Comparison of a modification of the ellman method to measure carbamate inhibition of acetylcholinesterase in plasma, erythrocytes and brain tissues in sprague dawley rats using two analytical systems.

Inhibition of the enzyme acetylcholinesterase (AChE) using a carbamate compound was measured in 30 Crl: CD(R)BR Sprague Dawley rats. Erythrocyte, plasma, and brain tissues were analyzed using modifications of the Ellman technique(1) on two different clinical chemistry analyzers. Both EDTA and heparin anticoagulated whole blood were used for the erythrocyte and plasma tests. Results demonstrated similar inhibition of the enzyme in all three tissues between the control and dosed groups using the two technique modifications and instruments. Final inhibition of plasma and erythrocyte AChE for the control vs. treated groups (males and females combined) was 89.5% vs. 82% and 39% vs. 38% for the Technicon AutoAnalyzertrade mark vs. the Boehringer Mannheim Hitachitrade mark 704, respectively. Inhibition of the left and right brain segments for the control vs. treated groups (males and females combined) was 35% vs. 39% and 33.2% vs. 29% for the Technicon and the Hitachi, respectively. All inhibitions were significant at the 5% level using two tailed Dunnett's t-Test. Hemolysates prepared from EDTA whole blood packed cells gave more consistent results on the Hitachi 704.

The effect of haemolysis on certain canine serum chemistry parameters.

Haemolysis has been known to cause artefacts in certain canine serum chemistry parameters. These parameters are often used by researchers to detect toxicity in certain studies; haemolysis, therefore, can make serum chemistry interpretation very difficult. In order to determine whether a relationship existed between the level of haemolysis and certain canine serum chemistry parameters, haemolysis was artificially induced by adding a haemolysate of known haemoglobin concentration to serum specimens. A routine clinical chemistry profile was performed on each specimen. Statistical analyses were performed on the results to examine the relationship between level of haemolysis and serum chemistry results. Interpretation of serum chemistry results of haemolysed canine sera paralleled, in most cases, human historical data.

Subchronic inhalation toxicity of benzene in rats and mice.

A subchronic inhalation toxicity study of benzene was conducted in CD-1 mice and Sprague-Dawley rats. Four groups of animals consisting of 150 mice and 50 rats/sex each were exposed to concentrations of 1, 10, 30, and 300 ppm benzene vapor, 6 hours/day, 5 days/week, for 13 weeks. Additional groups of mice and rats, of equal size, were exposed under similar conditions to filtered air and served as control groups. Thirty mice and 10 rats/sex in each group were sacrificed after 7, 14, 28, 56, and 91 days of treatment. Criteria used to evaluate exposure-related effects included behavior, body weights, organ weights, clinical pathology, gross pathology, and histopathology. Fifty animals per sex of each species were exposed concurrently for cytogenetic studies. In addition, blood serum was obtained for immunological assays. The results of these two studies will be reported separately. No consistent exposure-related trends were seen in the clinical observations and body weight data. Exposure-related clinical pathology changes were seen in the high-level (300 ppm) animals of both species. In the mice, these changes included decreases in hematocrit, total hemoglobin, erythrocyte count, leukocyte count, platelet count, myeloid/erythroid ratios, and percentage of lymphocytes. Mean cell volume, mean cell hemoglobin, glycerol lysis time, and the incidence and severity of red cell morphologic changes were increased in the mice. In the rats, decreased lymphocyte counts and a relative increase in neutrophil percentages were the only exposure-related clinical pathology alterations. Histopathologic changes were present in the thymus, bone marrow, lymph nodes, spleen, ovaries, and testes of mice exposed to 300 ppm and in most cases the incidence and severity of the lesions were greater in the males. These changes in the testes and ovaries at 300 ppm were also seen at lower concentrations, but they were of doubtful biological significance. In rats, the only exposure-related lesion consisted of slightly decreased femoral marrow cellularity in the animals exposed to 300 ppm.

Studies of the Pelger-Huët anomaly in foxhounds.

An inbred family of foxhounds with four members expressing the Pelger-Huët (P-H) anomaly is described. The disease-free status of all P-H affected dogs suggests a benign disorder, although review of breeding records indicated a lower percentage of pups weaned (63%) by P-H females compared with the percentage of pups weaned (81%) by outcrossed females throughout the foxhound colony. Light-microscopic examination of blood films from affected dogs revealed 50--67% neutrophils with round, oval, or bean-shaped nuclei and rarely (0.5%) segmented nuclei. Neutrophils examined by electron microscopy showed the nuclei to have a fine nuclear cleft and condensed chromatin and the cytoplasm to have mature heterochromatic granulation. Local P-H neutrophil mobilization through a standard skin abrasion into a chamber containing autologous serum was impaired at all time periods evaluated (1, 4, 8, and 24 hours) compared with the neutrophil mobilization by normal dogs. Antibody response to sheep erythrocyte immunization was also impaired. In vitro reactivity of normal and P-H lymphocytes stimulated by pokeweed mitogen was depressed when lymphocytes were cultured in plasma from a P-H dog but not when cultured in plasma from a normal dog. Vigorous blastogenic responses to phytohemagglutinin by normal and P-H lymphocytes cultured in P-H or normal plasma suggest the presence of a factor(s) in the P-H plasma which interferes with B-lymphocyte reactivity.

A comparison of polychromasia and reticulocyte counts in assessing erythrocytic regenerative response in the cat.

Three staining techniques were evaluated for use in assessing the erythrocytic regenerative responses in the cat. Using new methylene blue as a vital stain, the aggregate reticulocyte count closely corresponded to the reticulocyte count on air-dried smears stained with new methylene blue and to the polychromatophilic erythrocyte count on Wright's stained smears.