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Biomedical subjects

T Obata

Publications and source records attributed to T Obata.

At least 181 records · Page 10Linked to original sources
PubMed1990

Chromosomal transformation in Saccharomyces cerevisiae with DNA isolated by pulse field gel electrophoresis.

We isolated and purified yeast chromosome DNA molecules using pulse field gel electrophoresis (PFG). The isolated DNA had nearly the same size as the native chromosomal DNA on PFG. We could directly transform Saccharomyces cerevisiae yeasts with it, and obtain transformants that were selected by complementation of several markers. They had new chromosome DNA bands observed on PFG. The new chromosome was very stable during mitosis and mating processes, and each of the three homologous chromosomes in the derivative zygotes of transformants was separated equally in daughter cells.

DNA, Fungal↗
PubMed1990

[The application of flow cytometry in analysis of erythrocyte antigen determinants].

FCM has become an invaluable technique in a variety of clinical and research applications. Then, FCM is used for quantitative analysis of human erythrocyte antigens using Spectrum III. Antibody sensitizations give rise to erythrocyte agglutination making the FCM analysis of a single cell impossible. However, such agglutination could be prevented by some of erythrocyte fixations with PFA and DMS. To make examinations in an optimal concentration of primary antibodies was important for FCM assay. FCM was used to detect small percentage of D antigen positive cell contaminated in negative samples, subsequently positive cells were finally detected in 0.2%. This assay was utilized on a recipient of M/N mismatched allogeneic BMT, and an accurate proof of engraftment was obtained. Relationship of the numbers of antigen determinants and immunofluorescence intensities might be in linear correlation by log-log transformation. The fluorescence intensities of D antigen were analyzed for different rhesus phenotypes and variants such as Du and -D- cells. Lower fluorescence intensities on Du and higher intensities on -D- cell could be seen comparing with average value of D positive cells. However, no relationship between rhesus phenotypes and anti-D immunofluorescence intensities was observed. These findings suggest that FCM is useful and accurate technique for measuring relative antigen determinants of erythrocyte.

Blood Group Antigens↗
PubMed1990

Effect of procaterol on arterial blood gas in asthmatic children.

We determined changes in arterial blood gas after the inhalation of procaterol, a highly beta 2-selective and long-acting adrenergic agonist, in 11 asthmatic children. Seven of the patients, with a maximum fall of 14 mmHg (63.6%), showed a decrease in PaO2 (mean +/- SD = -7.1 +/- 4.0 mmHg) and had poorer pulmonary function with a lower initial PaO2 than four subjects who had an increase in PaO2 after inhalation. There was a statistically significant correlation between values of the PaO2 before and after inhalation (P less than .05).

Administration, Inhalation↗
PubMed1990

Isoelectric analysis of 3H-pargyline-labelled monoamine oxidase in rat and carp.

1. After selective binding of [3H]pargyline to either monoamine oxidase (MAO) A or MAO B in the rat liver, MAO B alone in the rat brain and MAO in carp brain and liver, molecular weight and isoelectric points (pI) of these MAO were determined by sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis and isoelectric focusing and results obtained were compared. 2. For all tissues tested, SDS-polyacrylamide gel electrophoresis of [3H]pargyline-bound samples revealed a labelled protein band of an apparent mol. wt of 60,000 da. 3. Estimation of radioactivity of [3H]pargyline bound after isoelectric focusing revealed a single protein band with acidic pI values of about 5.5 for rat brain and liver MAO B. 4. Moreover, the pI values of about 7.5 were obtained for carp brain and liver MAO. This basic value was also found for MAO A in the rat liver MAO A.

Animals↗
PubMed1990

[Effects of procaterol on arterial blood gas and pulmonary function in asthmatic children].

We examined the changes in arterial blood gas, FEV1 and V50 after the inhalation of procaterol on 19 occasions in 16 asthmatic children. The initial value of PaO2 had statistically significant correlation with the initial values of %FEV1 and %V50. PaO2 fell down in 11 out of 19 (57.9%) and remarkably decreased more than 5 mmHg in 6 out of 19 (31.6%). The fall in PaO2 was most significant at 5 min after the inhalation in almost subjects. The changes in PaO2 after the inhalation had good correlation with the initial value of %FEV1 and %V50. The initial values were quite lower in the patients with decreased PaO2 more than 5 mmHg than those with increased PaO2. Severe patients showed statistically low values of the initial PaO2 and %V50 and showed a fall in PaO2 after inhalation compared with moderate patients. An increase in A-aDO2 elicited that deteriorations of V/Q ratio caused a decrease in PaO2 after inhalation. There were no significant changes in heart rates and no complaints of nausea, headache or tremor.

