SRChing for the substrates of Src.

By the mid 1980's, it was clear that the transforming activity of oncogenic Src was linked to the activity of its tyrosine kinase domain and attention turned to identifying substrates, the putative next level of control in the pathway to transformation. Among the first to recognize the potential of phosphotyrosine-specific antibodies, Parsons and colleagues launched a risky shotgun-based approach that led ultimately to the cDNA cloning and functional characterization of many of today's best-known Src substrates (for example, p85-Cortactin, p110-AFAP1, p130Cas, p125FAK and p120-catenin). Two decades and over 6000 citations later, the original goals of the project may be seen as secondary to the enormous impact of these protein substrates in many areas of biology. At the request of the editors, this review is not restricted to the current status of the substrates, but reflects also on the anatomy of the project itself and some of the challenges and decisions encountered along the way.

Motivations for the recreational use of erectile enhancing medications in urban gay and bisexual men.

OBJECTIVES: Recreational erectile enhancing medication (EEM) use has been associated with a number of health risk behaviours among gay and bisexual men. This study aims to extend previous findings about the associations between recent EEM use and illegal drug use, incident sexually transmitted infections (STIs) and unprotected sex, as well as to report on motivations for EEM use. METHODS: A cross-sectional, street-intercept survey method was used to collect data from 912 gay/bisexual men at two large lesbian, gay and bisexual community events in New York City in 2006. RESULTS: Lifetime EEM use was reported by 28.0% of the men; 17.4% used EEM in the past 3 months. EEM users were more likely to be white and HIV positive. EEM users were more likely to engage in unprotected anal insertive sex with seroconcordant and serodiscordant partners. EEM users who were HIV negative were more likely to report using alcohol and other drugs before and during sex, especially crystal methamphetamine (AOR 18.66; 95% CI 6.82 to 51.02) as well as to endorse incident STIs. The most frequent responses for EEM use were to "add to the fun", "maintain an erection while using a condom" and "to have sex for hours". Men with HIV were 2.93 times (95% CI 1.24 to 6.88) more likely to endorse using EEMs to bareback. CONCLUSIONS: Gay and bisexual men use EEMs to enhance their sexual experiences among other motives. Different motives and correlates emerged by HIV status. Overall, EEM use was correlated with multiple health risk behaviours. EEM users who were HIV negative appear to be at particularly high risk of acquiring HIV.

Transtheoretical Model and substance use in HIV-positive youth.

The purpose of the study was to test constructs of the Transtheoretical Model (TTM) for predicting alcohol and other drug use in HIV-positive youth (ages 16-25). Questionnaires and interviews about alcohol and other drug use, stage of change, self-efficacy, emotional distress and social support were obtained from 64 HIV-positive youth. Structural equation modeling with standard errors determined by methods appropriate to small samples, demonstrated that self-efficacy mediated the relationship between stage of change and alcohol use and between social support and alcohol use. The same pattern of results emerged for marijuana use. The models predicted 47% of the variance in alcohol use and 69% of the variance in marijuana use. Results supported the TTM and highlight the potential of interventions that seek to boost self-efficacy and social support specific to reducing substance use.

Knowledge of human papillomavirus and effects on sexual behaviour of gay/bisexual men: a brief report.

The objective of this study was to examine the knowledge and misinformation about human papillomavirus (HPV) and differences in sexual risk practices. Self-report surveys assessing the history of HPV/genital warts and sexual practices were completed by 1065 gay/bisexual men in New York City. Of the men reporting a history of HPV, genital warts, or both, the majority reported having warts but not HPV, demonstrating inaccurate knowledge. A significantly greater percentage of men who reported both HPV and warts (HPV+) reported having unsafe sex compared with men reporting neither (HPV-) and men reporting warts but not HPV (HPV+ uninformed). HPV+ and HPV+ uninformed men reported significantly more men non-primary sex partners in the past three months than HPV- men. Findings indicate that many gay/bisexual men, a population at risk for HPV, are misinformed about its various permutations. Men who are HPV+ report increased sexual risk practices and more sexual partners. Comprehensive gay men's health programmes must include HPV education.

