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Biomedical subjects

Y Ohshima

Publications and source records attributed to Y Ohshima.

At least 37 records · Page 2Linked to original sources

[Right ventricular outflow tract reconstruction using monocusp valved outflow patch for pulmonary atresia with ventricular septal defect: influence of the presence of major aorto-pulmonary collateral arteries].

We have preferably utilized monocusp valved outflow patch (MVOP) for right ventricular outflow tract (RVOT) reconstruction in pulmonary atresia with ventricular septal defect (PA + VSD). The purpose of this study was to evaluate the influence of the presence of major aorto-pulmonary collateral arteries (MAPCAs) on probability of MVOP reconstruction and development of RVOT restenosis in midterm. 49 patients underwent complete repair (either MVOP reconstruction or Rastelli procedure) of PA + VSD in our service. These patients were divided into 2 groups: group 1; 21 patients with MAPCAs, group 2; 28 patients without MAPCAs. There was one operative death (group 1). The probably of MVOP reconstruction was similar between group 1 and group 2 (71 vs 79%, p = 0.57, chi 2 test). Follow-up was completed for 48 survivors with the period ranged 3-108 months (mean 47 months). In group 1, one patient died suddenly at home 10 months after surgery. For 47 long-term patients, the ratio of freedom from RVOT restenosis was 72% (95% CI: 52-92%, Kaplan-Meier method) at 5 year. There was no difference between 2 groups (group 1; 73%, 95% CI: 45-100%, group 2; 74%, 95% CI: 48-99%, respectively, p = 0.85 by Log-Rank test). The presence of MAPCAs in PA + VSD was not a risk factor for either the probably of MVOP reconstruction or development of RVOT restenosis in midterm.

Adolescent↗

A Caenorhabditis elegans MAP kinase kinase, MEK-1, is involved in stress responses.

The c-Jun N-terminal kinase (JNK), a member of the mitogen-activated protein kinase (MAPK) family, was shown to be involved in the response to various stresses in cultured cells. However, there is little in vivo evidence indicating a role for a JNK pathway in the stress response of an organism. We identified the Caenorhabditis elegans mek-1 gene, which encodes a 347 amino acid protein highly homologous to mammalian MKK7, an activator of JNK. Mek-1 reporter fusion proteins are expressed in pharyngeal muscle, uterus, a portion of intestine, and neurons. A mek-1 deletion mutant is hypersensitive to copper and cadmium ions and to starvation. A wild-type mek-1 transgene rescued the hypersensitivity to the metal ions. Double mutants of mek-1 with an eat-5, eat-11 or eat-18 mutation, which are characterized by a limited feeding defect, showed distinct growth defects under normal conditions. Expression of an activated form of MEK-1 in the whole animal or specifically in the pharynx inhibited pharyngeal pumping. These results suggest a role for mek-1 in stress responses, with a focus in the pharynx and/or intestine.

Amino Acid Sequence↗

Sensitive high-performance liquid chromatographic method for the determination of the lactone form and the lactone plus hydroxy-acid forms of the new camptothecin derivative DX-8951 in human plasma using fluorescence detection.

A sensitive quantitation of the lactone form and the lactone plus hydroxy-acid forms of DX-8951, a camptothecin derivative, in human plasma has been investigated by high-performance liquid chromatography (HPLC). This assay method consisted of two analytical procedures. In Procedure I, the lactone form was collected by the stepwise separation on a C18 cartridge. In Procedure II, the lactone plus hydroxy-acid forms were collected using another batch of the plasma sample by co-elution of the two forms from a C18 cartridge with acidic solution. The hydroxy-acid form of DX-8951 was quantitated from the difference of the lactone plus hydroxy-acid forms and the lactone form. Thereafter, these pre-treated samples were assayed by HPLC under the same HPLC conditions with a spectrofluorometer and a reverse-phase ODS column. The mobile phase was acetonitrile/0.05 M potassium dihydrogen phosphate (pH 3) (18:82, v/v) at a flow-rate of 1.0 ml/min. For the assay of the lactone form and the lactone plus hydroxy-acid forms of DX-8951 in plasma, analytical method were validated over the range 0.2-50 ng/ml.

Antineoplastic Agents, Phytogenic↗

Mutations in the large subunit of U2AF disrupt pre-mRNA splicing, cell cycle progression and nuclear structure.

