Enhancements in laser-generated hot-electron production via focusing cone targets at short pulse and high contrast

We report on the increase in the accelerated electron number and energy using compound parabolic concentrator (CPC) targets from a short-pulse (∼150 fs), high-intensity (>10^{18} W/cm^{2}), and high-contrast (∼10^{8}) laser-solid interaction. We report on experimental measurements using CPC targets where the hot-electron temperature is enhanced up to ∼9 times when compared to planar targets. The temperature measured from the CPC target is 〈T_{e}〉=4.4±1.3 MeV. Using hydrodynamic and particle in cell simulations, we identify the primary source of this temperature enhancement is the intensity increase caused by the CPC geometry that focuses the laser, reducing the focal spot and therefore increasing the intensity of the laser-solid interaction, which is also consistent with analytic expectations for the geometrical focusing.

Visual Search in 3D: Effects of Monoscopic and Stereoscopic Cues to Depth on the Validity of Feature Integration Theory and Perceptual Load Theory

Previous research has successfully used feature integration theory to operationalise the predictions of Perceptual Load Theory, while simultaneously testing the predictions of both models. Building on this work, we test the extent to which these models hold up in a 3D world. In two experiments, participants responded to a target stimulus within an array of shapes whose apparent depth was manipulated using a combination of monoscopic and stereoscopic cues. The search task was designed to test the predictions of (a) feature integration theory, as the target was identified by a single feature or a conjunction of features and embedded in search arrays of varying size, and (b) perceptual load theory, as the task included congruent and incongruent distractors presented alongside search tasks imposing high or low perceptual load. Findings from both experiments upheld the predictions of feature integration theory, regardless of 2D/3D condition. Longer search times in conditions with a combination of monoscopic and stereoscopic depth cues suggests that binding features into three-dimensional objects requires greater attentional effort. This additional effort should have implications for perceptual load theory, yet our findings did not uphold its predictions; the effect of incongruent distractors did not differ between conjunction search trials (conceptualised as high perceptual load) and feature search trials (low perceptual load). Individual differences in susceptibility to the effects of perceptual load were evident and likely explain the absence of load effects. Overall, our findings suggest that feature integration theory may be useful for predicting attentional performance in a 3D world.

Proof-of-concept of a neutron time-of-flight ellipsoidal detector

The time-resolved measurement of neutrons emitted from nuclear implosions at inertial confinement fusion facilities is used to characterize the fusing plasma. Several significant quantities are routinely measured by neutron time-of-flight (nToF) detectors in these experiments. Current nToF detectors use scintillators as well as solid-state Cherenkov radiators. The latter has an inherently faster time response and can provide a co-registered γ-ray measurement as well as improved precision in the bulk hot-spot velocity. This work discusses a nToF ellipsoidal detector that also utilizes a solid-state Cherenkov radiator. The detector has the potential to achieve a fast instrument response function allowing for characterization of the γ-ray burn history as well as the ability to field the detector closer to the fusion source. Proof-of-concept testing of the nToF ellipsoidal detector has been conducted at the National Ignition Facility using commercial optics. A time-resolved neutron signal has been measured from the diagnostic. Preliminary simulations corroborate the results.

Late onset recurrence of clinical signs after surgery for intervertebral disc extrusion in French bulldogs

OBJECTIVES

To identify the prevalence of recurrence of clinical signs after initial successful decompressive surgery for intervertebral disc extrusion in French bulldogs.

MATERIALS AND METHODS

A medical record search was performed to identify French bulldogs that experienced an initial successful outcome after surgery for thoracolumbar or cervical intervertebral disc extrusion. Collected information included signalment, neurological examination findings, intervertebral disc extrusion location, presence of vertebral malformations, kyphosis, type and extent of surgery. Decompressive surgery was not followed by extensive prophylactic fenestrations. Follow-up information was retrieved from medical records and telephone interviews with referring veterinary surgeons.

