Biology subjects

Huber, M. E.

Publications and source records attributed to Huber, M. E..

15 recordsLinked to original sources

bioRxiv2026

ThermoClock: A Novel Automated Temperature Regulation Device that Can Model Circadian Entrainment and Disruption in 2D and 3D in Vitro Models

Circadian rhythms are critical for maintaining homeostasis and regulating physiological functions, and consequentially impact disease progression; yet, they remain largely overlooked in in vitro models used in preclinical research. One major barrier to rigorously testing the role of circadian rhythms in these models is the lack of accessible tools that seamlessly integrate into standard culture setups and are capable of sustainably delivering time cues to cells and tissues in long term experiments. Here, we present the ThermoClock, a low-cost, Arduino-based automated temperature control system capable of delivering independent temperature programs to multiple cultures simultaneously. Using circadian reporter U2OS cell lines (Bmal1:Luc and Per2:Luc), we demonstrated that ThermoClock-driven temperature cycles (36{degrees}C/38.5{degrees}C, 12h:12h) produced significantly higher amplitude entrainment than a programmable incubator delivering identical temperature trajectories, suggesting that the ramp time to setpoint is a critical determinant of entrainment strength. We further applied ThermoClock to skin explants from keratinocyte-specific Dbp:Luc reporter mice, showing that circadian temperature cycles (T24: 12h:12h and T25: 12.5h:12.5h) extended synchronized circadian rhythms ex vivo, while a shortened T-cycle (T20: 10h:10h) induced rhythm disruptions. We also observed reduced cell migration in T20 temperature-entrained explants wounded ex vivo, closely recapitulating attenuated wound healing observed in T20 light-cycle-disrupted mice in vivo. Finally, we show that wounding can act as a phase-resetting cue but its efficacy depends on pre-injury entrainment state, with circadian entrained tissues (T25) resisting reset, while disrupted (T20) and unentrained tissues showed resetting sensitivity. These findings establish ThermoClock as a versatile platform for incorporating circadian regulation and, for the first time, disruption into 2D and 3D in vitro systems and demonstrate that peripheral clock disruption and its functional consequences can be modeled ex vivo.

bioengineering↗

bioRxiv2026

Perceiving latent dynamics: Innate and coachable visual estimation of limb damping

Humans are remarkably adept at extracting latent dynamic information from purely visual cues. Prior work shows that people can innately estimate differences in limb stiffness using solely their visual observation of movement, which suggests that components of mechanical impedance may be embedded within humans internal predictive models of movement. We tested whether humans can similarly perceive damping, a force-velocity relationship, and whether targeted coaching can enhance this visual ability. Specifically, 30 participants observed abstract two-link arm simulations with systematically varied elbow damping and rated their perceived level of damping for several trials. Participants completed two sessions separated by one of three brief coaching interventions: (1) no coaching, (2) coaching to attend to hand velocity, or (3) coaching to attend to elbow-angle velocity. Results reveal that (1) humans can innately perceive changes in arm damping using solely their visual observation of motion and (2) coaching further improved performance, with the elbow-angle coaching group showing a significantly greater increase in rating accuracy compared to the other two groups. This work extends our understanding of how action-perception coupling supports inference of mechanical impedance. Moreover, we demonstrated that perceptual strategies for estimating damping are malleable and can be systematically improved through coaching. We not only identified the visual cues observers relied on but also guided them toward more classifiable features, effectively strengthening their perceptual models of limb dynamics. Author summaryHumans are remarkably adept at understanding an objects latent dynamic properties simply by watching it move, even when the underlying forces are unseen. In this paper, we demonstrated that people can notice differences in how "damped" a moving limb is using vision alone. Moreover, we found that brief coaching helped participants focus on the most informative features, significantly improving their ability to differentiate the damping levels. These results demonstrate how people can visually infer aspects of movement that are normally thought to require physical interaction, offering insight into how the motor system links action and perception. They also show that strategies can be shaped and improved, supporting real-world healthcare applications. In stroke rehabilitation, physical therapists physically assess the resistance of a patients limb, so better guidance on the most relevant visual cues can help clinicians learn faster and even provide care remotely. In robot-assisted surgery, surgeons operate a console to perform procedures with limited or no force feedback, so they must estimate tissue dynamics properties largely from visual observation. Understanding how people visually estimate these dynamics can inform training for more precise surgical decisions. Overall, our findings clarify how humans interpret movement dynamics and how coaching can support more consistent and accurate perceptual decisions.

