Surface ozone and its precursors at Summit, Greenland: Comparison between observations and model simulations

Recent studies have shown significant challenges for atmospheric models to simulate tropospheric ozone (O3/and its precursors in the Arctic. In this study, ground-based data were combined with a global 3-D chemical transport model (GEOS-Chem) to examine the abundance and seasonal variations of O3 and its precursors at Summit, Greenland (72.34° N, 38.29° W; 3212 ma.s.l.). Model simulations for atmospheric nitrogen oxides (NOx/, peroxyacetyl nitrate (PAN), ethane (C2H6/, propane (C3H8/, carbon monoxide (CO), and O3 for the period July 2008-June 2010 were compared with observations. The model performed well in simulating certain species (such as CO and C3H8/, but some significant discrepancies were identified for other species and further investigated. The model generally underestimated NOx and PAN (by ∼50 and 30 %, respectively) for March-June. Likely contributing factors to the low bias include missing NOx and PAN emissions from snowpack chemistry in the model. At the same time, the model overestimated NOx mixing ratios by more than a factor of 2 in wintertime, with episodic NOx mixing ratios up to 15 times higher than the typical NOx levels at Summit. Further investigation showed that these simulated episodic NOx spikes were always associated with transport events from Europe, but the exact cause remained unclear. The model systematically overestimated C2H6 mixing ratios by approximately 20% relative to observations. This discrepancy can be resolved by decreasing anthropogenic C2H6 emissions over Asia and the US by ∼20 %, from 5.4 to 4.4 Tg year-1. GEOS-Chem was able to reproduce the seasonal variability of O3 and its spring maximum. However, compared with observations, it underestimated surface O3 by approximately 13% (6.5 ppbv) from April to July. This low bias appeared to be driven by several factors including missing snowpack emissions of NOx and nitrous acid in the model, the weak simulated stratosphereto-troposphere exchange flux of O3 over the summit, and the coarse model resolution

Lack of Awareness of Partner STD Risk Among Heterosexual Couples

CONTEXT: Individuals’ accurate assessment of their exposure to the risk of HIV and other STDs requires awareness of their sexual partners’ risk behaviors and disease status. METHODS: In a sample of 217 couples enrolled in a risk intervention trial in 1997–2002, both partners reported on their own risk behaviors and their perceptions of their partner's behavior; concordance of partners’ reports was examined using kappa statistics. Individual and relationship characteristics predicting lack of awareness of a partner's risk behavior were explored using multivariate logistic regression. RESULTS: Three percent of women and 14% of men were unaware that their partner had recently had a concurrent partner. Eleven percent and 12%, respectively, were unaware that their partner had ever injected drugs; 10% and 12% were unaware that their partner had recently received an STD diagnosis; and 2% and 4% were unaware that their partner was HIV‐positive. Women's lack of awareness of partner risk was associated with increasing age (odds ratio, 1.1), being of a race or ethnicity other than black or Latina (15.8) and having a Latino partner (3.7); it was positively associated with a man's report that he was married (4.4) and with relationship satisfaction as reported by both the woman and her partner (1.2 for each). Among men, lack of awareness was positively associated with partner's age (1.1) and with having a partner who was formerly married (8.2). CONCLUSIONS: Couple‐based interventions that assess each partner's awareness of the other's risk behavior may help programs better target couples’ STD prevention needs

Predictors of Discordant Reports of Sexual and HIV/Sexually Transmitted Infection Risk Behaviors Among Heterosexual Couples

Objectives: Assessments undertaken as part of couple-based HIV/sexually transmitted infection (STI) prevention intervention studies offer opportunities to expand our understanding of couple reporting of sexual and HIV/STI risk behavior. Increases in heterosexual transmission of HIV worldwide support more attention on the quality and use of couple-level sexual risk assessment. Study Design: This study examined interpartner concordance of self-reported sexual behaviors and HIV/STI risk behaviors among 217 women and their main male sexual partners at high risk for HIV/STI transmission and further explored specific individual and relationship characteristics by partner gender associated with discordant reporting of sexual and HIV/STI risk behaviors. Results: Consistent with prior studies, findings suggest fair to substantial agreement between partners on reports of most sexual and HIV/STI risk behavior, but only poor to fair agreement on reports of concurrent sexual behaviors and drug or alcohol use. Factors significantly associated with discordant reporting of sexual behaviors included length of couple relationship, level of relationship satisfaction, female partner’s marital status, and male partner’s HIV status, ethnicity, and age. Conclusions: Individual- and relationship-level factors predicting discordant partner reports of sexual and sexual risk behaviors highlight an opportunity to improve couple assessment by anticipating such discrepancies and developing effective mechanisms of quality assurance to avoid, address, or better explain such discordance in couple data sets

Intimate Partner Violence and HIV Among Drug-Involved Women: Contexts Linking These Two Epidemics—Challenges and Implications for Prevention and Treatment

Intimate partner violence (IPV) and HIV are two serious overlapping public health epidemics that disproportionately affect drug-involved women. This article reviews research that has identified a number of contexts that may explain the links between IPV and HIV transmission risks. These contexts include sexual coercion, fear of violence, negotiation of condom use, extra dyadic relationships, disclosure of sexually transmitted infections or HIV seropositivity to intimate partners, drug involvement of women and their male partners, low social status of drug-involved women, relationship dependencies, and sex ratio imbalances. The article focuses on how the bidirectional relationship between IPV and HIV risks may be mediated by a history of childhood sexual abuse and post-traumatic stress disorder. Also addressed are the challenges that substance user treatment programs face in dealing with female clients who experience IPV and the implications for HIV prevention

Atg6 is required for multiple vesicle trafficking pathways and hematopoiesis in Drosophila

