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Biomedical subjects

A Okamoto

Publications and source records attributed to A Okamoto.

At least 181 records · Page 10Linked to original sources
PubMed1991

Effect of Tween 80 on formation of the superficial L1 layer of the Mycobacterium avium-Mycobacterium intracellulare complex.

The effects of Tween 80 supplementation of liquid culture medium on the formation of the superficial L1 layer of the Mycobacterium avium-Mycobacterium intracellulare complex (MAC) were examined by serological and scanning electron microscopic experiments. Specific antiserum to the glycopeptidolipids on the L1 layer of M. avium S-139, made in a rabbit, was used for seroagglutination reactions with antigens prepared from strain S-139 grown in medium supplemented with various levels of Tween 80 (0, 0.05, 0.5, 5, and 50 mg/ml). The agglutination titers gradually decreased as the concentration of Tween 80 rose. Scanning electron microscopy showed that the fibrillar materials consisting mainly of glycopeptidolipids on the L1 layer of strain S-139 also disappeared with increases in the concentration of Tween 80. In addition, there was no obvious correlation between (i) the plasmid DNAs and serotypes of MAC and (ii) formation of the L1 layer of MAC. It is therefore concluded that Tween 80 used to supplement liquid culture medium affects formation of the L1 layer, which has been considered to be one of the pathogenic factors of MAC.

Animals↗
PubMed1991

Effect of molecular weight in amphipathic polyethyleneglycol on prolonging the circulation time of large unilamellar liposomes.

The effect in mice of the molecular weight of polyethyleneglycol on prolonging the circulation time of large unilamellar liposomes (LUVs) was examined using four different distearoyl N-(monomethoxy polyethyleneglycol succinyl) phosphatidylethanolamines (DSPE-PEGs). The molecular weights tested were 1000, 2000, 5000 and 12000. Incorporation of 6 mol% of DSPE-PEG in LUV composed of distearoylphosphatidylcholine (DSPC) / cholesterol (CH) (1:1 in molar ratio) increased the blood circulation half-life significantly more than those without DSPE-PEG derivatives. DSPE-PEGs with molecular weights of 1000 and 2000 prolonged the circulation time of liposomes more than other DSPE-PEGs with higher molecular weights, such as 5000 and 12000. Their effects are also higher than ganglioside GM1, a well described glycolipid with this effect. DSPC/CH LUV-incorporated DSPE-PEG with a molecular weight of 2000 displayed a high concentration in the blood, approximately 40% of the dose, 6 h after the injection.

Animals↗
PubMed1991

[Bile duct necrosis and hepatic necrosis following hepatic arterial infusion chemotherapy].

Three cases of bile duct necrosis owing to hepatic arterial infusion chemotherapy (HAI) were reported. Regarding HAI, transcatheter hepatic arterial embolization (TAE) was applied in two cases (hepatocellular carcinoma: 1; metastasis: 1) and 5-fluorouracil (continuous) combined with leucovorin (one shot) therapy (LV + 5-FU) was given to one metastatic case. In the data of blood biochemistry, serum alkaline phosphatase, gamma-glutamyl transpeptidase, and leucine aminopeptidase values characteristically elevated without the elevation of total bilirubin value. Hepatic tumors degenerated with necrosis in all cases and no viable cells were histologically recognized. Although the destruction of bile ducts was locally detected adjacent to these tumors in TAE cases and was more widespread in the LV + 5-FU case, these lesions were very similar in each case. Therefore, we concluded that both ischemia and drug toxicity induced bile duct necrosis and the necrosis around the bile duct was the secondary change due to the leaked bile juice.

Aged↗
PubMed1991

The cytoplasmic tail of CD4 targets chimeric molecules to a degradative pathway.

