Search PubMed⌕ Search

Biomedical subjects

H Oka

Publications and source records attributed to H Oka.

At least 343 records · Page 19Linked to original sources
PubMed1989

[Xanthine oxidoreductase activity in rat brain tissue: the changes after decapitation].

Since only little xanthine oxidase (XO) activity in mammalian brain was detected in earlier reports, the major end product of AMP degradation in the brain has been believed to be hypoxanthine. Our recent experimental study however, has indicated the presence of uric acid in the rat brain subjected to focal ischemia or cold injury. Allopurinol, a xanthine oxidoreductase inhibitor, has been found to markedly suppress the uric acid production in the same experimental settings. These results suggested that uric acid is generated from hypoxanthine by enzymatic reaction in injured brain tissue. The aim of this experiment is to prove the existence of xanthine oxidoreductase activity in brain tissue. Xanthine oxidoreductase activity in rat cerebral tissue was measured immediately or at 24-hour after decapitation. Under pentobarbital anesthesia, twenty Sprague-Dawley rats were killed by decapitation following washout of the blood by trans-cardiac perfusion with cold physiological saline. Immediately or after 24 hours of decapitation ischemia, the forebrain was removed and homogenized in 6 ml ice cold 0.05 M potassium phosphate buffer (pH 7.8) containing 1 mM phenylmethylsulfonyl fluoride, 0.3 mM EGTA, and 10 mM dithiothreitol. The homogenate was centrifuged at 100,000 g for 60 min and then the supernatant was dialyzed overnight against 0.05 M potassium phosphate buffer (pH 7.8). Aliquot of each dialyzed supernatant (sample) and standard xanthine solution with NAD was reacted at 37 degrees C for 15 min to measure the combined activity of xanthine dehydrogenase (XDH) and XO. For the measurement of XO, standard xanthine solution without NAD was used.(ABSTRACT TRUNCATED AT 250 WORDS)

Allopurinol↗
PubMed1989

[Assessment of myocardial necrosis by 111In-antimyosin F ab scintigraphy].

111In-antimyosin F ab (AM) myocardial scintigraphy was carried out in (A) 13 patients with acute myocardial infarction (9.9 +/- 2.2 days from the onset) and (B) 9 with myocarditis and/or dilated cardiomyopathy. Forty eight hours after injection of AM, the patients were injected with 74 MBq (2 mCi) of thallium-201 (TL). The two sets of Planar and SPECT image were obtained simultaneously using dual energy window sets. In group A, positive focal AM uptake was demonstrated in 12 (92%) patients. Higher AM uptake was observed in patients who had PTCR/PTCA. By combination with TL, it is useful to detect inferior infarction and to differentiate old from acute infarction. Dual SPECT images gave precise information about the infarcted area. In group B, positive diffuse AM uptake was demonstrated in 7 (77%) patients. In conclusion, AM myocardial scintigraphy was proven to be useful for the assessment of acute necrosis after myocardial infarction but also on-going necrosis of myocarditis and/or myopathy.

Adult↗
PubMed1988

Simultaneous determination of the nine food additives using high-performance liquid chromatography.

A technique for the simultaneous determination of sorbic acid, benzoic acid, dehydroacetic acid, p-hydroxybenzoic acid esters (ethyl, isopropyl, n-propyl, isobutyl and n-butyl p-hydroxybenzoate) and saccharin sodium using ion-pair reversed-phase high-performance liquid chromatography is described. The nine food additives were separated on a Nucleosil 3C18 (3 microns) column (75 x 4.6 mm I.D.) using methanol-acetonitrile-0.05 M aqueous acetonic acid solution (pH 4.5) (1.5:1:3.1) containing 2.5 mM cetyltrimethylammonium chloride as the mobile phase at a flow-rate of 1.0 ml/min, and detected at 233 nm. The food additives were separated within 18 min and their calibration graphs were linear between 2 and 200 ng.

Acetonitriles↗
PubMed1988

Effect of genistein on topoisomerase activity and on the growth of [Val 12]Ha-ras-transformed NIH 3T3 cells.

Genistein inhibited topoisomerase II and I; it increased the enzyme-DNA complex in L1210 cells at 1 micrograms/ml, and interfered with pBR322 DNA relaxation by the enzymes. To test the role of topoisomerase in the transformation by oncogenes, the effect of genistein on the transformation of NIH 3T3 cells by transfection with [Val 12]Ha-ras was compared with that of N-alpha-tosyl-L-lysyl-chloromethyl ketone (TLCK), since genistein inhibits tyrosine kinase as well as TLCK. Genistein reduced the number of foci of the transformed cells, and suppressed selectively the growth of ras-transformed NIH 3T3 cells but not normal NIH 3T3 cells. In contrast, TLCK did not affect the transformation. It inhibited the growth of the normal cells but not the transformed cells.

