Effects of sample handling methods on substance P concentrations and immunoreactivity in bovine blood samples.

Objective: To determine the effects of protease inhibitors and holding times and temperatures before processing on the stability of substance P in bovine blood samples.

Samples: Blood samples obtained from a healthy 6-month-old calf.

Procedures: Blood samples were dispensed into tubes containing exogenous substance P and 1 of 6 degradative enzyme inhibitor treatments: heparin, EDTA, EDTA with 1 of 2 concentrations of aprotinin, or EDTA with 1 of 2 concentrations of a commercially available protease inhibitor cocktail.

Effects of two simulated oxytetracycline dosing regimens on horizontal transfer of antimicrobial resistance plasmids in an in vitro pharmacodynamic model.

Objective: To evaluate the impact of oxytetracycline exposure on horizontal transfer of an antimicrobial resistance plasmid.

Sample: Populations of Salmonella enterica subsp enterica serovar Typhimurium and Escherichia coli.

Procedures: Mixed populations of plasmid donor (Salmonella Typhimurium) and recipient (E coli) bacteria were assigned to 1 of 2 simulated oxytetracycline dosing regimens (high peak concentration-short elimination half-life [HC-SHL] or low peak concentration-long elimination half-life [LC-LHL]) or served as untreated control replicates.