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Biomedical subjects

Y Seyama

Publications and source records attributed to Y Seyama.

At least 109 records · Page 6Linked to original sources
PubMed1992

[Effects of traditional Chinese medicines (dai-saiko-to, sho-saiko-to and hachimi-zio-gan) on spontaneously diabetic rat (WBN/Kob) with experimentally induced lipid and mineral disorders].

To clarify the therapeutic effects of several traditional Chinese medicines to improve disorders of carbohydrate, lipid and mineral metabolism, spontaneously diabetic rats (WBN/Kob) were treated with Vit. D2, 1 x 10(5) I.U./kg b.w./day, for 4 days, and then fed a hyperlipidemic diet containing traditional Chinese medicines for 6 weeks. The following results were obtained: 1) In the diabetic rats, the 3 traditional Chinese medicines further decreased the blood glucose level at 120 min after glucose loading in the glucose tolerance test. 2) The drugs increased the inorganic phosphate in the liver and normalized mineral metabolic disorder. 3) Hachimi-zio-gan decreased the cholesterol content in the kidney, and Sho-saiko-to decreased the cholesterol content in the elastin fraction (elastin-cholesterol) of the kidney. Such experimental results suggest that traditional Chinese medicines may be effective against the pathological conditions of diabetes mellitus that involve disorders of lipid and mineral metabolism.

Animals↗
PubMed1991

Characterization of prostaglandin and thromboxane receptors expressed on a megakaryoblastic leukemia cell line, MEG-01s.

MEG-01s, an established human megakaryoblastic leukemia cell line, exhibited specific high-affinity binding sites for [3H]iloprost, a stable prostaglandin (PG) I2 analogue, for [3H]SQ-29548, a stable thromboxane (TX) A2 antagonist and, for [3H]PGE2/PGE1, but not for [3H]PGD2. In the MEG-01s cells, iloprost/PGI2, or PGE1 stimulated cAMP production with ED50 values practically identical to the IC50 values for the [3H] iloprost binding. STA2 and U46619, TXA2/PGH2 agonists, PGE2/PGE1, iloprost/PGI2, and thrombin elevated the intracellular concentrations of Ca2+ ([Ca2+]i), as determined by Fura-2 fluorescence signals. Elevation of [Ca2+]i by PGE2/PGE1 and iloprost, but not that by TX-agonists or thrombin, was totally dependent on the presence of extracellular Ca2+. This effect by PGE2/PGE1 was partially inhibited by prior treatment of the cells with islet-activating protein (IAP), while that by TX-agonists or by PGI2/iloprost was not affected. We tentatively conclude from these results that: (1) MEG-01s cells express (a) PGI2/PGE1 receptor(s) coupled to adenylate cyclase and Ca2+ influx, a TXA2/PGH2 receptor coupled to the phosphatidylinositol-turnover-Ca2+ system, and the PGE2/PGE1 receptor coupled to Ca2+ influx; (2) the receptors for TXA2/PGH2 and iloprost and those for PGE2/PGE1 and thrombin are coupled to IAP-insensitive and IAP-sensitive GTP-binding proteins, respectively, and function in a different manner to elevate [Ca2+]i. Thus, the MEG-01s cell line is a pertinent model for studying eicosanoid receptor-mediated signal transduction in platelet/megakaryocyte systems.

Adenylate Cyclase Toxin↗
PubMed1991

Molecular cloning and expression of platelet-activating factor receptor from human leukocytes.

