Biomedical subjects

T Mikami

Publications and source records attributed to T Mikami.

At least 361 records · Page 20Linked to original sources

PubMed1995

Adrenergic receptor-mediated Cl- transport in rabbit corneal endothelial cells.

Adrenoceptor-mediated Cl- transport in cultured rabbit corneal endothelium was examined using a Cl(-)-sensitive fluorescent dye. The intracellular Cl- concentration ([Cl-]i) in the endothelial cells was estimated to be about 30 mM. Noradrenaline (0.001-0.1 mM) transiently decreased the [Cl-]i in a dose-dependent manner. Such a decrease in [Cl-]i was completely antagonized by pretreatment with the alpha-adrenoceptor antagonist phentolamine (0.1 mM). The selective alpha 2-adrenoceptor agonist UK 14304-18 (5-bromo-6-[(4H,5H-imidazol-2-yl)amino]quinoxaline, 0.1 mM) persistently decreased the [Cl-]i, but neither the alpha 1-adrenoceptor agonist phenylephrine (0.1 mM) nor the beta-adrenoceptor agonist isoproterenol (0.1 mM) had any effect. The alpha 2-adrenoceptor agonist/antagonist yohimbine (0.1 mM) persistently and more strongly decreased the [Cl-]i than UK 14304-18 did. The yohimbine-induced decrease in the [Cl-]i was not further altered by UK 14304-18 or phenylephrine, but partly reversed by noradrenaline, isoproterenol and an adenylate cyclase activator, forskolin (0.1 mM). The yohimbine-induced decrease in [Cl-]i was inhibited by the carbonic anhydrase inhibitor acetazolamide (1 mM), and Cl-/HCO3- exchange inhibitors, 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, but not by the H(+)-ATPase inhibitor N,N'-dicylohexylcarbodiimide. The forskolin-induced recovery in [Cl-]i was inhibited by the Na+/K+/Cl- cotransport inhibitor bumetanide (0.1 mM), but not by the Cl- channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed1995

Comparisons among feline herpesvirus type 1 isolates by immunoblot analysis.

Feline herpesvirus type 1 (FHV-1) isolated from cats suspected for feline viral rhinotracheitis could be divided into 3 genotypes (C7301, F2 and C7805 types) by digestion pattern with a restriction enzyme M1uI[16]. Variation of immunogenic products of 77 isolates were examined by immunoblot analysis using a polyvalent cat serum against C7301 strain, Japanese prototype strain of FHV-1. The result showed that a 36 kDa band was detected in 31 out of the 63 isolates belonging to C7301 type. However the band was not observed in the remaining 32 isolates of C7301 type and 14 isolates belonging to either F2 or C7805 type. In one isolate (91-58) of C7301 type, approximately 75 kDa band instead of 70 kDa band was observed, although the other bands were commonly observed in the remaining 76 isolates. From the results of the present and previous studies, FHV-1 field isolates could be divided into at least 4 groups and this grouping might be applicable for epidemiological studies of FHV-1 infection in the field.

Alphaherpesvirinae↗

PubMed1995

Seroepidemiological survey of feline retrovirus infections in cats in Taiwan in 1993 and 1994.

In order to investigate the prevalence of infections with three feline retroviruses feline immunodeficiency virus (FIV), feline leukemia virus (FeLV) and feline syncytial virus (FSV) in Taiwan, we collected a total of 75 blood samples from cats from veterinary hospitals, a breeding cattery and a homeless shelter in 1993 and 1994. We examined the presences of anti-FIV and FSV antibodies and FeLV-p27 antigen in these samples by the indirect immunofluorescence and/or enzyme-linked immunosorbent assays. All of the serum samples positive for FIV were obtained from homeless cats and the overall FIV positive rate was 4%. The overall positive rates of FSV and FeLV were 28% and 1.3%, respectively. From these results, together with previous seroepidemiological surveys by others, it was revealed that the prevalence of FIV and FeLV infections appeared to be lower in Taiwan than in the United States or Japan. In contrast, the prevalence of FSV infection in Taiwan was as high as that in Japan.

