Effect of levamisole on lymphocyte blastogenesis and neutrophil function in dexamethasone-treated cattle

Levamisole was evaluated at 6 dose levels for its ability to prevent the dexamethasone-induced suppression of in vitro lymphocyte blastogenesis or neutrophil function in cattle. Dexamethasone (0.4 mg/kg of body weight, IM) and levamisole hydrochloride (0.5, 1.0, 2.0, 4.0, or 8.0 mg/kg orally) were administered to groups of 4 cattle daily for 3 days. Another group of 4 cattle were given the 3-day dexamethasone treatment and 6.0 mg/kg of levamisole (the recommended anthelmintic dose) was given only once on the 1st day that dexamethasone was given. Results obtained from the dexamethasone-levamisole-treated cattle were compared with results obtained from cattle that were given only dexamethasone. Levamisole had no apparent consistent ability to enhance lymphocyte blastogenic responsiveness (to the mitogens phytohemagglutinin, concanavalin A, or pokeweed mitogen or in a 1-way mixed lymphocyte reaction) or to enhance neutrophil function (random migration, nitroblue tetrazolium reduction, iodination, or antibody-dependent cell-mediated cytotoxicity) in dexamethasone-treated cattle.     

Alterations in bovine lymphocyte function during the periparturient period

Lymphocytes from 8 Holstein heifers were evaluated during the periparturient period for mitogen-induced lymphocyte blastogenic responses. Phytohemagglutinin P- and concanavalin A-induced lymphocyte blastogenesis increased 2 and 3 weeks before parturition, respectively. However, by the first week after parturition, lymphocyte blastogenesis was markedly impaired.     

Portosystemic shunts in cats: seven cases (1976-1984)

Congenital portosystemic venous shunt causing signs of hepatic encephalopathy was diagnosed in 7 cats. The left gastric vein served as the shunt in four of these. Increases in blood ammonia and postprandial serum bile acids were the most consistent serum biochemical abnormalities. Excessive variation in red blood cell shape was a common but nonspecific hematologic finding. The jejunal-mesenteric venous injection of contrast material was the preferred method of portography to diagnose portosystemic shunts. Two cats were treated successfully by partial surgical occlusion of their shunts.     

Evaluation of auditory evoked potentials to predict depth of anaesthesia during fentanyl/fluanisone−midazolam anaesthesia in rats

Objectives To assess a method for monitoring depth of anaesthesia using components of middle latency auditory evoked potential (AEP) waveforms during anaesthesia with fentanyl/fluanisone and midazolam. Study design Prospective observational study. Animals Five female Wistar rats weighing between 210 and 250 g. Methods Implanted electrodes were used to record AEPs in animals receiving five doses of anaesthetic. Recordings were made at 5 minutes post‐injection (deep anaesthesia; no pedal withdrawal response, PWR) and then at 25 minutes (light anaesthesia; strong PWR). Responses showed five characteristic peaks occurring at 11, 14, 23, 42 and 68 ms that were measured for latency of occurrence and peak amplitude. Results Auditory evoked potential peaks P14, N23 and P42 were increased significantly in latency with successive anaesthetic injections [avg. F(1,4) = 12.53, p < 0.001; avg. F(1,4) = 10.6, p < 0.001; avg. F(1,4) = 3.9, p = 0.02, respectively]. Peak N23 showed a significant reduction in latency during the 20 minute recovery period following both the first and second anaesthetic injections (t(3) = 7.52, p = 0.005; t(4) = 5.17, p = 0.007, respectively). Peak P42 occurred significantly earlier 20 minutes following the second anaesthetic injection (t(4) = 4.75, p = 0.009). The mean overall depth of anaesthesia assessed using PWR scores was significantly correlated with the mean latency of peak N23, such that as the strength of PWR increased, N23 occurred significantly earlier (r = ?0.99, p = 0.01). The amplitude difference between peaks N23 and P42 increased after the second and third drug administrations [avg. F(1,4) = 10.65, p = 0.031 and avg. F(1,4) = 11.24, p = 0.028, respectively]. Conclusion The characteristics of these peaks, and in particular latency of peak N23, may provide a useful tool for assessing depth of anaesthesia produced by this, and possibly other anaesthetic agents.     

