Biomedical subjects

David Purcell

Publications and source records attributed to David Purcell.

6 recordsLinked to original sources

PubMed2006

Individual, interpersonal, and structural correlates of effective HAART use among urban active injection drug users.

Among individuals receiving highly active antiretroviral therapy (HAART), injection drug users (IDUs) are less likely to achieve HIV suppression. The present study examined individual-level, interpersonal, and structural factors associated with achieving undetectable plasma viral load (UVL) among US IDUs receiving recommended HAART. Data were from baseline assessments of the INSPIRE (Interventions for Seropositive Injectors-Research and Evaluation) study, a 4-site, secondary HIV prevention intervention for heterosexually active IDUs. Of 1113 study participants at baseline, 42% (n = 466) were currently taking recommended HAART (34% were female, 69% non-Hispanic black, 26% recently homeless; median age was 43 years), of whom 132 (28%) had a UVL. Logistic regression revealed that among those on recommended HAART, adjusted odds of UVL were at least 3 times higher among those with high social support, stable housing, and CD4 > 200; UVL was approximately 60% higher among those reporting better patient-provider communication. Outpatient drug treatment and non-Hispanic black race and an interaction between current drug use and social support were marginally negatively significant. Among those with high perceived support, noncurrent drug users compared with current drug users had a greater likelihood of UVL; current drug use was not associated with UVL among those with low support. Depressive symptoms (Brief Symptom Inventory) were not significant. Results suggest the major role of social support in facilitating effective HAART use in this population and suggest that active drug use may interfere with HAART use by adversely affecting social support. Interventions promoting social support functioning, patient-provider communication, stable housing, and drug abuse treatment may facilitate effective HAART use in this vulnerable population.

Adult↗

PubMed2005

Race, socioeconomic status, and the perceived importance of positive self-presentation in health care.

Hundreds of studies have documented disparities in medical treatment in the USA. These findings have generated research and initiatives intended to understand and ameliorate such disparities. Many articles examine disadvantaged patients' beliefs and attitudes toward health care, but generally limit their investigation to how these beliefs and attitudes influence adherence and utilization. Thus, this approach fails to consider whether patients use particular strategies to overcome providers' potentially negative perceptions of them and/or obtain quality medical care. In this paper, we examine positive self-presentation as a strategy that may be used by disadvantaged groups to improve their medical treatment. Analysis of survey data (the 2004 Greater Cincinnati Survey) suggests that both African Americans and lower socioeconomic status persons are more likely than whites or higher socioeconomic status persons to report that positive self-presentation is important for their getting the best medical care. Based on these findings, we suggest several routes for future research that will advance our understanding of patients' everyday strategies for getting the best health care.

Adolescent↗

PubMed2005

Recording human evoked potentials that follow the pitch contour of a natural vowel.

We investigated whether pitch-synchronous neural activity could be recorded in humans, with a natural vowel and a vowel in which the fundamental frequency was suppressed. Small variations of speech periodicity were detected in the evoked responses using a fine structure spectrograph (FSS). A significant response (P < 0.001) was measured in all seven normal subjects even when the fundamental frequency was suppressed, and it very accurately tracked the acoustic pitch contour (normalized mean absolute error < 0.57%). Small variations in speech periodicity, which humans can detect, are therefore available to the perceptual system as pitch-synchronous neural firing. These findings suggest that the measurement of pitch-evoked responses may be a viable tool for objective speech audiometry.

Adult↗

PubMed2005

Sexual risk taking among HIV-positive injection drug users: contexts, characteristics, and implications for prevention.

HIV-positive injection drug users (IDUs) ( N = 161) were recruited to complete a qualitative interview and a quantitative survey about sexual behavior and transmission risk. We identified two contexts in which exposure encounters occurred most commonly for HIV-positive IDUs: in intimate serodiscordant relationships and in the drug/sex economy. Salient characteristics in both contexts included the role of intimacy, drug use and sexual decision making, disclosure of HIV status, and perceived responsibility. Although these characteristics emerged in both risk contexts, they operated differently within each context. The preservation of intimacy was paramount among those in serodiscordant relationships, and agreements to take risks were common. In the drug/sex economy, serostatus disclosure was uncommon and drug acquisition and use played a significant role in sexual risk taking. Our data emphasize a need to address the specific transmission risk contexts occurring among HIV-positive IDUs and to prioritize social and interpersonal factors when promoting safer sexual norms among HIV-positive IDUs.

Adolescent↗

PubMed2003

The life priorities of HIV-seropositive injection drug users: findings from a community-based sample.

Using cross-sectional data from an ethnically diverse sample of 161 HIV-seropositive injection drug users (IDUs), we investigated (1) how HIV-positive IDUs rank their life priorities, (2) whether HIV prioritization (defined as whether or not ranking HIV as a top priority) is associated with risk behaviors, and (3) potential correlates of HIV prioritization. HIV was ranked as the most important priority by 37% of the participants. Among those who did not rank HIV as the top priority, housing, money, and safety from violence were particularly salient priorities. Those who gave the highest priority to HIV were less likely to have unprotected vaginal sex with primary partners who were HIV negative or of unknown serostatus, were less likely to split drugs with a used syringe, and used fewer numbers of injection drugs. HIV prioritization, however, was not associated with sex risk behaviors with nonprimary partners and HIV-positive primary partners. Significant correlates of HIV prioritization included age and the use of a heroin/stimulant mixture. These findings provide a number of important implications for HIV prevention intervention research for HIV-positive IDUs.

Adult↗

PubMed2003

Human auditory steady-state responses.

Steady-state evoked potentials can be recorded from the human scalp in response to auditory stimuli presented at rates between 1 and 200 Hz or by periodic modulations of the amplitude and/or frequency of a continuous tone. Responses can be objectively detected using frequency-based analyses. In waking subjects, the responses are particularly prominent at rates near 40 Hz. Responses evoked by more rapidly presented stimuli are less affected by changes in arousal and can be evoked by multiple simultaneous stimuli without significant loss of amplitude. Response amplitude increases as the depth of modulation or the intensity increases. The phase delay of the response increases as the intensity or the carrier frequency decreases. Auditory steady-state responses are generated throughout the auditory nervous system, with cortical regions contributing more than brainstem generators to responses at lower modulation frequencies. These responses are useful for objectively evaluating auditory thresholds, assessing suprathreshold hearing, and monitoring the state of arousal during anesthesia.

Acoustic Stimulation↗