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Biomedical subjects

Y Tamura

Publications and source records attributed to Y Tamura.

At least 307 records · Page 17Linked to original sources
PubMed1995

[Clinical effects of FUT-187 in reflux esophagitis after gastrectomy].

FUT-187 was orally administered to 38 patients with postgastrectomy reflux esophagitis for 4 weeks. The drug reduced the chief subjective symptoms of reflux esophagitis, such as heartburn, chest pain, precordial pain, and dysphagia for solids in 78.1% of patients. Redness, edema and erosion were also reduced in 53.3% of patients as determined endoscopically. Overall, FUT-187 exhibited an excellent therapeutic effect on the reflux esophagitis which was refractory to conventional treatments.

Administration, Oral↗
PubMed1994

Prostaglandin E2 protects cultured cortical neurons against N-methyl-D-aspartate receptor-mediated glutamate cytotoxicity.

The effects of prostaglandin (PG) E2 on glutamate-induced cytotoxicity were examined using primary cultures of rat cortical neurons. The cell viability was significantly reduced when cultures were briefly exposed to either glutamate or N-methyl-D-aspartate (NMDA) then incubated with normal medium for 1 h. Similar cytotoxicity was observed with the brief application of ionomycin, a calcium ionophore, and S-nitrosocysteine, a nitric oxide (NO)-generating agent. PGE2 at concentrations of 0.01-1 microM dose-dependently ameliorated the glutamate-induced cytotoxicity. PGE1, butaprost, an EP2 receptor agonist, and 8-bromo-cAMP were also effective in protecting cultures against glutamate cytotoxicity. By contrast, neither 17-phenyl-omega-trinor-PGE2, an EP1 receptor agonist, nor M&B 28767, an EP3 receptor agonist, affected glutamate-induced cytotoxicity. NMDA-induced cytotoxicity was ameliorated by PGE2, butaprost, MK-801, N-omega-nitro-L-arginine, a NO synthase inhibitor, and hemoglobin, which binds NO. These agents excluding MK-801 ameliorated the ionomycin-induced cytotoxicity. The cytotoxicity induced by S-nitrosocysteine was prevented only by hemoglobin but not by the other agents including PGE2. These findings indicate that PGE2 protects cultured cortical neurons against NMDA receptor-mediated glutamate neurotoxicity via EP2 receptors. EP2 receptor stimulation may suppress a step in NO formation triggered by Ca(2+)-influx through NMDA receptors.

Animals↗
PubMed1994

Dopamine-induced protection of striatal neurons against kainate receptor-mediated glutamate cytotoxicity in vitro.

The effects of dopamine on glutamate-induced cytotoxicity were examined using the primary cultures of rat striatal neurons. Cell viability was significantly reduced by exposure of cultures to glutamate or kainate for 24 h. In contrast, similar application of N-methyl-D-aspartate (NMDA) or alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) did not induce cytotoxicity. Kainate-induced cytotoxicity was significantly inhibited by kynurenate but not by MK-801. Dopamine at concentrations of 1-100 microM dose-dependently reduced kainate-induced cytotoxicity. Forskolin also significantly reduced kainate cytotoxicity. The neuroprotective effect of dopamine was antagonized by SCH 23390, a D1 receptor antagonist, but not by domperidone, a D2 receptor antagonist. Moreover, kainate-induced cytotoxicity was prevented by SKF 38393, a D1 receptor agonist, or forskolin but not by quinpirole, a D2 receptor agonist. The patch clamp study revealed that the same striatal neurons responded to both kainate and NMDA. During voltage clamp recording, neither kainate-induced currents nor NMDA-induced currents were affected by dopamine. Moreover, dopamine did not affect glutamate- or kainate-induced Ca2+ influx measured with fura-2. These findings indicate that dopamine prevents kainate receptor-mediated cytotoxicity without affecting the kainate receptor activities and intracellular Ca2+ movement. Dopamine-induced neuroprotection may be mediated by an increased intracellular cAMP formed following activation of D1 receptors.

Animals↗
PubMed1994

Nicotine-induced protection of cultured cortical neurons against N-methyl-D-aspartate receptor-mediated glutamate cytotoxicity.

