• Korean Journal of Materials Research
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• v.25 no.4
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• pp.165-170
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• 2015

Ceramics biomaterials are useful as implant materials in orthopedic surgery. In this study, porous HA(hydroxyapatite)/${\beta}$-TCP(tricalcium phosphate) composite biomaterials were successfully fabricated using HA/${\beta}$-TCP powders with 10-30 wt% $NH_4HCO_3$ as a space holder(SH) and $TiH_2$ as a foaming agent, and MgO powder as a binder. The HA/${\beta}$-TCP powders were consolidated by spark plasma sintering(SPS) process at $1000^{\circ}C$ under 20 MPa conditions. The effect of SH content on the pore size and distribution of the HA/${\beta}$-TCP composite was observed by scanning electron microscopy(SEM) and a microfocus X-ray computer tomography system(SMX-225CT). These microstructure observations revealed that the volume fraction of the pores increased with increasing SH content. The pore size of the HA/${\beta}$-TCP composites is about $400-500{\mu}m$. The relative density of the porous HA/${\beta}$-TCP composite increased with decreasing SH content. The porous HA/${\beta}$-TCP composite fabricated with 30%SH exhibited an elastic modulus similar to that of cortical bone; however, the compression strength of this composite is higher than that of cortical bone.

• Clinics in Shoulder and Elbow
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• v.9 no.1
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• pp.73-82
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• 2006

Purpose: The purpose of the present study was to evaluate the diagnostic efficacy of CT arthrography (CTA) in the assessment of various shoulder pathologies, compared with MR arthrography (MRA) and MRI with arthroscopic correlation. Materials and Methods: CTA in 84 patients, MRA in 70 patients, and MRI in 27 patients were obtained. A radiologist interpreted each image for 5 pathologies: Bankart, SLAP, Hill-Sachs lesion, full-thickness, and partial-thickness rotator cuff tear. Detailed arthroscopic reports were compared with CTA, MRA, and MRI. The sensitivity, specificity, predictive values, and accuracy were calculated. The agreement between each diagnostic modality and arthroscopy was calculated. Diagnostic efficacy was assessed by the areas under the receiver operating characteristic (ROC) curves. Results: The diagnostic values of all three imaging groups were comparable to each other for Bankart, SLAP, Hills-Sachs, and full-thickness cuff tear lesions, but those of CTA were lower than MRI and MRA for partial-thickness cuff tears. The areas under the ROC curves for CTA, MRA, and MRI were not significantly different for all pathologies, except for partial-thickness cuff tears. Conclusion: CTA was equally competent to MRA or MRI in demonstrating Bankart, Hill-Sachs lesions, SLAP, and full thickness rotator cuff tears but not as efficient in diagnosing partial thickness rotator cuff tears.

• Archives of Reconstructive Microsurgery
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• v.8 no.2
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• pp.139-148
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• 1999

Since Nakayama's first report about venous flap, many experimental and clinical studies were done about this new type of flap. And due to its various benefits, its applications as arterialized venous free flap type have increased recently. In this study we have attempted to reconstruct composite of defects of the hand with new modification of arterialized venous free flap and simultaneous reconstruction of skin, nerve, tendon were performed successfully. From 1994 to 1999, the defects of the hands in 35 patients were reconstructed with various modifications of arterialized venous free flaps. The range of age was from 19 to 55 years and size of flap ranged from $1{\times}2cm\;to\;14{\times}9cm$. Among them, 12 cases of flap over 20cm in size were included. Indications of flaps were as follows: resurfacing of the defects of the skin (9 cases), simultaneous reconstruction of extensor, skin and digital nerve(2 cases), reconstruction of the skin with extensor(5 cases), as a flap-through type vascular reconstruction(6 cases), for digital nerve reconstruction(2 cases), contracture release(3 cases), and finger tip reconstruction(9 cases). All of the cases except one survived with marginal skin necrosis less than 10%. And relatively large flaps over 20cm in size successfully survived without any delay procedures. Composite reconstructions including tendon and nerve were successful with new modifications of this flap. Arterialized venous free flap is one of the useful procedure in reconstruction of the hand because it has many advantages such as non-bulky and good quality of flap, variable length of pedicle, preservation of major vascular pedicle, less operation time, single operative field and in addition possibility of various modifications.

