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Biomedical subjects

T Mikami

Publications and source records attributed to T Mikami.

At least 91 records · Page 5Linked to original sources
PubMed2000

FGF-20, a novel neurotrophic factor, preferentially expressed in the substantia nigra pars compacta of rat brain.

We have isolated cDNA encoding a novel FGF (212 amino acids) from rat brain. Because this is the 20th documented member of the FGF family, we tentatively term it FGF-20. Among FGF family members, FGF-20 is most similar to FGF-9 and FGF-16 (70 and 62% amino acid identity, respectively). Human FGF-20 gene was found in the human genomic sequence mapped to the 8p21.3-p22 region. Human FGF-20 is highly identical to rat FGF-20 (95% amino acid identity). FGF-20 mRNA was preferentially expressed in rat brain among the adult major tissues examined. The localization of FGF-20 mRNA in rat brain was also examined by in situ hybridization. FGF-20 mRNA was preferentially expressed in the substantia nigra pars compacta. To examine the biological activity of FGF-20, recombinant rat FGF-20 was produced by insect cells infected with recombinant baculovirus containing rat FGF-20 cDNA. Recombinant rat FGF-20 enhanced the survival of midbrain dopaminergic neurons. The present results indicate that FGF-20 is a novel neurotrophic factor preferentially expressed in the substantia nigra pars compacta of rat brain.

Amino Acid Sequence↗
PubMed2000

Brain-specific expression of a novel human UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (GalNAc-T9).

We isolated cDNA coding for the ninth of the UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-T9) from human brain by the polymerase chain reaction. The polypeptide encoded by GalNAc-T9 contained the structural features characteristic of GalNAc transferases, such as a GT1 motif, a Gal/GalNAc transferase motif, (QXW)(3) repeats, and conserved His, Cys, and acidic amino acid residues. Northern blot analysis revealed the mRNA expression of the enzyme to be confined to the brain. The brain-specific expression of GalNAc-T9 suggested that this isozyme catalyzes O-glycosylation in the brain.

Amino Acid Sequence↗
PubMed2000

Decreased expression of CD44, alpha-catenin, and deleted colon carcinoma and altered expression of beta-catenin in ulcerative colitis-associated dysplasia and carcinoma, as compared with sporadic colon neoplasms.

BACKGROUND: To clarify the cell adhesion status in ulcerative colitis (UC)-associated colon neoplasm, expression of cell adhesion molecules were investigated and compared with that of sporadic colon neoplasm. METHODS: A total of 14 low grade dysplasias, 16 high grade dysplasias, and 8 adenocarcinomas associated with UC and 17 sporadic adenomas with mild to moderate dysplasia, 22 adenomas with severe dysplasia, and 15 invasive adenocarcinomas were immunohistochemically examined using monoclonal antibodies against CD44, E-cadherin, alpha- and beta-catenin, and deleted colon carcinoma (DCC). RESULTS: CD44, especially its standard form, and DCC expression was stronger in the sporadic colon neoplasms than in the UC-associated lesions. Although E-cadherin did not show significant differences between the two cases, alpha-catenin was more expressed in sporadic colon adenomas with severe dysplasia and carcinomas than in their UC-associated counterparts. Membranous beta-catenin staining was stronger in UC-associated neoplasms, whereas sporadic lesions had greater cytoplasmic and nuclear expression. CONCLUSIONS: The differences in cell adhesion molecule expression suggests that UC-associated and sporadic colon neoplasms arise from different pathways of tumorigenesis.

Cadherins↗
PubMed2000

The complete nucleotide sequence of the mitochondrial genome of sugar beet (Beta vulgaris L.) reveals a novel gene for tRNA(Cys)(GCA).

We determined the complete nucleotide sequence of the mitochondrial genome of an angiosperm, sugar beet (Beta vulgaris cv TK81-O). The 368 799 bp genome contains 29 protein, five rRNA and 25 tRNA genes, most of which are also shared by the mitochondrial genome of Arabidopsis thaliana, the only other completely sequenced angiosperm mitochondrial genome. However, four genes identified here (namely rps13, trnF-GAA, ccb577 and trnC2-GCA) are missing in Arabidopsis mitochondria. In addition, four genes found in Arabidopsis (ccb228, rpl2, rpl16 and trnY2-GUA) are entirely absent in sugar beet or present only in severely truncated form. Introns, duplicated sequences, additional reading frames and inserted foreign sequences (chloroplast, nuclear and plasmid DNA sequences) contribute significantly to the overall size of the sugar beet mitochondrial genome. Nevertheless, 55.6% of the genome has no obvious features of information. We identified a novel tRNA(Cys) gene (trnC2-GCA) which shows no sequence homology with any tRNA(Cys) genes reported so far in higher plants. Intriguingly, this tRNA gene is actually transcribed into a mature tRNA, whereas the native tRNA(Cys) gene (trnC1-GCA) is most likely a pseudogene.

