Biomedical subjects

M Ohta

Publications and source records attributed to M Ohta.

At least 55 records · Page 3Linked to original sources

PubMed2002

[WHO classification in thymoma].

WHO classification of thymic epithelial tumors have been shown to reflect their oncological behaviors, and type A, AB and B1 tumors have better prognosis than type B2 and B3 tumors, suggesting the significance of this classification in the clinical practice of thymomas. Type B tumors are more invasive than type A and AB tumors. Type B1 and B2 tumors are frequently associated with myasthenia gravis while type A and AB tumors are not. The findings of computed tomography (CT) imaging revealed that type A and AB tumors tend to be round and have the smooth surface while type B1, B2 and B3 tumors are often flat and have irregular surface. Type AB, B1 and B2 tumors possess a significant number of CD4+CD8+ double positive T cells in the tumor. These observations are supposed to be useful for preoperative evaluation of WHO classification of thymomas, and to help the clinicians decide application of preoperative therapy and the method of surgical resection including endoscopic surgery.

Humans↗

PubMed2001

A novel spermatogenesis-related factor-1 gene expressed in maturing rat testis.

A rat gene with testis-specific expression coinciding with spermatogenesis was cloned by differential display. This spermatogenesis-related factor-1 (SRF-1) gene was not expressed in other organs. Testicular expression was detected from 5 weeks of age and increased up to 15 weeks; this level of expression was maintained for 63 weeks. The 750-bp cloned gene was coded for an open reading frame of 202 amino acids. According to in situ hybridization at 7 weeks, this gene was expressed mainly in spermatocyte. The gene product may function as a molecular motor in meiosis, as the deduced amino acid sequence showed partial homology with kinesin-related proteins. The action of this gene and its product with respect to division of reproductive cells requires further investigation.

Amino Acid Sequence↗

PubMed2001

Ganglioside GD1a inhibits HGF-induced motility and scattering of cancer cells through suppression of tyrosine phosphorylation of c-Met.

We previously reported that ganglioside GD1a, which is highly expressed in poorly metastatic FBJ-S1 cells, inhibits the serum-induced motility of FBJ-LL cells and that the metastatic potential of FBJ-LL cells is completely suppressed by enforced GD1a expression (Hyuga et al., Int J Cancer 1999;83:685-91). We recently discovered that hepatocyte growth factor (HGF) induces FBJ-LL cell motility. In the present study, the HGF-induced motility of FBJ-S1 cells was found to be one-thirtieth that of FBJ-LL cells. This motility of GD1a-expressing transfectants, which were produced by transfection of FBJ-LL cells with GM2/GD2 synthase cDNA, decreased with increases in their GD1a expression and HGF induced almost no motility in GD1a-pretreated FBJ-LL cells, indicating that GD1a inhibits the HGF-induced motility of FBJ-LL cells. The expression of the HGF receptor c-Met on FBJ-S1 cells, FBJ-LL cells, transfectants and a mock-transfectant was almost the same. The level of tyrosine phosphorylation of c-Met after HGF stimulation in FBJ-S1 cells, GD1a-pretreated FBJ-LL cells and a GD1a-expressing transfectant was significantly lower than in FBJ-LL cells and a mock-transfectant. These findings suggested that GD1a inhibits the HGF-induced motility of FBJ-LL cells through suppression of tyrosine phosphorylation of c-Met. HepG2 cells, a human hepatoma cell line, were used to investigate whether GD1a interferes with other cancer cells expressing c-Met. HepG2 cells did not express GD1a. HGF induced cell scattering of HepG2 cells and the scattering was inhibited by pretreating the cells with GD1a. The c-Met in the cells was autophosphorylated by stimulation with HGF, but after treating the cells with GD1a, the HGF-induced autophosphorylation of c-Met was suppressed. These results suggest that GD1a acts as a negative regulator of c-Met in cancer cells.

Actins↗

PubMed2001

Marked reduction of the Cu/Zn superoxide dismutase polypeptide in a case of familial amyotrophic lateral sclerosis with the homozygous mutation.

We identified a missense mutation of the Cu/Zn superoxide dismutase (SOD) gene (Leu126Ser) in a Japanese family with ALS that included a patient with the homozygous mutation. The content of the Cu/Zn SOD polypeptide in erythrocytes was markedly reduced in the case with the homozygous mutation compared to those with the heterozygous mutation. We speculated that this reduction of the mutant Cu/Zn SOD molecule might be related to the severe clinical phenotype of the case.

