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Neuroma formation following limb amputation is a prevalent and debilitating condition that can deeply affect quality of life and productivity. Several approaches exist to prevent or treat neuromas; however, no approach is either consistently reliable or surgically facile, with high rates of neuroma occurrence and/or recurrence. The present study describes the development and testing of a xenogeneic nerve cap graft made from decellularized porcine nerve. The grafts were tested in vitro for cellular removal, cytotoxicity, mechanical properties, and morphological characteristics. The grafts were then tested in rat sciatic nerve gap reconstruction and nerve amputation models for 8 weeks. Gross morphology, electrophysiology, and histopathology assessments were performed to determine the ability of the grafts to limit pathologic nerve regrowth. In vitro testing showed well decellularized and demyelinated nerve cap graft structures without any cytotoxicity from residual reagents. The grafts had a proximal socket for the proximal nerve stump and longitudinally oriented internal pores. Mechanical and surgical handling properties suggested suitability for implantation as a nerve graft. Following 8 weeks in vivo, the grafts were well integrated with the proximal and distal nerve segments without evidence of fibrotic adhesions to the surrounding tissues or bulbous outgrowth of the nerve. Electrophysiology revealed absence of nerve conduction within the remodeled nerve cap grafts and significant downstream muscle atrophy. Histologic evaluation showed well organized but limited axonal regrowth within the grafts without fibrous overgrowth or neuromatous hypercellularity. These results provide proof of concept for a novel xenograft‐based approach to neuroma prevention. [ABSTRACT FROM AUTHOR]

The rat surgical anterior cruciate ligament transection (ACLT) model is commonly used to investigate intra‐articular osteoarthritis (OA) therapies, and histological assessment is often the primary outcome measure. However, histological changes do not always correlate well with clinical outcomes. Therefore, this study evaluated functional outcomes in the rat surgical ACLT model and compared intra‐articular injection volumes ranging from 20 to 50 μl. Unilateral ACLT was surgically induced and static weight‐bearing, mechanical allodynia, motor function, and gait were assessed in four groups of male, Sprague‐Dawley rats (n = 6 per group). Intra‐articular injections of 20 µl Dulbecco's phosphate‐buffered saline (DPBS), 50 µl DPBS, or 50 µl of synthetic biomimetic boundary lubricant were administered once weekly for 3 weeks postoperatively. Structural changes were evaluated histologically at 20 weeks. Rat cadaver knees were injected with 20, 30, 40, or 50 µl of gadolinium solutions and were imaged using magnetic resonance imaging (MRI). Static weight‐bearing, mechanical allodynia, and gait parameters in ACLT groups revealed differences from baseline and naïve controls for 4 weeks post‐ACLT; however, these differences did not persist beyond 6 weeks. Different intra‐articular DPBS injection volumes did not result in functional or histological changes; however, peri‐articular leakage was documented via MRI following 50, 40, and 30 µl but not 20 µl gadolinium injections. Statement of clinical significance: Differences in functional parameters were predominantly restricted to early, postoperative changes in the rat surgical ACLT model despite evidence of moderate histologic OA at 20 weeks. Injection volumes of 20–30 µl are more appropriate for investigating intra‐articular therapies in the rat knee. [ABSTRACT FROM AUTHOR]

Introduction/Aims: While the peripheral nervous system has the inherent ability to recover following injury, results are often unsatisfactory, resulting in permanent functional deficits and disability. Therefore, methods that enhance regeneration are of significant interest. The present study investigates an injectable nerve‐tissue‐specific hydrogel as a biomaterial for nerve regeneration in a rat nerve crush model. Methods: Nerve‐specific hydrogels were injected into the subepineurial space in both uninjured and crushed sciatic nerves of rats to assess safety and efficacy, respectively. The animals were followed longitudinally for 12 wk using sciatic functional index and kinematic measures. At 12 wk, electrophysiologic examination was also performed, followed by nerve and muscle histologic assessment. Results: When the hydrogel was injected into an uninjured nerve, no differences in sciatic functional index, kinematic function, or axon counts were observed. A slight reduction in muscle fiber diameter was observed in the hydrogel‐injected animals, but overall muscle area and kinematic function were not affected. Hydrogel injection following nerve crush injury resulted in multiple modest improvements in sciatic functional index and kinematic function with an earlier return to normal function observed in the hydrogel treated animals as compared to untreated controls. While no improvements in supramaximal compound motor action potential were observed in hydrogel treated animals, increased axon counts were observed on histologic assessment. Discussion: These improvements in functional and histologic outcomes in a rapidly and fully recovering model suggest that injection of a nerve‐specific hydrogel is safe and has the potential to improve outcomes following nerve injury. [ABSTRACT FROM AUTHOR]

