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Biomedical subjects

T Munakata

Publications and source records attributed to T Munakata.

At least 55 records · Page 3Linked to original sources
PubMed1990

Enhancement of cytotoxicity of active macrophages by mycoplasma: role of mycoplasma-associated induction of tumor necrosis factor-alpha (TNF-alpha) in macrophages.

Tumor necrosis factor-alpha (TNF-alpha)-inducing activity of several mycoplasmas including Mycoplasma pneumoniae, a causative agent in human respiratory infectious diseases, was investigated. Purified peritoneal macrophages from BALB/c mice markedly enhanced their cytotoxic activity to Meth A cells, when cultured with either viable or non-viable mycoplasmas. The supernatants of the macrophage culture with mycoplasmas, M. pneumoniae and Acholeplasma laidlawii, showed the potent cytotoxic activity to TNF-alpha-sensitive L cells but not to TNF-alpha-insensitive L cells. Addition of anti-TNF-alpha antiserum inhibited completely the cytotoxic activity of these supernatants, indicating that a major part of the cytotoxic activity might be due to TNF-alpha. Various other mycoplasmas, either glucose- or arginine-utilizing species, as far as tested showed also the potent activity to produce TNF-alpha. These results strongly suggest the possibility that mycoplasmas possess the activity of TNF-alpha induction which might be responsible for a part of enhancement of cytotoxic activity of macrophages and resistance to infection with mycoplasmas in vivo.

Animals↗
PubMed1990

[31P nuclear magnetic resonance study of intrahepatic energy metabolism in acute liver failure].

Changes in phosphorus metabolites and intracellular pH in acute liver failure induced by D-galactosamine (GAL) were evaluated non-destructively and continuously using 31P-NMR spectroscopy. Furthermore, changes in these parameters under ischemia were also examined. GAL(1.0g/kg) was injected intravenously to male Wistar rats. NMR measurements in perfused livers were performed with a GX-270FT NMR spectrometer (JEOL). Typical changes in 31P-NMR spectra were observed after GAL administration. ATP levels decreased to 57.4 +/- 12.4% at 12 hours and to 65.4 +/- 7.7% at 24 hours after the administration compared with that in control rats. Pi levels increased remarkably to 632.1 +/- 76.4% at 3 hours and recovered to 127.5 +/- 22% at 24 hours. NAD+/NADH and UDP-sugar levels gradually increased to 253.5 +/- 33.4 and 456.3 +/- 60.9%, respectively, at 24 hours. In GAL treated livers, ATP levels fell rapidly and Pi levels rose correspondingly during ischemia, and they rapidly recovered by reperfusion. The intracellular pH decreased to 7.16 +/- 0.032 from 7.38 +/- 0.065 at 3 hours after GAL administration. However, significant changes in pH were not observed until 24 hours. In GAL treated livers, slight changes in pH were observed under ischemia. These results indicate that 31P-NMR is a useful method to evaluate the damage of acute liver failure, and to diagnose liver diseases involving the intrahepatic energy metabolism.

Acute Disease↗
PubMed1989

The socio-cultural significance of the diagnostic label "neurasthenia" in Japan's mental health care system.

This paper is an attempt to explore the socio-cultural significance of deliberately disguising schizophrenia as neurasthenia, neurosis or malfunction of autonomic nervous system. To understand its significance, the socio-cultural background of Japanese attitudes toward mental illness and Japan's mental health care system is also examined from a non-Western standpoint.

Anxiety Disorders↗
PubMed1989

Suppressive effect of interferon-beta-activated natural killer cells on lipopolysaccharide-induced B cell differentiation of MRL/Mp-lpr/lpr mice.

The suppressive effects of mouse recombinant interferon-beta (IFN-beta) on B cell differentiation of MRL/Mp-lpr/lpr (MRL/1) mouse, a model of autoimmune diseases, and C3H/H2 mice, a normal situation, were investigated. Spleen mononuclear cells were cultured in the presence of lipopolysaccharide (LPS), and the suppressive effect of IFN-beta was examined on differentiation of B cells to plaque-forming cells (PFCs) by highly sensitive reversed hemolytic plaque assay. IFN-beta (5,000-10,000 units/ml) suppressed more than 50% of PFCs of both MRL/1 and C3H/H2 mice. This suppressive activity as well as the cytotoxicity of natural killer (NK) cells enhanced by IFN-beta was abrogated by treatment of the spleen cells with anti-asialo GM1 antibody in the presence of complement. This suppressive activity was also abrogated by intravenous administration of 20 microliter/mouse of anti-asialo GM1 12 hr before cultivation of spleen cells. These results suggest that NK cells activated by IFN might be responsible for the immunoregulation in autoimmune diseases.

Animals↗
PubMed1989

[Induction by mycoplasmas of tumor necrosis factor-alpha from macrophages].

