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Biomedical subjects

S Murata

Publications and source records attributed to S Murata.

At least 307 records · Page 17Linked to original sources
PubMed1981

Pharmacological studies on BB-1502, a new bronchodilator.

The pharmacological activities of BB-1502 (9-cyclohexyl-2-n-propoxy-9H-adenine), a potent bronchodilator and inhibitor of cyclic AMP phosphodiesterase, were compared with those of aminophylline in a number of biological systems. IOn vitro, BB-1502 relaxed guinea pig tracheal tissue at a concentration ca. 600 times lower than that required for aminophylline. The ability of BB-1502 to inhibit cyclic AMP phosphodiesterase of guinea pig lung origin was 15 times greater than that of aminophylline. The direct bronchodilator activity of BB-1502 determined in guinea pigs by the intraduodenal route was 5 times greater and the duration of the action longer than that of aminophylline. In dogs, intraduodenal BB-1502 inhibited bronchoconstriction induced by pilocarpine, histamine, or acetylcholine and the activity of the new compound was 4 to 7 times more potent than that of aminophylline. In experimental asthma studies, orally administered BB-1502 protected guinea pigs from allergy-induced asthma provoked by an antigen challenge with aerosolized egg albumin and here the potency was 4 times greater that that of aminophylline. Ascaris antigen-induced asthma in dogs was completely inhibited by the oral administration of BB-1502 in a dose of 1 mg/kg with significant protection seen at 0.3 and 0.1 mg/kg. No complete protection was obtained with aminophylline in the dog asthma model. Cardiovascular effects observed with guinea pigs and dogs following the oral administration of BB-1502 were considerably less than those seen with aminophylline. CNS side effects were nil in rats when BB-1502 was given at 3 times the dose that produced significant stimulation by aminophylline. Acute lethal toxicity determined in mice by the oral route was similar for BB-1502 and aminophylline.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1981

Electrochemical and ESR studies on Cu(II) complexes of bleomycin and its related compounds.

The 1:1 Cu(II) complexes of bleomycin (BLM) A2, BLM B2, epi-BLM B2, iso-BLM B2, depyruvamide-BLM A2, deglyco-BLM B2 and the structurally related peptides (P-5m, P-3A and P-3) have been comprehensively investigated by ESR and electrochemical methods. ESR spectra for Cu(II) complexes of BLM A2, epi-BLM B2, depyruvamide-BLM A2 and P-3 revealed the axially symmetric g-anisotropies. In contrast, ESR features of the iso-BLM B2, deglyco-BLM B2, P-5m and P-3A complexes, which lack the sixth ligation by the 3-O-carbamoyl group of mannose, exhibited rhombic g-anisotropies with decrease of the A parallel values. The cyclic voltamograms showed that all of the Cu(II) complexes underwent the well defined quasi-reversible one-electron Cu(II)/Cu(I) coupled redox reaction. The inverse of the redox potential, which measures the effective strength of the ligand field splitting, gave a linear relation with the observed g parallel value of each Cu(II) complex except for depyruvamide-BLM and P-3. The present results confirmed that the 3-O-carbamoyl group of the mannose moiety of the BLM molecule contributes to the stability of the metal site in BLM-Cu(II) complexes by ligation at the sixth coordination site.

Bleomycin↗
PubMed1981

[Effects of diltiazem on hemodynamics and His bundle electrogram in the anesthetized dog (author's transl)].

Effects of diltiazem, a calcium antagonist, on the cardiovascular system in the pentobarbital anesthetized dogs were investigated. Diltiazem (100 micrograms/kg and 300 micrograms/kg, i.v.) decreased blood pressure, heart rate and total peripheral resistance, while cardiac output and stroke volume were markedly increased. The max dp/dt of left ventricular pressure tended to increase with a dose of 100 micrograms/kg. Left ventricular end-diastolic pressure was slightly increased with a dose of 400 micrograms/kg. Rate pressure product was significantly reduced. Diltiazem (30 micrograms/kg and 100 micrograms/kg) increased pulmonary arterial flow together with the increase in both systolic and diastolic pulmonary arterial pressure. Diltiazem (100 micrograms/kg) increased common carotid, femoral and superior mesenteric arterial blood flow by 30 to 40%, whereas vertebral blood flow was increased by over 100%. The dose dependency in the vertebral blood flow was remarkable. Response of the vertebral artery to diltiazem was similar to that reported in the case of the coronary artery. In the His bundle electrogram, diltiazem increased the AH interval by about 10% at 100 micrograms/kg and 25% at 200 micrograms/kg, without changing the HV interval. Diltiazem-induced AH prolongation was completely depressed by epinephrine but only partially so by CaCl2. Thus, the effects of diltiazem on sinus rhythm and AV conduction in the anesthetized dog were more potent than the effects on cardiac contractility, although weaker than the effects of the vasodilating action. The vasodilator effects appear to be the primary action of diltiazem on the cardiovascular system.

