The role of bile salt in biliary lipid excretion was studied in 3 healthy ponies with chronic external biliary fistulas. After endogenous bile salt pool depletion, micelle-forming taurocholate or taurochenodeoxycholate was infused to replace excreted bile salt. Enterohepatic circulations were held open (total biliary diversion) throughout each study. Results indicated that biliary lipid excretion in ponies (113 +/- 21 nmol/in/kg of body weight) is approximately 10 times less than that reported in rodents. Although the lipid composition (4.4% cholesterol, 5.6% phospholipid, and 90% bile salt) was within the predicted range for a single phase of micellar (or vesicular) liquid in solution, it was supersaturated with cholesterol because of low absolute concentrations of bile salt and phospholipid. Ponies, like guinea pigs, were determined to have a high bile salt-independent secretion of biliary lipid with little (or no) coupling to endogenous bile salt output. However, bile salt excretion induced by higher taurocholate infusion rates (ie, those greater than the physiologic range of 61 to 125 nmol/min/kg) was positively correlated with an increase in biliary phospholipid excretion, but not cholesterol excretion, thus indicating that a threshold intracellular bile salt concentration may be associated with enchanced biliary phospholipid excretion in ponies. The apparent cholerectic effects of endogenous bile salts, taurocholate, and taurochenodenoxycholate (that is, the increment in bile flow per increment in bile salt recovered) were greater in ponies than reported for any other mammal.

Ovariectomized, nonlactating cows were treated with IM injections of either physiologic saline solution or prostaglandin F2 alpha. Plasma concentrations of cortisol increased significantly by 30 to 60 minutes after injection of prostaglandin F2 alpha, but there were no significant increases in plasma concentrations of estradiol, progesterone, or testosterone. After saline solution treatment, there were no increases in any of the hormones measured.

Serum immunoglobulins of the IgG isotype recognizing common gram-negative cell core epitopes were serially measured, using a direct ELISA, on samples obtained from 20 neonatal Holstein calves. An R-mutant Escherichia coli (strain J5) was used as a plate antigen in this assay. Total serum IgG concentration was measured using radial immunodiffusion. Half-lives of core antigen-specific IgG (7.56 days) and total serum IgG (22.66 days) were dramatically different (P less than 0.0005). This may be an indication of cross-reactive consumption of core antigen-specific immunoglobulins.

Sixteen 7-week-old Holstein male calves were inoculated with sporulated oocysts of Eimeria zuernii. Four calves (controls) were euthanatized and necropsied at 14 and 20 days after inoculation (DAI). Two calves were treated with 20 mg of dexamethasone (IM) on 13, 14, and 15 DAI and euthanatized and necropsied 17 DAI and 2 calves were given similar treatments and necropsied 20 DAI. The 8 other calves were euthanatized and necropsied 20 DAI. Two were started on the anticoccidial drug decoquinate in feed 13 DAI; 2 others were given decoquinated on the same schedule plus dexamethasone on 13, 14, and 15 DAI. Two calves were given the antibiotic narasin in feed beginning 13 DAI and 2 calves were given parasin on the same schedule plus dexamethasone on 13, 14, and 15 DAI. All calves, except 2 controls necropsied 14 DAI and 4 calves given decoquinate, discharged moderate-to-large numbers of oocysts in feces and had moderate-to-severe changes in fecal consistency. Histologic examintions revealed large numbers of endogenous stages in tissues of calves treated or not treated with dexamethasone. Few endogenous stages were observed in tissues from calves that were given decoquinate or decoquinate plus dexamethasone. Calves given narasin or narasin plus dexamethasone had moderate-to-large numbers of endogenous stages in the tissues.

Analysis of protein and antigen profiles of Tritrichomonas foetus isolates from cattle from 5 western states was accomplished sodium dodecyl sulfate polyacrylamide-gel electrophoresis, immunoblot, immunoprecipitation, and fluorography techniques. Total protein profiles of all isolates were compared by Coomassie brilliant blue staining of T foetus protein samples prepared by 4 protein-extraction methods. Antigenic tritrichomonas proteins were identified by immunoblot assay with polyclonal bovine or rabbit anti-T foetus serum. Additionally, [14C]glucosamine-labeled T foetus was used for total and antigenic glycoprotein analyses. Detectable differences in the composition of total proteins or antigenic tritrichomonal proteins were not observed among all isolates. However, intensity differences in some antigenic protein bands were apparent. Bovine and rabbit sera from immunized animals possessed antibodies to the same antigenic tritrichomonal proteins. Each T foetus isolate contained 4 to 7 molecular weight size classes of glycoprotein, which were labeled by [14C]glucosamine; however, only 3 to 4 glycoproteins were identified as antigens by bovine or rabbit antiserum.

