Biomedical subjects

K Okamoto

Publications and source records attributed to K Okamoto.

At least 73 records · Page 4Linked to original sources

PubMed2001

Mononuclear platinum(II) complex with 2-phenylpyridine ligands showing high cytotoxicity against mouse sarcoma 180 cells acquiring high cisplatin resistance.

Mouse sarcoma 180 cell with a 25-fold higher cisplatin (CDDP) resistance, termed S-180cisR, is newly established. S-180cisR cells grow quite slowly in the presence of CDDP with high concentration. This may show that S-180cisR cells modulate the cell cycle to acquire CDDP resistance. P-Glycoprotein is selectively expressed on the surface of S-180cisR, which is not on CDDP-sensitive S-180 parent cells. In an experiment using an inhibitor (verapamil) of P-glycoprotein, cytotoxicity of CDDP against S-180cisR is significantly increased (viz., IC(50) value is decreased) and accumulation of CDDP in S-180cisR cells is also increased. These results indicate that enhanced pumping-out of CDDP by P-glycoprotein should be one of the reasons for the CDDP resistance of S-180cisR. A platinum(II) complex with a cyclometalated 2-phenylpyridine ligand and a nonchelated one (complex 5) is synthesized, and its structure is determined by X-ray structural analysis. Complex 5 has a cyctotoxicity against S-180cisR higher than that of CDDP and its derivatives with 2- or 3-substituted pyridine ligands (complexes 2-4, 6, 7). Complex 5 is incorporated in S-180cisR to an enormously greater extent than CDDP; that is, the ratio of accumulated platinum amount after 3 h is 61.9. In S-180 parent cells, on the other hand, the ratio remains 8.1. This high accumulation of complex 5 into S-180cisR must account for the higher activity of complex 5 against S-180cisR compared to CDDP.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2001

anti-bis(mu-2-ammonioethanethiolato-kappa2S:S)bis[dichloropalladium(II)] dihydrate.

Each of two square-planar Pd(II) ions in the title compound, [Pd2Cl4(mu-Haet-S)2]*2H2O (Haet = 2-ammonioethanethiolate, C2H7NS), which was obtained by rearrangement of [Pd2[Pd(aet-N,S)2]4]4+ in acidic solution, is coordinated by two bridging S atoms from two Haet ligands and by two terminal Cl atoms, forming the dinuclear structure. Since the complex is situated on a center of symmetry, the two monodentate Haet arms are located on opposite sides of the central Pd2S2 square plane, i.e. the present complex is the anti isomer. The S-C-C-N torsion angle is 177.3 (6) degrees and some intermolecular hydrogen bonds are observed.

Journal Article↗

PubMed2001

Novel and simple two-step purification of a full-length rat glucocorticoid-receptor expressed in a baculovirus system.

We purified the activated recombinant glucicorticoid receptor (GR) overexpressed in insect cells by sequential chromatographies using Mono Q and Mono S columns. This procedure was based upon a new finding that the activated GR binds both to a Mono Q column and to a Mono S column at the same pH (pH 8.4). The entire chromatographies took about 3 h and GR represented 97% of the purified protein sample. The purified GR was able to bind specifically to a DNA fragment containing the glucocorticoid response element. This purification protocol will be applicable to the purification of native GR, point-mutated recombinant GR and other nuclear receptors.

Animals↗

PubMed2001

Menstrual and reproductive factors for subarachnoid hemorrhage risk in women: a case-control study in nagoya, Japan.

BACKGROUND AND PURPOSE: We sought to examine the relationship between menstrual and reproductive factors and the risk of subarachnoid hemorrhage (SAH), using a case-control study. METHODS: Cases consisted of a consecutive series of 124 women patients with first spontaneous SAH aged 30 to 79 years and confirmed aneurysm(s) by angiography and/or CT scan. Hospital and community controls subjects were identified, matched to each case by age (+/-2 years). RESULTS: Increased SAH risk was associated with (1) earlier age at menarche (adjusted odds ratio [OR]=3.24 for age <13 years compared with age >/=13 years; 95% CI, 1.25 to 4.03) and (2) nulligravidity (adjusted OR=4.23; 95% CI, 1.05 to 7.56). No significant association of SAH risk was found with regularity of menstrual cycle, age at pregnancy, age at first birth, and number of births. The greatest risk was for the combined effect of nulligravidity and earlier menarche (<13 years) (adjusted OR=6.37; 95% CI, 1.12 to 36.2). CONCLUSIONS: The combined effect of several variables related to menstrual and reproductive history may exert a greater influence on risk of SAH compared with a single menstrual or reproductive variable.

