The intra-day and inter-day reliability of a 6-second Wingate to determine maximal peak power in endurance-trained athletes.

Determining an athlete's maximal peak power (MPP) is crucial in profiling endurance sports participants. While short (3 to 6 seconds) all-out efforts have been validated for MPP assessment, prior studies mainly involved non-endurance trained athletes. This study aimed to assess the intra- and inter-day reliability of a 6-second Wingate test for MPP determination in endurance athletes. Endurance-trained participants (22 males, 5 females) completed nine 6-second Wingate tests over four days (3 trials at baseline, 2 trials on each subsequent day). Analysis revealed no systematic differences in MPP (F(4.09, 106.3) = 1.88, p = 0.117) or time to peak power (χ2 (8) = 5.23, p = 0.732) across the trials. Reliability, assessed through the intraclass correlation coefficient (ICC) and standard error of measurement (SEM), was excellent across all trials (ICC = 0.95, SEM = 40.0W, SEM% = 3.7%). Absolute reliability improved when selecting the average or the best MPP values from each day (SEM% = 2.7% and 2.9%, respectively). Within-day reliability was consistently rated as excellent, with the best values on the 4th day of tests. No significant differences in MPP values occurred between the first and second 6-second Wingate tests on days 1 to 3, with both trials demonstrating similar reliability values (SEM%: 3.2% vs 2.8%, for the first and second trials, respectively). The test also demonstrated a good sensitivity to detect a meaningful change in MPP values. In conclusion, the 6-second Wingate test proves reliable for determining MPP in endurance-trained athletes. Two trials are recommended on the first day of testing, with a single MPP likely sufficient to determine the athlete's MPP on subsequent days.

Influence of an Exercise-Specific Face Mask on Physiological and Perceptual Responses to Graded Exercise.

The impact of exercise-specific face masks (ESFMs) in aerobically fit individuals on physiological, perceptual, respiratory, and performance responses remains unclear. How ESFMs mitigate exercise-induced bronchoconstriction (EIB) is also unknown. Thus, this study aimed to determine how an ESFM altered within-exercise physiological, perceptual, respiratory, and performance responses to graded treadmill exercise. Twenty-four individuals (11 females) completed a discontinuous graded exercise test on a treadmill under two conditions (ESFM and unmasked). Physiological, respiratory function, and perceptual measures were assessed. Performance was determined by time to exhaustion. Statistical analyses included linear mixed-effects modeling, repeated measures analysis of variance, and pairwise comparisons using an alpha value of 0.05. ESFM use significantly impaired performance (median = -150.5 s) and decreased arterial oxygen saturation at maximal intensity (mean = -3.7%). Perceptions of air hunger and work of breathing were elevated across submaximal and maximal intensities. Perceived exertion and breathing discomfort were significantly elevated submaximally but not maximally. Spirometry measures were not significantly different at termination but were significantly improved at submaximal intensities in participants with and without EIB. ESFM use in fit individuals increased perceptual discomfort, impaired performance, and augmented arterial desaturation. Respiratory function improvements were observed but were accompanied by adverse perceptual sensations. Despite this, performance impairments may limit the real-world utility of ESFMs for athletes.

Motor Unit Number Index of the Upper Trapezius: A Meta-Analysis and Cross-sectional Study of Its Reliability.

Motor unit number index of the upper trapezius (MUNIX-Trapezius) is a candidate biomarker for bulbar lower motor neuron function; however, reliability data is incomplete. To assess MUNIX-Trapezius reliability in controls, we conducted a systematic review, a cross-sectional study (n = 20), and a meta-analysis. We demonstrated a high inter- and intra-rater intraclass correlation (0.86 and 0.94, respectively), indicating that MUNIX-Trapezius is reliable with between-study variability moderated by age and MUNIX technique. With further validation, this measure can serve as a disease monitoring and response biomarker of bulbar function in the therapeutic development for amyotrophic lateral sclerosis.

Nerve excitability measured with the TROND protocol in amyotrophic lateral sclerosis: a systematic review and meta-analysis.