Arabidopsis↗
PubMed2000

The role of CD4(+) or CD8(+) T cells in the protective immune response of BALB/c mice to Neospora caninum infection.

The role of CD4(+) or CD8(+) T cells in the immune response of BALB/c mice against Neospora caninum infection was examined by using anti-CD4 and/or anti-CD8 monoclonal antibodies (mAbs). Mice were intraperitoneally inoculated with anti-CD4 and/or anti-CD8 mAbs before and after infection with N. caninum and observed for 30 days after infection. Most of the anti-CD4 mAb-treated mice and all of the anti-CD4 and anti-CD8 mAbs-treated mice died within 30 days post-infection (p.i.). In contrast, 100% of PBS-treated mice and 70% of anti-CD8 mAb-treated mice survived more than 30 days. When compared with phosphate-buffered saline (PBS)-treated mice, the weight of mice treated with mAbs tended to decrease. From these results CD4(+) T cells, but not CD8(+) T cells, have an important role for protection of mice against N. caninum infection. Serum antibody levels to N. caninum in infected-mice treated with anti-CD4 mAb or a mixture of anti-CD4 and anti-CD8 mAbs were lower than those in the infected mice treated with anti-CD8 mAb or PBS. The mice treated with anti-interferon-gamma (IFN-gamma) mAb produced high antibody levels to N. caninum, but all mice died within 18 days p.i. These results indicated that IFN-gamma is an important cytokine for protection against N. caninum infection at the early stage of infection. However, since CD4(+) T cells against N. caninum were essential to the production of specific antibody, these antibodies might have important roles in host protection at the later stage of infection.

Animals↗
PubMed2000

Detection of Babesia caballi infection by enzyme-linked immunosorbent assay using recombinant 48-kDa merozoite rhoptry protein.

The 48-kDa Babesia caballi merozoite rhoptry protein was expressed using a pGEX4T expression vector in Escherichia coli as glutathione S-transferase fusion protein (GST-BC48), and the expressed GST-BC48 was used in an ELISA to detect specific antibodies in serum samples. No cross-reaction was observed with sera from horses experimentally infected with Babesia equi. GST-BC48 ELISA was a highly sensitive and specific test when compared with the CFT. A total of 209 horse sera obtained from Central Mongolia were examined with the GST-BC48 ELISA and 46.4% (97/209) were found to be seropositive for B. caballi, suggesting that the GST-BC48 ELISA can be successfully used for both quarantine and epidemiological studies.

Animals↗
PubMed2000

Fibroblast growth factor-16 is a growth factor for embryonic brown adipocytes.

In rat embryos, fibroblast growth factor (FGF)-16 is predominantly expressed in brown adipose tissue. To elucidate the role of FGF-16, we examined the expression of FGF-16 mRNA in rat embryonic brown adipose tissue at different developmental stages by Northern blotting analysis and in situ hybridization. FGF-16 mRNA was expressed abundantly in brown adipose tissue during embryonic day 17. 5, embryonic days 17.5-19.5, and thereafter at lower levels into the neonatal period. The expression profile of FGF-16 mRNA well corresponds to the proliferative profile of embryonic brown adipose tissue reported. We also examined the mitogenic activity of recombinant rat FGF-16 for primary brown adipocytes prepared from rat embryonic brown adipose tissue. FGF-16 showed significant mitogenic activity for primary brown adipocytes. The mitogenic activity was found to be exerted by binding and activating FGF receptor-4 in the brown adipose tissue. As a great induction of proliferation of rat brown adipose tissue during cold acclimation was reported, we also examined the expression of FGF-16 mRNA in the brown adipose tissue during cold acclimation by Northern blotting analysis. The expression of FGF-16 mRNA was not increased, but rather decreased. The expression profile of FGF-16 mRNA and the mitogenic activity of FGF-16 reported here indicate that FGF-16 is a unique growth factor involved in proliferation of embryonic brown adipose tissue.

Adipose Tissue, Brown↗
PubMed2000

Molecular cloning and sequencing of the cDNA encoding the feline FcgammaRIIIA (CD16) homologue.