Progression of unilateral laryngeal paralysis (LP) was quantified in an asymptomatic 4‐year‐old beagle during spontaneous breathing stimulated with inhaled 10% CO2. Laryngeal evaluation was performed sequentially to track progression of LP over an 18‐month period. Videos of the larynx during CO2‐stimulated breathing were obtained under propofol anaesthesia. Maximal inspiratory normalised glottal gap area (NGGA) was determined on each occasion for left and right hemiglottis. Left NGGA was smaller than the right side throughout the period of follow‐up. After 18 months, LP had progressed to such a degree that the left arytenoid was completely paralysed with no movement during inspiration. This case report demonstrates the possibility of early detection of LP, and quantification of progression. Early detection may allow regenerative surgical strategies for LP to maintain glottic area and reduce postoperative complication rates. [ABSTRACT FROM AUTHOR]

Background: Degenerative myelopathy (DM) in dogs is a progressive neurodegenerative condition that causes white matter spinal cord lesions. These lesions are undetectable on standard magnetic resonance imaging (MRI), limiting diagnosis and monitoring of the disease. Spinal cord lesions cause disruption to the structural integrity of the axons causing water diffusion to become more random and less anisotropic. These changes are detectable by the technique of diffusion tensor imaging (DTI) which is highly sensitive to diffusion alterations secondary to white matter lesion development. Objective: Perform spinal DTI on cohorts of dogs with and without DM to identify if lesions caused by DM will cause a detectable alteration in spinal cord diffusivity that correlates with neurological status. Animals Thirteen dogs with DM and 13 aged‐matched controls. Methods: All animals underwent MRI with DTI of the entire spine. Diffusivity parameters fractional anisotropy (FA) and mean diffusivity (MD) were measured at each vertebral level and statistically compared between groups. Results: Dogs with DM had significant decreases in FA within the regions of the spinal cord that had high expected lesion load. Decreases in FA were most significant in dogs with severe forms of the disease and correlated with neurological grade. Conclusions and Clinical Importance: Findings suggest that FA has the potential to be a biomarker for spinal cord lesion development in DM and could play an important role in improving diagnosis and monitoring of this condition. [ABSTRACT FROM AUTHOR]

Currently available software tools for automated segmentation and analysis of muscle cross-section images often perform poorly in cases of weak or non-uniform staining conditions. To address these issues, our group has developed the MyoSAT (Myofiber Segmentation and Analysis Tool) image-processing pipeline. MyoSAT combines several unconventional approaches including advanced background leveling, Perona-Malik anisotropic diffusion filtering, and Steger's line detection algorithm to aid in pre-processing and enhancement of the muscle image. Final segmentation is based upon marker-based watershed segmentation. Validation tests using collagen V labeled murine and canine muscle tissue demonstrate that MyoSAT can determine mean muscle fiber diameter with an average accuracy of ~92.4%. The software has been tested to work on full muscle cross-sections and works well even under non-optimal staining conditions. The MyoSAT software tool has been implemented as a macro for the freely available ImageJ software platform. This new segmentation tool allows scientists to efficiently analyze large muscle cross-sections for use in research studies and diagnostics. [ABSTRACT FROM AUTHOR]