neuroscience↗

bioRxiv2025

Gait adaptation to asymmetric foot-ground compliance applied by robotic footwear

Perturbing foot-ground interaction dynamics has shown promise for eliciting adaptations to inter-limb weight-bearing symmetry, a critical target for rehabilitation of asymmetrical neuromotor deficits affecting gait. To date, this perturbation paradigm has been delivered via adjustable stiffness treadmills, in which the treadmill deck displaces under the walkers foot during the stance phase of gait. Recently, we developed robotic footwear capable of delivering asymmetrical ground stiffness perturbations during walking, offering a portable experimental platform for asymmetrical ground stiffness perturbations, allowing it to be executed overground and on conventional treadmills. In this study, we quantified kinetic and spatio-temporal gait adaptation to a foot-ground compliance perturbation delivered by the novel robotic footwear. We found that participants shifted their vertical ground reaction force impulse, vertical pushoff peak, and peak braking force toward the unperturbed limb after the perturbation was removed, indicating a shift in neuromotor control elicited by the perturbation. We conclude that the robotic footwear can elicit weight bearing adaptations similar to adjustable stiffness treadmills, and that the dissipative mechanical properties of the shoes likely play a key role in the direction of the adaptation.

neuroscience↗

bioRxiv2025

Weight-bearing symmetry changes after asymmetric surface stiffness walking

Stroke is a leading cause of adult disability in the United States, often presenting as hemiparesis. A priority in hemiparetic gait rehabilitation is the restoration of gait symmetry. While split belt treadmill training has shown promise in correcting spatial gait asymmetry, weight bearing and propulsion asymmetry remain resistant to improvement. As an alternative approach, we tested asymmetric surface stiffness walking to induce signatures of neuromotor adaptation relevant to correcting weight bearing and propulsion asymmetries in hemiparetic stroke. We hypothesized that a bout of asymmetric stiffness walking would elicit aftereffects in the form of asymmetries in weight bearing, propulsion, and plantar flexor activity. Twelve healthy young adults performed a 10-minute bout of asymmetric stiffness walking on an adjustable stiffness treadmill. We measured baseline and post-perturbation ground reaction forces (GRF) and spatio-temporal measures during 5-minute walking bouts on a dual-belt instrumented treadmill. After asymmetric surface stiffness walking, participants walked with increased vertical GRF and plantar flexor muscle excitations during push-off on the perturbed side relative to unperturbed. Participants also decreased their mid-stance vertical GRF and increased their peak braking GRF on the perturbed side relative to unperturbed. Counter to our hypothesis, they did not increase their propulsion GRF on the perturbed side. We conclude that asymmetric stiffness walking elicited a neuromotor adaptation towards a relative increase in push-off in the target limb, albeit primarily vertically aligned in our cohort of healthy young adults, and that gait adaptation to asymmetric stiffness walking should be investigated in individuals with push-off asymmetries. New & NoteworthyWeight-bearing asymmetry in individuals with hemiparetic stroke is resistant to treatments that produce improvements in other gait function measures (e.g., spatio-temporal symmetry). We investigated a novel perturbed ground stiffness intervention applied by an adjustable surface stiffness treadmill and found significant aftereffects in vertical and braking ground reaction force peaks in healthy young adults, as well as increases in perturbed-side plantar flexor activity during push-off, indicating a strong potential for correcting persistent deficiencies in post-stroke gait.

neuroscience↗

bioRxiv2025

Adjustable Compliance Footwear Technology to Investigate Gait Adaptation

Kinetic asymmetries in gait caused by neurological impairments are a major factor in mobility deficiency. Gait perturbation training has shown promise for rehabilitating neurological gait asymmetry, but the transfer of benefits from treadmill training to overground walking is limited. To enable kinetic gait perturbation training on treadmills and overground, we developed novel adjustable compliance footwear technology. The system consists of a wearable pneumatic actuation module which controls the pressure of custom air pockets embedded in a soft lattice midsole, and is capable of independently and wirelessly adjusting the midsole compliance under each foot from 300 kN/m and 60% energy absorption to 18 kN/m and 75% energy absorption in under 4 seconds. Hindfoot and forefoot sole deflection data are measured via Hall effect sensors and paired magnets characterized to 1.7 mm accuracy. To demonstrate the experimental capability of the system, we successfully triggered multiple compliance changes during overground walking and recorded ground reaction forces and embedded sensor values during a prolonged asymmetric compliance walking bout on a treadmill. Future work will include a full experimental study of gait adaptation to asymmetric footwear compliance perturbations.

