Biomedical subjects

M Negishi

Publications and source records attributed to M Negishi.

At least 235 records · Page 13Linked to original sources

PubMed1993

[An efficient method for quantification of Helicobacter pylori in biopsy specimen using PCR].

A procedure for the detection and quantification of Helicobacter pylori in gastrointestinal tissue biopsy specimens by polymerase chain reaction (PCR) is presented. This method provides an accurate quantitative and sensitive measurement of the amount of H. pylori in the gastrointestinal tract without cultivation of this microorganism. We have used 30 cycles of PCR in the presence of 3.5mM Mg++ and demonstrated that the DNA content of one H. pylori cell is 0.0076pg. Using this approach, we analyzed samples of gastrointestinal tissue biopsies from 10 patients with various gastrointestinal disorder. Each of these patients had detectable H. pylori at levels ranging from 0.10 to 60.61 cells for each tissue cell. This new technique thus provides a useful way to detect H. pylori in gastrointestinal tissue biopsy specimens.

Adult↗

PubMed1992

Prostaglandin E2-induced arachidonic acid release and catecholamine secretion from cultured bovine adrenal chromaffin cells.

We recently reported that prostaglandin E2 (PGE2) and arachidonic acid (AA) each induced a gradual secretion of catecholamines from cultured bovine adrenal chromaffin cells in the presence of ouabain by stimulation of phosphoinositide metabolism. In the present study, we examined the relationship between phospholipase A2 and C activation and catecholamine secretion by PGE2 in chromaffin cells. The phospholipase A2 inhibitors p-bromophenacyl bromide and mepacrine did not affect the basal and ouabain-induced release, but dose-dependently blocked PGE2-evoked phosphoinositide metabolism and the consequent catecholamine release at an IC50 value of 3 microM. PGE2 induced rapid hydrolysis of [3H]AA from prelabeled phospholipid pools: the release of [3H]AA could be detected at as early as 15 sec and reached a plateau after 1 min. While the phospholipase C inhibitor neomycin did not inhibit PGE2-induced AA release, phospholipase A2 inhibitors dose-dependently inhibited it at IC50 values comparable to those for catecholamine release. Pretreatment of intact cells with the phorbol ester 12-O-tetradecanoylphorbol 13-acetate, but not with pertussis toxin, prevented AA release by PGE2. These results demonstrate that PGE2 activates phospholipase A2 as well as phospholipase C in a pertussis toxin-insensitive manner and suggest that the released arachidonic acid may be involved in PGE2-induced catecholamine release from chromaffin cells.

Adrenal Medulla↗

PubMed1992

Oligosaccharide composition of the neurotoxin-responsive sodium channel of mouse neuroblastoma and requirement of sialic acid for biological activity.

A glycoprotein, M(r) 200,000, which has the biological activity of the neurotoxin-responsive Na+ channel, was isolated from a clonal line of mouse neuroblastoma cells, N-18. The glycoprotein was purified to homogeneity in 18% yield by methods used to purify glycoproteins, which included metabolic labeling of the cells with L-[3H]fucose and binding of the radioactive glycoproteins to WGA- and lentil-Sepharose, and DEAE-cellulose. The glycoprotein has biological activity of neurotoxin-responsive ion flux when reconstituted into artificial phospholipid vesicles. This activity was shown to depend on the presence of sialic acid since treatment of the purified, reconstituted glycoprotein with Vibrio cholerae neuraminidase abolished the response to neurotoxins of 86Rb flux. The [3H]fucose-containing glycopeptides derived by Pronase digestion of the glycoprotein were characterized by affinity to immobilized lectins and contained di-, tri-, and tetra-antennary oligosaccharides in a ratio of 2:4:3. Most of the glycopeptides were sialylated as shown by binding characteristics to immobilized serotonin-Sepharose with and without neuraminidase. The structure of the diantennary oligosaccharides was elucidated by 500-MHz 1H NMR spectroscopy. The Con A-bound fraction contains alpha-NeuNAc-(2-->6)-bound group on the GlcNAc5' antenna and an alpha-NeuNAc-(2-->3)-bound groups on the GlcNAc5 antenna. An alpha-L-fucosyl group is (1-->6)-bound to the Asn core GlcNAc1 residue.

