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Biomedical subjects

T Kurata

Publications and source records attributed to T Kurata.

At least 253 records · Page 14Linked to original sources
PubMed1991

Experimental labyrinthitis in guinea pigs caused by a hantavirus.

Hantavirus-induced acute viral infection of the inner ear of guinea pigs is reported. Guinea pigs were inoculated directly into the inner ear through the round window, or intraperitoneally with hantavirus (B-1 strain), and the cochlea was examined using an immunohistochemical technique for the localization of viral antigens. Virus-specific antigens were detected prominently in the stria vascularis and to a lesser degree in other inner ear structures of the infected guinea pigs. The morphological changes in the inner ear structures of these guinea pigs were observed. Virus was isolated from the blood of some infected guinea pigs. These data suggest that hantavirus can infect the inner ear of the guinea pig via viremia. The effect of immunosuppression by ciclosporin A or cyclophosphamide is discussed.

Acute Disease↗
PubMed1991

Estimating tissue permeability and other bioelectrical parameters using membrane voltage and short-circuit current.

Evaluating the acute toxic effects of drugs or toxins is based mainly on studies which require the use of light microscopy. Recently, the effects of such substances on biological membranes, such as the nasal membrane, has been studied using the traditional Ussing chambers, which make it possible to study the transepithelial flux of drugs across membranes and to measure some bioelectrical parameters. A model is described, with which the changes in the membrane permeability, for sodium, potassium and chlorine, can be calculated directly, based on values obtained from the Ussing chamber system. Also, an experiment is described for evaluating the toxic effects of the cholera toxin B subunit, by measuring these changes in isolated rabbit nasal mucosa.

Animals↗
PubMed1991

The behavior of L-ascorbic acid in the healing process of dorsal wounds in guinea pigs.

The behavior of L-ascorbic acid (AsA) in the healing process of wounds in guinea pigs was investigated by determining AsA and dehydroascorbic acid (DAsA) levels. Dorsal skin wounds of guinea pigs fed AsA-deficient diets for 10 days were surgically induced, and the animals were intraperitoneally supplemented with 0, 0.5, 5, 50 mg/day of AsA for 4 days, respectively. The animals were sacrificed, and the amounts of AsA and DAsA in healing skin wound and intact skin were determined by high-performance liquid chromatography (HPLC). It was found that total AsA levels in the healing wound of the animals in AsA-supplemented groups were almost similar to those in intact skin, respectively. However, DAsA levels in the healing wounds on day 4 of the healing period are significantly higher than those not only in the intact skin but also in the completely regenerated skin on day 14 of the healing period. From these results, it was suggested that the wound healing process was accompanied by the oxidation of AsA, moreover, the reduction of DAsA to AsA did not sufficiently occur in vivo.

Animals↗
PubMed1991

Comparison of absorption of erythorbic acid and ascorbic acid in guinea pig small intestine.

Both the ascorbic acid (AsA) and erythorbic acid (ErA) absorption in the small intestine of guinea pigs were determined by the perfusion of the small intestine using isotonic phosphate buffer recycled in situ. The absorption rate of AsA in the small intestine of guinea pigs was higher than that of ErA; however, Km of AsA absorption was lower than that of ErA in normal guinea pigs. In AsA-deficient guinea pigs, the absorption rates of both AsA and ErA were higher than those in normal ones. The absorption of AsA and ErA in the small intestine of guinea pigs was inhibited by ouabain. Furthermore, AsA and ErA inhibited each other's absorption. Based on the results, the net amount of the absorbed ErA in the small intestine may be lower than that of AsA, and ErA absorption mechanism seemed to be similar to that of AsA. The absorption rate of both AsA and ErA in the small intestine of guinea pig might be dependent on the AsA level in the tissues.

Animals↗
PubMed1991

Vesicular stomatitis virus-mediated cell fusion subsequent to virus adsorption at different pH values.

Vesicular stomatitis virus (VSV)-mediated cell fusion from without can be induced by transient exposure to low pH, subsequent to adsorption of VSV at neutral pH. To study the mechanism of VSV-induced cell fusion, we examined the effect of pH condition at virus adsorption on acid-inducible VSV-mediated cell fusion. Although the binding of VSV to BHK-21 cells was most efficient under acidic condition (pH 5.7-6.3), extensive cell fusion was not observed under this condition. A temporary exposure to low pH after binding at neutral pH also decreased fusion activity. However, return to neutral pH for 2 min just after the acid binding restored the fusion activity. These results indicate the requirement of neutral pH condition for VSV-mediated cell fusion prior to the acid stimulation which induces conformational change of the virus glycoprotein into a fusogenic form.

Adsorption↗
PubMed1991

O2 uptake and CO2 elimination during mechanical ventilation with high frequency oscillation.