RESULTS

Eighty-four French bulldogs with thoracolumbar (n=55) or cervical (n=29) intervertebral disc extrusion were included. Forty-three (51%) dogs that had decompressive surgery for thoracolumbar (n=29) or cervical (n=14) intervertebral disc extrusion suffered recurrence of signs. The median time between decompressive surgery and recurrence of clinical signs was 9 months and 21 days. Of the 29 dogs suffering recurrence of clinical signs following surgery for thoracolumbar intervertebral disc extrusion, 24 returned for recurrence of clinical signs localised to the thoracolumbar segments, while five returned for recurrence of signs localised to the cervical region. Of the 14 dogs who suffered recurrence of signs following surgery for cervical intervertebral disc extrusion, nine returned for signs localised to the cervical region, while five returned for clinical signs localised to the thoracolumbar region.

CLINICAL SIGNIFICANCE

This study suggests a high rate of late onset recurrence of clinical signs after decompressive surgery for intervertebral disc extrusion in French bulldogs. This information can aid in the management of owner expectations.

Maintenance of statin therapy among people living with HIV

OBJECTIVE

Statins play a critical role in reducing the elevated risk of atherosclerotic cardiovascular disease (ASCVD) among people living with HIV (PLHIV). However, maintaining statin therapy is difficult and may be impeded further in PLHIV due to the risk of antiretroviral therapy (ART)/statin interactions. We estimated rates of statin discontinuation and reinitiation, and the percentage of days covered by statin use among PLHIV on ART, and investigated factors associated with these outcomes.

DESIGN

Observational cohort study.

METHODS

Clinical data from individuals attending the HIV-NAT Centre in Bangkok, Thailand between 2001 and 2020 were analyzed using Kaplan-Meier curves, competing-risk regression, and generalized estimating equations. Discontinuation was defined as statin cessation lasting 90 days.

RESULTS

Data on 318 PLHIV were included. After 1, 3, and 5 years, 22.3, 50.8, and 61.1% had discontinued statin use, respectively. Among those who discontinued (n = 178), 52.0% reinitiated statin use within 5 years. Factors associated with statin discontinuation were low education level, fewer concomitant medications, and lack of ASCVD. Factors associated with statin reinitiation were older age, diabetes, and high levels of LDL cholesterol. The adjusted mean percentage of days covered by a statin was 86.7, 61.1, and 58.1% in the 6 months prior to 1, 3, and 5 years of follow-up, respectively.

CONCLUSION

Maintenance of statin therapy is poor among PLHIV on ART but is not associated with using contraindicated antiretroviral/statin combinations. A better understanding of statin use in PLHIV will aid clinicians treating individuals and policy makers designing interventions for population-level ASCVD risk reduction.

The relation between measures of explicit shame and borderline personality features in adolescent inpatients

BACKGROUND

Shame is a highly negative emotion frequently experienced by individuals with borderline personality disorder (BPD) as well as those with internalizing or externalizing psychopathology. However, few studies have examined whether shame is related to BPD above and beyond other psychopathology. Further, although feelings of shame peak during adolescence, coinciding with the onset of BPD, very few studies have examined the relationship between shame and BPD in adolescence. Therefore, the current study examined (1) whether levels of shame differ between adolescent psychiatric inpatients with and without BPD and (2) whether borderline personality pathology accounts for additional variance in the experience of shame above and beyond internalizing and externalizing psychopathology.

METHODS

Adolescent psychiatric inpatients (n = 184, 67% female, M age = 15.26) completed clinical interviews and self-report measures as well as self-report measures of three types of explicit shame: state-shame, shame-proneness, and trait-shame.

RESULTS

T-tests revealed that adolescents with BPD reported significantly higher levels of each type of explicit shame. In hierarchical regression models, borderline personality features explained significant additional variance in shame-proneness and trait-shame while controlling for age, gender, and internalizing and externalizing psychopathology.

LIMITATIONS

Our sample was limited by a lack of demographic diversity and healthy control group, and the study did not examine relations with unique internalizing/externalizing disorders or features of BPD.

