Dividing to keep muscle together: the role of satellite cells in aging skeletal muscle

The factors responsible for the atrophy of skeletal muscle with aging remain to be elucidated. Recent evidence points toward an important role for a population of cells located on the surface of skeletal muscle fibers, known as satellite cells, in maintaining the integrity of skeletal myocytes throughout the life span. This Perspective examines the role that these cells are thought to play in aging muscle atrophy, and highlights a recent study by Brack and colleagues that attempts to understand the role of satellite cells in maintaining the ratio of myonuclear number to cytoplasmic volume within myocytes as we age.     

Specificity of back muscle response to submaximal fatiguing contractions

A fatigue-related decrease in quality and accuracy of the proprioceptive feedback from muscle spindles in the back (e.g. stretch reflexes) may lead to a deterioration of spinal stability, thereby making the spine more vulnerable to external perturbations. Endurance time, tissue oxygenation, reflex latency and blood pressure response were studied in twenty subjects during a submaximal endurance test of the back extensors (20 % MVC) performed as either a position task (supporting a weight stack while maintaining trunk position) or a force task (exerting a force against a dynamometer). Mean endurance time was 8.91 (± 2.79) min for the force task and 10.86 (± 6.93) min for the position task. This result is in striking contrast to what has previously been reported from limb muscles, and suggests that back muscles are especially well suited for postural tasks. An increased reflex latency found after the position task indicates that the disadvantage of the prolonged endurance time is a deterioration of the afferent input from the muscle spindles that may potentially hamper the protection of the spine.     

Popular epidemiology and toxic waste contamination: lay and professional ways of knowing.

Building on a detailed study of the Woburn, Massachusetts, childhood leukemia cluster, this paper examines lay and professional ways of knowing about environmental health risks. Of particular interest are differences between lay and professional groups' definitions of data quality, methods of analysis, traditionally accepted levels of measurement and statistical significance, and relations between scientific method and public policy. This paper conceptualizes the hazard-detection and solution-seeking activities of Love Canal, Woburn, and other communities as popular epidemiology: the process by which lay persons gather data and direct and marshal the knowledge and resources of experts in order to understand the epidemiology of disease, treat existing and prevent future disease, and remove the responsible environmental contaminants. Based on different needs, goals, and methods, laypeople and professionals have conflicting perspectives on how to investigate and interpret environmental health data.     

Long periods with uninterrupted muscle activity related to neck and shoulder pain

The aim was to analyze the relationship between periods with uninterrupted neck muscle activity for ≥ 4 min and neck and shoulder pain. The trapezius muscle activity was recorded bilaterally on 40 young workers and students during a full shift. Neck and shoulder pain, mechanical work load and decision control were reported at the same time as the muscle activity recording and 6 months later. A dose-response relationship was found between uninterrupted muscle activity and neck and shoulder pain, with a ten-fold higher risk for the group with more than half, compared to less than a third, of the shift with uninterrupted muscle activity. Self-reported mechanical work load showed a small but protective effect related to pain. Gender and decision control did not emerge as important risk factors in this model. In conclusion, this study indicates that work or other exposures that contains long periods with uninterrupted neck muscle activity of 4 min duration or longer should be minimized to reduce risk of neck and shoulder pain.     

Knitting an action net to reduce plastic waste: reusable takeout food containers in New York City

ABSTRACT

The paper presents an analysis of actions undertaken to promote and implement reusable takeout food containers in New York City in response to the overuse of plastic disposable single-use containers. It discusses, in detail, the emergence of an action net around this issue and business models for reusables. The paper contributes to the theoretical discussion on network emergence by analyzing the formation and axiological tensions within the action net. Currently, market solutions are the only ones exercised and perceived as achievable by network participants, who consider market conditions as both given and unchallengeable. The paper argues that chances for network expansion depend on network participants’ perceptions of the limitations of social change.     

Household time activities,food waste,and diet quality: the impact of non-marginal changes due to COVID-19

Review of Economics of the Household - In early 2020, a novel coronavirus quickly spread across the globe. In response to the rapidly increasing number of confirmed U.S. cases, state and local...     

The use of a vertical arm support device to reduce upper extremity muscle firing in sonographers

Work-related musculoskeletal disorders (WRMSD) in sonographers have increased over the past 20 years with shoulder injuries being the most prevalent. Advancing ultrasound technologies have reduced a sonographer's need to move when performing exams and increased prolonged arm abduction, resulting in static work postures and decreased joint perfusion. Work modifications in other industries have demonstrated that reducing arm abduction to 30° reduces muscle firing and fatigue. Although this is the ideal work posture for sonographers, there are many instances in which excessive arm abduction and static postures cannot be avoided. These positions are further complicated by the fact that the scanning arm is also supporting the weight of the ultrasound transducer. This observational case study evaluated the use of a moveable arm support system as a means to provide support for the scanning arm and reduce muscle firing during ultrasound exams in the scanning lab of a university diagnostic ultrasound educational program.     

A Response to U. T. Place

The Analysis of Verbal Behavior - Skinner’s (1957) analysis of verbal behavior has received an unwarranted amount of criticism over the years, and the recently published reviews of Verbal...     

Everything you never wanted to know about special education . . . and were afraid to ask (I.D.E.A.)

Social workers who work with families and children are often unaware of the legal protections afforded to educational experiences for children, particularly to children with disabilities. Yet, all social workers, regardless of their practice setting, should be aware of the important educational rights to which children with disabilities and their families are entitled, as codified in the original legislation, P.L. 94-142, and its subsequent revisions. This legislation is currently entitled the "Individuals with Disabilities Education Act," or the "I.D.E.A." Provisions included in the I.D.E.A. are covered with which all states that receive federal educational funding are mandated to comply. Reviewed are the 13 "disabling conditions" that allow for students to qualify to receive special educational services, as long as one of the conditions is adversely impacting their educational success. It concludes with recommendations for social work advocacy regarding this legislation.     

Response to Dr. Blythe

The education of social work students with regard to issues of social and cultural diversity has been a mandate of the Council on Social Work Education for over a decade. This mandate requires social work educators to increase students’ awareness of their own biases and to evaluate changes in students’ attitudes as they are exposed to content on diverse populations. In this endeavor, valid and reliable measures of attitude change can be a useful evaluation tool to assess instructional effectiveness. This article summarizes a variety of available instruments for measuring attitudes toward race, ethnicity, gender, sex stereotyping, physical disability, and age.     

Welcome to Mt. Huangshan

The newly developed tourist city of Huangshan possesses the extremely beautiful natural scenery of Mt. Huangshan, as well as the splendid culture of its 2,300-year history, providing marvelous enjoyment for both domestic and foreign tourists. The scenery in Mt. Huangshan is lovely all year round, with its four unique views—the rocks, the pine trees, the sea of clouds and the hot springs. In the areas around Mt. Huangshan, people can see folk customs as well as ancient architecture in the form of bridges, residences, arch towers, streets and ancestral halls.