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Biomedical subjects

J Demonty

Publications and source records attributed to J Demonty.

At least 55 records · Page 3Linked to original sources
PubMed1982

Release of endotoxic lipopolysaccharide by sensitive strains of Escherichia coli submitted to the bactericidal action of human serum.

Free endotoxin was assayed in filtered samples of E. coli suspensions submitted to the bactericidal and bacteriolytic action of 10% human serum. The Limulus amoebocyte lysate test, a passive hemolysis inhibition assay based on O antigenic specificity and the determination of 3-OH-myristic acid by mass spectrometry were used as assay methods differing from one another with regard to the part of the endotoxin macromolecule involved in the reaction. The biological activity of endotoxin was assessed in a mouse lethality test. The bactericidal and bacteriolytic action of human serum on sensitive strains of E. coli released quantities of endotoxic lipopolysaccharide (LPS) amounting to 3,000-12,000 ng/ml, for an inoculum of 1--3 x 10(8) colony-forming units. The material thus appearing in the medium was shown to react with the Limulus amoebocyte lysate, to be lethal for actinomycin D-sensitized mice and to bear O antigen, as well as 3-OH-myristic acid, a marker of lipid A. Samples of serum depleted of lysozyme by adsorption onto bentonite, and displaying a strictly bactericidal effect, released approximately 80% of the quantity of LPS appearing in the medium in a control experiment performed with untreated serum. The LPS release is therefore mainly linked to the bactericidal effect of antibody and complement. The amount of LPS released depended on the concentration of divalent cations in the medium, being reduced by an increase in the concentration of calcium and magnesium beyond the values optimal for complement activity. This effect was already observed for an increase in the concentration of divalent cations too low to alter the bactericidal or bacteriolytic effects. The significance of the release of endotoxin by complement dependent bactericidal reactions occurring in vivo is discussed.

Antibodies, Bacterial↗
PubMedDate not supplied

A study of the transplacental transfer and the mammary excretion of cefoxitin in humans.

Cefoxitin is a new semisynthetic cephamycin derivative with broad bactericidal activities. In order to determine the extent of the transplacental transfer of cefoxitin, 35 pregnant women received 1 Gm cefoxitin intramuscularly 15 to 180 minutes before normal or Caesarean delivery. Cefoxitin was measured microbiologically in maternal blood (multiple-time samples), umbilical blood (one-time sample), and amniotic fluid in the cases of Caesarean sections. The mammary excretion of cefoxitin injected at the same dose was investigated by measuring cefoxitin in the milk of 16 nursing mothers. In the maternal blood, a peak plasma level of approximately 25 microgram/ml was reached 30 minutes after the 1-Gm intramuscular injection. A clear-cut passage of cefoxitin in the umbilical cord blood was demonstrated. In the fetal blood, a peak level of 15 microgram/ml was obtained 45 minutes after the injection. No cefoxitin was detectable in any of the milk samples from 30 minutes to 24 hours after the 1-Gm intramuscular injection.

Adolescent↗