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Biomedical subjects

M Okazaki

Publications and source records attributed to M Okazaki.

At least 217 records · Page 12Linked to original sources
PubMed1997

Partial purification and characterization of manganese-oxidizing factors of Pseudomonas fluorescens GB-1.

The Mn(2+)-oxidizing bacterium Pseudomonas fluorescens GB-1 deposits Mn oxide around the cell. During growth of a culture, the Mn(2+)-oxidizing activity of the cells first appeared in the early stationary growth phase. It depended on the O2 concentration in the culture during the late logarithmic growth phase. Maximal activity was observed at an oxygen concentration of 26% saturation. The activity could be recovered in cell extracts and was proportional to the protein concentration in the cell extracts. The specific activity was increased 125-fold by ammonium sulfate precipitation followed by reversed-phase and gel filtration column chromatographies. The activity of the partly purified Mn(2+)-oxidizing preparation had a pH optimum of circa 7 and a temperature optimum of 35 degrees C and was lost by heating. The Mn(2+)-oxidizing activity was sensitive to NaN3 and HgCl2. It was inhibited by KCN, EDTA, Tris, and o-phenanthroline. Although most data indicated the involvement of protein in Mn2+ oxidation, the activity was slightly stimulated by sodium dodecyl sulfate at a low concentration and by treatment with pronase and V8 protease. By polyacrylamide gel electrophoresis, two Mn(2+)-oxidizing factors with estimated molecular weights of 180,000 and 250,000 were detected.

Bacterial Proteins↗
PubMed1997

Expression of genes encoding membrane-bound hydrogenase in Pseudomonas hydrogenovora under autotrophic condition is dependent on two different promoters.

Expression of a membrane-bound hydrogenase of the hydrogen-utilizing bacterium Pseudomonas hydrogenovora was induced specifically in autotrophic condition. Dot blot and primer extension analysis showed that the transcription of the hydrogenase gene started from the region upstream of a hydrogenase structural gene, hupS, which contained three putative sigma54-type promoter sequences (Phup1, Phup2, and Phup3). The lacZ-fusion analysis of the hupS-upstream region combined with site-directed mutagenesis showed that Phup1 and Phup3 would be essential for a transcriptional initiation. It was also found that the region upstream of Phup sequences was concerned with regulation of transcription.

Base Sequence↗
PubMed1997

Characterization of 50wt%SiO2-20wt%P2O5-30wt%CaO glass-ceramic powders prepared by the sol-gel process.

Glass-ceramic powders with the oxide batch formulation 50wt%SiO2, 20wt%P2O5 and 30wt%CaO were prepared by the sol-gel process using tetraethoxysilane, calcium nitrate and phosphoric acid as raw materials. The obtained gels and powders were characterized by TG-DTA thermal analysis, FTIR analyses and XRD measurements. The results indicated that (1) heating to more than 600 degrees C brought about elimination of -OC2H5 side chains from gels, and formation of a SiO2-based glass network, (2) crystallization such as Ca3(PO4)2 notably occurred in the SiO2-based glass matrix when heated to more than 900 degrees C, (3) -OH groups existed on SiO2-based glass-ceramic surfaces in the temperature region less than 900 degrees C, and (4) the melting point of this composition was more than 1400 degrees C. This study suggests that sol-gel-derived SiO2-based glass-ceramic powder containing P and Ca might be useful as bioactive implant materials.

Calcium Compounds↗
PubMed1997

Blood coagulability and fibrinolysis in streptozotocin-induced diabetic rats.

Changes in coagulation and fibrinolysis in the plasma (in vivo) and hepatocytes (ex vivo) were studied using hyperglycemic rats. Hyperglycemia was induced by intravenous injection of 50 mg/kg streptozotocin (STZ). Eight weeks after the injection, we observed increases in thrombin-antithrombin III complex and tissue type plasminogen activator activity, decreases in plasma levels of antithrombin III, plasminogen and alpha2-plasmin inhibitor, and significant shortening of activated partial thromboplastin time. In freshly isolated or cultured hepatocytes from STZ-induced hyperglycemic rats, concentrations of proteins related to coagulation were increased. An increase in alanine-aminotransferase leakage and decreases in the levels of amylase, triglycerides and phospholipids were observed in the culture medium of hepatocytes from STZ treated rats. In vivo study revealed that STZ-induced subchronic diabetes induced imbalance between coagulation and fibrinolysis, and ex vivo study in hepatocytes from STZ-treated rats showed membrane degeneration and reduction in amylase synthesis, while protein synthesis related to coagulation was not inhibited. These results suggest that, despite vulnerability of liver cells from STZ treated rats, coagulation activity in the liver is retained and rather enhanced in STZ-induced hyperglycemic rats, which may contribute to the promotion of atherosclerosis.

