Pharmacokinetics of pentobarbital and thiamylal as combined anesthetics in sheep

This study was performed to investigate the possible mechanisms underlying prolongation of anesthesia times in sheep caused by the sequential administration of thiamylal and pentobarbital. Sodium thiamylal was injected as an intravenous bolus dose (13.2 mg/kg) followed in 7 min by sodium pentobarbital (14.3 mg/kg) by the same route to seven sheep. Separate studies were conducted for each of the two drugs administered separately to the same animals at the same doses. Mean anesthesia times (to the return of the palpebral reflex) were 7.89 min (thiamylal), 5.39 min (pentobarbital) and 34.1 min (the sequential combination). The kinetic parameters Vd(area), Vd(ss), t 1/2 beta, and ClB for either drug were not affected by the other when given in combination. The t 1/2 alpha was shorter, and the Vc was smaller, for pentobarbital when administered with thiamylal, while there were no changes in thiamylal disposition for the combination regimen. Computer-generated curves, associated with the two-compartment open model showing the fraction of dose in each compartment as a function of time, illustrated that pentobarbital rapidly achieved higher concentrations in the peripheral compartment after prior thiamylal administration. Protein-binding studies showed that this could not be attributed to displacement of pentobarbital from plasma albumin by thiamylal. Calculation of total and free drug concentrations at the time of awakening showed that, when the drugs were combined, the concentration of each drug was less than half of that observed at awakening when they were studied separately. It can be concluded that the prolonged sleeping times associated with the sequential combination of the two agents were not due to an alteration in kinetic parameters of either drug caused by the other, but rather to an additive effect of the subanesthetic concentrations of the two drugs when combined. The fact that sleeping times were supra-additive is attributed to a shift of awakening time from the distribution (alpha) phase, when given independently, to the elimination (beta) phase when administered in combination.     

Mitogenic responses of baboon (Papio cynocephalus) peripheral blood mononuclear cells. A possible role for monocytes

Removal of carbonyl iron-adherent/phagocytic cells from baboon peripheral blood mononuclear cells generally resulted in a depressed blastogenic response to both pokeweed mitogen and concanavalin A. In the majority of cases, no alteration in dose requirement nor shift in kinetics was apparent. Staining for peroxidase activity indicated a reduced proportion of monocytes in the population of cells treated with iron. Therefore, the results of this study strongly suggest a potentiating role for monocytes in lectin stimulation of baboon lymphocytes.     

Prevention of coccidiosis in domestic dogs and captive coyotes (Canis latrans) with sulfadimethoxine-ormetoprim combination

Sulfadimethoxine-ormetoprim combination was evaluated as a coccidiostat against experimentally induced coccidiosis in young dogs and coyotes (Canis latrans). The animals were experimentally inoculated with 50,000 or 100,000 sporulated oocysts of Isospora ohiohensis (98%) and Isospora canis (2%). In experiment 1, daily treatment for 13 to 23 days with a combination of 27.5 mg of sulfadimethoxine/kg of body weight (BW) and 5.5 mg of ormetoprim/kg of BW admixed to the feed resulted in no significant (P greater than 0.05) difference in fecal oocyst counts between treated and nontreated groups of dogs or coyotes. In experiment 2, treatment with a combination of 55 mg of sulfadimethoxine/kg of BW and 11 mg of ormetoprim/kg of BW for 23 days was 99.8% effective against Isospora spp infections in dogs. Significantly (P less than 0.05) fewer oocysts were present in feces of treated dogs than were present in feces of nontreated dogs from first passage of oocysts at day 4 to the end of the patent period at days 19 to 21. After the 2nd week of treatment, BW of treated dogs were significantly greater (P less than 0.05) than BW of nontreated dogs. Evidence of drug toxicity was not observed clinically or by serum chemical analyses.     

Ocular changes in a cat with disseminated blastomycosis

A domestic shorthair cat examined because of dyspnea was found to have ophthalmoscopic and radiographic changes suggestive of systemic mycosis. The cat died despite antifungal therapy. Histologic examination revealed Blastomyces dermatitidis in the eyes, brain, lungs, stomach, liver, kidneys, spleen, pancreas, and adrenal glands. The pathologic changes were similar, but more widespread than those typically seen with canine blastomycosis.     

Multiple embryo-transplant offspring produced from quartering a bovine embryo at the morula stage

A non-surgical embryo collection was completed on a day 7 superovulated Chianina donor cow. Because all but two of the ova from the collection were unfertilised and a surplus of potential recipients was available, one embryo (an excellent quality late morula) was dissected into four equal portioned 'quarter' embryos using a simplified micromanipulation procedure. Each quarter embryo was then placed in a 0.25 ml French straw and non-surgically transplanted to four different crossbred beef recipient females. The remaining embryo was similarly transplanted to a herd mate recipient as an intact embryo. One recipient returned to oestrus, one recipient had an extended post transfer cycle and the two remaining recipients produced a live quarter embryo transplant calf each within 24 hours of the other. The intact embryo placed in a herd mate recipient did not produce a transplant calf. To the authors' knowledge, these transplant offspring are the first live births reported from a non-surgically collected later-stage bovine morula (day 7), which had been dissected into quarters and then individually transplanted non-surgically to recipient females. The procedure was relatively simple to perform and was completed in less than one hour.     

