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Biomedical subjects

T Oka

Publications and source records attributed to T Oka.

At least 721 records · Page 40Linked to original sources
PubMed1992

Benchmark test of transport calculations of gold and nickel activation with implications for neutron kerma at Hiroshima.

A benchmark test of the Monte Carlo neutron and photon transport code system (MCNP) was performed using a 252Cf fission neutron source to validate the use of the code for the energy spectrum analyses of Hiroshima atomic bomb neutrons. Nuclear data libraries used in the Monte Carlo neutron and photon transport code calculation were ENDF/B-III, ENDF/B-IV, LASL-SUB, and ENDL-73. The neutron moderators used were granite (the main component of which is SiO2, with a small fraction of hydrogen), Newlight [polyethylene with 3.7% boron (natural)], ammonium chloride (NH4Cl), and water (H2O). Each moderator was 65 cm thick. The neutron detectors were gold and nickel foils, which were used to detect thermal and epithermal neutrons (4.9 eV) and fast neutrons (> 0.5 MeV), respectively. Measured activity data from neutron-irradiated gold and nickel foils in these moderators decreased to about 1/1,000th or 1/10,000th, which correspond to about 1,500 m ground distance from the hypocenter in Hiroshima. For both gold and nickel detectors, the measured activities and the calculated values agreed within 10%. The slopes of the depth-yield relations in each moderator, except granite, were similar for neutrons detected by the gold and nickel foils. From the results of these studies, the Monte Carlo neutron and photon transport code was verified to be accurate enough for use with the elements hydrogen, carbon, nitrogen, oxygen, silicon, chlorine, and cadmium, and for the incident 252Cf fission spectrum neutrons.

Californium↗
PubMed1992

The effects of pravastatin on hyperlipidemia in renal transplant recipients.

Hyperlipidemia may be one of the risk factors in the development of atherosclerotic disease in renal transplant recipients. In the present study, 24 kidney recipients with hyperlipidemia were treated with an HMG-CoA reductase inhibitor, pravastatin (10 mg/day). All recipients had been treated with cyclosporine (CsA), azathioprine (Az), and prednisolone (Pred). The mean total cholesterol (T-chol) level decreased from 323 +/- 7.4 to 261 +/- 7.9 mg/dl at one month after starting treatment (P less than 0.01) and this level did not change during treatment for further 6 months. The mean LDL cholesterol level was also decreased from 205.9 +/- 11.2 to 118.7 +/- 8.1 mg/dl at 3 months after starting treatment (P less than 0.01). On the other hand, pravastatin did not affect the levels of HDL-cholesterol and triglycerides. Pravastatin did not show any effects on the white blood cell, monocyte, and lymphocyte counts, or the hemoglobin concentration (NS). One patient displayed a slight elevation of aspartate aminotransferase and alanine aminotransferase levels, but this was not sufficient to cease treatment. Pravastatin did not adversely affect the renal function or creatinine phosphokinase (CPK) levels. Two recipients developed nausea and vomiting and their treatment was stopped. Pravastatin appears to be a safe and efficacious method of treating hyperlipidemia in renal transplant recipients.

Cholesterol↗
PubMed1992

Characterization of an amorphous and soluble hemagglutinin from Yersinia pseudotuberculosis.

Yersinia pseudotuberculosis which were screened out depending on auto-agglutination and Ca2+ dependency, were examined for their production of hemagglutinin (HA), and its purification and characterization were performed. The HA with a broad reactivity with various mammalian erythrocytes was recovered from the culture supernatant of these strains grown at 37 C but not 25 C. HAs from two strains, R148R and T1040, were purified by salt precipitation, gel filtration and anion-exchange chromatography by HPLC. Both purified HAs were cysteine-deficient acidic protein with an apparent molecular weight in the range of 15,000 to 16,000. N-terminal amino acid sequences of the first 25 residues were found to share 12% identity with that of afimbrial adhesin from enterotoxigenic Escherichia coli 2230. Immunoelectron microscopy and immunodiffusion test with polyclonal antiserum raised against the purified R148RHA demonstrated that the HA was associated with the amorphous aggregates which were detached from bacteria. These results suggest that the HA of Y. pseudotuberculosis belongs to a third type of HA produced by the yersinial species.

Amino Acid Sequence↗
PubMed1992

A case of intramural uterine stromal tumor with epithelial differentiation.

