To determine the role of thromboxane A2 in the pathogenesis of experimentally induced immune complex glomerulonephritis, 12 concanavalin A-immunized Beagles were infused with 1 mg of concanavalin A via each renal artery and treated twice daily for 8 days with either 30 mg of CGS 12970/kg, PO, a specific thromboxane synthetase inhibitor, or placebo. The effect of treatment was assessed by measuring endogenous creatinine clearance and urine protein and eicosanoid excretion, and by evaluating changes in glomerular morphometric characteristics. On postinfusion day 8, urine protein, thromboxane B2, and 11-dehydro-thromboxane B2 excretion, glomerular epithelial crescent formation, and glomerular cell proliferation in the CGS 12970-treated dogs were significantly decreased when compared with values in the placebo-treated group. Differences were not observed in endogenous creatinine clearance, urine prostaglandin E2 and 6-keto-prostaglandin F1 alpha excretion, or glomerular polymorphonuclear leukocyte infiltration between groups in this study. These findings suggest thromboxane A2 has a role in the development of immune complex glomerulonephritis and that thromboxane synthetase inhibition may be beneficial in attenuating some of the functional and histologic changes associated with immune complex glomerulonephritis.

Biological responses to recombinant DNA-derived bovine interferon alpha (rBoIFN-alpha I1) by bovine alveolar macrophages were examined by measuring viral yield reduction and 2',5'-oligoadenylate synthetase (2',5'-OAS) production by IFN-treated cells. In vitro IFN pretreatment of alveolar macrophages reduced viral yield in cultures challenged exposed with parainfluenza-3 virus, compared with control cultures. In vitro treatment of alveolar macrophages with IFN also resulted in increased 2',5'-OAS activity. The 2',5'-OAS activity was measured in alveolar macrophages and blood mononuclear leukocytes of calves injected im with 3.6 X 10(6) U of rBoIFN-alpha I1/kg of body weight. The IFN action was monitored by measuring 2',5'-OAS activity of blood mononuclear leukocytes beginning 6 days before and ending 24 hours after IFN treatment. The 2',5'-OAS activity in the blood mononuclear leukocytes sharply increased 24 hours after IFN treatment, indicating response to IFN. The alveolar macrophages collected from the same calves 24 hours after IFN administration also had increased 2',5'-OAS activity, compared with alveolar macrophages from the same calves collected 6 days before treatment. Increased 2',5'-OAS activity indicates: a possible mechanism of IFN action in cattle that may be responsible for viral yield reduction; potential use of high enzyme activity as a marker for IFN induction; and potential use of 2',5'-OAS activity as a marker for determining effects of IFN on bovine macrophages and other cells of the bovine immune system.

Cell extracts that were prepared from blood mononuclear leukocytes from 66 samples obtained from 6 clinically normal calves contained mean 2',5'-oligoadenylate (2',5'-oligo[A]) synthetase activity sufficient to synthesize 186 +/- 82 pmol of 2',5'-oligo(A)/h/10(6) cells. Calves had no measurable serum interferon (IFN) activity. Five calves were given IM injections of 10(4), 10(5), 5 x 10(5), 10(6), and 10(7) U of bovine IFN-alpha 1/kg of body weight at 2-week intervals. Five dosing sequences were used with a 5 x 5 Latin square design so that each calf received each dose once. Activity of 2',5'-oligo(A) synthetase increased at 24 hours in response to all dosages of IFN and then declined following first-order kinetics, with an apparent half-life (t1/2) of 2.1 +/- 0.5 days. The area under the concentration-time curve for 2',5'-oligo(A) synthetase increased with dose of IFN more rapidly than did peak response. Serum IFN that was measured at 1-day intervals following administration of IFN was consistently measurable only at dosages above 10(6) U of IFN/kg. The t1/2 for circulating IFN was 12.4 +/- 1.0 hours. Over all dosages, increases in 2',5'-oligo(A) synthetase activity were measurable for 3.5 days longer than were increases in IFN following IM injection of IFN. None of the calves developed detectable anti-IFN antibodies.

