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Biomedical subjects

I Takashima

Publications and source records attributed to I Takashima.

At least 73 records · Page 4Linked to original sources
PubMed1995

Characterization of the mode of Hantaan virus infection in adult mice using a nested reverse transcriptase polymerase chain reaction: transient virus replication in adult mice.

A polymerase chain reaction (PCR) for the detection of hantavirus genome was established and applied to analyze the mode of infection of Hantaan virus in adult ICR mice. The cDNA for the S genome segment of Hantaan virus was reverse-transcribed from the total RNA of organs of the infected mice. The sequence in the S genome segment of Hantaan virus was successfully amplified by reverse transcriptase (RT)-PCR followed by nested PCR. In 5-week-old ICR mice inoculated intraperitoneally with Hantaan virus, strain 76-118 (1.3 x 10(5) FFU/mouse), the virus was detected in clots and lungs from 3 to 10 days post-inoculation (p.i.) by nested PCR and virus-isolation techniques. No virus was detected in any specimens collected on 1 day and after 28 days p.i., and in spleens and brains through the observation period by both methods. The antibody which was measured by indirect immunofluorescence antibody assay (IFA) appeared at 7 days p.i. and the geometric mean titer was elevated to its maximum level of 1:203 at 10 days p.i., maintaining the same level until 35 days p.i. These results suggest that adult mice are transiently infected with Hantaan virus.

Animals↗
PubMed1995

Evidence for the existence of Puumula-related virus among Clethrionomys rufocanus in Hokkaido, Japan.

We conducted field surveys of indigenous rodent species in Hokkaido, Japan from 1980 to 1993. Serum samples were collected from 663 rodents, including Clethrionomys rufocanus, Apodemus speciosus, A. argenteus, and C. rutilus. Antibody to hantavirus was determined by the protein G antibody assay. Positive C. rufocanus were detected in seven of eight collection sites, but no antibody was detected in the remaining rodent species. To reveal the serotype of the circulating virus in C. rufocanus, antibody titers to Hantaan, Seoul, Puumala, and Prospect Hill viruses were compared by means of the focus reduction neutralization test. The titers in positive sera were extremely high to the Sotkamo strain of Puumala virus. Results were confirmed by the reverse transcriptase-polymerase chain reaction, and suggested that Puumala-related viruses are in circulation among C. rufocanus populations in Hokkaido.

Animals↗
PubMed1995

[T cell receptor V beta repertoire of locoregional lymphocytes in malignant effusions].

We analyzed the T cell receptor (TCR) V beta repertoire of lymphocytes obtained from patients with malignant effusion treated by locoregional immunotherapy. Polymerase chain reaction using a panel of V beta subfamily specific oligonucleotide primers(V beta 1-20) was employed after reverse transcription of mRNA isolated from the locoregional cells. No major oligoclonality of TCR repertoire was observed in effusion lymphocytes before the treatment. The expression level of V beta 13.1 repertoire was significantly higher in effusion lymphocytes than in peripheral blood lymphocytes before treatment. V beta 20 gene expression increased significantly after locoregional administration of OK-432. It is suggested that TCR V beta 13.1 may be responsible for effusion lymphocytes and TCR V beta 20 for OK-432-related antigenic stimulus.

Adult↗
PubMed1994

Enhancement of infectivity of hantavirus in cell culture by centrifugation.

Centrifugation was introduced during virus adsorption to Vero E6 cells to improve the infectivity of hantavirus. Centrifugal adsorption of a stock solution of Hantaan virus strain 76-118 to a monolayer of Vero E6 cells enhanced virus infectivity depending on the centrifugation time and the centrifugal force. The maximum level of infectivity (3.1 x 10(6) FFU/ml) was enhanced after a 2 h centrifugation at 671 x g, which was almost 9-times higher than that of conventional adsorption of the virus at 37 degrees C for 1 h. Vero E6 cells were inoculated with a new hantavirus strain, KI-91-40, isolated with a low infectious titer (400 FFU/ml) from an urban rat and adsorbed by centrifugation. A higher virus titer was detected sooner compared to when using conventional adsorption. To analyze the mechanism of the enhancement, the centrifugation was carried out before and after virus adsorption. The infectivity was reduced when Vero E6 monolayers were centrifuged before virus inoculation. When the centrifugation proceeded after inoculation, the infectivity was almost equal to that without centrifugation. The infectivity was only enhanced when centrifugation was carried out during inoculation. These results indicate that centrifugation promotes a very early event of infection, probably attachment of the virus to cells.

