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Biomedical subjects

Y Hokama

Publications and source records attributed to Y Hokama.

At least 55 records · Page 3Linked to original sources
PubMed1988

Purification and characterization of two forms of chicken liver cytochrome P-450 induced by 3,4,5,3',4'-pentachlorobiphenyl.

3,4,5,3',4'-Pentachlorobiphenyl (PenCB), one of the most potent 3-methylcholanthrene (MC)-type inducers of hepatic enzymes in animals, caused a remarkable induction of liver microsomal monooxygenases, particularly 7-ethoxyresorufin (7-ER) O-deethylase, benzo(a)pyrene (BP) 3-hydroxylase, and testosterone 16 alpha-hydroxylase in chickens, but not NADPH-cytochrome c(P-450) reductase and cytochrome b5. Two forms of cytochrome P-450 (P-450) in liver microsomes of PenCB-treated chickens were purified and characterized. The absorption maxima of the CO-reduced difference spectra of both enzymes (chicken P-448 L and chicken P-448 H) were at 448 nm. From the oxidized form of their absolute spectra, chicken P-448 L was a low-spin form and chicken P-448 H was a high-spin form. They had molecular masses of 56 and 54 kDa, respectively. In a reconstituted system, 7-ER O-deethylation, BP 3-hydroxylation, and testosterone 16 alpha-hydroxylation were catalyzed at high rates by chicken P-448 L but not by chicken P-448 H. Chicken P-448 L also catalyzed N-demethylation of aminopyrine, benzphetamine, and ethylmorphine with relatively low activity. On the other hand, chicken P-448 H functioned only in catalyzing estradiol 2-hydroxylation. These results were supported by an inhibition study of microsomal monooxygenases using an antibody against each enzyme. Immunochemical studies revealed that the enzymes differ from each other but are both inducible by PenCB-treatment. Chicken P-448 L and chicken P-448 H respectively comprise about 82 and 7% of the total P-450 content in chicken liver microsomes.

Animals↗
PubMed1988

Myelin basic protein as a possible marker for oligodendroglioma.

To search for a marker for oligodendroglioma, immunohistochemical analysis of myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP) were performed on tissues from 38 oligodendrogliomas. MBP was detected in 14 such tumors, positive cells being characterized by having rather rich cytoplasm containing a large nucleus and a prominent nucleolus. They seemed to be relatively poorly differentiated cells corresponding to oligodendroglioma grade II in the WHO classification, and appeared to have some cytological resemblance to immature oligodendrocytes in the newborn brain. Mature grade I tumor cells with a small dark nucleus and a perinuclear halo, and grade III anaplastic cells were MBP-negative. GFAP-positive cells were also found in tumors containing MBP-positive cells. A double immunostain for MBP and GFAP demonstrated that some tumor cells were simultaneously stained with both. Presumably the oligodendroglioma cells that showed such dual immunostaining would intrinsically express a myelin-forming glial phenotype. MBP may be applicable as a marker for oligodendrogliomas.

Biomarkers, Tumor↗
PubMed1987

Comparison of DT-diaphorases purified from the liver cytosol of untreated, and 3,4,5,3',4'-pentachlorobiphenyl- and 3-methylcholanthrene-treated rats.

DT-Diaphorase purified from the liver cytosol of rats treated with a highly toxic PCB congener, 3,4,5,3',4'-pentachlorobiphenyl (PenCB), was compared to those from 3-methylcholanthrene (MC)-treated and untreated rats. Treatments with PenCB and MC resulted in about 8- and 7-fold increases of cytosolic DT-diaphorase activity, respectively. Purification of the enzyme preparations from untreated, and PenCB- and MC-treated rats were conducted by using DE-52, DEAE-Sephadex A-50, hydroxylapatite, and Bio-Gel P-150 column chromatographies. Both Sephadex G-100 gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that all of the final preparations from the three origins were homogeneous and had the same molecular weight of 59,000, consisting of two subunits with molecular weights of 30,000. Further studies on amino acid composition, Km value, optimum pH, and catalytic activities for various substrates also indicated that both PenCB- and MC-inducible DT-diaphorases were identical with that from the untreated rats. All three DT-diaphorases contained about 2 mol of FAD per mol of enzyme. Partial digestion of the enzymes by trypsin and subsequent analysis by HPLC revealed that the three preparations were indistinguishable. The identity among the three purified DT-diaphorases was finally confirmed by Ouchterlony immunodiffusion employing anti-serum raised against each enzyme preparation.