Adult↗

PubMed2001

Functional modulation of the glucocorticoid receptor and suppression of NF-kappaB-dependent transcription by ursodeoxycholic acid.

Ursodeoxycholic acid (UDCA) is the current mainstay of treatment for various liver diseases including primary biliary cirrhosis. UDCA acts as a bile secretagogue, cytoprotective agent, immunomodulator, and inhibitor of cellular apoptosis. Despite this cumulative evidence of the cytoprotective and immunosuppressive effects of UDCA, both the target molecule and pathway of UDCA action remain unknown. We previously described that, in the absence of glucocorticoid ligand, UDCA activates the glucocorticoid receptor (GR) into DNA binding species but does not elicit its transactivational function in a transient transfection assay. Here we further studied the molecular mechanism of UDCA action and revealed that the ligand binding domain of the GR is responsible for UDCA-dependent nuclear translocation of the GR. Indeed, we demonstrated that UDCA acts on the distinct region of the ligand binding domain when compared with the classical GR agonist dexamethasone, resulting in loss of coactivator recruitment and differential regulation of gene expression by the GR. Our data clearly indicated that UDCA, at least in part via activation of the GR, suppresses NF-kappaB-dependent transcription through the intervention of GR-p65 interaction. Together with the established clinical safety of UDCA, we may propose that UDCA could be a prototypical compound for development of a novel and selective GR modifier.

Active Transport, Cell Nucleus↗

PubMed2001

Combination therapy with transcatheter arterial chemoembolization and percutaneous ethanol injection compared with percutaneous ethanol injection alone for patients with small hepatocellular carcinoma: a randomized control study.

BACKGROUND: To assess whether the effectiveness of a combination of transcatheter arterial chemoembolization (TACE) and percutaneous ethanol injection (PEI) is superior to PEI alone in the treatment of patients with small hepatocellular carcinoma (HCC), a randomized controlled study was performed. METHODS: Fifty-two patients with one to three HCC tumors measuring < than 3 cm in greatest dimension were enrolled and underwent the combination TACE-PEI therapy (26 patients with 31 nodules) or PEI alone (26 patients with 34 nodules). There were no significant differences in background between the two groups. The mean follow-up was 30.1 months +/- 17.5 months. RESULTS: The cumulative detection rates of local residual disease in the TACE-PEI group (3.7% at 1 year and 19.3% at 3 years) were significantly lower compared with the detection rates in the PEI alone group (34.2% and 39.3%, respectively; P = 0.013). The cumulative new nodular recurrence rates in the TACE-PEI group (8.7% at 1 year and 19.3% at 3 years) tended to be lower compared with the recurrence rates in the PEI alone group (26.9% and 80.1%, respectively; P = 0.057). The cumulative survival rates were not significantly different between the two groups (TACE-PEI group: 100%, 80.8%, and 40.4% at 1 year, 3 years, and 5 years, respectively; PEI alone group: 91.3%, 65.9%, and 37.7%, respectively; P = 0.458). However, among the patients from each group with HCC tumors measuring < 2 cm, the survival rates in the TACE-PEI group were improved compared with the survival rates in the PEI alone group (P < 0.01) in addition to the detection rates of local residual disease and the new nodular recurrence rates (P < 0.01 and P = 0.047, respectively). The frequency of short-term and long-term adverse effects was not significantly different between the groups. However, only two major complications (biloma and ascites with pleural effusion) were observed, both of which occurred in patients in the TACE-PEI group. CONCLUSIONS: Combination therapy with TACE-PEI was superior to PEI alone in the treatment of patients with small HCC tumors, especially for patients with HCC tumors measuring < 2 cm in greatest dimension.

Aged↗

PubMed2001

Suppressive effect of irsogladine maleate on N-methyl-N-nitro-N-nitrosoguanidine (MNNG)-initiated and glyoxal-promoted gastric carcinogenesis in rats.

