from neonatal exposure to streptococcal antigens is discussed, particularly with reference to the induction of MCLS.

Antibody Formation↗
PubMed1989

Possible role of Streptococcus pyogenes in mucocutaneous lymph node syndrome. IX. Quantitation by ELISA of streptococcal pyrogenic exotoxin in the serum of MCLS patients.

In the present paper we describe the use of an enzyme-linked immunosorbent assay reinforced with an introduction of monoclonal antibody, for the detection and quantitation of streptococcal pyrogenic exotoxin (SPE) in the serum of patients with mucocutaneous lymph node syndrome (MCLS). The amount of SPE was usually at a high level, and its 100% incidence in patients' sera was proved whenever the assay was made on the day of admission, thereby showing a marked contrast to carefully matched control sera which failed to mediate any positive result. As for the change in detected amount of the toxin, a clear dichotomy was observed between the serum of gammaglobulin-treated patients and that of infants given aspirin; in the former the positive result turned to negative rapidly following the initiation of treatment coupled with a defervescence, while in the latter the reduction of SPE levels was scarcely monitored for as long as 17 days after the onset of illness. Quantitation of SPE might be an auxiliary test for the diagnosis of MCLS, because a considerable amount of SPE was assessed in a patient who developed characteristic huge coronary artery aneurysms following an illness which did not fulfill the diagnostic criteria. These findings support our speculation in relation to the certain role of S. pyogenes as an etiological agent for MCLS. The possible mechanisms of gammaglobulin treatment in reducing the prevalence of cardiovascular lesions and the duration of systemic inflammation are discussed.

Animals↗
PubMed1980

Anti-HLA-A, B, C and DR antibodies in renal transplant recipients.

Anti-HLA-A, B, C and DR antibodies in 173 sera derived form renal transplant recipients were examined, using the cytotoxicity techniques standardized at the 8th International Histocompatibility Workshop. About 50% of sera obtained within 6 months of transplantation showed anti-HLA-DR antibodies. Thereafter, serum anti-DR antibodies were found in about 30% of the examined sera. However, at more than 3 years after transplantation, the reappearance of anti-DR antibodies was noted in more than 60% of the examined sera. Anti-HLA-A, B and C antibodies were not found except in the sera from recipients with irreversible rejection. The post-transplant production of anti-DR antibodies against incompatible donor HLA-DR antigens was confirmed in sera derived repeatedly from the same patients.

Adult↗