Amino Acids↗
PubMed1987

Gambierdiscus toxicus in gut content of the surgeonfish Ctenochaetus strigosus (herbivore) and its relationship to toxicity.

Flesh of surgeonfish, Ctenochaetus strigosus, obtained from corresponding catches of C. strigosus implicated in ciguatera poisoning outbreaks was examined for ciguatoxin and related polyethers by the stick test enzyme immunoassay. Simultaneously, gut contents of the fish were examined under phase microscopy for the presence of Gambierdiscus toxicus. Eighty-seven per cent of the fish were stick EIA positive, while 98% were positive for G. toxicus in gut contents. The data obtained suggest a relationship between G. toxicus in gut content and tissue toxicity levels. This is in agreement with previous studies which demonstrated a relationship between G. toxicus in fish gut content and toxicity of the flesh to animals and humans.

Animals↗
PubMed1986

[MBP and GFAP immunohistochemistry of oligodendrogliomas with relationship to myelin-forming glia in cell differentiation].

The histologic feature of oligodendroglioma is constituted by the monotonously arranged sheets of tumor cells intersected with delicate vascular stroma. The shape of the tumor cells is usually uniform and occasionally rather pleomorphic. In order to clarify biological characteristics of the tumor cells at level of cell differentiation, immunohistochemical stains for myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP) with PAP method were performed on 13 oligodendrogliomas obtained by surgical removal. The cells stained positive with MBP immunostain were encountered in 5 tumors and their incidence was ranging from 1% to more than 30% of all tumor cells. The MBP-positive cells were characterized by having a large clear nucleus with a prominent nucleolus and relatively abundant cytoplasm, that seemed to mimic myelin-forming glia appearing in normal developing brain. The cells with poor cytoplasm or surrounded by a perinuclear halo were MBP-negative, and the pleomorphic cells in majority of anaplastic oligodendrogliomas were also negative. On the other hand, with GFAP stain the positive cells were observed in 8 tumors. It is still controversial to interpret the occurrence of GFAP-positive cells in oligodendrogliomas. In this study the GFAP-positive cells were morphologically identical to the MBP-positive cells, so that both MBP and GFAP are supposed to exist in the same tumor cells. It is assumed that some of oligodendroglioma cells which showed such immunostainabilities could possess an intrinsic character to express a phenotype of myelin-forming glia. Possibly, MBP substance is applicable as one of immunohistochemical markers for oligodendroglioma cells to indicate a certain cell differentiation.

Adult↗
PubMed1986

Significant enhanced superoxide anion (O2-) production in vitro by peripheral blood monocytes of lepromatous leprosy patients stimulated with liposome and suppression by C-reactive protein (CRP).

Peripheral blood monocytes (PBM) from normal individuals, infectious mononucleosis (IM) and leprosy patients were stimulated with liposome. The mean and standard error of superoxide anion (O2-) generated in nm/1.5 X 10(5) PBM/well for 5 normal subjects and 3 IM patients was 2.9 +/- 0.5 and 3.1 +/- 0.2, respectively. Monocytes stimulated with 100 ng C-reactive protein (CRP) incorporated into liposome gave values of 3.3 +/- 0.3 and 2.7 +/- 0.1 nm O-2/1.5 X 10(5) PBM/well for normals and IM, respectively. No significant differences in O2- production between liposome and liposome with incorporated CRP were shown. PBM from lepromatous patients demonstrated a significant (p less than 0.01) increase in O2- production with liposome alone compared with tuberculoid patients (3.5 +/- 0.4 vs 1.8 +/- 0.3). The most dramatic suppression of O2- shown when purified CRP was added to the mixtures in all groups examined [0.4 +/- 0.1 (500 ng), 0.3 +/- 0.0 (500 ng), 1.5 +/- 0.1 (100 ng), and 1.3 +/- 0.6 (100 ng) nm O2-/1.5 X 10(5) PBM/well for normals, IM, lepromatous, and tuberculoid, respectively]. Results of O2- formation with incorporation of CRP into liposome as compared with liposome alone had no significant effect on PBM of lepromatous or tuberculoid patients. It is suggested that CRP may play a significant role in regulation of oxygen free radicals formed during acute and chronic inflammatory episides.

