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Biomedical subjects

S Imai

Publications and source records attributed to S Imai.

At least 595 records · Page 33Linked to original sources
PubMed1986

Cardiotonic and coronary vasodilatatory effects of amrinone in the canine heart-lung preparation with a support dog as compared with those of dobutamine.

Analysis of the relative magnitude of the positive inotropic and chronotropic effects and the coronary vasodilating effects of amrinone conducted in the canine heart-lung preparation with a support dog in comparison with those of dobutamine demonstrated that amrinone was a preferential coronary vasodilator rather than a selective positive inotropic agent. An in vitro experiment in the canine papillary muscle suggested the initiation of the slow response action potential as a mechanism of the positive inotropic effect of amrinone.

Aminopyridines↗
PubMed1986

Effects of deoxyribonuclease I and neuraminidase treatments on the specific binding of 3H-prazosin and 3H-quinuclidinyl benzilate (3H-QNB) to alpha-adrenergic and muscarinic receptors in rat myocardial membranes.

The effects of neuraminidase and deoxyribonuclease I (DNase) treatments on the specific binding of 3H-prazosin and 3H-quinuclidinyl benzilate (3H-QNB) to alpha-adrenoceptors and muscarinic cholinergic receptors in the membrane of the rat myocardium was examined, and the dissociation constant (Kd) and the maximum number of binding sites (Bmax) was analyzed using the method of Scatchard analysis. Although no changes in Kd values were observed when DNA or sialic acid was removed from cardiac muscles by treatments with DNase or neuraminidase, the Bmax values of alpha-adrenergic and muscarinic receptors were markedly decreased after treatment with DNase, while neuraminidase treatment induced an increase in the Bmax values of the alpha-adrenoceptors. The possibility that these results provide the basis for elucidation of the characteristics of these receptors in the rat myocardium was discussed.

Animals↗
PubMed1986

Assessment of the cardiohemodynamic effects of ibopamine, an orally-active dopamine analogue, in the anesthetized open-chest guinea pig and the isolated guinea pig atria.

In the anesthetized open-chest guinea pig, ibopamine (10-300 micrograms/kg, i.v.), epinine (10-100 micrograms/kg, i.v.) and dopamine (10-300 micrograms/kg, i.v.) produced dose-related increases in heart rate (prevented by 20 micrograms/kg pindolol, i.v.), left ventricular dP/dt max and aortic flow. Ibopamine produced pressor effects (prevented by 0.5 mg/kg phentolamine, i.v.), while dopamine produced a slight depressor effect. A biphasic response (the pressor phase followed by a depressor) was observed after epinine, although the depressor phase was not significant. Calculated total peripheral resistance (TPR) tended to be increased after ibopamine and epinine (initial phase), while it was decreased after dopamine. Pindolol potentiated the increase in TPR produced by ibopamine and epinine, while the increase in TPR was converted to the decrease after phentolamine. Decreases in TPR produced by epinine and the highest dose of dopamine were inhibited by pindolol. In the isolated guinea pig atria, ibopamine (10(-6)-10(-4) M) increased the atrial rate and the developed tension in a concentration-related manner. The positive chronotropic and inotropic effects of ibopamine were of the same order as those of epinine.

Animals↗
PubMed1986

Two cases of spontaneous malignant fibrous histiocytoma in Wistar rats.

Spontaneous malignant fibrous histiocytoma (MFH) of subcutaneous tissues was found in 2 Wistar rats of a 18-month-old male and a 21-month-old female. These tumors consisted of spindle, oval, myxoid and giant cells. In the female rat, a similar histological pattern was found in the metastatic tumor nodules in the lung and liver. In the electron microscopy, four differentiated cells of fibroblast-like, histiocyte-like, giant and undifferentiated cells were identified in these tumors. Spontaneous MFH of Wistar rats in the present study was quite similar to those reported in rats of other strains.

Animals↗
PubMed1986

Genetic marker patterns and endogenous mammary tumor virus genes in inbred mouse strains of Japan.

In order to establish the genetic relatedness of the inbred mouse strains kept in Nara, genetic marker patterns were determined in conjunction with a study on endogenous mammary tumor viral genes in these strains. Isoenzyme patterns combined with patterns of other genetic markers, show that the unrelatedness between various inbred strains of the dd stock is as high or even higher as between strains of known different origin and geneology. Based on endogenous viral gene patterns the dd stock derived mice can be subdivided into three group, DDD, DDN, DDO, KF and DD/Tbr. The DD/Tbr and its foster-nursed substrain (DD/Tbrf) have the lowest number of endogenous viral genes, i.e. two, while the other strains carry 4-6 such genes. The SLN and SHN strains, derived from a Swiss stock, have a similar pattern of viral genes different that of all other strains studied, also strains of Swiss origin from other sources, such as the NFS and the GR.

Animals↗
PubMed1986

[Spontaneous calcification in F344/Slc and F344/JCL rats].

