• 한국재료학회지
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• 제25권4호
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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.

• 대한두개안면성형외과학회지
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• 제24권2호
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• pp.59-65
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• 2023

Background: Fibrous dysplasia (FD) is a localized bone disorder in which fibro-osseous tissue replaces the normal bone structure. Patients with craniofacial FD often present with gradual swelling, deformity, and compromised vision or hearing. We previously introduced "the core extirpation method," a novel surgical technique that is minimally invasive like traditional bone shaving but has longer-lasting effects. This study presents the long-term outcomes of our core extirpation method. Methods: We conducted a retrospective analysis of patients who underwent core extirpation for FD of the zygomaticomaxillary region from 2012 through 2021. Computed tomography (CT) scans were performed 6 to 12 months before the operation, immediately before and after the operation, and during follow-up visits. We performed all operations using the upper gingivobuccal approach, and we extirpated the core of the lesion while preserving the cortical structures of the zygoma and the maxilla to maintain symmetrical facial contour. Results: In 12 patients with lesions in the growth phase, anteroposterior/mediolateral (AP/ML) length discrepancies and the volume increased between preoperative and immediate postoperative CT scans. All patients' immediate postoperative AP/ML discrepancies were stable up to 12-17 months postoperatively. Postoperative volume showed continuous lesion growth; the median volume growth rate was 0.61 cc per month. Conclusion: In this article, we present our experiences managing FD using the minimally invasive core extirpation technique, which entails small expected blood loss and can be performed as day surgery. It provides similar cosmetic outcomes as traditional bone shaving but with longer-lasting results. Although there are some limitations with the study's retrospective nature and small sample size, our 4-year follow-up results show promising results of the core extirpation method in well-indicated patients.

• 한국전문물리치료학회지
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• 제10권3호
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• pp.17-27
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• 2003

Repetitive transcranial magnetic stimulation (rTMS) modulates cortical excitability beyond the duration of the rTMS trains themselves. Depending on rTMS parameters, a lasting inhibition or facilitation of cortical excitability can be induced. Therefore, rTMS of high or low frequency over motor cortex may change certain aspects of motor learning performance and cortical activation. This study investigated the effect of high and low frequency subthreshold rTMS applied to the motor cortex on motor learning of sequential finger movements and brain activation using functional MRI (fMRI). Three healthy right-handed subjects (mean age 23.3) were enrolled. All subjects were trained with sequences of seven-digit rapid sequential finger movements, 30 minutes per day for 5 consecutive days using their left hand. 10 Hz (high frequency) and 1 Hz (low frequency) trains of rTMS with 80% of resting motor threshold and sham stimulation were applied for each subject during the period of motor learning. rTMS was delivered on the scalp over the right primary motor cortex using a figure-eight shaped coil and a Rapid(R) stimulator with two Booster Modules (Magstim Co. Ltd, UK). Functional MRI (fMRI) was performed on a 3T ISOL Forte scanner before and after training in all subjects (35 slices per one brain volume TR/TE = 3000/30 ms, Flip angle $60^{\circ}$, FOV 220 mm, $64{\times}64$ matrix, slice thickness 4 mm). Response time (RT) and target scores (TS) of sequential finger movements were monitored during the training period and fMRl scanning. All subjects showed decreased RT and increased TS which reflecting learning effects over the training session. The subject who received high frequency rTMS showed better performance in TS and RT than those of the subjects with low frequency or sham stimulation of rTMS. In fMRI, the subject who received high frequency rTMS showed increased activation of primary motor cortex, premotor, and medial cerebellar areas after the motor sequence learning after the training, but the subject with low frequency rTMS showed decreased activation in above areas. High frequency subthreshold rTMS on the motor cortex may facilitate the excitability of motor cortex and improve the performance of motor sequence learning in normal subject.