Animals↗

PubMed1995

Detection of canine distemper virus nucleocapsid protein gene in canine peripheral blood mononuclear cells by RT-PCR.

For a rapid diagnosis of canine distemper virus (CDV) infection, the reverse transcription-PCR (RT-PCR) was carried out to detect CDV nucleoprotein (NP) gene from canine peripheral blood mononuclear cells (PBMCs). Two sets of primers were targeted to two regions of NP gene of CDV Onderstepoort strain. The NP gene fragments were well amplified by the RT-PCR in each of the RNA extracts from Vero cells infected with 6 laboratory strains of CDV including Onderstepoort strain, and from PBMCs of a dog experimentally infected with CDV. The amplified NP gene was detected in 17 of 32 samples from dogs which were clinically suspected for CDV infection at veterinary hospitals. No RT-PCR product was found in 52 samples from healthy dogs including 40 specific pathogen free beagles vaccinated with an attenuated live virus-vaccine for CDV and 12 stray dogs. The RT-PCR provides a fast, sensitive, and supplementary method for the diagnosis of CDV infection in dogs.

Animals↗

PubMed1995

Quantification of feline immunodeficiency virus (FIV) proviral DNA in peripheral blood mononuclear cells of cats infected with Japanese strains of FIV.

The polymerase chain reaction (PCR) method was applied for measurement of the proviral DNA copy number of feline immunodeficiency virus (FIV) in peripheral blood mononuclear cells (PBMC) of cats experimentally and naturally infected with FIV. In experimentally infected cats except one cat infected with the Petaluma strain, FIV-specific DNAs were efficiently amplified with the PCR method under the conditions used in this study. In the naturally FIV-infected cats, the specific DNAs were also amplified. We established a quantitative method for measurement of proviral DNA copy number in PBMC from cats infected with TM2-type of FIV strains, and found that the number was variable among the six cats examined, ranging from 10(4.0) to 10(5.7) copies per 10(5) PBMCs. This method can be applicable to cats naturally infected with FIV of TM2-type. Proviral DNA quantitation developed here could be useful as an additional parameter to evaluate the relationships among the proviral load, immune response and development of the clinical symptoms, and to monitor efficacy of antiviral therapy in vivo.

Animals↗

PubMed1995

Suppression of canine parvovirus growth in CRFK cells by canine distemper virus.

The growth of canine parvovirus (CPV) in Crandell feline kidney cells was suppressed when canine distemper virus (CDV) was simultaneously inoculated. The both virus antigens were found in the same cells. The synthesis of capsid protein antigen of CPV decreased in the co-inoculated cells. The growth of CDV was not affected by co-inoculation with CPV. These results suggest that the CDV showed suppressive effects on the CPV growth in cells when they are inoculated simultaneously.

Animals↗

PubMed1995

Establishment of carrier-state infection of a feline renal cell line with feline syncytial virus.

Although feline syncytial virus (FSV) is normally highly cytopathogenic in Crandell feline kidney cells, a non-cytopathic persistent infection was established in the cells after cocultivation of the initially infected cells with uninfected cells 4 times. More than 90% of the persistently infected cells were positive for FSV antigen, and electron microscopy showed that the culture produced morphologically normal FSV. Virus from the carrier culture was infectious, however, the titer of the virus from the culture was lower than that from the cytocidally infected CRFK cells.

Animals↗

PubMed1995

Construction of the recombinant feline herpesvirus type 1 deleted thymidine kinase gene.

We constructed a recombinant virus containing defined deletion within thymidine kinase (TK) gene from feline herpesvirus type 1 (FHV-1) C7301, which was isolated in Japan, by standard rescue procedures with thymidine arabinoside (araT) selection. The araT resistant recombinant virus was designated as C7301dlTK. Southern blot analysis, together with polymerase chain reaction, revealed a deletion with the expected size, based on agarose gel electrophoresis, of the TK gene region in the C7301dlTK. Growth kinetics of the C7301dlTK in CRFK cells was similar to that of ther parent C7301 that possesses TK activity. However, plaques produced by the C7301dlTK were significantly smaller than those of the parent virus. This report migth be applicable for the development of a new genetically engineered FHV-1 vaccine.

