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  • Author or Editor: Lawrence H. Arp x
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SUMMARY

Sera and tracheal washings (tw) were used to identify antigens of Bordetella avium recognized during experimentally induced bordetellosis in young turkeys. Pooled sera and tw were examined for antibody by a microtitration agglutination test and by western immunoblotting. In addition, comparable samples collected from 1-day-old turkeys and uninoculated control turkeys also were examined. At least 8 outer membrane proteins of B avium were recognized in immunoblots of sera and tw from infected turkeys. Reactivity of tw in immunoblots was qualitatively similar but less intense, compared with reactivity of corresponding sera collected on postinoculation (pi) weeks 2, 3, and 4. Molecular weights of the major outer membrane proteins of B avium recognized by sera and tw at pi week 4 were 100,000, 97,000, 36,000, 31,000, 21,000, 18,000, 14,000, and < 14,000. A protein with a molecular weight of 55,000 reacted nonspecifically in all samples tested. Antibody, detectable by microtitration agglutination, was in sera of 1-day-old turkeys and in sera and tw of B avium-infected turkeys during pi weeks 2 to 4.

Free access
in American Journal of Veterinary Research

SUMMARY

Conjunctiva-associated lymphoid tissue (calt) in the eyelids of chickens was studied by gross, histologic, and electron microscopic techniques. Structural features were characterized at 1 day of age and at posthatching week (phw) 1, 2, 3, 4, 6, 8, 12, and 16. Beginning at phw 1, prominent lymphoid nodules containing a heterogenous population of lymphocytes, lymphoblasts, and macrophages were first observed within conjunctival folds and fissures of the lower eyelid. Nodules contained germinal centers by phw 2 and plasma cells by phw 4. The epithelium associated with these nodules was flat, had short, irregular microvilli, contained intraepithelial lymphocytes, and lacked goblet cells. High endothelial venules were located at the base of lymphoid nodules and contained lymphocytes within and below the cuboidal endothelium. In the upper eyelid, calt was morphologically similar to lymphoid tissue in the lower eyelid, but nodules were smaller and more random, lacked association with epithelial folds and fissures, and were clustered around the opening of the nasolacrimal duct. By phw 12, calt was characterized by basal germinal centers outlined by collagenous stroma, suprafollicular plasma cells, columnar epithelium with goblet cells, and fewer intraepithelial lymphocytes. On the basis of these features, calt in chickens has morphologic characteristics similar to other components of the mucosal immune system and, therefore, may have a role in mucosal immunity.

Free access
in American Journal of Veterinary Research

Summary

An experimental model for subclinical edema disease was developed in weanling pigs. In multiple experiments, 3-week-old pigs were weaned, then inoculated intragastrically with 1010 colony-forming units of an SLT-IIv-positive strain of Escherichia coli originally isolated from a pig with edema disease (principals). Control pigs were inoculated with a nonpathogenic E coli strain. Of 39 principals, 8 developed clinical edema disease within 14 days after inoculation. However, 20 of 21 principals that did not develop clinical signs of edema disease, but were submitted for necropsy examination at 14 days after inoculation, had characteristic vascular lesions of edema disease. Vascular lesions, found principally in ileum and brain, consisted of segmental necrosis of myocytes in the tunica media of small arteries and arterioles. None of the pigs inoculated with a nonpathogenic strain of E coli developed edema disease or vascular lesions. None of the principals necropsied at 2 days after inoculation had vascular lesions. Development of vascular lesions by 14 days after inoculation was used as the end point for detecting subclinical edema disease in the model.

Free access
in American Journal of Veterinary Research

SUMMARY

The growth hormone (gh) secretagogue activity of variable dosages of clonidine (16.5, 50, 150, and 450 μg/kg of body weight), given orally mixed with the daily food ration, was evaluated in young and old dogs. Significant (P < 0.05) increase in plasma gh concentration was detected at all dosages tested in young dogs and in response to all but the lowest dose tested in the old dogs fed the clonidine-containing diet. Old dogs had plasma gh concentration that exceeded that of young dogs when higher doses of clonidine were used.

A clonidine (100 μg/kg)-supplemented diet was fed to middle-aged dogs twice daily for 30 days. Significant (P < 0.01) increase of plasma gh concentration was observed on the first day of the feeding trial, but was undetectable by day 30. After feeding the clonidine-enhanced diet for 30 days, the effects on thymic morphology were variable, and there was no effect on plasma thymulin titer. Clonidine-fed dogs had significantly increased lymphocyte blastogenic responsiveness to mitogens, compared with that of control dogs, when evaluated as stimulation index.

Free access
in American Journal of Veterinary Research