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in Journal of the American Veterinary Medical Association

Summary

Effects of 1 hour of colonic volvulus and 3 hours of reperfusion on concentrations of thromboxane (txb 2) and prostacyclin (6-keto-PGF) in portal, pulmonary arterial, and jugular blood were determined by radioimmunoassay to assess the site of production and clearance of these eicosanoids from the circulation in 5 anesthetized ponies. Colonic volvulus had no significant effect on mean arterial pressure or txb 2 concentrations, but significantly (P < 0.05) increased 6-keto-PGF concentrations in all blood samples. Immediately after colonic reperfusion, all eicosanoid concentrations were significantly (P < 0.05) increased. Then, txb 2 returned to baseline values, whereas 6-keto-PGF concentrations remained significantly (P < 0.05) high for the remainder of the study. Eicosanoid concentrations were significantly (P < 0.05) greater in portal blood than in pulmonary arterial and jugular blood samples at all periods. This suggests that the splanchnic circulation is the primary site of eicosanoid production during and after colonic volvulus and the liver appears to provide most of the circulatory clearance of thromboxane and prostacyclin.

Free access
in American Journal of Veterinary Research

SUMMARY

Cattle persistently infected with bovine viral diarrhea (bvd) virus have decreased neutrophil and lymphocyte functions. We reevaluated these functions and further characterized the inhibition of persistent bvd virus infection in neutrophils, using sensitive kinetic assays. In addition, the influence of in vitro incubation of neutrophils with recombinant bovine interferon gamma (rBoifn gamma) and in vitro incubation of lymphocytes with recombinant bovine interleukin-2 was evaluated.

Significant (P < 0.05) decrease in random migration under agarose, Staphylococcus aureus ingestion, cytochrome-C reduction, iodination, antibody-independent cell-mediated cytotoxicity, oxidant production, and cytoplasmic calcium flux were observed in neutrophils from cattle persistently infected with bvd virus, compared with noninfected control cattle. Incubation of neutrophils from noninfected controls with rBoifn gamma significantly (P < 0.05) decreased random migration under agarose, cytochrome-C reduction, and cytoplasmic calcium flux. Neutrophils from cattle persistently infected with bvd virus also had decreased random migration under agarose after incubation with rBoifn gamma; in addition, antibody-independent cell-mediated cytotoxicity, elastase release, and cytoplasmic calcium flux were significantly enhanced. The rBoifn gamma induced significantly (P < 0.05) different effects on chemotaxis, cytochrome-C reduction, iodination, and cytoplasmic calcium flux of neutrophils from infected and control cattle. The rBoifn gamma was more effective at improving the function of neutrophils from cattle persistently infected with bvd virus, compared with neutrophils from controls.

Lymphocytes from infected cattle had decreased histogenesis in response to phytohemagglutinin, concanavalin A, and pokeweed mitogen. Incubation of those lymphocytes with recombinant bovine interleukin-2, with no mitogen present, significantly (P < 0.05) increased incorporation of [3H]thymidine. However, the response of lymphocytes to mitogen stimulation was not significantly increased by the presence of recombinant bovine interleukin-2, indicating that depression of in vitro lymphocyte histogenesis in the cattle persistently infected with bvd virus is not attributable to decreased production of interleukin-2.

Free access
in American Journal of Veterinary Research

SUMMARY

Large colon torsion frequently is a fatal condition in horses. The purpose of the study reported here was to determine systemic arterial pressure, plasma eicosanoid concentrations, colonic blood flow, vascular resistance, tissue pH, and morphologic features associated with large colon torsion and detorsion, and to evaluate the effects of sodium heparin (80 IU/kg of body weight, iv) treatment on these values. Values were determined in 20 anesthetized ponies that were randomly assigned into 4 equal groups: control; control/heparin; torsion; torsion/heparin. Torsions were created by a 720° rotation of the cecum and colon around their long axes at the sternal and diaphragmatic flexures. After 1 hour of torsion, the torsion was corrected and the colon was allowed to reperfuse for 1 hour. Heparin was administered 30 minutes into the experiment. Parametric data were analyzed (P ≤ 0.05), using split-plot analysis of variance, with differences between means evaluated with a modified Bonferroni t test; histopathologic data were analyzed (P ≤ 0.05) with a Kruskal-Wallis one-way analysis of variance by ranks. Heparin prevented colonic detorsion-induced hypotension and increases in vascular resistance and thromboxane concentration, and it significantly increased colonic blood flow for 40 minutes during reperfusion. Heparin did not alter prostacyclin concentration or the histologic appearance of the large colon.

Free access
in American Journal of Veterinary Research