Overexpression of enhanced yellow fluorescent protein fused with Channelrhodopsin-2 causes contractile dysfunction in skeletal muscle.

Skeletal muscle activation using optogenetics has emerged as a promising technique for inducing noninvasive muscle contraction and assessing muscle function both in vivo and in vitro. Transgenic mice overexpressing the optogenetic fusion protein, Channelrhodopsin 2-EYFP (ChR2-EYFP) in skeletal muscle are widely used; however, overexpression of fluorescent proteins can negatively impact the functionality of activable tissues. In this study, we characterized the contractile properties of ChR2-EYFP skeletal muscle and introduced the ChR2-only mouse model that expresses light-responsive ChR2 without the fluorescent EYFP in their skeletal muscles.

Impact of capillary and sarcolemmal proximity on mitochondrial structure and energetic function in skeletal muscle.

Mitochondria within skeletal muscle cells are located either between the muscle contractile apparatus (interfibrillar mitochondria, IFM) or beneath the cell membrane (subsarcolemmal mitochondria, SSM), with several structural and functional differences reported between IFM and SSM. However, recent 3D imaging studies demonstrate that mitochondria are particularly concentrated in the proximity of capillaries embedded in sarcolemmal grooves rather than in proximity to the sarcolemma itself (paravascular mitochondria, PVM). To evaluate the impact of capillary vs.

Reorganization of mitochondria-organelle interactions during postnatal development in skeletal muscle.

Skeletal muscle cellular development requires the integrated assembly of mitochondria and other organelles adjacent to the sarcomere in support of muscle contractile performance. However, it remains unclear how interactions among organelles and with the sarcomere relates to the development of muscle cell function. Here, we combine 3D volume electron microscopy, proteomic analyses, and live cell functional imaging to investigate the postnatal reorganization of mitochondria-organelle interactions in skeletal muscle.

Leveraging Emerging Technologies to Expand Accessibility and Improve Precision in Rehabilitation and Exercise for People with Disabilities.

Physical rehabilitation and exercise training have emerged as promising solutions for improving health, restoring function, and preserving quality of life in populations that face disparate health challenges related to disability. Despite the immense potential for rehabilitation and exercise to help people with disabilities live longer, healthier, and more independent lives, people with disabilities can experience physical, psychosocial, environmental, and economic barriers that limit their ability to participate in rehabilitation, exercise, and other physical activities. Together, these barriers contribute to health inequities in people with disabilities, by disproportionately limiting their ability to participate in health-promoting physical activities, relative to people without disabilities.

Effect of a Commercial NCLEX-RN Preparation Product on First Time Pass Rates.

Introduction: Passing the National Council Licensure Exam-Registered Nurse (NCLEX-RN) is the entry into the profession for nurses, and rates of passing the exam on the first attempt are used as an important outcome measure for schools, students, and accrediting agencies.

Objective: This study was conducted in order to investigate if a commercial NCLEX-RN test preparation product impacted first time pass rates.

Methods: Data were collected from 688 students from six institutions who were taking the NCLEX-RN for the first time.

Fibrillar glomerulonephritis in a patient with systemic lupus erythematosus with no evidence of lupus nephritis.

Fibrillar glomerulonephritis (FGN) is a rare proliferative form of glomerular disease characterised by randomly oriented fibrillar deposits with a mean diameter of 20 nm. It has a rare association with systemic lupus erythematosus (SLE). We report the case of a female in her mid-50's with a 20 year history of SLE, who developed proteinuria due to FGN and had no histological evidence of lupus nephritis.

Skeletal Muscle Dysfunction in People With Multiple Sclerosis: A Physiological Target for Improving Physical Function and Mobility.

Impaired mobility is amongst the most debilitating symptoms reported by people with multiple sclerosis (MS). Historically, it has been viewed that walking impairments in people with MS are directly caused by the physical damage to the neurons in the central nervous system (CNS) which results from the immunopathology of MS. However, research from over the past 4 decades has revealed that physical function in people with MS is also affected by skeletal muscle dysfunction characterized by a reduced capacity to produce, regulate, and sustain the force-generating muscle contractions that propel human movement.

Mitochondrial network configuration influences sarcomere and myosin filament structure in striated muscles.

