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T Okubo

Publications and source records attributed to T Okubo.

At least 19 recordsLinked to original sources
PubMed1998

Electro-optic Properties of Colloidal Crystals As Studied by Reflection Spectroscopy.

Electro-optic properties of colloidal crystals of silica spheres in the exhaustively deionized aqueous suspension have been studied by the reflection spectroscopy using a T-type cell. Acoustic shear waves are induced when sine-wave electric fields ranging from 0.01 to 1 Hz are applied. Modulation effects of the crystals on the applied AC fields such as phase delay, change in response intensity, waveform transformation, and harmonics generation are observed. The shear waves propagate outside the electrodes where the electric field is absent. The synchronous fluctuation of the colloidal spheres including expanded electrical double layers in the crystal lattice will be one of the main causes of the electro-optic nature of the crystals. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Surface Tension of Biological Polyelectrolyte Solutions.

Surface tensions, gamma, of biological polyelectrolytes in aqueous solutions are studied systematically as possible at the air-water interface by the Wilhelmy method. The polyelectrolytes measured are sodium chondroitin sulfates A (NaCRA) and C (NaCRC), sodium poly-alpha,l-glutamate (NaPGA), poly-l-lysine hydrobromide (PLL . HBr), deoxyribonucleic acid (DNA), lysozyme (LZ), and bovine serum albumin (BSA). Linear-type macroions such as NaCR, NaPGA, PLL . HBr, and DNA have no surface activity in a wide range of polymer concentrations below the critical polymer concentration, m*, and increases as the concentration increases above m*. Surface activity of the undissociated state of macroions is rather high in general. Globule-like macroions such as LZ and BSA show high surface activity at isoelectric point above m* accompanied with orientation of the molecules along the air-water interface. Separation into the hydrophobic and hydrophilic parts at the interface and balancing in their strength are important for appearance of surface activity. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Novel mutations in the promoter and coding region of the human 5-HT1A receptor gene and association analysis in schizophrenia.

Dysfunction of serotonin systems has been implicated in schizophrenia. In the present study, the human 5-HT1A receptor gene containing the 5' untranslated region was screened in order to detect genetic variations, through which alteration of protein function or level of expression might contribute to schizophrenia. Genomic DNAs were isolated from whole-blood samples of 61 unrelated schizophrenic patients and 100 healthy controls. Genetic variations were screened systematically by single-strand conformational polymorphism (SSCP) analysis, followed by direct sequencing of polymerase chain reaction (PCR) product as well as restriction fragment-length polymorphism (RFLP). The novel mutations (-51T --> C, -152C --> G, -321G --> C, -480delA, and -581C --> A) were found in the 5' untranslated region. Furthermore, we found a novel missense mutation (Gly272Asp) in the coding region in addition to the mutations (Pro16Leu, 294G --> A, and 549C --> T) reported previously. No significant differences in genotype frequencies as well as allele frequencies were found between patients and controls. Our data provided no evidence of association between schizophrenia and the variants in the 5' untranslated region as well as the coding region of the human 5-HT1A receptor gene.

Genetic Markers↗
PubMed1998

Kinetic Analyses of Colloidal Crystallization in Alcoholic Organic Solvents and Their Aqueous Mixtures As Studied by Reflection Spectroscopy.

Reflection spectroscopy is used for the kinetic analyses of the nucleation and growth process of colloidal crystals of silica spheres (110 nm in diameter) in exhaustively deionized suspensions of purely alcoholic organic solvents (methyl alcohol, ethyl alcohol, and ethylene glycol) and aqueous mixtures with alcohols (methyl, ethyl, n-propyl, and n-butyl alcohols and ethylene glycol). Sphere concentrations studied range from 0.001 to 0.01 in volume fraction, rather high compared with those in water. Induction periods are from 5 to 2000 s and are prolonged with decreasing sphere concentration. Nucleation rates are 10(-3) to 10(3) mm-3 s-1 and increase sharply as sphere concentration increases. The crystal growth rates, v have been determined from the increase of intensity in the sharpened reflection peaks. Values of v range from 1 to 27 µm/s and decrease linearly as the reciprocal sphere concentration increases. Nucleation and crystallization rates decrease sharply as the fraction of the organic solvents increases in the mixtures with water. The importance of the electrostatic intersphere repulsion through the electrical double layers and the cooperative and synchronized fluctuation of colloidal spheres in the crystallization processes is supported. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

[Research on the contents of material safety data sheets].

