The integration of technology into exercise reg-imens has emerged as a strategy to enhance normal human capabilities and return human motor function after injury or illness by enhancing motor learning. Much research has focused on how active devices, whether confined to a lab or made into a wearable format, can apply forces at set times and conditions to optimize injury prevention and proper movement. As a result, these devices tend to be confined to single movements or simple interventions. A focus on active forces, however, ignores the potential of continuous passive interactions. In this paper, we investigate how passive device behaviors by themselves can contribute to the process of training proper movement. Using a wearable resistance (WR) device, which is outfitted with elastic bands, we apply a force field that passively changes in response to full-body movements. We first develop a method to measure the produced forces from the device without impeding the function and we characterize the device's force generation. We then present a study assessing the impact of the WR device on overhead squat form compared to visual or no feedback. Our findings suggest that the force fields produced while training with the WR device could improve performance in full-body exercises more consistently compared to direct visual feedback, with effects seen on cross-body asymmetry. Our results provide insights into the application of passive wearable resistance technology in practical exercise settings.

The integration of technology into exercise regimens has emerged as a strategy to enhance normal human capabilities and return human motor function after injury or illness by enhancing motor learning and retention. Much research has focused on how active devices, whether confined to a lab or made into a wearable format, can apply forces at set times and conditions to optimize the process of learning. However, the focus on active force production often forces devices to either be confined to simple movements or interventions. As such, in this paper, we investigate how passive device behaviors can contribute to the process of motor learning by themselves. Our approach involves using a wearable resistance (WR) device, which is outfitted with elastic bands, to apply a force field that changes in response to a person's movements while performing exercises. We develop a method to measure the produced forces from the device without impeding the function and we characterize the device's force generation abilities. We then present a study assessing the impact of the WR device on motor learning of proper squat form compared to visual or no feedback. Biometrics such as knee and hip angles were used to monitor and assess subject performance. Our findings indicate that the force fields produced while training with the WR device can improve performance in full-body exercises similarly to a more direct visual feedback mechanism, though the improvement is not consistent across all performance metrics. Through our research, we contribute important insights into the application of passive wearable resistance technology in practical exercise settings.

ABSTRACT Background The stroma plays a key role during renal development and in regeneration after injury. However, following injury, the stroma expands driving progressive fibrosis. Hyaluronan (HA) is a glycosaminoglycan that is absent in healthy kidney stroma but highly expressed in disease. To understand strategies to modulate stromal HA towards therapeutic advantage, this study compares HA and HA Synthase (HAS) enzyme expression in kidney development, health, disease, and recovery. Methods Rats underwent ischaemia reperfusion injury (IRI) with/without ischaemic preconditioning (IPC) and kidneys histologically analysed. Kidneys from C57BL/6 embryos and HAS1/3 -/- mice were also analysed and parallel mechanistic cell studies performed using primary human fibroblasts. Results In health, stromal HA was absent from the renal cortex. HAS1 was expressed in some epithelial cells, whilst HAS2 was not expressed. Following IRI there was increased stromal HA in areas of chronic fibrosis, alongside increased HAS2 (but not HAS1) expression. In contrast, during development prominent stromal HA matrices were evident in areas of tubular generation, with strong HAS1 (not HAS2) expression. Following IPC+IRI, stromal HA and HAS2 were attenuated; whilst HAS1 + cells expanded but were distinct from α-SMA + myofibroblasts. Cell studies demonstrated that HAS1 + fibroblasts had a functionally distinct phenotype, with enhanced migration and FAP expression but attenuated α-SMA, EDA-FN and COL1A1 expression, whereas HAS2 + fibroblasts demonstrated a classic α-SMA + contractile myofibroblast phenotype with high EDA-FN and COL1A1. Conclusions HA is a key regulator of stromal fibroblast heterogeneity, with HAS1 and HAS2 defining phenotypically distinct populations that may influence divergent renal outcomes following injury. SIGNIFICANCE STATEMENT Hyaluronan (HA) is a matrix glycosaminoglycans that is absent in healthy kidney cortex but demonstrates increased expression in the renal stroma during progressive fibrosis. This study makes comparisons of HA accumulation, localisation, and HA Synthase (HAS) protein expression during kidney development, in health, following ischaemic kidney injury and during renal recovery. The study identifies that different HAS isoenzymes (HAS1 and HAS2) mediate distinct functional fibroblast phenotypes in vitro and are localised in distinct stromal localisations and cell sub-populations in vivo . The data provides interesting insights into HA dependent regulation of fibroblast stromal heterogeneity and identifies the novel finding that HAS1 defines cell populations that are associated with kidney recovery following ischaemic injury and are protective against progressive renal fibrosis.