The cDNA for a platelet-activating factor (PAF) receptor was cloned from a human leukocyte cDNA library using a 0.8-kilobase pair fragment of the guinea pig lung PAF receptor cDNA (Honda, Z., Nakamura, M., Miki, I., Minami, M., Watanabe, T., Seyama, Y., Okado, H., Toh, H., Ito, K., Miyamoto, T., and Shimizu, T. (1991) Nature 349, 342-346). The cDNA (1.8-kilobase pairs) had an open reading frame encoding 342 amino acid residues with a calculated Mr of 39,203. The clone was shown to code for a PAF receptor based on the following criteria: 1) the amino acid sequence possesses seven putative membrane spanning domains with 83% identity to the guinea pig lung PAF receptor, 2) Xenopus laevis oocytes injected with the transcript of the clone showed an electrophysiological response to PAF, and 3) COS-7 cells expressing the encoded receptor showed ligand binding with the pharmacological properties of the PAF receptor. Activation of the PAF receptor yielded inositol 1,4,5-trisphosphate production in both COS-7 cells and oocytes, and guanosine 5'-O-(2-thio)bisphosphate injection into the oocytes inhibited PAF-induced Cl- current, providing an evidence that PAF stimulates phosphoinositide turnover via G-protein(s). PAF receptor mRNA was abundant in leukocytes and less so in an undifferentiated human eosinophilic cell line (EoL-1 cells) or human erythroleukemia cells (HEL cells). The production of the mRNA was prominently increased when EoL-1 cells were treated with granulocyte macrophage colony stimulating factor, interleukin-5, and n-butyrate.

Amino Acid Sequence↗
PubMed1991

Effects of cholestanol feeding on corneal dystrophy in mice.

A cholestanol-enriched diet administered for 8 months to BALB/c mice produced in 20% two kinds of corneal opacities resembling calcific band keratopathy and Schnyder's crystalline dystrophy in humans. The concentrations of cholestanol in serum, liver and cornea of the corneal opacity bearing mice were 30-40-times higher than those of normal mice. On the other hand, brain cholestanol level increased only 7-times in the opacity group as compared with that of control group. There was no significant difference in the cholesterol concentrations of serum and several tissues among opacity, non-opacity and the control group. The crystal particles were observed between epithelial basement membrane and superficial stroma by the electron microscopy. Energy dispersive analysis of the particles revealed that the deposits were composed principally of calcium and phosphorus with other crystalline materials, which was presumed to be cholestanol. These results suggest that the cholestanol may deposit in the cornea from elevated serum levels. Deposition of cholestanol in cornea and related area may be a cause of corneal dystrophy in CTX.

Animals↗
PubMed1991

Characterization of partially purified prostaglandin E2 receptor from the canine renal medulla: evidence for physical association of the receptor protein with the inhibitory guanine nucleotide-binding protein.

Prostaglandin (PG) E2 binding protein, a putative PGE2 receptor, was purified 26-fold with 0.4% recovery from canine renal outer medullary membranes solubilized with 12% digitonin with the sequential use of a Superose 12, Wheat Germ Agglutinin (WGA) Affigel 10, DEAE-5PW and Ampholine column chromatographies. The final preparation retained the binding activity specific for PGE2, but lost most of the sensitivity to guanosine-5'-(gamma-thio)triphosphate (GTP gamma S). An antibody against alpha subunit of the inhibitory guanine nucleotide-binding protein (alpha Gi)1 and alpha Gi2 or that against common sequences of alpha subunit of guanine nucleotide-binding proteins (alpha G(common)) reacted at 41 kDa protein in the sample of each step of purification, but failed to do so in the final preparation. An antibody against alpha Gi3 or alpha Go had no effect. In fact, peaks of the binding activity and immunoreactivity for alpha Gi1,2 were chromatographically separated by isoelectric focusing. Moreover, antibodies against alpha G(common) or alpha Gi1,2, but not that against alpha Gi3 and alpha Go, precipitated PGE2 binding activity in the active fractions of WGA-Affigel 10 column chromatography. These results suggest that the PGE2 receptor is an acidic glycoprotein and that Gi1 or Gi2 is physically associated with the PGE2 receptor and dissociates from the receptor protein during purification procedures.

Animals↗
PubMed1991

Cloning by functional expression of platelet-activating factor receptor from guinea-pig lung.

Platelet-activating factor (PAF), a unique phospholipid mediator, possesses potent proinflammatory, smooth-muscle contractile and hypotensive activities, and appears to be crucial in the pathogenesis of bronchial asthma and in the lethality of endotoxin and anaphylactic shock. Despite this, little is known of the molecular properties of the PAF receptor and related signal transduction systems. Although several lines of evidence suggest that activation of the PAF receptor stimulates phospholipase C and subsequent inositol trisphosphate formation through G protein(s), the PAF receptor and calcium channel are reported to show a close relation. As a first approach to cloning lipid autacoid receptors, we have isolated complementary DNA for the PAF receptors. Our strategy involved gene expression in Xenopus laevis oocytes and electrophysiological detection of PAF-induced responses. Sequence analysis indicates that the receptor belongs to the superfamily of G protein-coupled receptors.

