Search PubMed⌕ Search

Biomedical subjects

K Nishida

Publications and source records attributed to K Nishida.

At least 109 records · Page 6Linked to original sources
PubMed1999

Protective effect of metallothionein to ras DNA damage induced by hydrogen peroxide and ferric ion-nitrilotriacetic acid.

Metallothionein (MT) is a strong antioxidant, due to a large number of thiol groups in the MT molecule and MT has been found in the nucleus. To investigate whether MT can directly protect DNA from damage induced by hydroxyl radical, the effects of MTs on DNA strand scission due to incubation with ferric ion-nitrilotriacetic acid and H2O2 (Fe3+ -NTA/H2O2) were studied. The Fe3+-NTA/H2O2 resulted in a higher rate of deoxyribose degradation, compared to incubation of Fe3+/H2O2, presumably mediated by the formation of hydroxyl radicals (*OH). This degradation was inhibited by either Zn-MT or Cd-MT, but not by Zn2+ or Cd2+ at similar concentrations. The Fe3+ -NTA/H2O2 resulted in a concentration dependent of increase in DNA strand scission. Damage to the sugar-phosphodiester chain was predominant over chemical modifications of the base moieties. Incubation with either Zn-MT or Cd-MT inhibited DNA damage by approximately 50%. Preincubation of MT with EDTA and N-ethylmaleimide, to alkylate sulfhydryl groups of MT, resulted in MT that was no longer able to inhibit DNA damage. These results indicates that MT can protect DNA from hydroxyl radical attack and that the cysteine thiol groups of MT may be involved in its nuclear antioxidant properties.

Animals↗
PubMed1999

p53 null mutations undetected by immunohistochemical staining predict a poor outcome with early-stage non-small cell lung carcinomas.

The importance of p53 mutations in the pathogenesis of human lung carcinoma is well established, but it is still controversial whether the presence of p53 mutations or overexpression of p53 protein adversely affects an individual patient's chances of survival. The controversy may be partially due to the methodological differences in examination for p53 alterations: gene analysis or immunohistochemical staining. Furthermore, recent studies have suggested that different types of mutations of the p53 tumor suppressor gene confer different biological properties. To clarify the relationship between immunohistochemical staining and prognosis, we investigated mutations using single-strand conformation polymorphism followed by sequencing for exons 4-8 and 10 in 144 surgically treated non-small cell lung carcinoma patients with intensive clinical follow-up. Of 144 cases, 107 adenocarcinomas were examined for immunohistochemical staining with RSP53 antibody. p53 gene mutations were observed in 65 tumors (45%), including 44 missense and 21 null mutations, the latter comprising 7 nonsense mutations, 8 deletions, 2 insertions, and 4 splicing junction mutations. Presence of p53 mutations was an independent prognostic factor with a statistical trend (P = 0.14) in stage I patients but not in all cases. When examined by mutational pattern, null mutation was a significant indicator of poor outcome by multivariate analysis (P = 0.03) in stage I patients, whereas cases with missense mutations and without mutations did not differ (P = 0.76). Forty (37%) tumors demonstrated overexpression of the p53 protein but without any survival difference. Most tumors (76%) with missense mutations were immunopositive, but those with null mutations with one exception (93%) were not, and the concordance between the mutations and immunohistochemical staining was rather low at 65%. These data suggest that the type of p53 mutation is important for prediction of outcome in early-stage non-small cell lung carcinoma patients, whereas immunohistochemical staining for abnormal p53 gene products is nonpredictive. Furthermore, null mutations causing loss of function of the gene product may play more important roles than missense mutations in tumor progression.

Adenocarcinoma↗
PubMed1999

Aminoacylation of tRNAs encoded by Chlorella virus CVK2.

