OBJECTIVE:To evaluate for changes in sexual behaviors associated with daily pill use among men who have sex with men (MSM) participating in a preexposure prophylaxis trial.
DESIGN:Randomized, ...double-blind, placebo-controlled trial. Participants were randomized 1:1:1:1 to receive tenofovir disoproxil fumarate or placebo at enrollment or after a 9-month delay and followed for 24 months.
METHODS:Four hundred HIV-negative MSM reporting anal sex with a man in the past 12 months and meeting other eligibility criteria enrolled in San Francisco, Atlanta, and Boston. Sexual risk was assessed at baseline and quarterly visits using Audio Computer-Assisted Self-Interview. The association of pill taking with sexual behavior was evaluated using logistic and negative-binomial regressions for repeated measures.
RESULTS:Overall indices of behavioral risk declined or remained stable during follow-up. Mean number of partners and proportion reporting unprotected anal sex declined during follow-up (P < 0.05), and mean unprotected anal sex episodes remained stable. During the initial 9 months, changes in risk practices were similar in the group that began pills immediately vs. those in the delayed arm. These indices of risk did not differ significantly after initiation of pill use in the delayed arm or continuation of study medication in the immediate arm. Use of poppers, amphetamines, and sexual performance–enhancing drugs were independently associated with one or more indices of sexual risk.
CONCLUSIONS:There was no evidence of risk compensation among HIV-uninfected MSM in this clinical trial. Monitoring for risk compensation should continue now that preexposure prophylaxis has been shown to be efficacious in MSM and other populations and will be provided in open-label trials and other contexts.
OBJECTIVES:To evaluate the clinical safety of daily tenofovir disoproxil fumarate (TDF) among HIV-negative men who have sex with men.
DESIGN:Randomized, double-blind, placebo-controlled trial. ...Participants were randomized 1:1:1:1 to immediate or delayed study drug (TDF, 300 mg orally per day, or placebo).
METHODS:Four hundred healthy HIV-uninfected men who have sex with men reporting anal sex with another man within the previous 12 months enrolled in Atlanta, Boston, and San Francisco. HIV serostatus, clinical and laboratory adverse events (AEs), adherence (pill count, Medication Event Monitoring System, and self-report), and sexual and other sociobehavioral data were assessed at 3-month intervals for 24 months. Primary outcomes were clinical safety, assessed by incidence of AEs and laboratory abnormalities.
RESULTS:Study drug was initiated by 373 (93%) participants (186 TDF and 187 placebo), of whom 325 (87%) completed the final study visit. Of 2428 AEs reported among 334 (90%) participants, 2366 (97%) were mild or moderate in severity. Frequencies of commonly reported AEs did not differ significantly between TDF and placebo arms. In multivariable analyses, back pain was more likely among TDF recipients (P = 0.04); these reports were not associated with documented fractures or other objective findings. There were no grade ≥3 creatinine elevations; grades 1 and 2 creatinine increases were not associated with TDF receipt. Estimated percentage of study drug doses taken was 92% by pill count and 77% by Medication Event Monitoring System. Seven seroconversions occurred4 on placebo and 3 among delayed arm participants not yet on study drug.
CONCLUSIONS:Daily oral TDF was well tolerated, with reasonable adherence. No significant renal concerns were identified.
Various metrics for HIV burden and treatment success e.g. HIV prevalence, community viral load (CVL), population viral load (PVL), percent of HIV-positive persons with undetectable viral load have ...important public health limitations for understanding disparities.
Using data from an ongoing HIV incidence cohort of black and white men who have sex with men (MSM), we propose a new metric to measure the prevalence of those at risk of transmitting HIV and illustrate its value. MSM with plasma VL>400 copies/mL were defined as having 'transmission risk'. We calculated HIV prevalence, CVL, PVL, percent of HIV-positive with undetectable viral loads, and prevalence of plasma VL>400 copies/ml (%VL400) for black and white MSM. We used Monte Carlo simulation incorporating data on sexual mixing by race to estimate exposure of black and white HIV-negative MSM to a partner with transmission risk via unprotected anal intercourse (UAI). Of 709 MSM recruited, 42% (168/399) black and 14% (44/310) white MSM tested HIV-positive (p<.0001). No significant differences were seen in CVL, PVL, or percent of HIV positive with undetectable viral loads. The %VL400 was 25% (98/393) for black vs. 8% (25/310) for white MSM (p<.0001). Black MSM with 2 UAI partners were estimated to have 40% probability (95% CI: 35%, 45%) of having ≥1 UAI partner with transmission risk vs. 20% for white MSM (CI: 15%, 24%).