Animals↗

PubMed1992

Interaction of alpha subunit of GTP-binding protein Go with a 20-kDa Triton-insoluble membrane protein in bovine brain.

Heterotrimeric Go bound to the membranes of bovine brain, but Go alpha remained bound to the membranes even after activation with GTP gamma S. Furthermore, Go alpha bound to a Triton X-100-insoluble fraction of the membranes in a saturable manner. However, the 37-kDa Go alpha eliminated by trypsin at the amino-terminus could not bind to the fraction. Using a blot overlay approach of the Triton-insoluble fraction, only a 20-kDa protein was identified that interacts with Go alpha. These results indicate that Go alpha binds to a 20-kDa Triton-insoluble protein in the bovine brain membranes.

Animals↗

PubMed1992

Roles of residues 129 and 209 in the alteration by cytochrome b5 of hydroxylase activities in mouse 2A P450S.

Cytochrome b5 stimulates the coumarin 7-hydroxylation activity of P450coh. A mutation of Arg-129 in P450coh, however, abolishes the stimulation. Moreover, this mutant P450coh binds loosely to cytochrome b5-conjugated Sepharose 4B, whereas wild-type P450coh binds tightly. Consistent with this, the mutation increases the Ka value for b5 binding approximately 6-fold. The identity of residue 209 also alters the stimulation of the activity of P450coh depending on the type of the substrates used and products formed. Coumarin 7-hydroxylation activity is greatly stimulated by cytochrome b5 only when Phe is at position 209, while cytochrome b5 stimulates testosterone hydroxylation activity of P450coh in which Phe, Asn, Ser or Lys substitutes residue 209. P450coh changes its rate of hydrogen peroxide formation depending on the identity of residue 209 and substrate used. Cytochrome b5 decreases the hydrogen peroxide formation of some P450coh whose activities are stimulated by the cytochrome; however, the decrease does not always result in stimulating the activity. The results indicate, therefore, that residues 129 and 209 play different roles in stimulating P450coh activity by cytochrome b5; Arg-129 is a key residue in the cytochrome b5-binding domain and is essential for the stimulation. Residue 209, however, alters the efficiency of electron transport for substrate oxidation as a residue which resides near the sixth ligand of heme and in the substrate-binding site.

Animals↗

PubMed1992

Glycyrrhetinic acid bound to 11 beta-hydroxysteroid dehydrogenase in rat liver microsomes.

A binding protein which exhibits high affinity to [3H]glycyrrhetinic-acid in the rat liver microsomal fraction was solubilized with 0.2% Triton DF-18 and then purified to homogeneity. The equilibrium dissociation constant of the [3H]glycyrrhetinic-acid binding reaction and the maximal concentration for the binding of the purified protein, as determined by Scatchard plot analysis, were 27.6 nM and 7.79 nmol/mg protein, respectively. The molecular mass of the subunit (34 kDa) and 30 amino acids of N-terminal sequence of the purified protein were entirely the same as those of the reported 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD). In each purification step, the recovery and purification (fold) of the glycyrrhetinic-acid binding activity corresponded to the values of 11 beta-HSD activity. These results show that the purified [3H]glycyrrhetinic-acid binding protein is 11 beta-HSD. From the molecular mass of 11 beta-HSD (135 kDa) and the maximal concentration of the binding site, it was calculated that one glycyrrhetinic acid molecule binds to one 11 beta-HSD molecule. The inhibitory effects of various glycyrrhetinic-acid derivatives on [3H]glycyrrhetinic acid binding and 11 beta-HSD activity indicate that the C30-carboxyl and C11-carbonyl groups of glycyrrhetinic acid are the principal structures for the 11 beta-HSD inhibition.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed1992

Inhibitory effect of an intracellular glutathione on delta 12-prostaglandin J2-induced protein syntheses in porcine aortic endothelial cells.