The Material Safety Data Sheet (MSDS) system for the safe management of chemical substances was officially promulgated in 1993 and has been gradually put into practice through administrative guidance in Japan. However, little research has been done on the quality of such data sheets provided from various sectors of industries. We examined two sets of MSDSs obtained from a refractory ceramic plant. In the first survey in 1995, the set of MSDSs was from July, 1992 to March, 1994; and in the second survey in 1997, the set was from April, 1994 to November, 1996. The number of MSDSs examined in these two surveys was 159 and 81, respectively. The number of MSDSs in which "Hazard Identification" was indicated was 100 (63%) in the 1995 survey and 75 (93%) in the 1997 survey. The number of those in which "Toxicological Information (Stability and Reactivity)" was indicated was 81 (51%) and 80 (99%), respectively. The description rates for the essential items, including the above two, were found to be improving.

Data Collection↗
PubMed1998

Clinical significance of inhibitors in acquired von Willebrand syndrome.

Of 260 patients enrolled, 25 patients (9.6%) were associated with acquired von Willebrand syndrome (AvWS). We studied 25 patients with AvWS, retrospectively. AvWS was diagnosed by reduced levels of von Willebrand factor (vWF) (decrease of von Willebrand factor antigen [vWF:Ag] and von Willebrand ristocetin cofactor [vWF:RCoF]), a decrease of ristocetin-induced platelet agglutination (RIPA), sometimes decreased high-molecular-weight multimers, and prolonged bleeding time with neither prior nor family histories of bleeding problems and the evidence of normal vWF:RCoF in their families. The inhibitor of vWF was determined by mixing patient plasma with pooled normal plasma. Eight patients in this study had the inhibitors to vWF that were of the IgG class; the subclasses were IgG1 (7 cases) and IgG2 (1 case). Multimeric analysis of vWF showed selective loss of large multimers in most patients with AvWS similar to that of congenital type-2 von Willebrand disease (vWD). All inhibitors blocked ristocetin-mediated vWF binding to platelets. Five out of 6 IgGs evaluated here recognized the 39/34-kD fragment (residues 480/481-718) and Fragment III (residues 1-1365) that implied binding domain of glycoprotein Ib (GPIb), whereas 1 recognized Fragment I (residues 911-1365). A close relationship was found between the presence of the inhibitor and bleeding tendency. Of the 7 patients with inhibitors, 6 patients (86%) had a bleeding tendency, as well as 1 of the 15 patients without inhibitors (6%). The efficacy of treatment of underlying diseases and/or therapy with deamino D-arginine vasopressin (DDAVP) for the treatment of AvWS also depends on the presence of an inhibitor. Four of 8 patients with inhibitors (50%) had poor response to treatment of the underlying disease and/or therapy with DDAVP, as well as 1 of the 16 patients without inhibitors (6%). These results indicate that patients with AvWS developing inhibitors to vWF are likely to have bleeding problems and might be resistant to treatment of underlying diseases and/or therapy with DDAVP for bleeding to AvWS. We also showed evidence that intravenous immunoglobulin therapy (0.3 g/kg, 3 days) was effective to correct a hemostatic defect and manage severe bleeding in a patient with AvWS developing inhibitors. We might consider an additional treatment including expensive high-dose immunoglobulin therapy when uncontrollable bleeding is continued after the treatment of the underlying diseases and/or therapy with DDAVP.

Adult↗
PubMed1998

Inhibition of inducible nitric oxide synthase prevents LPS-induced acute lung injury in dogs.

