The Impact of Social Determinants of Health on the Treatment of Distal Radius Fracture

BACKGROUND

Disparities in social determinants of health (SDH) have been shown to play an increasingly important role in the equitable delivery of health care. Distal radius fractures (DRFs) are among the most common upper-extremity injuries encountered. This study aims to examine the influence of economic, educational, social, environmental, and healthcare disparities on management of these injuries.

METHODS

PearlDiver Mariner insurance claims database was analyzed for treatment patterns of DRF in patients aged 18 to 65 years based on the presence or absence of social determinants of health disparities (SDHDs). Outcome variables included the primary mode of management of DRF, including operative versus non-operative, as well as concomitant procedures. Multivariate logistic regression was used to compare fracture management modality in patients with and without SDHDs.

RESULTS

Of 161 704 patients identified with DRF, 38.3% had at least 1 reported SDHD. The majority of SDHDs were economic. Patients identified with 1 or more SDHDs had a higher medical comorbidity index. Patients with environmental SDHD were more likely to receive non-operative management. Within any SDHD and economic subgroups, odds of operative management were higher. No relationship was identified between SDHD and concomitant procedures.

CONCLUSIONS

The presence of environmental disparities in SDH may predispose patients disproportionately to non-operative management. The presence of SDHDs may influence medical decision-making in favor of open reduction and internal fixation in patients with DRF treated operatively. In treating at-risk populations, providers should be aware of the potential for implicit bias associated with SDHDs and prioritize shared decision-making between patients and physicians.

Nanoscale Rheology: Dynamic Mechanical Analysis over a Broad and Continuous Frequency Range Using Photothermal Actuation Atomic Force Microscopy

Polymeric materials are widely used in industries ranging from automotive to biomedical. Their mechanical properties play a crucial role in their application and function and arise from the nanoscale structures and interactions of their constitutive polymer molecules. Polymeric materials behave viscoelastically, i.e., their mechanical responses depend on the time scale of the measurements; quantifying these time-dependent rheological properties at the nanoscale is relevant to develop, for example, accurate models and simulations of those materials, which are needed for advanced industrial applications. In this paper, an atomic force microscopy (AFM) method based on the photothermal actuation of an AFM cantilever is developed to quantify the nanoscale loss tangent, storage modulus, and loss modulus of polymeric materials. The method is then validated on styrene-butadiene rubber (SBR), demonstrating the method's ability to quantify nanoscale viscoelasticity over a continuous frequency range up to 5 orders of magnitude (0.2-20,200 Hz). Furthermore, this method is combined with AFM viscoelastic mapping obtained with amplitude modulation-frequency modulation (AM-FM) AFM, enabling the extension of viscoelastic quantification over an even broader frequency range and demonstrating that the novel technique synergizes with preexisting AFM techniques for quantitative measurement of viscoelastic properties. The method presented here introduces a way to characterize the viscoelasticity of polymeric materials and soft and biological matter in general at the nanoscale for any application.

Development and validation of a diagnostic aid for convulsive epilepsy in sub-Saharan Africa: a retrospective case-control study

BACKGROUND

Identification of convulsive epilepsy in sub-Saharan Africa relies on access to resources that are often unavailable. Infrastructure and resource requirements can further complicate case verification. Using machine-learning techniques, we have developed and tested a region-specific questionnaire panel and predictive model to identify people who have had a convulsive seizure. These findings have been implemented into a free app for health-care workers in Kenya, Uganda, Ghana, Tanzania, and South Africa.

METHODS

In this retrospective case-control study, we used data from the Studies of the Epidemiology of Epilepsy in Demographic Sites in Kenya, Uganda, Ghana, Tanzania, and South Africa. We randomly split these individuals using a 7:3 ratio into a training dataset and a validation dataset. We used information gain and correlation-based feature selection to identify eight binary features to predict convulsive seizures. We then assessed several machine-learning algorithms to create a multivariate prediction model. We validated the best-performing model with the internal dataset and a prospectively collected external-validation dataset. We additionally evaluated a leave-one-site-out model (LOSO), in which the model was trained on data from all sites except one that, in turn, formed the validation dataset. We used these features to develop a questionnaire-based predictive panel that we implemented into a multilingual app (the Epilepsy Diagnostic Companion) for health-care workers in each geographical region.

FINDINGS

We analysed epilepsy-specific data from 4097 people, of whom 1985 (48·5%) had convulsive epilepsy, and 2112 were controls. From 170 clinical variables, we initially identified 20 candidate predictor features. Eight features were removed, six because of negligible information gain and two following review by a panel of qualified neurologists. Correlation-based feature selection identified eight variables that demonstrated predictive value; all were associated with an increased risk of an epileptic convulsion except one. The logistic regression, support vector, and naive Bayes models performed similarly, outperforming the decision-tree model. We chose the logistic regression model for its interpretability and implementability. The area under the receiver operator curve (AUC) was 0·92 (95% CI 0·91-0·94, sensitivity 85·0%, specificity 93·7%) in the internal-validation dataset and 0·95 (0·92-0·98, sensitivity 97·5%, specificity 82·4%) in the external-validation dataset. Similar results were observed for the LOSO model (AUC 0·94, 0·93-0·96, sensitivity 88·2%, specificity 95·3%).

INTERPRETATION

On the basis of these findings, we developed the Epilepsy Diagnostic Companion as a predictive model and app offering a validated culture-specific and region-specific solution to confirm the diagnosis of a convulsive epileptic seizure in people with suspected epilepsy. The questionnaire panel is simple and accessible for health-care workers without specialist knowledge to administer. This tool can be iteratively updated and could lead to earlier, more accurate diagnosis of seizures and improve care for people with epilepsy.

FUNDING

The Wellcome Trust, the UK National Institute of Health Research, and the Oxford NIHR Biomedical Research Centre.

Trends in Physician Payments for Hand Surgery Consultations and Clinic Visits

PURPOSE

The primary objective of this study was to identify the trends in reimbursement for hand surgeons for new patient visits, outpatient consultations, and inpatient consultations from the years 2010-2018. In addition, we sought to investigate the influence of payer mix and coding level of service on physician reimbursement in these settings.

METHODS

The PearlDiver Patients Records Database was used to identify clinical encounters and their respective physician reimbursements for analysis within this study. This database was queried using Current Procedural Terminology codes to identify relevant clinical encounters for inclusion, filtered for the presence of valid demographic information and by physician specialty for the presence of a hand surgeon, and tracked by primary diagnoses. Cost data were then calculated and analyzed regarding the payer type and level of care.

RESULTS

In total, 156,863 patients were included in this study. The mean reimbursement for inpatient consultations, outpatient consultations, and new patient encounters increased by 92.75% ($134.85 to $259.93), 17.80% ($161.33 to $190.04), and 26.78% ($102.58 to $130.05), respectively. When normalized to 2018 dollars to adjust for inflation, the percent increases were 67.38%, 2.24%, and 10.09%, respectively. Commercial insurance reimbursed hand surgeons to a greater degree than any other payer type. Mean physician reimbursement differed depending on the level of service billed, with the level of service V reimbursing 4.41 times more than the level of service I visits for new outpatient visits, 3.66 times more for new outpatient consultations, and 3.04 times more for new inpatient consultations.

CONCLUSIONS

This study helps to provide physicians, hospitals, and policymakers with objective information regarding the trends in reimbursement to hand surgeons. Although this study indicates increasing reimbursements for consultations and new patient visits to hand surgeons, the margins shrink when adjusted for inflation.

LEVEL OF EVIDENCE

Economic Analysis IV.

Very cold and ultra cold neutron sources for ESS

The goal of the “Workshop on Very Cold and Ultra Cold Neutron Sources for ESS” was to discuss scientific cases, ideas and possibilities for the implementation of sources of Very Cold and Ultra Cold neutrons at the European Spallation Source. The ESS facility, presently under construction, offers several possibilities for in-pile UCN or VCN sources, in primis thanks to the available space below the spallation target where additional neutron sources can be placed to complement those above the target. Neutron beams can be extracted over a wide angular range with a grid of forty-two beamports with 6° average angular separation, allowing future instruments to be installed which may view either the upper or lower moderator systems. Of greatest interest for fundamental physics is the so-called Large Beamport foreseen for the NNBAR experiment. This beamport is also particularly well suited to feed a UCN source, for which several ideas were presented that employ either superfluid helium or solid deuterium as established neutron converter materials. Concepts for VCN sources make use of novel materials for VCN production and/or advanced reflectors to increase yields in the coldest part of the neutron spectrum from a cryogenic neutron source. In this paper we discuss these ideas and the possible locations of UCN and VCN sources at ESS.