CONCLUSIONS

Our findings contribute to growing evidence that shame is an important component of BPD, particularly during adolescence, and suggest that shame should be addressed in treatment.

The five line-of-sight neutron time-of-flight (nToF) suite on the National Ignition Facility (NIF)

Measurement of the neutron spectrum from inertial confinement fusion implosions is one of the primary diagnostics of implosion performance. Analysis of the spectrum gives access to quantities such as neutron yield, hot-spot velocity, apparent ion temperature, and compressed fuel ρr through measurement of the down-scatter ratio. On the National Ignition Facility, the neutron time-of-flight suite has been upgraded to include five independent, collimated lines of sight, each comprising a high dynamic range bibenzyl/diphenylacetylene-stilbene scintillator [R. Hatarik et al., Plasma Fusion Res. 9, 4404104 (2014)] and high-speed fused silica Cherenkov detectors [A. S. Moore et al., Rev. Sci. Instrum. 89, 10I120 (2018)].

First-dose ChAdOx1 and BNT162b2 COVID-19 vaccines and thrombocytopenic, thromboembolic and hemorrhagic events in Scotland

Reports of ChAdOx1 vaccine-associated thrombocytopenia and vascular adverse events have led to some countries restricting its use. Using a national prospective cohort, we estimated associations between exposure to first-dose ChAdOx1 or BNT162b2 vaccination and hematological and vascular adverse events using a nested incident-matched case-control study and a confirmatory self-controlled case series (SCCS) analysis. An association was found between ChAdOx1 vaccination and idiopathic thrombocytopenic purpura (ITP) (0-27 d after vaccination; adjusted rate ratio (aRR) = 5.77, 95% confidence interval (CI), 2.41-13.83), with an estimated incidence of 1.13 (0.62-1.63) cases per 100,000 doses. An SCCS analysis confirmed that this was unlikely due to bias (RR = 1.98 (1.29-3.02)). There was also an increased risk for arterial thromboembolic events (aRR = 1.22, 1.12-1.34) 0-27 d after vaccination, with an SCCS RR of 0.97 (0.93-1.02). For hemorrhagic events 0-27 d after vaccination, the aRR was 1.48 (1.12-1.96), with an SCCS RR of 0.95 (0.82-1.11). A first dose of ChAdOx1 was found to be associated with small increased risks of ITP, with suggestive evidence of an increased risk of arterial thromboembolic and hemorrhagic events. The attenuation of effect found in the SCCS analysis means that there is the potential for overestimation of the reported results, which might indicate the presence of some residual confounding or confounding by indication. Public health authorities should inform their jurisdictions of these relatively small increased risks associated with ChAdOx1. No positive associations were seen between BNT162b2 and thrombocytopenic, thromboembolic and hemorrhagic events.

Socioeconomic and psychosocial factors are associated with poor treatment outcomes in Australian adults living with HIV: a case-control study

Background A substantial minority of patients living with HIV refuse or cease antiretroviral therapy (ART), have virological failure (VF) or develop an AIDS-defining condition (ADC) or serious non-AIDS event (SNAE). It is not understood which socioeconomic and psychosocial factors may be associated with these poor outcomes.

METHODS

Thirty-nine patients with poor HIV treatment outcomes, defined as those who refused or ceased ART, had VF or were hospitalised with an ADC or SNAE (cases), were compared with 120 controls on suppressive ART. A self-report survey recorded demographics, physical health, life stressors, social supports, HIV disclosure, stigma or discrimination, health care access, treatment adherence, side effects, health and treatment perceptions and financial and employment status. Socioeconomic and psychosocial covariates significant in bivariate analyses were assessed with conditional multivariable logistic regression, adjusted for year of HIV diagnosis.