Viruses that infect certain strains of the unicellular green alga, Chlorella, have a large, linear dsDNA genome that is 330-380 kb in size; this genomic size is the largest known among viruses and is equivalent to approximately 60% of the smallest prokaryotic genome of Mycoplasma genitalium (580 kb). Besides many putative protein-coding genes, a cluster of 10-15 tRNA genes is present in these viral genomes. Some of these tRNA genes contain peculiar insertions. In infected host cells, the viral tRNAs of CVK2, a Chlorella virus isolate, have been demonstrated to be cotranscribed as a large precursor, approximately 1.0 kb in size, that is precisely processed into individual mature tRNA species. Acidic Northern blot analysis of eight of these tRNAs has revealed that they are actually aminoacylated in vivo, indicating their involvement in viral protein synthesis. They may help the virus reach maximal replication potential by overcoming codon usage barriers that exist between the virus and its host. These results provide evidence that some components of the host protein synthesis machinery can be replaced by viral gene products. This is the first report of tRNA aminoacylation encoded by viruses of eukaryotes.

Acylation↗
PubMed1999

Association of the proto-oncogene product dbl with G protein betagamma subunits.

The Rho family of GTP-binding proteins has been implicated in the regulation of various cellular functions including actin cytoskeleton-dependent morphological change. Its activity is directed by intracellular signals mediated by various types of receptors such as G protein-coupled receptors. However, the mechanisms underlying receptor-dependent regulation of Rho family members remain incompletely understood. The guanine nucleotide exchange factor (GEF) Dbl targets Rho family proteins thereby stimulating their GDP/GTP exchange, and thus is believed to be involved in receptor-mediated regulation of the proteins. Here, we show the association of Dbl with G protein betagamma subunits (Gbetagamma) in transient co-expression and cell-free systems. An amino-terminal portion conserved among a subset of Dbl family proteins is sufficient for the binding of Gbetagamma. In fact, Ost and Kalirin, which contain this Gbetagamma-binding motif, also associate with Gbetagamma. c-Jun N-terminal kinase was synergistically activated upon co-expression of Dbl and Gbeta in a dominant-negative Rho-sensitive manner. However, GEF activity of Dbl toward Rho as measured by in vitro GDP binding assays remained unaffected following Gbetagamma binding, suggesting that additional signals may be required for the regulation of Dbl.

Animals↗
PubMed1999

Integrin-regulated secretion of interleukin 4: A novel pathway of mechanotransduction in human articular chondrocytes.

Chondrocyte function is regulated partly by mechanical stimulation. Optimal mechanical stimulation maintains articular cartilage integrity, whereas abnormal mechanical stimulation results in development and progression of osteoarthritis (OA). The responses of signal transduction pathways in human articular chondrocytes (HAC) to mechanical stimuli remain unclear. Previous work has shown the involvement of integrins and integrin-associated signaling pathways in activation of plasma membrane apamin-sensitive Ca2+-activated K+ channels that results in membrane hyperpolarization of HAC after 0. 33 Hz cyclical mechanical stimulation. To further investigate mechanotransduction pathways in HAC and show that the hyperpolarization response to mechanical stimulation is a result of an integrin-dependent release of a transferable secreted factor, we used this response. Neutralizing antibodies to interleukin 4 (IL-4) and IL-4 receptor alpha inhibit mechanically induced membrane hyperpolarization and anti-IL-4 antibodies neutralize the hyperpolarizing activity of medium from mechanically stimulated cells. Antibodies to interleukin 1beta (IL-1beta) and cytokine receptors, interleukin 1 receptor type I and the common gamma chain/CD132 (gamma) have no effect on me- chanically induced membrane hyperpolarization. Chondrocytes from IL-4 knockout mice fail to show a membrane hyperpolarization response to cyclical mechanical stimulation. Mechanically induced release of the chondroprotective cytokine IL-4 from HAC with subsequent autocrine/paracrine activity is likely to be an important regulatory pathway in the maintenance of articular cartilage structure and function. Finally, dysfunction of this pathway may be implicated in OA.

Adult↗
PubMed1999

An association between lipid peroxidation and alpha-naphthylisothiocyanate-induced liver injury in rats.