The modifying effect of irsogladine maleate (IRG) on N-methyl-N-nitro-N-nitrosoguanidine (MNNG)-initiated and glyoxal-promoted gastric carcinogenesis was examined in male Wistar rats. Six-week-old rats were divided into ten groups. Groups 1 through 6 were given MNNG (100 mg/l in drinking water) for 25 weeks from the start of the experiment, whereas groups 7 through 10 received distilled water in the initiation phase as the vehicle treatment. Groups 1 and 8 were kept on the basal diet and distilled water throughout the experiment (55 weeks). Groups 2-8 were given 0.5% glyoxal in the drinking water for 30 weeks from 26th week of the experiment. Group 3 was fed the diet mixed with 100 ppm IRG for 25 weeks from the start of experiment. Groups 4 and 8 were fed the diet mixed with 100 ppm IRG for 30 weeks from 26th week of experiment. Groups 5 and 9 or 6 were given 100 or 25 ppm IRG containing diet, respectively throughout the experiment. Group 10 was given the basal diet and distilled water as the vehicle treated control. Tumors of upper digestive tracts (stomach and duodenum) were developed in groups: 1 (12/17 rats, 71%), 2 (11/12 rats, 92%), 3 (9/16 rats, 56%), 4 (5/12 rats, 42%), 5 (6/15 rats, 40%) and 6 (7/12 rats, 58%). High dose of IRG in initiation and/or promotion phase significantly reduced the incidence of tumors of the upper digestive tracts. The average numbers of the digestive tracts neoplasms in groups 3,5 and 6 given glyoxal and IRG were less than those in group 2 which received only glyoxal. These results suggest that IRG could be a preventive agent against the occurrence of neoplasms of the upper digestive tract.

Animals↗

PubMed2001

Definition of a dioxin receptor mutant that is a constitutive activator of transcription: delineation of overlapping repression and ligand binding functions within the PAS domain.

The intracellular dioxin (aryl hydrocarbon) receptor is a ligand-activated transcription factor that mediates the adaptive and toxic responses to environmental pollutants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin and structurally related congeners. Whereas the ligand-free receptor is characterized by its association with the molecular chaperone hsp90, exposure to ligand initiates a multistep activation process involving nuclear translocation, dissociation from the hsp90 complex, and dimerization with its partner protein Arnt. In this study, we have characterized a dioxin receptor deletion mutant lacking the minimal ligand-binding domain of the receptor. This mutant did not bind ligand and localized constitutively to the nucleus. However, this protein was functionally inert since it failed to dimerize with Arnt and to bind DNA. In contrast, a dioxin receptor deletion mutant lacking the minimal PAS B motif but maintaining the N-terminal half of the ligand-binding domain showed constitutive dimerization with Arnt, bound DNA, and activated transcription in a ligand-independent manner. Interestingly, this mutant showed a more potent functional activity than the dioxin-activated wild-type receptor in several different cell lines. In conclusion, the constitutively active dioxin receptor may provide an important mechanistic tool to investigate receptor-mediated regulatory pathways in closer detail.

Animals↗

PubMed2001

[A family with multiple thrombosis including infancy occurrence].

Since the first patient with antithrombin deficiency was reported, various hereditary thrombophilia have been discovered. However, we experienced a family line of multiple thrombosis in which known hereditary thrombophilia were all refuted. Case 1 died of inferior vena cava thrombosis at the age of 56 days. Case 2, the elder sister of Case 1, developed deep vein thrombosis of the left leg at age 2. She was started on warfarin but contracted deep vein thrombosis of the right leg at the age of 7. In the family of these cases there have been another five cases of thrombosis, spanning three generations, giving a total of seven cases. Six of the cases developed at an early age, below 50 years. Antithrombin, protein C, protein S, heparin cofactor II, soluble thrombomodulin, plasminogen, alpha 2 plasminogen inhibitor, and tissue factor pathway inhibitor were measured but there were no abnormalities, nor was there any resistance to activated protein C. The onset of thrombosis in this family is becoming younger with the passing of generations, and clinical symptoms have been showing a worsening tendency.

Age Factors↗

PubMed2001

Movement of endoplasmic reticulum in the living axon is distinct from other membranous vesicles in its rate, form, and sensitivity to microtubule inhibitors.

The endoplasmic reticulum (ER) is the major membranous component present throughout the axon. Although other membranous structures such as synaptic vesicles are known to move via fast axonal transport, the dynamics of ER in the axon still remains unknown. To study the dynamics of ER in the axon, we have directly visualized the movement of two ER-specific membrane proteins, the sarcoplasmic/endoplasmic reticulum calcium-ATPase and the inositol 1,4,5-trisphosphate receptor, both of which were tagged with green fluorescence protein (GFP) and expressed in cultured chick dorsal root ganglion neurons. In contrast to GFP-tagged synaptophysin that moved as vesicles at 1 microm/sec predominantly in the anterograde direction in the typical style of fast axonal transport, the two ER proteins did not move in a discrete vesicular form. Their movement determined by the fluorescence recovery after photobleaching technique was bi-directional, 10-fold slower (approximately 0.1 microm/sec), and temperature-sensitive. The rate of movement of ER was also sensitive to low doses of vinblastine and nocodazole that did not affect the rate of synaptophysin-GFP, further suggesting that it is also distinct from the well-documented movement of membranous vesicles in its relation with microtubules.

