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Biomedical subjects

K Okada

Publications and source records attributed to K Okada.

At least 469 records · Page 26Linked to original sources
PubMed1997

Measurement of histidinohydroxylysinonorleucine and hydroxyproline in skin collagen by reversed-phase high-performance liquid chromatography after 9-fluorenylmethyl chloroformate labeling.

A novel, highly sensitive method to quantify histidinohydroxylysinonorleucine (HHL), a trifunctional type of cross-link in skin collagen, was developed. HHL in skin hydrolysates labeled with 9-fluorenylmethyl chloroformate (FMOC-Cl) was separated by reversed-phase high-performance liquid chromatography. Mass spectrometric analysis revealed that two FMOCs were bound to two primary amino acid residues, histidine and hydroxylysine, but not to lysine residue in one HHL molecule. Hydroxyproline was simultaneously measured to express the molar ratio of HHL to collagen. The detection range of HHL was from 1 to 10 pmol and that of hydroxyproline from 1 to 50 pmol. A 6-mm punch-biopsied human skin sample contained 0.40 to 0.69 mol of HHL per one molecule of collagen. This sensitive method is useful as it is rapid and can be used to examine the aging process or the change of HHL content in skin collagens of various pathologic states.

Chromatography, High Pressure Liquid↗
PubMed1997

Nitric oxide mediates murine cytomegalovirus-associated pneumonitis in lungs that are free of the virus.

4 wk after intraperitoneal inoculation of 0.2 LD50 (50% lethal dose) of murine cytomegalovirus (MCMV) in adult BALB/c mice, MCMV remained detectable in the salivary glands, but not in the lungs or other organs. When the T cells of these mice were activated in vivo by a single injection of anti-CD3 monoclonal antibody, interstitial pneumonitis was induced in the lungs that were free of the virus with an excessive production of the cytokines. In the lungs of such mice persistently infected with MCMV, the mRNA of the cytokines such as IL-2, IL-6, TNF-alpha, and IFN-gamma were abundantly expressed 3 h after the anti-CD3 injection, and the elevated levels continued thereafter. A marked expression of inducible nitric oxide synthetase (iNOS) was then noted in the lungs, suggesting that such cytokines as TNF-alpha and IFN-gamma may have induced iNOS. Although the increase in NO formation was demonstrated by the significant elevation of the serum levels of nitrite and nitrate, the interstitial pneumonitis was not associated with either increased superoxide formation or peroxynitrite-induced tyrosine nitration. Nevertheless, the administration of an NO antagonist also alleviated the interstitial pneumonitis provoked by anti-CD3 mAb. Based on these findings, it was concluded that MCMV-associated pneumonitis is mediated by a molecule of cytokine-induced NO other than peroxynitrite.

Animals↗
PubMed1997

Synthetic of Uniform Spindle-Type Titania Particles by the Gel-Sol Method

Uniform spindle-type titania (TiO2) particles were prepared by a novel gel-sol method. A mixed solution of titanium(IV) isopropoxide and triethanolamine at molar ratio 1:2 prepared in a drybox was mixed with doubly distilled water to make the final concentration of titanium(IV) 0.50 mol dm-3. The mixture was further mixed with an equal volume of 2.0 mol dm-3 ammonia solution, and the resulting solution was aged for 24 h at 100°C. By this aging a highly viscous gel was formed, but there was no sign of nucleation of titania at this stage. The gel was then aged at 140°C for 3 days to nucleate and grow the titania particles. The gel network formed in the first aging played a decisive role in the second aging to produce the uniform particles of titania, as a reservoir of the metal ions to lower the supersaturation for preventing extensive nucleation and as an anticoagulant fixing the growing particles in the matrix. The product was identified by XRD as anatase particles elongated in the direction of the c-axis. The aspect ratio, as well as the size of the resulting particles, was reduced as the concentration of ammonia was decreased. Copyright 1997Academic Press

Journal Article↗
PubMed1997

Epidermal cell differentiation in Arabidopsis determined by a Myb homolog, CPC.