Many different cell surface receptors undergo endocytosis via coated pits. Once having entered the cell, the receptors are sorted into diverse pathways. Which path a given receptor will follow is determined by signals inherent in the receptor's structure. The nature of these structural features is not yet known. In this study, we have taken the approach of constructing chimeric molecules to localize the domain of the T-cell surface molecule CD4 which is responsible for targeting it for degradation. Chimeric molecules bearing the cytoplasmic domain of CD4 and the extracellular domain of either the low-density lipoprotein receptor or a major histocompatibility complex (MHC) class I molecule were both internalized in response to phorbol 12-myristate 13-acetate and were subsequently degraded, indicating that the cytoplasmic tail of CD4 contains all the information required for both processes. The ability to modulate the level of MHC class I molecules on the cell surface offers an approach to investigating quantitative aspects of antigen presentation, the initial possibilities of which are explored herein.

CD4 Antigens↗
PubMed1990

Purification and characterization of 3-mercaptopyruvic acid S-conjugate reductases.

Three kinds of 3-mercaptopyruvic acid S-conjugate reductase (MPR-I, MPR-II and MPR-III) were purified from rat liver cytosol. These enzymes reduced 3-mercaptopyruvic acid S-conjugates derived from cysteine conjugates and some endogenous alpha-keto acids to the corresponding alpha-hydroxy acids in the presence of either NADH (for MPR-I and MPR-II) or NADPH (MPR-III), while simple aldehydes or ketones did not significantly induce substrate activity. The molecular weight of the present enzymes was about 80 kDa composed of two subunits of the same molecular weight. Km values of MPR-I, MPR-II and MPR-III were 0.38, 0.06 and 0.29 mM for S-(4-bromophenyl)-3-thiopyruvic acid, respectively, and 0.15 mM for NADH (MPR-I, MPR-II) and NADPH (MPR-III). Vmax values of MPR-I, MPR-II and MPR-III for this substrate were 5.3, 20 and 13 nmol/min/mg, respectively. The sulphydryl-modifying agents inhibited the enzyme activities of all the three reductases. Based on the properties including substrate selectivity for alpha-keto acids derived from aromatic amino acids, we assumed that MPR-II and aromatic alpha-keto acid reductase are the same enzyme, while enzymes similar to MPR-I and MPR-III have not been reported. From the viewpoints of metabolism of xenobiotics, these enzymes are likely to be important in biotransformation of cysteine conjugates to 3-mercaptolactic acid S-conjugates.

Animals↗
PubMed1990

Three-dimensional structures of aspartate aminotransferase from Escherichia coli and its mutant enzyme at 2.5 A resolution.

The structure of Escherichia coli aspartate aminotransferase complex with the inhibitor 2-methylaspartate, and that of the mutant enzyme in which an arginine was substituted for a lysine residue thereby forming a Schiff base with the coenzyme pyridoxal 5'-phosphate, were determined at 2.5 A resolution, by the molecular replacement method using the known structure of pig cytosolic aspartate aminotransferase. The enzyme catalyzes the reversible transamination between L-aspartate and alpha-ketoglutarate, and forms a dimeric structure of two identical subunits. Each subunit comprises two domains, a small and a large one. Although, in general, the overall and secondary structure of E. coli enzyme are similar to those of higher animals, some differences of enzymatic action between the enzyme from E. coli and those from higher animals could be explained on the basis of the X-ray structures and molecular mechanics calculation based on them.

Amino Acids↗
PubMed1990

Prognosticating study for cervical myelopathy using evoked spinal cord potentials.

One hundred twenty-three cases of cervical spondylotic and ossification of the posterior longitudinal ligament (OPLL) myelopathy cases with long tract signs subjected to surgical treatment were studied to identify the most important factors having an influence on postoperative outcome using evoked spinal cord potentials (ESCP). Disappearance and positive wave changes of these potentials at the level of responsible lesions and slow conduction velocity under 40 m indicated an unsatisfactory outcome. Localized-lesion cases diagnosed by ESCPs had excellent results, significantly more so than extensive-lesion cases, regardless of operative methods. In 123 cases, 76% were found to have localized lesions, while the other 24% showed extensive lesions. Concerning the difference between CSM and OPLL, 54% of OPLL and only 14% of CSM demonstrated extensive lesions.

