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Biomedical subjects

T Miyazaki

Publications and source records attributed to T Miyazaki.

At least 685 records · Page 38Linked to original sources
PubMed1989

Determination of bromperidol in serum by automated column-switching high-performance liquid chromatography.

A column-switching high-performance liquid chromatographic method with ultraviolet detection is described for the simple and rapid determination of bromperidol, a neuroleptic drug, in dog and human sera. The drug in serum and trifluperidol added to the serum as an internal standard were extracted with hexane-chloroform, and the extract was subjected to automated column-switching high-performance liquid chromatography using a hydrophilic metaacrylate polymer column (TSK gel PW precolumn) for sample clean-up and a reversed-phase column (TSK gel ODS-80TM) for separation. The detection limit of bromperidol is 0.3 ng/ml serum and the recovery of bromperidol added to serum (2.7-16.0 ng/ml) was satisfactory with a standard deviation of 3% or less.

Adult↗
PubMed1989

Excitatory and inhibitory effects of epinephrine on neonatal rat sympathetic preganglionic neurons in vitro.

Current and voltage recordings were made from antidromically identified sympathetic preganglionic neurons (SPNs) in transverse thoracolumbar spinal cord slices removed from neonatal rats. When applied by either pressure ejection or superfusion, epinephrine (Epi) caused a slow depolarization or an inward current in 62 SPNs (42%) and a slow hyperpolarization or an outward current in 21 SPNs (14%). The responses persisted in low calcium- or tetrodotoxin-containing media. The Epi-induced depolarization or inward current was associated with increased membrane resistance; it was reduced by membrane hyperpolarization and nullified at a membrane potential of about -100 mV; a clear reversal however was not observed at more negative potential levels. In a number of SPNs the Epi-induced depolarization was accompanied by small inhibitory postsynaptic potentials. The latter were eliminated by a low calcium solution and by the glycine antagonist strychnine, suggesting that they were caused by glycine or a glycine-like substance released from interneurons subsequent to activation by Epi. The Epi-induced hyperpolarization or outward current was associated with decreased membrane resistance, and nullified around -100 mV. The alpha-adrenergic antagonist, dihydroergotamine, and alpha 1-antagonist, prazosin, reversibly blocked the excitatory, whereas the alpha 2-antagonist, yohimbine, abolished the inhibitory response, respectively. It is concluded that Epi acting on alpha 1- and alpha 2-adrenergic receptors depolarizes and hyperpolarizes the rat SPNs by decreasing or increasing membrane conductances to potassium ions.

Adrenergic Fibers↗
PubMed1989

Efficient expression of genetically engineered hepatitis B virus surface antigen P31 proteins in yeast.

We have constructed plasmids that express modified hepatitis B virus surface antigen (HBsAg) P31-coding genes (M-P31c, d, e, f, and i) having various genetically engineered pre-S2 regions. The plasmids contain the GAPDH (gene coding for glyceraldehyde-3-phosphate dehydrogenase) promoter and the PGK (gene coding for 3-phosphoglycerate kinase) terminator, both isolated from sake brewing yeast, Saccharomyces cerevisiae Kyokai III. Expression levels of the modified HBsAg P31 proteins in yeast are greatly increased from 0.4% to 11.7% of total cell protein. However, the specific mRNAs are expressed at equal levels and the degradation rates of the modified P31 proteins do not vary significantly. Therefore, we considered that different expression levels of the modified P31 proteins are attributed to the changes of the post-translational efficiency. And it was suggested that the conformational stability of the N-terminal peptide (Met-1-Phe-46) in the endoplasmic reticulum membrane determines the expression level of modified P31 proteins.

Amino Acid Sequence↗
PubMed1989

Glycine potentiates NMDA responses in rat hippocampal CA1 neurons.

When superfused onto rat hippocampal slices, glycine (0.1-0.5 mM) potentiated the depolarization induced by pressure application of NMDA in normal Krebs solution and the synaptic discharge evoked by stimulation of the Schaffer collateral-commissural inputs to the CA1 pyramidal neurons bathed in Mg2+-free media; the effects were not prevented by strychnine. In addition, glycine partially reversed the blocking effect of D-2-amino-5-phosphonovalerate (AP5) on N-methyl-D-aspartate (NMDA)-induced depolarization. These results show that glycine at relatively high concentrations potentiates the NMDA-mediated response in hippocampal slices.

