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Kinematic analyses of rodent behavior are frequently used in neuroscience research, and commonly in spinal cord injury (SCI) studies. Unfortunately, skin motion artifact introduces significant errors into these data, because the skin is only loosely coupled to the underlying skeleton by connective tissue. In rats, these errors can be as large as 50-75%,as quantified by past work using x-ray fluoroscopy. Here we show that infrared videography of a subcutaneous tattoo can overcome skin motion artifact in rodent kinematics. The method yields data similar to gold standard x-ray fluoroscopy systems at a fraction of the cost, does not affect the animals’ locomotion, and results in markers that persist for at least 10 weeks. We found that, compared to a gold-standard x-ray fluoroscopy study that directly tracked the skeleton, our method reduced the error in mean hip angle from 17 ± 6.0 to 3.1 ± 2.4 degrees (mean ± SEM), and the root-mean-square (RMS) error across the mean hip angle waveform from 20 to 5.3 degrees (n=4 rats). The knee joint angle waveform derived from infra-red imaging tightly matched the shape of the x-ray waveform after allowing for a constant offset, having RMS error reduced from 8.1 to 1.2 degrees. The method stands to significantly reduce between-animal errors, and hence between laboratory errors, in these ubiquitous model systems, especially important in SCI studies where individuals are assigned to different treatments.

All else being equal, evolution is going to drive animals to require the least food to move a unit distance. What is the best way to do that? Some efficiencies can be 'hard-wired' into the body - the relatively unchanging morphology of the animal. But flexibility is also needed - given the task at hand, state of the body, or state of the external environment, it may be best to dynamically choose an appropriate mode of locomotion. For example, slow walking may be great for searching and foraging, but it won't catch fast moving prey. Similarly, maximum speed gallops may be great for escaping danger, but they preclude eating along the way. This primer summarizes what we know about the determinants of locomotor costs and the strategies animals use to minimize cost. It summarizes key findings across levels of organization, from individual muscles to interactions with other organisms and the environment. At the mid-level of organization we highlight gaits, a particularly interesting topic of inquiry with a rich history. We are in an exciting time for the science of movement because we have more, better tools than ever before for observing and manipulating systems, from the molecular level to herds of animals on the Savannah. Even more importantly, there are so many open, exciting questions to ask.

Aging causes dramatic changes in the locomotion of animals, including the human animal. Treadmill training has been used frequently as a method to improve locomotion and to gather kinematic data that can quantify locomotor ability. Rats are one of the premier models of human disease, in which treadmill locomotion is readily observed and quantified. Several studies have looked at changes in the H-reflex (Caron et al. in Neurobiol Aging 42:61–68, 2016) in old rats, but an in-depth examination of changes in locomotion in old rats has not been a significant focus of past works, despite the utility of such non-invasive data. Here, we investigate changes in the locomotor kinematics of aged rats with treadmill training, over a 4-week treadmill training regime. Our results show that the ankle and knee angles are significantly more flexed on the last day of training compared to the first day. Additionally, we use principal components analysis to find additional features extracted from the kinematics that change across training sessions. Our results suggest that the required training for consistent running at higher speeds for older rats is approximately 3 weeks. We also showed some joint angles were more flexed after training sessions. Thus, future work will build on these results by extracting higher-order features with which to evaluate a treatment for aged animals, by including data from young and old rats that do or do not, receive the treatment.

Locomotion is key to survival, yet it can be disturbed by injuries, diseases, and aging. Therefore, it is important for researchers in biology, neuroscience, biomechanics, and further afield. Locomotion is frequently quantified using kinematic data, and quadrupeds including rodents are medical model animals used worldwide. Kinematics typically result from the tracking of some landmarks, often joint centers. Although commercially available systems and software exist for the analysis of these kinematic data, they are expensive, often restricted to use with a given apparatus, and may be inextensible. Therefore, there is a need for an open source tool to analyze kinematic data. We present a Python software to address this need. It uses 2D coordinates from four cameras and DLT coefficients from the calibrated volume to generates 3D coordinates [1] . A method is presented to modify the knee and elbow joint positions in 3D. Then, kinematic features are extracted, and they are sorted in a time series format to plot a summary of a study. In addition, we generate videos from the tracked points, 3D reconstruction of the points, showing joint angles for eight joints, the location of animal on the belt, and the animal's speed on the belt. The software has been evaluated by eight trials to show the importance of the work. The 3D reconstruction error, having an average of 7.36 pixels, was calculated for the markers. The presented program can be used in different fields. It will encourage the researchers to design the studies based on their needs because they can change the setup in any required conditions while they can extract the kinematic data.

Implanted polymer scaffolds can induce inflammation leading to the foreign body response (FBR), fibrosis, and implant failure. Thus, it is important to understand how immune cells interact with scaffolds to mitigate inflammation and promote a regenerative response. We previously demonstrated that macrophage phenotype is modulated by fiber and pore diameters of an electrospun scaffold. However, it is unclear if this effect is consistent among other innate immune cells. Mast cells are inflammatory sentinels that play a vital role in the FBR of implanted biomaterials, as well as angiogenesis. We determined if altering electrospun scaffold architecture modulates mast cell responses, with the goal of promoting regenerative cell-scaffold interactions. Polydioxanone (PDO) scaffolds were made from 60 mg/mL or 140 mg/mL PDO solutions, yielding structures with divergent fiber and pore diameters. Mouse mast cells plated on these scaffolds were activated with IL-33 or lipopolysaccharide (LPS). Relative to the 60 mg/mL scaffold, 140 mg/mL scaffolds yielded less IL-6 and TNF, and greater VEGF secretion. Pores >4-6 μm elicited less IL-6 and TNF secretion. IL-33-induced VEGF regulation was more complex, showing effects of both pore size and fiber diameter. These data indicate parameters that can predict mast cell responses to scaffolds, informing biomaterial design to increase wound healing and diminish implant rejection. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 884-892, 2019.