Administration, Inhalation↗
PubMed1990

Leakage of thyroid hormone-inducible monoamine oxidase inhibitor from rat liver cytosol.

T4-induced endogenous monoamine oxidase (MAO) inhibitor in rat liver perfusate by perfusion with sucrose buffer and lipid peroxide (LPO) and superoxide dismutase (SOD) in rat liver tissues were investigated after pretreatment with total hepatic ischemia. When the gel filtration of these rats liver perfusate were carried out using Sephadex G-25, fraction 18-20 were found to inhibit MAO activity. LPO of these rats were increased, but SOD activity was decreased. The accumulation of lipid peroxides would partly result from decreased activity of SOD as a consequence of membrane disorders. These results suggest that T4-induced MAO inhibitor in rat cytosol was released into plasma by membrane disorder.

Animals↗
PubMed1989

Lactamimides: a novel chemical class of calcium antagonists with diltiazem-like properties.

The effects of a series of lactamimides on [3H]d-cis-diltiazem binding to rat brain membranes, on [3H]nitrendipine binding to cardiac membranes, and on calcium-induced contractions in depolarized guinea pig taenia and ileum preparations were examined. Several of the lactamimides examined displaced [3H]d-cis-diltiazem binding and antagonized, in a competitive fashion, calcium-induced contractions. Over the series of lactamimides, there was a highly significant, positive linear correlation (r = 0.87, P less than 0.001) between their potency to displace [3H]d-cis-diltiazem and their potency to antagonize calcium-induced contractions in the depolarized taenia and ileum preparations. Of the lactamimides examined, MDL 16,582A [N-(2,2-diphenylpentyl)azacyclotridecan-2-imine. hydrochloride] had potency equivalent to d-cis-diltiazem with pA2 values of 7.27 and 7.38, respectively, against calcium-induced contractions in the guinea pig ileum. These lactamimides are a novel chemical class displaying diltiazem-like calcium antagonist properties.

Animals↗
PubMed1989

Endogenous monoamine oxidase inhibitor-like substances in monkey brain.

The extraction and partial purification of endogenous "monoamine oxidase (MAO) inhibitor-like" material from the monkey brain are described. The endogenous material (F-1 and F-2) obtained after Bio-Gel P-2 gel filtration and silica column chromatography inhibited MAO in the monkey brain mitochondria toward 5-hydroxytryptamine (5-HT), beta-phenylethylamine (beta-PEA), tyramine and dopamine as substrates. The inhibitory effects of F-1 and F-2 were non-linear concentration dependent, and F-1 non-competitively inhibited A-form MAO, while F-2 inhibited A-form MAO competitively and inhibited B-form MAO non-competitively. These substances were more potent inhibitors of A-form than of B-form MAO. F-2 was heat stable but liable to the treatment with pepsin and trypsin. F-1 was not inactivated by heat treatment and digestion with pepsin and trypsin. F-1 may be a low molecular weight (less than 1350) compound, including certain monoamines or their metabolites or other unidentified compounds, while F-2 was a low molecular weight (about 2500) peptide.

Animals↗
PubMed1989

A cytoplasmic thyroid hormone binding protein: characterization using monoclonal antibodies.

We have previously purified a cellular thyroid hormone binding protein (p58) from a human carcinoma cell line [Kitagawa, S., Obata, T., Hasumura, S., Pastan, I., & Cheng, S.-y. (1987) J. Biol. Chem. 262, 3903-3908]. In the present study, the binding characteristics, the molecular properties, and subcellular localization of p58 were further characterized. Binding of the purified p58 to thyroid hormones was examined. Analysis of binding data indicates that p58 binds to 3,3',5-triiodo-L-thyronine (T3) with a Kd of 24.3 +/- 0.3 nM and n = 0.71. p58 binds to L-thyroxine similarly as to T3. However, D-T3 and reverse-T3 bind to p58 with an affinity 4- and 20-fold less than that of T3, respectively. By use of the purified p58 as an immunogen, two hybridomas, J11 and J12, secreting monoclonal antibodies to p58 were isolated; both antibodies belong to the IgG1K subclass. J12 recognizes p58 from human, monkey, dog, hamster, and rat, but not mouse. J11 exhibits a similar species specificity except that it does not react with p58 from hamster. With these antibodies, p58 was found to be not posttranslationally modified by glycosylation, sulfation, or phosphorylation. It has a cellular degradation rate t1/2 congruent to 2.1 h. Immunocytochemical studies indicate that p58 is located in the nonmembranous cytoplasm (cytosol). These results are consistent with subcellular fractionation studies which show that greater than 95% of J11 and J12 reactivity and T3 binding activity can be found in the 110,000g supernatant.

