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Biomedical subjects

Y Akimoto

Publications and source records attributed to Y Akimoto.

At least 145 records · Page 8Linked to original sources
PubMed1985

A new model of ventricular fibrillation induced by isoprenaline and catechol-O-methyl transferase inhibitor at a high perfusion temperature in isolated rat hearts.

Isolated rat hearts were perfused with various concentrations of isoprenaline (0.01-10 mumol/liter) for 30 min at a constant flow rate (6.5 ml/min) at 37-44 degrees C. The occurrence of ventricular fibrillations was isoprenaline concentration dependent and also perfusion temperature dependent in the combined treatment with various concentrations of isoprenaline and high perfusion temperatures. When the hearts were perfused with isoprenaline (1 mumol/liter) in the presence of tropolone (100 mumol/liter) at 40-41 degrees C, the duration of ventricular fibrillations was significantly prolonged, but the incidence of ventricular fibrillations was similar to that produced with isoprenaline (1 mumol/liter) alone. The antiarrhythmic drugs such as quinidine sulfate, lidocaine hydrochloride, dl-propranolol hydrochloride, carteolol hydrochloride, atenolol, dl-verapamil hydrochloride, and diltiazem hydrochloride, given at a concentration of 10 mumol/liter, significantly suppressed the incidence and duration of such ventricular fibrillations. Bretylium tosylate (10 mumol/liter) significantly suppressed the duration of the ventricular fibrillations but not their incidence. These results indicate that ventricular fibrillation induced by combined treatment with a high concentration of isoprenaline and tropolone at a high perfusion temperature in isolated rat hearts is a more useful experimental model of arrhythmia than conventional models.

Animals↗
PubMed1985

Ampicillin concentrations in human serum, gingiva, mandibular bone, dental follicle, and dental pulp following a single oral dose of talampicillin.

Eighty-one patients who underwent the extraction of impacted mandibular third molars in the nonfasting state were given a single oral dose of talampicillin (500 mg) preoperatively. Specimens of venous blood (n = 132), gingiva (n = 70), mandibular bone (n = 78), dental follicle (n = 63), and dental pulp (n = 59) were obtained during the operation and assayed for ampicillin content. The mean peak concentrations in serum (9.64 micrograms/ml), gingiva (4.72 micrograms/mg), mandibular bone (1.77 micrograms/ml), dental follicle (3.46 micrograms/ml), and dental pulp (5.53 micrograms/mg) all occurred at approximately 150 minutes after administration of talampicillin. The ratios of the corresponding serum concentration to the peak concentrations in the various oral tissues when both were plotted as drug concentration curves were: gingiva, 0.50; mandibular bone, 0.16; dental follicle, 0.34; and dental pulp, 0.52. Talampicillin was absorbed well by the intestine, and sufficient concentrations of the resulting metabolite, ampicillin, were found in oral tissues.

Administration, Oral↗
PubMed1985

Ampicillin concentrations in human serum, gingiva, the mandibular bone, and dental follicle following a single oral administration.

Ampicillin (ABPC) concentrations in human serum, gingiva, the mandibular bone, and dental follicle after a single oral administration of ampicillin (500 mg) were assayed by the agar diffusion (paper disc) method. The peak times of all specimens were identical, being 120 min after administration. The peak concentrations of the respective specimens were 2.01 micrograms/ml, 1.03, 0.34, and 0.72 micrograms/g, respectively. The concentration ratios of gingiva, the mandibular bone, and dental follicle to their corresponding serum at the peak time were 0.51, 0.16, and 0.35, respectively.

Administration, Oral↗
PubMed1985

Concentrations of ampicillin and cefadroxil in human serum and mixed saliva following a single oral administration of talampicillin and cefadroxil, and relationships between serum and mixed saliva concentrations.