Nitric oxide (NO) is produced by inducible NO synthase (iNOS) after LPS stimulation, and reacts with superoxide to form peroxynitrite. We hypothesize that in LPS-induced lung injury, NO generated by iNOS plays a key role through the formation of peroxynitrite. We developed an acute lung injury dog model by injecting LPS, and examined the effects of selective iNOS inhibitors, aminoguanidine (AG) and S-methylisothiourea sulfate (SMT), on the LPS-induced lung injury. At 24 h after LPS injection, arterial oxygen tension and mean arterial pressure decreased, and shunt ratio and lung wet-to-dry weight ratio increased. On histology, the LPS group had marked neutrophil infiltration and widening of the alveolar septa. On immunohistochemistry, iNOS and nitrotyrosine, a major product of nitration of protein by peroxynitrite, were observed in the interstitium, capillary wall, and neutrophils in the airspaces of the LPS group. Treatments with AG and SMT prevented worsening of gas exchange, hemodynamics, and wet-to-dry weight ratio. On histology, AG and SMT treatments markedly suppressed lung injury, iNOS protein, and nitrotyrosine production. We conclude that NO released by iNOS may play a critical role in the pathogenesis of LPS-induced acute lung injury. This study suggests that iNOS inhibitors may have potential in the treatment of LPS-induced acute respiratory distress syndrome.

Animals↗
PubMed1998

Comparison of the qualified occupational physician systems in the United Kingdom and Japan.

The British educational system of occupational medicine was compared to the Japanese system. Furthermore, a comparison was carried out between the certified occupational physician (COP) recognized by the Japan Society for Occupational Health in Japan and the Associateship of the Faculty of Occupational Medicine (AFOM) by the Faculty of Occupational Medicine (FOM) which is a part of the Royal College of Physicians in the United Kingdom. Judging from the comparison of the minimum total training period, the clinical training period, the occupational health training period, the method of examination and the success rate between COP and AFOM, it is suggested that the British system of occupational physicians may be better as a training system for occupational medicine and may regard occupational clinical training as more important than the Japanese system does. A comparison of a Diploma in Occupational Medicine (Dip Occ Med) approved by the FOM and the certification of occupational physicians by the Japan Medical Association has shown that the former has an examination but there is no test system in the latter. It should be discussed whether an examination system for the certification of occupational physicians should be introduced into the Japanese system in the near future.

Education, Medical, Continuing↗
PubMed1998

DNA cleavage and 8-hydroxydeoxyguanosine formation caused by tamoxifen derivatives in vitro.

DNA damage caused by tamoxifen and its derivatives was examined by estimating the conversion of supercoiled pUC18 plasmid DNA to linear form by means of agarose gel electrophoresis. N-Desmethyltamoxifen induced DNA cleavage and its effect was enhanced by the addition of reducing agents such as dithiothreitol, NADPH and 2-mercaptoethanol. 4-Hydroxytamoxifen itself had little effect, but the cleavage was slightly enhanced by the addition of reducing agents. DNA damage was higher with alpha-hydroxytoremifene than with alpha-hydroxytamoxifen, which had a prominent effect only at high concentration. The cleavage by alpha-hydroxy derivatives were not enhanced by reducing agents. No damage was induced by tamoxifen, toremifene, 3-hydroxytamoxifen or N-desmethyltoremifene. The DNA cleavage by N-desmethyltamoxifen was inhibited by the addition of EDTA, mannitol, sodium azide, methionine, catalase and superoxide dismutase. The formation of 8-hydroxy-2'-deoxyguanosine was also examined with calf thymus DNA in vitro. A slight increase of its level was found with 4-hydroxytamoxifen in the presence of dithiothreitol and also with N-desmethyltamoxifen in the presence of NADPH, but alpha-hydroxytoremifene and alpha-hydroxytamoxifen were ineffective. These experimental data suggest that among metabolites of tamoxifen, N-desmethyltamoxifen and probably also 4-hydroxytamoxifen cause oxidative DNA damage in which redox cycling is involved. The DNA damage by alpha-hydroxytoremifene appears to involve a different mechanism from that by N-desmethyltamoxifen. Tamoxifen and toremifene are possibly metabolized to the forms contributing to DNA damage.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1998

[Mitral valve replacement for three cases of hypertrophic obstructive cardiomyopathy--surgical treatment].

