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Biomedical subjects

S Ohta

Publications and source records attributed to S Ohta.

At least 505 records · Page 28Linked to original sources
PubMed1994

[A case of aseptic meningoencephalitis in a patient with secondary Sjögren syndrome with systemic lupus erythematosus].

A 26-year-old woman, who had been treated with prednisolone 30 mg/day for secondary Sjögren syndrome (SjS) with systemic lupus erythematosus (SLE), was complicated with aseptic meningoencephalitis (AME). Cerebrospinal fluid (CSF) cell counts were 26/3, total protein 126 mg/dl, glucose 41 mg/dl. The CSF, blood, nasopharyngeal swab were cultured for bacteria, mycobacteria, viruses and fungi, but no evidence for an infectious etiology was obtained in this patient. The pair sera study for viruses titer were performed, but no significant titer elevation was observed. Head magnetic resonance imaging showed remarkable atrophy of bilateral occipital lobe and dilatation of posterior horn of bilateral ventricles. The high 2-5AS enzyme activity in the CSF suggested indirectly that the cause of this meningoencephalitis was virus infection. In this case microbiological studies were negative, so central nervous system SLE and/or central nervous system SjS were not completely neglected.

Adult↗
PubMed1994

A family of potato genes that encode Kunitz-type proteinase inhibitors: structural comparisons and differential expression.

Potato tubers contain a complex group of proteins of 20 to 24 kDa that exhibit homology to Kunitz-type proteinase inhibitors. We isolated three cDNAs and two genomic clones that encode members of the potato Kunitz-type proteinase inhibitor (PKPI) family. Comparison of the structures of these and other cloned genes indicated that genes of the PKPI family can be classified into three major homology groups, namely, A, B and C. The PKPI-A and -B genes exhibit higher homology to one another than to the PKPI-C genes. Determination of the N-terminal amino acid sequences of 18 polypeptides from the complex group of 20- to 24-kDa proteins that had been separated by column chromatography and subsequently gel electrophoresis revealed three different sequences that corresponded to PKPI-A, -B, and -C. PKPI-A genes include those coding for a cathepsin D inhibitor, while PKPI-B and -C genes include those coding for trypsin and/or chymotrypsin inhibitors and a subtilisin inhibitor. Precursors to PKPIs are synthesized with an N-terminal extra peptide that appears to contain, in addition to the signal peptide, a short propeptide with a highly conserved Asn-Pro-Ile-Xxx-Leu-Pro motif that is identical to the potential vacuolar-sorting determinant in the N-terminal propeptide of a precursor to sporamin of sweet potato. Expression of the PKPI-A and -B genes is differentially regulated: PKPI-A mRNA but not PKPI-B mRNA were induced in leaves after wounding or upon treatment with methyl jasmonate. Nuclear genes for PKPI-A and -B do not contain introns, and the homology between the two types of gene extends only 72 bp upstream from the site of initiation of transcription.

Amino Acid Sequence↗
PubMed1994

[A case of subacute stroke with high uptake of 99mTc-HMPAO in the reperfused infarct corresponding to low perfusion area].

We reported a case of subacute stroke which showed high uptake of 99mTc-d,l-hexamethylpropyleneamine oxime (HMPAO) in the reperfused infarct corresponding to slightly decreased perfusion by 133Xe inhalation CBF measurement. In the chronic stage, both SPECT images of 99mTc-HMPAO and 133Xe showed low perfusion in the affected lesion. It was, therefore, considered that the high uptake of 99mTc-HMPAO had represented luxury perfusion. In the subacute stage of stroke, high uptake of 99mTc-HMPAO may imply luxury perfusion but not always hyperperfusion. It is suggested that the fractional fixation of 99mTc-HMPAO temporarily change in the affected lesion and it is essential to take into consideration the clinical stage for the interpretation of SPECT images.

Acute Disease↗
PubMed1994

[A study on the distribution of metastases at autopsy in 70 patients with ovarian cancer].

A total of 6,457 autopsy protocols were reviewed to identify 70 women who died of ovarian cancer. 1. Epithelial tumors were the most common tumor (74%). Twenty% were germ cell tumors. There were two cases each of sarcoma and stromal cell tumors. 2. The patients with germ cell tumors were younger than those with epithelial tumors. The duration of the epithelial tumor disease was longer than that of germ cell tumor. 3. The most common mechanism of death was carcinomatosis (69%). Eight of 70 patients (11%) had respiratory failure. One case of subacute cor pulmonale was due to tumor embolization. One case had a rupture of the portal vein. 4. The peritoneum was most frequently involved in every tumor (87%). The liver was the second most frequent site (73%). Other frequent metastatic sites included the lungs (44%), and spleen (47%). Lymph nodes including the paraaortic, pelvic and mesenteric were also very frequent metastatic sites. 5. CDDP containing regimens were used in 33 cases (47%). FAMT regimen was the second most common treatment (15.7%). Another common treatment is whole abdominal radiotherapy (14%). The patients treated with the CDDP containing regimen had a significantly longer survival time (23.4 months) than those treated with FAMT (19.2 months) and others (13.6 months). 6. For metastasis to the lungs, spleen and mesenteric lymph nodes the patients treated with the CDDP containing regimen were more numerous than those treated without CDDP. For metastasis to the kidneys, the patients treated without CDDP were more numerous than those treated with CDDP containing regimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

[A case report of mitral valve replacement for infective endocarditis in pregnancy].