Animals↗

PubMed1995

Serological survey of canine distemper virus infection using enzyme-linked immunosorbent assay.

For detection of antibodies against canine distemper virus (CDV), an enzyme-linked immunosorbent assay (ELISA) was developed using a crude extract from cells infected with the Onderstepoort strain of CDV as antigen. Twenty-six sera from dogs experimentally vaccinated with the Snyder-Hill strain of CDV were compared by ELISA and a standard virus neutralization (NV) test. Since a good correlation between the titers obtained by both tests was observed, ELISA was considered to be a rapid and reliable method for a serological survey of CDV infection. When a total of 167 sera from dogs suspected of canine distemper under natural conditions were examined by the ELISA, 29 of the sera (17%) were found to have low VN antibody titers and high ELISA titers. The reason for the discrepancy in the titers was discussed.

Animals↗

PubMed1995

Influence of partial hepatectomy in dogs on trimethadione metabolism and microsomal monooxygenases.

1. The recovery of trimethadione (TMO) metabolism and its association with liver weight and the activity of TMO N-demethylase have been reported in rat following partial (68%) hepatectomy. In the present study, we examined the effect of liver regeneration on hepatic P450 isozymes and TMO metabolism in dog. 2. The ratio of dimethadione (DMO), being the only TMO metabolite, to TMO at 2 h after i.v. injection of TMO (4 mg/kg) fell to 80% of that in the preoperative animals by 24 h after hepatectomy. The DMO/TMO ratio gradually recovered from days 7 to 14, and by day 21 after hepatectomy it had increased to about 25%. At 28 days post-hepatectomy the ratio had returned to preoperative levels. 3. The activity of benzphetamine N-demethylase, TMO N-demethylase, p-nitro-anisole O-demethylase and aniline hydroxylase increased 3 days post-hepatectomy, exhibiting levels 4.77, 3.45, 1.51 and 1.91 times greater respectively than that of the preoperative liver in the same animal. Two weeks post-hepatectomy these activities had returned to normal. The activity of the 16 beta- and 2 beta-hydroxylation of testosterone was unchanged. However, the activity of 6 beta-hydroxylase decreased 7 days post-hepatectomy, while 16 alpha-hydroxylation had increased at 3 and 7 days post-hepatectomy compared with controls. 4. The changes in liver weight were nearly restored to preoperative levels 7 days post-hepatectomy. 5. Although the P450 content was unchanged from days 1 to 7 post-hepatectomy, it had decreased by 30% at day 14 and by 20% at day 28. The P4502B11 content 3, 7 and 14 days post-hepatectomy had increased 8, 10 and 2 times respectively, while the P4503A12 content at 7 and 14 days decreased by 30 approximately 50% compared with that of the pre-operative liver. 6. The data presented above do not reveal any relationship between P4502B11 induction and liver regeneration. The reason for such a change is unknown, therefore further investigation needs to be carried out.

Animals↗

PubMed1995

Hormonal control of cholesterol cholelithiasis in the female hamster.

Male golden Syrian hamsters from Sasco form cholesterol gallstones when fed a lithogenic diet; in contrast, female hamsters are resistant to stones when fed the identical diet. Upon addition of the synthetic androgen, methyl-testosterone, to the diet, the incidence of cholesterol gallstones in female hamsters increased from 0% to 40% after 3 weeks and from 0% to 86% after 6 weeks. Cholesterol cholelithiasis remained high in the males. Biliary cholesterol and phospholipid levels were elevated in the females fed the hormone and approached those of the males. The cholesterol saturation of bile in the females increased from 36% to 75% after 3 weeks and from 54% to 109% after 6 weeks. In addition, an appreciable proportion of the cholesterol in the bile of female hamsters was now present in the form of vesicles. The bile acid composition was significantly altered by methyltestosterone even though the total bile acid concentration did not change; the bile acid composition of the female hamsters approached that of the males. The glycine to taurine ratio of the bile acids was drastically reduced by methyltestosterone in the females and to a lesser extent in males. In summary, in female hamsters the addition of methyltestosterone to the lithogenic diet induced cholesterol gallstones, elevated total biliary phospholipid and cholesterol, altered the bile acid composition, and changed the distribution of cholesterol from micelles to vesicles. The data obtained so far do not enable us to define the precise mechanism of action of methyltestosterone.