Objective H-Reflex is a test that is carried out to measure the relative excitability of reflex pathways. Although reliable, conventional methods consist of performing many small steps, which requires a high level of attentiveness, and thus can carry an elevated risk of human error, despite proper training. Equipment that is available to perform those tests with different levels of automation are typically proprietary, inextensible by the user, and expensive. Here we present a novel MATLAB application that can accurately and reliably perform automated H-Reflex measurements, test the stimulating electrodes, and carry out typical subsequent analyses. Methods This application is a Graphical User Interface that works with inexpensive equipment and offers many important features such as measuring electrode impedance in-situ, automating lengthy measurements like recruitment curves and frequency response trials, standardizing electric stimulation properties, automatic exporting of digital data and metadata, and immediately analyzing acquired data with single-click events. Results Our new method was validated against conventional H-Reflex measurement methods with 2 anesthetized rats. The difference between acquired data using both methods was negligible (mean difference=0.0038; std=0.0121). Our app also detected electrode impedance with high accuracy (94%). Conclusion The method presented here allows reliable and efficient automated H-reflex measurements and can accurately analyze the collected data. Significance The features provided by our app can speed up data collection and reduce human error, and unlike conventional methods, allow the user to analyze data immediately after the record. This can result in higher research quality and give broader access to the technique.

Statins are HMG-CoA reductase inhibitors prescribed for lowering cholesterol. They can also inhibit inflammatory responses by suppressing isoprenylation of small G proteins. Consistent with this, we previously found that fluvastatin suppresses IgE-mediated mast cell function. However, some studies have found that statins induced pro-inflammatory cytokines in macrophages and NK cells. In contrast to IgE signaling, we show that fluvastatin augments IL-33-induced TNF and IL-6 production by mast cells. This effect required the key mast cell growth factor, stem cell factor (SCF). Treatment of IL-33-activated mast cells with mevalonic acid or isoprenoids reduced fluvastatin effects, suggesting fluvastatin acts at least partly by reducing isoprenoid production. Fluvastatin also enhanced IL-33-induced NF-κB transcriptional activity and promoted neutrophilic peritonitis in vivo, a response requiring mast cell activation. Other statins tested did not enhance IL-33 responsiveness. Therefore, this work supports observations of unexpected pro-inflammatory effects of some statins and suggests mechanisms by which this may occur. Because statins are candidates for repurposing in inflammatory disorders, our work emphasizes the importance of understanding the pleiotropic and possible unexpected effects of these drugs.

Spinal cord injury (SCI) often results in life-long sensorimotor impairment. Spontaneous recovery from SCI is limited, as supraspinal fibers cannot spontaneously regenerate to form functional networks below the level of injury. Despite this, animal models and humans exhibit many motor behaviors indicative of recovery when electrical stimulation is applied epidurally to the dorsal aspect of the lumbar spinal cord. In 1976, epidural stimulation was introduced to alleviate spasticity in Multiple Sclerosis. Since then, epidural electrical stimulation (EES) has been demonstrated to improve voluntary mobility across the knee and/or ankle in several SCI patients, highlighting its utility in enhancing motor activation. The mechanisms that EES induces to drive these improvements in sensorimotor function remain largely unknown. In this review, we discuss several sensorimotor plasticity mechanisms that we hypothesize may enable epidural stimulation to promote recovery, including changes in local lumbar circuitry, propriospinal interneurons, and the internal model. Finally, we discuss genetic tools for afferent modulation as an emerging method to facilitate the search for the mechanisms of action.

Bistable spined soft robots enable high-speed cheetah-like galloping and fast-speed swimming, as well as high-force manipulation., Soft machines typically exhibit slow locomotion speed and low manipulation strength because of intrinsic limitations of soft materials. Here, we present a generic design principle that harnesses mechanical instability for a variety of spine-inspired fast and strong soft machines. Unlike most current soft robots that are designed as inherently and unimodally stable, our design leverages tunable snap-through bistability to fully explore the ability of soft robots to rapidly store and release energy within tens of milliseconds. We demonstrate this generic design principle with three high-performance soft machines: High-speed cheetah-like galloping crawlers with locomotion speeds of 2.68 body length/s, high-speed underwater swimmers (0.78 body length/s), and tunable low-to-high-force soft grippers with over 1 to 103 stiffness modulation (maximum load capacity is 11.4 kg). Our study establishes a new generic design paradigm of next-generation high-performance soft robots that are applicable for multifunctionality, different actuation methods, and materials at multiscales.

Background Metal electrodes are a mainstay of neuroscience. Characterization of the electrical impedance properties of these cuffs is important to ensure successful and repeatable fabrication, achieve a target impedance, revise novel designs, and quantify the success or failure of implantation and any potential subsequent damage or encapsulation by scar tissue. New methods Impedances are frequently characterized using lumped-parameter circuit models of the electrode–electrolyte interface. Open-source tools to gather and analyze these frequency sweep data are lacking. Here, we present such software, in the form of Matlab code, which includes a GUI. It automatically acquires frequency sweep data and subsequently fits a simplified Randles model to these data, over a user specified frequency range, providing the user with the model parameter estimates. Also, it can measure an unknown impedance of an element over a range of frequencies, as long as an external resistor can be added for the measurements. Results The tool was tested on five bright platinum nerve cuffs in vitro. The average charge transfer resistance, solution resistance, CPE value, and impedance magnitude were estimated. Comparison to existing methods The measured values of the impedance of cuffs were in agreement with the literature ( Wei and Grill, 2009 ). Variation between cuffs fabricated as consistently as possible amounted to 10% for impedance magnitude and 4° for impedance phase. Conclusion The results show that this low-cost tool can be used to characterize a cuff across different conditions including after implantation. The latter makes it useful for a longer-term study of electrode viability.