This meta-analysis assessed the 30+ nerve excitability indices generated by the TROND protocol to identify potential biomarkers for amyotrophic lateral sclerosis (ALS). A comprehensive search was conducted in multiple databases to identify human studies that tested median motor axons. Forest plot analyses were performed using a random-effects model to determine the pooled effect (Z-score), heterogeneity (I2), and Cohen's d for potential biomarker identification. Out of 2,866 studies, 23 studies met the inclusion criteria, incorporating data from 719 controls and 942 patients with ALS. Seven indices emerged as potential biomarkers: depolarizing threshold electrotonus (TEd) 90-100 ms, strength-duration time constant (SDTC), superexcitability, TEd 40-60 ms, resting I/V slope, 50% depolarizing I/V, and subexcitability (ranked by the magnitude of the difference between patients and controls from largest to smallest). In a sensitivity analysis focusing on patients with larger compound muscle action potentials (CMAPs), only four indices were potential biomarkers: TEd 10-20 ms, TEd 90-100 ms, superexcitability, and SDTC. Among the extensive range of 30+ excitability indices generated by the TROND protocol, we have identified seven indices that effectively differentiate patients with ALS from healthy controls. Furthermore, a smaller subset of four indices shows promise as potential biomarkers when the CMAP remains relatively large. However, most studies were considered to be at moderate risk of bias due to case-control designs and absence of sensitivity and specificity calculations, underscoring the need for more prospective diagnostic test-accuracy studies with appropriate disease controls.NEW & NOTEWORTHY This meta-analysis uncovers seven potential axonal excitability biomarkers for lower motor neuron pathology in ALS, shedding light on ion channel dysfunction. The identified dysfunction aligns with the primary pathology-protein homeostasis disruption. These biomarkers could fill a gap to detect presymptomatic spread of the disease in the spinal cord and monitor treatments targeting protein homeostasis and limiting spread, toward enhancing patient care.

CAPTURE ALS: the comprehensive analysis platform to understand, remedy and eliminate ALS.

The absence of disease modifying treatments for amyotrophic lateral sclerosis (ALS) is in large part a consequence of its complexity and heterogeneity. Deep clinical and biological phenotyping of people living with ALS would assist in the development of effective treatments and target specific biomarkers to monitor disease progression and inform on treatment efficacy. The objective of this paper is to present the Comprehensive Analysis Platform To Understand Remedy and Eliminate ALS (CAPTURE ALS), an open and translational platform for the scientific community currently in development. CAPTURE ALS is a Canadian-based platform designed to include participants' voices in its development and through execution. Standardized methods will be used to longitudinally characterize ALS patients and healthy controls through deep clinical phenotyping, neuroimaging, neurocognitive and speech assessments, genotyping and multisource biospecimen collection. This effort plugs into complementary Canadian and international initiatives to share common resources. Here, we describe in detail the infrastructure, operating procedures, and long-term vision of CAPTURE ALS to facilitate and accelerate translational ALS research in Canada and beyond.

Fifty Years of Motor Unit Number Estimation.

The objective was to use bibliometric analysis to create an infographic of motor unit number estimation methods over the past 50 years. The original method was published in 1971, but secondary and tertiary waves of research using alternative methods occurred in the early 2000s and a decade later. A metric of influence was used to determine if different methods had clear peaks of use over the past 50 years. While the original method continues to register influence, the MUNIX method introduced in 2004 stands out as the most influential method to estimate the innervation status of skeletal muscles.

GABA facilitates spike propagation through branch points of sensory axons in the spinal cord.

Movement and posture depend on sensory feedback that is regulated by specialized GABAergic neurons (GAD2+) that form axo-axonic contacts onto myelinated proprioceptive sensory axons and are thought to be inhibitory. However, we report here that activating GAD2+ neurons directly with optogenetics or indirectly by cutaneous stimulation actually facilitates sensory feedback to motor neurons in rodents and humans. GABAA receptors located at or near nodes of Ranvier of sensory axons cause this facilitation by preventing spike propagation failure at the many axon branch points, which is otherwise common without GABA. In contrast, GABAA receptors are generally lacking from axon terminals and so cannot inhibit transmitter release onto motor neurons, unlike GABAB receptors that cause presynaptic inhibition. GABAergic innervation near nodes and branch points allows individual branches to function autonomously, with GAD2+ neurons regulating which branches conduct, adding a computational layer to the neuronal networks generating movement and likely generalizing to other central nervous system axons.

