Diversity of human papillomavirus in the anal canal of men: the HIM Study.

Human papillomavirus (HPV) infections are associated with the development of anogenital lesions in men. There are no reports describing the distribution of non-α HPV types in the anal canal of a sexually diverse group of men. The HPV Infection in Men (HIM) Study is a multicentre study on the natural history of HPV infection in Brazil, Mexico, and the USA. At baseline, 12% of anal canal PCR HPV-positive specimens were not typed by the Roche Linear Array, and were considered to be unclassified. Our goals were to characterize HPVs among these unclassified specimens at baseline, and to assess associations with participant socio-demographic and behavioural characteristics. Unclassified HPVs were typed by sequencing of amplified PGMY09/11 products or cloning of PGMY/GP + nested amplicons followed by sequencing. Further analysis was conducted with FAP primers. Of men with unclassified HPV in the anal canal, most (89.1%) were men who have sex with women. Readable sequences were produced for 62.8% of unclassified specimens, of which 75.2% were characterized HPV types. Eighteen, 26 and three different α-HPV, ß-HPV and γ-HPV types were detected, respectively. α-HPVs were more commonly detected among young men (18-30 years) than among older men (45-70 years), whereas ß-HPVs were more frequent among mid-adult men (31-44 years). ß-HPVs were more common among heterosexual men (85.0%) than among non-heterosexual men. All ß-HPVs detected among non-heterosexual men were ß2-HPV types. The high prevalence of ß-HPV in the anal canal of men who do not report receptive anal sex is suggestive of other forms of transmission that do not involve penile-anal intercourse.

Interactive lethal and mutagenic effects of ultraviolet light and bleomycin in yeast: synergism or antagonism?

The mutagenic interactions of ultraviolet light and bleomycin in haploid populations of Saccharomyces cerevisiae were analyzed. Survival and mutation frequency as a function of different bleomycin concentrations after one conditioning dose of UV radiation were determined. Furthermore, corresponding interaction functions and sensitization factors were calculated. A synergistic interaction between UV light and bleomycin was shown for both lethal and mutagenic events when the cells were in nutrient broth during the treatments. Conversely, the interaction between UV light and bleomycin was antagonistic when the cells were in deionized water during the treatment. The magnitude of lethal and mutagenic interactions depends on dose, and thus presumably on the number of lesions. The observed interactions between UV light and bleomycin suggest that the mechanism that is most likely involved is the induction of repair systems with different error probabilities during the delay of cell division.