Three patients with obstructive cardiomyopathy underwent surgical treatment. Mitral valve replacement was performed in all three cases and myectomy of hypertrophic septal muscle was performed in one case. The pressure gradients between the left ventricle and the aorta was less than 10 mmHg in all cases after surgery, Clinical symptoms strikingly improved in three cases. An accurate surgical treatment could be achieved by choosing either myotomy-myectomy, mitral valve replacement or both in the setting of individual condition of each patients.

Cardiomyopathy, Hypertrophic↗
PubMed1998

Additional recognition sites in the C-terminal heparin-binding domain of fibronectin promote adhesion of PMA-treated U937 cells.

Recently we have shown an evidence that a peptide, corresponding to residues Gln1892 to Gly1910, from the C-terminal heparin-binding domain of fibronectin promotes adhesion of phorbol-12-myristate 13-acetate (PMA)-treated U937 cells and binds to both integrin alpha 4 beta 1 and glycosaminoglycans on U937 cells surface. We present additional adhesion-promoting sites to PMA-treated U937 cells present in the C-terminal heparin-binding domain of fibronectin. Three synthetic peptides (residues Ala1819 to Lys1830, designated E5; Thr1828 to Gly1940, E4; and Lys1946 to Leu1963, D1) were active to inhibit adhesion of PMA-treated U937 cells to the 29-kDa fragment comprising the C-terminal heparin-binding domain of fibronectin. Scrambled versions of these peptides had no inhibitory activity on this adhesion. The IgG-conjugated peptides (IgG-E5, IgG-E4, and IgG-D1) were also active and supported adhesion to an extent comparable to that of the 29-kDa fragment. The adhesion of PMA-treated U937 cells on these three IgG-conjugated peptides was only inhibited by glycosaminoglycans and not by integrin alpha 4 beta 1. These results indicate that additional adhesion-promoting sequences are present in the C-terminal heparin-binding domain of fibronectin and that the activity of these peptides depends on peptide sequence, mainly the result of net charges or net hydropathy indices.

Amino Acid Sequence↗
PubMed1998

Allogeneic peripheral blood progenitor cell transplantation conditioned with anti-thymocyte globulin for treatment of graft failure after allogeneic bone marrow transplantation.

A 43-year-old female with AML-M1 developed late graft failure 4 months after her first allogeneic bone marrow transplant. The patient then underwent a second transplant with peripheral blood progenitor cells obtained from the same HLA-identical brother. The donor peripheral blood progenitor cells were mobilized with granulocyte colony-stimulating factor (10 micrograms/kg daily s.c. for 6 days). The patient received horse anti-thymocyte globulin alone (15 mg/kg per day for 5 days) as the conditioning regimen. Rapid hematopoietic recovery followed a sustained engraftment. The time to reach 0.5 x 10(9)/l neutrophils and 25 x 10(9)/l platelets was 10 and 12 days, respectively. Cytogenetic analysis of bone marrow performed on day +20 demonstrated a 46XY karyotype of donor origin. There was no acute graft-versus-host disease. The patient remains in complete remission with a karnofsky score of 90% 5 months after peripheral blood progenitor cell transplantation. To treat graft failure after allogeneic bone marrow transplantation, allogeneic peripheral blood progenitor cell transplantation conditioned with anti-thymocyte globulin alone should be considered as a feasible alternative to marrow transplant.

Adult↗
PubMed1998

Isolated extramedullary relapse in knee joint after allogeneic bone marrow transplantation for Ph ALL.