• 대한의용생체공학회:의공학회지
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• 제37권2호
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• pp.90-103
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• 2016

본 연구는 유한 요소 법을 이용한 노화되어 강성/강도가 저하되는 요추 체의 얇은 피질과 해면 골의 하중 분담 비율 분석과 사용된 탄성계수들의 평가가 목적이다. 해면 골의 나은 해석을 위하여, 20년마다 압축 시험에서 얻은 탄성계수를 체적 공극 비율로 나눈 유효 탄성계수를 사용하였다. 이와 상응하는 피질 쉘도 공극 비율을 포함한 빔 이론의 수식들로부터 유효 탄성계수를 구한 후에 적용하였다. 또한 p-요소를 사용하여 수치 오차를 최소화하였다. 보고된 논문들을 참고하여 후관절 부분이 제거된 매개 변수적인 퇴행된 L3 척추 형상을 만들어 유한 요소 모델링 하였다. 일정 변위의 압축 조건을 가한 후에 여덟 조각의 부피 별로 각 뼈에서 탄성 변형률 에너지와 수직 하중의 비율을 사용하여 하중 분담 비율을 계산하였다. 결과로는 1) 20대에서 80대까지 해면 골의 하중 비율은 55%에서 49%로 감소하였다; 2) 피질 쉘은 중간 면에서 최고 비율을, 해면 골은 종판에서 최고 비율을 나타냈다; 3) 다공성 얇은 피질과 해면 골을 위한 유효 탄성계수의 사용은 적절하였다; 4) 두 방법을 이용하여 얻은 하중 분담 비율의 차이는, 전체 비율은 1% 미만 내에서 같지만 각 위치에서의 비율 값들은 약간 달랐다.

• The Korean Journal of Physiology
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• 제18권2호
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• pp.117-124
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• 1984

It has been recently reported that cingulate cortex mar facilitate gastric acid secretion, but its facilitatory mechanism on the gastric acid secretion is still unclear. This study was undertaken to investigate the facilitatory mechanism of the cingulate cortex upon gastric acid secretion in rats. Twenty·three male albino rats were divided into the cingulate(N= 13) and the operated control(N= 10) groups. The cingulate group in which cingulate cortex was removed by suction through a slit-shaped opening on each side of, and parallel to, the sagittal suture. In the operated control group, the surgical procedure was ended with the skull opening and the incision of dura mater. The gastric juice was collected via a chronic gastric cannula after 24 hours of fast, with water ad libitum. The juice was collected continuously for 6 hours, starting 3 hours prior to the injection of gastric secretagogue, pentagastrin$(12\;{\mu}g/kg)$ or histamine dihydrochloride $(320\;{\mu}g/kg)$. Three one·hour samples were obtained before ana after the administration of each secretagogue. The two agents were injected separately and subcutaneously at intervals of 1 week, the blood samples were drawn from the abdominal aorta for the radioimmunoassay of postprandial plasma gastrin concentration in response to the forced feeding of 10% cod liver oil. 1) After pentagastrin administration, the volume of gastric juice tended to decrease, but its acidity tended to increase in the cingulate group compared with those of the operated control group. However, there was no any difference in the acid output between the two groups. 2) Histamine-stimulated acid output and volume of the gastric juice of the cingulate group decreased significantly compared with those of the operated control group, while there was not significantly different in the acidity between the two groups. 3) Before pentagastrin or histamine administration, any change was not observed in the gastric acid secretion following the cingulate cortical ablation. 4) Postprandial plasma gastrin concentration in response to the forced feeding of 10% cod liver oil was insignificantly lower in the cingulate group than in the operated control group. It is inferred from the above results that the cingulate cortex exerts a facilitatory influence upon the histamine-stimulated gastric acid secretion in rats, and its influence may not be mediated by the stimulation of gastrin secretion.

