• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회A
• /
• pp.372-377
• /
• 2007

For more than 2,500 years, surgical teaching has been based on the so called "see one, do one, teach one" paradigm, in which the surgical trainee learns by operating on patients under close supervision of peers and superiors. However, higher demands on the quality of patient care and rising malpractice costs have made it increasingly risky to train on patients. Minimally invasive surgery, in particular, has made it more difficult for an instructor to demonstrate the required manual skills. It has been recognized that, similar to flight simulators for pilots, virtual reality (VR) based surgical simulators promise a safer and more comprehensive way to train manual skills of medical personnel in general and surgeons in particular. One of the major challenges in the development of VR-based surgical trainers is the real-time and realistic simulation of interactions between surgical instruments and biological tissues. It involves multi-disciplinary research areas including soft tissue mechanical behavior, tool-tissue contact mechanics, computer haptics, computer graphics and robotics integrated into VR-based training systems. The research described in this paper addresses the problem of characterizing soft tissue properties for medical virtual environments. A system to measure in vivo mechanical properties of soft tissues was designed, and eleven sets of animal experiments were performed to measure in vivo and in vitro biomechanical properties of porcine intra-abdominal organs. Viscoelastic tissue parameters were then extracted by matching finite element model predictions with the empirical data. Finally, the tissue parameters were combined with geometric organ models segmented from the Visible Human Dataset and integrated into a minimally invasive surgical simulation system consisting of haptic interface devices and a graphic display.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제26권6호
• /
• pp.565-580
• /
• 2000

This study was designed to evaluate the influence of cultured epidermal tissue graft and the administration of transforming growth factor(TGF)-${\beta}_3$ on maxillary growth in surgically created palatal defects. A total of 155 rats were divided into 2 groups according to surgical timing : postnatal 2 weeks(n=95), 4 weeks(n=40) and control(unoperated) group(n=20). The postnatal 2-week surgical group was subdivided into 3 groups according to repair methods: conventional surgery(Von Langenbeck technique)group(n=23); cultured tissue graft group(n=25); and full thickness skin graft group(n=25). Additionally, recombinant human TGF-${\beta}_3$ was administered(30ng or 150ng) on collagen matrix in surgically created palatal defects during surgery(9 conventional surgeries, 9 cultured tissue grafts) in 2-week-old rats. The results showed that all types of surgical treatment decreased maxillary growth compared with the control(unoperated) group(p<0.0001). On the other hand, the tissue graft group, whether cultured tissue or grafted skin, contributed to increased maxillary growth(p<0.0001).And exogenous TGF-${\beta}_3$ might play a role in connective tissue proliferation and new bone generation during wound healing on palatal defects. Our results suggest that grafting cultured epidermis with collagen matrix decreases the scar tension on maxillary growth more than conventional palatal surgery does. Therefore, exogenous TGF-${\beta}_3$ may contribute to accelerate wound healing on palatal defects.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제39권2호
• /
• pp.55-62
• /
• 2013

Bone tissue engineering is one of the important therapeutic approaches to the regeneration of bones in the entire field of regeneration medicine. Mesenchymal stem cells (MSCs) are actively discussed as material for bone tissue engineering due to their ability to differentiate into autologous bone. MSCs are able to differentiate into different lineages: osteo/odontogenic, adipogenic, and neurogenic. The tissue of origin for MSCs defines them as bone marrow-derived stem cells, adipose tissue-derived stem cells, and, among many others, dental stem cells. According to the tissue of origin, DSCs are further stratified into dental pulp stem cells, periodontal ligament stem cells, stem cells from apical papilla, stem cells from human exfoliated deciduous teeth, dental follicle precursor cells, and dental papilla cells. There are numerous in vitro/in vivo reports suggesting successful mineralization potential or osteo/odontogenic ability of MSCs. Still, there is further need for the optimization of MSCs-based tissue engineering methods, and the introduction of genes related to osteo/odontogenic differentiation into MSCs might aid in the process. In this review, articles that reported enhanced osteo/odontogenic differentiation with gene introduction into MSCs will be discussed to provide a background for successful bone tissue engineering using MSCs with artificially introduced genes.

