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Biomedical subjects

H Oka

Publications and source records attributed to H Oka.

At least 379 records · Page 21Linked to original sources

Contribution of hepatic reticuloendothelial system to glomerular IgA deposition in rat liver injury.

Liver damage was induced in rats by a single dose of dimethylnitrosamine or D-galactosamine. In the dimethylnitrosamine model, marked glomerular IgA deposition occurred between Days 4 and 28, with its peak at Day 14. Serum IgA levels were significantly increased at Days 2 and 4, then gradually decreased, and normalized at Day 14. In the D-galactosamine model, however, no such deposition was observed, though serum IgA levels similarly increased on Days 2 and 4. IgA content in high molecular weight fraction from serum increased at Day 3 in both models. This increment remained at Day 7 only in the dimethylnitrosamine model, in which carbon clearance from the circulation was significantly decreased at Day 3. These data suggest that dysfunction of the hepatic reticuloendothelial system is a factor contributing to glomerular IgA deposition occurring in liver injury.

Alanine Transaminase↗

Morphology of layer V pyramidal neurons in the cat somatosensory cortex: an intracellular HRP study.

Pyramidal tract (PT) or corticopontine neurons of the cat somatosensory cortex (SI) were identified with antidromic activation on stimulation of the bulbar pyramid or pontine nuclei (PN) and stained intracellularly with HRP after examining the electrophysiological properties. Comparison of the conduction velocity of the stem axons and the soma-dendritic morphology revealed that in the cat SI, there exists two types of layer V pyramidal neurons, i.e. one has smooth apical dendrites with larger soma (51.6 +/- 9.5 x 22.7 +/- 2.8 micron) and the other has richly spinous apical dendrites with smaller soma (34.0 +/- 8.8 x 15.3 +/- 3.3 micron). The former group responded antidromically at latencies shorter than 1 ms by PT stimulation or 1.5 ms by PN stimulation, respectively. These values were consistent with the borderline latencies between two similar groups of layer V pyramidal neurons in the motor (fast and slow PTNs) and parietal (aspiny and spiny layer V corticopontine neurons) cortices in the cat.

Afferent Pathways↗

Improvement of chemical analysis of antibiotics. XIII. Systematic simultaneous analysis of residual tetracyclines in animal tissues using thin-layer and high-performance liquid chromatography.

A simultaneous analytical system for residual tetracycline antibiotics (TCs) in animal tissues including liver has been developed. This system consists of three methods using Baker 10 C18 clean-up followed by high-performance liquid chromatography (method A), thin-layer chromatography (TLC)-UV densitometry (method B) and TLC with spray reagents (method C). Methods A and B were established for the precise determination of TCs and method C for universal screening. The recoveries from beef liver fortified at the level of 1.0 ppm and their coefficients of variation were 60.5-83.3% and 2.3-3.9% (method A) and 58.1-92.8% and 1.0-3.7% (method B), respectively. The detection limits in animal tissues were 0.01 ppm (method A) and 0.1 ppm (methods B and C). The time required for the analysis of four samples was 2.5-3 h with each method.

Animals↗

Simple method for the analysis of food dyes on reversed-phase thin-layer plates.

A technique for the determination of food dyes using reversed-phase thin-layer chromatography on octadecyl-modified silica is described. A solvent system containing 5.0% aqueous sodium sulphate solution enables good separation of the food dyes. Their separation is dependent on the pH of the solvent system, good separation among all dyes being obtained between pH 6.0 and 7.0. The determination of thirteen dyes can be achieved by a combination of methanol-acetonitrile-5.0% aqueous sodium sulphate solution (3:3:10) (solvent system A) and methanol-methyl ethyl ketone-5.0% aqueous sodium sulphate solution (1:1:1) (solvent system B). Solvent system A was used for the determination of Tartrazine, Amaranth, Indigo Carmine, New Coccine, Sunset Yellow FCF, Allura Red AC, Fast Green FCF and Brilliant Blue FCF and for the screening of Acid Red (R-106), Eosin (R-103), Erythrosin (R-3), Rose Bengale (R-105) and Phloxine (R-104). When the spots of R-3, R-103, R-104, R-105 and R-106 appear on the plate, their determination can be achieved by using solvent system B. Each calibration graph was linear between 0.2 and 1.0 micrograms.

Chromatography, Thin Layer↗

Morphological features of layer V pyramidal neurons in the cat parietal cortex: an intracellular HRP study.

