Four balance trials were conducted in 3 groups of 5 calves each at 0, 4, 8, and 14 weeks after initial inoculation with Ostertagia ostertagi. Group-1 calves were inoculated with 100,000 third-stage larvae (L3) of O. ostertagi/wk for 14 weeks. Group-2 calves were inoculated with 10,000 L3/wk for 14 weeks, and group-3 calves were not inoculated. Effects of infection on apparent digestibilities of dry matter and nitrogen, and balances of nitrogen and water were evaluated. Neither clinically apparent (group 1) nor subclinical (group 2) O. ostertagi infections had observable effects on the apparent digestibility of dry matter. Subclinical infection also had no significant effects on nitrogen digestibility or nitrogen and water balance. Clinically apparent infection, however, decreased the apparent digestibilities of nitrogen significantly (P < 0.05) at 4, 8, and 14 weeks after inoculation, and decreased nitrogen balance at 4 and 8 weeks after inoculation. Group-1 calves also had lower water intake, fecal-water excretion, and apparent water balance, but higher urinary water output at 4, 8, and 14 weeks after inoculation.

Paraherquamide, an oxindole alkaloid metabolite of Penicillium paraherquei and P. charlesii, is a new anthelmintic with potential broad-spectrum use. In initial trials, it had an excellent safety profile in cattle and sheep at doses efficacious against a dozen or more helminths, but recently it produced unexpected and severe toxicosis in dogs at doses far below those that were safe in the ruminants. To provide data on which to build rational safety tests in the future, we tested the acute toxicity of paraherquamide administered PO to male CD-1 mice and compared its profile with the most potent anthelmintic known, ivermectin. The estimated doses lethal to 50% of a group of mice were 14.9 and 29.5 mg/kg of body weight for paraherquamide and ivermectin, respectively. The no-effect doses were 5.6 and 18.0 mg/kg for paraherquamide and ivermectin, respectively. Signs of intoxication in paraherquamide-treated mice, if they developed, emanated within 30 minutes of administration, irrespective of dose, and consisted of either mild depression with complete recovery or a 5- to 10-minute period of breathing difficulty followed by respiratory failure and death by 1 hour after treatment. Gross necropsy findings in paraherquamide-treated mice that died in the high-dose group were normal. Ivermectin-related toxicity was slower and more predictable, taking place over a 3-day period, with dose-dependent signs of intoxication consisting of tremors, ataxia, recumbency, coma, and death. Necropsy of ivermectin-treated mice that died in the high-dose group revealed dehydration, a condition most likely resulting from the coma-induced state. These observations are congruent with clinical data from dog studies and suggest that if broad-spectrum use of ivermectin (expected to be approx 0.2 mg/kg) is unlikely because of idiosyncratic toxic effects in certain dogs, then use of a compound for dogs with an acute safety factor half of ivermectin, such as paraherquamide, would be even more unlikely. These data are also coupled with observations from anthelmintic trials to suggest that ivermectin possesses a substantially greater therapeutic index than does paraherquamide as a broad-spectrum antiparasiticide for ruminants. Although paraherquamide has a lesser therapeutic index, a strategic use for it as an anthelmintic against ruminant parasites that have become resistant to any or all of the other modern broad-spectrum anthelmintics can be suggested.

The effects of Actinobacillus (Haemophilus) pleuropneumoniae and its metabolites on the oxygenation activity of porcine pulmonary alveolar macrophages (PAM) were studied, using a chemiluminescence technique. Actinobacillus pleuropneumoniae strains of serotypes 2, 3, and 9 in a dose of 1, 10, and 100 colony-forming units/ macrophage first stimulated the oxygen radical production of PAM. After having reached a peak value, oxygenation activity decreased, finally resulting in total suppression of PAM. All these effects were neutralized by homologous convalescent pig sera that had been adsorbed onto inactivated A pleuropneumoniae strains. Moreover, cross-neutralization was shown between serotypes 2 and 3. Inactivated A pleuropneumoniae strains did not influence the oxidative activity of PAM. Undiluted and lower dilutions of sterile A pleuropneumoniae culture supernatants were toxic for PAM, whereas higher dilutions of the supernatants stimulated oxygen radical production of the macrophages. These effects were heat-sensitive and were neutralized by homologous convalescent pig sera. Cross-neutralization was shown between serotypes 2 and 3. These findings indicated that stimulation and inhibition of the oxygenation activity of PAM are attributable to heat-sensitive metabolites produced by A pleuropneumoniae.

When Salmonella typhimurium and Clostridium perfringens were tested in conventional chickens, larger numbers of S typhimurium and C perfringens adhered to Eimeria tenella-infected ceca than to uninfected ceca. In germ-free chickens, S typhimurium and C perfringens adhered to the E tenella-infected cecal mucosa more than to the uninfected cecal mucosa, but fewer Bacteroides vulgatus and Bifidobacterium thermophilum adhered to the E tenella-infected ceca than to the uninfected ceca. Many bacteria adhered to the lesions caused by E tenella as observed by scanning electron microscopy. On the basis of our findings, we suggest that infection with E tenella upsets the balance of competitive adherence of bacteria, allowing more colonization of S typhimurium and C perfringens.