2-Amino-5-phosphonovalerate↗
PubMed1989

Processing enzymes acting on carbohydrate moiety of lysosomal hydrolases in leukemic cells: elevated activity of N-acetylglucosamine-1-phosphotransferase.

We previously demonstrated that an acidic variant form of lysosomal arylsulfatase B accumulated in chronic myelogenous leukemia (CML) cells was highly phosphorylated at its carbohydrate moiety (Uehara Y, et al, Cancer Res 43:5618, 1983). Since lysosomal hydrolases including the sulfatase underwent the posttranslational phosphorylation processing at the carbohydrate moiety, we investigated two enzymes acting on the processing in peripheral leukocytes from leukemia patients. The activity level of the first enzyme in the processing, an N-acetylglucosamine-1-phosphotransferase to form phosphodiester at the carbohydrates, was significantly higher in CML cells than in normal control. The transferase level in CML cells was also higher compared with that in normal bone marrow cells, which include myeloid progenitor cells. However, the activity of the second processing enzyme, a phosphodiester glycosidase that converts a phosphodiester to a phosphomonoester, showed no consistent change in CML cells. Thus, increment of the sulfatase variant containing phosphomonoesters and diesters in CML cells is most probably associated with elevated activities of the phosphotransferase. In two cases of CML in blastic crisis and a case of acute myelogenous leukemia (AML), activity of the processing enzyme was considerably decreased concomitant with reduction of peripheral blastic cells by chemotherapy.

Adult↗
PubMed1989

Determination of renin activity in human plasma by column-switching high-performance liquid chromatography with fluorescence detection.

A column-switching high-performance liquid chromatographic (HPLC) method with fluorescence detection is described for the determination of the renin activity in human plasma. The method is based on the quantification of the enzymatically produced angiotensin I. Angiotensin I liberated from a synthetic substrate (tridecapeptide of human angiotensinogen) and [Val5]-angiotensin I as an internal standard are converted into fluorescent derivatives by reaction with benzoin. The derivatives are separated from various interfering substances by column-switching HPLC using three reversed-phase columns. The limit of detection (signal-to-noise ratio = 3) of the renin activity is 2.7 pmol of angiotensin I formed per h per ml of plasma, which corresponds to approximately 820 fmol of angiotensin I injected. The column-switching method in combination with pre-column derivatization for the fluorimetric detection permits the sensitive and selective determination of the enzymatically formed angiotensin I. Hence low activities of renin in normal human plasma are readily measured.

Chromatography, High Pressure Liquid↗
PubMed1989

Effects of halothane and hypoxia on hepatic oxygen metabolism in the dog.

Hepatic oxygen delivery and consumption were assessed in mongrel dogs receiving 2MAC of halothane combined with graded hypoxic hypoxemia (21-8% oxygen). Hepatic blood flow was measured using electromagnetic flowmetry; hepatic oxygen delivery and consumption were calculated from measured hepatic blood flow and oxygen content in hepatic arterial, portal venous and hepatic venous blood. In hypoxia-halothane group, total hepatic blood flow decreased at mild hypoxia (15% O2) from control value, but recovered to control level at moderate hypoxia (10% O2), then again decreased at 8% O2. Oxygen supply to the liver was decreased with the augmentation of hypoxia in hypoxia-halothane and hypoxia-alone groups, and it was significantly lower in the hypoxia-halothane group at 15 and 12% O2. Hepatic oxygen consumption also decreased from air control values with the increment of hypoxia, but there was no significant difference between the groups. Arterial ketone body ratio, which indicates mitochondrial energy charge level, decreased with the development of hypoxia but there was no significant difference in this ratio between the groups. These results show that halothane aggravated oxygen supply to the liver at mild to moderate hypoxia (15-12% O2), but did not worsen it specifically at more serious hypoxia (10-8% O2) compared with hypoxia alone. Hepatic hypoxia itself could not thus be a main cause of halothane hepatotoxicity.

