A possible mode of cardiovascular actions of dopamine in dogs

A possible mode of cardiovascular actions of dopamine was studied using ephedrine. In the dog pretreated with repeated administrations of ephedrine (total dose, 40 or 80 mg/kg, i.v.) or with combined administrations of ephedrine (total dose, 90 mg/kg, s.c. and i.v.) and reserpine (2 mg/kg, s.c., 24 hr previously), pressor responses to dopamine were eliminated and reversed to depressor responses whereas depressor responses to dopamine were potentiated. Positive chronotropic effects of dopamine were almost eliminated. Pressor and positive chronotropic effects of tyramine were almost abolished. Sympathomimetic effect of noradrenaline and adrenaline were potentiated while those of isoprenaline were inhibited. In the heart-lung preparation of ephedrine-treated dogs (total dose, 40 mg/kg, i.v.), cardiac stimulating effects of dopamine and tyramine were strongly depressed, and those of noradrenaline, adrenaline and isoprenaline were reduced to some extent. In the open-chest dogs, after pretreatment of cocaine (4 mg/kg, i.v.), pressor, positive inotropic and chronotropic effects of noradrenaline were potentiated, whilst those of tyramine were inhibited. Those of dopamine were not visibly altered, but depressor, negative chronotropic and inotropic effects of dopamine appeared at small doses. In the ephedrine-pretreated dogs, these sympathomimetic effects of dopamine and tyramine after cocaine were strongly depressed and those of noradrenaline were inhibited to a certain degree. The results obtained with ephedrine suggest that dopamine differs from other catecholamines and tyramine in the mode of cardiovascular actions.

[Phamacolofical studies of ifenprodil]

Pharmacological effects of ifenprodil (IP), 4-benzyl-alpha-(p-hydroxyphenyl)-beta-methyl-1-piperidineethanol-L-(+)-tartrate monohydrate (Funai Pharmaceutical), a potential vasodilator, were studied in the dog, rabbit, guinea-pig and mouse. 1) Intravenous administration of IP (0.1 approximately 1 mg/kg) exhibited a continuous fall in blood pressure, an increase in heart rate and an increase in cardiac contractile force in the dog. The depressor and chronotropic effects of IP appeared likewise in the pithed dog, and the depressor responses were slightly more evident in the rabbit. The cardiovascular responses to IP were not affected by pretreatment with atropine or diphenhydramine, however, the chronotropic and inotropic effects were completely removed and the depressor response was depressed to some extent by propranolol. On the contrary, a pressor response to adrenaline was reversed to a depressor one after IP in the dog. 2) In heart-lung preparation of dogs, IP brought about slight cardiac stimulating effects, such as an increase in contractile force and a rise in aortic pressure. 3) IP induced a transient slight excitation in in situ movements of the rabbit intestine, and a similar excitation followed with a inhibition in movements of isolated intestine (10(-6), 2.5 X 10(-5) g/ml. This slight excitation was not affected by pretreatment with atropine, whereas the inhibition was depressed to a certain degree by simultaneous pretreatment with phenoxybenzamine and propranolol. IP produced a slight tonic increase in the guinea-pig isolated intestine and inhibited markedly the excitatory effect of histamine in the intestine. 4) IP did not affect the bronchial muscle but inhibited prominently a contractile respose of the muscle to histamine in in situ experiments on guinea-pig. 5) Locomotor activity was reduced dose-dependently and thiopental hypnosis was potentiated similarly after subcutaneous administration of IP (5 approximately 40 mg/kg), while skeletal muscle relaxant effects were not observed. 6) Survival time under a condition of acute anoxia was not changed with a dose of 0.5 and 1 mg/kg, but shortened with a dose of 5 mg/kg. The results suggest that IP has a alpha-blocking, a beta-stimulating and a moderate antihistaminic effects, and shows some cardiovascular effects, such as continuous depressor and chronotropic effects, and a moderate central inhibition.

