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Biomedical subjects

H Oka

Publications and source records attributed to H Oka.

At least 307 records · Page 17Linked to original sources
PubMed1990

A case of inflammatory pseudotumor of the gallbladder and bile duct.

A rare cause of obstructive jaundice is presented. A 43-yr-old man developed jaundice with fever and weight loss, and showed lymphadenopathy, reticular shadows on chest roentgenogram, deranged liver function tests, eosinophilia, low values of complement proteins, and hypergammaglobulinemia. There was a stricture throughout the bilateral hepatic ducts and common hepatic and bile ducts with dilated intrahepatic bile ducts on imagings. The walls of the gallbladder and common bile duct were thickened due to diffuse granulomatous lesions of unknown etiology, composed mainly of plasma cells, lymphocytes, and fibroblasts identical with inflammatory pseudotumor. The same histological findings also were observed in the lung and lymph nodes. Jaundice disappeared, with reduced thickening of the common bile duct wall. All clinical and laboratory abnormalities subsided after high-dose prednisolone therapy, starting when dyspnea developed. There is no similar case in the literature.

Adult↗
PubMed1989

Foam counter-current chromatography of bacitracin. I. Batch separation with nitrogen and water free of additives.

A foam counter-current chromatographic method utilizing a true counter-current movement between nitrogen and distilled water through a long narrow coiled tube is described. Samples introduced into the coil are separated according to their foaming capability: foam-active materials generate foam and quickly move with nitrogen toward one end of the coil while the remainder are carried with the liquid stream in the opposite direction and eluted through the other end of the coil. The utility of the method was demonstrated in the fractionation of commercial bacitracin (BC). Hydrophobic components including BC-A, BC-F and several minor components were enriched with foam and collected in decreasing order of hydrophobicity, whereas hydrophilic components were eluted with the liquid in decreasing order of polarity. The results indicate that foam-active components can be effectively separated by foam counter-current chromatography using nitrogen and distilled water without a surfactant or other additives.

Bacitracin↗
PubMed1989

Allopurinol inhibits uric acid accumulation in the rat brain following focal cerebral ischemia.

Uric acid (UA) in the rat brain was measured by HPLC with an electrochemical detector following focal ischemia. At 24 h after the operation, the UA level in the ischemic center was 105.47 +/- 8.39 nmol/g tissue, whereas it was 8.36 +/- 1.86 in the sham-operated group. Allopurinol, xanthine oxidase inhibitor, almost completely inhibited this UA accumulation. These data demonstrate that the UA increase in the ischemic brain is due to the xanthine oxidase reaction.

Allopurinol↗
PubMed1989

Multilayer coil planet centrifuge for analytical high-speed counter-current chromatography.

A compact portable model of a high-speed counter-current chromatograph enables efficient analytical separations of microgram sample quantities within 10 min. A series of preliminary experiments was conducted to study retention of the stationary phase of various two-phase solvent systems in short coils with different helical diameters. Under the optimal experimental conditions, analytical capability of the apparatus was successfully demonstrated in separation of flavonoids from a crude sea buckthorn ethanol extract in a multilayer coil with a total capacity of 8 ml.

Centrifugation↗
PubMed1989

Improvement of chemical analysis of antibiotics. XVI. Simple and rapid determination of residual pyridonecarboxylic acid antibacterials in fish using a prepacked amino cartridge.

A simple and rapid method for the determination of residual pyridonecarboxylic acid antibacterials (PCAs) (oxolinic acid, nalidixic acid and piromidic acid) in fish was developed using a combination of high-performance liquid chromatography (HPLC) and clean-up with an amino-type prepacked cartridge. PCAs were extracted with n-hexane-ethyl acetate (1:3) and the extract was applied to a Baker 10 amino cartridge. PCAs were eluted from the cartridge with acetonitrile-methanol-0.01 M aqueous oxalic acid solution (pH 3.0) (3:1:6) and were determined by HPLC. The separations were performed on Nucleosil 3C18 (3 microns, 75 x 4.6 mm I.D.) using a mobile phase containing oxalic acid. The recoveries of PCAs from various fishes fortified at the level of 1.0 ppm were 77.1-95.5%, and the detection limits were 0.05 ppm. The analytical time per sample was less than 30 min.