Despite similarities in other metrics, black MSM in our cohort are three times as likely as white MSM to have HIV transmission risk. With comparable risk behaviors, HIV-negative black MSM have a substantially higher likelihood of encountering a UAI partner at risk of transmitting HIV. Our results support increasing HIV testing, linkage to care, and antiretroviral treatment of HIV-positive MSM to reduce prevalence of those with transmission risk, particularly for black MSM.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Pre-exposure prophylaxis (PrEP) trials are evaluating regimens containing tenofovir-disoproxil fumarate (TDF) for HIV prevention. We determined the baseline prevalence of low bone mineral density ...(BMD) and the effect of TDF on BMD in men who have sex with men (MSM) in a PrEP trial in San Francisco.
We evaluated 1) the prevalence of low BMD using Dual Energy X-ray Absorptiometry (DEXA) in a baseline cohort of 210 HIV-uninfected MSM who screened for a randomized clinical trial of daily TDF vs. placebo, and 2) the effects of TDF on BMD in a longitudinal cohort of 184 enrolled men. Half began study drug after a 9-month delay to evaluate changes in risk behavior associated with pill-use. At baseline, 20 participants (10%) had low BMD (Z score≤-2.0 at the L2-L4 spine, total hip, or femoral neck). Low BMD was associated with amphetamine (OR = 5.86, 95% CI 1.70-20.20) and inhalant (OR = 4.57, 95% CI 1.32-15.81) use; men taking multivitamins, calcium, or vitamin D were less likely to have low BMD at baseline (OR = 0.26, 95% CI 0.10-0.71). In the longitudinal analysis, there was a 1.1% net decrease in mean BMD in the TDF vs. the pre-treatment/placebo group at the femoral neck (95% CI 0.4-1.9%), 0.8% net decline at the total hip (95% CI 0.3-1.3%), and 0.7% at the L2-L4 spine (95% CI -0.1-1.5%). At 24 months, 13% vs. 6% of participants experienced >5% BMD loss at the femoral neck in the TDF vs. placebo groups (p = 0.13).
Ten percent of HIV-negative MSM had low BMD at baseline. TDF use resulted in a small but statistically significant decline in BMD at the total hip and femoral neck. Larger studies with longer follow-up are needed to determine the trajectory of BMD changes and any association with clinical fractures.
ClinicalTrials.gov: NCT00131677.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We tested a couples HIV testing and counseling (CHTC) intervention with male couples in Atlanta by randomizing eligible couples to receive either CHTC or separate individual voluntary HIV counseling ...and testing (iVCT). To evaluate the acceptability and safety of CHTC, main outcomes were satisfaction with the intervention and the proportions of couples reporting intimate partner violence (IPV) and relationship dissolution after the service. The results indicated that the service was very acceptable to men (median 7-item index of satisfaction was 34 for CHTC and 35 for iVCT, P = .4). There was no difference in either incident IPV (22% versus 17% for CHTC and iVCT, respectively, P = .6) or relationship dissolution (42% versus 51% for CHTC and iVCT, respectively, P = .5). Based on the preliminary data, CHTC is safe for male couples, and it is equally acceptable to iVCT for men who have main partners.
In the United States, a substantial proportion of HIV transmissions among men who have sex with men (MSM) arise from main sex partners. Couples voluntary HIV testing and counseling (CHTC) is used in ...many parts of the world with male–female couples, but CHTC has historically not been available in the U.S. and few data exist about the extent of HIV serodiscordance among U.S. male couples. We tested partners in 95 Atlanta male couples (190 men) for HIV. Eligible men were in a relationship for ≥3 months and were not known to be HIV-positive. We calculated the prevalence of couples that were seroconcordant HIV-negative, seroconcordant HIV-positive, or HIV serodiscordant. We evaluated differences in the prevalence of HIV serodiscordance by several dyadic characteristics (e.g., duration of relationship, sexual agreements, and history of anal intercourse in the relationship). Overall, among 190 men tested for HIV, 11 % (
n
= 20) were newly identified as HIV-positive. Among the 95 couples, 81 % (
n
= 77) were concordant HIV-negative, 17 % (
n
= 16) were HIV serodiscordant, and 2 % (
n
= 2) were concordant HIV-positive. Serodiscordance was not significantly associated with any evaluated dyadic characteristic. The prevalence of undiagnosed HIV serodiscordance among male couples in Atlanta is high. Offering testing to male couples may attract men with a high HIV seropositivity rate to utilize testing services. Based on the global evidence base for CHTC with heterosexual couples and the current evidence of substantial undiagnosed HIV serodiscordance among U.S. MSM, we recommend scale-up of CHTC services for MSM, with ongoing evaluation of acceptability and couples’ serostatus outcomes.