Animals↗

PubMed1995

Molecular interactions between retroviruses and herpesviruses.

Human and animal herpesviruses are able to stimulate gene expression of various human and animal retroviruses and the activation appears to be a common theme. It is of interest why the retroviruses can be commonly activated by herpesviruses despite clear diversities in each mechanism for retrovirus gene expression. In this review, three typical examples of the interactions; human immunodeficiency virus and human herpesviruses, avian retroviruses and Marek's disease virus, and feline immunodeficiency virus and feline herpesvirus type I will be given to respond the above question on the basis of the comparative study of molecular interactions.

Alpharetrovirus↗

PubMed1994

A gD homologous gene of feline herpesvirus type 1 encodes a hemagglutinin (gp60).

A gene-encoding glycoprotein D (gD) homologue of feline herpesvirus type 1 (FHV-1) was identified and sequenced. It was located within an EcoRI 4.3-kbp fragment in the middle of the unique short region. The primary translation product of the gD homologous gene is predicted to consist of 374 amino acids with a molecular weight (MW) of 43.2 kDa. Comparative analysis among gD counterparts of other herpesviruses revealed that six cysteine residues which correlate with disulfide bond structure were conserved, and the amino acid sequences had homologies of 32.6% with bovine herpesvirus type 1 gIV, 29.1% with pseudorabies virus gp50, 28.3% with equine herpesvirus type 1 gD, and 22.0% with herpes simplex virus type 1 gD. When the gD homologue was expressed in COS cells and examined by indirect immunofluorescence and immunoprecipitation assays, it was recognized only by monoclonal antibodies (MAbs) reactive with gp60 which have virus-neutralizing and hemagglutination (HA)-inhibition (HI) activities. This expressed product had a MW of approximately 60 kDa and was shown to be a hemagglutinin by HA and HI tests with the MAbs. These results suggest that the gD homologue of FHV-1 is a hemagglutinin.

Amino Acid Sequence↗

PubMed1994

An improved method for detecting cytostatic toxin (emetic toxin) of Bacillus cereus and its application to food samples.

We developed an improved HEp-2 cell assay method for the detection of Bacillus cereus toxin, which affects the proliferation of HEp-2 cells. The cytostatic toxin was stable upon exposure to heat, pH 2, pH 11 and trypsin, which suggests it is an emetic. Using the HEp-2 cell assay, we examined the distribution and contamination of B. cereus strains that produced an emetic toxin in various foods. Although there were 228 enterotoxin producers among 310 B. cereus strains obtained from foods, 16 of them produced the cytostatic type (emetic toxin). All of the strains that produced the cytostatic toxin were of the H.1 serotype.

Bacillus cereus↗

PubMed1994

Nucleotide sequence analysis of Marek's disease virus (MDV) serotype 2 homolog of MDV serotype 1 pp38, an antigen associated with transformed cells.

Marek's disease (MD) virus (MDV) serotype 1 (MDV1) pp38, an antigen associated with MD-transformed cells, has been identified as an MDV1 serotype-specific antigen by analyses using specific monoclonal antibodies (MAbs). In the present study, we determined the region in the MDV serotype 2 (MDV2) genome that has homology with the MDV1 pp38 gene. As a result of sequence analysis, it was determined that an open reading frame (ORF) existed in this region. Furthermore, Northern blot analysis and reverse transcriptase polymerase chain reaction confirmed the existence of an RNA transcript related to the ORF in MDV2-infected cells. Computer analyses revealed that MDV1 pp38 could be divided into two parts; one part was highly homologous and the other part was not homologous with the peptides deduced from the ORF of MDV2, indicating that the epitope recognized by a MDV1 pp38-specific MAb is located in the latter part.

Amino Acid Sequence↗

PubMed1994

Nucleotide sequence and characterization of the feline herpesvirus type 1 immediate early gene.