The roots of plants normally carry small hairs arranged in a regular pattern. Transfer DNA-tagged lines of Arabidopsis thaliana included a mutant with few, randomly distributed root hairs. The mutated gene CAPRICE (CPC) encoded a protein with a Myb-like DNA binding domain typical of transcription factors involved in animal and plant development. Analysis in combination with other root hair mutations showed that CPC may work together with the TTG gene and upstream of the GL2 gene. Transgenic plants overexpressing CPC had more root hairs and fewer trichomes than normal. Thus, the CPC gene determines the fate of epidermal cell differentiation in Arabidopsis.

Amino Acid Sequence↗
PubMed1997

Overcoming CPT-11 resistance by using a biscoclaurine alkaloid, cepharanthine, to modulate plasma trans-membrane potential.

Irinotecan, 7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxycamptothecin, (CPT-11) resistance was overcome by using a biscoclaurine alkaloid, cepharanthine, in CPT-11- and multidrug-resistant 50MT-1 cells. 50MT-1 cells were established from a mouse breast-cancer cell line, FM3A, by subjecting the cells to a low dose of CPT-11 continuously. 50MT-1 cells exhibited resistance to CPT-11 (40-fold in colony-formation assay) and to other drugs such as doxorubicin (11.7-fold) and etoposide (VP-16) (16.8-fold). The plasma trans-membrane potential was lower in 50MT-1 cells than in FM3A cells, although there were no differences in expressions of P-glycoprotein and of DNA topoisomerase-I and -II proteins. The lower membrane potential in 50MT-1 cells was augmented by co-treatment with a non-toxic dose of cepharanthine. CPT-11 resistance in 50MT-1 cells was overcome (5.0- to 1.4-fold, 6-hr exposure) by the co-treatment with cepharanthine through increasing intracellular accumulation of CPT-11. Resistance to doxorubicin and VP-16 was also overcome by cepharanthine treatment (2.5- to 0.69-fold and 4.2- to 1.4-fold respectively). We conclude that the modification of plasma trans-membrane potential by cepharanthine should be effective in overcoming CPT-11 and multidrug resistance in 50MT-1 cells.

Alkaloids↗
PubMed1997

Deletion of c-myb exon 9 induced by insertion of repeats.

A simple repeat was found to be inserted into exon 9 of the c-myb gene in three out of 20 bovine T lymphomas. The repeat was composed of multiple copies of a 12-nucleotide motif and had no significant homology to the sequences reported so far. Tumor cells containing the repeat expressed two kinds of c-myb mRNA: (1) are that included the repetitive sequence in exon 9, and (2) are that lacked the whole sequence of exon 9. Transfection of an expression vector containing exon and intron sequences and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of the mRNA demonstrated that the insertion of the repeat enhanced exon skipping of the transfected minigene. These observations imply that the insertion of the repeat may enhance exon skipping of the c-myb pre-mRNA. Although the transcription-activating activity by the c-Myb with the repeat was low, that by the c-Myb without exon 9 was three- to eightfold higher than the wild-type c-Myb. These data suggest that insertion of the 12-nucleotide repeat in codon 359 may result in c-Myb proteins having high- and low-transcription-activating activity.

Animals↗
PubMed1997

Biomarker evidence of DNA oxidation in lung cancer patients: association of urinary 8-hydroxy-2'-deoxyguanosine excretion with radiotherapy, chemotherapy, and response to treatment.

Ratios of urinary 8-hydroxy-2'-deoxyguanosine to urinary creatinine (8-OHdG/creatinine) have been considered as a good biological indicator of DNA oxidation. Urinary 8-OHdG/creatinine levels of lung cancer patients were evaluated by enzyme-linked immunosorbent assay using a monoclonal antibody N45.1 during radiotherapy and chemotherapy. An increase in urinary 8-OHdG/creatinine was found in non-small-cell carcinoma (non-SCC) patients during the course of radiotherapy. SCC patients showed higher levels of urinary 8-OHdG/creatinine than the controls. Furthermore, SCC patients with complete or partial response to the chemotherapy showed a significant decrease in urinary 8-OHdG/creatinine while patients with no change or progressive disease showed an increase.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1997

Competence of a migratory bird, red-bellied thrush (Turdus chrysolaus), as an avian reservoir for the Lyme disease spirochetes in Japan.

