Biomedical subjects

David W Purcell

Publications and source records attributed to David W Purcell.

At least 19 recordsLinked to original sources

PubMed2006

Safe syringe disposal is related to safe syringe access among HIV-positive injection drug users.

We evaluated the effect of syringe acquisition on syringe disposal among HIV-positive injection drug users (IDUs) in Baltimore, New York City, and San Francisco (N = 680; mean age 42 years, 62% male, 59% African-American, 21% Hispanic, 12% White). Independent predictors of safe disposal were acquiring syringes through a safe source and ever visiting a syringe exchange program. Weaker predictors included living in San Francisco, living in the area longer, less frequent binge drinking, injecting with an HIV+ partner, peer norms supporting safe injection, and self-empowerment. Independent predictors of safe "handling"-both acquiring and disposing of syringes safely-also included being from New York and being older. HIV-positive IDUs who obtain syringes from a safe source are more likely to safely dispose; peer norms contribute to both acquisition and disposal. Interventions to improve disposal should include expanding sites of safe syringe acquisition while enhancing disposal messages, alternatives, and convenience.

Adult↗

PubMed2006

Do prevention interventions reduce HIV risk behaviours among people living with HIV? A meta-analytic review of controlled trials.

OBJECTIVE: To conduct a meta-analytic review of HIV interventions for people living with HIV (PLWH) to determine their overall efficacy in reducing HIV risk behaviours and identify intervention characteristics associated with efficacy. METHODS: Comprehensive searches included electronic databases from 1988 to 2004, hand searches of journals, reference lists of articles, and contacts with researchers. Twelve trials met the stringent selection criteria: randomization or assignment with minimal bias, use of statistical analysis, and assessment of HIV-related behavioural or biologic outcomes at least 3 months after the intervention. Random-effects models were used to aggregate data. RESULTS: Interventions significantly reduced unprotected sex [odds ratio (OR), 0.57; 95% confidence interval (CI) 0.40-0.82] and decreased acquisition of sexually transmitted diseases (OR, 0.20; 95% CI, 0.05-0.73). Non-significant intervention effects were observed for needle sharing (OR, 0.47, 95% CI, 0.13-1.71). As a whole, interventions with the following characteristics significantly reduced sexual risk behaviours: (1) based on behavioural theory; (2) designed to change specifically HIV transmission risk behaviours; (3) delivered by health-care providers or counsellors; (4) delivered to individuals; (5) delivered in an intensive manner; (6) delivered in settings where PLWH receive routine services or medical care; (7) provided skills building, or (8) addressed a myriad of issues related to mental health, medication adherence, and HIV risk behaviour. CONCLUSION: Interventions targeting PWLH are efficacious in reducing unprotected sex and acquisition of sexually transmitted diseases. Efficacious strategies identified in this review should be incorporated into community HIV prevention efforts and further evaluated for effectiveness.

Adult↗

PubMed2006

Examining the role of partner status in an HIV prevention trial targeting HIV-positive gay and bisexual men: the seropositive urban men's intervention trial (SUMIT).

The goal of this analysis was to examine whether partner status impacted behavioral outcomes from the Seropositive Urban Men's Intervention Trial (SUMIT). We contrasted sample characteristics of HIV-positive gay and bisexual men with and without main partners and then examined differences in sexual behaviors among men participating in an enhanced HIV prevention intervention compared to those in a standard condition. Logistic regression analyses were performed to differentiate characteristics of men with and without main partners and mixed-model logistic regression analyses were performed to test for intervention effects. Men with main partners showed a greater likelihood of having unprotected anal sex with any partner, although the number of male sexual partners was higher for men without a main partner. SUMIT generally produced few differences in sexual risk behaviors and did not affect several potential mediator variables of the relationship between the intervention and sexual behaviors with main and nonmain partners.

Bisexuality↗

PubMed2006

Recruitment source and behavioral risk patterns of HIV-positive men who have sex with men.

To effectively target HIV prevention activities, community outreach workers need to know how to locate persons at greatest risk for acquiring or transmitting HIV. This study compared the behavioral characteristics of HIV-positive men who have sex with men recruited from different sources: AIDS service organizations, mainstream gay environments, public/private sex environments, and friend referrals. Men recruited from sex environments exhibited the riskiest behavior: more male partners, more likely to have casual sex, more likely to have had unprotected insertive sex with men of HIV-negative or unknown status, less likely to have disclosed serostatus to primary partners, less comfortable discussing serostatus with others, and less feeling of personal responsibility for disclosure. A distinctive group of men, the referral group, did not identify with the gay community and reported sex with men and women. Future efforts should continue to assess the types of people that are recruited from different sources so that program and research efforts can be appropriately targeted.

