Effect of positive social comparative feedback on the resting state connectivity of dopaminergic neural pathways: A preliminary investigation.

Positive social comparative feedback is hypothesized to generate a dopamine response in the brain, similar to reward, by enhancing expectancies to support motor skill learning. However, no studies have utilized neuroimaging to examine this hypothesized dopaminergic mechanism. Therefore, the aim of this preliminary study was to investigate the effect of positive social comparative feedback on dopaminergic neural pathways measured by resting state connectivity. Thirty individuals practiced an implicit, motor sequence learning task and were assigned to groups that differed in feedback type. One group received feedback about their actual response time to complete the task (RT ONLY), while the other group received feedback about their response time with positive social comparison (RT + POS). Magnetic resonance imaging was acquired at the beginning and end of repetitive motor practice with feedback to measure practice-dependent changes in resting state brain connectivity. While both groups showed improvements in task performance and increases in performance expectancies, ventral tegmental area and the left nucleus accumbens (mesolimbic dopamine pathway) resting state connectivity increased in the RT + POS group but not in the RT ONLY group. Instead, the RT ONLY group showed increased connectivity between ventral tegmental area and primary motor cortex. Positive social comparative feedback during practice of a motor sequence task may induce a dopaminergic response in the brain along the mesolimbic pathway. However, given that absence of effects on expectancies and motor learning, more robust and individualized approaches may be needed to provide beneficial psychological and behavioral effects.

Fatigue Is Associated With Perceived Effort and 2-Dimensional Reach Performance After Stroke.

BACKGROUND AND PURPOSE: Poststroke fatigue (PSF) is prevalent and often manifests as high perceived effort during activities. Little is known about how PSF influences goal-directed reaching after stroke. The purpose of this study was 2-fold (1) to evaluate how perceived effort changed when individuals with stroke performed a reaching task with various demands and (2) to determine whether PSF was associated with perceived effort during reaching and reach performance. METHODS: Thirty-six individuals with chronic stroke performed 2-dimensional reach actions under varied conditions with the more and less affected arms. Perceived effort during reaching was assessed using rating of perceived exertion (RPE) and Paas Mental Effort Rating Scale (MERS). Derived reach kinematics were used to quantify reach performance. The Fatigue Severity Scale (FSS) was administered to assess fatigue severity. RESULTS: Perceived effort was higher when participants reached with the more affected arm, reached toward far and small targets, and performed memory-guided reaching. Both RPE and MERS significantly correlated with the FSS score (r = 0.50 and 0.35, respectively, P < 0.05). Further, FSS correlated with movement time during the more affected arm reaching (ρ = 0.40, p < 0.05) and reach performance discrepancy between the fast and self-selected speed conditions when participants performed with the less affected arm (ρ = 0.36, P < 0.05). Exploratory analysis revealed that the relationship between fatigue and reach control appeared to be modulated by task demand. DISCUSSION AND CONCLUSIONS: PSF is associated with perceived effort during reaching and reach performance after stroke. These relationships might offer insights into arm performance in the real world after stroke. VIDEO ABSTRACT: for more insights from the authors Supplemental Digital Content available at http://links.lww.com/JNPT/A476.

Workforce Engagement for Compassionate Advocacy, Resilience, and Empowerment (WE CARE): An Evidence-Based Wellness Program.

Poor well-being and burnout among the nursing workforce were heightened by the COVID-19 pandemic. The purpose of this study was to deliver, spread, and sustain an evidence-based wellness program, Workforce Engagement for Compassionate Advocacy, Resilience, and Empowerment (WE CARE), for nurse leaders, staff registered nurses (RNs), and patient care technicians (PCTs) to ameliorate or prevent burnout, promote resilience, and improve the work environment. The program included Community Resiliency Model (CRM) training provided by a certified 6-member wellness team. A baseline and 6-month follow-up survey included measures of well-being, moral distress, burnout, resilience, perceived organizational support (POS), job satisfaction, intent to leave (ITL), and work environment. A total of 4900 inpatient RNs, PCTs, and leaders of a 1207-bed academic medical center in the southeastern United States were analyzed. From baseline (n = 1533) to 6-month follow-up (n = 1457), well-being, moral distress, burnout, job satisfaction, and work environment improved; however, resilience, POS, and ITL did not. Although we have seen some improvements in well-being and mental health indicators, it is still early in the intervention period to have reached a critical mass with the training and other interventions. The mental health and work environment issues among nurses are so complex, no one-size-fits-all intervention can resolve.