Significant improvement in blood pressure control among older adults with hypertension in rural South Africa: findings from a prospective 5,000-patient cohort, 2014–2019

Background

Sub-Saharan Africa is undergoing an epidemiologic transition dominated by a widespread epidemic of hypertension (HTN). Since 2014, we began studying a cohort of 5,059 individuals in rural South Africa, to describe the evolution of HTN among older adults, and understand the impact of targeted interventions by local health systems.

Purpose

Characterize the updated prevalence and incidence of HTN in a prospective cohort between baseline (2014) and follow-up (2019), and describe changes in blood pressure (BP) treatment.

Methods

HTN was defined as systolic blood pressure (SBP) ≥140 mm Hg, diastolic blood pressure (DBP) ≥90 mm Hg, or self-reported medication use. Prevalence and incidence rates were calculated using inverse-probability weights to account for mortality and attrition. Poisson regression was used to identify predictors of disease incidence. We calculated the percentage of individuals with controlled versus uncontrolled HTN (with 140/90 mm Hg as cutoff), self-reported medication use, and compared these values between 2014 and 2019.

Results

Compared to 2014 (n=5,059), study participants in 2019 (n=4,176) were expectedly older (mean age 61.7±13.1 vs 66.0±13.0 years) but had similar sex distribution (53.6% vs 53.5% females) and weighted rates of obesity (mean BMI 27.5±10.0 vs 27.0±6.5), with higher rates of smoking (9.1% vs 11.8%) and diabetes (11.1% vs 13.7%). The HTN prevalence did not increase over time (58.4% vs 59.8%), and there was a significant reduction in mean SBP (138.0 vs 128.5 mm Hg, p<0.001) and DBP (82.1 vs 79.6 mm Hg, p<0.001). In the subgroup of hypertensive individuals with measured BP and self-reported medication use in both 2014 and 2019 (n=796), the percentage who had controlled HTN on medications increased from 44.5% to 62.3% while the percentage who had uncontrolled HTN on medications or uncontrolled HTN not on medications decreased (48.5% to 32.2% and 7.2% to 3%, respectively) from 2014 to 2019 (Figure 1). The HTN incidence was 6.2 per 100 person-years, which was lower than prior reports from this area (8.4 per 100 person-years in 2010–2015); in multivariable models, age was the only significant predictor of incident HTN. In the subgroup of individuals who were healthy at baseline with measured BP and self-reported medication use in 2014 and 2019 (n=2,257), very few developed HTN by 2019 (15.2%); of those, the majority already had controlled HTN and was on medications by 2019 (Figure 2).

Conclusions

The prevalence of HTN did not increase in this aging cohort; in fact there was a clinically and statistically significant decline in mean BP and a substantial increase in the proportion of hypertensive patients with controlled HTN taking medications between 2014 and 2019. The prevalence of obesity, smoking and other risk factors did not decrease over time, suggesting that the mean BP decrease in this cohort is likely due to increased access and adherence to medications, promoted by local health systems.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Institute on Aging (P01 AG041710), and Department of Science and Innovation, the University of the Witwatersrand, South Africa.

A community mobilisation intervention to improve engagement in HIV testing, linkage to care, and retention in care in South Africa: a cluster-randomised controlled trial

BACKGROUND

Community mobilisation, engaging communities in a process to collectively enact change, could improve HIV testing and care engagement. In South Africa, current rates fall below those needed for epidemic control. We assessed whether community mobilisation increased HIV testing, linkage to care, and retention in care over time in intervention relative to control communities.

METHODS

We conducted a cluster-randomised controlled trial in villages in the Agincourt sub-district of the rural Mpumalanga Province in South Africa. 15 villages were randomly assigned to either a community mobilisation intervention engaging residents to address social barriers to HIV testing and treatment (intervention arm) or to a control arm using balanced randomisation. Villages were eligible if they had been fully enumerated in 2014, had not been included in previous mobilisation activities, and included over 500 permanent adult residents aged 18-49 years. Primary outcomes included quarterly rates of HIV testing, linkage to care, and retention in care documented from health facility records among residents of the intervention and control communities over the 3-year study period. Intention-to-treat analyses employed generalised estimating equations stratified by sex. This trial is registered with ClinicalTrials.gov, NCT02197793.

FINDINGS

Between Aug 1, 2015, and July 31, 2018, residents in eight intervention communities (n=20 544 residents) and seven control communities (n=17 848) contributed data; 92 residents contributed to both arms. Among men, HIV testing increased quarterly by 12·1% (relative change [RC] 1·121, 95% CI 1·099 to 1·143, p<0·0001) in the intervention communities and 9·5% (1·095, 1·075 to 1·114, p=0·011) in the control communities; although increases in testing were greater in the intervention villages, differences did not reach significance (exponentiated interaction coefficient 1·024, 95% CI 0·997 to 1·052, p=0·078). Among women, HIV testing increased quarterly by 10·6% (RC 1·106, 95% CI 1·097 to 1·114, p<0·0001) in the intervention communities and 9·3% (1·093, 1·084 to 1·102, p=0·053) in the control communities; increases were greater in intervention communities (exponentiated interaction coefficient 1·012, 95% CI 1·001 to 1·023, p=0·043). Quarterly linkage increased significantly among women in the intervention communities (RC 1·013, 95% CI 1·002 to 1·023, p=0·018) only. Quarterly linkage fell among men in both arms, but decreased significantly among men in the control communities (0·977, 0·954 to 1·002, p=0·043). Quarterly retention fell among women in both arms; however, reductions were tempered among women in the intervention communities (exponentiated interaction coefficient 1·003, 95% CI <1·000 to 1·006, p=0·062). Retention fell significantly among men in both arms with difference in rates of decline.

INTERPRETATION

Community mobilisation was associated with modest improvements in select trial outcomes. The sum of these incremental, quarterly improvements achieved by addressing social barriers to HIV care engagement can impact epidemic control. However, achieving optimal impacts will probably require integrated efforts addressing both social barriers through community mobilisation and provision of improved service delivery.

FUNDING

US National Institutes of Health, National Institute of Mental Health, and United States President's Emergency Plan for AIDS Relief through Right to Care and Project SOAR.

A-19 Distress Predicts Poorer Cognitive Performance At Post-Injury In Concussed Athletes

Purpose: This study evaluated the consistency between athletes’ self-reported cognitive symptoms and cognitive test performance. Methods: The sample included 784 Canadian Football League athletes who underwent standardized cognitive testing with cognitive testing (ImPACT) and the Brief Symptom Inventory (BSI-18) at baseline. Over 2 consecutive seasons, 46 players were diagnosed with concussions following assessment with team physicians within 48 hours; 10 were eliminated due to missing data. Five cognitive symptoms (feeling slowed down, feeling in a fog, not feeling right, difficulties concentration, difficulties with memory) were used to create a composite score (Cog). The Cog index, the depression, anxiety, total index scores from the BSI, and the 5 ImPACT cognitive domains were correlated at baseline and post-injury. History of learning disabilities, ADHD, psychiatric diagnosis, and history of concussion were co-variates. Results: There were no significant correlations between Cog, depression, anxiety or total BSI scores and the ImPACT cognitive domains at baseline. At post injury there were no significant correlations between Cog or ImPACT index scores. In contrast, significant negative correlations were found between BSI Anxiety and verbal memory (r = 0.67, p &lt; 0.01), visual memory (r = 0.68, p &lt; 0.01), and visual-motor processing speed (r = 0.48, p &lt; 0.05). In addition, there were significant negative correlations between the BSI total score and visual memory (r = 0.51, p &lt; 0.05) and reaction time (r = 0.55, p &lt; 0.05). Conclusions: Self-reported cognitive difficulties do not correlate with poorer cognitive outcomes in our sample of professional football players. However, distress at post-injury was significantly correlated to performance, suggesting psychological variables may play a role in cognitive functioning.

