Age-associated loss of muscle mass, or sarcopenia, contributes directly to frailty and an increased risk of falls and fractures among the elderly. Aged mice and elderly adults both show decreased muscle mass as well as relatively low levels of the fat-derived hormone leptin. Here we demonstrate that loss of muscle mass and myofiber size with aging in mice is associated with significant changes in the expression of specific miRNAs. 57 miRNAs were altered with aging in the mice and many of these miRNAs are, for the first time, reported to be associated specifically with age-related muscle atrophy. These include miR-221, previously identified in studies of myogenesis and muscle development as playing a role in the proliferation and terminal differentiation of myogenic precursors. We also treated aged mice with recombinant leptin, to determine whether leptin therapy could improve muscle mass and alter the miRNA expression profile of aging skeletal muscle. Leptin treatment significantly increased hindlimb muscle mass and extensor digitorum longus fiber size in aged mice. Furthermore, the expression of 37 miRNAs was altered in muscles of leptin treated mice. In particular, leptin treatment increased the expression of miR-31 and miR-223, miRNAs known to be elevated during muscle regeneration and repair. These findings suggest that aging in skeletal muscle is associated with marked changes in the expression of specific miRNAs, and that nutrient-related hormones such as leptin may be able to reverse muscle atrophy and alter the expression of atrophy-related miRNAs in aging skeletal muscle.

Slipped capital femoral epiphysis (SCFE) has a well-documented association with underlying endocrine conditions, including thyroid hormone aberrations and parathyroid dysfunction.Recombinant growth hormone therapy has also been identified as a risk factor for the development of SCFE.Presentation before their 10th birthday or after their 16th birthday along with height of <10th percentile are reliable risk factors for identifying children with an SCFE who are at a heightened risk for an underlying endocrinopathy and can been used to guide selective laboratory testing.Patients with unilateral SCFE presentations with an underlying endocrinopathy are at a heightened risk for contralateral slip development and should be treated with prophylactic fixation.

IntroductionElectrosurgery for dissection and hemostasis remains one of the foundational tools for the field of surgery as a whole. Monopolar cautery remains the most utilized modality for achieving the aforementioned goals. Given the prolonged history and pre-modern development of "Bovie" cautery, there remains a paucity of data regarding appropriate settings and intensity for various tissue types, procedures, or locales. As a result, utilized settings depend on precedent and personal preference. We aimed to determine the amount of secondary soft tissue injury by volume and depth beyond the electrocautery pen tip in the skin and subcutaneous tissue as well as skeletal muscle. MethodsPorcine samples were used for experimental testing using two testing types: 1) skin and subcutaneous tissue and 2) Skeletal muscle. Sample sizes were standardized at 1 cm3 cubes. For skin samples, tissue injury was created with either a scalpel or electrocautery pen on cut setting, and tested at intensities from 10 to 150 in increments of 10. Skeletal muscle samples were similarly tested using the electrocautery pen only in either a cut or coagulation setting. Samples were tested at incremental intensities from 10 to 120 for both settings. Electrocautery was tested for a period of five seconds with a continuous current. All samples were placed in formalin and underwent histologic staining with hematoxylin and eosin staining to be assessed for the extent of tissue injury in terms of depth, radius, and volume. The measurements were recorded in millimeters. ResultsFor skin incision, there was a positive and significant correlation with respect to the radius (R=.73, p=0.006). When considering intensity with an interval of 10-70 there was a positive and significant correlation with respect to the radius, depth, and volume. The cold knife incision had no notable soft tissue injury beyond the depth of the incision. Regarding skeletal muscle, again, a significant and positive correlation between increasing monopolar settings was noted for both the coagulation and cut functions (R=.84, p=.0005; R=0.84, p=0.0006). A positive correlation was found between increasing cut intensity and volume of soft tissue injury (R=0.73, p=.008); this was not reflected in the coagulation setting. When limited to an intensity range of 10-60, a significant relationship was noted for depth, radius and volume (R=.95, p= <0.001; R=0.98, p= <.001; R=.92, p=.001). ConclusionIn all samples, apart from the cold knife skin incision, additional soft tissue injury beyond the tip of the electrocautery pen was noted. Given our findings, recommendations include using the lowest setting required for the purposes of the given surgical case as well as minimizing electrocautery use for skin incisions given its association with a larger volume of tissue injury in comparison with a scalpel. Additionally, electrocautery should be used with care in, and around neurovascular structures as soft tissue injury did occur several millimeters beyond the tip of the electrocautery pen. Furth...

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