Animals↗
PubMed1989

A case of exercise-induced anaphylaxis: evidence of an association with the complement system.

We studied a 17-year-old girl with exercise-induced anaphylaxis (EIA). She experienced 10 episodes of EIA which demonstrated cutaneous, digestive and cardiorespiratory symptoms. This subject exhibited elevation in plasma histamine (13.3 ng/ml) and decrease in CH50 (17 U/ml) and C3 (70 mg/dl) after naturally induced EIA. On remission day CH50 (26 U/ml), C3 (83 mg/dl) and C4 (15 mg/dl) were of relatively low values. Her mother demonstrated the same tendency with a low level of C4 (14 mg/dl), and this suggested an underlying genetic disorder in the complement system. Exercise challenge could not elicit EIA symptomatically but showed fluctuation of CH50. The triggering mechanism of EIA was unclear; however there is a possibility that complement plays an important role in EIA.

Adolescent↗
PubMed1989

[Neurochemical studies on bifemelane, a new cerebral function improver. I. Effects of bifemelane on the function of neurotransmission-related enzymes and receptors in rat brain].

We examined neurochemically the effects of bifemelane (BF) on muscarinic ACh (mACh-R) and beta-adrenergic receptors (beta-AdR) and imipramine binding sites and the activities of acetylcholinesterase (AChE), choline acetyltransferase (CAT) and monoamine oxidase (MAO) in the P2 fractions of rat brain, ex vivo and in vitro. Male rats were given daily injections of 10, 30 mg/kg BF, p.o., for a period of 4 weeks. The Kd and Bmax values for mACh-R in the rat forebrain by administration of 10, 30 mg/kg BF decreased significantly compared with that of the control, although the Kd and Bmax values for beta-AdR and imipramine binding sites were almost identical. The Km and Vmax values of A- and B-form MAO decreased in rats that had been administered 30 mg/kg BF for 4 weeks. The binding of 3H-QNB (quinuclidinyl benzilate) on mACh-R, 125I-CYP (iodocyanopindolol) on beta-AdR and 3H-imipramine on imipramine binding sites decreased by 60, 20 and 70% in the presence of 1 microM BF, respectively, while the addition of 1 microM BF inhibited MAO activity by about 50%. However, CAT and AChE activities were not inhibited by BF.

Acetylcholinesterase↗
PubMed1989

Effect of diethylnitrosamine on monoamine oxidase in rat liver.

The effect of diethylnitrosamine (DEN), a well-known experimental carcinogen, toward MAO-A and MAO-B activity of rat liver was investigated. The oxidations of both beta-PEA (MAO-B) and 5-HT (MAO-A) were inhibited by DEN. The K1 values of DEN in the inhibition of rat liver MAO-A and MAO-B activity were determined. The kinetic data show that DEN is a competitive, MAO-B selective inhibitor and its inhibitory effect on MAO-B is about 4-fold more potent than that on MAO-A. DEN might change the proportions of the multiple forms of MAO activity in tumor cells.

Animals↗
PubMed1989

Amine oxidase released into plasma of rats treated with hepatotoxin allyl formate.

Amine oxidase activity in plasma of rats were investigated after pretreatment with the perilobular hepatotoxin allyl formate (AF). Amine oxidase activities in plasma elevated after administration of AF 0.1 ml/kg i.p. to male rats with 1 microM and 100 microM benzylamine (Bz), 10 microM beta-phenylethylamine (beta-PEA) and 100 microM serotonin (5-HT) as substrates. But the complete inhibition of amine oxidase activities with 5-HT and beta-PEA were not observed by clorgyline as A-form MAO inhibitor and deprenyl as beta-form MAO inhibitor. The deamination of 1 microM Bz was not inhibited at high concentrations of these MAO inhibitors, while it was inhibited at low concentrations of phenelzine and semicarbazide. On the other hand, the deamination of 100 microM Bz was highly sensitive with these MAO inhibitors, while it was less sensitive with phenelzine and semicarbazide as compared with 1 microM Bz. Then, the Km values of amine oxidase in plasma of AF-administered rats with Bz as substrate were determined from Lineweaver-Burk double reciprocal plots. Two Km values for Bz of high and low Bz concentration in amine oxidase in plasma of AF-administered rats were obtained. However, this Km value of low Bz concentration was not obtained from liver mitochondria and microsomes of control rat and AF-administered rats. The Km value for beta-PEA of MAO in plasma of AF-administered rats was the same as the values of rat liver mitochondrial MAO. These results indicate that native mitochondrial MAO was released from the liver, and two or more distinct amine oxidases were released from other organs in response to AF.