A case of intrauterine tumor in a 62-year-old Japanese woman is presented. It was thought initially that this was a case of uterine tumor resembling an ovarian sex cord tumor. To examine the cytological features of the tumor cells, electron microscopical and immunohistochemical studies were done, and a hormone assay of the tumor tissue was performed. The tumor cells were rich in rough endoplasmic reticulum (rER), mitochondria and microfilaments. Some tumor cells tended to form glandular patterns, but these epithelial elements were frequently scattered among fibrous stromal elements. Though many tumor cells with an epithelial appearance possessed a large quantity of cytokeratin and vimentin, they did not secrete estradiol, progesterone, testosterone or human chorionic gonadotropin. This case was finally diagnosed as an intramural uterine stromal tumor with epithelial differentiation after taking all the available data into consideration. This would be classified as an endometrial stromal tumor with epithelial elements, recently proposed and named by Clement and Scully.

Antigens, Neoplasm↗
PubMed1992

Phenotypic progression of a rat lymphoid cell line immortalized by human T-lymphotropic virus type I to induce lymphoma/leukemia-like disease in rats.

Rat lymphoid cells, TARS-1, immortalized by coculture with adult T-cell leukemia cells, were intraperitoneally injected into 65 newborn, inbred WKAH/Hkm rats. In most of the rats, tumor nodules were discernible 7 to 15 days after transplantation but were completely rejected within 5 to 6 weeks. Two rats with no tumor nodules exhibited gait disturbances and paralysis of the hind legs 3 to 4 weeks after transplantation. Histological and hematological examinations revealed that a lymphoma/leukemia-like disease had developed in one of the two rats, and the T-lymphoid cell line WLeuk-1 was established from peripheral blood mononuclear cells from this rat. When the WLeuk-1 cells were transplanted into newborn WKAH/Hkm rats, the animals died of a lymphoma/leukemia-like disease within several weeks after transplantation, in contrast to their rejection of the TARS-1 cells. Southern blot and karyotype analyses revealed that WLeuk-1 cells had retained the marker chromosomes and human T-lymphotropic virus type I (HTLV-I) integration patterns of the parent cell line, TARS-1. The additional specific chromosome abnormalities 3p+,t (12;13), and Xq+ were found in the WLeuk-1 cells. Moreover, the expression of HTLV-I structural proteins was slightly depressed in WLeuk-1 cells, while that of the transacting factors p40tax and p21x, but not that of p27rex, was enhanced about fivefold compared with that in TARS-1. The transactivating function of p40tax was intact in WLeuk-1, as evidenced by enhanced interleukin-2 receptor alpha chain expression. These results suggest that aberrant expression of HTLV-I regulatory genes and alteration of cellular genes were associated with the phenotypic progression of the WLeuk-1 cell line.

Animals↗
PubMed1992

Distribution of two types of infiltrating helper T cells among rat renal allografts, spleen, peripheral blood, and regional lymph node cells.

Cytokine production by graft-infiltrating cells (GIC) of helper T cell (Th) subtypes were investigated in rat kidney allograft compared to those infiltrating the spleen, those in peripheral blood, and in regional lymph nodes. The relative proportion of OX-22 positive cells (Th type 1) and the W3/25-positive cells (Th) of GIC was 49.4 +/- 2.1% on day 3 and 52.7 +/- 2.2% on day 6, whereas those in spleen cells was 80.3 +/- 4.1% (p less than 0.05) and 95.5 +/- 2.5% (p less than 0.01), respectively. GIC produced more B cell-stimulating factor 2 (BSF-2, 106.3 +/- 8.2 U/ml) when compared to spleen cells (15.9 +/- 4.6 U/ml; p less than 0.01), peripheral blood mononuclear cells (4.2 +/- 1.0 U/ml; p less than 0.01) or lymph node cells (24.9 +/- 4.0 U/ml; p less than 0.01) upon stimulation with donor BN lymphocytes in vitro. However, GIC produced less interleukin 2 (IL-2, less than 1.0 U/ml) and IL-3 (less than 1.0 U/ml) than produced by spleen cells (5.1 +/- 0.9 U/ml, p less than 0.05, and 10.5 +/- 2.3 U/ml, p less than 0.01, respectively) or lymph node cells (4.5 +/- 0.4 U/ml, p less than 0.01; 23.5 +/- 3.1 U/ml, p less than 0.01, respectively). These results demonstrate that the subtype of Th cells which produce BSF-2 migrates selectively to allografts.