•Technology development must be aligned with key trends in decarbonization.•Costs reductions are needed. We rank options by value and feasibility.•Reduction in fuel cell component costs is essential ...to commercial success.•Fuel cell cost reductions are most important.•Innovations in systems design and materials can also reduce cost.
Does generation of zero-carbon electricity from coal make sense for a decarbonized grid? Coal-based integrated gasification fuel cell systems with CO2 capture have the potential to participate in future decarbonized power grids. Over the next decade, such systems are scheduled to progress from a conceptual scheme to its first demonstration projects in China and Japan. A key issue in the long-term viability of the technology will be reducing costs so they are competitive against other forms of zero-carbon electricity; in addition, the systems must be able to operate as part of low carbon grids. We systematically evaluate the major on-going research directions, and rank them according to their economic potential, degree of technical challenge, and possible synergies with other efforts to transition to low-carbon energy systems worldwide. Our analysis indicates that the most promising pathway to making integrated gasification fuel cell technologies cost-competitive against other forms of low-carbon electricity is co-deployment of solid oxide fuel cell technologies in integrated gasification fuel cell cycle and distributed energy applications to expand the scale of production to a level that benefits both areas. Other avenues based on system optimization or improvements in fuel cell performance or degradation through materials development can help, but cannot by themselves deliver cost-competitive electricity absent an order of magnitude reduction in the cost of solid oxide fuel cell components.
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We here present and analyze a novel conceptual design of 550 MW-level, syngas-fueled intermediate-temperature solid oxide fuel cell (SOFC)/Air Turbine (AT) hybrid system with an oxy-fuel combustion. ...To decouple the operation of SOFC and AT and allow independent operation of each, an intermediate heat exchanger is implemented between SOFC and AT cycles to transfer only heat from SOFC to AT. To facilitate CO2 separation and capture, the gas streams from both electrodes are separately operated and pure O2 is used in the afterburner for combustion. A total of four scenarios has been analyzed to cover the effects of current density, pressure and staged SOFC design. The results show that by elevating the pressure to 10 atm and using two-stage SOFC design, the system can achieve an overall efficiency of 64% at a nominal power output. The work provides important engineering insights in SOFC staged design and operating conditions for the next-generation SOFC/turbine hybrid systems.
•A MW-level syngas-fueled solid oxide fuel cell/Air Turbine hybrid system.•An intermediate heat exchanger between SOFC and AT.•Pressure and multi-stage SOFC design effects on the overall system efficiency.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Explored the effect of practical issues in body heat thermoelectric energy harvester.•Suggested optimal/practical geometries for the heat sink and thermoelectric module.•Considered the effect of a ...boost converter’s voltage dependent efficiency.•Estimated power output of 0.48mW within a wearable area.
Recent studies on improving the thermoelectric figure of merit (ZT) have advanced research into self-powered, wearable technologies using thermoelectric generators. However, previous design approaches do not consider structurally practical heat sink and module geometries, the use of a boost converter, or the size constraint of the generator due to aesthetic appeal, all of which lower the overall power output. Additionally, the reduced efficiency in using a boost converter changes the electrical and thermal load matching conditions for maximum power. In this study, the limitations of practicality were considered for a wearable thermoelectric generator that utilizes a state-of-the-art boost converter and an optimized heat sink. Heat sink fin geometries and thermoelectric module geometries were explored to maximize the power output within a 42.0cm2 area and a 1.0cm total height, in order to justify the wearability of the energy harvester. With optimized values of fin and module heights, the system was designed to produce 0.48mW of electrical power at a boosted output voltage of 3.0V, enough to power a small heart-rate monitor.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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