A-37 Ocular Motor Impairments in Concussion Professional Football Players

Purpose: The purpose of this study was to examine baseline and post-concussion injury characteristics of ocular eye movements using the Sync Think visual eye tracking apparatus in professional football players in the Canadian Football League (CFL). Methods: The visual tracking testing protocol uses an integrated stimulus presentation-eye tracking apparatus (EyeLink CL; SR Research, Ontario, Canada) with which eye movements were recorded at 500 Hz using infrared video-oculography. The standard deviation of radial errors (SDRE) and tangential errors (SDTE) were used to determine poor visual tracking. Participants were (n = 748) rostered players in the Canadian Football League. All participants completed assessments at baseline. Sixteen players completed post-concussion assessments and 98 players completed post-exertional assessments during the 2021 season to evaluate the impact of physical exertion on ocular movement metrics. Results: Participants with diagnosed concussions (n = 16+) demonstrated significantly poorer performance on measures of both gaze stability and smooth pursuit (p &lt; 0.001). The poorer results were correlated with significantly higher subjective ratings of dizziness (p &lt; 0.01) and fogginess (p &lt; 0.001). In contrast, healthy participants who completed the same ocular motor assessments demonstrated no significant differences compared to baseline test performance. Conclusions: Findings suggest that subtle differences in oculomotor functioning arise from sport concussion in professional football players. Further research with larger sample sizes and correlation with other cognitive and physical outcomes is warranted.

A-12 Mental Health Outcomes for CFL Athletes with ADHD

Purpose: Current research suggests that athletes with Attention Deficit Hyperactivity Disorder (ADHD) are at risk for poorer outcomes arising from sport related concussions (SRC). There is limited research related evaluating mental health outcomes in athletes diagnosed with ADHD. The purpose of the study is to evaluate mental health outcomes among Canadian Football League (CFL) athletes with (ADHD) and to measure outcomes based upon a history of concussion. Methods: Professional football players from the CFL (n = 784) were administered a baseline mental health measure, the Health-Related Quality of Life (HRQL), as a component of pre-season evaluations as part of a larger cohort study (Active Rehabilitation). Diagnosis of ADHD was the independent variable and HRQL index scores measuring physical functioning, depression, cognitive functioning, were dependent variables. A second analysis compared ADHD athletes with no history of concussion to those with a history of concussion on the HRQL indexes. Results: Participants diagnosed with ADHD (n = 80) had statistically significant differences on the Physical Functioning (t(782) = −3.359, p &lt; 0.001), Depression ((t(782) = −2.820, p = 0.002) and Cognitive (t(782) = −3.570, p &lt; 0.001) domains of the HRQL, compared to athletes without ADHD. Among the athletes who are diagnosed with ADHD, no mental health differences were found between those who have at least one concussion and those who do not. Conclusions: This study did not find a significant effect of concussion on mental health outcomes in participants with ADHD. However, athletes with ADHD present with higher mental health symptoms which may merit closer monitoring.

O-285 Artificial intelligence algorithms reach expert-level accuracy in automated grading of blastocyst morphology assessment based on static embryo images and Gardner criteria

Study question

Can artificial intelligence (AI) algorithms reach expert-level accuracy in blastocyst morphology assessment according to Gardner criteria?

Summary answer

The prediction accuracy of the best performing AI algorithm (Deit), outperformed human-level mean accuracies compared to an embryologist majority vote for all Gardner morphological criteria.

What is known already

Routinely, morphological grading of blastocysts is performed visually according to Gardner criteria, which suggest expansion (EXP), quality of inner cell mass (ICM), and trophectoderm (TE) as key parameters to predict treatment outcome. Consequently, blastocyst scoring is prone to inter-and intra-observer variability, which may lead to inconsistencies in selecting blastocysts for transfer. AI-based algorithms may help to improve treatment outcome predictability, as it has been suggested recently. In those studies, parameters such as blastocyst quality or stage were annotated by experts from static or time-lapse-derived blastocyst images, to train AI algorithms, e.g. XCeption or YOLO, and compare them to human annotators.

Study design, size, duration

This retrospective study involves 2,270 images from 837 patients collected over a period of four years in a university IVF clinic.

Participants/materials, setting, methods

All images were annotated by one senior embryologist and divided into a training and a balanced test set. Subsequently, eight embryologists labeled 300 test set images such that every single image was seen by at least four embryologists. Annotators diverging from the ensemble vote for more than one standard deviation were excluded (n = 2) to set the ground truth labels. Finally, three AI architectures (XCeption, Swin, Deit) were trained and evaluated on that particular ground truth.

Main results and the role of chance

Out of nine annotators, labelling accuracy of two embryologists diverged from the consensus vote for more than one standard deviation for at least one of the three Gardner criteria. The consensus vote was built from the remaining seven annotators (mean accuracy EXP 0.81, ICM 0.70, TE 0.67). The Swin architecture outperformed the mean expert accuracy for all three criteria (EXP 0.82, ICM 0.76, TE 0.68), while the Deit and the XCeption architecture outperformed the mean expert accuracy in ICM accuracy (Deit 0.72, XCeption 0.73), and performed equal or worse in EXP and TE accuracy (Deit EXP 0.77, ICM 0.73; XCeption EXP 0.77, TE 0.66). When compared to a recent study conducted on time-lapse imaging data using AI algorithms, all our models outperform the ICM accuracy and achieve comparable TE accuracy. To minimize the role of chance in calculating the models' prediction accuracies, the SWA-Gaussian (SWAG) algorithm was used. SWAG is a method to reflect and calibrate uncertainty representation in Bayesian deep learning. It is based on modelling a Gaussian distribution for each networks' weight and applying it as a posterior over all neural network weights to perform Bayesian model averaging.

Limitations, reasons for caution

To reflect a real IVF lab scenario, embryologists of different origins and levels of experience were involved and no scoring training was offered to the participants. These facts could have potentially negatively affected the degree of consensus, although we excluded two annotators diverging from the mean labeling accuracy.

Wider implications of the findings

In the past, AI algorithms proved to reliably differentiate between good and bad prognosis blastocysts but not necessarily between blastocysts of similar quality. Further AI-supported differentiation on the basis of expansion and cell lineages will facilitate the ranking of blastocysts and would bring automated scoring closer to clinical application.

Trial registration number

Not applicable.

Differences in Corticosterone Release Rates of Larval Spring Salamanders (Gyrinophilus porphyriticus) in Response to Native Fish Presence

Simple Summary

In amphibians, glucocorticoid hormones play a key role in the response to predation stress. Predators can directly affect prey via injury and death, but they can also have indirect effects due to the activity of glucocorticoids. The regulation of glucocorticoids can differ between populations that have co-evolved with predators and those that have not. We measured glucocorticoids at baseline and in response to a novel stressor in free-living larval salamanders that either live with or without fish predators naturally. We found that salamanders living with fish predators had lower measures of glucocorticoids than those without fish predators. Our study indicates that predator presence alters glucocorticoid regulation, which may allow species to better cope with native and introduced predators.

Abstract

Invasive fish predators are an important factor causing amphibian declines and may have direct and indirect effects on amphibian survival. For example, early non-lethal exposure to these stressors may reduce survival in later life stages, especially in biphasic species. In amphibians, the glucocorticoid hormone corticosterone is released by the hypothalamo–pituitary–interrenal axis (HPI), as an adaptive physiological response to environmental stressors. The corticosterone response (baseline and response to acute stressors) is highly flexible and context dependent, and this variation can allow individuals to alter their phenotype and behavior with environmental changes, ultimately increasing survival. We sampled larvae of the spring salamander (Gyrinophilus porphyriticus) from two streams that each contained predatory brook trout (Slavelinus fontinalis) in the lower reaches and no predatory brook trout in the upper reaches. We measured baseline and stress-induced corticosterone release rates of larvae from the lower and upper reaches using a non-invasive water-borne hormone assay. We hypothesized that corticosterone release rates would differ between larvae from fish-present reaches and larvae from fish-free reaches. We found that baseline and stressor-induced corticosterone release rates were downregulated in larvae from reaches with fish predators. These results indicate that individuals from reaches with predatory trout are responding to fish predators by downregulating corticosterone while maintaining an active HPI axis. This may allow larvae more time to grow before metamorphosing, while also allowing them to physiologically respond to novel stressors. However, prolonged downregulation of corticosterone release rates can impact growth in post-metamorphic individuals.