Animals↗

PubMed2001

Pathological study of the diffuse myelin pallor in the anterolateral columns of the spinal cord in amyotrophic lateral sclerosis.

An immunohistochemical study using a monoclonal antibody against macrophage (Ki-M1p) was performed to examine which fiber tracts are affected in the spinal cords and brainstems of ALS patients. In 21 out of 30 ALS patients, various degrees of macrophage infiltration were observed diffusely in the anterolateral columns beyond the corticospinal tracts. On the other hand, a few macrophages were scattered in 20 non-ALS patients in the anterolateral columns outside the corticospinal tracts. In ALS brainstems, the macrophages were mainly localized in the corticospinal tracts. The result suggests that the diffuse myelin pallor in the anterolateral columns beyond the corticospinal tracts may be derived from intrinsic spinal cord lesions. Quantitative investigation using a monoclonal antibody against phosphorylated neurofilaments (SMI-31) revealed that the decrease in the numbers of small fibers would induce the diffuse myelin pallor in anterolateral columns of ALS patients. From these findings, we propose that the propriospinal bundles are candidates for the degenerating fibers in the anterolateral columns of ALS.

Adult↗

PubMed2001

Development of the polymer micelle carrier system for doxorubicin.

We show the result of pre-clinical study of NK911, a polymeric micelle carrier system for doxorubicin (DOX). The NK911 micelle carrier consists of polyethyleneglycol and conjugated doxorubicin-polyaspartic acid. It has high hydrophobic inner core, and therefore can entrap the sufficient amount of DOX. NK911 has a small particle size of about 40 nm in diameter that accumulates in tumor tissue by EPR effect showing much stronger activity than the free DOX. We plan to perform a clinical trial at National Cancer Center Hospital, Japan from 2001.

Animals↗

PubMed2001

A mouse model for adenovirus gene delivery.

The cellular attachment receptor for adenovirus (Ad), Coxsackie adenovirus receptor (CAR), required for delivery of Ad into primary cells, is not present on all cell types, thus restricting Ad-gene delivery systems. To circumvent this constrain, a transgenic mouse has been generated that expresses a truncated human CAR in all tissues analyzed. These mice allowed efficient in vitro infections at low multiplicities into lymphoid, myeloid, and endothelial cells. Furthermore, in vivo administration of Ad-vectors results in infection of macrophages, lymphocytes, and endothelial cells. In addition, tail vein injection resulted in targeting of virus into previously inaccessible areas, such as the lung and the capillaries of the brain. The CAR transgenic mice will be useful for rapid functional genomic analysis in vivo, for testing the efficacy of gene therapy procedures or as a source of easily transducible cells.

Adenoviridae↗

PubMed2001

Adenovirus-mediated transfer of p53 augments hyperthermia-induced apoptosis in U251 glioma cells.

PURPOSE: Hyperthermia kills glioma cells by inducing apoptosis and is thereby an effective therapeutic modality for the treatment of malignant gliomas. However, cells harboring mutated p53 are refractory to hyperthermia-induced apoptosis. In this study, we assessed whether or not adenovirus (Adv)-mediated transduction of p53 overrides this resistant mechanism. METHODS AND MATERIALS: We transduced the p53 wild-type tumor suppressor gene into U251 glioma cells harboring mutated p53 using Adv vectors in combination with hyperthermia (43, 44.5 degrees C), and evaluated the degree of cell death and apoptosis. RESULTS: The percentage of cells that had died, as measured by trypan blue staining, among U251 cells infected with the Adv for p53 (Adv-p53) and treated with hyperthermia, was significantly higher than the percentage of cells that had died among U251 cells infected with Adv-p53 and not treated with hyperthermia, or those infected with the control Adv for dE (Adv-dE) and treated with hyperthermia. The degree of apoptosis, measured at 24 h after treatment, in hyperthermia-treated U251 cells infected with Adv-p53 (43 degrees C, 73%; 44.5 degrees C, 92%) was much higher than that infected with Adv-p53 (41%), or that infected with control Adv-dE and treated with hyperthermia (43 degrees C, 1.3%; 44.5 degrees C, 19%). Treatment with combined hyperthermia and Adv-p53 infection induced cleavage of caspase-3 in U251 cells. CONCLUSION: These results indicate that Adv-mediated transduction of p53 would render glioma cells highly sensitive to hyperthermia.