This study was intended to elucidate gas exchange in a quasi-steady state during high frequency oscillatory ventilation (HFO) in terms of arterial blood gases, tidal volume(VT) and frequency of oscillation (f). Firstly, experiments were performed on anesthetized, paralyzed and tracheostomized dogs using a piston-type oscillator with a fresh air bias flow. The f values employed in the animal experiments were 10 to 30 Hz, and VT values were 1 to 3 ml/kg of body weight. Changes in PaO2 observed during HFO could be expressed by the equation PaO2 = 125.2-60.3/(VT X f), which closely coincided with the alveolar ventilation equation for O2, i.e., PaO2 = 125-78/, VA, Where P(A-a) O2 and O2 consumption were assumed to be 25 Torr and 90 ml/min, respectively. PaCO2 during HFO deviated from the curve of the alveolar ventilation equation, PaCO2 = constant/, VA at a higher VT x f, and was distributed along the hyperbolic curve of PaCO2 = 1/, VA + 14.7. This suggested that HFO shows a certain limitation in CO2 elimination. Secondly, indicator gas transport through straight tube models for two directions, i.e., wash-in and wash-out, were observed. Wash-in of indicator gases (He, N2 and SF6) in terms of indicator appearance time at the other end of the tube changed as a function of VT x f. The effect of increasing f at a fixed VT on the wash-in was much less than that of increasing VT at a fixed f. The heavier gas (SF6) was washed in faster than the lighter gas (He) although wash-in of each indicator gas was closely related to the function VT x f. Washout in terms of the appearance time of indicators in the opposite direction was, however, strongly dependent on VT, and the effect of increasing f at a fixed VT on wash-out reached a limit beyond a certain f. It was concluded from the present study, that both convective dispersion and augmented diffusion play important roles, although they are not clearly distinguished, as gas transport mechanisms during HFO. The difference between inspiratory and expiratory gas transport modes could be explained by differences in flow profiles, relative important of convective dispersion, and/or time required for gas mixing in the airways.

Animals↗
PubMed1991

H-2-unrestricted adjuvant effect of cholera toxin B subunit on murine antibody responses to influenza virus haemagglutinin.

Cholera toxin B subunit (CTB) has been shown to augment the antibody responses to influenza virus haemagglutinin (HA) in BALB/c mice immunized with HA vaccine together with CTB. In this study, mouse strain differences in the adjuvant effect of CTB on anti-HA antibody responses were investigated along with those in the antibody responses to CTB or HA, using various inbred and H-2 congenic strains. The antibody responsiveness to CTB depended on the H-2 haplotype of the strain: strains with the H-2b haplotype were high responders, those with H-2a, H-2k and H-2s were low responders, and those with H-2d were intermediate. The responsiveness to HA was also related to the H-2 haplotype: H-2a and H-2k strains were high responders, H-2b and H-2s strains were low responders, and H-2d strains were intermediate. However, the degree of the adjuvant effect of CTB on anti-HA antibody responses was almost constant, regardless of the H-2 haplotype or other genetic backgrounds of the strain. The lack of genetic restriction of the adjuvant effect would be favourable for application of CTB-combined HA vaccine to humans, who are genetically diverse. Moreover, these results suggest that the immunogenicity and adjuvanticity of CTB differ essentially in their mechanisms.

Adjuvants, Immunologic↗
PubMed1990

Experiments on herpes simplex viral infections of the facial nerve in the tympanic cavity.

An experimental protocol was developed to study viral infection of the facial nerve. Facial palsy was induced in a guinea pig model by inoculating type 1 herpes simplex virus (HSV-1) directly onto the facial nerve in the temporal bone. Partial removal of the bony wall of the fallopian canal was effected, and virus was placed on the nerve after incising its sheath on the right side and without incision of the sheath on the left side. All animals exhibited subsequent bilateral facial palsies, but with severe changes occurring on the right side. The animals were then sacrificed sequentially following infection. Immunofluorescence and histopathological studies revealed the presence of HSV antigen, infiltration of inflammatory cells, hemorrhage, and degeneration of the right facial nerve. In the left nerves, a slight hemorrhage was recognized without cellular infiltration or HSV antigens. These results suggest that the intact facial nerve is rather resistant to HSV infection, but this defense mechanism is easily destroyed by damage to the facial nerve sheath.

Animals↗
PubMed1990

Coxsackie B antigen in the central nervous system of a patient with fatal acute encephalitis: immunohistochemical studies of formalin-fixed paraffin-embedded tissue.

A case of fatal acute encephalitis due to Coxsackie B1 virus is described. Confirmation of Coxsackie B virus as the etiological agent of encephalitis was based on identification of the virus antigen in formalin-fixed paraffin-embedded tissue sections. In the past, the diagnosis was obtained by serological studies of peripheral blood and viral isolation. This is the first report in which indirect immunofluorescent and immunoperoxidase methods using rabbit antiserum raised against Coxsackie B types 1-6 was utilized in determining the etiology of encephalitis. It must be emphasized that these methods can be used both on biopsy or autopsy specimens, even retrospectively.

