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Biomedical subjects

R Sato

Publications and source records attributed to R Sato.

At least 325 records · Page 18Linked to original sources
PubMed1987

Structural analysis of cloned cDNAs for polycyclic hydrocarbon-inducible forms of rabbit liver microsomal cytochrome P-450.

Two cDNA clones, pHPah1 and pHPah2, encoding polycyclic hydrocarbon-inducible forms of rabbit liver microsomal cytochrome P-450 were isolated and their nucleotide sequences were determined. The inserts of pHPah1 and pHPah2 contained open reading frames specifying the entire primary structures of cytochrome P-450s, consisting of 518 and 516 amino acid residues, respectively. The deduced amino acid sequences for pHPah1 and pHPah2 are 76 and 73% homologous with rat P-450c and P-450d, respectively, and 96% homologous with rabbit P-450 forms 6 and 4, respectively. We conclude that pHPah1 and pHPah2 encode the rabbit counterparts of rat P-450c and P-450d, respectively. A region highly conserved in all species of cytochrome P-450 so far examined, called the HR2 region, can be detected in the pHPah1 and pHPah2 primary structures, but another conserved region, HR1, cannot be observed. Northern hybridization analysis of total RNAs from livers of untreated and drug-treated rabbits demonstrated that the pHPah1 and pHPah2 genes are expressed in untreated animals, induced considerably by administration of 3-methylcholanthrene or beta-naphthoflavone, and suppressed by phenobarbital and isosafrole.

Amino Acid Sequence↗
PubMed1987

Wavelength Effect on the Action of a N-Phenylimide S-23142 and a Diphenylether Acifluorfen-Ethyl in Cotyledons of Cucumber (Cucumis sativus L.) Seedlings.

Specific wavelengths of light required for expression of phytotoxic activity of S-23142 (N-[4-chloro-2-fluoro-5-propargyloxy]phenyl-3,4,5,6-tetra- hydrophthalimide) and acifluorfen-ethyl (ethyl-5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitro benzoic acid) were determined in cotyledons of cucumber seedlings using the Okazaki Large Spectrograph. Leakage of amino acids from the cotyledons was measured as an indication of the phytotoxic activity. The wavelength effects showed common major peaks of activity at 550 and 650 nanometers and a minor peak at 450 nanometers for both herbicides, indicating a common primary photoreaction. Concomitant application of DCMU (3-[3,4-dichlorophenyl]-1,1-dimethylurea) with S-23142 had little influence on the effective wavelengths for S-23142 activity. Light of 450 and 650 nanometers was relatively less effective in achlorophyllous tissue grown in far red light than in green tissue. These results strongly suggest that the phytotoxic action of S-23142 and diphenylethers involves multiple photoreactions and that one of the photoreceptor pigments may be chlorophyll or its related pigment, although photosynthesis is not involved.

Journal Article↗
PubMed1987

Electrophysiological effects of flecainide on guinea pig ventricular muscle in high [K+]o, acidosis and hypoxia.

The electrophysiological effects of flecainide on the action potential were examined in guinea pig ventricular muscles using microelectrode recording methods. Under the control conditions, flecainide (0.5-1 microgram/ml) did not alter the resting potential, action potential duration (APD) or effective refractory period (ERP). The major effect of flecainide was on maximum upstroke velocity (Vmax), which was depressed in a dose-dependent manner. In high [K+] medium (potassium concentration = 10 mM), Vmax was depressed by 16.8% at a concentration of 1.0 microgram/ml (8.8% in normal [K+]o). In metabolic acidosis (pH = 6.89), it was depressed by 15.7% at the same concentration of the drug (8.3% in normal condition). The changes in ERP and ERP/APD90% in high [K+]o and metabolic acidosis were not significantly different from the normal condition. After hypoxic perfusion for 15 min, Vmax depression by flecainide was 16.3% (7.4% in control medium). The increase of ERP/APD90% was also greater in hypoxia. These data indicate that the most prominent effect of flecainide is Vmax depression which is enhanced under the high K+, acidic and hypoxic conditions. Therefore, it is suggested that flecainide may be most effective for ventricular arrhythmias occurring in myocardial ischemia.

Acidosis↗
PubMed1987

[FT, 5-FU and uracil concentrations of the blood, bile and tissue of hepatoma with liver cirrhosis after oral administration of UFT].