Journal Article↗
PubMed1989

bcr rearrangement and C-abl gene expression in Ph1-positive hybrid acute leukemia with simultaneous proliferation of lymphoid and myeloid blasts.

bcr gene rearrangement and c-abl gene expression were analyzed in a patient with Philadelphia chromosome (Ph1)-positive hybrid acute leukemia with simultaneous proliferation of lymphoid and myeloid blasts. These data were compared with those from a patient with chronic myelogenous leukemia (CML) in mixed crisis. The leukemic cells of both patients showed immuno-phenotypic profiles such as non-T, non-B common ALL with some MPO-positive leukemic cells and rearranged JH genes. On analysis of molecular events associated with the Ph1 chromosome, the leukemic cells of a patient with CML in mixed crisis showed bcr rearrangement and an 8.5-kb bcr-abl chimeric mRNA, but those of a patient with Ph1-positive hybrid acute leukemia showed no 8.5-kb bcr-abl mRNA, as previously reported in a number of Ph1-positive acute lymphoblastic leukemia (ALL) cases. These results revealed that the molecular event found in Ph1-positive ALL is not only restricted to lymphoid lineage but may play an important role in the proliferation of the myeloid lineage.

Adult↗
PubMed1989

Serum 2'-5'oligoadenylate synthetase as a monitoring marker of anti-viral effect during interferon therapy for chronic type B hepatitis.

We evaluated the usefulness of serum 2'-5'oligoadenylate synthetase (2-5AS) activity assay in monitoring the anti-viral activity of chronic type B hepatitis patients during IFN therapy. The serum 2-5AS activity was rapidly increased during the above therapy and was maintained at a medium-to-high level throughout the therapy period, although the capacity for increase reflected differences among individuals. The kinetics of serum 2-5AS activity during the therapy was almost consistent with that of the PBMCs 2-5AS activity. 2-5AS activity had an inverse correlation with DNA-P; i.e. DNA-P often disappeared from serum after interferon treatment in patients with a marked response in serum 2-5AS activity. The enhancement of serum 2-5AS activity during IFN therapy seemed to correlate with an increase in anti-viral activity. The results suggest that the serum 2-5AS activity assay is a useful probe for monitoring the anti-viral activity of chronic type B hepatitis patients during interferon therapy.

2',5'-Oligoadenylate Synthetase↗
PubMed1989

In vivo administration of allopurinol affects ovulation and early embryonic development in rabbits.

The potential role of the hypoxanthine-xanthine oxidase system in human chorionic gonadotropin-induced ovulation, nuclear maturation, and preimplantation development was investigated in the rabbit by use of the xanthine oxidase inhibitor allopurinol. Allopurinol (50 mg/kg) or vehicle was injected, followed by human chorionic gonadotropin (100 IU). Administration of inhibitor or vehicle was repeated 3 hours later. Ovaries and ovulated ova were inspected 12 or 24 hours after human chorionic gonadotropin administration for follicle rupture, cumulus dispersal, and nuclear maturation. Ova were inseminated in vitro and assessed for development to the blastocyst stage, up to 96 hours after insemination. Allopurinol significantly reduced ovulatory efficiency, defined as the percent of large follicles that ovulate, and decreased the percent of ova with cumulus dispersal. Allopurinol significantly inhibited morula and blastocyst formation. These data suggest that the xanthine oxidase system may play a role in ovulation and early embryonic development.

Allopurinol↗
PubMed1989

Distributional variation of P-450 immunoreactive hepatocytes in human liver disorders.

Implications of P-450 in human hepatic disorders were immunohistochemically examined. We first confirmed that an antibody against P-450-HM1, an isozyme of cytochrome P-450 which was purified from human livers at autopsy, detects only P-450 on immunoblots. In a study of 79 consecutive autopsied livers using the avidin-biotin-peroxidase complex method, the antibody reacted strongly with fetal hepatocytes, the reaction being more intense in the left lobe than in the right lobe. In normal livers, immunoreactivity was confined to centrilobular hepatocytes, decreasing in the periportal zone. Enhanced expression was occasionally found in scattered hepatocytes and in hepatocytes surrounding sublobular veins; this enhancement was related to longterm steroid therapy. No specific induction was observed in patients with toxic hepatitis. In patients with fibrosis, cirrhosis, or regenerative nodules, however, P-450-positive hepatocytes were observed in the periportal and middle zones as well as in the central zone. In contrast, hepatocellular carcinomas were devoid of P-450 immunoreactivity. These results suggest that P-450-HM1, which is abundant in the fetal liver, is reexpressed in regenerating hepatocytes but not in cancers.