F344/Slc and F344/JCL rats 2 years of age were histologically examined for the incidence and distribution of calcification. In the male rats of both strains, calcification was observed in the testis, lung, brain, kidney, heart, aorta, cornea, prostate and seminal vesicle respectively. In the female F344/JCL rats, calcification appeared in the kidney, lung, cornea, brain, stomach, ovary and heart. Among these of both sexes, the lung was one of the most affected organs for calcification. On the other hand, calcification in the kidney was more severe and frequent in the females than in the males, suggesting that the sex may be one of enhancing factors for calcification.

Animals↗
PubMed1986

Relaxant effects of pinacidil, nicorandil, hydralazine and nifedipine as studied in the porcine coronary artery and guinea-pig taenia coli.

Effects of pinacidil, a newly synthesized vasodilator, on contractures induced in the porcine coronary artery and the guinea-pig taenia coli were investigated in comparison with those of nicorandil, hydralazine and nifedipine. These four substances produced a dose-dependent relaxation of K+-induced contracture in the coronary artery, and the order of relaxant activity was nifedipine greater than pinacidil greater than hydralazine divided by nicorandil (IC50: 1.62 X 10(-8), 1.98 X 10(-4), 1.70 X 10(-3), 2.35 X 10(-3) M, respectively). Hydralazine inhibited the contraction induced by caffeine in a Ca2+-free (EGTA) high potassium medium in a concentration-dependent manner (IC50: 8.43 X 10(-3) M). Pinacidil and nicorandil produced a partial inhibition of this contraction (45.2, 22.3% inhibition at 10(-2) M, respectively), while nifedipine was ineffective. In the isolated guinea-pig taenia coli, these compounds caused a concentration-dependent relaxation. The relaxant action by pinacidil and nicorandil was more potent in spontaneously contracting preparation or in preparations contracted by 30 mM [K+]0 than in preparations contracted by 100 mM [K+]0, while the reverse was true with nifedipine. Hydralazine was effective at similar concentrations on these three types of contraction. From these findings it was inferred that the smooth muscle relaxing-action of pinacidil and nicorandil was ascribable to the inhibitory action on the spontaneous spike activities of the surface membrane. Inhibition of the mobilization of calcium from intracellular store sites may play some role.

Animals↗
PubMed1986

Epstein-Barr virus infection and oncogenesis in primary immunodeficiency.

Lymphomas occurred in 3 of 16 Japanese patients with ataxia telangiectasia (AT) and Wiskott-Aldrich syndrome (WAS). The patients had a persistently reactivated Epstein-Barr virus (EBV) infection with a remarkable decrease in virus-specific cellular immunity. In these patients, the B lymphocytes were more sensitive to EBV-induced events and to cellular proto-oncogene activation than seen in the healthy counterparts. This immunologic and genetic background was considered to explain the massive lymphoproliferation in these primary immunodeficiency disorders.

Adolescent↗
PubMed1986

Epstein-Barr virus-enhancing plant promoters in east Africa.

The extracts of a certain African plant species, Euphorbia tirucalli, were found to have markedly enhancing effects on the activation of latent Epstein-Barr virus (EBV) genomes in the EBV carrying lymphoblastoid cells and also on EBV-induced transformation of human lymphocytes. The Euphorbia tirucalli was especially noticeable in highly endemic areas of Burkitt's lymphoma (BL), an EBV-associated malignancy, in Kenya and Tanzania. The activation of the latent EBV genome and the EBV-induced transformation enhancement were also observed with the soil and drinking water taken around the plants, strongly indicating that the people living in BL endemic areas are frequently exposed to such an EBV-enhancing plant promoter substance.

Africa, Eastern↗
PubMed1986

[Obstetric factors associated with intracranial hemorrhage (ICH) in premature infants and antenatal prediction of ICH].

Obstetric factors associated with intracranial hemorrhage (ICH) were evaluated in 98 inborn premature infants of less than 1,500 gm birth weight or less than 32 weeks of gestation. ICH was detected in 25 (25.5%) of these infants by ultrasound sonography and/or computed tomography. No association of obstetric factors such as maternal age, parity, gravidity, premature rupture of the membrane, toxemia, placenta previa, fetal position, mode of delivery or fetal sex with ICH was noted. But the ICH group showed a higher incidence of placental abruption, infarction, infection and incompetent cervix than the non-ICH group. In addition, gestational ages and birth weights were less in the ICH group than in the non-ICH group, although differences were not significant except for the group with incompetent cervix (p less than 0.05). However, Apgar scores and FHR scores according to Krebs et al. for the ICH group were significantly lower than those for the non-ICH group. The two groups were distinguished by multivariable discriminant analysis of FHR scores, birth weights and gestational ages (discriminant efficiency, 3.74: F-value, 20.6: true positive ratio, 81.3%). These results suggested that antenatal prediction of ICH in premature infants was possible, but further studies are needed to elucidate the reliability of its prediction.

Adult↗