The prp2 gene of fission yeast has previously been shown to encode the large subunit of the splicing factor spU2AF. SpU2AF(59) is an evolutionarily conserved protein that has an arginine/serine-rich region and three RNA recognition motifs (RRMs). We have sequenced three temperature-sensitive alleles of prp2 and determined that the mutations result in single amino acid changes within one of the RRMs or between RRMs. All mutant alleles of prp2 have pre-mRNA splicing defects at the non-permissive temperature. Although the mutant strains are growth-arrested at 37 degrees C, they do not elongate like typical fission yeast cell cycle mutants. The DNA of the prp2(-) strains stains more intensely than a wild-type strain, suggesting that the chromatin may be condensed. Ultrastructural studies show differences in the mutant nuclei including a prominent distinction between the chromatin- and non-chromatin-enriched regions compared to the more homogenous wild-type nucleus. Two-hybrid assays indicate that some of the wild-type protein interactions are altered in the mutant strains. These results suggest that normal functioning of spU2AF(59) may be essential not only for pre-mRNA splicing but also for the maintenance of proper nuclear structure and normal cell cycle progression.

Alleles↗

Efficacy of long-term azathioprine for relapsing nephrotic syndrome.

Seven patients who had an initial attack of nephrotic syndrome in childhood and had frequent relapses even after cyclophosphamide therapy were given a 2-year course of azathioprine. The mean annual relapse rates decreased from 2.4+/-0.5 in the year preceding azathioprine to 0.4+/-0.8 in the 1st and 2nd years after its initiation. All six patients who were observed for more than 6 months after discontinuation of the therapy were relapse free for this period. Average doses of prednisolone could also be decreased in the 2nd and subsequent years after the therapy. There were no significant toxic effects. Long-term azathioprine therapy may be well tolerated and effective for nephrotic patients with frequent relapses.

Adolescent↗

Modulation of calcium-induced clot formation of human plasma by Malassezia furfur.

The effect of Malassezia furfur on clot formation by human plasma was examined. The clotting time in the presence of M. furfur or Candida albicans was measured. M. furfur shortened the clotting time of calcium-induced clots by human plasma in a concentration-dependent manner. However, the protein content of the clots formed were not significantly different between the M. furfur-treated and the control group. The clotting time of clots triggered by thrombin or by placing plasma in glass tubes, which artificially activate the blood coagulation systems, were not affected by treatment with M. furfur. Moreover, acetone-treated M. furfur also shortens the calcium-induced clot formation time, while treatment with zymolyase, which causes decomposition of beta-glucan, did not shorten it. These results suggest that M. furfur activates the blood coagulation systems, and the beta-glucan portion of M. furfur plays a key role in shortening calcium-induced clot formation time.

Acetone↗

Older boys benefit from higher initial prednisolone therapy for nephrotic syndrome. The West Japan Cooperative Study of Kidney Disease in Children.

BACKGROUND: A long course of the initial prednisolone therapy has been shown to be more effective than standard-course therapy in reducing relapse rates in children with idiopathic nephrotic syndrome, but it is commonly accompanied by corticosteroid toxicities. There has been no study on prednisolone dosage for the effective treatment of nephrotic syndrome. METHODS: Sixty-eight children (42 boys and 26 girls) with an initial attack of nephrotic syndrome were randomly allocated into two different long-course treatment groups. Patients in Group 1 received a daily prednisolone dose of 60 mg/m2 for six weeks, followed by an alternate-day dose of 40 mg/m2 for six weeks. Patients in Group 2 had a daily dose of 40 mg/m2 instead of 60 mg/m2. RESULTS: Four children in each group did not respond within six weeks. Group 1 was associated with a significantly earlier response but more frequent corticosteroid toxicities than Group 2. Boys in Group 1 had a higher rate of sustained remission than boys in Group 2 (P = 0.0073), especially boys four years old or more (P = 0.0027), but girls did not show a significant difference (P = 0.863). Boys four years old or more in Group 1 had a course of frequent relapsing less often than those in Group 2 (2 of 13 vs. 6 of 8, P = 0.0075). CONCLUSION: These findings indicate that efficient prednisolone doses may vary between sexes and ages, and that a higher initial prednisolone therapy may be of greater benefit to older boys.

Adolescent↗

Enhancement of IL-8 production from human monocytic and granulocytic cell lines, THP-1 and HL-60, stimulated with Malassezia furfur.