Effect of behavioural practice targeted at the motor action selection network after stroke.

Motor action selection engages a network of frontal and parietal brain regions. After stroke, individuals activate a similar network, however, activation is higher, especially in the contralesional hemisphere. The current study examined the effect of practice on action selection performance and brain activation after stroke. Sixteen individuals with chronic stroke (Upper Extremity Fugl-Meyer motor score range: 18-61) moved a joystick with the more-impaired hand in two conditions: Select (externally cued choice; move right or left based on an abstract rule) and Execute (simple response; move same direction every trial). On Day 1, reaction time (RT) was longer in Select compared to Execute, which corresponded to increased activation primarily in regions in the contralesional action selection network including dorsal premotor, supplementary motor, anterior cingulate and parietal cortices. After 4 days of practice, behavioural performance improved (decreased RT), and only contralesional parietal cortex significantly increased during Select. Higher brain activation on Day 1 in the bilateral action selection network, dorsolateral prefrontal cortex and contralesional sensory cortex predicted better performance on Day 4. Overall, practice led to improved action selection performance and reduced brain activation. Systematic changes in practice conditions may allow the targeting of specific components of the motor network during rehabilitation after stroke.

Characterizing Differences in Sources of and Contributions to Fecal Contamination of Sediment and Surface Water with the Microbial FIT Framework.

Surface water monitoring and microbial source tracking (MST) are used to identify host sources of fecal pollution and protect public health. However, knowledge of the locations of spatial sources and their relative impacts on the environment is needed to effectively mitigate health risks. Additionally, sediment samples may offer time-integrated information compared to transient surface water. Thus, we implemented the newly developed microbial find, inform, and test framework to identify spatial sources and their impacts on human (HuBac) and bovine (BoBac) MST markers, quantified from both riverbed sediment and surface water in a bovine-dense region. Dairy feeding operations and low-intensity developed land-cover were associated with 99% (p-value < 0.05) and 108% (p-value < 0.05) increases, respectively, in the relative abundance of BoBac in sediment, and with 79% (p-value < 0.05) and 39% increases in surface water. Septic systems were associated with a 48% increase in the relative abundance of HuBac in sediment and a 56% increase in surface water. Stronger source signals were observed for sediment responses compared to water. By defining source locations, predicting river impacts, and estimating source influence ranges in a Great Lakes region, this work informs pollution mitigation strategies of local and global significance.

Identifying bioaugmentation candidates for bioremediation of polycyclic aromatic hydrocarbons in contaminated estuarine sediment of the Elizabeth River, VA, USA.

Estuarine sediments near former creosoting facilities along the Elizabeth River (Virginia, USA) are contaminated by polycyclic aromatic hydrocarbons (PAHs). In this study, we interrogated the bacterial community of the Elizabeth River with both culture-based and culture-independent methods to identify potential candidates for bioremediation of these contaminants. DNA-based stable isotope probing (SIP) experiments with phenanthrene and fluoranthene using sediment from the former Republic Creosoting site identified relevant PAH-degrading bacteria within the Azoarcus, Hydrogenophaga, and Croceicoccus genera. Targeted cultivation of PAH-degrading bacteria from the same site recovered 6 PAH-degrading strains, including one strain highly similar to Hydrogenophaga sequences detected in SIP experiments. Other isolates were most similar to organisms within the Novosphingobium, Sphingobium, Stenotrophomonas, and Alcaligenes genera. Lastly, we performed 16S rRNA gene amplicon microbiome analyses of sediment samples from four sites, including Republic Creosoting, with varying concentrations of PAHs. Analysis of these data showed a striking divergence of the microbial community at the highly contaminated Republic Creosoting site from less contaminated sites with the enrichment of several bacterial clades including those affiliated with the Pseudomonas genus. Sequences within the microbiome libraries similar to SIP-derived sequences were generally found at high relative abundance, while the Croceicoccus sequence was present at low to moderate relative abundance. These results suggest that Azoarcus and Hydrogenophaga strains might be good target candidates for biostimulation, while Croceicoccus spp. might be good targets for bioaugmentation in these sediments. Furthermore, this study demonstrates the value of culture-based and culture-independent methods in identifying promising bacterial candidates for use in a precision bioremediation scheme. KEY POINTS: • This study highlights the importance of using multiple strategies to identify promising bacterial candidates for use in a precision bioremediation scheme. • We used both selective cultivation techniques and DNA-based stable isotope probing to identify bacterial degraders of prominent PAHs at a historically contaminated site in the Elizabeth River, VA, USA. • Azoarcus and Hydrogenophaga strains might be good target candidates for biostimulation in Elizabeth River sediments, while Croceicoccus spp. might be good targets for bioaugmentation.