Animals↗
PubMed1989

Improved high-speed counter-current chromatograph with three multilayer coils connected in series. I. Design of the apparatus and performance of semipreparative columns in 2,4-dinitrophenyl amino acid separation.

A compact desktop model of a high-speed counter-current chromatograph holds three identical multilayer coils in the symmetrical positions around the rotary frame to maintain perfect balance of the centrifuge system without the use of a counterweight. These multilayer coils are connected in series to make up a total capacity of 400 ml while the unique gear arrangement on the rotary frame establishes a twist-free mechanism of the flow tubes so that continuous elution can be performed without the use of rotary seal. The high performance of the present system was successfully demonstrated in separations of 10-250 mg of 2,4-dinitrophenyl amino acid mixtures in a two-phase solvent system composed of chloroform-acetic acid-0.1 M hydrochloric acid (2:2:1, v/v/v).

Amino Acids↗
PubMed1989

Improved method for continuous UV monitoring in high-speed counter-current chromatography.

Continuous UV monitoring of the effluent in high-speed counter-current chromatography often encounters difficulty mainly due to the thermolabile nature of the mobile phase which tends to develop turbidity in the flow cell under a slight shift of the ambient temperature. This problem was effectively solved by inserting a fine PTFE tube (3 m x 0.46 mm I.D.) between the column outlet and the UV monitor and immersing a large portion of the tube into a waterbath heated at 30 degrees C. A similar tube was applied at the outlet of the UV monitor to create back pressure which suppressed gas bubble generation from the mobile phase. By the combined use of these devices, noiseless UV tracing was successfully demonstrated in two model experiments using thermolabile two-phase solvent systems: separation of flavonoids from the sea buckthorn ethanol extract with chloroform-methanol-water (4:3:2, v/v/v) and separation of bacitracin components with chloroform-ethanol-water (5:4:3, v/v/v).

Chromatography↗
PubMed1989

Induction of angiotensin-converting enzyme inhibitory activity by acid-limited proteolysis of glyceraldehyde 3-phosphate dehydrogenase.

Angiotensin-converting enzyme (ACE) inhibitors were excised from glyceraldehyde 3-phosphate dehydrogenase (GAPDH) preparations of tuna and porcine muscles by heating at 120 degrees C for 5 min in 1 M AcOH-20 mM HCl. The inhibitors were then purified by successive chromatographies. The final product from tuna was identified as Pro-Thr-His-Ile-Lys-Trp-Gly-Asp, which was the ACE inhibitor obtained from tuna muscle [Kohama et al. (1988) Biochem. Biophys. Res. Commun. 155, 332-337]. The porcine ACE inhibitor was found to be Pro-Ala-Asn-Ile-Lys-Trp-Gly-Asp, which was identical to the porcine muscle GAPDH peptide 79-86. These results strongly suggested that the ACE inhibitory octapeptides derived from GAPDH proteins by acid-limited proteolysis at Asp-Pro and Asp-Ala peptide bonds.

Amino Acid Sequence↗
PubMed1989

Stimulative effects of TMB-8 and trifluoperazine on pancreatic hormone release.

The effects of 8-N-N-diethylamino octyl 3,4,5-trimethoxybenzoate (TMB-8) and trifluoperazine (TFP) on the early phase (10 min) of the release of pancreatic hormones from isolated rat islets were investigated. TMB-8 and TFP stimulated insulin, glucagon, and somatostatin release in a dose-dependent manner at a low glucose concentration (2.5 mM). The levels of glucagon and somatostatin release were also stimulated by these two agents at a high glucose concentration (10 mM). Their effects were independent of external calcium ion level. These two agents did not modify insulin release at the high glucose concentration. The stimulative effects of the two agents on the release of these hormones were partially suppressed when the islets were pretreated with 6-hydroxydopamine (6-OHDA), a chemical adrenergic denervator that acts at nerve endings. In this situation, the norepinephrine (NE) released from pancreatic islets decreased to 44% of that of non-treated islets (P less than 0.01). The addition of NE (10(-9) M) to the incubation medium increased insulin, glucagon, and somatostatin secretion by 20-30% over control levels (P less than 0.05). In conclusion, the early phase of pancreatic hormone release was stimulated by TMB-8 and TFP. Our results strongly suggest that these two drugs could be mediated by the NE released from nerve endings in the islets.