The use of the Internet by gay and bisexual male escorts: sex workers as sex educators.

While prior studies have targeted street-based male sex workers as potential vectors of disease transmission, the number of men who work independently through Internet chat-rooms and other online endeavors has steadily increased. It is likely that these men differ substantially from their street-based counterparts in terms of sexual risk behaviors with their clients. The purpose of this study was to explore the ways in which the Internet has impacted the work of male escorts and their sexual practices with clients. Semi-structured qualitative interviews and quantitative surveys were administered to 46 such men. Less than half the men reported unprotected anal sex with clients. The qualitative data lend support to this finding, in that the majority talked about refusing any unsafe sex with clients, and many reported taking the extra step of educating their clients about the dangers of risky sex. Some of the escorts described the methods used to incorporate safer sex practices into sessions with their clients. Internet-based male escorts can play an important role as potential sex educators on the front lines of the fight against HIV and other sexually transmitted infections.

Correlates of depressive symptoms among HIV-positive injection drug users: the role of social support.

Using cross-sectional data from an ethnically diverse sample of HIV-positive injection drug users (IDUs), we sought to identify correlates of depressive symptoms. We were particularly interested in whether perceived social support was associated with depression among HIV-positive IDUs and whether social support buffered adverse effects of other correlates. Data were collected from a sample of HIV-positive IDUs recruited from a variety of venues in the New York City and San Francisco metropolitan areas in the USA. Multiple regression analysis identified four significant correlates of depressive symptoms. Perceived social support and having a regular place for HIV medical care were significantly associated with lower levels of depressive symptoms, while history of mental health problems and non-injection polydrug use were significantly associated with higher levels of depressive symptoms. Moreover, a significant interaction effect was found between social support and non-injection polydrug use, indicating that social support buffers the association between non-injection polydrug use and depression. These results suggest that increasing social support might be a useful tool for HIV-positive IDUs in reducing depression and the adverse effect of non-injection polydrug use.

Intentional unsafe sex (barebacking) among HIV-positive gay men who seek sexual partners on the internet.

While unsafe sex has been reported throughout the HIV epidemic, the underlying assumption has been that most persons do not seek to purposely ham unprotected sex. Within the gay community, the term 'barebacking' has emerged to refer to intentional unsafe anal sex. The prevalence of barebacking is evidenced among gay men, particularly those who are HIV-positive, by the number of internet sites devoted to barebacking and the number of men seeking sexual partners through the use of the internet. To gain insight into barebacking, a sample of 112 HIV-positive gay men were recruited from internet sites where men seek to meet each other for sex. The major it of participants (84%)reported engaging in barebacking in the past three months, and 43% of the men reported recent bareback sex with a partner of unknown serostatus. These results indicate the potential for widespread transmission of HIV to uninfected men by the partners they meet on the internet. Analyses revealed that men who reported bareback sex only with HIV-positive partners scored lower in sexual adventurism than those who had bareback sex regardless of partner serostatus. A significant correlation was observed between defining masculinity as sexual prowess and intentional unprotected anal sex. There are serious implications for HIV prevention efforts, in that internet-based education should be a priority in order to reach men who rely on this mechanism to find sexual partners.

Characteristics of HIV antiretroviral treatments, access and adherence in an ethnically diverse sample of men who have sex with men.

Data regarding HIV antiretroviral treatment regimens, access to treatment and medical care, and adherence to medications were collected as part of the Seropositive Urban Men's Study, a formative study of HIV-positive men who have sex with men. Participants (N = 456) were recruited from AIDS service organizations, mainstream gay venues and public/commercial sex environments. The sample was 94% gay or bisexually-identified; 29% were African American, 24% Latino and 30% white. The majority (71%) indicated being on antiretroviral treatment, and most were taking a protease inhibitor/nucleoside reverse transcriptase inhibitor combination. African American men in New York City were less likely to be on treatment. Among those on treatment (n = 322), 51% reported at least one day in which they had missed a dose of their medication and the mean number of days in which a dose was missed (in the past 30 days) was 1.72. Multivariate analyses indicated that avoidant coping, frequency of drinking alcohol and difficulty in communicating with sex partners about HIV were related to days of missed doses, suggesting the need or desire to escape from the reality of life with HIV as a potential explanation for poor adherence.

