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Biomedical subjects

T Minagawa

Publications and source records attributed to T Minagawa.

At least 145 records · Page 8Linked to original sources
PubMed1982

Induction of alpha and beta interferons during the hyporeactive state of gamma interferon by Mycobacterium bovis BCG cell wall fraction in Mycobacterium bovis BCG-sensitized mice.

Characterization of interferon (IFN) induced by a second challenge with specific antigen was investigated during the development of hyporeactivity established after challenge of Mycobacterium bovis BCG-sensitized mice with BCG cell wall fraction (BCG-CW). When BCG-sensitized mice were challenged with BCG-CW, IFN-gamma was detected in the circulation 4 h later and rapidly disappeared. After IFN-gamma disappeared from their blood, mice became completely hyporeactive to the second challenge with BCG-CW for 1 day, and thereafter they recovered from this hyporeactive state. However, we always observed that IFN induced at first by the second challenge with BCG-CW during the hyporeactive state was type I IFN-alpha/beta, but thereafter was entirely IFN-gamma. Induction of IFN-alpha/beta by the specific antigen during restoration from the hyporeactive state in BCG-sensitized mice is discussed.

Animals↗
PubMed1982

Studies on spontaneous production of gamma-interferon in Behçet's disease.

Gamma-interferon (IFN-gamma) is detected at a higher level in the sera of patients with Behçet's disease than in control subjects. To investigate the cellular source of IFN-gamma, peripheral blood lymphocytes (PBL) from patients were cultured and found to produce IFN-gamma spontaneously in their fresh culture fluids. The average IFN titers in cultures of the patients' PBL were significantly higher than those of the control cultures (p less than 0.0001). The IFN activity was significantly higher in cultures of the patients in the ocular convalescent stage than in the exacerbation stage (p less than 0.0001), as was the case with serum interferon activity. Fractionation of PBL showed that only T gamma lymphocytes of the patients produced IFN-gamma spontaneously in the cultures. No IFN was produced in the culture fluids of T non-gamma cells, non-T cells or macrophages. T gamma cells and IFN-gamma may therefore play a significant role in the immunopathophysiology of Behçet's disease.

Behcet Syndrome↗
PubMed1981

Cellular source of interferon induced in human peripheral blood mononuclear leukocytes by mumps virus or by tumour cells persistently infected with mumps virus.

Human leukocyte interferon (IFN-a) was induced in cultures of human peripheral blood mononuclear leukocytes (PBML) from seropositive healthy donor infected by mumps virus, or by a human lung carcinoma cell line (Pc-10) persistently infected with mumps virus (Pc-10/M-V). Adherent cells (M0), non-T, non-B cells and B cells all produced IFN in response to mumps virus or Pc-10/MpV cells. The non-T, non-B cells co-cultured with Pc-10/MpV cells produced high-titred IFN. However, T cells did not produced any antiviral factors even in the presence of M0. Furthermore, T cells activated with phytohaemagglutinin (PHA-P), concanavalin A or treated with u.v.-irradiated mumps virus, or Pc-10/MpV cells pretreated with mitomycin C did not produce any antiviral factors in response to either mumps virus or Pc-10/MpV cells.

Carcinoma↗
PubMed1981

Enhancement of cytotoxicity of human peripheral blood lymphocytes by interferon.

Human lung carcinoma cells persistently infected with mumps virus (Pc-10/MpV) were lysed with human peripheral blood mononuclear leukocytes (PBML) obtained from seropositive donors who had anti-mumps virus-neutralizing antibody in their sera. This cellular cytotoxicity was due not to the cytotoxic T lymphocytes but mainly to the non-T, non-B cells, possibly related to natural killer (NK) cells. Moreover, it was concerned not with antibody against mumps virus antigens but with alpha-interferon (IFN-alpha) produced in the mixture of human PBML and Pc-10/MpV cells, since this cellular cytotoxicity was suppressed by anti-human IFN-alpha rabbit serum. Exogeneous IFN-alpha augmented the cytotoxicity of non-T, non-B cells, not T cells, for the uninfected Pc-10 cells. IFN-gamma that had been induced by heat-killed Listeria monocytogenes in PBML had the same capacity to augment NK activity did IFN-alpha.