Previously, we reported that Malassezia furfur, causing systemic fungal infection, was taken up into human monocytic cell line, THP-1, in a concentration-dependent manner. This fact suggested that M. furfur could activate phagocytes, such as monocyte and polymorphonuclear leukocyte. Thus we examined cytokine mRNA expression from human monocytic and granulocytic cell line, THP-1 and HL-60, stimulated with M. furfur by using reverse transcriptase-polymerase chain reaction (RT-PCR) and ELISA. We chose IL-1alpha, IL-6, IL-8, IL-12 and TNF-alpha as primers for THP-1, and IL-1alpha, IL-6 and IL-8 for HL-60. M. furfur induced the expression of IL-8 mRNA from THP-1 and HL-60 following incubation for 3 h, and also induced IL-1alpha mRNA from HL-60, although this induction was weaker than that of IL-8 mRNA. Furthermore, opsonized M. furfur induced stronger expression of IL-8 mRNA in comparison with intact M. furfur. IL-8 production from THP-1 and HL-60 was enhanced in a concentration- and incubation time-dependent manner. These facts strongly suggested that M. furfur could activate phagocytes, and could induce inflammatory responses in systemic infection.

Cell Line↗

Increased oxidative stress in rats with chronic nitric oxide depletion: measurement of urinary 8-hydroxy-2'-deoxyguanosine excretion.

Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) has been reported to serve as a sensitive biomarker of oxidative stress. We examined the effect of chronic blockade of nitric oxide (NO) on urinary excretion of 8-OHdG in rats. Two types of NO synthase inhibitor were used: N(G)-nitro-L-arginine methyl ester (L-NAME) as a non-selective inhibitor and aminoguanidine (AG) as a selective inhibitor of the inducible isoform. Oral administration of L-NAME (20, 50 and 80 mg/dl of drinking water), but not AG (400 mg/dl), for 4 weeks induced systemic hypertension and a significant reduction in urinary excretion of NO2-/NO3-. Rats treated with L-NAME also showed a significant increase in urinary 8-OHdG excretion compared with the control animals. The effects of L-NAME (50 mg/dl) on blood pressure and urinary excretion of NO2/NO3- and 8-OHdG were restored by a large dose of L-arginine (2.0 g/dl). Chronic AG administration did not significantly alter urinary 8-OHdG excretion. On combining all the data, there was a significant negative correlation between urinary NO2-/NO,- and 8-OHdG. These observations suggest the importance of constitutive NO synthase activity in the maintenance of oxidant buffering capacity in rats. Oral administration of L-NAME may serve as a model of hypertension due to chronic NO deficiency with increased oxidative stress.

8-Hydroxy-2'-Deoxyguanosine↗

No increased risk of thrombosis in heterozygous congenital dysplasminogenemia.

To assess the risk of thrombosis in congenital dysplasminogenemia, we studied 10 unrelated families with this disorder. The probands were excluded from the analysis of data to prevent bias in the selection of subjects. Positive thrombotic histories were found in 1 of the 25 family members determined to have heterozygous congenital dysplasminogenemia and in 2 of their 41 biochemically unaffected relatives. The percentages of family members with no history of thrombosis up to a given age among subjects with and without congenital dysplasminogenemia were analyzed by the Kaplan-Meier method. No significant difference between the 2 groups was observed by generalized Wilcoxon test (P = .32) or Cox-Mantel test (P = .62). These findings suggest that heterozygous congenital dysplasminogenemia is not associated with an increased risk of thrombosis.

Adolescent↗

Disruption of clh-1, a chloride channel gene, results in a wider body of Caenorhabditis elegans.

We cloned the clh-1 gene coding for a putative ClC chloride channel in Caenorhabditis elegans. The gene product exhibited a high degree of homology with human ClC-1 and ClC-2. The clh-1 gene was predominantly expressed in the hypodermis, including seam cells. Null mutations of clh-1 caused a significantly wider body and an abnormal alae structure. High osmolarity in the culture medium restored the normal body width of the clh-1 mutants. These results suggest that the clh-1 gene contributes to maintenance of the body width through regulation of osmolarity.

Amino Acid Sequence↗

Mouse ULK2, a novel member of the UNC-51-like protein kinases: unique features of functional domains.

The UNC-51 serine/threonine kinase of C. elegans plays an essential role in axonal elongation, and unc-51 mutants exhibit uncoordinated movements. We have previously identified mouse and human cDNAs encoding UNC-51-like kinase (ULK1). Here we report the identification and characterization of the second murine member of this kinase family, ULK2. Mouse ULK2 cDNA encodes a putative polypeptide of 1033 aa which has an overall 52% and 33% amino acid identity to ULK1 and UNC-51, respectively. ULKs and UNC-51 share a typical domain structure of an amino-terminal kinase domain, a central proline/serine rich (PS) domain, and a carboxy-terminal (C) domain. Northern blot analysis showed that ULK2 mRNA is widely expressed in adult tissues. In situ hybridization analysis indicated that ULK2 mRNA is ubiquitously localized in premature as well as mature neurons in developing nervous system. ULK2 gene was mapped to mouse chromosome 11B1.3 and rat chromosome 10q23 by FISH. HA-tagged ULK2 expressed in COS7 cells had an apparent molecular size of approximately 150 kDa and was autophosphorylated in vitro. Truncation mutants suggested that the autophosphorylation occurs in the PS domain. Although expression of ULK2 failed to rescue unc-51 mutant of C. elegans, a series of ULK2/UNC-51 chimeric kinases revealed that function of the kinase and PS domains are conserved among species, while the C domain acts in a species-specific manner. These results suggest that ULK2 is involved in a previously uncharacterized signaling pathway in mammalian cells.

