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226 result(s) for "Wu, Mengnan"
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American Society of Biomechanics Journal of Biomechanics Award 2018: Adaptive motor planning of center-of-mass trajectory during goal-directed walking in novel environments
To aid in the successful execution of goal-directed walking (discrete movement from a start location to an end target) the central nervous system forms a predictive motor plan. For the motor plan to be effective, it must be adapted in response to environmental changes. Despite motor planning being inherent to goal-directed walking, it is not understood how the nervous system adapts these plans to interact with changing environments. Our objective was to understand how people adapt motor plans of center of mass (COM) trajectory during goal-directed walking in response to a consistent change in environmental dynamics. Participants preformed a series of goal-directed walking trials in a novel environment created by a cable robot that applied a lateral force field to their COM. We hypothesized that participants would adapt to the environment by forming an internal model of their COM trajectory within the force field. Our findings support this hypothesis. Initially, we found COM trajectory significantly deviated in the same direction as the applied field, relative to baseline (no field) (p = 0.002). However, with practice in the field, COM trajectory adapted back to the baseline (p = 0.6). When we unexpectedly removed the field, participants demonstrated after-effects, COM trajectory deviated in the direction opposite of the field relative to baseline (p < 0.001). Our findings suggest that when performing a goal-directed walking task, people adapt a motor plan that predicts the COM trajectory that will emerge from the interaction between a specific set of motor commands and the external environment.
Low-force human–human hand interactions induce gait changes through sensorimotor engagement instead of direct mechanical effects
Physical human–robot interactions (pHRI) often provide mechanical force and power to aid walking without requiring voluntary effort from the human. Alternatively, principles of physical human–human interactions (pHHI) can inspire pHRI that aids walking by engaging human sensorimotor processes. We hypothesize that low-force pHHI can intuitively induce a person to alter their walking through haptic communication. In our experiment, an expert partner dancer influenced novice participants to alter step frequency solely through hand interactions. Without prior instruction, training, or knowledge of the expert’s goal, novices decreased step frequency 29% and increased step frequency 18% based on low forces (< 20 N) at the hand. Power transfer at the hands was 3–700 × smaller than what is necessary to propel locomotion, suggesting that hand interactions did not mechanically constrain the novice’s gait. Instead, the sign/direction of hand forces and power may communicate information about how to alter walking. Finally, the expert modulated her arm effective dynamics to match that of each novice, suggesting a bidirectional haptic communication strategy for pHRI that adapts to the human. Our results provide a framework for developing pHRI at the hand that may be applicable to assistive technology and physical rehabilitation, human-robot manufacturing, physical education, and recreation.
The anti-inflammatory drug Montelukast ameliorates cognitive deficits by rescuing the inflammatory levels in young AD animal models
Neuroinflammation precedes the clinical symptoms onset of Alzheimer’s disease (AD) by decades. However, the anti-inflammatory drugs were not always effective at all stages of the disease. Here, using the fly and mouse AD models, we evaluated the effects of anti-inflammatory drugs on inflammatory-related factors and the proinflammatory cytokines at different ages of AD animals. We also performed behavioral tests to evaluate the cognitive aspects of AD. Combined with the bioinformatics analysis, we would like to exhibit a better understanding of AD. Based on the previous studies and reanalysis of published database, we found aged AD animals might better represent the inflammatory status of symptomatic AD. Our results showed that mRNA levels of antimicrobial peptides (AMPs) were highly expressed in 10-day-old AD flies, while no significant difference was observed in 40-day-old AD. In aged APP/PS1 mice (22.5 months), inflammatory-related factors NF-κB, IBA1, and the mRNA levels of proinflammatory cytokines Il-1β and Il-6 were not differentially expressed. In contrast, a significant increase was observed in 7.5-month-old APP/PS1 mice. Moreover, the anti-inflammatory drug Montelukast (MON) did not ameliorate the inflammatory and cognitive defects in 22.5-month-old aged mice but showed a rescue effect in 7.5-month-old young APP/PS1 mice. Altogether, our study demonstrates the different inflammatory status might lead to variations of anti-inflammatory drug efficacy, which helps to clarify the importance of considering the pathological stage of the disease when administering treatment.
Thermal–Alkaline Etching of SiC Nanoparticles for Colloidal Stabilization and Enhanced Wear Resistance in Electrodeposited Co/SiC Coatings
Composite electrodeposited coatings hold significant potential for marine and aerospace applications due to their synergistic corrosion resistance and wear durability, yet nanoparticle agglomeration and interfacial incompatibility persistently undermine their performance. Conventional dispersion techniques—mechanical agitation, surfactants, or high-energy methods—fail to resolve these issues, often introducing residual stresses, organic impurities, or thermal damage to substrates. This study addresses these challenges through a novel thermal-assisted alkaline etching (TAE) protocol that synergistically removes surface oxides and enhances colloidal stability in β-SiC nanoparticles. By combining NaOH-based etching with low-temperature calcination (250 °C), the method achieves oxide-free SiC surfaces with elevated hydrophilicity and a ζ-potential of −25 mV, enabling submicron clustering (300 nm) without surfactants. Electrodeposited Co/SiC coatings incorporating TAE-SiC exhibited current-modulated reinforcement, achieving optimal SiC incorporation (5.9 at% Si) at 8 A/dm2 through electrophoretic–hydraulic synergy, along with uniform cross-sectional distribution validated by SEM. Tribological assessments revealed shorter wear tracks in TAE-SiC-enhanced coatings compared to their untreated counterparts, suggesting enhanced interfacial coherence despite a comparable mass loss. Demonstrating scalability through cost-effective aqueous-phase chemistry, this methodology provides a generalized framework applicable to other ceramic-reinforced systems (e.g., Al2O3 and TiC), offering transformative potential for next-generation protective coatings in harsh operational environments.
