Afferents to Action: Cortical Proprioceptive Processing Assessed with Corticokinematic Coherence Specifically Relates to Gross Motor Skills.

Voluntary motor control is thought to be predicated on the ability to efficiently integrate and process somatosensory afferent information. However, current approaches in the field of motor control have not factored in objective markers of how the brain tracks incoming somatosensory information. Here, we asked whether motor performance relates to such markers obtained with an analysis of the coupling between peripheral kinematics and cortical oscillations during continuous movements, best known as corticokinematic coherence (CKC). Motor performance was evaluated by measuring both gross and fine motor skills using the Box and Blocks Test (BBT) and the Purdue Pegboard Test (PPT), respectively, and with a biomechanics measure of coordination. A total of 61 participants completed the BBT, while equipped with electroencephalography and electromyography, and the PPT. We evaluated CKC, from the signals collected during the BBT, as the coherence between movement rhythmicity and brain activity, and coordination as the cross-correlation between muscle activity. CKC at movements' first harmonic was positively associated with BBT scores (r = 0.41, p = 0.001), and alone showed no relationship with PPT scores (r = 0.07, p = 0.60), but in synergy with BBT scores, participants with lower PPT scores had higher CKC than expected based on their BBT score. Coordination was not associated with motor performance or CKC (p > 0.05). These findings demonstrate that cortical somatosensory processing in the form of strengthened brain-peripheral coupling is specifically associated with better gross motor skills and thus may be considered as a valuable addition to classical tests of proprioception acuity.

Temporally stable beta sensorimotor oscillations and corticomuscular coupling underlie force steadiness.

As humans, we seamlessly hold objects in our hands, and may even lose consciousness of these objects. This phenomenon raises the unsettled question of the involvement of the cerebral cortex, the core area for voluntary motor control, in dynamically maintaining steady muscle force. To address this issue, we measured magnetoencephalographic brain activity from healthy adults who maintained a steady pinch grip. Using a novel analysis approach, we uncovered fine-grained temporal modulations in the beta sensorimotor brain rhythm and its coupling with muscle activity, with respect to several aspects of muscle force (rate of increase/decrease or plateauing high/low). These modulations preceded changes in force features by ∼40 ms and possessed behavioral relevance, as less salient or absent modulation predicted a more stable force output. These findings have consequences for the existing theories regarding the functional role of cortico-muscular coupling, and suggest that steady muscle contractions are characterized by a stable rather than fluttering involvement of the sensorimotor cortex.

Engineering gene overlaps to sustain genetic constructs in vivo.

Evolution is often an obstacle to the engineering of stable biological systems due to the selection of mutations inactivating costly gene circuits. Gene overlaps induce important constraints on sequences and their evolution. We show that these constraints can be harnessed to increase the stability of costly genes by purging loss-of-function mutations. We combine computational and synthetic biology approaches to rationally design an overlapping reading frame expressing an essential gene within an existing gene to protect. Our algorithm succeeded in creating overlapping reading frames in 80% of E. coli genes. Experimentally, scoring mutations in both genes of such overlapping construct, we found that a significant fraction of mutations impacting the gene to protect have a deleterious effect on the essential gene. Such an overlap thus protects a costly gene from removal by natural selection by associating the benefit of this removal with a larger or even lethal cost. In our synthetic constructs, the overlap converts many of the possible mutants into evolutionary dead-ends, reducing the evolutionary potential of the system and thus increasing its stability over time.

Clinical Walking Tests and Gait Pattern Characterization During 6-Minute Walk Test Using Inertial Sensors: Follow-Up in Individuals With Lower Limb Amputation.

Inertial measurement units and normative values enable clinicians to quantify clinical walking tests and set rehabilitation goals. Objectives of this study were (1) to compare time- and distance-based walking tests in individuals with lower limb amputation (iLLA) and normative values following rehabilitation discharge (T1) and 6 weeks after discharge (T2) and (2) to investigate spatiotemporal and foot kinematic parameters over a 6-minute walk test using inertial measurement units. Twelve iLLA participated in this study. Distance, cadence, stance ratio, loading rate ratio, push-up ratio, path length, and minimum toe clearance were analyzed during 6-minute walk test. Nonparametric repeated-measures analysis of variance tests, Bonferroni corrections, were performed. Time of distance-based walking tests diminished at T2 (P < .02). Compared with normative values, walking performance in iLLA was reduced. Cadence at T2 increased significantly (P = .026). Stance ratio increased in both legs at T2 (P < .05). Push-up ratio tended to decrease at T2 in the amputated leg (P = .0003). Variability of path length and minimum toe clearance at T2 were less than at T1 in the nonamputated leg (P < .05). Spatiotemporal improvement at T2 could be due to prosthesis adaptation in iLLA. The lower performance of the functional walk test compared with normative values could be due to amputation and pain-related fatigue.