C-Reactive Protein↗
PubMed1985

Difference of lectin binding sites of secretory granules between normal pituitary and adenoma cells.

Electron-immunocytochemical staining with lectin (concanavalin A: Con A) binding sites analysis was applied to study secretory granules of human pituitary adenomas and surrounding normal pituitary tissue using post-embedded serial ultrathin sections. Twelve cases of human pituitary adenoma and three specimens of normal pituitary tissue surrounding adenomas were studied: the cases were operated on between 1982 and 1984. The tumors consisted of four prolactin (PRL)-, six growth hormone (GH)-, and two adrenocorticotropic hormone (ACTH)-producing adenomas. In parallel with the detection of Con A binding sites of secretory granules, their secreting hormones were characterized electron-microscopically with the immunocytochemical horseradish peroxidase (HRP) labeling using the avidin-biotin technique. The two cases of ACTH-producing adenomas showed either weak or negative reactions with Con A on secretory granules, while normal ACTH-producing pituitary cells showed strong reactions with Con A on every secretory granule observed. Large secretory granules of PRL- or GH-producing cells showed negative reactions with Con A both in the pituitary adenoma and normal pituitary, while some small granulated or sparsely granulated adenoma cells also showed strong reactions with Con A. The complexity of human pituitary adenomas is illustrated as well as the difference in biochemical structure of normal pituitary cells and pituitary adenoma cells secreting the same specific hormone.

Adenoma↗
PubMed1985

A rapid, simplified enzyme immunoassay stick test for the detection of ciguatoxin and related polyethers from fish tissues.

A simplified and rapid enzyme immunoassay stick test is presented in this study. The salient feature of this test is the use of a coating (Liquid Paper) on the stick to adsorb the lipid ciguatoxin and its related polyether toxins onto the stick. This rapid solid phase stick test has been able to differentiate clinically implicated fishes (14 samples) from non-toxic (60 samples) with P less than 0.005. Comparison of the stick test with the enzyme immunoassay procedure with the positive fish samples demonstrated a good correlation. All samples were positive by both procedures. Further comparison of the stick test, enzyme immunoassay and the mouse bioassay with unknown fish samples showed good relationships between the three procedures. Examination of 71 Seriola dumerili, a fish generally implicated in ciguatera poisoning, with the stick test procedure showed that 89% of the fishes were non-toxic and thus consumed without any incidence of ciguatera poisoning. Analysis of graded concentrations of ciguatoxin, in ng/ml of methanol, showed a typical immunological precipitation pattern. The stick test as conceived is simple and rapid, while retaining its sensitivity and specificity to detect ng levels of ciguatoxin and its related polyether toxins. It is suggested that the stick test will be valuable in the screening of ciguatoxin and related polyether toxins in contaminated fish tissues.

Animals↗
PubMed1985

Accumulation, excretion and effects on hepatic enzymes of polychlorinated quaterphenyl congeners in rats.

Six skeletal congeners of polychlorinated quaterphenyls (PCQs), namely polychlorinated o-quaterphenyl (2,2'-PCQ), 2,3'-diphenylbiphenyl (2,3'-PCQ), 2,4'-diphenylbiphenyl (2,4'-PCQ), m-quaterphenyl (3,3'-PCQ), 3,4'-diphenylbiphenyl (3,4'-PCQ) and p-quaterphenyl (4,4'-PCQ), were orally administered to Wistar rats at a dose of 10 mg/rat. On the 5th day after administration of PCQs, the rats were examined for accumulation of PCQ congeners, hepatic enzyme activities and organ weight changes. Accumulation of 3,3'-PCQ, 3,4'-PCQ and 4,4'-PCQ were 1.5-3.2% of dose in the liver, while those of 2,2'-PCQ, 2,3'-PCQ and 2,4'-PCQ were only 0.1 to 0.2%. The amount of 4,4'-PCQ accumulated in the mesenteric adipose tissue, 20 micrograms/rat, was much higher than those of other PCQ congeners. Large amounts of the PCQ congeners administered were excreted in the feces on the first day, accounting for 96 to 98% of dose for 2,2'-PCQ and 4,4'-PCQ, and 55 to 75% for the other PCQ congeners, and the daily excretions of PCQs after the second day were very small, less than 10% of the dose. Benzo [a] pyrene 3-hydroxylase activity was significantly depressed by the treatment with 3,3'-PCQ, 3,4'-PCQ and 4,4'-PCQ, contrasting to the toxic congeners of polychlorinated biphenyls and dibenzofurans which enhanced markedly this enzyme activity. DT-Diaphorase activity was also depressed by the treatment with 2,3'-PCQ, 2,4'-PCQ and 3,4'-PCQ. Significant atrophy of the thymus was observed by the treatment with 4,4'-PCQ.