Sustained muscle contraction occurs through interactions between actin and myosin filaments within sarcomeres and requires a constant supply of adenosine triphosphate (ATP) from nearby mitochondria. However, it remains unclear how different physical configurations between sarcomeres and mitochondria alter the energetic support for contractile function. Here, we show that sarcomere cross-sectional area (CSA) varies along its length in a cell type-dependent manner where the reduction in Z-disk CSA relative to the sarcomere center is closely coordinated with mitochondrial network configuration in flies, mice, and humans.

Prediction of future falls among full-time wheelchair and scooter users with multiple sclerosis: A prospective study.

Background: Seventy-five percent (75%) of full-time wheelchair or scooter users with multiple sclerosis (MS) experience at least one fall in a period of 6 months. Falls are detrimental for the independence, quality of life, and community participation. No previous prospective study has evaluated fall risk factors in this segment of MS community.

Regulation of the evolutionarily conserved muscle myofibrillar matrix by cell type dependent and independent mechanisms.

Skeletal muscles play a central role in human movement through forces transmitted by contraction of the sarcomere. We recently showed that mammalian sarcomeres are connected through frequent branches forming a singular, mesh-like myofibrillar matrix. However, the extent to which myofibrillar connectivity is evolutionarily conserved as well as mechanisms which regulate the specific architecture of sarcomere branching remain unclear.

Subcellular Specialization of Mitochondrial Form and Function in Skeletal Muscle Cells.

Across different cell types and within single cells, mitochondria are heterogeneous in form and function. In skeletal muscle cells, morphologically and functionally distinct subpopulations of mitochondria have been identified, but the mechanisms by which the subcellular specialization of mitochondria contributes to energy homeostasis in working muscles remains unclear. Here, we discuss the current data regarding mitochondrial heterogeneity in skeletal muscle cells and highlight potential new lines of inquiry that have emerged due to advancements in cellular imaging technologies.

A National Study of Progression Policies and Course Repetition in Prelicensure Registered Nursing Programs.

Background: The literature lacks description of the incidence of nursing students failing and repeating courses. Nursing student repeaters delay graduation and entry into the workforce; they are also at risk for attrition.

Aim: The aim of the study was to describe the incidence of nursing student repeaters and progression policies in the United States.

Consensus for the General Use of Equine Water Treadmills for Healthy Horses.

Water treadmill exercise has become popular in recent years for the training and rehabilitation of equine athletes. In 2019, an equine hydrotherapy working group was formed to establish what was commonly considered to be best practice in the use of the modality. This article describes the process by which general guidelines for the application of water treadmill exercise in training and rehabilitation programmes were produced by the working group.

The Functional Impact of Mitochondrial Structure Across Subcellular Scales.

Mitochondria are key determinants of cellular health. However, the functional role of mitochondria varies from cell to cell depending on the relative demands for energy distribution, metabolite biosynthesis, and/or signaling. In order to support the specific needs of different cell types, mitochondrial functional capacity can be optimized in part by modulating mitochondrial structure across several different spatial scales.

The unified myofibrillar matrix for force generation in muscle.

Human movement occurs through contraction of the basic unit of the muscle cell, the sarcomere. Sarcomeres have long been considered to be arranged end-to-end in series along the length of the muscle into tube-like myofibrils with many individual, parallel myofibrils comprising the bulk of the muscle cell volume. Here, we demonstrate that striated muscle cells form a continuous myofibrillar matrix linked together by frequently branching sarcomeres.

EMRE is essential for mitochondrial calcium uniporter activity in a mouse model.

The mitochondrial calcium uniporter is widely accepted as the primary route of rapid calcium entry into mitochondria, where increases in matrix calcium contribute to bioenergetics but also mitochondrial permeability and cell death. Hence, regulation of uniporter activity is critical to mitochondrial homeostasis. The uniporter subunit EMRE is known to be an essential regulator of the channel-forming protein MCU in cell culture, but EMRE's impact on organismal physiology is less understood.

MUSCLE MITOCHONDRIAL CAPACITY AND ENDURANCE IN ADULTS WITH TYPE 1 DIABETES.

Unlabelled: The impact of type 1 diabetes (T1D) on muscle endurance and oxidative capacity is currently unknown.

