Biomedical subjects

T Mikami

Publications and source records attributed to T Mikami.

At least 343 records · Page 19Linked to original sources

PubMed1995

The C/EBP site in the feline immunodeficiency virus (FIV) long terminal repeat (LTR) is necessary for its efficient replication and is also involved in the inhibition of FIV LTR-directed gene expression by pseudorabies virus ICP4.

We investigated effects of site-specific mutation of the putative C/EBP binding site in the feline immunodeficiency virus (FIV) long terminal repeat (LTR) on the basal promoter activity in Crandell feline kidney (CRFK) cells and on replication efficiency in CRFK cells and a T-lymphoblastoid cell line, MYA-1 cells. Mutation of the C/EBP site reduced the basal promoter activity in CRFK cells and prevented efficient FIV replication in both CRFK and MYA-1 cells. Gel-mobility-shift assay using nuclear extracts from CRFK and MYA-1 cells revealed that the nuclear factor(s) actually binds to the C/EBP site, but there was a clear difference in the binding patterns to the C/EBP site between CRFK and MYA-1 cell nuclear proteins. Furthermore, we demonstrated that the C/EBP site is necessary for inhibition of FIV LTR-directed gene expression by pseudorabies virus (PRV) ICP4. The C/EBP site is sufficient to confer inhibitory effect by PRV ICP4 on heterologous promoters. These data suggest that the C/EBP site in the FIV LTR is important for the positive regulation of FIV gene expression and replication and is also required for the negative regulation of FIV gene expression by PRV ICP4.

Animals↗

PubMed1995

Physical and gene organization of mitochondrial DNA from the fertile cytoplasm of sugarbeet (Beta vulgaris L.).

We have constructed a complete physical map of the mitochondrial genome from the male-fertile cytoplasm of sugarbeet. The entire sequence complexity can be represented on a single circular master chromosome of 358 kb. This master chromosome contains three copies of one recombinationally active repeat sequence, with two copies in direct orientation and the other in inverted orientation. The positions of the rRNA genes and of 23 polypeptide genes, determined by filter hybridization, are scattered throughout the genome, with triplicate rrn26 genes located partially or entirely within the recombination-repeat elements. Three ribosomal-protein genes (rps1A, rps14 and rps19) were found to be absent from sugarbeet mtDNA. Our results also reveal that at least six regions homologous with cDNA are dispersed in the mitochondrial genome.

Chromosome Mapping↗

PubMed1995

The chloroplast trnP-trnW-petG gene cluster in the mitochondrial genomes of Beta vulgaris, B. trigyna and B. webbiana: evolutionary aspects.

The chloroplast trnP-trnW-petG gene cluster has been identified in the mitochondrial DNA (mtDNA) of sugar beet (Beta vulgaris). The chloroplast-derived trnW gene is transcribed in the mitochondria; the other two genes, however, do not seem to be transcribed. This gene cluster is also present in the mitochondrial genomes of two wild Beta species, B. trigyna and B. webbiana. Sugar beet and the two wild relatives share 100% sequence identity in the coding regions of both the mitochondrial trnP and trnW genes. On the other hand, the petG genes from the wild Beta mtDNAs were found to be disrupted either by a 5-bp duplication (B. trigyna) or by a deletion of the 5' region (B. webbiana). A data-base search revealed that a conserved sequence of 60 bp is present in the trnP-trnW intergenic region of the mitochondrial genomes of the three Beta species as well as in other higher plants, including wheat and maize, and that the conserved sequence is absent from the chloroplast counterpart. Our results thus favour the hypothesis of a monophyletic origin of the trnP-trnW-petG cluster found in the plant mitochondrial genomes examined.

Base Sequence↗

PubMed1995

Phylogenetic analysis of the long terminal repeat of feline immunodeficiency viruses from Japan, Argentina and Australia.

