Characterization of bovine neutrophil beta2-adrenergic receptor function.

This study compares bovine leukocyte beta-adrenergic receptor densities to that of the rat, demonstrates for the first time a functional beta(2)-adrenergic receptor signaling pathway in steer neutrophils, and investigates the effect of an inflammatory stimulus on that signaling pathway. The beta(1)-/beta(2)-adrenergic antagonist ([3H])CGP-12177 demonstrated that rat lymphocyte specific binding-site density was highest, followed by steer and dairy cow lymphocytes, and lastly steer and dairy cow neutrophils. The beta(2)-adrenergic agonist terbutaline stimulated steer neutrophil adenosine 3,5-cyclic monophosphate (cAMP) production, an effect increased by inclusion of > or = 1 x 10(-8) M phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C. Both terbutaline and the nonselective phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) independently decreased steer neutrophil superoxide anion production in a concentration-dependent manner, with 1 x 10(-4) M IBMX enhancing both the potency and efficacy of the terbutaline effect (up to 74% reduction in superoxide anion production). Superoxide anion production was also reduced by the synthetic cAMP analog 8-bromo-cAMP, which increased the potency of the IBMX effect on superoxide anion production. Taken together, these data demonstrate the presence of a beta(2)-adrenergic receptor signaling pathway in bovine neutrophils much like that described in other animal species, as well as the potential for an inflammatory stimulus to alter its function.

Efficacy of fenbendazole in the treatment of experimental Giardia infection in dogs.

OBJECTIVE: To evaluate the efficacy of fenbendazole as a treatment for Giardia sp. ANIMALS: 10 male and 10 female commercial-source Beagles. PROCEDURE: The experiment was conducted in 2 replicates. Dogs considered free of Giardia infection on the basis of results of 3 consecutive negative fecal examinations were experimentally infected with approximately 1,000 Giardia cysts isolated from dog feces. After verification of infection, the dogs were allocated to 2 groups (treated and untreated) and were housed in separate rooms. Treated dogs received 50 mg of fenbendazole/kg of body weight, p.o., daily, for 3 days. After treatment on the third day, treated dogs were removed from their runs, shampooed, rinsed with disinfectant, and returned to disinfected runs. Fecal samples were collected from all dogs 12 times during the next 25 days. RESULTS: Giardia cysts were found in the feces of every untreated dog during all or part of the test period. Nine of 10 treated dogs did not have Giardia cysts in any fecal sample examined; the other dog had a positive result on a single sample in the third week after treatment. CONCLUSION AND CLINICAL RELEVANCE: Fenbendazole, at the nematocidal label dosage, is an effective drug for treatment of Giardia infection in dogs.