Background: Sarcopenia is associated with poor prognosis in lung cancer. Skeletal muscle area can be quantified based on radiodensity of CT scan. The purpose of this study was to evaluate the prognostic significance of radiodensity-based detailed skeletal muscle quantification on outcomes after surgery of non-small cell lung cancer (NSCLC). Methods: Single cross-sectional area of the skeletal muscle (−29 to 150 HU) at the 3rd lumbar vertebra (L3) level retrospectively measured on preoperative CT for NSCLC patients (n=272), who underwent surgical resection during 2011 to 2016. The diagnosis of sarcopenia was made when a L3 muscle index (L3MI; L3 muscle area/height2) of less than 55 cm²/m² for men and less than 39 cm²/m² for women. Skeletal muscle was subsequently classified based on radiodensity level as low attenuation muscle (−29 to <30 HU) and high attenuation muscle (30 to 150 HU). Using a maximal-chi-squared test, low attenuation muscle accounted less than 24.5% of the total muscle, which was considered healthy muscle. Data on clinical characteristics (demographic information, TNM stage, histology) and prognosis (disease-free survival; DFS, and overall survival; OS) were collected. Results: Sarcopenia was found 22.4% in preoperative CT (32.9% for men and 6.5% for women). The prevalence of patients with healthy muscle was 15.4% (21.3% for men and 6.5% for women). There was no significant difference between the 3-year DFS rate (77.0% vs. 67.0%, P=0.142) or 3-year OS rate (84.8% vs. 87.9%, P=0.576) between patients with and without sarcopenia. However, patients with healthy muscle tend to show longer 3-year DFS rate (79.4% vs. 67.2%, P=0.094) and 3-year OS rate (92.6% vs. 86.1%, P=0.176). In the multivariable analysis, healthy muscle was one of the independent prognosticators for a 3-year DFS rate (HR, 0.50, P=0.035), along with R1 resection (HR, 5.90, P<0.001), pathologic T stage (HR, 2.69, P<0.001), and pathologic N stage (HR, 2.43, P<0.001). Conclusions: The proportion of low attenuation muscle was associated with DFS in resected lung cancer patients. Further investigation is needed to establish whether radiodensity-based detailed skeletal muscle quantification could be early biomarker to predict prognosis in NSCLC.

Sarcopenia is the degenerative loss of skeletal muscle mass and function associated with aging and occurs in the absence of any underlying disease or condition. A comparison of the age-related molecular signaling signatures of different muscles has not previously been reported. In this study, we compared the age-related molecular signaling signatures of the intercostal muscles, the diaphragm, and the gastrocnemii using 6-month and 20-month-old rats. The phosphorylation of Akt, ribosomal S6, and Forkhead box protein O1 (FoxO1) in diaphragms significantly increased with age, but remained unchanged in the intercostal and gastrocnemius muscles. In addition, ubiquitin-proteasome degradation, characterized by the levels of MuRF1 and Atrogin-1, did not change with age in all rat muscles. Interestingly, an increase in LC3BII and p62 levels marked substantial blockage of autophagy in aged gastrocnemii but not in aged respiratory muscles. These changes in LC3BII and p62 levels were also associated with a decrease in markers of mitochondrial quality control. Therefore, our results suggest that the age-related signaling events in respiratory muscles differ from those in the gastrocnemii, most likely to preserve the vital functions played by the respiratory muscles.

For patients with severe burns that consist of contractures induced by fibrous scar tissue formation, a graft must adhere completely to the wound bed to enable wound healing and neovascularization. However, currently available grafts are insufficient for scar suppression owing to their nonuniform pressure distribution in the wound area. Therefore, considering the characteristics of human skin, which is omnidirectionally stretched via uniaxial stretching, we proposed an auxetic skin scaffold with a negative Poisson’s ratio (NPR) for tight adherence to the skin scaffold on the wound bed site. Briefly, a skin scaffold with the NPR effect was fabricated by creating a fine pattern through 3D printing. Electrospun layers were also added to improve adhesion to the wound bed. Fabricated skin scaffolds displayed NPR characteristics (−0.5 to −0.1) based on pulling simulation and experiment. Finger bending motion tests verified the decreased marginal forces (<50%) and deformation (95%) of the scaffold comprising rarely dead cells and their spindle-shaped morphologies revealed the high cytocompatibility of the developed scaffold. Overall, the developed skin scaffold may help reduce wound strictures in the joints of patients with burns as it exerts less pressure on the wound margin.

Type 2 diabetes (T2D) patients suffer from dyspnea, which contributes to disease-related morbidity. Although T2D has been reported to induce a catabolic state in skeletal muscle, whether T2D induces muscle wasting in respiratory muscles has not yet been investigated. In this study, we examine the difference in the molecular signaling signature of muscle wasting between the intercostal and gastrocnemius muscles using db/db mice, a well-known diabetic mouse model. Akt phosphorylation was significantly decreased in both the intercostal and gastrocnemius muscles of db/db mice and was accompanied by a decrease in mTORC1 activity. In addition, FoxO phosphorylation was suppressed, and ubiquitin-proteasome degradation, characterized by the level of Atrogin-1 and MuRF1, was subsequently enhanced in both muscle types of db/db mice. An increase in LC3BII levels and a decrease in p62 levels marked the occurrence of substantial autophagy in the gastrocnemius muscle but not in the intercostal muscles of db/db mice. Therefore, we suggest that the signaling events of muscle wasting in the intercostal muscles of db/db mice are different from those in the gastrocnemius muscle of db/db mice.

So Young Lee, M.D., Kun Woo Kim, M.D., Jae-Ik Lee, M.D., Ph.D., Dong-Kyun Park, M.D., Ph.D., Kook-Yang Park, M.D., Ph.D., Chul-Hyun Park, M.D., Ph.D., Kuk-Hui Son, M.D., Ph.D.. Korean J Thorac Cardiovasc Surg 2018;51:76-80. https://doi.org/10.5090/kjtcs.2018.51.1.76