To evaluate the competence of migratory birds as reservoirs for the Lyme disease spirochetes, we examined two species of migrants, Red-bellied thrush (Turdus chrysolaus) and Black-faced bunting (Emberiza spodocephala) in Nemuro, the northern part of Japan. Spirochetes were found in four individual birds out of 11 T. chrysolaus, three isolates were detected from the skins and the other one was obtained from the liver. No spirochete was found to be infected in 20 E. spodocephala. As far as we know, this is the first record of direct detection of the spirochetes from migratory birds in Japan. The spirochetes were also isolated from immature ixodid ticks, Ixodes persulcatus, fed on those species of birds. The spirochetes were transmitted trans stadially to the next stage, when infected ticks molted. All of the isolates from birds and ticks were identified as Borrelia garinii by our ribotyping and flagellin gene sequence analyses. Our results strongly suggest that the migratory birds are reservoirs in the transmission of the Lyme disease spirochetes in Japan.

Animals↗
PubMed1997

Tranilast inhibits the growth of rat mesangial cells.

We investigated the effects of tranilast on the growth of cultured rat mesangial cells. The number of mesangial cells increased fivefold during a 5-day incubation in RPMI 1640 with 20% fetal bovine serum. The number of cells was significantly lower in the presence of tranilast than in its abscence. Tranilast (0 approximately 500 microM) inhibited platelet-derived growth factor (PDGF)-induced DNA synthesis of rat mesangial cells cultured in RPMI 1640 medium containing 0.5% fetal bovine serum in a dose-dependent manner. The inhibition of DNA synthesis by tranilast was not affected by the presence of indomethacin (1 microg/ml) or N(G)-monomethyl-L-arginine (0.5 mM). Tranilast did not stimulate nitrite oxide synthesis in PDGF-stimulated cells. Mitogen-activated protein kinase activity in mesangial cells was significantly increased by exposure to PDGF, while the effect was significantly suppressed in the presence of tranilast. The present study revealed that tranilast inhibits the growth of rat mesangial cells, independently of nitric oxide or prostacycline synthesis.

Animals↗
PubMed1997

Interactions between autologous CD4+ and CD8+ T lymphocytes and human squamous cell carcinoma of the head and neck.

The autotumor (AuTu)-specific cytolytic T lymphocyte (CTL) line established from the peripheral blood of a patient with oral squamous cell carcinoma (Cancer Res. 53, 1461, 1993) contained >95% of CD8+ and <5% of CD4+ T cells. This CTL line was infected with Herpesvirus saimiri to increase its life span in culture. Two transformed T cell sublines were obtained: the monoclonal CD4+ line (TCR Vbeta2+ V alpha15+) and the oligoclonal CD8+ line (TCR Vbeta6+, Vbeta7+ and Vbeta9+) both of which were maintained in culture for >6 months without AuTu restimulation and which did not produce any virus. The virus-transformed and untransformed T cell lines were compared for phenotypic and functional characteristics, including the ability to kill AuTu, induce expression of the major histocompatibility complex (MHC) antigens on AuTu, and respond to AuTu by cytokine production and/or proliferation. The H. saimiri-transformed CD4+ T cells expressed higher levels of surface adhesion molecules and CD45RO than untransformed cells and lysed AuTu by inducing DNA fragmentation as well as necrosis. This lysis was inhibited by antibodies to CD4 but not to class I or II MHC molecules. The CD4+ T cells produced IL2, TNF-alpha, and GM-CSF and proliferated in response to AuTu. They induced and sustained proliferation of CD8+ T cells in cocultures with AuTu. Supernatants obtained from cocultures of the CD4+ T cells with AuTu also induced proliferation of the CD8+ T cell line. In contrast, the H. saimiri-transformed CD8+ T cells did not kill AuTu or release cytokines in response to AuTu. However, upon pretreatment of AuTu with IFN-gamma to increase expression of MHC antigens, these T cells regained the ability to recognize and kill AuTu targets. Coincubation of AuTu with the CD4+ or CD8+ T cells significantly augmented expression of class I and II MHC antigens on AuTu. These data indicate that H. saimiri-transformed tumor-reactive T cell lines provide a useful model of interactions between immune effector cells and AuTu, and that CD4+ T cells play a critical role in the regulation of immune responses to squamous cell carcinoma of the head and neck.

CD4-Positive T-Lymphocytes↗
PubMed1997

Anterior decompression of foraminal stenosis below a lumbosacral transitional vertebra. A case report.