The concentrations of ampicillin (ABPC) from talampicillin (TAPC) and cefadroxil (CDX) in serum and mixed saliva were assayed by the thin layer disc plate method. Talampicillin and cefadroxil (500 mg) were given by a single oral administration. The relationships between serum and mixed saliva ampicillin and cefadroxil concentrations were evaluated in the paired specimens collected from 10 different persons, respectively. The means of concentration ratios of mixed saliva to serum ampicillin and cefadroxil were 0.006 +/- 0.003 and 0.025 +/- 0.010 (mean +/- SD), respectively. Significant correlation coefficients between mixed saliva and serum concentrations were found for both ampicillin and cefadroxil, which were r = 0.78, P less than 0.001, and r = 0.67, P less than 0.001, respectively.

Adult↗
PubMed1985

Alterations in biodistribution of [3H]Ro 15-1788 in mice by acute stress: possible changes in in vivo binding availability of brain benzodiazepine receptor.

The biodistribution of [3H]Ro 15-1788 in control and stress-loaded mice (forced swimming) was compared. In control mice, carrier-free [3H]Ro 15-1788 was selectively and highly distributed in Bz receptor rich brain regions, while radioactivity in the brain was very low following administration of carrier-added tracer, which suggested that in vivo non-specific binding of this tracer was very low. Significant changes in biodistribution of carrier-free [3H]Ro 15-1788 were observed in stress-loaded mice, which strongly indicated that in vivo binding availability of Bz receptor in the brain was rapidly and reversibly reduced by acute stress. The degree of these changes was very dependent upon the stressful conditions, such as swimming duration and water temperature, and a significant alteration in biodistribution of [3H]Ro 15-1788 was particularly observed in the cerebral cortex. Simplified Scatchard analysis of in vivo binding of this tracer was performed, and results suggested that these alterations were mainly caused by changes in the Kd value rather than the Bmax value.

Animals↗
PubMed1983

[Pharmacological studies of guanabenz. Effects on the peripheral nervous and other organ systems].

General pharmacological properties of guanabenz (GUB), a new anti-hypertensive agent, were studied in comparison with those of clonidine (CLD) and guanethidine (GUD). Intravenous or peroral administration of GUB caused a contraction of the nictitating membrane in cats and mydriasis in mice, while it produced an inhibitions of the gastrointestinal motility in dogs; the motility of isolated rabbit ileum; and chacol transport, salivation and gastric acid secretion in rats. GUB had no or slight inhibitory actions on contractile responses induced by peripheral sympathetic or parasympathetic nerve stimulation in various organs; however, it had antagonistic actions against the norepinephrine-induced contraction of isolated guinea-pig vas deferens. The contractile responses to epinephrine and tyramine in the nictitating membrane and to sympathetic nerve stimulation in isolated guinea-pig vas deferens were potentiated by GUB. GUB specifically antagonized the serotonin-induced contraction of the isolated rat fundus strip and nonspecifically inhibited acetylcholine, histamine or Ba2+-induced contractions of isolated guinea-pig ileum at higher concentrations. GUB exhibited local anesthetic actions and diuretic effects, but had no particular actions on neuromuscular transmission, isolated rat uterus, guinea-pig tracheal muscle and the hematic system. These effects of GUB were found to be almost identical with but less potent than those of CLD. The effects of GUD were basically different from GUB.

Animals↗
PubMed1982

Amoxicillin concentrations in serum, jaw cyst, and jawbone following a single oral administration.

Forty-four patient who underwent enucleation of jaw cysts were administered amoxicillin preoperatively. Specimens of venous blood (44), walls and fluids from periodontal (31) and dentigerous (13) cysts, and jawbone (26) were obtained during the operation and assayed for amoxicillin content. Measurable concentrations were found in all specimens. The levels were higher in periodontal cysts than in dentigerous cysts, and higher in maxillary bone than in mandibular bone. Since amoxicillin can easily and rapidly pass through the epithelial lining according to the change in concentration, the penetration by amoxicillin of blood/cyst wall/cyst fluid probably depends on simple diffusion.

