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Biomedical subjects

Y Ohshima

Publications and source records attributed to Y Ohshima.

At least 55 records · Page 3Linked to original sources
PubMed1999

Cyclin D2, but not cyclin D1, overexpression closely correlates with gastric cancer progression and prognosis.

Expression of cyclins D1 and D2, as well as cyclin-dependent kinase 4 (cdk4), was investigated by means of immunohistochemistry in 455 gastric cancer cases. Additional western blotting was performed for four breast cancer and four gastric cancer cell lines and 35 fresh frozen gastric cancer samples, to confirm the cyclin D1, D2, and cdk4 data. Cyclin D1 was restricted to the nucleus of cancer cells with a few exceptions, whereas cyclin D2 was present in both cell compartments, but predominantly in the cytoplasm. Cdk4 was intermediately expressed. Cyclin D1 was overexpressed in 93 cases (20.4 per cent) and cyclin D2 in 105 (23.0 per cent). In the cyclin D2 cases, this correlated with greater age (p=0.0004), better differentiation (p=0.0023), greater depth of cancer invasion (p=0. 003), the presence of lymph node metastasis (p=0.0014), vascular invasion by cancer cells (p< 0.0001), and poor prognosis (p< 0.0001), while cyclin D1 did not correlate with any of these except age (p=0.00193). Multivariate analysis revealed cyclin D2 overexpression to be an independent prognostic factor, in addition to depth of cancer invasion and lymph node status. Cdk4 overexpression was linked to cyclin D1, but not cyclin D2 overexpression. The results indicate that cyclin D2 up-regulation plays an important role in the progression and prognosis of gastric cancer independently of cdk4, whereas cyclin D1 overexpression does not.

Adult↗
PubMed1999

Characterization of the ptr6(+) gene in fission yeast: a possible involvement of a transcriptional coactivator TAF in nucleocytoplasmic transport of mRNA.

Transport of mRNA from the nucleus to the cytoplasm is one of the important steps in gene expression in eukaryotic cells. To elucidate a mechanism of mRNA export, we identified a novel ptr [poly(A)+ RNA transport] mutation, ptr6, which causes accumulation of mRNA in the nucleus and inhibition of growth at the nonpermissive temperature. The ptr6(+) gene was found to encode an essential protein of 393 amino acids, which shares significant homology in amino acid sequence with yTAFII67 of budding yeast Saccharomyces cerevisiae and human hTAFII55, a subunit of the general transcription factor complex TFIID. A Ptr6p-GFP fusion protein is localized in the nucleus, suggesting that Ptr6p functions there. Northern blot analysis using probes for 10 distinct mRNAs showed that the amount of tbp+ mRNA encoding the TATA-binding protein is increased five- to sixfold, whereas amounts of others are rapidly decreased at the nonpermissive temperature in ptr6-1. ptr6 has no defects in nuclear import of an NLS-GFP fusion protein. These results suggest that Ptr6p required for mRNA transport is a Schizosaccharomyces pombe homologue of yTAFII67 and hTAFII55. This is the first report suggesting that a TAF is involved in the nucleocytoplasmic transport of mRNA in addition to the transcription of the protein-coding genes.

Cell Nucleus↗
PubMed1999

Control of DAF-7 TGF-(alpha) expression and neuronal process development by a receptor tyrosine kinase KIN-8 in Caenorhabditis elegans.