Adult↗

PubMed2001

Tumor necrosis factor gene polymorphisms in patients with sporadic Parkinson's disease.

We studied promoter region polymorphisms in the tumor necrosis factor (TNF) gene at position -1031, -863, and -857, in 172 Japanese patients with sporadic Parkinson's disease (PD). The frequency of the -1031C allele, a high producer of TNF, increased significantly in early onset PD patients compared with controls. In addition, PD patients with the -1031C allele showed a significantly earlier onset than those without -1031C allele, after stratification of the data by an interleukin-1beta gene polymorphism. Our findings suggest that TNF might have a toxic effect in PD.

Adult↗

PubMed2001

Trehalose sensitivity in Drosophila correlates with mutations in and expression of the gustatory receptor gene Gr5a.

Drosophila taste gene Tre is located on the distal X chromosome and controls gustatory sensitivity to a subset of sugars [1, 2]. Two adjacent, seven-transmembrane domain genes near the Tre locus are candidate genes for Tre. One (CG3171) encodes a rhodopsin family G protein receptor [3, 4], and the other (Gr5a) is a member of a chemosensory gene family encoding a putative gustatory receptor [5-7]. We carried out molecular analyses of mutations in Tre to elucidate their involvement in the gustatory phenotype. Here, we show that Tre mutations induced by P element-mediated genomic deletions disrupt Gr5a gene organization and the expression of Gr5a mRNA, while disruption of the CG3171 gene or its expression was not always associated with mutations in Tre. In flies with the spontaneous mutation Tre(01), both CG3171 and Gr5a mRNAs are transcribed. Coding sequences of these two candidate genes were compared among various strains. A total of three polymorphic sites leading to amino acid changes in CG3171 were not correlated with the gustatory phenotype. Among four nonsynonymous sites in Gr5a, a single nucleotide polymorphism leading to an Ala218Thr substitution in the predicted second intracellular loop cosegregated with Tre(01). Taken together, the mutation analyses support that Gr5a is allelic to Tre.

Animals↗

PubMed2001

Riluzole stimulates nerve growth factor, brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor synthesis in cultured mouse astrocytes.

Riluzole is an antiexcitotoxic agent used for the treatment of amyotrophic lateral sclerosis, and reported to have neuroprotective effects in animal models of Parkinson's disease, Huntington's disease and brain ischemia. We investigated the effects of riluzole on synthesis of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) in cultured mouse astrocytes. The protein and mRNA levels were measured by enzyme-linked immunosorbent assay and semiquantitative reverse transcription-polymerase chain reaction, respectively. Treatment with riluzole at 100 microg/ml (426 microM) for 24 h increased the contents of NGF, BDNF, and GDNF in the culture medium 109-fold, 2.0-fold and 3.1-fold over the control, respectively. The drug-induced relative mRNA levels of NGF, BDNF, and GDNF were 7.3-fold at 2 h, 2.1-fold at 4 h, and 1.9-fold at 2 h, respectively. These results indicate that riluzole stimulates synthesis of NGF, BDNF and GDNF in cultured astrocytes. Riluzole might exert neuroprotective effects, at least in part, via stimulation of neurotrophic factors.

Animals↗

PubMed2001

A remodeling system of the 3'-sulfo-Lewis a and 3'-sulfo-Lewis x epitopes.