Animals↗
PubMed1989

[Infantile JRA and ACTH therapy].

Systemic juvenile rheumatoid arthritis is characterized by chronic arthritis and associated with extra-articular features. Although JRA may present at any age throughout childhood, the onset of symptoms during the first year of life is relatively uncommon. The diagnosis of infantile JRA is difficult because of poor complaints. We had a 7-month-old female, first onset at 6 months of age for daily "spiking" fever and skin rash, subsequently developed signs of systemic rheumatoid arthritis. Although aspirin or other nonsteroidal anti-inflammatory agents were used for the therapy, no significant effect was obtained. Prednisone was administered to control arthritis and serious systemic features, however no satisfactory effect was shown. In this patient a single morning alternate-day shot of ACTH-Z (4 units) was employed, and this regimen showed significant effect to control her clinical symptoms. It may be necessary to add a small dose of ACTH-Z for control in some cases of infantile JRA patient compared to adult cases.

Adrenocorticotropic Hormone↗
PubMed1989

Monoamine oxidase activity in the liver of rats given diethylnitrosamine.

The effect of diethylnitrosamine (DEN), a well known experimental carcinogen, MAO-A and MAO-B activity of rat liver was investigated. The oxidations of both 5-HT (MAO-A) and beta-PEA (MAO-B) were inhibited by DEN in vitro. DEN is reversible inhibitor, after enzyme-inhibitor preincubation. MAO-B activity in rat liver was decreased by continuous administration of 50 ppm DEN for several definite periods to rats. The almost 2-fold increase in the ratio of MAO-A/MAO-B was observed in rat liver mitochondria and microsomes. When 5-HT was used as substrate, there was no significant difference of Km and Vmax values between mitochondrial preparations from livers of control and DEN fed rats. However, when the mitochondria from livers of DEN fed rats were used as enzyme preparation, Vmax decreased to about 47% of the control with beta-PEA as substrate. DEN might change the proportions of the multiple forms of MAO activity in tumor cells.

Animals↗
PubMed1988

Antibodies against the human cellular 3,3',5-triiodo-L-thyronine-binding protein (p 58).

High-titer antibodies against a cellular thyroid hormone-binding protein (Mr 58,000, p58) were developed by a special immunization method. To enhance immune responses, this method uses a boosting protocol in which repeated injections of small amounts of antigen are administered at 2-day intervals. Antibodies were detected 1 week after the last injection of antigen by ELISA, Western dot blotting and immunoprecipitation. The anti-p58 antibodies recognized p58 which is bound to the thyroid hormone. With the availability of anti-p58 antibodies, it has become possible to study cellular localization and function.

Animals↗
PubMed1988

Thyroid hormone down-regulates p55, a thyroid hormone-binding protein that is homologous to protein disulfide isomerase and the beta-subunit of prolyl-4-hydroxylase.

We have previously characterized a cellular thyroid hormone-binding protein (p55) that is found concentrated on the lumenal face of the endoplasmic reticulum and nuclear envelope (Cheng, S.-y., Hasumura, S., Willingham, M.C., and Pastan, I. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 947-951). To understand the role p55 plays in thyroid hormone action, we examined the regulation of p55 by 3,3',5-triiodo-L-thyronine (T3). Rat pituitary tumor GH3 cells cultured in regular medium, thyroid hormone-depleted medium (Td medium), or Td medium supplemented with 50 nM T3 (Td + T3 medium) were metabolically labeled with [35S]methionine and immunoprecipitated with antibodies against p55. Treatment with T3 caused a fall in p55 levels. Poly(A+) RNA from cells cultured in regular, Td, or Td + T3 medium was hybridized to a cDNA from p55. T3 withdrawal or addition had no effect on p55 mRNA levels. Furthermore, the initial rates of synthesis of p55 from cells cultured in regular, Td, and Td + T3 were found to be similar. However, analysis of the decay curves from cells in which p55 was pulse-labeled with [35S]methionine indicated that p55 is 2-fold less stable in T3 containing medium. These results indicated that down-regulation of p55 by T3 occurs at the post-translational level. Since DNA sequence analysis indicates that p55 is identical to protein disulfide isomerase and the beta-subunit of prolyl-4-hydroxylase, T3 may mediate its effects on the synthesis, secretion, and/or transport of proteins via p55.

Animals↗