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Biomedical subjects

T Minagawa

Publications and source records attributed to T Minagawa.

At least 91 records · Page 5Linked to original sources
PubMed1990

Suppression of host resistance against Listeria monocytogenes infection by 15-deoxyspergualin in mice.

The effects of 15-deoxyspergualin (DSG), an immunosuppressive agent, on host resistance against Listeria monocytogenes were studied in mice. Administration of DSG in the early phase of infection resulted in fatal listeriosis by preventing acquired anti-listerial resistance, even though the infectious dose was sublethal for the untreated controls. In contrast, DSG treatment started after development of the acquired immunity was ineffective. Endogenous production of interferon-gamma (IFN-gamma) and tumour necrosis factor (TNF) in the bloodstreams induced by the infection was normal in DSG-treated mice. Nevertheless, augmentation of macrophage functions such as expression of major histocompatibility complex (MHC) class II antigens, phagocytic activity and listericidal activity induced by the infection was abrogated by DSG treatment. These results suggest that the inhibitory effect of DSG on anti-listerial resistance might be different from cyclosporine A (CsA).

Animals↗
PubMed1989

Synergistic action of three recombination gene products of bacteriophage T4, uvsX, uvsY, and gene 32 proteins.

Previously we proved that uvsX protein catalyzes reactions similar to those thought to occur during T4 recombination (Yonesaki, T., Ryo, Y., Minagawa, T., and Takahashi, H. (1985) Eur. J. Biochem. 148, 127-134; Yonesaki, T., and Minagawa, T. (1985) EMBO J. 4, 3321-3327). Now we have found that uvsY protein stabilizes binding of uvsX protein and single-stranded DNA and weakly stimulates those reactions catalyzed by uvsX protein, although it has little activity, if any, by itself. Gene 32 protein also stimulates them weakly at low concentrations, but is strongly inhibitory at high concentrations (Yonesaki, T., and Minagawa, T. (1985) EMBO J. 4, 3321-3327; Formosa, T., and Alberts, B. M. (1986) J. Biol. Chem. 261, 6107-6118). This inhibition is counteracted by uvsY protein. The highest efficiency of uvsX protein is achieved by the co-existence of a small amount of uvsY protein and a large amount of gene 32 protein. We discuss the mechanism and the role of the three proteins in recombination.

Adenosine Triphosphate↗
PubMed1989

Human tumor necrosis factor increases the resistance against Listeria infection in mice.

The resistance in mice against Listeria infection was augmented by treatment with recombinant human tumor necrosis factor (TNF). To elucidate this phenomenon, we examined the effect of TNF on macrophage activation. TNF-treated macrophages had listericidal activity in vitro and superoxide anion production. In addition, macrophage migration was inhibited in the presence of TNF. Therefore, activation of macrophages by TNF was similar to activation by macrophage-activating factor or macrophage-migration-inhibitory factor.

Animals↗
PubMed1989

Detection of high levels of immunoreactive human beta-1 interferon in sera from HIV-infected patients.

We have examined human interferon beta-1 (HuIFN-beta 1) levels in the sera from patients with various diseases by using a newly developed highly sensitive enzyme-linked immunosorbent assay system (ELISA). High levels of HuIFN-beta 1 were detected in the sera from Human Immunodeficiency Virus-I (HIV-I) infected patients, especially of asymptomatic carriers. The serum level of HuIFN-beta 1 may be a good indicator of HIV-I infection and of other immunological disorders.

AIDS-Related Complex↗
PubMed1989

Interactions between endogenous gamma interferon and tumor necrosis factor in host resistance against primary and secondary Listeria monocytogenes infections.

Intravenous injection of rat anti-mouse gamma interferon (IFN-gamma) monoclonal antibody as well as rabbit anti-mouse tumor necrosis factor (TNF) antibody into mice which had received a sublethal infection with Listeria monocytogenes cells resulted in acceleration of listeriosis. Endogenous IFN-gamma seemed to be produced early in infection, because suppression of antilisterial resistance was significant when a single injection of anti-IFN-gamma monoclonal antibody was given on day 0 or day 1 of infection. Production of TNF but not of IFN-gamma in the bloodstream early in infection was inhibited by administration of anti-IFN-gamma monoclonal antibody. The suppressive effect of anti-IFN-gamma and anti-TNF antibodies on antilisterial resistance was not augmented by simultaneous administration of these antibodies. On the other hand, in the secondary infection, simultaneous administration of anti-IFN-gamma and anti-TNF antibodies, but not of either of these antibodies alone, into L. monocytogenes-immune mice resulted in high mortality and explosive multiplication of bacterial cells in the spleens and livers. These results suggest that endogenously produced IFN-gamma and TNF are both essential to the host defense against L. monocytogenes infection and that these cytokines might act by different modes between the primary infection and the secondary infection.