Adult↗

PubMed2006

Desire for children and pregnancy risk behavior among HIV-infected men and women in Uganda.

To identify ways to improve prevention of mother-to-child transmission (PMTCT) of HIV, we conducted a cross-sectional study of 1,092 HIV-infected men and women attending an AIDS support organization in Jinja, Uganda, between October 2003 and June 2004. Pregnancy risk behavior was defined as having sex without contraceptive or condom. Overall, 42% of participants were sexually active, 33% practiced pregnancy risk behavior, and 18% desired more children. Men were almost four times to want more children than the women (27% vs. 7%). Among those practicing pregnancy risk behavior, 73% did not want more children and were at high risk for unwanted pregnancies. Although 81% knew that mother-to-child transmission of HIV could be prevented, only 22% believed that an HIV-infected woman who received PMTCT therapy could still deliver an HIV-infected child. Lack of MTCT information, having attended the program for </=2 years and desire for children were independently associated with pregnancy risk behavior. PMTCT and other HIV prevention and care programs should ensure provision of family planning for HIV-infected populations who do not want to become pregnant.

Adult↗

PubMed2006

Disclosure of HIV status and adherence to daily drug regimens among HIV-infected children in Uganda.

Pediatric adherence to daily drug regimens has not been widely assessed in Africa where majority of HIV infected children live. Using in-depth interviews of 42 HIV-infected children taking ART and/or cotrimoxazole prophylaxis, and 42 primary caregivers, at a comprehensive HIV/AIDS clinic in Uganda, we evaluated their adherence experiences for purposes of program improvement. Daily drug regimens provided by the pediatric clinic included cotrimoxazole prophylaxis as well as ART and cotrimoxazole combined. Complete disclosure of HIV status by caregivers to children and strong parental relationships were related to good adherence. Structural factors including poverty and stigma were barriers to adherence even for children who had had complete disclosure and a supportive relationship with a parent. To ensure adherence to life-extending medications, our findings underscore the need for providers to support caregivers to disclose, provide on-going support and maintain open communication with HIV-infected children taking cotrimoxazole prophylaxis and ART.

AIDS-Related Opportunistic Infections↗

PubMed2006

Depression and CD4 cell count among persons with HIV infection in Uganda.

Despite the importance of mental illness and the high prevalence of HIV in Africa, few studies have documented depressive symptoms among HIV-infected persons in Africa. We assessed factors associated with depression among HIV-infected adults undergoing anti-retroviral eligibility screening in Eastern Uganda. Depressive symptoms were measured using the Center for Epidemiologic Studies Depression Scale (CES-D). Univariate and multiple regression analyses were conducted to identify socio-demographic characteristics and disease-related factors associated with depression. Among 1017 HIV-infected participants assessed for depression, 47% (476/1017) reported depressive symptoms (CES-D >/= 23). Adjusting for age, gender, education, and source of income, patients with CD4 counts <50 cells/microl were more likely to be depressed (odds ratio 2.34, 95% confidence interval, 1.39-3.93, P = 0.001). Women, participants >50 years, and those without an income source were more likely to be depressed. Depression was common among HIV-infected persons in rural Uganda and was associated with low CD4 cell counts. Appropriate screening and treatment for depression should be considered for comprehensive HIV care.

Adolescent↗

PubMed2006

Update and overview of practical epidemiologic aspects of HIV/AIDS among injection drug users in the United States.

In a changing public health landscape in which local, state, and federal agencies must confront threats of bioterrorism, emerging infections, and numerous chronic diseases, transmission of HIV among injection drug users (IDUs) continues to be an important public health issue and one of the driving forces behind the HIV epidemic. Using a computerized MEDLINE search of published articles from January 1981 through October 2005, we conducted a literature review of practical epidemiologic aspects of HIV/AIDS among IDUs in the United States. Although recent trends indicate a decline in the proportion of newly diagnosed HIV infections associated with injection drug use, drug-use behaviors overall still account for 32% of new HIV diagnoses. Factors in addition to syringe sharing contribute to HIV transmission among IDUs: risky sexual behaviors, sharing of drug preparation equipment and drug solutions, and contextual and social factors. Promising approaches for HIV prevention include rapid HIV testing, office-based substance abuse treatment, behavioral interventions, improved communication about syringe exchange programs, and case management. HIV among IDUs continues to be an important public health problem in the 21st century. It is imperative that public health agencies continue to monitor and combat the HIV epidemic among IDUs to ensure that hard-won gains will not be eroded.