UFT was orally administered to eight patients with hepatocellular carcinoma (HCC) combined with liver cirrhosis and to five patients with normal liver. The concentrations of FT-207 (FT), 5-FU, and uracil in blood, tissue and bile were then respectively determined. The FT level in cancer tissue and non-cancer tissue was almost identical in patients with HCC. On the other hand, the 5-FU level in normal liver tissue was significantly higher (P less than 0.05) than that in cancer tissue, and the uracil level in normal liver tissue was lower than that in cancer tissue (P less than 0.05). Transportation of FT from blood to liver was significantly correlated with clearance of indocyanine green from the blood (ICGK). These results suggested that transportation of FT from blood to liver and activation of FT were impaired in HCC with liver cirrhosis. However, the 5-FU level in the cancer tissue of HCC tended to be higher than that in non-cancer tissue. The 5-FU level in the tissue had a significant correlation with the FT level in the tissue. In addition, it was presumed that cancer tissue was able to produce 5-FU from FT more quickly than non-cancer tissue.

Administration, Oral↗
PubMed1986

Molecular structure of human lymphocyte receptor for immunoglobulin E.

We have isolated and sequenced a cDNA clone encoding the human lymphocyte receptor for IgE (Fc epsilon R). The deduced protein sequence reveals that Fc epsilon R consists of 321 amino acids, without any signal sequence, and is oriented with its N-terminus on the cytoplasmic side and its C-terminus on the outside of the cell. This molecule shows striking sequence homology with chicken asialoglycoprotein receptor (hepatic lectin), suggesting a possible role for Fc epsilon R in endocytosis. Fc epsilon R mRNA is expressed in B cells, B cell lines, and macrophage cell lines. It is not expressed in T cells or T cell lines, with the exception of an HTLV-transformed T cell line. mRNAs expressed in a macrophage line and in the latter T cell line differ in size from mRNA expressed in B cells. Human BSF-1 (or IL-4) induces the expression of Fc epsilon R mRNA in B cells, but not in T cells.

Amino Acid Sequence↗
PubMed1986

Fc epsilon receptor, a specific differentiation marker transiently expressed on mature B cells before isotype switching.

The expression of Fc epsilon R on human lymphocytes was studied with the anti-Fc epsilon R mAbs. Fc epsilon R was expressed on most mu+,delta+ circulating B cells, whereas T cells did not express Fc epsilon R even in patients with hyper-IgE syndrome. B cells with gamma, alpha, or epsilon phenotype did not express Fc epsilon R, moreover its expression could not be induced, suggesting that the Fc epsilon R expression was correlated with isotype switching. mu+delta+ B cells in bone marrow did not express Fc epsilon R, but PHA-sup (supernatant from PHA-stimulated cell cultures) could induce its expression, and the addition of IgE augmented this induction. Recombinant IL-2, IL-1, IFN-gamma or -beta, or purified B cell differentiation factor (BSF-2 B cell-stimulatory factor 2) could not induce Fc epsilon R expression in bone marrow B cells. IFN-gamma inhibited the Fc epsilon R expression induced by PHA-sup, suggesting that the human counterpart of BSF-1 may be responsible for Fc epsilon R expression in bone marrow B cells. B cells from patients with common variable immunodeficiency and ataxia telangiectasia did not express Fc epsilon R, but PHA-sup could induce its expression, indicating that circulating B cells of these patients are at a differentiation stage similar to B cells in bone marrow. The study showed that Fc epsilon R is a B cell-specific differentiation marker, the expression of which is restricted to a defined stage of B cell differentiation.

B-Lymphocytes↗
PubMed1986

Monoclonal anti-Fc epsilon receptor antibodies with different specificities and studies on the expression of Fc epsilon receptors on human B and T cells.