Animals↗
PubMed1989

Recombinant murine gamma interferon induces enhanced resistance to Listeria monocytogenes infection in neonatal mice.

Neonatal mice within 24 h of birth were highly susceptible to intraperitoneal infection with Listeria monocytogenes. The 50% lethal dose of bacterial cells was 6.3 X 10(1) CFU for neonates and 3.2 X 10(6) CFU for adult mice. A single injection of recombinant murine gamma interferon (rMuIFN-gamma) protected neonatal mice from simultaneous challenge with a lethal dose of L. monocytogenes cells. The rMuIFN-gamma effect was dose dependent: protection was consistently observed in mice treated with rMuIFN-gamma at doses of more than 4 X 10(2) U (0.1 microgram of protein) per mouse. Bacterial growth in the spleens and livers of rMuIFN-gamma-treated neonates was significantly suppressed in comparison with that in the nontreated controls. The infected neonatal mice showed acquired antilisterial resistance against secondary intravenous infection after 4 weeks of age, and this resistance was significantly augmented in mice that had been treated with rMuIFN-gamma.

Adjuvants, Immunologic↗
PubMed1988

Suppression of delayed-type hypersensitivity in mice pretreated with diethylstilbesterol: involvement of sex hormones in immunomodulation.

Delayed-type hypersensitivity (DTH) responses were suppressed in female mice treated with diethylstilbesterol (DES), a synthetic nonsteroidal compound possessing estrogenic activity, but not in male mice. Upon analysis of this DTH-suppression in DES-treated female mice by use of the macrophage migration inhibition (MI) assay, an in vitro correlate of DTH, suppressor adherent cells (i.e., macrophages) in the peritoneal cavity were found to play an important role in this DTH suppression. On the other hand, DES-induced suppression was observed in surgically castrated male mice with depressed plasma testosterone (TS) levels, but not in TS-treated female mice or in castrated male mice, which suggests that TS inhibited the DES suppression. These results provide evidence that DTH response may be modulated by sex hormones.

Adjuvants, Immunologic↗
PubMed1988

Function of cloned T4 recombination genes, uvsX and uvsY, in cells of Escherichia coli.

Genes uvsX and uvsY of bacteriophage T4 both control genetic recombination and repair of damaged DNA, and their mutant phenotypes bear a striking resemblance to each other. It has been shown recently that the uvsX gene product is analogous to the recA gene product of Escherichia coli (Yonesaki et al. 1985; Yonesaki and Minagawa 1985; Formosa and Alberts 1986), but the function of the uvsY gene is unknown. To obtain further insight into the function of these genes we introduced plasmidborne copies of the two genes separately or together into E. coli. The uvsX gene rendered recA- cells more resistant to UV and raised the recombination frequency of lambda phage and E. coli, but hampered induction of the lambda prophage and the SOS function of E. coli. The uvsY gene had no detectable function when introduced alone into E. coli but significantly enhanced the function of the uvsX gene when the two plasmid-borne genes were introduced together.

Cloning, Molecular↗
PubMed1988

In vitro and in vivo recombination-related reactions of Escherichia coli recA protein and glucosyl-hydroxymethyl-deoxycytidine DNA.

Recombination of T4 phage is not controlled by the host recA gene but by an analogous phage gene, uvsX. We have tested the hypothesis that recA protein is inactive in T4-infected cells because it is unable to catalyze reactions involving single stranded DNA containing glucosyl-hydroxylmethyl-deoxycytidine. We found, however, that with modified and unmodified deoxycytidine containing DNAs, uvsX protein and recA protein catalyze in vitro reactions related to DNA recombination, but in T4-infected cells recA protein fails to promote strand transfer of DNA which contains unmodified deoxycytidine.

DNA, Bacterial↗
PubMed1988

Endogenous tumor necrosis factor (cachectin) is essential to host resistance against Listeria monocytogenes infection.

