Atraumatic loop electrodes for electroretinography

A simple method is described for producing inexpensive, atraumatic electrodes for electroretinography. Scleral contact is obtained by a loop of ultra-lightweight stainless steel wire placed between the eye and lower lid. Recordings obtained by this method in animals are equal to those recorded with needle electrodes, and the expense and complex construction of contact lens electrodes of varying sizes is avoided. Sample recordings made with loop and needle electrodes from the same ophthalmologically normal dog are presented.     

The fungitoxicity of substituted 2-phenylbenzofurans

Thirty-seven 2-phenylbenzofurans, variously substituted in the homocyclic rings, were synthesised and assessed for antifungal activity in laboratory tests. High activity was shown only by compounds containing a hydroxy group, though amino compounds were also fungitoxic but at a lower level. Possible mechanisms by which these substitutions impart fungitoxicity are discussed with particular reference to the partitioning properties of the molecule.     

Identification of canine T-lymphocyte subsets with monoclonal antibodies.

A panel of five murine monoclonal antibodies to canine T-lymphocytes were produced. Antibodies 4.78, 12.125 and 8.358 reacted with approximately 18%, 39% and 60% peripheral blood lymphocytes, respectively. Two color flow cytometric analysis showed that lymphocytes expressing 1.140, 4.78, 8.53 and 12.125 were subsets of lymphocytes expressing 8.358. The lymphocytes expressing 8.358 were negative for surface immunoglobulin. The subsets defined by 1.140, 4.78 or 8.53, 12.125 were mutually exclusive and together account for most cells expressing 8.358 in the peripheral blood, spleen, and lymph node. In the thymus, approximately 47% cells were positive for both 1.140/4.78 and 8.53/12.125. SDS-PAGE analysis of radiolabelled thymus cell lysates demonstrated that antibodies 1.140 and 4.78 immunoprecipitated a 32,35 kd heterodimer under reducing conditions and 12.125 immunoprecipitated a single 56 kd chain under reducing and non-reducing conditions. Antibodies 8.53/12.125 and 1.140/4.78 react with canine lymphocyte populations that occur in proportions similar to lymphocytes expressing CD4 and CD8 like molecules in several primate and non-primate species. The molecules recognized by 12.125 and 1.140/4.78 were similar in size and subunit composition to human CD4 and CD8.     

Multiple drug resistance in Pasteurella multocida and Pasteurella haemolytica from cattle and swine.

The results of antimicrobial susceptibility testing on 262 strains of Pasteurella multocida and 141 strains of Pasteurella haemolytica isolated from cattle and swine from 1971 to 1974 were analyzed for patterns of resistance to streptomycin, penicillin, tetracycline, and chloramphenicol, using a modified Kirby-Bauer procedure. Resistance was recorded for 80.5% of the isolants of P multocida and 92.2% of those of P haemolytica. Resistance to streptomycin was most frequent, followed by resistance to penicillin and tetracycline. Most cultures of P multocida and P haemolytica were susceptible to chloramphenicol. There were 9 patterns of resistance with the aforementioned antibiotics. The combinations, streptomycin and penicillin and streptomycin and tetracycline, each accounted for approximately 10% of the resistance patterns of P multocida. Approximately half of the 14 isolants of P haemolytica were resistant to the combination of streptomycin, penicillin, and tetracycline. These observations underscore the need for antimicrobial susceptibility testing of clinical isolants of P multocida and P haemolytica.     

The hen's egg: Factors affecting shell splitting during boiling

Experiments are described from which it is concluded that the shell will split when an egg is boiled if thermal expansion of the egg's liquid or gaseous contents, which have a higher coefficient of expansion than the shell, is insufficiently relieved by escape through the membranes and pores. The probability of splitting was enhanced if the shell had low structural strength due to a pre‐existing crack or to large size, skew shape or low effective thickness; once these factors had been taken into account there was no significant effect of the shell's aspect ratio, colour, glossiness, roughness or degree of ridging, nor of the hen's age or a strain history of selection for egg production. The incidence of splitting depended also on storage time and temperature: it was very low in newly laid eggs; in eggs stored at room temperature it rose to a maximum at about 5 d, then fell and was again low after about 21 d; in eggs stored at — 2 °C the time‐scale was increased and the incidence of splitting was still high after 14 d storage. These effects are due to two changes occurring during storage: progressive reduction of permeability of the membranes and shell to the liquid contents of the egg, which impedes escape of the contents when they expand during cooking, and progressive increase in the size of the air space, which provides expansion space. Allowing refrigerated eggs to warm to room temperature before cooking and adding salt to the cooking water did not significantly affect the incidence of splitting; putting eggs into cold rather than boiling water did not reduce the incidence of splitting except when the air space was large, following prolonged storage at room temperature.

The belief, common among housewives, that shell splitting occurs more commonly now than in earlier decades may be well‐founded but, if so, the change is probably due to a combination of two practices that have been introduced to maintain interior egg quality but which coincidentally raise the probability of shell‐splitting during boiling: rapid distribution from hen to housewife and refrigerated storage. There is no evidence that shells are now thinner, that hens of modern, high‐production strains lay eggs with weaker shells or that white shells are weaker than brown ones.     

Lymphocyte populations in the synovial membranes of dogs with rheumatoid arthritis.

Lymphocyte populations in the synovial membranes of dogs with canine rheumatoid arthritis (CRA) were investigated by immunohistochemical staining techniques. T-lymphocytes were the predominant cell type distributed throughout the supporting layer of the synovial membranes. B-lymphocytes expressing IgG were seen far more commonly than those expressing either IgA or IgM. Synovial membrane biopsies from normal and osteoarthritic joints did not have the marked cellular infiltrates seen in joints with CRA. The synovial immunohistopathological features in dogs with CRA are similar to those seen in human rheumatoid arthritis.