Organization of polyoma virus DNA in mouse tumor cell lines

Summary Restriction mapping of polyoma virus DNA in mouse tumor cell lines gave patterns that varied with the cell line examined. These reflected differences in both the organization and the state of integration of virus genomes in the host chromosomes. (The cell lines were derived from tumors induced by polyoma virusin vivo and were propagated continuously in culture.) Two of the cell lines contained multiple copies of tandemly integrated virus genomes as well as free virus DNA molecules. Two other cell lines appeared to contain only integrated virus genomes arranged as tandem repeats. Based on restriction analysis with eleven different endonucleases, the virus DNA in one of the cell lines containing both free and integrated virus genomes was not detectably defective or hypermethylated. This is in contrast to most previously described polyoma virus transformed mouse cells. These virus genomes may, however, contain point mutations or unobserved rearrangements. The second cell line possessing free virus DNA molecules contained both nondefective and defective virus genomes. Most, if not all, defective virus genomes in this line were integrated. The two other cell lines possessing only detectable integrated virus DNA apparently contained only defective virus genomes. The defect in both cases was a small deletion (0.2 kb) encompassing 0.12 map units on the physical map of polyoma virus DNA, a region coding for the proximal part of the large T antigen. Moreover, in contrast to the cell lines with free and detectably nondefective virus DNA, the virus DNA was extensively methylated in cell lines containing only integrated and defective virus genomes.With 6 Figures     

Soft tissue sarcomas: ultrasonographic evaluation of local recurrences

OBJECTIVE: The diagnosis of early local recurrence of soft tissue sarcomas, especially in those treated with surgery and radiotherapy, is a difficult clinical problem. Financial constraints led us to use ultrasonography instead of CT or MR imaging. The aim of this study was to evaluate the role of ultrasonography (US) in detecting local recurrence. METHODS AND RESULTS: Fifty patients with previous treatment for soft tissue sarcomas were evaluated prospectively for recurrence by US and histopathology. Seven of the 50 patients were clinically suspected to have recurrent tumour. Ultrasonography showed recurrence in 26, no recurrence in 18, benign disease in four and was indeterminate in two cases. Ultrasonography was instrumental in guiding fine needle aspiration biopsies of small local recurrences and indeterminate lesions in 17 patients. In the sonographically tumour positive patients, histopathology confirmed recurrence in 24; one case had benign disease and one patient refused surgery. Thirteen of the 18 sonographically tumour negative patients were operated upon; all were negative for tumour on histopathology. Both the indeterminate cases showed recurrence on histopathology. The benign cases were confirmed by histopathology correlation. Ultrasound guided fine needle aspiration cytology (FNAC) was positive in 14 out of 17 patients (88%). The sensitivity and specificity of US was 92.30% and 94.4% respectively. CONCLUSION: Our study concludes that US is an extremely useful and cost effective method in the detection of early local recurrences of soft tissue sarcomas and should therefore be used for initial routine follow-up and guided biopsies.     

The use of perioperative Sofradex® eardrops in preventing tympanostomy tube blockage: a prospective double‐blinded randomized‐controlled trial

Around 11–12% of tympanostomy tubes are reported to become blocked by middle ear secretions or blood immediately following surgery, and so no longer function. Many otologists routinely instil an antibiotic and steroid‐containing solution at the time of surgery in the belief that this may reduce this complication. The aim of the study was to investigate the efficacy of instilling the antibiotic and steroid‐containing solution Sofradex^® at the time of grommet insertion in preventing grommet blockage. Double‐blind randomized‐controlled trial, comparing rates of grommet blockage in ears treated with Sofradex^® drops against control (no drops) in patients undergoing bilateral grommet insertion. Sixty‐one pairs of results were obtained. There was a significant difference between the rates of grommet blockage in the two groups. Grommets with Sofradex^® drops instilled perioperatively were nine times less likely to be blocked than controls [1.6%versus 13.1%, odds ratio (Sofradex^®/control) = 9.06, 95% confidence interval (CI): 1.04–78.82, P = 0.05]. There was no association between grommet blockage and perioperative bleeding or the nature and presence of middle ear secretions. Sofradex^® eardrops are effective in reducing the rate of grommet blockage when instilled perioperatively.