Assessment of biomechanical deficits in individuals with a trans-tibial amputation during level gait using one-dimensional statistical parametric mapping.

BACKGROUND: Most previous studies reported biomechanical deficits in individuals with a trans-tibial amputation (TTA) during gait using zero-dimensional analyses. However, these analyses do not allow to precisely determine during which part of the gait cycle these deficits occur. There is a need to use more appropriate methods to map the differences, such as one-dimensional statistical parametric mapping. RESEARCH QUESTION: What are the most relevant phases of the gait cycle during which the biomechanical deficits in TTA occur? METHODS: Eight TTA and 15 healthy counterparts (CON) underwent one biomechanical gait analysis. Pelvis, hip, knee and ankle kinematics, total support moment (TSM) and gastrocnemius lateralis, vastus lateralis and tibialis anterior muscle activity were compared between the amputated (AmLL), the intact (InLL) and the control (CnLL) lower limbs using one-dimensional statistical parametric mapping. RESULTS: More ankle dorsiflexion and knee flexion were observed for the AmLL compared to the InLL and CnLL (ankle only) from the end of the stance phase to the beginning of the swing phase. Less knee flexion was also found for the AmLL during early stance phase. More pelvis posterior tilt and rotation toward the contralateral limb was observed during most of the gait cycle for the AmLL compared to the InLL. TSM was smaller for the AmLL compared to the CnLL during early stance phase. SIGNIFICANCE: Using a one-dimensional statistical parametric mapping approach for TTA gait analysis, this study provides novel insights on their biomechanical gait deficits compared to CON. Greater reliance on the InLL was observed in TTA as suggested by the asymmetric kinematic and kinetic profiles.

Droplet printing reveals the importance of micron-scale structure for bacterial ecology.

Bacteria often live in diverse communities where the spatial arrangement of strains and species is considered critical for their ecology. However, a test of this hypothesis requires manipulation at the fine scales at which spatial structure naturally occurs. Here we develop a droplet-based printing method to arrange bacterial genotypes across a sub-millimetre array. We print strains of the gut bacterium Escherichia coli that naturally compete with one another using protein toxins. Our experiments reveal that toxin-producing strains largely eliminate susceptible non-producers when genotypes are well-mixed. However, printing strains side-by-side creates an ecological refuge where susceptible strains can persist in large numbers. Moving to competitions between toxin producers reveals that spatial structure can make the difference between one strain winning and mutual destruction. Finally, we print different potential barriers between competing strains to understand how ecological refuges form, which shows that cells closest to a toxin producer mop up the toxin and protect their clonemates. Our work provides a method to generate customised bacterial communities with defined spatial distributions, and reveals that micron-scale changes in these distributions can drive major shifts in ecology.

Six-Minute Walk Test in Individuals With Unilateral Lower Limb Amputations.

BACKGROUND: The 6-minute walk test (6MWT) is one of the common clinical tests to assess rehabilitation progress and needs in individuals with lower-limb amputation (iLLAs). However, the analysis of this test is mostly limited to the distance parameter. The first aim was to investigate effort intensity and spatiotemporal parameters of 6MWT in iLLAs using inertial measurement units (IMUs) and heart rate (HR) monitor, and second, to assess physical, physiological, and pain-related aspects of fatigue over 6MWT. METHODS: Eleven unilateral iLLAs (57.91±15.63 years old) participated in this study. To evaluate HR and spatiotemporal parameters over 6MWT, data were classified using 6 intervals of 1 minute each (I1-I6). The pain level of participants was estimated using the visual analog scale (VAS). RESULTS: Our results showed that the means of normalized HR gradually increased over 6MWT (I1: 61.59±10.73 HRmax%, I6: 70.15±12.26 HRmax%, P = .003). Variability of HR during the first interval of 6MWT was higher than the others (P < .05). The stance ratio of the gait cycle increased over 6MWT (P < .05). Cadence and speed decreased over 6MWT (P < .05). VAS score after 6MWT was significantly higher than before 6MWT (P = .016). CONCLUSION: In this preliminary study, effort intensity over 6MWT gradually increased because of enhancement of HR. Deterioration of speed and cadence and enhancement of stance ratio over 6MWT imply potential physical aspects of fatigue and instability. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

The impact of body-mass index on the frontal knee alignment estimation using three-dimensional reconstruction based on movement analysis.