We amplified the cDNA encoding the feline FcgammaRIIIA (CD16) homologue from peripheral blood mononuclear cells by polymerase chain reaction and cloned two forms of FCGR3A cDNA. Sequencing analysis revealed that the open reading frame of feline FCGR3A cDNA consists of 750 or 747 base pairs encoding 250 or 249 amino acid residues, respectively. Comparison of the predicted amino acid sequence of feline FCGR3A cDNA with those of other mammalians' homologues revealed that the extracellular domain has a relatively low homology. However, the cytoplasmic domain contained an 8-amino acid motif, Leu-Phe-Val-Val-Asp-Thr-Gly-Leu, which was considered to interact with an accessory molecule such as the gamma chain of Fc receptors for IgE to form heterodimeric complexes.

Amino Acid Sequence↗
PubMed2000

Comparison of the mutational spectra of the lacZ transgene in four organs of the MutaMouse treated with benzo[a]pyrene: target organ specificity.

We recently demonstrated that not all organs with a high rate of induction of mutation in the lacZ transgene develop tumors in the lambdalacZ transgenic mice (MutaMouse) used for a long-term carcinogenicity study with benzo[a]pyrene (BP). To better understand the role of chemical-induced in vivo mutations in carcinogenesis, we compared the mutational spectra of the lacZ transgene in four organs of the MutaMouse obtained 2 weeks after five daily consecutive oral treatments with 125 mg/kg/day BP. lacZ transgenes were analyzed in two target organs (forestomach and spleen) and two non-target organs (colon and glandular stomach) for BP-induced carcinogenesis in MutaMouse, and all of these organs were highly mutated in the lacZ transgene. The sequence data showed similar mutational spectra of the lacZ transgene between the two target organs; the predominant mutations were G:C-->T:A transversions (55% and 50% for forestomach and spleen, respectively), followed by deletions (20% and 21% for forestomach and spleen, respectively) mainly at G:C site. The frequent G:C-->T:A transversions are consistent with reports of the mutational spectra produced in the p53 gene in tumors generated in rats and mice exposed to BP. In contrast, the mutational spectra of the lacZ transgene in the two non-target organs are different from those in the target organs, and are also suggested to differ from one another. These findings suggest an organ/tissue-specific mechanism of mutagenesis.

Administration, Oral↗
PubMed2000

Expression of canine interferon-beta by a recombinant vaccinia virus.

A recombinant vaccinia virus expressing canine interferon (IFN)-beta was constructed (vv/cIFN-beta). In rabbit kidney (RK13) and canine A72 cells infected with vv/cIFN-beta, the recombinant canine IFN-beta was detected in both cell extracts and supernatants, and the IFN activities of the culture supernatants were also detected. Inhibition of N-linked glycosylation by tunicamycin treatment indicated that the recombinant canine IFN-beta was modified by N-linked glycosylation in a different way between RK13 and A72 cells, and that N-linked glycosylation is essential for its secretion. The growth of vv/cIFN-beta at a low multiplicity of infection was inhibited by antiviral activity of canine IFN-beta, indicating that this recombinant virus could be used as a suicide viral vector.

Animals↗
PubMed2000

A synthetic antagonist for the peroxisome proliferator-activated receptor gamma inhibits adipocyte differentiation.

While searching for natural ligands for the peroxisome proliferator-activated receptor (PPAR) gamma, we identified a synthetic compound that binds to this receptor. Bisphenol A diglycidyl ether (BADGE) is a ligand for PPARgamma with a K(d(app)) of 100 microM. This compound has no apparent ability to activate the transcriptional activity of PPARgamma; however, BADGE can antagonize the ability of agonist ligands such as rosiglitazone to activate the transcriptional and adipogenic action of this receptor. BADGE also specifically blocks the ability of natural adipogenic cell lines such as 3T3-L1 and 3T3-F442A cells to undergo hormone-mediated cell differentiation. These results provide the first pharmacological evidence that PPARgamma activity is required for the hormonally induced differentiation of adipogenic cells.

1-Methyl-3-isobutylxanthine↗
PubMed2000

Exercise myocardial perfusion scintigraphy is useful for evaluating myocardial ischemia even in the elderly.

