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Biomedical subjects

D Grey

Publications and source records attributed to D Grey.

23 records · Page 2Linked to original sources
PubMed1977

Sensitivity of Pseudomonas aeruginosa to sulphonamides and trimethoprim and the activity of the combination trimethoprim: sulphamethoxazole.

The activities of three sulphonamides and trimethoprim against strains of Pseudomonas aeruginosa have been studied. Sulphadiazine had most activity, sulphadimidine had little, and the activity of sulphamethoxazole was intermediate. According to their sensitivity to sulphamethoxazole, strains were divided into two groups: "highly resistant" (16%, MIC greater than 1000 microgram per ml) and "moderately resistant" (84%, MIC less than or equal to 1000 microgram per ml). The former were resistant on disk testing to Sulphatriad 300 microgram. Sulphamethoxazole and trimethoprim did not act in synergy against them. The moderately resistant strains were sensitive to Sulphatriad; trimethoprim and sulphamethoxazole showed marked synergy against them in agar-plate dilution tests. The concentrations of trimethoprim and sulphamethoxazole necessary for synergy lay for each drug within the range of concentrations at which they have been found in urine, and the ratio of their MICs when acting in synergy was similar to the ratio of their concentrations in urine. It is suggested that a disk containing trimethoprim and sulphamethoxazole in a ratio of 1 : 2 rather than 1 : 20 would be more appropriate when testing strains from urine for their sensitivity to co-trimoxazole.

Dose-Response Relationship, Drug↗
PubMed1977

Trimethoprim-resistant bacteria: cross-resistance patterns.

One hundred and eighty one strains (clinically isolated) of trimethoprim-resistant bacteria were tested for sensitivity to proguanil, pyrimethamine, methotrexate and methasquin. All these agents had less intrinsic antibacterial activity than trimethoprim, and there was marked cross-resistance between trimethoprim on the one hand and pyrimethamine and methasquin on the other. Methotrexate was of very low activity against Gram-negative bacilli, but was highly inhibitory for streptococci. Proguanil had approximately the same activity for all the organisms tested, and appears not to act as an anti-folate agent.

Aspartic Acid↗
PubMed1974

The influence of anaesthetics on the increase in the water permeability of the toad bladder induced by vasopressin.

1 Single lobes of the bladder of Bufo marinus were isolated and filled with, and suspended in, oxygenated Ringer solution. The fluid in contact with the outside (serosa) of the lobes had a total osmolarity of 225 m-osmol/litre, and that bathing the inside (mucosa) of 45 m-osmol/litre.2 Osmotic water flow from mucosa to serosa was measured by weighing the lobes every 30 minutes. It was negligible unless vasopressin was added to the serosal bath. Standard concentrations of either 1.25 or 6.25 mu/ml were used to render the bladder lobes permeable to water.3 The presence in the serosal medium of pentobarbitone or thiopentone in concentrations ranging from 0.25 to 2.5 mM, or of chloralose in concentrations ranging from 0.65 to 6.5 mM, diminished the increase in water permeability induced by vasopressin.4 The three anaesthetics exerted similar inhibitory effects on the action of vasopressin from the serosal and from the mucosal surface of the bladder.5 In the presence of a constant high concentration of anaesthetic, increasing the concentration of vasopressin over three orders of magnitude led to stepwise increases of osmotic water flow out of the lobes, although at every dose level the effect of vasopressin was depressed by the anaesthetic. However, it was not completely abolished even if the concentration of vasopressin was close to threshold.6 The increase in water permeability of the bladder induced by 3',5'-adenosine monophosphate (cyclic AMP) was also depressed by the three anaesthetics.7 Possible explanations of the findings are discussed.

Adenosine Monophosphate↗