Using biodegradable pins, sternal cartilage autografts were fixed into osteochondral defects of the distal radial carpal bone in ten 2 to 3-year-old horses. The defects measured 1 cm2 at the surface and were 4 mm deep. Control osteochondral defects of contralateral carpi were not grafted. After confinement for 7 weeks, horses were walked 1 hour daily on a walker for an additional 9 weeks. Horses were euthanatized at 16 weeks. Half of the repair tissue was processed for histologic and histochemical (H&E and safranin-O fast green) examinations. The other half was used for the following biochemical analyses: type-I and type-II collagen contents, total glycosaminoglycan content, and galactosamine-to-glucosamine ratio. On histologic examination, the repair tissue in the grafted defects consisted of hyaline-like cartilage. Repair tissue in the nongrafted defects consisted of fibrocartilaginous tissue, with fibrous tissue in surface layers. On biochemical analysis, repair tissue of grafted defects was composed predominantly of type-II collagen; repair tissue of nongrafted defects was composed of type-I collagen. Total glycosaminoglycan content of repair tissue of grafted defects was similar to that of normal articular cartilage. Total glycosaminoglycan content of nongrafted defects was 62% of that of normal articular cartilage (P < 0.05). Repair tissue of all defects was characterized by galactosamine-to-glucosamine ratio significantly (P < 0.05) higher than that of normal articular cartilage. These results at 16 weeks after grafting indicate that sternal cartilage may potentially constitute a suitable substitute for articular cartilage in large osteochondral defects of horses.

An ELISA was developed and tested to detect antibodies to Eperythrozoon suis in swine. Results were compare with those of the indirect hemagglutination (IHA) test. Antigen isolated from swine heavily infected with E suis was used for both tests. Comparison of the ELISA with the IHA test revealed a significant (P < 0.001) correlation between results. Of 114 samples obtained from 9 swine infected with E suis, 8 7.7% were seropositive (titer greater than or equal to 200) via the ELISA, and 80.7% were seropositive (titer greater than or equal to 20) via the IHA test. The sensitivity of the ELISA was greater than that of the IHA test. All blood samples obtained from specific-pathogen-free swine tested negative for E suis antibody. Cross-reactions were not observed between E suis antigen and antisera against various swine and cattle disease agents using ELISA. We concluded that the ELISA may be used for rapid and effective diagnosis of infection with E suis in swine.

The role of silage feeding in the origin of an epizootic of encephalitic listeriosis in a sheep flock was investigated by use of a new direct Listeria-selective isolation and enumeration medium, in combination with serotyping and phage typing. The silage contained high numbers (about 10(6) cells/g) of a L monocytogenes strain indistinguishable with respect to serovar and phagovar from that isolated from the brains of sick sheep. These results provided unambiguous bacteriologic evidence of the epidemiologic link between silage consumption and listeriosis in ruminants.

An efficient, single-step method for purification of the 110-kilodalton (kDa) hemolysin of Actinobacillus pleuropneumoniae was developed. An immunoaffinity column was made by cross-linking murine monoclonal antibody 8C2 to the 110-kDa hemolysin of A pleuropneumoniae strain J45 serotype 5 to protein A-agarose beads. Purified hemolysin with high hemolytic activity was obtained after washing the column with phosphate-buffered saline solution, and eluting the hemolysin with 50 mM diethylamine, pH 11.0. The same column was also used to purify the hemolysin from A pleuropneumoniae strain 4074 serotype 1. The purification procedure could be completed within 5 hours, and almost 50% of the total hemolytic activity and hemolysin protein was recovered in pure form.

Ten multiparous sows were inoculated between 46 and 50 days of gestation with a fetal swine isolate of encephalomyocarditis virus (EMCV) to investigate the ability of the virus to cause transplacental infection and fetal death. Four sows (group 1) were inoculated IM with EMCV MN-25 that had been passaged 4 times on baby hamster kidney-21 line cell monolayers. Two sows were euthanatized at postinoculation (PI) day 23, and the other 2 sows at PI day 44. An additional 6 sows (group 2) were inoculated IM with the same virus that had been passaged 5 additional times in pigs. Two sows were euthanatized at 14 days, and the remaining 4 sows at PI day 28. Clinical signs were not observed in any of the sows, whereas all sows seroconverted to EMCV. In group 1, only 2 of 50 fetuses were mummified. Virus was not recovered, although EMCV antibodies were detected in the 2 mummified fetuses. In group 2, the 2 sows that were euthanatized at PI day 14 had 26 normal fetuses and there was no evidence of fetal infection. However, in the 4 sows euthanatized at PI day 28, 20 of 48 fetuses were mummified, hemorrhagic, or edematous. Encephalomyocarditis virus was recovered from 21 of 48 fetuses. Transplacental infection and fetal deaths in pregnant sows was achieved following infection with EMCV passaged in pigs.

A selected group of pharmaceutical compounds were evaluated for the ability to inhibit the biochemical activity of fibrinoligase (coagulation factor XIIIa) in pooled equine plasma. Criteria for the pharmaceuticals selected were based on the mechanism of the transglutamination biochemical reaction mediated by coagulation factor XIIa . These criteria were complemented by recognition of the molecular configuration and chemical composition of amino acid residue side chains involved in the process of covalent fibrin monomer polymerization (cross-linking, transglutamination) mediated by this enzyme. Each pharmaceutical was evaluated individually and in combination with other potential coagulation factor XIIIa inhibitors in an effort to detect additive and synergistic phenomenon. In this context, pharmaceuticals with a carbonylamide (eg, cefuroxime, Girard's reagent-P, prolinamide) were applied in concert with compounds with a terminal amine (eg, D-arginine, L-lysine) functional group. In concept, this method theoretically served to competitively simulate glutamine and lysine amino acid residues within strands of fibrin monomer substrate involved in phase I (carbonylamide) and phase II (terminal amine) of the transglutamination reaction (covalent fibrin monomer cross-linking). Halogen-dinitro and ethylene compounds were also evaluated because of their reported ability to inactivate enzyme systems dependent on an intact sulfhydryl group located at their biochemically active site (eg, cystine amino acid residue). This group of pharmaceutical compounds failed to inhibit the biochemical activity mediated by coagulation factor XIIIa in equine plasma.