KIN-8 in C. elegans is highly homologous to human ROR-1 and 2 receptor tyrosine kinases of unknown functions. These kinases belong to a new subfamily related to the Trk subfamily. A kin-8 promoter::gfp fusion gene was expressed in ASI and many other neurons as well as in pharyngeal and head muscles. A kin-8 deletion mutant was isolated and showed constitutive dauer larva formation (Daf-c) phenotype: about half of the F(1) progeny became dauer larvae when they were cultivated on an old lawn of E. coli as food. Among the cells expressing kin-8::gfp, only ASI sensory neurons are known to express DAF-7 TGF-(beta), a key molecule preventing dauer larva formation. In the kin-8 deletion mutant, expression of daf-7::gfp in ASI was greatly reduced, dye-filling in ASI was specifically lost and ASI sensory processes did not completely extend into the amphid pore. The Daf-c phenotype was suppressed by daf-7 cDNA expression or a daf-3 null mutation. ASI-directed expression of kin-8 cDNA under the daf-7 promoter or expression by a heat shock promoter rescued the dye-filling defect, but not the Daf-c phenotype, of the kin-8 mutant. These results show that the kin-8 mutation causes the Daf-c phenotype through reduction of the daf-7 gene expression and that KIN-8 function is cell-autonomous for the dye-filling in ASI. KIN-8 is required for the process development of ASI, and also involved in promotion of daf-7 expression through a physiological or developmental function.

Amino Acid Sequence↗
PubMed1999

[Concomitant mitral valvuloplasty and fenestrated total cavopulmonary connection: a case report].

A seven-year-old boy with tricuspid atresia successfully underwent a fenestrated total cavopulmonary connection and mitral valvuloplasty. Preoperative cardiac catheterization showed a mean pulmonary artery pressure of 16 mmHg. Pulmonary arteriography showed poor development of the branches (PA index: 180). Echocardiography revealed mild to moderate mitral valve incompetence due to prolapse of anterior leaflet. Mitral valve was exposed through the trans-septal approach. The excess chorda length was tucked into a longitudinal split in the top of the posterior papillary muscle. Then wedge resection of the redundant segment of the anterior leaflet and bilateral annuloplasty were performed. Finally, a total extracardiac cavopulmonary anastomosis with a 6 mm fenestration was completed. Postoperative clinical course was uneventful, and he is doing well with no recurrence of mitral incompetence 1 year after the operation.

Child↗
PubMed1999

[Midterm results of bilateral enlargement of the aortic valve ring for valve replacement].

From 1989, 4 patients underwent bilateral enlargement of the aortic valve ring for valve replacement. Age at the operation ranged from 2 to 8 (mean 6) years; body weight ranged from 14.9 to 25.4 (mean 19.0) kg. This procedure enabled us to implant a prosthesis 3 to 4 sizes larger (19 to 23 mm) than that measured with the native aortic annulus (13 to 17 mm). There was no late death and no cardiac event over a mean follow-up period of 6.2 years. Pressure gradient across the prosthesis measured by echocardiography was 40 mmHg in 1 patient who underwent aortic valve replacement with the use of 19 mm St. Jude Medical valve at 2 years of age. There was no significant pressure gradient in other 3 patients. All patients showed normal left ventricular function. We conclude that bilateral enlargement of the aortic valve ring for valve replacement has provided good midterm results with no mortality and no cardiac event.

Aortic Valve↗
PubMed1998

The fission yeast prp10(+) gene involved in pre-mRNA splicing encodes a homologue of highly conserved splicing factor, SAP155.

In the fission yeast Schizosaccharomyces pombe, 14 prp (pre-mRNAprocessing) mutants have been isolated to date. We cloned the prp10(+) gene by complementation of the temperature-sensitive growth of prp10. Five types of transcripts were found that were alternatively spliced with respect to two possible introns located in the 5'-terminal region. Three of them are probably functional and code for putative proteins of approximately 1200 amino acids. Proteins highly homologous to Prp10p are present in other organisms, one of which is a human spliceosome-associated protein SAP155, a subunit of the splicing factor complex SF3. The C-terminal two-thirds of Prp10p is highly conserved among species, and contains consensus repeats for the regulatory subunit A of protein phosphatase PP2A. A gene disruption experiment indicated that the prp10(+) gene is essential for viability in S.pombe. Prp10p tagged with GFP is predominantly localized in the nuclear DNA region. A series of deletions showed that the less conserved N-terminal region of approximately 300 amino acids in Prp10p is dispensable, although the corresponding region was thought to play important roles in the mammalian splicing system.

