In vitro effects of prostaglandin E1, prostaglandin E2, indomethacin, histamine, and tuftsin on chemiluminescence response of bovine polymorphonuclear leukocytes

The in vitro effects of prostaglandin E1 (PGE1), prostaglandin E2 (PGE2), indomethacin, histamine, and tuftsin on the chemiluminescence response of bovine polymorphonuclear cells (PMN) were determined. Addition of PGE1, PGE2, indomethacin, and histamine in vitro significantly suppressed the chemiluminescence response of bovine PMN's, whereas tuftsin had no effect. Suppression was dependent upon the continued presence of PGE1, PGE2, and histamine in the culture media. However, indomethacin's suppressive effect remained even after it was removed from the culture media. Hydrogen peroxide generated chemiluminescence was suppressed by high concentrations of indomethacin and histamine. Results of this study suggest possible pharmacologic or regulatory mechanisms for certain of these immune modulators in the control of the oxidative burst reaction of bovine PMN's.     

Exogenous pituitary and recombinant growth hormones induce insulin and insulin-like growth factor 1 resistance in pig adipose tissue

In the present study, pigs were treated daily for 7 days with exogenous porcine growth hormone (pGH; 70 micrograms/kg BW) in order to determine whether pGH induced insulin and insulin-like growth factor 1 (1GF-1) resistance in pig adipose tissue. In the first experiment, pituitary-derived pGH (ppGH) decreased basal and insulin-stimulated lipogenesis by 50%. Insulin sensitivity decreased more than 90% as the result of pGH treatment. Sensitivity and responsiveness to IGF-1 were decreased 50% by ppGH. In a second experiment, pigs were treated daily (70 micrograms/kg BW) with exogenous pituitary pGH (ppGH) or recombinant pGH (rpGH) for 7 days in order to determine if the effects of pGH were intrinsic properties of the hormone. Both rpGH and ppGH caused similar decreases in basal rates of lipogenesis, insulin- and IGF-1-stimulated lipogenesis, and insulin and IGF-1 responsiveness in pig adipose tissue. In summary, the decrease in adipose tissue growth of pigs treated chronically with pGH is due in large part to the suppression of fatty acid synthesis and a decrease in the ability of insulin to stimulate lipid synthesis in pig adipocytes. These responses are intrinsic properties of pGH since the effects of rpGH mimicked those of ppGH. The role and importance of a decrease in IGF-1 responsiveness remains to be resolved.     

Effects of domperidone and thyrotropin-releasing hormone on secretion of luteinizing hormone and prolactin during the luteal phase and following induction of luteal regression in sheep

Effects of domperidone, a peripheral dopamine receptor antagonist, on secretion of LH and prolactin were studied during the luteal phase and following administration of PGF2 alpha. Since hyperprolactinemia has been reported to inhibit secretion of LH in ewes, effects of thyrotropin-releasing hormone (TRH) also were examined. Ewes 8-10 days post-estrus were assigned to be treated with: 1) vehicle (n = 5); 2) 0.3 mg domperidone (n = 6); 3) 1.0 mg domperidone (n = 6); 4) 3 micrograms TRH (n = 6); or 5) 10 micrograms TRH (n = 6) every 4 hours for 60 hr. Luteal regression was induced with PGF2 alpha at 12 hr after initiation of treatments. During the luteal phase, pulses of LH were more frequent (P less than .05) and the amplitudes of these were higher (P less than .05) in ewes treated with domperidone or TRH than in control ewes. These changes in LH occurred even though each treatment elevated markedly concentrations of prolactin in plasma. After induction of luteal regression, mean of LH and frequency of LH discharges were similar in all groups. However, in ewes treated with the 1.0 mg/4 hr dose of domperidone the pulse amplitude was greater than in the other groups (2.3 vs 1.1 ng/ml). Dose-response relationships and the magnitude of the prolactin release following domperidone or TRH varied with time. Treatments did not affect the timing of the LH surge or the increase in progesterone associated with the subsequent cycle.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isolation of Legionella pneumophila from calves and the prevalence of antibodies in cattle, sheep, horses, antelopes, buffaloes and rabbits

The lungs of 139 calves presented for autopsy and 29 healthy slaughtered calves were examined for Legionella by culture and by direct immunofluorescence (DIF) with fluorescein-conjugated antisera. About 17% of the cadaver lungs and 4% of lungs from slaughtered animals were positive by DIF. Legionella organisms were only isolated from the lungs of two cadavers (L. pneumophila, serogroup 1). In a prevalence study of antibodies to Legionella in domestic and wild animals of various species, titers of greater than or equal to 64 were demonstrated by indirect immunofluorescence in sera of 10% of dairy cattle, 5% of beef cattle, 4% of sheep, 22% of antelopes, 35% of horses, 36% of buffaloes and 0% of laboratory rabbits. The isolation of Legionella from lung tissue is evidence for a possible etiologic role of Legionella spp. in natural pathology of animals.     