Promoting safer sex among HIV-positive youth with haemophilia: theory, intervention, and outcome.

The goal of the project was to develop and evaluate theory-based interventions designed to change sexual behaviour and promote safer sex practices of HIV seropositive young men and adolescents with haemophilia to prevent transmission to sexual partners and offspring. Safer sex was defined as abstinence, consistent condom use, or 'outercourse' (intimate, non-intercourse sexual behaviour). This project utilized the Transtheoretical Model developed by Prochaska and DiClemente, which describes behaviour change as an incremental, stage-based process. The 1-year intervention protocol consisted of two individual sessions and two peer-centred activities. One hundred and four adolescents, residing in 22 states, participated. Pre- and post-intervention evaluations were conducted to measure stage progression for participants. The number who were in the action or maintenance stage of change for safer sex was significantly greater at post-test than at pre-test (79 vs. 62%, P < 0.0001). Participants also reported an increased use of outercourse. In addition, significant increases in self-efficacy and knowledge regarding safer sex were demonstrated. Following these stage-based interventions, participants were significantly more likely to be engaging in safer sex behaviours than they were previously. These intervention activities can be adapted for use with other adolescent populations and for other behaviour change goals in adolescents with haemophilia.

Sexual and drug-using practices of HIV-positive men who frequent public and commercial sex environments.

An ethnically diverse sample (69.7% men of colour) of HIV-seropositive MSM from the New York City and San Francisco metropolitan areas were recruited from a variety of social settings. While only 27.0% of the participants were recruited from PSEs (public sex environments where men 'cruise' for potential sex partners, such as parks) and CSEs (commercial sex environments where an admission is paid for entrance, such as bathhouses and sex clubs), 49.6% reported attending PSEs and 40.7% reported attending CSEs. Only a minority of participants from the full sample reported sexual behaviours that would have placed a partner at highest risk for HIV seroconversion. However, differences between those who frequented CSEs and those who did not emerged on several psychosocial factors (sexual sensation seeking, depression, perceived responsibility towards protecting sexual partners from HIV infection), sexual risk behaviours (unprotected oral and anal sex) and types of recreational drugs used. Fewer differences were found between those who frequented PSEs and those who did not.

Chronic inhibition of cortex microsomal Mg(2+)/Ca(2+) ATPase-mediated Ca(2+) uptake in the rat pilocarpine model following epileptogenesis.

In the rat pilocarpine model, 1 h of status epilepticus caused significant inhibition of Mg(2+)/Ca(2+) ATPase-mediated Ca(2+) uptake in cortex endoplasmic reticulum (microsomes) isolated immediately after the status episode. The rat pilocarpine model is also an established model of acquired epilepsy. Several weeks after the initial status epilepticus episode, the rats develop spontaneous recurrent seizures, or epilepsy. To determine whether inhibition of Ca(2+) uptake persists after the establishment of epilepsy, Ca(2+) uptake was studied in cortical microsomes isolated from rats displaying spontaneous recurrent seizures for 1 year. The initial rate and total Ca(2+) uptake in microsomes from epileptic animals remained significantly inhibited 1 year after the expression of epilepsy compared to age-matched controls. The inhibition of Ca(2+) uptake was not due to individual seizures nor an artifact of increased Ca(2+) release from epileptic microsomes. In addition, the decreased Ca(2+) uptake was not due to either selective isolation of damaged epileptic microsomes from the homogenate or decreased Mg(2+)/Ca(2+) ATPase protein in the epileptic microsomes. The data demonstrate that inhibition of microsomal Mg(2+)/Ca(2+) ATPase-mediated Ca(2+) uptake in the pilocarpine model may underlie some of the long-term plasticity changes associated with epileptogenesis.

