• Journal of Korean Neurosurgical Society
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• v.54 no.6
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• pp.467-476
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• 2013

Objective : This study aimed to evaluate the hypotheses that administration routes [intra-arterial (IA) vs. intravenous (IV)] affect the early stage migration of transplanted human bone marrow-derived mesenchymal stem cells (hBM-MSCs) in acute brain infarction. Methods : Male Sprague-Dawley rats (n=40) were subjected to photothrombotic infarction. Three days after photothrombotic infarction, rats were randomly allocated to one of four experimental groups [IA group : n=12, IV group : n=12, superparamagnetic iron oxide (SPIO) group : n=8, control group : n=8]. All groups were subdivided into 1, 6, 24, and 48 hours groups according to time point of sacrifice. Magnetic resonance imaging (MRI) consisting of T2 weighted image (T2WI), $T2^*$ weighted image ($T2^*WI$), susceptibility weighted image (SWI), and diffusion weighted image of rat brain were obtained prior to and at 1, 6, 24, and 48 hours post-implantation. After final MRI, rats were sacrificed and grafted cells were analyzed in brain and lung specimen using Prussian blue and immunohistochemical staining. Results : Grafted cells appeared as dark signal intensity regions at the peri-lesional zone. In IA group, dark signals in peri-lesional zone were more prominent compared with IV group. SWI showed largest dark signal followed by $T2^*WI$ and T2WI in both IA and IV groups. On Prussian blue staining, IA administration showed substantially increased migration and a large number of transplanted hBM-MSCs in the target brain than IV administration. The Prussian blue-positive cells were not detected in SPIO and control groups. Conclusion : In a rat photothrombotic model of ischemic stroke, selective IA administration of human mesenchymal stem cells is more effective than IV administration. MRI and histological analyses revealed the time course of cell migration, and the numbers and distribution of hBM-MSCs delivered into the brain.

• Journal of Korean Neurosurgical Society
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• v.40 no.5
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• pp.336-341
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• 2006

Objective : The authors conducted a retrospective study to evaluate the preservation rates of serviceable hearing and to determine its prognostic factors after gamma knife stereotactic radiosurgery[GK SRS] in the patient with vestibular schwannomas. Methods : Between December 1997 and March 2005, 54 patients with a sporadic vestibular schwannoma and serviceable hearing [Gardner Robertson grade I-II] were enrolled in this study. Electronic database of medical records and radiological examinations before and after GK SRS were investigated to the last follow up. The mean marginal dose was $12.3{\pm}0.7Gy$. The mean maximum dose delivered to the tumor center was 24.7Gy [$22{\sim}30Gy$]. The median tumor volume was 2cc [$0.1{\sim}9.1cc$]. The median follow-up period of magnetic resonance[MR] imaging was 31 months [$6{\sim}99\;months$], and the mean follow-up period of audiometry was 24 months [$4{\sim}70\;months$]. Results : The tumor control rate was 100% in the patients with the follow up period more than 2 years. The trigeminal and facial nerve preservation rates were 98% and 100%, respectively. Twenty-eight [52%] of the 54 patients preserved serviceable hearing and 16 [30%] patients retained their pre-GK G-R grade level after GK SRS. In the univariate and multivariate analysis, there was no significant prognostic factor in preservation of the serviceable hearing. Conclusion : The hearing preservation rate is still unsatisfactory compared with the results of other cranial nerve preservation and tumor control in the treatment of vestibular schwannoma by GK SRS. More sophisticated strategy during and after GK SRS is necessary to improve long-term hearing preservation.

• Biomolecules & Therapeutics
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• v.19 no.2
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• pp.261-266
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• 2011