bioengineering↗

bioRxiv2025

IFNγ regulates MR1 transcription and antigen presentation

Antigen presentation molecules play key roles in activating T cell immunity. Multiple complementary pathways are known to regulate classical MHC-I molecules at transcriptional, translational, and post-translational levels. Intracellular trafficking mechanisms dictating post-transcriptional regulation of MR1, the MHC Class I-like molecule which restricts MAIT cells, have been an area of focus; however, little is known about MR1 transcriptional regulation. We demonstrate that, similar to classical MHC-I, interferons regulate MR1 transcription. Treatment of airway epithelial cells (AEC) with recombinant IFN{beta} or IFN{gamma} variably increased MR1 transcripts, while only IFN{gamma} significantly increased surface MR1 expression and enhanced antigen presentation to MAIT cells. The MR1 promoter contains binding motifs for interferon regulatory factor 1 (IRF1), an important MHC-I transcription factor. IRF1 knockout reduced IFN{gamma}-stimulated MR1 transcription, surface expression, and antigen presentation. Conversely, knockout of Nod-like Receptor family CARD domain containing 5 (NLRC5), a critical component of IFN{gamma}-induced MHC-I transcription, did not significantly impact MR1 expression. These findings were corroborated in primary human AEC treated with IFN{gamma}. In co-culture experiments, MAIT cells incubated with Streptococcus pneumoniae-infected primary AEC produced sufficient IFN{gamma} to stimulate upregulation of MR1 expression. Our data support a model where IFN{gamma} from activated MAIT cells or another source stimulates IRF1-dependent MR1 expression and antigen presentation, leading to greater MAIT cell activation. A robust MR1-dependent MAIT cell response may be beneficial for early infection responses, allowing minimal antigen stimulus to generate greater proinflammatory activity.

immunology↗

bioRxiv2024

Forward Simulations of Walking on Surfaces with Asymmetric Mechanical Impedance: Insights for Gait Rehabilitation

Gait asymmetry, prevalent in stroke survivors and various other neurological and musculoskeletal conditions, leads to abnormal joint loading, increased fall risk, and reduced walking efficiency. Traditional rehabilitation methods often fail to consistently reduce weight-bearing gait asymmetry, necessitating innovative approaches. This study explores the potential of an adjustable mechanical impedance treadmill to amplify weight-bearing asymmetries, leveraging the "error amplification" technique akin to split-belt treadmill training. We developed a 2D optimal control gait model in OpenSim to simulate walking on a rigid platform with one leg and a compliant platform, with adjustable stiffness and damping, with the other. We simulated 112 unique mechanical impedance conditions of the compliant platform and analyzed the effects of these conditions on stance time, ground reaction forces (GRFs), and muscle activations. Our results identified specific impedance parameters that can be utilized to amplify propulsion asymmetries, providing a potential new approach for gait rehabilitation post-stroke. Future work should validate these results in experimental settings and further explore optimal impedance parameters for effective gait therapy of various gait impairments.

bioengineering↗

bioRxiv2024

A fluorescent probe enables the discovery of improved antagonists targeting the intracellular allosteric site of the chemokine receptor CCR7

Intracellularly acting ligands of G protein-coupled receptors (GPCRs) are gaining significant interest in GPCR drug discovery. In this study, we report the development of the fluorescent ligand Mz437 (4) targeting the CC chemokine receptor CCR7 at an intracellular allosteric site. We demonstrate its experimental power by applying 4 to identify two improved intracellular CCR7 antagonists, SLW131 (10) and SLW132 (21m), developed by converting two weakly active antagonists into single- or double-digit nanomolar ligands with minimal modifications. The thiadiazoledioxide 10 was derived from the CCR7 antagonist Cmp2105 by removing a methyl group from the benzamide moiety, while the squaramide 21m was obtained from the CXCR1/CXCR2 antagonist and clinical candidate navarixin by replacing the ethyl substituent by a tert-butyl group to engage a lipophilic subpocket. We show that 10 and 21m qualify to probe CCR7 biology both in recombinant cells and in the endogenous signaling environment of immune cells. Our novel probes are expected to facilitate the design of next-generation intracellular CCR7 ligands and serve as molecular tools to interrogate CCR7 biology in human and murine endogenous settings. Entry for the Table of Contents O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=109 SRC="FIGDIR/small/607356v1_ufig1.gif" ALT="Figure 1"> View larger version (59K): org.highwire.dtl.DTLVardef@1298d55org.highwire.dtl.DTLVardef@fdebf2org.highwire.dtl.DTLVardef@8d9aecorg.highwire.dtl.DTLVardef@b6308d_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗

bioRxiv2024

AdjuSST: An Adjustable Surface Stiffness Treadmill

Humans have the remarkable ability to manage foot-ground interaction seamlessly across terrain changes despite the high dynamic complexity of the task. Understanding how adaptation in the neuromotor system enables this level of robustness in the face of changing interaction dynamics is critical for developing more effective gait retraining interventions. We developed an adjustable surface stiffness treadmill (AdjuSST) to trigger these adaptation mechanisms and enable studies to better understand human adaptation to changing foot-ground dynamics. The AdjuSST system makes use of fundamental beam-bending principles; it controls surface stiffness by controlling the effective length of a cantilever beam. The beam acts as a spring suspension for the transverse endpoint load applied through the treadmill. The system is capable of enforcing a stiffness range of 15-300kN/m within 340 ms, deflecting linearly downwards up to 10 cm, and comfortably accommodating two full steps of travel along the belt. AdjuSST offers significant enhancements in effective walking surface length compared to similar systems, while also maintaining a useful stiffness range and responsive spring suspension. These improvements enhance our ability to study locomotor control and adaptation to changes in surface stiffness, as well as provide new avenues for gait rehabilitation.

bioengineering↗

bioRxiv2023

Gait adaptation to asymmetric hip stiffness applied by a robotic exoskeleton

Wearable exoskeletons show significant potential for improving gait impairments, such as interlimb asymmetry. However, a more profound understanding of whether exoskeletons are capable of eliciting neural adaptation is needed. This study aimed to characterize how individuals adapt to bilateral asymmetric joint stiffness applied by a hip exoskeleton, similar to split-belt treadmill training. Thirteen unimpaired individuals performed a walking trial on the treadmill while wearing the exoskeleton. The right side of the exoskeleton acted as a positive stiffness torsional spring, pulling the thigh towards the neutral standing position, while the left acted as a negative stiffness spring pulling the thigh away from the neutral standing position. The results showed that this intervention applied by a hip exoskeleton elicited adaptation in spatiotemporal and kinetic gait measures similar to split-belt treadmill training. These results demonstrate the potential of the proposed intervention for retraining symmetric gait.

neuroscience↗

bioRxiv2023

Bilateral asymmetric hip stiffness applied by a robotic hip exoskeleton elicits kinematic and kinetic adaptation

Wearable robotic exoskeletons hold great promise for gait rehabilitation as portable, accessible tools. However, a better understanding of the potential for exoskeletons to elicit neural adaptation--a critical component of neurological gait rehabilitation--is needed. In this study, we investigated whether humans adapt to bilateral asymmetric stiffness perturbations applied by a hip exoskeleton, taking inspiration from asymmetry augmentation strategies used in split-belt treadmill training. During walking, we applied torques about the hip joints to repel the thigh away from a neutral position on the left side and attract the thigh toward a neutral position on the right side. Six participants performed an adaptation walking trial on a treadmill while wearing the exoskeleton. The exoskeleton elicited time-varying changes and aftereffects in step length and propulsive/braking ground reaction forces, indicating behavioral signatures of neural adaptation. These responses resemble typical responses to split-belt treadmill training, suggesting that the proposed intervention with a robotic hip exoskeleton may be an effective approach to (re)training symmetric gait.

neuroscience↗

bioRxiv2022

Minimum effort simulations of split-belt treadmill walking exploit asymmetry to reduce metabolic energy expenditure

Walking on a split-belt treadmill elicits an adaptation response that changes the baseline step length asymmetry of the walker. The underlying causes of this adaptation, however, are difficult to determine. It has been proposed that effort minimization may drive this adaptation, based on the idea that adopting longer steps on the fast belt, or positive step length asymmetry (SLA), can cause the treadmill to exert net-positive mechanical work on a bipedal walker. However, humans walking on split-belt treadmills have not been observed to reproduce this behavior when allowed to freely adapt. To determine if an energy minimization motor control strategy would result in experimentally observed adaptation patterns, we conducted simulations of walking on different combinations of belt speeds with a human musculoskeletal model which minimized muscle effort. The model adopted increasing amounts of positive step length asymmetry and decreased its net metabolic rate with increasing belt speed asymmetry, up to +25.6% SLA and -14.3% metabolic rate at a 3:1 belt speed ratio, relative to tied-belt walking. These gains were primarily enabled by an increase of braking work and a reduction of propulsion work on the fast belt. The results suggest that a purely energy minimization driven split belt walking strategy would involve substantial positive SLA, and that the lack of this characteristic in human behavior points to additional factors influencing the motor control strategy, such as aversion to excessive joint loads, asymmetry, or instability. New & NoteworthyBehavioral observations of split-belt treadmill adaptation have been inconclusive toward its underlying causes. To estimate gait patterns when driven exclusively by one of these possible causes, we simulated split-belt walking with a musculoskeletal model which minimized its energy cost. Our model took significantly longer steps on the fast belt and reduced its metabolic rate below tied-belt walking, unlike experimental observations. This suggests that asymmetry is energetically optimal, but human adaptation involves additional factors.

