Search PubMed⌕ Search

Biomedical subjects

Y Okuyama

Publications and source records attributed to Y Okuyama.

At least 19 recordsLinked to original sources
PubMed2006

Bone response to titanium implants coated with thin sputtered HA film subject to hydrothermal treatment and implanted in the canine mandible.

Hydroxyapatite (HA) was coated onto titanium implants using radio frequency magnetron sputtering. The HA films were crystallized in an autoclave tube using low temperature hydrothermal treatment. The average film thickness on the implant was 1.1 microm. HA-coated and pure-titanium implants were inserted into canine mandibles for up to 24 weeks. Forty-eight implants were placed in eight beagles. After 2, 4, 12 and 24 weeks, implants were retrieved and prepared for histological observation, and the HA film thickness was determined using energy-dispersive X-ray spectroscopy. Light microscopy revealed that, after two weeks, the bone response to the HA-coated implants was much better than to the pure titanium implants, and osteoblasts were observed at the bone-implant interface. After four weeks, the screw threads of the HA-coated implants were almost completely covered with bone. The HA film thickness rapidly decreased up to four weeks of implantation, then gently decreased, reaching 0.40+/-0.03 microm at the upper region of the implant after 12 weeks. That indicates that about 80% of the HA film had dissolved after 12 weeks of implantation. The rate of decrease in the HA film thickness was greater with increasing implant depth.

Animals↗
PubMed2005

Serial changes in plasma brain natriuretic peptide concentration at the infarct and non-infarct sites in patients with left ventricular remodelling after myocardial infarction.

OBJECTIVES: To clarify the role of infarct and non-infarct sites on left ventricular (LV) remodelling after myocardial infarction by measuring brain natriuretic peptide (BNP) from each site. METHODS AND RESULTS: BNP from the aorta and the anterior interventricular vein (AIV) was measured in 45 patients with first anterior myocardial infarction at one, six, and 18 months. The LV was significantly dilated (> 10 ml/m(2) of end diastolic volume from one to 18 months) in 20 patients (remodelling (R) group) but not in 25 others (non-remodelling (NR) group). Patient characteristics and LV functions did not differ significantly at one month but plasma BNP concentration was higher in group R than in group NR (336 (288) v 116 (106) pg/ml, p < 0.01), predicting the degree of LV dilatation. The difference in BNP concentration between the aortic root and AIV (DeltaBNP), reflecting BNP secreted from the infarct site, did not differ at one month. In both groups BNP and DeltaBNP significantly decreased from one to six months (p < 0.05) and decreased from six months to 18 months, but the change was not significant. BNP and DeltaBNP were significantly higher in group R than in group NR after six months, when LV dilatation was not evident in both groups. CONCLUSION: Enhanced BNP secretion at one month in the non-infarct and infarct ventricular sites predicts subsequent LV dilatation (that is, remodelling). The slower process of LV remodelling decreased BNP secretion at both sites. Thus, BNP concentration should be useful for monitoring ventricular remodelling after infarction.

Cardiomyopathy, Dilated↗
PubMed2005

Plasma protein adsorption to nanofabricated fluorinated polyimide surface.

In this article, a series of fluorinated polyimides rubbed at different pressures was prepared, and the plasma protein adsorption on the rubbed polyimide films was evaluated using a micro-bicinchoninic acid protein assay. Interestingly, the amount of plasma protein adsorbed on the polyimide surface strongly depended on the rubbing pressure. The amounts of BSA and Fbg adsorbed on the rubbed polyimide film significantly decreased with an increase in the rubbing pressure. In contrast, the amounts of IgG adsorbed on the rubbed film dramatically increased with an increase in the rubbing pressure. In particular, it is interesting to note that a specific adsorption surface for IgG is formed by the rubbing process. We proposed that the nano-ordered hydrophilic and hydrophobic patternings formed on the top and bottom surfaces on the rubbed fluorinated polyimide film might have a significant influence on the plasma protein adsorption.

Adsorption↗
PubMed2003

Clinical features and treatment of hematopoietic stem cell transplantation-associated gastric antral vascular ectasia.