Cloning, Molecular↗
PubMed1998

OX40 costimulation enhances interleukin-4 (IL-4) expression at priming and promotes the differentiation of naive human CD4(+) T cells into high IL-4-producing effectors.

Th2 cell development is critically dependent on the presence of interleukin-4 (IL-4) at priming. The cellular origin and the mechanisms regulating this early production of IL-4 at the site of naive T-cell priming are extensively investigated. We previously reported that anti-CD3-activated and CD28-costimulated naive human CD4(+) T cells themselves release very low but sufficient levels of IL-4 to support their development into high IL-4-producing cells. We show here that ligation of OX40 Ag, a member of the tumor necrosis factor receptor (TNF-R) family, on activated umbilical cord blood CD4(+) T cells upregulates IL-4 production at priming and thereby promotes their development into effector cells producing high levels of the type 2 cytokines IL-4, IL-5, and IL-13. OX40 ligation increases four times the expression of IL-4 mRNA after 48 hours of anti-CD3/B7.1 activation and significantly augments the release of IL-4 and IL-13 in primary cultures. The effects of OX40 costimulation on Th cell differentiation are observed in the presence of optimal and suboptimal CD28 stimulation. Because OX40 ligand is expressed on dendritic cells, the OX40 costimulation pathway may be involved in the physiological regulation of Th cell development by augmenting the differentiation of IL-4-producing cells.

CD28 Antigens↗
PubMed1998

Cloning and characterization of a human DEAH-box RNA helicase, a functional homolog of fission yeast Cdc28/Prp8.

During the splicing process, spliceosomal snRNAs undergo numerous conformational rearrangements that appear to be catalyzed by proteins belonging to the DEAD/H-box superfamily of RNA helicases. We have cloned a new RNA helicase gene, designated DBP2 (DEAH-boxprotein), homologous to the Schizosaccaromyces pombe cdc28(+)/prp8(+) gene involved in pre-mRNA splicing and cell cycle progression. The full-length DBP2 contains 3400 nucleotides and codes for a protein of 1041 amino acids with a calculated mol. wt of 119 037 Da. Transfection experiments demonstrated that the GFP-DBP2 gene product, transiently expressed in HeLa cells, was localized in the nucleus. The DBP2 gene was mapped by FISH to the MHC region on human chromosome 6p21.3, a region where many malignant, genetic and autoimmune disease genes are linked. Because the expression of DBP2 gene in S.pombe prp8 mutant cells partially rescued the temperature-sensitive phenotype, we conclude that DBP2 is a functional human homolog of the fission yeast Cdc28/Prp8 protein.

Amino Acid Sequence↗
PubMed1998

Productive infection of neonatal CD8+ T lymphocytes by HIV-1.

CD8+ T lymphocytes confer significant but ultimately insufficient protection against HIV infection. Here we report that activated neonatal CD8+ T cells can be productively infected in vitro by macrophage-tropic (M-tropic) HIV-1 isolates, which are responsible for disease transmission, whereas they are resistant to T cell-tropic (T-tropic) HIV strains. Physiological activation of CD8-alpha/beta+ CD4- T cell receptor-alpha/beta+ neonatal T cells, including activation by allogeneic dendritic cells, induces the accumulation of CD4 messenger RNA and the expression of CD4 Ag on the cell surface. The large majority of anti-CD3/B7.1-activated cord blood CD8+ T cells coexpress CD4, the primary HIV receptor, as well as CCR5 and CXCR4, the coreceptors used by M- and T-tropic HIV-1 strains, respectively, to enter target cells. These findings are relevant to the rapid progression of neonatal HIV infection. Infection of primary HIV-specific CD8+ T cells may compromise their survival and thus significantly contribute to the failure of the immune system to control the infection. Furthermore, these results indicate a previously unsuspected level of plasticity in the neonatal immune system in the regulation of CD4 expression by costimulation.

CD4 Antigens↗
PubMed1998

Cerebrospinal fluid ferritin in glioblastoma: evidence for tumor synthesis.