Investigating charge-up and fragmentation dynamics of oxygen molecules after interaction with strong X-ray free-electron laser pulses

The X-ray-induced charge-up and fragmentation process of a small molecule is examined in great detail by measuring the molecular-frame photoelectron interference pattern in conjunction with other observables in coincidence.

Cantilever signature of tip detachment during contact resonance AFM

Contact resonance atomic force microscopy, piezoresponse force microscopy, and electrochemical strain microscopy are atomic force microscopy modes in which the cantilever is held in contact with the sample at a constant average force while monitoring the cantilever motion under the influence of a small, superimposed vibrational signal. Though these modes depend on permanent contact, there is a lack of detailed analysis on how the cantilever motion evolves when this essential condition is violated. This is not an uncommon occurrence since higher operating amplitudes tend to yield better signal-to-noise ratio, so users may inadvertently reduce their experimental accuracy by inducing tip-sample detachment in an effort to improve their measurements. We shed light on this issue by deliberately pushing both our experimental equipment and numerical simulations to the point of tip-sample detachment to explore cantilever dynamics during a useful and observable threshold feature in the measured response. Numerical simulations of the analytical model allow for extended insight into cantilever dynamics such as full-length deflection and slope behavior, which can be challenging or unobtainable in a standard equipment configuration. With such tools, we are able to determine the cantilever motion during detachment and connect the qualitative and quantitative behavior to experimental features.

[Cortisol concentrations in sheep before, during and after sham foot trimming on a tilt table - the suitability of different matrices]

INTRODUCTION

Matrices that can be collected non-invasively for quantification of a stress response in sheep have received little attention in the veterinary literature. This study examines the suitability of blood, tears and saliva for determining a stress response in sheep undergoing sham foot trimming on a tilt table. The cortisol concentration of blood, tears and saliva and the concentration of cortisol metabolites in faeces were measured in 13 healthy Meat Merino ewes once a day for six days. Sham foot trimming on a tilt table was used as the stressor and was done during a one-hour period on day 4; cortisol concentrations of blood and tears were measured at 0, 10, 20, 30, 40 and 60 minutes. Cortisol concentrations of blood (maximum at 30 minutes) and tears (maximum at 40 minutes) increased during the procedure and then decreased. There were significant correlations between cortisol concentrations of blood and tears (p = 0,04) during sham foot trimming (area under the curve, 0 to 60 minutes). Over the entire 6-day study period, significant correlations were seen between the cortisol concentrations of blood and tears (r = 0,55; p.

Echocardiographic and Electrocardiographic Abnormalities Among Elderly Adults With Cardiovascular Disease in Rural South Africa

BACKGROUND

Sub-Saharan Africa is undergoing an epidemiological transition fueled by the interaction between infectious and cardiovascular diseases. Our cross-sectional study aimed to characterize the spectrum of abnormalities suggesting end-organ damage on ECG and transthoracic echocardiograms (TTE) among older adults with cardiovascular diseases in rural South Africa.

METHODS

The prevalence of ECG and TTE abnormalities was estimated; χ2 analyses and multivariable logistic regressions were performed to test their association with sex, hypertension, and other selected comorbidities.

RESULTS

Overall, 729 ECGs and 155 TTEs were completed, with 74 participants completing both. ECG evaluation showed high rates of left ventricular hypertrophy (LVH, 36.5%) and T wave abnormalities (13.6%). TTE evaluation showed high rates of concentric LVH (31.6%), with moderate-severe (56.8%) diastolic dysfunction. Participants with hypertension showed more cardiac remodeling on ECG by LVH (45.4% versus 22.1%, P<0.01), and TTE by concentric LVH (42.5% versus 8.2%, P<0.01) and increased left ventricular mass (58.5% versus 20.4%, P<0.0001). In multivariable logistic regression, systolic blood pressure remained significantly associated with LVH on ECG (adjusted odds ratio, 1.03 per mm Hg [95% CI, 1.03-1.04], P<0.0001) and increased left ventricular mass on TTE (adjusted odds ratio, 1.04 per mm Hg [95% CI, 1.01-1.06], P=0.001). Male participants (n=326, 40.2%) were more likely than females (n=484, 59.8%) to show ECG abnormalities like LVH (45% versus 30.8%, P<0.01), whereas females were more likely to show TTE abnormalities like concentric LVH (40.8% versus 13.5%, P<0.01) and increased left ventricular mass (58.4% versus 23.1%, P<0.0001). Similar results were confirmed in multivariable models.

CONCLUSIONS

Our findings suggest that cardiovascular diseases are widespread in rural South Africa, with a larger burden of hypertensive heart disease than previously appreciated, and define the severity of end-organ damage that is already underway. Local health systems must adapt to face the growing burden of hypertension, as suboptimal rates of hypertension diagnosis and treatment may dramatically increase the heart failure burden.

Mental health and well-being of older adults living with HIV in sub-Saharan Africa: a systematic review

OBJECTIVE

In this systematic review, we aimed to summarise the empirical evidence on common mental disorders (CMDs), cognitive impairment, frailty and health-related quality of life (HRQoL) among people living with HIV aged ≥50 years (PLWH50 +) residing in sub-Saharan Africa (SSA). Specifically, we document the prevalence and correlates of these outcomes.

DESIGN, DATA SOURCES AND ELIGIBILITY CRITERIA

The following online databases were systematically searched: PubMed, CINAHL, PsycINFO, Embase and Scopus up to January 2021. English-language publications on depression, anxiety, cognitive function, frailty and quality of life among PLWH50+ residing in SSA were included.

DATA EXTRACTION AND SYNTHESIS

We extracted information, including study characteristics and main findings. These were tabulated, and a narrative synthesis approach was adopted, given the substantial heterogeneity among included studies.

RESULTS

A total of 50 studies from fifteen SSA countries met the inclusion criteria. About two-thirds of these studies emanated from Ethiopia, Uganda and South Africa. Studies regarding depression predominated (n=26), followed by cognitive impairment (n=13). Overall, PLWH50+ exhibited varying prevalence of depression (6%-59%), cognitive impairments (4%-61%) and frailty (3%-15%). The correlates of CMDs, cognitive impairment, frailty and HRQoL were rarely investigated, but those reported were sociodemographic variables, many of which were inconsistent.

CONCLUSIONS

This review documented an increasing number of published studies on HIV and ageing from SSA. However, the current evidence on the mental and well-being outcomes in PLWH50+ is inadequate to characterise the public health dimension of these impairments in SSA, because of heterogeneous findings, few well-designed studies and substantial methodological limitations in many of the available studies. Future work should have sufficiently large samples of PLWH50+, engage appropriate comparison groups, harmonise the measurement of these outcomes using a standardised methodology to generate more robust prevalence estimates and confirm predictors.

PROSPERO REGISTRATION NUMBER

CRD42020145791.

Fractionation of carbohydrates and proteins and in vitro rumen kinetics of corn silage under various storage durations

The experiment evaluated the effects on the chemical composition (fermentation, kinetic parameters, and protein and carbohydrate fractions) of corn silage after various storage durations (45, 90, 180, and 360 days). Experimental mini silos of the corn plants were made and opened after various storage periods. The experimental design was completely randomized with four treatments and four replications per treatment. Variables such as pH, lactic acid and acetic acid showed a quadratic effect, whereas effluent and gas losses increased linearly with prolonged storage. Proteolysis was observed with an increase in storage, resulting in a rise in ammonia-N, soluble N, and non-protein N concentration and reduction in true protein. The soluble carbohydrate fractions were reduced, and digestible and indigestible fibre were increased. For the kinetic degradation parameters of the silages obtained through in vitro gas methodology, the highest fermentation rate occurred in the first 12 hours of incubation, and the highest volume of gas produced within 96 hours was obtained for silages with shorter storage (45 days). The increase in storage resulted in greater losses and lower ruminal degradability in vitro, causing a decrease in protein quality and nutritional value.

Cohort profile: A Prospective Household cohort study of Influenza, Respiratory syncytial virus and other respiratory pathogens community burden and Transmission dynamics in South Africa, 2016-2018

Purpose

The PHIRST study (Prospective Household cohort study of Influenza, Respiratory Syncytial virus, and other respiratory pathogens community burden and Transmission dynamics in South Africa) aimed to estimate the community burden of influenza and respiratory syncytial virus (RSV) including the incidence of infection, symptomatic fraction, and to assess household transmission.

