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Biomedical subjects

H Imai

Publications and source records attributed to H Imai.

At least 559 records · Page 31Linked to original sources
PubMed1983

[Influence of indomethacin and clidanac on the blood pressure lowering effect of beta-blockers].

In conscious rabbits, the intravenous administration of pindolol (1.25 mg/kg), propranolol (1 mg/kg) and alprenolol (2 mg/kg) induced a highly significant decrease of mean arterial blood pressure and significant bradycardia. In the same model, the intravenous administration of saline, indomethacin, and clidanac did not affect the mean arterial blood pressure and heart rate. Pretreatment with indomethacin and clidanac reduced the effect of these beta-blockers on the mean arterial blood pressure and had no effect on the heart rate. Treating of the guinea pig heart homogenate with 1 microM indomethacin or clidanac decreased the number of beta-adrenoceptors without changing their affinity. These results suggest that indomethacin and clidanac interfere with beta-adrenoceptor-mediated effects.

Adrenergic beta-Antagonists↗
PubMed1983

Effect of a protein-bound polysaccharide preparation, PS-K, on dimethyl hydrazine induction of intestinal tumors in rats.

The effect of a protein-bound polysaccharide preparation, PS-K, on the induction of intestinal tumors by dimethyl hydrazine (DMH) was assessed in Wistar rats. One hundred and fifty-one rats were randomly divided into two groups. Seventy-two rats were treated with DMH alone and 79 rats were treated with DMH and PS-K. All animals were subjected to a sequential autopsy and all lesions within the gastro-intestinal tract were examined macroscopically and histologically. Tumor incidence in the DMH plus PS-K-treated group was significantly lower than that in the group treated with DMH alone. The most interesting histological finding was marked lymphoid infiltration in and around the tumors of the rats in the PS-K-treated group. The number of circulating lymphocytes dropped below the control range in the 25th and 35th weeks for the group treated with DMH alone, but the drop in the PS-K-treated group was smaller. Delayed-type hypersensitivity reaction to purified protein derivative was well maintained in the PS-K-treated rats. The most interesting findings in these experiments were differences in the serum blocking activities and serum immunosuppressive substance in these two groups; they were markedly reduced in the PS-K-treated rats. The present results may be explained in terms of competitive action of PS-K against the immunosuppressive factor produced by a tumor-bearing host.

Animals↗
PubMed1982

Morphology and intracellular responses of an identified dorsal raphe projection neuron.

Stimulation of ventral medial tegmentum elicits an antidromic action potential and an inhibitory postsynaptic potential in dorsal raphe projection neurons. The inhibitory postsynaptic potential is not wholly due to activation of recurrent inhibitory circuits as it is not monosynaptic and its onset precedes the antidromic action potential. Light microscopic examination of horseradish peroxidase-filled projection neurons reveals a neuron type with radiating, poorly branched dendrites and terminal dendritic thickets. The axon of the exemplary neuron presented is seen to leave the nucleus but gives off a single collateral while still within the parent cell's dendritic domain.

Action Potentials↗
PubMed1982

The importance of the presence of metabolizable sugars in a medium for in vitro fertilization of hamster eggs with postovulatory oviduct contents.

Hamster eggs with postovulatory oviduct contents were added to a simple defined medium, without serum albumin, but supplemented with different combinations of energy sources. They were then inseminated by epididymal spermatozoa. In a medium containing D-glucose but without pyruvate and/or lactate, high proportions of acrosome-reacted spermatozoa (78-94%) and eggs undergoing fertilization (89-96%) were obtained 9-9.5 h after insemination. With only pyruvate or lactate as substrates, or with both pyruvate and lactate, acrosome reactions occurred in only 2-4% of the sperm. When D-glucose ranging in concentration from 2.78 to 8.34 mM was added, a high proportion (82-95%) of the eggs inseminated were found to be fertilized. Substituting D-galactose, L-glucose, L-fucose, D-lactose, or D-saccharose for D-glucose resulted in very low numbers of acrosome-reacted sperm (0-12%) and fertilized eggs (0-7%). However, in the presence of metabolizable sugars, such as D-mannose or D-fructose, the acrosome reaction was seen in 78-85% of the sperm examined and 87-95% of the eggs tested were fertilized.

Animals↗
PubMed1982

Abnormal platelet aggregation response in Huntington's disease.