Atg6 (beclin 1 in mammals) is a core component of the Vps34 complex that is required for autophagy. Beclin 1 (Becn1) functions as a tumor suppressor, and Becn1(+/-) tumors in mice possess elevated cell stress and p62 levels, altered NF-kappaB signaling and genome instability. The tumor suppressor function of Becn1 has been attributed to its role in autophagy, and the potential functions of Atg6/Becn1 in other vesicle trafficking pathways for tumor development have not been considered. Here, we generate Atg6 mutant Drosophila and demonstrate that Atg6 is essential for autophagy, endocytosis and protein secretion. By contrast, the core autophagy gene Atg1 is required for autophagy and protein secretion, but it is not required for endocytosis. Unlike null mutants of other core autophagy genes, all Atg6 mutant animals possess blood cell masses. Atg6 mutants have enlarged lymph glands (the hematopoietic organ in Drosophila), possess elevated blood cell numbers, and the formation of melanotic blood cell masses in these mutants is not suppressed by mutations in either p62 or NFkappaB genes. Thus, like mammals, altered Atg6 function in flies causes hematopoietic abnormalities and lethality, and our data indicate that this is due to defects in multiple membrane trafficking processes

A Glutamate-Dependent Redox System in Blood Cells Is Integral for Phagocytosis in Drosophila melanogaster

SummaryGlutamate transport is highly regulated as glutamate directly acts as a neurotransmitter [1–3] and indirectly regulates the synthesis of antioxidants [4, 5]. Although glutamate deregulation has been repeatedly linked to serious human diseases such as HIV infection and Alzheimer’s [6–8], glutamate’s role in the immune system is still poorly understood. We find that a putative glutamate transporter in Drosophila melanogaster, polyphemus (polyph), plays an integral part in the fly’s immune response. Flies with a disrupted polyph gene exhibit decreased phagocytosis of microbial-derived bioparticles. When infected with S. aureus, polyph flies show an increase in both susceptibility and bacterial growth. Additionally, the expression of two known glutamate transporters, genderblind and excitatory amino acid transporter 1, in blood cells affects the flies’ ability to phagocytose and survive after an infection. Consistent with previous data showing a regulatory role for glutamate transport in the synthesis of the major antioxidant glutathione, polyph flies produce more reactive oxygen species (ROS) as compared to wild-type flies when exposed to S. aureus. In conclusion, we demonstrate that a polyph-dependent redox system in blood cells is necessary to maintain the cells’ immune-related functions. Furthermore, our model provides insight into how deregulation of glutamate transport may play a role in disease

Enrollment of minority women and their main sexual partners in an HIV/STI prevention trial

There is a paucity of empirical reports that quantitatively assess the success of recruitment strategies in randomized clinical trials (RCTs) using sampling units other than the individual. As innovations in HIV and sexually transmitted infection (STI) preventive intervention protocols and targets of change evolve, there is a need to examine the efficacy of attendant adaptations to recruitment protocols and strategies in the enrollment of study participants. This article examines factors related to enrollment of women and their main, male sexual partners in an RCT of a relationship–based HIV/STI preventive intervention conducted from 1997 to 2001. Among eligible participants (N = 388), findings indicate that race/ethnicity, employment status, marital status, and language preference were significantly associated with enrollment among eligible, potential participants. Additionally, being HIV–positive and having a past or current STI were significantly associated with enrollment. These findings underscore the need to ensure sufficient representation of all risk groups in RCTs, especially those testing innovative HIV/STI preventive intervention approaches or using novel enrollment strategies

Promoting Female Condom Use to Heterosexual Couples: Findings from a Randomized Clinical Trial

CONTEXT: The female condom remains the only female‐initiated method for preventing pregnancy and STDs, including HIV. Innovative methods for promoting its use, and for involving male partners in its use, are needed. METHODS: A sample of 217 women and their main male sexual partners were randomly assigned to one of three study conditions: a six‐session relationship‐based STD prevention intervention provided to the couple together, the same intervention provided to the woman only or a single‐session education control provided to the woman only. Assessments were conducted at baseline and three months postintervention. Contrast coding was used to examine whether the effects of the two active interventions differed from those of the control intervention, and whether the effects of the two active interventions differed from each other. Regression analyses were used to estimate treatment effects. RESULTS: During follow‐up, participants in either active intervention were more likely to use a female condom with their study partner and with all partners, and used female condoms at a higher rate with all partners, than individuals assigned to the control intervention; at the end of three months, they were more likely to intend to use the condom in the next 90 days. No significant differences in outcomes were found between the active intervention groups. CONCLUSIONS: Focusing on both a woman and her main male sexual partner is efficacious in increasing female condom use and intention to use among heterosexual couples at risk for HIV and other STDs

Couple-Based HIV Prevention in the United States: Advantages, Gaps, and Future Directions

This article presents an overview of couple-based HIV prevention research to date, advantages of using and core components of couple-based interventions, gaps in the current understanding of couple-based HIV prevention, status of dissemination research and the transportability of effective couple-based HIV prevention and treatment to real-world settings, and recommendations for future directions in couple-based prevention and treatment. Couple-based studies conducted among several populations—heterosexuals, men who have sex with men, and drug users—reported in the research literature were reviewed. Commonalities and limitations were noted in customary focus areas of the couple-based approaches: sexual and drug risk reduction, HIV testing behaviors, adherence to HIV treatment, and prevention of mother-to-child transmission. Couple-based intervention strategies have been rigorously tested and are a valuable addition to the arsenal of HIV prevention strategies. Immediate needs and opportunities include couple-based intervention strategies for prevention of HIV and other sexually transmitted infections among serodiscordant couples, couples who do not know their HIV status, and couples in whom both partners are HIV negative, but at risk of HIV infection. There is a particular need to develop couple-based intervention strategies for men who have sex with men and for drug-involved couples