Pharmacologic stress testing is recommended to elderly patients as a valuable alternative to exercise testing. We examined whether exercise testing is as useful for evaluating myocardial ischemia in the elderly as in the young. The consecutive 1,508 patients who underwent exercise 201Tl single-photon emission computed tomography (SPECT) were divided into six age groups: 6-29 years (n = 56), 30-44 (n = 143), 45-54 (n = 311), 55-64 (n = 498), 65-74 (n = 402), and 75-88 (n = 98). Both heart rate and rate-pressure product at peak exercise were significantly lower in patients aged 75-88 than in the other five groups. The frequency of ischemic ST depression was higher in patients aged 75-88 than in those aged 6-74, although the difference was not significant. Moreover, the frequency of 201Tl transient defect was significantly higher in patients aged 75-88 than in those aged 6-74. On the other hand, the sensitivity of ischemic ST depression for 201Tl transient defect was similar among the six groups, but the specificity was significantly lower in patients aged 75-88 than in those aged 6-74. In conclusion, exercise 201Tl SPECT is useful for evaluating myocardial ischemia even in the elderly, but exercise electrocardiography has limitations such as lower specificity in the elderly than 201Tl SPECT.

Adolescent↗
PubMed2000

Variable number of tandem repeat loci in the mitochondrial genomes of beets.

We found four unrelated tandem repeat loci (TR1, TR2, TR3 and TR4) in the mitochondrial genomes of beets, with the TR1 locus embedded within a three-membered family of recombining repeat sequences (the rrn26-repeat). TR1 is composed of an array of 32-bp tandem repeats, the number of which varies from 2 to 13 among the seven beet genotypes examined. It is interesting to note that TR1 has 7-bp direct repeats flanking the array, which may be involved in the generation of the tandem repeat array. Such striking features are shared by the remaining TR loci, and this is thus the first description of minisatellite nucleotide sequences from a higher-plant mitochondrial genome.

Base Sequence↗
PubMed2000

Growth-inhibitory effects of interferon-gamma on Neospora caninum in murine macrophages by a nitric oxide mechanism.

To clarify the effector pathway of Neospora caninum growth-inhibitory activity induced by interferon-gamma (IFN-gamma) in murine macrophages we examined the relationship between IFN-gamma and nitric oxide (NO). Production of NO was enhanced in cultures of macrophages supplemented with IFN-gamma, and dose-dependent growth inhibition was observed. These findings suggest that the inhibitory activity induced in macrophages by IFN-gamma is mediated NO molecules. A competitive inhibitor of the L-arginine-dependent effector pathway, NG-monomethyl-L-arginine, virtually abolished the inhibitory effects induced by IFN-gamma. From this finding it appears that the inhibitory effects induced by IFN-gamma in macrophages may be mediated by an L-arginine-dependent effector pathway that involves NO production. In vivo, mice with a targeted disruption of the inducible NO synthase gene (iNOS-/-) were more susceptible than wild-type mice to N. caninum. Therefore, the production of NO in macrophages induced by IFN-gamma is an important mechanism for the killing of intracellular N. caninum.

Animals↗
PubMed2000

Delivery of Neospora caninum surface protein, NcSRS2 (Nc-p43), to mouse using recombinant vaccinia virus.

In order to develop a vaccine against Neospora caninum in dogs and cattle, we constructed a recombinant vaccinia virus expressing the N. caninum surface protein, NcSRS2 (Nc-p43). Monoclonal antibodies to NcSRS2 and anti-N. caninum tachyzoite mouse serum recognized the NcSRS2 expressed by the recombinant vaccinia virus. In addition, recombinant NcSRS2 was transported to the cell surface. Mice infected with the recombinant virus predominantly produced IgG1 antibody (Ab) to N. caninum, rather than producing IgG2a Ab. Moreover, splenocytes from mice infected with the recombinant virus proliferated in the presence of the N. caninum antigen. Mice immunized with the recombinant virus gave rise to humoral and cellular immune responses to N. caninum tachyzoites. This study showed that a recombinant vaccinia virus expressing NcSRS2 might be useful for the production of a live vaccine against N. caninum infection.

Animals↗
PubMed2000

Expression of SAG-1 of Toxoplasma gondii in transgenic mice.

We describe the expression of SAG-1 cDNA in B6C3F1 mice by microinjecting a 3.3 kbp DNA fragment, consisting of the cytomegalovirus enhancer-chicken beta-actin hybrid promoter and SAG-1 into the pronucleus of a fertilized egg at the one-cell stage. Offspring derived from this microinjection were analyzed for the integration and functional expression of the SAG-1 transgene. Steady-state expressions of both the mRNA for SAG-1 and SAG-1 protein product were detected in the brain, thymus, spleen and liver. Approximately 50% of F1 and F2 progeny inherited the SAG-1 transgene from SAG-1 transgenic mice in Mendelian fashion. These results indicated that SAG-1 transgenic lines were established. Transgenic mice harboring the SAG-1 gene will contribute a critical tool of defining the molecular mechanisms of SAG-1 in pathogenesis and host immune response.

3T3 Cells↗