Delta 12-Prostaglandin (PG) J2 caused porcine aortic endothelial cells to synthesize a 31,000-dalton heme oxygenase and a 67,000-dalton protein (p67). Treatment of the cells with buthionine sulfoximine (BSO), an inhibitor of glutathione (GSH) synthesis, depleted intracellular GSH, and enhanced the induction of heme oxygenase and p67 syntheses by delta 12-PGJ2. In contrast, treatment with GSH increased the intracellular GSH level and reduced the induction. There was a reciprocal relationship between the level of intracellular GSH, and that of the induction of heme oxygenase and p67 syntheses by delta 12-PGJ2. An increase in the intracellular GSH level caused an increase in the ethyl acetate-unextractable form of delta 12-PGJ2 in the cytosol, but suppressed the accumulation of delta 12-PGJ2 in the nuclei. Furthermore, GSH strongly inhibited the in vitro binding of delta 12-PGJ2 to isolated nuclei, which is N-ethylmaleimide sensitive. Moreover, the induction of heme oxygenase and p67 syntheses by the thiol-reactive agents arsenite and diethylmaleate was also inhibited by GSH treatment and enhanced by BSO treatment. These results demonstrate that intracellular GSH suppresses delta 12-PGJ2-induced heme oxygenase and p67 syntheses by inhibiting the binding of delta 12-PGJ2 to nuclei.

Animals↗

PubMed1992

Identification of the prostacyclin receptor by use of [15-3H1]19-(3-azidophenyl)-20-norisocarbacyclin, an irreversible specific photoaffinity probe.

The prostaglandin I (PGI2) receptor of mouse mastocytoma P-815 cells was characterized by photo-affinity labeling with the stable PGI2 analogue [15-3H1]-19-(3-azidophenyl)-20-norisocarbacyclin ([3H] APNIC) used as a potential photoaffinity probe for the receptor. [3H]APNIC bound to the mastocytoma membrane with high affinity and in a saturable manner. Scatchard plot analysis indicated a single binding site with a Kd of 4.7 nM and a Bmax of 0.58 pmol/mg protein. The binding of [3H]APNIC was dose dependently inhibited by APNIC and iloprost, another stable PGI2 agonist, and to a much lesser extent by PGE2. The binding of the radioligand showed sensitivity to the guanine nucleotide guanosine 5'-O-(3-thio-triphosphate) (GTP gamma S). Photolysis of [3H]APNIC-prelabeled membranes resulted in incorporation of radiolabel into a protein of approximately 43 kDa. Photolabeling was inhibited by PGI2 agonists and other prostaglandins with specificity for the PGI2 receptor and was modulated by GTP gamma S. A protein of approximately 45 kDa was also labeled by [3H]APNIC in the membrane of porcine platelets, membranes that are known to be abundant in PGI2 receptors. These results demonstrate that [3H]APNIC specifically labels a protein that may represent the PGI2 receptor and that this radioprobe will be a useful reagent for further characterization and purification of the PGI2 receptor.

Affinity Labels↗

PubMed1992

Mouse thromboxane A2 receptor: cDNA cloning, expression and northern blot analysis.

A cDNA clone for the mouse thromboxane A2 receptor was isolated from mouse lung cDNA library. The cDNA has a 1,023 base pair open reading frame which encodes a protein of 341 amino acid residues. STA2 and U-46619 induced inward current in Xenopus laevis oocytes injected with the transcript of the clone. Specific binding of [3H]S-145 was found in membranes of COS-1 cells transfected with the cDNA (Kd = 3.3 nM) and was displaced with unlabeled prostaglandins and thromboxane analogues in the order of S-145 greater than STA2 greater than U-46619 greater than PGD2 greater than PGF2 alpha = PGE2. Northern blot analysis demonstrated that thromboxane A2 receptor mRNA is expressed abundantly in thymus, spleen and lung.

Amino Acid Sequence↗

PubMed1992

Cloning and expression of a cDNA for mouse prostaglandin E receptor EP3 subtype.

