PubMed Health⌕ Search

Biomedical subjects

K Muramoto

Publications and source records attributed to K Muramoto.

At least 19 recordsLinked to original sources
PubMed1992

Functional and morphological changes in cultured neurons of rat cerebral cortex induced by long-term application of aluminum.

Aluminum is an environmental neurotoxin and a suspected risk factor for Alzheimer's disease. The neurotoxicity of aluminum on cultured neurons of rat cerebral cortex was investigated using an assay system for synapse formation and immunohistochemistry. The frequency of spontaneous oscillations of intracellular Ca2+, which is correlated to the number of synapses, was decreased after exposure to 100 microM of aluminum chloride for 22 days. Long-term application of aluminum (48 days) caused aggregation of cell bodies and fasciculation of processes. Processes and cell bodies were strongly stained by antibody to tau protein, which is one of the main components of Alzheimer's neurofibrillary tangles. It is suggested that the characteristics of the degeneration of cultured neurons induced by aluminum show some similarities to the pathology observed in brains with Alzheimer's disease.

Aluminum↗
PubMed1992

The amino-acid sequence of a lectin from conger eel, Conger myriaster, skin mucus.

The amino-acid sequence of a beta-galactoside-binding lectin isolated from the skin mucus of the conger eel Conger myriaster was determined. The lectin (30 kDa) was composed of two identical subunits of 135 amino acid residues with N-acetylserine at the N-terminus and no half-cystinyl residue. It was a 30-34% sequence identical to vertebrate beta-galactoside-binding lectin and proved to be a member of the S-type lectin family.

Amino Acid Sequence↗
PubMed1992

Block of synapse formation between cerebral cortical neurons by a protein kinase inhibitor.

Synchronized Ca2+ transients in cultured hippocampal neurons reflect the pattern of underlying electrical activity. Here we demonstrate a similar synchronization of cerebral cortical neurons in culture, and show that this functional coupling is correlated to the appearance of morphologically identified synapses using electron microscopy. During screening of a series of drugs for inhibition of in vitro synaptogenesis, the continuous presence of a protein kinase inhibitor (K-252b) in the culture medium was found to block the synchronous firing and to decrease significantly the number of morphologically identifiable synapses. Since K-252b does not permeate the cell membrane, the results strongly suggest that phosphorylation of cell surface protein(s) by a K-252b sensitive-protein kinase is an essential process in synapse formation.

Animals↗
PubMed1991

Isolation and characterization of somatolactin, a new protein related to growth hormone and prolactin from Atlantic cod (Gadus morhua) pituitary glands.

The characterization of cod somatolactin (SL), a new pituitary protein belonging to the growth hormone/prolactin family, is described. Cod SL has a molecular weight of 26 kDa and consists of 209 amino acids, of which eight are Cys. The protein has three disulfide bonds between residues Cys5-Cys15, Cys65-Cys181, and Cys198-Cys206. The Cys residues at positions 42 and 180 are not involved in disulfide bonding. The positions of these disulfide bonds are homologous to those found in prolactin and growth hormone. Cod SL has two possible N-glycosylation sites, but only one appears to have carbohydrate units attached. Chemical analysis showed the following sugars to be present: galactose, mannose, N-acetylneuramic acid, and glucosamine. A smaller variant (23 kDa) of SL has been isolated, which is believed to be deglycosylated. Sequence comparison revealed cod SL to be similarly related to both GH and PRL, but slightly higher identity was observed to the tetrapod hormones (27-33%) than to the teleost hormones (21-27%).

Amino Acid Sequence↗
PubMed1991

Inhibitory effects of a novel PAF antagonist E6123 on anaphylactic responses in passively and actively sensitized guinea pigs and passively sensitized mice.

The effects of the platelet-activating factor (PAF) antagonist, E6123, on anaphylactic responses in guinea pigs and mice were investigated. E6123 inhibited i.v. antigen (Ag)- or inhaled Ag-induced bronchoconstriction in passively and actively sensitized guinea pigs after oral administration at 3 and 10 micrograms/kg, respectively. E6123 inhibited Ag inhalation-induced airway hyperreactivity in guinea pigs after oral administration at 30 micrograms/kg. E6123 protected mice from anaphylactic death with an ED50 value (p.o.) of 7 micrograms/kg. The inhibitory effects of E6123 described above were very potent compared to those of the PAF-antagonists WEB2347 and Y-24180. The present results suggest that E6123 may be beneficial for the treatment of asthma, a condition in which PAF is assumed to be involved.

