Disturbance of the human gut microbiota in patients with Myotonic Dystrophy type 1.

Myotonic dystrophy type 1 (DM1) is a rare autosomal dominant genetic disorder. Although DM1 is primarily characterized by progressive muscular weakness, it exhibits many multisystemic manifestations, such as cognitive deficits, cardiac conduction abnormalities, and cataracts, as well as endocrine and reproductive issues. Additionally, the gastrointestinal (GI) tract is frequently affected, encompassing the entire digestive tract. However, the underlying causes of these GI symptoms remain uncertain, whether it is biomechanical problems of the intestine, involvement of bacterial communities, or both. The primary objective of this study is to investigate the structural changes in the gut microbiome of DM1 patients. To achieve this purpose, 35 patients with DM1 were recruited from the DM-Scope registry of the neuromuscular clinic in the Saguenay-Lac-St-Jean region of the province of Québec, Canada. Stool samples from these 35 patients, including 15 paired samples with family members living with them as controls, were collected. Subsequently, these samples were sequenced by 16S MiSeq and were analyzed with DADA2 to generate taxonomic signatures. Our analysis revealed that the DM1 status correlated with changes in gut bacterial community. Notably, there were differences in the relative abundance of Bacteroidota, Euryarchaeota, Fusobacteriota, and Cyanobacteria Phyla compared to healthy controls. However, no significant shift in gut microbiome community structure was observed between DM1 phenotypes. These findings provide valuable insights into how the gut bacterial community, in conjunction with biomechanical factors, could potentially influence the gastrointestinal tract of DM1 patients.

MyotonPro Is a Valid Device for Assessing Wrist Biomechanical Stiffness in Healthy Young Adults.

Background: The MyotonPro is a portable device for measuring biomechanical and viscoelastic properties in superficial soft tissues. The aims of this study are firstly to validate the MyotonPro compared to a reliable gold-standard frame and secondly to observe the influence of MyotonPro measurement on the total wrist viscoelasticity. Methods: Three silicone polymers with different elastic properties were assessed with the MyotonPro and with a reference rheometer (Universal Tribometer Mod). Then, a free oscillations method was used to measure the passive elastic and viscous stiffness of the wrist and compared to MyotonPro forearm measurements. Results: A one-way ANOVA demonstrated the validity of the MyotonPro's stiffness (p = 0.001), decrement (p < 0.001), and relaxation (p = 0.008) parameters for measuring the elastic stiffness (k) of the three polymers. The MyotonPro parameters demonstrated excellent reliability on the forearm. Proximal and distal anterior myofascial measurements of the MyotonPro were moderately correlated to the elastic stiffness (p = 0.0027-0.0275, absolute r = from 0.270 to 0.375) of the wrist while the postero-distal myofascial tissues of the forearm demonstrated a moderate correlation with the viscous stiffness of the wrist (p = 0.0096-0.0433, absolute r = from 0.257 to 0.326). Discussion: The MyotonPro is a valid device for measuring elastic stiffness as well as a portable, affordable, and easy-to-use tool for quantifying the biomechanical properties and viscoelasticity of myofascial tissue in healthy subjects.

Haptic Devices Based on Real-Time Dynamic Models of Multibody Systems.

Multibody modeling of mechanical systems can be applied to various applications. Human-in-the-loop interfaces represent a growing research field, for which increasingly more devices include a dynamic multibody model to emulate the system physics in real-time. In this scope, reliable and highly dynamic sensors, to both validate those models and to measure in real-time the physical system behavior, have become crucial. In this paper, a multibody modeling approach in relative coordinates is proposed, based on symbolic equations of the physical system. The model is running in a ROS environment, which interacts with sensors and actuators. Two real-time applications with haptic feedback are presented: a piano key and a car simulator. In the present work, several sensors are used to characterize and validate the multibody model, but also to measure the system kinematics and dynamics within the human-in-the-loop process, and to ultimately validate the haptic device behavior. Experimental results for both developed devices confirm the interest of an embedded multibody model to enhance the haptic feedback performances. Besides, model parameters variations during the experiments illustrate the infinite possibilities that such model-based configurable haptic devices can offer.