Exercise induced intermittent dorsal displacement of the soft palate (DDSP) is a common cause of airway obstruction and poor performance in racehorses. The definite etiology is still unclear, but through an experimental model, a role in the development of this condition was identified in the dysfunction of the thyro-hyoid muscles. The present study aimed to elucidate the nature of this dysfunction by investigating the spontaneous response to exercise of the thyro-hyoid muscles in racehorses with naturally occurring DDSP. Intramuscular electrodes were implanted in the thyro-hyoid muscles of nine racehorses, and connected to a telemetric unit for electromyographic monitoring implanted subcutaneously. The horses were recruited based on upper airway function evaluated through wireless endoscopy during exercise. Five horses, with normal function, were used as control; four horses were diagnosed as DDSP-affected horses based on repeated episodes of intermittent dorsal displacement of the soft palate. The electromyographic activity of the thyro-hyoid muscles recorded during incremental exercise tests on a high-speed treadmill was analyzed to measure the mean electrical activity and the median frequency of the power spectrum, thereafter subjected to wavelet decomposition. The affected horses had palatal instability with displacement on repeated exams prior to surgical implantation. Although palatal instability persisted after surgery, only two of these horses displaced the palate after instrumentation. The electromyographic traces from this group of four horses showed, at highest exercise intensity, a decrease in mean electrical activity and median power frequency, with progressive decrease in the contribution of the high frequency wavelets, consistent with development of thyro-hyoid muscle fatigue. The results of this study identified fatigue as the main factor leading to exercise induced palatal instability and DDSP in a group of racehorses. Further studies are required to evaluate the fiber type composition and metabolic characteristics of the thyro-hyoid muscles that could predispose to fatigue. [ABSTRACT FROM AUTHOR]

Introduction: Controversy exists over the effects of functional electrical stimulation (FES) on reinnervation. We hypothesized that intramuscular FES would not delay reinnervation after recurrent laryngeal nerve (RLn) axonotmesis.Methods: RLn cryo-injury and electrode implantation in ipsilateral posterior cricoarytenoid muscle (PCA) were performed in horses. PCA was stimulated for 20 weeks in eight animals; seven served as controls. Reinnervation was monitored through muscle response to hypercapnia, electrical stimulation and exercise. Ultimately, muscle fiber type proportions and minimum fiber diameters, and RLn axon number and degree of myelination were determined.Results: Laryngeal function returned to normal in both groups within 22 weeks. FES improved muscle strength and geometry, and induced increased type I:II fiber proportion (p = 0.038) in the stimulated PCA. FES showed no deleterious effects on reinnervation.Discussion: Intramuscular electrical stimulation did not delay PCA reinnervation after axonotmesis. FES can represent a supportive treatment to promote laryngeal functional recovery after RLn injury. Muscle Nerve 59:717-725, 2019. [ABSTRACT FROM AUTHOR]

This publication offers modern, state‐of‐the‐art International Neural Monitoring Study Group (INMSG) guidelines based on a detailed review of the recent monitoring literature. The guidelines outline evidence‐based definitions of adverse electrophysiologic events, especially loss of signal, and their incorporation in surgical strategy. These recommendations are designed to reduce technique variations, enhance the quality of neural monitoring, and assist surgeons in the clinical decision‐making process involved in surgical management of recurrent laryngeal nerve. The guidelines are published in conjunction with the INMSG Guidelines Part II, Optimal Recurrent Laryngeal Nerve Management for Invasive Thyroid Cancer–Incorporation of Surgical, Laryngeal, and Neural Electrophysiologic Data. Laryngoscope, 128:S1–S17, 2018 [ABSTRACT FROM AUTHOR]

Peripheral nerve possesses the inherent ability to regrow and recover following injury. However, nerve regeneration is often slow and incomplete due to limitations associated with the local microenvironment during the repair process. Manipulation of the local microenvironment at the site of nerve repair, therefore, represents a significant opportunity for improvement in downstream outcomes. Macrophages and Schwann cells play a key role in the orchestration of early events after peripheral nerve injury. We describe the production, characterization, and use of an injectable, peripheral nerve-specific extracellular matrix-based hydrogel (PNSECM) for promoting modulation of the local macrophage and Schwann cell responses at the site of nerve repair in a rodent model of sciatic nerve injury. We show that PNSECM hydrogels largely maintain the matrix structure associated with normal native peripheral nerve tissue. PNSECM hydrogels were also found to promote increased macrophage invasion, higher percentages of M2 macrophages and enhanced Schwann cell migration when used as a lumen filler in a rodent model of nerve gap repair using an inert nerve guidance conduit. These results suggest that an injectable PNSECM hydrogel can provide a supportive, bioactive scaffold which promotes repair of peripheral nerve in vivo. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 450-459, 2018. [ABSTRACT FROM AUTHOR]