BACKGROUND: We evaluated the influence of the body-mass index (BMI) on the estimation of the static frontal knee alignment (FKA) using three-dimensional (3D) reconstruction method based on movement analysis. METHODS: Two-hundred nineteen knees (120 individuals with end-stage osteoarthritis) were analyzed. The validity of the 3D method was evaluated under comparison with a reference method based on weight bearing full-leg length radiography. Extensive statistical analyses (Pearson's correlation, one-way ANOVA, linear regression, boxplot diagram) over four groups of BMI (normal, overweight, obese class I and obese classes II and III) were performed. RESULTS: For BMI below 25 kg/m2, the validity of the 3D method was confirmed. For BMI over 25 kg/m2, there was an increasing error of the 3D method, especially for the obese groups affected with a large varus alignment. CONCLUSIONS: In a biomechanical context of movement analysis, the results of the study suggest that the 3D method may represent a satisfying alternative to the full-leg radiograph method with limitations regarding to BMI over 25 kg/m2.

The Evolution and Ecology of Bacterial Warfare.

Bacteria have evolved a wide range of mechanisms to harm and kill their competitors, including chemical, mechanical and biological weapons. Here we review the incredible diversity of bacterial weapon systems, which comprise antibiotics, toxic proteins, mechanical weapons that stab and pierce, viruses, and more. The evolution of bacterial weapons is shaped by many factors, including cell density and nutrient abundance, and how strains are arranged in space. Bacteria also employ a diverse range of combat behaviours, including pre-emptive attacks, suicidal attacks, and reciprocation (tit-for-tat). However, why bacteria carry so many weapons, and why they are so often used, remains poorly understood. By comparison with animals, we argue that the way that bacteria live - often in dense and genetically diverse communities - is likely to be key to their aggression as it encourages them to dig in and fight alongside their clonemates. The intensity of bacterial aggression is such that it can strongly affect communities, via complex coevolutionary and eco-evolutionary dynamics, which influence species over space and time. Bacterial warfare is a fascinating topic for ecology and evolution, as well as one of increasing relevance. Understanding how bacteria win wars is important for the goal of manipulating the human microbiome and other important microbial systems.

The effect of partners' education on women's reproductive and maternal health in developing countries.

The effect of partners' education on women's and children's health in developing countries has received relatively little attention to date. This study uses couple data from 37 recent Demographic and Health Surveys fielded in sub-Saharan African and Asian countries to assess the effect of partners' schooling on women's modern contraceptive use, frequency of antenatal care visits, and skilled birth attendance. Using multilevel logistic regressions, the study shows that partners' schooling has strong effects on their spouses' maternal healthcare utilization; especially when partners had secondary or higher levels of schooling. Overall, women whose partners had an above secondary level of education were 32% more likely to use modern contraceptives, 43% more likely to attend at least four antenatal care visits, and 55% more likely to deliver their most recent baby with a health professional, compared to women whose partner had no education, after controlling for individual and community-level covariates. Finally, interacting the partners' years of schooling, we found that an additional year of partners' schooling was 1) positively associated with modern contraceptive use when the women had low educational attainment (substitution effect), but negatively associated when women were better educated, 2) positively and increasingly associated with the frequency of antenatal care visits as women's education increased (multiplicative effect), and 3) positively and significantly associated with skilled birth attendance for less educated women (substitution effect). This study highlights the importance of male education in shaping their wife's health behaviours in developing countries and provides strong impetus for male education beyond primary level (as well as for women), something that has been neglected in past policy discourse.

A gait retraining system using augmented-reality to modify footprint parameters: Effects on lower-limb sagittal-plane kinematics.

Improving lower-limb flexion/extension angles during walking is important for the treatment of numerous pathologies. Currently, these gait retraining procedures are mostly qualitative, often based on visual assessment and oral instructions. This study aimed to propose an alternative method combining motion capture and display of target footprints on the floor. The second objectives were to determine the error in footprint modifications and the effects of footprint modifications on lower-limb flexion/extension angles. An augmented-reality system made of an optoelectronic motion capture device and video projectors displaying target footprints on the floor was designed. 10 young healthy subjects performed a series of 27 trials, consisting of increased and decreased amplitudes in stride length, step width and foot progression angle. 11 standard features were used to describe and compare lower-limb flexion/extension angles among footprint modifications. Subjects became accustomed to walk on target footprints in less than 10 min, with mean (± SD) precision of 0.020 ±â€¯0.002 m in stride length, 0.022 ±â€¯0.006 m in step width, and 2.7 ±â€¯0.6° in progression angle. Modifying stride length had significant effects on 3/3 hip, 2/4 knee and 4/4 ankle features. Similarly, step width and progression angle modifications affected 2/3 and 1/3 hip, 2/4 and 1/4 knee as well as 3/4 and 2/4 ankle features, respectively. In conclusion, this study introduced an augmented-reality method allowing healthy subjects to modify their footprint parameters rapidly and precisely. Walking with modified footprints changed lower-limb sagittal-plane kinematics. Further research is needed to design rehabilitation protocols for specific pathologies.