Aged↗
PubMed1990

Effect of Tween 80 on the growth of Mycobacterium avium complex.

The effect of Tween 80 on the growth of Mycobacterium avium complex (MAC) in liquid culture condition was investigated. Observation of the colony-forming units (CFU) and the morphology of MAC with transmission and scanning electron microscopy showed that Tween 80 at 0.05% in the medium (ca. 0.5 mg/ml) had bacteriostatic action and caused cell elongation. Tween 80 at 0.5% or more in the medium (ca. 5 mg/ml) reduced the quantity of MAC glycolipids and also led to false positive or positive results in biochemical tests for mycobacterial identification using nitrate reductase, urease, or arylsulfatase. To determine whether or not surfactants could reduce the MAC permeability barrier, the minimal inhibitory concentration (MIC) of antituberculosis drugs on MAC was determined in liquid medium with or without several kinds of surfactants including Tween 80. Five surfactants including Tween 80 increased the activity of antituberculosis drugs to MAC. These findings suggest that Tween 80 acts directly on the cell wall of MAC.

Antitubercular Agents↗
PubMed1990

[Interaction between polyethylene films and brombexine HCl in solid dosage form. II. Effects of moisture property on the sorption of the drug].

The interaction between bromhexine HCl and polyethylene containers was studied in solutions and in tablet packaging systems. Various bromhexine HCl aqueous solutions of different pHs were stored in polyethylene containers at 25 degrees C. The remaining amount of bromhexine HCl was determined by high performance liquid chromatography. It was observed that the transition of bromhexine HCl to polyethylene was inhibited by the addition of some surfactants into the solution, and by lowering the solution pH. In the solid dosage forms, influences of the additives were also studied. It was observed that the decrease of the content of bromhexine HCl in the solid dosage form was inhibited by the addition of acids (citric acid, tartaric acid) and surfactant (sodium dodecyl sulfate) and accelerated by the addition of sodium bicarbonate, similarly to those in solutions. The results indicated that the transition to polyethylene films was influenced by the molecular state of bromhexine HCl.

Adsorption↗
PubMed1990

Variable mutations of the RB gene in small-cell lung carcinoma.

Loss of heterozygosity for chromosome 13q including the RB locus is a common genetic alteration in small-cell lung carcinoma (SCLC) as well as in retinoblastoma. We examined the RB cDNA sequences of exon 13 to 18 and exon 19 to 23 in 9 SCLC cell lines to detect mutations which cause inactivation of the remaining allele of the RB gene. Internal deletions of RB cDNA were observed in 3 of the 9 SCLC cell lines. In the Lu-24 cell line, a 114 base pairs (bp) deletion corresponding to exon 22 was due to abnormal splicing, which probably resulted from a two-base mutation within genomic exon 22, and aberrant 105 kilodaltons RB protein was detected by immunoprecipitation analysis. A base pair deletion within exon 20 in the Lu-135 cell line and a 1 bp deletion within exon 23 in the Lu-141 cell line were due to the deletions of the corresponding genomic DNA, and each deletion resulted in formation of a premature termination codon. These results indicate that both alleles of the RB genes are inactivated in SCLC by several different mechanisms, including small deletion, mutation and chromosomal loss.

Alleles↗
PubMed1990

Synthesis of new bile salt analogues, sodium 3 alpha, 7 alpha-dihydroxy-5 beta-cholane-24-sulfonate and sodium 3 alpha, 7 beta-dihydroxy-5 beta-cholane-24-sulfonate.

