Ground reaction force estimates from ActiGraph GT3X+ hip accelerations.

Simple methods to quantify ground reaction forces (GRFs) outside a laboratory setting are needed to understand daily loading sustained by the body. Here, we present methods to estimate peak vertical GRF (pGRFvert) and peak braking GRF (pGRFbrake) in adults using raw hip activity monitor (AM) acceleration data. The purpose of this study was to develop a statistically based model to estimate pGRFvert and pGRFbrake during walking and running from ActiGraph GT3X+ AM acceleration data. 19 males and 20 females (age 21.2 ± 1.3 years, height 1.73 ± 0.12 m, mass 67.6 ± 11.5 kg) wore an ActiGraph GT3X+ AM over their right hip. Six walking and six running trials (0.95-2.19 and 2.20-4.10 m/s, respectively) were completed. Average of the peak vertical and anterior/posterior AM acceleration (ACCvert and ACCbrake, respectively) and pGRFvert and pGRFbrake during the stance phase of gait were determined. Thirty randomly selected subjects served as the training dataset to develop generalized equations to predict pGRFvert and pGRFbrake. Using a holdout approach, the remaining 9 subjects were used to test the accuracy of the models. Generalized equations to predict pGRFvert and pGRFbrake included ACCvert and ACCbrake, respectively, mass, type of locomotion (walk or run), and type of locomotion acceleration interaction. The average absolute percent differences between actual and predicted pGRFvert and pGRFbrake were 8.3% and 17.8%, respectively, when the models were applied to the test dataset. Repeated measures generalized regression equations were developed to predict pGRFvert and pGRFbrake from ActiGraph GT3X+ AM acceleration for young adults walking and running. These equations provide a means to estimate GRFs without a force plate

The Future of Agriculture in Our Community: A Pilot Program to Increase Community Dialogue About Agricultural Sustainability

The Future of Agriculture in Our Community is a program developed to allow Pennsylvania communities to assess and address the needs of local agriculture. This article describes the program in detail and provides results from an evaluation conducted of the pilot program. Findings (n=55) suggest that the program was received very well among participants and seemed to increase community organization skills, knowledge of local agriculture, interest in agriculture and in community life, and intentions to participate in future volunteer efforts. Based on these results, recommendations are offered for those interested in pursuing similar programs

DIET INDUCED OBESITY MAY AFFECT THE FORCE-VELOCITY RELATIONSHIP IN RAT SOLEUS

INTRODUCTION Obesity is associated with chronic, low-grade inflammation that has been shown to affect several musculoskeletal tissues [1].  Previously, we observed that diet induced obesity (DIO) using a high-fat, high sugar diet results in molecular and morphological alterations in muscles, including an increase in intramuscular fat. However, it remains unclear if these alterations affect muscle function, as few studies have characterized the functional properties of muscles in obese individuals [2]. Arguably, one of the most important functional properties of skeletal muscle is the force-velocity relationship (FVR).  When muscles are shortening at increasing velocities, force decays exponentially as the proportion of attached cross bridges and the average force per cross-bridge decreases. As fat infiltration reduces the contractile material and structure of obese muscles, the functional properties of muscles, specifically the FVR may be affected. Therefore, the purpose of this study was to characterize the FVR in rat soleus muscles obtained from obese and normal rats. We hypothesized that soleus muscles of obese rats would produce lower absolute and relative forces at any given shortening velocity compared with muscles from control animals. METHODS Outbred, individually housed male Sprague-Dawley rats, aged 10-12 weeks, were randomized to a high fat, high sugar diet (DIO, 40% fat 45% sucrose, n=9) or a standard chow diet (n=5, chow, 12% fat, 0% sucrose) for 12 weeks. Prior to surgery, animals were sedated, weighed, and body composition was quantified using dual energy X-ray absorptiometry. The right soleus muscle was exposed and a custom cuff-type electrode was implanted on the tibial nerve. The soleus tendon was isolated from the Achilles with the calcaneus attached and fixed to a motor along the muscle’s natural alignment. The muscle was then stretched to its optimum length and electrically stimulated at 35Hz at 2.5x the motor unit threshold [3]. An isometric force reading was acquired over 2.5 s stimulation. The soleus was then stretched past its optimum length and shortened at increasing velocities, a force reading was collected at optimal length using Windaq Software. Data were collected at 1000Hz. Forces during shortening were measured at the same length and time point as the isometric reference force. This process was repeated for shortening velocities increasing from 2 mm/s to 70 mm/s. Animals were sacrificed and soleus muscles were harvested and weighed. Data were processed using a custom Matlab ® zero-phase filter program. Instantaneous forces were normalized to the peak isometric force for each animal. Comparisons were made using a Student’s t-tests, α=0.05. RESULTS On average, DIO animals had higher body mass and body fat compared to the control rats (p<0.001). Soleus mass was similar between DIO animals and chow (p=0.321), as was peak active isometric force (DIO: 2.48±0.10 N, chow: 2.08±0.33 p=0.183). FVR relationships were statistically different at shortening velocities between 3 and 35 mm/s (DIO > Chow at each given velocity; p<0.05, Fig. 1). DISCUSSION The results opposed the expected outcomes of this study and, therefore, the hypothesis was not satisfied. These findings could be due to a higher proportion of fast twitch fibers in the DIO or longer fascicle lengths in the DIO rats, but these speculations remain to be tested. Another possible explanation involves a potential increase in sensitivity to stimulation in the DIO soleus muscle resulting in increased force. Future work will examine other structural levels and muscle contractile proteins to understand these preliminary findings