Administration, Inhalation↗
PubMed1991

Structure-activity studies on triazolothienodiazepine derivatives as platelet-activating factor antagonists.

A series of triazolodiazepines was synthesized and evaluated for anti-platelet activating factor (PAF) activities. Structure-activity relationship (SAR) studies on this series revealed that the introduction of a methyl group into the 8-position of the thienodiazepine nucleus can lead to a lengthening of the duration of action. Introduction of a methyl group produced an asymmetric center and the enantiomers so formed were separated with an optical resolving column. In the in vitro assay system, the (+)-isomers displayed 50-200 times more potent anti-PAF activity than the (-)-isomers. After comparison of toxicology and pharmacokinetics, (+)-6-(2-chlorophenyl)-3- cyclopropanecarbonyl-8,11-dimethyl-2,3,4,5-tetrahydro-8H-pyrido[4' ,3':4,5]thieno[3,2-f][1,2,4]triazolo[4,3-a][1,4]diazepine (35(+)-isomer, E6123) was selected from among the compounds synthesized as a candidate for clinical study.

Animals↗
PubMed1991

[Role of combined pulmonary resection during descending thoracic aortic aneurysmectomy].

Between April, 1982 and December 1990, five of 98 patients who underwent aneurysm repair for the thoracic aorta received combined resection of the descending thoracic aortic aneurysm and the lung because of marked adhesion between the aneurysm and the lung. Partial resection of the upper lobe of the lung was performed in all of five patients with auto-suture device. Three of the five patients needed no homologous blood transfusion during the surgery. Neither operative death nor pulmonary complication related to lung injury and bleeding was noticed. Our results indicate that partial resection of the lung is beneficial for avoiding intra-operative rupture of the aneurysm as well as lung injury in patients with descending thoracic aortic aneurysm severely adherent to the lung.

Aged↗
PubMed1990

The amino-acid sequence of multiple lectins of the acorn barnacle Megabalanus rosa and its homology with animal lectins.

The amino-acid sequence of a lectin isolated from the coelomic fluid of the acorn barnacle Megabalanus rosa has been determined. The lectin (Mr 140,000) is a multimeric protein whose subunit consists of 173 amino acids and one carbohydrate chain attached to Asn-39. The amino-acid sequence was determined by the manual sequencing of peptides derived from the protein by digestion with Staphylococcus aureus V8 proteinase, lysine endopeptidase and chymotrypsin, as well as fragments produced by cleavage with cyanogen bromide. The amino-acid sequence of the lectin was compared with the sequence of one (Mr 64,000) of the multiple lectins of M. rosa. They are distinct molecules in spite of a significant homology in their amino-acid sequences. The amino-acid sequence includes some regions homologous to those in other invertebrate lectins, such as sea urchin and flesh fly lectins, and vertebrate lectins. This is the first report to show the amino-acid sequence of multiple lectins isolated from an invertebrate.

Amino Acid Sequence↗
PubMed1990

The positions of the disulfide bonds and the glycosylation site in a lectin of the acorn barnacle Megabalanus rosa.

The positions of the interchain and intrachain disulfide bonds and the glycosylation site in a lectin of the acorn barnacle Megabalanus rosa were determined. The lectin (Mr 140,000) is composed of the same subunit (Mr 22,000) which is cross-linked by disulfide bonds to form a dimer. Intact lectin yielded two fragments, CB1 and CB2, by cleavage with cyanogen bromide. One intrachain and two interchain disulfide bonds were identified as Cys-53-Cys-61, Cys-14-Cys-50' and Cys-50-Cys-14', respectively, by enzymatic digestion and Edman degradation of CB1. Two intrachain disulfide bonds were determined as Cys-78-Cys-168 and Cys-144-Cys-160 by enzymatic digestion of CB2. The two intrachain disulfide bonds are well conserved through all invertebrate lectins and calcium-dependent animal lectins. S-Carboxamidomethylated lectin was digested with Staphylococcus aureus V8 proteinase and separated by reversed-phase HPLC. Glycopeptides were detected by the 4-N,N-dimethylamino-4'-azobenzene sulfonyl hyrazide method. Sequence analyses of the glycopeptides showed that a carbohydrate chain attached to Asn-39.

Amino Acid Sequence↗
PubMed1990

Effects of a novel PAF antagonist, E6123, on PAF-induced biological responses.