We report the nucleotide sequence of feline herpesvirus type 1 (FHV-1) immediate early (IE) gene encoding a homologue to the ICP4 protein of herpes simplex virus type 1 and its flanking sequences. When we examined the regulatory function of the FHV-1 IE gene product by using the transient transfection assay with an effector plasmid expressing the FHV-1 IE gene in combination with chimeric various promoter-chloramphenicol acetyltransferase reporter constructs, the product was able to transactivate a putative FHV-1 TK promoter, pseudorabies virus and equine herpesvirus type 1 ICP4 promoters, and human immunodeficiency virus (HIV) long terminal repeat (LTR) in Crandell feline kidney cells. Furthermore, the FHV-1 IE gene product could transactivate both feline immunodeficiency virus and HIV LTRs in SW480 cells but not in Felis catus whole fetus 4 cells.

Alphaherpesvirinae↗

PubMed1994

O6-alkylguanine-DNA alkyltransferase activity of human malignant glioma and its clinical implications.

Activity of the DNA repair protein O6-alkylguanine-DNA alkyltransferase (AGT) is an important determinant of responsiveness of tumor cells to chloroethylnitrosoureas (CENUs), representative chemotherapeutic agents for primary malignant gliomas. In order to assess the real states of this repair protein in human malignant gliomas, we assayed AGT activity in surgically extirpated 42 malignant glioma samples and studied the distribution of the activity under certain clinical conditions. There were wide variations in AGT activity between individuals. No significant difference in AGT activity on average was seen either between glioblastoma and anaplastic astrocytoma, nor between primary and recurrent tumors. Among 42 malignant gliomas, 7 samples (16.7%) had low AGT activity less than 0.1 pmoles/mg protein. In the case of glioblastoma, tumors possessing higher AGT activity tended to be less responsive to post-operation remission-induction therapy including CENUs. The result of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) chemosensitivity assay by using the corresponding surgical specimens suggested a close relationship between cellular resistance to CENUs and AGT activity. It was found to be unlikely that a short term administration of CENUs had a significant effect on AGT activity of brain tumors in human body. We could detect a bit of definite evidences of the relevance of AGT to resistance to CENUs and need to conduct further investigations for other resistance factors.

Astrocytoma↗

PubMed1994

Combined antitumor effects of TNF and G-CSF on a human medulloblastoma xenograft line.

The antitumor effects of TNF and G-CSF on a xenograft line of human medulloblastoma were examined. (Method):1) A human medulloblastoma xenograft line was transplanted into nude mice. Tumor bearing nude mice were divided into the following eight groups: untreated controls (C); those receiving a subcutaneous injection of G-CSF for one week (G1); for four weeks (G2); those receiving an intratumoral injection of TNF for four weeks (Tit); an intravenous injection of TNF (Tiv); those receiving a combination of G1 and Tit (G1 + Tit); a combination of G2 and Tit (G2 + Tit); and a combination of G2 and Tiv (T2 + Tiv). The relative tumor weight in each group was calculated and any antitumor effects were examined by calculating a tumor growth inhibition ratio. 2) Tumor bearing nude mice were divided into the following two groups: those receiving a subcutaneous injection of G-CSF and an intravenous injection of TNF (G+T); and only an intravenous injection of TNF (T). We evaluated the pathological findings from the tumors at 0 h, 0.5 h, 1 h, 3 h, 6 h, 12 h, 24 h and 48 h after the TNF injection. Routine H.E. staining and immunostaining using antigranulocyte and antimacrophage antibodies were performed. (Results): 1) The tumor growth inhibition ratio was 0.112, 0.190, 0.287, 0.451, 0.347, 0.635, and 0.622 at G1, G2, Tit, Tiv, G1 + Tit, G2 + Tit, G2 + Tiv group. A combined antitumor effect was clearly seen in the G2 + Tit and the G2 + Tiv groups. 2) The tumor was fragmented by the infiltration of many inflammatory cells 24 hours after TNF injection. Many more macrophages were observed in the tumors of G+T mice than in the T mice. Granulocytes were observed only in the tumors of the G+T mice.

Animals↗