An Analysis of Frequency of Continuous Blood Pressure Variation and Haemodynamic Responses during Haemodialysis.

BACKGROUND: Higher beat-to-beat blood pressure (BP) variation during haemodialysis (HD) has been shown to be associated with elevated cardiac damage markers and white matter ischaemic changes in the brain suggesting relevance to end-organ perfusion. We aimed to characterize individual patterns of BP variation and associated haemodynamic responses to HD. METHODS: Fifty participants underwent continuous non-invasive haemodynamic monitoring during HD and BP variation were assessed using extrema point (EP) frequency analysis. Participants were divided into those with a greater proportion of low frequency (LF, n = 21) and high frequency (HF, n = 22) of BP variation. Clinical and haemodynamic data were compared between groups. RESULTS: Median EP frequencies for mean arterial pressure (MAP) of mid-week HD sessions were 0.54 Hz (interquartile range 0.18) and correlated with dialysis vintage (r = 0.32, p = 0.039), NT pro-BNP levels (r = 0.32, p = 0.038), and average real variability (ARV) of systolic BP (r = 0.33, p = 0.029), ARV of diastolic BP (r = 0.46, p = 0.002), and ARV of MAP (r = 0.57, p < 0.001). In the LF group, MAP positively correlated with cardiac power index (CPI) in each hour of dialysis, but not with total peripheral resistance index (TPRI). In contrast, in the HF group, MAP correlated with TPRI in each hour of dialysis but only with CPI in the first hour. CONCLUSIONS: EP frequency analysis of continuous BP monitoring during dialysis allows assessment of BP variation and categorization of individuals into low- or high-frequency groups, which were characterized by different haemodynamic responses to dialysis. This may assist in improved individualization of dialysis therapy.

Academic-Practice Partnership Pivot During COVID-19 Pandemic Surge.

Health care systems continue to experience the sequential aftermath of the COVID-19 pandemic, with major care access, quality, safety, financial sustainability, and workforce considerations. Yet, academic-clinical partnership opportunities exist for transformational change, even when efforts to respond to a pandemic seem insurmountable. A nursing partnership between an academic health center nursing school and university health system provided short- and long-term support for the nursing workforce shortage during a COVID-19 surge. An academic-clinical integration framework guided planning, clinical support activities, outcomes achieved, technology innovations, and shared lessons associated with these efforts. The COVID-19 surge response steps included a call to action, preparation for surge support by the academic and clinical partners, and a team approach for clinical service delivery by faculty, students, and staff. Through the 6-week COVID-19 surge response, more than 10 000 hours of hospital nurse staffing were provided by nursing school faculty and students; over 770 worked shifts that provided approximately 30% of the full surge hospital supplemental staffing and approximately 46 000 vaccine encounters. Well-established academic-clinical nursing partnerships allow for quick pivots in the rapidly changing COVID-19 environment that can enhance nursing clinical proficiency and competency, augment clinically immersive learning, and reinforce analytics to measure health outcomes, lower costs, improve access, quality, safety, and workforce conditions.