Mössbauer effect and electron paramagnetic resonance studies on yeast aconitase

Mössbauer effect and electron paramagnetic resonance (EPR) were measured for yeast aconitase [EC 4.2.1.3] purified from the cells of Candida lipolytica (ATCC 200114). Mössbauer spectra suggested that yeast aconitase nostly contained two high-spin Fe(III) ions in an antiferromagnetically coupled binuclear complex that resembled oxidized 2 Fe ferredoxins, together with a small amount of high-spin Fe(II). EPR spectra recorded no signal at 77degreesK, but showed a slightly asymmetric signal centered at g=2.0 at 4.2degreesK, presumably due to the small amount of Fe(II) Fe(III) pairs.

Superoxide dismutases from a blue-green alga, Plectonema boryanum

Iron-containing and manganese-containing superoxide dismutases were found in Plectonema boryanum. The Mn-enzyme occupies about 10% of total activity. The Fe-enzyme was purified to near homogeneity. It contains 2 atoms of iron per mol. Its molecular weight is 41,700 and it is composed of two subunits of identical molecular weight without disulfide linkage. Amino acid composition is presented. Electron paramagnetic resonance spectrum revealed that iron occurs in a high spin ferric form and in some anisotropic environment. The absorption spectrum and the absence of acid-labile enzymes are insensitive to cyanide. Although the Fe-enzyme is sensitive to hydrogen peroxide, the Mn-enzyme is not.

Metastatic carcinoma in cirrhotic liver--Statistical survey of autopsies in Japan

Autopsy records for the period of 1958-1972 in Japan as listed in 'The Annual of the Pathological Autopsy Cases' were reviewed and the incidence of metastatic neoplasms in the cirrhotic liver was surveyed. This included data from 240,377 patients of which 8,798 cases (3.66%) had liver cirrhosis excluding biliary and cardiac types. Those who had coexistent liver cirrhosis and extrahepatic malignant neoplasm totalled 737 (8.4% of the cirrhotics). Of these 737 patients, 194 had metastatic neoplasms to the cirrhotic liver (26.3% of those who had cirrhosis and neoplasms). The incidence of hepatic matastases in the non-cirrhotics was 38.3% during the period 1958-1959, and 43.2% in 1967-1968. The difference in incidence of metastasis to the cirrhotic as opposed to the non-cirrhotic liver is statistically significant. This finding supports the claim that metastatic neoplasms to the cirrhotic liver are less frequent than metastasis to the non-cirrhotic liver. However, they are by no means rare. These results may be due to that the patients with both cirrhosis and neoplasms can not live long enough for metastasis to develop.

Specific movement of cell membranes fused with HVJ (Sendai virus)

When Ehrlich ascites tumor cells fused with UV-inactivated HVJ (Sendai virus) were cultured, the viral envelope antigens, which had been integrated at random into the cell membranes, accumulated at one site on the fused cell. The site showed a specific structure, namely, a projection of the cytoplasm from the spherical fused cell surface with clusters of many long microvillilike protrusions from it. When the fused cells were conjugated with antibody against Ehrlich ascites tumor cells and cultured, the antigen-antibody complex also accumulated on the projection.Associated with the development of the projection and accumulation of viral antigens, vacuoles developed at the base of the projection in the cytoplasm of the fused cells in culture. The development of the projection and vacuoles and the accumulation of viral antigens were all inhibited by glucose, mannose, galactose, sodium azide, and cycloheximide, and these inhibitions were reversible. All these structures were observed in multinucleated cells, but few in mononucleated cells after reaction with HVJ (Sendai virus). We consider that these three phenomena correlate with each other and may result from changes in cell-membrane systems caused by fusion of cells.

An anucleolate mutant of the cellular slime mould Dictyostelium discoideum

Summary: An anucleolate mutant (AN) was isolated from the cellular slime mould, Dictyostelium discoideum. The AN developed normally until the beginning of culmination, when development stopped and no differentiation of the spore or stalk cell occurred. The AN had nucleoli at the vegetative stage, but lost them after formation of a cell mass, in contrast to the wild type (WT) which possessed them throughout development. AN cells disaggregated from a slug, reconstructed nucleoli and resumed vegetative growth. Difference in tetrazolium reduction between the prestalk cell and the pre-spore cell, as observed in the WT, was not detected in the AN, although vacuoles specific to the pre-spore cell were formed. When the WT and AN cells were mixed, they aggregated together, but no interaction in cell differentiation was observed. The roles of nucleoli in the development of this organism are discussed.