Animals↗
PubMed1994

Kinetics and cross-reactivity of the virus-specific antibody-forming cells in mice during primary and secondary infection with Japanese encephalitis virus and related flaviviruses.

A modified antibody-forming cell assay was used to enumerate splenocytes secreting antibodies to Japanese encephalitis (JE) virus and four other flaviviruses in infected cells as the target antigens. The optimal viral antigen expression for the assay was standardized in the infected cells for each virus and the incubation time varied depending of the cell line and the virus. The kinetics of response of JE virus-infected mice readily showed IgG isotype switching. Antibody-forming splenocytes of mice primed or boosted with one flavivirus could distinguish, in variable proportions, the homologous virus antigen from heterologous ones depending on the serocomplex of the virus. Antibody-forming cells from flavivirus-infected mice were flavivirus specific as evidenced by the lack of recognition of Getah virus (alphavirus) antigen. After JE virus-infected mice were cross-primed with another flavivirus, the IgG-forming cell response resembled the secondary response to both viruses but had higher affinity to JE virus than to the cross-priming virus.

Animals↗
PubMed1994

Comparison of nucleotide sequences of M genome segments among Seoul virus strains isolated from eastern Asia.

The nucleotide sequences of the M genome segments of three Seoul virus strains (KI strains) which were isolated from urban rats inhabiting the same enzootic focus between 1983 and 1988 were compared. The viral cDNAs were amplified by PCR and were directly sequenced. The nucleotide sequences of KI strains were extremely homologous regardless of isolation year (less than 10 substitutions in 3651 nucleotides, less than 4 substitutions in 1133 amino acids). In addition, the nucleotide sequence of the KI strain isolated in 1983 (KI-83-262) was also quite similar to that of other Seoul viruses, which were isolated from laboratory rats in Japan (strain SR-11, 98.1% and B-1 strain, 96.5%), from an urban rat in Korea (Seoul 80-39, 96.5%) and from an urban rat in China (R22 strain, 93.4%). All possible N-glycosylation sites in the deduced amino acid sequences were conserved among all Seoul viruses examined. The nucleotide and amino acid sequences of Seoul virus strains were highly conserved although they were isolated from various districts of eastern Asia. These results indicate the genetic stability of Seoul virus strains maintained under a natural environment and the homology of Seoul viruses isolated from various districts of eastern Asia. The relationship among Seoul virus strains isolated from eastern Asia was compared by phylogenetic analysis.

Amino Acid Sequence↗
PubMed1994

Epizootiological studies of hantavirus infection among urban rats in Hokkaido, Japan: evidences for the persistent infection from the sero-epizootiological surveys and antigenic characterizations of hantavirus isolates.

Epizootiological studies of hantavirus infection among urban rats were carried out through the surveys repeated 11 times at the same dumping ground area in 1983 to 1988. A total of 279 rats (Rattus norvegicus) were captured during the surveys. Sero-positive animals to hantavirus strain SR-11 were detected in all the surveys. Overall positive rate of rats 6 months old or more (94/128, 73.4%) was significantly higher than that of younger rats (23/151, 15.2%, x2 = 96.4, P < 0.001). Therefore, age dependent acquisition of hantavirus infection among rats was confirmed. Seven hantavirus strains, KI-83-262 (August, in 1983, designated as strain KI-262 in our previous report (2)), KI-85-1 and 85-2 (July in 1985), KI-88-4, 88-11, 88-15 and 88-24 (October, 1988) were isolated from lung tissues of adult rats which have high titers of neutralizing antibody. Although the serum specimens of virus carrier rats neutralized the infectivity of all the KI isolates, no apparent antigenic change in the isolates was detected by indirect immunofluorescent antibody (IFA) assay using polyclonal and monoclonal antibodies (MAbs) regardless of isolation years. However, neutralization test showed slight difference of antigenicity among KI strains. These results epizootiologically confirmed that hantavirus infected persistently among urban rats in a presence of neutralizing antibody.

Animals↗
PubMed1994

[Skin reaction to OK-432 and its dosage for locoregional administration].

