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M Tada

Publications and source records attributed to M Tada.

At least 271 records · Page 15Linked to original sources
PubMed1994

gamma-Glutamylcysteine ethyl ester for myocardial protection in dogs during ischemia and reperfusion.

OBJECTIVES: The aim of this study was to examine the infarct-limiting effects of gamma-glutamylcysteine ethyl ester, a newly discovered synthetic precursor of glutathione biosynthesis, in a canine model of myocardial infarction. BACKGROUND: Reduced glutathione plays an important role in protecting cells against damage induced by reactive oxygen species during myocardial ischemia and reperfusion. Gamma-glutamylcysteine ethyl ester is capable of penetrating into cells in its intact form and increasing intracellular glutathione levels. METHODS: Dogs were subjected to a 90-min coronary occlusion followed by 5 h of reperfusion. An intravenous bolus injection of gamma-glutamylcysteine ethyl ester (3 or 10 mg/kg body weight) was administered immediately before reperfusion. Regional myocardial blood flow was measured with the use of colored microspheres. RESULTS: Gamma-glutamylcysteine ethyl ester effectively reduced infarct size in a dose-dependent manner (mean +/- SEM 26.4 +/- 3.5% in the low dose group [3 mg/kg, n = 10] and 19.0 +/- 3.4% in the high dose group [10 mg/kg, n = 10]; each p < 0.05 vs. the value in the control group [40.6 +/- 4.8%, n = 10]). There were no differences between the control and treated groups in hemodynamic variables or regional myocardial blood flow either during the ischemic period or after reperfusion. The reduced glutathione content of ischemic myocardium in the control group (0.62 +/- 0.11 mumol/g, p < 0.01) was significantly lower than that in nonischemic myocardium (1.46 +/- 0.07 mumol/g), and it was preserved by treatment in a dose-dependent manner (3 mg/kg, 0.83 +/- 0.06 mumol/g; 10 mg/kg, 0.92 +/- 0.14 mumol/g; each p < 0.05 vs. control level). There were no differences in oxidized glutathione content between nonischemic and ischemic myocardium or among the three groups. CONCLUSIONS: Gamma-glutamylcysteine ethyl ester, a precursor of glutathione, significantly attenuates myocardial ischemia and reperfusion injury when administered immediately before reperfusion.

Animals↗
PubMed1994

Modulation of KC/gro protein (interleukin-8 related protein in rodents) release from hepatocytes by biologically active mediators.

Modulation of the release of KC/gro protein (a chemoattractant for neutrophils; IL-8 related protein in rodents) from isolated hepatocytes after stimulation with biologically active mediators was investigated. The release of KC/gro protein from hepatocytes of control rats was enhanced by stimulation with lipopolysaccharide, IL-1 beta or TNF-alpha in a dose-dependent manner, but was not enhanced by IL-6. In contrast, although spontaneous release of KC/gro protein from the hepatocytes of chronically ethanol-fed rats was markedly enhanced as compared with control rats, the relative increase by stimulation with lipopolysaccharide, IL-1 beta or TNF-alpha was significantly smaller than in controls. These findings suggest that the regulation of hepatocyte KC/gro protein production might be disturbed in chronically ethanol-fed rats.

Alcoholism↗
PubMed1994

Amino acids Lys-Asp-Asp-Lys-Pro-Val402 in the Ca(2+)-ATPase of cardiac sarcoplasmic reticulum are critical for functional association with phospholamban.

Phospholamban interacts with SERCA2 (sarco/endoplasmic reticulum calcium ATPase isoform 2) but not SERCA3. The use of chimeric SERCA2/SERCA3 molecules has revealed that amino acids 336-412 in the phosphorylation domain of SERCA2 are essential for functional association with phospholamban (Toyofuku, T., Kurzydlowski, K., Tada, M., and MacLennan, D. H. (1993) J. Biol. Chem. 268, 2809-2815). When mutations were made in SERCA2 between amino acids 336 and 412 and the mutants were coexpressed with phospholamban, only mutation of amino acids Lys397 to Val402 affected phospholamban association with the Ca(2+)-ATPase. A chimeric Ca(2+)-ATPase, CH2, was created in which the phosphorylation domain of SERCA2 was replaced with that of SERCA3, disrupting functional interaction with phospholamban. The SERCA3 sequence QGEQLV402 was then mutated to the corresponding SERCA2 sequence, KDD-KPV402, and to the sequence KGEKPV402, resulting in restoration of functional interaction with phospholamban. Mutation to KGNKPV402 or to QGEQPV402 did not restore functional interaction with phospholamban. These results demonstrate that amino acids Lys397-Val402 comprise the interaction site with phospholamban in SERCA2, and probably also in SERCA1, and that the appropriate balance of charged and hydrophobic residues is an important feature of the interaction.

