Homonegativity, substance use, sexual risk behaviors, and HIV status in poor and ethnic men who have sex with men in Los Angeles

This study evaluates associations between internalized homonegativity and demographic factors, drug use behaviors, sexual risk behaviors, and HIV status among men who have sex with men (MSM) and with men and women (MSM/W). Participants were recruited in Los Angeles County using respondent-driven sampling (RDS) and completed the Internalized Homonegativity Inventory (IHNI) and questionnaires on demographic and behavioral factors. Biological samples were tested for HIV and for recent cocaine, methamphetamine, and heroin use. The 722 MSM and MSM/W participants were predominantly African American (44%) and Hispanic (28%), unemployed (82%), homeless (50%), and HIV positive (48%) who used drugs in the past 6 months (79.5%). Total and Personal Homonegativity, Gay Affirmation, and Morality of Homosexuality IHNI scores were significantly higher for African American men than for other ethnicities, for MSM/W than for MSM, for recent cocaine users than for recent methamphetamine users, and for HIV-seronegative men than for HIV-seropositive men. Linear regression showed the Gay Affirmation scale significantly and inversely correlated with the number of sexual partners when controlling for effects of ethnicity/race and sexual identification, particularly for men who self-identified as straight. Highest IHNI scores were observed in a small group of MSM/W (n = 62) who never tested for HIV. Of these, 26% tested HIV positive. Findings describe ways in which internalized homophobia is a barrier to HIV testing and associated HIV infection and signal distinctions among participants in this sample that can inform targeted HIV prevention efforts aimed at increasing HIV testing.

The longitudinal impact of HIV+ parents' drug use on their adolescent children

The impact of parental substance use on the emotional and behavioral adjustment of their adolescent children was examined over 5 years. A representative sample of 220 parents with HIV (PWH) and 330 adolescent children in New York City were repeatedly assessed. Some parents never used marijuana or hard drugs over the 5 years (nonusers). Among those who were users, substance use varied over time. PWH who used substances during a specific 3-month period were classified as active users and those who abstained from substance use were classified as inactive users. Longitudinal regression analyses were used to analyze the impact of variations in patterns of substance use over time on their adolescent children's emotional adjustment and behavioral problems. PWH relapse exacerbated adolescent substance use, trouble with peers, and adolescent emotional distress. Even time-limited reductions in parents' substance abuse can have a significant positive impact on their adolescent children's emotional and behavioral adjustment. Interventions that address parental substance use among PWH should be developed to ameliorate the impact of substance use relapse on their adolescents.

Prostate mechanical imaging: a new method for prostate assessment

OBJECTIVES

To evaluate the ability of prostate mechanical imaging (PMI) technology to provide an objective and reproducible image and to assess the prostate nodularity.

METHODS

We evaluated the PMI device developed by Artann Laboratories in a pilot clinical study. For the 168 patients (ages 44 to 94) who presented to an urologist for prostate evaluation, PMI-produced images and assessment of prostate size, shape, consistency/hardness, mobility, and nodularity were compared with digital rectal examination (DRE) findings. The PMI and DRE results were further tested for correlation against a transrectal ultrasound of the prostate (TRUS) guided biopsy for a subgroup of 21 patients with an elevated prostate-specific antigen level.

RESULTS

In 84% of the cases, the PMI device was able to reconstruct three-dimensional (3D) and 2D cross-sectional images of the prostate. The PMI System and DRE pretests were able to determine malignant nodules in 10 and 6 patients, respectively, of the 13 patients with biopsy-confirmed malignant inclusions. The PMI System findings were consistent with all 8 biopsy negative cases, whereas the DRE had 1 abnormal reading for this group. The correlation between PMI and DRE detection of palpable nodularity was 81%, as indicated by the area under the receiver operating characteristic curve. Estimates of the prostate size provided by PMI and DRE were statistically significantly correlated.

CONCLUSIONS

The PMI has the potential to enable a physician to obtain, examine, and store a 3D image of the prostate based on mechanical and geometrical characteristics of the gland and its internal structures.