RESULTS

Cases and controls did not differ significantly with regard to sex (96.2% (n = 153) male) or age (mean (± s.d.) 51 ± 11 years). Twenty cases (51%) had refused or ceased ART, 35 (90%) had an HIV viral load >50 copies mL-1, 12 (31%) were hospitalised with an ADC and five (13%) were hospitalised with a new SNAE. Three covariates were independently associated with poor outcomes: foregoing necessities for financial reasons (adjusted odds ratio (aOR) 3.1, 95% confidence interval (95% CI) 1.3-7.6, P = 0.014), cost barriers to accessing HIV care (aOR 3.1, 95% CI 1.0-9.6, P = 0.049) and lower quality of life (aOR 3.8, 95% CI 1.5-9.7, P = 0.004).

CONCLUSIONS

Despite universal health care, socioeconomic and psychosocial factors are associated with poor HIV outcomes in adults in Australia. These factors should be addressed through targeted interventions to improve long-term successful treatment.

Short Communication: Carotid Intima-Media Thickness Is Not Associated with Neurocognitive Impairment Among People Older than 50 Years With and Without HIV Infection from Thailand

Neurocognitive impairment (NCI) contributes to poor quality of life among HIV-positive individuals. Cardiovascular risk factors, including the predictor of subclinical atherosclerosis, carotid intima-media thickness (cIMT), are reported to be associated with NCI. Data on NCI and its association with cIMT among HIV positive are limited, especially in Asian populations. We aimed to determine the prevalence of NCI and its association with cIMT among HIV-positive and HIV-negative aging Thai individuals. Cognitive performance was evaluated by the Thai version of Montreal Cognitive Assessment (MoCA) with a cutoff of <25/30 for diagnosis of NCI. Depression was evaluated by PHQ-9 Patient Depression Questionnaire, with scores ≥5 indicating depression. cIMT measurement was performed by experienced neurologists, and abnormal cIMT was defined as cIMT ≥0.9 mm or presence of carotid plaques. Among 340 well suppressed and aging HIV-positive and 102 HIV-negative matched participants, the median age (interquartile range) was 55 (52-59) years and 61.5% were males. For HIV positive group, the median duration on antiretroviral therapy was 18.3 years with median CD4 of 615.5 cells/mm³, and 97.4% had current plasma HIV RNA <50 copies/mL. The most common antiretroviral agents used were tenofovir disoproxil fumarate (76.8%), lamivudine (70.3%), efavirenz (26.7%), and emtricitabine (23.8%). HIV-positive and HIV-negative participants performed comparably between each domain and had comparable prevalence of NCI (59.4% vs. 61.7%, p = .69). However, the HIV-positive group had a high prevalence of depression (24.71% vs. 13.73%, p = .019). HIV-positive status [adjusted odd ratio (aOR) 0.91; 95% confidence interval (CI) 0.57-1.47, p = .71] and cIMT (aOR 1.17; 95% CI 0.77-1.79, p = .47) were not significantly associated with NCI. Given the high prevalence of NCI and depression among aging HIV-positive individuals, routine screening for NCI and depression should be integrated into the HIV care services.

Investigating Mechanisms for Maternal Education Disparities in Enacting Health-Promoting Infant Care Practices

BACKGROUND

Although higher education and healthier practices are positively associated, the explanatory mechanisms for this association remain unclear. The purpose of this study was to better understand mechanisms underlying this association by examining maternal adherence to 2 health-promoting infant care practices: supine placement and breastfeeding.

METHODS

We analyzed nationally representative data from the Study of Attitudes and Factors Effecting Infant Care, which surveyed US mothers after infant birth and 2 months thereafter. Using the Theory of Planned Behavior as a framework, we used structural equation models to elucidate mediational pathways from maternal education to supine infant placement or any breastfeeding.

RESULTS

Data from 3297 mothers demonstrated 77.0% of infants usually were placed supine, and 57.8% received any breastfeeding. The overall direct effect of maternal educational level on supine placement and any breastfeeding was odds ratio (OR) 1.31 (95% confidence interval [CI] 1.11-1.54) and OR 2.82 (95% CI 2.35-3.37), respectively. In pathway analyses, the strongest associations with both supine position and breastfeeding were seen with positive attitudes (supine: aOR 18.96, 95% CI 9.00-39.92; breastfeeding: aOR 3.86, 95% CI 2.19-6.82) and positive social norms (supine: aOR 6.69, 95% CI 4.52-9.89; breastfeeding: aOR 5.17, 95% CI 4.28-6.23). Mothers with more education had higher odds of both positive attitudes and positive norms for the 2 practices.