As recent reports suggest that nanoparticles may penetrate into cell membrane and effect DNA condition, it is necessary to assay possible cytotoxic and genotoxic risk. Three different sizes of magnetic nanoparticle silica (MNP@$SiO_2$) (50, 100 and 200 nm diameter) were tested for cytotoxicity and DNA damage using L5178Y cell. MNP@$SiO_2$ had constant physicochemical characteristics confirmed by transmission electron microscope, electron spin resonance spectrometer and inductively coupled plasma-atomic emission spectrometer for 48 h. Treatment of MNP@$SiO_2$ induced dose and time dependent cytotoxicity. At 6 h, 50, 100 or 200 nm MNP@$SiO_2$ decreased significantly cell viability over the concentration of 125 ${\mu}g/ml$ compared to vehicle control (p<0.05 or p<0.01). Moreover, at 24 h, 50 or 100 nm MNP@$SiO_2$ decreased significantly cell viability over the concentration of 125 ${\mu}g/ml$(p<0.01). And treatment of 200 nm MNP@$SiO_2$ decreased significantly cell viability at the concentration of 62.5 ${\mu}g/ml$ (p<0.05) and of 125, 250, 500 ${\mu}g/ml$ (p<0.01, respectively). Furthermore, at 48 h, 50, 100 or 200 nm MNP@$SiO_2$ decreased significantly cell viability at the concentration of 62.5 ${\mu}g/ml$ (p<0.05) and of 125, 250, 500 ${\mu}g/ml$ (p<0.01, respectively). Cellular location detected by confocal microscope represented they were existed in cytoplasm, mainly around cell membrane at 2 h after treatment of MNP@$SiO_2$. Treatment of 50 nm MNP@$SiO_2$ significantly increased DNA damage at middle and high dose (p<0.01), and treatment of 100 nm or 200 nm significantly increased DNA damage in all dose compared to control (p<0.01). Taken together, treatment of MNP@$SiO_2$ induced cytotoxicity and enhanced DNA damage in L5178Y cell.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.1
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• pp.58-65
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• 2012

In this study, to reduce the motion of the vessels resulting from resonance and secondary undulation by long-period waves, numerical review on the control performance of resonator was carried out by attaching the resonator to the established harbor of real waters. In the numerical analysis, CGWAVE MODULE of commercial software SMS(Surface water Modeling System), a finite element model based on 2-dimensional elliptical mild slope equation was applied, and through comparative analysis of the existing experiments and analysis results on the rectangular model ports, the validity of the friction coefficients in which validity and effectiveness of SMS on the secondary undulation analysis is applied was verified. Based on this, the control performance of resonator was confirmed through comparative review of the secondary undulation according to whether or not to attach the resonator to rectangular harbor. In addition, to reduce long-period motion of the moored vessels and the secondary undulation which may occur in Pohang new port, the method to move the resonant period which causes abnormal motion of the vessels to long-term one was discussed through application of the resonators with various sizes, thereby identifying the availability.

• Clinics in Shoulder and Elbow
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• v.19 no.3
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• pp.125-129
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• 2016

Background: Superior migration of humeral head has been conventionally determined by measuring the acromiohumeral distance (AHD), We sought to devise a novel measurement system more reliably and accurately than AHD. We described a structural landmark called 'C-line'. In this study, we investigated the clinical usefulness of 'step-off of the C-line (SOC)' compared to that of AHD. Methods: The C-line formed from the medial margin of the proximal humeral head continuing up to the inferior margin of the articular glenoid and then to the lateral border of the scapula. The superior migration of the humeral head triggered by a rotator cuff tear introduces a discontinuity in this C-line. We measured the distance of this discontinuity. We enrolled 144 patients who underwent a rotator cuff repair. We selected 58 controls who didn't have any cuff lesions apparent on magnetic resonance imaging. Using radiographs derived from standardized true anteroposterior views of the shoulder, we measured the SOC and the AHD. We used t-tests for statistical analyses. Results: A rotator cuff tear was associated with an increase in SOC and a decrease in AHD. In control group, the mean SOC was $1.29{\pm}1.71mm$ and AHD was $9.71{\pm}2.65mm$. In cuff tear group, the mean SOC was $3.15{\pm}3.41mm$ and AHD was $8.28{\pm}1.76mm$. The mean SOCs of the patient group in relation to the mean SOC of the control group according to tear size, the SOCs of medium tear and lager groups showed statistically significant increase (p<0.05). Conclusions: The SOC may be a similarly effective to diagnose cuff tears of medium size and larger compared with AHD.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.1
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• pp.41-52
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• 2009