Animals↗
PubMed1992

Comparison of lipids, apoproteins and associated enzyme activities between diabetic and nondiabetic end-stage renal disease.

Lipids, apoproteins and associated enzyme activities in type 2 diabetic end-stage renal disease (ESRD) were compared with that in nondiabetic ESRD and normal controls. Of the 40 uremic patients with non-insulin-dependent diabetes mellitus, 20 patients were receiving stable continuous hemodialysis treatment (CHT). Of the 39 patients with nondiabetic ESRD, 21 were undergoing CHT. Patients with nondiabetic ESRD exhibited elevated levels of serum triglyceride and a marked reduction in high-density-lipoprotein (HDL) cholesterol. Concentrations of serum apolipoprotein (Apo) C-3 were higher than in controls, whereas mean levels of serum Apo E were lower. The concentrations of serum Apo A-1 and Apo A-2 decreased with diminished lecithin: cholesterol acyltransferase activity. Lipoprotein lipase activity decreased in undialysed patients, and hepatic triglyceride lipase activity decreased significantly throughout the observation. Patients with diabetic ESRD exhibited elevated serum Apo B and normal serum Apo E levels, besides the lipid and Apo abnormalities observed in nondiabetic ESRD. Moreover, a prominent reduction in serum Apo A-1 was found in dialysed diabetic patients. The Apo B/Apo A-1 ratio was significantly higher in diabetic ESRD than in nondiabetic patients undergoing CHT. These results indicate that lipid abnormalities are accelerated in diabetic ESRD and may constitute a serious risk for the development of atherosclerosis.

Adult↗
PubMed1992

Pharmacokinetics of high-dose methylprednisolone in children.

Disposition of methylprednisolone was characterized in 11 children receiving the high-dose therapy (26.0 mg/kg on average). After intravenous infusion, methylprednisolone hemisuccinate was rapidly converted to methylprednisolone with a half-life of about 20 min. Methylprednisolone in serum, eliminated monoexponentially in 8 patients and biexponentially in the remaining three, had the mean residence time of about 3 h, and a terminal half-life of 2.5 h. The volume of distribution at steady state, and the clearance were 1.3 liters/kg and 0.5 liters/kg/h, respectively. Although these average pharmacokinetic parameters were comparable to those determined in other studies with conventional low doses, the clearance values in our data were characterized by 5-fold interindividual difference, suggesting large variations in exposures to methylprednisolone among children on the high-dose pulse therapy.

Adolescent↗
PubMed1992

Progesterone regulation of a pregnancy-specific transcription repressor to beta-casein gene promoter in mouse mammary gland.

Progesterone inhibits casein gene expression in the mammary gland during pregnancy. A pregnancy-specific mammary nuclear factor (PMF) is a transcriptional repressor that binds to the two separate sites of the beta-casein promoter region and mediates the inhibition of mouse beta-casein gene expression by progesterone. PMF has been detected in mouse mammary tissue during pregnancy, but not during the virginal or lactational periods. Southwestern hybridization showed that the PMF-binding sequence (TGAT/ATCA) bound a protein with a mol wt of 65 kilodaltons from mammary nuclear extract from pregnant mice, but not that from lactating animals. In this study the hormonal regulation of binding activity of PMF and its relationship to casein gene expression were also examined in vivo using ovariectomy of pregnant mice. Ovariectomy rapidly reduces the circulating progesterone and estrogen levels and induces lactogenesis in the mammary tissue of pregnant mice. After ovariectomy, the binding activity of PMF in the mammary gland was reduced to a very low level (< 5% of the sham-operated level) at 24 h, whereas the binding activity of another nuclear protein, octamer-like binding factor, was not altered 24 h after the operation. Progesterone injection at the time of ovariectomy inhibited the loss of PMF-binding activity, and the level of its activity was maintained at about 66% the level of sham-operated pregnant animals 24 h after steroid administration. The ability of progesterone to prevent the ovariectomy-mediated decrease in PMF-binding activity was specific, since other steroid hormones, such as estrogen, hydrocortisone, or testosterone, were incapable of doing so. In contrast to PMF, ovariectomy increased the level of beta-casein mRNA in mammary tissue, and this increase was inhibited by concomitant administration of progesterone, suggesting that the extent of beta-casein gene expression was inversely related to PMF-binding activity in mammary tissue. These results are consistent with the view that PMF plays a role in the regulation of casein gene expression by mediating the inhibitory action of progesterone.