The nucleotide sequences of the long terminal repeat of five Japanese, five Argentine and three Australian isolates of feline immunodeficiency virus (FIV) were determined and compared with those of isolates previously described. The results revealed that the Japanese isolates were found to cluster with nucleotide sequence similarity of 95.6%-99.4%. The Australian isolates also clustered with nucleotide sequence similarity of 97.2%-99.4%. The Argentine isolates formed two groups; the LP9 isolate is closely related to the Japanese isolates, whereas the LP1, LP3, LP20 and LP24 isolates are distant from both the Japanese and Australian isolates. From these results, FIV can be divided into three groups, namely: (I) the Californian, Australian and British isolates; (II) the Japanese isolates and one Argentine LP9 isolate; (III) the other Argentine isolates.

Animals↗

PubMed1995

Hydrophilic bile acids: prevention and dissolution experiments in two animal models of cholesterol cholelithiasis.

The effects of beta-muricholic acid and hyocholic acid on cholesterol cholelithiasis were examined in two animal models. The following experiments were carried out: A) In a gallstone prevention study, prairie dogs were fed the lithogenic diet with or without 0.1% beta-muricholic or 0.1% hyocholic acid for eight weeks. B) In a second prevention study, hamsters were fed the lithogenic diet with or without 0.1% beta-muricholic acid or 0.1% hyocholic acid for six weeks. C) In a gallstone dissolution study, hamsters were fed the lithogenic diet for six weeks to induce stones; stone dissolution was examined during administration of a cholesterol-free purified diet with or without 0.1% beta-muricholic acid or 0.1% hyocholic acid. In the prevention study in prairie dogs (A), both bile acids failed to prevent stone formation, the cholesterol saturation index of bile was 0.89 in the lithogenic controls, remained unchanged with hyocholic acid and increased to 1.52 in the beta-muricholic acid group. In the prevention study in hamsters (B), beta-muricholic acid completely inhibited the cholesterol cholelithiasis (0% stone incidence); the cholesterol saturation index of bile was 1.78 (compared to lithogenic controls, 1.37). Hyocholic acid reduced stone incidence to 16% with a cholesterol saturation index of 0.98. In the dissolution study in hamsters (C), preexisting cholesterol gallstones were not dissolved by either hydrophilic bile acid after feeding these bile acids for an additional six weeks; at the end of the experiment, the cholesterol saturation indices were below unity.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1995

Dietary fat alters the distribution of cholesterol between vesicles and micelles in hamster bile.

The type of dietary fat strongly affects the incidence of gallstones in the hamster model of cholesterol cholelithiasis. The present study was designed to determine whether dietary fats could affect gallstone formation by altering the microstructure (vesicular/micellar ratio) of cholesterol in bile. Golden Syrian hamsters from Sasco (Omaha, NE) or Charles River (Wilmington, MA) were fed nutritionally adequate semipurified diets to which were added: (i) 4.0% butterfat without added cholesterol; (ii) 1.2% palmitic acid plus 0.3% cholesterol; or (iii) 4.0% safflower oil plus 0.3% cholesterol. Gallstone incidence and the percentage of cholesterol in vesicles and micelles were determined after two- or six-week feeding periods. Three out of ten Sasco hamsters fed the 1.2% palmitic acid diet for two weeks had cholesterol stones, while none of the eight Charles River animals had stones. In the Sasco hamsters, a significant proportion of the biliary cholesterol was found in void volume vesicles (28.8%) and small vesicles (17.1%); Charles River hamsters had negligible proportions (1.1%) of cholesterol in void volume vesicles and 15.4% in small vesicles. Cholesterol gallstones were most abundant in Sasco hamsters fed 1.2% palmitic acid for six weeks (nine out of ten animals); the mean cholesterol saturation index of the bile was 1.27. A significant proportion of the biliary cholesterol was eluted in the void volume vesicles (21.4%) and in small vesicles (15.0%). Five of the eight identically treated Charles River hamsters had cholesterol stones; the cholesterol saturation index averaged 1.36, and the biliary cholesterol was present in void volume vesicles (31.3%) and small vesicles (14.3%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Synthesis and metabolism of sodium 3 alpha,7 alpha-dihydroxy-25,26-bishomo-5 beta-cholane-26-sulfonate in the hamster.