Establishment of optimal dosage of OK-432, a streptococcal preparation, was studied based on its skin test was studied. Locoregional immunotherapy using OK-432 was conducted for patients with malignant fluids. More OK-432 was administered to patients having a weaker skin reaction to OK-432 and less to those having a stronger one, corresponding to their redness diameter of skin reaction. There was a marked difference in OK-432-skin test among patients. Some patients with malignant fluids having small redness responded to the treatment after a large amount of OK-432, and others were well controlled by a smaller dosage of OK-432. It is suggested that OK-432-skin test may provide the optimal dosage for local treatment of malignant fluids.

Ascitic Fluid↗
PubMed1993

Improved sensitivity in the antibody-forming cell assay for Japanese encephalitis virus in mice by optimal fixation of cells and avidin-biotin complex (ABC) immunocytochemistry.

A sensitive modified method for the detection in vitro of antibody-forming cells (AFCs) in Japanese encephalitis (JE) virus infected mice is described. The procedure involves the selection of the most appropriate incubation period, after the infection of monolayer cells, for expression of viral antigens to be recognized by AFCs. Adequate preservation of the expressed antigens was achieved after fixation with paraformaldehyde-lysine-periodate buffer (PLP). The development of spots which corresponded to AFCs was successfully obtained with the use of the avidin-biotin complex (ABC) amplification reaction. The number of the spots developing after completion of the assay was greater after PLP fixation compared with other fixation solutions such as methanol, formalin and acetone-water. Optimum antigen expression on the infected cells for recognition by lymphoid cells was reached after 24 h of infection. However, it was possible to detect viral antigens on the infected cells 8 h after infection. The ABC reaction was shown to be the best procedure for developing spots compared with other immunocytochemical methods. A linear increment was observed in the number of spots that developed at different spleen cell densities. This assay is simple to perform and could detect virus-specific Ig producing cells from the spleens of mice infected with JE virus. It also makes it possible to enumerate accurately the kinetics of the AFC response in different lymphoid organs during infection or after vaccination.

Animals↗
PubMed1993

Neutralization of Chlamydia psittaci with monoclonal antibodies.

Neutralization of Chlamydia (C.) psittaci avian strain P-1041 was examined in vitro using monoclonal antibodies (MAbs). Of the 10 MAbs used, 6 were found to exhibit neutralizing capability. These include 3 against major outer membrane protein (MOMP), 1 against lipopolysaccharide (LPS) and 2 against other protein molecules [90 kilodalton (kDa) and 90/50 kDa]. Most neutralizing MAbs were dependent on complement for efficient neutralization, while a strain-specific MAb (2B5) against the 90 kDa protein displayed a different requirement for complement and neutralized the infectivity of the P-1041 at high concentrations without complement. By competitive inhibition enzyme-linked immunosorbent assay (competitive inhibition ELISA), all 3 neutralizing anti-MOMP MAbs were demonstrated to recognize different epitopes found in very close proximity to each other on the outer membrane.

Antibodies, Bacterial↗
PubMed1993

Antimicrobial effects of a new carboxyquinolone drug, Q-35, on five serogroups of Leptospira interrogans.

New carboxyquinolone drugs, including the recently developed Q-35, were evaluated for their in vitro potency against five serogroups of Leptospira interrogans. Q-35, ofloxacin, ciprofloxacin, and tosufloxacin showed MICs (0.05 to 0.20 microgram/ml) comparable to those of tetracycline. However, MBCs of these drugs varied between 10- and 100-fold above the MIC for most strains tested. Q-35 was shown to be active against L. interrogans in vitro as judged by the MICs obtained.

Anti-Infective Agents↗
PubMed1993

Seroepidemiological survey of chlamydial infections in light horses in Japan.

To investigate the overall prevalence of chlamydial infections in light (i.e. non-draught) horses in Japan, 599 sera obtained from 12 localities in 1991 were tested for complement fixation antibodies. The mean antibody positive rates of the all sera were 15.2% (91/599) and the regional positive rates were higher in Honshu (19.1%, 48/251) and Kyushu (20.0%, 20/100) than in Hokkaido (9.3%, 23/248). In Honshu, the highest rate (56.0%, 28/50) was observed in Utsunomiya. Analysis of the positive rate in different age groups showed that the 2-5 years age-group had the highest prevalence of chlamydial infections. This indicates that chlamydial infection is prevalent in light horses in Japan.

Animals↗
PubMed1993

Antibiotic resistance of Escherichia coli and Salmonella from apparently healthy slaughtered cattle and pigs, and diseased animals in Zambia.