Coupling of single cutaneous afferents in the hand with ankle muscles, and their response to rapid light touch displacements.

Light touch reduces sway during standing. Unexpected displacement of a light touch reference at the finger can produce rapid responses in ankle muscles when standing, suggesting cutaneous receptors in the hand are functionally coupled with ankle muscles. Using microneurography in the median nerve, we tested the hypotheses: 1) that cutaneous afferent activity of mechanoreceptors of the hand would modulate electromyographic (EMG) activity of ankle muscles, and 2) that displacement of a light touch contact across a receptor's sensory territory would be encoded in the afferent activity. Spike-triggered averaging of EMG activity of tibialis anterior (TA) and soleus (SOL) demonstrated that 34 of 42 (81%) cutaneous afferents recorded modulated activity of ankle muscles with latencies between 40 and 119 ms. Cutaneous afferents of all types (slow and fast adapting, types I and II) demonstrated responses in TA and SOL, in both the ipsilateral and contralateral leg. Activity from 11 cutaneous afferents was recorded while a light touch contact was displaced across their receptive fields. Afferent activity increased with stimulus onset and remained elevated for the stimulus duration for all afferents recorded. These results suggest that cutaneous afferents from the hand consistently form connections with motor pools of the leg at latencies implicating spinal pathways. In addition, the same population of afferents is readily excited by the displacement of a light touch contact. Therefore, cutaneous receptors of the hand can be recruited and used to alter motoneuron pool excitability in muscles important to balance control, at latencies relevant for rapid balance responses.NEW & NOTEWORTHY Light touch provides cutaneous feedback argued to contribute to balance control and shown to reduce postural sway. We demonstrate that activity of cutaneous afferents in the median nerve modulates motor pool excitability of ankle muscles at short latencies and that these afferents respond when a light touch contact is displaced. These findings suggest that cutaneous receptors of the hand can contribute to rapid regulation of muscle activity important to standing balance.

Size Selective Corona Interactions from Self-Assembled Rosette and Single-Walled Carbon Nanotubes.

Nanoparticle corona phases, especially those surrounding anisotropic particles, are central to determining their catalytic, molecular recognition, and interfacial properties. It remains a longstanding challenge to chemically synthesize and control such phases at the nanoparticle surface. In this work, the supramolecular chemistry of rosette nanotubes (RNTs), well-defined hierarchically self-assembled nanostructures formed from heteroaromatic bicyclic bases, is used to create molecularly precise and continuous corona phases on single-walled carbon nanotubes (SWCNTs). These RNT-SWCNT (RS) complexes exhibit the lowest solvent-exposed surface area (147.8 ± 60 m-1 ) measured to date due to its regular structure. Through Raman spectroscopy, molecular-scale control of the free volume is also observed between the two annular structures and the effects of confined water. SWCNT photoluminescence (PL) within the RNT is also modulated considerably as a function of their diameter and chirality, especially for the (11, 1) species, where a PL increase compared to other species can be attributed to their chiral angle and the RNT's inward facing electron densities. In summary, RNT chemistry is extended to the problem of chemically defining both the exterior and interior corona interfaces of an encapsulated particle, thereby opening the door to precision control of core-shell nanoparticle interfaces.

Assessing inter-rater reproducibility in MScanFit MUNE in a 6-subject, 12-rater "Round Robin" setup.