It has been reported that the chemically synthesized 3'-sulfo-Le(a) and 3'-sulfo-Le(x) epitopes have a high potential as a ligand for selectins. To elucidate the physiological functions of 3'-sulfated Lewis epitopes, a remodeling system was developed using a combination of a betaGal-3-O-sulfotransferase GP3ST, hitherto known alpha1,3/1,4-fucosyltransferases (FucT-III, IV, V, VI, VII, and IX) and arylsulfatase A. The pyridylaminated (PA) lacto-N-tetraose (Galbeta1-3GlcNAcbeta1-3Galbeta1-4Glc) was first converted to 3'-sulfolacto-N-fucopentaose II (sulfo-3Galbeta1-3(Fucalpha1-4)GlcNAcbeta1-3Galbeta1-4Glc)-PA by sequential reactions with GP3ST and FucT-III. The 3'-sulfolacto-N-fucopentaose III (sulfo-3Galbeta1-4(Fucalpha1-3)GlcNAcbeta1-3Galbeta1-4Glc)-PA was then synthesized from lacto-N-neotetraose (Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc)-PA by GP3ST and FucT-III, -IV, -V, -VI, -VII, or -IX in a similar manner. The substrate specificity for the 3'-sulfated acceptor of the alpha1,3-fucosyltransferases was considerably different from that for the non-substituted and 3'-sialylated varieties. When the GP3ST gene was introduced into A549 and Chinese hamster ovary cells expressing FucT-III, they began to express 3'-sulfo-Le(a) and 3'-sulfo-Le(x) epitopes, respectively, suggesting that GP3ST is responsible for their biosynthesis in vivo. The expression of the 3'-sialyl-Le(x) epitope on Chinese hamster ovary cells was attenuated by the introduction of GP3ST gene, indicating that GP3ST and alpha2,3-sialyltransferase compete for the common Galbeta1-4GlcNAc-R oligosaccharides. Last, arylsulfatase A, which is a lysosomal hydrolase that catalyzes the desulfation of 3-O-sulfogalactosyl residues in glycolipids, was found to hydrolyze the sulfate ester bond on the 3'-sulfo-Le(x) (type 2 chain) but not that on the 3'-sulfo-Le(a) (type 1 chain). The present remodeling system might be of potential use as a tool for the study of the physiological roles of 3'-sulfated Lewis epitopes, including interaction with selectins.

Animals↗

PubMed2001

A family study of Tourette syndrome in Japan.

Although the mode of inheritance remains in doubt, twin and family studies conducted mostly in the United States and western Europe suggest that genetic factors play an important role in the transmission and expression of Tourette syndrome (TS). In an effort to evaluate population-based genetic differences, we generated risk estimates for first-degree relatives of TS probands in Japan using methods similar to those utilized in recent Western studies. The subjects were 52 TS probands seen at an outpatient clinic of Tokyo University Hospital and their 165 first-degree relatives. All probands and one or more first-degree relatives in each family were interviewed concerning the presence of tic and obsessive-compulsive symptoms by expert clinicians. The age-corrected rates of TS, chronic motor tics, obsessive-compulsive disorder, and subclinical obsessive-compulsive symptoms in the first-degree relatives were 2.0%, 12.0%, 1.6%, and 7.0%, respectively. Rates of TS and related disorders in Japan appear to be much lower than those in recent Western family studies. If replicated, these data suggest that there may be differences in the nature and frequency of vulnerable alleles for TS and related disorders in the Japanese compared to European populations.

Adolescent↗

PubMed2001

Reactivation of feline foamy virus from a chronically infected feline renal cell line by trichostatin A.

Although acute infection of feline foamy virus (FeFV) is normally highly cytopathogenic in Crandell feline kidney (CRFK) cells, a noncytopathic persistent infection was established in the cells after cocultivation of the initially infected cells with uninfected cells four times. To investigate reactivation of persistent infection, CRFK cells chronically infected with FeFV were treated with trichostatin A (TA), a histone deacetylase inhibitor. TA induced higher FeFV production from the Coleman strain carrier culture and also induced marked syncytium formation. In contrast, human foamy virus, which contains less homologous long terminal repeat (LTR) and putative internal promoter (IP) sequences, persistently infecting baby hamster kidney cells was not reactivated by TA. The Sammy-1 strain of FeFV, from which a part of the U3 region in the LTR is naturally deleted, showed less reactivation. The Coleman LTR promoter-based beta-Gal-expressing plasmid was activated in the persistently Coleman-infected cells in the presence of TA, whereas the Sammy-1 LTR was not activated. Furthermore, the amounts of Gag protein expressed did not change in the presence or absence of TA. Because the putative IP region was very similar between the two strains, the initiation by TA is relatively specific for LTR sequences, and, therefore, histone deacetylation is at least in part responsible for reactivation of FeFV from carrier cell culture.

Animals↗

PubMed2001

A pH-sensitive interaction of troponin I with troponin C coupled with strongly binding cross-bridges in cardiac myofilament activation.