Adipose Tissue↗
PubMed1985

Inductive effect on hepatic enzymes and toxicity of congeners of PCBs and PCDFs.

The present paper describes a marked induction of liver microsomal cytochrome P-450 and cytosolic DT-diaphorase to cause possible disorder of steroid homeostasis and promotion of carcinogenicity of 4-nitroquinoline N-oxide (4-NQO) in rats by pretreatment with 3,4,5,3',4'-pentachlorobiphenyl (PenCB) or 2,3,4,7,8-pentachlorodibenzofuran (PenCDF). The animals were sacrificed 5 days after the pretreatment. These induction experiments showed that 7 alpha-hydroxylation of both progesterone and testosterone in liver microsomes was selectively increased to a great extent, but hydroxylations at the 2 alpha-, 6 beta- and 16 alpha-positions were depressed, together with 5 alpha-reduction. From the same microsomes, three of the strongly induced P-450 isozymes, i.e., high- and low-spin P-448s and P-452, were purified. The last isozyme was most responsible for 7 alpha-hydroxylation of testosterone. The pretreatment, also increased activity of DT-diaphorase and reduction of 4-NQO about 10-fold in liver 9000g supernatants. This reduction of 4-NQO was solely catalyzed by DT-diaphorase and the only product was 4-hydroxylaminoquinoline N-oxide, a proximate carcinogen, indicating that the pretreatment strongly increased production of a proximate carcinogen from 4-NQO. Such an enhancement of the metabolic activation of 4-NQO by the pretreatment was also observed to some extent in the lung and the skin. Persistency of PenCB and PenCDF in the liver of rats was also discussed.

4-Nitroquinoline-1-oxide↗
PubMed1984

Immunologic basis for the pathogenesis of pterygium.

We examined surgically excised pterygial tissues from 26 patients for the various immunoglobulin classes by direct immunofluorescence. Of the 26 patients, 19 (73.1%) showed positive staining with goat anti-human IgG fluorescein-labeled antibody. Direct immunofluorescence with goat anti-human IgE fluorescein-labeled antibody was found in all 26 samples, varying in fluorescent intensity from 1+ to 4+. Routine histologic staining disclosed an infiltration of small lymphocytes and plasma cells into the pterygium. These results suggest that an immunologic mechanism, possibly Type 1 hypersensitivity, may contribute to the pathogenesis of pterygium.

Dust↗
PubMed1984

Amino acid sequence of Japanese horseshoe crab (Tachypleus tridentatus) coagulogen B chain: completion of the coagulogen sequence.

The complete amino acid sequence of the B chain derived from Tachypleus tridentatus coagulogen was determined. It consisted of a total of 129 amino acid residues with a NH2-terminal glycine and COOH-terminal phenylalanine. Sequence studies of the whole B chain and the fragments obtained from the digests with trypsin, alpha-chymotrypsin, thermolysin and Staphylococcal protease V8 showed the following sequence: (sequence; see text) These structural studies of the B chain and the previously established amino acid sequences of the A chain and peptide C derived from T. tridentatus coagulogen, now make it possible to complete the whole sequence of coagulogen consisting of 175 amino acid residues with the molecular weight of 19,723.

Amino Acid Sequence↗
PubMed1984

Effects of adriamycin on the macromolecular synthesis in rat myocardiocytes and KB cells.

Effects of adriamycin on cardiomyocytes and KB cells have been examined. Adriamycin inhibited DNA and RNA synthesis in both rat myocardial cells and KB cells. Protein synthesis was also inhibited but at a much higher dosage. In myocardiocytes, protein synthesis was dose-dependent with inhibition being almost complete at 100 microM. In contrast, inhibition of protein synthesis in KB cells leveled off at 50%.

Animals↗