We report a patient who relapsed in a patella and knee joint after allogeneic bone marrow transplantation (BMT) for Ph chromosome-positive acute lymphoblastic leukemia. The patient complained of pain and swelling of knee joint 14 months post-BMT. Fluid from the knee joint included leukemic cells consistent with the immunophenotype of blasts prior to BMT and also revealed the bcr/abl transcript by reverse-transcriptase polymerase chain reaction. Magnetic resonance imaging demonstrated an abnormal signal in the patella. Radiotherapy to the localized extramedullary lesion was successful and no bone marrow relapse has been detected cytologically and cytogenetically to date. This case suggests that the physician should be aware of unusual relapse sites of leukemia post-BMT.

Adult↗
PubMed1998

Diagnostic value of hemostatic parameters in bone marrow transplant-associated thrombotic microangiopathy.

We investigated hemostatic parameters in a prospective study of 16 patients who received bone marrow transplants (BMT). We found a significant rise in the levels of fibrinogen, plasmin-alpha2 antiplasmin inhibitor complex, tissue-plasminogen activator.plasminogen activator inhibitor complex (t-PA.PAI), von Willebrand factor antigen, and thrombomodulin on day 14 after transplant compared with values before transplant. Protein C and thrombin-antithrombin III levels did not change significantly. No significant changes in prothrombin time ratio, activated partial thromboplastin time, or protein S were detected. Patients who had grades II-IV graft-versus-host disease (GVHD) (n = 6) showed a significantly higher level of t-PA.PAI on day 14 compared with those with grades 0-I GVHD (n = 10) (P = 0.0062). Three patients with grades II-IV GVHD developed thrombotic microangiopathy (TMA) on days 19, 19 and 62. In these patients, we noted significantly lower levels of fibrinogen (P = 0.0383), and significantly higher levels of t-PA.PAI (P = 0.0008) and thrombomodulin (P = 0.0001) on day 14 compared with those patients who did not develop TMA. These results suggest that prothrombotic states and endothelial damage may be caused by the conditioning regimen and/or acute GVHD during BMT; thrombomodulin values on day 14 post BMT may be useful in surveillance for TMA because of endothelial cell injury.

Adolescent↗
PubMed1998

An effective method for isolating alginate lyase-producing Bacillus sp. ATB-1015 strain and purification and characterization of the lyase.

A new alginate lyase-producing micro-organism, designated as Bacillus sp. strain ATB-1015, was effectively isolated from soil samples pretreated for 3 months with a substrate of the enzyme, sodium alginate. Alginate lyase activity was assayed by the degrading activity of biofilm of Teflon sheet discs, which was formed by a mucoid strain of Pseudomonas aeruginosa PAM3 selected from clinical isolates. The extracellular alginate lyase was precipitated with ammonium sulphate from the culture broth, and purified by gel filtration and anion exchange chromatography. The molecular weight of the lyase was estimated to be 41 kDa by SDS polyacrylamide gel electrophoresis and Sephacryl S-200 HR column chromatography. The optimum pH and temperature for the enzyme activity were around 7.5 and 37 degrees C, respectively, and the Km value was 0.17% with the substrate, sodium alginate. The lyase activity was completely inhibited by treatment with 1 mmol l-1 of EDTA and the decreased activity was almost completely recovered by the addition of 2 mmol l-1 of CaCl2. The activity was not affected by treatment with the protein denaturants, 0.01 mol l-1 of SDS or 1 mmol l-1 of urea. The lyase had substrate specificity for both the poly-guluronate and poly-mannuronate units in the alginate molecule.

Alginates↗
PubMed1998

Occupational lung diseases and global occupational health on the Net.

Occupational lung disease is a major area of concern in occupational health, exhibiting a diverse panorama across countries. While pneumoconiosis is deemed to be the most common occupational disease in many developing countries, emphasis is shifting towards asbestos-related lung diseases and occupational asthma in industrialized countries. Following the Occupational Health for All strategies set forth by the World Health Organization, we propose that a model system based upon the Global Health Network can serve as an effective vehicle towards the prevention of occupational lung diseases on a global scale. It has the potential to: (1) enhance transmission of data and collaboration with the primary health care system in disease surveillance; (2) strengthen research and information transfer and (3) promote education and training at all levels of prevention, with a possible application to the interpretation of chest radiograms.

Computer Communication Networks↗