Animals↗
PubMed1989

Improved cross-axis synchronous flow-through coil planet centrifuge for performing counter-current chromatography. I. Design of the apparatus and analysis of acceleration.

A novel design of the cross-axis synchronous flow-through coil planet centrifuge is introduced. The apparatus holds a pair of large coil holders symmetrically, one on each side of the rotary frame, at a lateral position 12.5 cm from the center of the holder shaft held 10 cm from the centrifuge axis. Mathematical analysis of acceleration generated by the planetary motion of the apparatus revealed a unique centrifugal force field which promises high retention of the stationary phase in the multilayer coil to perform efficient preparative-scale counter-current chromatography.

Chromatography↗
PubMed1989

Improved cross-axis synchronous flow-through coil planet centrifuge for performing counter-current chromatography. II. Studies on retention of stationary phase in short coils and preparative separations in multilayer coils.

Performance of the apparatus was evaluated in terms of stationary phase retention, partition efficiency and sample loading capacity. Preliminary studies with short coils revealed high retention of the stationary phase under a proper combination of the head-tail elution and planetary motion. Preparative capability of the apparatus was successfully demonstrated on efficient multigram separations of 2,4-dinitrophenyl amino acids, indole auxins, and bacitracin in a pair of large multilayer coils with a total capacity of 1.5 l.

Amino Acids↗
PubMed1989

Improvement of chemical analysis of antibiotics. XV. Isocratic high-performance liquid chromatographic methods for the analysis and preparative separation of the components of bacitracin.

Isocratic high-performance liquid chromatographic (HPLC) systems were established for analytical and preparative separation of the components of the antibiotic preparation bacitracin (BC). The best analytical results were obtained using a C18 modified silica gel column (Capcell Pak C18) with a solvent system of 0.04 M disodium hydrogenphosphate buffer and methanol (4:6), pH 9-10. The calibration graphs showed good linear relationships between 50 and 1000 ng for BC-A and between 65 and 1000 ng for BC-F. With respect to the preparative HPLC, a Capcell Pak C18 column with methanol-0.05 M aqueous sodium sulphate solution (6:4) as a mobile phase gave satisfactory results. The isolation of BC-A and -F was readily achieved without decomposition of the components by using the present preparative HPLC followed by desalting on a prepacked C18 cartridge.

Anti-Bacterial Agents↗
PubMed1989

Serum titers of pre-S(2) antigen in patients with acute and chronic type B hepatitis: relation to serum aminotransferase activity and other hepatitis B virus markers.

The peptide which is encoded by the pre-S(2) region of hepatitis B virus DNA, the pre-S(2) antigen, was determined quantitatively by an enzyme immunoassay system employing monoclonal antibodies. The prevalence and titer of pre-S(2)Ag were 91.9% (91/99) and 10,356 +/- 19,053 units (mean +/- S.D., arbitrary units) for hepatitis B e antigen (HBeAg)-positive patients with acute and chronic HBV infection and 86.0% (74/86) and 952 +/- 1,565 units for HBeAg-negative subjects. In four patients with acute hepatitis B, pre-S(2)Ag titers changed in parallel with HBV DNA levels, and the disappearance of pre-S(2)Ag from serum was associated with a rapid fall of ALT levels into the normal range, whereas the fluctuation of pre-S(2)Ag titer correlated with persistence of ALT elevations. In all of the 19 episodes of acute exacerbation of hepatitis which occurred in nine patients with chronic active hepatitis B, a significant elevation of pre-S(2)Ag titer was observed, closely overlapping an increase or appearance of HBV DNA, and its peak preceded peaks of ALT by 1 to 11 weeks (mean +/- S.D. = 4.26 +/- 2.57 weeks). These observations suggest that quantitative measurement of pre-S(2)Ag would be useful for estimation of the magnitude of HBV replication and would help predict the prognosis of acute hepatitis B and of acute exacerbation in chronic hepatitis B.

Acute Disease↗
PubMed1989

Fatty acid myocardial imaging using 123I-beta-methyl-iodophenyl pentadecanoic acid (BMIPP): comparison of myocardial perfusion and fatty acid utilization in canine myocardial infarction (occlusion and reperfusion model).