During a sublethal murine infection with Listeria monocytogenes cells, tumor necrosis factor (TNF) activity was detectable in neither sera nor spleen homogenates at any stage of the infection when a bioassay with L-929 cells (less than 4 U/ml) was used. However, injecting the mice with an immunoglobulin fraction obtained from a rabbit hyperimmunized with recombinant murine TNF-alpha resulted in acceleration of listeriosis. When 1 mg of anti-TNF antibody was injected per mouse, all the mice died from listeriosis, even though the infectious dose was sublethal for the untreated controls. The antigen-specific elimination of the bacterium from the spleens and livers of anti-TNF antibody-treated mice was delayed, depending on the dose of the antibody injected. Endogenous TNF seemed to be produced early in infection, because suppression of antilisterial resistance was significant when a single injection of anti-TNF antibody was given between day zero and day 2 of infection. The effect of endogenous TNF on antilisterial resistance was due to neither regulation of alpha interferon (IFN-alpha) and IFN-gamma production nor induction of IFN-beta subtype 1 (IFN-beta 1), because anti-TNF antibody treated-mice produced normal levels of IFN-alpha and IFN-gamma in the bloodstream during infection and administration of monoclonal anti-murine IFN-beta 1 antibody had no effect on the development of listeriosis. Alternatively, the listericidal activity of peritoneal macrophages of L. monocytogenes-infected mice could be abrogated by injection of anti-TNF antibody in vivo. These results suggest that the lower level of TNF is produced endogenously in mice that received L. monocytogenes infection and that it plays an essential role in the host defense against L. monocytogenes infection.

Animals↗
PubMed1988

Prevention by gamma interferon of fatal infection with Listeria monocytogenes in mice treated with cyclosporin A.

The significance of interferons (IFNs) induced by Listeria monocytogenes in the antilisterial defense mechanism was studied in mice. Cyclosporin A (CsA) had no effect on IFN-alpha production that was induced in the bloodstream after intravenous infection of mice with L. monocytogenes, whereas IFN-gamma that was induced in the bloodstreams of control mice 6 h after stimulation with specific antigen in the late phase of infection was suppressed in CsA-treated mice, depending on the dose of the drug injected. The decrease in IFN-gamma production caused an increase in bacterial growth in the spleens and livers of CsA-treated mice. Furthermore, administration of a daily dose of CsA at 80 or 100 mg/kg of body weight resulted in fatal listeriosis, even though the dose was nonlethal for normal mice. The administration of recombinant murine IFN-gamma on day 0 of L. monocytogenes infection prevented CsA-treated mice from developing fatal listeriosis and restored their ability to produce IFN-gamma in the bloodstream, in response to specific antigen in the late phase of infection.

Animals↗
PubMed1987

Characterization of the bacteriophage T3 DNA packaging reaction in vitro in a defined system.

The bacteriophage T3 DNA packaging system in vitro defined here is composed of purified proheads and two non-capsid proteins, the products of genes 18 and 19 (gp18 and gp19). In this system, a precursor complex (50 S complex) accumulates in the presence of adenosine 5'-O-(3'-thiotriphosphate) (ATP-gamma-S), a non-hydrolyzable analog of ATP. The 50 S complex is converted to a filled head in the presence of ATP. The conversion of the 50 S complex, formed by preincubation with ATP-gamma-S, to the mature head proceeds in a synchronous manner after the addition of ATP. The lag time for formation of mature heads from the 50 S complex is 1.8, 4.5 and 6.8 minutes at 30, 25 and 20 degrees C, respectively. DNA is translocated into the capsid at a constant rate of 5.7 x 10(3) base-pairs per minute at 20 degrees C. The conversion of the 50 S complex to the mature head exhibits a sigmoidal relationship with respect to the concentration of ATP, the concentration for half-maximal activity being about 20 microM. The transition of the prohead to the expanded capsid occurs at 20 degrees C at one minute 40 seconds after the initiation of DNA translocation, when one-fourth of the genome has been packaged into a prohead. At the same time, the capsid-DNA complex becomes stable to high concentrations of salt. When DNA translocation is interrupted by the addition of ATP-gamma-S, packaged DNA exists at 0 degrees C as well as at 20 degrees C but the exit of DNA stops after one-third of the genome is inside the capsid. After exit, DNA is retranslocated into the expanded capsid by the addition of ATP at a rate of about 5.7 x 10(3) base-pairs per minute at 20 degrees C. The decrease in concentration of ATP interrupts DNA translocation into the capsid but does not induce DNA exit. Interrupted DNA translocation may be reinitiated by the addition of ATP. DNA exit is not induced by the addition of ATP-gamma-S to mature heads or partially filled heads pretreated with DNase.

