Nitric oxide (NO) is generated from L-arginine by a family of enzymes called the NO synthases. Previous investigators have proposed that the expression of this inducible enzyme (iNOS) may account for the characteristic vasodilatation, oedema and impairment of get motility seen in active ulcerative colitis. Using a specific antibody to iNOS, we have investigated the distribution of this enzyme in colonic tissue from patients with histologically proven ulcerative colitis. Eight patients with ulcerative colitis expressed calcium-independent citrulline activity (9.96 +/- 2.34 pmol citrulline mg-1 protein min-1) and showed immunoreactivity to the iNOS antibody within the inflammatory infiltrate of the lamina propria, and also within the cytoplasm of the epithelial cells lining the colon. Five age-matched controls showed no calcium-independent citrulline activity (0.2 +/- 0.08 pmol citrulline mg-1 protein min-1) and no immunoreaction to the antibody. We conclude that this enzyme is present in colonic tissue including the epithelium from patients with active colitis. Inhibition of this enzyme may provide a novel therapeutic option for patients with active ulcerative colitis.

et al. 1977), as well as fibrosis of the thyroid and orbit; these associations suggest systemic rather than local mechanisms in its pathogenesis. Methysergide, hydrallazine, or related compounds are implicated in more than 10% of cases and the disease may abate on their withdrawal. Chemical and viral agents are known to cause vasculitis and could be responsible in the remaining cases. This evidence allows speculation that retroperitoneal fibrosis is initiated by an external agent stimulating formation or deposition of immune complexes in the walls of large vessels, the site being determined by complex size or local haemodynamic factors. The consequent vasculitis permits exudation of plasma rich in immune complexes which tracks in the retroperitoneal space, exciting a chronic inflammatory reaction. Obstruction of hollow organs by this inflammatory tissue will be reversible by steroids only before collagen has been laid down. The concept of retroperitoneal fibrosis beginning as a vasculitis has practical as well as theoretical implications; in those cases where steroids fail to reverse obstruction, or where it recurs following surgery, cytotoxic drugs given either singly or in combination may be of benefit. The rationale for combinations of cytotoxic drugs is that their proven benefit in the management of known lymphoproliferative disease, such as the leukaemias or Hodgkin's disease, may also apply to the connective tissue diseases which are putatively immunoproliferative. However the value of intensive immunosuppression is unproven and a controlled trial, which is nearing completion at this centre, is essential.

The effectiveness of the removal of an ellipse of central axillary skin in treating axillary hyperhidrosis has been assessed. In suitable subjects this simple operation would appear to be well worthwhile.

Summary In a survey of benign gastric ulceration conducted in the Hounslow Health District from 1981 to 1982, there was an annual incidence for this condition of 43.6 per 100,000 of the population older than 14 y, with a male:female ratio of 0.9:1. This incidence is comparable to that found in other surveys over the last 30 y, but the male:female ratio is lower than in the past. This reduction is accounted for by a rise in the peak age incidence for gastric ulcer, particularly in women, and a greater proportion of the total population in this higher age group being women. In spite of a large local Asian population, no gastric ulcers occurred in this ethnic group. Thirty-eight per cent of the patients presented with acute bleeding, and 44% of these bleeders gave a history of previous ingestion of non-steroidal anti-inflammatory drugs compared with only 14% of the non-bleeding group (P less than 0.015).