The effects of nicotine on glutamate-induced cytotoxicity were examined using primary cultures of rat cortical neurons. The cell viability was significantly reduced when cultures were briefly exposed to glutamate or N-methyl-D-aspartate (NMDA) then incubated with normal medium for 1 h. A 1-h exposure of the cultures to kainate or alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) reduced cell viability. Incubating cultures with nicotine for 1-24 h protected cortical neurons against glutamate cytotoxicity. Maximum protection against glutamate cytotoxicity was induced with a 2-h nicotine incubation. Exposure to nicotine for up to 2 h did not affect cell viability by itself although cell viability was reduced in a time-dependent manner when the exposure exceeded 4 h. Neuroprotection by nicotine was dependent on both the concentration and incubation period. Nicotine reduced the NMDA cytotoxicity but did not attenuate that of kainate and AMPA. The neuroprotective effects of nicotine against glutamate cytotoxicity were antagonized by mecamylamine and hexamethonium but not by atropine. These results indicate that nicotinic receptor stimulation induces neuroprotection against glutamate cytotoxicity mediated by NMDA receptors.

Animals↗
PubMed1994

Separation and characterization of diastereoisomers of antisense oligodeoxyribonucleoside phosphorothioates.

Diastereoisomers of oligodeoxyribonucleoside phosphorothioates (OPT) up to a tetramer were effectively separated with reversed-phase high-performance liquid chromatography (reversed-phase HPLC) under optimized conditions. The diastereoisomers of OPT resulted in different retention times on the reversed-phase HPLC. From the results, we found that there were certain rules in the elution order of the diastereoisomers. The configurational sequence of the diastereoisomers was determined by digestion with nuclease P1, snake venom phosphodiesterase, and alkaline phosphatase. The diastereoisomers were studied by CD spectroscopy with respect to their conformation in aqueous media. We found that a large variation in the conformation of diastereoisomers exists. Results suggest that much attention should be paid to the diastereoisomerism in antisense molecules having chiral internucleotide linkages such as OPT.

Base Sequence↗
PubMed1994

Physicochemical and antibacterial properties of lactoferrin and its hydrolysate produced by heat treatment at acidic pH.

In order to apply functionally active lactoferrin (Lf) to food products, the effect of pH on the heat stability of Lf was studied. Lf was easily denatured to an insoluble state by heat treatment under neutral or alkaline conditions, above pH 6. In contrast, it remained soluble after heat treatment under acidic conditions at pH 2 to 5, and the HPLC pattern of Lf heat-treated at pH 4 at 100 degrees C for 5 min was the same as that of native Lf. Lf was found to be very thermostable at pH 4, and could be pasteurized or sterilized without any significant loss of its physicochemical properties. Lf was hydrolyzed by heat treatment at pH 2 to 3 at above 100 degrees C, and its iron binding capacity and antigenicity were lost. But the antibacterial activity of the hydrolysate was found to be much stronger than that of native Lf. The antibacterial component of Lf hydrolysate produced by heat treatment at acidic pH was verified to be a peptide including the sequence of residues 1-54 from the N-terminal end of the bovine Lf molecule.

Amino Acid Sequence↗
PubMed1994

Regulating factors of liver regeneration after hepatectomy.

The factors regulating liver regeneration were studied by measuring changes in the liver volume and serum hepatocyte growth factor (HGF) levels after hepatectomy. Changes in the liver volumes were studied in 68 hepatectomized patients, including (A) hepatoma patients who had chronic hepatitis or liver cirrhosis (n = 44) and (B) metastatic liver cancer patients who had normal liver parenchyma (n = 24). The hepatic volume increased by 13.8% of the remnant hepatic volume in group A and by 49.1% in group B. The examined factors included the percentage of resected liver volume (%RLV) and the results of laboratory tests. Regression analysis showed that in group A, both %RLV (beta = 0.46) and the serum total bilirubin (T-Bil) level (beta = -0.33) correlated significantly with the extent of liver regeneration and that in group B, only %RLV (beta = 0.78) correlated significantly with the regeneration. Serum HGF levels after hepatectomy were studied in 21 hepatectomized patients, including 11 hepatoma patients and 10 patients with some types of metastatic liver cancer. Serum HGF levels increased significantly after surgery in all 21 patients. Regression analysis, however, showed that the change in HGF was related to liver cirrhosis (beta = 0.46) and to the maximal postoperative T-Bil level (beta = 0.51) but not to the extent of liver regeneration after hepatectomy. These results suggest that liver regeneration is regulated primarily by factors relating to the percentage of the resected liver parenchyma and that serum HGF levels do not directly relate to liver regeneration after surgery.

Aged↗
PubMed1994

Morphologic and metabolic study of the effect of oxygenated perfluorochemical perfusion on amputated rabbit limbs.

