HPV infection is highly prevalent in sexually active men and can be detected by use of a variety of specimens and methods. There have been few natural-history studies and no transmission studies of HPV in men. The information that we have reviewed may be useful for future natural-history studies and for modeling the potential impact of a prophylactic HPV vaccine.

Infection with human papillomavirus (HPV) type 16 accounts for about half of cervical cancers worldwide. This study investigated the seroepidemiology of HPV-16 infection in the United States by using a population-based survey. Serum samples and questionnaire data were collected from 1991 to 1994 for the National Health and Nutrition Examination Surveys. HPV-16-specific IgG antibody was detected by use of an HPV-16 virus-like particle ELISA. HPV-16 seropositivity in the US population aged 12-59 years was 13.0% (95% confidence interval, 11.5%-14.7%). Seroprevalence was higher in women (17.9%) than in men (7.9%). Age, race/ethnicity, and number of lifetime sex partners were associated with HPV seropositivity in women. Race/ethnicity, age at first intercourse, urban/nonurban residence, years of sexual activity, and having had sex with a man were associated with HPV seropositivity in men. Information on HPV-16 seroepidemiology will be important for designing prevention efforts including vaccine programs.

Condom use was associated with reduced risk of gonorrhea and chlamydia in men and women in most studies, despite methodologic limitations that likely underestimate condom effectiveness. Epidemiologic studies that better address these factors are needed to provide more accurate assessment of condom effectiveness.

The emerging Overhauser effect Dynamic Nuclear Polarization (ODNP) technique measures the translational mobility of water within the vicinity (5-15 Å) of preselected sites. The work presented here expands the capabilities of the ODNP technique and illuminates an important, previously unseen, property of the translational diffusion dynamics of water at the surface of DNA duplexes. We attach nitroxide radicals (i.e., spin labels) to multiple phosphate backbone positions of DNA duplexes, allowing ODNP to measure the hydration dynamics at select positions along the DNA surface. With a novel approach to ODNP analysis, we isolate the contributions of water molecules at these sites that undergo free translational diffusion from water molecules that either loosely bind to or exchange protons with the DNA. The results reveal that a significant population of water in a localized volume adjacent to the DNA surface exhibits fast, bulk-like characteristics and moves unusually rapidly compared to water found in similar probe volumes near protein and membrane surfaces. Control studies show that the observation of these characteristics are upheld even when the DNA duplex is tethered to streptavidin or the mobility of the nitroxides is altered. This implies that, as compared to protein or lipid surfaces, it is an intrinsic feature of the DNA duplex surface that it interacts only weakly with a significant fraction of a network of surface hydration water. The displacement of this translationally mobile water is energetically less costly than that of more strongly bound water by up to several kBT and thus can lower the activation barrier for interactions involving the DNA surface.

No abstract

Oligomerization has important functional implications for many membrane proteins. However, obtaining structural insight into oligomeric assemblies is challenging, as they are large and resist crystallization. We focus on proteorhodopsin (PR), a protein with seven transmembrane α-helices that was found to assemble to hexamers in densely packed lipid membrane, or detergent-solubilized environments. Yet, the structural organization and the subunit interface of these PR oligomers were unknown. We used site-directed spin-labeling together with electron spin-resonance lineshape and Overhauser dynamic nuclear polarization analysis to construct a model for the specific orientation of PR subunits within the hexameric complex. We found intersubunit distances to average 16 Å between neighboring 55 residues and that residues 177 are >20 Å apart from each other. These distance constraints show that PR has a defined and radial orientation within a hexamer, with the 55-site of the A-B loop facing the hexamer core and the 177-site of the E-F loop facing the hexamer exterior. Dynamic nuclear polarization measurements of the local solvent dynamics complement the electron spin-resonance-based distance analysis, by resolving whether protein surfaces at positions 55, 58, and 177 are exposed to solvent, or covered by protein-protein or protein-detergent contacts.

The treatment of genital warts remains frustrating since it is often painful, expensive, and unsuccessful. Moreover, little is known about the infectivity and natural history of exophytic genital warts or subclinical genital infection with human papillomavirus. The traditional goals of therapy for sexually transmitted diseases--eradication of infection, elimination of symptoms, prevention of long-term sequelae, and interruption of transmission--are currently not attainable for or applicable to genital warts. The medical literature from January 1988 to August 1993 was reviewed for recent studies on the treatment of exophytic warts. The following treatments were included in the reviewed studies: podofilox (which was recently approved by the Food and Drug Administration), podophyllin, cryotherapy, topical 5-fluorouracil, intralesional interferon, systemic interferon, and laser surgery. No single treatment modality was superior to another, and recurrence rates associated with all modalities were high. Treatment of genital warts should be guided by preferences of the patient, and a specific therapeutic regimen should be chosen with consideration of expense, efficacy, convenience, and potential for adverse effects.

Couples who use contraceptives not only protect themselves against unwanted pregnancies, but also may reduce their risk of becoming infected with a sexually transmitted disease (STD). No currently available method, however, is highly effective in protecting simultaneously against pregnancy and infection. Thus, couples who place high priority on minimizing both risks may have to use two methods. The need for contraceptive methods that provide effective protection against both pregnancy and STDs has been intensified by the HIV epidemic, but progress has been slowed by the lack of integration between the STD and family planning fields. The first part of this two-part article discusses the similarities and differences between the two fields, examines the impact of STDs on contraceptive use and services, and reviews the scientific literature dealing with the effects of condoms, spermicides and barrier-and-spermicide methods on the risk of STD transmission. Part II (which will appear in the next issue) examines what is known about the effects of oral contraceptives, the IUD, tubal sterilization and abortion on reproductive tract infections. The second part also includes a discussion of the trade-offs involved in choosing a contraceptive and presents estimates of the first-year rates of unplanned pregnancy and gonorrhea infection (given an infected partner) that would occur among women using various contraceptive methods.