Gastric rupture in horses: a review of 54 cases

The historical, clinical, laboratory, surgical and necropsy findings in 54 cases of gastric rupture in horses are described. Eleven per cent of the deaths of horses undergoing exploratory coeliotomy for colic during the period of the study were a result of gastric rupture. Comparison with all horses which had exploratory coeliotomies for colic over an eight year period did not show that horses with gastric rupture were different from these reference horses regarding age, breed or season. There were fewer stallions than expected in the gastric rupture group. Horses with histories of both acute and chronic (more than 36 h) colic were susceptible to gastric rupture. Primary and idiopathic causes of gastric dilation and rupture accounted for about one-third of the horses. All but one of these cases resulting from secondary causes fell into three aetiologically-related groups: obstructive, peritoneal and enteric, with approximately equal numbers of horses in each group. Most of the ruptures occurred along the greater curvature of the stomach. At least six horses ruptured their stomachs postoperatively in the presence of an indwelling nasogastric tube. The presence or absence of gastric reflux following nasogastric intubation was not a reliable indicator, on its own, of gastric dilation. Horses that later died from gastric rupture had markedly elevated heart rate, hypochloraemia, peritoneal exudative effusion (particularly with evidence of sepsis), pre- and/or postoperative gastric reflux and small or large intestinal disease. However, no distinctive feature of these horses was shown to place them at risk of gastric rupture.     

A model of animal-human brucellosis transmission in Mongolia

We developed a dynamic model of livestock-to-human brucellosis transmission in Mongolia. The compartmental model considers transmission within sheep and cattle populations and the transmission to humans as additive components. The model was fitted to demographic and seroprevalence data (Rose Bengal test) from livestock and annually reported new human brucellosis cases in Mongolia for 1991-1999 prior to the onset of a mass livestock-vaccination campaign (S19 Brucella abortus for cattle and Rev 1 Brucella melitensis for sheep and goat). The vaccination effect was fitted to livestock- and human-brucellosis data from the first 3 years of the vaccination campaign (2000-2002). Parameters were optimized on the basis of the goodness-of-fit (assessed by the deviance). The simultaneously fitted sheep-human and cattle-human contact rates show that 90% of human brucellosis was small-ruminant derived. Average effective reproductive ratios for the year 1999 were 1.2 for sheep and 1.7 for cattle.     

Equine cell-mediated immune response to Rhodococcus (Corynebacterium) equi

A lymphocyte blastogenic assay was developed to serve as an in vitro correlate of cell-mediated immunity to Rhodococcus (Corynebacterium) equi (R equi) in the equine species. Lymphocytes obtained from a group of experimental ponies showed no response in cell culture to R equi heat extract or lysozyme extract antigens. Ponies were assigned to groups for experimental inoculation. Three ponies were inoculated subcutaneously with live R equi, 3 were given live R equi by intranasal and intratracheal routes, and 4 ponies were left untreated. Lymphocytes from all inoculated ponies had a mitogenic response to R equi antigens in lymphocyte blastogenic assays performed between the 7th and 40th days after inoculation. Lymphocytes from noninoculated control ponies remained unresponsive to R equi antigens. Delayed-type hypersensitivity reactions developed in all experimentally exposed ponies after intradermal administration of the R equi antigen preparations. In a 2nd phase of experimentation, blastogenesis assays were performed on lymphocytes from horses in herds with endemic R equi infections. Results indicated that many of the animals had significant (stimulation index greater than 2) cell-mediated responses to the bacterium, but there was no distinct correlation between the immune response and clinical history. These data indicated that cell-mediated immunity is involved in the interaction of the equine immune system with R equi.     

Effects of in vitro and in vivo administration of recombinant bovine interferon-gamma on bovine neutrophil responses to Brucella abortus

The effects of in vitro and in vivo treatment of bovine polymorphonuclear leukocytes with recombinant bovine interferon-gamma on in vitro bovine polymorphonuclear leukocyte functions and the survival of Brucella abortus were determined. Activation of neutrophils in vitro with interferon-gamma resulted in enhanced production of O2- and myelopeoroxidase-H2O2-halide activity by neutrophils in the presence of B. abortus. The improved iodination responses were correlated with an enhanced ability to perform iodination in the presence of 5'-guanosine monophosphate and adenine which have previously been shown to contribute to inhibition of neutrophil myeloperoxidase-H2O2-halide activity by B. abortus. The ability of opsonized B. abortus to survive in the presence of neutrophils activated in vitro or in vivo was partially decreased by approximately 10% of control when compared to survival rates within control phagocytes. These results suggest that activation of neutrophils with recombinant interferon-gamma partially enhances their oxidative metabolic responses, resulting in a slightly enhanced ability to kill virulent B. abortus.     

Alterations in bovine neutrophil function during the periparturient period

Neutrophils from 8 Holstein heifers were evaluated for function during the periparturient period. Random migration, ingestion of bacteria, superoxide anion production, native (nonenhanced) chemiluminescence, iodination, and antibody-dependent, cell-mediated cytotoxicity by neutrophils were determined. Foremilk samples were evaluated for bacteria. Significant (P less than 0.05) increases in random migration of neutrophils, iodination, and chemiluminescence were evident 2 weeks before parturition and then decreased dramatically by the first week after parturition. These impairments of neutrophil function after parturition may be manifested as a severe cumulative deficit in the native defenses afforded by the neutrophil.