Amino Acid Sequence↗
PubMed1991

Cerebrotendinous xanthomatosis: clinical and biochemical evaluation of eight patients and review of the literature.

We present the clinical and laboratory findings of 8 patients with cerebrotendinous xanthomatosis. The clinical features consisted of a combination of bilateral Achilles tendon xanthomas, cataracts, low intelligence, pyramidal signs, cerebellar signs, convulsions, peripheral neuropathy, foot deformity, cardiovascular disease or atherosclerosis, EEG abnormality, and increased CSF protein. Increased cholesterol was present in the serum, CSF and red cell membrane of all 8 patients. The bile of one patient with late age onset of the disease showed an attenuated production of bile acids and bile alcohols. Three of the 7 had obstruction and/or marked narrowing of the coronary arteries. Data on 136 patients reported throughout the world are reviewed.

Achilles Tendon↗
PubMed1991

The differences in 12-hydroxyeicosatetraenoic acid and thromboxane B2 release from guinea pig platelets.

Anti-12(S)-hydroxyeicosatetraenoic acid (12-HETE)-antibody and anti-thromboxane B2 (TXB2)-antibody were generated and applied to the radioimmunoassay. The detection limit for 12-HETE was 16 pg. The cross-reactivities of anti-12-HETE-antibody were 4.6% for 15-HETE, 0.18% for 5-HETE and below 0.15% for leukotrienes and prostaglandins (PGs). 12-HETE and TXB2 released from guinea pig platelets were measured by radioimmunoassay. Platelet activating factor (PAF) at 10(-9) M induced the aggregation of platelets, the releases of immunoreactive-12-HETE (1.8 +/- 1.2 ng/10(8) platelets, mean +/- S.D.) and immunoreactive-TXB2 (18.5 +/- 17.3 ng/10(8) platelets). Collagen at 1 microgram/ml also evoked platelet aggregation, the releases of immunoreactive-12-HETE (2.7 +/- 1.1 ng/10(8) platelets) and immunoreactive-TXB2 (11.8 +/- 4.6 ng/10(8) platelets). By the stimulation with these compounds, TXB2 was produced in a greater amount than 12-HETE from guinea pig platelets. Although 10(-7) M and 10(-6) M U46619, a TXA2 mimetic, caused platelet aggregation, arachidonic acid metabolites were not released. These data suggest the presence of different mechanisms of platelet activation depending on each stimulus.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1991

Two pathways for GM2(NeuGc) expression in mice: genetic analysis.

We have reported that WHT/Ht mice express neither GM2(NeuGc) nor GM1(NeuGc) in the liver or erythrocytes due to a defect on the Ggm-2 gene, which was demonstrated to control the activity of UDP-GalNAc:GM3(NeuGc) N-acetylgalactosaminyltransferase in mouse liver, and, in addition, WHT/Ht mice do not express a detectable amount of GM2(NeuGc) but do express GM1(NeuGc) in tissues other than the liver and erythrocytes, such as the spleen, thymus, heart, lung, kidney, and testis [Nakamura et al. (1988) J. Biochem. 103, 201-208]. In order to determine whether the phenotype of WHT/Ht mice exhibiting an undetectable amount of GM2(NeuGc) in these tissues is genetically controlled or not, we analyzed the expression of gangliosides in the progeny obtained on backcross mating between (BALB/c X WHT/Ht)F1 and WHT/Ht mice, and in a GM2(NeuGc) congenic mouse, WHT.C. Concerning the expression of GM2(NeuGc) in the liver, lung, and kidney, 102 backcross mice could be segregated into two types. One type expressed a detectable amount of GM2(NeuGc) in the liver, lung, and kidney, and the other type did not. The ratio of the numbers of mice exhibiting these two types was 42: 60, indicating that the two phenotypes were genetically determined by the involvement of a single autosomal gene. Recombination as to GM2(NeuGc) expression in the liver, lung, and kidney was not detected among the 102 backcross mice. Analysis of the GM2(NeuGc) congenic mouse indicated that a detectable amount of GM2(NeuGc) was expressed in the liver, erythrocytes, lung, kidney, heart, spleen, and small intestine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Composition of long chain bases in ceramide of the guinea pig Harderian gland.