E6123 is a new member of the benzodiazepine class of PAF antagonists. Although it has similar activity in vitro to the two representative antagonists WEB2347 and Y24180, in vivo it is far more active than these compounds. Thus E6123 was effective in inhibiting dose-dependently PAF-induced bronchoconstriction when administered orally or intravenously (IC50 1.0 and 1.3 micrograms/Kg, respectively, at 3 hr), and had a minimum effective dose of 10 micrograms/Kg and 3 micrograms/Kg, respectively, against PAF-induced hematoconcentration and edema at 3 hr after oral administration. Furthermore, E6123 protects mice from PAF-induced death dose-dependently (ED50 7 micrograms/Kg at 3 hr). In conclusion, E6123 should prove valuable in pharmacological and clinical research into the roles of PAF, and in therapy of diseases such as asthma, in which PAF is assumed to play a pathological role.

Animals↗
PubMed1990

Recovery of tryptophan in peptides and proteins by high-temperature and short-term acid hydrolysis in the presence of phenol.

The addition of 3% (w/v) phenol to 6 M HCl largely prevented the destruction of tryptophan during rapid hydrolysis of peptides and proteins at 166 degrees C for 25 min or at 145 degrees C for 4 h. This hydrolysis procedure was advantageous for amino acid microanalysis using conventional high-performance liquid chromatography with a precolumn derivatization technique. The recovery of tryptophan from proteins was at least 80%. The addition of phenol also improved the recovery of methionine and carboxymethylcysteine. The amount of tryptophan in proteins electroblotted onto a polyvinylidene difluoride membrane was determined by this method.

Chromatography, High Pressure Liquid↗
PubMed1990

Pharmacological activities of a novel thienodiazepine derivative as a platelet-activating factor antagonist.

(S)-(+)-6-(2-Chlorophenyl)-3-cyclopropanecarbonyl-8,11- dimethyl - 2,3,4,5 - tetrahydro - 8H - pyrido[4',3':4,5] thieno[3,2-fl-[1,2,4]triazolo]4,3-a][1,4]diazepine (E-6123) is a newly synthesized platelet-activating factor (PAF) antagonist. The effects of E-6123 on in vitro and in vivo PAF-induced responses were investigated. The IC50 values of E-6123 on 3H-PAF binding to human and guinea pig platelets were 2.7 and 3.0 nmol/l, respectively, and those on PAF-induced platelet aggregation in platelet-rich plasma of human, guinea pig and beagle dog were 10.1, 14.7 and 16 nmol/l, respectively. Oral administration of E-6123 at 3 and 10 micrograms/kg to dogs inhibited ex vivo PAF-induced platelet aggregation in a dose-dependent manner. In guinea pigs, E-6123 at 3 micrograms/kg completely inhibited ex vivo PAF-induced platelet aggregation up to 8 h and the inhibition was still significant at 24 h after administration. Occupancy of the platelet PAF receptor by E-6123 at 3 h and 24 h after administration amounted to 80% and 56%, respectively. Bronchoconstriction induced by PAF injection in guinea pigs was inhibited dose-dependently by oral or intravenous administration of E-6123 at similar doses. The IC50 value of E-6123 at 3 h after oral administration was 1 microgram/kg. Oral administration of E-6123 at 3 micrograms/kg inhibited the bronchoconstriction by more than 90% up to 8 h. Hemato-concentration induced by PAF injection in guinea pigs was inhibited by oral administration of E-6123 at 10 micrograms/kg. E-6123 also protected mice from PAF injection-induced death in a dose-dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1989

Isolation and characterization of a novel cytolytic factor in purple fluid of the sea hare, Aplysia kurodai.

A novel cytolytic factor, aplysianin P, which induces tumor lysis, was purified to apparent homogeneity from the purple fluid of the sea hare Aplysia kurodai. Purified aplysianin P was a single Mr 60,000 polypeptide. This factor was half-maximally active at 3-25 ng protein/ml and lysed all the tumor cells tested but did not lyse normal WBC or RBC. Aplysianin P was labile on treatments with heat, low pH, urea, and periodate, but not with Pronase. The factor completely inhibited the syntheses of DNA, RNA, and protein by tumor cells within 2 h and caused their complete cytolysis within 18 h. Tumor lysis by aplysianin P was inhibited by N-acetylneuraminic acid, suggesting that recognition of the sugar moiety is a key step in the cytolysis induced by aplysianin P. The factor also prolonged the survival of mice bearing syngeneic MM46 ascites. It did not resemble previously isolated antineoplastic glycoproteins from the eggs (aplysianin E) or albumen gland (aplysianin A) of A. kurodai in terms of molecular size, antigenicity, or amino acid composition. These results suggest that aplysianin P found in an invertebrate, the sea hare, is a new antitumor factor.