FUNCTIONAL EFFECTS OF DIET INDUCED OBESITY ON PERMEABLIZED RAT MUSCLE FIBRES

INTRODUCTION Muscle performance is determined by the metabolic, calcium handling, and sarcomeric characteristics of its constituent fibres. Diet induced obesity (DIO) may influence contractile performance in whole muscle, but little is known about the effects of DIO at the single fibre level. Particularly, how DIO might influence the contractile characteristics of single fibres free from the influence of metabolic or calcium handling properties is not established. There is some limited evidence to suggest that DIO may influence the sarcomeric proteins. For example, troponin T, an important regulatory protein found on the thin filament, exhibits a shift from the fast T3 isoform, to the slow T1 isoform, in mouse soleus muscle following high fat feeding, with no associated change in myosin heavy chain isoform [1]. These results suggest that DIO may cause fast fibres to express slow isoforms of sarcomeric proteins in postural muscles of mixed fibre-type. The purpose of this study was to assess the force-calcium and force-velocity relationships of skinned fast and slow fibres of vastus intermedius, a mixed fibre-type postural muscle [2], in chow-fed rats and a rat model of DIO. It was hypothesized that fast fibres from DIO rats would exhibit characteristics associated with a slower fibre phenotype, including increased calcium sensitivity and lower shortening velocities. METHODS Individually housed male Sprague-Dawley rats, aged 10-12 weeks, were randomized to undergo diet induced obesity (DIO) where they were fed a high fat, high sugar diet (n = 6) or a standard chow diet (n = 6) for 12 weeks. The caloric content of DIO diets was 40% fat and 45% sucrose, compared to chow diets which consisted of 12% fat and 0% sucrose. Both vastus intermedius muscles were collected from each rat. Similar to the mouse soleus, the fibre type distribution of rat vastus intermedius is approximately 50% type I and 50% type IIa fibres [2]. Muscles were chemically skinned in a glycerol-rigor solution for 2 weeks.  Two fast and two slow fibres per animal were then isolated and mounted in a model 802B skinned fibre test system (Aurora Scientific) at 2.4 µm sarcomere length for testing.  Preliminary fibre type assessment was made using a strontium sensitivity test [3].  The force-pCa relationship was assessed from pCa 7.2 to pCa 4.2. The force-velocity relationship was assessed by measuring the shortening velocity during isotonic contractions.  Maximal shortening velocity (Vmax) was assessed by a slack test protocol. Statistical differences were determined using Student’s t-test or a two-way factorial ANOVA and Newman-Keuls post-hoc analysis as appropriate, α = 0.05. RESULTS Dual-energy X-ray absorptiometry scans revealed DIO rats had significantly higher body mass, fat mass, and greater percent body fat than chow fed rats (all p<0.05), while lean mass was not significantly different between groups. DIO did not affect the force per cross-sectional area (CSA) of skinned fibres (Table 1). Fast DIO fibres had significantly lower maximum shortening velocities when compared to fast chow fibres (p<0.05; Table 1). No such differences were observed in slow fibres. Independent of fibre type, DIO fibres had significantly higher calcium sensitivity than chow fibres (p<0.01, Table 1).  While the Hill coefficient of the force pCa relationship was different between fast and slow chow fibres, no differences were seen in DIO fibres (p<0.05; Table 1).DISCUSSION AND CONCLUSIONS Consistent with a fast to slow phenotype transition, Vmax was lower in fast DIO fibres. However, DIO influenced the force-calcium relationship of both fast and slow fibres. Therefore, adaptations are not limited to fast fibres, but rather influence contractility on a larger scale. Whether this influence is global or localized to postural muscles remains to be determined. The specific isoforms of contractile proteins expressed in single fibres should be assessed following DIO