An association between lipid peroxidation and alpha-naphthylisothiocyanate (ANIT)-induced liver injury was examined in rats injected once with the toxicant (75 mg/kg body weight). The severity of liver injury was estimated 12, 24, 48, and 72 h after ANIT injection. Liver injury appeared 24 h after ANIT injection, progressed at 48 h, and recovered at 72 h, judging from the serum levels of marker enzymes and components. Serum lipid peroxide (LPO) concentration increased 24 h after ANIT injection and further increased at 48 h, but this increase was attenuated at 72 h. In contrast, liver LPO content increased 12 h after ANIT injection and further increased 24 and 48 h, but this increase was attenuated at 72 h. Similarly, myeloperoxidase (MPO) activity, an index of neutrophil infiltration, in the liver tissue increased 12 h after ANIT injection and further increased at 24 and 48 h, but this increase was attenuated at 72 h. Either serum LPO concentration or liver LPO content was significantly correlated with liver MPO activity (r = 0.661 for serum LPO concentration; r = 0.585 for liver LPO content). These results suggest that lipid peroxidation might be associated with ANIT-induced liver injury in rats and that this lipid peroxidation might occur via oxygen radicals derived from neutrophils infiltrated into the liver tissue of ANIT-intoxicated rats.

1-Naphthylisothiocyanate↗
PubMed1999

Genetic variation of chlorella viruses: variable regions localized on the CVK2 genomic DNA.

A physical map of the Chlorella virus CVK2 genomic DNA has been constructed based on a cosmid contig covering the entire genomic region. By using Southern blot analysis with 22 gene probes, the gene arrangement along the genome was compared between CVK2 and PBCV-1, the prototypic member of Phycodnaviridae, whose genomic sequence is now available. The major rearrangements were (1) an insertion of a 20-kbp region around the left end of CVK2 DNA, (2) a duplication of the gene for major capsid protein in CVK2 DNA, (3) deletions/insertions of some open reading frames, and (4) divergence in the terminal inverted repeat sequences. Despite these changes, extensive colinearity was revealed between most of the genes along the CVK2 and PBCV-1 genomes. These data imply that the Chlorella virus genome has an overall high degree of genomic stability, encompassing specific islands of rearrangements.

Amino Acid Sequence↗
PubMed1999

Gab-family adapter proteins act downstream of cytokine and growth factor receptors and T- and B-cell antigen receptors.

We previously found that the adapter protein Gab1 (110 kD) is tyrosine-phosphorylated and forms a complex with SHP-2 and PI-3 kinase upon stimulation through either the interleukin-3 receptor (IL-3R) or gp130, the common receptor subunit of IL-6-family cytokines. In this report, we identified another adapter molecule (100 kD) interacting with SHP-2 and PI-3 kinase in response to various stimuli. The molecule displays striking homology to Gab1 at the amino acid level; thus, we named it Gab2. It contains a PH domain, proline-rich sequences, and tyrosine residues that bind to SH2 domains when they are phosphorylated. Gab1 is phosphorylated on tyrosine upon stimulation through the thrombopoietin receptor (TPOR), stem cell factor receptor (SCFR), and T-cell and B-cell antigen receptors (TCR and BCR, respectively), in addition to IL-3R and gp130. Tyrosine phosphorylation of Gab2 was induced by stimulation through gp130, IL-2R, IL-3R, TPOR, SCFR, and TCR. Gab1 and Gab2 were shown to be substrates for SHP-2 in vitro. Overexpression of Gab2 enhanced the gp130 or Src-related kinases-mediated ERK2 activation as that of Gab1 did. These data indicate that Gab-family molecules act as adapters for transmitting various signals.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Anti-apoptotic function of Rac in hematopoietic cells.

