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Biomedical subjects

A Brunner

Publications and source records attributed to A Brunner.

At least 55 records · Page 3Linked to original sources
PubMed1980

Extrachromosomal oligomycin-resistant mutants of the petite-negative yeast Kluyveromyces lactis. Properties of mitochondrial ATPase and cross-resistance to inhibitors of phosphoryl transfer reactions.

The mitochondrial ATPase from oligomycin-resistant mutants which map on different regions of an extrachromosomal DNA (01 and 011 class mutants) showed an increased resistance to oligomycin and venturicidin when assayed in vitro as compared to the sensitive strains. The resistance to oligomycin of the isolated mitochondrial ATPase from 01 class mutants was higher than that of the 011 class mutants. Cross resistance of the oligomycin-resistant mutants to the antibiotics peliomycin and ossamycin, which also inhibit phosphoryl transfer reactions in mitochondria (Walter et al., 1967), was observed, 01 mutants being more resistant to ossamycin than 011 class mutants. At the concentrations of peliomycin studied, no difference in sensitivity among both groups of oligomycin-resistant mutants could be detected. Mitochondrial respiration and isolated mitochondrial ATPase activity are sensitive to venturicidin, suggesting that the previously observed (Brunner et al., 1977) in vivo venturicidin resistance of K. lactis is probably due to an impairment of the influx of the drug at the level of the plasma membrane.

Adenosine Triphosphatases↗
PubMed1978

[Pipoxizin, a new bronchodilator].

Pipoxizin is a new bronchodilator with the chemical name chlorhydrate-4-diphenyl-methylene-1-(2-/2-(2-hydroxy-ethoxy)-ethoxy/-ethyl/-ethyl)-piperidine. This substance exhibits powerful antihistaminic and antiserotonin properties but no parasympathetic or beta-adrenergic properties. The effects of Pipoxizin have been compared with those of the wellknown product hexoprenalin (Ipradol). Twelve male patients, each with bronchial obstruction, took part in the trials. Plethysmography before and after Alupent inhalation was carried out to determine the reversibility or irreversibility of the bronchial obstruction. On the following day, the plethysmorgraphic tests were repeated before and after intravenous injection of Pipoxizin, and on the third day, the tests were repeated again after intravenous injection of hexoprenalin. Pulse and blood pressure were monitored. Following the use of Pipoxizin, there was a significant decrease in the following parameters: RT, RE, RV, ITGV, pulse rate, and systolic blood pressure. A significant increase was found in FEV1. After hexoprenalin injection, there was a significant decrease only in RV and an increase in FEV1. A comparison of Pipoxizin and hexoprenalin shows a significant difference between the two products, Pipoxizin having the more favourable effect.

Bronchial Spasm↗
PubMed1978

The marginal band and its role in the ellipsoidal shape of Geochelone carbonaria erythrocytes.

Erythrocytes from a chelonian (Geochelone carbonaria) were submitted to physical and chemical treatments. Observations of their change in shape from ellipsoidal to spherical were made by means of light microscopy. A 100% change to the spherical shape was attained with erythrocytes under high temperature treatment (42 degrees C) for 45 min., and at room temperature (29 degrees C) plus colchicine, for 60 min. Erythrocytes kept at room temperature present changes in shape while those kept at low temperature (10 degrees C) did not exhibit significant changes in their original ellipsoidal shape, but displayed an intact marginal band (MB). By direct examination the diameter of microtubules was found to be nearly 300 A in the dissociated form and 0.70 mu when bundled. In cross section the value found for microtubule diameter was up to 210 A. These measures are compatible with those found by several other authors. Counting of microtubules by ultrathin sectioning indicated approximately 70 tubules per cell, a value that is higher than that found in other species. By means of electron microscopy the marginal band can be observed intact or dissociated into several dense rings formed by parallel microtubules running nearly or accompanying the periphery of the stroma. Temperature and colchicine are responsible for the depolymerization of the microtubules. In the stroma of spherical erythrocytes a dense peripheric fold can be observed but microtubules were never found. It is suggested therefore that the role of the marginal band is essential to maintain the ellipsoidal shape of chelonian erythrocytes.

Animals↗
PubMed1977

The isolation and genetic characterization of extrachromosomal chloramphenicol and oligomycin-resistant mutants from the petite-negative yeast Kluyveromyces lactis.