Gastric antral vascular ectasia (GAVE) may occur after hematopoietic stem cell transplantation (HSCT) and cause severe and prolonged gastric bleeding. The underlying pathology of transplant-associated GAVE (HSCT-GAVE) is poorly understood and an effective therapeutic strategy has not been established yet. We retrospectively reviewed the medical records of 230 consecutive allogeneic transplant recipients in our institution between January 1997 and June 2002. We identified five patients who developed HSCT-GAVE (2.2%). Four patients had bleeding from HSCT-GAVE and one patient had HSCT-GAVE discovered incidentally. The clinical features of these patients were similar in that they all received conditioning treatment with busulfan and had history of thrombotic microangiopathy. Furthermore, treatment with a beta-blocker apparently improved the outcome of HSCT-GAVE in three patients.

Adolescent↗
PubMed2003

Interaction between fibroblast cells and fluorinated polyimide with nano-modified surface.

In this study, we investigated the effect of surface nano-modification of aromatic fluorinated polyimide (6FDA-6FAP) derived from 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2,2'-bis (4-aminophenyl) hexafluoropropane (6FAP) on the interaction with proteins and cells. The surface of 6FDA-6FAP was modified by surface-rubbing showed nano-ordered stripes along the rubbing direction. The rat fibroblast FR cells formed multicellular spheroids with high cell density on the rubbed surface then expressed excellent collagen production similarly in vivo, while on the non-modified surface the cells formed two-dimensional monolayers and the collagen production was negligible. The modulation of cell function by the surface nano-modification along with surface micro-modification may be one of the most important considerations during the design and manufacture of novel biochips or tissue engineering materials.

Animals↗
PubMed2002

Isolation of an Acinetobacter sp. ST-550 which produces a high level of indigo in a water-organic solvent two-phase system containing high levels of indole.

Acinetobacter sp. strain ST-550 was isolated from fumus soil as an efficient indigo producer in the presence of organic solvent. The minimum inhibitory concentration of indole was 0.4 mg/ml for ST-550. ST-550 produced only a small amount of indigo (less than 0.01 microg/ml) when grown in the presence of indole at concentrations of 0.05 to 0.3 mg/ml without any organic solvent. However. ST-550 produced indigo effectively when grown in the presence of a large volume of diphenylmethane and a high level of indole: optimized conditions were 3 ml of a medium containing 0.3 ml diphenylmethane and 2.7 mg indole. Under these conditions, ST-550 produced 0.88 mg indigo (292 microg/mI medium).

Acinetobacter↗
PubMed2001

Optical mapping of ventricular defibrillation in isolated swine right ventricles: demonstration of a postshock isoelectric window after near-threshold defibrillation shocks.

BACKGROUND: Investigators who studied ventricular defibrillation by use of optical mapping techniques failed to observe an initial defibrillation event (isoelectric window or quiescent period) shown by electrode mapping studies. This discrepancy has important implications for the mechanisms of defibrillation. The purpose of the present study was to demonstrate an optical equivalent of an isoelectric window after a near-threshold defibrillation shock. Methods and Results-- We studied 10 isolated, perfused swine right ventricles. Upper limit of vulnerability was determined by shocks on T waves. A 50% probability of successful defibrillation (DFT50) was determined with an up-down algorithm. Immediately after unsuccessful defibrillation shock, new wavefronts were generated. When the shock strength was low, immediate reinitiation of reentry and ventricular fibrillation might occur without a postshock isoelectric window. However, if the shock strength was within 50 V of DFT50 (near-threshold), a synchronized activation occurred, followed by organized repolarization that ended 64+/-18 ms after shock. After a period of quiescence (18+/-24 ms), activation recurred 83+/-33 ms after shock and reinitiated ventricular fibrillation. Similar patterns of activation, including a quiescent period, were observed after shock was applied on the T wave of the paced beat that induced ventricular fibrillation. Upper limit of vulnerability correlated well with DFT50. CONCLUSIONS: In isolated swine right ventricles, an optical equivalent of an isoelectric window exists after near-threshold defibrillation shocks. These findings support the idea that a near-threshold defibrillation shock terminates all activation wavefronts but fails to halt ventricular fibrillation because the same shock reinitiates ventricular fibrillation after an isoelectric window.