Multi-segment analysis of spinal kinematics during sit-to-stand in patients with chronic low back pain.

While alterations in spinal kinematics have been frequently reported in patients with chronic low back pain (CLBP), a better characterization of the kinematics during functional activities is needed to improve our understanding and therapeutic solutions for this condition. Recent studies on healthy subjects showed the value of analyzing the spine during sit-to-stand transition (STST) using multi-segment models, suggesting that additional knowledge could be gained by conducting similar assessments in CLBP patients. The objectives of this study were to characterize three dimensional kinematics at the lower lumbar (LLS), upper lumbar (ULS), lower thoracic (LTS) and upper thoracic (UTS) joints during STST, and to test the hypothesis that CLBP patients perform this movement with smaller angle and angular velocity compared to asymptomatic controls. Ten CLBP patients (with minimal to moderate disability) and 11 asymptomatic controls with comparable demographics (52% male, 37.4±5.6 years old, 22.5±2.8kg/m(2)) were tested using a three-dimensional camera-based system following previously proposed protocols. Characteristic patterns of movement were identified at the LLS, ULS and UTS joints in the sagittal plane only. Significant differences in the form of smaller sagittal-plane angle and smaller angular velocity in the patient group compared to the control group were observed at these three joints. This indicated a more rigid spine in the patient group and suggested that CLBP rehabilitation could potentially be enhanced by targeting movement deficits in functional activities. The results further recommended the analysis of STST kinematics using a pelvis-lumbar-thoracic model including lower and upper lumbar and thoracic segments.

Fertility Limitation and Child Schooling in Ouagadougou: Selective Fertility or Resource Dilution?

Using original data collected in Ouagadougou, Burkina Faso, this study investigates evidence for the competing theories that fertility reductions increase children's education through either the quantity-quality tradeoff (intentionally choosing smaller families to make greater investments in education and other indicators of child quality) or resource dilution (having more children reduces resources available per child, regardless of intentionality of family size). The results provide evidence for both hypotheses: children having four or fewer siblings were significantly more likely to be enrolled in school if their mothers had intentionally stopped childbearing relative to those whose mothers wanted more children but whose childbearing was limited by subfecundity. The difference between intentional and unintentional family limitation was not significant for parities greater than five. In addition, the relationship between number of siblings and their schooling is negative, regardless of the intentionality of family-size limitation, but the strength of this negative relationship is approximately twice as high among children whose mothers intentionally limited fertility (reflecting both selection and dilution effects) than among children whose mothers were subfecund (reflecting the pure dilution effect).

Environmental factors and childhood Fever in areas of the Ouagadougou Health and Demographic Surveillance System, Burkina Faso.

Using data on 825 under-5 children from the Ouagadougou Health and Demographic Surveillance System collected in 2010, this article examines the effects of aspects of the immediate environment on childhood fever. Logit regression models were estimated to assess the effects of the quality of the local environment on the probability that a child is reported to have had a fever in the two weeks preceding the survey, after controlling for various demographic and socioeconomic variables. While the estimated impact of some environmental factors persisted in the full models, the effects of variables such as access to water and type of household waste management decreased in the presence of demographic, socioeconomic and neighbourhood factors. The management of waste water was found to significantly affect the occurrence of childhood fever. Overall, the results of the study call for more efforts to promote access to tap water to households at prices that are affordable for the local population, where the threats to child health appears to be greatest.

Fertility decline and child schooling in urban settings of Burkina Faso.

As evidenced in Western rich countries, Asia, and Latin America, lower fertility allows couples to invest more in each of their children's schooling. This postulate is the key rationale of family planning policies in sub-Saharan Africa. Yet, most studies on Africa have found no correlation or even a positive relationship between the number of children in a family and their educational attainment. These mixed results are usually explained by African family solidarity and resource transfers that might reduce pressures on household resources occasioned by many births as well as methodological problems that have afflicted much research on the region. Our study aims to assess the impact of family size on children's schooling in Ouagadougou (capital of Burkina Faso), using a better measure of household budget constraints and taking into account the simultaneity of fertility and schooling decisions. In contrast to most prior studies on sub-Saharan Africa, we find a net negative effect of sibship size on the level of schooling achieved by children--one that grows stronger as they progress through the educational system.

Gender inequality and the use of maternal healthcare services in rural sub-Saharan Africa.