STUDY DESIGN: A case of unilateral far-out foraminal entrapment of the L5 spinal nerve below a transitional vertebra is presented with a review of the literature. OBJECTIVES: To describe management of a rare far-out foraminal stenosis below a transitional vertebra and to evaluate the surgical procedure and results. SUMMARY OF BACKGROUND DATA: Far-out foraminal stenosis with radiculopathy caused by bony spur formation secondary to anomalous articulation between the transverse process and the sacral ala is rarely reported. Decompression at this point traditionally has been performed through a posterior approach, similar to that performed for the far-out syndrome. There are no previous reports describing anterior decompression through an extraperitoneal approach. METHODS: The diagnosis was confirmed by computed tomography, magnetic resonance imaging, and selective radiculography. Anterior decompression was performed by resecting the bony spur using a wide muscle-splitting extraperitoneal approach. RESULTS: Anterior decompression was performed with minimal intervention to the spine and the trunk muscles. Good relief of low back pain and sciatica was obtained. CONCLUSIONS: Selective radiculography was the method of examination with the optimal diagnostic value for far-out foraminal stenosis. An anterior approach to the decompression of far-out foraminal stenosis below a lumbosacral transitional vertebra is a relatively simple and effective method.

Adult↗
PubMed1997

Enhancement of tissue-type plasminogen activator (t-PA) activity by purified t-PA receptor expressed in human endothelial cells.

We demonstrated previously that tissue-type plasminogen activator (t-PA) bound to its specific receptor (t-PAR) on human umbilical vein endothelial cells (HUVEC) in suspension and that t-PAR of mol wt. 20 kDa interacted only with t-PA to form 90 kDa complex (Fukao, H., Hagiya, Y., Nonaka, T., Okada, K., and Matsuo, O. (1992) Biochem. Biophys. Res. Commun. 187, 956-962). In the present study, 20 kDa t-PAR was purified from HUVEC and the function of the t-PAR was investigated by analyzing its effect on plasminogen activation by t-PA. About 2.2 microg t-PAR protein was purified from cell lysate of 1.0 X 10(9) HUVEC as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) by gel filtration with TSK-3000SW and reversed phase separation with high performance liquid chromatography (HPLC). 125I-t-PA but not 125I-plasminogen specifically bound to the purified t-PAR in ligand blot assay. Plasminogen activation by t-PA in the presence of purified t-PAR in solution was increased. Furthermore, t-PA bound to immobilized t-PAR efficiently expressed its plasminogen activation activity. Kinetic analysis revealed that t-PA in the presence of soluble t-PAR and t-PA bound to immobilized t-PAR exhibited 34- and 90-fold increase in plasminogen activation, respectively. The t-PAR did not interact with anti-annexin II antibody. These findings indicate that the 20 kDa t-PAR is a novel molecule which immobilizes t-PA and enhances its proteolytic activity on the cell surface of endothelial cells.

Cells, Cultured↗
PubMed1997

Protein kinase C and c-myc gene activation pathways in thrombopoietin signal transduction.

Thrombopoietin (TPO) is the major regulator of the proliferation and differentiation of megakaryocyte precursors through interaction with its receptor encoded by the c-mpl protooncogene. We established the human TPO-dependent leukemia cell line, UT-7/TPO (Blood 87, 4552, 1996). In these cells, TPO activated protein kinase C (PKC) in a time dependent manner. Subsequently, the c-myc gene was transiently induced to a maximal level 60-90 minutes after TPO exposure. In addition, we found that stimulating UT-7/TPO cells with TPO rapidly induces the significant accumulation of inositol 1, 4, 5-trisphosphate (Ins-P3), leading to the mobilization of calcium from intracellular stores. Taken together, the activation of PKC and subsequent c-myc gene induction are involved in the TPO-induced cellular response(s), presumably through the activation of PLC.

Calcium↗
PubMed1997

Cyclic thrombocytopenia in a patient treated with cyclosporine for refractory idiopathic thrombocytopenic purpura.

