The role of stress in inflammatory bowel disease remains debated and few studies have tested the role of stress in conjunction with experimental animal models of colitis. In this investigation we tested the hypothesis that cold-restraint stress would adversely effect the severity of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats, and examined mechanisms for the response. Results indicated that increasing intermittent prior exposures to stress significantly enhanced TNBS-induced colitis severity. An associated stress-induced decrease in colonic mucin glycoprotein content, reduction in goblet cells, and histochemical mucin suggested reduced mucin was a pathogenetic factor. Myeloperoxidase content increased and mast cell counts in the colon decreased but colonic permeability only temporarily increased with increasing stress exposure. Prior adrenalectomy or administration of an adrenergic blocking agent did not prevent the colonic changes to stress, but mast cell stabilization or inhibition of cholinergic pathways reduced the stress-induced colonic changes.

Adrenalectomy↗

PubMedDate not supplied

Spontaneous thyroid-containing teratoma associated with impaired development in the African clawed frog, Xenopus laevis.

Teratomas are rare in amphibians and the neoplasm described here, which had a significant thyroid carcinoma component, is the first tumour of this type to be reported in Xenopus laevis. The thyroid component contained moderately to well-differentiated acinar glands showing much hyperplasia, dysplasia, and reduced and distorted colloid reservoirs. Cartilaginous, neural, muscular, mesenchymal and gut-like epithelial components were also observed in this ventral mediastinal neoplasm, indicating aberrant proliferation from all three germ layers. This teratoma was only one abnormality in a complex of developmental changes, followed for 28 months, which appeared in a single generation of sibling 2-week-old Xenopus larvae. Two hundred larvae produced by an apparently normal adult pair initially showed ocular defects, including microphthalmia, anophthalmia and tumours projecting near the eyes. During further development up to 28 months, mediastinal tumours developed in nine frogs; these tumours were associated with reduced growth, the frogs reaching only 13-20% of normal weight, and greatly enhanced ventral pigmentation.

Animals↗

PubMedDate not supplied

Ethanol-induced gastric mucosal damage in the rat with Taenia-stimulated hypertrophic gastropathy.

The susceptibility to ethanol-induced lesions was studied in rats with experimental hypertrophic gastropathy, in order to examine the nature of gastric mucosal resistance in this condition. Acute erosions were induced by a standard per os method of administration with graded concentrations of ethanol; underlying mucosal hypertrophic gastropathy was induced by infection with Taenia taeniaeformis. The gastric mucosal content of histamine and serotonin was also assessed. Hypertrophic gastropathy was characterized by mucus cell hyperplasia, greatly increased stomach weight, increased mucosal content of histamine, and no effect in resistance to gastric injury induced by graded doses of ethanol. Correlated changes in serotonin content with treatment were not observed, but mucosal histamine content was correlated inversely with ethanol administration in both parasite-infected and non-infected rats. This model of hypertrophic gastropathy could be of interest to study the pathogenesis of hypertrophic gastropathy and its response to known injurious agents.

Animals↗

PubMedDate not supplied

Bloodletting in the horse: a therapeutic modality in the early to mid-nineteenth century.

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History, Modern 1601-↗

PubMedDate not supplied

Cytopathology induced by mercuric chloride and methylmercury in cultured renal cells of the Atlantic spotted dolphin (Stenella plagiodon).

High mercury concentrations have been reported in various tissues of cetaceans, but the toxicological effects of mercury on cetaceans remain unclear. In vivo study is difficult due to the endangered status of these marine mammals and co-exposure to both mercury and selenium (antagonist of mercury) in the oceanic environment. The present data are the first ultrastructural information on dolphin renal cells exposed to mercury in vitro. Multiple organelle changes were observed in Atlantic spotted dolphin (Stenella plagiodon) renal cells treated with mercuric chloride (HgCl2) or methylmercury chloride (MeHgCl2). Mitochondria and rough endoplasmic reticula were swollen after treatment with HgCl2 or MeHgCl. Mitochondrial dense bodies and small cytoplasmic spherical granules of high electron density were also observed after exposure to MeHgCl. Cytoplasmic vacuoles and myelin-like figures were induced by both HgCl2 and MeHgCl. Nuclear changes included karyolysis, nuclear buds, and a novel observation in mercury-treated cells, vacuolization of (micro-)nucleoli after treatment with HgCl2. These morphological changes (multiple organelle damage and nuclear budding) indicated mercury-treated dolphin renal cells underwent oncosis and necrosis, and supported earlier pathophysiologic findings of diverse toxic actions on genetic, respiratory and other cellular functions.

Animals↗