Neural stimulation and recording in rodents are common methods to better understand the nervous system and improve the quality of life of individuals who are suffering from neurological disorders (e.g., epilepsy), as well as for permanent reduction of chronic pain in patients with neuropathic pain and spinal-cord injury. This method requires a neural interface (e.g., a headmount) to couple the implanted neural device with instrumentation system. The size and the total weight of such headmounts should be designed in a way to minimize its effect on the movement of the animal. This is a crucial factor in gait, kinematic, and behavioral neuroscience studies of freely moving mice. Here we introduce a lightweight ‘snap-in’ electro-magnetic headmount that is extremely small, and uses strong neodymium magnetics to enable a reliable connection without sacrificing the lightweight of the device. Additionally, the headmount requires minimal surgical intervention during the implantation, resulting in minimal tissue damage. The device has demonstrated itself to be robust, and successfully provided direct electrical stimulation of nerve and electrical muscle stimulation and recording, as well as powering implanted LEDs for optogenetic use scenarios.

Regulating soft tissue repair to prevent fibrosis and promote regeneration is central to creating a microenvironment conducive to soft tissue development. Macrophages play an important role in this process. The macrophage response can be modulated using biomaterials, altering cytokine and growth factor secretion to promote regeneration. Electrospun polydioxanone (PDO) fiber scaffolds promoted an M2 phenotype when macrophages were cultured on large diameter, highly porous scaffolds, but an M1 phenotype on smaller diameter fibers. In this study, we investigated whether incorporation of galectin-1, an immunosuppressive protein that enhances muscle regeneration, could promote the M2 response. Galectin-1 was incorporated into large and small fiber PDO scaffolds during electrospinning. Galectin-1 incorporation increased arginase-1 and reduced iNOS and IL-6 production in mouse bone-marrow derived macrophages compared with PDO alone for both scaffold types. Inhibition of ERK mitogen-activated protein kinase did not alter galectin-1 effects on arginase-1 and iNOS expression, but reversed IL-6 suppression, indicating that IL-6 is mediated by a different mechanism. Our results suggest that galectin-1 can be used to modulate macrophage commitment to a pro-regenerative M2 phenotype, which may positively impact tissue regeneration when using small diameter PDO scaffolds. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2562-2571, 2017.

Studying animal locomotion improves our understanding of motor control and aids in the treatment of motor impairment. Mice are a premier model of human disease and are the model system of choice for much of basic neuroscience. Placement of the tips of appendages, here paws, is typically critical for locomotion. Tracking paws from a video is difficult, however, due to frequent occlusions and collisions. We propose a method and provide software to track the paws of rodents. We use a superpixel-based method to segment the paws, direct linear transform to perform 3D reconstruction, a 3D Kalman filter (KF) to solve the matching problem and label paws across frames, and spline fits through time to resolve common collisions. The automated method was compared to manual tracking. The method had an average of 2.54 mistakes requiring manual correction per 1000 frames with a maximum of 5.29 possible errors while these values were estimates of the expected errors. We present an algorithm and its implementation to track the paws of running rodents. This algorithm can be applied to different animals as long as the tips of the legs can be differentiated from the background and other parts of the body using color features. The presented algorithm provides a robust tool for future studies in multiple fields, where precise quantification of locomotor behavior from a high-speed video is required. We further present a graphical user interface (GUI) to track, visualize, and edit the tracking data.

The horse has evolved to gallop economically at high speed. Limb force increases with speed but direct measures of limb ground reaction forces (GRFs) at gallop are sparse. This study reports GRFs for multiple limbs, using force plates, across seven Thoroughbred racehorses during ridden galloping. The results show peak vertical GRF values of 13.6 N kg−1 (non-lead hindlimb), 12.3 N kg−1 (lead hindlimb), 14.0 N kg−1 (non-lead forelimb) and 13.6 N kg−1 (lead forelimb) at 11.4 m s−1 and recorded values are consistent with those predicted from duty factor. The distribution of body weight between the forelimbs and hindlimbs is approximated to 50:50, and is variable with speed, unlike the 60:40 commonly stated for cursorial quadrupeds in the literature. An even distribution of load on all limbs may help minimise accumulation of fatigue and assist in injury avoidance. Cranio-caudal force data concur with the observation that horses apply a net accelerative impulse with the hindlimbs and a net decelerative impulse with the forelimbs. Capturing GRFs enhances our knowledge on the mechanics of galloping in fast-moving species and provides insight into injury risk and factors limiting athletic performance.

One method for the evaluation of sensorimotor therapeutic interventions, the horizontal ladder walking task, analyzes locomotor changes that may occur after disease, injury, or by external manipulation. Although this task is well suited for detection of large effects, it may overlook smaller changes. The inability to detect small effect sizes may be due to a neural compensatory mechanism known as “cross limb transfer”, or the contribution of the contralateral limb to estimate an injured or perturbed limb’s position. The robust transfer of compensation from the contralateral limb may obscure subtle locomotor outcomes that are evoked by clinically relevant therapies, in the early onset of disease, or between higher levels of recovery. Here, we propose angled rungs as a novel modification to the horizontal ladder walking task. Easily-adjustable angled rungs force rats to locomote across a different locomotion path for each hindlimb and may therefore make information from the contralateral limb less useful. Using hM3Dq (excitatory) Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) expressed in large diameter peripheral afferents of the hindlimb in the intact animal, we characterized the sensitivity of our design to detect stepping differences by comparing locomotor changes observed on angled rungs to those observed on a standard horizontal ladder. On our novel asymmetrical ladder, activation of DREADDs resulted in significant differences in rung misses (p = 0.000011) and weight-supporting events (p = 0.049). By comparison, on a standard ladder, we did not observe differences in these parameters (p = 0.86 and p = 0.98, respectively). Additionally, no locomotor differences were detected in baseline and inactivated DREADDs trials when we compared ladder types, suggesting that the angled rungs do not change animal gait behavior unless intervention or injury is introduced. Significant changes observed with angled rungs may demonstrate more sensitive probing of locomotor changes due to the decoupling of cross limb transfer.