Objectives/hypothesis: The trachea is essential to respiratory function and is a mechanically and biochemically complex composite tissue. Tissue-engineering approaches to treat tracheal diseases require detailed knowledge of the native mechanical and biochemical properties of the trachea. Although the porcine trachea represents an excellent preclinical model, relevant mechanical and biochemical composition are incompletely characterized.Study Design: Experimental. The mechanical and biochemical properties of 12 intact porcine tracheas were determined to characterize their compliance, as well as the aggregate modulus, bidirectional elastic modulus, hydraulic permeability, and biochemical characteristics of individual cartilage rings.Results: Data demonstrate the glycosaminoglycan content of tracheal rings was (mean ± standard deviation) 190 ± 49 μg/mg. Hydroxyproline content was 8.2 ± 3.2 μg/mg, and DNA content was 1.3 ± 0.27 μg/mg, a four-fold difference between circumferential elastic modulus (5.6 ± 2.0 megapascal [MPa]) and longitudinal composite elastic modulus (1.1 ± 0.7 MPa, P < 0.0001) was also observed. Aggregate modulus (stiffness) of porcine tracheal rings was 1.30 ± 0.28 MPa, and inflationary compliance was 0.00472 ± 0.00188 cmH2 O(-1) .Conclusion: This study presents a comprehensive characterization of the relevant biochemical and mechanical properties of porcine tracheal cartilage, which is considered an excellent candidate for xenogenic tracheal graft and a source for tissue-engineered tracheal reconstruction. The range of parameters characterized in this study agrees with those reported for hyaline cartilage of the airway in other species. These characteristics can be used as quantitative benchmarks for tissue-engineering approaches to treat tracheal disease.Level Of Evidence: NA. Laryngoscope, 126:E325-E331, 2016. [ABSTRACT FROM AUTHOR]

OBJECTIVE To evaluate whether the ultrashort-acting neuromuscular blocking agent gantacurium can be used to blunt evoked laryngospasm in anesthetized cats and to determine the duration of apnea without hemoglobin desaturation. ANIMALS 8 healthy adult domestic shorthair cats. PROCEDURES Each cat was anesthetized with dexmedetomidine and propofol, instrumented with a laryngeal mask, and allowed to breathe spontaneously (fraction of inspired oxygen, 1.0). The larynx was stimulated by spraying sterile water (0.3 mL) at the rima glottidis; a fiberscope placed in the laryngeal mask airway was used to detect evoked laryngospasm. Laryngeal stimulation was performed at baseline; after IV administration of gantacurium at doses of 0.1, 0.3, and 0.5 mg/kg; and after the effects of the last dose of gantacurium had terminated. Duration of apnea and hemoglobin oxygen saturation (measured by means of pulse oximetry) after each laryngeal stimulation were recorded. Neuromuscular block was monitored throughout the experiment by means of acceleromyography on a pelvic limb. RESULTS Laryngospasm was elicited in all cats at baseline, after administration of 0.1 mg of gantacurium/kg, and after the effects of the last dose of gantacurium had terminated. The 0.3 and 0.5 mg/kg doses of gantacurium abolished laryngospasm in 3 and 8 cats, respectively, and induced complete neuromuscular block measured at the pelvic limb; the mean ± SE duration of apnea was 2 ± I minutes and 3 ± 1.5 minutes, respectively. Hemoglobin oxygen saturation did not decrease significantly after administration of any dose of gantacurium. CONCLUSIONS AND CLINICAL RELEVANCE Gantacurium may reduce tracheal intubation-associated morbidity in cats breathing oxygen. [ABSTRACT FROM AUTHOR]