A multibody-based approach to the computation of spine intervertebral motions in scoliotic patients.

In idiopathic scoliotic patients, dynamical intervertebral efforts acting between vertebrae seem to be correlated with the spinal deformity. The quantification of these efforts, which is useful for the orthopedic surgeons to set up their surgical planning is the final objective of the present research. As a first step, we focus in this contribution on the geometrical reconstruction of the spine and especially on the rotation sequences between vertebrae in a multibody approach. The reconstruction process is performed in the standing position with possible bending, using an optimization process based on geometrical data reconstructed from radiographs. The obtained results will serve as input for the subsequent gait motion for which the limited set of geometrical information must be compensated.

Lombo-sacral joint efforts during gait: comparison between healthy and scoliotic subjects.

INTRODUCTION: The internal efforts in the human body in motion could provide valuable information for the evaluation and follow-up of subjects with musculo-skeletal pathologies, such as scoliosis, but are still difficult to accurately measure. In this context, the objective of this study is to compare the lombo-sacral (L5-S1) joint efforts during gait (i.e.: mediolateral forces, mediolateral torques, and anteroposterior torques) between typically developed adolescents (TDA) and adolescents with left lumbar or thoracolumbar idiopathic scoliosis (AIS), categorized by their Cobb angle (CA). MATERIAL AND METHODS: 12 TDA, 10 AIS with CA < 20°, 13 AIS with CA between 20° and 40° as well as 16 AIS in preoperative condition performed gait at 4 km/h on instrumented treadmill. Among the latter group, 8 AIS were evaluated after surgical intervention (participants with at least a diminution of 30° of their CA). The acquisition system measured the human body joint motion via optokinetic sensors, and the ground reaction forces via a treadmill fitted with force sensors. The L5-S1 intervertebral efforts were calculated using a tridimensional inverse dynamical model of the human body. RESULTS: The mediolateral forces were significantly higher for AIS with CA between 20° and 40° and for AIS in pre-operative condition compared to TDA values. But neither mediolateral nor anteroposterior torque was significantly different between groups. After surgical intervention the maximal anteroposterior torque was significantly lower compared to pre-surgical value. CONCLUSION: The participants with severe idiopathic scoliosis present higher L5-S1 mediolateral forces than TDA, which could lead to a supplementary asymmetric vertebra growth modulation and the progression of the scoliotic deformities in the framework of the Hueter-Volkman principle. Further research should include the tridimensional reconstruction of the spine in order to observe differences between categories of AIS patients in terms of dynamical behaviors along the spine.

Quantification of global intervertebral torques during gait: comparison between two subjects with different scoliosis severities.

The internal forces in the human body in motion could provide valuable information for the evaluation and follow-up of subjects with musculo-skeletal pathologies, such as scoliosis, but are still difficult to accurately measure. In this context, the objective of this study is to quantify the global intervertebral torques along the spine during walking, in order to compare the dynamical behavior between two subjects with different scoliosis severities. Practically, two patients, both with left lumbar adolescent idiopathic scoliosis (lumbar Cobb angles: 40 degrees), but with different apical axial rotations (20 degrees and 30 degrees) and different thoracic Cobb angles (20 degrees and 30 degrees), walked on a treadmill at 4 km/h. The acquisition system included optokinetic sensors (reflective markers), recording the 3D-joint coordinates, and a treadmill equipped with strain gauges, measuring the external forces independently applied to both feet. The global intervertebral torques were computed using an inverse dynamic model of the human body in 3D. As results, significant differences of the subject kinematics and ground reaction forces were recorded, which lead to different internal torque behavior in magnitude, maxima and minima when normalized to the subject mass. In conclusion in this preliminary study, different dynamical behavior was found between two subjects with different scoliosis severities, suggesting that the scoliosis severity could be affected by abnormal internal torques along the spine during gait (different than in the standing posture), which could lead to a supplementary asymmetric growth modulation of the vertebrae and the further progression of the scoliotic deformities in the framework of the Hueter-Volkman principle. Finally, this is a pilot study and the results will inform future studies and biomechanical modeling.