Action Potentials↗
PubMed2001

Second allogeneic peripheral blood stem cell transplantation with fludarabine-based low-intensity conditioning regimen for relapsed myelodysplastic syndrome after allogeneic bone marrow transplantation.

We describe the case of a 51-year-old patient with relapsed myelodysplastic syndrome after allogeneic bone marrow transplantation (BMT), who underwent allogeneic peripheral blood stem cell transplantation (PBSCT) after conditioning with a novel regimen consisting of fludarabine, busulfan, and antithymocyte globulin. The second PBSCT was performed early, at 3 months after the initial allogeneic BMT, but it was well tolerated and complete hematologic remission was documented. The patient did not experience any early transplantation-related organ toxicity but died from opportunistic infection 6 months after the second transplantation. Our experience suggests that this novel regimen may induce remission and could be offered to patients relapsing after the first transplantation; however, the fludarabine-containing regimen might be accompanied by profound immunosuppression.

Antineoplastic Agents↗
PubMed2001

Effect of sesame seeds rich in sesamin and sesamolin on fatty acid oxidation in rat liver.

Activities of enzymes involved in hepatic fatty acid oxidation and synthesis among rats fed sesame (Sesamum indicum L.) differing in lignan content (sesamin and sesamolin) were compared. Sesame seeds rich in lignans from two lines, 0730 and 0732, lines established in this laborary, and those from a conventional cultivar (Masekin) were employed. Seeds from the 0730 and 0732 lines contained sesamin and sesamolin at amounts twice those from Masekin. Sesame seeds were added at levels of 200 g/kg to the experimental diets. Sesame increased both the hepatic mitochondrial and the peroxisomal fatty acid oxidation rate. Increases were greater with sesame rich in lignans than with Maskin. Noticeably, peroxisomal activity levels were >3 times higher in rats fed diets containing sesame seeds from the 0730 and 0732 lines than in those fed a control diet without sesame. The diet containing Masekin seed caused only a 50% increase in the value, however. Diets containing seeds from the 0730 and 0732 lines, compared to the control and Masekin diets, also significantly increased the activity of hepatic fatty acid oxidation enzymes including acyl-CoA oxidase, carnitine palmitoyltranferase, 3-hydroxyacyl-CoA dehydrogenase, and 3-ketoacyl-CoA thiolase. In contrast, diets containing sesame lowered the activity of enzymes involved in fatty acid synthesis including fatty acid synthase, glucose-6-phosphate dehydrogenase, ATP-citrate lyase, and pyruvate kinase. No significant differences in enzyme activities were, however, seen among diets containing sesame from Masekin cultivar and lines 0730 and 0732. Serum triacylglycerol concentrations were lower in rats fed diets containing sesame from lines 0730 and 0732 than in those fed the control or Masekin diet. It is apparent that sesame rich in lignans more profoundly affects hepatic fatty acid oxidation and serum triacylglycerol levels. Therefore, consumption of sesame rich in lignans results in physiological activity to alter lipid metabolism in a potentially beneficial manner.

Animals↗
PubMed2001

Effect of leucocyte reduction on the potential alloimmunogenicity of leucocytes in fresh-frozen plasma products.

