salicylates and tridodecylmethylammonium

Transport of the organic anion salicylate by the Malpighian tubules and gut of larval and adult fruit flies was studied using two salicylate-selective microelectrode methods. The first method combined the high selectivity of tridodecylmethylammonium-based electrodes for salicylate with the self-referencing ion-selective microelectrode technique for non-invasive spatial and temporal analysis of salicylate flux. Measurements with this technique revealed secretion of salicylate across the main and distal segments of the Malpighian tubule as well as the midgut, ileum and rectum. The second method used a salicylate-selective microelectrode to measure the concentration of salicylate in fluid droplets secreted by isolated Drosophila Malpighian tubules set up in a Ramsay secretion assay. Transepithelial salicylate flux was calculated as the product of fluid secretion rate and secreted fluid salicylate concentration. Measurements with this method revealed that salicylate transport was active and saturable; the kinetic parameters J(max) and K(t) were 2.72 pmol min(-1) tubule(-1) and 0.046 mmol l(-1), respectively. Measurements of transepithelial salicylate flux determined by both microelectrode methods were in good agreement. Transepithelial flux measurements measured by microelectrodes were also validated by comparing them with measurements of radiolabelled salicylate levels in secreted droplets. Salicylate concentrations in haemolymph samples were measured with salicylate-selective microelectrodes after injection of salicylate into the haemocoel or after insects were fed salicylate-rich diets. The rate of salicylate secretion by Malpighian tubules in vitro was sufficient to account for the measured rate of decline of salicylate concentration in the haemolymph in vivo.

Topics: Analysis of Variance; Animals; Biological Transport, Active; Digestive System; Drosophila melanogaster; Ion Transport; Kinetics; Malpighian Tubules; Microelectrodes; Quaternary Ammonium Compounds; Salicylates

During the pathogenesis of catheter-related urinary tract infection, bacteria attach to the catheter and migrate along a biofilm into the bladder. We studied the effect of coating silastic catheters with salicylic acid on bacterial and yeast adherence. An agar roll technique, bioluminescent assay, and radiolabeling study all produced consistent results. There was a dose related inhibition of adherence with Pseudomonas aeruginosa, Enterobacter aerogenes, Klebsiella pneumoniae, Candida albicans, and Enterococcus faecalis. Inhibition of over 90% was noted with Enterobacter and Pseudomonas. Similar results were obtained in broth and synthetic urine. A dose related reduction in adherence was seen with all gram-negative rods and yeast as measured by a radiolabeling assay. TDMAC was used to bind the salicylic acid to the catheters with > 95% inhibition of the gram-negative rods. These studies suggest the potential role of coating catheters with salicylic acid to reduce bacterial adherence and urinary tract infection.

Topics: Bacterial Adhesion; Candida albicans; Catheterization; Cell Adhesion; Enterobacter; Enterococcus faecalis; Klebsiella pneumoniae; Leucine; Luminescent Measurements; Pseudomonas aeruginosa; Quaternary Ammonium Compounds; Salicylates; Salicylic Acid; Silicone Elastomers; Silicones