Background/Objective: Gut dysbiosis has been linked with the development of low-grade inflammation in part due to an increase in pro-inflammatory cytokines and a decrease in short chain fatty acid production. This project aims to study the effects of antibiotics-driven dysbiosis on host gene expression in murine ilea. Additionally, we will examine the ilea for morphological differences among treatment groups. Methods: Wild-type C57Bl/6J mice were given either an antibiotic (ampicillin, neomycin, vancomycin, or metronidazole) in water or water alone from 5 to 16 weeks of age. Mice were euthanized at 16 weeks, and the ilea were collected. RNA isolation and quantification were performed using the QIAgen RNeasy Lipid Tissue Mini Kit and BioTek Cytation 5 with Take3 plate, respectively.Histology of the ilea will be performed using hematoxylin and eosin (H&E) staining. Results: The average RNA yield was 3.91 ± 1.14 μg/mg of tissue, and the average RNA purity, reported as the 260/280 nm ratio, was 2.06 ± 0.02. A Kruskal-Wallis test revealed there was no statistically significant difference in the average RNA yield between experimental groups (p-value = 0.15). Transcriptomes of isolated samples will be sequenced, and results will be analyzed in association with 16S sequencing (Zymo) of bacterial communities of the gut. Based on prior murine studies, we expect upregulation of pro-inflammatory cytokines and downregulation of tight junction proteins, which contribute to inflammation and increased gut permeability. Conclusion and Scientific Impact: At this time, conclusions on the effects of antibiotics- driven dysbiosis on murine ileal gene expression and H&E staining cannot be made as further results and analysis are pending. However, the RNA sequencing and H&E results will be important to examine the impact of changes to the gut microbiome resulting from the administration of various antibiotics and further understand the relationship between antibiotics- driven dysbiosis and the microbe-host relationship

Cell spreading and migration play central roles in many physiological and pathophysiological processes. We have previously shown that MFN2 regulates the migration of human neutrophil-like cells via suppressing Rac activation. Here, we show that in mouse embryonic fibroblasts, MFN2 suppresses RhoA activation and supports cell polarization. After initial spreading, the wild-type cells polarize and migrate, whereas the Mfn2-/- cells maintain a circular shape. Increased cytosolic Ca2+ resulting from the loss of Mfn2 is directly responsible for this phenotype, which can be rescued by expressing an artificial tether to bring mitochondria and endoplasmic reticulum to close vicinity. Elevated cytosolic Ca2+ activates Ca2+/calmodulin-dependent protein kinase II, RhoA, and myosin light-chain kinase, causing an overactivation of nonmuscle myosin II, leading to a formation of a prominent F-actin ring at the cell periphery and increased cell contractility. The peripheral actin band alters cell physics and is dependent on substrate rigidity. Our results provide a novel molecular basis to understand how MFN2 regulates distinct signaling pathways in different cells and tissue environments, which is instrumental in understanding and treating MFN2-related diseases.