Infective endocarditis in pregnancy is uncommon. A 37-week pregnant woman presented with infective endocarditis. Echocardiography revealed prominent mitral valve vegetations. The patient underwent cesarean section and a 2,800 g male infant was delivered. In order to prevent embolization, mitral valve replacement was performed 3 days after cesarean section with SJM valve. Both mother and child are doing well now.

Adult↗
PubMed1993

Accumulation of mtDNA with a mutation at position 3271 in tRNA(Leu)(UUR) gene introduced from a MELAS patient to HeLa cells lacking mtDNA results in progressive inhibition of mitochondrial respiratory function.

A new mitochondrial DNA (mtDNA) mutation of tRNA(Leu)(UUR) at nucleotide position 3271 (MELAS3271) was determined to be involved in the pathogenic process of mitochondrial diseases MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) using intercellular transfer of patient-derived mtDNA to mtDNA-less HeLa cells (rho 0 HeLa cells). Cybrid clones containing imported mtDNA exclusively from a MELAS patient with MELAS3271 mtDNA were isolated, and the influence of MELAS3271 mtDNA on mitochondrial translation activity and mitochondrial respiratory complex I enzyme activity were examined. Accumulation of more than 87% MELAS3271 mutant mtDNA in the cybrid clones induced both low complex I activity and abnormal mtDNA-encoded polypeptide synthesis including at least complex I subunit ND6. suggesting involvement of the new MELAS-associated mutation in the pathogenesis.

Blotting, Southern↗
PubMed1993

Content of mutant mitochondrial DNA and organ dysfunction in a patient with a MELAS subgroup of mitochondrial encephalomyopathies.

A point mutation of mitochondrial tRNALeu(UUR) gene is responsible for a MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) subgroup of mitochondrial encephalomyopathies. In most cases, the mutant mitochondrial DNA (mtDNA) coexists with normal mtDNA in a heteroplasmic manner. In order to quantify the content of mutant mtDNA, we developed a quantitative method of PCR. Using this method, the distribution of the mutant mtDNA was examined in 32 different tissues among 18 autopsied organs from a patient with MELAS, who had shown hypophyseal dysfunction. The percentage of the mutant mtDNA at nucleotide number 3243 in each tissue was ranged between 22% and 95%. The content of the mutant mtDNA was at the highest (95%) in the hypophysis and higher in the cerebral cortex than in the white matter. This study shows a possible correlation of tissue dysfunction with accumulation of the mutant mtDNA within the brain.

Adult↗
PubMed1993

Human dihydrolipoamide succinyltransferase: cDNA cloning and localization on chromosome 14q24.2-q24.3.

We isolated cDNA for dihydrolipoamide succinyltransferase from a human fibroblast cDNA library in lambda gt11. The cDNA revealed that the human dihydrolipoamide succinyltransferase lacked a sequence motif of an E3 and/or E1 binding site. This suggests that the human dihydrolipoamide succinyltransferase possesses a unique structure consisting of two domains in contrast with the dihydrolipoamide acyltransferases of other alpha-keto acid dehydrogenase complexes. In addition, we found that the human dihydrolipoamide succinyltransferase gene is located on chromosome 14 at q24.2-q24.3 and that a sequence related to the dihydrolipoamide succinyltransferase gene is located on chromosome 1 at p31. Interestingly, the gene for the dihydrolipoamide acyltransferase of the branched chain alpha-keto acid dehydrogenase complex is also located on chromosome 1p31 (Zneimer et al. (1991) Genomics 10, 740-747).

Acyltransferases↗
PubMed1993

Gene structure of human mitochondrial ATP synthase gamma-subunit. Tissue specificity produced by alternative RNA splicing.