Animals↗
PubMed1997

[A study on clinical teaching method in nursing education--focusing on teaching method of touching].

The purpose of this study is the development of effective clinical teaching methods of nursing education using touching in hospital nursing care. The clinical teaching-learning process was designed based on the Steinaker, N.W. & R. Bell's experiential learning model (1979), in which teaching-learning process was divided into five steps-exposure, participation, identification, internalization, and dissemination. Three hypotheses were postulated as follows: 1-1. Guidance given to nursing students to use touching in nursing care will make them conscious of the efficiency of touching. 1-2. Nursing students will grasp the efficiency of their nursing action by "cause and effect" relations. 2-0. Guidance given to nursing students to use touching in their nursing care will allay and soften their anxiety and tension toward such nursing practices. 3-0. Nursing intervention by touching will heighten the clinical judgement ability of nursing students. The teaching-learning plan was carried out in a nursing school in Kitakyushu-shi. Fifteen nursing students studied by this plan. The results was as follows: a. Hypotheses 1-1, 1-2, 2-0, were confirmed. b. Hypothesis 3-0, was not confirmed.

Clinical Competence↗
PubMed1997

Heterogeneous fluoridated hydroxyapatites partially substituted with fluoride ions.

The partially substituted fluoridated apatites H-FHAp0.5 and FH-HAp0.5 were synthesized heterngeneously by supplying fluoride at a concentration equivalent to half of the maximum value of fluorapatite during the initial or final half of the experimental period. Although X-ray diffraction patterns and SEM photos of H-FHAp0.5 and FH-HAp0.5 apatites were not significantly different, high-resolution electron microscopy showed quite different features; H-FHAp0.5 type apatite was an elongated hexagon with electron beam damage in the core, and FH-HAp0.5 type apatite was a rather wide hexagon analogous to fluorapatite. Energy dispersive spectroscopy attached to the SEM showed H-FHAp0.5 apatite to have a higher fluoride peak intensity than FH-HAp0.5. These results supported the previous speculations on the two different types of heterogeneous fluoridated hydroxyapatites: hydroxyapatite covered with fluorapatite and fluorapatite coverted with hydroxyapatite.

Crystallization↗
PubMed1997

Evaluation of precipitation and direct methods for HDL-cholesterol assay by HPLC.

HDL-cholesterol (HDL-C) values measured by precipitation (sodium phosphotungstate-MgCl2) and direct methods were compared with those obtained by HPLC with a new column (TSKgel Lipopropak) and an eluent (TSKeluent LP-1). The HDL-C values determined by the precipitation method were significantly (P <0.001) lower than those by the HPLC method, whereas the HDL-C values by the direct method were slightly but significantly higher (P <0.02) than those by the HPLC method. A quantitative HPLC analysis of the cholesterol concentration in HDL and non-HDL fractions in the supernatant of serum separated by precipitation reagents with different MgCl2 concentrations ranging from 7.3 to 44 mmol/L revealed that reagents with >22 mmol/L MgCl2 precipitated part of HDL as well as non-HDL lipoproteins. The HPLC method providing quantitative and qualitative information with high precision was regarded as being a reliable approach for HDL-C assay. The HPLC can be also used to evaluate alternative methods for cholesterol assay.

Chemical Precipitation↗
PubMed1997

[A case report of Vp3 hepatocellular carcinoma responding to multidisciplinary treatment].

We report a 60-year-old man who had hepatocellular carcinoma with tumor thrombus in the main portal vein and left portal branch (VP3HCC). He was treated with transarterial chemo-embolization, surgical resection and intra-arterial infusion chemotherapy. He is now surviving without any sign of recurrence for 12 months after the initial therapy, even though the prognosis of VP3HCC is poor. This is a case in which the effect of multidisciplinary treatment was indicated.

Antibiotics, Antineoplastic↗
PubMed1996

Molecular epidemiology of breast cancers in northern and southern Japan: the frequency, clustering, and patterns of p53 gene mutations differ among these two low-risk populations.

Comparison of acquired mutations in the p53 tumor suppressor gene can illuminate factors contributing to carcinogenesis among cancer cohorts. Japan has an ethnically homogeneous population with a low incidence of breast cancer. Previously we reported an unusual frequency, allelic status, and clustering of mutations in breast cancers from the northern part of the main Japanese island. To extend these findings, exons 2-11 and adjacent intronic sequences were analysed in tumors of women from northern (Hokkaido) and southern (Tokushima) Japan. The frequency of breast cancers with p53 gene mutations in the Hokkaido group is the highest reported (81%) while that in Tokushima (28%) is similar to most other populations. Thirteen of the 19 mutations (68.4%) in the Hokkaido cohort were heterozygous, an unusually high frequency for p53 mutations in any tumor type. There were three missense mutations at codon 175, a known hotspot for alterations in the p53 gene, and three missense mutations at codon 179, a rare site for p53 changes. In addition, the patterns of p53 gene mutation differed between the two Japanese cohorts (P=0.04). The multiple differences in acquired p53 mutations suggest unsuspected biological differences among breast cancers in northern and southern Japan. In addition, the high frequency of p53 mutations in breast cancers from Hokkaido predicted a poorer prognosis for this population which was confirmed on examination of mortality data.