Platelet aggregation response to epinephrine, dopamine, serotonin, adenosine diphosphate, arachidonic acid, and collagen was examined in seven patients with Huntington's disease and nine of their relatives. All patients, except for two cases that were in terminal states, showed enhanced response to all the stimulants, especially to dopamine and epinephrine. The platelet aggregation response in many relatives also deviated from the normal limit. The relationship between platelet aggregation abnormality in Huntington's disease and the pathophysiology of the disease was discussed from the view of a generalized membrane defect hypothesis in Huntington's disease, and of disturbed cathecholamine metabolism, both in the CNS and periphery. A possibility that platelet aggregation response examination will be a useful screening test of offspring at risk was proposed.

Adenosine Diphosphate↗
PubMed1982

Coronary arterial heart disease in hybrid hares fed alternating cholesterol-enriched and normal diets.

At one-week intervals hybrid hares (Lepus europaeus X Lepus timidus) were fed supplemented or nonsupplemented commercial pellets. Supplements were 1% cholesterol (USP-grade) and 6% peanut oil. In addition, the normal nonsupplemented diet was fed for a month when they appeared weak or when serum cholesterol values exceeded 1,000 mg/dl at monthly examinations. At the end of 1 year on such an alternating regimen, the hares appeared well nourished. Atherosclerotic lesions were severe and involved the epicardial and intramyocardial segments of the coronary arteries as well as the thoracic and abdominal aorta. Coronary arterial lesions were characterized by fibromuscular thickening with stainable lipids, necrosis, and calcification. Intramyocardial arterioles were diseased with fibromuscular plaques rich in foam cells. Transmural infarcts of the left ventricle occurred distal to the stenotic arterial lesions. Exact mechanisms are unknown for the development of such functionally significant coronary atherosclerosis. Among the possible pathogenetic factors, however, the alternating schedule seems most important. Such a regimen resulted in fluctuating, mild to moderate hypercholesterolemia and relatively good nutritional state of hybrid hares.

Animals↗
PubMed1982

Effect of L-leucine-supplemented diet on the nicotinamide adenine dinucleotide content of rat liver.

The hepatic nicotinamide adenine dinucleotide (NAD) content was significantly lower in rats fed a diet supplemented with 0.45-10% L-leucine for 1-3 weeks than in control rats fed laboratory chow (24.6% protein). High dietary levels of leucine did not affect the activity of hepatic tryptophan pyrrolase or quinolinate phosphoribosyltransferase, which are key enzymes in the tryptophan leads to NAD pathway. The increased hepatic NAD contents 4 hours after intraperitoneal injections of the NAD precursors L-tryptophan, niacin and nicotinamide were not influenced by excess dietary leucine. These observations suggest that decrease in the hepatic NAD content by excess dietary leucine is not due to alteration of NAD metabolism resulting from accumulation of leucine or its metabolite. The uptake of 1 mM L-[side chain-2,3-3H]tryptophan into isolated jejunal segments was inhibited markedly by 10 mM-leucine. Similar inhibitory effects were observed with 10 mM L-valine, L-isoleucine, L-phenylalanine and L-methionine, but not-L-lysine, L-aspartate, L-alanine or glycine. The radioactivity in portal blood after administration of a solution of 10 mumol of L-[side chain-3-14C]tryptophan in 1 ml of physiological saline by stomach tube was inhibited markedly by addition to the solution of 100 mumol of L-leucine or the other amino acids that inhibited L-tryptophan uptake by isolated jejunal segments. These findings strongly suggest that decrease in the liver NAD content by excess dietary leucine is mainly due to competitive inhibition by L-leucine of intestinal absorption of L-tryptophan.

Animals↗
PubMed1982

[Inhibitory effect of TN-762 (suprofen) on platelet aggregation].

Inhibitory effects of TN-762 (suprofen), ketoprofen, and indomethacin on rat or rabbit platelet aggregation were examined. Of these compounds tested, Suprofen showed the most potent effect on platelet aggregation in vitro, especially in AA-induced rabbit platelet aggregation (IC50 = 0.01 microM). Suprofen showed an inhibitory effect similar to that of ketoprofen and indomethacin on rat platelet aggregation ex vivo. The lethal effect of AA in the rabbits was protected by suprofen (0.05 mg/kg p.o.) at concentrations lower than the other compounds. Similar to the compounds, suprofen had little effect on the PG I2 synthesis in the rat aorta. In order to test the direct effects of these compounds on the platelet avoiding the effects of other plasma components, gel-filtrated rat platelets were used. All tested compounds showed similar inhibitory effect. To investigating the interaction of these compounds with the lipid bilayers, we used the liposome as a model membrane. The tested compounds inhibited liposome aggregation induced by 4 mM Ca2+. In this experiment, the interaction of suprofen with the lipid bilayers was shown.

Adenosine Diphosphate↗