We completely sequenced the human gene for ATP synthase gamma-subunit, which was approximately 23 kilobases long and was composed of 10 exons. Exons 1 and 2 encoded the N-terminal presequence required for mitochondrial import, while exons 9 and 10 encoded the C-terminal portions of mature protein. Enzymatic amplification of human heart and liver cDNAs using the polymerase chain reaction revealed two mRNA transcripts that were predicted to encode two 30-kDa isoforms of the gamma-subunit, which differed by the addition of a single amino acid (Asp273) at the C terminus of the liver type isoform. These two mRNA transcripts of the heart (H) type and liver (L) type were generated by alternative splicing of an exon. The same alternative splicing event was observed in bovine tissue. In human tissues, the H type mRNA devoid of exon 9 was expressed specifically in the heart and skeletal muscle, which require rapid energy supply. The L type mRNA was expressed in the brain, liver, kidney etc. Both transcripts were expressed in the skin, intestine, stomach, and aorta. This tissue specificity of transcript heterogeneity suggests the distinct functional or regulatory roles of the gamma-subunit isoforms in the catalysis of ATP synthase. This is the first report on tissue-specific isoforms generated by alternative splicing in an energy transducing mitochondrial protein.

Alternative Splicing↗
PubMed1993

An unspliced cDNA for human dihydrolipoamide succinyltransferase: characterization and mapping of the gene to chromosome 14q24.2-q24.3.

Abnormality of the dihydrolipoamide succinyltransferase gene may be a cause of familial Alzheimer's disease linked to chromosome 14q24.3. However, the locus of the dihydrolipoamide succinyltransferase gene on this chromosome was uncertain. An unspliced cDNA of about 2.3 kb for human dihydrolipoamide succinyltransferase was isolated. This cDNA contained three exons and four introns and the nucleotide sequences at the 5' donor and 3' acceptor sites of all introns conformed to the gt-ag rule. The amino acid sequences of the three exons support our previous observation that human dihydrolipoamide succinyltransferase lacks a sequence motif for an E1 and/or E3 binding site. The unspliced cDNA was mapped only on human chromosome 14q24.2-q24.3 by fluorescent in situ hybridization. Thus the dihydrolipoamide succinyltransferase gene is concluded to be located on human chromosome 14q24.2-q24.3.

Acyltransferases↗
PubMed1993

Cis-diamminedichloroplatinum(II) inhibits p34cdc2 protein kinase in human lung-cancer cells.

cis-Diamminedichloroplatinum(II) (CDDP) induced G2-phase arrest in PC-9 human cancer cells. To elucidate how CDDP acts on cell-cycle regulation, we analyzed the effect of CDDP on cell-cycle regulators such as p34cdc2 protein kinase. p34cdc2 protein kinase activity was maximum in G2 phase and decreased after G2/M transition in synchronized PC-9 human lung cancer cells. Evidence for a phosphorylated p34cdc2 protein kinase complexed with cyclin B was obtained from cells in G2 phase and the p34cdc2 protein kinase appeared to be dephosphorylated at M phase. After exposure to CDDP in G1 phase, PC-9 cells were arrested in G2 phase. The activation of p34cdc2 protein kinase was inhibited by CDDP. Cyclin A and wee-I kinase were not affected by the exposure to CDDP. Cyclin B was degraded in M phase in PC-9 cells. Exposure to CDDP did not affect the degradation of cyclin B. Our data suggest that the effect of CDDP on cell-cycle phase might be regulated by the dephosphorylation of p34cdc2 protein kinase. To determine whether the p34cdc2 protein kinase is a primary target for CDDP, we examined the direct effect of CDDP on tyrosine dephosphorylation of p34cdc2 protein kinase in cellular extracts. Cell lysates from synchronized PC-9 in G2 phase were immunoprecipitated with p13-Sepharose beads. In vitro dephosphorylation of phosphotyrosine of p34cdc2 protein kinase was observed after exposure to okadaic acid in a concentration-dependent manner. The dephosphorylation of p34cdc2 protein kinase by okadaic acid was inhibited by CDDP. We hypothesize that inhibition of p34cdc2 dephorphorylation by CDDP is important for its growth-inhibiting properties.

CDC2 Protein Kinase↗
PubMed1993

Methamphetamine antagonistic property of (+)- and (-)-4-phenyltetrahydroisoquinoline in rat anococcygeus muscle.

The antagonistic effects of (+)- and (-)-4-phenyl-1,2,3,4-tetrahydroisoquinoline (4PTIQ) on methamphetamine in the rat anococcygeus muscle were compared with those of cocaine and nomifensine. Methamphetamine contracted the anococcygeus muscle through the release of norepinephrine from noradrenergic nerve terminals. (+)-4PTIQ inhibited the methamphetamine-induced contractions more strongly than cocaine and nomifensine. (+)-4PTIQ had no potentiating effects on exogenous norepinephrine-induced contraction, which was considered to be an index of amine neuronal uptake blockade. On the other hand, (-)-4PTIQ, cocaine and nomifensine produced a significant leftward shift of the norepinephrine concentration-response curve, i.e. they showed a strong blocking effect on amine neuronal uptake. These results suggest that the inhibitory effects of (+)-4PTIQ on the action of methamphetamine are mediated by a mechanism other than inhibition of amine neuronal uptake.

