Bovine respiratory syncytial virus (BRSV) is a major cause of respiratory disease in young cattle. Here we demonstrate BRSV persistence at low levels in tracheobronchial and mediastinal lymph nodes up to 71 days after the experimental infection of calves. Positive results were obtained on viral genomic RNA and messenger RNA coding for the nucleoprotein, glycoprotein (G), and fusion protein (F). G and F proteins were also detected in the pulmonary lymph nodes by immunohistochemistry. Double-staining experiments revealed that viral antigen was present in B-lymphocytes. Coculture experiments with the lymph node cells showed that the virus was still able to infect permissive target cells, even though no cytopathic effect was recorded. In vitro studies indicate that BRSV was still able to replicate in bovine B-lymphocyte cell lines 6 months after infection. These results may also be relevant to the understanding not only of the epidemiology and the peculiarities of the immune response of BRSV infections but also of human respiratory syncytial virus infections.
Eighty-nine patients with clinical problems arising from the thoracic or abdominal aorta had computed tomography (CT) scans with contrast enhancement in addition to standard aortograms. Forty-four patients had aneurysms, 22 had aortic graft complications, and 23 had aortoiliac occlusion. CT scanning provided diagnostic information not apparent by conventional angiography in 39 patients (43.8%). This additional information did not significantly alter the operative management in 13 patients (14.6%). The helpful information provided by CT in these patients included demonstration of gallstones, renal cysts, anomalous venous structures, horseshoe kidney, and femoral anastomotic aneurysms. However, in 26 of 89 patients (29%), the additional data obtained by CT significantly changed the timing or approach to operative management. Management was altered in 12 of 44 patients (28%) with aneurysms, 7 of 22 patients (32%) with aortic graft complications, and 7 of 23 patients (30%) with aortoiliac occlusive disease or suspected distal thromboembolism. Specific information provided by CT included contained aortic aneurysm rupture, aortic dissection, laminated intraluminal thrombus or pseudointima, extent of perigraft infection, aortic atherosclerosis, anastomotic false aneurysm, and thrombus as a source of distal embolization. Thus, CT had a significant impact on operative management. It serves as a valuable adjunct to aortography in patients with complex aortic problems.
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