A specific thromboxane synthetase inhibitor, 3-methyl-2 (3-pyridyl)-1-indoleoctanoic acid (CGS 12970) was administered orally to 6 healthy adult Beagles at a dosage of 30 mg/kg of body weight. Blood generation of thromboxane B2 and urinary excretion of thromboxane B2 were measured before and after administration of CGS 12970. Although 97 +/- 0.4% inhibition of thromboxane B2 generation was observed within 2 hours after a single dose of CGS 12970 was administered orally, an effect on urinary excretion of thromboxane B2 was not observed. Additionally, oral administration of 30 mg/kg every 12 hours resulted in 80 +/- 14% inhibition of thromboxane B2 generation but had no effect on urinary thromboxane B2 excretion.

The antiviral activity of recombinant DNA-derived bovine alpha 1-1 interferon on an established swine testicular cell line and primary testicular cell cultures derived from swine of various ages (2 days, 3 weeks, and 5 weeks) was determined. Bovine interferon induced a dose-dependent increase in 2-5A synthetase in testicular cells, regardless of the source of the cells. Furthermore, interferon inhibited replication of vesicular stomatitis virus to an equivalent extent in all testicular cell cultures. The results indicate that 2-5A synthetase is a reliable marker of interferon activity in swine testicular cell cultures and that the induction of 2-5A synthetase and antiviral effects of recombinant bovine interferon in primary testicular cell cultures are not dependent on the age of the donor animal.

Twelve Beagles were inoculated with concanavalin A, and after a mean ninefold increase in antibody titer, 1 mg of concanavalin A was infused into each renal artery of each dog to induce in situ immune complex glomerulonephritis. Starting 4 weeks after renal arterial infusion, 6 dogs were treated orally 3 times daily with 30 mg of 3-methyl-2 (3 pyridyl)-1-indoleoctanoic acid (CGS 12970)/kg of body weight, a thromboxane synthetase inhibitor, and 6 dogs (control group) received a gelatin capsule 3 times daily. Endogenous creatinine clearance and 24-hour urinary excretion of protein and thromboxane B2 were determined for each dog prior to renal arterial infusion, at the initiation of treatment and at 2, 4, 6, and 8 weeks after initiation of treatment. In addition, methyoxy-(3)H inulin clearance was determined at initiation of treatment and 4 and 8 weeks later. Renal specimens were examined histologically at the initiation of treatment and 4 and 8 weeks later. Glomerular mononuclear profiles/micrometers(3) were determined from at least 10 equatorially sectioned glomeruli from each dog. Paired t tests were used to compare mean values at the various time points to the respective mean baseline value and 2-sample t tests were used to evaluate differences between treatment groups. At the start of treatment (4 weeks after renal arterial infusion of concanavalin A), histologic evaluation of renal specimens revealed glomerular epithelial crescent formation, mononuclear cell proliferation, and infiltration of neutrophils. Mononuclear cell profiles and urinary excretion of protein and thromboxane B2 were significantly increased, but endogenous creatinine clearance values were unchanged. Treatment with CGS 12970 did not affect endogenous creatinine clearance, methyoxy-(3)H inulin clearance, or glomeruli, however, CGS 12970 treatment significantly decreased urinary excretion of protein and thromboxane B2 when compared with values in the control group. These findings suggested that thromboxane has a role in the pathogenesis of established glomerulonephritis and that thromboxane synthetase inhibition treatment may be beneficial in dogs with established glomerulonephritis.

To determine the role of thromboxane A2 in the pathogenesis of experimentally induced immune complex glomerulonephritis, 12 concanavalin A-immunized Beagles were infused with 1 mg of concanavalin A via each renal artery and treated twice daily for 8 days with either 30 mg of CGS 12970/kg, PO, a specific thromboxane synthetase inhibitor, or placebo. The effect of treatment was assessed by measuring endogenous creatinine clearance and urine protein and eicosanoid excretion, and by evaluating changes in glomerular morphometric characteristics. On postinfusion day 8, urine protein, thromboxane B2, and 11-dehydro-thromboxane B2 excretion, glomerular epithelial crescent formation, and glomerular cell proliferation in the CGS 12970-treated dogs were significantly decreased when compared with values in the placebo-treated group. Differences were not observed in endogenous creatinine clearance, urine prostaglandin E2 and 6-keto-prostaglandin F1 alpha excretion, or glomerular polymorphonuclear leukocyte infiltration between groups in this study. These findings suggest thromboxane A2 has a role in the development of immune complex glomerulonephritis and that thromboxane synthetase inhibition may be beneficial in attenuating some of the functional and histologic changes associated with immune complex glomerulonephritis.