Tetramesityldisilene, a stable compound containing a silicon-silicon double bond

Irradiation of 2,2-bis(2,4,6-trimethylphenyl)hexamethyltrisilane in hydrocarbon solution produces tetramesityldisilene, which can be isolated as a yellow-orange solid stable to room temperature and above in the absence of air. Like the olefins of carbon chemistry, tetramesityldisilene undergoes addition reactions across the silicon-silicon double bond.

The adequacy of cytology and colposcopy in diagnosing cervical neoplasia in HIV-seropositive women

The purpose of this study was to compare cytology and colposcopy as predictors of cervical intraepithelial neoplasia (CIN) in women infected with the human immunodeficiency virus (HIV). A cross-sectional analysis of cytology, colposcopy, and colposcopic biopsy results from 51 HIV-seropositive women attending an ambulatory HIV service was conducted. Cytology slides were reviewed by two cytopathologists blinded to patients' HIV status. There was strong agreement in the readings of two cytopathologists, with a kappa score of 0.9. Of 29 women with normal cytology, 21 (72%) had pathology on histology, including 7 (24%) with CIN. Colposcopic impression correlated well with histology results. Of 22 women with abnormal cytology, 82% had abnormal histology. The overall prevalence of CIN was high at 45%, increasing from 35% in women with CD4 counts over 400 to 56% in women with CD4 counts below 200. In conclusion, screening cytology is limited by false-negative results; routine colposcopy should be considered in this high-risk population.