Predictors of Daily Steps at 1-Year Poststroke: A Secondary Analysis of a Randomized Controlled Trial.

Background and Purpose: Walking has the potential to improve endurance and community participation after stroke. Obtaining ≥6000 daily steps can decrease subsequent stroke risk. Early identification of those prone to low daily steps could facilitate interventions that lead to increased walking and improved health. The purpose of this study was to (1) determine which factors at 2 months poststroke can predict daily step counts at 1 year and (2) determine what step count at 2 months corresponds to obtaining ≥6000 daily steps at 1-year poststroke. Methods: This was a secondary analysis of data from the Locomotor Experience Applied Post Stroke trial, which enrolled participants with walking speeds <0.80 m/second at 2 months poststroke. Daily steps were assessed at 2 months and 1-year poststroke. Linear regression was used to predict daily step counts at 1 year based on factors including age, sex, race and/or ethnicity, stroke severity, walking speed, endurance, fitness, motor function, balance, and balance confidence. A receiver operating characteristic curve determined which step count corresponded to reaching ≥6000 steps at 1 year. Results: Data from 206 participants, mean age=63 (13) years, 43% female, mean baseline daily step count=2922 (2749) steps, were analyzed. The final model to predict daily steps at 1 year poststroke contained daily steps at 2 months and balance (Berg Balance Scale score); these factors explained 38% of the variability in daily steps at 1 year (P≤0.001). Participants obtaining ≥1632 daily steps at 2 months were 1.86 (95% CI, 1.52­2.27) times more likely to reach ≥6000 daily steps at 1-year poststroke. Conclusions: Daily steps and balance at 2 months poststroke were the strongest predictors of future daily steps. Improving daily physical activity and targeting balance early after stroke may be necessary to increase physical activity at 1-year poststroke.

Transmission of Antimicrobial-Resistant Staphylococcus aureus Clonal Complex 9 between Pigs and Humans, United States.

Transmission of livestock-associated Staphylococcus aureus clonal complex 9 (LA-SA CC9) between pigs raised on industrial hog operations (IHOs) and humans in the United States is poorly understood. We analyzed whole-genome sequences from 32 international S. aureus CC9 isolates and 49 LA-SA CC9 isolates from IHO pigs and humans who work on or live near IHOs in 10 pig-producing counties in North Carolina, USA. Bioinformatic analysis of sequence data from the 81 isolates demonstrated 3 major LA-SA CC9 clades. North Carolina isolates all fell within a single clade (C3). High-resolution phylogenetic analysis of C3 revealed 2 subclades of intermingled IHO pig and human isolates differing by 0-34 single-nucleotide polymorphisms. Our findings suggest that LA-SA CC9 from pigs and humans share a common source and provide evidence of transmission of antimicrobial-resistant LA-SA CC9 between IHO pigs and humans who work on or live near IHOs in North Carolina.

Noninvasive continuous intradialytic blood pressure monitoring: the key to improving haemodynamic stability.

PURPOSE OF REVIEW: Intradialytic hypotension (IDH) occurs in 20% of haemodialysis treatments, leading to end-organ ischaemia, increased morbidity and mortality; and contributing to poor quality of life for patients. Treatment of IDH is reactive since brachial blood pressure (BP) is recorded only intermittently during haemodialysis, making early detection and prediction of hypotension impossible. Noninvasive continuous BP monitoring would allow earlier detection of IDH and thus support the development of methods for its prediction and consequently prevention. RECENT FINDINGS: Noninvasive continuous BP monitoring is not yet part of routine practice in renal dialysis units, with a small number of devices (e.g. finger cuffs) having occasionally been used in research settings. In use, patients frequently report pain or discomfort at measurement sites. Additionally, these devices can be unreliable in patients with reduced blood flow to the digits, often manifest in dialysis patients. All existing methods are sensitive to patient movement.A new method for continuously estimating BP has been developed by monitoring arterial pressure near the arteriovenous fistula which can be achieved without any extraneous monitoring equipment attached to the patient. Additionally, artificial intelligence-based methods for real-time prediction of IDH are currently emerging. SUMMARY: Key monitoring technologies and computational methods are emerging to support the development of real-time IDH prediction.