Purpose: Measure muscle endurance and oxidative capacity of adults with T1D compared to controls.

Methods: A cross-sectional study design with a control group was used.

Muscle Dysfunction and Walking Impairment in Women with Multiple Sclerosis.

Background: Recent evidence suggests that skeletal muscle dysfunction is involved in disability progression in people with multiple sclerosis (MS). However, the relationship between muscle dysfunction and walking impairments in MS remains unclear. Thus, the cross-sectional relationships between muscle-specific oxidative capacity and walking endurance in women with MS were evaluated.

MitoRACE: evaluating mitochondrial function in vivo and in single cells with subcellular resolution using multiphoton NADH autofluorescence.

Key Points: We developed a novel metabolic imaging approach that provides direct measures of the rate of mitochondrial energy conversion with single-cell and subcellular resolution by evaluating NADH autofluorescence kinetics during the mitochondrial redox after cyanide experiment (mitoRACE). Measures of mitochondrial NADH flux by mitoRACE are sensitive to physiological and pharmacological perturbations in vivo. Metabolic imaging with mitoRACE provides a highly adaptable platform for evaluating mitochondrial function in vivo and in single cells with potential for broad applications in the study of energy metabolism.

Effects of Treadmill Training on Muscle Oxidative Capacity and Endurance in People with Multiple Sclerosis with Significant Walking Limitations.

Background: Exercise can improve muscle function and mobility in people with multiple sclerosis (MS). However, the effects of exercise training on skeletal muscle oxidative capacity and endurance in people with MS remain unclear, and few studies have evaluated muscle plasticity in people with MS who have moderate-to-severe disability. The present study evaluated the effects of treadmill training on muscle oxidative capacity and muscle endurance and examined the relationship to walking function in people with MS who have moderate-to-severe disability.

Muscle-Specific Endurance of the Lower Back Erectors Using Electrical Twitch Mechanomyography.

Lower back pain is a common symptom potentially associated with skeletal muscle dysfunction. The purpose of this study was to evaluate endurance in the lower back muscles of healthy participants using accelerometer-based mechanomyography. Methods: Young healthy subjects (N = 7) were tested.

Subcellular connectomic analyses of energy networks in striated muscle.

Mapping biological circuit connectivity has revolutionized our understanding of structure-function relationships. Although connectomic analyses have primarily focused on neural systems, electrical connectivity within muscle mitochondrial networks was recently demonstrated to provide a rapid mechanism for cellular energy distribution. However, tools to evaluate organelle connectivity with high spatial fidelity within single cells are currently lacking.

Effect of Antigravity Treadmill Training on Muscle Oxidative Capacity, Muscle Endurance, and Walking Function in a Person with Multiple Sclerosis.

Background: Exercise training can improve skeletal muscle metabolism in persons with multiple sclerosis (MS). However, quantification of exercise-mediated improvements in muscle metabolism has been limited, particularly in people with high levels of disability. We evaluated the effect of 9 weeks of antigravity treadmill training on muscle oxidative capacity and muscle endurance and assessed the relationship to walking function in a person with MS.

Muscle-specific endurance of the trapezius muscles using electrical twitch mechanomyography.

Background: Symptoms of fatigue and pain are often reported for the trapezius muscle in the shoulder. The present study evaluated endurance in the trapezius muscles of healthy participants using electric twitch mechanomyography (ETM).

Methods: Surface electrodes and a tri-axial accelerometer were placed over the left trapezius muscle.

Assessment of Mitochondrial Dysfunction in Clinical Populations Using Near-Infrared Spectroscopy.

The ability to sustain submaximal exercise is largely dependent on the oxidative capacity of mitochondria within skeletal muscle, and impairments in oxidative metabolism have been implicated in many neurologic and cardiovascular pathologies. Here we review studies which have demonstrated the utility of Near-infrared spectroscopy (NIRS) as a method of evaluating of skeletal muscle mitochondrial dysfunction in clinical human populations. NIRS has been previously used to noninvasively measure tissue oxygen saturation, but recent studies have demonstrated the utility of NIRS as a method of evaluating skeletal muscle oxidative capacity using post-exercise recovery kinetics of oxygen metabolism.