Cortactin: coupling membrane dynamics to cortical actin assembly.

Exposure of cells to a variety of external signals causes rapid changes in plasma membrane morphology. Plasma membrane dynamics, including membrane ruffle and microspike formation, fusion or fission of intracellular vesicles, and the spatial organization of transmembrane proteins, is directly controlled by the dynamic reorganization of the underlying actin cytoskeleton. Two members of the Rho family of small GTPases, Cdc42 and Rac, have been well established as mediators of extracellular signaling events that impact cortical actin organization. Actin-based signaling through Cdc42 and Rac ultimately results in activation of the actin-related protein (Arp) 2/3 complex, which promotes the formation of branched actin networks. In addition, the activity of both receptor and non-receptor protein tyrosine kinases along with numerous actin binding proteins works in concert with Arp2/3-mediated actin polymerization in regulating the formation of dynamic cortical actin-associated structures. In this review we discuss the structure and role of the cortical actin binding protein cortactin in Rho GTPase and tyrosine kinase signaling events, with the emphasis on the roles cortactin plays in tyrosine phosphorylation-based signal transduction, regulating cortical actin assembly, transmembrane receptor organization and membrane dynamics. We also consider how aberrant regulation of cortactin levels contributes to tumor cell invasion and metastasis.

Substance use and sexual transmission risk behavior of HIV-positive men who have sex with men.

We examined substance use in relationship to transmission risk behavior (unprotected insertive, UIAI, or receptive anal intercourse, URAI) between HIV-positive men who have sex with men (MSM) and their HIV-negative or unknown serostatus partners. Men who engaged in transmission risk behavior with casual partners were more likely than men who did not engage in such behavior to have used various substances. Users of certain drugs were specifically less likely to use condoms with HIV-negative or unknown status partners than users. Of men who drank alcohol, those who drank more frequently before or during sex engaged in significantly more UIAI with casual partners. Of men who used drugs, those who used more frequently before or during sex were more likely to engage in URAI with casual partners. In multivariate analyses, use of inhalants as well as drinking before or during sex predicted UIAI, while use of inhalants as well as noninjection drug use before or during sex predicted URAI. HIV prevention programs for HIV-positive MSM should focus on decreasing substance use and use specifically before or during sex. Developing prevention programs for substance-using MSM is critical to improve community health and decrease HIV transmissions.

Awareness and use of untested barrier methods by HIV-seropositive gay and bisexual men.

Little is known about HIV-seropositive men's awareness and use of untested barrier methods during anal intercourse. A sample of 240 HIV-seropositive men (69.2% men of color) completed a self-administered survey that included items on nonoxynol-9 (N-9), female condoms, and the simultaneous use of two male condoms (double bagging). Most participants (79.6%) had heard of N-9 being used to prevent HIV transmission during anal intercourse. Of these, 20.0% rated N-9 as more effective than condoms, and 14.6% had used N-9 instead of condoms. Fewer men (35.4%) were aware of female condoms being used during anal intercourse. Overall, few respondents (5.4%) had used female condoms; 53.8% of whom rated the device as more pleasurable than male condoms. Most men (69.6%) had heard of double bagging, and 35.2% had engaged in this practice. Of these, 45.1% rated the practice as less pleasurable than using a single condom. Few associations were observed between participant characteristics and the awareness or use of these barrier methods. The widespread use of these untested methods emphasizes the urgent need to further educate HIV-seropositive men about the potential risks of N-9 use and to test the effectiveness of other strategies that may serve as alternatives to male condom use.

Cell-cycle-dependent association of protein phosphatase 1 and focal adhesion kinase.

