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Biomedical subjects

M Simon

Publications and source records attributed to M Simon.

At least 721 records · Page 40Linked to original sources
PubMed1975

Cardiovascular effects of 1-benzylimidazole.

A derivative of imidazole, 1-benzylimidazole [(1-phenylmethyl)-H-imidazole], was found to have strong cardiotonic activity. In isolated ventricular strips of rabbits, 6.3 times 10(-5) M 1-benzylimidazole (BI) increased contractile force by 100%, and in the intact cat, 0.5 mg/kg of BI increased cardiac output by 30 to 40%. The increase was maintained in both preparations for 5 to 30 minutes. Heart rate was not changed in the atropine-pretreated cat. Basic cycle length, recorded intracellularly in rabbit sinoatrial nodal cells, was increased by 8%. Since BI had many actions similar to the cardiac glycosides, including the absence of effects on rate and resistance to adrenergic beta blockers, it was of interest to determine whether BI and ouabain could interact and modify, or enhance their respective actions. In combination, it was found that ouabain and BI had summative effects on contractility and maintained the frequency-force relationships. In this respect, the action of BI is similar to that of glucagon and Ca++, but not to that of the catecholamines.

Animals↗
PubMed1975

[Radioimmunologic assay of alpha-fetoprotein in various normal and pathological conditions].

AFP can be measured by radioimmunoassay in 52 hours using an incubation at 18 degrees C for 48 hours and the double antibody solid phase method to separate the free labelled AFP from the labelled AFP bound to the antibodies. In these conditions, the sensitivity and precision of the assay are very satisfactory and the results are directly in correlation with the results obtained using the classical double antibody method. In the serum of normal people, except pregnant women, the concentration of AFP is not detectable or is less than 20 ng/ml. In the serum of pregnant women, AFP increases from the 8th. week of gestation to the 32nd., then stabilises or gradually decreases.

Carcinoembryonic Antigen↗
PubMed1974

Positioning flagellar genes in Escherichia coli by deletion analysis.

Two methods were devised to select a series of overlapping deletion mutations carried on episomal elements in Escherichia coli. The deletions were then used in an analysis of (i) the relative position on the genome of previously described mutant loci in the flagellar genes, (ii) the relative position of a newly defined cistron, flaN, and (iii) the orientation and direction of transcription of genes previously assigned to multicistronic transcriptional units. As a result of this analysis and previous work, we report the following arrangement of the flagellar genes in the his-aroD region of the E. coli genetic map: his-flaR-flaQ-flaP-flaA-flaE-flaO-flaC-flaB-flaN-hag-flaD-uvrC-flaI-mot- flaG-flaH. The genes flaA, P, Q, and R, flaB, C, O and E, and flaG and H are co-transcribed in that order.

Chromosome Mapping↗
PubMed1974

Assembly of hybrid flagellar filaments.

The distribution of flagellin subunits in flagellar filaments synthesized by merodiploid strains carrying two distinguishable hag loci has been examined. The filament was found to be a homogeneous co-polymer of the two subunits. This suggests that the subunits may be able to mix freely before being assembled.

Antigens, Bacterial↗
PubMed1974

Characterization of Escherichia coli flagellar mutants that are insensitive to catabolite repression.

In Escherichia coli, the synthesis of the flagellar organelle is sensitive to catabolite repression. Synthesis requires the presence of the cyclic adenosine monophosphate receptor protein (Crp) and 3',5'-cyclic adenosine monophosphate (cAMP); i.e., mutants that lack Crp or adenylcyclase (Cya) synthesize no flagella. We isolated and characterized a series of mutants (cfs) that restored flagella-forming ability in a Crp strain of E. coli. The mutations in these strains were transferred onto episomes and they were then introduced into a variety of other strains. The presence of the mutation resulted in flagella synthesis in Cya and Crp strains as well as in the wild type grown under conditions of catabolite repression. Deletion analysis and other genetic studies indicated that: (i) the cfs mutations had a dominant effect when they were in the transconfiguration in merodiploids: (ii) they occurred in or very close to the flaI gene: and (iii) their expression required the presence of an intact flaI gene adjacent to the cfs mutation. Biochemical studies showed that the synthesis of at least two flagellar polypeptides, the hook subunit and an amber fragment of flagellin, were absent in strains that carried a cya mutation. Their synthesis was depressed in strains grown under conditions of catabolite repression. The presence of the cfs mutation restored the specific synthesis of these two polypeptides. We suggest that the formation of the flaI gene product is the step in flagellar synthesis that is catabolite sensitive and requires cAMP. We propose a regulatory function for the product of the flaI gene.

Adenylyl Cyclases↗