Hypercapnia produces a profound effect on respiratory drive and upper airway function to maintain airway patency. Previous work has evaluated the effects of hypercapnia on the sole arytenoid abductor, the posterior cricoarytenoid (PCA), using indirect measures of function, such as electromyography and direct nerve recording. Here we describe a novel method to evaluate PCA function in anesthetized animals and use this method to determine the effects of hypercapnia on PCA function. Eight dogs were anesthetized, and a laryngeal mask airway was used, in combination with high-speed videoendoscopy, to evaluate laryngeal function. A stepwise increase in inspired partial pressure of CO2 produced marked arytenoid abduction above 70-mmHg end-tidal CO2 (...) (P < 0.001). Glottic length increased above 80-mmHg ... (P < 0.02), and this lead to underrepresentation of changes in glottic area, if standard measures of glottic area (normalized glottic gap area) were used. Use of a known scale to determine absolute glottic area demonstrated no plateau with increasing ... up to 120 mmHg. Ventilatory parameters also continued to increase with no evidence of a maximal response. In a second anesthetic episode, repeated bursts of transient hypercapnia for 60 s with an ... of 90 mmHg produced a 43-55% increase in glottic area (P < 0.001) at or shortly after the end of the hypercapnic burst. A laryngeal mask airway can be used in combination with videoendoscopy to precisely determine changes in laryngeal dimensions with high temporal resolution. Absolute glottic area more precisely represents PCA function than normalized glottic gap area at moderate levels of hypercapnia. [ABSTRACT FROM AUTHOR]

The article presents a study that aimed to validate a transducer which is specifically designed to measure force exerted on surgical sutures. The validation was done both in vitro as well as in ex vivo model. It concludes that short-term in vivo implantation that is properly calibrated may provide a person an advancement in knowledge in terms of techniques that use suture implants like laryngoplasty.

The equine upper airway is highly adapted to provide the extremely high oxygen demand associated with strenuous aerobic exercise in this species. The tongue musculature, innervated by the hypoglossal nerve, plays an important role in airway stability in humans who also have a highly adapted upper airway to allow speech. The role of the hypo- glossal nerve in stabilizing the equine upper airway has not been established. Isolated tongues from eight mature horses were dissected to determine the distal anatomy and branching of the equine hypoglossal nerve. Using this information, a peripheral nerve location technique was used to perform bilateral block of the common trunk of the hypoglossal nerve in 10 horses. Each horse was subjected to two trials with bilateral hypoglossal nerve block and two control trials (unblocked). Upper airway stability at exercise was determined using videoendoscopy and measurement of tracheal and pharyngeal pressure. Three main nerve branches were identified, medial and lateral branches and a discrete branch that innervated the geniohyoid muscle alone. Bilateral hypoglossal block induced nasopharyngeal instability in 10/19 trials, and none of the control trials (0/18) resulted in instability (P < 0.00 1). Mean treadmill speed (± SD) at the onset of instability was 10.8 ± 2.5 mIs. Following its onset, nasopharyngeal instability persisted until the end of the treadmill test. This instability, induced by hypoglossal nerve block, produced an expiratory obstruction similar to that seen in a naturally occurring equine disease (dorsal displacement of the soft palate, DDSP) with reduced inspiratory and expiratory pharyngeal pressure and increased expiratory tracheal pressure. These data suggest that stability of the equine upper airway at exercise may be mediated through the hypoglossal nerve. Naturally occurring DDSP in the horse shares a number of anatomic similarities with obstructive sleep apnea. Study of species with extreme respiratory adaptation, such as the horse, may provide insight into respiratory functioning in humans. [ABSTRACT FROM AUTHOR]

