Epithelioid sarcoma in a dog.

A tumour in an 11-year-old male crossbred Fox Terrier, showing the clinical and pathological features of epithelioid sarcoma in man is reported. Clinical aspects, location, peculiar pattern of spread and evolution, together with histopathological and immunohistological findings of this rare tumour simulating a granuloma are described. Controversial histogenesis is discussed.     

Release of soluble transferrin receptor from the surface of human leukemic HL60 cells

Information regarding transferrin (Tf) receptor degradation is largely incomplete. HL60 cells were shown to release to their growth medium a Tf-binding protein which could be immunoprecipitated by anti-Tf receptor monoclonal antibodies (MoAbs) B3/25 and OKT9. Soluble Tf receptor was detected in the medium within one hour of replating of cells, and its release was inhibited at 4 degrees C. The affinity of Tf for the soluble receptor released by cells (kd = 2.3 x 10(-10) mol/L) was slightly lower than its affinity for the detergent-solubilized cellular receptor (kd = 1.2 x 10(-10) mol/L). 125I-Tf internalized and released by cells subsequently bound to Tf receptor released by the same cells, and soluble Tf receptor in the conditioned medium (CM) inhibited 125I-Tf binding to intact cells. The soluble Tf receptor isolated from the CM was smaller (78,000 daltons) than the cell surface receptor (94,000 daltons) when analyzed by gel electrophoresis under reducing conditions. Isolated cell membranes readily released soluble receptor; however, this release could be blocked by protease inhibitors. The soluble Tf receptor may represent the extracytoplasmic domain of the cellular Tf receptor released from the surface of HL60 cells through proteolytic cleavage by a membrane-based protease.     

Nitric oxide mediates the neurogenic vasodilation of bovine cerebral arteries

Nitric oxide (NO) is a mediator of the vasodilation induced by a variety of physiological and pharmacological stimuli. The possible role of NO in the relaxation elicited in cerebral arteries by perivascular nerve stimulation has been investigated. Electrical field stimulation of precontracted bovine cerebral arteries induced a relaxation that was blocked by tetrodotoxin, but not by adrenergic or muscarinic receptor antagonists, suggesting the existence of noradrenergic, noncholinergic dilator nerves, as has been shown in other species. The relaxation was significantly reduced by the inhibitors of NO synthesis, NG-monomethyl-L-arginine and nitro-L-arginine methyl ester, but not by the enantiomer, NG-monomethyl-D-arginine. Such a reduction was reversed by L-arginine. In addition, transmural nerve stimulation (TNS)-induced relaxation was potentiated by superoxide dismutase. No response to TNS was observed in arteries without endothelium. These results suggested that neurogenic relaxation of bovine cerebral arteries is mediated by endothelium-derived NO.     

Pneumothorax and other lung diseases: effect of altered resolution and edge enhancement on diagnosis with digitized radiographs

Prior studies have shown that pneumothorax is one of the more difficult entities to diagnose with digitized radiography. This study was designed to test whether increasing resolution from 1.25 to 2.5 line pairs per millimeter (lp/mm) and image processing (edge enhancement from unsharp masking) would increase accuracy and confidence in the diagnosis of pneumothorax, as well as normal cases and other forms of lung disease. Conventional radiographs were digitized with use of a laser reader and then reformatted as film hard copy. Eleven observers read 35 cases reformatted in three different ways (1.25 lp/mm, 2.5 lp/mm, 1.25 lp/mm unsharp mask). The images with finer resolution (2.5 lp/mm) and unsharp mask images were superior to those with coarser resolution (1.25 lp/mm) for the diagnosis of pneumothorax. There was no difference in diagnostic accuracy for normal patients. For abnormalities other than pneumothorax, the unsharp mask images were significantly worse. Confidence in the diagnosis of pneumothorax and other abnormalities was highest with the finest resolution (2.5 lp/mm).