Immunofluorescence studies with protein phosphatase-1 (PP1) isoforms-specific antibodies detected PP1delta, but not alpha or gamma1, at focal adhesions. PP1delta also co-immunoprecipitated with the focal adhesion kinase (FAK) and the alphav-integrin. In the present study glutathione S-transferase (GST)-PP1delta pulled-down FAK from fibroblasts extract and the interaction domain localized between residues 159 and 295 of delta. The association was confirmed by the ability to GST-FAK-related non-kinase (FRNK) to pull-down PP1delta from fibroblasts extract. GST-FRNK also pulled-down purified muscle PP1 catalytic subunit, thus indicating direct interaction between FAK and PP1. FAK displays consensus sequences for phosphorylation by cell division cycle kinase-2-cyclin B, and might be a PP1 substrate. In fact, FAK immunoprecipitated from metabolically-labelled mitotic HeLa cells without tyrosine phosphatase inhibitors was phosphorylated on Ser only and was dephosphorylated in vitro by purified muscle PP1, with loss of phospho-Ser. No PP1 was associated with FAK immunoprecipitated from mitotic HeLa cells. However, progressively more PP1 activity was assayed in FAK-immunoprecipitates obtained from cells released from mitosis. The associated activity was maximal at 2 h from the mitotic release (when 85-90% of the cells remained round) and decreased to basal level by 8 h (when cells were all polygonal). At the same time FAK underwent dephosphorylation, which was completed by 4 h. FAK obtained from cells at 1.5 h was Ser-phosphorylated, and underwent dephosphorylation during in vitro incubation, with loss of phospho-Ser, indicating the presence of active FAK-bound phosphatase. The only FAK-associated PP1 isoform between 1 and 8 h was PP1delta. The results suggest that FAK dephosphorylation by PP1delta occurs in cells released from mitosis, and confirmed the specific association of PP1delta, as detected previously in adherent cells.

A double epidemic: crystal methamphetamine drug use in relation to HIV transmission among gay men.

Emerging research on methamphetamine use among gay men suggests that growth in the use of this drug could present serious problems for HIV/AIDS prevention within the gay community. This article summarizes current studies on the extent, role, and context of methamphetamine use among gay men and its relationship to high risk sexual behaviors related to HIV transmission. Methamphetamine is often used by gay men to initiate, enhance, and prolong sexual encounters. Use of the drug is, therefore, associated with particular environments where sexual contact among gay men is promoted, such as sex clubs and large "circuit" parties. Research with gay and bisexual men indicates that methamphetamine use is strongly associated with risky sexual behaviors that may transmit HIV. This relationship, coupled with emerging evidence that methamphetamine use is on the rise among gay men, suggests that the drug could exacerbate the HIV/AIDS epidemic among this community. The article offers recommendations for further research and suggestions for prevention programs regarding methamphetamine use by gay men.

A significant increase in both basal and maximal calcineurin activity in the rat pilocarpine model of status epilepticus.

This study focused on the effects of status epilepticus on the activity of calcineurin, a neuronally enriched, calcium-dependent phosphatase. Calcineurin is an important modulator of many neuronal processes, including learning and memory, induction of apoptosis, receptor function and neuronal excitability. Therefore, a status epilepticus-induced alteration of the activity of this important phosphatase would have significant physiological implications. Status epilepticus was induced by pilocarpine injection and allowed to continue for 60 min. Brain region homogenates were then assayed for calcineurin activity by dephosphorylation of p-nitrophenol phosphate. A significant status epilepticus-dependent increase in both basal and Mn(2+)-dependent calcineurin activity was observed in homogenates isolated from the cortex and hippocampus, but not the cerebellum. This increase was resistant to 150 nM okadaic acid, but sensitive to 50 microM okadaic acid. The increase in basal activity was also resistant to 100 microM sodium orthovanadate. Both maximal dephosphorylation rate and substrate affinity were increased following status epilepticus. However, the increase in calcineurin activity was not found to be due to an increase in calcineurin enzyme levels. Finally, increase in calcineurin activity was found to be NMDA-receptor activation dependent. The data demonstrate that status epilepticus resulted in a significant increase in both basal and maximal calcineurin activity.