Animals↗
PubMed1988

Short latency activation of local circuit neurons in the cat somatosensory cortex.

Intracellular horseradish peroxidase (HRP) study was performed in the cat primary somatosensory cortex (SI) under Nembutal anesthesia. Response properties of neurons were analysed with stimulation of the peripheral nerve (superficial radial nerve; SR) and thalamic ventrobasal nucleus (VB). A total number of 23 cells (15 in layers III and IV, 6 in layer V and 2 in layer VI) were identified morphologically as local circuit neurons with intracellular HRP staining. The latencies of SR-induced (7.7-8.5 ms) as well as VB-induced excitatory postsynaptic potentials (EPSPs) (1.3-1.5 ms) were significantly shorter than those of pyramidal neurons (9.1-10.6 ms for SR and 1.6-2.8 ms VB EPSPs). Morphological features of identified local circuit neurons are all, except one in layer VI, aspiny and presumed to be inhibitory in nature. The present study indicates that presumed inhibitory interneurons in the cat SI could be activated first by thalamic inputs among cortical neurons and set to inhibit the output cells for the sharp contrast in the sensory processing.

Animals↗
PubMed1988

Cell-specific hypomethylation of the pepsinogen gene in pepsinogen-producing cells.

The pepsinogen gene is hypomethylated in the stomach, in which it is expressed. For demonstration that this hypomethylation of the pepsinogen gene in the stomach reflects pepsinogen-producing cells, we analyzed fractions of dispersed mucosal cells with various contents of pepsinogen-producing cells prepared from guinea pig stomach by centrifugal elutriation. mRNA expression and the extent of hypomethylation of the pepsinogen gene in each fraction was closely correlated with the content of pepsinogen-producing cells. These results suggested hypomethylation of the pepsinogen gene in pepsinogen-producing cells and differential pepsinogen gene methylation in cell subpopulations in the stomach.

Animals↗
PubMed1988

Analysis and purification of toxic peptides from cyanobacteria by reversed-phase high-performance liquid chromatography.

A simple, rapid and reliable chemical analysis method for microcystins (cyanoginosins) has been studied. Three different mobile phases for high-performance liquid chromatography were selected and optimized. Also the adsorptive powers of three commercially available C18 cartridges were compared and the results successfully applied to the clean up of three of the toxins. Finally a total system for the analysis and isolation of microcystins was established.

Chromatography, High Pressure Liquid↗
PubMed1988

Fibroblast-like transformation and c-myc gene alteration of human hepatocytes induced by novobiocin and butyrate.

Topoisomerase II inhibitor novobiocin and deacetylase inhibitor sodium butyrate synergistically transformed Chang liver cells into fibroblast-like cells. In these fibroblast-like cells, the production of type III procollagen was increased and the DNase I hypersensitivity of c-myc gene was reduced. In addition, these changes were associated with an increased acetylation of nuclear proteins, especially those of DNase I sensitive nucleosomes. Therefore, it is suggested that chemical modulation of nuclear proteins by novobiocin and butyrate may be responsible, at least partly, for the alteration of the chromatin structure of c-myc gene and the fibroblast-like transformation of Chang liver cells.

Butyrates↗
PubMed1988

Isolation of angiotensin-converting enzyme inhibitor from tuna muscle.

A novel inhibitor of angiotensin-converting enzyme (ACE) has been discovered and isolated in a pure form from acid extract of tuna muscle by successive column chromatographies and HPLC. The final preparation showed IC50 values of 1 microM and 2 microM for ACEs from bovine and rabbit lungs, respectively. The amino acid sequence of the inhibitor has been established as Pro-Thr-His-Ile-Lys-Trp-Gly-Asp by the Edman procedure and carboxypeptidase digestion.

Amino Acid Sequence↗
PubMed1988

Enzyme-linked immunosorbent assays for serum pepsinogens I and II using monoclonal antibodies--with data on peptic ulcer and gastric cancer.

Serum pepsinogen I and pepsinogen II levels in 369 healthy controls, 38 duodenal ulcer, 30 gastric ulcer and 46 stomach cancer including 21 early and 25 advanced gastric cancer patients were measured by enzyme-linked immunosorbent assays using pepsin moiety-reacting monoclonal antibodies to pepsinogens I and II. Serum pepsinogen I and pepsinogen II levels were higher in the duodenal and gastric ulcer groups than in the control. Although there was no significant difference in serum pepsinogen II between stomach cancer and control, serum pepsinogen I was significantly lower in the former than in the latter and also in advanced gastric cancer than in early gastric cancer. A specific negative correlation of serum pepsinogen I with patient age was observed in stomach cancer but not in peptic ulcer or control groups. Receiver operating characteristic analysis was performed and indicated that serum pepsinogen I, compared with serum pepsinogen II or the pepsinogen I/pepsinogen II ratio, is the most effective marker for stomach cancer.