Lateral cecal arterial blood flow, carotid arterial pressure, heart rate, and mechanical activity in the duodenum, right ventral colon, cecal body, and cecal apex were measured in 6 conscious healthy horses for 60 minutes during and for 120 minutes after IV infusion of 0.9% NaCl solution (control) or fenoldopam. There were no significant changes in these measurements during or after infusion of 0.9% NaCl (saline) solution. Fenoldopam, a selective dopamine- 1 receptor agonist, was administered in saline solution at dosages of 0.01, 0.05, and 0.1 ug/kg/min. Intravenous infusion of fenoldopam at 0.01 ug/kg/min significantly increased heart rate, but did not change average carotid arterial pressure or lateral cecal arterial blood flow. Intravenous infusion of fenoldopam at both 0.05 and 0.1 ug/kg/min significantly increased heart rate, significantly decreased average carotid arterial pressure, and significantly increased lateral cecal arterial blood flow. Intravenous infusion of fenoldopam at 0.01, 0.05 and 0.1 ug/kg/min did not significantly change the mechanical activity measured by the area under the strain gauge defection curve for the duodenum, right ventral colon, cecal body, or cecal apex. These results suggest that dopaminergic-1 receptors are present on the colonic vascudopaminergic-1 receptors exist on the visceral smooth muscle of the duodenum, right ventral colon, cecal body, or cecal apex of horses.

A micro-ELISA, using horseradish peroxidase-conjugated anti-canine IgE and polystyrene microtitration wells for detection of allergen-specific IgE in canine serum, was developed. Specificity of anti-canine IgE was confirmed by reversed cutaneous anaphylaxis evaluations, gel-precipitation reactions, immunoelectrophoresis, immunoaffinity chromatography, and heat inactivation. Individual allergen blanks were used to account for variable nonspecific binding among various allergens, and results were normalized using 4 reference sera. Coefficients of variation for intra-assay and interassay variability ranged from 0.77 to 5.66% and 3.15 to 9.83%, respectively. Results observed with wells coated with mixtures of various allergen extracts yielded results approximately equal to results (average) of wells containing individual components. Agreement between ELISA and skin test results ranged from 43 to 64%, depending on allergen used.

Liposomes with entrapped gentamicin were used to treat mice with infection attributable to Brucella melitensis. Liposomes bearing positive charge and formed by egg yolk lecithin, cholesterol, and stearylamine were effective in the elimination of B melitensis residing in liver and spleen. Negatively charged liposomes, formed by egg yolk lecithin, cholesterol, and dicetyl phosphate were also effective in suppression of the infection in liver, but were less so in suppression of the infection in the spleen. Free gentamicin was less effective than the encapsulated antibiotic. At 20 hours after administration of gentamicin encapsulated in liposomes, the gentamicin concentrations in liver and spleen were similar, regardless of the charge of the liposomes--neutral, positive, or negative. However, positively charged liposomes were more efficient than were other liposome types for the treatment of brucellosis caused by B melitensis.

Ceftazidime pharmacokinetic values were studied in unweaned calves given the antibiotic alone or in combination with probenecid. Ceftazidime was administered IV to 9 calves at a dosage of 10 mg/kg of body weight and IM (10 mg/kg) to 8 calves, to 7 calves (10 mg/kg plus probenecid [40 mg/kg]), and to 9 calves (10 mg/kg plus probenecid [80 mg/kg]). Serum concentration-vs-time data were analyzed, using noncompartmental methods based on statistical moment theory. The data for IV ceftazidime administration also were fitted by use of a linear, open 2-compartment model. The mean (+/- SD) terminal half-life was 138.7 +/- 23.6 minutes and 126.3 +/- 10.5 minutes after IV and IM administrations, respectively. The mean residence time was 167.3 +/- 21.1 minutes and 201.4 +/- 16.8 minutes after IV and IM administrations, respectively. Coadministration of probenecid did not affect the terminal half-life or mean residence time values. The total body clearance was 1.75 +/- 0.26 ml/min/kg, and the volume of distribution at steady state was 0.294 +/- 0.064 L/kg. The estimated mean absorption time was 34.1 minutes. There were no significant differences between the mean residence time calculated by statistical moment theory or by compartmental analysis, indicating central compartment output of ceftazidime. The 90% minimal inhibitory concentration values of ceftazidime determined for Escherichia coli, Salmonella spp, Pasteurella multocida, and P haemolytica isolates ranged from less than 0.01 to 0.1 microgram/microliter.

Serum and vaginal Brucella-specific immunoglobulin isotypes (IgGl, IgG2, IgM, and IgA), obtained from 62 crossbred beef heifers vaccinated with Brucella abortus salt-extractable proteins and subsquently challenge exposed with B abortus S2308, were studied. Brucella-specific IgG antibodies and Brucella-specific immunoglobulin isotypes were quantitated by a fluorometric immunoassay. Serum and vaginal immunoglobulin responses were evaluated as a method of distinguishing infected from noninfected heifers. Rivanol precipitation, complement-fixation, buffered-antigen brucellosis tests and an ELISA were performed on sera. For immunoglobulin isotypes, vaccinated heifers had mean antibody responses higher than baseline mean antibody responses for at least 31 weeks after vaccination. After challenge exposure, significant differences (P > 0.05) were not detected between mean antibody responses of vaccinated and nonvaccinated heifers. Vaginal Brucella-specific antibody responses did not correlate with protection from disease. Vaginal Brucella-specific IgM was detected only at the time of abortion.