Acquired Immunodeficiency Syndrome↗

PubMed2006

Unprotected sexual behavior among heterosexual HIV-positive injection drug using men: associations by partner type and partner serostatus.

Few studies have examined sexual risk behaviors of HIV-positive, heterosexual, injection drug using (IDU) men. We investigated such behaviors and associations with risk among sexually active, HIV-positive IDU men who reported only female sex partners in the 3 months prior to baseline interview. We examined associations separately for four non-exclusive groups of men by crossing partner type (main or casual) and partner serostatus (HIV-positive or HIV-negative/unknown). Of 732 male participants, 469 (64%) were sexually active with only female partners. Of these 469 men, 155 (33%) reported sex with HIV-positive main partners, 127 (27%) with HIV-negative or unknown serostatus main partners, 145 (31%) with HIV-positive casual partners, and 192 (41%) with HIV-negative/unknown serostatus casual partners. Significant multivariate associations for unprotected sex with HIV-negative or unknown serostatus main partners were less self-efficacy to use condoms, weaker partner norms supporting condoms, and more negative condom beliefs. Similar correlates were found for unprotected sex with HIV-positive main and casual partners. In addition, alcohol or drug use during sex was a significant correlate of unprotected sex with HIV-positive main partners, while depression was significant for HIV-positive casual partners. For unprotected sex with HIV-negative/unknown status casual partners, self-efficacy for condom use, sex trade, and education were significant multivariate correlates. A combination of broad and tailored intervention strategies based on the relationship pattern of men's lives may provide the most benefit for reducing unprotected sex with female partners.

Adult↗

PubMed2006

The Bolger conference on PDE-5 inhibition and HIV risk: implications for health policy and prevention.

INTRODUCTION: Recent reports have linked the use of phosphodiesterase type 5 (PDE-5) inhibitors with increased rates of high-risk sexual behavior and HIV transmission in some individuals. AIM: A National Institute of Mental Health (NIMH)-funded, multidisciplinary conference was convened to evaluate scientific research, clinical and ethical considerations, and public policy implications of this topic. MAIN OUTCOME MEASURES: Published and unpublished findings on effects of PDE-5 inhibitors on sexual behavior; published guidelines and management recommendations. METHODS: Leading investigators in relevant disciplines (e.g., public health, epidemiology, medical ethics, urology, psychology) participated in a 2-day meeting, including representatives of government, scientific, and regulatory agencies (the Centers for Disease Control, Food and Drug Administration, NIMH, and the National Institute on Drug Abuse). Panelists provided critical reviews of substantive areas of research, followed by question and answer sessions on each topic. On the second day, working groups were convened to identify critical gaps and priorities in three major areas: (i) research and evaluation needs; (ii) prevention strategies and clinical management issues; and (iii) policy and prevention implications. RESULTS: Research needs and priorities were categorized into four specific areas: (i) basic and clinical/laboratory research; (ii) epidemiology and risk factors; (iii) social-behavioral processes and interventions; and (iv) prevention/policy and educational needs. Identified gaps in the available data include populations at risk (e.g., risk among heterosexuals, risk profiles among subpopulations of men who have sex with men) and the specific role of PDE-5 inhibitors in HIV seroconversion. Specific areas of emphasis were the need for safer sex counseling, comprehensive sexually transmitted infection (STI) screening and follow-up when indicated, avoidance of potentially dangerous drug interactions, and potential benefits of testosterone replacement for HIV-positive men with decreased androgen and other symptoms of hypogonadism. Conclusions. A conference was convened on the topic of PDE-5 inhibition and HIV risk. This "white paper" summarizes the findings of the conference and recommendations for future research.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed2006

Compensation following real-time manipulation of formants in isolated vowels.

Auditory feedback influences human speech production, as demonstrated by studies using rapid pitch and loudness changes. Feedback has also been investigated using the gradual manipulation of formants in adaptation studies with whispered speech. In the work reported here, the first formant of steady-state isolated vowels was unexpectedly altered within trials for voiced speech. This was achieved using a real-time formant tracking and filtering system developed for this purpose. The first formant of vowel /epsilon/ was manipulated 100% toward either /ae/ or /I/, and participants responded by altering their production with average Fl compensation as large as 16.3% and 10.6% of the applied formant shift, respectively. Compensation was estimated to begin <460 ms after stimulus onset. The rapid formant compensations found here suggest that auditory feedback control is similar for both F0 and formants.