The purpose of this investigation was to examine the effect of oxygenated perfluorochemical perfusion on ischemia injury to skeletal muscle in rabbits. Forty-two hindlimbs of white rabbits were divided into six groups: 3-hr perfusion; 6-hr perfusion; 3-hr hypothermia; 6-hr hypothermia; sham operation without perfusion or hypothermia preservation; and biopsy. Endothelial cells in these muscles were evaluated using electron microphotography. The areas of both the inner and outer sides of cross-sectioned endothelial cells without cell nuclei were measured, and a new "capillary index" was calculated: (outer area--inner area)/outer area. The values of the capillary index in the perfusion groups were similar to those in the biopsy group. However, the values in the hypothermia groups were significantly greater than those in the biopsy group. These measurements suggested that the perfluorochemical perfusion method preserved the capillary endothelial cells in a nearly normal condition. The adenine nucleotides of these muscles were also evaluated. ATP levels in the 6-hr hypothermia group showed a substantial decrease to 57 percent of those in the sham-operated group. The 6-hr perfusion group levels, however, decreased only to 80 percent of those in the sham-operated group. Although application of the oxygenated perfluorochemical perfusion method did not maintain normal ATP levels, the maintenance of ATP levels was clearly higher than levels maintained in the hypothermia-preservation group. These findings suggest that oxygenated perfluorochemical perfusion is a satisfactory method for preserving amputated limbs.

Adenine Nucleotides↗
PubMed1994

Pressure gradients between intraluminal and extraluminal spaces may affect the potassium induced contraction in the rabbit's basilar arteries.

In order to investigate the different contactile effects between intraluminal and extraluminal vasoactive agents, we studied the contractile responses of rabbit basilar artery to selective intraluminal and extraluminal administration of potassium, serotonin and histamine in vitro. We also studied how the physical pressure gradients, such as hydrostatic or osmotic pressure gradients between intraluminal and extraluminal spaces, affect potassium-induced contraction. Intraluminal potassium (30 mM) induced a significantly greater contraction than extraluminal potassium. Serotonin (2 x 10(-7) M) and histamine (10(-5) M) applied intraluminally caused the same magnitude of the contraction as those applied extraluminally and no significant differences were noted between these applications. These differences in potassium-induced contraction were more significant when the intraluminal hydrostatic pressure was elevated by 20 mmHg. Contraction by either intraluminal or extraluminal potassium was significantly decreased when intraluminal pressure was raised by 40 mmHg. As the osmotic pressure gradients between the extraluminal and the intraluminal spaces were increased, these differences in potassium-induced contraction were decreased. Our findings suggest that physical pressure gradients may affect potassium-induced contraction in a different manner from pharmacologically-induced contraction and that free ions can penetrate the vascular wall by physical pressure gradients between the intraluminal and extraluminal spaces of cerebral artery.

Animals↗
PubMed1994

Monoclonal antibody specifically reacting against 73-kilodalton heat shock cognate protein: possible expression on mammalian cell surface.

The heat shock proteins (hsp) are regarded as being immunogenic to the animal hosts. Although certain hsp are suggested to be expressed on the cell surface, further evidence for the cell surface expression of these proteins has been required. In this article we report the development of a MAb NT22. This antibody reacted with ATP-binding proteins (which contain a large amount of 70-kDa hsp family) of HeLa cells, and with purified bovine 70-kDa hsp. It did not react with the E. coli lysate, but clearly reacted with the recombinant rat hsc73. However, NT22 failed to react with hsp72. Furthermore, stress treatment of cells also indicated that considerable amounts of NT22-defined antigen translocated into the nucleus from the cell cytoplasm. These results suggest that NT22 is a novel MAb that reacts specifically to the mammalian hsc73. Moreover, this antibody could detect the constitutive and stress-induced cell surface expression of its relevant antigen. It is expressed preferentially on EBV-transformed B cell and certain epithelial cancer cell lines. However, resting B cells did not express this antigen on the cell surface. These data indicate that hsc73 could be expressed on the cell surface of certain cells, and suggest that hsc73 may interact with the host immune system.

Adenosine Triphosphate↗
PubMed1994

Cytochrome b5-like hemoprotein/cytochrome b5 reductase complex in rat liver mitochondria has NADH-linked aquacobalamin reductase activity.

