• Molecules and Cells
• /
• v.43 no.10
• /
• pp.848-855
• /
• 2020

Cells assemble stress granules (SGs) to protect their RNAs from exposure to harmful chemical reactions induced by environmental stress. These SGs release RNAs, which resume translation once the stress is relieved. During stem cell differentiation, gene expression is altered to allow cells to adopt various functional and morphological features necessary to differentiate. This process induces stress within a cell, and cells that cannot overcome this stress die. Here, we investigated the role of SGs in the progression of stem cell differentiation. SGs aggregated during the neuronal differentiation of human bone marrow-mesenchymal stem cells, and not in cell lines that could not undergo differentiation. SGs were observed between one and three hours post-induction; RNA translation was restrained at the same time. Immediately after disassembly of SGs, the expression of the neuronal marker neurofilament-M (NF-M) gradually increased. Assembled SGs that persisted in cells were exposed to salubrinal, which inhibited the dephosphorylation of eukaryotic translation initiation factor 2 subunit 1 (eIF2α), and in eIF2α/S51D mutant cells. When eIF2α/S51A mutant cells differentiated, SGs were not assembled. In all experiments, the disruption of SGs was accompanied by delayed NF-M expression and the number of neuronally differentiated cells was decreased. Decreased differentiation was accompanied by decreased cell viability, indicating the necessity of SGs for preventing cell death during neuronal differentiation. Collectively, these results demonstrate the essential role of SGs during the neuronal differentiation of stem cells.

• Journal of Korean Neurosurgical Society
• /
• v.48 no.2
• /
• pp.139-144
• /
• 2010

Objective : We report our surgical experience in the treatment of 16 consecutive patients with benign craniovertebral junction (CVJ) tumor, observed from 2003 to 2008 at our department. Methods : We had treated 6 foramen magnum meningiomas, 6 cervicomedullary hemangioblastomas, 1 accessory nerve schwannoma, 1 hypoglossal nerve schwannoma, 1 C2 root schwannoma, and 1 cavernous hemangioma. Clinical results were evaluated by Karnofsky Performance Scale (KPS) and all patients underwent preoperative neuroradiological evaluation with computed tomography (CT) and magnetic resonance image (MRI). Angiography was performed in 15 patients and preoperative embolization was done in 2 patients. Results : Five far-lateral, 1 supracondylar and 10 midline suboccipital approaches were performed. Gross total removal was achieved in 15 cases (94%) and subtotal removal in 1 patient (6%). None of the patients required occipitocervical fusion. Radiological follow-up showed no recurrence in cases totally removed. Postoperative decrease of KPS scores was recorded in only 1 patient. The treatment of cervicomedullary solid hemangioblastoma presented particular issues : by preoperative embolization, we removed tumor totally without an excessive bleeding or brainstem injury. In one of foramen magnum meningioma, we carried out subtotal removal due to hard tumor consistency and encasement of neurovascular structures. Conclusion : The choice of surgical approaches and the extent of bone resection should be defined according to the location and size of individual tumors. Moreover, we emphasize that preoperative neuroradiological evaluations on presumptive tumor type could be helpful to the surgeon in tailoring the technique and providing the required exposure for different lesions, without unnecessary surgical steps.

• Archives of Plastic Surgery
• /
• v.38 no.6
• /
• pp.845-850
• /
• 2011

Purpose: In general, orientals including Korean, have a mesocephalic face whereas Caucasians, among the western, have a dolichocephalic face. Unlike the western, in orientals including Korean, prominent malar bones are recognized as stubborn and unattractive appearance. That is why reduction malarplasty is one of the most popular aesthetic surgical procedure in Korea. Many surgical methods to reposition prominent malar bones have been performed by means of a coronal incision or a combined incisions, using both the intraoral and the external incision. Bicoronal approach has advantage such as wide operative field, easy to maintain symmetry and possibility of combining facial lift but has shortcoming, such as external scars, long operative time, and the possibility of facial nerve or artery injury. Intraoral approach has advantages of short operative time, simplicity of procedure and no external scar. But this approach is associated with problems of cheek drooping, limited exposure and difficulty in making symmetry. Methods: During 8 years, we performed a reduction malarplasty without internal fixation through an minimal intraoral incision and dissection in 39 patients. Results: The patients were followed for 46 months, with satisfactory results and no cheek drooping. There was no patient who want to revise the inappropriate operative result such as asymmetry and incomplete correction. Conclusion: We conclude that minimal intraoral incision and dissection could acquire satisfactory result of reduction malarplasty along with prevention of cheek drooping.