Lactic acid (LA) is present in tumors, asthma, and wound healing, environments with elevated IL-33 and mast cell infiltration. Although IL-33 is a potent mast cell activator, how LA affects IL-33–mediated mast cell function is unknown. To investigate this, mouse bone marrow–derived mast cells were cultured with or without LA and activated with IL-33. LA reduced IL-33–mediated cytokine and chemokine production. Using inhibitors for monocarboxylate transporters (MCT) or replacing LA with sodium lactate revealed that LA effects are MCT-1– and pH-dependent. LA selectively altered IL-33 signaling, suppressing TGF-β–activated kinase-1, JNK, ERK, and NF-κB phosphorylation, but not p38 phosphorylation. LA effects in other contexts have been linked to hypoxia-inducible factor (HIF)-1α, which was enhanced in bone marrow–derived mast cells treated with LA. Because HIF-1α has been shown to regulate the microRNA miR-155 in other systems, LA effects on miR-155-5p and miR-155-3p species were measured. In fact, LA selectively suppressed miR-155-5p in an HIF-1α–dependent manner. Moreover, overexpressing miR-155-5p, but not miR-155-3p, abolished LA effects on IL-33–induced cytokine production. These in vitro effects of reducing cytokines were consistent in vivo, because LA injected i.p. into C57BL/6 mice suppressed IL-33–induced plasma cytokine levels. Lastly, IL-33 effects on primary human mast cells were suppressed by LA in an MCT-dependent manner. Our data demonstrate that LA, present in inflammatory and malignant microenvironments, can alter mast cell behavior to suppress inflammation.

Musculoskeletal modelling has become a valuable tool with which to understand how neural, muscular, skeletal and other tissues are integrated to produce movement. Most musculoskeletal modelling work has to date focused on humans or their close relatives, with few examples of quadrupedal animal limb models. A musculoskeletal model of the mouse hindlimb could have broad utility for questions in medicine, genetics, locomotion and neuroscience. This is due to this species’ position as a premier model of human disease, having an array of genetic tools for manipulation of the animal in vivo, and being a small quadruped, a category for which few models exist. Here, the methods used to develop the first three‐dimensional (3D) model of a mouse hindlimb and pelvis are described. The model, which represents bones, joints and 39 musculotendon units, was created through a combination of previously gathered muscle architecture data from microdissections, contrast‐enhanced micro‐computed tomography (CT) scanning and digital segmentation. The model allowed muscle moment arms as well as muscle forces to be estimated for each musculotendon unit throughout a range of joint rotations. Moment arm analysis supported the reliability of musculotendon unit placement within the model, and comparison to a previously published rat hindlimb model further supported the model's reliability. A sensitivity analysis performed on both the force‐generating parameters and muscle's attachment points of the model indicated that the maximal isometric muscle moment is generally most sensitive to changes in either tendon slack length or the coordinates of insertion, although the degree to which the moment is affected depends on several factors. This model represents the first step in the creation of a fully dynamic 3D computer model of the mouse hindlimb and pelvis that has application to neuromuscular disease, comparative biomechanics and the neuromechanical basis of movement. Capturing the morphology and dynamics of the limb, it enables future dissection of the complex interactions between the nervous and musculoskeletal systems as well as the environment.

Understanding how animals regulate their gait during locomotion can give biological insight and inspire controllers for robots. Why animals use the gallop at the highest speeds remains incompletely explained. Hypothesized reasons for galloping include that it enables recruitment of spinal musculoskeletal structures, that it minimizes energy losses as predicted by collisional theory, or that it provides extended flight phases with more time for leg placement and hence enhances or provides necessary maneuverability [Alexander 1988 Am. Zool. 28 237–45; Ruina, Bertram and Srinivasan 2005 J. Theor. Biol. 237 170–92; Usherwood 2019 J. Exp. Zool. Part A 333 9–19; Hildebrand1989 Bioscience 39 766–75]. The latter-most hypothesis has implications in robotics, where controllers based on the concept of multistability have gained some traction. Here we examine this hypothesis by studying the dynamics of dog gait on flat and rough terrain. This hypothesis predicts that injection of noise into timing and location of ground contacts during the galloping gait by rough terrain will result in an isotropically more noisy gallop gait, centered around the gallop used on flat terrain. We find that dog gait in terms of leg swing timing on rough terrain is not consistently more variable about the mean gait, and constrain the upper limits of this variability to values that are unlikely to be biologically relevant. However the location of the mean gait indeed only shifts by a small amount. Therefore, we find limited support for this hypothesis. This suggests that achieving a target gallop gait with tight regulation is still the desired behavior, and that large amounts of variability in gait are not a desired feature of the gallop. For robotics, our results suggest that the emergent animal-environment dynamics on rough terrain do not exhibit uniformly wider basins of attraction. Future robotics work could test whether controllers that do or do not allow shifts in mean gait and gait variability produce more economical and/or stable gallops.

Mast cells have functional plasticity affected by their tissue microenvironment, which greatly impacts their inflammatory responses. Because lactic acid (LA) is abundant in inflamed tissues and tumors, we investigated how it affects mast cell function. Using IgE-mediated activation as a model system, we found that LA suppressed inflammatory cytokine production and degranulation in mouse peritoneal mast cells, data that were confirmed with human skin mast cells. In mouse peritoneal mast cells, LA-mediated cytokine suppression was dependent on pH- and monocarboxylic transporter-1 expression. Additionally, LA reduced IgE-induced Syk, Btk, and ERK phosphorylation, key signals eliciting inflammation. In vivo, LA injection reduced IgE-mediated hypothermia in mice undergoing passive systemic anaphylaxis. Our data suggest that LA may serve as a feedback inhibitor that limits mast cell-mediated inflammation.