• Asian Pacific Journal of Cancer Prevention
• /
• 제14권3호
• /
• pp.1681-1685
• /
• 2013

Background: Head and neck SCC is a common cancer related to various factors. IL-10, a pleiotropic cytokine produced by macrophages, T-helper-2 cells, and B lymphocytes, is thought to play a potential pathogenetic or therapeutic role in a number of human conditions, such as inflammation, autoimmunity and cancer. The present study was designed to evaluate the relation between tissue expression, serum and salivary levels of IL-10 in head and neck squamous cell carcinomas (HNSCCs) and their correlation with clinicopathologic features. Materials and Methods: Samples were collected from 30 patients with HNSCCs and 24 healthy volunteers. IHC analysis was used to examine the tissue expression and ELISA was employed to measure serum and salivary levels. Results: Our study showed tissue expression of IL-10 to be significantily higher in patients (P: 0.001), but there was no relation between tissue expression, serum and salivary levels of the marker (P>0.05). Also except for a positive correlation between tissue expression of IL-10 and stage (P: 0.044), there was no relation between this marker and clinicopathologic features. There was no correlation between serum and salivary levels in either patients or controls. Conclusions: It seems there is no correlation between level of IL-10 in serum and saliva and this marker in saliva and serum does not reflect tissue expression.

• Journal of Periodontal and Implant Science
• /
• 제39권4호
• /
• pp.391-398
• /
• 2009

Purpose: The purpose of this study was to quantify and compare the expressions of CRP and M-CSF in the gingival tissues of the patients with chronic periodontitis associated to hypertension. Methods: Gingival tissue samples were obtained during periodontal surgery or tooth extraction. Clinically healthy gingival tissue samples from systemically healthy 12 patients were categorized as group 1 (n=12). Inflammatory gingival tissue samples from patients with chronic periodontitis were categorized as group 2 (n=12). Inflammatory gingival tissue samples from patients with chronic periodontitis associated with hypertension were categorized as group 3 (n=12). Tissue samples were prepared and analyzed by Western blotting. The quantification of CRP and M-CSF were performed using a densitometer and statistically analyzed by one-way ANOVA followed by Tukey test. Results: There were significant differences between group 1 and group 2 and between group 1 and group 3 in both CRP and M-CSF. The differences between group 2 and group 3 were not statistically significant in both proteins. However, the expression levels of CRP and M-CSF in hypertensive inflammatory gingiva showed increased tendency compared to non-hypertensive inflammatory gingiva. Conclusions: It is suggested that CRP and M-CSF might be used as inflammatory and bone resorption markers in periodontal diseased tissue. It is assumed that hypertension may be associated with the progression of periodontal inflammation and alveolar bone resorption.

• 대한기계학회논문집B
• /
• 제35권11호
• /
• pp.1237-1242
• /
• 2011

인산칼슘 재료는 하이드록시 아파타이트(Hydroxyapatite)와 트리칼슘 포스페이트(Tricalcium-phosphate)를 포함하고 있으며, 인체 골 조직의 무기성분으로 세포 독성이 없고 생체 적합한 성질을 가지고 골 전도성이 있다. 또한 두 재료가 혼합되어 있는 이상 인산칼슘(Biphasic calcium phosphate) 재료는 골 유도성이 있다고 알려져 있다. 이러한 골 조직 재생에 많은 장점을 가지고 있는 인산칼슘 재료는 파우더 타입으로, 3 차원 자유형상의 인공지지체를 제작하는 데 어려움이 있어 고분자 재료에 첨가하여 사용되었다. 본 연구에서는 자유형상 제작 기술을 이용하여 원하는 내/외부 형상을 가지는 3 차원 인산칼슘 인공지지체를 제작하고, 골 조직 재생용 인공지지체로의 사용이 적합한지를 확인하기 위해 MC3T3-E1 를 이용한 세포 증식, 골 조직 분화 실험을 수행하였다.

• Journal of Periodontal and Implant Science
• /
• 제37권4호
• /
• pp.849-857
• /
• 2007