Amino Acids↗
PubMed1989

Selective potentiation of lymphocyte-derived macrophage chemotactic factor release in complete Freund's adjuvant-treated guinea pigs.

Dinitrophenol (DNP)-ovalbumin(OA)-induced tissue macrophage reaction in sensitized guinea pigs is enhanced by treatment with complete Freund's adjuvant (CFA). The enhancement of the reaction may be due to the increased production of a T-lymphocyte-derived macrophage chemotactic factor (LDMCF) because treatment of animals with CFA potentiates antigen- and concanavalin A(ConA)-induced release of LDMCF activity from spleen cells of the CFA-treated animals in vitro. This potentiating effect by CFA seems to be ascribed to the release of an adherent-cell-derived soluble factor from the CFA-treated animals. The adherent cell-derived factor, LDMCF-potentiating factor (LDMCF-PF), preferentially potentiates the release of LDMCF activity but not of eosinophil chemotactic activity from antigen- or Con-A-stimulated T lymphocytes. Protein synthesis is required for release of LDMCF-PF. Molecular weight of LDMCF-PF activity is assumed to be about 10,000-20,000. LDMCF-PF activity is sensitive to trypsin, to neuraminidase, and also to alkalinity at pH 11, suggesting that LDMCF-PF is a glycoprotein. The present study provides one explanation for the enhanced macrophage reaction in delayed-type hypersensitivity reactions.

Animals↗
PubMed1989

Purification and characterization of an antibacterial and antineoplastic protein secretion of a sea hare, Aplysia juliana.

The fetid secretion of a sea hare, Aplysia juliana, was lethal to crabs and also inhibited the growth of bacteria. When the secretion was partitioned between water and n-hexane, only the n-hexane layer, which had a nauseating odor, was lethal to crabs. The water-soluble fraction showed strong antibacterial activity and inhibited the growth of both Gram-positive and Gram-negative bacteria. Antibacterial activity of the water-soluble fraction was destroyed by heating at 50 degrees C for 15 min, but was resistant to treatment with proteolytic enzymes. The active principle, named julianin-S, was purified by gel filtration and ion exchange chromatography. The purified specimen gave a single protein showing a mol. wt of approximately 67,000, as determined by gel filtration. Julianin-S inhibited the growth of Bacillus subtilis by 50% at a concentration of 70 ng protein/ml. It was also cytotoxic to murine tumor cells and inhibited in vitro growth of L1210 cells by 50% at a concentration of 8 ng protein/ml.

Animals↗
PubMed1989

Quantitative determination of sulfated glycopeptide by two-dimensional electrophoresis on cellulose acetate membrane.

Quantitative determination of the sulfated glycoproteins present in tissue and secretion fluid was performed. After digestion of the specimen with pronase in order to convert glycoproteins to glycopeptides, the sulfated glycopeptides were separated from a mixture of acidic glycans (glycosaminoglycans, sialoglycopeptides and sulfated glycopeptides) by two-dimensional electrophoresis on cellulose acetate membrane [(1986) J. Biochem. Biophys. Methods 12, 239-246]. After staining with alcian blue, the spot of sulfated glycopeptide on the cellulose acetate membrane was cut out, and then only the dye bound to the sulfated glycopeptide was extracted with a 5% cetylpyridinium chloride solution at 100 degrees C for 15 min. The extract was then measured by absorbance at 615 nm using an authentic sulfated glycopeptide as a standard. This method facilitated the determination of sulfated glycopeptides, which were separated from other acidic glycans, within the range 0-25 micrograms.

Animals↗
PubMed1989

Purification and characterization of a cytolytic protein from purple fluid of the sea hare, Dolabella auricularia.

A novel cytolytic factor, dolabellanin P, was purified to apparent homogeneity from the purple fluid of the sea hare, Dolabella auricularia. Purified dolabellanin P is a single polypeptide of 60 kDa. The amino acid composition and the N-terminus of the factor were also determined. This factor nonspecifically lysed all the cells tested at 50-200 ng protein/ml. Dolabellanin P caused complete cytolysis within 2 h. The factor is distinct from antineoplastic glycoproteins previously isolated from eggs (aplysianin E) or albumen gland (aplysianin A) of Aplysia kurodai in terms of certain cytolytic properties. These results suggest that dolabellanin P, found in the sea hare, a marine invertebrate, is a new cytolytic factor.

Amino Acid Sequence↗