Avermectins and flea control: structure-activity relationships and the selection of selamectin for development as an endectocide for companion animals.

Evaluation of a wide range of avermectin derivatives for flea activity in an in vitro feeding screen using the cat flea, Ctenocephalides felis, revealed a narrow structure-activity relationship (SAR) with activity surprisingly associated with monosaccharides and especially their C-5-oximes. We discovered commercially exploitable flea activity in a single compound, selamectin 33, which also possessed the necessary antiparasitic spectrum and margin of safety for development as a broad-spectrum companion animal endectocide.

Delay in presentation of patients with acute stroke to hospital in Oxford.

We identified prospectively all patients (181 patients, 183 episodes) admitted to hospital in Oxford with acute stroke from 1 January to 30 June 1997. Data were inadequate in 30, leaving 153 episodes in 151 patients (63 men, 90 women). Structured interviews were used to investigate the timing of events preceding admission. Most strokes (91%) occurred at home, and 36% of patients were alone. After a median delay of 15 min, 56% called a GP (median 30 min response), 41% an ambulance (median 48 min to admission), and 3% went directly to A&E. Median time from hospital admission to doctor assessment was 69 min. Factors reducing delay were: initially calling an ambulance rather than a GP (p < 0.0001); onset not at home (p < 0.001); symptoms improving between onset and admission (p < 0.002); and altered consciousness (p < 0.002). The stroke was not recognized by 44% of patients, but no significant delay resulted. Overall, 31% were admitted within 3 h of onset, 46% within 6 h. Initial contact with the GP is a major determinant of delay. If acute therapies for stroke become available, GPs should be the primary targets for an educational initiative.