Adolescent↗

PubMed2006

Simultaneous latency estimations for distortion product otoacoustic emissions and envelope following responses.

The purpose of this research was to simultaneously estimate processing delays in the cochlea and brainstem using the same acoustic stimuli. Apparent latencies were estimated from ear canal measurements of 2f1-f2 distortion product otoacoustic emissions (DPOAEs), and scalp recordings of the f2-f1 envelope following response (EFR). The stimuli were equal level tone pairs (65 dB SPL) with the upper tone f2 set at either 900 or 1800 Hz to fix the initiation site of the DPOAE and EFR. The frequency of f1 was swept continuously between frequency limits chosen to keep the EFR response between 150 and 170 Hz. The average DPOAE latencies were 9.6 and 6.2 ms for f2 =900 and 1800 Hz, and the corresponding EFR latencies were 12.4 and 8.8 ms. In a control condition, a third (suppressor) tone was added near the DPOAE response frequency to evaluate whether the potential source at fdp was contributing significantly to the measured emission. DPOAE latency is the sum of both inward and outward cochlear delays. The EFR apparent latency is the sum of inward cochlear delay and neural processing delay. Neural delay was estimated as approximately 5.3 ms for both frequencies of stimulation.

Acoustic Stimulation↗

PubMed2006

Adaptive control of vowel formant frequency: evidence from real-time formant manipulation.

Auditory feedback during speech production is known to play a role in speech sound acquisition and is also important for the maintenance of accurate articulation. In two studies the first formant (F1) of monosyllabic consonant-vowel-consonant words (CVCs) was shifted electronically and fed back to the participant very quickly so that participants perceived the modified speech as their own productions. When feedback was shifted up (experiment 1 and 2) or down (experiment 1) participants compensated by producing F1 in the opposite frequency direction from baseline. The threshold size of manipulation that initiated a compensation in F1 was usually greater than 60 Hz. When normal feedback was returned, F1 did not return immediately to baseline but showed an exponential deadaptation pattern. Experiment 1 showed that this effect was not influenced by the direction of the F1 shift, with both raising and lowering of F1 exhibiting the same effects. Experiment 2 showed that manipulating the number of trials that F1 was held at the maximum shift in frequency (0, 15, 45 trials) did not influence the recovery from adaptation. There was a correlation between the lag-one autocorrelation of trial-to-trial changes in F1 in the baseline recordings and the magnitude of compensation. Some participants therefore appeared to more actively stabilize their productions from trial-to-trial. The results provide insight into the perceptual control of speech and the representations that govern sensorimotor coordination.

Acoustic Stimulation↗

PubMed2005

Partner awareness of the serostatus of HIV-seropositive men who have sex with men: impact on unprotected sexual behavior.

Prior research has provided conflicting evidence about the association between partner awareness of an HIV-seropositive person's serostatus and HIV transmission behavior via unprotected intercourse. The current study examined partner awareness of participant HIV-seropositive status and sexual behavior in a multiethnic sample of HIV-seropositive men who have sex with men. Most HIV-seropositive men reported that their primary partners are aware, and most reported that at least some non-primary partners are aware the participant was HIV-seropositive before first having sex. Partner awareness of participant HIV-serostatus was related to unprotected sexual behavior during the past 3 months in a non-linear fashion, as men with partners who were inconsistently aware had higher rates of unprotected receptive anal intercourse than men with partners who were consistently aware or consistently unaware. Men with partners who were inconsistently aware also had higher rates of insertive oral intercourse than men with partners who were consistently aware. However, there were no differences in HIV transmission risk behavior between men with partners who were consistently aware and men with partners who were consistently unaware a participant was HIV-seropositive.

Adult↗

PubMed2005

Experiencing release: sex environments and escapism for HIV-positive men who have sex with men.

There are nonsexual reasons that may motivate people to seek out sexual activity with others. Some men who have sex with men may seek out sex environments to engage in sexual behavior. Among the nonsexual reasons that exist for men who have sex with men is a desire to escape from distressing thoughts and feelings. The amplified sexuality and other unique characteristics of sex environments allow men to have more intense emotional experiences around sex. Using the cognitive escape model as a theoretical foundation, this analysis focuses on the emotional vulnerability that some of the men who visit these venues may be avoiding and how their experiences at these venues might act as releasing mechanisms to alleviate dissonant thoughts and feelings. Implications for public health services and future research are discussed.