Escherichia (E.) coli and Salmonella (S.) choleraesuis (subsp. choleraesuis and subsp. salamae) from apparently healthy slaughtered cattle and pigs in 1989 in Zambia, were examined for antibiotic resistance and the presence of conjugative R plasmid. Salmonella strains from diseased animals (cattle, chickens, leopards, lions and warthogs) were similarly tested. The majority of the cattle had been nomadically kept in so-called "traditional farms" while all the pigs were from commercial farms. More pigs (39%; 41/105) harboured drug-resistant E. coli than cattle (6.7%; 7/105). Moreover, the number of drug-resistant E. coli was higher among strains from pigs (31.2%; 49/157) than cattle (4.2%; 7/167). For both cattle and pigs, drug resistance was more frequently observed against tetracycline, streptomycin, sulfadimethoxine and ampicillin than other antibiotics and the single resistance pattern occurred most frequency, especially among pig E. coli strains. Drug-resistant Salmonella was recorded in 3.6% (1/28) of strains from slaughtered cattle and 31.3% (10/32) of those from diseased animals. Drug-resistant E. coli from pigs and cattle carried R plasmid at high frequency.

Animals↗
PubMed1992

Protective role of antigenic sites on the envelope protein of Hantaan virus defined by monoclonal antibodies.

To investigate the role of Hantaan virus envelope glycoprotein in infection, a panel of monoclonal antibodies (MAbs) was examined in vitro with several serological tests and in vivo by passive transfer experiments in mice. An antigenic site, specific for the inhibition of infected cell focus was detected with the focus inhibition neutralization test (FINT), in addition to the neutralization related antigenic sites, which were revealed by the ordinary focus reduction neutralization test (FRNT). Suckling mice were given the MAbs by passive transfer followed by lethal Hantaan virus challenge. All neutralizing MAbs detected by either FRNT or FINT protected all mice from lethal infection, confirming the importance of the antigenic sites as a protective antigen. Mice given non-neutralizing MAbs by passive transfer, however, began to die earlier than the control group; mean time to death (18.2 +/- 2.1 to 21.5 +/- 2.8 days) being significantly shorter than that of the control group (25.8 +/- 1.8, p less than 0.01, Mann-Whitney, U probability test). Virus titers in brains of mice which died early, were about 10 times higher than those of control mice. These results indicated the early death phenomenon of mice which was mediated by the anti-virus antibody.

Animals↗
PubMed1992

Antibody-dependent enhancement of hantavirus infection in macrophage cell lines.

Antibody-dependent enhancement (ADE) of hantavirus infections (strains Hantaan 76-118 and SR-11) was studied using macrophage-like cell lines (J774.1, P388D1, and U937). Significantly higher virus titers (1,000 to 4,000 FFU/ml) were obtained by pretreatment of the virus with immune serum as compared to normal serum (less than 20 FFU/ml). Monoclonal antibodies (MAbs) to strain Hantaan 76-118 were employed to determine the antigenic determinants responsible for the ADE activity. ADE of the infection occurred with MAbs to both G1 and G2 envelope glycoproteins, but not with MAbs to nucleocapsid protein. Antigenic determinants related to haemagglutination or virus neutralization were found to cause ADE of the infection.

Animals↗
PubMed1992

Development and application of protein G antibody assay for the detection of antibody to hantavirus.

A new serodiagnostic method designated protein-G antibody assay (PGA) was developed for detection of hantavirus infection in various species of animals. The assay procedure includes reacting the sera with hantavirus-infected cells on glass slides, followed by incubation of biotinylated protein G and amplification with the avidin-biotinylated peroxidase complex. Specific antibody in rabbit, rat, mouse and Mongolian gerbil serum was detected by this method. The PGA titres were similar to those of the neutralization titre. In the sera of Mongolian gerbils infected with strain SR-11, antibody was first detected 10 days post infection, and the titre increased to 1:256 at 18 days post-infection. PGA was evaluated using sera of urban rats (Rattus norvegicus) captured in an endemic area of hantavirus infection. The negative (much less than 1:1, 24/62, 38.7%) and positive groups (much greater than 1:16, 38/62, 61.3%) were clearly distinguished. PGA titres were closely related to IFA titres in the sera. Two of 10 sera from Clethrionomys rufocanus and one from Apodemus speciosus captured in the same endemic area were positive to both PGA and IFA. These data indicate that PGA is a simple and useful method for seroepizootiological surveys of hantavirus infection, especially in wild rodent reservoirs.

Animals↗