Inhibition of phagosome-lysosome fusion in macrophages by soluble extracts of virulent Brucella abortus

Water extracts of virulent Brucella abortus were able to inhibit phagosome-lysosome fusion in unelicited murine peritoneal macrophages following ingestion of yeast. Extracts from an avirulent strain were unable to produce a similar effect. Lipopolysaccharide from B abortus did not appear to be involved with the ability of the extracts to inhibit fusion.     

Response of growing-finishing pigs to decreasing floor space allowance and(or) virginiamycin in diet

Five hundred forty crossbred pigs were utilized in four trials (10 replications) at two stations to determine the separate and interacting effects of decreasing floor space allowance with or without the addition of virginiamycin to the diet on performance of growing-finishing pigs. Pigs were allowed .37, .33 or .28 m2/pig during the growing phase (23 to 55 kg) and .74, .66, .56 m2/pig during the finishing phase (55 to 100 kg) and fed either a corn-soybean meal control diet or the control diet plus 11 mg of virginiamycin/kg of diet. Floor space allowances were achieved by varying pen size, so the number of pigs and feeder space per pig were constant for all pens. During the growing phase, daily gain (P less than .01) daily feed intake (P less than .05) and feed conversion ratio (P less than .05) decreased as floor space allowance decreased. During the finishing phase and for the total test period, daily gain (P less than .01) and feed conversion ratio (P less than .05) were reduced but daily feed intake was not affected (P greater than .05) by restricted floor space allowance. The addition of virginiamycin to the diet had no effect on pig performance. The virginiamycin X floor space allowance interaction was not significant, suggesting that pigs fed a diet with or without virginiamycin responded similarly to restricted floor space allowance. The data suggest that the addition of virginiamycin to the diet was ineffective in overcoming the decrease in performance of growing-finishing pigs caused by crowded conditions.     

Hemorrhage from the cosmetic otoplasty of Doberman Pinschers with von Willebrand's disease

The hemorrhagic tendencies of 23 Doberman Pinscher pups were observed during cosmetic otoplasty and were ranked by a +1 to +4 grading system (+1 = least hemorrhage, and +4 = most hemorrhage). A second estimate of the hemostatic competencies of these dogs was made by counting the gauze sponges used in the otoplasties. Factor VIII-related antigen concentrations and coagglutinin cofactor concentrations were measured in plasma samples from blood drawn not more than 30 hours before the surgical procedures were done. The factor VIII-related antigen concentrations were between 9% and 147% of the concentration in a normal plasma pool, and the coagglutinin cofactor concentrations were between 1% and 165%, indicating that some of these dogs had von Willebrand's disease. The hemorrhagic tendencies of 12 pups were graded +1. This group had a mean antigen concentration of 75% (min-max, 38% to 147%) and a mean coagglutinin cofactor concentration of 89% (min-max, 42% to 165%). These were significantly greater than the antigen and cofactor concentrations of the grades +2 (n = 5), +3 (n = 3), or +4 (n = 3) dogs. Significant differences were not found when antigen concentrations of the grade +2 dogs (mean, 16%; min-max, 11% to 22%), grade +3 dogs (mean, 13%; 12% to 16%), and grade +4 dogs (mean, 11%; 9% to 12%) were compared with each other, nor were significant differences seen among the coagglutinin cofactor concentrations of the grade +2 dogs (mean, 7%; min-max, 1% to 11%), grade +3 dogs (mean, 6%, 4% to 8%), and grade +4 dogs (mean, 5%; 2% to 9%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Methodological aspects of the determination of nitrogen metabolism parameters from 15N-tracer experiments on swine based on nitrogen metabolism models. 2. Calculation of N metabolism parameters from the time of urinary excretion of 15N

After a 45-hour infusion of 15N-lysine and 15N-glycine resp. with pigs of 25 kg live weight, the infusion of the tracer was disrupted and a 3-day reduction phase was made part of the experiment. The N-metabolism parameters such as protein synthesis and decomposition quotas were calculated on the basis of the temporal development of 15N-amounts excreted in urine. The labelling and reduction phases were evaluated simultaneously. By means of including the total N-amount of the animal body the balance calculation becomes more stable. The possible influence of the tracer amino acid in connection with the 3-pool-model is discussed on the basis of the ascertained parameters.     

Variation of fiber types in the triceps brachii, longissimus dorsi, gluteus medius, and biceps femoris of horses

The distribution of type-I and type-II fibers in 9 different parts of the musculi triceps brachii, longissimus dorsi, gluteus medius, and biceps femoris was studied to determine whether biopsies from these muscles give reliable information. All 4 investigated muscles were not homogeneous in their fiber-type distribution. Large differences existed among different muscle parts. The percentage of type-I fibers increased toward the deeper and cranial parts of the muscles. In the same zone of the gluteus muscle, differences of 30% were found for type-I fibers. Therefore, results obtained by biopsies of muscles must be interpreted with caution.