Slow skeletal muscle troponin I (ssTnI) expressed predominantly in perinatal heart confers a marked resistance to acidic pH on Ca(2+) regulation of cardiac muscle contraction. To explore the molecular mechanism underlying this phenomenon, we investigated the roles of TnI isoforms (ssTnI and cardiac TnI (cTnI)) in the thin filament activation by strongly binding cross-bridges, by exchanging troponin subunits in cardiac permeabilized muscle fibers. Fetal cardiac muscle showed a marked resistance to acidic pH in activation of the thin filament by strongly binding cross-bridges compared to adult muscle. Exchanging ssTnI into adult fibers altered the pH sensitivity from adult to fetal type, indicating that ssTnI also confers a marked resistance to acidic pH on the cross-bridge-induced thin filament activation. However, the adult fibers containing ssTnI or cTnI but lacking TnC showed no pH sensitivity. These findings provide the first evidence for the coupling between strongly binding cross-bridges and a pH-sensitive interaction of TnI with TnC in cardiac muscle contraction, as a molecular basis of the mechanism conferring the differential pH sensitivity on Ca(2+) regulation.

Actin Cytoskeleton↗

PubMed2001

Selective glycopeptide mapping of erythropoietin by on-line high-performance liquid chromatography--electrospray ionization mass spectrometry.

Selective glycopeptide mapping of recombinant human erythropoietin (rhEPO) used as a model glycoprotein was successfully carried out by on-line high-performance liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) using a Vydac C18 column eluted in acetonitrile-1 mM ammonium acetate, pH 6.8. rhEPO expressed in a Chinese hamster ovary clone was exhaustively digested into four glycopeptides and nine peptides with endoproteinase Glu-C. Both glycopeptides and peptides were eluted with trifluoroacetic acid as the eluent, whereas only glycopeptides were eluted selectively with ammonium acetate in the following order: N38, N24, 0126, and N83. Furthermore, many glycoforms included in each glycopeptide were found to be separated by differences in the numbers of sialic acid and N-acetyllactosaminyl repeats. Twenty, 16 and 22 different N-linked oligosaccharides were determined at Asn24, 38, and 83, respectively, and two different O-linked oligosaccharides were observed at Ser126. Our method is simple, rapid, and useful for determining the carbohydrate structures at each glycosylation site and for elucidating the site-specific carbohydrate heterogeneity.

Chromatography, High Pressure Liquid↗

PubMed2001

Chloroplast ribonucleoproteins function as a stabilizing factor of ribosome-free mRNAs in the stroma.

Post-transcriptional RNA processing is an important step in the regulation of chloroplast gene expression, and a number of chloroplast ribonucleoproteins (cpRNPs) are likely to be involved in this process. The major tobacco cpRNPs are composed of five species: cp28, cp29A, cp29B, cp31, and cp33 and these are divided into three groups (I, II, and III). By immunoprecipitation, gel filtration, and Western blot analysis, we demonstrated that these cpRNPs are abundant stromal proteins that exist as complexes with ribosome-free mRNAs. Many ribosome-free psbA mRNAs coprecipitate with cpRNPs, indicating that the majority of stromal psbA mRNAs are associated with cpRNPs. In addition, an in vitro mRNA degradation assay indicated that exogenous psbA mRNA is more rapidly degraded in cpRNP-depleted extracts than in nondepleted extracts. When the depleted extract was reconstituted with recombinant cpRNPs, the psbA mRNA in the extract was protected from degradation to a similar extent as the psbA mRNA in the nondepleted extract. Moreover, restoration of the stabilizing activity varied following addition of individual group-specific cpRNPs alone or in combination. When the five cpRNPs were supplemented in the depleted extract, full activity was restored. We propose that these cpRNPs act as stabilizing factors for nonribosome-bound mRNAs in the stroma.

Blotting, Western↗

PubMed2001

Hereditary angioedema with a de novo mutation of exon 8 in the C1 inhibitor gene showing recurrent edema of the hands around the peripheral joints: importance for the differential diagnosis of joint swelling.