• 한국컴퓨터그래픽스학회논문지
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• 제6권1호
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• pp.19-27
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• 2000

본 논문에서는 볼륨 데이터로부터 관심대상 객체의 3차원 경계면을 추출하고 이에 대한 기하학적 모델을 생성하기 위하여 자체교차방지 기능을 가진 다해상도 변형 모델을 제시한다. 변형 모델은 경계면 추출에 우수한 성능을 가진 것으로 알려져 있지만, 기존 변형 모델은 초기화 의존성, 오목한 경계면 추출의 취약성, 모델 요소간 자체교차 발생의 세가지 문제점을 가지고 있다. 제안하는 변형 모델은 다해상도의 볼륨 데이터를 기반으로하여 모델을 저해상도에서 고해상도로 세분화해가면서 객체의 경계면을 추출함으로서 초기화에의 의존성을 극복할 뿐 아니라 빠른 속도로 경계면에 수렴할 수 있다. 또한, 삼각형 메쉬 크기를 볼륨 데이터의 복셀 크기에 맞추어 항상 균일하게 유지함으로써 모델이 내부 힘의 제약없이 오목한 경계면을 성공적으로 추출할 수 있게 하였고, 모델이 변형될 때마다 자체교차방지 힘을 적용하여 모델내 삼각형 메쉬간의 자체교차를 사전에 방지할 수 있도록 하였다. 제안 모델을 컴퓨터 합성 볼륨 데이터 및 뇌 MR 볼륨 영상 데이터에 적용한 결과 오목한 함몰 부위를 가진 구와 뇌피질의 경계면을 자체교차없이 빠른 속도로 추출할 수 있었다.

• Journal of Korean Neurosurgical Society
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• 제38권5호
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• pp.359-365
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• 2005

Objective : The study investigates the extent of brain shift and its effect on the accuracy of the stereotaxic procedure. Methods : Thirty-five patients underwent 40stereotactic procedures between June 2002 and March 2004. There were 26 males, mean age 59years old. There were 34procedures for Parkinson's disease, 2 for essential tremor, 3 for cerebral palsy, 1 for dystonia. Patients were divided in four groups based on postoperative pneumocephalus : under 5cc [9 procedures], between $5{\sim}10cc$ [13procedures], between $10{\sim}15cc$ [11 procedures] and more than 15cc [7procedures]. The coordinates of the anterior commissure[AC], posterior commissure[PC], and target were defined in pre-and intraoperative magnetic resonance image scans and the amount of air volume was measured with @Target (BrainLab, Heimstetten, Germany]. Results : The mean AC-PC was 26.5mm for patients with less than 5cc, 26.9mm for $5{\sim}10cc$, 25.8mm for $10{\sim}15cc$ and 26.2mm for more than 15cc. The length of AC-PC line and coordinates of AC, PC was also not statistically different, Euclidean distance as well as ${\Delta}x$, ${\Delta}y$, ${\Delta}z$ of AC, PC, and target were also not statistically different among the groups [p>,1]. There was a variance in target of $0.7{\sim}7.6mm$, Euclidean distance of 2.5mm, related to electrophysiology but not to brain-shift. Conclusion : The amount of air accumulated in the intracranial space and compressing the cortical surface has no effect on the localization of subcortical stereotactic target and landmarks.

• Journal of Korean Neurosurgical Society
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• 제40권3호
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• pp.180-185
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• 2006

Objective : Middle cerebral artery occlusion[MCAO] has widely been used to produce ischemic brain lesions. The lesions induced by MCAO tend to be variable in size because of the variance in the collateral blood supply found in the mouse brain. To establish a less invasive and reproducible focal ischemia model in mice, we modified the technique used for rat photo thrombosis model. Methods : Male C57BL/6 mice were subjected to focal cerebral ischemia by photothrombosis of cortical microvessels. Cerebral infarction was produced by intraperitoneal injection of Rose Bengal, a photosensitive dye and by focal illumination through the skull. Motor impairment was assessed by the accelerating rotarod and staircase tests. The brain was perfusion-fixed for histological determination of infarct volume four weeks after stroke. Results : The lesion was located in the frontal and parietal cortex and the underlying white matter was partly affected. A relatively constant infarct volume was achieved one month after photothrombosis. The presence of the photothrombotic lesion was associated with severe impairment of the motor performance measured by the rotarod and staircase tests. Conclusion : Photothrombotic infarction in mice is highly reproducible in size and location. This procedure can provide a simple method to produce cerebral infarction in a unilateral motor cortex lesion. In addition, it can provide a suitable model for study of potential neuroprotective and therapeutic agents in human stroke.