Ferritin concentrations in cerebrospinal fluid (CSF) of 16 patients with glioblastoma were found to be very high (mean, 103.0 ng/mL) relative to 29 patients with viral meningitis and 20 patients with headache (mean concentrations, 5.4 and 4.3 ng/mL respectively). Simultaneous measurement of ferritin in CSF and serum revealed CSF concentrations exceeding those in serum in 11 of 16 patients with glioblastoma (CSF vs. serum ratio, 132.6%), contrasting with very low ratios in patients with meningitis (7.9%) or headache (4.9%). Ferritin was detected immunocytochemically in tumor cell cytoplasm in a resected glioblastoma. Thus, ferritin in CSF appears to be produced by glioblastoma cells, with a biologic significance requiring further investigation.

Adult↗
PubMed1998

Soluble mannan and beta-glucan inhibit the uptake of Malassezia furfur by human monocytic cell line, THP-1.

The uptake of live and heat-killed Malassezia furfur HIC 3321, HIC 3343 and Candida albicans ATCC 10231 by human monocytic cell line, THP-1, was examined. THP-1 was differentiated by PMA for 7 days before use. The uptake of these yeasts by THP-1 was increased in a concentration-dependent manner of yeasts, and the uptake reached plateau level at the E/T (yeast/THP-1) ratio 5. In addition, a higher percentage of heat-killed cells than live cells was taken in THP-1. Yeast mannan and beta-1,3-glucan, random coiled conformer, inhibited the uptake of live and heat-killed M. furfur by THP-1, though dextran T-250, that is alpha-glucan, and schizophyllan (SPG), triple helix conformer of beta-glucan, did not. Interestingly, mannan inhibited the uptake of both types, live and heat-killed, of C. albicans, however, laminaran inhibited the uptake of heat-killed C. albicans alone. Opsonization of these yeasts with normal human serum enhanced the uptake of yeasts, although opsonization with heat-inactivated serum, the treatment at 56 degrees C for 30 min, did not enhance. These results suggested that live and heat-killed M. furfur was recognized by THP-1 through mannose receptor, beta-glucan receptor and complement receptor type 3 via the activation of alternative pathway of complement.

Candida albicans↗
PubMed1998

Characteristics and efficiency of glutamine production by coupling of a bacterial glutamine synthetase reaction with the alcoholic fermentation system of baker's yeast.

Glutamine production with bacterial glutamine synthetase (GS) and the sugar-fermenting system of baker's yeast for ATP regeneration was investigated by determining the product yield obtained with the energy source for ATP regeneration (i.e., glucose) for yeast fermentation. Fructose 1,6-bisphosphate was accumulated temporarily prior to the formation of glutamine in mixtures which consisted of dried yeast cells, GS, their substrate (glucose and glutamate and ammonia), inorganic phosphate, and cofactors. By an increase in the amounts of GS and inorganic phosphate, the amounts of glutamine formed increased to 19 to 54 g/liter, with a yield increase of 69 to 72% based on the energy source (glucose) for ATP regeneration. The analyses of sugar fermentation of the yeast in the glutamine-producing mixtures suggested that the apparent hydrolysis of ATP by a futile cycle(s) at the early stage of glycolysis in the yeast cells reduces the efficiency of ATP utilization. Inorganic phosphate inhibits phosphatase(s) and thus improves glutamine yield. However, the analyses of GS activity in the glutamine-producing mixtures suggested that the higher concentration of inorganic phosphate as well as the limited amount of ATP-ADP caused the low reactivity of GS in the glutamine-producing mixtures. A result suggestive of improved glutamine yield under the conditions with lower concentrations of inorganic phosphate was obtained by using a yeast mutant strain that had low assimilating ability for glycerol and ethanol. In the mutant, the activity of the enzymes involved in gluconeogenesis, especially fructose 1,6-bisphosphatase, was lower than that in the wild-type strain.

Adenosine Triphosphate↗
PubMed1998

Increased bone resorption during the first year after stroke.

