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Biomedical subjects

M Takeda

Publications and source records attributed to M Takeda.

At least 865 records · Page 48Linked to original sources
PubMed1987

Time dependent impairment of vagally mediated inhibition of noradrenaline release in the dog heart.

The effects of right vagal nerve stimulation on changes in heart rate, mean coronary sinus blood flow, and noradrenaline overflow rate induced by right cardiac sympathetic nerve stimulation were investigated in anaesthetised decentralised, open chest dogs, when autonomic nerve fibres were stimulated tonically at a frequency of 4 or 5 Hz for 2.5 min. Sympathetic nerve stimulation produced a mean(SEM) increase in each of the variables (50(7.0)% in heart rate, 48(6.3)% in coronary sinus blood flow, and 87.0(12.3) ng.min-1 in noradrenaline overflow rate into coronary sinus blood at 30 s), and the increments remained almost constant during continued stimulation. Vagal nerve stimulation induced a decrease of 34(3.4)% in heart rate and of 22(4.5)% in coronary sinus blood flow and a slight reduction (-9(3.2) ng.min-1) in noradrenaline overflow rate at 30 s. Only the decrease in heart rate faded slightly with time. Combined stimulation of the sympathetic and parasympathetic nerves induced a decrease of 19(5.0)% in heart rate and 4(7.5)% in coronary sinus blood flow and an increase of 34.3(12.0) ng.min-1 in noradrenaline overflow rate at 30 s. The decrease in heart rate and coronary sinus blood flow faded, and noradrenaline overflow rate increased significantly to 86.4(17.3) ng.min-1 at 120 s. The temporal changes in heart rate, coronary sinus blood flow, and noradrenaline overflow rate caused by combined nerve stimulation were readily inhibited by treatment with atropine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Diapause induction and termination: north-south strain differences in Ostrinia nubilalis.

Diapause induction and termination responses of a northern strain (Minnesota [MN]) of Ostrinia nubilalis were compared with those of a southern strain (Georgia [GA]). A thermoperiod in constant light (12 hr at 25 degrees C alternating with 12 hr at 4 degrees C) failed to induce diapause in GA larvae, but approximately 50% diapause induction was observed in the MN population. Moreover, the 50% of MN larvae that continued their development (i.e., underwent pupation and adult development) did so at a slower rate, as measured by days to pupation, than GA larvae. In the laboratory, diapausing MN larvae responded more slowly to the optimal light-dark (LD) cycle for terminating diapause, LD 16:8, than did GA larvae. In the field MN populations are univoltine (i.e., are characterized by one generation per year). A delayed termination response in the spring, coupled with a longer critical daylength for diapause induction as daylength decreases during late summer (earlier diapause) restricts the time during which development can occur as contrasted with GA populations. In addition, it is postulated that these two phenomena, coupled with a possibly slower growth rate in the MN insects as revealed under laboratory conditions, may collectively represent the basis for univoltinism in the field.

Animals↗
PubMed1987

Cardiovascular responses to a newly developed cardiotonic agent, ZSY-39 [4-methyl-5-(4-pyridinyl)-thiazole-2-carboxyamide] in dog cross-circulated atrial and ventricular preparations.

The cardiovascular effects of ZSY-39 [4-methyl-5-(4-pyridinyl)-thiazole-2-carboxyamide] were investigated in isolated and blood-perfused atrial and ventricular muscles perfused with donor's arterial blood. When ZSY-39 was given i.v. to the intact donor dog, hypotension with a slight tachycardia was induced at a dose range of 30-1,000 micrograms/kg. At the same time, slight positive chronotropic and inotropic responses appeared in isolated, perfused atria at i.v. doses of 300 and 1,000 micrograms/kg ZSY-39, indicating a relatively dominant inotropic action. Direct injection of ZSY-39 into the cannulated sinus node artery of the isolated atrium produced positive chronotropic and inotropic responses in a dose-related manner (1 to 300 micrograms). ZSY-39 also induced a dose-dependent increase in developed tension in the isolated ventricle. The positive chronotropic and inotropic effects of ZSY-39 were not modified by an adequate dose of propranolol which completely blocked norepinephrine-induced positive chronotropic and inotropic responses. From these results, it is concluded that ZSY-39 has mild cardiotonic properties, showing relatively selective positive inotropic activity.

Animals↗
PubMed1987

Effects of DJ-7141, a new alpha-2 agonist, 2-(2-chloro-6-fluorophenyl)-2,3,5,6-tetra-hydro-1H-imidazo[1,2-a] imidazole hydrochloride, on the isolated atrium, cross-perfused with blood from a support dog.

The effects of DJ-7141, a new alpha-2 agonist, on an isolated atrial preparation cross-perfused with arterial blood from a support dog were investigated. In the isolated atrium, a selective injection of DJ-7141 (1-100 micrograms) into the sinus node artery induced dose-dependent positive chronotropic and inotropic effects. The positive cardiac effects of DJ-7141 were not only inhibited by propranolol and by imipramine, but reversed to negative effects, whereas the positive cardiac effects of norepinephrine were blocked by propranolol and potentiated by imipramine. Tetrodotoxin (TTX) did not modify the cardiac responses to DJ-7141. After propranolol treatment, the negative chronotropic and inotropic responses to DJ-7141 were not influenced by atropine, which completely blocked acetylcholine-induced cardiac responses. When DJ-7141 was injected into the support dog at a dose of 10-300 micrograms/Kg i.v., it induced a brief increase in femoral arterial blood pressure and a long-lasting decrease in heart rate in the support dog and increases in atrial rate and contractile force in the isolated atrium. These results suggest that the new alpha-2 agonist, DJ-7141, induces indirect positive chronotropic and inotropic effects due to a tyramine-like action and direct negative cardiac effects in the isolated dog heart, and that the tyramine-like effect may be partially responsible for the increase in blood pressure seen with DJ-7141 in in situ dogs.

