Development of a quantitative method for evaluation of the electroencephalogram of rats by using radiotelemetry.

The objective of this study was to develop a method for recording the electroencephalogram (EEG) of rats by using radiotelemetry followed by automated analysis of the raw tracing by fast Fourier transformation (FFT). We surgically implanted four 4- to 5-month-old Wistar (Crl:(WI)BR) rats each with two epidural electrodes and an attached radiotransmitter (Physiotel Implant, model TA11CTA, Data Sciences International, Inc., St. Paul, Minn.). Raw EEG signals were routed to a digital storage oscilloscope (DataSys 7200, Gould Instrument Systems, Valley View, Ohio) with FFT and averaging capabilities. FFTs of raw signals were generated at baseline (predose) and after intraperitoneal dosing of the rats with atropine (30 min postdose; 6 mg/kg), caffeine (90 and 150 min postdose; 30 mg/kg), ketamine (15 and 30 min postdose; 50 mg/kg), and pentobarbarbital (60 and 90 min postdose; 40 mg/kg). For atropine, caffeine, and pentobarbital, the overall direction of the change in power across the spectrum (0 to 40 Hz) was the same as that reported previously. Relative peaks in power were consistent with those previous reports for atropine at < or =5 Hz and caffeine at approximately 7.5 Hz. Ketamine caused a shift in peak power from 5 to 10 Hz to < 5 Hz, as shown by other investigators. FFT analysis of EEG signals captured by radiotelemetry may provide a meaningful method for studying the CNS effect of novel compounds.

Efficacy of an inactivated FeLV vaccine compared to a recombinant FeLV vaccine in minimum age cats following virulent FeLV challenge.

The aim of the study was to determine the efficacy of an inactivated feline leukemia virus (FeLV) vaccine (Versifel(®) FeLV, Zoetis.) compared to a recombinant FeLV vaccine (Purevax(®) FeLV, Merial Animal Health) in young cats, exposed under laboratory conditions to a highly virulent challenge model. The study was designed to be consistent with the general immunogenicity requirements of the European Pharmacopoeia 6.0 Monograph 01/2008:1321-Feline Leukaemia Vaccine (Inactivated) with the exception that commercial-strength vaccines were assessed. Fifty seronegative cats (8-9 weeks old) were vaccinated subcutaneously on two occasions, three weeks apart, with either placebo (treatment group T01), Versifel FeLV Vaccine (treatment group T02), or Purevax FeLV Vaccine (treatment group T03) according to the manufacturer's directions. Cats were challenged three weeks after the second vaccination with a virulent FeLV isolate (61E strain). Persistent FeLV antigenemia was determined from 3 to 15 weeks postchallenge. Bone marrow samples were tested for the presence of FeLV proviral DNA to determine FeLV latent infection. At week 15 after challenge with the virulent FeLV 61E strain, the Versifel FeLV Vaccine conferred 89.5% protection against FeLV persistent antigenemia and 94.7% protection against FeLV proviral DNA integration in bone marrow cells. In comparison, the Purevax FeLV Vaccine conferred 20% protection against FeLV persistent antigenemia and 35% protection against FeLV proviral DNA integration in bone marrow cells following challenge. The data from this study show that the Versifel FeLV Vaccine was efficacious in preventing both FeLV persistent p27 antigenemia and FeLV proviral DNA integration in bone marrow cells of cats challenged with this particular challenge model under laboratory conditions and provided better protection than Purevax FeLV in this experimental challenge model with highly virulent FeLV.