Purpose: The purposes of this study were to compare and quantify the expressions of RANK and RANKL in the gingival tissues of non-periodontitis patient and patients with chronic periodontitis, in order to understand the contribution of these proteins to periodontal destruction. Material and methods: Gingival tissue samples were obtained during periodontal surgery or tooth extraction. According to the patient's systemic condition & clinical criteria of gingiva, each gingival sample was divided into two groups. Group 1 (n=8) is clinically healthy gingiva without bleeding and no evidence of bone resorption or periodontal pockets, obtained from non-periodontitis patients. Group 2 (n=8) is inflammed gingiva from patients with chronic periodontitis. Tissue samples were prepared and analyzed by Western blotting. The quantification of RANK and RANKL were performed using a densitometer and statistically analyzed by Student's t-Test. Results: The expression of RANK were similar in group 1 and 2. The difference between group 1 and 2 was not statistically significant. And the mean amount of RANKL was more increased in group 2 than group 1. The difference between group 1 and group 2 was statistically significant. Conclusion: The expression level RANK didn't show any significant difference between healthy tissue from non-periodontitis patients and inflamed tissue from chronic periodontitis, but the expression level of RANKL in inflammed tissue from chronic periodontitis showed significantly increased tendency compared to healthy gingiva from non-periodontitis patients. Therefore, characteristics of RANK and RANKL in progress of chronic periodontitis would be basis of further studies in diagnostic method and treatment index of the disease.

• 비파괴검사학회지
• /
• 제32권5호
• /
• pp.469-483
• /
• 2012

인체 연조직에서 기계적인 진동의 전달 특성은 조직의 탄성 특성에 의존한다. 연조직의 진동 특성으로부터 암이나 종양을 진단할 수 있기 때문에 진동의 전달 특성에 대한 연구는 중요한 의미를 가진다. 이 논문은 연조직의 표면에 위치하는 여러 형태의 응력 진동원에 의해 연조직 내에 발생되는 변위 패턴을 분석하고 비교하였다. 진동원으로는 수직하중, 접선하중, 그리고 면외전단하중이 고려되었다. 점탄성 단일층에서의 변위에 대한 이론적 표현식을 구하였고, 수치계산은 반공간 및 무한평판조직에서 수행되었다. 그리고 유한크기조직에서의 변위패턴을 유한요소법으로 시뮬레이션하였다. 응력 형태, 진동원 크기 및 주파수, 그리고 경계면이 변위에 미치는 영향이 분석되었다.

• Journal of Industrial and Engineering Chemistry
• /
• 제67권
• /
• pp.388-395
• /
• 2018

Significant efforts have been applied toward fabricating three-dimensional (3D) scaffolds using 3D-bioprinting tissue engineering techniques. Gelatin has been used in 3D-bioprinting to produce designed 3D scaffolds; however, gelatin has a poor printability and is not useful for fabricating desired 3D scaffolds using 3D-bioprinting. In this study, we fabricated pore size controlled 3D gelatin scaffolds with two step 3D-bioprinting approach: a low-temperature ($-10^{\circ}C$) freezing step and a crosslinking process. The scaffold was crosslinked with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). The pore sizes of the produced 3D gelatin scaffolds were approximately 30% smaller than the sizes of the designed pore sizes. The surface morphologies and pore sizes of the 3D gelatin scaffolds were confirmed and measured using scanning electron microscopy (SEM). Human dermal fibroblasts (HDFs) were cultured on a 3D gelatin scaffold to evaluate the effect of the 3D gelatin scaffold pore size on the cell proliferation. After 14 days of culture, HDFs proliferation throughout the 3D gelatin scaffolds prepared with more than $580{\mu}m$ pore size was approximately 14% higher than proliferation throughout the 3D gelatin scaffold prepared with a $435{\mu}m$ pore size. These results suggested that control over the 3D gelatin scaffold pore size is important for tissue engineering scaffolds.

• Animal cells and systems
• /
• 제5권3호
• /
• pp.231-236
• /
• 2001

SINE-R retroposons have been derived from human endogenous retrovirus HERV-K family and found to be hominoid specific. Both SINE-R retroposons and HERV-K family are potentially capable of affecting the expression of closely located genes. From cDNA library of human fetal brain, we identified seven SINE-R retroposons and compared them with sequences derived from GenBank database. The SINE-R retroposons from human feta1 brain showed 85∼97% sequence similarities with the human-specific retroposon SINE-R.C2. They also showed 88∼96% sequence similarities with the sequence of the schizo-cDNA clone that derived from postmortem frontal cortex tissue of a schizophrenic patient. Phylogenetic analysis using the neiqhbor-joining method revealed that the seven new SINE-R retroposons from cDNA library of the human feta1 brain have proliferated independently during human evolution. The data indicate that such SINE-R retroposons are expressed in human fetal brain and deserve further investigation as potential leads to understanding of neuropsychiatric diseases.