OBJECTIVES/GOALS: Our goal was to assess the ability of a 3D-Printed dual cover-core design alveolar ridge bone graft, to withstand the average maximum masticatory force of a healthy person. To this end, we characterized the materials, ran a finite element analysis (FEA) model, and validated it using a resin 3D-printed version tested under compression with strain gauges. METHODS/STUDY POPULATION: A tricalcium-phosphate/hydroxyapatite paste and mixed methacrylated alginate-gelatin were used for the core, and polycaprolactone for the cover. These were characterized using ASTM standards D695 and D638 for compression, tensile, and rheological testing. Then we converted cone CT-scan images of a mandibular alveolar ridge defect to an .stl file, and designed the cover and core in Meshmixer. The model was then imported into ANSYS 11.0, and a downward compression force of 500 N, the maximum masticatory force of a healthy adult, was applied on the graft and mandible’s top ridge. The different models included solid and porous covers and cores, as well as comparing screws on one or both sides of the cover, then validated by compressing a resin 3D-printed versions. RESULTS/ANTICIPATED RESULTS: The FEA model provided maximum displacements, Von Mises stress (VMS), and stress/strain values for each model. The highest maximum displacement was found on the solid covers with a combination of both buccal and lingual screws, at 0.162 mm. The lowest maximum displacement was found in the porous cover at 0.085 mm. All VMS values were below the tensile yield strength, meaning that the materials would not yield. The highest maximum stress was found on the porous cover at 13.52 MPa, the lowest was 1.06 MPa on the cover with no screws. The highest strain was found on the porous model at 0.010, which was 5.6x higher than the solid cover. The porous cover also showed less stress shielding, thus allowing a beneficial mechanical stimulation of the bone, and the lowest maximum displacement, possibly due to flexion through the pores. DISCUSSION/SIGNIFICANCE: Preliminary FEA models demonstrated that for the considered materials, a cover-core design of the mandibular implant would sustain the desired 500 N of force without yielding. The porous cover provides the most benefits, causing the least stress shielding and allowing diffusion of biological factors to support the osteoinductive role of the core.

Hyaluronan, a glycosaminoglycan synthesized by three isoenzymes (Has1, Has2, Has3), is known to play a role in regulating bone turnover, remodeling, and mineralization, which in turn can affect bone quality and strength. The goal of this study is to characterize how the loss of Has1 or Has3 affects the morphology, matrix properties, and overall strength of murine bone. Femora were isolated from Has1-/-, Has3-/-, and wildtype (WT) C57Bl/6 J female mice and were analyzed using microcomputed-tomography, confocal Raman spectroscopy, three-point bending, and nanoindentation. Of the three genotypes tested, Has1-/-bones demonstrated significantly lower cross-sectional area (p = 0.0002), reduced hardness (p = 0.033), and lower mineral-to-matrix ratio (p < 0.0001). Has3-/- bones had significantly higher stiffness (p < 0.0001) and higher mineral-to-matrix ratio (p < 0.0001) but lower strength (p = 0.0014) and bone mineral density (p < 0.0001) than WT. Interestingly, loss of Has3 was also associated with significantly lower accumulation of advanced glycation end-products than WT (p = 0.0478). Taken together, these results demonstrate, for the first time, the impact of the loss of hyaluronan synthase isoforms on cortical bone structure, content, and biomechanics. Loss of Has1 impacted morphology, mineralization, and micron-level hardness, while loss of Has3 reduced bone mineral density and affected organic matrix composition, impacting whole bone mechanics. This is the first study to characterize the effect of loss of hyaluronan synthases on bone quality, suggesting an essential role hyaluronan plays during the development and regulation of bone.

Background/Objective: Movement and walking are huge facets in how we go about our lives and experience the world. Gait is compromised in numerous conditions, from injury and chronic pain to neurological conditions and arthritis. Movement biomechanics have therefore been studied extensively in humans for decades. Although animal models are often used to examine the progression of various health conditions, translational gait research in animal models are less complete, and there is limited information on gait changes as mice grow. Methods: We recorded video segments of wild-type C57Bl/6J mice during skeletal growth (5 weeks to 16 weeks) walking (n = 4 Female, n = 2 Male) at 20 cm/s on the DigiGait system, a transparent treadmill equipped with a high-speed camera. Videos captured a ventral view of the mouse and were processed using DigiGait Analysis software, which uses local thresholding and position-finding algorithms to examine paw placement on the treadmill belt. Manual adjustments were made to eliminate artifacts and confirm heel-strike and toe-off times. After these corrections, the software returns stride parameters that were compared between sexes. Results: Over 30 gait metrics, including stride length, frequency, stance/swing times, and stance width, were calculated for all four limbs per animal for several time points. Stride length increased from 4.5 ± .5 cm at week 5 to 5.0 ± .8 cm at week 16, and frequency decreased from 4.6 ± .6 to 4.2 ± .6 steps per second. No notable changes in stance width, symmetry, or stance/swing ratio were identified. Conclusion and Potential Impact: Future directions for this research include conducting a principal component analysis to investigate the variability within the gait data. Identifying trends in gait parameters will help create a more complete picture of gait maturation. Establishing this baseline data allows for its comparison against treatment groups and the potentially meaningful investigation of translatable therapeutics and interventions.