Adult↗
PubMed1996

Tyrosine dephosphorylation of glycogen synthase kinase-3 is involved in its extracellular signal-dependent inactivation.

We examined whether extracellular signals regulate glycogen synthase kinase-3 (GSK-3) activity through tyrosine dephosphorylation of GSK-3. In resting Chinese hamster ovary cells overexpressing the human insulin receptor (CHO-IR cells), GSK-3 was tyrosine-phosphorylated and active. Insulin and 12-0-tetradecanoylphorbol 13-acetate (TPA) induced inactivation and tyrosine dephosphorylation of GSK-3. It is known that Ser-9 of GSK-3beta is phosphorylated in response to insulin and that the phosphorylation of this amino acid residue causes inactivation of GSK-3beta. However, the ectopically expressed GSK-3beta(delta9), in which the N-terminal nine amino acids of GSK-3beta were deleted, was still inactivated and tyrosine-dephosphorylated in response to insulin. Protein phosphatase 2A treatment partially reversed insulin-induced GSK-3beta inactivation, but did not change GSK-3beta(delta9) inactivation. In CHO-IR cells where protein kinase C was down-regulated, TPA neither inactivated nor tyrosine-dephosphorylated GSK-3. However, insulin inactivated and tyrosine-dephosphorylated GSK-3, although to a lesser degree than in the control cells. These results suggest that in addition to serine phosphorylation, tyrosine dephosphorylation of GSK-3 is also important for the regulation of GSK-3 activity in response to extracellular signals and that insulin regulates GSK-3 activity through both protein kinase C-dependent as well as protein kinase C-independent pathways.

Amino Acid Sequence↗
PubMed1996

Differences in hypervariable region 1 quasispecies of hepatitis C virus between human serum and peripheral blood mononuclear cells.

The complexity of hypervariable region 1 (HVR1) quasispecies of hepatitis C virus (HCV) in serum and peripheral blood mononuclear cells (PBMCs) was assessed at several time points in 11 patients with chronic hepatitis C. Polymerase chain reaction and single-strand conformation polymorphism analysis revealed that four patients (36%) showed serial changes in the complexity of HVR1 quasispecies, which were identical in both serum and PBMCs; two patients (18%) showed both serial changes in quasispecies and differences in quasispecies between serum and PBMCs; and five patients (45%) showed neither serial changes in nor quasispecies differences between serum and PBMCs. These results demonstrate both the existence of different quasispecies between serum and PBMCs and the infection of PBMCs by HCV.

Adult↗
PubMed1996

Localization and ontogeny of GLUT3 expression in the rat retina.

This study investigates the presence, localization, and developmental expression of a neuron-specific facilitated-diffusion glucose transporter, GLUT3, in the rat retina so as to elucidate molecular mechanisms regulating glucose homeostasis in support of the visual function. Immunoblot analysis using anti-GLUT3 antibody (ALM3-C) revealed the presence of GLUT3 as a heterogeneously glycosylated protein with an average molecular weight of approximately 44 kDa. Although immunofluorescence staining showed it to be localized primarily in the inner and outer plexiform layers, some of the cell bodies in the inner nuclear layer also showed weak immunoreactivity. Immunoblot analysis of developing rat retinal tissues revealed the presence of the GLUT3 protein as early as embryonic day 15 (E15), and immunofluorescence staining revealed its expression in the inner plexiform layer near the time of birth and in the outer plexiform layer at postnatal day 14 (P14), i.e., when the eyes normally open and retinal activity commences. The protein's abundance remained at a relatively low level during the embryonic stages and up until the end of the first postnatal week (P7), though a transient increase was confirmed to occur at E18. From P13, however, the abundance steadily increased, rapidly reaching the adult level at P24. Based on these observations, we hypothesize that GLUT3 is expressed in some subsets of retinal neurons, being preferentially abundant in their neuronal processes, and that its ontogeny is closely associated with morphological and functional development of the retina. As such, this suggests that GLUT3 plays some important role(s) in the retina where glucose metabolism is essential.

Animals↗
PubMed1996

Expression of alpha 1 adrenergic receptor subtype mRNAs in the rat cardiovascular system with aging.