Animals↗
PubMed1992

[Mechanism of the anti-osteoarthritic action of ulinastatin in comparison with those of indomethacin and triamcinolone].

We investigated the effect of ulinastatin, a candidate anti-osteoarthritic drug, in comparison with indomethacin and triamcinolone, two well-known drugs for osteoarthritis, on IL-1 production by monocytes, proteoglycan synthesis by chondrocytes and superoxide generation by leukocytes. Ulinastatin, a glycoprotein purified from human urine, suppressed both the IL-1 production and the IL-1 induced reduction of proteoglycan synthesis. In addition, ulinastatin inhibited superoxide generation. These actions of ulinastatin seemed to be related to its inhibitory actions against serine proteases such as trypsin, alpha-chymotrypsin, plasmin, leukocyte elastase and leukocyte cathepsin G. Triamcinolone suppressed the IL-1 production more potently than ulinastatin and it also suppressed the IL-1 induced reduction of proteoglycan synthesis. Triamcinolone alone, however, reduced the proteoglycan synthesis, and it did not affect the superoxide generation. In contrast, indomethacin had no effect on proteoglycan synthesis and superoxide generation, although it accelerated the IL-1 production. These results indicate that these three drugs have different mechanisms of action on the factors involved in the pathogenesis of osteoarthritis. Since ulinastatin has broad actions, which are considered to be beneficial for preventing some process of osteoarthritic pathogenesis, ulinastatin is expected to be an useful drug for the treatment of osteoarthritis.

Animals↗
PubMed1992

Specific activities of 60Co and 152Eu in samples collected from the Atomic-Bomb Dome in Hiroshima.

Neutron-induced activities 60Co and 152Eu have been measured for samples collected from the Atomic-Bomb Dome locating at 161 m from the hypocenter of the Hiroshima Bomb. Specific activities 60Co/Co and 152Eu/Eu at the time of the detonation have been determined as 10.0 +/- 1.0 Bq mg-1 (steel sample S4) and 80 +/- 9 Bq mg-1 (granite sample G1), respectively. Detailed measurements of 60Co and 152Eu activities for samples collected from various locations of the Dome show almost no directional dependence whether the sample faced to the epicenter or not, nor vertical height dependence between 17 m height and the ground level. In addition, 152Eu was not detected in the sample collected from the basement. It has been shown that the present 60Co activity value, the nearest steel one to the hypocenter, as well as other short distance data are systematically lower than the calculated values based on the neutron fluence of the DS86.

Cobalt Radioisotopes↗
PubMed1992

[Changes in mental workload and fatigue during performance of a mental task. 1. An experiment in 8-h self-paced transcribing task].

The changes in mental workload and fatigue during a one-day transcribing task were examined by determining some subjective and physiological measures which reflect mental activity. With an interval of one week between the three test days, 12 male students rested and performed self-paced transcribing task with moderate and maximum effort for 8 h each. The subjects transcribed more characters in the task with maximum effort than with moderate effort. In both the morning and afternoon, adrenaline excretion increased and heart rate decreased with the lapse of time. In linear proportion to the total working hours, occipital midline beta-2 amplitude, subjective rating of tiredness and subjective symptoms of fatigue rose, but critical flicker values fell slightly in the task with maximum effort. It was inferred from these results that with lapse of working hours intellectual activity and feeling of fatigue increase and the level of arousal slightly declines. Hence, it was considered that mental workload becomes heavier and subjective feeling of fatigue increases as the working hours become longer.

Adult↗
PubMed1992

Detection by western blotting of an antibody to the hepatitis C virus E1 envelope protein in sera of patients with chronic liver disease.

We detected an antibody to HCV envelope protein (E1) in sera of patients with HCV-related chronic liver diseases (20 patients with chronic hepatitis and 5 patients with liver cirrhosis) by Western blotting using the fusion protein of E1 envelope protein and beta-galactosidase as an antigen. The antibody to HCV E1 (anti-HCV E1) was detected in 8 (42%) of 19 patients positive for HCV-RNA (16 were positive and 3 were negative for antibody to C100-3) and in 1 (17%) of 6 patients negative for HCV-RNA but positive for antibody to C100-3. HCV-RNA was detected in 8 (89%) of 9 anti-HCV E1 positive sera. The value of alanine aminotransferase was significantly higher in patients positive for anti-HCV E1 than in patients negative for the antibody. Although an antibody to the envelope protein of HCV is suspected to be one of the candidates of virus-neutralizing antibodies, our results suggest this hypothesis appears to be unlikely.