Partial characterization of a Legionella pneumophila serogroup 1 immunodominant antigenic determinant recognized by a monoclonal antibody. Legionella specific antigenic determinant

A monoclonal antibody was used to characterize a serogroup 1 specific Legionella pneumophila Philadelphia strain 1 antigenic determinant. A quantitative fluorometric assay was developed to quantitate the antibody sites (2.7 +/- 0.4 X 10(5)) on Legionella bacteria and to determine the physico-chemical parameters of the antibody-antigen interaction (at 4 degrees C: delta G = -10.9 Kcal X mol-1, delta H = 1.7 Kcal X mol-1, delta S = 45 cal X K-1 X mol-1). The same method was used to study the modification or the removal of the antigen by chemical and enzymatic means (trypsin, papain, lysozyme, acetone, chloroform-methanol and Tris-EDTA); only Tris-EDTA extraction resulted in a significant decrease in antibody binding sites. Inhibition studies of the fluorescein-labelled antibody binding were performed with different sugars of which only L-fucosylamine was inhibitory, and with other monoclonal antibodies to Legionella pneumophila serogroup 1 in order to compare their fine specificity and affinity. The results indicate that the epitope recognized was an immunodominant carbohydrate including an aminodideoxyhexose and carried by the lipopolysaccharide.     

Experimental infection of mice with Rhodococcus equi: differences in virulence between strains

The growth kinetics in outbred mice of clinical and environmental isolates of Rhodococcus equi were followed by serial bacterial enumeration of organ homogenates. Clinical isolates multiplied until Day 4 before being progressively cleared, but could still be recovered from the liver at 3-4 weeks post-infection. Intravenous inoculation of clinical strains was associated with histopathological responses very similar to those elicited by intravenous infection with various facultative intracellular parasites. Whereas lesions in mice and foals at 7-9 days following respiratory infection are those of severe bronchopneumonia with massive consolidation, a week later the patterns of host response have diverged as the murine lesions resolve. The type strain, NCTC 1621 and 4-6 environmental isolates were eliminated without prior multiplication and these strains caused negligible lesions. The two environmental strains which behaved as the clinical strains were recovered from a stud with an R. equi problem. No association of colonial morphology of R. equi with virulence was apparent.     

A multicentric retrospective study of serum/plasma urea and creatinine concentrations in dogs using univariate and multivariate decision rules to evaluate diagnostic efficiency

BACKGROUND: Urea and creatinine are the most frequently used indirect markers in plasma and serum of glomerular filtration rate in dogs. Both have been shown to lack sensitivity but their diagnostic efficiency for the diagnosis of kidney disease has been minimally investigated. OBJECTIVE: The purpose of this retrospective study was to investigate the influence of possible factors of variation on both analytes and to determine whether specific decision rules should be drawn up for subpopulations of dogs. METHODS: The results of urea and creatinine measurements, breed, sex, age, and health status (healthy, renal disease, or nonrenal disease) of 3822 dogs were collected from the archives of 5 veterinary clinics. Data were analyzed with univariate and multivariate decision rules with and without adjustment. RESULTS: There were significant effects and interactions of almost all of the sources of variation. Slight improvements in diagnostic efficiency were obtained by adjusting the decision rules to these sources of variations. Univariate decision rules gave approximately the same diagnostic efficiency for urea and creatinine concentrations, with sensitivity and specificity in the range of 70% and 90%, respectively, using the upper limit of the reference interval as the threshold value. Multivariate decision rules provided only minor improvements in diagnostic efficiency. CONCLUSION: Simultaneous measurement of both urea and creatinine is of limited diagnostic value over the analysis of a single variable. Creatinine is the preferred analyte as it is affected by fewer extrarenal factors of variation.     

Multicenter case-control study of risk factors associated with development of vaccine-associated sarcomas in cats

OBJECTIVE: To determine whether particular vaccine brands, other injectable medications, customary vaccination practices, or various host factors were associated with the formation of vaccine-associated sarcomas in cats. DESIGN: Prospective multicenter case-control study. ANIMALS: Cats in the United States and Canada with soft tissue sarcomas or basal cell tumors. PROCEDURE: Veterinarians submitting biopsy specimens from cats with a confirmed diagnosis of soft tissue sarcoma or basal cell tumor were contacted for patient medical history. Time window statistical analyses were used in conjunction with various assumptions about case definitions. RESULTS: No single vaccine brand or manufacturer within antigen class was found to be associated with sarcoma formation. Factors related to vaccine administration were also not associated with sarcoma development, with the possible exception of vaccine temperature prior to injection. Two injectable medications (long-acting penicillin and methyl prednisolone acetate) were administered to case cats more frequently than to control cats. CONCLUSIONS AND CLINICAL RELEVANCE: Findings do not support the hypotheses that specific brands or types of vaccine within antigen class, vaccine practices such as reuse of syringes, concomitant viral infection, history of trauma, or residence either increase or decrease the risk of vaccine-associated sarcoma formation in cats. There was evidence to suggest that certain long-acting injectable medications may also be associated with sarcoma formation.