The small GTP-binding protein Rac plays a pivotal role in the regulation of diverse physiological events including reorganization of the actin cytoskeleton, cell cycle progression, and transformation. Here we show an anti-apoptotic effect of Rac in interleukin-3-dependent murine hematopoietic BaF3 cells. Activated Rac(G12V), when ectopically expressed in BaF3 cells, rendered the cells resistant to apoptosis upon interleukin-3 deprivation, while activated mutants of Rho and Cdc42 displayed no significant anti-apoptotic effect. In contrast to activated Ras, which also supports cell survival in the absence of interleukin-3, Rac required fetal bovine serum for the prevention of cell death. The involvement of phosphatidylinositol 3-kinase downstream of Rac was demonstrated by the inhibition of Rac-induced cell survival by wortmannin and LY294002 and the presence of phosphatidylinositol kinase activity in the Rac immunoprecipitate. Furthermore, the serine/threonine kinase Akt was stimulated by activated Rac and fetal bovine serum in a synergistic manner. Rac-induced Akt activation was mediated by phosphorylation of threonine-308 and serine-473. In addition to the phosphatidylinositol 3-kinase/Akt pathway, the p38 mitogen-activated protein kinase pathway was crucial for Rac-dependent survival, whereas p38 mitogen-activated protein kinase nas not implicated in Ras-induced anti-apoptotic signaling. These findings provide evidence for the involvement of Rac in survival signaling of hematopoietic cells.

Animals↗
PubMed1999

Doubling time of serum CA 19-9 in the clinical course of patients with pancreatic cancer and its significant association with prognosis.

BACKGROUND AND OBJECTIVES: Pancreatic cancer is generally a disease with a poor prognosis, and relationship between change of serum CA 19-9 level and progression of this disease was investigated with regard to clinical pace of disease and tumor growth. METHODS: CA 19-9 doubling time was examined in 75 patients with pancreatic cancer, including 41 inoperable cases. Then, its relation with their prognosis and change in tumor was evaluated. RESULTS: The doubling time of CA 19-9 and CEA could be calculated in 90.2% and 58.5% of patients with inoperable pancreatic cancer. CA 19-9 doubling time was clearly associated with survival time in inoperable and palliatively operated cases, but not with sex, age, site of the lesion, or liver metastasis, and was significantly correlated with the tumor volume doubling time. CONCLUSIONS: Examination of CA 19-9 doubling time may be useful in clinical evaluation of the prognosis for patients with pancreatic cancer and could possibly prove valuable in terms of the analysis of the growth process in this disease.

Adult↗
PubMed1999

Therapeutic effect of Oren-gedoku-to extract on stress-induced acute gastric mucosal lesions in rats.

Oral administration of Oren-gedoku-to extract (TJ-15), a traditional Chinese herbal medicine for the therapy of gastric ulcers and gastritis, dose-dependently prevented the progression of acute gastric mucosal lesions in rats with water immersion restraint (WIR) stress. The preventive effect of TJ-15 on the lesion progression was stronger than that of Saiko-keishi-to extract (TJ-10) or Shigyaku-san extract (TJ-35), each of which is a traditional Chinese herbal medicine for the therapy of gastric ulcers and gastritis, when compared on the basis of a single dosage of each medicine for adults. This TJ-15 administration attenuated increases in gastric mucosal lipid peroxide concentration and xanthine oxidase and myeloperoxidase activities with the gastric mucosal lesion progression and recovered the decreased gastric mucosal non-protein SH concentration found at a progressed stage of the gastric mucosal lesions. These results indicate that TJ-15 exerts a therapeutic effect on WIR stress-induced acute gastric lesions in rats more strongly than TJ-10 or TJ-35, and suggest that the therapeutic effect of TJ-15 could be due to its preventive actions on lipid peroxidation and sulphydryl oxidation via oxygen free radicals generated by the xanthine-XO system and infiltrated neutrophils in the gastric mucosa and on neutrophil infiltration into the tissue.

Animals↗
PubMed1999

Preventive effect of teprenone on stress-induced gastric mucosal lesions and its relation to gastric mucosal constitutive nitric oxide synthase activity.

