Mechanical compression creates a quiescent muscle stem cell niche.

Tissue stem cell niches are regulated by their mechanical environment, notably the extracellular matrix (ECM). Skeletal muscles consist of bundled myofibers for force transmission. Within this macroscopic architecture, quiescent Pax7-expressing (Pax7+) muscle stem cells (MuSCs) are compressed between ECM basally and myofiber apically. Muscle injury causes MuSCs to lose apical compression from the myofiber and re-enter the cell cycle for regeneration. While ECM elasticities have been shown to affect MuSC's renewal, the significance of apical compression remains unknown. To investigate the role of apical compression, we simulate the MuSCs' in vivo mechanical environment by applying physical compression to MuSCs' apical surface. We demonstrate that compression drives activated MuSCs back to a quiescent stem cell state, regardless of basal elasticities and chemistries. By mathematical modeling and cell tension manipulation, we conclude that low overall tension combined with high axial tension generated by compression leads to MuSCs' stemness and quiescence. Unexpectedly, we discovered that apical compression results in up-regulation of Notch downstream genes, accompanied by the increased levels of nuclear Notch1&3 in a Delta ligand (Dll) and ADAM10/17 independent manner. Our results fill a knowledge gap on the role of apical compression for MuSC fate and have implications to stem cells in other tissues.

Reconstruction of a pathologic fracture following osteomyelitis of the mandible using a fibula osteocutaneous flap.

The use of a fibula osteocutaneous flap is currently the mainstay of segmental mandibular reconstruction. This type of flap is used to treat tumors, trauma, or osteoradionecrosis of the mandible. However, a fibula osteocutaneous flap may also be a good option for reconstructing the mandible to preserve oropharyngeal function and facial appearance in cases of pathological fracture requiring extensive segmental bone resection. Chronic osteomyelitis is one of the various causes of subsequent pathologic mandibular fractures; however, it is rare, and there have been few reports using free flaps in osteomyelitis of the mandible. We share our experience with a 76-year-old patient who presented with a pathologic fracture following osteomyelitis of the mandible that was reconstructed using a fibula osteocutaneous flap after wide segmental resection.

Anthropometric Changes in the Upper Lip Between the Standing Position in the Clinic and Supine Position on the Operative Table in Secondary Cleft Lip Nasal Deformities.

BACKGROUND: We evaluated changes in lip height and length by position in cleft lip nasal deformity patients who underwent treatment with Millard technique. METHODS: A retrospective review of the medical records and an anthropometric analysis of photographs were performed in 209 cases of cleft lip nasal deformity. In the photogrammetric analysis, the lip height and length were calculated with respect to the intercanthal width. To evaluate the change in the difference between the cleft- and noncleft-side measurements between the standing and supine positions, the difference between the cleft- and noncleft-side measurements (Δnc-c) was calculated. We identified which patients and surgical factors affected the difference between the cleft- and noncleft-side measurements between the standing and supine positions (Δst-sp). RESULTS: From a total of 120 cases, cases with missing medical charts and clinical photographs were excluded, and 89 cases were included in this study. The discrepancy between the cleft-side lip height and noncleft-side lip height was significantly different between the standing and supine positions (P = 0.007). According to the univariate regression analysis, Δst-sp (sbal-cphi) had a significant positive correlation with body mass index (P = 0.044). In the final multiple linear regression analysis, body mass index had a significant positive correlation with Δst-sp (sbal-cphi, P = 0.044). CONCLUSION: In our results, the difference in vertical lip height is easy to underestimate in the supine position during surgery. Therefore, surgeons should verify lip height with the patient in the sitting or standing position during the operation to avoid undercorrecting lips with short heights.

Meningothelial hamartoma of the scalp.

Meningothelial hamartoma is a benign tumor composed of ectopic meningothelial elements in the dermis and subcutaneous tissue. It mainly occurs in the scalp; however, the incidence is extremely low. The origin of meningothelial hamartoma has not been elucidated; nevertheless, it has been theorized that it derives from ectopic meningothelial rests displaced during embryologic development. It can be diagnosed histologically as proliferation of connective tissue elements and cells arranged in solid nests, resembling vascular tumors. On immunohistochemistry, it stains positively for epithelial membrane antigen and vimentin. At least 17 cases have been reported, verifying the rarity of the lesion. We present the case of a 16-year-old male patient with a soft scalp mass which was thought to be a lipoma, but turned out to be a meningothelial hamartoma on histology.

Economic analysis of cloud-based desktop virtualization implementation at a hospital.

BACKGROUND: Cloud-based desktop virtualization infrastructure (VDI) is known as providing simplified management of application and desktop, efficient management of physical resources, and rapid service deployment, as well as connection to the computer environment at anytime, anywhere with any device. However, the economic validity of investing in the adoption of the system at a hospital has not been established. METHODS: This study computed the actual investment cost of the hospital-wide VDI implementation at the 910-bed Seoul National University Bundang Hospital in Korea and the resulting effects (i.e., reductions in PC errors and difficulties, application and operating system update time, and account management time). Return on investment (ROI), net present value (NPV), and internal rate of return (IRR) indexes used for corporate investment decision-making were used for the economic analysis of VDI implementation. RESULTS: The results of five-year cost-benefit analysis given for 400 Virtual Machines (VMs; i.e., 1,100 users in the case of SNUBH) showed that the break-even point was reached in the fourth year of the investment. At that point, the ROI was 122.6%, the NPV was approximately US$192,000, and the IRR showed an investment validity of 10.8%. From our sensitivity analysis to changing the number of VMs (in terms of number of users), the greater the number of adopted VMs was the more investable the system was. CONCLUSIONS: This study confirms that the emerging VDI can have an economic impact on hospital information system (HIS) operation and utilization in a tertiary hospital setting.

Fluorescence turn-on probe for homocysteine and cysteine in water.

A simple fluorescent probe based on an ortho-hydroxy aldehyde-functionalized coumarin showed selective responses to homocysteine and cysteine by fluorescence turn-on.