Antibody Specificity↗
PubMed1989

Fatal and non-fatal methomyl intoxication in an attempted double suicide.

A 79-year-old man and his 73-year-old wife attempted double suicide by ingesting methomyl powder. The woman died 19 h after ingestion in spite of intensive care. At autopsy a large number of miliary hemorrhages were found in both thalami of the brain. Her husband, however, recovered after 10 days of treatment. Methomyl (CAS No. 16752-77-5, Lannate) in the biological materials was analyzed by gas chromatography-mass spectrometry. The methomyl concentration was 44 micrograms/g in the wife's serum sample collected 1 h after ingestion, and 0.2 microgram/g in the blood sample collected at autopsy. The methomyl concentration in the husband's blood sample collected 28 h after ingestion was from 0.01 to 0.1 microgram/g. It is suggested that prompt and adequate intensive care including a direct hemoperfusion is necessary to effect the recovery of patients with lethal blood levels of methomyl. The miliary hemorrhages found in the thalami of the brain are suspected to have been caused by asphyxia induced by methomyl intoxication.

Aged↗
PubMed1989

Detection of S-methylfenitrothion, aminofenitrothion, aminofenitroxon and acetylaminofenitroxon in the urine of a fenitrothion intoxication case.

A 23-year-old male attempted suicide by ingesting approximately 50 ml of 5% fenitrothion emulsion, and vomited soon afterwards. He was admitted to a hospital about 3 h after ingestion. He recovered and was discharged from hospital 3 days after admission. The serum cholinesterase activity (normal range: 175-440 I.U.) was only 29 at 3 h, 32 at 1 day, 59 at 2 days and 75 at 3 days after ingestion. Fenitrothion and its metabolites in the body fluids were extracted by an Extrelut column extraction method, detected by a gas chromatograph equipped with either a hydrogen flame ionization detector or a flame photometric detector, and confirmed by a gas chromatograph-mass spectrometer. Fenitrothion concentration in the blood was 169.5 ng/g at 3 h after ingestion. The half life of blood fenitrothion concentration was found to be about 4.5 h. Fenitrothion metabolites, 3-methyl-4-nitrophenol, aminofenitrothion, aminofenitroxon, acetylaminofenitroxon and S-methylfenitrothion, were detected in the urine samples. All of them except S-methylfenitrothion were detected in the urine samples collected up to 62 h after ingestion. It would appear therefore that fenitrothion poisoning can be determined by detection and analysis of the metabolites in urine even if fenitrothion has not been detected in the blood.

Adult↗
PubMed1989

Electrophysiological effects of acute ischaemia on electrically stable myocardial infarction.

The purpose of this study was to examine the effects of acute ischaemia superimposed on an electrophysiologically stable, small myocardial infarction, and to determine the mechanisms of induced ventricular arrhythmias, using a canine infarction model. Ten dogs without inducible ventricular tachycardia or fibrillation on the 7th day post-myocardial infarction (Group 1) and 14 control dogs (Group 2) were subjected to 30 min acute ischaemia by occlusion of the proximal left anterior descending artery. The areas of infarcted myocardium ranged from 1.0 to 20.4% (mean 8.9, SD 7.7) of total left ventricular weight. Ventricular arrhythmias were inducible by programmed electrical stimulation in eight of 10 dogs (80%) after acute ischaemia, but in only one of 14 control dogs (7%) (p less than 0.005). In seven of eight Group 1 dogs, epicardial mapping showed that ventricular arrhythmias did not originate from the epicardial region. In one dog, in which there was simultaneous epicardial and endocardial mapping, an endocardial electrogram from the boundary area between infarcted and acutely ischaemic zones recorded continuous fragmented activity. It was thus suggested that re-entry in a relatively isolated endocardial site could be attributed to the induction of ventricular tachyarrhythmias, and that the electrical instability could be significantly enhanced during acute ischaemia when underlying myocardial infarction was present.