Adolescent↗
PubMed1992

A case of primary intrahepatic sclerosing cholangitis (PISC) complicated with atypical biliary epithelial proliferation.

A 70-yr-old woman was admitted to our hospital with duodenal ulcer and anemia. The result of liver function test was abnormal and showed persistent elevated alkaline phosphatase levels. Thus, after recovery from duodenal ulcer, endoscopic retrograde cholangiopancreatography (ERCP) was performed; the characteristic "beaded" appearance with band-like strictures and saccular outpouchings affecting the intrahepatic biliary system were found. The diagnosis of primary intrahepatic sclerosing cholangitis (PISC) was made on the basis of the generally accepted diagnostic criteria of primary sclerosing cholangitis (PSC). However, the histological finding from a liver biopsy specimen revealed highly atypical epithelial proliferation of bile ducts. This case of PISC complicated with atypical biliary glandular changes is described, and the distinction between PISC and carcinoma of the bile duct is discussed.

Aged↗
PubMed1992

[Usefulness of MR angiography in renal tumor].

MR angiography using a gradient-echo, pulse sequence FLASH (fast, low-angle shot) method during breath-hold with a "MAGNETOM H-15" scanner (1.5 Tesla; Siemens Medical System) was performed on 27 patients with renal tumor at our clinic between February 20, 1990 and September 30, 1991 and we studied to evaluate its usefulness. Of these 27 patients, 22 patients including one patient under hemodialysis treatment had renal cell carcinoma and one patient had oncocytoma pathologically proven from the excised specimens. The remaining four patients including two patients associated with inferior vena caval tumor thrombus were clinically diagnosed as renal cell carcinoma based on the result of imaging examinations such as excretory urography, ultrasonography, computed tomography and conventional angiography. However, they could not be operated on because their tumors were too advanced. By reconstruction of the data of consecutive coronal scans of the abdomen with Maximum Intensity Projection (MIP), the MR angiography could in all cases delineate abdominal blood vessels such as the abdominal aorta, inferior vena cava and renal arteries and veins simultaneously without any intravenous contract materials. Our present study revealed that MR angiography has some advantages, especially with regard to preoperative angiographic information about the abdomen of patients with renal tumor. That is, MR angiography can delineate many kinds of arteries and veins of the abdomen simultaneously and in a broader range, as well as it can be performed on the patients with hypersensitivity to iodinated contrast materials or renal insufficiency in a usual fashion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1992

Characterization, self-assembly and reattachment of S layer from Clostridium botulinum type E saroma.

S layer of Clostridium botulinum type E Saroma and its subunits were isolated and characterized for their chemical and morphological properties. The S layer was composed of a number of subunits with apparent molecular weights ranging from about 10 to 150 kDa. The isolated S layer subunits possess the ability to assemble into recrystallized flat sheets in the absence of any supporting layer and to reattach to the cell wall from which they have been removed. Immunoblot analysis using an antiserum against whole cells of the organism showed that 60 kDa and 90 kDa subunits of the S layer were major somatic antigens of the organism. Immunogold-labeling using monospecific antiserum raised to the individual 60 and 90 kDa proteins revealed that both subunits were exposed evenly over the entire cell surface. The amino acid compositions of both subunits showed that aspartate and glutamate were predominant whereas cystine and methionine were poor. The amino acid composition and acidic property of the two subunits of the S layer agree well with the results obtained from the S layers of other bacterial species as well as other pathogenic clostridia.

Amino Acid Sequence↗
PubMed1992

In vitro self-assembly of the S layer subunits from Clostridium difficile GAI 0714 into tetragonal arrays.

Regularly arrayed surface component (S layer) of Clostridium difficile strain GAI 0714 was isolated with 4 M guanidine hydrochloride from the cell wall of the organism, and examined for self-assembly in vitro. The S layer was composed of two different protein subunits with molecular weights of 32 kDa and 45 kDa. Optical diffraction analysis revealed that the morphological units of both native and self-assembled S layer were essentially identical and composed of a rhombus possessing each side of 8.1 nm and interior angle of 88 degrees. The self-assembly of S layer subunits were induced in the presence of divalent cations such as Ca2+ or Zn2+, but Ba2+ or monovalent cations including K+, Na+ and Li+ failed to induce self-assembly. These results suggest that Ca+2 or Zn+2 may act as bridges to link negatively charged surface subunits.

Bacterial Outer Membrane Proteins↗