Evaluation of a prevention intervention to reduce HIV Risk among Angolan soldiers

We developed and evaluated a military-focused HIV prevention intervention to enhance HIV risk-reduction knowledge, motivation, and behaviors among Angolan soldiers. Twelve bases were randomly assigned to HIV prevention or control conditions, yielding 568 participants. HIV prevention participants received training in preventing HIV (4.5 days) and malaria (0.5 days). Control participants received the reverse. Monthly booster sessions were available after each intervention. We assessed participants at baseline, 3 and 6 months after the training. HIV prevention participants reported greater condom use and less unprotected anal sex at 3 months, as well as greater HIV-related knowledge and perceived vulnerability at 3 and 6 months. Within-group analyses showed HIV prevention participants increased condom use, reduced unprotected vaginal sex, and reduced numbers of partners at both follow-ups, while control participants improved on some outcomes at 3 months only. A military-focused HIV prevention intervention may increase HIV-related knowledge, motivation, and risk reduction among African soldiers.

Predictors of sexual risk behaviors among newly homeless youth: a longitudinal study

PURPOSE

To longitudinally examine the association between newly homeless youth individual factors (sociodemographic characteristics, depression, substance use), and structural factors, such as living situation (family, institution, nonfamily), with sexual risk behaviors.

METHODS

A cohort of newly homeless youth from Los Angeles County (N = 261; aged 12-20 years) was interviewed at baseline, 3, 6, 12, 18, and 24 months. At each assessment youth were asked about symptoms of depression (using the Brief Symptom Inventory), substance use, living situation, and sexual risk behaviors (number of sexual partners and condom use). Random effects models were used to determine the effects of predictors on the number of sexual partners and on condom use over time, by gender.

RESULTS

At baseline, 77% of youth had been sexually active, increasing to 85% of youth at 24 months of follow-up. For predictors of multiple sexual partners, among male youth, these included living in nonfamily settings and using drugs; among females, living situation was not predictive of having multiple sexual partners but drug use was. For condom use, among females, living in a nonfamily setting and drug use decreased the odds of always using condoms; for males, no factors were found to be predictive of condom use.

CONCLUSIONS

Living with nonfamily members and drug use appear to be the most salient in explaining sexual risk among newly homeless youth. Our findings indicate that interventions aimed at reducing sexual risk behaviors, and thereby reducing sexually transmitted diseases and HIV among newly homeless youth, need to help youth in finding housing associated with supervision and social support (family and institutional settings) as well as aim to reduce drug use.

Evaluation of the validity of the Quality of Well-being Scale in Trinidad and Tobago

Both developing countries in the Caribbean and developed countries face resource allocation challenges. However, cost-effectiveness analysis instruments that may assist in allocation of resources have not been tested in Caribbean countries. Trinidad and Tobago is an advantageous location to test an instrument for potential use in the Caribbean. It has a single payer healthcare system and a literate population. Due to historical and current migration from other Caribbean countries, the population might be a fair representation of English-speaking Caribbean nations. We tested the validity of the Quality of Well-being Scale (QWB) on a sample of the non-institutionalized general population in Trinidad. The survey included reports of chronic conditions and items from the Trinidad and Tobago National Health Interview Survey. Data were analyzed using a multivariable regression model. One adult from each of 235 households consented to the interview. The results are consistent with results obtained in the United States of America. Being older female, more chronic conditions and more symptoms/problems were significantly associated with lower mean QWB scores. These results suggest that the QWB with US-derived weights show evidence of validity in Trinidad and Tobago. Thus, health decision makers can use the QWB to compare the effects of different health conditions and health interventions. In addition, investigators can make cross-cultural comparisons of QWB scores for diseases or health conditions.