CONCLUSIONS

The associations linking educational attainment with health practices are intricate, with multiple mediating pathways. Attitudes and social norms are powerful forces that mediate the association between maternal educational attainment and both infant supine positioning and breastfeeding, and may be important mediators for other health behaviors.

Prevalence and predictors of donor milk programs among U.S. advanced neonatal care facilities

OBJECTIVE

(1) Determine national prevalence and predictors of donor milk programs among levels 2-4 advanced neonatal care facilities; (2) describe characteristics of donor milk programs.

STUDY DESIGN

We randomly selected 120 U.S. hospitals with levels 2-4 advanced neonatal care facilities among each of four U.S. regions and surveyed the medical directors from July 2017 to November 2017 regarding donor milk use. We weighted responses according to the number of birthing hospitals in each region.

RESULTS

Response rate was 213/480 (44%). Twenty-eight percent of level 2 and 88% of levels 3 and 4 neonatal care facilities had donor milk programs. Donor milk programs occurred more often in the South vs. Northeast (aOR 3.7 [1.1, 12.5] and less often in safety-net hospitals (≥75% Medicaid patients) vs. nonsafety-net hospitals (aOR 0.3 [0.1, 0.8]).

CONCLUSION

In 2017, the vast majority of levels 3 and 4 neonatal care facilities had donor milk programs but disparities existed according to the safety-net hospital status and region.

Level of UV Exposure, Skin Type, and Age Are More Important than Thiopurine Use for Keratinocyte Carcinoma Development in IBD Patients

BACKGROUND

Retrospective studies observe an increased risk of keratinocyte carcinomas (KCs) in patients with inflammatory bowel disease (IBD) on thiopurine (TP) medication. The role of traditional risk factors such as skin type and sun protection behavior has not been studied in this population. This study aimed to examine traditional KC risk factors and thiopurine use on skin cancer development in an IBD cohort.

METHODS

Consecutive IBD patients were recruited from four specialist centers in Australia and New Zealand, each with varying UV exposure indices. Data pertaining to race, skin color, freckling and sun protection behavior, dose of TP therapy, and skin cancer development were elicited through a self-reported questionnaire.

RESULTS

A total of 691 IBD patients were included with 62 reporting KC development. Thiopurine usage was similar among patients who developed skin cancer compared with those who did not (92% vs. 89%, p = 0.3). There was no statistically significant association between KC development and TP dose or 6-thioguanine nucleotide levels. In multivariate modeling, four factors were independently and significantly associated with KC: age over 61 years old versus less than 30 years old (OR 6.76; 95% CI 2.38-19.18), residing in Brisbane versus Christchurch (OR 3.3; 95% CI 1.6-6.8), never staying in the shade versus staying in the shade ≥ 50% of the time (OR 3.8; 95% CI 1.4-10.5), and having a skin type that never tanned versus other skin types (OR 6.9; 95% CI 2.9-16.0).

CONCLUSION

Skin type, age, and sun protection behavior are more important risk factors for KC development than thiopurine medication use in this IBD population.

Production of relativistic electrons at subrelativistic laser intensities

Relativistic electron temperatures were measured from kilojoule, subrelativistic laser-plasma interactions. Experiments show an order of magnitude higher temperatures than expected from a ponderomotive scaling, where temperatures of up to 2.2 MeV were generated using an intensity of 1×10^{18}W/cm^{2}. Two-dimensional particle-in-cell simulations suggest that electrons gain superponderomotive energies by stochastic acceleration as they sample a large area of rapidly changing laser phase. We demonstrate that such high temperatures are possible from subrelativistic intensities by using lasers with long pulse durations and large spatial scales.