OBJECTIVE: To assess the inter-rater reliability of MScanFit MUNE using a "Round Robin" research design. METHODS: Twelve raters from different centres examined six healthy study participants over two days. Median, ulnar and common peroneal nerves were stimulated, and compound muscle action potential (CMAP)-scans were recorded from abductor pollicis brevis (APB), abductor digiti minimi (ADM) and anterior tibial (TA) muscles respectively. From this we calculated the Motor Unit Number Estimation (MUNE) and "A50", a motor unit size parameter. As statistical analysis we used the measures Limits of Agreement (LOA) and Coefficient of Variation (COV). Study participants scored their perception of pain from the examinations on a rating scale from 0 (no pain) to 10 (unbearable pain). RESULTS: Before this study, 41.6% of the raters had performed MScanFit less than five times. The mean MUNE-values were: 99.6 (APB), 131.4 (ADM) and 126.2 (TA), with LOA: 19.5 (APB), 29.8 (ADM) and 20.7 (TA), and COV: 13.4 (APB), 6.3 (ADM) and 5.6 (TA). MUNE-values correlated to CMAP max amplitudes (R2-values were: 0.463 (APB) (p<0.001), 0.421 (ADM) (p<0.001) and 0.645 (TA) (p<0.001)). The average perception of pain was 4. DISCUSSION: MScanFit indicates a high level of inter-rater reliability, even with only limited rater experience and is overall reasonably well tolerated by patients. These results may indicate MScanFit as a reliable MUNE method with potential as a biomarker in drug trials.

Singing and Dancing With Neuromuscular Conditions: A Mixed-Methods Study.

The purpose of this study was to assess the safety and meaningfulness of a 15-week recreational dance and singing program for people with neuromuscular conditions. Within a transformative mixed-methods design, pulmonary function tests, plethysmography through wearable technology (Hexoskin vests), individualized neuromuscular quality-of-life assessments (version 2.0), and semistructured interviews were used. The interviews were analyzed through inductive, semantic thematic analysis. Although the sample sizes were small (six people with neuromuscular conditions), the authors found no evidence of safety concerns. There was evidence of respiratory improvements and reported improvements in swallowing and speech. The most notable quality-of-life changes included improvements related to weakness, swallowing, relationships, and leisure. The participants shared that the program offered meaningful social connection and embodied skills and safe and pleasurable physical exertion. The authors learned that recreational singing and dancing programs could be a safe and deeply meaningful activity for those with neuromuscular conditions that impact respiration.

Decreased excitability of motor axons contributes substantially to contraction fatigability during neuromuscular electrical stimulation.

The present study was designed to (i) determine the time course of changes in motor axon excitability during and after neuromuscular electrical stimulation (NMES); and (ii) characterize the relationship between contraction fatigability, NMES frequency, and changes at the axon, neuromuscular junction, and muscle. Eight neurologically intact participants attended 3 sessions. NMES was delivered over the common peroneal nerve at 20, 40, or 60 Hz for 8 min (0.3 s "on", 0.7 s "off"). Threshold tracking was used to measure changes in axonal excitability. Supramaximal stimuli were used to assess neuromuscular transmission and force-generating capacity of the tibialis anterior muscle. Torque decreased by 49% and 62% during 8 min of 40 and 60 Hz NMES, respectively. Maximal twitch torque decreased only during 60 Hz NMES. Motor axon excitability decreased by 14%, 27%, and 35% during 20, 40, and 60 Hz NMES, respectively. Excitability recovered to baseline immediately (20 Hz) and at 2 min (40 Hz) and 4 min (60 Hz) following NMES. Overall, decreases in axonal excitability best predicted how torque declined over 8 min of NMES. During NMES, motor axons become less excitable and motor units "drop out" of the contraction, contributing substantially to contraction fatigability and its dependence on NMES frequency. Novelty: The excitability of motor axons decreased during NMES in a frequency-dependent manner. As excitability decreased, axons failed to reach threshold and motor units dropped out of the contraction. Overall, decreased excitability best predicted how torque declined and thus is a key contributor to fatigability during NMES.

Emissions of nitrogen oxides and volatile organic compounds from liquefied petroleum gas-fueled taxis under idle and cruising modes.