This paper reports the chemical synthesis of a new bile acid analogue, namely sodium 3 alpha,7 alpha-dihydroxy-25,26-bishomo-5 beta-cholane-26-sulfonate (bishomoCDC-sul) from chenodeoxycholic acid and describes its metabolism in the hamster. The structure of the new compound was confirmed by proton and carbon-13 nuclear magnetic resonance spectroscopy. After intravenous infusion of [3H]-labeled sulfonate into bile fistula hamsters, it was extracted by the liver and secreted into the bile; more than 65% of the radioactivity was recovered in the bile within 1 h. Following intraduodenal administration of the [3H]sulfonate and [14C]chenodeoxycholyltaurine, both compounds were excreted into the bile more slowly; only 41 and 43% of the radioactivity, respectively, were recovered in the bile during the four-hour experimental period. In contrast, when the labeled compounds were injected into the terminal ileum, both the sulfonate and chenodeoxycholyltaurine were rapidly absorbed and secreted into the bile; 84 and 97%, respectively, of the radioactivity were recovered during a four-hour period. Chromatographic analysis demonstrated that in these short-term experiments most (> 95%) of the sulfonate was secreted into the bile without biotransformation regardless of the route of administration. When infused intravenously at increasing doses, bishomoCDC-sul induced cholestasis at an infusion rate of 1 mumol/min/kg. These results suggest that sodium 3 alpha,7 alpha-dihydroxy-25,26-bishomo-5 beta-cholane-26-sulfonate was absorbed from the terminal ileum by active transport, extracted by the liver, and secreted into the bile in a manner similar to that of the natural bile acids.

Animals↗

PubMed1995

Angiotensin-converting enzyme gene polymorphism in Japanese patients with hypertrophic cardiomyopathy.

To examine the contribution of the angiotensin-converting enzyme (ACE) gene to hypertrophic cardiomyopathy (HCM), we determined the ACE insertion/deletion (I/D) polymorphism in 80 patients with HCM and 88 of their unaffected siblings and children. Patients were divided into familial or solitary HCM (FHCM or SHCM) groups with or without affected family members. Genotypes were identified by the polymerase chain reaction (PCR) with oligonucleotide primers flanking the polymorphic region in intron 16 of the ACE gene to amplify template DNA prepared from peripheral leukocytes. D-allele frequencies were 0.38 in all subjects, 0.42 in patients with HCM, and 0.35 in relatives (p < 0.05). The probability ratios were 1.98, 1.46, and 2.97 in patients with HCM, FHCM, and SHCM, respectively. The D allele frequency was higher in SHCM than in FHCM (p < 0.05). The findings suggest that HCM, especially in solitary cases, is partially determined by genetic disposition. Findings imply that the ACE D allele is one of the genetic contributing factors associated with cardiac hypertrophy in HCM.

Aged↗

PubMed1995

Expression of Marek's disease virus (MDV) serotype 2 gene which has partial homology with MDV serotype 1 pp38 gene.

We constructed the recombinant baculovirus expressing the gene of non-pathogenic Marek's disease virus (MDV) serotype 2 (MDV2) which encodes a polypeptide with partial homology to MDV serotype 1 (MDV1) pp38, an antigen associated with transformed cells. The recombinant MDV2 protein was detected as a band of 32 kDa in immunoblot analysis with MDV2-infected chicken serum. Mouse serum against insect Spodoptera frugiperda cells infected with the recombinant baculovirus immunoprecipitated a 38 kDa molecule from the lysate of MDV2-infected chicken embryo fibroblasts (CEFs) but did not immunoprecipitate the MDV1 pp38 from the lysate of MDV1-infected CEFs. This result indicates that the recombinant MDV2 protein has no epitopes shared with the MDV1 pp38.

Animals↗

PubMed1995

Preparation of monoclonal antibodies against Marek's disease virus serotype 1 glycoprotein D expressed by a recombinant baculovirus.