Cyclic thrombocytopenia (CT) is a rare disorder with cyclic changes of the platelet counts. Though the pathogenesis of this disorder has not been clarified, recent reports suggest that periodic destruction and/or ineffective production of platelets may be important causes of the disease. We report a case of a patient with refractory idiopathic thrombocytopenic purpura (ITP) in whom CT developed after cyclosporine A (CyA) therapy. There was an inverse relation between platelet counts and the serum levels of platelet-associated immunoglobulin G (PAIgG). The ploidy of bone marrow megakaryocytes also had an inverse relation with platelet counts. When the platelet count was low, the ploidy of megakaryocytes increased (P < 0.01). The number and area of bone marrow megakaryocytes were unrelated to platelet counts. These results indicate the possibility of platelet destruction caused by immunological mechanisms in CT. Cyclosporine A could have certain but fluctuating regulatory effects against antibody production for circulating platelets, which could lead to cyclic changes of the platelet counts. This case also suggests that CyA can be effective in severe refractory ITP. Regulatory mechanisms of platelet production and destruction and appropriate doses of CyA should be further studied in autoimmune-mediated thrombocytopenias.

Adult↗
PubMed1997

K-ras gene mutations in intrahepatic bile duct tumors of Syrian golden hamsters.

BACKGROUND AND OBJECTIVES: In our laboratory, we have developed a new model of carcinoma of the bile duct in Syrian golden hamsters, using N-nitrosobis(2-oxopropyl)amine (BOP). Morphologic and biologic characteristics of the carcinoma induced in this model are similar to those seen in humans. In order to examine the gene-related carcinogenesis of intrahepatic bile duct carcinoma, we investigated mutations in the K-ras gene in various early hyperplastic and neoplastic lesions of these hamsters, according to the original sites of the lesions. METHODS: Inbred female hamsters were given a subcutaneous injection of N-nitrosobis(2-oxopropyl)amine (BOP) following dissection of the extrahepatic bile duct on the distal end of the common duct and preparation of a cholecystoduodenostomy (CDDB) or simple laparotomy (SL). Neoplastic lesions arising from the intrahepatic bile duct were histologically examined, and K-ras mutations were investigated. RESULTS: Mutations of K-ras codon 12 were evident in 12% of tubular hyperplasias, 19% of tubular adenocarcinomas, 15% of papillary hyperplasias and 36% of papillary adenocarcinomas. In papillary adenocarcinoma arising from a large bile duct, K-ras mutations occurred more frequently than in tubular adenocarcinoma arising from ductule or ductular proliferation. K-ras mutations were present even in a hyperplasia; the positive rates of the mutations increased in the presence of a carcinoma. Genetic changes in carcinoma of the intrahepatic bile duct varied based on sites of the duct and the histological type. CONCLUSIONS: A part of the hyperplastic lesions of the intrahepatic bile duct presented K-ras gene mutation. This suggests that K-ras gene mutation is an early event in the carcinogenic process. In carcinoma of the intrahepatic bile duct, the lesion arising from a large bile duct of the hepatic hilum tended to exhibit a higher frequency of K-ras gene mutation than did a tubular lesion arising from ductule or ductal proliferation. This hamster model is useful to examine the carcinogenesis of human intrahepatic bile duct carcinoma.

Adenocarcinoma↗
PubMed1997

Osteogenic cell cytotoxicity and biomechanical strength of the new ceramic Diopside.

Diopside was prepared by sintering a powder compact composed of CaMgSi2O6 at 1573K for 2 h. In order to clarify the biocompatibility of Diopside, the cytotoxicity of Diopside against the osteogenic cell line MC3T3-E1 and the bone-Diopside interface strength were examined. On both the 14th and 21st days of incubation of MC3T3-E1 cells with Diopside, ALP activities were not significantly lower than those of the CTRL. TEM photographs of MC3T3-E1 on Diopside after 14 days of incubation showed active secretion of crystals from osteoblast-like cells. Scanning electron microscopic analysis showed that the cells on Diopside formed multiple cell layers similar to those on the CTRL both 14 and 21 days after incubation. These results showed that Diopside had no cytotoxic effect on MC3T3-E1. The pulling test showed that failure loads of Diopside were significantly lower than those of AWGC. Histologically, there was no fibrous tissue or foreign body reaction at the bone interface. SEM-EPMA showed that Diopside had attached to the bone via a calcium-phosphorus layer. SEM back-scattered electron imaging showed that the Diopside plate had degraded to a porous state 12 weeks after implantation. These findings indicate that Diopside is a biodegradable ceramic.

3T3 Cells↗