Antigens, Viral↗
PubMed1990

Measles associated with coronary arteritis.

A two-year-old girl with measles virus (MV) and chronic Epstein-Barr virus (EBV) infection developed lethal coronary aneurysmal arteritis accompanied by giant cell pneumonia, systemic lymphadenitis and hepatosplenomegaly. In her coronary arteries, lungs and aorta, cells containing intranuclear and intracytoplasmic inclusions, including syncytial giant cells, were detected, the presence of MV in the organs being proved by electron microscopic and immunofluorescent studies. Immunopathology further demonstrated MV to be disseminated in almost all organs other than lymph nodes. Clinical diagnosis of chronic EBV infection was established on the basis of persistent high titers of antibodies against capsid and early antigens of EBV and viral presence was confirmed by Southern blot hybridization in a mesenterial lymph node obtained at autopsy. To the best of our knowledge, this is the first description of MV association with coronary aneurysmal arteritis, raising the possibility that measles infection can cause severe vasculitis under immuno-suppressive states, such as that caused by chronic EBV infection.

Adult↗
PubMed1990

Cross-protection against influenza B type virus infection by intranasal inoculation of the HA vaccines combined with cholera toxin B subunit.

The relationship between the antibody responses to various influenza B type virus HA vaccines and protection against live B virus infection was investigated in Balb/c mice which had been inoculated intranasally with a combination of the HA vaccines and B subunit of cholera toxin (CTB) 4 weeks previously. The inoculation of HA vaccine, prepared from B/Ibaraki/2/85 (B/Ibaraki), B/Nagasaki/1/87 (B/Nagasaki) or B/Aichi/5/88 (B/Aichi) viruses, combined with CTB induced high levels of both nasal IgA and serum HI antibodies to any of B/Ibaraki, B/Nagasaki and B/Aichi viral antigens. Simultaneous inoculation of each CTB-combined HA vaccine provided complete protection against B/Ibaraki virus infection which is demonstrated by both rapid clearance of pulmonary virus and complete survival. On the other hand, the inoculation of HA vaccine prepared from B/Yamagata/16/88 (B/Yamagata) virus together with CTB induced only a low level of nasal IgA antibodies, cross-reactive to B/Ibaraki, B/Nagasaki and B/Aichi viral antigens and protected only partially against B/Ibaraki virus challenge. The involvement of the B type virus-specific immunity in this protection was suggested by the absence of protection against B/Ibaraki virus infection in mice previously inoculated with both A/PR/8/34 (H1N1) virus HA vaccine and CTB. These results suggest that antibodies to various influenza B viruses are cross-reactive to each B type virus antigens and that cross-protection against B virus infection could be conferred depending on the degree of B type virus cross-reactive immunity including secretory IgA antibodies.

Animals↗
PubMed1990

Comparison of intranasal inoculation of influenza HA vaccine combined with cholera toxin B subunit with oral or parenteral vaccination.

The antibody responses to influenza virus A/PR/8/34 HA vaccine and protection against virus challenge in mice given the vaccine together with the B subunit of cholera toxin (CTB) intranasally were compared with those in mice given the vaccine with CTB perorally, intraperitoneally or subcutaneously. Intranasal vaccination induced remarkably higher levels of antiviral IgA antibodies in both respiratory washings and serum than did other routes of vaccination. The titres of antiviral IgG antibodies in respiratory washings and serum, and haemagglutination-inhibiting (HI) antibodies in serum, were similar after intranasal and parenteral vaccination. Oral vaccination, however, induced low levels of antiviral IgG antibodies but no detectable HI antibodies. Moreover, intranasal immunization elicited significantly higher titres of antiviral IgA antibodies in intestinal secretions in comparison with oral immunization. In contrast, parenteral immunization failed to induce these IgA antibodies. In virus challenge studies, a greater protective effect was seen after intranasal and intraperitoneal vaccination than after other routes of vaccination. These results suggest that intranasal inoculation of combined HA vaccine and CTB is superior to oral or parenteral inoculation in protecting mice. Furthermore, the intestinal antiviral IgA responses suggest that intranasal administration of CTB-combined vaccines could be effective not only against respiratory pathogens but also against enteropathogens.

Administration, Intranasal↗
PubMed1990

Functional role of respiratory tract haemagglutinin-specific IgA antibodies in protection against influenza.

