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Biomedical subjects

H Kamiya

Publications and source records attributed to H Kamiya.

At least 163 records · Page 9Linked to original sources
PubMed1997

Modulation of the arterial baroreceptor reflex by the vasopressin receptor in the area postrema of the hypertensive rats.

The role of arginine8-vasopressin (AVP) in regulation of the baroreceptor reflex in the area postrema was examined in anesthetized hypertensive rats. The sensitivity of the baroreceptor reflex in a one-kidney one clip (1K1C) hypertensive rats was increased in only the initial stage (2 weeks), in association with increase in blood pressure, and then returned to the normal level. This increase in the sensitivity of the baroreceptor reflex in the initial stage was reversed by microinjection of a V1 or V2 antagonist (1 microg) into the area postrema. AVP V2 receptor mRNA was expressed temporarily in the area postrema in this period. These results suggest that vasopressin receptors in the area postrema is important in regulating the sensitivity of the baroreceptor reflex.

Animals↗
PubMed1997

Leading versus lagging strand mutagenesis induced by 7,8-dihydro-8-oxo-2'-deoxyguanosine in Escherichia coli.

We have previously shown that a single N-2-acetylaminofluorene (AAF) adduct bound to the C-8 position of a guanine residue located within plasmids containing the unidirectional ColE1 origin of replication induces a 20-fold higher mutation frequency when the adduct is located in the lagging strand as compared to the leading strand. In this study, single 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxodG) lesions have been introduced in the leading and lagging strand orientation within the same sequence context as for the AAF adducts. The induced frequency of guanine to thymine transversions has been measured, using a specific PCR-based quantitative assay, in strains deficient in the repair of the oxidative lesion. The potential involvement of the UvrABC excision repair system in the removal of 8-oxodG has also been investigated and ruled out. Concerning the mutation frequency asymmetry, in contrast to AAF adducts, 8-oxodG adducts induce the same mutation frequency, irrespective of their location in the leading or lagging strands. This striking difference between 8-oxodG and dGuo-C8-AAF adducts is discussed in terms of their differential capacity to block DNA replication.

2-Acetylaminofluorene↗
PubMed1997

Substitution and deletion mutations induced by 2-hydroxyadenine in Escherichia coli: effects of sequence contexts in leading and lagging strands.

To evaluate the mutation frequency and the mutation spectrum of 2-hydroxyadenine (2-OH-Ade), an oxidative DNA lesion, the modified base was site-specifically incorporated into a unique restriction enzyme site (SalI, GTCGA*C or AflII, CTTA*AG where A* represents 2-OH-Ade) in single- and double-stranded vectors. The 2-OH-Ade residues were introduced into (+)- and (-)-strands of the double-stranded vectors and into the (+)-strand of single-stranded vectors. When the vectors were transfected intoEscherichia coli, the modified base showed little to no cytotoxicity. The mutation frequencies of 2-OH-Ade in the SalI and AflII sites were approximately 0.8 and 0.07%, respectively, with double-stranded (+)-vectors. An increase in the mutation frequencies was not observed with single-stranded vectors. When incorporated into the (-)-strand, the mutation frequencies of 2-OH-Ade in the SalI and AflII sites were approximately 0.3 and 0.1%, respectively. The mutations observed most frequently were -1 deletions at both positions, in the case of the (+)-strand. On the other hand, we observed that 2-OH-Ade in the (-)-strand induced A-->G and A-->T substitutions. These results indicate that 2-OH-Ade residues in DNA induce substitution and deletion mutations without blocking replication inE.coli.

DNA↗
PubMed1997

Changes in intracellular cytokine levels in lymphocytes induced by measles virus.

We investigated the changes in intracellular cytokine levels in different lymphocyte populations induced by measles virus (MV). MV-infected and uninfected peripheral blood mononuclear cells were cultured with phorbol 2-myristate 13-acetate plus ionomycin in the presence of monensin for 10 hr. Surface antigen and intracellular cytokines, interleukin (IL)-2, interferon (IFN)-gamma, and IL-4, were stained simultaneously and analyzed by flow cytometry. The percentage of cells that expressed IL-2 and IFN-gamma was significantly increased in MV-infected CD3+, CD4+, and CD8+ lymphocytes and alphabeta T lymphocytes compared with that in uninfected lymphocytes. In gammadelta T lymphocytes, expression of IFN-gamma, not IL-2, was increased in MV-infected cells compared with that in uninfected cells. IL-2 was increased mainly in MV-infected CD4+ lymphocytes and alphabeta T lymphocytes, whereas IFN-gamma was increased mainly in MV-infected CD8+ lymphocytes and gammadelta T lymphocytes. Expression of IL-4 was unaffected by MV infection. These results demonstrate that MV enhances intracellular levels of type 1 cytokines during the acute phase of measles.