Participants

We enrolled 1684 individuals in 327 randomly selected households in a rural and an urban site over three consecutive influenza and two RSV seasons. A new cohort of households was enrolled each year. Participants were sampled with nasopharyngeal swabs twice‐weekly during the RSV and influenza seasons of the year of enrolment. Serology samples were collected at enrolment and before and after the influenza season annually.

Findings to Date

There were 122 113 potential individual follow‐up visits over the 3 years, and participants were interviewed for 105 783 (87%) of these. Out of 105 683 nasopharyngeal swabs, 1258 (1%) and 1026 (1%) tested positive on polymerase chain reaction (PCR) for influenza viruses and RSV, respectively. Over one third of individuals had PCR‐confirmed influenza each year. Overall, there was influenza transmission to 10% of household contacts of an index case.

Future Plans

Future planned analyses include analysis of influenza serology results and RSV burden and transmission. Households enrolled in the PHIRST study during 2016–2018 were eligible for inclusion in a study of SARS‐CoV‐2 transmission initiated in July 2020. This study uses similar testing frequency to assess the community burden of SARS‐CoV‐2 infection and the role of asymptomatic infection in virus transmission.

Welding fume nanoparticles from solid and flux-cored wires: Solubility, toxicity, and role of fluorides

Welding fume particles are hazardous. Their toxicity likely depends on their composition and reactivity. This study aimed at exploring the role of sodium or other fluorides (NaF), which are intentionally added to flux-cored wire electrodes for stainless steel welding, on the solubility (in phosphate buffered saline) and toxicity of the generated welding fume particles. A multi-analytical particle characterization approach along with in-vitro cell assays was undertaken. The release of Cr(VI) and Mn from the particles was tested as a function of fluoride solution concentration. The welding fume particles containing NaF released significantly higher amounts of Cr(VI) compared with solid wire reference fumes, which was associated with increased cytotoxicity and genotoxicity in-vitro. No crystalline Na or potassium (K) containing chromates were observed. Cr(VI) was incorporated in an amorphous mixed oxide. Solution-added fluorides did not increase the solubility of Cr(VI), but contributed to a reduced Mn release from both solid and flux-cored wire fume particles and the reduction of Cr(VI) release from solid wire fume particles. Chemical speciation modeling suggested that metal fluoride complexes were not formed. The presence of NaF in the welding electrodes did not have any direct, but possibly an indirect, role in the Cr(VI) solubility of welding fumes.

Nanoscale Mass Spectrometry Multimodal Imaging via Tip-Enhanced Photothermal Desorption

Materials ranging from adhesives, pharmaceuticals, lubricants, and personal care products are traditionally studied using macroscopic characterization techniques. However, their functionality is in reality defined by details of chemical organization on often noncrystalline matter with characteristic length scales on the order of microns to nanometers. Additionally, these materials are traditionally difficult to analyze using standard vacuum-based approaches that provide nanoscale chemical characterization due to their volatile and beam-sensitive nature. Therefore, approaches that operate under ambient conditions need to be developed that allow probing of nanoscale chemical phenomena and correlated functionality. Here, we demonstrate a tool for probing and visualizing local chemical environments and correlating them to material structure and functionality using advanced multimodal chemical imaging on a combined atomic force microscopy (AFM) and mass spectrometry (MS) system using tip-enhanced photothermal desorption with atmospheric pressure chemical ionization (APCI). We demonstrate enhanced performance metrics of the technique for correlated imaging and point sampling and illustrate the applicability for the analysis of trace chemicals on a human hair, additives in adhesives on paper, and pharmaceuticals samples notoriously difficult to analyze in a vacuum environment. Overall, this approach of correlating local chemical environments to structure and functionality is key to advancing research in many fields ranging from biology, to medicine, to material science.

Incident Cognitive Impairment During Aging in Rural South Africa: Evidence From the HAALSI Cohort, 2014 to 2019

We estimated the incidence of cognitive impairment and its key sociodemographic, social, and health-related predictors at the first longitudinal follow-up of the population-representative “Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa” (HAALSI) cohort of adults aged ≥40 in rural Agincourt, South Africa. Cognitive impairment was defined as scoring ≥1.5 SD below the baseline mean composite time orientation and episodic memory score, or requiring a proxy interview with “fair” or “poor” proxy-reported memory. Activity of daily living (ADL) limitations were compared according to incident cognitive impairment status. Incidence rates (IRs) and rate ratios (IRRs) for cognitive impairment according to sociodemographic, social, and health-related predictors were estimated using Poisson regression with robust standard errors, and weighted to account for mortality. Over a 3.7-year mean follow-up, 309/3,861 at-risk participants newly developed cognitive impairment (IR=24.0/1000 person-years (PY); 95% CI: 21.6-26.8). Incidence increased from IR=9.1/1000 PY (95% CI: 5.5-16.1) among those aged 40-44 at baseline to IR=76.5/1000 PY (95% CI: 63.2-93.4) among those aged 80+. At least one ADL limitation was prevalent in 39% of those with incident cognitive impairment, compared to 7% of non-impaired participants. Incident cognitive impairment did not vary by sex/gender, HIV status, or cardiovascular factors, but was strongly graded according to education, literacy, household assets, employment, marital status, and frequency of alcohol consumption. This study presents one of the first incidence rate estimates for cognitive impairment in sub-Saharan Africa. Social disparities in cognitive impairment were apparent in patterns similar to many high-income countries.

Photon-recoil imaging: Expanding the view of nonlinear x-ray physics

Addressing the ultrafast coherent evolution of electronic wave functions has long been a goal of nonlinear x-ray physics. A first step toward this goal is the investigation of stimulated x-ray Raman scattering (SXRS) using intense pulses from an x-ray free-electron laser. Earlier SXRS experiments relied on signal amplification during pulse propagation through dense resonant media. By contrast, our method reveals the fundamental process in which photons from the primary radiation source directly interact with a single atom. We introduce an experimental protocol in which scattered neutral atoms rather than scattered photons are detected. We present SXRS measurements at the neon K edge and a quantitative theoretical analysis. The method should become a powerful tool in the exploration of nonlinear x-ray physics.

Defining the electrocardiographic and echocardiographic abnormalities in a population of older adults with cardiovascular disease in rural south africa

Background

The African continent is undergoing an epidemiologic transition from infectious to cardiovascular (CV) diseases. National health systems face a critical shortage of population-level data to target the growing burden of hypertension (HTN). Very little is known on the impact of HTN on the rural population in many African countries, where over 85% of the rural population will migrate to cities and shape the modern CV disease spectrum of Africa in the next decade.

Purpose

To characterize the prevalence of HTN and HTN-related EKG and TTE abnormalities in a rural cohort in South Africa (n=5,059).

Methods

Between 2014 and 2015, 804 EKGs and 158 TTEs were performed on participants aged 40 or older randomly sampled from a longitudinal cohort residing in the Agincourt sub-district of rural South Africa. EKGs and TTEs were interpreted by two blinded physicians, and clinically meaningful variables defined using the Minnesota code (EKG) and European Association of Cardiovascular Imaging guidelines (TTE). Chi-square tests were conducted to define the association of EKG/TTE abnormalities with HTN, and stratify by gender.

Results

Over 55% of the sample (n=810) met blood pressure criteria for HTN, with a high prevalence of obesity (29%). On EKG, 36.5% participants had left ventricular hypertrophy (LVH), 13.6% T wave abnormalities, 7.5% Q wave abnormalities and 18.8% prolonged QT interval. Males (n=291) had more LVH (45% vs 30.8%, p&lt;0.01) and Q wave abnormalities (10% vs 5.9%, p=0.04) than females. Instead, females (n=438) had more prolonged QT intervals (28.8% vs 21%, p=0.02). Compared to those without HTN, participants with HTN had more LVH (45.4% vs 22.1%, p&lt;0.01), ST segment abnormalities (17.4% vs 10.7%, p&lt;0.01) and prolonged QT interval (23.4% vs 11.4%, p&lt;0.01). On TTE, there was a high prevalence of moderate (31%) / severe (25.8%) diastolic dysfunction, and concentric LVH (31.6%). Females had more concentric LVH (40.8% vs 13.5%, p&lt;0.01), and high relative wall thickness (70% vs 18.1%, p&lt;0.01) than males. Participants with HTN had more concentric LVH (42.5% vs 8.2%, p&lt;0.01), LV mass (58.5% vs 20.4%, p&lt;0.01) and LV mass index (52.8% vs 30.6%, p&lt;0.01), than those without HTN.

