RESUMEN
Cardiovascular changes associated with indwelling catheters were evaluated in 51 adult beagle dogs catheterized for 4 to 9 weeks. Pathologic changes consistent with traumatic injury were in the vena cava and endocardium of the right atrium of 88% of cannulated dogs. Lesions were characterized by surface denudation and diffuse intimal thickening due to myointimal hyperplasia and deposition of extracellular matrix. Affected intima was lined by hyperplastic, poorly differentiated endothelial cells and contained round to oval cells with characteristics of smooth muscle cells. After 9 weeks, thickened intima was vascularized and composed of spindle-shaped cells and fibrillar stroma. Intimal sclerosis and localized proliferative papillary projections in the vena cava cranial to areas of myointimal hyperplasia occurred infrequently. Traumatic lesions, regardless of location or severity, did not extend below the internal elastic membrane. Inflammatory cellular responses, when present, were minimal. The location, distribution, and morphogenesis of catheter-related cardiovascular lesions distinguishes them from those induced by chemical toxicity or pharmacotoxicity.
Asunto(s)
Enfermedades Cardiovasculares/veterinaria , Cateterismo Periférico/veterinaria , Enfermedades de los Perros/etiología , Endocardio/patología , Venas Cavas/patología , Animales , Enfermedades Cardiovasculares/etiología , Enfermedades Cardiovasculares/patología , Cateterismo Periférico/efectos adversos , Catéteres de Permanencia/efectos adversos , Catéteres de Permanencia/veterinaria , Enfermedades de los Perros/patología , Perros , Femenino , Atrios Cardíacos/patología , Venas Yugulares , Masculino , Microscopía Electrónica , Microscopía Electrónica de Rastreo , Venas Cavas/ultraestructuraRESUMEN
The association of Treponema hyodysenteriae with porcine caecal and colonic mucosal surfaces was studied by electron microscopy after orogastric inoculation of pigs with pure cultures. Examination of caecal and colonic mucosa from infected and control animals revealed that large numbers of the spirochaete were associated only with intestinal mucosal surfaces of infected animals. Further examination of the intestinal mucosa from infected pigs showed that T. hyodysenteriae colonized two sites preferentially: the mucus-filled crypts of Lieberkühn and the mucus gel covering the epithelium. Furthermore, no evidence of either specific or nonspecific adhesion to the epithelium proper was found, suggesting that penetration of, or trapping in the mucus gel may be the predominant mechanism of mucosal association by T. hyodysenteriae. Moreover, T. hyodysenteriae was also observed to be highly motile in intestinal mucus, moving faster than any other organism present, and this 'high speed' motility appeared to facilitate penetration into the mucosa. The pattern of motility observed was also highly suggestive of chemotaxis, and this was subsequently confirmed using an in vitro assay to porcine mucus material. It is suggested, therefore, that motility and chemotaxis are important factors/mechanisms in the association and colonization of porcine intestinal mucosa by T. hyodysenteriae.