Taxonomic changes in the gut microbiota are associated with cartilage damage independent of adiposity, high fat diet, and joint injury

Abstract Lipodystrophic mice are protected from cartilage damage following joint injury. This protection can be reversed by the implantation of a small adipose tissue graft. The purpose of this study was to evaluate the relationship between the gut microbiota and knee cartilage damage while controlling for adiposity, high fat diet, and joint injury using lipodystrophic (LD) mice. LD and littermate control (WT) mice were fed a high fat diet, chow diet, or were rescued with fat implantation, then challenged with destabilization of the medial meniscus surgery to induce osteoarthritis (OA). 16S rRNA sequencing was conducted on feces. MaAslin2 was used to determine associations between taxonomic relative abundance and OA severity. While serum LPS levels between groups were similar, synovial fluid LPS levels were increased in both limbs of HFD WT mice compared to all groups, except for fat transplanted animals. The Bacteroidetes:Firmicutes ratio of the gut microbiota was significantly reduced in HFD and OA-rescued animals when compared to chow. Nine novel significant associations were found between gut microbiota taxa and OA severity. These findings suggest the presence of causal relationships the gut microbiome and cartilage health, independent of diet or adiposity, providing potential therapeutic targets through manipulation of the microbiome

THE EFFECTS OF DIET INDUCED OBESITY ON THE FORCE-LENGTH RELATIONSHIP IN RAT SOLEUS

INTRODUCTION Obesity is associated with chronic inflammation, which has been shown to affect the integrity of musculoskeletal tissues [1]. Previous data from our group suggests that obesity can result in intramuscular fat deposition [1]. It is unclear if this structural alteration has functional consequences, as the implications of obesity on muscle mechanics are not well understood. Therefore, the purpose of this study was to quantify the active force produced by soleus muscles of obese and non-obese rats at a range of muscle lengths. As the inclusion of fat into the muscle fibers will leave less room for contractile proteins, we hypothesized that obese rats will produce lower forces normalized to muscle mass at every length than non-obese control rats.   METHODS Fourteen rats were randomly allocated to a 12-week diet: either an obesity-inducing high fat high sucrose diet (DIO, 40% fat, 45% sucrose, n=8) or a standard chow diet (chow, 12% fat 0% sucrose, n=6). Prior to surgery, body composition was evaluated using dual energy X-ray absorptiometry. Custom-made tibial nerve cuffs were surgically attached to the right tibial nerve of each animal. The soleus was exposed, mechanically isolated, and clamped to a force transducer. The muscle was then stretched to a predetermined length and electrically stimulated at 3 times the motor unit threshold (50Hz) and the force output was measured [3]. Force tracings were digitized using WINDAQ® software. Passive, active, and total forces produced by the soleus were normalized to the maximum in vivo length of each animal. Forces were averaged into 5% length intervals within each animal. Students t-tests or a two-way ANOVA were conducted between groups, and a Bonferroni correction was used as needed, α=0.05. RESULTS DIO rats had increased body mass (DIO 816.4 ± 30.1g, chow 645.0 ± 28.3g; p<0.05) and body fat (DIO 39.2 ± 1.3%, chow 21.8 ± 2.1%; p<0.05) compared to chow-fed rats. Soleus mass (DIO: 0.28 ± 0.01 g, chow: 0.26 ± 0.11 g, p=0.32), was similar between the two groups. Absolute peak isometric force was similar between the two groups (DIO: 2.58 ± 0.10 N, chow: 2.18 ± 0.34 N, p=0.23). Active isometric force normalized to soleus mass was significantly higher in DIO group rats at every muscle length (Figure 1, p<0.05). DISCUSSION AND CONCLUSIONS On average, DIO rats produced more active force at a given normalized length and soleus mass than chow rats, a finding that refutes our original hypothesis. Since optimal length occurs at the same relative muscle length for both groups, and since the decline in force from maximum is similar between groups, it appears that fascicle length, and an associated shift in the force-length relationship cannot explain our results. Results of differences in the force-velocity relationship (not shown here) suggest that the DIO rats may have a higher proportion of fast twitch fibres, but the relative force among slow and fast fibres is similar, and thus also should not affect these results. The results suggest that the force per cross-sectional area is higher in muscles from obese compared to lean rats, a finding that defies explanation at this time and needs thorough investigation in the future. Histology and tests looking at fibre and cell level muscle structures may provide more insight