Three monoclonal antibodies, 1-7 (gamma 2b), 3-5 (gamma 1), and 8-30 (mu), specific to Fc epsilon receptors (Fc epsilon R) on human B cells were established. The two monoclonals (1-7 and 8-30) could inhibit the binding of IgE to Fc epsilon R in rosette formation assays, as well as FACS analysis, and were shown to recognize the same epitope of Fc epsilon R. The other monoclonal antibody (3-5) recognized the same molecule but a different epitope, and marginally inhibited the IgE binding. The molecules on RPMI 8866 cells recognized by these monoclonal antibodies had Mr of 46,000 and 25,000 to 30,000 daltons as determined by immunoprecipitation and SDS-PAGE analysis. By employing these monoclonal antibodies, the expression of Fc epsilon R on circulating lymphocytes was studied. Approximately 50% of B cells from normal, nonatopic individuals were found to express Fc epsilon R, and a remarkable increase in the expression of Fc epsilon R was observed in B cells of atopic patients. The expression of Fc epsilon R was not detected in T cells from atopic patients (including hyper IgE syndrome) as well as normal individuals. Incubation of B cells with PHA-conditioned medium plus IgE augmented the expression of Fc epsilon R in the Fc epsilon R+ B cell population but not in Fc epsilon R- population. PHA-conditioned medium plus IgE did not induce Fc epsilon R expression on T cells.

Antibodies, Monoclonal↗
PubMed1986

Delineation and characterization of human B cell subpopulations at various stages of activation by using a B cell-specific monoclonal antibody.

Human tonsillar B cells were separated into three distinct subpopulations, Ba-/IgD+, Ba+/IgD+, and Ba+/IgD-, by using a B cell-specific monoclonal antibody (anti-Ba) that recognizes only activated B cells, and anti-IgD antibody. Stimulation of Ba-/IgD+ cells with anti-mu plus PHA-conditioned culture supernatant (PHA-sup) or TPA induced Ba+/IgD+ cells, which reverted to Ba-/IgD+ phenotype in the absence of continuous stimulation. Further stimulation of Ba+/IgD+ cells with several B cell activators, such as TPA plus anti-mu or PWM plus T cells, resulted in the loss of IgD expression. Three-color FACS analysis showed that the expression of transferrin receptor (TFR) was at its maximum in Ba+/IgD- cells, and the intensity of this expression was proportional to that of Ba expression in Ba+/IgD+ cells. PHA-sup induced maximum proliferation in Ba+/IgD- cells, and the degree of response was a function of the intensity of Ba expression in Ba+/IgD+ cells. PHA-sup or purified BCDF (BSF-2) induced Ig secretion preferentially in Ba+/IgD- cells. Taken together, these results show that resting B cells (Ba-/IgD+) are activated into Ba+/IgD+ cells, and then into Ba+/IgD- cells, under mitogenic stimulation, and BCDF induces the final maturation of Ba+/IgD- cells into Ig-secreting cells. Ba+/IgD- cells, which maximally expressed TFR as well as Ba and displayed maximum proliferative response to PHA-sup, did not express any Tac antigen. On the other hand, in vitro activated B cells expressed Ba and TFR as well as Tac antigen.

Antibodies, Anti-Idiotypic↗
PubMed1986

Expression and function of an early activation marker restricted to human B cells.

A B cell-specific monoclonal antibody (anti-Ba) was prepared. In two-color FACS analysis the anti-Ba reacted with a subpopulation of Ig+ or B1+ cells obtained from tonsils, but did not react with most B1+ cells derived from PBL. Activation of B cells from PBL with TPA or anti-mu induced Ba expression and the addition of PHA-conditioned supernatant with anti-mu-enhanced Ba expression. Other B cell activators, such as Staphylococcus aureus Cowan I (Staph-A) or PWM plus T cells, could induce Ba expression. Ba expression was observed 6 hr after stimulation and reached a peak level at 72 hr. Ba expression was strictly restricted to B cells. H-7, a specific inhibitor of protein kinase C (C-kinase), displayed a dose-dependent inhibitory effect on Ba expression, showing dependency on C-kinase for Ba expression. Anti-Ba inhibited B cell proliferation induced by anti-mu and B-BCGF distinct from BSF-1. The results presented in this study suggest that the Ba antigen on B cells may be comparable to the Tac antigen on T cells.

Animals↗
PubMed1986

Selectivity of cerebral vasodilators on basilar arteries.

Ca-antagonistic activities of cerebral vasodilators, nicardipine and 1-(3,4-dimethoxyphenyl)-2-(4-diphenylmethylpiperazinyl)ethanol dihydrochloride (NC-1100) were tested on basilar and renal arteries, thoracic aorta and portal vein of rabbit, and rat vas deferens. Both the cerebral vasodilators used herein had a selectivity to basilar arteries. The selectivity to the basilar arteries is considered to be one of the factors in deciding the pharmacological property of the cerebral vasodilators.

Animals↗