• Archives of Plastic Surgery
• /
• v.32 no.4
• /
• pp.447-453
• /
• 2005

The coverage of soft tissue defects around the knee joint or upper one third of lower leg presents a difficult challenge to the reconstructive surgeon. Various reconstructive choices are available depending on the location, size and depth of the defect. The authors present their clinical application of a medial sural artery perforator island flap as a useful alternative method for upper one third of lower leg and knee reconstruction. From 2002 to 2004, we operated total 4 patients (total 4 flaps) using the medial sural artey perforator island flap for coverage of the defect on upper one third of lower leg and knee, of 4 patients, 3 patients was men and one was woman. Average patient age was 54.6 years. The largest flap obtained was 10x8cm2. Postoperative follow up of the patients ranged from two to 33 months. In two cases, defects was located on upper one third of lower leg and in other two cases, defects were on the knee. All four cases had bone exposure open wound. In angiography, 2 cases had injured in the anterior tibial artery, 1 case had injured in the posterior tibial artery. There were no diabetes or other vascular disease. All 4 flaps were survived completely, without minor complications such as venous congestion and hematoma. Donor morbidity was restricted substantially to the donor linear scar. There were no functional impairment. As the main advantages of the medial sural perforator island flap, it ensures constant location and reliable blood supply without sacrificing any main source artery or damaging underlying muscle. This procedure is valuable extension of local flap for defect coverage with minimal functional deficit donor site and good aesthetic result on the defect. We consider it as one of the useful methods of the upper one third of lower leg and knee reconstruction.

• Journal of Korean Neurosurgical Society
• /
• v.39 no.5
• /
• pp.329-334
• /
• 2006

Objective : In selected cases, the transsphenoidal approach[TSA] can be extended anteriorly to the tuberculum sellae, chiasmatic sulcus, and planum sphenoidale to obtain direct exposure of the suprasellar cisterns and its contents. We applied this modification of the TSA to various lesions of the presellar and suprasellar areas. We evaluate our clinical experience of this technique and review the related literature. Methods : From 1999 to 2004, we used the transsphenoidal supradiaphragmatic intradural approachs[TSIAs] in 9 patients who had various lesions at the pre- and suprasellar regions. Concomitant presellar extension of the bone window was performed with the sublabial or transnasal transseptal transphenoidal techniques. After removal of the lesions, sellar or anterior cranial floor was repaired with silicone plate substitute. Results : The TSIAs have been applied in the following cases : four tuberculum sellae meningiomas, two craniopharyngiomas, two Rathke's cleft cysts, and one non-functioning macroadenoma. The complications were one case of visual acuity decrease and one cerebrospinal fluid rhinorrhea. Conclusion : The TSIA is easily applicable through a minor modification of the standard TSA. It is suitable for removing lesions located in the presellar and suprasellar area adjacent to the pituitary stalk with minimal brain manipulation and decreased morbidity.

• Safety and Health at Work
• /
• v.6 no.3
• /
• pp.159-173
• /
• 2015

The hand coordinate systems for measuring vibration exposures and biodynamic responses have been standardized, but they are not actually used in many studies. This contradicts the purpose of the standardization. The objectives of this study were to identify the major sources of this problem, and to help define or identify better coordinate systems for the standardization. This study systematically reviewed the principles and definition methods, and evaluated typical hand coordinate systems. This study confirms that, as accelerometers remain the major technology for vibration measurement, it is reasonable to standardize two types of coordinate systems: a tool-based basicentric (BC) system and an anatomically based biodynamic (BD) system. However, these coordinate systems are not well defined in the current standard. Definition of the standard BC system is confusing, and it can be interpreted differently; as a result, it has been inconsistently applied in various standards and studies. The standard hand BD system is defined using the orientation of the third metacarpal bone. It is neither convenient nor defined based on important biological or biodynamic features. This explains why it is rarely used in practice. To resolve these inconsistencies and deficiencies, we proposed a revised method for defining the realistic handle BC system and an alternative method for defining the hand BD system. A fingertip-based BD system for measuring the principal grip force is also proposed based on an important feature of the grip force confirmed in this study.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.27 no.6
• /
• pp.565-569
• /
• 2001

