An investigation into the effect of ischaemia and pressure on irritant inflammation

Reports of chemical burns beneath tourniquets during orthopaedic procedures led us to explore the irritant effects produced by the skin antiseptics used during such procedures. A sphygmomanometer and tourniquet, at a pressure of 200 mmHg for 30 min, was used to created pressure and ischaemia which were then examined separately for their respective effects on irritant inflammation in normal subjects and those with atopic eczema. As no inflammation could be demonstrated with the antiseptics, we subsequently used the known irritant chemical anthralin to examine the effect of ischaemia with and without pressure. Site-related variation in anthralin-induced inflammation was observed but there was no demonstrable effect of either pressure or ischaemia on the inflammatory response. Therefore, as we are unable to show a relationship between ischaemia with or without pressure and irritant inflammation, we conclude that burns under tourniquets are likely to be idiosyncratic reactions and their further investigation requires examination of the individuals affected.

A non-invasive micronucleus assay in the rat liver

The potent rat-liver mitogen 4-acetylaminofluorene (4AAF) is shown here to provide an effective replacement for the surgical procedure of 2/3 partial hepatectomy (2/3PH) in the in vivo rat-liver micronucleus assay described by Tates and his colleagues. This protocol modification enables the assay to be conducted on a routine basis. Control observations for both 2/3PH and 4AAF-treated rats are presented, together with evidence indicating 4AAF itself to be without activity in the assay, irrespective of the mitogenic stimulus. The activities of the rat carcinogens DMN, 2AAF, DMH and 6BT, and of the non-carcinogens 4AAF and 4N are demonstrated. Recommendations for the conduct of the modified assay are made.