BACKGROUND AND PURPOSE: Significant bone mineral density (BMD) reduction occurs in stroke patients on the hemiplegic side compared with the intact side. To elucidate the pathogenesis of hip fractures in this population, we measured serum markers of bone metabolism and BMD in the stroke patients within 1 year (early group) and between 1 and 2 years after onset of hemiplegia (long-term group). METHODS: Sera were collected from 51 patients from the early group and 93 patients from the long-term group. All patients had hemiplegia. Sera were assayed for pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen (ICTP; a bone resorption marker) and bone Gla protein (a bone formation marker). The z score of BMD was determined in both second metacarpals. RESULTS: Serum ICTP concentrations (ng/mL) were higher in the early group (15.4+/-4.1) than in the long-term group (6.7+/-4.4). Bone Gla protein was normal or low in both groups. Multiple regression analysis identified Barthel Index, degree of hemiplegia, and illness duration as independent determinants of ICTP in the early group, whereas Barthel Index, degree of hemiplegia, and serum calcium were determinants of ICTP in the long-term group. There were statistically significant correlations between the z score of the hemiplegic side and age, Barthel Index, degree of hemiplegia, illness duration, 25-hydroxyvitamin D (25-OHD), and ICTP in the early group and between the z score and degree of hemiplegia and 25-OHD level in the long-term group. CONCLUSIONS: The pathogenesis of reduced BMD differed between the early and long-term stroke groups. These results suggest that in the early group, increased bone resorption caused by immobilization was responsible for osteopenia on the hemiplegic side, whereas the degree of hemiplegia and 25-OHD level were the determinants of osteopenia in the long-term group.

Aged↗
PubMed1998

A cyclic nucleotide-gated channel inhibits sensory axon outgrowth in larval and adult Caenorhabditis elegans: a distinct pathway for maintenance of sensory axon structure.

The tax-2 and tax-4 genes of C. elegans encode two subunits of a cyclic nucleotide-gated channel that is required for chemosensation, thermosensation and normal axon outgrowth of some sensory neurons. Here we show that, in tax-2 and tax-4 mutants, young larvae have superficially normal axons, but axon outgrowth resumes in inappropriate regions in late larval stages. Using a temperature-sensitive mutation in tax-2, we find that tax-2 activity is required during the adult stage to preserve normal axon morphology. These results indicate that tax-2 and tax-4 are required for the maintenance of correct axon structure, and reveal an unexpected plasticity that allows C. elegans axons to be remodeled long after their initial connections have been established. TAX-2 and TAX-4 have been proposed to form a transduction channel for chemosensation and thermosensation, and tax-2 activity is required in the adult stage for normal chemotaxis to NaCl and odorants. Animals mutant for the daf-11 gene have axon phenotypes that are similar to those of tax-2 and tax 4 mutants; this axon phenotype also has a late time of action. daf-11 regulates a developmental process called dauer larva formation that is controlled by sensory stimuli, and tax-2 and tax-4 can either stimulate or inhibit dauer larva formation in different contexts.

Animals↗
PubMed1998

Inhibition of corneal inflammation by the topical use of Ras farnesyltransferase inhibitors: selective inhibition of macrophage localization.