Animals↗
PubMed1993

Expression of sialyl Lewis(x) antigen on human T cells.

Sialyl Lewis(x) (sLe(x)) antigen, which has been introduced as tumor-associated cell surface carbohydrates, was demonstrated to be expressed on a subpopulation of human CD4+ and CD8+ T cells. It was also demonstrated that the majority of gamma delta T cells as well as natural killer cells expressed a high level of sLe(x) antigen. The sLe(x) expression on T cells were up-regulated by activation with various T cell stimulants. The sLe(x)+ CD4+ T cells were enriched in CD4+CD45RO+ memory type of T cells but not in CD4+CD45RA+ T cells. Moreover, sLe(x)+ CD4+ T cells were demonstrated to show higher proliferative responses to T cell stimulants such as CD4+CD45RO+ T cells. These results initially clarified the expression of sLe(x) carbohydrate on human T cells and indicated the important role of sLe(x)-expressing T cells in immune responses.

Antibodies, Monoclonal↗
PubMed1993

Ovariectomy decreases the mRNA levels of transforming growth factor-beta 1 and increases the mRNA levels of osteocalcin in rat bone in vivo.

Estrogen depletion causes postmenopausal osteoporosis. Here we report that steady state mRNA levels of transforming growth factor-beta 1 (TGF-beta 1) and osteocalcin in bone persistently decreased and increased, respectively, in vivo in estrogen-depleted rats after ovariectomy (OVX). 21 female Wistar rats (7-month-old) were randomized and underwent OVX or sham-operation, total RNA was extracted from tibiae and assessed by Northern blot analysis. OVX induced 70-80% decrease in TGF-beta 1 mRNA levels and 2- to 3-fold increase in mRNA levels of osteocalcin compared with controls three weeks after surgery. These changes persisted up to twelve weeks post-operation. OVX caused 15% reduction in femoral bone mineral density and 2-fold elevation in serum osteocalcin levels as early as two weeks post-operation. Moreover, estrogen depletion resulted in marked decrease and increase, respectively, in steady state mRNA levels of TGF-beta 1 and osteocalcin in vitro in osteoblastic rat osteosarcoma cells, ROS 17/2.8. Our results provide the first in vivo evidence that expression of TGF-beta and osteocalcin in bone is reciprocally regulated at the transcriptional level in estrogen deficient OVX rats and suggests that TGF-beta 1 may play a role in estrogen-dependent maintenance of normal bone density.

Amino Acid Isomerases↗
PubMed1993

4-Phenyltetrahydroisoquinoline, but not nomifensine or cocaine, inhibits methamphetamine-induced dopamine release.

The inhibitory effect of 4-phenyltetrahydroisoquinoline (4-PTIQ) on methamphetamine-induced dopamine release in the rat nucleus accumbens was investigated using a brain microdialysis method. Methamphetamine (10(-6) M) infusion through a microdialysis probe induced the release of dopamine. Although the uptake inhibitors, cocaine (3 x 10(-6) M) and nomifensine (10(-6) M), failed to block dopamine release, 4-PTIQ (10(-6 M) inhibited the dopamine-releasing effect of methamphetamine. 4-PTIQ did not affect the elevation of the extracellular dopamine level induced by high concentrations of nomifensine (10(-5) M) and cocaine (3 x 10(-5) M). 4-PTIQ was the weakest inhibitor of [3H]dopamine uptake by rat striatal synaptosomes. These results suggest that 4-PTIQ is a selective antagonist against the dopamine-releasing effect of methamphetamine in the nucleus accumbens.

Animals↗
PubMed1993

Smaller isoform of human mitochondrial transcription factor 1: its wide distribution and production by alternative splicing.

Mitochondrial transcriptional factor 1 (mtTF1) is required for both transcription and replication of mammalian mitochondrial DNA (mtDNA) and it has two consensus sequences of HMG (high mobility group) boxes. In studies on the regulation of gene expression of mtTF1, we examined the steady state level of the mRNA in cultured HeLa cells. We found that in addition to the major mRNA, 30% of the mRNA of mtTF1 in the cells was a smaller isoform with a 96 base deletion. This smaller mRNA was also found in most human tissues. The region of the deletion corresponds to the second HMG-box, which may interact directly with DNA. We examined the structure of the genomic gene encoding the human mtTF1 to determine the mechanism of the deletion. We found that the gene is composed of 7 exons spanning over 10 kilobase-pairs and that its 5th exon is identical to the 96 bases skipped in the shorter mRNA. Therefore, the shorter mtTF1 is concluded to be generated by alternative splicing.

Alternative Splicing↗