348. Kidney Function Decline Among HIV-infected Thai Adults: Is Low Vitamin D One of the Factors?

Background

The prevalence of both hypovitaminosis D and Chronic Kidney disease (CKD) are high among Thai HIV-infected adults. Therefore, we examined the association of hypovitaminosis D and kidney function decline among HIV-infected Thai adults.

Methods

Using data prospectively collected from the HIV-NAT long-term cohort, we selected patients who were on ART, and virologically suppressed for ≥6 months. Baseline was defined as when the patient had a serum 25 OHD measured, with estimated Glomerular filtration rate (eGFR) above 60 mL/minute. Participants with eGFR measured at least twice a year were analyzed in the study. The primary outcome was kidney function impairment assessed as eGFR decline. Generalised estimating equations (GEE) were used to assess associations between the outcome and patient comorbidities and disease-related characteristics, including age, sex, body mass index (BMI) hypertension, gout, diabetes mellitus, co-infections with Hepatitis B or C viruses HIV-viral load and co-variate interactions with vitamin D status defined as normal, insufficient or deficient.

Results

A total of 435 participants were observed longitudinally through observations over the median follow-up of 24 (IOR 12–48) months. The median age of the participants was 46.6 (IOR 38.06–54.29) years. Median serum 25 OHD was 23.4 (IQR 18.5–29) ng/mL, and 209 (48%) and 126(29%) had insufficient and deficient 25 OH levels, respectively. Median baseline eGFR was 95 (IQR 82.70–104.93) mL/minute/l.73 m². We found a significant interaction between BMI and vitamin D concentration (P = 0.02). In our multivariate model, the adjusted mean predictions of eGFR change at 24 months for patients with BMI ≥25 kg/m² and deficient, insufficient and sufficient vitamin D were 89.8 (88.3–91.4), 91.2 (90.1–92.4) and 92.8 (91.3–94.4), respectively. In those with BMI <25 kg/m² and deficient, insufficient and sufficient Vitamin D the adjusted mean predictions in eGFR change were 92.0 (91.1–93.0), 91.6 (90.9–92.3) and 92.3 (91.3–93.3), respectively.

Conclusion

HIV-infected Thai adults with high BMI (25 and above) but who are vitamin D deficient had a statistically significant eGFR decline. Further studies in larger populations with multi-ethnic groups are warranted.

Disclosures

All authors: No reported disclosures.

Metabolic profiles of individuals switched to second-line antiretroviral therapy after failing standard first-line therapy for treatment of HIV-1 infection in a randomized, controlled trial

BACKGROUND

To investigate metabolic changes associated with second-line antiretroviral therapy (ART) following virological failure of first-line ART.

METHODS

SECOND-LINE was an open-label randomized controlled trial. Participants were randomized 1:1 to receive ritonavir-boosted lopinavir (LPV/r) with 2-3 nucleoside/nucleotide reverse transcriptase inhibitors (N[t]RTI group) or raltegravir (RAL group). 210 participants had a dual energy X-ray absorptiometry (DXA)-scan at baseline, week 48 and 96. We categorized participants according to second-line ART backbone: thymidine analogue (ta-NRTI) + lamivudine/emtricitabine (3[F]TC; ta-NRTI group); tenofovir (TDF)+3(F)TC (TDF group); TDF+ta-NRTI ±3(F)TC (TDF+ta-NRTI group); RAL. Changes in fasted total cholesterol (TC), low-density lipoprotein (LDL)-cholesterol, high-density lipoprotein (HDL)-cholesterol, TC/HDL-cholesterol ratio, triglycerides and glucose from baseline to week 96 were examined. We explored the association between metabolic and DXA-assessed soft-tissue changes. Linear regression methods were used.