Rat liver mitochondrial NADH-linked aquacobalamin reductase was characterized to clarify its enzymological properties. Most of the enzyme was solubilized with 10 g/L Triton X-100 from rat liver mitochondrial membranes. The elution behavior of the solubilized enzyme was identical to that of NADH-cytochrome c reductase (b-type cytochromes/cytochrome b5 reductase complex) during DEAE-Sepharose Fast Flow column chromatography. By mixing both purified cytochrome b5-like hemoprotein (outer membrane-cytochrome b) and cytochrome b5 reductase, cob(II)alamin was formed from aquacobalamin and NADH. These results provide evidence that the outer membrane-cytochrome b/cytochrome b5 reductase complex has the activity of the NADH-linked aquacobalamin reductase in rat liver mitochondria. Some properties of the NADH-linked aquacobalamin reductase were studied using the function of rat liver mitochondrial membranes. The specific activity (109.5 +/- 14.3 nmol.min-1.mg protein-1) of the enzyme was shown under physiological conditions (pH 7.1 at 40 degrees C). The optimal pH and temperature for activity were 7.1 and 40 degrees C, respectively. The apparent Km values were 41.9 mumol/L for aquacobalamin in the presence of 0.2 mmol/L NADH and 14.4 mumol/L for NADH in the presence of 0.1 mmol/L aquacobalamin. The enzyme was specific for aquacobalamin, because cyanocobalamin could not be reduced by the enzyme.

Animals↗
PubMed1994

Virulence region of plasmid pNL2001 of Salmonella enteritidis.

The virulence region of the Salmonella enteritidis 55 kb plasmid pNL2001 was identified by Tn1-insertion mutagenesis, DNA hybridization studies, and Western blot analysis of proteins encoded in the virulence region of the plasmid. DNA hybridization studies showed that the pNL2001 plasmid contained a 6.4 kb SalI-EcoRI fragment homologous to the 6.4 kb SalI-EcoRI Salmonella plasmid virulence (spv) region of the S. choleraesuis 50 kb plasmid (pKDSC50). One of the 247 Tn1-insertion mutants of S. enteritidis, designated strain TA19, showed a reduced mouse lethality, and the Tn1-insertion of strain TA19 was located within this homologous 6.4 kb region, suggesting that the 6.4 kb SalI-EcoRI fragment of pNL2001 contained the spv region. Two contiguous SalI-EcoRI fragment were cloned into the expression vectors. By the 6.4 kb SalI-EcoRI fragment were cloned into the expression vectors. By Western blot analysis using four Spv peptide antisera, each specific for individual proteins encoded in the spvR, spvA, spvB and spvC genes of pKDSC50, four proteins encoded in the 6.4 kb SalI-EcoRI fragment of pNL2001 were identified. Protein SpvR with an apparent molecular mass of 32 kDa was produced from the 2.3 kb SalI-EcoRI fragment, and protein SpvA, SpvB and SpvC with apparent molecular masses of 32, 70 and 29 kDa, respectively, were produced from the 4.1 kb EcoRI-EcoRI fragment. From the 4.1 kb EcoRI::Tn1 fragment of the TA19 plasmid, proteins SpvA and SpvB were expressed, but not SpvC. It was therefore suggested that the spvC gene may contribute to the expression of virulence of S. enteritidis. Furthermore, the nucleotide sequence of the 6.4 kb SalI-EcoRI fragment encoding these four proteins was determined. Four open reading frames which encoded the four proteins with deduced molecular masses of 33,906, 28,200, 65,349 and 27,646 Da were detected. Deduced amino acid sequences of each protein showed a high degree of identity to corresponding sequences in the virulence region of S. choleraesuis, S. dublin and S. typhimurium virulence plasmids. Therefore, we confirmed that the virulence plasmids of Salmonellae including S. enteritidis share the highly conserved region responsible for virulence.

Amino Acid Sequence↗
PubMed1994

Antigenic mimicry of Clostridium chauvoei flagella by polyclonal anti-idiotypic antibodies.

Polyclonal rabbit anti-idiotypic (anti-Id) antibodies against two monoclonal antibodies (MAbs) specific for the flagella of Clostridium chauvoei were produced, purified and characterised. Lack of cross-reactivity with heterologous MAbs indicated that the anti-Id antibodies were highly specific. The surface-exposed epitopes of the flagellar filament recognised with protective MAb were further distinguished by the anti-Id antibodies. Moreover, each anti-Id antibody inhibited the binding of its related MAb to flagellar antigens in a competitive enzyme-linked immunosorbent assay, suggesting that the anti-Id antibodies bore an internal image of the flagellar antigens. The survival rate of mice was increased to nearly twice that of controls by immunisation with anti-Id 41, which had been produced with a protective MAb; in contrast, anti-Id 114, produced with a non-protective MAb, failed to immunise. The results suggest that an anti-Id antibody containing an internal image of C. chauvoei flagella might be used as a vaccine.

Animals↗