Conclusions

The rural population in South Africa is already affected by a high burden of HTN and high obesity levels. Within this cohort, patients with HTN have significantly more EKG and TTE abnormalities that predict adverse CV outcomes. EKG and TTE evaluation can be used to identify high-risk groups that national health systems should prioritize with frequent monitoring and more aggressive medical treatment.

Funding Acknowledgement

Type of funding source: Private hospital(s). Main funding source(s): Brigham and Women's Hospital

Forensic postmortem computed tomography in suspected unnatural adult deaths

PURPOSE

Our study sought to evaluate validity of forensic postmortem CT in establishing cause of death (COD) in suspected unnatural adult death based on the reference standard of autopsy.

METHODS

In our prospective, single-center study, 64 of 94 consecutive corpses (70.7 % male, mean age: 47.4 years) who underwent CT and autopsy between November 2013 and April 2019 were included in the analysis. Primary objective was agreement between CT and autopsy on primary COD using kappa statistics. Secondary objectives were competing COD and specific pathological findings.

RESULTS

Agreement on primary COD between forensic CT and autopsy without or in consideration of toxicological and histological findings was strong (85.9 % [55 of 64 corpses]; κ = 0.83 [95 %CI: 0.74 to 0.93] and 95.3 % [61 of 64 corpses]; κ = 0.94 [95 %CI: 0.84-1.04], respectively, McNemar p = 0.03). Sensitivity and specificity of CT in identification of acute heart failure, intracranial bleeding, burns and heat shocks, gunshot wounds, polytrauma, cranio-cerebral trauma, and strangulation or hanging was 100 %, each. Acute respiratory failure was detected with a sensitivity and specificity of 100 % and 96.8 %, cuts and stab wounds with 95.2 % and 100 %, and intoxication, pneumonia, or gastrointestinal bleeding with 60.0 % and 100 %, respectively. Agreement on competing COD was moderate (51.6 %, [33 of 64 corpses]; κ = 0.47 [95 %CI: 0.40 to 0.53], p < 0.001).

CONCLUSIONS

Forensic postmortem CT, complemented by external, toxicological, and histological examination was sufficiently valid to assess primary COD in the majority of suspected unnatural deaths with few restrictions.

The Impact of a Conditional Cash Transfer on Multidimensional Deprivation of Young Women: Evidence from South Africa's HTPN 068

Despite the growing popularity of multidimensional poverty measurement and analysis, its use to measure the impact of social protection programs remains scarce. Using primary data collected for the evaluation of HIV Prevention Trials Network (HPTN) 068, a randomized, conditional cash transfer intervention for young girls in South Africa that ran from 2011 to 2015, we construct an individual-level measure of multidimensional poverty, a major departure from standard indices that use the household as the unit of analysis. We construct our measure by aggregating multiple deprivation indicators across six dimensions and using a system of nested weights where each domain is weighted equally. Our findings show that the cash transfer consistently reduces deprivations among girls, in particular through the domains of economic agency, violence, and relationships. These results show how social protection interventions can improve the lives of young women beyond single domains and demonstrate the potential for social protection to simultaneously address multiple targets of the SDGs.

Publisher Correction: Enhanced ferroelectricity in ultrathin films grown directly on silicon

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Size-dependent influence of NOx on the growth rates of organic aerosol particles

Atmospheric new-particle formation (NPF) affects climate by contributing to a large fraction of the cloud condensation nuclei (CCN). Highly oxygenated organic molecules (HOMs) drive the early particle growth and therefore substantially influence the survival of newly formed particles to CCN. Nitrogen oxide (NOx) is known to suppress the NPF driven by HOMs, but the underlying mechanism remains largely unclear. Here, we examine the response of particle growth to the changes of HOM formation caused by NOx. We show that NOx suppresses particle growth in general, but the suppression is rather nonuniform and size dependent, which can be quantitatively explained by the shifted HOM volatility after adding NOx. By illustrating how NOx affects the early growth of new particles, a critical step of CCN formation, our results help provide a refined assessment of the potential climatic effects caused by the diverse changes of NOx level in forest regions around the globe.

HIV self-testing among young women in rural South Africa: A randomized controlled trial comparing clinic-based HIV testing to the choice of either clinic testing or HIV self-testing with secondary distribution to peers and partners

BACKGROUND

HIV testing rates in many hyper-endemic areas are lower than needed to curtail the HIV epidemic. New HIV testing strategies are needed to overcome barriers to traditional clinic based testing; HIV self-testing is one modality that offers promise in reaching individuals who experience barriers to clinic-based testing.

METHODS

We conducted a randomized control trial among young women ages 18-26 living in rural Mpumalanga, South Africa where they were randomized in a 1:1 allocation to either the: (1) HIV Counseling and Testing (HCT) arm: an invitation to test at one of the 9 local government clinics where free HCT is provided and is standard of care (SOC), or (2) choice arm: choice of either a clinic-based HCT invitation or oral HIV Self-Testing (HIVST) kits. Depending on the arm, participants were also provided either: (1) 4 HCT invitations to provide to peers/partners for HIV testing at one of the 9 local clinics, or (2) 4 HIV self-test kits to provide to peers/partners (thus 5 total HIVST kits or HCT invitations). Young women were asked to return 3 months and 9 months after enrollment to assess testing uptake and invitation or kit distribution to peers and partners and experiences with testing. Peers and partners who were reported by index participants to have received kits/invitations during follow-up visits were also invited to attend a study visit to assess their testing experiences. The trial is registered at clinical trials.gov NCT03162965.

FINDINGS

287 young women were enrolled and randomized, with 146 randomized to the HCT arm and 141 to the choice (HCT or HIVST) arm. Of those randomized to the choice arm, over 95% (n=135) chose the HIV self-testing kit and only 6 individuals chose HCT. At the 3-month follow-up visit, 92% of index participants in the choice arm reported having tested for HIV compared to 43% of participants in the HCT arm, resulting in a significant risk difference of 49% (95% CI 40%, 58%). By 9 months, this difference decreased to a risk difference of 25% (95% CI 17%, 33%) between arms (96% in the choice arm and 72% in the HCT arm). Participants in the choice arm were also more likely to invite peers and partners to test compared to the HCT arm (94% vs. 76% or an average of 4.97 vs 2.79 tests). Few male partners were invited to test by index participants; however, index participants in the choice arm were more likely to have their male partners test than index participants in the HCT arm (RR 2.99, 95% CI 1.45, 6.16).

INTERPRETATION

When given a choice between clinic-based HIV testing and HIV oral self-testing, the overwhelming majority of young women chose HIVST. In addition, those offered a choice of HIV testing modality were much more likely to test, distribute test kits to peers and partners, and to have peers and partners who reported testing compared to the HCT arm. Self-testing offers an important opportunity to significantly increase testing rates among young women and their peers and partners compared to clinic-based HCT. Other strategies to reach men with testing are needed.

FUNDING

US National Institutes of Health.

Self-Esteem as an Indicator of Transactional Sex Among Young Women in Rural South Africa (HPTN 068)

Transactional sex (TS) has been shown to contribute to the HIV epidemic in sub-Saharan Africa. Previous research has yet to identify psychosocial factors that make young women vulnerable to engaging in TS. This analysis examined the association between self-esteem and TS among young women in rural South Africa. A post hoc analysis of post-intervention survey data from HPTN 068 was conducted. Log-binomial regression was used to compute a prevalence ratio measure of association. Among 1942 young women, the prevalence of TS among those with lower self-esteem was 4.7 times the prevalence of TS among those with higher self-esteem (p < 0.001). Findings provide support for the association between lower self-esteem and TS in this context and may inform intervention development.