Amino Acid Sequence↗
PubMed1994

Human astrocytomas and glioblastomas express monocyte chemoattractant protein-1 (MCP-1) in vivo and in vitro.

Expression of the monocyte chemoattractant protein-1 (MCP-1) was examined in human central nervous system tumours (glioblastomas and astrocytomas) and normal human brain. Northern blot analysis demonstrated constitutive expression of MCP-1 mRNA in 6 of 12 glioblastoma cell lines. Expression could be stimulated by interleukin (IL)-1 beta and tumour necrosis factor (TNF)-alpha in all cell lines tested. Immunoprecipitation demonstrated secretion of both isoforms, MCP-1 alpha and -beta, of the MCP-1 protein. Reverse-transcription polymerase chain reaction and Northern blot analysis on tissues demonstrated MCP-1 mRNA expression in 17 of 17 glioblastomas, 3 of 6 anaplastic astrocytomas and 6 of 6 low-grade astrocytomas, as well as in fetal brain but not in normal adult brain. In situ hybridization on 2 glioblastomas and 1 low-grade astrocytoma indicates that neoplastic astrocytes and endothelial cells express MCP-1 mRNA in vivo. Moreover, tumour cyst fluids of glioblastomas and astrocytomas were able to induce monocyte chemoattraction in an in vitro assay. This chemotactic activity was specifically neutralized by anti-MCP-1 antibodies in 9 of 10 samples, further demonstrating the production of bioactive MCP-1 in vivo and supporting an important role for this factor in the infiltration of monocytes/macrophages into tumour tissue.

Astrocytoma↗
PubMed1994

DNA adduct formation of hepatocarcinogenic aromatic amines in rat liver: effect of cytochrome P450 inducers.

F344 rats were treated with an i.p. injection of 2-amino-6- methyldipyrido[1,2-a:3',2'-d]imidazole (Glu P-1) or 3-methoxy-4-aminoazobenzene (3-MeO-AAB) and examined for the formation of the DNA adduct in the liver. To examine the effect of pretreatment with a cytochrome P450 (CYP) inducer on the formation of DNA adduct, these rats were pretreated with 3-methylcholanthrene (MC; CYP1A1/1A2 inducer) or phenobarbital (PB; CYP2B inducer). Administration of Glu P-1 and 3-MeO-AAB gave 2 and 5 adducts, respectively, as determined by 32P-postlabeling assay. By Glu P-1 administration, pretreatment of rats with MC, but not with PB, increased the total amount of DNA adducts including 3 new adducts as minor products. In contrast, pretreatment of rats with PB increased the total amount of DNA adducts derived by 3-MeO-AAB. The increase of aromatic amine DNA adducts by pretreatment with a CYP inducer was proportional to the activity of induced CYP isozyme(s) responsible for the mutagenic activation of each aromatic amine.

Animals↗
PubMed1994

The point mutation Arg615-->Cys in the Ca2+ release channel of skeletal sarcoplasmic reticulum is responsible for hypersensitivity to caffeine and halothane in malignant hyperthermia.

Malignant hyperthermia (MH) is an autosomal dominant myopathy. Molecular genetic studies have shown that the alteration of Arg615 to Cys in the Ca2+ release channel of skeletal muscle sarcoplasmic reticulum (ryanodine receptor) is cosegregated with porcine MH (Fujii, J., Otsu, K., Zorzato, F., de Leon, S., Khanna, V. K., Weiler, J. E., O'Brien, P. J., and MacLennan, D. H. (1991) Science 253, 448-451; Otsu, K., Khanna, V. K., Archibald, A., and MacLennan, D. H. (1991) Genomics 11, 744-750). Here, using the fluorescence calcium indicator indo-1, we determined the concentration of ionized cytosolic calcium in myoblastic cells transfected with either the wild-type or mutated ryanodine receptor cDNA. The cells expressing the mutant ryanodine receptor showed higher sensitivity to caffeine, which induces Ca2+ release from the sarcoplasmic reticulum through the ryanodine receptor. Exposure to clinical doses of halothane resulted in a rapid increase of [Ca2+]i in cells expressing the mutated ryanodine receptor, whereas no [Ca2+] changes were observed in cells expressing the wild-type ryanodine receptor. These results provide definite evidence that a single amino acid mutation, Arg615-->Cys, in the ryanodine receptor is causative of MH.