Alpha 1 adrenoreceptors mediate inotropic and chronotropic responses in the heart and vaso-constriction in blood vessels. Pharmacological studies using selective antagonists for subtypes of alpha 1 receptor suggest that different receptor subtypes may mediate different physiological effects. Prior studies have demonstrated that alpha 1-mediated cardiac responses are altered in aging and that alpha 1 receptor number declines with age in the rat heart. The distribution of alpha 1 receptor subtypes in cardiac tissue and subtype-specific changes with aging, however, have not been established. Using R Nase protection assays and in situ hybridization techniques, we have detected message for alpha 1B, alpha 1A, and alpha 1D in all four chambers of the rat heart and in multiple blood vessels. We found no significant changes in alpha 1 receptor subtype mRNA levels in hearts from young (4 months) and old (25 months) Sprague-Dawley rats. Also, there was expression of these three subtypes in all blood vessels assayed. We conclude that transcriptional regulation of alpha 1 adrenoreceptor subtypes does not account for age-related changes in cardiac alpha-adrenergic responsiveness.

Aging↗
PubMed1996

Activation of heat shock protein (hsp)70 and proto-oncogene expression by alpha1 adrenergic agonist in rat aorta with age.

Induction of heat shock proteins (hsp) most likely is a homeostatic mechanism in response to metabolic and environmental insults. We have investigated signal transduction mechanisms involved in alpha1, adrenergic receptor stimulation of hsp7O gene expression in isolated aortas with age. We found that alpha1 adrenergic agonists directly induced hsp70 mRNA in rat aorta in vitro; the alpha1, selective antagonist prazosin blocked this effect whereas chloroethylclonidine, an antagonist which has some selectivity for alpha1B receptors, was ineffective. This response was insensitive to pertussis toxin and was partially blocked by the protein kinase C inhibitor H7. Removal of extracellular calcium attenuated induction of hsp70 mRNA but not the induction of c-fos or c-myc. The induction of hsp70 mRNA by either norepinephrine or by phorbol dibutyrate was blunted in aortas from old (24-27 mo) rats whereas c-fos responses were not diminished in the older vessels. The hsp70 response to elevated temperature (42 degrees C) was not changed with age. Activation of hsp70 expression most likely involves a pertussis toxin insensitive G protein which activates protein kinase C, and requires extracellular calcium. With age, hsp70 gene expression induced by stimulation of alpha1 adrenergic receptors is markedly attenuated, which could modify responses to stress or vascular injury with aging.

Adrenergic alpha-1 Receptor Agonists↗
PubMed1996

Ras-interacting domain of Ral GDP dissociation stimulator like (RGL) reverses v-Ras-induced transformation and Raf-1 activation in NIH3T3 cells.

Ral GDP dissociation stimulator (RalGDS) and RalGDS like (RGL) are putative effector proteins of Ras and contain the Ras-interacting domain (RID) at their C-terminal regions. v-Ras is known to activate c-fos promoter/enhancer and Raf-1 and to transform NIH3T3 cells. It is also known that v-Raf activates c-fos promoter/enhancer and transforms NIH3T3 cells. In this study, we examined the effect of RID on the phenotype of the cells transformed by v-Ras and v-Raf. Overexpression of RID greatly reduced cell growth in low serum, colony-forming activity in soft agar, c-fos promoter/enhancer activity, and Raf-1 activity of v-Ras-transformed cells. However, overexpression of RID did not affect the phenotype of v-Raf-transformed cells. These results clearly indicate that RID of RGL specifically binds to Ras in mammalian cells, that it blocks the signal from Ras to Raf-1, and that it reverses v-Ras-induced malignant phenotype. It has been reported that Ras-binding domains of Raf-1 and neurofibromatosis type 1 (NF1) reverse v-Ras-induced malignant phenotype. Since there is no homology in primary structures of RGL, Raf-1, and NF1, there may be a similarity of secondary or tertiary structure among RID of RGL and Ras-binding domains of Raf-1 and NF1, and the structure might be useful for developing a potential medicine for human cancers caused by Ras.

3T3 Cells↗
PubMed1996

Hemorrhage from abdominal non-Hodgkin's lymphoma treated successfully by emergency transcatheter arterial embolization.

A 49-year-old Japanese woman with follicular lymphoma who presented with severe abdominal and back pain is reported. She was known to have malignant lymphoma and had been previously treated with combination chemotherapy. An abdominal tumor occurring at the root of the mesentery and involving the superior mesenteric artery (SMA) had been diagnosed by computed tomography (CT), magnetic resonance imaging, and abdominal angiography. Emergent ultrasonography and CT findings showed intraperitoneal bleeding from the abdominal tumor. Selective SMA angiography revealed extravasation from a small branch originating from the dorsal pancreatic artery, which was embolized through a catheter by using platinum coils. It should be noted that a large tumor of malignant lymphoma, involving large vessels, may bleed, and in such a case selective transcatheter arterial embolization may be one of the effective modalities for hemostasis.

Abdominal Neoplasms↗