Animals, including humans, have been shown to maintain a gait during locomotion that minimizes the risk of injury and energetic cost. Despite the importance of understanding the mechanisms of gait regulation, ethical and experimental challenges have prevented full exploration of these. Here we present data on the gait response of mice to rapid, precisely timed, spatially confined mechanical perturbations. Our data elucidate that after the mechanical perturbation, the mouse gait response is anisotropic, preferring deviations away from the trot towards bounding, over those towards other gaits, such as walk or pace. We quantified this shift by projecting the observed gait onto the line between trot and bound, in the space of quadrupedal gaits. We call this projection λ. For λ=0, the gait is the ideal trot; for λ=±π, it is the ideal bound. We found that the substrate perturbation caused a significant shift in λ towards bound during the stride in which the perturbation occurred and the following stride (linear mixed effects model: Δλ=0.26±0.07 and Δλ=0.21±0.07, respectively; random effect for animal, p 0.05 for both strides, n = 8 mice). We hypothesize that this is because the bounding gait is better suited to rapid acceleration or deceleration, and an exploratory analysis of jerk showed that it was significantly correlated with λ (p 0.05). Understanding how gait is controlled under perturbations can aid in diagnosing gait pathologies and in the design of more agile robots.

Implanted polymer scaffolds can induce inflammation leading to the foreign body response (FBR), fibrosis, and implant failure. Thus, it is important to understand how immune cells interact with scaffolds to mitigate inflammation and promote a regenerative response. We previously demonstrated that macrophage phenotype is modulated by fiber and pore diameters of an electrospun scaffold. However, it is unclear if this effect is consistent among other innate immune cells. Mast cells are inflammatory sentinels that play a vital role in the FBR of implanted biomaterials, as well as angiogenesis. We determined if altering electrospun scaffold architecture modulates mast cell responses, with the goal of promoting regenerative cell-scaffold interactions. Polydioxanone (PDO) scaffolds were made from 60 mg/mL or 140 mg/mL PDO solutions, yielding structures with divergent fiber and pore diameters. Mouse mast cells plated on these scaffolds were activated with IL-33 or lipopolysaccharide (LPS). Relative to the 60 mg/mL scaffold, 140 mg/mL scaffolds yielded less IL-6 and TNF, and greater VEGF secretion. Pores4-6 μm elicited less IL-6 and TNF secretion. IL-33-induced VEGF regulation was more complex, showing effects of both pore size and fiber diameter. These data indicate parameters that can predict mast cell responses to scaffolds, informing biomaterial design to increase wound healing and diminish implant rejection. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 884-892, 2019.

Although many arthropods have the ability to voluntarily lose limbs, how these animals rapidly adapt to such an extreme perturbation remains poorly understood. It is thought that moving with certain gaits can enable efficient, stable locomotion; however, switching gaits requires complex information flow between and coordination of an animal's limbs. We show here that upon losing two legs, spiders can switch to a novel, more statically stable gait, or use temporal adjustments without a gait change. The resulting gaits have higher overall static stability than the gaits that would be imposed by limb loss. By decreasing the time spent in a low-stability configuration—effectively “limping” over less stable phases of the stride—spiders increased the overall stability of the less statically-stable gait with no observable reduction in speed, as compared to the intact condition. Our results shed light on how voluntary limb loss could have persisted evolutionarily among many animals, and provide bioinspired solutions for robots when they break or lose limbs.

Examining locomotion has improved our basic understanding of motor control and aided in treating motor impairment. Mice and rats are the model system of choice for basic neuroscience studies of human disease. High frame rates are needed to quantify the kinematics of running rodents, due to their high stride frequency. Manual tracking, especially for multiple body landmarks, becomes extremely time-consuming. To overcome these limitations, we proposed the use of superpixels based image segmentation as superpixels utilized both spatial and color information for segmentation. We segmented some parts of body and tested the success of segmentation as a function of color space and SLIC segment size. We used a simple merging function to connect the segmented regions considered as neighbor and having the same intensity value range. In addition, 28 features were extracted, and t-SNE was used to demonstrate how much the methods are capable to differentiate the regions. Finally, we compared the segmented regions to a manually outlined region. The results showed for segmentation, using the RGB image was slightly better compared to the hue channel. For merg- ing and classification, however, the hue representation was better as it captures the relevant color information in a single channel., Comment: This paper has been accepted by the Journal of Pattern Recognition and Image Analysis (PRIA), being published by July 2018

One of the grand challenges for modern science is to understand how animals (including humans!) move. Movement results from the dynamic interaction of many complex, nonlinear constituents: the nervous system, muscles, body, and an often-unpredictable external environment. Yet many animals move quickly through the environment with stability and economy surpassing our technology. This talk will present three threads of research that seek to understand different aspects of legged locomotion control: 1) comparative work in insects, dogs, and the XRL robot aimed at understanding both how and why control strategy varies with body morphology, 2) a dynamical systems approach to understanding gait, that aims to understand how the "fine structure" of experimentally observed quadrupedal gait control reflects constraints such as stability, and finally, 3) recent work that brings the new genetic tools of optogenetics and chemogenetics (DREADDs) to bear on long-standing problems in legged locomotion control, and that is finding application in spinal cord injury.

How animals, including humans, are moving has been a grand challenge for modem science that has a direct impact on our health and wellbeing. It can provide a wealth of information to explain the biological world, and to treat human and animal disease. In addition, it can guide us to improve prosthetic limb design or legged robots [1], [2].

Nerve cuff electrodes can be used in neuroprosthetic applications, treatment of chronic pain, acquiring sensory feedback, and recording electroneurograms. The nerve cuffs are not dependent on the muscle length and limb position compared to the surface and muscle electrodes; they are fixed around the nerve which reduces the relative movement caused by muscle contraction. In addition, it can reduce the required magnitude to stimulate nerves [1].