Layer V pyramidal neurons in the cat parietal cortex (areas 5 and 7) were investigated with intracellular HRP staining. Antidromic responses were recorded intracellularly as well as extracellularly with pontine stimulation under Nembutal anesthesia. The relationship between the latency of antidromic responses and the morphology of HRP-stained neurons was analyzed. A total of 65 neurons were stained with HRP, and sixteen of these neurons were activated antidromically with pontine stimulation. Two distinct groups of layer V pyramidal neurons were detected morphologically by intracellular HRP staining; i.e., one (F type) consisted of neurons with relatively large somata (58.4 +/- 8.1 micron X 24.5 +/- 5.1 micron, N = 11) and aspiny or sparsely spinous apical dendrites, and the other (S type) consisted of neurons with smaller somata (44.6 +/- 7.6 micron X 19.3 +/- 3.9 micron, N = 22) and richly spinous apical dendrites. These two groups showed different electrophysiological properties; i.e., the former responded antidromically to pontine stimulation at a latency shorter than 1.5 ms (namely, with a conduction velocity faster than 18 m/second) and the latter responded at a latency longer than 1.5 ms. The two neuronal types in the parietal cortex corresponded respectively to fast and slow pyramidal tract neurons (PTNs) investigated in the sensorimotor cortex. Although their morphological features were almost similar to those of PTNs, the branching pattern of apical dendrites of the F-type pyramidal neuron seemed to be different from that of fast PTNs. In the parietal cortex, apical dendrites of F-type neurons showed rather frequent branching in layer I. This was similar to the pattern of branching in slow PTNs. Such a characteristic branching pattern suggested that, in the cat parietal cortex, layer V pyramidal neurons of both types are adapted to receive cerebellar inputs through the ventroanterior (VA) thalamic nucleus to the superficial cortical layers.

Action Potentials↗

Synergism between subthreshold concentrations of thrombin and 12-O-tetradecanoylphorbol 13-acetate in platelet activation.

A comparison was made between the time courses and interdependence of platelet aggregation, serotonin release, and cytosolic free Ca2+ concentration in the same sample of platelets loaded with [14C]-serotonin and Ca2+-sensitive photoprotein aequorin. In 100 micrograms/ml aspirin-treated platelets, neither 0.01 U/ml thrombin nor 50nM TPA, an active phorbol ester, induced significant aggregation, serotonin release, or a rise in the intracellular calcium concentration. However, when these two agents were added together, marked aggregation and release were observed without a change in the cytosolic free Ca2+ concentration. No correlation was observed between the extent of the synergistic effects and time of preincubation with TPA. Potentiatory effects of protein kinase C on receptor-mediated agonists need to be considered in platelet activation.

Blood Platelets↗

Improvement of chemical analysis of antibiotics. XII. Simultaneous analysis of seven tetracyclines in honey.

An analytical system for the simultaneous determination of residual oxytetracycline, tetracycline, chlortetracycline, doxycycline, methacycline, demethylchlortetracycline and minocycline in honey has been established by a combination of simple thin-layer chromatographic (TLC) and precise high-performance liquid chromatographic (HPLC) methods. In this system, screening by TLC can detect tetracyclines (TCs) at a level of 0.1 ppm in honey without the need for special equipment, and the quantitative method by HPLC can determine TCs with good recovery (83.7-99.6%) and coefficient variation (0.9-4.3%).

Chromatography, High Pressure Liquid↗

Improvement of chemical analysis of antibiotics. XI. Simultaneous fluorodensitometric determination of polyether antibiotics.

A simultaneous determination of three polyether antibiotics, salinomycin, monensin and lasalocid, was established by silica gel and RP-18 high-performance thin-layer chromatography (HPTLC) using 18,19-dihydrosalinomycin and 18,19-dihydro-20-ketosalinomycin as internal standards. Fluorescent derivatives of the polyethers were prepared by reaction of their sodium salts with 1-bromoacetylpyrene and Kryptofix 222 in acetonitrile. A silica gel HPTLC plate with carbon tetrachloride-ethyl acetate-acetonitrile (50:5:10) as a solvent system and a RP-18 HPTLC plate with dichloromethane-ethyl acetate-acetone-acetonitrile (15:2:1:55) gave satisfactory separations of the five pyrenacyl esters of salinomycin, monensin, lasalocid, 18,19-dihydrosalinomycin and 18,19-dihydro-20-ketosalinomycin. Under these conditions the internal standard 18,19-dihydrosalinomycin was found to be suitable for the simultaneous determination of salinomycin and monensin, and 18,19-dihydro-20-ketosalinomycin for lasalocid. A linear relationship was obtained between the fluorescence intensity and the amount of each antibiotic in the range 2-14 ng. The detection limit of the three antibiotics was 100 pg.