Objective To identify sites for arthroscopic access to the palmar aspects of the antebrachiocarpal (AC) and middle carpal (MC) joints, and describe visible carpal bone surfaces for each approach. Study Design Prospective experimental study. Animals Equine carpi: 16 cadavers, 8 live horses. Methods A latex model was used to identify possible sites for arthroscopic access to the palmar aspects of the AC and MC joints. Carpi (n=24) were examined arthroscopically and arthroscopic access sites and visible carpal bone surfaces were described. Results Arthroscopic approaches and instrument portals were developed for the medial and lateral aspects of the palmar pouches of the AC and MC joints. The palmar surface of the radial carpal bone and radius, and the dorsal articular surfaces of the accessory carpal bone, could be viewed using palmar approaches to the AC joint. The palmar aspect of the radial, third and second carpal bones (medially) and ulnar and fourth carpal bones (laterally) could be observed using a palmar approach to the MC joint. Conclusions Arthroscopic access, using separate medial and lateral portals to the AC and MC joints, allowed assessment of portions of the caudodistal radius, the palmar surfaces of the radial, ulnar, second, third and fourth carpal bones, and the dorsal aspect of the accessory carpal bone. Clinical Relevance Arthroscopic approaches to the palmar aspect of the carpus could be used to remove fracture fragments, and to assess the medial palmar intercarpal ligaments. [ABSTRACT FROM AUTHOR]

OBJECTIVE To create a model of transient unilateral laryngeal paralysis (LP) that will allow the study of cricoarytenoideus dorsalis dysfunction and a method for quantification of varying degrees of LP in dogs. ANIMALS 5 castrated male research Beagles. PROCEDURES Between January and February 2018, dogs were anesthetized and instrumented with a laryngeal mask airway and a flexible endoscope to record the rima glottidis. The left or right recurrent laryngeal nerve (RLn) was localized using ultrasonography and electrical stimulation, then conduction blockade was induced with perineural lidocaine. The normalized glottal gap area (NGGA) was measured before and every 15 minutes after the block. Inspired 10% carbon dioxide (CO2) was administered for 1 minute at each sampling time. The inspiratory increase in NGGA (total and each side) was measured at peak inspiration. The change in hemi-NGGA for the control side versus the anesthetized side was evaluated with a mixed-effect model. RESULTS During CO2 stimulation, the increase in inspiratory hemi-NGGA was consistently less (P < .001) for the treated side (–8% to 13%) versus the control side (49% to 82%). A compensatory increase (larger than at baseline) in the control hemi-NGGA was observed. The total NGGA remained unaffected. CLINICAL RELEVANCE Unilateral local anesthesia of the RLn produced transient unilateral LP with a compensatory increase in the hemiNGGA for the contralateral side. This model could facilitate the evaluation of respiratory dynamics, establishment of a grading system, and collection of other important information that is otherwise difficult to obtain in dogs with LP. [ABSTRACT FROM AUTHOR]

Background Quantification of the number of axons reinnervating a target organ is often used to assess regeneration after peripheral nerve repair, but because of axonal branching, this method can overestimate the number of motor neurons regenerating across an injury. Current methods to count the number of regenerated motor neurons include retrograde labeling followed by cryosectioning and counting labeled motor neuron cell bodies, however, the process of sectioning introduces error from potential double counting of cells in adjacent sections. New method We describe a method, retroDISCO, that optically clears whole mouse spinal cord without loss of fluorescent signal to allow imaging of retrograde labeled motor neurons using confocal microscopy. Results Complete optical clearing of spinal cords takes four hours and confocal microscopy can obtain z-stacks of labeled motor neuron pools within 3–5 min. The technique is able to detect anticipated differences in motor neuron number after cross-suture and conduit repair compared to intact mice and is highly repeatable. Comparison with existing method RetroDISCO is inexpensive, simple, robust and uses commonly available microscopy techniques to determine the number of motor neurons extending axons across an injury site, avoiding the need for labor-intensive cryosectioning and potential double counting of motor neuron cell bodies in adjacent sections. Conclusions RetroDISCO allows rapid quantification of the degree of reinnervation without the confounding produced by axonal sprouting. [ABSTRACT FROM AUTHOR]