BACKGROUND AND OBJECTIVES: Adverse effects mediated by leucocytes in cellular blood products are widely recognized. There are few studies, however, concerning the effects of residual leucocytes in fresh-frozen plasma (FFP). We examined the quantities and characteristics of leucocytes in FFP in order to investigate the potential leucocyte-associated adverse effects of FFP transfusion, focusing on the risk of alloimmunization. MATERIALS AND METHODS: The quantity of leucocytes in FFP was estimated by using the Nageotte method and flow cytometry (FCM) analysis. The viability and subsets of leucocytes were determined by FCM using propidium iodide (PI) and fluorescein-conjugated antibodies. To investigate alloimmunogenicity caused by the leucocytes in FFP, mixed lymphocyte cultures (MLC) were performed using fresh, allogeneic peripheral blood mononuclear cells (PBMCs) as responder cells and cell-concentrated thawed FFP as a stimulator. We also studied the performance of leucocyte-reduction filters with FFP products. RESULTS: The average number of leucocytes in a single unit of FFP, derived from 200 ml of whole blood, was 2.98 x 10(6) (range 0.99-8.38 x 10(6)). The majority of these cells were PI-positive dead cells; however, a small but consistent population of PI-negative cells was present in these products. Both dead and live cells expressed human leucocyte antigen (HLA) class I antigens, and approximately 38% of these cells expressed HLA class II antigens. The average number of viable CD3+ T cells in one unit of FFP was 2.36 x 10(4). Growth of the allogeneic PBMCs increased following stimulation with highly concentrated FFP. Use of leucocyte-reduction filters significantly reduced the concentrations of both PI-positive (dead) and PI-negative (live) cells. The growth of allogeneic lymphocytes after stimulation with FFP was also completely suppressed by leucocyte filtration of FFP. CONCLUSION: Transfusion of FFP is potentially alloimmunogenic owing to its residual leucocyte content. Leucocyte-reduction filters appear to be effective in suppressing the alloimmunogenicity of FFP.

Adult↗
PubMed2001

In vitro melanin binding of NS-49, a phenethylamine class alpha 1A-adrenoceptor agonist.

Characteristics of the in vitro binding of NS-49 ((R)-(-)-3'-(2-amino-1-hydroxyethyl)-4'-fluoromethanesulfonanilide hydrochloride, CAS 137431-04-0) to synthetic melanin were determined and compared with those of other drugs. At all the drug concentrations tested (12.5-200 mumol/l), chloroquine (CAS 54-05-7) had the highest melanin binding (%), followed by ofloxacin (CAS 82419-36-1), NS-49, norephedrine (CAS 154-41-6) and diazepam (CAS 439-14-5). Binding constants (Kb), calculated with the Langmuir adsorption isotherm were, in the order (largest to smallest) chloroquine, ofloxacin, NS-49, norephedrine, the Kb value for NS-49 being one-thirteenth that for chloroquine, one-seventh that for ofloxacin and ten times higher than that for norephedrine. 53% of NS-49 that was bound to synthetic melanin dissociated during 24 h of incubation after the binding experiment. The percent of dissociation for NS-49 was higher than the values for chloroquine (5%) and ofloxacin (39%). After 1 day incubation in the dissociation experiment, the amount of NS-49 bound per mg of melanin was 23 nmol, being less than the amounts of chloroquine (210 nmol) and ofloxacin (78 nmol). These findings indicate that NS-49 has a lower affinity for synthetic melanin than chloroquine and ofloxacin, which have high affinities and therefore accumulate in melanin containing ocular tissues.

Adrenergic alpha-Agonists↗
PubMed2001

Effects of diacetyl monoxime and cytochalasin D on ventricular fibrillation in swine right ventricles.

Whether or not the excitation-contraction (E-C) uncoupler diacetyl monoxime (DAM) and cytochalacin D (Cyto D) alter the ventricular fibrillation (VF) activation patterns is unclear. We recorded single cell action potentials and performed optical mapping in isolated perfused swine right ventricles (RV) at different concentrations of DAM and Cyto D. Increasing the concentration of DAM results in progressively shortened action potential duration (APD) measured to 90% repolarization, reduced the slope of the APD restitition curve, decreased Kolmogorov-Sinai entropy, and reduced the number of VF wave fronts. In all RVs, 15-20 mmol/l DAM converted VF to ventricular tachycardia (VT). The VF could be reinduced after the DAM was washed out. In comparison, Cyto D (10-40 micromol/l) has no effects on APD restitution curve or the dynamics of VF. The effects of DAM on VF are associated with a reduced number of wave fronts and dynamic complexities in VF. These results are compatible with the restitution hypothesis of VF and suggest that DAM may be unsuitable as an E-C uncoupler for optical mapping studies of VF in the swine RVs.