Abstract Hiring practices in academia have critically limited the entry of individuals from historically excluded groups (e.g., people who identify as Black/African American, Hispanic/Latino, American Indian/Alaskan Native, LGBTQ+, people with disabilities) into our biomedical engineering faculty. Excluding such individuals has hindered our profession’s research impact and ability to equitably educate our students. With many departments committed to “do better,” we now need to embrace a new mindset and gain the skills necessary to rectify injustices in our faculty hiring processes. Here, we offer a faculty hiring roadmap that departments can leverage to eliminate many barriers of entry to members of historically excluded groups as faculty in biomedical engineering. We call on our colleagues to recognize the failings of our current hiring practices and adopt the guidelines provided here to diversify biomedical engineering departments so that we might collectively accelerate the impact, innovation, and power of our profession.

Background and Hypothesis Bacterial vaginosis, which is the imbalance of normal vaginal microbiota, contributes to preterm delivery, vaginitis, and decreased drug efficacy. Despite metronidazole efficacy in reducing BV contributing organisms, BV continues to recur in 50% of patients. Previous studies showing imidazole propionate’s role in the pathogenesis of type II diabetes suggest that similar metabolite-regulated pathways in vaginal microbiomes may be the key in pathogenesis of uterine diseases such as BV. Thus, the purpose of this study was to observe the relationship between vaginal metabolites, host or microbiome-derived, and transcriptomic responses in vaginal epithelial tissues stratified by vaginal microbiome composition (“microbiome group”). The hypothesis was that differences in vaginal microbiome composition result in differential regulation of metabolite-host pathway functional relationships. Project Methods Transcript levels and metabolite concentrations precollected from 23 East African women were processed and analyzed via R. Transcriptomic data were converted into KEGG pathway enrichment scores via ssGSEA2.0, a package within R. Enrichment scores were correlated (Spearman) with metabolite levels by microbiome group and lactobacillus dominant phenotypes, and relationships were visualized via Heatmap3 and Cytoscape. Results: The results showed varying strengths in correlation among metabolites and KEGG pathway enrichment scores after filtering for strong correlations (R > |0.5|) and significance (p< 0.05). Nonlactobacillus dominant microbiomes showed fewer strongly associated metabolite-KEGG pathway relationships compared to the lactobacillus dominant microbiome group, specifically the imidazole-related networks. Conclusion: In this study, variations in significant correlations among metabolites and KEGG pathways suggests that microbiome diversity may contribute to how metabolites regulate host pathways in vaginal epithelial cells. The reduced pathway interactions observed in imidazole compounds suggests that dysregulation may contribute to recurrence of bacterial vaginosis. This method of modelling could be used to characterize the regulation of critical pathways associated with the pathogenesis of bacterial vaginosis.

•In vivo tagged MRI was used to estimate 3D strain fields during mild head impact.•Peak strains of 0.02–0.05 were measured and correlated with peak angular velocity.•First study to report in vivo estimates of impact-induced strain along axonal fibers.•Regional differences in axonal fiber strains observed between head motions.