Chromatography, Thin Layer↗

Effects of teleocidin on the morphology and c-myc expression of hepatoma cells which are not inhibited by protein kinase antagonists.

PLC/PRF/5 hepatoma cells cultured with a tumor promoter teleocidin showed polygonal cellular appearance with many vacuole-like structures, and reduced both c-myc mRNA level and growth rate. These teleocidin effects were partly mimicked by sodium butyrate but not by a protein kinase C stimulant 1-oleoyl-2-acetylglycerol(OAG). Protein kinase C inhibitor 1-(5-isoquinolinyl-sulfonyl)-2-methyl-piperazine(H7), calmodulin-dependent protein kinase antagonist N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide(W7) and topoisomerase II inhibitor novobiocin failed to inhibit the effects of teleocidin. These results may suggest the presence of still unknown biochemical pathways which mediate the actions of teleocidin.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

Improvement of chemical analysis of antibiotics. X. Determination of eight tetracyclines using thin-layer and high-performance liquid chromatography.

Analytical methods for eight tetracyclines (TCs) were established using silica gel high-performance thin-layer chromatography (HPTLC), reversed-phase thin-layer chromatography (RP-TLC) and high-performance liquid chromatography (HPLC). Good separations of eight TCs were obtained using chloroform-methanol-5% disodium ethylenediaminetetraacetate solution (65:20:5) (lower layer) and methanol acetonitrile 0.5 M oxalic acid solution (1:1:4) (pH 3.0) on silica gel HPTLC and C8 TLC plates, respectively. A combination of HPTLC and RP-TLC made possible the identification of the eight TCs. Each calibration graph was linear between 0.1 and 1.0 microgram using UV densitometry except for rolitetracycline. For detection reagents, the diazonium salts including Fast Violet B gave variously coloured spots with the eight TCs and good sensitivities were obtained except with minocycline. In HPLC, the simultaneous analysis of the eight TCs on a C8 column was possible using methanol-acetonitrile-0.01 M oxalic acid solution (1:1.5:7) adjusted to pH 3.0 as the mobile phase. A linear relationship was obtained between 1.0 and 10 ng using the usual sample preparation except for rolitetracycline. The direct determination of rolitetracycline was possible using tetrahydrofuran, dimethyl sulphoxide and the mobile phase as solvents for preparation of the sample. For the determination of residual rolitetracycline, it was effective to measure the amount of rolitetracycline as tetracycline by HPLC, HPTLC and RP-TLC after conversion of rolitetracycline to tetracycline by incubating for 5 min in methanol at 50 degrees C.

Anti-Bacterial Agents↗

Antibody that recognizes conformations of calmodulin in the serum from patient with chronic active hepatitis.

According to the effects of Ca++ on the reactivity, anti-calmodulin antibody in the sera of patients with autoimmune chronic active hepatitis was classified into three types, which were tentatively designated as type 1, 2 and 3. Type 1 antibody reacted with calmodulin only in the presence of free Ca++. Binding of type 2 antibody to calmodulin was inhibited by the presence of free Ca++. Type 3 antibody reacted with calmodulin regardless of the presence or absence of free Ca++. Thus the sera contained the populations of the antibody which recognized the different conformations of calmodulin molecule.

Autoantibodies↗

Improvement of chemical analysis of antibiotics. IX. A simple method for residual tetracyclines analysis in honey using a tandem cartridge clean-up system.

A simple, rapid and precise analytical method for the residual tetracyclines in honey has been established using a tandem cartridge clean-up system (prepacked reversed-phase and ion-exchange cartridges) followed by high-performance liquid chromatography. The recoveries of oxytetracycline (OTC), tetracycline (TC), chlortetracycline (CTC) and doxycycline (DC) from honey spiked at a level of 1.0 ppm are 87.1, 85.3, 98.0 and 99.0%, respectively, with coefficients of variation of 1.1-3.9%. The detection limits in honey are 0.02 ppm for OTC and TC, and 0.05 ppm for CTC and DC, respectively. The time required for the analysis of four samples is only 1 h.

Anti-Bacterial Agents↗