This report describes the chemical synthesis of two new bile salt analogues, namely sodium 3 alpha,7 alpha-dihydroxy-5 beta-cholane-24-sulfonate and sodium 3 alpha,7 beta-dihydroxy-5 beta-cholane-24-sulfonate from chenodeoxycholic acid and ursodeoxycholic acid, respectively. Each common bile acid was converted into the corresponding 5 beta-cholane-3,7,24-triol by treatment with ethyl chloroformate in the presence of triethylamine followed by sodium borohydride reduction. Reaction of the cholanetriol with p-toluenesulfonyl chloride at 4 degrees C afforded the partially tosylated product, 24-p-toluenesulfoxy-5 beta-cholane-3,7-diol, which was then treated with sodium iodide to produce 24-iodo-5 beta-cholane-3,7-diol. The 24-iodide was refluxed with sodium sulfite in aqueous ethanol to give the desired sulfonate analogue of the naturally occurring bile acid, chenodeoxycholic acid or ursodeoxycholic acid.

Bile Acids and Salts↗
PubMed1989

Restricted tissue distribution of Mlsa determinants. Stimulation of Mlsa-reactive T cells by B cells but not by dendritic cells or macrophages.

Evidence was sought on the tissue distribution of Mlsa determinants, a class of cell-associated non-H-2 alloantigens that is highly immunogenic for unprimed T cells. Whereas normal CD4+ T cells and an Mlsa-reactive T hybridoma gave strong responses to Mlsa-positive stimulator populations containing Ig+ B cells, anti-Mlsa responses to B-depleted stimulators were almost undetectable. The B-depleted stimulators tested included Thy-1- spleen cells from mu-suppressed mice (mice treated with anti-mu antibody from birth) and J11d- preparations of spleen dendritic cells (DC) and peritoneal macrophages (M phi) from normal mice. Each of these populations was strongly immunogenic for allo-H-2-reactive T cells. The failure to detect Mlsa determinants on Ig- APC, i.e., M phi and DC, suggests that Mlsa determinants are not typical H-2-associated peptides. The data are more compatible with a model in which Mlsa determinants represent (or form part of) an integral cell membrane molecule expressed largely, and perhaps exclusively, on B cells. T cells might recognize these molecules only in native form, "processed" Mlsa determinants being nonimmunogenic. Consistent with this possibility, no evidence was found that Mlsa-negative B cells could absorb Mlsa determinants from Mlsa-positive B cells in a chimeric environment.

Animals↗
PubMed1989

Oronasal fistulae in repaired cleft palates.

The study reviews oronasal fistulae occurring after palatoplasty. Subjects were fifty-two patients who had received palatoplasty in our clinic from 1981 to 1987. In twenty-one cases (40%) oronasal fistulae persisted. Two-thirds of these fistulae were slits or pinholes. The ratio of fistula occurrence was relatively high compared to other reports. Most of them were observed at the junction of the premaxilla and maxilla. There was no significant difference between fistula formation and the distance of the push back, and also there was no correlation with the width of the cleft.

Cleft Palate↗
PubMed1989

Plasmid profiles of Mycobacterium avium complex isolated from swine.

Twenty strains of Mycobacterium avium complex (MAC) isolated from swine and five strains from humans were examined for drug susceptibility and plasmid content. Four strains of swine origin and two strains of human origin harbored plasmid DNAs differing in molecular weights. No relationship between plasmid contents and drug resistance was observed. Southern DNA-DNA hybridization showed that small plasmids from swine MAC strains were homologous to those from human origin at the nucleotide level.

Animals↗
PubMed1989

[Interaction between polyethylene films and bromhexine HCl in solid dosage forms. I. Effects of moisture contents in the solid dosage forms on the sorption of the drug].

The decrease of bromhexine HCl contents in granules and tablets was determined when the preparations were stored in polyethylene film package. Effects of temperature, contact area with film, excipients and moisture contents in the preparation on the remaining amount of bromhexin HCl were studied in order to investigate the interaction mechanism between bromhexine HCl and polyethylene film. It was observed that the decrease of bromhexine HCl was due to the sorption to the polyethylene film. The results indicated that the moisture contents of the dosage forms determined the rate of sorption predominantly, and that removal of adsorbed water from dosage forms was effective to prevent bromhexine HCl content decrease.

Adsorption↗