Liquefied petroleum gas (LPG) as an alternative fuel is increasingly used in mainland China, few reports are however available about emissions from LPG-fueled vehicles. In this study, 26 LPG-fueled taxis in Guangzhou, south China were tested using a chassis dynamometer to obtain their emission factors of nitrogen oxides (NOx) and volatile organic compounds (VOCs) under idle and cruising (10-60 km h-1) modes. The emission factors of NOx on average increased with speed from 4.13 g kg-fuel-1 at idling to 71.1 g kg-fuel-1 at 60 km h-1 at a slope of 10.6 g kg-fuel-1 per 10 km h-1 increase in speed. Alkanes were the most abundant (71.9%) among the VOCs in the exhaust, followed by alkenes (25.2%), ethyne (2.7%), and aromatic species (0.2%). Emission factors of VOCs at idling averaged 8.24 g kg-fuel-1, higher than that of 6.23-7.36 g kg-fuel-1 when cruising at 10-60 km h-1, but their ozone formation potentials (OFPs) were lower at idling (15.8 g kg-fuel-1) than under cruising (19.1-23.8 g kg-fuel-1) largely due to higher emission of more reactive alkenes under cruising mode. Emissions of both NOx and VOCs increased significantly with mileages. Measured emission factors of NOx and reactive VOCs in this study suggested that replacing the gasoline-powered taxis with the LPG-fueled taxis with LPG-gasoline bi-fuel engines and no efficient after-treatment devices would not benefit in reducing the emissions of ozone precursors, and strengthening the emission control for LPG vehicles with dedicated LPG engines and after-treatment converters, as did in Hong Kong, could further benefit in reducing the emission of photochemically active species when using LPG as alternative fuels.

Implantable Nanosensors for Human Steroid Hormone Sensing In Vivo Using a Self-Templating Corona Phase Molecular Recognition.

Dynamic measurements of steroid hormones in vivo are critical, but steroid sensing is currently limited by the availability of specific molecular recognition elements due to the chemical similarity of these hormones. In this work, a new, self-templating synthetic approach is applied using corona phase molecular recognition (CoPhMoRe) targeting the steroid family of molecules to produce near infrared fluorescent, implantable sensors. A key limitation of CoPhMoRe has been its reliance on library generation for sensor screening. This problem is addressed with a self-templating strategy of polymer design, using the examples of progesterone and cortisol sensing based on a styrene and acrylic acid copolymer library augmented with an acrylated steroid. The pendant steroid attached to the corona backbone is shown to self-template the phase, providing a unique CoPhMoRE design strategy with high efficacy. The resulting sensors exhibit excellent stability and reversibility upon repeated analyte cycling. It is shown that molecular recognition using such constructs is viable even in vivo after sensor implantation into a murine model by employing a poly (ethylene glycol) diacrylate (PEGDA) hydrogel and porous cellulose interface to limit nonspecific absorption. The results demonstrate that CoPhMoRe templating is sufficiently robust to enable a new class of continuous, in vivo biosensors.

Nerve excitability differences in slow and fast motor axons of the rat: more than just Ih.

The objective was to determine biophysical differences between fast and slow motor axons using threshold tracking and demonstrate confounds related to anesthetic. Nerve excitability of motor axons innervating the slow-twitch soleus (SOL) and fast-twitch tibialis anterior (TA) muscles was tested. The experiments were conducted with pentobarbital sodium (SP) anesthetic and compared with previous results that used ketamine-xylazine (KX). Nerve excitability indices measured with SP show definitive differences between TA and SOL motor axons that extend beyond previous reports. Nerve excitability indices sensitive to changes in Ih indicated an increase in SOL axons compared with TA axons [e.g., S3 t = 7.949 (df = 10), P < 0.001; hyperpolarizing threshold electrotonus (90-100 ms), t = 2.659 (df = 20); P = 0.01; hyperpolarizing I/V slope, t = 4.308 (df = 19); P < 0.001]. SOL axons also had a longer strength-duration time constant [t = 3.35 (df = 20); P = 0.003] and a longer and larger magnitude relative refractory period [RRP (ms) t = 3.53 (df = 12); P = 0.004; Refractoriness at 2 ms, t = 0.0055 (df = 9); P = 0.006]. Anesthetic choice affected many measures of peripheral nerve excitability with differences most apparent in tests of threshold electrotonus and recovery cycle. For example, recovery cycle with KX lacked a clear superexcitable and late subexcitable period. We conclude that KX had a confounding effect on nerve excitability results consistent with ischemic depolarization. Results using SP revealed the full extent of differences in nerve excitability measures between putative slow and fast motor axons of the rat. These results provide empirical evidence, beyond conduction velocity, that the biophysical properties of motor axons vary with the type of muscle fiber innervated. These differences suggest that fast axons may be predisposed to dysfunction during hyperpolarizing stresses, e.g., electrogenic sodium pumping following sustained impulse conduction.NEW & NOTEWORTHY Nerve excitability testing is a tool used to provide insight into the properties of ion channels in peripheral nerves. It is used clinically to assess pathophysiology of axons. Researchers customarily think of motor axons as homogeneous; however, we demonstrate there are clear differences between fast and slow axons in the rat. This is important for interpreting results with selective motor neuronopathy, like aging where fast axons are at high risk of degeneration.