The surface treatment of titanium implant could bring out the biochemical bonding between bone and implant. The purpose of this study was to evaluate the biomechanical bone response of Mg-ion implanted implants with plasma source ion implantation method. Twelve New Zealand white rabbits were included in this study. Each rabbit received one control fixture (blasted with resorbable blasting media, RBM) and three types of Mg ion implanted fixtures in tibiae. The implants were left in place for 6 weeks before the rabbits were sacrificed. Removal torque value and resonance frequency analysis (ISQ) were compared. The repeated measured analysis of variance was used with $P{\leq}0.05$ as level of statistical significance. ISQ was not different among all groups. However, the ISQ was increased after 6 weeks healing. The group had lowest ISQ value showed the greatest increment. Mg-1 implants with 9.4% retained ion dose showed significantly higher removal torque value than that of the other implants. From this results, it is concluded that the Mg-1 implants has stronger bone response than control RBM surface implant.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.23 no.2
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• pp.57-62
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• 2012

Objectives : Characteristic symptoms, including hyperactivity and easy distractibility, in children with attention-deficit hyperactivity disorder (ADHD) suggest that their brain status, even at rest, might differ from that of healthy children. This study was conducted in order to determine whether resting state brain activity is compromised in medication-naive children with ADHD. Methods : Twenty medication-naive children with ADHD (mean age $10.3{\pm}2.5$) and 28 age- and gender-matched healthy volunteers (mean age $10.3{\pm}2.0$) underwent measurements for resting state brain activity using functional magnetic resonance imaging (fMRI). Among resting state related-independent components (RSICs) extracted from fMRI data using independent component analysis, a significant difference in RSICs was observed between groups, using a mixed Gaussian/gamma model. Results : Except for IQ, which was higher in the healthy control group, no demographic difference was observed between the two groups (p<.001). Significantly less activation of one RSIC, which includes the bilateral precuneus/posterior cingulate cortex, occipito-temporal junction, and anterior cingulate cortex, was observed in the ADHD group, compared with the control group (p<.05). Conclusion : An abnormal RSIC, posterior default mode network (DMN), was observed in the medication-naive ADHD group. Results of our study suggest that abnormality of posterior DMN is one of the main pathophysiologies of ADHD.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.32 no.4
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• pp.137-143
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• 2021

Objectives: Despite the growing concern regarding the adverse effects related to problematic smartphone use (PSU), little is known about underlying morphologic changes in the brain. The brainstem is a deep brain structure that consists of several important nuclei associated with emotions, sensations, and motor functions. In this study, we sought to examine the difference in the volume of brainstem substructures among adolescents with and without PSU. Methods: A total of 87 Korean adolescents participated in this study. The PSU group (n=20, age=16.2±1.1, female:male=12:8) was designated if participants reported a total Smartphone Addiction Proneness Scale (SAPS) score of ≥42, whereas the remaining participants were assigned to the control group (n=67, age=15.3±1.7, female:male=19:48). High-resolution T1 magnetic resonance imaging was performed, and the volume of each of the four brainstem substructures [midbrain, pons, medulla, and superior cerebellar peduncle (SCP)] was measured. Analysis of covariance was conducted to reveal group differences after adjusting for effects of age, gender, whole brainstem volume, depressive symptoms, and impulsivity. Results: The PSU group showed a significantly smaller volume of the SCP than the control group (F=8.273, p=0.005). The volume of the SCP and the SAPS score were negatively correlated (Pearson's r=-0.218, p=0.047). Conclusion: The present study is the first to reveal an altered volume of the brainstem substructure among adolescents with PSU. This finding suggests that the altered white matter structure in the brainstem could be one of the neurobiological mechanisms underlying behavioral changes in PSU.