Animals↗
PubMed1981

[Bronchodilator actions of diltiazem in vitro and in vivo (author's transl)].

Bronchodilator effects of diltiazem were investigated in the isolated guinea pig tracheal chain and in the anesthetized cat. Interaction of diltiazem with isoproterenol (iso) was also examined. Diltiazem (10(-4) g/ml) relaxed by 70% the tracheal chain contracted by histamine, 10(-5) g/ml. This effect of diltiazem was not affected by pretreatment with propranolol, 3 X 10(8) g/ml. Diltiazem (400 microgram/kg, i.v.) diminished by 20% the elevation of intratracheal pressure induced by serotonin aerosol, the effect of which lasted for approximately 20 min. On the other hand, diltiazem (10(-5) g/ml) produced no influence on the iso-induced relaxation of the guinea pig trachea. In the anesthetized dog, diltiazem (20 microgram/kg/min, i.v.) did not affect the iso-induced bronchodilation when histamine was used as a spasmogen, while the positive chronotropic action of iso was diminished. On the contrary, propranolol (30 microgram/kg, i.v.) potentiated the bronchoconstrictor effect of histamine and suppressed both the bronchodilating and positive chronotropic actions of iso. Thus, the effects of diltiazem differed from those of propranolol. In summary, diltiazem showed bronchodilation both in vitro and in vivo, although the activity was not so potent, With regard to the iso-induced bronchodilation, diltiazem had no effect at a dose which diminished the positive chronotropic action of iso.

Animals↗
PubMed1980

[Mechanism of action of certain fibrinolytic bis-tetrahydroisoquinolines: their antagonists and histamine- and 5-hydroxytryptamine-releasing effects (author's transl)].

1, 1'-Heptamethylene-bis-6, 7-dimethoxy-1, 2, 3, 4-tetrahydroisoquinoline (HBDT) and 1, 1'-tetramethylene-bis-6, 7-dimethoxy-1, 2, 3, 4-tetrahydroisoquinoline (bisobrin) produced an edema when given subcutaneously into the hind paws of rats. The inhibitory effects of various antagonists on the paw edema and fibrinolysis induced by HBDT were examined in rats to determine whether chemical mediators other than histamine were involved. The relation of histamine to the fibrinolytic activity of these bis-tetrahydroisoquinoline derivatives has already been reported. Both edema and fibrinolysis were significantly inhibited by pretreatment with promethazine, cyproheptadine or phentolamine, but not by dibenamine, propranolol, atropine, indomethacin or pyridinolcarbamate. epsilon-Aminocaproic acid inhibited the fibrinolytic activity completely without any effect on the paw edema. HBDT released 5-hydroxytryptamine (5-HT) along with histamine from rat peritoneal mast cells. However, the amount of released 5-HT was considerably smaller than that of histamine. These results suggested that bis-tetrahydroisoquinolines released both histamine and 5-HT and that these mediators produced paw edema and induced fibrinolysis by enhancement of plasmin production.

Animals↗
PubMed1980

Developmental process of chronic subdural collections of fluid based on CT scan findings.

One hundred twenty-four follow-up scans were performed on 24 patients who had had posttraumatic subdural collections of low density. Of the 24 patients, 6 developed chronic subdural hematomas. Six other subdural collections showed a temporary increase in attenuation but eventually resolved. The remaining 12 subdural collections resolved without apparent increase in density. Illustrative cases are presented with computed tomographic scans. The identity of these posttraumatic subdural lesions of low density is discussed. They seem to be posttraumatic subdural hygromas.

Adult↗