Antibodies, Monoclonal↗
PubMed1988

Hypomethylation and expression of pepsinogen A genes in the fundic mucosa of human stomach.

We have examined the correlation between the extents of methylation and expression of pepsinogen A genes in normal human tissues. Expression of pepsinogen A mRNA was detected only in the fundic mucosa of the stomach and both CCGG and GCGC sites in the genes region were less methylated in the fundic mucosa than in other non-expressing tissues. Thus, there was an inverse correlation between the extents of methylation and expression of pepsinogen A genes and the role of DNA methylation in the regulation of pepsinogen A genes expression during normal differentiation was suggested.

DNA↗
PubMed1988

Comparison of functional responses of canine coronary artery and saphenous vein.

Functional responses of canine circumflex coronary arteries and saphenous veins before and after grafting surgery were assessed following physiologic and pharmacologic interventions. Developed tension of ringed segments of vessels was recorded isometrically. Dose-dependent responses to norepinephrine revealed significantly greater responses of saphenous veins than coronary arteries (maximal responses were 2.79 +/- 0.45 and 0.44 +/- 0.34 g, respectively; p less than 0.001). Sensitivity to norepinephrine [as evaluated by 50% effective dose (ED50) value] was 3.3 times greater in the saphenous veins (p less than 0.001). STA2, a synthetic thromboxane A2 analog (see Methods), produced similar contractions of both vessels [maximal responses were 2.13 +/- 0.37 g in saphenous vein and 1.64 +/- 0.85 g in coronary artery; p less than not significant (NS)], while sensitivity to STA2 of saphenous veins was 3.1 times greater than that of coronary arteries (p less than 0.001). In contrast to the foregoing responses, coronary arteries demonstrated significantly greater responses to potassium than saphenous veins (maximal responses were 2.16 +/- 0.71 g and 1.40 +/- 0.56 g, respectively; p less than 0.001). Moreover, coronary arteries revealed 1.6 times greater sensitivity than saphenous veins (p less than 0.001). When saphenous veins were transplanted into the femoral artery, the segments of the grafts (2 weeks or 3 months after surgery) revealed 4.0 and 1.7 times greater sensitivity (denervation supersensitivity) to norepinephrine and potassium than those of the control veins (p less than 0.01, respectively). Contractile tension response, however, decreased by at least 50% 3 months after surgery, most probably due to a thickened vessel wall and a reduced compliance.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Antithrombin III concentrate in the treatment of fulminant hepatic failure.

Twenty-six patients with fulminant hepatic failure were treated with daily infusions of antithrombin III concentrate until recovery of consciousness or death. Seven patients were alive (group A), 7 survived 17 to 47 days after treatment (group B), and 12 died within 9 days (group C). Decreased plasma antithrombin III levels increased on the day after treatment, irrespective of the pretreatment levels in all patients. Continuous or temporary normalization was seen in all patients in groups A and B, but in only 5 in group C patients whose bleeding was extensive (p less than 0.05). An abrupt drop in peripheral platelet counts occurred when plasma antithrombin III levels were below normal. General bleeding accompanied this drop. These results suggest that maintained normal plasma antithrombin III levels are beneficial for prolonged survival time in fulminant hepatic failure, probably through controlling intravascular coagulation, and that antithrombin III infusion may be useful for such treatment.

Antithrombin III↗
PubMed1988

Exocrine pancreatic function test by endoscopic retrograde aspiration of pure pancreatic juice.

The validity of endoscopic retrograde aspiration of pure pancreatic juice (PPJ) as an exocrine pancreatic function test was evaluated in terms of coefficients of variation in control subjects, reproducibility on repeated examinations, and sensitivity for detecting patients with chronic pancreatitis (CP). PPJ was obtained from, nine control subjects, four patients with suspected CP and 13 with CP. PPJ was collected from within the pancreatic duct by endoscopic retrograde catheterization of the papilla at 2-min intervals for 20 minutes after a bolus intravenous injection of secretin (1U/kg) and then for further 20 minutes after a bolus intravenous injection of CCK-PZ (1U/kg). It was recognized that endoscopic aspiration of PPJ was at least as useful and reliable as the traditional pancreozymin secretin test. Useful parameters included 10-min secretory volume and 10-min bicarbonate output after secretin stimulation, and 10-min enzyme output after CCK-PZ stimulation (lipase output showed higher sensitivity than amylase output). Maximal bicarbonate concentration showed poorer reproducibility and sensitivity despite better coefficients of variation. Lower limits in controls (mean-1.5SD) were 22.5ml for 10-min secretory volume, 2.7mEq for 10-min bicarbonate output, 24.5 x 10(3)U for 10-min amylase output and 3.4 x 10(3)IU for 10-min lipase output.

Adult↗