RESULTS

We analysed 454 participants. Participants in RAL group had greater TC increases, TC (adjusted mean difference [aMD]=0.65, 95% CI 0.33, 0.96), LDL-c (aMD=0.38, 95% CI 0.15, 0.61) and glucose (aMD=0.47, 95% CI -0.01, 0.92) compared to TDF group, and had greater increases in TC (aMD=0.65, 95% CI 0.28, 1.03), HDL-c (aMD=0.12, 95% CI 0.02, 0.23) and LDL-c (aMD=0.41, 95% CI 0.13, 0.69) compared to TDF+ta-NRTI group. TC/HDL ratio and triglycerides increased in all groups without significant differences between groups. A 1 kg increase in trunk fat mass was associated with an increase in TC.

CONCLUSIONS

We observed metabolic changes of limited clinical significance in the relatively young population enrolled in this study. However, the metabolic changes observed may have greater clinical significance in older people living with HIV or those with other concomitant cardiovascular risks.

Antiretroviral-naïve HIV-infected patients had lower bone formation markers than HIV-uninfected adults

There are limited studies regarding bone health among people living with HIV (PLHIV) in Asia. We compared bone mineral density (BMD), serum 25-hydroxyvitamin D (25(OH)D) status and bone turnover markers (serum procollagen type1 N-terminal propeptide (P1NP), osteocalcin (OC) and C-terminal cross-linking telopeptide of type1 collagen) among 302 antiretroviral therapy (ART) naive PLHIV compared to 269 HIV-uninfected controls from Thailand. People aged ≥30 years, with and without HIV infection (free of diabetes, hypertension, and active opportunistic infection) were enrolled. BMD at the lumbar spine, total hip, and femoral neck were measured using Hologic DXA at baseline and at 5 years. We analyzed BMD, serum 25(OH)D levels, and bone turnover markers at the patients' baseline visit. PLHIV were 1.5 years younger and had lower BMI. PLHIV had higher mean serum 25(OH)D level and similar BMD to the controls. Interestingly, PLHIV had significantly lower bone formation (serum P1NP and OC), particularly those with low CD4 count. Only a few participants had low bone mass. ARV naïve middle-aged PLHIV did not have lower BMD or lower vitamin D levels compared to the controls. However, PLHIV had lower bone formation markers, particularly those with low CD4 count. This finding supports the benefit of early ART.

Mediators of Improved Adherence to Infant Safe Sleep Using a Mobile Health Intervention

OBJECTIVES

To determine mediators of improvements in infant safe-sleep (SS) practices in a mobile health intervention.

METHODS

In a cluster-randomized controlled trial, mothers received SS intervention or breastfeeding control videos for 60 days. Maternal responses about infant sleep position and location (outcomes) and mediators (attitudes, perceived social norms, and perceived control) from the theory of planned behavior were assessed. Intervention effects on mediators and association between mediators and outcomes were examined.

RESULTS

Of 1600 recruited, 1263 mothers participated. Mothers receiving SS videos were more likely to have positive attitudes and norms for supine sleep (attitudes: adjusted odds ratio [aOR] = 2.35 [95% confidence interval (CI) 1.72 to 3.20]; norms: aOR = 1.75 [95% CI 1.27 to 2.42]) and recommended sleep location (attitudes: aOR = 1.91 [95% CI 1.54 to 2.36]; norms: aOR = 1.37 [95% CI 1.13 to 1.66]). Positive attitudes and norms toward supine sleep and room-sharing without bed-sharing were associated with higher odds of both practices (supine: aOR = 8.25 [95% CI 4.72 to 14.43] for positive attitudes and aOR = 6.67 [95% CI 4.25 to 10.46] for norms; room-sharing: aOR = 7.14 [95% CI 5.35 to 9.53] for positive attitudes and aOR = 4.44 [95% CI 3.03 to 6.51] for norms). Both positive attitudes and positive norms mediated the effect of the intervention.

CONCLUSIONS

The intervention achieved success in improving adherence to SS recommendations by changing maternal attitudes and norms about supine sleeping and room-sharing without bed-sharing. Recognition that these attitudes and norms appear to be the main drivers of mothers' choices regarding infant-sleep practices should inform health messaging strategies to promote SS.