Adult↗

PubMed2005

Prevention with gay and bisexual men living with HIV: rationale and methods of the Seropositive Urban Men's Intervention Trial (SUMIT).

OBJECTIVES: To provide a public health rationale for prevention with HIV-seropositive gay and bisexual men and to describe the methods of the Seropositive Urban Men's Intervention Trial (SUMIT). DESIGN: A randomized intervention trial. METHODS: Self-identified HIV-positive gay and bisexual men were recruited from community-based venues in New York City and San Francisco. Eligible participants completed an A-CASI baseline assessment, were asked to provide samples for sexually transmitted infection (STI) testing, and were randomly assigned to either a single-session intervention or a six-session enhanced intervention designed to reduce HIV transmission risk and promote serostatus disclosure. Participants who attended the first intervention session were assessed 3 and 6 months post-intervention. STI testing was offered at the 6-month assessment. RESULTS: A total of 1168 self-identified HIV-seropositive gay and bisexual men completed the baseline assessment, and 1110 of these (95%) opted for STI testing. A total of 811 attended the first intervention session, of which 85% were assessed at 3 months and 90% were assessed at 6 months. Of those assessed at 6 months, 92% (670/729) provided a blood or urine sample for STI testing. CONCLUSION: SUMIT demonstrates the feasibility and acceptability of prevention research with HIV-seropositive gay and bisexual men. The study provides new information about the sexual behavior, serostatus disclosure practices, and the efficacy of an intervention to reduce HIV transmission risk.

Adolescent↗

PubMed2005

Sexual harm reduction practices of HIV-seropositive gay and bisexual men: serosorting, strategic positioning, and withdrawal before ejaculation.

OBJECTIVE: This study assessed unprotected anal and oral sex behaviors of HIV-positive gay and bisexual men in New York City and San Francisco with their main and non-main sexual partners. Here we focus on the use of three harm reduction strategies (serosorting, strategic positioning, and withdrawal before ejaculation) in order to decrease transmission risk. METHOD: The data from a baseline assessment of 1168 HIV-positive gay and bisexual men in the two cities were utilized. Men were recruited from a variety of community-based venues, through advertising and other techniques. RESULTS: City differences were identified, with more men in San Francisco reporting sexual risk behaviors across all partner types compared with men in New York City. Serosorting was identified, with men reporting significantly more oral and anal sex acts with other HIV-positive partners than with HIV-negative partners. However, men also reported more unprotected sex with partners of unknown status compared with their other partners. Some evidence of strategic positioning was identified, although differences were noted across cities and across different types of partners. Men in both cities reported more acts of oral sex without ejaculation than with ejaculation, but the use of withdrawal as a harm reduction strategy for anal sex was more common among men from San Francisco. CONCLUSION: Overall, evidence for harm reduction was identified; however, significant differences across the two cities were found. The complicated nature of the sexual practices of gay and bisexual men are discussed, and the findings have important implications for prevention efforts and future research studies.

Adult↗

PubMed2005

Illicit substance use, sexual risk, and HIV-positive gay and bisexual men: differences by serostatus of casual partners.

OBJECTIVE: To examine the use of alcohol and illicit drugs among HIV-positive gay and bisexual men and to determine substance-use-related predictors of unprotected sex with casual partners who were HIV negative, HIV positive, or whose serostatus was unknown. DESIGN: Cross-sectional assessment of baseline data from a behavioral intervention. METHODS: From 1999 to 2001, we recruited 1168 HIV-positive gay and bisexual men in New York City and San Francisco and determined the prevalence of drinking and drug use, as well as the use of substances with sex. We then examined associations between substance use variables and risky sexual behaviors with casual partners by partner serostatus. RESULTS: Substance use was common, and the use of "party drugs" [e.g. methamphetamine, nitrate inhalants (poppers), ketamine, and gamma hydroxybutyrate] was most often associated with sexual risk in multivariate models. Substance use before or during sex was not associated with risk with HIV-negative partners, but was associated with risk with HIV-positive and unknown-serostatus partners. CONCLUSION: Substance use before or during sex was not associated with risk with HIV-negative partners, suggesting that disclosure by HIV-negative sexual partners of HIV-positive men may be important. Being a user of particular party drugs was associated with recent risk with HIV-negative partners. With partners whose serostatus was unknown, the use of certain party drugs and using substances in the context of sex was associated with risk, possibly as a result of reliance on assumptions of seroconcordance. This same pattern was seen for HIV-positive casual partners. These data have intervention implications for both HIV-positive and HIV-negative men.

Adult↗