Gene therapy for follistatin mitigates systemic metabolic inflammation and post-traumatic arthritis in high-fat diet-induced obesity

Obesity-associated inflammation and loss of muscle function play critical roles in the development of osteoarthritis (OA); thus, therapies that target muscle tissue may provide novel approaches to restoring metabolic and biomechanical dysfunction associated with obesity. Follistatin (FST), a protein that binds myostatin and activin, may have the potential to enhance muscle formation while inhibiting inflammation. Here, we hypothesized that adeno-associated virus 9 (AAV9) delivery of FST enhances muscle formation and mitigates metabolic inflammation and knee OA caused by a high-fat diet in mice. AAV-mediated FST delivery exhibited decreased obesity-induced inflammatory adipokines and cytokines systemically and in the joint synovial fluid. Regardless of diet, mice receiving FST gene therapy were protected from post-traumatic OA and bone remodeling induced by joint injury. Together, these findings suggest that FST gene therapy may provide a multifactorial therapeutic approach for injury-induced OA and metabolic inflammation in obesity

Nanotherapy targeting NF-κB attenuates acute pain after joint injury

Inflammation after joint injury leads to joint responses that result in eventual osteoarthritis development. Blockade of inflammation, by suppressing NF-κB expression, has been shown to reduce joint injury-induced chondrocyte apoptosis and reactive synoviti

Co-constructing Simulations with Learners: Roles, Responsibilities, and Impact

Co-constructed simulations were designed and piloted with senior occupational therapy master’s students in a neurorehabilitation practice module. The instructor served as the guide for the students through all phases of the case creation, simulation development, delivery, and debrief. The instructor facilitation promoted self-regulated learning (SRL) of knowledge and skill development through independent discovery and peer learning. This paper provides an evidence-informed co-construction simulation design with outlined stages, roles, and responsibilities for the instructor and learner. Thematic qualitative analysis of student feedback highlighted enhanced insight and SRL as a result of multiple role preparation, observation and interaction with peers, close interaction with the instructor, and the multi-stage debrief process. Recommended key features and critical interactions for a successful co-constructed design are also identified for the learner, instructor, and simulation. The co-construction simulation process and design elements are suitable for learners in any health-related field of study

Hydrogel encapsulation of genome-engineered stem cells for long-term self-regulating anti-cytokine therapy

Biologic therapies have revolutionized treatment options for rheumatoid arthritis (RA) but their continuous administration at high doses may lead to adverse events. Thus, the development of improved drug delivery systems that can sense and respond commensurately to disease flares represents an unmet medical need. Toward this end, we generated induced pluripotent stem cells (iPSCs) that express interleukin-1 receptor antagonist (IL-1Ra, an inhibitor of IL-1) in a feedback-controlled manner driven by the macrophage chemoattractant protein-1 (Ccl2) promoter. Cells were seeded in agarose hydrogel constructs made from 3D printed molds that can be injected subcutaneously via a blunt needle, thus simplifying implantation of the constructs, and the translational potential. We demonstrated that the subcutaneously injected agarose hydrogels containing genome-edited Ccl2-IL1Ra iPSCs showed significant therapeutic efficacy in the K/BxN model of inflammatory arthritis, with nearly complete abolishment of disease severity in the front paws. These implants also exhibited improved implant longevity as compared to the previous studies using 3D woven scaffolds, which require surgical implantation. This minimally invasive cell-based drug delivery strategy may be adapted for the treatment of other autoimmune or chronic diseases, potentially accelerating translation to the clinic