Examining locomotion has improved our basic understanding of motor control and aided in treating motor impairment. Mice and rats are premier models of human disease and increasingly the model systems of choice for basic neuroscience. High frame rates (250 Hz) are needed to quantify the kinematics of these running rodents. Manual tracking, especially for multiple markers, becomes time-consuming and impossible for large sample sizes. Therefore, the need for automatic segmentation of these markers has grown in recent years. We propose two methods to segment and track these markers: first, using SLIC superpixels segmentation with a tracker based on position, speed, shape, and color information of the segmented region in the previous frame; second, using a thresholding on hue channel following up with the same tracker. The comparison showed that the SLIC superpixels method was superior because the segmentation was more reliable and based on both color and spatial information., This paper has been accepted for 2017 Asilomar conference, IEEE

Mast cell activation via the high-affinity IgE receptor (FcεRI) elicits production of inflammatory mediators central to allergic disease. As a synthetic antioxidant and a potent ribonucleotide reductase (RNR) inhibitor, Didox (3,4-dihyroxybenzohydroxamic acid) has been tested in clinical trials for cancer and is an attractive therapeutic for inflammatory disease. We found that Didox treatment of mouse bone marrow-derived mast cells (BMMC) reduced IgE-stimulated degranulation and cytokine production, including IL-6, IL-13, TNF and MIP-1a (CCL3). These effects were consistent using BMMC of different genetic backgrounds and peritoneal mast cells. While the RNR inhibitor hydroxyurea had little or no effect on IgE-mediated function, high concentrations of the antioxidant N-acetylcysteine mimicked Didox-mediated suppression. Furthermore, Didox increased expression of the antioxidant genes superoxide dismutase and catalase, and suppressed DCFH-DA fluorescence, indicating reduced reactive oxygen species production. Didox effects were not due to changes in FcεRI expression or cell viability, suggesting it inhibits signaling required for inflammatory cytokine production. In support of this, we found that Didox reduced FcεRI-mediated AP-1 and NFκB transcriptional activity. Finally, Didox suppressed mast cell-dependent, IgE-mediated passive systemic anaphylaxis in vivo. These data demonstrate the potential use for Didox as a means of antagonizing mast cell responses in allergic disease.

While IgE is considered the primary mediator of mast cell activation, IL-33 contributes substantially in asthma, allergic rhinitis, and atopic dermatitis. To develop effective treatments for allergic disease, it is important to understand the role of therapeutic agents on IL-33 activation. We examined the effect of Didox (3,4-dihydroxybenzohydroxamic acid), an antioxidant and ribonucleotide reductase (RNR) inhibitor, on IL-33-mediated mast cell activation. Didox suppressed IL-6, IL-13, TNF, and MIP-1α (CCL3) production in bone marrow derived mast cells following IL-33 activation. This suppression was observed in different genetic backgrounds and extended to peritoneal mast cells. The antioxidant N-acetylcysteine mimicked the suppression of Didox, albeit at a much higher dose, while the RNR inhibitor hydroxyurea had no effect. Didox substantially suppressed IL-33-mediated NFκB and AP-1 transcriptional activities. These results suggest that Didox attenuates IL-33-induced mast cell activation and should be further studied as a potential therapeutic agent for inflammatory diseases involving IL-33.

Legged animals utilize gait selection to move effectively and must recover from environmental perturbations. We show that on rough terrain, domestic dogs, Canis lupus familiaris, spend more time in longitudinal quasi-statically stable patterns of movement. Here, longitudinal refers to the rostro-caudal axis. We used an existing model in the literature to quantify the longitudinal quasi-static stability of gaits neighbouring the walk, and found that trot-like gaits are more stable. We thus hypothesized that when perturbed, the rate of return to a stable gait would depend on the direction of perturbation, such that perturbations towards less quasi-statically stable patterns of movement would be more rapid than those towards more stable patterns of movement. The net result of this would be greater time spent in longitudinally quasi-statically stable patterns of movement. Limb movement patterns in which diagonal limbs were more synchronized (those more like a trot) have higher longitudinal quasi-static stability. We therefore predicted that as dogs explored possible limb configurations on rough terrain at walking speeds, the walk would shift towards trot. We gathered experimental data quantifying dog gait when perturbed by rough terrain and confirmed this prediction using GPS and inertial sensors (n=6, P, Summary: Dogs co-ordinate their limbs on rough terrain in a manner consistent with optimization for quasi-static longitudinal stability.

There have been many investigations into consistent, individual differences in behavior (animal personalities), but rather less attention has been given to the possibility that individuals might differ consistently in their "cognitive style," which refers to the way information is acquired, processed, stored, or acted on. Both personality and cognition have important fitness consequences, and it has been proposed that variation in cognition could be functionally related to variation in personality. Here, we test this hypothesis using three-spined sticklebacks (Gasterosteus aculeatus) as a model and adopt a classic T-maze with food reward experimental paradigm. We first confirmed that fish choose the correct arm of the maze significantly more than would be expected by chance and that this improves with trial number. We then explored predictors of individual differences in the speed (time to making a decision) and accuracy (whether the first decision is correct) in decision making. We find bolder behavioral types (who tend to be male) arrive at the correct decision sooner than their shyer conspecifics. However, boldness was not related to decision accuracy. Moreover, we did not find any significant difference in fish’s improvement in decision accuracy over successive trials according to boldness or sex. This suggests that although bolder fish may acquire information more quickly because they make decisions faster, they do not differ from shyer conspecifics in their decision-making accuracy. The absence of such a trade-off might offer a functional explanation for why, in stickleback fish and many other species, bolder individuals tend to initiate movement and shyer individuals to follow—bold leaders may result in faster group decisions without compromising accuracy.

The observation of both human and animal kinematics has proven to be of tremendous scientific value for both understanding biological phenomena and development of medical treatments. Rodents, in particular, are widely used as a model for human disease. Unfortunately, they are also notoriously difficult to use in experiments requiring the use of motion capture (MoCap) for kinematic analyses. Current commercially available technology for rodent MoCap (e.g. Digigait [1, 2], Motorater, Noldus Catwalk [3, 4]) requires either frequent anaesthesia for shaving and tattooing of anatomical landmarks , or retroreflective markers known to agitate rodent subjects. Less automated methods require the use of high speed video capture and manual tracking, which both time and data intensive.