• Archives of Reconstructive Microsurgery
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• v.13 no.1
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• pp.74-81
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• 2004

This study was designed to introduce the cross-leg free flap only for vein anastomosis as an alternative salvage method for the reconstruction of severe soft tissue defects in vascular-compromised lower extremities. Four cross-leg free flap reconstructions were performed using the latissimus dorsi muscle to reconstruct soft tissue defects in the lower extremity. The recipient artery was confined to the ipsilateral side and the venous anastomosis was carried out in the contralateral side. Both legs were immobilized together with an external fixator. All patients were males, and had a mean age of 31 years. The mean time of pedicle division was 8.8 days range of 7 to 10 days. The mean size of the flap was 186.5 cm2. All flaps survived after pedicle division without venous congestion. There was no complication in joint stiffness, nor donor site morbidity except for a linear scar. The cross-leg free flap only for vein anastomosis is a refinement of a salvage procedure used for the reconstruction of severe soft tissue defects in vascular-compromised lower extremities.

• Journal of Biomedical Engineering Research
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• v.17 no.1
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• pp.61-70
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• 1996

In cementless total hip arthroplasty(THA), an initial stability of the femoral component is mandatory to achieve bony inyowth and secondary long term fixation. Primary stability of the femoral component can be obtained by minimizing the magnitude of relative micromotions at bone stem interface. An accurate evaluation of interf'ace micromotion and stress/strain fields in the bone-implant system may be relevant for better understanding of clinical situations and improving THA design. Recently finite element method(FEM) was introduced in'orthopaedic research field due to its unique capacity to evaluate stress in structure of complex shape, loading and material behavior. The authors developed the 3-dimensional finite element model of proximal femur with $Multilock^{TM}$ stem of 1179 blick elements to analyse the micromotions and mechanical behaviors at the bone-stem inteface in early post-operative period for the load simulating single leg stance. The results indicates that the values of relative motion for this well fit stem were $150{\mu}m$ in maximum $82{\mu}m$ in minimum and the largest relative motion was developed in medial region of Proximal femur and in anterior-posterior direction. The motion in the proximal bone was much greater than in the distal bone and the stress pattern showed high stress concentration on the cortex near the tip of the stem. These findings indicate that the loading on the hip joint in the early postoperative situation before achieving bony ingrowth could produce large micromotion of $150{\mu}m$ and clinicaly non-cemented THA patient should not be allowed weight bearing strictly early in the postoperative period.

• The Korean Journal of Physiology and Pharmacology
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• v.21 no.6
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• pp.675-686
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• 2017

Orthostatic hypotension (OH) is associated with symptoms including headache, dizziness, and syncope. The incidence of OH increases with age. Attenuation of the vestibulosympathetic reflex (VSR) is also associated with an increased incidence of OH. In order to understand the pathophysiology of OH, we investigated the physiological characteristics of the VSR in the disorder. We applied sodium nitroprusside (SNP) to conscious rats with sinoaortic denervation in order to induce hypotension. Expression of pERK in the intermediolateral cell column (IMC) of the T4~7 thoracic spinal regions, blood epinephrine levels, and blood pressure were evaluated following the administration of glutamate and/or SNP. SNP-induced hypotension led to increased pERK expression in the medial vestibular nucleus (MVN), rostral ventrolateral medullary nucleus (RVLM) and the IMC, as well as increased blood epinephrine levels. We co-administered either a glutamate receptor agonist or a glutamate receptor antagonist to the MVN or the RVLM. The administration of the glutamate receptor agonists, AMPA or NMDA, to the MVN or RVLM led to elevated blood pressure, increased pERK expression in the IMC, and increased blood epinephrine levels. Administration of the glutamate receptor antagonists, CNQX or MK801, to the MVN or RVLM attenuated the increased pERK expression and blood epinephrine levels caused by SNP-induced hypotension. These results suggest that two components of the pathway which maintains blood pressure are involved in the VSR induced by SNP. These are the neurogenic control of blood pressure via the RVLM and the humoral control of blood pressure via epinephrine release from the adrenal medulla.

• Quality Improvement in Health Care
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• v.15 no.2
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• pp.83-86
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• 2009

연구배경: 수술적 치료가 필요한 척추관 협착증 환자들은 주로 60세 이상의 고령환자로 장기간의 입원 시 기회 감염의 증대와 불필요한 의료비의 증대를 가져오게 되며, 수술 후 환자들의 재원일수의 증가는 병원의 병상가동률을 감소시키고, 전공의에게는 불필요한 업무를 증가시킨다. 연구목적: 비용 효과면에서 최적화된 진료 지침의 개발은 불필요한 의료비의 감소 및 Hospital Induced Complication을 줄여 환자 만족도를 증진시킬 수 있으며, 각 환자에 대한 전공의 업무를 줄일 수 있다. 의료기관: 서울특별시에 소재한 2,075병상의 종합전문요양기관 연구방법: 정형외과 및 신경외과의 척추관 협착증 환자의 처방을 비교하여 최적의 표준진료지침을 개발하고 최종적으로 CP Master Program(EMR 프로그램)에 입력하여 환자에게 적용하였다. 연구결과: CP 적용 전, 후 비교를 통해 재원일수는 3.8일이 감소하였으며, 이에 따라 병상 가동률 및 진료수익이 증가했으리라고 예상되며 현재 비교 검토 중이다. 또한, CP 개발 및 CP Master Program의 사용을 통한 전공의 업무 감소에 대해 검토하고 있다.