Neural correlates of within-session practice effects in mild motor impairment after stroke: a preliminary investigation.

While the structural integrity of the corticospinal tract (CST) has been shown to support motor performance after stroke, the neural correlates of within-session practice effects are not known. The purpose of this preliminary investigation was to examine the structural brain correlates of within-session practice effects on a functional motor task completed with the more impaired arm after stroke. Eleven individuals with mild motor impairment (mean age 57.0 ± 9.4 years, mean months post-stroke 37.0 ± 66.1, able to move ≥ 26 blocks on the Box and Blocks Test) due to left hemisphere stroke completed structural MRI and practiced a functional motor task that involved spooning beans from a start cup to three distal targets. Performance on the motor task improved with practice (p = 0.004), although response was variable. Baseline motor performance (Block 1) correlated with integrity of the CST (r = - 0.696) while within-session practice effects (change from Block 1 to Block 3) did not. Instead, practice effects correlated with degree of lesion to the superior longitudinal fasciculus (r = 0.606), a pathway that connects frontal and parietal brain regions previously shown to support motor learning. This difference between white matter tracts associated with baseline motor performance and within-session practice effects may have implications for understanding response to motor practice and the application of brain-focused intervention approaches aimed at improving hand function after stroke.

Microbial Find, Inform, and Test Model for Identifying Spatially Distributed Contamination Sources: Framework Foundation and Demonstration of Ruminant Bacteroides Abundance in River Sediments.

Microbial pollution in rivers poses known ecological and health risks, yet causal and mechanistic linkages to sources remain difficult to establish. Host-associated microbial source tracking (MST) markers help to assess the microbial risks by linking hosts to contamination but do not identify the source locations. Land-use regression (LUR) models have been used to screen the source locations using spatial predictors but could be improved by characterizing transport (i.e., hauling, decay overland, and downstream). We introduce the microbial Find, Inform, and Test (FIT) framework, which expands previous LUR approaches and develops novel spatial predictor models to characterize the transported contributions. We applied FIT to characterize the sources of BoBac, a ruminant Bacteroides MST marker, quantified in riverbed sediment samples from Kewaunee County, Wisconsin. A 1 standard deviation increase in contributions from land-applied manure hauled from animal feeding operations (AFOs) was associated with a 77% (p-value <0.05) increase in the relative abundance of ruminant Bacteroides (BoBac-copies-per-16S-rRNA-copies) in the sediment. This is the first work finding an association between the upstream land-applied manure and the offsite bovine-associated fecal markers. These findings have implications for the sediment as a reservoir for microbial pollution associated with AFOs (e.g., pathogens and antibiotic-resistant bacteria). This framework and application advance statistical analysis in MST and water quality modeling more broadly.

Impacts of an Urban Sanitation Intervention on Fecal Indicators and the Prevalence of Human Fecal Contamination in Mozambique.

Fecal source tracking (FST) may be useful to assess pathways of fecal contamination in domestic environments and to estimate the impacts of water, sanitation, and hygiene (WASH) interventions in low-income settings. We measured two nonspecific and two human-associated fecal indicators in water, soil, and surfaces before and after a shared latrine intervention from low-income households in Maputo, Mozambique, participating in the Maputo Sanitation (MapSan) trial. Up to a quarter of households were impacted by human fecal contamination, but trends were unaffected by improvements to shared sanitation facilities. The intervention reduced Escherichia coli gene concentrations in soil but did not impact culturable E. coli or the prevalence of human FST markers in a difference-in-differences analysis. Using a novel Bayesian hierarchical modeling approach to account for human marker diagnostic sensitivity and specificity, we revealed a high amount of uncertainty associated with human FST measurements and intervention effect estimates. The field of microbial source tracking would benefit from adding measures of diagnostic accuracy to better interpret findings, particularly when FST analyses convey insufficient information for robust inference. With improved measures, FST could help identify dominant pathways of human and animal fecal contamination in communities and guide the implementation of effective interventions to safeguard health.