Objective--To determine the effects of hypoglossal nerve block and electrical stimulation of the thyrohyoideus muscles on position of the larynx and hyoid apparatus in resting horses. Animals--16 healthy horses that underwent hypoglossal nerve block and 5 healthy horses that underwent electrical stimulation of the thyrohyoideus muscles. Procedures--Horses underwent bilateral hypoglossal nerve block or electrical stimulation of the thyrohyoideus muscles. Positions of the basihyoid bone, ossified part of the thyroid cartilage, and articulations of the thyrohyoid bones and thyroid cartilage were determined in radiographic images obtained before and after performance of hypoglossal nerve blocks or during thyrohyoideus muscle stimulation. Radiographic images were obtained with the heads of horses in neutral (thyrohyoideus muscle stimulation) or neutral and extended (hypoglossal nerve block) positions. Radiographic images of horses obtained after performance of hypoglossal nerve blocks were also evaluated to detect dorsal displacement of the soft palate. Results--Hypoglossal nerve blocks did not induce significant changes in the positions of evaluated anatomic sites in radiographic images obtained in neutral or extended head positions. Hypoglossal nerve block did not induce dorsal displacement of the soft palate in horses at rest. Bilateral thyrohyoideus muscle stimulation induced significant dorsal movement (mean ± SD change in position, 18.7 ± 6.8 mm) of the ossified part of the thyroid cartilage; rostral movement of evaluated anatomic structures was small and not significant after thyrohyoideus muscle stimulation. Conclusions and Clinical Relevance--Bilateral electrical stimulation of the thyrohyoideus muscles in horses in this study induced dorsal laryngeal movement. [ABSTRACT FROM AUTHOR]

Objective--To compare effects of 3 methods of topically applied cold treatment (cryotherapy) on digital laminar and venous temperatures in horses. Animals--9 healthy adult Thoroughbreds. Procedures--Thermocouples were placed in palmar digital veins and digital laminae of both forelimbs of horses. Three methods of cryotherapy were applied to the distal aspects of the limbs: wader boot (63-cm-tall vinyl boot filled with ice and water [ice slurry]), ice bag (5-L fluid bag filled with ice slurry), and a gel pack boot (boot containing frozen gel packs). Gel packs and ice slurries were replenished every hour during cryotherapy. The forelimb that received the first treatment was randomly assigned; thereafter, control and treated forelimbs were alternated for each treatment. For each treatment, temperatures were recorded every minute during 15-minute pretreatment, 2-hour treatment, and ≥ 30 minute rewarming periods. Once temperatures had returned to within 3°C below pretreatment values, the experiment was repeated in a similar manner for other cryotherapy methods. Results--Digital venous temperatures were similar to laminar temperatures during each treatment. Ice bag and wader boot treatments caused similar cooling of digits. Gel boot treatment did not cause substantial cooling of digits. Conclusions and Clinical Relevance--Ice bag treatment caused laminar and digital venous cooling equivalent to that of wader boot treatment. Cryotherapy by use of 5-L fluid bags with an ice slurry may be a readily available, practical, and efficient method for prevention of laminitis in horses. Digital laminar and venous temperatures were similar in forelimbs of horses before and during cryotherapy. [ABSTRACT FROM AUTHOR]

Objective-To investigate the efficacy and safety of a low-volume, single-catheter, continuous peripheral neural blockade (CPNB) technique to locally deliver bupivacaine to alleviate signs of severe forelimb pain resulting from experimentally induced tendonitis in horses. Design-Randomized controlled experimental trial. Sample-14 horses and 5 forelimbs from equine cadavers. Procedures-Horses underwent collagenase-induced superficial digital flexor tendonitis in the midmetacarpal region of 1 forelimb. To deliver analgesia, a closed-tip catheter was placed from lateral to medial, approximately 12 cm distal to the accessory carpal bone, between the suspensory ligament and accessory ligament of the deep digital flexor tendon. Success of catheter placement and anesthetic delivery was documented ex vivo in 5 forelimbs from equine cadavers. Effective analgesia in affected forelimbs of horses from continuous (n = 7) versus intermittent (7) local anesthetic delivery (intermittent peripheral neural blockade; IPNB) was compared over a 3-day period. Results-Horses that received CPNB in the affected forelimb were less lame than horses that received IPNB. A lower proportion of CPNB-treated horses had behavioral and physiologic signs of pain, compared with IPNB-treated horses. Neither technique completely blocked the sensation of pain or resulted in swelling in the distal portion of the forelimb, vasodilation, or an increase in lameness. After removal, Staphylococcus aureus was cultured from 1 catheter tip. Conclusions and Clinical Relevance-For short-term treatment, CPNB was more effective than IPNB for reduction in signs of severe pain in the distal aspect of the forelimb of horses. [ABSTRACT FROM AUTHOR]