A review of acute responses, after-effects and chronic complications related to microneurography.

Microneurography, a technique used to detect postganglionic sympathetic nerve traffic in humans, is increasingly used to further the understanding of autonomic regulation in health and disease. The technique involves the transcutaneous insertion of a microelectrode into a peripheral nerve, following which, a variety of adverse acute responses; after-effect and chronic complications have been documented. Here, we comprehensively review the potential adverse outcomes of microneurography and provide updated quantifiable incidence rates of their occurrence within a general population. We also present recommendations for risk assessment and management of such outcomes, as well as recommendations to improve future reporting. This review aims to use objective evidence to improve the understanding of the rare, but present, adverse outcomes of microneurography.

Intentions of Canadian health professionals towards recommending exercise for people living with ALS.

BACKGROUND: To provide a nationwide overview of the attitudes, social pressure, perceived ability and intentions of health professionals toward exercise prescription for people living with ALS (pALS). METHODS: An online survey of physician and non-physician health professionals (HPs) working in academic ALS clinics across Canada. RESULTS: The response rate was 48% (84/176) with 30% of respondents identifying as physicians, 63% as other HPs and the remainder as administrative or research personnel. Respondents were sharply divided in their intentions to provide exercise counsel: 24% unlikely and 45% likely. Respondents with low intentions were HPs that considered this activity outside their scope of practice. Measures of intention and attitude were more positive for flexibility compared to strength and aerobic exercise. Perceptions of social pressure and ability to provide exercise counsel were significantly correlated with intention across the three exercise modes in all respondents. Qualitative themes identified as barriers to exercise prescription were lack of confidence or competence (31% physicians, 32% HP), patient tolerance (30% HP), lack of evidence (22% physicians) and lack of infrastructure (22% physicians). CONCLUSIONS: While "lack of evidence" for the benefit of exercise was a deterrent for physicians, the larger issue for all respondents was building competence and confidence in exercise prescription for pALS.

Conditioning electrical stimulation promotes functional nerve regeneration.

Peripheral nerve regeneration following injury is often incomplete, resulting in significant personal and socioeconomic costs. Although a conditioning crush lesion prior to surgical nerve transection and repair greatly promotes nerve regeneration and functional recovery, feasibility and ethical considerations have hindered its clinical applicability. In a recent proof of principle study, we demonstrated that conditioning electrical stimulation (CES) had effects on early nerve regeneration, similar to that seen in conditioning crush lesions (CCL). To convincingly determine its clinical utility, establishing the effects of CES on target reinnervation and functional outcomes is of utmost importance. In this study, we found that CES improved nerve regeneration and reinnervation well beyond that of CCL. Specifically, compared to CCL, CES resulted in greater intraepidermal skin and NMJ reinnervation, and greater physiological and functional recovery including mechanosensation, compound muscle action potential on nerve conduction studies, normalization of gait pattern, and motor performance on the horizontal ladder test. These findings have direct clinical relevance as CES could be delivered at the bedside before scheduled nerve surgery.