We have examined the effect of exogenous linear chain high molecular weight hyaluronic acid (HMW HA) on endogenously synthesized hyaluronic acid (HA) and associated binding proteins in primary cultures of fibroblast-like stromal cells that were obtained by collagenase digestion of the murine peripatellar fat pad. The cultures were expanded in DMEM that was supplemented with fetal bovine serum and basic fibroblast growth factor (bFGF) then exposed to macrophage-colony-stimulating factor (MCSF) to induce macrophage properties, before activation of inflammatory pathways using E. coli lipopolysaccharide (LPS). Under all culture conditions, a significant amount of endogenously synthesized HA localized in LAMP1-positive lysosomal vesicles. However, this intracellular pool was depleted after the addition of exogenous HMW HA and was accompanied by enhanced proteolytic processing and secretion of de novo synthesized versican, much of which was associated with endosomal compartments. No changes were detected in synthesis, secretion, or proteolytic processing of aggrecan or lubricin (PRG4). The addition of HMW HA also modulated a range of LPS-affected genes in the TLR signaling and phagocytosis pathways, as well as endogenous HA metabolism genes, such as Has1, Hyal1, Hyal2, and Tmem2. However, there was no evidence for association of endogenous or exogenous HMW HA with cell surface CD44, TLR2 or TLR4 protein, suggesting that its physiochemical effects on pericelluar pH and/or ionic strength might be the primary modulators of signal transduction and vesicular trafficking by this cell type. We discuss the implications of these findings in terms of a potential in vivo effect of therapeutically applied HMW HA on the modification of osteoarthritis-related joint pathologies, such as pro-inflammatory and degradative responses of multipotent mesenchymal cells residing in the synovial membrane, the underlying adipose tissue, and the articular cartilage surface.

The TTR (transforming growth factor β1 (TGFβ1) injection with treadmill running) model of murine joint injury was used to examine effects of intra-articular Hyaluronan (IA HA) on the metabolism of subchondral bone. HA was injected 24 h after TGFβ1 injection and its effects on the mRNA of 80 genes in the Nfkb pathway, and bone remodeling genes, Acp5, Nos2 and Arg1, in femoral and tibial epiphyses/metaphyses of injected and contralateral legs was assessed. Structural bone parameters at those sites were determined by Micro-computed tomography (micro CT) and bone remodeling cells identified with histochemistry for tartrate-resistant acid phosphatase and immunohistochemistry for Nitric oxide synthase 2 (NOS2) and Arginase 1. Gene expression responses in femoral compartments were generally inhibitory and notably biphasic whereas the tibia was relatively non-responsive. Gene expression was also altered in the contralateral femoral compartment but were predominantly activated. IA TGFb did not alter bone structure in the injected leg, but resulted in a statistically significant reduction (25-40%) in trabecular bone of the contralateral limb. IA HA did not affect such changes. This bone loss was associated with an acute decrease in transcript abundance for Acp5, Nos2, Arg1 and this decrease persisted for Nos2 and Arg1. In conclusion, the data illustrate that in this model, IA TGFβ1 injection results in marked biphasic changes in NfKb-regulated apoptosis, IL1 and IL12 pathways, which were transiently altered after IA HA therapy. The finding that all modulations are essentially restricted to the femoral compartment is consistent with the predominant localization and clearance of injected HA from this site.

Objective: To obtain dense spatiotemporal measurements of brain deformation from two distinct but complementary head motion experiments: linear and rotational accelerations. Methods: This study introduces a strategy for integrating harmonic phase analysis of tagged magnetic resonance imaging (MRI) and finite-element models to extract mechanically representative deformation measurements. The method was calibrated using simulated as well as experimental data, demonstrated in a phantom including data with image artifacts, and used to measure brain deformation in human volunteers undergoing rotational and linear acceleration. Results: Evaluation methods yielded a displacement error of 1.1 mm compared to human observers and strain errors between ${\text{0.1}}\pm {\text{0.2}}{\% \,(\text{mean}\pm \text{std}.\,\text{dev.)}}$ for linear acceleration and ${\text{0.7}}\pm {\text{0.3}}\% $ for rotational acceleration. This study also demonstrates an approach that can reduce error by 86% in the presence of corrupted data. Analysis of results shows consistency with 2-D motion estimation, agreement with external sensors, and the expected physical behavior of the brain. Conclusion: Mechanical regularization is useful for obtaining dense spatiotemporal measurements of in vivo brain deformation under different loading regimes. Significance: The measurements suggest that the brain's 3-D response to mild accelerations includes distinct patterns observable using practical MRI resolutions. This type of measurement can provide validation data for computer models for the study of traumatic brain injury.