• SSchwann cells and macrophages play key roles in the aftermath of peripheral nerve injury. • Previous methods of Schwann cell isolation relied on pre-enrichment through cell culture, which alters phenotype. • This paper describes two methods for accurate separation of live Schwann cells and macrophages from injured murine nerve. • Live cells are sorted immediately after harvest, allowing gene expression analysis. • B6;D2-Tg(S100b-eGFP)1Wtj/J mice express GFP in Schwann cells and macrophages. Schwann cells (SC) and macrophages play key roles in the response to peripheral nerve injury (PNI). Accurate isolation of such cells is essential for further analyses that can lead to better understanding of the repair process after PNI. Separation of live SC from the injury site without culture enrichment is necessary for targeted gene expression analysis. Two flow cytometric techniques are presented for rapid enrichment of live SC and macrophages from injured murine peripheral nerve without the need for culture. SC were isolated by fluorescent activated cell sorting (FACS) using transgenic expression of eGFP in SC, or by exclusion of other cell types collected from the injury site. Gene expression analyses of peripheral nerve repair have commonly used whole nerve lysates. Isolating SC allows more accurate understanding of their specific role in repair. SC are commonly enriched from nerve by culture, however this changes gene expression patterns and limits the utility for transcriptomic analysis. The surface marker p75-NTR has variable expression in different SC phenotypes and during the course of injury and repair. Using p75-NTR for SC isolation might enrich only a subset of SC. More stably expressed lineage markers for SC are intracellular and not suitable for sorting for gene expression. The methods used here avoid the requirement for surface marker labeling of SC. Gene expression analysis of sorted cells from both methods showed successful enrichment of SC. Lineage markers such as Map1b, p75-NTR and S100b were enriched in the sorted SC population. SC sorting by eGFP expression showed improved enrichment, particularly of mature myelinating genes, although this could represent sampling of a subset of SC. [ABSTRACT FROM AUTHOR]

Normal laryngeal function has a large impact on quality of life, and dysfunction can be life threatening. In general, airway obstructions arise from a reduction in neuromuscular function or a decrease in mechanical stiffness of the structures of the upper airway. These reductions decrease the ability of the airway to resist inspiratory or expiratory pressures, causing laryngeal collapse. We propose to restore airway patency through methods that replace damaged tissue and improve the stiffness of airway structures. A number of recent studies have utilized image-guided approaches to create cell-seeded constructs that reproduce the shape and size of the tissue of interest with high geometric fidelity. The objective of the present study was to establish a tissue engineering approach to the creation of viable constructs that approximate the shape and size of equine airway structures, in particular the epiglottis. Computed tomography images were used to create three-dimensional computer models of the cartilaginous structures of the larynx. Anatomically shaped injection molds were created from the three-dimensional models and were seeded with bovine auricular chondrocytes that were suspended within alginate before static culture. Constructs were then cultured for approximately 4 weeks post-seeding and evaluated for biochemical content, biomechanical properties, and histologic architecture. Results showed that the three-dimensional molded constructs had the approximate size and shape of the equine epiglottis and that it is possible to seed such constructs while maintaining 75%+ cell viability. Extracellular matrix content was observed to increase with time in culture and was accompanied by an increase in the mechanical stiffness of the construct. If successful, such an approach may represent a significant improvement on the currently available treatments for damaged airway cartilage and may provide clinical options for replacement of damaged tissue during treatment of obstructive airway disease.