• Journal of the Ergonomics Society of Korea
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• v.25 no.4
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• pp.129-135
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• 2006

he purpose of this study is to measure bio-signal to investigate the driver's physiological response change under real situation using train simulator. The train simulator used in this study is KTX model and according to changes of driving situation, The bio-signal controlled by autonomic nervous system, such as GSR(Galvanic Skin Response), SpO2(Saturation percent O2), HR(Heart Rate), ECG(Electrocardiograph), EEG(Electroencephagram) and movement and response of eye were measured. Statistically significant difference in bio-signal data and eye movement activity pattern were investigated under several different driving speeds using analysis of variance (p<0.05). The GSR and HR value measured in average and mission speed operation is higher than in high-speed operation. β wave of EEG in average speed operation become more activated than in high speed operation. In accordance with a characteristic of rail vehicle, movement and response of eye in high-speed operation requiring relatively simple maneuver become less activated than in either average or mission speed operations. Conclusively, due to more careful driving controls in average and mission speed operation are required than in high-speed operation, level of mental and physical stresses of train driver was increased and observed through changes of bio-signal and eye movement measured in this study.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.2 no.1
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• pp.19-37
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• 2004

The purpose of this study was to examine the effects of Progressive Resistive Exercise Program and Aqua Exercise Program on Lower extremity Muscle strength, Balance in Elderly old. The average age of elder female was 71.65 years. Subjects of the study were twenty older women living in daejon. The date were analyzed with frequency, independent t-test, paired t-test using SPSS PC(ver.10.0). The subjects were practiced with focusing on the Progressive Resistive Exercise Program and Aqua Exercise Program for 8 weeks, from 8, April 2002 to 1, June 2002. The results of this study were as follows: 1. After the Progressive Resistive Exercise Program, Balance ability by OLSTR, OLSTL was improved(p<0.05) on the soft surface with close eyes. 2. After the Aqua Exercise Program, the strength of the right knee flexors and extensors was improved(p<0.05). 3. After the Aqua Exercise Program, the strength of the left knee flexors was improved(p<0.01). 4. After the Aqua Exercise Program, Balance ability by OLSTR was improved(p<0.001) on the soft surface with open eyes, close eyes and by OLSTL was improved(p<0.05) on the hard surface with open eyes.

• IMMUNE NETWORK
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• v.2 no.1
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• pp.25-34
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• 2002

Background: Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by synovial hyperplasia and joint destruction. The synovial fibroblasts express cell adhesion molecules and have a role in adhesive interation with inflammatory cells in synovial tissue. It has been suggested that hypoxic conditioins are thought to exist in arthritic joints, and several studies indicate that reactive oxygen species (ROS) produced in hypoxic condition can initiate events that lead to pro-adhesive changes via increased expression of adhesion molecules. So, this study wsa designed to examine whether antioxidant can inhibit hypoxia-induced expression of ICAM-1 in cultured human synovial fibroblasts. Methods: Synovial fibroblasts were isolated from synovial tissue in patients with RA and cultured at hypoxic condition. Antioxidant, PDTC (pyrrolidine dithiocarbamate) were pre-treated for an hour before the hypoxic culture and synovial fibroblasts were harvested at 0, 6, 12, 24, 48 hours time points. Cell surface ICAM-1 expression in synovial fibroblasts was examined by the flow cytometric analysis. To analyse the expression of ICAM-1 mRNA, reverse-transcriptase polymerase chain reaction (RT-PCR) was performed. The levels of cytokines in culture supernatants were measured by ELISA, and activation of NF-${\kappa}B$ was analysed by electrophoretic mobility shift assay. The adhesive reaction between synovial fibroblasts and lymphocytes was assayed by measurement of fluorescent intensity of BCECF-AM in lymphocytes. Results: Hypoxic stimuli up-regulated the ICAM-1 expression as well as the adhesive interaction of human synvial fibroblasts to lymphocytes in a time-dependent manner, and PDTC inhibited hpyoxia-induced ICAM-1 expression and cell-cell interaction. PDTC also inhibited the hypoxia-induced activation of intracellular transcription factor, NF-${\kappa}B$. PDTC decreased the amount of hypoxia-induced production of IL-$1{\beta}$ and TNF-${\alpha}$. Conclusion: These studies demonstrate that PDTC inhibit the hypoxia-induced expression of the adhesion molecule, ICAM-1 and activation of NF-${\kappa}B$ in cultured human synovial fibroblasts.