Action Potentials↗
PubMed2001

A human case of protothecosis successfully treated with itraconazole.

Cutaneous protothecosis developed in a 63-year-old Japanese female. The patient had a long history of steroid use for bronchial asthma. A tender, swollen, erythematous plaque with white papules covered the dorsal aspect of the patients right hand. Histopathological examination showed typical protothecosis with numerous mulberry-like sporangia positive for periodic acid-Schiff stain. The pathogen was identified as Prototheca wickerhamii. After a 6-week course of 150-200 mg/day itraconazole (ITCZ) therapy, the patients culture was negative for P. wickerhamii. No recurrence was seen after 12 weeks of ITCZ therapy. This case of protothecosis and those of 16 patients are summarized. All the patients had lived in mid- to southern Japan. Only 12 cases of protothecosis treated with ITCZ have been reported in the literature; 8 of these cases were cured with ITCZ therapy alone. In cases treated with ITCZ at no more than 100 mg/day, medication was typically needed for 2 months; most of the cases treated with ITCZ at 200 mg/day were successfully cured within 2 months. A 2-month course of ITCZ at 200 mg/day appears to be adequate treatment for human protothecosis.

Antifungal Agents↗
PubMed2000

Identification of a polymorphism in the promoter region of DRD4 associated with the human novelty seeking personality trait.

Polymorphism in the human dopamine D4 receptor gene (DRD4) exon III has been associated in some but not all studies of the human personality trait of Novelty Seeking. We searched for polymorphisms in the 5' region of DRD4 and identified six polymorphisms as follows: -1217G Ins/Del, -809G/A, -616C/G, -603T Ins/Del, -602(G)8-9, and -521C/T. Associations between these polymorphisms and personality traits measured by the Temperament and Character Inventory (TCI) were investigated in 86 healthy Japanese volunteers. The -521C/T polymorphism was significantly associated with Novelty Seeking (P = 0.0001). Subjects with the C/C genotype exhibited the highest Novelty Seeking scores and those with the T/T genotype exhibited the lowest. A transient expression method revealed that the T variant of the C-521T polymorphism reduces transcriptional efficiency. The present study suggests a contribution of dopamine D4 receptor availability to individual differences in Novelty Seeking behavior. Molecular Psychiatry (2000) 5, 64-69.

Adolescent↗
PubMed2000

Mutation and association analysis of the 5' region of the dopamine D3 receptor gene in schizophrenia patients: identification of the Ala38Thr polymorphism and suggested association between DRD3 haplotypes and schizophrenia.

Although the association between the Ser9Gly polymorphism of the dopamine D3 receptor gene (DRD3) and schizophrenia has been investigated by many research groups, it is not known whether the Ser9Gly polymorphism alone or a variation in linkage disequilibrium may effect susceptibility to schizophrenia. We searched the 5' region of the DRD3 gene and found three novel polymorphisms: -712G/C, -205A/G, and Ala38Thr. The Ala38Thr polymorphism is located in the first transmembrane region and is conserved in the monkey, mouse, and rat. Case-control comparisons in 153 Japanese schizophrenia patients and 122 Japanese controls did not suggest an association between Ala38Thr and schizophrenia. However, there was a marginally significant association between the Ser9 allele of the Ser9Gly polymorphisms and schizophrenia (P = 0.02). Furthermore, there was a highly significant association between haplotypes of the -712G/C, -205A/G, and Ser9Gly polymorphisms and schizophrenia (P = 0.0007, corrected P = 0.007). These positive findings were replicated in an additional 99 Japanese schizophrenia patients and 132 controls (P = 0.04 and 0.0004, respectively). The most allelic differences of the Ser9Gly polymorphism between patient and control groups arose from the chromosome carrying specific alleles of the other three polymorphisms. This study indicates unknown variant(s) in linkage disequilibrium with the DRD3 haplotypes associated with schizophrenia.

5' Untranslated Regions↗