Using Bayesian space-time models to understand the substance use environment and risk for being referred to child protective services

Parental substance misuse has often been cited as a cause of children being referred for investigation of child abuse and neglect. Research on how the substance use environment might affect this relationship is still in its infancy with primarily only cross-sectional studies finding a positive relationship of alcohol outlet density at the level of neighborhoods and alcohol prices at level of states and maltreatment. A longitudinal study shows that increasing female drug-related arrests are related to increasing rates of maltreatment in rural and urban counties. The current study incorporates three aspects of the substance use environment in a panel study of 58 California counties over 4 years (n = 232) to study this relationship for referrals to child protective services (CPS) for child abuse and neglect. We use conditionally autoregressive (CAR) Bayesian models to model the spatial and temporal structure in the data. We find that use of welfare benefits, the number of outliers per population, and the number of drug-related arrests per population are positively related to referrals while unemployment and admissions to publicly funded alcohol and drug user treatment programs are negatively correlated to referrals. Significant spatial structure and space-time relationships are also found. The findings indicate that supply of alcohol and drugs (as measured by number of alcohol outlets and arrests for drug use and sales) may increase risk for being referred to CPS, but treatment for substance use does not increase the risk for referral.

A hierarchical semiparametric regression model for combining HIV-1 phylogenetic analyses using iterative reweighting algorithms

Phylogenetic modeling is computationally challenging and most phylogeny models fit a single phylogeny to a single set of molecular sequences. Individual phylogenetic analyses are typically performed independently using publicly available software that fits a computationally intensive Bayesian model using Markov chain Monte Carlo (MCMC) simulation. We develop a Bayesian hierarchical semiparametric regression model to combine multiple phylogenetic analyses of HIV-1 nucleotide sequences and estimate parameters of interest within and across analyses. We use a mixture of Dirichlet processes as a prior for the parameters to relax inappropriate parametric assumptions and to ensure the prior distribution for the parameters is continuous. We use several reweighting algorithms for combining completed MCMC analyses to shrink parameter estimates while adjusting for data set-specific covariates. This avoids constructing a large complex model involving all the original data, which would be computationally challenging and would require rewriting the existing stand-alone software.

On models for binomial data with random numbers of trials

A binomial outcome is a count s of the number of successes out of the total number of independent trials n=s+f, where f is a count of the failures. The n are random variables not fixed by design in many studies. Joint modeling of (s, f) can provide additional insight into the science and into the probability pi of success that cannot be directly incorporated by the logistic regression model. Observations where n= 0 are excluded from the binomial analysis yet may be important to understanding how pi is influenced by covariates. Correlation between s and f may exist and be of direct interest. We propose Bayesian multivariate Poisson models for the bivariate response (s, f), correlated through random effects. We extend our models to the analysis of longitudinal and multivariate longitudinal binomial outcomes. Our methodology was motivated by two disparate examples, one from teratology and one from an HIV tertiary intervention study.

Reductions in drug use among young people living with HIV

ZIP models were used to detect reductions in drug abuse among young people living with HIV (YPLH) over 15 months when most young people abstain from use. YPLH (n = 171) aged 16 to 29 years were randomly assigned to an 18 session intervention or a delayed-intervention condition. The ZIP models showed significant reductions in abuse of multiple substances over time in the non-delayed intervention. Previous analyses did not find significant reductions. Intervention efficacy often cannot be detected if there are highly skewed distributions of outcomes, such as drug abuse. ZIP modeling offers an opportunity to more reliably detect behavioral changes.

Iodine deficiency activates antioxidant genes and causes DNA damage in the thyroid gland of rats and mice

Because thyroid nodules are frequent in areas with iodine deficiency the aim of this study was to characterise molecular events during iodine deficiency that could explain mutagenesis and nodule formation. We therefore studied gene expression of catalytic enzymes prominent for H(2)O(2) detoxification and antioxidative defence, quantified DNA oxidation and damage as well as spontaneous mutation rates (SMR) in mice and rats fed an iodine controlled diet. Antioxidative enzymes such as superoxide dismutase 3, glutathione peroxidase 4 and the peroxiredoxins 3 and 5 showed increased mRNA expression, which indicates increased radical burden that could be the cause of additional oxidized base adducts found in thyroidal genomic DNA in our experiments of iodine deficiency. Furthermore, the uracil content of thyroid DNA was significantly higher in the iodine-deficient compared to the control group. While SMR is very high in the normal thyroid gland it is not changed in experimental iodine deficiency. Our data suggest that iodine restriction causes oxidative stress and DNA modifications. A higher uracil content of the thyroid DNA could be a precondition for C-->T transitions often detected as somatic mutations in nodular thyroid tissue. However, the absence of increased SMR would argue for more efficient DNA repair in response to iodine restriction.