Amino Acid Sequence↗

Site-directed mutagenesis of the response regulator DmsR for the dmsCBA operon expression in Rhodobacter sphaeroides f. sp. Denitrificans: An essential residue of proline-130 in the linker.

DmsR protein is a member of the OmpR response regulator subfamily that activates the transcription of the dmsCBA operon in Rhodobacter sphaeroides f. sp. denitrificans. By site-directed mutagenesis some functional amino acid residues were investigated in DmsR, which consists of the N-terminal regulatory and the C-terminal DNA-binding domains and the linker connecting the two domains. The substitution of P130S in the linker caused decreases of both DNA-binding and transcriptional activator activities. Introducing additional substitutions of R129P or D131P to the DmsR-P130S derivative recovered both activities, demonstrating necessity of proline residue at one of the positions 129-131 in the linker. Substitutions of D12A, D55A, and K104M, at residues conserved in the phosphorylation region, caused no production of DMSO reductase, but retained DNA-binding ability, suggesting that unphosphorylated DmsR also has high affinity to its target nucleotide sequence of DNA. Substitutions in the C-terminal domain suggested the presence of a winged helix-turn-helix structure observed in the DNA-binding domain of the Escherichia coli OmpR.

Bacterial Proteins↗

Naive human CD4+ T cells are a major source of lymphotoxin alpha.

It is generally accepted that immunologically naive T cells display a very restricted cytokine production profile consisting mainly of IL-2, which is used as an autocrine growth factor. Here we report that activated naive CD4+ T cells, of neonatal or adult origin, express very high levels of soluble lymphotoxin (LT) alpha (LTalpha3), as determined by ELISA, RNase protection assay, and intracytoplasmic staining. Besides LTalpha3 and IL-2, these cells also produce high levels of TNF-alpha together with significant amounts of IFN-gamma and IL-13. Naive cells also express LTbeta mRNA and the membrane form of LTalpha (LTalphabeta). On average, naive CD4+ T cells secrete four times more LTalpha3 than Th1-like cells, twice more than naive CD8+ T cells, and ten times more than B cells. Thus, naive T cells express a large spectrum of cytokines, mainly of the Th1 type, and the very high levels of LTalpha3/TNF-alpha that they release may play an hitherto unsuspected role in the early stage of T cell-dependent immune responses.

Adult↗

Functional reconstitution of a heteromeric cyclic nucleotide-gated channel of Caenorhabditis elegans in cultured cells.

The tax-4 and tax-2 genes of Caenorhabditis elegans are essential for normal olfaction, gustation, and thermosensation, suggesting that they have a role in sensory transduction. The predicted products of these genes are similar to the cyclic nucleotide-gated (CNG) channel subunits used in vertebrate vision and olfaction: TAX-4 is highly related to those alpha subunits, while TAX-2 is most closely related to the beta subunits of the rod phototransduction channels. TAX-4 has previously been shown to form a highly sensitive cGMP-gated channel when expressed in human HEK293 cells. Here we show that TAX-4 and TAX-2 form a heteromeric channel when expressed in HEK293 cells, but TAX-2 does not form a channel on its own. Since these genes are expressed in the same neurons, most of the native channels in C. elegans are likely to be hetero-oligomers of TAX-4 and TAX-2 subunits, with TAX-4 as the alpha subunit and TAX-2 acting as a modifying beta subunit. The heteromeric TAX-4/TAX-2 channel is 25-fold less sensitive to cGMP than the TAX-4 channel, but it remains highly selective for cGMP over cAMP. The heteromeric channel and the TAX-4 homomeric channel differ in their blockage by divalent cations and in their single channel properties. These results suggest that cGMP is used as the second messenger during sensory signal transduction in C. elegans, and that distinct roles for alpha and beta subunits of CNG channels are conserved in vertebrate and invertebrate signal transduction.

Animals↗