A functional cDNA clone for mouse EP3 subtype of prostaglandin (PG) E receptor was isolated from a mouse cDNA library using polymerase chain reaction based on the sequence of the human thromboxane A2 receptor and cross-hybridization screening. The mouse EP3 receptor consists of 365 amino acid residues with putative seven-transmembrane domains. The sequence revealed significant homology to the human thromboxane A2 receptor. Ligand binding studies using membranes of COS cells transfected with the cDNA revealed specific [3H]PGE2 binding. The binding was displaced with unlabeled PGs in the order of PGE2 = PGE1 greater than iloprost greater than PGF2 alpha greater than PGD2. The EP3-selective agonists, M&B 28,767 or GR 63799X, potently competed for the [3H]PGE2 binding, but no competition was found with EP1- or EP2-selective ligands. PGE2 and M&B 28,767 decreased forskolin-induced cAMP formation in a concentration-dependent manner in Chinese hamster ovary cells permanently expressing the cDNA. Northern blot analysis demonstrated that the EP3 mRNA is expressed abundantly in kidney, uterus, and mastocytoma P-815 cells and in a lesser amount in brain, thymus, lung, heart, stomach, and spleen.

Alprostadil↗

PubMed1992

Involvement of protein kinase C in thrombin-induced translocation of Gi2 alpha from the membrane to the cytosol in mouse mastocytoma P-815 cells.

Recently, we reported that in mouse mastocytoma P-815 cells the cytosol contains some factor(s) which promotes the release of GTP-activated Gi2 alpha from the membrane, and that thrombin induces the translocation of Gi2 alpha from the membrane to the cytosol (Takahashi, S., Negishi, M. and Ichikawa, A. (1991) J. Biol. Chem. 266, 5367-5370). Here we investigated the mechanism underlying the thrombin-induced translocation of Gi2 alpha in mastocytoma cells. Thrombin induced a rapid and transient increase in the intracellular Ca2+ concentration ([Ca2+]i) within 1 min, attenuated pertussis toxin-catalyzed ADP-ribosylation of Gi2 in the membrane, and caused the subsequent translocation of Gi2 alpha. Thrombin induced the translocation of protein kinase C from the cytosol to the membrane, and a protein kinase C inhibitor, staurosporine, completely inhibited the thrombin-induced translocation of Gi2 alpha. When cells were treated with thrombin, the ability of the cytosol to release Gi2 alpha from the membrane in the presence of GTP gamma S markedly increased. This stimulatory effect of thrombin on the ability of the cytosol was mimicked by 12-O-tetradecanoylphorbol 13-acetate (TPA), but not by the Ca2+ ionophore, ionomycin. The thrombin- and TPA-induced potentiation of the ability of the cytosol to release Gi2 alpha was completely abolished by staurosporine. Furthermore, phosphorylation of the cytosol by protein kinase C markedly potentiated the ability of the cytosol to release Gi2 alpha. These results together demonstrate that the thrombin-induced translocation of Gi2 alpha is due to enhancement of the ability of the cytosol to release Gi2 alpha via activation of protein kinase C.

Adenosine Diphosphate Ribose↗

PubMed1992

Translocation of alpha subunits of stimulatory guanine nucleotide-binding proteins through stimulation of the prostacyclin receptor in mouse mastocytoma cells.