Implanted Nanosensors in Marine Organisms for Physiological Biologging: Design, Feasibility, and Species Variability.

In recent decades, biologists have sought to tag animals with various sensors to study aspects of their behavior otherwise inaccessible from controlled laboratory experiments. Despite this, chemical information, both environmental and physiological, remains challenging to collect despite its tremendous potential to elucidate a wide range of animal behaviors. In this work, we explore the design, feasibility, and data collection constraints of implantable, near-infrared fluorescent nanosensors based on DNA-wrapped single-wall carbon nanotubes (SWNT) embedded within a biocompatible poly(ethylene glycol) diacrylate (PEGDA) hydrogel. These sensors are enabled by Corona Phase Molecular Recognition (CoPhMoRe) to provide selective chemical detection for marine organism biologging. Riboflavin, a key nutrient in oxidative phosphorylation, is utilized as a model analyte in in vitro and ex vivo tissue measurements. Nine species of bony fish, sharks, eels, and turtles were utilized on site at Oceanogràfic in Valencia, Spain to investigate sensor design parameters, including implantation depth, sensor imaging and detection limits, fluence, and stability, as well as acute and long-term biocompatibility. Hydrogels were implanted subcutaneously and imaged using a customized, field-portable Raspberry Pi camera system. Hydrogels could be detected up to depths of 7 mm in the skin and muscle tissue of deceased teleost fish ( Sparus aurata and Stenotomus chrysops) and a deceased catshark ( Galeus melastomus). The effects of tissue heterogeneity on hydrogel delivery and fluorescence visibility were explored, with darker tissues masking hydrogel fluorescence. Hydrogels were implanted into a living eastern river cooter ( Pseudemys concinna), a European eel ( Anguilla anguilla), and a second species of catshark ( Scyliorhinus stellaris). The animals displayed no observable changes in movement and feeding patterns. Imaging by high-resolution ultrasound indicated no changes in tissue structure in the eel and catshark. In the turtle, some tissue reaction was detected upon dissection and histopathology. Analysis of movement patterns in sarasa comet goldfish ( Carassius auratus) indicated that the hydrogel implants did not affect swimming patterns. Taken together, these results indicate that this implantable form factor is a promising technique for biologging using aquatic vertebrates with further development. Future work will tune the sensor detection range to the physiological range of riboflavin, develop strategies to normalize sensor signal to account for the optical heterogeneity of animal tissues, and design a flexible, wearable device incorporating optoelectronic components that will enable sensor measurements in moving animals. This work advances the application of nanosensors to organisms beyond the commonly used rodent and zebrafish models and is an important step toward the physiological biologging of aquatic organisms.

Characterization of the Nile Grass Rat as a Unique Model for Type 2 Diabetic Polyneuropathy.

Type 2 diabetes (T2D) has reached pandemic proportions worldwide. Almost half of T2D patients suffer from polyneuropathy that can present as paresthesia, hyperalgesia, allodynia, or hypoesthesia. Therapeutic treatment options are largely incomplete, suggesting new avenues of research are needed. Herein, we introduce the African Nile Grass rat (NGR), which develops T2D solely by diet manipulation, as a novel T2D polyneuropathy model. The purpose of this study was to first characterize T2D-induced polyneuropathy in the NGRs before highlighting their strength as a potential prediabetic model of T2D. NGRs with long-term T2D exhibit hallmark features of polyneuropathy such as decreased motor nerve conduction velocity, intraepidermal denervation, and hyposensitivity to noxious mechanical and thermal stimulation. At the dorsal root ganglia, T2D neurons have altered sodium channel expression, specifically increased Nav1.7 and Nav1.9, and their surrounding satellite glial cells express glial fibrillary acidic protein. Now that these T2D NGRs have been characterized and shown to have a similar presentation to human and other animal models of T2D, the strength of this diet-induced model can be exploited. The prediabetic changes can be observed over their long progression to develop T2D which may allow for a therapeutic window to prevent T2D before permanent damage occurs.