Impact of an Urban Sanitation Intervention on Enteric Pathogen Detection in Soils.

Environmental fecal contamination is common in many low-income cities, contributing to a high burden of enteric infections and associated negative sequelae. To evaluate the impact of a shared onsite sanitation intervention in Maputo, Mozambique on enteric pathogens in the domestic environment, we collected 179 soil samples at shared latrine entrances from intervention (n = 49) and control (n = 51) compounds during baseline (preintervention) and after 24 months (postintervention) as part of the Maputo Sanitation Trial. We tested soils for the presence of nucleic acids associated with 18 enteric pathogens using a multiplex reverse transcription qPCR platform. We detected at least one pathogen-associated gene target in 91% (163/179) of soils and a median of 3 (IQR = 1, 5) pathogens. Using a difference-in-difference analysis and adjusting for compound population, visibly wet soil, sun exposure, wealth, temperature, animal presence, and visible feces, we estimate the intervention reduced the probability of detecting ≥1 pathogen gene by 15% (adjusted prevalence ratio, aPR = 0.85; 95% CI: 0.70, 1.0) and the total number of pathogens by 35% (aPR = 0.65; 0.44, 0.95) in soil 24 months following the intervention. These results suggest that the intervention reduced the presence of some fecal contamination in the domestic environment, but pathogen detection remained prevalent 24 months following the introduction of new latrines.

Getting ahead of antibiotic-resistant Staphylococcus aureus in U.S. hogs.

Antibiotic-resistant strains of Staphylococcus aureus, an opportunistic bacterial pathogen, have emerged in industrial livestock operations and agricultural settings. In the United States, there is limited access to industrial livestock operations and farm-level antibiotic use data. As a result, studies often rely on retail meat as a proxy for direct animal sampling. To move beyond this limitation and assess S. aureus colonization in hogs, we purchased the heads of recently-slaughtered hogs and compared S. aureus populations in those raised on industrial hog operations versus those raised without antibiotics. S. aureus isolates were analyzed for antibiotic resistance and putative genotypic markers of livestock adaptation. Although methicillin-resistant S. aureus (MRSA) was not detected in this study, all of the hogs from industrial hog operations (n = 9/9) carried multidrug-resistant S. aureus (MDRSA) with two livestock-adaptation markers (scn-negative and clonal complex (CC) 9 or 398) compared to 11% of hogs raised without antibiotics (n = 1/9). Hogs from industrial operations were 9.0 times (95% confidence interval (CI): 1.4-57.1) as likely to carry livestock-adapted S. aureus and 4.5 times (95% CI: 1.3-15.3) as likely to carry MDRSA as hogs raised without antibiotics. In contrast, the majority of antibiotic-free hogs (67%, n = 6/9) contained human-adapted S. aureus (i.e. scn-positive, CC1) compared to 11% (n = 1/9) of IHO hogs. These results indicate that antibiotic use in IHO hogs may make them more conducive hosts to antibiotic-resistant, livestock-adapted S. aureus strains when compared to hogs raised without antibiotics. Our results are important, as they provide strong evidence that antibiotic use practices influence the S. aureus populations carried by U.S. hogs, supporting the need for increased access to routine monitoring of hog operations for antibiotic resistance management using a One Health framework.

Chitosan Coagulation Pretreatment to Enhance Ceramic Water Filtration for Household Water Treatment.

Viruses are major contributors to the annual 1.3 million deaths associated with the global burden of diarrheal disease morbidity and mortality. While household-level water treatment technologies reduce diarrheal illness, the majority of filtration technologies are ineffective in removing viruses due to their small size relative to filter pore size. In order to meet the WHO health-based tolerable risk target of 10-6 Disability Adjusted Life Years per person per year, a drinking water filter must achieve a 5 Log10 virus reduction. Ceramic pot water filters manufactured in developing countries typically achieve less than 1 Log10 virus reductions. In order to overcome the shortfall in virus removal efficiency in household water treatment filtration, we (1) evaluated the capacity of chitosan acetate and chitosan lactate, as a cationic coagulant pretreatment combined with ceramic water filtration to remove lab cultured and sewage derived viruses and bacteria in drinking waters, (2) optimized treatment conditions in waters of varying quality and (3) evaluated long-term continuous treatment over a 10-week experiment in surface waters. For each test condition, bacteria and virus concentrations were enumerated by culture methods for influent, controls, and treated effluent after chitosan pretreatment and ceramic water filtration. A > 5 Log10 reduction was achieved in treated effluent for E.coli, C. perfringens, sewage derived E. coli and total coliforms, MS2 coliphage, Qß coliphage, ΦX174 coliphage, and sewage derived F+ and somatic coliphages.

