Biomedical subjects
Publications and source records attributed to A Silvers.
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In 1994-1995, the Electric Power Resource Institute (EPRI) undertook a major national survey of time in microenvironments with 1200 respondents aged 18 and older. It did so using a methodology that minimized the problems of respondent recall and reporting by the use of a "time diary," in which survey respondents reported in detail about their actual activities "yesterday" including time spent outdoors. In addition, respondents were asked questions about the extent of contact with soil they had on that day. Significant proportions (20%) of the American public reported coming in direct contact with soil on a typical day and those who did come in contact were exposed for about 1.7 h per day; some 6% of the public reported being exposed for more than 2 h on the day in question, mainly by hand (although 3% of respondents reported soil contact with their head or face). As expected, men reported far more soil contact than women; surprisingly few consistent differences were found by age, or by marital status, parental status or employment status. Contrary to expectations, higher contact was not reported by minorities, or by less educated or less affluent respondents. Moreover, these patterns generally remained unchanged after adjustment for other demographic predictors. More as expected, higher exposure was reported in the Spring months, on weekends, and in rural areas and in the South and West regions of the country, patterns again largely unaffected by multivariate controls for other predictors. In general, while certain predictors of soil exposure were much the same for time spent outdoors, there were some notable exceptions.
OBJECTIVE: To present two cases of probable lymphoepithelial cysts of the submandibular glands in patients who were human immunodeficiency virus (HIV) positive and who also had lymphoepithelial cysts of the parotid glands. MATERIALS AND METHODS: Computed tomography and MRI of two HIV positive patients with lymphoepithelial cysts of the parotid glands and cysts in the submandibular glands were correlated with the histories and the possible presence of other known causes of submandibular gland multiple cysts. RESULTS: Because of the present treatment philosophy regarding HIV positive patients with major salivary gland cysts, surgical resection of these glands was not performed. All other known causes of multiple submandibular gland cysts were excluded by either history or laboratory data. CONCLUSION: Computed tomography and MRI on two patients with known HIV infection and bilateral parotid lymphoepithelial cysts are presented. Both patients also had bilateral multiple submandibular gland cysts and no evidence of obstructive glandular disease, autoimmune disease, or other organ system cysts. These cases of presumed submandibular gland lymphoepithelial cysts are rare in the literature. They are presented in the hope that other radiologists will be stimulated to document the occurrence of this entity.
The sequence of events that predispose to the onset of sinusitis are usually attributed to pathophysiologic factors within the ostiomeatal complex. Ostial compromise or obstruction with reduced clearance of antral pathogens has been implicated as a major factor that contributes to early sinus disease. Recent work in this laboratory has indicated that other processes may also contribute to this cascade. Using an infectious model in rabbits, the role of nasal obstruction in early, acute sinusitis was studied. Unilateral nasal closure was followed by bilateral inoculation with 10(8) CFU of Streptococcus pneumoniae type 3. Antral gas composition was examined on days 1, 2, 3, 5, 7, and 14, and swabs obtained for culture. Representative rabbits underwent CT scans to evaluate changes in nasal and sinus mucosa. Results showed a significant increase in CO2 and a trend toward a decrease in O2 on the obstructed side. There was also a significant decrease in obstructed CO2 levels from postoperative days (POD) 1-14. Acute sinusitis was not observed in any animal: however, nasal obstruction gave rise to a dramatic prolongation of bacterial retention. On days 2-7 bacteria was consistently cultured from the obstructed side only. CT scans on POD 2 and POD 3 showed mucosal thickening in the sinus and infundibulum on the obstructed side, indicative of sinus pathology. These results indicate that nasal obstruction may be a key factor in the cascade of events that predispose to the onset of sinus disease.