Acute Disease↗
PubMed1989

Electrophysiological effects of flecainide in a canine 7 day old myocardial infarction model.

Flecainide has been reported to be effective in suppressing chronic ventricular arrhythmias in clinical studies, but the electrophysiological mechanisms of its action are not understood. We therefore studied its effects on re-entrant ventricular arrhythmias in eight dogs with 7 day old infarction. Epicardial mapping and local refractory periods were obtained using 48 channel bipolar electrodes attached to the epicardium. Epicardial conduction velocity was significantly depressed by flecainide (2 mg.kg-1 intravenously), from 49.3 (SD 11.9) cms-1 to 35.3(11.2) cm s-1 (p less than 0.01). Flecainide prolonged effective refractory periods (ERP) in the normal, border and infarct zones: normal (n = 93), from 189.5 (15.9) to 219.3 (17.7) ms, p less than 0.01; border (n = 54) from 187.4(24.0) to 225.2 +/- 32.5 ms, p less than 0.01; and infarct (n = 93), from 197.7 (30.6) to 247.1 (34.2) ms, p less than 0.01. However, the percent change in refractoriness was greater in the infarct zone than in the normal zone, at 25.7(17.1)% v 16.2 (10.3)%, p less than 0.01. Furthermore, an area of functional unidirectional conduction block developed within the infarct zone where the maximal dispersion of ERP was observed. Inducible sustained ventricular tachycardia (SVT) was prevented in one dog and slowed (300 to 150 beats.min-1) in another by flecainide, while ventricular fibrillation remained inducible in one dog. Pro-arrhythmic effects were observed in two of five dogs without inducible SVT. In conclusion, flecainide significantly depressed conduction velocity and prolonged local refractoriness in the epicardial myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Suppressive effect of interferon-beta-activated natural killer cells on lipopolysaccharide-induced B cell differentiation of MRL/Mp-lpr/lpr mice.

The suppressive effects of mouse recombinant interferon-beta (IFN-beta) on B cell differentiation of MRL/Mp-lpr/lpr (MRL/1) mouse, a model of autoimmune diseases, and C3H/H2 mice, a normal situation, were investigated. Spleen mononuclear cells were cultured in the presence of lipopolysaccharide (LPS), and the suppressive effect of IFN-beta was examined on differentiation of B cells to plaque-forming cells (PFCs) by highly sensitive reversed hemolytic plaque assay. IFN-beta (5,000-10,000 units/ml) suppressed more than 50% of PFCs of both MRL/1 and C3H/H2 mice. This suppressive activity as well as the cytotoxicity of natural killer (NK) cells enhanced by IFN-beta was abrogated by treatment of the spleen cells with anti-asialo GM1 antibody in the presence of complement. This suppressive activity was also abrogated by intravenous administration of 20 microliter/mouse of anti-asialo GM1 12 hr before cultivation of spleen cells. These results suggest that NK cells activated by IFN might be responsible for the immunoregulation in autoimmune diseases.

Animals↗
PubMed1989

[Rapid diagnostic methods for fungal infections--using chromogenic limulus tests and enzymatic measurement of D-arabinitol].

Conventional chromogenic limulus test (toxicolor test) reacts with glucan of bakers yeast as well as endotoxin, because toxicolor test contains factor G which is sensitive to glucan and polysaccharide of fungus. A new endotoxin specific limulus test (endospecy test) was developed to improve reaction which responded only to endotoxin. The toxicolor test showed the positive reaction to the culture media of candida albicans 7N strain in RPMI 1640 medium, but the endospecy test did not. D-arabinitol, measured by fluometric enzymatic method, also was positive to culture media. These results suggested that a combination of the toxicolor and the endospecy test and enzymatic measurement of D-arabinitol could be applied to rapid diagnostic methods of fungal infection.

Humans↗