Biology subjects

Sartori, M.

Publications and source records attributed to Sartori, M..

10 recordsLinked to original sources

bioRxiv2026

MyoAssist 1.0: An Open-Source Framework for Neuromechanical Simulation of Physical Human-Device Interaction

Physical human-device interaction is central to many emerging technologies in neurorehabilitation and assistive robotics, but simulation-based research in this area remains fragmented across musculoskeletal models, assistive-device representations, task definitions, and controller-development workflows. This fragmentation limits the accessibility, reproducibility, and extensibility of studies on prostheses, exoskeletons, wearable rehabilitation devices, and related human-device systems. Here we introduce MyoAssist 1.0, an open-source framework for neuromechanical simulation of physical human-device interaction built within the MyoSuite ecosystem. MyoAssist organizes each simulation environment as a composed human-device-task system that combines compatible musculoskeletal, assistive-device, and task-scenario components through a shared composition pipeline. The current release includes 15 assistive-device models spanning gait assistance, upper-body support, manipulation, and seated mobility and supports compatible musculoskeletal models ranging from reduced lower-limb models to a 416-muscle full-body model. These human-device systems can be simulated within the broad task scenarios provided by MyoSuite, while MyoAssist adds locomotion-specific task scenarios with configurable terrain and target-velocity conditions for gait-assistive studies. MyoAssist also provides two complementary controller-development frameworks: a reinforcement-learning framework for training adaptive policies and a controller-optimization framework for tuning structured, interpretable human and device controllers. Both frameworks operate on the same simulation environments and provide standardized evaluation outputs for inspecting, comparing, reusing, and extending learned and structured control strategies. By integrating modular human models, assistive-device models, task scenarios, and training workflows under a shared open-source interface, MyoAssist aims to lower the barrier to reproducible simulation-based research and to support collaborative development of assistive technologies for neurorehabilitation and physical human-device interaction.

bioengineering↗

bioRxiv2026

Experiment-free learning of exoskeleton assistance remains an unsolved problem

In "Experiment-free exoskeleton assistance via learning in simulation", Luo et al. [1] present an ambitious framework for developing exoskeleton controllers through reinforcement learning exclusively in computer simulation. The authors report that a control policy trained on a small dataset from one subject was directly transferred to physical hardware, reducing human metabolic cost during walking, running, and stair climbing by more than any prior device. If confirmed, this would represent a major breakthrough for the field of wearable robotics and their clinical applications. However, a close examination of the published materials casts doubt on these claims. The reported experimental results violate physiological limits on the relationship between mechanical power and muscle energy use during gait2,3,4. The algorithmic claims are surprising and cannot be verified; in contrast with established replicability standards in machine learning5,6, executable code has not been made available. We conclude that the goals of this study have not yet been verifiably achieved and make recommendations for avoiding publication errors of this type in the future.

physiology↗

bioRxiv2025

Long-Term Functional 3D Human Skeletal Muscle Constructs from Human Induced Pluripotent Stem Cells Enable Electrically Controlled Remodelling Studies

Studying skeletal muscle remodelling across large temporal scales is difficult because most 3D tissue-engineered skeletal muscle (3D-TESM) models cannot sustain stable development over prolonged culture. Skeletal muscle adaptations in vivo are strongly influenced by changes in tissue length, but most TESM models are mechanically restrictive, limiting elongation and thereby constraining structural remodelling. The stiffness of the pillars that anchor the tissues is a key determinant of how much they can shorten or elongate during development, thereby shaping both their morphology and force-generating capacity. To address this limitation, we investigated how TESMs derived from human induced pluripotent stem cells (hiPSCs) develop over two weeks when suspended between pillars with distinct mechanical properties, ranging from mechanically compliant to mechanically stiff boundary conditions. We focused on both passive and active force-generating properties. With compliant pillars, tissues compacted primarily along their length (~66% reduction), followed by progressive elongation (~50% increase) from day 5 onward. In contrast, with stiff pillars, tissues compacted across their width, with no longitudinal shortening. Despite these morphological differences, projected tissue area decreased similarly across setups. Spontaneous contractions emerged from day 7 and continued until day 14, typically occurring in bursts at 0.6-0.8 Hz. Passive force peaked early with compliant pillars and declined thereafter, while remaining relatively stable with stiff pillars. Under stepwise electrical stimulation, maximal contractility wasconsistently observed at ~50 Hz. Active force rose sharply between day 12 and day 14, with the steepest increase (up to 2000%) in compliant pillars. Although sample size was limited, the consistency of trends across stiffness conditions and surface treatments provides valuable insights into how boundary mechanics shape 3D-TESM development. These findings offer a foundation for designing next-generation muscle culture systems that support dynamic remodelling, force maturation, and training-responsive behaviours. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=95 SRC="FIGDIR/small/672872v2_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@4caa3borg.highwire.dtl.DTLVardef@13c421dorg.highwire.dtl.DTLVardef@11881a1org.highwire.dtl.DTLVardef@1e673a4_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2025