Horse locomotion is remarkably economical. Here, we measure external mechanical work of the galloping horse and relate it to published measurements of metabolic cost. Seven Thoroughbred horses were galloped (ridden) over force plates, under a racing surface. Twenty-six full strides of force data were recorded and used to calculate the external mechanical work of galloping. The mean sum of decrements of mechanical energy was −876 J (±280 J) per stride and increments were 2163 J (±538 J) per stride as horses were accelerating. Combination with published values for internal work and metabolic costs for galloping yields an apparent muscular efficiency of 37–46% for galloping, which would be reduced by energy storage in leg tendons. Knowledge about external work of galloping provides further insight into the mechanics of galloping from both an evolutionary and performance standpoint.

The neural circuitry that controls legged locomotion is exquisitely state dependent. The response to a perturbation at one phase of the locomotor cycle is very different from another. As such, tools that enable closed loop experiments in which freely moving animals can be precisely perturbed, either neurally or mechanically, will improve our ability to probe the locomotor control architecture. Because locomotion emerges from the coupled interaction of the nervous system, musculoskeletal system, and physics of the moving body, ideally an experimenter could simultaneously perturb the nervous system, mechanics of the moving animal, or both, at precise moments during well defined locomotor behaviour. Combining the new technique of optogenetics with closed loop tracking of state and fast mechanical perturbations would make this possible. Here we present a computer vision feedback controlled treadmill designed to enable such perturbations. We show that insects (cockroaches Blaberus discoidalis ) and mice ( Mus mus ; C57BL/6) run freely, with preferred speeds in agreement with the literature, over many strides, on the system. We demonstrate the utility of the closed loop system by automatically gathering high speed video (HSV) data when the running animal meets specific operational criteria; here, running within a restricted range of speeds near the midline of the treadmill for a minimum of 2 s. We quantify the mouse's gait from HSV data with a phase-based approach, confirming a normal trotting gait. These results demonstrate the system's potential for dissecting the neuromechanical basis of legged locomotion through closed-loop experimental design.

The purpose of this study was to perform a number of preliminary in vitro evaluations on an array of modified gelatin gel sponge scaffolds for use in a bone graft application. The gelatin gels were modified through the addition of a number of components which each possess unique properties conducive to the creation and regeneration of bone: a preparation rich in growth factors (PRGF, a bioactive, lyophilized form of platelet-rich plasma), hydroxyapatite, and chitin whiskers. Platelet-rich plasma therapy is an emerging practice that has proven effective in a number of clinical applications, including enhancing bone repair through improved deposition of new bony matrix and angiogenesis. As such, the inclusion of PRGF in our gelatin scaffolds was intended to significantly enhance scaffold bioactivity, while the addition of hydroxyapatite and chitin whiskers were anticipated to increase scaffold strength. Additionally, the gelatin sponges, which readily dissolve in aqueous solutions, were subjected to 1-Ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC) cross-linking, either during or post-gelation, to control their rate of degradation. Scaffolds were evaluated in vitro with respect to compressive strength, mass loss/degradation, protein release, and cellular interaction, with results demonstrating the potential of the gelatin gel sponge scaffold for use in the regeneration of bone.

TGF-β1 is involved in many pathological conditions, including autoimmune disorders, cancer, and cardiovascular and allergic diseases. We have previously found that TGF-β1 can suppress IgE-mediated mast cell activation of human and mouse mast cells. IL-33 is a member of the IL-1 family capable of inducing mast cell responses and enhancing IgE-mediated activation. In this study, we investigated the effects of TGF-β on IL-33–mediated mast cell activation. Bone marrow–derived mast cells cultured in TGF-β1, β2, or β3 showed reduced IL-33–mediated production of TNF, IL-6, IL-13, and MCP-1 in a concentration-dependent manner. TGF-β1 inhibited IL-33–mediated Akt and ERK phosphorylation as well as NF-κB– and AP-1–mediated transcription. These effects were functionally important, as TGF-β1 injection suppressed IL-33–induced systemic cytokines in vivo and inhibited IL-33–mediated cytokine release from human mast cells. TGF-β1 also suppressed the combined effects of IL-33 and IgE-mediated activation on mouse and human mast cells. The role of IL-33 in the pathogenesis of allergic diseases is incompletely understood. These findings, consistent with our previously reported effects of TGF-β1 on IgE-mediated activation, demonstrate that TGF-β1 can provide broad inhibitory signals to activated mast cells.

Mast cells are critical effectors of allergic disease and can be activated by IL-33, a proinflammatory member of the IL-1 cytokine family. IL-33 worsens the pathology of mast cell–mediated diseases, but therapies to antagonize IL-33 are still forthcoming. Because steroids are the mainstay of allergic disease treatment and are well known to suppress mast cell activation by other stimuli, we examined the effects of the steroid dexamethasone on IL-33-mediated mast cell function. We found that dexamethasone potently and rapidly suppressed cytokine production elicited by IL-33 from murine bone marrow–derived and peritoneal mast cells. IL-33 enhances IgE-mediated mast cell cytokine production, an activity that was also antagonized by dexamethasone. These effects were consistent in human mast cells. We additionally observed that IL-33 augmented migration of IgE-sensitized mast cells toward antigen. This enhancing effect was similarly reversed by dexamethasone. Simultaneous addition of dexamethasone with IL-33 had no effect on the phosphorylation of MAP kinases or NFκB p65 subunit; however, dexamethasone antagonized AP-1- and NFκB-mediated transcriptional activity. Intraperitoneal administration of dexamethasone completely abrogated IL-33-mediated peritoneal neutrophil recruitment and prevented plasma IL-6 elevation. These data demonstrate that steroid therapy may be an effective means of antagonizing the effects of IL-33 on mast cells in vitro and in vivo, acting partly by suppressing IL-33-induced NFκB and AP-1 activity.