A recombinant baculovirus, the genome of which contains DNA encoding Marek's disease virus serotype 1 (MDV1) homolog of glycoprotein D (gD) of herpes simplex virus under the polyhedrin promoter was constructed and designated rAcMDV1gD. Five monoclonal antibodies (MAbs) which recognize the MDV1 homolog of gD (MDV1 gD) in Spodoptera frugiperda cells infected with rAcMDV1gD were prepared. The MAbs reacted with proteins ranging from 52 to 49 kDa in rAcMDV1gD-infected cell lysates by immunoblot analysis. These molecular weights were coincident with molecular weights predicted from the open reading frame of MDV1 gD. By ELISA additivity test, the 5 MAbs were divided into 3 groups which seemed to recognize 3 different epitopes. In addition, all of the 5 MAbs were reactive with chick embryo fibroblasts (CEFs) expressing MDV1 gD. The MAbs are considered to be useful to study the role of MDV1 gD in MDV1 infection.

Animals↗

PubMed1995

Immunohistochemical analysis of the lymphoid organs of dogs naturally infected with canine distemper virus.

The pathogenesis of acute canine distemper in three naturally infected dogs was investigated. The lymphoid organs showed atrophy without secondary follicles. The distribution of canine distemper virus (CDV) antigens was examined immunohistochemically with monoclonal antibodies specific for canine Thy-1, immunoglobulin (Ig) M, CD4, CD8, CD21 and CD45RB, and anti-measles virus nucleocapsid protein serum. The viral antigens were located in the T-cell-dependent areas and in the follicles of lymphoid organs; they were observed mainly in the Thy-1, or CD4-positive cells, but also in the CD8-, CD21-, or IgM-positive cells. The results indicated that Thy-1-positive and CD4-positive T cells serve as major target cells for CDV during the acute stage of infection.

Animals↗

PubMed1995

Immunohistochemical studies of lymphoid tissues of rabbits infected with rinderpest virus.

The pathogenesis of infection with the L-strain of rinderpest virus (RPV) in rabbits was investigated. Of several lymphoid tissues examined, those associated with the gut showed the most marked virus growth. The virus titres were maximal 4 days after inoculation but had declined at day 6. The distribution of viral antigen was examined immunohistochemically with the recently established anti-rabbit CD5 monoclonal antibody (MoAb), which is a pan-T-cell marker, and the anti-RPV-nucleoprotein MoAb. The virus antigen was localized in the CD5+ area at the initial stage of infection but spread to all areas of the lymphoid tissues at the later stages. By flow cytometric analysis with both rabbit CD5 and CD4 MoAbs, a decrease of the CD4+ and CD5+ subpopulations was observed in the spleen and mesenteric lymph nodes.

Animals↗

PubMed1995

Expression and identification of the feline herpesvirus type 1 glycoprotein B (gp143/108).

The gene for feline herpesvirus type 1 (FHV-1) glycoprotein B (gB) has been cloned into an expression vector, pRVSVneo, containing the long terminal repeat of Rous sarcoma virus and polyadenylation signal of SV40. This expression vector containing FHV-1 gB gene, pRVSVgBneo, was transfected into Crandell feline kidney (CRFK) cells which are susceptible to FHV-1 infection. By indirect immunofluorescence analysis, the expressed gB was recognized with a panel of monoclonal antibodies (MAbs) against FHV-1 gp143/108. Immunoprecipitation analysis using a MAb 34H12 showed that molecular weights of the gB were 143 and 108 kDa under non-denaturing conditions that 108, 70, 64, and 58 kDa under denaturing conditions. The molecular weights were similar to those of the gB expressed in FHV-1-infected CRFK cells. In addition, when plasmid DNAs were injected into mice to obtain gB-monospecific serum, the pooled serum from mice inoculated with pRVSVgBneo, but not with pRVSVgDneo or pRVSVneo, recognized the FHV-1 gB polypeptides.

Animals↗

PubMed1995

Temporal patterns of feline immunodeficiency virus transcripts in peripheral blood cells during the latent stage of infection.

We have investigated the in vivo state of feline immunodeficiency virus (FIV) transcription in peripheral blood mononuclear cells (PBMC) of chronically FIV-infected, asymptomatic cats. FIV was detected in a high percentage of PBMC but not in the plasma of these cats. By quantitative reverse transcription-PCR (RT-PCR) analysis. FIV transcriptional status in the PBMC was characterized by extremely low or undetectable levels of unspliced or singly spliced mRNAs and predominantly multiply spliced mRNAs. Upon stimulation in vitro, however, the larger mRNA species and infectious virus production were rapidly induced in the PBMC. Furthermore, we demonstrated that viral production was induced in association with differential increases in the levels of each multiply spliced mRNA coding for FIV regulatory proteins. From these results, we suggest that replication of FIV is blocked at an early stage of gene expression in vivo, as described in asymptomatic human immunodeficiency virus (HIV) -infected patients, and that FIV infection in cats may be a useful model for clinical latency of HIV infection in man. Moreover, we propose that the replication of FIV in vivo may be controlled by the differential expression of each multiply spliced mRNA.