Functional effects of deforestation on stream ecosystems in Madagascar based on growth and production of mayflies (Ephemeroptera)

The effects of deforestation on species richness and abundance of tropical freshwater organisms are increasingly well documented, but corresponding effects on functional properties of ecosystems, such as productivity and growth, are largely unknown. Here we investigated the biomass production and growth of eight species of mayflies (Ephemeroptera) in streams of eastern Madagascar. We compared three study sites in primary tropical forest with three in degraded open canopy area (savoka). All species were asynchronous and aseasonal. Seven species were multivoltine (3-4 generations per year) and one was semi-voltine. Biomass production of the most abundant species was 4-5 times greater in savoka than in forest, and standing biomass: productivity (P/B) was always higher in savoka. This production shift was mainly caused by the two Xyrodromeus species, both of which feed on periphytic algae that are more abundant in an open canopy. Surprisingly, Xyrodromeus females emerged more rapidly and were larger in size in savoka than in forest. Our results clearly indicate that deforestation in tropical Madagascar leads not only to a shift in mayfly community composition, but perhaps more importantly to functional changes in the ecosystem, namely standing biomass, annual production, and female size at maturity.

ecology↗

bioRxiv2024

Towards Wearable Electromyography for Personalized Musculoskeletal Trunk Models using an Inverse Synergy-based Approach

Electromyography (EMG)-driven musculoskeletal models (EMS) of the trunk are used for estimating lumbosacral joint moments and compressive loads during lifting tasks. These models provide personalized estimates of the parameters using information from many sensors. However, to advance technology from labs to workplaces, there is a need for sensor reduction to improve wearability and applicability. Therefore we introduce an EMG sensor reduction approach based on inverse synergy extrapolation, to reconstruct unmeasured EMG signals for different box-lifting techniques. 12 participants performed an array of tasks (squat, stoop, unilateral twist and bilateral twist) with different weights (0 kg, 7.5 kg and 15 kg). We found that two synergies were sufficient to explain the different lifting tasks (median variance accounted for of 0.91). Building upon this, we used two sensors at optimal subject-specific muscle locations to reconstruct the EMG of four unmeasured channels. Evaluation of the reconstructed and reference EMG showed median coefficients of determination (R2) between 0.70 and 0.86, with median root mean squared errors (RMSE) ranging from 0.02 to 0.04 relative to maximal voluntary contraction. This indicates that our proposed method shows promise for sensor reduction for driving a trunk EMS for ambulatory biomechanical risk assessment in occupational settings and exoskeleton control.

bioengineering↗

bioRxiv2024

Predictive Control of Musculotendon Loads Across Fast and Slow-twitch Muscles in a Simulated System with Parallel Actuation

Research in lower limb wearable robotic control have largely focused on reducing the metabolic cost of walking or compensating for a portion of the biological joint torque e.g., by applying support proportional to estimated biological joint torques. However, due to different musculotendon unit (MTU) contractile speed properties, less attention has been given to the development of wearable robotic controllers that can steer MTU dynamics directly. Therefore, closed-loop control of MTU dynamics needs to be robust across fiber phenotypes, i.e. ranging from slow type I to fast type IIx in humans. The ability to closed-loop control the in-vivo dynamics of MTUs, could lead to a new class of wearable robots that can provide precise support to targeted MTUs, for preventing onset of injury or to provide precision rehabilitation to selected damaged tissues. In this paper, we introduce a novel closed-loop control framework that utilizes Nonlinear Model Predictive Control (NMPC) to keep the peak Achilles tendon force within predetermined boundaries during diverse range of cyclic force production simulations in the human ankle plantarflexors. This control framework employs a computationally efficient model comprising a modified Hill-type MTU contraction dynamics component and a model of the ankle joint with parallel actuation. Results indicate that the closed-form muscle-actuation models computational time is in the order of microseconds and is robust to different muscle contraction velocity properties. Furthermore, the controller achieves tendon force control within a timeframe below 14 ms, aligning with the physiological electromechanical delay of the MTU and facilitating its potential for future real-world applications.

bioengineering↗

bioRxiv2021

What ecological factors favor parthenogenesis over sexual reproduction? A study on the facultatively parthenogenetic mayfly Alainites muticus in natural populations.

Different reproductive modes are characterized by costs and benefits which often depend on ecological contexts. Benefits of sex are expected to increase under complex biotic interactions, whereas parthenogenesis can be beneficial for reproductive assurance when females are mate limited. Here, we study how different ecological contexts influence the frequency of sex or parthenogenesis in the facultatively parthenogenetic mayfly Alainites muticus. We first verified that high parthenogenetic frequencies translate into female-biased population sex ratios. We then measured the population sex ratio (a proxy for parthenogenetic capacities), density of individuals (mate limitation) and community diversity (biotic interaction complexity) for 159 A. muticus populations, and used structural equation modeling to investigate their direct and indirect influences on sex ratios. We found no effect of community diversity or altitude on sex ratios. Furthermore, even when females can reproduce parthenogenetically, they generally reproduce sexually, indicating that the benefits of sex exceed its costs in most situations. Sex ratios become female-biased in low population densities, as expected if mate limitation selects for parthenogenesis. Mate limitation might be widespread in mayflies because of their very short adult lifespan and limited dispersal, which can generate strong selection for reproductive assurance and may provide a steppingstone towards obligate parthenogenesis.

