Although use of the Internet as a vehicle for HIV/STI research is increasing, its viability to recruit at-risk populations such as Hispanic men who have sex with men (HMSM) to participate in community-based HIV studies is in its infancy. We report on the first 171 participants enrolled in an ongoing study exploring use of the Internet to recruit Hispanic men who have sex with men (HMSM) living in Miami-Dade County, Florida to participate in community-based studies. We report our initial success with chat-room recruitment and describe the sexual and drug use practices of the initial set of participants who were recruited through the Internet. In addition, we describe the formative work conducted to develop the Internet recruitment procedures we are testing. In two months, we spent 211 hours recruiting in chat-rooms and engaged 735 chatters. One hundred and seventy-six men came to our community sites; 172 (98%) were eligible and completed an audio computer-assisted self-interview. In the previous six months, 94.7% of participants had anal sex; 48.9% did not use condoms for anal sex or used them inconsistently; and 48.5% had used club drugs. Six-month use rates for individual drugs were: poppers (31.6%), cocaine (15.8%), ecstasy (14%) and crystal methamphetamines (11.7%). Use of club drugs was significantly associated with unprotected insertive and unprotected receptive anal sex. These initial findings point to the Internet's potential as a tool for recruiting at-risk Hispanic MSM for community studies.

Objectives The purpose of the current study was to assess the role of gender and ethnicity in the relationship between alcohol use and risky sexual behavior. Method Sexually active college students (n = 425) reported on alcohol expectancies, perceived risk of HIV, and drinking and sexual behavior in the context of a larger health behavior survey. Results Approximately one-third of participants reported binge drinking 3 or more times in the past two weeks. African American women reported less drinking and less positive alcohol expectancies than other women. Older men engaged more often than younger men in binge drinking and reported more sexual partners in the past year. Younger age and greater perceived risk for HIV were positively associated with condom use for both women and men. Conclusion Collectively, these findings suggest that alcohol abuse and HIV prevention efforts among young adults need to consider gender, ethnicity, and age.

Mapping posttranslational modifications (PTMs), which diversely modulate biological functions, represents a significant analytical challenge. The centerpiece technology for PTM site identification, mass spectrometry (MS), requires proteolytic cleavage in the vicinity of a PTM to yield peptides for sequencing. This requirement catalyzed our efforts to evolve MS-grade mutant PTM-directed proteases. Citrulline, a PTM implicated in epigenetic and immunological function, made an ideal first target, because citrullination eliminates arginyl tryptic sites. Bead-displayed trypsin mutant genes were translated in droplets, the mutant proteases were challenged to cleave bead-bound fluorogenic probes of citrulline-dependent proteolysis, and the resultant beads (1.3 million) were screened. The most promising mutant efficiently catalyzed citrulline-dependent peptide bond cleavage (k cat /K M = 6.9 × 10 5 M). The resulting C-terminally citrullinated peptides generated characteristic isotopic patterns in MALDI-TOF MS, and both a fragmentation product y 1 ion corresponding to citrulline (176.1030 m/z) and diagnostic peak pairs in the extracted ion chromatograms of LC-MS/MS analysis. Using these signatures, we identified citrullination sites in protein arginine deiminase 4 (12 sites) and in fibrinogen (25 sites, two previously unknown). The unique mass spectral features of PTM-dependent proteolytic digest products promise a generalized PTM site-mapping strategy based on a toolbox of such mutant proteases, which are now accessible by laboratory evolution.T he identification and mapping of protein posttranslational modifications (PTMs), which underpin the regulation of virtually every cellular function, represents one of the most significant challenges of modern-day analytical science. Accessing this biochemical information requires direct observation of the modified site, often in low abundance within the complex cellular milieu. The ability to address this sample complexity is precisely why tandem mass spectrometry (MS/MS) now dominates proteomic analysis. LC-MS/MS instruments can analyze mixtures of thousands of peptides, acquiring the mass-to-charge ratio (m/z) of each peptide precursor ion (MS1) and fragmenting the most abundant precursors for a second dimension of MS analysis (MS2). Database searching of MS/MS "bottom-up" proteomic data entails matching observed precursor and fragmentation product ion masses with those of a theoretical protein digest, returning the amino acid sequence of each ion (including any PTMs) and statistical confidence of the sequence match (1, 2).Bottom-up MS/MS workflows generate peptides for analysis almost ubiquitously by digestion using trypsin, which cleaves the C-terminal peptide bonds of Arg and Lys with high catalytic efficiency and selectivity (3). Regions of a protein too densely or too sparsely populated with tryptic sites result in sequencing coverage gaps, which can conceal PTM sites during mapping experiments. Digestion with alternative proteases (4, 5), which reinforce tryptic cleavage...

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