Animals↗

PubMed1995

Restriction endonuclease analysis of field isolates of feline herpesvirus type 1 and identification of heterogeneous regions.

The genomic heterogeneity of 78 isolates of feline herpesvirus type 1 (FHV-1) recently isolated from cats suspected to have feline viral rhinotracheitis was analyzed by examining the digestion patterns found with restriction endonuclease MluI. The FHV-1 field isolates were classified into at least three genotypes, namely, the C7301, F2 (an attenuated vaccine strain), and C7805 types. The C7301 type seems to be a major type, since 64 of the 78 isolates belonged to this type. Eight and six isolates belonged to the F2 and C7805 types, respectively. Compared with the C7301 type, the heterogeneous region of the F2 type was localized to a 4.3-kbp EcoRI fragment within the US segment and the heterogeneous region of the C7805 type was localized to a 5.5-kbp XbaI fragment within the UL segment. Northern (RNA) blot analysis revealed no differences in the products transcribed from these regions. In addition, nucleotide sequence analysis showed that the MluI sites not found in the F2 and C7805 types were located in the regions homologous to the herpes simplex virus type 1 gI and UL5 genes, respectively.

Animals↗

PubMed1995

Investigation of phagocyte-inducible factor in tumor-implanted mice.

The number of spleen Mac-1-positive cells was markedly increased in methylcholanthrene-induced Meth-A fibrosarcoma (Meth-A)-implanted mice. When the sera of Meth-A-implanted mice were added to normal bone marrow cells, granulocyte and macrophage colony stimulating factor (GM-CSF)-dependent growth of bone marrow cells was significantly enhanced. Analysis of the Meth-A-implanted mice sera showed that the levels of serum transferrin were markedly elevated. When the sera of Meth-A-implanted mice were pretreated with anti-mouse transferrin antibody, the enhancement of GM-CSF-dependent cell growth was almost abolished. Cell growth was also stimulated by the addition of transferrin which also caused an increase in the number of Mac-1-positive cells. Analysis of the effect of transferrin on bone marrow cells showed that the response of the cells to GM-CSF was significantly increased by preincubation with transferrin.

Animals↗

PubMed1995

Synthesis and antitumor activity of novel dolastatin 10 analogs.

Dolastatin 10 (1) is a potent antineoplastic pentapeptide. Novel dolastatin 10 analogs each modified at one of the constituent amino acid derivatives, were synthesized and their antitumor activity was evaluated against P388 leukemia in mice. The structural requirements for antitumor activity are discussed. Some of the analogs, 31c, 35c, 38b, and 50c showed excellent activity in vivo. Highly active 50c, which lacks the thiazole group of 1, was selected for further development as an antitumor agent.

Animals↗

PubMed1995

[Examination of toxin production from environmental Bacillus cereus and Bacillus thuringiensis].

Emetic toxin- and entero toxin-producing activities were examined for 524 strains of Bacillus cereus and 90 strains of Bacillus thuringiensis to determine the distribution and contamination in natural environment, including foods, vegetable, soil and etc. Emetic toxin was assayed by the production of acid from HEp-2 cells induced by the culture supernatants of Bacillus, which was developed as an improved method for the detection of B. cereus heat-stable emetic-toxin by us. In the 524 strains of B. cereus tested, 11 out of 60 strains obtained from bean paste and 5 out of 20 strains obtained from peach produced emetic toxin which was detected by the HEp-2 cell method. All these emetic toxin-producing isolate strains were classified into H1 serotype. The 90 strains of B. thuringiensis did not produce emetic toxin, but the 47 strains produced entero toxin.

Bacillus cereus↗