Microorganisms in the Placenta: Links to Early-Life Inflammation and Neurodevelopment in Children.

Prenatal exposure to various stressors can influence both early and later life childhood health. Microbial infection of the intrauterine environment, specifically within the placenta, has been associated with deleterious birth outcomes, such as preterm birth, as well as adverse neurological outcomes later in life. The relationships among microorganisms in the placenta, placental function, and fetal development are not well understood. Microorganisms have been associated with perinatal inflammatory responses that have the potential for disrupting fetal brain development. Microbial presence has also been associated with epigenetic modifications in the placenta, as well other tissues. Here we review research detailing the presence of microorganisms in the placenta and associations among such microorganisms, placental DNA methylation, perinatal inflammation, and neurodevelopmental outcomes.

Test-retest reliability and minimal detectable change of corticospinal tract integrity in chronic stroke.

Diffusion tensor imaging (DTI) can be used to index white matter integrity of the corticospinal tract (CST) after stroke; however, the psychometric properties of DTI-based measures of white matter integrity are unknown. The purpose of this study was to examine test-retest reliability as determined by intraclass correlation coefficients (ICC) and calculate minimal detectable change (MDC) of DTI-based measures of CST integrity using three different approaches: a Cerebral Peduncle approach, a Probabilistic Tract approach, and a Tract Template approach. Eighteen participants with chronic stroke underwent DTI on the same magnetic resonance imaging scanner 4 days apart. For the Cerebral Peduncle approach, a researcher hand drew masks at the cerebral peduncle. For the Probabilistic Tract approach, tractography was seeded in motor areas of the cortex to the cerebral peduncle. For the Tract Template approach, a standard CST template was transformed into native space. For all approaches, the researcher performing analyses was blind to participant number and day of data collection. All three approaches had good to excellent test-retest reliability for fractional anisotropy (FA; ICCs >0.786). Mean diffusivity, axial diffusivity, and radial diffusivity were less reliable than FA. The ICC values were highest and MDC values were the smallest for the most automated approach (Tract Template), followed by the combined manual/automated approach (Probabilistic Tract) then the manual approach (Cerebral Peduncle). The results of this study may have implications for how DTI-based measures of CST integrity are used to define impairment, predict outcomes, and interpret change after stroke.

Measuring Environmental Exposure to Enteric Pathogens in Low-Income Settings: Review and Recommendations of an Interdisciplinary Working Group.

Infections with enteric pathogens impose a heavy disease burden, especially among young children in low-income countries. Recent findings from randomized controlled trials of water, sanitation, and hygiene interventions have raised questions about current methods for assessing environmental exposure to enteric pathogens. Approaches for estimating sources and doses of exposure suffer from a number of shortcomings, including reliance on imperfect indicators of fecal contamination instead of actual pathogens and estimating exposure indirectly from imprecise measurements of pathogens in the environment and human interaction therewith. These shortcomings limit the potential for effective surveillance of exposures, identification of important sources and modes of transmission, and evaluation of the effectiveness of interventions. In this review, we summarize current and emerging approaches used to characterize enteric pathogen hazards in different environmental media as well as human interaction with those media (external measures of exposure), and review methods that measure human infection with enteric pathogens as a proxy for past exposure (internal measures of exposure). We draw from lessons learned in other areas of environmental health to highlight how external and internal measures of exposure can be used to more comprehensively assess exposure. We conclude by recommending strategies for advancing enteric pathogen exposure assessments.