Images from the surface of asteroid Ryugu show rocks similar to carbonaceous chondrite meteorites

The near-Earth asteroid (162173) Ryugu is a 900-m-diameter dark object expected to contain primordial material from the solar nebula. The Mobile Asteroid Surface Scout (MASCOT) landed on Ryugu's surface on 3 October 2018. We present images from the MASCOT camera (MASCam) taken during the descent and while on the surface. The surface is covered by decimeter- to meter-sized rocks, with no deposits of fine-grained material. Rocks appear either bright, with smooth faces and sharp edges, or dark, with a cauliflower-like, crumbly surface. Close-up images of a rock of the latter type reveal a dark matrix with small, bright, spectrally different inclusions, implying that it did not experience extensive aqueous alteration. The inclusions appear similar to those in carbonaceous chondrite meteorites.

Gas Chromatographic Method for Putrescine and Cadaverine in Canned Tuna and Mahimahi and Fluorometric Method for Histamine (Minor Modification of AOAC Official Method 977.13): Collaborative Study

A collaborative study was conducted to test a modification to the AOAC fluorometric method for histamine (AOAC® Official Method 977.13) that substitutes 75% methanol as the extracting solvent. All other steps remain unchanged. The extracts prepared with 75% methanol were also used to collaboratively test a gas chromatographic (GC) method for determination of putrescine and cadaverine in seafood. In the GC method, the extracted diamines are converted to fluorinated derivatives, the reaction mixtures are passed through solid-phase extraction columns, and the derivatives are quantitated by electron capture GC after separation on an OV-225 column. Fourteen laboratories using the GC method for putrescine and cadaverine and 16 laboratories using the fluorometric method for histamine analyzed 14 canned tuna and raw mahimahi (including blind duplicates and a spike) containing 0.2-2.6 ppm putrescine, 0.6-9.1 ppm cadaverine, and 0.6-154 ppm histamine. At the 5 ppm level, recoveries ranged from 71 to 102% for putrescine and 77 to 112% for cadaverine; the respective repeatability relative standard deviations (RSDr) were 5.2 and 15%, and the respective reproducibility relative standard deviations (RSDR) were 8.8 and 18%. At the 50 ppm level, histamine recoveries ranged from 84 to 125%, RSDr was 3.6%, and RSDR was 9.4%. The GC method for determination of putrescine in canned tuna and cadaverine in canned tuna and mahimahi has been adopted first action by AOAC INTERNATIONAL, and the AOAC Official Method 977.13, Histamine in Seafood, Fluorometric Method, has been modified

Simultaneous Determination of Multiple Tetracycline Residues in Milk by Metal Chelate Affinity Chromatography: Collaborative Study

To meet federal and state regulatory needs, a liquid chromatographic (LC) method with ultraviolet (UV) detection was developed for determination of 7 tetracyclines at 30 ng/mL in milk. Raw milk samples are defatted, acidified, and centrifuged to remove proteins, and tetracyclines are specifically absorbed from the milk by chelation with metal ions bound to small Chelating Sepharose Fast Flow columns. Tetracyclines are removed from these columns with EDTA-containing buffer, and extracts are further cleaned by ultrafiltration. Finally, extracts are concentrated and analyzed simultane ously by using on-line concentration. This method was validated in a collaborative study that involved 11 laboratories, including the authors’ laboratory. Each laboratory was asked to prepare and analyze known control and fortified milk samples, as well as 18 coded blind samples. Eight laboratories completed all analyses. Average interlaboratory recoveries for the known fortified samples ranged from 59% (methacycline at 15 ng/mL) to 78% (oxytetracy cline at 60 ng/mL). Average recovery for each of 7 residues at 30 ng/mL were between 60 and 110%, meeting single-residue guidelines for accuracy set by the U.S. Food and Drug Administration. Reproducibility relative standard deviation (RSDR) for the known fortified samples varied from 11 to 39%, with 6 of 7 residues at the 30 ng/mL level having RSDR values at or below 20%. Seven of 8 laboratories correctly identified blind control milk samples and all 28 residues present in blind samples. The metal chelate affinity—LC method for determination of multiple tetracycline residues in milk has been adopted first action by AOAC INTERNATIONAL.

Recombinant HIV-1 vaccine candidates based on replication-defective flavivirus vector

Multiple approaches utilizing viral and DNA vectors have shown promise in the development of an effective vaccine against HIV. In this study, an alternative replication-defective flavivirus vector, RepliVax (RV), was evaluated for the delivery of HIV-1 immunogens. Recombinant RV-HIV viruses were engineered to stably express clade C virus Gag and Env (gp120TM) proteins and propagated in Vero helper cells. RV-based vectors enabled efficient expression and correct maturation of Gag and gp120TM proteins, were apathogenic in a sensitive suckling mouse neurovirulence test, and were similar in immunogenicity to recombinant poxvirus NYVAC-HIV vectors in homologous or heterologous prime-boost combinations in mice. In a pilot NHP study, immunogenicity of RV-HIV viruses used as a prime or boost for DNA or NYVAC candidates was compared to a DNA prime/NYVAC boost benchmark scheme when administered together with adjuvanted gp120 protein. Similar neutralizing antibody titers, binding IgG titers measured against a broad panel of Env and Gag antigens, and ADCC responses were observed in the groups throughout the course of the study, and T cell responses were elicited. The entire data demonstrate that RV vectors have the potential as novel HIV-1 vaccine components for use in combination with other promising candidates to develop new effective vaccination strategies.

Conditional cash transfers and the reduction in partner violence for young women: an investigation of causal pathways using evidence from a randomized experiment in South Africa (HPTN 068)

Introduction

Evidence has shown that the experience of violence by a partner has important influences on women's risk of HIV acquisition. Using a randomized experiment in northeast South Africa, we found that a conditional cash transfer (CCT) targeted to poor girls in high school reduced the risk of physical intimate partner violence (IPV) in the past 12 months by 34%. The purpose of this analysis is to understand the pathways through which the CCT affects IPV.

Methods

HPTN 068 was a phase 3, randomized controlled trial in rural Mpumalanga province, South Africa. Eligible young women (aged 13–20) and their parents or guardians were randomly assigned (1:1) to either receive a monthly cash transfer conditional on monthly high school attendance or no cash transfer. Between 2011 and 2015, participants (N = 2,448) were interviewed at baseline, then at annual follow‐up visits at 12, 24 and 36 months. The total effect of the CCT on IPV was estimated using a GEE log‐binomial regression model. We then estimated controlled direct effects to examine mediation of direct effects through intermediate pathways. Mediators include sexual partnership measures, the sexual relationship power scale, and household consumption measures.

Results

We found evidence that the CCT works in part through delaying sexual debut or reducing the number of sexual partners. The intervention interacts with these mediators leading to larger reductions in IPV risk compared to the total effect of the CCT on any physical IPV [RR 0.66, CI(95%):0.59–0.74]. The largest reductions are seen when we estimate the controlled direct effect under no sexual debut [RR 0.57, CI(95%):0.48–0.65] or under no sexual partner in the last 12 months [RR 0.53, CI(95%):0.46–0.60].

Conclusions

Results indicate that a CCT for high school girls has protective effects on their experience of IPV and that the effect is due in part to girls choosing not to engage in sexual partnerships, thereby reducing the opportunity for IPV. As a lower exposure to IPV and safer sexual behaviours also protect against HIV acquisition, this study adds to the growing body of evidence on how cash transfers may reduce young women's HIV risk.

Pedestrian hit by a car impacted metal pole: reconstructing the head load

Fatal head injuries are frequently seen in pedestrians hit by motorized vehicles. In our case, the pedestrian sustained a devastating head injury with skull splitting in the mediosagittal plane. A car collided with a traffic sign causing a bending of the pole. The metal pole hit a man standing close beside it; the man had a head injury severity that is more commonly due to falling objects than due to traffic accidents. Assuming a head mass of 5 kg, simplified calculations yield maximum contact forces of ca. 36 kN exceeding mean parietal fracture forces which are in the order of magnitude of 12.5 kN. The influences of the effective body mass and the horizontal distance between the pole and the pedestrian on maximum contact forces are investigated. High contact forces in our case can be mainly explained by the comparably high impact velocity and by a partial mass transfer of the total car mass to the pole.

