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A polymyxin-cloth enzyme immunoassay (polymyxin-CEIA) was developed for the detection of the foodborne pathogenEscherichia coliO157. This simple assay utilized inexpensive polymyxin-coated polyester cloth as an adsorbent forE. colilipopolysaccharide (LPS) antigens present in test samples such as enrichment cultures of ground beef. Captured LPS was immunoenzymatically detected using commercially available anti-O157 polyclonal antibodies. The assay was sensitive and highly specific for strains bearing the O157 and related antigens, and permitted the detection ofc. 1–10 cfus spiked into ground beef samples after a brief enrichment in double modified trypticase soy broth. We suggest that the polymyxin-CEIA will provide a simple, rapid and inexpensive screening method forE. coliO157 in ground beef.

Seven Vasculour D grafts, five Gore-Tex grafts and seven Solco-graft, 8 mm by 30 cm, implanted as thoraco-abdominal bypasses in dogs. Sixteen were retrieve at two months. Graft size was assessed angiographically in representative dogs of each group prior to sacrifice. Initial examination of the retrieved specimens revealed pannus extensions at both anastomoses on all graft types, and a variable midgraft appearance from smooth and glistening to partially thrombus coated. Histological assessment of graft segments revealed widely differing healing responses on the three graft types. Tissue attachment to both graft surfaces and varying degrees of tissue incorporation were observed in the Vasculour D and Gore-Tex prostheses. The Solco-graft specimens showed no evidence of tissue incorporation on the wall at two months. Tissue on the graft surfaces remains loosely attached and unicorporated. Pannus extensions were thickest on the Solco-graft. Variably thin fibrin is scattered over the luminal surface of the three graft types. Vascularization of the wall particularly the internal capsulae was noted in the Vasculour D grafts. Although biological responses in the dog are difficult to extrapolate to man, the types of comparison testing allowed by the use of the thoraco-abdominal by-pass procedure can provide valuable information of degree of dilation, relative tissue attachment, tissue incorporation into various types of prostheses and kidney infarcts study. The greatest value of the thoraco-abdominal by-pass lies in graft sizes and length without special regard for patency: assessment of graft size post-implantation and structural changes is then made possible.

Recombinants of oncogenic and nononcogenic avian leukosis viruses were tested for their oncogenic potential in chickens. The results indicate that at least two regions of the viral genome determine the oncogenic potential of these viruses. The first region contains sequences that control viral mRNA synthesis. These sequences determine the potential of a virus to induce a low incidence of lymphomas, carcinomas, chondrosarcomas, fibrosarcomas, and osteopetrosis. The second region lies outside the sequences that control viral mRNAs synthesis. These sequences determine the ability of a virus to induce a high incidence of lymphomas or osteopetrosis.

A series of recombinants between Rous-associated virus type 0 (RAV-0), RAV-1, and a replication-competent avian leukosis virus vector (RCAN) have been tested for disease potential in day-old inoculated K28 chicks. RAV-0 is a benign virus, whereas RAV-1 and RCAN induce lymphoma and a low incidence of a variety of other neoplasms. The results of the oncogenicity tests indicate that (i) the long terminal repeat regions of RAV-1 and RCAN play a major role in disease potential, (ii) subgroup A envelope glycoproteins are associated with a two- to fourfold higher incidence of lymphoma than subgroup E glycoproteins, and (iii) certain combinations of 5' viral and env sequences cause osteopetrosis in a highly context-dependent manner. Long terminal repeat and env sequences appeared to influence lymphomogenic potential by determining the extent of bursal infection within the first 2 to 3 weeks of life. This would suggest that bursal but not postbursal stem cells are targets for avian leukosis virus-induced lymphomogenesis. The induction of neutralizing antibody had no obvious influence on the incidence of lymphoma.