HIV-1 viral fitness estimation using exchangeable on subsets priors and prior model selection

The phenotype-genotype problem is a fundamental problem of biology where an organism's genotype (genetic information) predicts its phenotype (observable characteristic). Viral fitness, defined as the reproductive capacity of a virus compared to a standard, is a continuous phenotype. We construct models to predict viral fitness as a function of mutation away from the standard wildtype virus. Data of this nature are difficult to analyse because there are potentially many more parameters than observations. We treat this issue as a regression problem using a prior with both a shrinkage component and a variable selection component. The key to practical implementation of the model is the prior specification for the regression coefficients. We use results from the scientific literature to construct several informative exchangeable within subsets priors (ESP). We use prior model selection (PMS) to select among our priors. Two novel graphics present results from five models each with 71 predictors.

Time squared: repeated measures on phylogenies

Studies of gene expression profiles in response to external perturbation generate repeated measures data that generally follow nonlinear curves. To explore the evolution of such profiles across a gene family, we introduce phylogenetic repeated measures (PR) models. These models draw strength from 2 forms of correlation in the data. Through gene duplication, the family's evolutionary relatedness induces the first form. The second is the correlation across time points within taxonic units, individual genes in this example. We borrow a Brownian diffusion process along a given phylogenetic tree to account for the relatedness and co-opt a repeated measures framework to model the latter. Through simulation studies, we demonstrate that repeated measures models outperform the previously available approaches that consider the longitudinal observations or their differences as independent and identically distributed by using deviance information criteria as Bayesian model selection tools; PR models that borrow phylogenetic information also perform better than nonphylogenetic repeated measures models when appropriate. We then analyze the evolution of gene expression in the yeast kinase family using splines to estimate nonlinear behavior across 3 perturbation experiments. Again, the PR models outperform previous approaches and afford the prediction of ancestral expression profiles. To demonstrate PR model applicability more generally, we conclude with a short examination of variation in brain development across 4 primate species.

A case of ACTH-independent bilateral macronodular adrenal hyperplasia and severe congestive heart failure

Cortisol secretion in ACTH independent bilateral macronodular adrenal hyperplasia (AIMAH) can be regulated by aberrant adrenal receptors. We describe a patient with Cushing's syndrome (CS) due to AIMAH and concomitant Class IV congestive heart failure (CHF). Clinical testing for the presence of aberrant receptors revealed a pronounced serum cortisol (257%) and aldosterone response (212%) to the administration of ACTH and a partial serum cortisol (35%) and aldosterone (106%) response to upright posture. This suggested the possible presence of aberrant hormone receptors for ACTH [melanocortin 2 receptor (MC2-R)], vasopressin, catecholamines or angiotensin II (AT-II) on the patient's adrenal glands. Adrenal tissue from the patient demonstrated an eight-fold increased expression of MC2-R compared to normal adrenal tissue. This increased expression was consistent with the increase in cortisol and aldosterone seen in response to exogenous ACTH. We propose that the severe CHF resulted in activation of the renin-angiotensin system, with an increased production of AT-II. The elevated circulating levels of AT-II may have led to increased expression of MC2-R on the patient's adrenal glands and increased responsiveness to ACTH. This unusual case of CS may elucidate a heretofore unknown mechanism for the development of AIMAH.

Newly homeless youth STD testing patterns over time

PURPOSE

To use the Behavioral Model for Vulnerable Populations to examine the predisposing and need characteristics of newly homeless youth that are associated with sexually transmitted disease (STD) testing over time.

METHODS

A longitudinal cohort of newly homeless youth from Los Angeles County (n = 261; ages 12-20 years) were followed for 24 months. Youth were interviewed at baseline, 3, 6, 12, 18, and 24 months, and asked about their background, housing situation, emotional distress (using the Brief-Symptom Inventory), substance use, sexual risk behaviors, and their STD testing rates. We modeled our longitudinal data using logistic random effects models.