The translocation of the alpha subunits of Gs from the membrane to the cytosol by iloprost, a stable prostacyclin analogue, was studied in mouse mastocytoma P-815 cells. In the presence of guanosine 5'-O-(thiotriphosphate) (GTP gamma S), iloprost stimulated the adenylate cyclase activity, caused the release of both 42- and 45-kDa proteins reactive with the anti Gs alpha carboxyl-terminal antibody, RM/1, from the membrane and attenuated cholera toxin-catalyzed ADP-ribosylation of the 42- and 45-kDa proteins in the membrane. The iloprost-stimulated adenylate cyclase activity and release of Gs alpha from the membrane were markedly suppressed by RM/1. Cholera toxin treatment also stimulated the adenylate cyclase activity and release of Gs alpha from the membrane, and iloprost synergistically potentiated these actions of cholera toxin. In mastocytoma cells, iloprost induced the translocation of both 42- and 45-kDa Gs alpha from the membrane to the cytosol, 45-kDa Gs alpha remaining in the cytosol for a longer time than 42- kDa Gs alpha. Whereas 42-kDa Gs alpha in the cytosol was eluted at the position of Mr = approximately 40,000 45-kDa Gs alpha was eluted at the position of Mr = approximately 120,000 from a Superose 12 gel filtration column. In contrast, both 42- and 45-kDa Gs alpha released in vitro from the membrane by iloprost plus GTP gamma S were eluted at the position of Mr = approximately 40,000, but only 45-kDa Gs alpha was eluted at the position of Mr = approximately 120,000 when it was incubated with cytosol. These results taken together demonstrate that iloprost induces the translocation of both 42- and 45-kDa Gs alpha from the membrane to the cytosol and that only the 45-kDa Gs alpha released exists in the cytosol as a soluble complex with unidentified component(s) in mastocytoma cells.

Adenosine Diphosphate Ribose↗

PubMed1992

Direct linkage of three tachykinin receptors to stimulation of both phosphatidylinositol hydrolysis and cyclic AMP cascades in transfected Chinese hamster ovary cells.

The mammalian tachykinin system consists of three distinct peptides, substance P, substance K, and neuromedin K, and possesses three corresponding receptors. In this investigation we examined intracellular signal transduction of the individual tachykinin receptors by transfection and stable expression of these receptor cDNAs in Chinese hamster ovary cells. The three receptors commonly showed a rapid and marked stimulation in both phosphatidylinositol (PI) hydrolysis and cyclic AMP formation in response to tachykinin interaction. Direct linkage of the three receptors to both phospholipase C and adenylate cyclase was evidenced by the finding that tachykinin, added together with GTP, activated these enzyme activities in membrane preparations derived from tachykinin receptor-expressing cells. The stimulation of cyclic AMP formation was less efficient than that of PI hydrolysis in receptor-expressing cells as well as their membrane preparations (about 1 order of magnitude difference in the effective peptide concentrations). However, the stimulatory responses of the PI hydrolysis and cyclic AMP formation in both receptor-expressing cells and their membrane preparations were induced in complete agreement with the tachykinin binding selectivity of each subtype of the receptors. This investigation demonstrated unequivocally that the tachykinin receptors have the potential to couple directly to both phospholipase C and adenylate cyclase and to stimulate PI hydrolysis and cyclic AMP formation.

Adenylyl Cyclases↗

PubMed1992

Feeding behavior and ambulatory activity in rats with D-galactosamine-induced hepatic failure.

This study was undertaken to investigate changes in feeding behavior and ambulatory activity, in rats with D-galactosamine (D-GAL)-induced hepatic failure. D-GAL was administered (1000 mg/kg) IP at 1800, just before the dark phase. The first significant decrease of ambulatory activity in rats with hepatic failure was observed between 0000 and 0300 h. A significant increase in drinking behavior was observed between 1800 and 2100 h, and a significant decrease was observed between 2100 and 0300 h. A significant decrease in food intake occurred between 1800 and 2400 h. Thereafter, there was no difference in food intake. In conclusion, we demonstrated significant changes in ambulatory activity, drinking behavior and food intake produced by D-GAL. A wide variation in systems, including monoamine turnover, and amino acid disturbance could be expected in these animals, and such changes might also have contributed to the results observed.

Amino Acids, Branched-Chain↗

PubMed1992

Induction of heme oxygenase by delta 12-prostaglandin J2 in porcine aortic endothelial cells.

delta 12-Prostaglandin (PG)J2 stimulated the synthesis of a 31,000-dalton protein (termed p31) and the induction of cellular heme oxygenase activity in porcine aortic endothelial cells. A good correlation was observed between the time courses and dose dependencies of the induction of p31 synthesis and that of heme oxygenase activity by delta 12-PGJ2. Hemin, a known inducer of heme oxygenase, also induced p31 synthesis as well as heme oxygenase activity in the cells. On two-dimensional gel electrophoresis, p31 induced by delta 12-PGJ2 exhibited an isoelectric point of 5.4, which coincided exactly with that induced by hemin. These results indicate that the p31 induced by delta 12-PGJ2 in porcine aortic endothelial cells is heme oxygenase.