Amino Acid Sequence↗
PubMed1994

A mouse TGF-beta type I receptor that requires type II receptor for ligand binding.

A cDNA for a serine/threonine kinase receptor was isolated from a mouse brain cDNA library. The receptor transiently expressed on COS cells bound TGF-beta 1 not by itself but only when TGF-beta type II receptor was coexpressed. The molecular mass of the ligand-receptor complex was estimated to be 75 kDa. The type II receptor-dependent binding and the molecular mass of the complex suggest that the receptor is a TGF-beta type I receptor.

Amino Acid Sequence↗
PubMed1994

Analysis of the p53 gene and its expression in human glioblastoma cells.

Chromosome 17p has been shown to be an early and frequent target for loss of heterozygosity through mitotic recombination in astrocytomas. These losses are frequently accompanied by point mutations in the p53 gene of the remaining allele, resulting in loss of wild type p53 function. However, a fraction of astrocytomas retain constitutional heterozygosity and do not have p53 mutations; some of these lose wild type p53 activity through binding to the protein product of amplified mdm2 genes. To test whether loss of wild type p53 biological function is a necessary step in astrocytoma progression we analyzed p53 expression and biological function in 13 glioma cell lines. All the cell lines expressed a 2.8-kilobase p53 transcript and showed various amounts of p53 protein by immunoprecipitation, except for cell line LN-Z308 which had only a small truncated p53 mRNA and no protein expression. To test whether the p53 expressed in these cell lines was functionally wild type or mutant we transfected them with a plasmid construct harboring a chloramphenicol acetyltransferase (CAT) reporter gene under the control of transcriptional elements that are induced by wild type but not mutant p53. Four lines were shown to retain wild type p53 function. Sequencing of the p53 gene in two of these cell lines confirmed the wild type genotype. These results show that inactivation of the p53 gene is not an obligatory step in glioblastoma genesis. This suggests either that two pathways (p53 inactivation dependent or independent) may lead to a tumor group classified histologically as glioblastoma or that in some cases p53 mutations are bypassed due to the presence of mutations in downstream effector genes.

Animals↗
PubMed1994

Amino acids Glu2 to Ile18 in the cytoplasmic domain of phospholamban are essential for functional association with the Ca(2+)-ATPase of sarcoplasmic reticulum.

Phospholamban inhibits the Ca(2+)-ATPase of cardiac sarcoplasmic reticulum by lowering its affinity for Ca2+. In earlier studies (Toyofuku, T., Kazimierz, K., Tada, M., and MacLennan, D. H. (1993) J. Biol. Chem. 268, 2809-2815), parts of the phosphorylation and nucleotide binding/hinge domains of the Ca(2+)-ATPase were shown to be essential for phospholamban interaction. In order to identify the sites in phospholamban which interact with the Ca(2+)-ATPase, a series of mutants containing amino acid replacements in the cytoplasmic and transmembrane regions of phospholamban were co-expressed with the cardiac/slow-twitch muscle Ca(2+)-ATPase isozyme, SERCA2a, in HEK-293 cells. Mutation of residues in the cytoplasmic 1A domain of phospholamban, including positively charged residues, Lys3, Arg9, Arg13, and Arg14, negatively charged residue, Glu2, hydrophobic residues, Val4, Leu7, Ala11, Ile12, Ala15, and Ile18, and phosphorylation site residues, Ser16 and Thr17, resulted in loss of the inhibitory effect of phospholamban on Ca2+ transport by the Ca(2+)-ATPase. By contrast, mutation of Met1, Gln5, Tyr6, Thr8, Ser10, Glu19, or Met20 or of residues in the cytoplasmic 1B domain (Pro21 to Asn30) and of Cys41 in the transmembrane domain (Leu31 to Leu52) did not diminish the inhibitory effects of phospholamban on Ca2+ transport. These results suggest that a region essential for functional association of phospholamban with the Ca(2+)-ATPase lies in the cytoplasmic 1A domain of phospholamban.