Animals↗
PubMed1997

Schistosoma mansoni oviposition in vitro reflects worm fecundity in vivo: individual-, parasite age- and host-dependent variations.

In an attempt to determine whether in vitro oviposition of adult S. mansoni reflects the fecundity status of worms in vivo, Mongolian gerbils and ICR, BALB/c and SCID mice were infected with about 100 cercariae and examined on an individual basis, 5-12 weeks later, for worm burden, counts of eggs in liver and small intestine, and for the rate of egg deposition of ex-vivo female worms cultured in vitro, singly or in pairs, over a 3-5 day incubation period. The percentage of egg-laying female worms and the number of eggs laid/female after 3 days in culture showed, like worm fecundity in vivo, wide inter-worm variability, especially in 5-, 6- and 12-week-old worms; varied significantly with the age of the parasite with a maximum level attained by worms of approximately 8 weeks of age; and differed in worms recovered from different host species and strains. The data taken together indicate that measuring the egg-producing ability of S. mansoni in vitro reflects the fecundity status of worms in vivo and additionally provides likely explanations for hitherto poorly understood findings on schistosome fecundity.

Animals↗
PubMed1997

Immunization of mice with ultraviolet-attenuated cercariae of Schistosoma mansoni transiently reduces the fecundity of challenge worms.

In the present study cohorts of ICR and BALB/c mice were immunized with u.v.-irradiated cercariae of S. mansoni and challenged 5 weeks later, in parallel with unimmunized control mice, with approximately 100 cercariae. Total worm burdens at 5, 6, 7 and 8 weeks after challenge were significantly reduced by 27-65% in immunized mice. The total number of eggs and the number of eggs/female worm trapped in liver and small intestine were reduced significantly at 6 and 7 weeks post challenge in immunized, as compared to unimmunized mice. Decrease in tissue egg load could be achieved in BALB/c mice passively transferred with spleen cells from u.v.-attenuated cercaria-immunized mice. The proportion of female worms laying eggs in vitro was diminished only in worms recovered from highly resistant mice. The reduction in worm oviposition in immunized mice was no longer apparent at 8 weeks. The data taken together indicate that highly effective immunization of outbred and inbred mice with attenuated cercariae leads to significant, but transient, impairment in challenge worm egg production.

Adoptive Transfer↗
PubMed1997

Differential effects of phorbol ester on AMPA and NMDA components of excitatory postsynaptic currents in dentate neurons of rat hippocampal slices.

Protein kinase C (PKC) is present abundantly in the mammalian central nervous system, and is involved in a variety of neuronal functions. Phorbol esters mimic the role of diacylglycerol, the physiological activator of PKC. We examined effects of phorbol 12,13-diacetate (PDAc) on excitatory synaptic transmission in neurons in the dentate granule cell layer of rat hippocampal slices using the whole-cell patch clamp technique. Excitatory postsynaptic currents (EPSCs) evoked by stimulation of the perforant path (pp) consisted of AMPA and NMDA receptor-mediated components. The application of PDAc potentiated both components of the EPSC, but the effect was more pronounced on the NMDA component. The potentiating effect of PDAc on the NMDA component was dependent on the membrane potential, being most prominent at - 31 and -51 mV. Omega-agatoxin-IVA, a P-type Ca2+ channel blocker, suppressed both AMPA and NMDA components to a similar extent by reducing transmitter release. However, when the PDAc-potentiated AMPA component was reduced to the control level by applying omega-agatoxin-IVA, a substantial potentiation on the NMDA component remained. These results suggest that the potentiation of the NMDA component of the EPSC by PDAc is caused partly by a postsynaptic mechanism in the dentate neurons.

Animals↗
PubMed1997

Phorbol ester and forskolin suppress the presynaptic inhibitory action of group-II metabotropic glutamate receptor at rat hippocampal mossy fibre synapse.