Ceramide of the guinea pig Harderian gland was isolated and characterized. The purified ceramide gave two spots on thin-layer chromatography. Ceramide with the higher Rf value (NHCer) contained non-hydroxy fatty acids and that with the lower Rf value (HCer) contained 2-hydroxy fatty acids. The ratio of NHCer to HCer was 6:1. The non-hydroxy fatty acids of NHCer were composed of straight-chain acids (94.9%) and branched-chain acids (5.1%). The 2-hydroxy fatty acids were also composed of straight-chain acids (94.2%) and branched-chain acids (5.8%). The ratio of straight-chain acids to branched-chain acids was similar in NHCer and HCer. The long chain bases of NHCer and HCer consisted of straight chain sphinganines and sphingenines, and methyl-branched long chain bases. In NHCer, 59.9% of the total bases were methyl branched, and in HCer, 48.3%. The characteristics of ceramide, that is, the large amount of methyl-branched long chain bases and relatively small amount of methyl-branched fatty acids, are similar to those of cerebroside and sphingomyelin isolated from the same organ, although the ratios of constituents are different among these sphingolipids.

Animals↗
PubMed1991

[Early changes of postpneumonectomy lung growth in premature rats].

Following pneumonectomy in animals, the contralateral lung increases in volume, weight, collagen content, protein, and cell number, reaching levels approximate to those of both lungs of control animals. The volume and weight response in quicker and more complete in young animals compared to old animals. The increase in the amount of DNA was found to be greater in young rats compared to old ones. However, little is known about the effects of pneumonectomy in immature animals, in which combined effects of normal and the compensatory lung growth may be expected. The present studies were aimed at elucidating early changes in terms of morphology and biochemistry in the contralateral lung following pneumonectomy in premature rats. Male Sprague-Dawley rats (2 week-old) were subdivided into 3 groups. Group P, underwent left pneumonectomy, group S was sham operated, which group C was matched by age, sex, and weight with group P. Morphological studies consisted of light microscopic morphometry and immunohistochemistry using anti-bromodeoxyuridine (BrdU) were performed. Biochemical studies included measurement of DNA polymerase activity, DNA and RNA content, collagen and elastin content. The wet lung weight in group P after one week reached approximately the same as that of bilateral lungs of groups S and C. The fixed lung volume of group P reached that of group S or group C at three weeks. The activity of DNA polymerase and BrdU positive alveoli were increased only during the early period following pneumonectomy. DNA content in group P reached the same range as group S and C at 4 weeks, suggesting the occurrence of cellular hyperplasia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Leukotriene A4 hydrolase is a zinc-containing aminopeptidase.

A comparison of amino acid sequences revealed that leukotriene A4 (LTA4) hydrolase is homologous to various types of aminopeptidases. Consistently with the finding, the purified LTA4 hydrolases from both human and guinea pig sources contained equimolar zinc ion, as determined by atomic absorption spectrometry. The enzyme had a significant amount of aminopeptidase activity toward synthetic peptide substrates. Both LTA4 hydrolase and aminopeptidase activities were inhibited by o-phenanthroline, p-chloromercuribenzoic acid, and Leu-thiol with similar IC50 values. Co-purification as well as co-immunoprecipitation of both enzyme activities with an affinity-purified antibody against LTA4 hydrolase strongly suggest that the two enzyme activities reside in a single protein.

Aminopeptidases↗
PubMed1990

Characterization of the guinea pig lung membrane leukotriene D4 receptor solubilized in an active form. Association and dissociation with an islet-activating protein-sensitive guanine nucleotide-binding protein.