Retraction Note: CT, MRI, and 18F-FDG PET/CT imaging features of seven cases of adult pancreatoblastoma
This article has been retracted. Please see the Retraction Notice for more detail: https://doi.org/10.1186/s12880-022-00958-4
RETRACTED ARTICLE: CT, MRI, and 18F-FDG PET/CT imaging features of seven cases of adult pancreatoblastoma
Objective This study mainly analysed the imaging data for seven cases of adult pancreatoblastoma (PB) and summarized additional imaging features of this disease based on a literature review, aiming to improve the understanding and diagnosis rate of this disease. Materials and methods The imaging data for seven adult patients pathologically diagnosed with adult PB were retrospectively analysed. Among the seven patients, six underwent computed tomography (CT) scans, two patients underwent abdominal magnetic resonance imaging (MRI), and five patients underwent 18 F-FDG PET/CT. Results The tumours were located in the head of the pancreas in three cases, in the tail of the pancreas in two cases, and in the gastric antrum and neck of the pancreas in one case. Six tumours showed blurred edges, and an incomplete envelope was observed in only two cases when enhanced, which showed extruded growth and cyst-solid masses; one tumour was a solid mass with ossification. Showing mild or significant enhancement in the arterial phase (AP) for six cases. In the MRI sequence, isointensity was found on suppressed T1-weighted imaging, and hyperintensity was noted on suppressed T2-weighted imaging in two cases, with significant enhancement. Pancreatic duct dilatation was found in four cases. Tumour 18 F-FDG PET/CT imaging exhibited high uptake in five cases. Conclusion Adult PB involves a single tumour and commonly manifests as cystic-solid masses with blurred edges. Capsules are rare, ossification is an important feature, tumours can also present in ectopic pancreatic tissues, with mild or strengthening in the AP, and 18 F-FDG uptake is high. These features are relatively specific characteristics in adult PB.
General and Specific Strategies Used to Facilitate Locomotor Maneuvers
People make anticipatory changes in gait patterns prior to initiating a rapid change of direction. How they prepare will change based on their knowledge of the maneuver. To investigate specific and general strategies used to facilitate locomotor maneuvers, we manipulated subjects' ability to anticipate the direction of an upcoming lateral \"lane-change\" maneuver. To examine specific anticipatory adjustments, we observed the four steps immediately preceding a maneuver that subjects were instructed to perform at a known time in a known direction. We hypothesized that to facilitate a specific change of direction, subjects would proactively decrease margin of stability in the future direction of travel. Our results support this hypothesis: subjects significantly decreased lateral margin of stability by 69% on the side ipsilateral to the maneuver during only the step immediately preceding the maneuver. This gait adaptation may have improved energetic efficiency and simplified the control of the maneuver. To examine general anticipatory adjustments, we observed the two steps immediately preceding the instant when subjects received information about the direction of the maneuver. When the maneuver direction was unknown, we hypothesized that subjects would make general anticipatory adjustments that would improve their ability to actively initiate a maneuver in multiple directions. This second hypothesis was partially supported as subjects increased step width and stance phase hip flexion during these anticipatory steps. These modifications may have improved subjects' ability to generate forces in multiple directions and maintain equilibrium during the onset and execution of the rapid maneuver. However, adapting these general anticipatory strategies likely incurred an additional energetic cost.