Noninvasive measurements of tissue deformation provide biomechanical insights of an organ, which can be used as clinical functional biomarkers or experimental data for validating computational simulations. However, acquisition of 3D displacement information is susceptible to experimental inconsistency and limited scan time. In this research, we describe the process of tracking tagged magnetic resonance imaging (MRI) as enforcing harmonic phase conservation in finite-element (FE) models. This concept is demonstrated as a tool for motion estimation in an experimental brain phantom, and images from the human heart and tongue. Our results demonstrate that the new methodology offers robustness to edge and large-displacement artifacts, and that it can be seamlessly coupled with numerical simulations for estimating fiber stretch in residually stressed tissue, or for inverse identification of muscle activation.

ABSTRACTArticular cartilage lines the load‐bearing surfaces of long bones and undergoes compositional and structural degeneration during osteoarthritis progression. Contrast enhanced microcomputed tomography (μCT) is being applied to a variety of preclinical models, including the mouse, to map structural and compositional properties in 3‐D. The thinness (∼30–50 μm) and high cellularity of mouse articular cartilage presents a significant imaging challenge. Our group previously showed that mouse articular cartilage and proteoglycan (PG) content can be assessed by μCT with the ioxagalate‐based contrast agent Hexabrix, but the voxel size used (6 μm) was deemed to be barely adequate. The objective of the present study is to assess the utility of a novel contrast agent, CA4+, to quantify mouse articular cartilage morphology and composition with high resolution μCT imaging (3 μm voxels) and to compare the sensitivity of CA4+ and Hexabrix to detect between‐group differences. While both contrast agents are iodine‐based, Hexabrix is anionic and CA4+ is cationic so they interact differently with negatively charged PGs. With CA4+, a strong correlation was found between non‐calcified articular cartilage thickness measurements made with histology and μCT (R2 = 0.72, p < 0.001). Cartilage degeneration—as assessed by loss in volume, thickness, and PG content—was observed in 34‐week‐old mice when compared to both 7‐ and 12‐week‐old mice. High measurement precision was observed with CA4+, with the coefficient of variation after repositioning and re‐imaging samples equaling 2.8%, 4.5%, 7.4% and 5.9% for attenuation, thickness, volume, and PG content, respectively. Use of CA4+ allowed increased sensitivity for assessing PG content compared to Hexabrix, but had no advantage for measurement of cartilage thickness or volume. This improvement in imaging should prove useful in preclinical studies of cartilage degeneration and regeneration. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2740–2748, 2017.

In traumatic brain injury (TBI), rapid head acceleration resulting from a blow or fall results in detrimental brain tissue deformation. These types of injuries are frequent and can have devastating effects. Understanding the relationship between acceleration and deformation is a challenging and essential step towards designing effective preventive strategies. This study describes patterns of acceleration-induced brain deformation in a group of human volunteers (n = 7). Unlike previous research, the analysis herein involved spatiotemporal analysis of 3D kinematics. In each subject, tagged magnetic resonance imaging (MRI) was acquired during a mild acceleration event, and displacements were extracted using a mechanically regularized motion estimation algorithm. This technique involved registering an anatomical template (a finite-element mesh) to all of the subjects allowing translation of scalar strain projections back to the template to be averaged. Our results show that, in individuals, weighting acceleration measurements by the subject’s brain volume improves the correlation between acceleration magnitude and deformation (R2 of 0.66 in the weighted comparison, compared to 0.34). In individuals, and the group, brain deformation peaked after the peak acceleration, and near the interface between the brain and the skull. However, some deformation was also observed near medial brain structures, which supports the idea that the falx plays a role in transferring mechanical power to the middle of the brain.