Adrenergic alpha-Agonists↗
PubMed1987

[Clinical trial of SM-108 in myeloproliferative disorders].

SM-108 (4-carbamoylimidazolium-5-olate) is a new purine antagonist which blocks IMP dehydrogenase, the key enzyme of de novo GMP biosynthesis. Eleven patients were entered into a clinical study of SM-108 for the treatment of myeloproliferative disorders. These included 10 cases of chronic myelogenous leukemia (CML) and one case of essential thrombocythemia (ET). Two cases of CML had received prior chemotherapy. SM-108 was given orally at a dose of 400-600mg/m2 daily. Of nine evaluable cases, four cases of CML achieved complete responses and two cases of CML achieved partial responses (response rate = 66.7%). The duration of drug action was short, and the daily dosage required adjustment at frequent intervals. Long-term response without therapy has not been seen with SM-108 in CML. There was no response in the case of ET. The side effects included constipation (1/11), diarrhea (1/11) and mild hepatic toxicity (1/11). No cardiac or renal toxicity was observed.

Adult↗
PubMed1987

Pharmacological analysis of chrono- and inotropic responses to diazepam in the isolated, blood-perfused canine atrium.

Effects of diazepam on the pacemaker activity and atrial contractility were investigated using the isolated and blood-perfused canine atrium. When diazepam in a dose range of 3-300 micrograms was injected directly into the sinus node artery, biphasic (negative followed by positive) chrono- and inotropic responses were dose-relatedly evoked. These responses were not affected by atropine in a dose which blocked ACh-induced negative ones. Propranolol inhibited positive chrono- and inotropic responses to diazepam, and prolonged the duration of the negative responses. Imipramine, in a dose which blocked tyramine-induced positive responses, significantly augmented the positive inotropic responses to diazepam. From these results, it is suggested that diazepam induces direct negative chrono- and inotropic effects, the mechanism of which remains to be defined, and indirect positive effects by catecholamine release from the sympathetic nerve terminals, though not mediated by a tyramine-like action. Diazepam tended to potentiate negative chrono- and inotropic effects of adenosine but not significantly, suggesting that diazepam plays a minor role as an adenosine potentiator in the dog right atrium.

Acetylcholine↗
PubMed1987

Clinical effect of newly developed oral carbonaceous adsorbent (AST-120) in patients with advanced stages of chronic glomerulonephritis.

Clinical effects of a newly developed oral carbonaceous adsorbent (AST-120) in patients with advanced stages of chronic glomerulonephritis is described. Measurements of serum creatinine were performed before, during and after the administration of AST-120. The reciprocal of serum creatinine concentration was also plotted serially in each patient. The mean levels of the slope of the reciprocal serum creatinine vs time plot after administration of AST-120 was decreased compared with those before the administration of AST-120 but there was no statistical significance (p greater than 0.10). Further studies with more patients are needed to determine whether the administration of AST-120 may be useful for treatment of patients with chronic glomerulonephritis.

Adsorption↗
PubMed1987

[A case of persistent trigeminal artery aneurysm treated by proximal obliteration of feeding vessels in both intra- and extracranial compartments].

The authors described a case with a saccular aneurysm of the persistent trigeminal artery (PTA) treated with intra- and extracranial proximal obliteration of the feeding arteries. PTA aneurysm is a rare disorder found only 14 cases in the literature. There have been only 4 cases treated by surgical procedure; 2 underwent direct surgery and the remaining 2 had carotid ligation. Both of the cases treated by direct obliteration of the aneurysm sustained diplopia and sensory disturbance around the orbit as postoperative neurological deficits. We thought another choice of treatment to reduce the risk of rupture of the aneurysm avoiding postoperative complications. Clinical presentation of the present case was rt-oculomotor palsy, which disappeared before the operation. Cerebral angiography disclosed an intracavernous sinus aneurysm with a broad neck arising from the rt-internal carotid-PTA junction. Bilateral posterior cerebral arteries were perfused by the rt-internal carotid artery was compressed manually, lt-vertebral angiography showed the aneurysm and the internal carotid artery simultaneously via the PTA as retrograde filling. Because the direct surgery might cause damage to the cranial nerves passing through the cavernous sinus, we employed proximal obliteration of the feeding vessels. The operation was done by the following steps: ligation of the cervical portion of the rt-internal carotid artery, rt-superficial temporal artery-middle cerebral artery anastomosis, clipping of the PTA at the basilar side.(ABSTRACT TRUNCATED AT 250 WORDS)

Cavernous Sinus↗
PubMed1987

Pharmacologic basis of responses to midazolam in the isolated, cross-perfused, canine right atrium.

The effects of midazolam on atrial rate and contractile force in the isolated canine atrium perfused with donor blood were investigated. When midazolam in a dose range of 100-1000 micrograms was injected directly into the sinus node artery of the isolated atrium, biphasic (negative followed by positive) chronotropic and triphasic (positive, negative followed by positive) inotropic effects were induced. After propranolol or imipramine, the positive chronotropic and the secondary positive inotropic effects were significantly suppressed, but the initial positive inotropic effect was not affected. Tetrodotoxin, atropine, or R05-4864, a selective ligand for peripheral benzodiazepine binding sites, did not modify midazolam-induced effects. When midazolam in a dose of 0.1-1 mg/kg was administered intravenously to the donor dog, monophasic negative chronotropic and inotropic effects in the isolated atrium were observed but were not as prominent. We conclude that midazolam has direct cardiac inhibitory properties including catecholamine release due to a tyramine-like action.

Animals↗