Selective activation of second messenger pathways were tested on presynaptic metabotropic glutamate receptor action at mossy fibre-CA3 synapses, using a rat hippocampal slice preparation. Application of the protein kinase C activator, phorbol 12,13-diacetate, or the adenylate cyclase activator, forskolin, markedly enhanced the mossy fibre field excitatory postsynaptic potentials, and suppressed the relative magnitude of the synaptic depression induced by (2S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine, an agonist at group-II metabotropic glutamate receptors. These effects were also observed in a low Ca2+ solution, suggesting that they were not due to saturation of transmitter release process. Inactive analogues of the respective activators (4alpha-phorbol 12,13-didecanoate and 1,9-dideoxyforskolin) neither enhanced the mossy fibre responses nor suppressed (2S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine-induced synaptic depression. These results suggest that the presynaptic inhibitory action of group-II metabotropic glutamate receptors at mossy fibre-CA3 synapses could be negatively regulated by protein kinase C- and cyclic AMP-dependent mechanisms.

Animals↗
PubMed1997

Measles virus induces apoptotic cell death in lymphocytes activated with phorbol 12-myristate 13-acetate (PMA) plus calcium ionophore.

Peripheral blood mononuclear cells (PBMC) and T lymphocytes were infected with measles virus (MV) and cultured with a protein kinase C (PKC) activator, PMA and a calcium ionophore, ionomycin. After stimulation, cell viability and incorporation of 5-bromo-2'- deoxyuridine (BrdU) were decreased in MV-infected cells compared with mock-infected cells. DNA content analysis and terminal deoxytransferase (TdT)-mediated dUTP nick end labelling demonstrated that the hypodiploid fraction and DNA fragmentation were increased in MV-infected, T lymphocytes activated with PMA plus ionomycin. These data suggest that MV induces apoptotic cell death in cells activated by PMA plus ionomycin. In contrast to stimulation with PMA plus ionomycin, mitogenic stimulation with phytohaemagglutinin (PHA) did not induce apoptotic cell death in MV-infected cells, although cell proliferation was suppressed. Apoptosis induced in stimulated, MV-infected cells may be one mechanism of immunosuppression.

Adult↗
PubMed1997

Relationship between a low toxicity of the mutant A subunit of enterotoxigenic Escherichia coli enterotoxin and its strong adjuvant action.

In the work described here it was determined if and how unnicking in the A subunit of Escherichia coli enterotoxin at Arg192 or nearby residues affected biological activities of the toxin. The mutant toxin was constructed to lack the nick site in the A subunit by deleting the tripeptide Arg192-Thr193-Ile194, which is essential for toxicity. The mutant toxin did not exhibit agmatine ADP-ribosyltransferase activity in the presence or absence of the ADP-ribosylation factor and had less diarrhoeal activity and lower induction of cyclic AMP than did LT. The mutant toxin exhibited a much stronger adjuvant action on antibody responses to measles virus, keyhole limpt haemocyanin, bovine immunoglobulin and ovalbumin compared with LT. The altered toxicity of the mutant toxin might be closely related to the potent adjuvant action on antibody responses to antigens. The relationship between two activities is discussed.

ADP Ribose Transferases↗
PubMed1997

Herpes simplex virus type 1 induces apoptosis in peripheral blood T lymphocytes.

Apoptosis in peripheral blood T lymphocytes induced by herpes simplex virus type 1 (HSV-1) was investigated by use of DNA content analysis and the terminal deoxytransferase-mediated dUTP nick end-labeling method. The hypodiploid fraction in the cell cycle and DNA fragmentation were both increased in HSV-1-infected T lymphocytes compared with that in mock-infected T lymphocytes on stimulation with phytohemagglutinin (PHA). There was no difference in the hypodiploid fraction and DNA fragmentation between HSV-1-infected T lymphocytes and mock-infected cells cultured without PHA. HSV-1 enhanced apoptosis in CD4 and HLA-DR-positive T lymphocytes, but not in CD8 lymphocytes, when stimulated with PHA. These results demonstrate that HSV-1 infection enhances apoptosis in activated T lymphocytes, particularly CD4 and HLA-DR-positive T lymphocytes. bcl-2 expression was unchanged in mock- and HSV-1-infected CD4 and CD8 lymphocytes cultured with or without PHA, indicating that bcl-2 does not contribute to HSV-1-induced apoptotic cell death. Apoptosis in CD4 helper T lymphocytes may account for immunosuppression and lymphocytopenia following HSV-1 infection.