A new surgical approach to the area of the infratemporal fossa and parapharyngeal space is described. This approach results in a wide-field exposure of the infratemporal fossa, pterygomaxillary space and parapharyngeal space. We used two osteotomies on the patient's mandible and temporary resection of zygomatic arch for superior margin of tumor. Lower lip splitting was not needed because the incision was started in the frontal scalp, curved in front of and below the external auditary canal, and extended anteriorly to the greater horn of hyoid bone on the neck along a skin crease. We had good results without sacrifice of the facial nerve, mandibular function and sensory supply of the face and oral cavity.

• Korean Journal of Cleft Lip And Palate
• /
• v.6 no.1
• /
• pp.27-34
• /
• 2003

Patients with maxillary hypoplasia secondary to cleft lip and palate present numerous challenging problems for the oral and maxillofacial surgeon, These patients present with maxillary hypoplasia in multiclimensions, and often have thin or structually weak bone. This deformity has been traditionally corrected by Le Fort I osteotomy and acute skeletal advancement with wide surgical exposure. The long-term results of cleft patients with maxillary deficiency treated with this traditional approach has been sometimes disappointing, and an increased relapse tendency has been reported, Distraction osteogenesis for these cleft patients offers successful results while potentially minimizing the risk of relapse. Advancing the maxilla via distraction forces requires only a minor surgical procedure that maintains vascularity and neurosensory integrity. Moreover, the response of the facial soft tissues during maxillary distraction has proven to be more favorable than with a conventional LeFort I osteotomy. The purpose of this report is to present the use of maxillary distraction osteogenesis by rigid external distraction (RED) system for the treatment of patient with maxillary deficiency secondary to cleft lip and palate.

• Journal of Radiation Protection and Research
• /
• v.44 no.4
• /
• pp.149-155
• /
• 2019

Background: Magnetic resonance (MR) image guided radiation therapy system, enables real time MR guided radiotherapy (RT) without additional radiation exposure to patients during treatment. However, MR image lacks electron density information required for dose calculation. Image fusion algorithm with deformable registration between MR and computed tomography (CT) was developed to solve this issue. However, delivered dose may be different due to volumetric changes during image registration process. In this respect, synthetic CT generated from the MR image would provide more accurate information required for the real time RT. Materials and Methods: We analyzed 1,209 MR images from 16 patients who underwent MR guided RT. Structures were divided into five tissue types, air, lung, fat, soft tissue and bone, according to the Hounsfield unit of deformed CT. Using the deep learning model (U-NET model), synthetic CT images were generated from the MR images acquired during RT. This synthetic CT images were compared to deformed CT generated using the deformable registration. Pixel-to-pixel match was conducted to compare the synthetic and deformed CT images. Results and Discussion: In two test image sets, average pixel match rate per section was more than 70% (67.9 to 80.3% and 60.1 to 79%; synthetic CT pixel/deformed planning CT pixel) and the average pixel match rate in the entire patient image set was 69.8%. Conclusion: The synthetic CT generated from the MR images were comparable to deformed CT, suggesting possible use for real time RT. Deep learning model may further improve match rate of synthetic CT with larger MR imaging data.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.13 no.2
• /
• pp.153-159
• /
• 1991

The use of the autogenous free fat is a well-known procedure to fill in superficial depressions resulting from the traumatic or congenital defects. The major donor site for this procedure was the abdominal subcutaneous fat or buttocks. In 1977, Egyedi was the first to report the use of the buccal fat pad as a pedicled graft. The buccal fat pad is a structure usually considered to be a nuisance when encountered in intraoral procedures such as facial bone osteotomies, elevation of buccal falp, or procedures on Stensen's duct. In these operations, appearance of the buccal fat pad complicates surgical exposure. The buccal fat pad is a lobulated convex mass of fatty tissue covered by a very delicate membrane, and is described as having a body from which four processes extend. These projection serve as a filling material between the various muscular structures in the area. Recently malar depression was augmented with the pedicled buccal fat pad in 3 cases, and it was used for the reconstruction of the nasolabial fold in one case.