Animals↗

PubMed1992

Changes in urinary retinol binding protein excretion and other indices of renal tubular damage in patients with non-insulin dependent diabetes.

Changes in urine retinol binding protein (RBP, M(r) 21,000) excretion and other indices of renal tubular damage were investigated in the patients with non-insulin dependent diabetes mellitus (NIDDM). Changes in urine RBP excretion were well paralleled with those of urine NAG excretion. In RBP-negative patients, the subjects with hypertension (systolic blood pressure > or = 140 mmHg or diastolic blood pressure > or = 90 mmHg) showed higher beta 2-microglobulin (beta 2-MG) excretion and albumin (Alb)/Cr ratios than normotensive ones. In addition, both urine beta 2-MG excretions and Alb/Cr ratios were significantly increased in RBP-positive patients. The measurement of urine RBP excretion may have an additional role in the diagnosis of renal tubular dysfunction in diabetic patients.

Acetylglucosaminidase↗

PubMed1992

Altered monoamine metabolism in the hypothalamus of the genetically obese yellow (Ay/a) mouse.

Changes in hypothalamic monoamine metabolism were investigated in the genetically obese yellow (Ay/a) mouse. At the age of 6 weeks when there was no difference in body weight between black (a/a) and yellow (Ay/a) mice, the contents of norepinephrine (NE), dopamine (DA) and their main metabolites (MHPG, DOPAC) were already significantly reduced in yellow (Ay/a) mice. Reduction of 5-hydroxytryptamine (5-HT) level and an increasing 5-HIAA/5-HT ratio has been observed. When a significant increase in body weight in the yellow (Ay/a) mouse at the age of 12 weeks was present, both NE and DA contents have been increased in the hypothalamus of the obese mouse. MHPG level was lower than in the lean mouse, resulting in an increase of MHPG/NE ratio. The present study suggests that the observed reduction in hypothalamic NE and DA metabolism might be involved in the development of overweight gain in the yellow (Ay/a) mouse.

Animals↗

PubMed1992

Molecular characterization of the murine Coh locus: an amino acid difference at position 117 confers high and low coumarin 7-hydroxylase activity in P450coh.

Coumarin 7-hydroxylase (P450coh) and steroid 15 alpha-hydroxylase (P450(15 alpha) are encoded by members within the mouse 2A subfamily. Since P450coh activity is regulated by the Coh locus, we characterized P450coh cDNAs in strains having high coumarin 7-hydroxylase activity (CohH homozygote) including 129/J and DBA/2J, and compared them with P450coh cDNAs in low activity strains (CohL homozygote) C57BL/6J, C3H/HeJ and AKR/J. The nucleotide sequences of these two cDNAs differ by a single base, which results in an amino acid difference at position 117 (Val in P450cohH and Ala in P450cohL). The CohH phenotype exhibits approximately 10-fold greater Vmax and four-fold lower Km values than those in the CohL. Male 129 AKF1/J expresses approximately equal amounts of P450cohH and P450cohL mRNAs, associated with two Coh alleles. The levels of P450coh and P450(15 alpha) mRNAs in the F1 offspring suggested that a trans-acting factor(s) appeared to regulate the expressions of the P450 genes. A recent duplication in the ancestral mouse established the line of descent to P450(15 alpha) from the ancestral P450coh gene. During evolution, amino acid substitutions have selectively occurred at positions which alter the enzyme's substrate specificity and increase in the specific activity. Consistent with an important role of natural selection in the evolution of these genes is the relatively high nonsynonomous substitution rates on the P450(15 alpha) and the P450coh branches. As a result of these evolution events, the gene family consists of members which exhibit an extremely high degree of structural similarity, but very divergent hydroxylase activities and modes of regulation.

Animals↗