Administration, Oral↗
PubMed1981

[Pharmacological study of mequitazine (LM-209) (II). Anti-allergic action (author's transl)].

The anti-allergic effect of Mequitazine (LM-209) which was found to have an anti-histaminic activity was investigated in guinea-pigs. The inhibitory activities of LM-209 on the Schultz-Dale reaction and ileum contraction by some mediators released from the sensitized guinea-pig lung were the same as those of clemastine fumarate (CL) but with 5 times the potency. LM-209 and CL, but these activities were less potent than in the case of disodium cromoglycate. The various anaphylactic reactions mediated by IgG in guinea-pigs were inhibited by LM-209, CL and chlorpheniramine maleate (CPM). The homologous PCA mediated IgE in rats was also inhibited by LM-209, CL and CPM, but the duration of the action with LM-209 was markedly longer. In experimentally-induced asthma, the decrease of respiratory rate and volume was significantly inhibited by LM-209, but was not affected by CL. Thus, LM-209 seems to inhibit the allergic reaction mainly by an antagonistic action on allergic mediators.

Anaphylaxis↗
PubMed1981

[Effects of diltiazem on catecholamine release from cat adrenal glands (author's transl)].

Effects of diltiazem on catecholamine (CA) release evoked by several secretagogues were investigated in cat adrenal glands perfused in situ with Locke solution. All compounds were introduced into the perfusion medium. It was found that the release of CA stimulated by either acetylcholine (ACh) (10(-4) M) or high K+ (56 mM) was reduced by approximately 50 and 90% in the presence of 10(-5) and 10(-4) M diltiazem respectively, while diltiazem at 10(-6) M exhibited little or no influence on the Ca release. In addition, diltiazem at a concentration of 10(-6) M or higher produced a dose-related decrease in the CA release evoked by introduction of CaCl2 (2.2 mM) into Ca2+-free perfusion medium. On the other hand, removal of Na+ from the perfusion medium (osmolarity was adjusted with osmotically equal amount of sucrose) caused an increase in release of CA from the glands. Diltiazem (10(-5) M or higher) also reduced this CA release, but its activity was weaker than those found in experiments with ACh, high K+, and Ca2+. In all cases, the effects were reversible on washout. On the contrary, diltiazem, even at a higher concentration of 10(-4) M, exhibited no inhibitory effect on the release of CA induced by acetaldehyde (3 X 10(-3) M). It was suggested that diltiazem, through its Ca2+-antagonistic action, may reduce the evoked CA release which depends on extracellular Ca2+.

Acetylcholine↗
PubMed1980

A pathological study of intracranial aneurysms particularly of aneurysms other than saccular ones.

The author has investigated grossly and microscopically 90 intracranial aneurysms among 63 individuals, autopsied at the Tokyo-to Medical Examiner Office and partly at the 2nd Department of Pathology, Showa University School of Medicine. These aneurysms consisted of 74 of the saccular type, 5 of the arteriosclerotic type, 6 of the spindle-shaped aneurysm of the vertebrals and 5 of the dolichoectatic type, respectively. In this paper, the author has discussed the differences of pathogenesis of the above mentioned four types of aneurysms. The saccular aneurysm is thought to occur from turbulence of blood stream by intimal thickening developing from "Verzweigungspolster" (VP) of Rotter at the neck of the aneurysm, and the arteriosclerotic aneurysm to occur by the same manner as the saccular one, superimposed on severe atherosclerosis during a long time. The spindle-shaped aneurysm of the vertebral arteries is thought to be of inflammatory nature, relating to slowness of blood stream in the vertebral arteries, and the dolichoectatic aneurysm to be due to hemodynamic disturbance of the vertebro-basilar artery system by means of atherosclerosis of the arterial walls neighboring to the top of the basilar artery.

Adult↗