Amino Acid Sequence↗
PubMed1994

Role of polymorphonuclear leukocytes in galactosamine hepatitis: mechanism of adherence to hepatic endothelial cells.

To investigate the role of polymorphonuclear leukocytes in galactosamine-induced hepatic injury, we injected rats intraperitoneally with antiserum against rat polymorphonuclear leukocytes to deplete circulating neutrophils, then administered galactosamine plus lipopolysaccharide. Polymorphonuclear leukocytes in the hepatic sinusoids were increased after administration of galactosamine plus lipopolysaccharide, whereas pretreatment with the antiserum decreased the number of circulating leukocytes and reduced the mortality and the severity of hepatic injury. Serum collected 1 hr after galactosamine/lipopolysaccharide treatment enhanced in vitro polymorphonuclear leukocyte adherence to hepatic endothelial cells and induced leukocyte superoxide production. Intercellular adhesion molecule-1 expression on hepatic endothelial cells was also enhanced after stimulation with the serum. Polymorphonuclear leukocyte adhesion was partially inhibited by an antibody against tumor necrosis factor-alpha but not by superoxide dismutase. These results suggest that polymorphonuclear leukocytes play an important role in galactosamine-induced hepatic injury and that the accumulation and activation of leukocytes, as well as the enhanced expression of adhesion molecules on hepatic endothelial cells, can be induced by biologically active mediators such as tumor necrosis factor-alpha. In addition, prostaglandins E1 and E2 lessened the enhanced adherence of polymorphonuclear leukocytes and thus contributed to protection against hepatic injury.

Alprostadil↗
PubMed1994

Thyroid hormone enhances Ca2+ pumping activity of the cardiac sarcoplasmic reticulum by increasing Ca2+ ATPase and decreasing phospholamban expression.

Phospholamban is a putative suppressor of the Ca2+ ATPase of the cardiac sarcoplasmic reticulum. The level of mRNA encoding the Ca2+ ATPase has been shown to be increased, whereas the phospholamban mRNA level to be decreased in the ventricles obtained from hyperthyroid rabbits [Nagai R, Zarain-Herzberg A. Brandl CJ, Fujii J. Tada M. MacLennan DH, Alpert NR, Periasamy M. (1989) Proc Natl Acad Sci USA 86: 2966-2970]. The present study was designed to examine whether these effects of thyroid hormone on the expression of the Ca2+ ATPase and phospholamban are exerted directly on cardiac myocytes and whether the resultant incoordinate expression of these proteins alters Ca2+ pumping activity. We studied the levels of phospholamban and Ca2+ ATPase mRNA in primary isolated neonatal rat myocardial cells incubated with triiodothyronine (T3) for 3-48 h and the Ca2+ uptake activity of the microsomes prepared from the cells. Northern blot analysis showed that T3 decreased phospholamban mRNA levels to about a half of control in 24 h. On the other hand, Ca2+ ATPase mRNA gradually increased with time. EC50 for phospholamban mRNA expression was 2.5 x 10(-10) M which was approximately 10 times higher than that for the Ca2+ ATPase. T3 increased Vmax of Ca2+ uptake with the significant reduction of K0.5 for Ca2+ (0.40 +/- 0.02 microM for control v 0.31 +/- 0.02 microM for T3-treated vesicles), indicating that thyroid hormone stimulates Ca2+ pumping activity not only by increasing the Ca2+ ATPase but also decreasing phospholamban. These results suggested that phospholamban regulates the Ca2+ ATPase in dual modes; in short time range, by decreasing the affinity of the Ca2+ ATPase for Ca2+ by phosphorylation of phospholamban with cAMP-dependent protein kinase, and in long time range, by changing the molecular ratio between the two proteins through the regulation of gene expression.

Animals↗
PubMed1994

Effect of cadmium (CdCl2) on cell proliferation and production of EDRF (endothelium-derived relaxing factor) by cultured human umbilical arterial endothelial cells.

