A comparison of the mitogenic effects of a phorbol ester on lymphocytes from bovine spleen,lymph node and peripheral bloodComparaison des effets mitogenes d'un ester de phorbol sur des lymphocytes bovins de rate,de ganglions lymphatiques et de sang peripherique

A comparison of the mitogenic effects of a phorbol ester on lymphocytes from bovine spleen, lymph node and peripheral blood.Bovine lymphocytes from three tissues, lymph node, spleen and peripheral blood were compared for their mitogenic responses to 12-O-tetraecanoylphorbol-13-acetate (TPA), a phorbol ester tumor promoter. TPA alone was found to be either not mitogenic or caused only a weak response when compared with the mitogenic lectin phytohemagglutinin (PHA). Of the three lymphocyte preparations, blood cells showed the greatest proliferative response to TPA. However, all three, lymph node, blood and spleen cells, showed a co-mitogenic response to TPA. That is, TPA synergistically enhanced DNA synthesis in cells stimulated with a suboptimal concentration of PHA.     

In vitro and in vivo effects of chlorpyrifos and cypermethrin on blood cholinesterases in sheep

The combination of the organophosphate (OP) chlorpyrifos (CPF) and the pyrethroid cypermethrin (CPM) is commonly marketed as pour‐on formulations for the control of sheep lice, ked, and blowflies. CPF irreversibly inhibits acetylcholinesterases (AChE), while pyrethroids are not AChE inhibitors. However, combinations of pyrethroids with OPs showed a highly synergistic effect on AChE inhibition. Thus, the aim of the current work was to evaluate in vitro and in vivo the inhibitory potency of both pesticides, alone and in combination with AChE and butyrylcholinesterase (BChE) activities in sheep blood. In vitro, IC50 values were similar after CPF or CPF plus CPM incubations. The pour‐on coadministration of recommended doses of CPF and CPM did not cause a significant inhibition of AChE and BChE in sheep blood. Only slight percentages of inhibition of their catalytic activities were observed when both drugs were given at 4‐fold higher dose rates. The lower systemic availability of topical administration of OPs in sheep may help to explain the lower degree of inhibition of blood AChE and BChE in vivo. The results emerged from this research are a further contribution to the knowledge of the risks of implementing higher dosage regimens of OPs‐containing antiparasitic formulations.     

Comparison of the ability of feline calicivirus (FCV) vaccines to neutralise a panel of current UK FCV isolates

Feline calicivirus (FCV) comprises a large number of strains which are related antigenically to varying degrees. The antigenic variability creates problems for choosing antigens to include in vaccines. Historically, these have been selected for use based on their cross-reactivity with a high proportion of field strains. However, it is important to determine the current level of cross-reactivity of vaccines and whether or not this may be decreasing owing to widespread vaccine use. In this in vitro study, we have compared the ability of antisera to two vaccine viruses (FCV strain F9 and FCV strain 255) to neutralise a panel of 40 recent UK field isolates. These 40 isolates were obtained by randomised, cross-sectional sampling of veterinary practices in different geographical regions of the UK so as to ensure they were representative of viruses circulating in the veterinary-visiting population of cats in the UK. Virus neutralisation assays showed that both vaccine strains are still broadly cross-reactive, with F9 antiserum neutralising 87.5% and 255 antiserum 75% of isolates tested with antiserum dilutions of 1 in 2 or greater. However, when antibody units were used, in order to take account of differences in homologous titres between antisera, fewer isolates were neutralised, with F9 antiserum showing a slightly higher proportion of isolates neutralised than 255. Multivariable analysis of the sample population of 1206 cats from which the 40 isolates were derived found that vaccinated cats were at a decreased risk of being positive for FCV, whereas cats from households with more than one cat, and cats with mouth ulcers were at increased risk. In addition as cats became older their risk of shedding FCV decreased.     

Fibrosarcoma adjacent to the site of microchip implantation in a cat

A 14-year-old spayed female domestic shorthair cat presented with an interscapular mass. A computed tomography scan, biopsy, and histological examination revealed a fibrosarcoma adjacent to a pet identification microchip. Because the cat was previously vaccinated at this site, it is not possible to establish definitive causation of the fibrosarcoma, but this is the first report of a tumor in the vicinity of a microchip in a cat. Microchip-associated tumors have been reported in rodents and dogs. Veterinarians should be aware that because inflammation may predispose felines to tumor formation, separation and observation of vaccination and implantation sites are indicated. Adherence to American Association of Feline Practitioners (AAFP) vaccination guidelines and monitoring of microchip implantation sites are recommended.