Membrane fractions from the guinea pig lung had high- and low-affinity binding sites for LTD4 with Kd values of 0.016 and 9.1 nM, respectively. In the presence of guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) or by prior treatment of the membrane with islet-activating protein (IAP), the high-affinity site shifted to a low-affinity state. Consistently, a 41-kDa protein was ADP-ribosylated by treatment of the lung membranes with IAP, and this event was inhibited by the addition of GTP gamma S. We solubilized the LTD4 receptor from the lung membranes in an active form with 5 mM 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) and 10% glycerol. On a gel filtration column, the binding activity was eluted at the volume corresponding to a Mr of 70,000 or over 500,000 in the presence or absence of Mg2+ (5-20 mM), respectively, in solubilizing buffers. The Kd value of [3H]LTD4 binding to the 70-kDa protein was similar to the low-affinity binding constant of the membrane and was insensitive to GTP gamma S. The preparation solubilized in the absence of Mg2+ showed both high- and low-affinity binding sites for LTD4, and the addition of GTP gamma S shifted the high-affinity site to a low-affinity one. Thus, 1) the LTD4 receptor is coupled to an IAP-sensitive GTP-binding protein, 2) this GTP-binding protein is dissociable from the receptor by solubilizing the lung membrane with CHAPS and Mg2+, and 3) the receptor associated to or dissociated from a GTP-binding protein exhibited a high- or low-affinity state, respectively. These data provide an insight into the molecular mechanism of regulation of the LTD4 receptor signaling process by association and dissociation with an IAP-sensitive GTP-binding protein.

Animals↗
PubMed1990

Use of radio-gas chromatography and tritium label to optimize derivatization procedures.

A sensitive determination of gas chromatographic peak yields by a new radio-gas chromatograph equipped with a synchronized accumulating radioisotope detector is described. Peak yields could be easily determined by the radio-gas chromatograph using [3H]hexadecane or [3H]androstenedione as a standard substance. The usefulness of the determination of peak yields was demonstrated by optimizing the derivatization conditions of 6-keto-prostaglandin F1 alpha.

6-Ketoprostaglandin F1 alpha↗
PubMed1990

Immunological quantitation and immunohistochemical localization of leukotriene A4 hydrolase in guinea pig tissues.

We prepared a highly specific polyclonal antibody against leukotriene (LT) A4 hydrolase using a recombinant human enzyme. Using this antibody, we quantified LTA4 hydrolase protein content in the cytosols of guinea pig tissues. The enzyme protein content correlated well with the enzyme activity with a correlation coefficient of 0.87. However, the enzyme activity per mg of the enzyme in the cytosols was low, particularly in the liver and adrenal gland, compared with the specific activity of the purified enzyme. These observations suggest the presence of inhibitory substances and/or inactive enzymes in the cytosols of these tissues. To determine the cellular localization of LTA4 hydrolase in tissues other than blood cells, we carried out immunohistochemical examinations of guinea pig tissues. We identified epithelial cells in the tracheobronchial system and gastrointestinal tract, smooth muscle cells in the bronchi and aorta, vascular endothelial cells, and the intestinal plexus as novel cellular sources of the enzyme in the parenchyme of the tissue. Thus, LTA4 hydrolase was widely distributed in various types of parenchymal cells in the tissues, and this observation warrants further investigations on the biological activities of LTB4 in these cells and tissues.

Animals↗
PubMed1990

Solubilization and characterization of leukotriene B4 receptor-GTP binding protein complex from porcine spleen.

A high amount of leukotriene B4 (LTB4) binding protein was observed in the porcine spleen. It was solubilized and partially purified from spleen membrane with 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS). Scatchard analysis indicated the presence of a single class of receptor with Kd and Bmax values of 0.26 nM and 120 fmol/mg protein, respectively. The receptor was specific for LTB4, and Ki values for 20-hydroxy- and 20-carboxy-LTB4, both inactive metabolites of LTB4, were 1.7 nM and over 1,000 nM, respectively. By the addition of 10 microM GTP gamma S, a low affinity binding site appeared with a Kd value of 390 nM. A pretreatment of the receptor-GTP binding protein complex with islet-activating protein (IAP) increased the inhibitory effect of GTP gamma S on LTB4 binding, indicating that the LTB4 receptor is coupled with an IAP-sensitive GTP-binding protein in the porcine spleen.

Animals↗