evolutionary biology↗

bioRxiv2019

Extremely widespread parthenogenesis and a trade-off between alternative forms of reproduction in mayflies (Ephemeroptera)

Studying alternative forms of reproduction in natural populations is of fundamental importance for understanding the costs and benefits of sex. Mayflies are one of the few animal groups where sexual reproduction co-occurs with different types of parthenogenesis, providing ideal conditions for identifying benefits of sex in natural populations. Here, we establish a catalogue of all known mayfly species capable of reproducing by parthenogenesis, as well as mayfly species unable to do so. Overall, 1.8% of the described species reproduce parthenogenetically, which is an order of magnitude higher than reported in other animal groups. This frequency even reaches 47.8% if estimates are based on the number of studied rather than described mayfly species. In terms of egg-hatching success, sex is a more successful strategy than parthenogenesis, and we found a trade-off between the efficiency of sexual and parthenogenetic reproduction across species. This means that improving the capacity for parthenogenesis may come at the cost of being less able to reproduce sexually, even in facultative parthenogens. Such a trade-off can help explain why facultative parthenogenesis is extremely rare among animals despite its potential to combine the benefits of sexual and parthenogenetic reproduction. We argue that parthenogenesis is frequently selected in mayflies in spite of this probable trade-off because their typically low dispersal ability and short and fragile adult life may frequently generate situations of mate limitation in females. Mayflies are currently clearly underappreciated for understanding the benefits of sex under natural conditions.

evolutionary biology↗

bioRxiv2018

BIN1 recovers tauopathy-induced long-term memory deficits in mice and interacts with Tau through Thr348 phosphorylation

The bridging integrator 1 gene (BIN1) is a major genetic risk factor for Alzheimers disease (AD). In this report, we investigated how BIN1-dependent pathophysiological processes might be associated with Tau. We first generated a cohort of control and transgenic mice either overexpressing human MAPT (TgMAPT) or both human MAPT and BIN1 (TgMAPT;TgBIN1), which we followed-up from 3 to 15 months. In TgMAPT;TgBIN1 mice short-term memory deficits appeared earlier than in TgMAPT mice; however - unlike TgMAPT mice - TgMAPT;TgBIN1 mice did not exhibit any long-term or spatial memory deficits for at least 15 months. After sacrifice of the cohort at 18 months, immunohistochemistry revealed that BIN1 overexpression prevents both Tau mislocalization and somatic inclusion in the hippocampus, where an increase in BIN1-Tau interaction was also observed. We then sought mechanisms controlling the BIN1-Tau interaction. We developed a high-content screening approach to characterize modulators of the BIN1-Tau interaction in an agnostic way (1,126 compounds targeting multiple pathways), and we identified - among others - an inhibitor of Calcineurin, a Ser/Thr phosphatase. We determined that Calcineurin dephosphorylates BIN1 on a Cyclin-dependent kinase phosphorylation site at T348, promoting the open conformation of the neuronal BIN1 isoform. Phosphorylation of this site increases the availability of the BIN1 SH3 domain for Tau interaction, as demonstrated by nuclear magnetic resonance experiments and in primary neurons. Finally, we observed that the levels of the neuronal BIN1 isoform were decreased in AD brains, whereas phospho-BIN1(T348):BIN1 ratio was increased, suggesting a compensatory mechanism. In conclusion, our data support the idea that BIN1 modulates the AD risk through an intricate regulation of its interaction with Tau. Alteration in BIN1 expression or activity may disrupt this regulatory balance with Tau and have direct effects on learning and memory.

neuroscience↗

bioRxiv2018

BIN1 genetic risk factor for Alzheimer is sufficient to induce early structural tract alterations in entorhinal cortex-dentate gyrus pathway and related hippocampal multi-scale impairments

Genetic factors are known to contribute to Late Onset Alzheimers disease (LOAD) but their contribution to pathophysiology, specially to prodomic phases accessible to therapeutic approaches are far to be understood. To translate genetic risk of Alzheimers disease (AD) into mechanistic insight, we generated transgenic mouse lines that express a [~]195 kbp human BAC that includes only BIN1, a gene associated to LOAD. This model gives a modest BIN1 overexpression, dependent of the number of BAC copies. At 6 months of age, we detected impaired entorhinal cortex (EC)-hippocampal pathways with specific impairments in EC-dentate gyrus synaptic long-term potentiation, dendritic spines of granular cells and recognition episodic memory. Structural changes were quantified using MRI. Their whole-brain functional impact were analyzed using resting state fMRI with a hypoconnectivity centered on entorhinal cortex. These early phenotype defects independent of any changes in A-beta can be instrumental in the search for new AD drug targets.

neuroscience↗