Biomedical subjects
Publications and source records attributed to D M Webb.
A 1-week-old Jersey bull calf with a history of diarrhea, weakness, and lethargy was submitted for necropsy. Principal macroscopic findings were enteritis and multifocal necrotizing hepatitis. Histologically and ultrastructurally, organisms with characteristics of Bacillus piliformis were associated with the foci of necrosis in the liver.
A 10-week-old, black buck antelope calf, from the Mesker Park Zoo in Evansville, Indiana was found dead without observed signs of illness. Necropsy disclosed disseminated ecchymoses on the pericardium, diaphragm, intestines, and renal capsules and more extensive hemorrhage in the muscles of the hindquarters. There were numerous, 1 mm, pale foci on the capsular and cut surfaces of the liver and spleen which, on microscopic examination, were necrotic foci containing variable numbers of neutrophils and mononuclear leukocytes with numerous, short, Gram-positive, cocco-bacilli at the periphery. Listeria monocytogenes was isolated from the liver. Septicemia is the most common form of listeriosis in non-domestic ruminants. Listeriosis should be suspected when unexpected deaths are accompanied by multifocal necrotizing hepatitis and splenitis, myocarditis, and disseminated hemorrhage.
A technique is described to allow electron microscopic investigation of a specific feature of a section on a glass slide. A section on a glass slide (previously treated with a silicone release agent) is processed as required for light microscopy. The section is then impregnated with Araldite and cured with an epoxy resin block on top of it. The section and block are removed from the slide and viewed with a light microscope. The selected area for ultrastructural study remains under continuous observation while the block is trimmed. Semi-thin (1 micron) sections retain the original staining for light microscopy and ultra-thin sections are stained with heavy metals in the normal manner. We show how an inflammatory lesion in a large area of muscle in a case of polymyositis may be quickly located and studied at the ultrastructural level.
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Furazolidone induces a cardiotoxicosis when fed in toxic concentrations to newly hatched ducklings. This preliminary experiment was designed to determine if creatine kinase (CK) isoenzymic activities or other serum analytes would be useful as indicators of these cardiac alterations. Sera from 12 ducklings (six fed a control ration and six fed the control ration with 700 mg furazolidone added per kg of feed [700 ppm] for 28 days) were analyzed for CK isoenzymic activities, electrolytes, nitrogenous metabolites, hepatic enzymic activities, bilirubin, and glucose. Statistically significant differences between control and treated groups were detected for creatine kinase MB (CK-MB, cardiac muscle origin) isoenzymic activity and bilirubin, potassium, calcium, and total carbon dioxide concentrations. Differences other than CK-MB isoenzymic activity were generally explained by factors related to the toxicosis or sample handling. These findings suggest that CK-MB isoenzymic activity may be useful to detect and monitor the progress of cardiac injury in furazolidone toxicosis, thereby increasing the usefulness of this model of dilated cardiomyopathy. Our findings, analyzed on the Kodak Ektachem 700 Dry Chemistry Analyzer, are compared with serum chemistry values reported in the literature.
Cystic testicular degeneration was induced in groups of ducklings by feeding furazolidone at 250, 400, 550, or 750 mg per kilogram of feed (ppm) for 4 weeks. In normal ducklings, tall, columnar Sertoli cells predominated in the seminiferous epithelium. In treated ducklings, the mildest ultrastructural alteration was cytoplasmic vacuolation of Sertoli cells. In birds with more severely affected tubules, cytoplasmic vacuolation was more severe and the cells were cuboidal or rounded. The rounded cells desquamated into the tubular lumens, eventually undergoing cytolysis. In birds with the most severely affected tubules, only extensively flattened epithelial cells lined the extremely dilated seminiferous tubules. The interstitium was edematous and compacted between the expanded tubules. Many of the testicular ultrastructural alterations in furazolidone-intoxicated ducklings were similar to those described in the testicles of sodium-intoxicated cockerels.
Cystic testicular tubular dilatation was seen in ducklings fed a ration containing furazolidone at 250, 400, 550, or 700 ppm for 28 days. Gross evidence of cystic testicular dilatation was observed at necropsy in 16% (32/203) of the ducklings that survived to the end of the study. Gross testicular lesions consisted of various degrees of enlargement with increased translucency in moderately to severely enlarged testicles. Histological evidence of cystic testicular dilatation was present in 45% (41/91) of the testicles examined. Histologically, the tubules were in various states of dilatation with attenuation of the seminiferous epithelium proportional to the severity of dilatation. In the most severely affected testicles, tubules were greatly dilated, distorted, and fluid-filled, with extensively flattened epithelium visible on the inner margin of the tubule as a thin rim of cytoplasm with a protuberant nucleus. Interstitial tissues were compressed to thin septa between the dilated tubules.
Spirochetes similar to those described in the ceca of broilers with diarrhea and in laying hens with decreased egg production and growth were identified in the ceca of captive-raised juvenile ring-necked pheasants (Phasianus colchicus). The birds were submitted for diagnostic investigation of an illness characterized by a seromucoid ocular discharge, sneezing, swollen infraorbital sinuses, and weight loss. In addition to cecal spirochetosis, the birds had mild enteric coccidiosis, trichomoniasis, and nematodiasis (Heterakis spp.); esophageal capillariasis; and respiratory mycoplasmosis. Weakly beta-hemolytic spirochetes isolated from the ceca of one pheasant were identified as Serpulina pilosicoli with the use of a 16S rRNA sequence-specific polymerase chain reaction amplification assay. Diffuse cecal enterocyte attachment was reproduced in a 1-day-old chick challenged with the pheasant S. pilosicoli isolate. Immunohistochemical staining of sections of ceca from the pheasant and challenged chick with a Serpulina spp. flagellar antigen-specific monoclonal antibody confirmed spirochetal attachment to cecal enterocytes. The etiologic significance of the spirochete infection is unknown because respiratory signs and multiple gastroenteric pathogens dominated the clinicopathologic manifestations and an intestinal disorder was not a clinical complaint.