RESULTS

Characteristics of homeless youth that were associated with STD testing in our multivariate model included time in study (odds ratio [OR] 1.3, 95% confidence interval [CI] 1.1-1.6), age at baseline (OR 1.2, 95% CI 1.1-1.4), being African-American (OR 2.7, 95% CI 1.4-5.3), being from a mixed race/ethnic group (OR 2.8, 95% CI 1.3-5.8), self-identifying as a gay/bisexual male (OR 2.9, 95% CI 1.2-6.9), self-identifying as a heterosexual female (OR 2.2, 95% CI 1.3-3.7), using amphetamines (OR 1.7, 95% CI 1.1-2.6), and history of having gotten someone/becoming pregnant (OR 2.3, 95% CI 1.4-3.9). Youth who lived in an apartment were less likely to have received an STD test than youth who lived in other types of housing (OR .4, 95% CI .2-.9). Sexual risk behaviors such as inconsistent condom use (OR 1.0, 95% CI .6-1.4) and number of sexual partners over past 3 months (OR 1.1, 95% CI 1.0-1.1) were not predictive of STD testing over time.

CONCLUSIONS

A need exists for interventions to target young newly homeless youth who engage in high-risk sexual behaviors to increase their STD testing rates and thereby decrease their risk for HIV infection.

A Bayesian heterogeneous analysis of variance approach to inferring recent selective sweeps

The distribution of microsatellite allele sizes in populations aids in understanding the genetic diversity of species and the evolutionary history of recent selective sweeps. We propose a heterogeneous Bayesian analysis of variance model for inferring loci involved in recent selective sweeps by analyzing the distribution of allele sizes at multiple loci in multiple populations. Our model is shown to be consistent with a multilocus test statistic, ln RV, proposed for identifying microsatellite loci involved in recent selective sweeps. Our methodology differs in that it accepts original allele size data rather than summary statistics and allows the incorporation of prior knowledge about allele frequencies using a hierarchical prior distribution consisting of log normal and gamma probability distributions. Interesting features of the model are its ability to simultaneously analyze allele size data for any number of populations and to cope with the presence of any number of selected loci. The utility of the method is illustrated by application to two sets of microsatellite allele size data for a group of West African Anopheles gambiae populations. The results are consistent with the suppressed-recombination model of speciation, and additional candidate loci on chromosomes 2 (079 and 175) and 3 (088) are discovered that escaped former analysis.

Changing Behaviors and Patterns Among Cambodian Sex Workers

OBJECTIVE

Identify patterns and behaviors among direct and indirect female sex workers (DFSWs and IDFSWs, respectively) across Cambodia's 5 major cities from 1997 to 2003.

METHODS

Interviews with DFSWs and IDFSWs followed random selection from clusters in 5 cities. Individual characteristics and condom use with clients and other partners were assessed in univariate and multivariate analyses.

RESULTS

From 1997 to 2003, consistent condom use with clients increased from 53% to 96% among DFSWs and from 30% to 84% among IDFSWs. DFSWs reported staying in their profession longer, had fewer clients per day, stayed longer in each brothel, were in increasingly larger brothels, and were tested more for HIV. For IDFSWs, there were significant changes: more reported practicing commercial sex and testing for HIV. In adjusted models, reported condom use with clients was significantly higher among DFSWs in later survey years (odds ratio [OR], 2.17) and who were never married (OR, 1.69), were in larger brothels (OR, 1.02), and charged more for sex (OR, 1.27), but lower for DFSWs with sweethearts (OR, 0.68) and who reported abnormal vaginal discharge (OR, 0.52). For IDFSWs, in the adjusted models, reported condom use with clients was higher in later years (OR, 1.77) and for those reporting abnormal vaginal discharge (OR, 1.34) and HIV testing (OR, 1.46), and lower for those with sweethearts (OR, 0.49).

CONCLUSIONS

From 1997 to 2003, Cambodian direct and indirect sex workers increased their use of condoms each year with commercial as well as noncommercial partners, contributing to the evidence that HIV prevention programs can produce significant changes in risk behaviors.