Adenosine Triphosphate↗
PubMed1987

Effect of breast feeding on responses of systemic interferon and virus-specific lymphocyte transformation in infants with respiratory syncytial virus infection.

In order to elucidate the mechanisms of breast-feeding-induced resistance to respiratory syncytial virus (RSV) infection, groups of breast-fed and bottle-fed infants with this infection were tested at the onset of illness and then again 1 and 2 weeks later for the presence of interferon (IFN) as well as of virus-specific lymphocyte transformation (LTF) activity. Alpha-IFN was detected in nine out of ten breast-fed infants, while it was found in only 11 out of 21 bottle-fed subjects. The rate of the detection of IFN was significantly higher in the former group (P less than .05). Mean levels of IFN activity were also higher in breast-fed infants than in bottle-fed subjects during the course of the illness. It was noted, however, that previous breast feeding elicited little enhancing effect on the IFN response of infants with RSV infection. Combining the two feeding groups, suppressed LTF activity to RSV seemed to be related to a positive IFN response, although the association was not statistically significant. These observations suggest that breast feeding has unique mechanisms for modulating the immune response of infants with RSV infection.

Breast Feeding↗
PubMed1987

On the molecular mechanism of DNA translocation during in vitro packaging of bacteriophage T3 DNA.

The process of packaging of bacteriophage T3 DNA in a defined in vitro system can be separated into two stages: formation of a precursor complex (50 S complex) in the presence of adenosine-5'-O-(3'-thiotriphosphate) (ATP-gamma-S) and subsequent translocation of DNA into the head by the addition of ATP. Packaged DNA exits when DNA translocation is interrupted by the addition of ATP-gamma-S (M. Shibata, H. Fujisawa, and T. Minagawa, 1987, Virology, in press; M. Shibata, H. Fujisawa, and T. Minagawa, 1987, J. Mol. Biol., in press). The in vitro system packaged nicked and cross-linked DNAs but did not package single-stranded DNA. DNA packaging was inhibited by intercalating reagents such as ethidium bromide, acridine orange, and 4',6-diamino-2-phenylindole dihydrochloride. The inhibitory effect was proportional to the ability of intercalating agents to unwind DNA. Ethidium bromide did not inhibit the formation of 50 S complex but blocked translocation of DNA into and out of the capsid. DNA packaging was inhibited by actinomycin D and distamycin A which bind to the minor groove of the DNA helix. From these results, we conclude that DNA packaging mechanism utilizes the exterior structure of duplex DNA for translocating the DNA into the capsid.

Capsid↗
PubMed1987

Characterization of ATPase activity of a defined in vitro system for packaging of bacteriophage T3 DNA.

We have developed a defined in vitro system for packaging phage T3 DNA which is composed of purified proheads and the noncapsid proteins gp18 and gp19, products of genes 18 and 19 (K. Hamada, H. Fujisawa, and T. Minagawa, 1986, Virology 151, 119-123). The in vitro system displayed an ATPase activity. The requirements for ATPase activity were the same as those for DNA packaging. ATPase was inhibited by a nonhydrolyzable ATP analog, adenosine-5'-O-(3'-thiotriphosphate) (ATP-gamma-S). ATPase activity did not display specificity for T3 DNA. A reaction mixture containing 8- proheads, proheads deficient in gp8, a portal protein for DNA entrance, or mature heads had no gp18- gp19-dependent ATPase activity. gp8 itself had no ATPase activity and did not complement 8- proheads for ATPase activity. Photoaffinity labeling of proheads, gp18 and gp19 with 8-azidoadenosine-5'-[alpha-32P]triphosphate([32P]8-N3ATP) resulted in preferential labeling of gp19. Protection from incorporation of [32P]8-N3ATP was afforded by ATP but not by AMP and ADP. From these results, it is concluded that gp19 has an ATP binding site(s). A conserved sequence of ATP-binding site containing Gly-X-Gly-X-X-Gly-X-Val is found in gp19.

Adenosine Triphosphatases↗