Recently, we demonstrated that teprenone, an anti-ulcer agent, exerts protective and preventive actions against water immersion restraint (WIR) stress-induced gastric mucosal lesions in rats both by inhibiting neutrophil infiltration into the gastric mucosal tissue and by preserving gastric mucus synthesis and secretion. In rats with WIR stress we have also found a decrease in gastric mucosal constitutive nitric oxide synthase (cNOS) activity and a drastic increase in gastric mucosal inducible nitric oxide synthase (iNOS) activity. The decrease in gastric mucosal cNOS activity is closely related to an increase in neutrophil infiltration into the gastric mucosa and a decrease in the level of gastric mucus. In this study of WIR-stressed rats, therefore, we examined whether the inhibitory actions of teprenone on neutrophil infiltration and decreases in mucus synthesis and secretion in the gastric mucosa of rats are related to the change in gastric mucosal cNOS activity during the development of gastric mucosal lesions. Pre-administration of teprenone (200 mg kg-1) prevented the decrease in gastric mucosal cNOS activity with attenuations of neutrophil infiltration into gastric mucosal tissues and decreased levels of gastric mucosal hexosamine, an index of gastric mucin, and adherent mucus in rats with 3 or 6 h of WIR stress. These preventive effects of teprenone on the gastric mucosal neutrophil infiltration and the decrease in gastric mucus levels in rats with WIR stress were completely reversed with inhibition of gastric mucosal cNOS activity by co-administration of NG-monomethyl L-arginine (L-NMMA), a non-selective NOS inhibitor. These results suggest that the inhibitory actions of teprenone on neutrophil infiltration and decreases in mucus synthesis and secretion in the gastric mucosa of rats with WIR stress are closely related to the maintenance of cNOS activity in the gastric mucosal tissue.

Animals↗
PubMed1999

Preventive effect of melatonin on the progression of carbon tetrachloride-induced acute liver injury in rats.

We examined the preventive effect of melatonin on the progression of carbon tetrachloride (CCl4)-induced acute liver injury in rats. In rats injected with CCl4 (1.0 ml/kg body weight), liver injury appeared 6 h after the injection and progressed at 24 h. This liver injury progression was prevented by treatment with melatonin (50 or 100 mg/kg body weight), which was conducted 6 h after CCl4 injection. An increase in liver lipid peroxide content and a decrease in liver reduced glutathione content occurred with the liver injury progression. These changes were prevented by the post-treatment of melatonin (50 or 100 mg/kg body weight). These results indicate that melatonin can prevent the progression of CCl4-induced acute liver injury through its antioxidant action.

Animals↗
PubMed1999

Expression of CD44 variants in osteosarcoma.

The standard form of CD44 (CD44H) is a transmembranous glycoprotein, widely distributed on a variety of human lymphoid cells, epithelial cells and tumours. CD44 has many variant forms, which are generated by alternative splicing. In recent years, CD44 has been reported to be related to the degree of tumour differentiation, tumour cell invasion, and metastasis. We investigated 44 tumour specimens in 39 patients with osteosarcoma immunochemically to analyse the expression of CD44 standard (CD44H) and variant exon-encoded gene products (CD44v3, v4, v5, v6, v7, v9, and v10). Furthermore, the relationship between CD44 expression and the clinical outcome of patients with osteosarcoma was analysed. Membrane accentuation and exclusive cytoplasmic reactivity were analysed as separate staining patterns. Tumour cells and some multinucleated giant cells were markedly stained. CD44H, v3, v4, v5, v6, v7, v9, and v10 were expressed in 85%, 49%, 54%, 59%, 46%, 5%, 28%, and 10% of the specimens respectively. The cumulative 5-year metastasis-free survival was 58% in CD44v6-negative cases and 24% in CD44v6-positive cases (P=0.046). However, the cumulative 5-year metastasis-free survival was not significantly different between cases positive and negative for other variants of CD44. Multivariate analysis (Cox proportional-hazard model) with CD44v6 expression (positive or negative), chemotherapy (intensive or non-intensive), tumour site (proximal or distal), and age (at least 30 years or less than 30 years) showed that expression of CD44v6 and chemotherapy were important prognostic factors in patients with osteosarcoma. Overexpression of CD44 isoforms containing variant v6 is correlated with poor prognosis in patients with osteosarcoma.

Adolescent↗
PubMed1999

Amyloid and Pro501 Thr-mutated (beta)ig-h3 gene product colocalize in lattice corneal dystrophy type IIIA.