Adenoviridae↗

PubMed2001

fac-Trichloro(quinolin-8-ylimido-N,N')(triphenylphosphine-P)rhenium(V).

The Re atom in [Re(C(9)H(6)N(2))Cl(3)(C(18)H(15)P)] is octahedrally coordinated by three Cl atoms in facial positions, two N atoms from 8-imidoquinoline (imq) and one P atom from triphenylphosphine. The Re-N(imido) distance [1.760 (9) and 1.772 (8) A] for imq is very short and implies double-bond character. The trans influence of the P atom is indicated. Intra- and intermolecular pi-pi interactions between the pi-rings in the complex are also observed.

Journal Article↗

PubMed2001

Prognostic significance of combined conventional and immunocytochemical cytology for peritoneal washings in endometrial carcinoma.

BACKGROUND: Noncancerous cells simulating adenocarcinoma cells may interfere with the analysis of peritoneal cytology (PC) in patients with endometrial carcinoma. Immunocytochemistry (ICC) may improve the diagnosis of PC. METHODS: PC slides from 115 patients with endometrial carcinoma were reviewed. Suspicious or positive cell clusters were recovered with a cell transfer method and were subjected to ICC for MOC-31, cytokeratin 5/6, and p53. Conventional Papanicolaou staining and ICC results were compared directly on the same cells. RESULTS: By combined conventional and immunocytochemical PC (CONV-ICC-PC), cytodiagnosis was positive in 18 of 115 patients (15.7%) and suspicious in 3 of 115 patients (2.6%). According to a multivariate Cox regression analysis of patients with tumors confined to the uterus that included grade, myometrial invasion, cervical involvement, and CONV-ICC-PC, only CONV-ICC-PC was an independent prognostic factor (P < 0.05). A multivariate analysis for all of the patients studied that compared CONV-ICC-PC with staging variables revealed that only peritoneal metastasis (P < 0.0001) and lymph node metastasis (P < 0.01) were independent prognostic factors. When peritoneal metastases were excluded, CONV-ICC-PC (P < 0.01) and lymph node metastasis (P < 0.0025) were the independent prognostic factors. By cell transfer and p53 immunostaining in samples from 14 patients with malignant cells in their peritoneal washings, no deaths occurred among 5 patients with negative p53, whereas 5 of 9 patients with positive p53 died of disease at the time of data analysis. CONCLUSIONS: MOC-31 immunostaining improves the diagnosis of PC in endometrial carcinoma. Positive PC is an important prognostic factor for patients with endometrial carcinoma confined to the uterus. The p53 positive cells in PC have possible prognostic significance.

Adult↗

PubMed2001

Replication and preferential inheritance of hypersuppressive petite mitochondrial DNA.

Wild-type yeast mitochondrial DNA (mtDNA) is inherited biparentally, whereas mtDNA of hypersuppressive petite mutants is inherited uniparentally in crosses to strains with wild-type mtDNA. Genomes of hypersuppressive petites contain a conserved ori sequence that includes a promoter, but it is unclear whether the ori confers a segregation or replication advantage. Fluorescent in situ hybridization analysis of wild-type and petite mtDNAs in crosses reveals no preferential segregation of hypersuppressive petite mtDNA to first zygotic buds. We identify single-stranded DNA circles and RNA-primed DNA replication intermediates in hypersuppressive petite mtDNA that are absent from non-hypersuppressive petites. Mutating the promoter blocks hypersuppressiveness in crosses to wild-type strains and eliminates the distinctive replication intermediates. We propose that promoter-dependent RNA-primed replication accounts for the uniparental inheritance of hypersuppressive petite mtDNA.

DNA Replication↗

PubMed2001

Characterization of ruthenium-dinitrogen tetraamine complexes by XAFS spectroscopy.

A reaction between N2 and trans-Ru(II)Cl2L (L=2,5,9,12-tetramethyl-2.5,9,12-tetraazatridecane) in aqueous solutions has been investigated by XAFS spectroscopy. Ru K-edge EXAFS clearly revealed that there exists an N2-bridged binuclear complex and that the Ru-Ru distance is 4.96 A with the coordination number of 0.5. The Ru K-edge energies of the N2 complexes are closer to that of Ru(III)Cl2L+ rather than that of Ru(II)Cl2L, indicating back donation from the Ru dpi to the N2 pi* orbitals.

Journal Article↗