• Journal of the Korean Arthroscopy Society
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• v.15 no.2
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• pp.83-91
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• 2011

Purpose: Microfracture has been used as a first-line treatment to repair articular cartilage defects. In this study, a new technique using an extracelluar matrix biomembrane to cover the cartilage lesions after microfracture was evaluated in terms of cartilage repairability and clinical outcome compared with conventional microfracture technique in a prospective randomized trial. Materials and Methods: A total of 53 patients (59 cases) without osteoarthritis who had focal full thickness articular cartilage lesions were randomly assigned in two group. Seventeen patients (17 cases) underwent conventional microfracture procedure (control group) and thirty-six patients (42 cases) received microfracture and placing biomembrane cover (ArtiFilm$^{TM}$) concomitantly (experimental group). Clinical assessment was done through 6 months postoperatively using the subjective International Knee Documentation Committee IKDC questionnaire, and visual analog scale (VAS) for pain and satisfaction. Magnetic resonance imaging (MRI) was performed at 6 months after the operation in all patients. Results: In clinical outcomes, the significant difference was observed between both groups in IKDC, but not in VAS for pain and for satisfaction (final outcomes of IKDC, p=0.001; VAS for pain, p=0.074; VAS for satisfaction, p=0.194). The MRI showed good to complete defect fill (67 to 100%) in 33 patients (78.6%) of experimental group and 4 patients (23.5%) of control group, respectively. In control group, 9 of 17 patients (52.9%) showed poor defect fill (less than 33%), whereas 5 (11.9%) in experimental group (p=0.001). Assessment of peripheral integration revealed no gap formation in 35 patients (83.3%) in experimental group and 6 patients (35.3%) in control group (p=0.001). No serious complications or adverse effects related to the biomembrane were found. Conclusion: Good short-term follow-up clinical results were obtained in the group whose cartilage defects in the knee joint were covered with biomembrane after the microfracture, with the MRI findings confirming the excellent regeneration of the defective cartilage area. This suggests that the surgery to cover the defective area with biomembrane (ArtiFilm$^{TM}$) after the microfracture procedure is a safe, more effective treatment to induce cartilage regeneration.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.2
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• pp.180-186
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• 2008

Purpose: This study was performed to evaluate the effect of the implant recipient site preparation methods on primary stability of implants with the instruments of $Osstell^{TM}$ and $Periotest^{(R)}$ in the iliac bone of cadaver. Methods and materials: The 8 iliac bones in 4 cadavers and implants treated with resorbable blasting media (RBM) were used. $Periotest^{(R)}$ (Simens AG, Germany) and $Osstell^{TM}$ (Model 6 Resonance Frequency Analyser: Integration Diagnostics Ltd., Sweden) were used to measure primary stability of implants. Implants were inserted into the iliac crest of the cadaver. In control group, the recipient site was prepared according to the manufacturer's recommendation: 1.8 mm guide drill, 2.0 mm initial drill, 2.7 mm pilot drill, 2.7 mm twist drill, 3.0 mm twist drill, 3.3 mm pilot drill, 3.3 mm twist drill, and 3.3 mm countersink drill as well as tapping drill were used in order. In the group 1, implant recipient sites were prepared by sequentially drilling from 1.8 mm guide drill to 3.0 mm twist drill and then inserted implants without countersinking and tapping. In the group 2, implant recipient sites were prepared to 3.0 mm twist drill and countersink drill and then inserted implants without tapping. In the group 3, the sites were prepared to 3.0 mm twist drill and countersink drill as well as tapping drill. In the group 4, the sites were prepared to 3.3 mm twist drill. In the group 5, the sites were prepared to 3.3 mm twist drill and countersink drill. A total of 60 implants were placed (n=10). The stability was measured using $Osstell^{TM}$ and $Periotest^{(R)}$ mesiodistally and buccolingually. To compare the mean stability of each group statistically, One-way ANOVA was used and correlation of instrument were analyzed using SPSS 12.0. The results obtained were as follows; 1. The stability of group 1 measured using $Osstell^{TM}$ and $Periotest^{(R)}$ buccolingually showed the highest, and there are significant difference statistically between control group and experimental group 1,2,4 in each instruments respectively (p<0.05). 2. The stability of group 1 measured using $Osstell^{TM}$ and $Periotest^{(R)}$ mesiodistally showed the highest. There are significant difference statistically between control group and all experimental groups in $Osstell^{TM}$, and between control group and experimental group 1,2,3,4 (p<0.05). 3. There are high correlation between the measurements of $Osstell^{TM}$ and $Periotest^{(R)}$ (p<0.05). Conclusion: These results indicate that the primary stability of implant can be obtained by the recipient sites preparation with smaller diameter drill than that of implant or minimal drilling.