Production of Altered Cell Foci by 3-Methylcholanthrene in Mouse Cells Infected with AKR Leukemia Virus

This report describes altered cell foci observed 9-14 days after treatment with 3-methylcholanthrene of mouse-embryo tissue cultures that had previously been infected with wild-type AKR (RNA tumor) virus. The foci consisted of randomly oriented, piled-up, spindle-shaped cells. When heavily stained with Giemsa, the colonies of transformed cells were grossly visible and countable. Under the same experimental conditions, such changes of morphology were not detectable in the uninfected cells treated with 3-methylcholanthrene or in untreated cells infected with virus. The procedure may provide a rapid, quantitative test system for measurement of the oncogenic potential of certain carcinogens. As in similar previous studies in rat and hamster cells, the results suggest that the infectious, but nontransforming, RNA tumor viruses provided nascent oncogenic information, which when activated by 3-methylcholanthrene served as the specific genetic determinants of transformation.     

Evaluation of the clinical usefulness of mycobacterial skin test antigens in adults with pulmonary mycobacterioses.

A double-blind, multicenter study was conducted to evaluate the usefulness of mycobacterial skin test antigens for the specific diagnosis of adult pulmonary mycobacterial disease. The skin test antigens used were PPD-T (M. bovis) and PPD-B (M. intracellulare), made bioequivalent to 5 TU PPD-S through bioassay in human subjects. Of the 192 adults (18 yr of age or older), those with disease caused by M. tuberculosis (MTB) had significantly larger reactions to PPD-T than did those with disease caused by nontuberculous mycobacteria (NTM) or those with negative culture results (NEG)(13.41 mm versus 4.87 and 4.96 mm, respectively, p less than 0.001). The mean induration to PPD-B in NTM was not different from that in MTB or NEG. Defining a "positive" to be greater than or equal to 10 mm induration and a size difference of greater than or equal to 3 mm between PPD-T and PPD-B, the sensitivity, specificity, and positive predictive value (PPV) for PPD-T in diagnosing MTB versus NTM was 29, 90, and 75%. Corresponding values for PPD-B and NTM disease were 70, 61, and 64%. Dual testing was less useful in distinguishing disease caused by any of the mycobacteria from NEG. Although the sensitivity of PPD-B, made bioequivalent to PPD-S, was high, the specificity and PPV were low. We conclude that this preparation of PPD-B is no more useful in distinguishing adult pulmonary disease caused by NTM than is PPD-T alone.     

Parental Monitoring,Parent–Adolescent Communication About Sex,and Sexual Risk Among Young Men Who Have Sex with Men

Parental monitoring and parent–adolescent communication about sex protect against HIV-related sexual risk behaviors among heterosexual adolescents, but it is unknown if these findings generalize to young men who have sex with men (YMSM). Sexual orientation-specific stressors, including “coming out” to parents, complicate the family context of YMSM. We examined associations between parental monitoring, communication about sex, outness to cohabitating parents, and sexual behaviors. Ethnically diverse YMSM ages 14–19 provided cross-sectional data (n = 257). Monitoring and outness to parents interacted to predict recent same-sex unprotected anal intercourse (UAI). For YMSM who reported mixed or uncertain outness to parents, higher levels of perceived parental monitoring were associated with greater risk of UAI. Higher levels of communication about sex were associated with greater risk of UAI for YMSM out to parents. Parental monitoring and communication about sex might not protect YMSM against sexual risk in the same way they protect heterosexual youth. Future research should examine whether adapted forms of family factors could protect YMSM, and family-based HIV risk-reduction interventions for YMSM should be attuned to the unique ways family factors function within this group.