Several species of mycoplasmas including M. pneumoniae, the causative agent of human respiratory infection, were investigated for tumor necrosis factor-alpha (TNF-alpha) induction. The cytotoxic activity to Meth A cells of peritoneal macrophages purified from BALB/c mice was enhanced markedly when cultured with either viable or nonviable mycoplasmas. The supernatant of macrophage culture mixed with mycoplasmas, M. pneumoniae or A. laidlawii, showed a potent cytotoxic activity to TNF-alpha-sensitive but not to TNA-alpha-insensitive L cells. Addition of anti-TNA-alpha antiserum inhibited completely the cytotoxic activity of the supernatant, indicating that the cytotoxic activity is due mostly to TNF-alpha. These results strongly suggest that mycoplasmas possess an activity to induce TNF-alpha, which enhances the cytotoxic activity of macrophages and prevent infection with mycoplasmas in vivo.

Animals↗
PubMed1988

Role of CD8 (Lyt-2) in cytotoxic T-cell function. Analysis of variants of a cytotoxic T-cell clone with reduced Lyt-2 expression.

The role of CD8 (Lyt-2) in the function of a long-term cytotoxic T-cell (CTL) clone (Cl96) was analysed. Previous studies had shown that C196 cells utilize the alpha beta T-cell receptor and depend on Lyt-2 to recognize and lyse P815 mastocytoma target cells. Recognition is H-2Kd-restricted, presumably involving a P815 specific antigenic structure. Here we analyse a number of variants selected from Cl96 that have reduced or virtually abolished expression of Lyt-2, alone or in combination with other deficiencies. We studied the ability of these variant cells to lyse either P815, a process requiring both specific antigen recognition and triggering of cytolytic function, or to lyse the anti-CD3 hybridoma 145-2C11, a process that requires the triggering of cytolytic function only. The results shows that in the case or a permanently activated CTL effector cell such as Cl96, Lyt-2 is required for antigen recognition but is not essential for the triggering of cytotoxicity.

Animals↗
PubMed1987

Induction of interferon production by natural killer cells by organogermanium compound, Ge132.

Interferon (IFN)-inducing activity of the organogermanium compound Ge132 in human peripheral mononuclear cells was investigated. By using Percoll discontinuous density gradient centrifugation, peripheral blood nonphagocytic and nonadherent mononuclear cells were divided into the low-and high-density fractions. Natural killer (NK)-enriched low-density fractions, but not the T-cell-enriched high-density fractions, showed IFN production by the stimulation of Ge132. The maximal titer of IFN by NK-enriched fractions (F1 + F2) was observed after a 74-h cultivation in the presence of 200 micrograms/ml Ge132. IFN production by the NK-enriched fractions was abrogated by treatment of the cells with monoclonal antibody against human NK cells in the presence of complement. The treatment with antiserum-neutralizing human IFN-gamma resulted in a marked reduction, indicating that a major part of IFN was IFN-gamma. These results suggested that Ge132 might possess affinity to NK cells, inducing IFN production by NK cells.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1986

Suppressive effect of human natural killer cells on Epstein-Barr virus-induced immunoglobulin synthesis.

The suppressive effect of human natural killer (NK) cells on Epstein-Barr virus (EBV)-induced immunoglobulin (Ig) synthesis by autologous B cells was investigated. By Percoll discontinuous density gradient centrifugation, low-density fractions enriched for NK cells were isolated from human peripheral blood lymphocytes. These NK-enriched fractions were added to purified autologous B cells in the presence of EBV, were cultivated for 8 days, and were examined for their suppressive effect on Ig synthesis by an enzyme-linked immunosorbent assay. The fractions markedly suppressed both IgM and IgG synthesis induced by EBV. It was possible to reduce the suppressive effect of NK-enriched cells by complement-dependent lysis of NK cells and Leu-11, but not by OKT3 monoclonal antibody, indicating that NK cells may be responsible for the suppression of Ig synthesis. Upon close examination of interferon (IFN) activity, it was revealed that the co-cultures of NK-enriched cells and EBV-infected B cells generated production of IFN-alpha, which might be produced by NK cells in response to EBV-stimulated B cells. Addition of anti-IFN-alpha but not anti-IFN-gamma serum almost completely abrogated the suppressive effect of NK-enriched cells on Ig synthesis, indicating that IFN-alpha produced are required for the NK cell-mediated suppression of Ig synthesis. However, addition of IFN-alpha into purified B cells showed no direct suppressive effect on EBV-induced Ig synthesis by B cells in the absence of NK cells. Nevertheless, NK cells when previously incubated with IFN-alpha and added to B cells showed a suppressor activity on Ig synthesis to a level higher than that of untreated NK controls. These results strongly suggest the possibility that NK cells display an interaction with EBV-infected B cells and produce IFN-alpha, which in turn activates NK cells. These activated NK cells suppress the Ig synthesis by B cells, which undergo transformation induced by EBV.

Antibodies, Monoclonal↗
PubMed1986

Sociocultural background of the mental health system in Japan.

Japan is not among the countries with a high ratio of beds and admissions into psychiatric hospitals to total population, but the average length of hospitalization in Japan is among the longest in the world. The ie characteristic of Japanese culture has taken care of the elderly and the mentally disturbed even though it regarded them as a nuisance, thus serving to keep the number of beds and admissions in Japan lower than in Western countries. But those treated as a nuisance who sever all face-to-face ties upon being admitted to hospitals tend to be expected culturally to regard the hospitals as their homes, thus prolonging the length of their hospitalization.

Community Mental Health Services↗