The effect of cadmium chloride (CdCl2) on cell proliferation and EDRF (endothelium-derived relaxing factor) production by cultured human umbilical arterial endothelial cells (HUAECs) was investigated. The viability of HUAECs decreased dose-dependently after the addition of Cd (cadmium chloride). Morphologic examination by phase contrast microscopy revealed severe damaging effects of Cd at higher concentrations. The cytotoxic effect of Cd on DNA synthesis was also concentration-dependent. The effect of Cd on EDRF production by indomethacin-treated HUAECs was assessed by its anti-platelet aggregatory effect. Platelet aggregation studies were carried out in cuvettes lined with HUAECs using an aggregometer. The anti-platelet aggregatory effect was decreased dose-dependently by pretreatment with Cd. These findings suggest that HUAECs are susceptible to concentration-dependent Cd cytotoxicity, and that Cd can inhibit the production of EDRF by HUAECs.

Cadmium↗
PubMed1994

Production of interleukin-1 receptor antagonist by human glioblastoma cells in vitro and in vivo.

We investigated the expression and production of the interleukin-1 receptor antagonist (IL-1ra) in three human glioblastoma cell lines (LN443, LN444, LN859). Reverse transcription-polymerase chain reaction (RT-PCR) demonstrated the expression of IL-1ra mRNA transcripts in the three cell lines. These three cell lines also expressed mRNA for IL-1 alpha, IL-1 beta, as well as IL-1 receptor type I and type II, suggesting the presence of an IL-1 autocrine loop in these cell lines. Northern blot analysis demonstrated that the IL-1ra mRNA expression increased with IL-1 beta or tumor necrosis factor (TNF)-alpha but not with GM-CSF stimulation in both LN443 and LN444 cell lines. PMA stimulation increased the mRNA expression in LN444 but not in LN443 cells. Immunocytochemical staining showed IL-1ra immunoreactivity in these three cell lines. ELISA on culture supernatants demonstrated that the IL-1ra was secreted from the cell lines in agreement with the mRNA expression. RT-PCR with isoform-specific primers showed that both intracellular and secreted forms of IL-1ra were expressed by the three cell lines, with a predominance of the intracellular form. In vivo study with RT-PCR and Northern blot analysis demonstrated IL-1ra mRNA in six out of 12 human glioblastoma and two out of five anaplastic astrocytoma tissues, although the expression level was not high in some cases. Immunohistochemistry demonstrated the presence of IL-1ra within the cytoplasm of tumor cells in six out of 10 glioblastomas in vivo. These results suggest a potential role of IL-1ra in regulation of the IL-1 autocrine loop in glioblastomas.

Base Sequence↗
PubMed1994

Polymorphonuclear leukocytes-induced injury in hypoxic cardiac myocytes.

Growing evidence suggests that free radicals derived from polymorphonuclear leukocytes (PMNs) play an important role in myocardial ischemia-reperfusion injury. To elucidate the cellular mechanism by which activated PMNs exacerbate ischemic myocardial damage, we investigated the extent of cell injury, assessed by the morphological deterioration, free radical generation, and lipid peroxidation in mouse embryo myocardial cells coincubated with activated PMNs. The generation of PMN-derived free radicals was related to the extent of myocardial cell injury. When myocardial cell sheets were subjected to hypoxia and glucose-free media, myocardial cells were injured (cristalysis in the mitochondria and disruption of the sarcolemma) after adding various PMN activators, and the injury extended to the adjacent cells. Chemiluminescent emission and production of thiobarbituric acid-reactive substances in the coincubated cells increased markedly compared with myocardial cells or PMNs alone. The augmented lipid peroxidation coincided with the progression of myocardial cell injury. Catalase inhibited the myocardial cell injury by 52%, the chemiluminescence by 46%, and lipid peroxidation by 50%, whereas superoxide dismutase exhibited less pronounced inhibition. These results indicate that a chain reaction of lipid peroxidation in myocardial cells induced by PMN-derived free radicals closely correlates with membrane damage and contributes to the propagation of irreversible myocardial cell damage.

Animals↗
PubMed1994

Diagnostic ERCP.

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Biliary Tract Diseases↗
PubMed1994

Esophageal hemangioma: endoscopic diagnosis and treatment.

We report on a 72-year-old man complaining of spontaneous retrosternal chest pain in whom an esophagogram showed a filling defect in the upper esophagus. On endoscopy, a polypoid lesion with a bluish-white surface was seen, the biopsy indicating the presence of a hemangioma. Endoscopic ultrasonography demonstrated the superficial origin of the lesion and the presence of vascular structures. Endoscopic resection was performed using a combination of hemostatic clipping and snare polypectomy, with excellent results. Follow-up for ten months did not reveal any recurrence.

Aged↗