ART Denial: Results of a Home-Based Study to Validate Self-reported Antiretroviral Use in Rural South Africa

There is increasing interest in home based testing and treatment of HIV to expand access to treatment in sub-Saharan Africa. Such programs rely on self-reported HIV history and use of antiretroviral therapy (ART). However, the accuracy of self-reported ART use in community settings is not well described. In this study, we compared self-reported ART (SR-ART) use in a home based survey against biological exposure to ART (BE-ART), in a population study of older adults in South Africa. Health and Aging in Africa: a Longitudinal Study of an INDEPTH community in South Africa (HAALSI) is a cohort of adults aged 40 +. The baseline home-based interview included self-reported HIV status and ART use. All participants also underwent biological testing for HIV antibodies, viral load and exposure to emtricitabine (FTC) or lamivudine (3TC), which are included in all first-line and second-line ART regimens in the public-sector South African HIV program. We calculated the performance characteristics for SR-ART compared to BE-ART and fit multivariable logistic regression models to identify correlates of invalid SR-ART responses. Of 4560 HAALSI participants with a valid HIV test result available, 1048 (23%) were HIV-positive and 734 [70% of people living with HIV (PLWH)] were biologically validated ART users (BE-ART). The sensitivity of SR-ART use was 64% (95% CI 61-68%) and the specificity was 94% (95% CI 91-96%); the positive predictive value (PPV) was 96% (95% CI 94-98%) and negative predictive value (NPV) was 52% (95% CI 48-56%). We found no sociodemographic predictors of accurate SR-ART use. Over one in three individuals with detectable ART in their blood denied current ART use during a home-based interview. These results demonstrate ongoing stigma related to HIV and its treatment, and have important implications for community health worker programs, clinical programs, and research studies planning community-based ART initiation in the region.

Assessing risk for HIV infection among adolescent girls in South Africa: an evaluation of the VOICE risk score (HPTN 068)

INTRODUCTION

To maximize impact and minimize costs, antiretroviral pre-exposure prophylaxis (PrEP) interventions should be offered to those at highest risk for HIV infection. The risk score derived from the VOICE trial is one tool currently being utilized to determine eligibility in adolescent PrEP trials in sub-Saharan Africa. This study is aimed at evaluating the utility of the risk score in predicting HIV incidence among a cohort of adolescent girls in rural South Africa.

METHODS

We utilized data from HIV Prevention Trials Network (HPTN) 068, a phase III randomized controlled trial conducted in rural Mpumalanga province, South Africa. School-attending young women aged 13 to 20 years were enrolled into the trial from 2011 to 2012 and followed for up to three years. A risk score based on individual-level risk factors measured at enrolment was calculated for HPTN 068 participants who completed a one-year follow-up visit and were HIV seronegative at enrolment. Possible scores ranged from 0 to 10. A proportional hazards model was then used to determine if risk score at enrolment was predictive of incident HIV infection at follow-up and an area under the curve analysis was used to examine the predictive ability of the score.

RESULTS AND DISCUSSION

The risk score had limited variability in the HPTN 068 sample. Scores ≥5 identified 85% of incident infections from 94% of the sample, compared to the VOICE sample in which scores ≥5 identified 91% of incident infections from only 64% of participants. The risk score did not predict HIV incidence after one year of follow-up (hazard ratio = 1.029; 95% confidence interval (CI): 0.704, 1.503, p = .884) and showed poor predictive ability (area under the curve = 0.55; 95% CI: 0.44, 0.65). Certain individual risk factors that comprise the risk score may be context specific or not relevant for adolescent populations. Additional factors should be considered when assessing risk for the purposes of determining PrEP eligibility.

CONCLUSIONS

The VOICE risk score demonstrated low utility to predict HIV incidence in the HPTN 068 sample. Findings highlight the need for an age and developmentally appropriate tool for assessing risk for HIV infection among adolescents. Use of the VOICE risk score for determining PrEP eligibility in younger populations should be carefully considered.

Depressive Symptoms and Their Relation to Age and Chronic Diseases Among Middle-Aged and Older Adults in Rural South Africa

BACKGROUND

Understanding how depression is associated with chronic conditions and sociodemographic characteristics can inform the design and effective targeting of depression screening and care interventions. In this study, we present some of the first evidence from sub-Saharan Africa on the association between depressive symptoms and a range of chronic conditions (diabetes, HIV, hypertension, and obesity) as well as sociodemographic characteristics.

METHODS

A questionnaire was administered to a population-based simple random sample of 5,059 adults aged 40 years and older in Agincourt, South Africa. Depressive symptoms were measured using a modified version of the eight-item Center for Epidemiological Studies-Depression screening tool. Diabetes was assessed using a capillary blood glucose measurement and HIV using a dried blood spot.

RESULTS

17.0% (95% confidence interval: 15.9%-18.1%) of participants had at least three depressive symptoms. None of the chronic conditions were significantly associated with depressive symptoms in multivariable regressions. Older age was the strongest correlate of depressive symptoms with those aged 80 years and older having on average 0.63 (95% confidence interval: 0.40-0.86; p < .001) more depressive symptoms than those aged 40-49 years. Household wealth quintile and education were not significant correlates.

CONCLUSIONS

This study provides some evidence that the positive associations of depression with diabetes, HIV, hypertension, and obesity that are commonly reported in high-income settings might not exist in rural South Africa. Our finding that increasing age is strongly associated with depressive symptoms suggests that there is a particularly high need for depression screening and treatment among the elderly adults in rural South Africa.

Nanomechanics of cellulose deformation reveal molecular defects that facilitate natural deconstruction

Technologies surrounding utilization of cellulosic materials have been integral to human society for millennia. In many materials, controlled introduction of defects provides a means to tailor properties, introduce reactivity, and modulate functionality for various applications. The importance of defects in defining the behavior of cellulose is becoming increasingly recognized. However, fully exploiting defects in cellulose to benefit biobased materials and conversion applications will require an improved understanding of the mechanisms of defect induction and corresponding molecular-level consequences. We have identified a fundamental relationship between the macromolecular structure and mechanical behavior of cellulose nanofibrils whereby molecular defects may be induced when the fibrils are subjected to bending stress exceeding a certain threshold. By nanomanipulation, imaging, and molecular modeling, we demonstrate that cellulose nanofibrils tend to form kink defects in response to bending stress, and that these macromolecular features are often accompanied by breakages in the glucan chains. Direct observation of deformed cellulose fibrils following partial enzymatic digestion reveals that processive cellulases exploit these defects as initiation sites for hydrolysis. Collectively, our findings provide a refined understanding of the interplay between the structure, mechanics, and reactivity of cellulose assemblies.

HIV self-testing: South African young adults' recommendations for ease of use, test kit contents, accessibility, and supportive resources

BACKGROUND

The uptake of HIV self-testing (HIVST) could address socio-structural barriers that prevent South African youth from utilizing the testing resources available in their communities. However, to facilitate this, we must tailor components of the HIVST kit and process to ensure that we reach and encourage youth to test. The purpose of this study to elucidate concerns and issues regarding HIVST rollout among South African youth.

METHODS

This study was conducted in two phases: 1) focus group discussions with rural, South African youth aged 18-24 and 2) direct observations of participants completing with an oral HIVST kit and/or a blood based HIVST kit. In phase 2a participants were invited to try both an oral and blood-based HIVST kit. In phase 2b, participants selected the HIVST kit of their choice.

RESULTS

We enrolled 35 unique participants in phase 1, 20 participants in phase 2a, and 40 participants in phase 2b. While the focus group discussions highlighted hypothetical HIVST use only, participants appreciated the privacy that the HIVST could afford them. However, they expressed concerns about whether HIVST could be trusted due to false positives and negatives, as well as whether a person would be able to emotionally handle the results if they tested alone. They suggested that the kits be used alongside someone who could provide support. In phases 2a and 2b, participants were overwhelmingly positive about both kits regarding ease of use and whether their results could be trusted. The participants, however, experienced more challenges with the blood-based versus oral test. When given the choice in phase 2b, most participants (80%) chose the oral HIVST over the blood-based HIVST.

CONCLUSIONS

During the focus group discussions, participants raised concerns about the validity of HIVST, lack of emotional support when testing alone, and the cost of HIVST kits, all of which could be addressed through current testing campaigns. Most of those who actually tested had positive experiences with HIVST and would recommend it to their friends. When offered a choice, most preferred the oral test.

TRIAL REGISTRATION

NCT03162965 , registered 19th May 2017.