We describe a patient with hereditary angioedema (HAE), showing recurrent edema around the peripheral joints. Her symptoms began at the age of 18 with hand swelling distal to the wrist joints. Until she was referred to our hospital 3 years after her initial symptoms, she was still undiagnosed, although she was suspected of having rheumatoid arthritis. Laboratory examination showed reduced levels of CH50 and C4 with normal C3 levels. The C1 inhibitor (C1-INH) was decreased to 5 mg/ml, with remarkably reduced activity. Although these findings were compatible with a diagnosis of HAE, there were no episodes of skin edema in her family. To establish the diagnosis, we carried out DNA analysis of the C1-INH gene, which revealed a newly identified de novo mutation of G to A at nucleotide 16869 in exon 8. As described in this patient, localized edema around the peripheral joints may be the only manifestation of HAE. HAE should therefore be taken into consideration for the differential diagnosis of joint swelling.

Adolescent↗

PubMed2001

Functional consequences of the mutations in human cardiac troponin I gene found in familial hypertrophic cardiomyopathy.

Functional consequences of the six mutations (R145G, R145Q, R162W, DeltaK183, G203S, K206Q) in cardiac troponin I (cTnI) that cause familial hypertrophic cardiomyopathy (HCM) were studied using purified recombinant human cTnI. The missense mutations R145G and R145Q in the inhibitory region of cTnI reduced the intrinsic inhibitory activity of cTnI without changing the apparent affinity for actin. On the other hand, the missense mutation R162W in the second troponin C binding region and the deletion mutation DeltaK183 near the second actin-tropomyosin region reduced the apparent affinity of cTnI for actin without changing the intrinsic inhibitory activity. Ca(2+) titration of a fluorescent probe-labeled human cardiac troponin C (cTnC) showed that only R162W mutation impaired the cTnC-cTnI interaction determining the Ca(2+) affinity of the N-terminal regulatory domain of cTnC. Exchanging the human cardiac troponin into isolated cardiac myofibrils or skinned cardiac muscle fibers showed that the mutations R145G, R145Q, R162W, DeltaK183 and K206Q induced a definite increase in the Ca(2+)-sensitivity of myofibrillar ATPase activity and force generation in skinned muscle fibers. Although the mutation G203S also showed a tendency to increase the Ca(2+) sensitivity in both myofibrils and skinned muscle fibers, no statistically significant difference compared with wild-type cTnI could be detected. These results demonstrated that most of the HCM-linked cTnI mutations did affect the regulatory processes involving the cTnI molecule, and that at least five mutations (R145G, R145Q, R162W, DeltaK183, K206Q) increased the Ca(2+) sensitivity of cardiac muscle contraction.

Actins↗

PubMed2001

Single lung transplantation from a brain-dead donor for a patient with idiopathic pulmonary fibrosis. A breakthrough after new legislation in Japan.

Two single lung transplants from a single cadaveric donor were successfully conducted at 2 institutions on March 29, 2000, the first such procedure in Japan under newly introduced legislation. Our patient was a 48-year-old woman with idiopathic pulmonary fibrosis who underwent left single-lung transplantation under cardiopulmonary support. The donor lung was preserved in 4 degrees C modified Euro-Collins solution. Total ischemic time was 5 hours and 37 minutes. The postoperative course was uneventful. The patient was discharged on postoperative day 62 with satisfactory respiratory function.

Brain Death↗

PubMed2001

Thymic carcinoma successfully resected with superior vena cava after chemoradiotherapy.

A 57-year-old woman hospitalized for thymic cancer invading the superior vena cava and left brachiocephalic vein evidenced both pleural and pericardial effusion. After chemotherapy with cisplatin and docetaxel and concurrent radiotherapy, the entire tumor was successfully resected along with the pericardium, superior vena cava, and left brachiocephalic vein, followed by vascular reconstruction. Pathologically, viable tumor cells were identified only in the center of the tumor as anaplastic cell carcinoma. Induction chemoradiotherapy thus appears useful in enabling complete resection of advanced thymic carcinoma.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2001

Clinical development of trastuzumab in breast cancer.

The HER-2/neu protein is thought to be a unique and useful target for antibody therapy of cancers overexpressing the HER-2/neu gene. The recombinant humanized anti-HER-2 monoclonal antibody, trastuzumab (Herceptin) is now available for clinical use in the U.S.A. It is also expected to be available in Japan in the near future. In this paper, the details of this novel biologic agent are reviewed in conjunction with a phase I study performed in Japan.

Animals↗