PURPOSE: To assess the relative distribution in the cornea of amyloid and (beta)ig-h3 gene product in lattice corneal dystrophy type IIIA (LCD-IIIA). METHODS: Serial sections from the cornea of a patient with LCD-IIIA were subjected to either Congo red staining or immunohistochemistry employing an antibody to (beta)ig-h3. Also, genomic DNA was isolated from peripheral blood and used as a template for polymerase chain reaction to amplify all exons of (beta)ig-h3. RESULTS: Exon 11 of (beta)ig-h3 was mutated (Pro501Thr). Subepithelial and intrastromal congophilic deposits exhibited a birefringency characteristic of amyloid. These regions of the tissue were also highly immunoreactive with the antibody to the (beta)ig-h3 gene product. CONCLUSION: Amyloid and Pro501Thr-mutated (beta)ig-h3 protein accumulate and colocalize in LCD-IIIA.

Aged↗
PubMed1999

Epithelial hyperproliferation and transglutaminase 1 gene expression in Stevens-Johnson syndrome conjunctiva.

In Stevens-Johnson syndrome, pathological keratinization of the ordinarily nonkeratinized corneal and conjunctival mucosal epithelia results in severe visual loss. We examined conjunctiva covering cornea in five eyes in the chronic cicatricial phase of Stevens-Johnson syndrome. Normal conjunctiva from five age-matched individuals was studied also. The number of epithelial cells in Stevens-Johnson syndrome conjunctiva that were immunoreactive with a monoclonal antibody, Ki-67, to a nuclear antigen found only in proliferating cells was greater than normal (93.8+/-19.8 cells above 100 basal cells versus 12.8+/-0.5 cells above 100 basal cells; P = 0.009). In addition, although clinical inflammation was mild, massive lymphocytic infiltration was seen in the substantia propria of conjunctiva covering cornea. In situ hybridization documented transglutaminase 1 (keratinocyte transglutaminase) mRNA in suprabasal cells of the abnormally thickened conjunctival epithelium in all Stevens-Johnson syndrome patients. In contrast, no message was detected in normal conjunctival or corneal epithelia. Transglutaminase 1 is expressed during the terminal differentiation of keratinocytes where it helps synthesize cornified cell envelopes. We speculate that in Stevens-Johnson syndrome, epithelial hyperproliferation, and transglutaminase 1 gene expression lead to the pathological keratinization of ocular surface mucosal epithelia.

Adult↗
PubMed1999

Modulation of stress-induced gastric mucosal lesions by exogenous L-arginine.

L-arginine, a nitric oxide (NO) precursor, can exert both ameriolative and deteriorative effects on gastric mucosal lesions. This study was designed to determine whether exogenous L-arginine modulates stress-induced gastric mucosal lesions through NO production by either constitutive NO synthase (cNOS) or inducible NO synthase (iNOS) in gastric mucosal tissues. In rats subjected to water immersion restraint stress over a 6-hour period, the concentration of gastric mucosal nitrite/nitrate, breakdown products of NO, increased with the development of gastric mucosal lesions and a decrease in cNOS activity and a drastic increase in iNOS activity in the gastric mucosal tissue. Preadministration of L-arginine (150 to 600 mg/kg intraperitoneally) attenuated the lesion development with prevention of increases in gastric mucosal nitrite/nitrate concentration and iNOS activity. In contrast, postadministration of L-arginine (150 to 600 mg/kg intraperitoneally) enhanced the lesion development with further increase in gastric mucosal nitrite/nitrate concentration. This deteriorative action of postadministration of L-arginine (300 mg/kg intraperitoneally) was prevented by pretreatment with aminoguanidine (100 mg/kg subcutaneously), a selective iNOS inhibitor, with inhibition of increases in gastric mucosal iNOS activity and nitrite/nitrate concentration. These results indicate that preadministered L-arginine protects against water immersion restraint stress-induced gastric mucosal lesions, possibly through restricted NO production by cNOS in gastric mucosal tissues, whereas postadministered L-arginine aggravates the stress-induced gastric mucosal lesions, possibly through excessive NO production by iNOS increasing in gastric mucosal tissues.

Animals↗