Mice are one of the most commonly used laboratory animals, with an extensive array of disease models in existence, including for many neuromuscular diseases. The hindlimb is of particular interest due to several close muscle analogues/homologues to humans and other species. A detailed anatomical study describing the adult morphology is lacking, however. This study describes in detail the musculoskeletal geometry and skeletal muscle architecture of the mouse hindlimb and pelvis, determining the extent to which the muscles are adapted for their function, as inferred from their architecture. Using I2KI enhanced microCT scanning and digital segmentation, it was possible to identify 39 distinct muscles of the hindlimb and pelvis belonging to nine functional groups. The architecture of each of these muscles was determined through microdissections, revealing strong architectural specialisations between the functional groups. The hip extensors and hip adductors showed significantly stronger adaptations towards high contraction velocities and joint control relative to the distal functional groups, which exhibited larger physiological cross sectional areas and longer tendons, adaptations for high force output and elastic energy savings. These results suggest that a proximo-distal gradient in muscle architecture exists in the mouse hindlimb. Such a gradient has been purported to function in aiding locomotor stability and efficiency. The data presented here will be especially valuable to any research with a focus on the architecture or gross anatomy of the mouse hindlimb and pelvis musculature, but also of use to anyone interested in the functional significance of muscle design in relation to quadrupedal locomotion.

We used a radio tracking system to examine the speed of 373 racehorses on different gradients on an undulating racecourse during 33 races, each lasting a few minutes. Horses show a speed detriment on inclines (0.68 m·s−1·1% gradient−1, r2= 0.97), the magnitude of which corresponds to trading off the metabolic cost (power) of height gain with the metabolic cost (power) of horizontal galloping. A similar relationship can be derived from published data for human runners. The horses, however, were also slower on the decline (−0.45 m·s−1·1% gradient−1, r2= 0.92). Human athletes run faster on a decline, which can be explained by the energy gained by the center of mass from height loss. This study has shown that horses go slower, which may be attributable to the anatomical simplicity of their front legs limiting weight support and stability when going downhill. These findings provide insight into limits to athletic performance in racehorses, which may be used to inform training regimens, as well as advancing knowledge from both veterinary and basic science perspectives.

The size of an organism is critical to understanding its biology. A telling example comes from the use of sound to localize a potential predatory or prey: this can be based on interaural time difference, but only if the distance between the ears, and hence the size of the head, is large enough. Or consider vision: the diffraction limit constrains the size of image-forming eyes to a certain minimum. The importance of size as a holistic feature of organisms, with consequences for our understanding at every length scale, was taken firmly on board in the early 20th century.

Examining locomotion has improved our basic understanding of motor control and aided in treating motor impairment. Mice are a premier model of human disease and increasingly the model system of choice for basic neuroscience. High frame rates (higher than 150 Hz) are needed to quantify the kinematics of running mice, due to their high stride frequency (up to 10 Hz). Thus manual tracking, especially for multiple markers, becomes time-consuming and impossible for large sample sizes. Therefore, an automated method is necessary. Several methods have been used to automatically or semi-automatically track mice, including commercially available systems (Digigait [1, 2], Motorater, Noldus Catwalk [3, 4]). These systems can be typically prohibitively expensive, and may only provide information about paws during the stand phase. In research and industry approaches to tracking mice have frequently relied on shaving fur and then drawing markers on the skin for subsequent tracking raw video [5], or on the attachment of retroreflective markers, and the use of optical motion capture systems. These methods have the drawback of requiring anesthesia and multiple handlings applications of markers, and the problem of animal removing the attached markers. Here, we develop methods to track and label the body and paws directly from high speed color video, without shaving fur or attaching markers. We analyse data from the C57BL/6 mouse, because it is the most widely used strain in basic research and biomedicine.

Reported data for injuries sustained by jockeys in thoroughbred horse racing vary greatly. While the range of abilities and types of racing may account for some variation, the variations result mainly from differences in the definitions and methodologies employed in the studies. The British Horseracing Authority (BHA) facilitated a meeting of experts from the four leading horse racing countries in Europe. Using an approach adopted by the previous consensus groups addressing sports injuries, issues related to definitions, methodology and implementation were discussed and voted on by the group during a structured one-day meeting. Following this meeting, two members of the consensus group produced a draft document, based on the group discussions, which was circulated for review; two revisions were prepared before the final consensus statement was produced. The definition of injury and the criteria for recording the severity and nature of injuries are proposed for use in future epidemiological studies of injuries sustained by riders and associated support staff in the thoroughbred horse racing industry. Suggestions are made for recording participant baseline information together with recommendations on how injuries sustained during racing and associated activities should be reported. The definitions and methodology proposed for recording injuries, sustained during thoroughbred horse racing activities will lead to more uniform data being collected. The surveillance procedures presented here may also be applicable to other equine sports such as trotting, polo, show jumping and eventing. Based on injuries reported to racecourse medical officers in France, Ireland and the UK over the period 1992–2001, jockeys have an incidence of 1–2 injuries per 1000 rides in flat racing and 6–12 injuries per 1000 rides in jump racing.1 Insurance claims from injured jockeys indicate lower incidences of 1 injury per 1000 rides in flat racing and 3 injuries per 1000 rides in jump racing2 but …

SUMMARYGliding is thought to be an economical form of locomotion. However, few data on the climbing and gliding of free-ranging gliding mammals are available. This study employed an animal-borne three-dimensional acceleration data-logging system to collect continuous data on the climbing and gliding of free-ranging Malayan colugos, Galeopterus variegatus. We combined these movement data with empirical estimates of the metabolic costs to move horizontally or vertically to test this long-standing hypothesis by determining whether the metabolic cost to climb to sufficient height to glide a given distance was less than the cost to move an equivalent distance horizontally through the canopy. On average, colugos climb a short distance to initiate glides. However, due to the high energetic cost of climbing, gliding is more energetically costly to move a given horizontal distance than would be predicted for an animal travelling the same distance through the canopy. Furthermore, because colugos spend a small fraction of their time engaged in locomotor activity, the high costs have little effect on their overall energy budget. As a result, the energetic economy hypothesis for the origins of gliding is not supported. It is likely that other ecologically relevant factors have played a greater role in the origins of gliding in colugos and other mammals.