Intranasal inoculation of haemagglutinin (HA) purified from influenza virus A/PR/8/34 (PR8, H1N1) together with cholera toxin B subunit, into Balb/c mice resulted in complete protection against PR8 infection in parallel with the induction of high levels of HA-specific IgA and IgG antibodies on the respiratory tract. The respiratory tract IgA and IgG were purified from nasal and lung washings of the immunized mice using affinity columns, and their HA-specific activities were measured by enzyme-linked immunosolvent, plaque neutralization and haemagglutination inhibition assays. The purified IgA and IgG had the following properties: (1) They were able to neutralize virus in vitro. (2) The purified IgA included major antibodies directed against PR8 virus and minor antibodies cross-reactive with A/Yamagata/120/86 (H1N1) or A/Fukuoka/C29/85 (H3N2) virus, while the purified IgG included major antibodies to the homotypic virus, minor antibodies to the H1N1 virus and only a trace amount of antibodies to the H3N2 virus. (3) When separated on a Sephacryl column, most of the IgA anti-HA activities occurred in the polymeric fractions of purified IgA, whereas the IgG anti-HA activities occurred in the monomeric fractions. (4) When passively administered to normal mouse respiratory tract before infection, the purified IgA protected against PR8 infection. These results suggest that HA-specific, polymeric IgA antibodies on the respiratory tract by themselves provide not only protection against the homotypic virus but also higher levels of heterotypic immunity than IgG.

Animals↗
PubMed1990

Enhancement of DTH response by cholera toxin B subunit inoculated intranasally together with influenza HA vaccine.

The effects of B subunit of cholera toxin (CTB) on delayed-type hypersensitivity (DTH) response to influenza vaccine derived from influenza virus A/PR/8/34 (PR-8, HlNl) virus were investigated in B10 mice that were immunized intranasally with both influenza vaccine and CTB. The result showed that intranasal inoculation of this combination augmented DTH response to influenza vaccine, which reached its peak 6 days after inoculation, and also induced accelerated DTH response upon a second inoculation of influenza vaccine alone 4 weeks later, that the cross-reactive DTH response to PR-8 vaccine was elicited by the injection of the different influenza A-type virus vaccine into the footpad of the vaccinated mice, but was not by influenza B-type virus vaccine, that the DTH-mediating T cells were detected selectively in the lungs of mice that received the nasal inoculation of the vaccine and CTB together, but that subcutaneous inoculation of this combination failed to induce DTH-mediating T cells in the lungs. These results, together with the previous papers (Tamura et al, Vaccine 7: 257-262; 314-320, 1989), suggest that CTB could augment both humoral and DTH responses against influenza vaccine in the respiratory mucosal tract.

Adjuvants, Immunologic↗
PubMed1990

Disseminated adenovirus (type 19) infection in a neonate. Rapid detection of the infection by immunofluorescence.

A case of fatal disseminated adenovirus infection in a neonate who suffered from severe keratoconjunctivitis and pneumonitis is reported. The diagnosis was made seven days after the onset of illness based on the detection of adenovirus antigen in the smears of the tracheal suction and conjunctival swab by immunofluorescence. Viral antigen was detected in the frozen or formalin-fixed autopsy specimens of the lungs, kidneys, spleen, liver and lymph nodes. Typical crystal arrangement of adenovirus virions was observed in the alveolar epithelial cells by electron microscopy. The isolated virus was identified to be of type 19 by a neutralization test. The IF examination using adenovirus group specific immune reagents on the smears of clinical specimens appears to be useful for rapid diagnosis of viral infections.

Adenoviridae Infections↗
PubMed1990

[Diagnosis of varicella-zoster virus (VZV) infection by using FITC-labeled monoclonal antibodies].

Anti-varicella zoster virus (VZV) mouse monoclonal antibodies conjugated with fluorescein isothiocyanate were evaluated for their usefulness as a practical diagnostic tool in the clinical field by examining cells infected with isolated herpes viruses and 431 clinical samples. The kit stained clearly the cells infected with 14 isolated VZV strains without cross reaction to 15 isolated herpes simplex virus type-1 strains (HSV-1) and 14 type-2 (HSV-2) strains. In clinical specimens, viral antigens of VZV were detected in 92/105 (87.6%) cases of varicella and in 176/190 (92.6%) cases of herpes zoster. Specific fluorescence of VZV was also observed in 5 out of 96 cases diagnosed as HSV infections, although these samples had no specific reaction to HSV when tested by the commercially available diagnostic kit. In 24 cases which could not be clinically diagnosed as herpes zoster or herpes simplex, the VZV antigen was demonstrated in 9 cases. All 109 VZV-positive cases in virus isolation by culture were also judged VZV-antigen positive by the kit, while all 69 HSV-positive cases in virus isolation were VZV-antigen negative. Furthermore, the VZV antigen was detected by the kit in 53/60 clinical diagnoses of varicella or herpes zoster without successful virus isolation. These results clearly indicate the usefulness of the kit as a practical VZV diagnostic reagent, especially in terms of specific sensitivity and easy technical manipulation.

Antibodies, Monoclonal↗