ADNP missense variant p.C687R disrupts chromatin regulation and GABAergic differentiation in Helsmoortel–Van der Aa syndrome
Background Activity-dependent neuroprotective protein (ADNP) is a critical regulator of neurodevelopment, and most pathogenic variants reported in Helsmoortel–Van der Aa syndrome (HVDAS) are truncating variants. In contrast, the functional consequences of ADNP missense variants remain largely unclear. We integrated an ADNP variant cohort in China with variants recorded in the NCBI ClinVar database, revealing a major gap in the interpretation of ADNP missense variants. Methods We investigated a rare de novo ADNP missense variant, p.C687R, predicted to disrupt the ninth zinc finger domain. In vitro, p.C687R was overexpressed in HEK293T cells to assess subnuclear localization by immunofluorescence and chromatin binding patterns using CUT&Tag, with chromatin interactions inferred from published Hi-C datasets. CRISPR/Cas9-mediated ADNP knockout was performed for comparison. In vivo, wild-type ADNP or p.C687R was introduced into the embryonic mouse cortex at E14.5 via in utero electroporation (IUE) and neuronal development was evaluated at E18.5 and P14. Patient-derived induced pluripotent stem cells (iPSCs) from a de novo p.C687R carrier were differentiated into neural progenitor cells (NPCs) and analyzed by multi-omic profiling (RNA-seq, ChIP-seq, ATAC-seq), with lineage-specific markers examined by immunofluorescence. Results p.C687R displays altered subnuclear localization and redistributes wild-type ADNP when overexpressed in HEK293T. IUE in the mouse cortical plate revealed impaired neuronal migration and abnormal cortical arborization. Genome-wide profiling in HEK293T demonstrated a p.C687R-specific chromatin occupancy pattern, preferentially targeting histone modification-related genes. Knockout of ADNP led to upregulation of neuronal genes, including GABAergic lineage-associated genes. In patient-derived iPSCs, a distinct set of neurodevelopmental genes, including key regulators of GABAergic differentiation, showed increased bivalent histone marks (H3K4me3/H3K27me3). Although their promoters remained in an open chromatin state, these genes were transcriptionally silent in pluripotent cells but became more activated upon GABAergic differentiation. Limitations This study is based on a single patient-derived line in combination with complementary experimental models. In the heterozygous endogenous context, distinguishing increased functional activity from dosage-related effects requires further investigation. Replication in additional patient-derived or engineered lines is required to determine the generalizability. Conclusions Our results suggest that p.C687R may exert gain-of-function-like effects in experimental systems and underscore chromatin-mediated regulation of GABAergic lineage genes in HVDAS.
Transplanted deep-layer cortical neuroblasts integrate into host neural circuits and alleviate motor defects in hypoxic-ischemic encephalopathy injured mice
Background Hypoxic-ischemic encephalopathy (HIE) is a major cause of neonatal disability and mortality. Although intensive studies and therapeutic approaches, there are limited restorative treatments till now. Human embryonic stem cell (hESCs)-derived cortical neural progenitors have shown great potentials in ischemic stroke in adult brain. However, it is unclear whether they are feasible for cortical reconstruction in immature brain with hypoxic-ischemic encephalopathy. Methods By using embryonic body (EB) neural differentiation method combined with DAPT pre-treatment and quantitative cell transplantation, human cortical neuroblasts were obtained and transplanted into the cortex of hypoxic-ischemic injured brain with different dosages 2 weeks after surgery. Then, immunostaining, whole-cell patch clamp recordings and behavioral testing were applied to explore the graft survival and proliferation, fate commitment of cortical neuroblasts in vitro, neural circuit reconstruction and the therapeutic effects of cortical neuroblasts in HIE brain. Results Transplantation of human cortical neural progenitor cells (hCNPs) in HIE-injured cortex exhibited long-term graft overgrowth. DAPT pre-treatment successfully synchronized hCNPs from different developmental stages (day 17, day 21, day 28) to deep layer cortical neuroblasts which survived well in HIE injured brain and greatly prevented graft overgrowth after transplantation. Importantly, the cortical neuroblasts primarily differentiated into deep-layer cortical neurons and extended long axons to their projection targets, such as the cortex, striatum, thalamus, and internal capsule in both ipsilateral and contralateral HIE-injured brain. The transplanted cortical neurons established synapses with host cortical neurons and exhibited spontaneous excitatory or inhibitory post-synaptic currents (sEPSCs or sIPSCs) five months post-transplantation. Rotarod and open field tests showed greatly improved animal behavior by intra-cortex transplantation of deep layer cortical neuroblasts in HIE injured brain. Conclusions Transplanted hESCs derived cortical neuroblasts survive, project to endogenous targets, and integrate into host cortical neural circuits to rescue animal behavior in the HIE-injured brain without graft overgrowth, providing a novel and safe cell replacement strategy for the future treatment of HIE.
Comparison of the biometric parameters in patients with high myopia and anisometropia
Background To compare biometric parameters, especially lens parameters, in patients with high myopia and anisometropia. Methods Patients with spherical equivalent greater than -6D and at least one eye with an axial length greater than 26 mm and a difference in binocular axial length greater than 2 mm were included in this study. In each patient, the eye with a relatively shorter axial length was assigned to Group S, and the other eye was assigned to Group L. In patients whose binocular axial length difference was greater than 4 mm, the eye with the shorter axial length was assigned to Group S1 and the other eye was assigned to Group L1. In patients whose shorter eye axial was less than 26 mm, the eye with the shorter axial was assigned to Group S2 and the other eye was assigned to Group L2. Central corneal thickness, corneal curvature radius, axial length, anterior chamber depth, lens thickness, white-to-white corneal diameter and the radius of the anterior and posterior lens capsules were compared between Group S and Group L, Groups S1 and L1, and Groups S2 and L2. Results Sixty-four people were enrolled in the study. There were 26 people with an axial length difference more than 4 mm (Group S1 and Group L1) and 34 patients with an axial length less than 26 mm (Group S2 and Group L2). No significant differences were found in any parameters except axial length between Group S and Group L, Groups S1 and L1, or Groups S2 and L2 ( p  > 0.05). Conclusions The anterior parameters of patients with high myopia did not change with the axial length.