Apoptosis↗
PubMed1997

Production of murine monoclonal antibodies to guinea pig leukocytes and immunohistochemistry of guinea pig skin exposed to Schistosoma mansoni.

Using histochemical ATPase-staining of the guinea pig epidermal sheet, we have demonstrated remarkable accumulations of ATPase-positive cells after exposure to attenuated Schistosoma mansoni cercariae. To characterize further the cells accumulating in the skin after exposure to S. mansoni, we produced a panel of monoclonal antibodies (MAb) to guinea pig leukocytes. These were immunohistochemically classified into 15 types and included MAb to the major histocompatibility complex (MHC) Class I and Class II molecules, shared antigens of all lymph node cells or between lymph node cells and Langerhans' cells (LC), T cells and macrophages (M phi), and M phi including the large Tingible body M phi in the secondary follicle. Varied MAb to M phi, including commercially available MAb (MR-1), were negative with ATPase- and MHC Class II-positive cells accumulated in the skin exposed to S. mansoni. Three MAb (HUSM-30 and 46, and commercially available MSgp2) detected an identical staining profile of accumulated cells with epidermal LC, but two MAb (HUSM-12 and 42) positively stained accumulated cells but not resident LC. These results indicate that the cells accumulated in the guinea pig skin within a few days after exposure to attenuated cercariae of S. mansoni are closest to LC, not to Mø, and may be blood-borne LC/dendritic cells.

Animals↗
PubMed1997

Apoptosis of cord blood T lymphocytes by herpes simplex virus type 1.

We investigated apoptosis induced by herpes simplex virus type 1 (HSV-1) in cord blood T lymphocytes by using agarose gel electrophoresis, DNA content analysis and the terminal deoxytransferase (TdT)-mediated dUTP nick end-labelling (TUNEL) method. DNA fragmentation and the hypodiploid fraction in the cell cycle were both increased in HSV-1-infected CD4 and CD8 lymphocytes stimulated with phytohaemagglutinin (PHA) compared to mock-infected lymphocytes. The percentage of cells in the S phase was decreased in HSV-1-infected CD4 and CD8 lymphocytes. HSV-1 antigen, glycoprotein D (gD) and regulatory protein ICP27 were detected in 8-18% of the hypodiploid fraction of PHA-stimulated, HSV-1-infected lymphocytes. Apoptosis was induced not only in HSV-1 antigen-expressing cells but also in cells not expressing detectable viral proteins. Addition of anti-Fas antibody, anti-Fas-ligand antibody or a mixture of both had no effect on HSV-1-induced apoptosis, indicating that the Fas-Fas-ligand pathway did not contribute to HSV-1-induced apoptosis.

Antigens, Viral↗
PubMed1997

[Efficacy of nasal influenza vaccine combined with Escherichia coli heat-labile enterotoxin B subunit containing a trace amount of the holotoxin in healthy volunteers].

We conducted a field trial to evaluate the efficacy of nasal influenza vaccine combined with Escherichia coli heat-labile enterotoxin B subunit (LTB) containing a trace amount of the holotoxin (LT) in preventing or attenuating influenza among volunteers during the winter season of 1994-1995. A trivalent inactivated influenza vaccine, composed of A/Yamagata/32/89 (H1N1), A/Kitakyusyu/159/93 (H2N2) and B/Mie/1/93 influenza virus strains, was administered intranasally together with recombinant LTB containing 1% recombinant LT (LTB*). Vaccination was done twice 4 weeks apart. Salivary secretory IgA and serum HI antibodies were measured before and 8 weeks after the primary vaccination. Thirty-two volunteers were enrolled in this study; 18 volunteers (mean age 37.7 +/- 11.3) were given LTB*-combined vaccine and 14 volunteers (mean age 44.1 +/- 11.3) given placebo. Outbreaks of H3N2 subtype and B type virus were observed during this study period. Six (42.9%) of the 14 volunteers in the placebo group and 3 (16.7%) of the 18 receiving the LTB*-combined vaccine contracted influenza. There was no statistically significant difference between the two groups, because the number of subjects was small. Higher percentage of positive IgA and HI antibody responses among vaccines given vaccine with LTB* were observed as compared with those in the placebo group. Positive IgA antibody response to all vaccine strains were observed in 46.7% (7/15) of the vaccine group. On the other hand, none of the placebo group showed positive IgA antibody response to all vaccine strains. These results suggest that nasal influenza vaccine with LTB* appears to be effective in preventing influenza.