neuroscience↗

bioRxiv2022

Chronic obstructive pulmonary disease and cigarette smoke exposure lead to dysregulated MAIT cell activation by bronchial epithelial cells

Chronic obstructive pulmonary disease (COPD) is associated with airway inflammation, increased infiltration by CD8+ T lymphocytes, and infection-driven exacerbations. COPD is most commonly caused by cigarette smoke (CS), however the mechanisms driving development of COPD in some smokers but not others are incompletely understood. Lung-resident mucosal-associated invariant T (MAIT) cells play a role in both microbial infections and inflammatory diseases. MAIT cell frequency is reduced in the peripheral blood of individuals with COPD, however the role of MAIT cells in COPD pathology is unknown. Here, we examined MAIT cell activation in response to CS-exposed primary human bronchial epithelial cells (BEC) from healthy, COPD, or smoker donors. We observed significantly higher MAIT cell responses to COPD BEC than healthy BEC. However, COPD BEC stimulated a smaller fold-increase in MAIT cell response despite increased microbial infection. For all donor groups, CS-exposed BEC elicited reduced MAIT cell responses; conversely, CS exposure increased ligand-mediated MR1 surface translocation in healthy and COPD BEC. Our data demonstrate MAIT cell activation is dysregulated in the context of CS and COPD. MAIT cells could contribute to CS- and COPD-associated inflammation through both inappropriate activation and reduced early recognition of bacterial infection, contributing to microbial persistence and COPD exacerbations.

immunology↗

bioRxiv2021

Forward simulations of walking on a variable surface-impedance treadmill: A comparison of two methods

Recent experiments with a variable stiffness tread-mill (VST) suggest that modulating foot-ground contact dynamics during walking may offer an effective new paradigm for gait rehabilitation. How gait adapts to extended perturbations of asymmetrical surface stiffness is still an open question. In this study, we simulated human gait with prolonged asymmetrical changes in ground stiffness using two methods: (1) forward simulation of a muscle-reflex model and (2) optimal control via direct collocation. Simulation results showed that both models could competently describe the biomechanical trends observed in human experiments with a VST which altered the walking surface stiffness for one step. In addition, the simulations revealed important considerations for future experiments studying the effect of asymmetric ground stiffness on gait behavior. With the muscle-reflex model, we observed that although subtle, there was a difference between gait biomechanics before and after the prolonged asymmetric stiffness perturbation, showing the behavioral signature of an aftereffect despite the lack of supraspinal control in the model. In addition, the optimal control simulations showed that damping has a large effect on the overall lower-body muscle activity, with the muscle effort cost function used to optimize the biomechanics increasing 203% between 5 Ns/m and 2000 Ns/m at a stiffness of 10 kN/m. Overall, these findings point to new insights and considerations for advancing our understanding of human neuromotor control of locomotion and enhancing robot-aided gait rehabilitation.

neuroscience↗

bioRxiv2019

Rigid Foot Soles Improve Balance in Beam Walking

Maintaining balance while walking on a narrow beam is a challenging motor task. This is presumably because the foots ability to exert torque on the support surface is limited by the beam width. Still, the feet serve as a critical interface between the body and the external environment, and it is unclear how the mechanical properties of the feet affect balance. Here we examined how restricting the degrees of freedom of the feet influenced balance behavior during beam walking. We recorded whole-body joint kinematics of subjects with varying skill levels as they walked on a narrow beam with and without wearing flat, rigid soles on their feet. We computed changes in whole-body motion and angular momentum across these conditions. Results showed that wearing rigid soles improved balance in the beam walking task, but that practice with rigid soles did not affect or transfer to task performance with bare feet. The absence of any after-effect suggested that the improved balance from constraining the foot was the result of a mechanical effect rather than a change in neural strategy. Though wearing rigid soles can be used to assist balance, there appear to be limited training or rehabilitation benefits from wearing rigid soles.

neuroscience↗