To evaluate the relationship between myocardial perfusion and fatty acid metabolism in canine myocardial infarction, 16 dogs were studied using thallium and 123I-beta-methyl-iodophenyl pentadecanoic acid (BMIPP). Eight dogs (group A) had left anterior coronary arterial occlusion (6 h ligation), 6 dogs (group B) had reperfusion (3 h ligation and 1 h reperfusion) and 2 dogs served as the normal control. Myocardial imaging with BMIPP was excellent, owing to its higher uptake and longer retention in myocardium and rapid blood disappearance in addition to diminished liver and lung uptake. The mean half time value which was generated from the BMIPP myocardial washout curve, was significantly larger in the reperfused myocardium. The gamma camera imaging showed uncoupling of BMIPP and thallium (BMIPP uptake greater than thallium uptake) in five dogs in group B. On the other hand, all dogs in group A had a persistent defect in BMIPP and thallium uptake. Our findings indicate that the combination of BMIPP and thallium for myocardial imaging supply different information about the zone of infarction and ischemia, which may be useful for the assessment of myocardial viability.

Animals↗
PubMed1989

Application of mechanical mobility of periodontal tissues to tooth mobility examination.

Tooth mobility examination is important in planning dental treatment, as it may give an indication of alveolar bone loss and the condition of the periodontal ligament. In clinical dental diagnosis a manual tooth mobility examination is useful. However, its determination of tooth mobility is subjective and depends on the skill and experience of the clinician. The authors have previously reported on a device for measuring the biomechanical properties of human periodontium using an impedance head. Using this device, the mechanical mobility of periodontium can be measured and the mechanical parameters of the periodontal physical model are obtained. Tooth mobility is defined objectively on the basis of discriminant scores of mechanical parameters, and a mobility triangle (MT) figure is drawn as a record for visual interpretation. The paper describes the validation of the mechanical mobility measurements and their interpretation using mobility parameters and a personal computer to produce a mobility triangle figure. The method is compared favourably with clinical mobility measurement. The relationship of the model to underlying pathology is tested by measurements performed on various tooth model systems.

Biomechanical Phenomena↗
PubMed1989

Implications of hyperechoic lesions in small hepatocellular carcinoma.

Of 34 solitary small hepatocellular carcinomas (HCC) 2 cm in diameter or less, 13 with hyperechoic lesions were observed serially by sonography, and 11 of these were examined histologically. Serial examination showed that hypoechoic areas appeared at the periphery of or within, the hyperechoic tumor, and that these areas expanded more with tumor growth than the hyperechoic areas as if compressing or displacing the existing hyperechoic areas. Histologically, the hyperechoic lesions were composed mostly of well-differentiated cancer cells containing fat droplets, whereas the hypoechoic lesions were composed of cancer cells without fat droplets. In the two tumors that were formed almost completely of cancer cells showing fatty metamorphosis, cancer cells without fat droplets proliferated mainly in the periphery of the tumor. These findings suggest that, in hyperechoic HCC, cancer cells with fat droplets appear in the early stage of HCC, and probably change into concer cells without fat droplets by the time that a certain tumor size is reached, with gradual displacement by the latter type of cell during tumor growth.

Biopsy↗
PubMed1989

Reciprocal changes in serum albumin and alpha-fetoprotein levels in the recovery course of acute viral hepatitis stimulated by glucagon and insulin therapy: analysis of a double blind controlled trial.

The records of 57 patients with acute viral hepatitis (28 given hormones and 29 placebo) in a double blind controlled trial of one week of glucagon and insulin therapy were analyzed. In the placebo group, SGPT values dropped after treatment with improved prothrombin time and serum levels of total bilirubin and albumin. In the hormone group, they changed similarly, except serum albumin levels which were reversed during treatment (P less than 0.05). There was a bottom line of serum albumin levels which preceded a peak of serum alpha-fetoprotein levels within one week in the placebo group, but was around the peak in the hormone group. There were 12 patients in the hormone group in whom serum alpha-fetoprotein levels rose with treatment and decreased after its discontinuation, and 5 in the placebo group (P less than 0.05). Such a change in serum alpha-fetoprotein levels was accompanied by decreased serum albumin levels in 6 of 10 patients given hormones and none of the 5 given placebo (P less than 0.05). These results indicate reciprocal changes in serum albumin and alpha-fetoprotein levels appearing during the recovery course of acute viral hepatitis, and suggest that this therapy may stimulate its development. Stimulation of liver regeneration by this therapy merits consideration.

Adult↗