In this study, we measure gender inequality both at individual level by women׳s household decision-making and at contextual level by permissive gender norms associated with tolerance of violence against women and assess their impact on maternal healthcare services utilisation in rural Africa. We apply multilevel structural equation modelling to Demographic and Health Survey (DHS) data from Ghana, Kenya, Tanzania and Uganda to gain better measure and effect of the gender norms construct. The results show that women in Ghana and Uganda, who live in areas where gender norms are relatively tolerant of violence against women, are less likely to use skilled birth attendants and timely antenatal care. In Tanzania, women who live in this type of environment are less likely to attend four or more antenatal visits. In contrast, the effects of a woman׳s decision-making authority on maternal health service use are less pronounced in the same countries.

Does antenatal care matter in the use of skilled birth attendance in rural Africa: a multi-country analysis.

While the importance of antenatal care for maternal and child health continues to be debated, several researchers have documented its impact on intermediate variables affecting survival such as birth weight. These studies have also highlighted the problems of causality that are typically not taken into account when estimating the effects of antenatal care on skilled birth attendance. In this study, we revisit this relation in the rural areas of four countries: Ghana, Kenya, Uganda and Tanzania. Using a structural equation modeling approach that corrects for endogeneity, in all four countries we find that the usual simpler probit (or logit) models tend to underestimate the direct effect of antenatal care on skilled birth attendance. Furthermore, in two of the countries, this estimated effect is mediated by the range of services offered to women during antenatal care. These results suggest that governments and NGOs should place more importance on the role of antenatal care providers and on the services they offer, in efforts to promote skilled birth attendance.

Why are virgin adolescents worried about contracting HIV/AIDS? Evidence from four sub-Saharan African countries.

Whether well founded or not, perceptions of one's own HIV risk have been shown by health behavior models to be an important factor in determining individuals' sexual behavior. Although empirical studies on the determinants of HIV risk perception exist, only a few have focused on adolescents who are not yet sexually active. Using data from nationally-representative surveys of adolescents, we assess the factors associated with HIV risk perception among sexually inactive adolescents in four sub-Saharan African countries at different stages of the HIV/AIDS epidemic (Burkina Faso, Ghana, Malawi and Uganda). The results show that there is no single influence on adolescents' HIV risk perception, but rather a range of individual, environmental and community factors such as schooling, knowledge about HIV, regional HIV prevalence and adolescents' social networks. These results can help better calibrate programs and policies addressing sexual and reproductive health issues among adolescents, a group that is disproportionately affected by new HIV infections.

Innate immune recognition of flagellin limits systemic persistence of Brucella.

Brucella are facultative intracellular bacteria that cause chronic infections by limiting innate immune recognition. It is currently unknown whether Brucella FliC flagellin, the monomeric subunit of flagellar filament, is sensed by the host during infection. Here, we used two mutants of Brucella melitensis, either lacking or overexpressing flagellin, to show that FliC hinders bacterial replication in vivo. The use of cells and mice genetically deficient for different components of inflammasomes suggested that FliC was a target of the cytosolic innate immune receptor NLRC4 in vivo but not in macrophages in vitro where the response to FliC was nevertheless dependent on the cytosolic adaptor ASC, therefore suggesting a new pathway of cytosolic flagellin sensing. However, our work also suggested that the lack of TLR5 activity of Brucella flagellin and the regulation of its synthesis and/or delivery into host cells are both part of the stealthy strategy of Brucella towards the innate immune system. Nevertheless, as a flagellin-deficient mutant of B. melitensis wasfound to cause histologically demonstrable injuries in the spleen of infected mice, we suggested that recognition of FliC plays a role in the immunological stand-off between Brucella and its host, which is characterized by a persistent infection with limited inflammatory pathology.

Association between age at first sexual relation and some indicators of sexual behaviour among adolescents.

This study explores the relationship between age at first sexual intercourse and four indicators of sexual behaviour among adolescents aged 14 to 19 years in Burkina Faso, Malawi and Uganda. Analyses are conducted using data from National Surveys of Adolescents, organized in 2004. Multivariate analyses are performed using dichotomous logistic regression and ordered polychotomic logistic regression. Analyses show that initiation of sexual activity before age 14 is more likely to be associated with having a casual sex partner. It is less likely to be associated with condom use at first sexual relation or with systematic condom use in the past 12 months. These associations vary depending on adolescents' country and gender. Delaying onset of sexuality could be a surer and safer way to protect health during adolescence. However, sexual and reproductive health programs that advocate abstinence only are likely to have few positive effects on young people. To better implement this strategy, sexual education for adolescents should be integrated.