Antibodies, Viral↗
PubMed1981

Alternative induction of IFN-alpha and IFN-gamma by Listeria monocytogenes in human peripheral blood mononuclear leukocyte cultures.

Production of interferon (IFN) by Listeria monocytogenes (LM) in human peripheral blood mononuclear leukocyte (PBML) cultures was studied. Acid-labile IFN-gamma was produced in Ficoll-Hypaque-purified mononuclear cell cultures in response to heat-killed LM (HK-LM). However, plastic dish (PD)-nonadherent cells produced acid-stable IFN-alpha, whereas the cells reconstituted with PD-adherent cells (M phi) and PD-nonadherent cells produced IFN-gamma by HK-LM, IFN-gamma was produced only in a mixture of SRBC rosette-forming (T) cells and M phi. Neither T cells nor M phi produced IFN by HK-LM. On the other hand, IFN-alpha was produced from non-T and nylon wool-nonadherent (non-T, non-B) cells by stimulation with HK-LM in the absence of M phi. A reciprocal type of IFN produced in human PBML was absolutely dependent on the presence or absence of M phi. A soluble fraction extracted from sonically disrupted LM had a high potential to induce IFN-gamma in human PBML. Possible mechanism of the alternative production of IFN-gamma or IFN-alpha in human PBML by Listeria are discussed.

Adult↗
PubMed1980

[Effect of motor cortex stimulation on recruitment pattern during reflex activity of fast and slow motor units in the cat (author's transl)].

In order to learn whether change of the fixed recruitment order is induced by the activity of motor cortex or not, the effects of motor cortex stimulation on stretch or vibration reflex of single motor units were examined in 43 motor units of the triceps surae muscle in cats. On the single alpha axon identified functionally there was observed two types of firing pattern in response to the muscle stretch; a phasic change and a tonic change in firing pattern. Then, according to the firing pattern, the fast or the slow motor units defined by the twitch contraction time was classified into the fast-phasic unit, the fast-tonic unit, the slow-phasic unit, and the slow-tonic unit. The axonal conduction velocity was significantly correlated with the reciprocal of twitch contraction time (r = 0.812, p < 0.001). Since the conduction velocity reflects the motoneuron size, larger motoneurons would correspond to the fast motor units and smaller ones to the slow units. By repetitive stimulation of the contralateral pericruciate cortex, the activities of the fast-phasic units were facilitated (11 units), those of the fast-tonic units were either facilitated (3) or inhibited (4), and those of the slow-tonic units were inhibited (24 units) except that only one slow-phasic unit was facilitated. Namely, larger motoneurons with higher conduction velocity had a shorter contraction time and a phasic discharge pattern, and were facilitated by the cortical stimulation, while the smaller ones with lower conduction velocity had the opposite properties. Further, the cortical control described above, were confirmed by the experiment which examined the simultaneous responses to the MG vibration of two or three axons in a natural filament of the MG nerve. These findings suggest that a stereotyped recruitment order according to the motoneuron size could be modified by the input system from the motor cortex.

Action Potentials↗
PubMed1979

Purification and some properties of deoxyribonuclease whose synthesis is controlled by gene 49 of bacteriophage T4.

An enzyme which specifically cleaves very-fast-sedimenting DNA of bacteriophage T4 is synthesized after infection of T4, and its synthesis is controlled by gene 49 [1,2]. This enzyme has been proved to be a DNase [2]. We have purified this DNase 3000-fold from extracts of E. coli infected with T4. The purified preparation was practically free from other DNases, and the DNase activity was not detectable in cells infected with a mutant defective in gene 49. The enzyme activity from cells infected with a temperature-sensitive mutant of gene 49 was also temperature-sensitive, suggesting strongly that gene 49 is a structural gene of the DNase. The molecular weight of the wild-type enzyme was estimated to be 50 x 10(3) by gel filtration chromatography. The purified DNase did not cleave native and denatured DNAs of T3 and T4, but cleaved renatured T3 DNA with enzymatically fragmented T3 DNA, indicating that gaps in the DNA duplex are structures susceptible to the DNase. Cleavage of the hybridized T3 DNA occurred when the fragmented DNA was phosphorylated at either the 3' or 5'-strand termini.

Deoxyribonucleases↗