Assay of suxamethonium and laudexium on the frog rectus abdominis.

Suxamethonium, like acetylcholine, causes contracture of the isolated rectus abdominis muscle of the frog, whereas laudexium antagonizes this effect. These actions may be used to assay both drugs with reasonable speed and fiducial limits, provided that changes in responsiveness of the preparation during the course of assay are met by suitable design and analysis. Small quantities of suxamethonium and laudexium may be assayed in certain body fluids.

Local action of some antibacterial substances against Corynebacterium ovis in guinea-pig skin.

When a suspension of living Corynebacterium ovis was injected intradermally in guinea-pigs, a lesion of roughly circular outline developed within 24 hr. Lesions of smaller diameter arose if benzylpenicillin, dequalinium, hedaquinium, cetrimide, or oxytetracycline were injected at the identical site, either before, with, or after C. ovis.

Detection and measurement of antagonism to folic acid.

Methods of testing competitive antagonism in bacterial systems are considered and evaluated with particular reference to antifolic acids. Four antifolic acids-pteridine O/129, methotrexate, CB2295 and CB2335-were examined for competitiveness and potency in three test systems-Leuc. citrovorum and folinic acid, Str.