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Biomedical subjects

S Wilson

Publications and source records attributed to S Wilson.

At least 595 records · Page 33Linked to original sources

Characteristics of antimicrobial resistance of Escherichia coli from animals: relationship to veterinary and management uses of antimicrobial agents.

Five-hundred fifty-five (555) isolates of Escherichia coli were obtained from fecal specimens of a representative number of animals from five farms in the United States. Antibiotic exposure of the selected herds was determined by an epidemiological survey of these farms. The incidence of multiple resistance in the E. coli isolates was higher in herds exposed to continuous feeding of antimicrobial agents (84.8%) than in a herd not receiving antimicrobials (15.7%). The most common resistance configuration observed was the triple pattern of dihydrostreptomycin (DS), sulfonamide (SU), and tetracycline (TE). The second most frequent pattern consisted of four resistances: ampicillin (AM), DS, SU, and TE. The frequency of transfer factors was much higher in multiply resistant organisms from the herds exposed to antimicrobial medicaments. The E. coli isolates were relatively efficient in fostering and transferring heterologous resistance factors. AM resistance factors occurred more frequently in herds which were exposed to feed levels of penicillin (27.9%) than in those that were not (6.4%).

Animal Diseases↗

Repression of colony formation reversed by antiserum to mouse thymocytes.

Marrow cells derived from C57BL/6 mice form many fewer splenic colonies in irradiated C57BL/6 x C3H F1 hybrid recipients than in irradiated C57BL/6 recipients (repression of colony formation). This effect is reversed by treatment of the hybrid recipients with active antiserum to mouse thymocytes. The repression phenomenon cannot readily be explained in immunological terms; hence the effect of the antilymphocyte serum on this phenomenon may not result from immunosuppression in the usual sense.

Animals↗

Regulation of acetylcholinesterase in neuroblastoma cells.

The specific activity of mouse neuroblastoma acetylcholinesterase (EC 3.1.1.7) increased 25-fold when the rate of cell division was restricted. The results show that acetylcholinesterase activity is regulated in neuroblastoma cells and that the regulatory mechanism is inversely related to the rate of cell division. Under the same conditions the specific activity of catechol-O-methyl transferase (EC 2.1.1.6) did not change significantly.

Acetylcholinesterase↗