Administration, Intranasal↗
PubMed1997

IL-5 as a strong secretagogue for human eosinophils.

The ability of IL-5 to induce eosinophil degranulation was investigated. Peripheral blood eosinophils from patients with mildly allergic individuals were isolated with CD16- selection method. Eosinophils were then incubated with interleukin-5 (IL-5) (0.1-100 ng/ml) for 1-48 h and EPX in the supernatants were measured with RIA. We found that IL-5 induced significant amount of eosinophil protein X in a concentration-dependent manner at 24 h. Eosinophil viability was about 90% either in the presence or absence of IL-5 at 24 h. Eosinophils stimulated with IL-5 adhered to the plate. Anti-CD18 mAb blocked adhesion and degranulation induced by IL-5. Dexamethasone and TGFbeta significantly inhibited degranulation in a concentration-dependent manner. These results suggest that IL-5 may be a strong secretagogue for eosinophils, that adhesion via beta2 integrin is a requisite for degranulation, and that the anti-inflammatory effect of corticosteroids and TGFbeta may be exerted at least in part, through the inhibition of eosinophil degranulation.

CD18 Antigens↗
PubMed1997

Comparison of oxidation products from DNA components by gamma-irradiation and Fenton-type reactions.

The four 2'-deoxyribonucleosides were gamma-irradiated or were aerobically treated with Fenton-type-reagents, Fe(II)-EDTA or a renal carcinogen Fe(II)-nitrilotriacetic acid (NTA) under the neutral conditions. The reaction mixtures were immediately analyzed by reverse-phase HPLC. Major products detected were 2-hydroxydeoxyadenosine (2-OH-dA), 8,5'-cyclodeoxyadenosine (cyclo-dA), 8-hydroxydeoxyadenosine (8-OH-dA). 5-formyldeoxyuridine (5-CHO-dU), 5-hydroxydeoxycytidine (5-OH-dC), 8-hydroxydeoxyguanosine (8-OH-dG), 8,5'-cyclodeoxyguanosine (cyclo-dG), and glyoxal and its adduct with dG. Ratio of these oxidized products were dramatically changed depending upon the agents used. For example, 2-OH-dA was a modified nucleoside produced most efficiently by Fe(II)-EDTA, while 5-CHO-dU and 5-OH-dC were the major products by the Fe(II)-NTA treatment and gamma-irradiation, respectively. Glyoxal itself was estimated to be produced most frequently (13 folds of 8-OH-dG) when treated with Fe(II)-EDTA, but its formation was not detected by the treatment with Fe(II)-NTA or by gamma-irradiation. 8-OH-dA was not produced by Fe-EDTA or Fe-NTA but was produced by gamma-irradiation. In contrast, 2-OH-dA was not produced by gamma-irradiation. These results suggest that triphosphates of 2-OH-dA, cyclo-dA, 8-OH-dA, cyclo-dG, 5-CHO-dU, 5-OH-dC, and glyoxal-dG as well as 8-OH-dG may be produced in cells with different ratio by various types of oxidative stress and involved in mutagenesis and carcinogenesis.

Chromatography, High Pressure Liquid↗
PubMed1997

[Pharmacokinetic and clinical evaluation of azithromycin in the pediatric field].

35 children between 9 months and 12 years of ages were given 9.1 to 12.2 mg/kg of azithromycin (AZM) once a day for 3 days. In the treatment of pediatric infectious diseases, we studied pharmacokinetics, efficacy and safetiness of AZM. After administration of 10 mg/kg/day of AZM for 3 days, the elimination half-life was calculated to be 3.8 +/- 16.3 hours (n = 6, mean +/- S.D.). The excretion rate of AZM in the urine within 120 hours of administration was 9.0 +/- 2.3% (n = 5). For the evaluation of efficacy of AZM, we treated 33 cases of children with pharyngotonsillitis, bronchitis, mycoplasma bronchitis, pneumonia, mycoplasma pneumonia, atypical pneumonia, and SSTI. The efficacy rate of these cases were 93.9%. 6 strains of bacteria were identified as causative agents. All strains were eradicated upon the treatment. One case of elevated GOT and GPT and two cases of elevated GPT were observed. No clinical adverse reactions were observed. In conclusion, AZM was useful for the treatment of pediatric infectious diseases were examined.

Anti-Bacterial Agents↗