Spontaneous mutants of the petite-negative yeast Kluyveromyces lactis, resistant to the antibiotics chloramphenicol and oligomycin, were isolated and genetically characterized. Three chloramphenicol-resistant mutants showed non-Mendelian inheritance when crossed to sensitive parents. Of 5 oligomycin-resistant strains studied, three exhibited resistance due to the presence of an extrachromosomal mutation. The resistance of the other two deriving from a nuclear and recessive mutation. When two factor crosses in trans configuration were performed between two of the chloramphenicol and the five oligomycin-resistant mutants a polarity in recombination was observed with a predominance of sensitive (OSCS) over resistant (ORCR) reciprocal recombinants. Allelism tests carried out among the oligomycin-resistant mutants indicated the presence of at least two distinct extrachromosomal regions responsible for the resistance.

Chloramphenicol↗
PubMed1977

Chromosomal and extrachromosomal inheritance of erythromycin-resistance in the "petite-negative" yeast Kluyveromyces lactis.

Spontaneously arising erythromycin-resistant mutants were isolated in the "petite-negative" yeast Kluyveromyces lactis. Two independently arising mutants were studied, in one erythromycin-resistance was conferred by a single dominant nuclear gene, and in the other the resistance was extrachromosomally inherited. In fermentable medium growth of sensitive and resistant strains in presence or absence of erythromycin does not qualitatively change the cytochrome absorption spectra, whereas oxygen uptake of parental strains growing in glucose-medium is affected by the drug. The importance of "petite-negative" yeasts like Kluyveromyces lactis for the study of nucleo-cytoplasmic interrelations is discussed.

Chromosomes↗
PubMed1977

Induction of hemosome formation and hemoglobin biosynthesis in HeLa cells.

Tissue cultures of HeLa cells in Hank's medium suspension, previously mixed with a solution containing reticulocyte polysomes and/or free globin, hemoglobin and blood plasma from bled rabbits, were homogenized, and an electrophoretic pattern of hemoglobin band was obtained from the supernatant; hemoglobin denatures under the tissue culture conditions. HeLa cells show typical hemosomes, identidical to those found in immature erythrocytes of embryos, and adult mammals with hemolytic anemias. When HeLa cell suspensions are mixed with solutions void of anemic blood plasma, or containing normal rabbit blood plasma, anomalous organelles are formed in the cells, and no hemoglobin biosynthesis occurs.

Anemia↗
PubMed1977

Comparative ultrastructure of late rabbit-embryo erythroid cells in liver and peripheral blood.

A morphological study of hemoglobin biosynthesis activity in rabbit-embryo liver and peripheral blood was comparatively developed. Orthochromatic erythroblasts and reticulocytes of the same maturing degree were analysed through thin sections, as to their organellar constitution and behaviour regarding iron incorporation. It was found that peripheral blood erythroid cells contain mainly hemosomes, organelles taken as sites of final hemoglobin molecule biosynthesis. The ratio between the mean number of hemosomes in blood erythroid cell sections and that in liver erythroid cell sections reaches a little more than 6:1. Inversely, late liver erythroid cells are predominantly constituted by mitochondria that directly or indirectly participate in hemosome formation. The ratio between the mean number of mitochondria in blood erythroid cell sections and that in liver erythroid cell sections reaches 1:11. Besides this, the iron incorporation activity is higher in peripheral blood erythroid cells than in liver erythroblasts and reticulocytes. It is apparent that erythroid cells in the liver accumulate heme, given the ratio of the means of iron incorporation activity per cell to hemosome per cell (3.67), while blood erythroid cells, with a 1.08 ratio, synthesize heme, which is immediately afterwards integrated into the globin chains. The sudden increase in the formation of hemosomes when liver orthochromatic erythroblasts and reticulocytes enter the peripheral blood, reflecting an enhancement of hemoglobin synthesis, agrees with biochemical findings of other authors.

Animals↗
PubMed1975

The regulation of myo-inositol-1-phosphate-synthase activity from Neurospora crassa by pyrophosphate and some cations.

The effect of several cations on the inhibition by PPi of the enzyme myo-inositol-1-phosphate synthase (1L-myo-inositol-1-phosphate lyase (isomerizing) EC 5.5.1.4) from Neurospora crassa was studied. The study wastol biosynthesis can occur in the presence of an intracellular PPi concentration which exceeds the Ki for the enzyme by 350-fold. The inhibition of enzyme activity by PPi,at pH 7.7, was reversed, in decreasing order of effectiveness, by Mn-2, Fe-3

Ammonia↗