• Journal of Radiation Protection and Research
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• 제41권3호
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• pp.253-259
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• 2016

Background: This study investigated the effects of zoledronic acid (ZA) on radiation-induced bone loss in C3H/HeN mice. Materials and Methods: C3H/HeN mice were divided into sham control and three irradiated groups (3 Gy, gamma ray). The irradiated mice were treated for 12 weeks with vehicle, amifostine (intraperitoneal injection), or ZA (subcutaneous injection). Grip strength, uterus weight, and serum alkaline phosphatase (ALP), and tartrate-resistant acid phosphatase (TRAP) levels were measured. Tibiae were analyzed using micro-computed tomography. Results and Discussion: Treatment of ZA ($100{\mu}g{\cdot}kg^{-1}{\cdot}week^{-1}$) significantly preserved trabecular bone volume, trabecular thickness, trabecular number, trabecular separation, bone mineral density of proximal tibia metaphysic, and cortical bone volume, but did not alter the uterus weight of the mice. The administration of ZA for 12 weeks lowered serum ALP and TRAP levels in irradiated mice, suggesting that ZA can reduce the bone turnover rate in mice. No differences were apparent between the amifostine-treated group and the irradiation control group. Conclusion: The results indicate that ZA can prevent radiation-induced bone loss in mice.

• Journal of Nutrition and Health
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• 제48권5호
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• pp.381-389
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• 2015

본 연구는 성장기 동물모델의 고과당 식이섭취가 골성장 (bone growth) 및 성숙 (bone maturation)에 미치는 영향을 연구하기 위해 수행되었다. 이를 평가하기 위해 생화학적 표지자 (biochemical markers), 경골의 구조학적 파라미터 (structural parameters) 및 골밀도 (BMD), 신장의 조직학적 변화를 측정하였고, 결과를 요약하면 다음과 같다. 1) 30% 고과당 섭취 (8주 동안) 및 30% 고과당 + 45 kcal% 고지방 섭취는 경골 내 해면골 (Tibia trabecular bone)의 부피비 (BV/TV), 해면골의 평균 개수 (Tb.N) 및 패턴요소 (Tb.Pf)를 향상시켰다. 2) 45 kcal% 고지방 섭취는 경골 내 피질골 (Tibia trabecular bone)의 부피를 향상시켰다. 3) 30% 고과당 섭취는 신장의 출혈 (interstitial bleeding), 공포화 변성 (vacuolation), 사구체 울혈 (glomerular congestion) 등의 병변을 유발하지 않았다. 4) 30% 고과당 섭취는 혈중 OC 농도를 낮추었고, 요 중 DPD농도에는 영향을 주지 않았다. 5) 8주 동안의 30% 고과당 섭취는 유의한 경향의 체중증가를 유도하였고, 45 kcal% 고지방 섭취는 유의적인 체중증가를 나타내었다. 본 연구 결과에 따르면 고과당의 섭취는 신기능의 손상 없이 성장기 해면골을 더욱 치밀하게 만드는 것으로 나타났다. 많은 선행연구들을 통하여 설탕이나 포도당의 과잉 섭취가 골 소실을 유발한다고 보고되어 왔으며, 본 연구를 포함한 이전 연구들을 종합해보면 고과당 섭취는 설탕이나 포도당 과잉 섭취가 유발하는 골 소실을 유발하지는 않는 것으로 보인다. 하지만 이러한 결과가 고과당 섭취가 골형성을 돕는다는 것을 의미하지는 않는다. 따라서 본 연구의 결과는 골의 형성 및 성숙에 중요한 시기인 청소년기에 안전한 과당섭취 가이드라인을 위한 초석을 다지는데 참고자료로서 사용될 수 있으며, 설탕이나 포도당 등을 과당으로 대체하여 섭취하는 것이 골 건강에 도움이 될 수 있을지는 향후 추가적인 연구가 필요할 것으로 보인다.