PURPOSE: Ras farnesyltransferase inhibitors are known to block the membrane translocalization of oncogenic Ras protein. They inhibit the cytoplasmic mitogen-activated protein kinase signaling cascade related to Ras protein. Thus far, Ras farnesyltransferase inhibitors have been exclusively regarded with the anticancer drugs. The object of this study was to elucidate the role of Ras farnesyltransferase inhibitors on the corneal opacity induced by an inflammatory stimulus. METHODS: We used a cauterization-induced corneal inflammation model. The central corneas of BALB/c mice were cauterized with silver nitrate (1 mm in diameter). Ras farnesyltransferase inhibitors, either manumycin or gliotoxin eye drops (each drug dissolved in balanced salt solution [BSS] at concentrations of 1 mM), were topically delivered to the cauterized cornea every 8 hours; BSS eye drops were used as a control. Clinical signs such as corneal edema, opacity, and corneal neovascularization, which are major causes of visual disturbance, were then examined 96 hours after the cauterization. The corneal edema and opacity were clinically scored under a stereoscopic microscope. The corneal neovascularization was evaluated by the length of the blood vessels from the limbus and the sum of extension central angle of vascularized limbus. Furthermore, the corneas were examined histologically, and the phenotypes of the cornea-infiltrating cells were analyzed by flow cytometry. RESULTS: The control corneas showed prominent edema, neovascularization, and opacity. Histologic analysis revealed corneal epithelial and endothelial cell loss and a large amount of inflammatory cell infiltration into the corneal stroma. Flow cytometric analysis revealed that most of the infiltrating cells were neutrophils and macrophages. In contrast, the degree of corneal edema, neovascularization, and opacity was significantly less in the manumycin- or gliotoxin-treated corneas than in the control corneas. Histologically, the manumycin- and gliotoxin-treated corneas showed minimum edema and good epithelialization. Flow cytometric analysis showed corneal infiltration of macrophages to be selectively and clearly inhibited. Neither manumycin nor gliotoxin produced any side effects in the noncauterized normal cornea either clinically or histologically. CONCLUSIONS: Ras proteins play an important role in cauterization-induced corneal inflammation and the opacity it induces. Ras farnesyltransferase inhibitors thus have a great potential for improving the treatment of corneal opacity induced by a corneal inflammatory stimulus.

Administration, Topical↗
PubMed1997

Expression and function of OX40 ligand on human dendritic cells.

OX40 ligand (OX40L), a member of the TNF family, was shown to be capable of signaling both the cells on which it is expressed and those expressing OX40, its cognate receptor. Here we show that OX40L is expressed on dendritic cells (DC), the most efficient APC to prime naive T cells. The expression and the functional activity of OX40L were examined by means of mAbs used to stain or cross-link OX40L on 1) freshly isolated human blood DC (bDC) and 2) monocyte-derived DC at different stages of differentiation. These were derived from monocytes cultured either with IL-4 and granulocyte-macrophage CSF (IL-4-Mo-DC) or with IL-4 and granulocyte-macrophage CSF plus TNF-alpha. Both types of Mo-DC expressed OX40L after stimulation through CD40; ligation of OX40L on activated IL-4-Mo-DC enhanced by 4- to 35-fold their cytokine production (TNF-alpha, IL-12 p40, IL-1 beta, and IL-6) and increased CD80, CD86, CD54, and CD40 expression. Stimulation of activated IL-4-Mo-DC through OX40L strikingly enhanced their maturation as evidenced by CD83 up-regulation, CD115 (CSF-1R) down-regulation, and typical morphologic changes. OX40L was constitutively expressed on a subset of bDC, and its ligation slightly enhanced CD40L-stimulated IL-12 production. OX40L was down-regulated after overnight culture and spontaneously reexpressed on a subset of mature bDC (CD83high, CD33high, CD11chigh, CD5+). Thus, the expression of OX40L on DC suggests a physiologic role of this molecule during T cell priming by virtue of its ability to costimulate both T cell and DC activation and differentiation.

Adult↗
PubMed1997

Structure and expression of the gsa-1 gene encoding a G protein alpha(s) subunit in C. elegans.

The heterotrimeric guanine nucleotide-binding proteins (G proteins) act as switches in the signal transduction from cell surface receptors to a variety of effectors. Among them, Gs proteins stimulate adenylate cyclase activities and regulate ion channels in mammals. We identified the gsa-1 gene encoding a G protein alpha subunit in the nematode Caenorhabditis elegans. The predicted product consists of 375 amino acid residues, 66% of which are identical with those of a mammalian Gs(alpha) subunit. The gsa-1 gene was physically mapped near the left end of chromosome I. A gsa-1/lacZ fusion gene was expressed in many cells in embryos, larvae and adults, including neurons, body wall muscle cells and muscle cells of the pharynx and the vulva. The results presents a basis for genetic studies of the gsa-1 gene.

Amino Acid Sequence↗