Escherichia coli O157 incident associated with a farm open to members of the public.

Three children, one who lived on an open farm and two who visited the farm in school parties, developed Vero cytotoxin producing Escherichia coli (VTEC) O157 infection in 1997. All had been in direct contact with animals. All were admitted to hospital with diarrhoea and two developed the haemolytic uraemic syndrome, one of whom developed severe neurological impairment. E.coli O157 phage type 21 that produced Vero cytotoxin 2 were isolated from the three children and from a goat paddock and two cows at the farm. The isolates were indistinguishable by molecular typing. The farm closed voluntarily for six weeks while recommendations to reduce the exposure of visitors to faecal contamination and to improve hygiene procedures (especially handwashing) were implemented. More research is needed into all aspects of VTEC O157 on farms, including the natural history of carriage in animals, the organism prevalence and factors that affect infectivity to humans. Further consideration is needed about the role of open farms in zoonoses, and how open farms can be assisted in reducing risks for visitors. The public need to be educated about the risks and about their responsibilities, which include the need to wash hands thoroughly and to avoid hand to mouth contact when visiting farms.

A new monoclonal antibody to epithelial membrane antigen (EMA)-E29. A comparison of its immunocytochemical reactivity with polyclonal anti-EMA antibodies and with another monoclonal antibody, HMFG-2.

Two polyclonal rabbit antibodies to epithelial membrane antigen (EMA), two mouse monoclonal antibodies (E29 and HMFG-2), and a "cocktail" of these two monoclonals have been compared using an indirect immunoperoxidase technique. Sections from 25 tissues (17 malignant and 8 benign), were examined. The distribution of staining with each of these reagents was similar, but the polyclonal antibodies produced stronger staining in colorectal carcinomas and lactating breast, whereas staining with the monoclonal antibodies was stronger in non-neoplastic pleural mesothelium and in pulmonary alveolar cells. When the two monoclonals were mixed there was no increase in staining intensity. E29 gave a "cleaner" result than HMFG-2, with better discrimination between cells and stroma, and is highly suitable for routine diagnostic histopathology.

Histochemistry of epithelial metaplasia and dysplasia in human stomach and colorectum.

Histochemical techniques reveal the functional divergence of carcinomas of the gastrointestinal tract and their tissues of origin. The principal changes are either the impairment or loss of normal functions or the acquisition of new functions. The latter may be those of heterologous adult tissues (metaplasia) or foetal tissues. Dysplasia or intra-epithelial neoplasia is regarded as a selective precancerous lesion. One might predict the functional profiles of dysplasia to be intermediate between those of normal and carcinomatous tissues. This appears to be only partially true in that high grade dysplasia (amounting to carcinoma-in-situ) will show appropriate cancer-associated changes, whereas low grade dysplasia may be functionally identical to its normal counterpart. Paradoxically, it is possible to demonstrate cancer-associated changes in non-neoplastic lesions such as incomplete intestinal metaplasia of gastric mucosa and both metaplastic polyps and transitional mucosa of the colorectum. If a proportion of the changes occurring in the course of malignant transformation have a metaplastic basis, it is possible that these are caused by the same environmental agents which lead to benign metaplasias. Benign metaplastic lesions may signal the presence of a potentially carcinogenic microenvironment, whilst some, such as incomplete intestinal metaplasia, are regarded as precancerous.