Evaluation of a multiple system atrophy model in rats using multitracer microPET.

Yoon, Hyung Ho,Lee, Chong Sik,Hong, Seok Ho,Min, Joongkee,Kim, Yong Hwan,Hwang, Onyou,Jeon, Sang Ryong Springer-Verlag 2012 Acta neurochirurgica Vol.154 No.5

<P>A double toxin-double lesion strategy is appropriate for mimicking of striatonigral degeneration. Because knowledge of human pathology is limited, animal models must be well characterized prior to testing of therapeutic approaches to treat multiple system atrophy. In double-toxin animal models, however, reduced contralateral rotation after apomorphine injection is restored within a few weeks via an unknown mechanism; the animals thus revert to PD status. We assessed this phenomenon using multitracer microPET and tissue staining.</P>

Optimal Ratio of Wnt3a Expression in Human Mesenchymal Stem Cells Promotes Axonal Regeneration in Spinal Cord Injured Rat Model

Yoon, Hyung Ho,Lee, Hyang Ju,Min, Joongkee,Kim, Jeong Hoon,Park, Jin Hoon,Kim, Ji Hyun,Kim, Seong Who,Lee, Heuiran,Jeon, Sang Ryong The Korean Neurosurgical Society 2021 Journal of Korean neurosurgical society Vol.64 No.5

Objective : Through our previous clinical trials, the demonstrated therapeutic effects of MSC in chronic spinal cord injury (SCI) were found to be not sufficient. Therefore, the need to develop stem cell agent with enhanced efficacy is increased. We transplanted enhanced Wnt3-asecreting human mesenchymal stem cells (hMSC) into injured spines at 6 weeks after SCI to improve axonal regeneration in a rat model of chronic SCI. We hypothesized that enhanced Wnt3a protein expression could augment neuro-regeneration after SCI. Methods : Thirty-six Sprague-Dawley rats were injured using an Infinite Horizon (IH) impactor at the T9-10 vertebrae and separated into five groups : 1) phosphate-buffered saline injection (injury only group, n=7); 2) hMSC transplantation (MSC, n=7); 3) hMSC transfected with pLenti vector (without Wnt3a gene) transplantation (pLenti-MSC, n=7); 4) hMSC transfected with Wnt3a gene transplantation (Wnt3a-MSC, n=7); and 5) hMSC transfected with enhanced Wnt3a gene (1.7 fold Wnt3a mRNA expression) transplantation (1.7 Wnt3a-MSC, n=8). Six weeks after SCI, each 5×10⁵ cells/15 µL at 2 points were injected using stereotactic and microsyringe pump. To evaluate functional recovery from SCI, rats underwent Basso-Beattie-Bresnahan (BBB) locomotor test on the first, second, and third days post-injury and then weekly for 14 weeks. Axonal regeneration was assessed using growth-associated protein 43 (GAP43), microtubule-associated protein 2 (MAP2), and neurofilament (NF) immunostaining. Results : Fourteen weeks after injury (8 weeks after transplantation), BBB score of the 1.7 Wnt3a-MSC group (15.0±0.28) was significantly higher than that of the injury only (10.0±0.48), MSC (12.57±0.48), pLenti-MSC (12.42±0.48), and Wnt3a-MSC (13.71±0.61) groups (p<0.05). Immunostaining revealed increased expression of axonal regeneration markers GAP43, MAP2, and NF in the Wnt3a-MSC and 1.7 Wnt3a-MSC groups. Conclusion : Our results showed that enhanced gene expression of Wnt3a in hMSC can potentiate axonal regeneration and improve functional recovery in a rat model of chronic SCI.

Recording nerve signals in canine sciatic nerves with a flexible penetrating microelectrode array

Byun, Donghak,Cho, Sung-Joon,Lee, Byeong Han,Min, Joongkee,Lee, Jong-Hyun,Kim, Sohee IOP 2017 Journal of neural engineering Vol.14 No.4

<P> <I>Objective</I>. Previously, we presented the fabrication and characterization of a flexible penetrating microelectrode array (FPMA) as a neural interface device. In the present study, we aim to prove the feasibility of the developed FPMA as a chronic intrafascicular recording tool for peripheral applications. <I>Approach</I>. For recording from the peripheral nerves of medium-sized animals, the FPMA was integrated with an interconnection cable and other parts that were designed to fit canine sciatic nerves. The uniformity of tip exposure and <I>in vitro</I> electrochemical properties of the electrodes were characterized. The capability of the device to acquire <I>in vivo</I> electrophysiological signals was evaluated by implanting the FPMA assembly in canine sciatic nerves acutely as well as chronically for 4 weeks. We also examined the histology of implanted tissues to evaluate the damage caused by the device. <I>Main results</I>. Throughout recording sessions, we observed successful multi-channel recordings (up to 73% of viable electrode channels) of evoked afferent and spontaneous nerve unit spikes with high signal quality (SNR  >  4.9). Also, minor influences of the device implantation on the morphology of nerve tissues were found. <I>Significance</I>. The presented results demonstrate the viability of the developed FPMA device in the peripheral nerves of medium-sized animals, thereby bringing us a step closer to human applications. Furthermore, the obtained data provide a driving force toward a further study for device improvements to be used as a bidirectional neural interface in humans.</P>

Biodegradable Screws Containing Bone Morphogenetic Protein-2 in an Osteoporotic Rat Model

Jin, Eun-Sun,Kim, Ji Yeon,Lee, Bora,Min, JoongKee,Jeon, Sang Ryong,Choi, Kyoung Hyo,Jeong, Je Hoon The Korean Neurosurgical Society 2018 Journal of Korean neurosurgical society Vol.61 No.5

Objective : The aim of this study was to evaluate the effect for biodegradable screws containing bone morphogenetic protein-2 (BMP-2) in an osteoporotic rat model. Methods : Twenty-four female Wistar rat (250-300 g, 12 weeks of age) were randomized into four groups. Three groups underwent bilateral ovariectomy (OVX). Biodegradable screws with or without BMP-2 were inserted in the proximal tibia in two implantation groups. The extracted proximal metaphysis of the tibiae were scanned by exo-vivo micro-computed tomography. Evaluated parameters included bone mineral density (BMD), trabecular bone volume (BV/TV), trabecular number, trabecular thickness, and trabecular separation (Tb.Sp). The tibia samples were pathologically evaluated by staining with by Hematoxylin and Eosin, and trichrome. Results : Trabecular formation near screw insertion site was evident only in rats receiving BMP-2 screws. BMD and BV/TV significantly differed between controls and the OVX and OVX with screw groups. However, there were no significant differences between control and OVX with screw BMP groups. Tb.Sp significantly differed between control and OVX and OVX with screw groups (p<0.05), and between the OVX and OVX with screw BMP group (p<0.05), with no statistically significant difference between control and OVX with screw BMP groups. Over the 12 weeks after surgery, bone lamellae in direct contact with the screw developed more extensive and thicker trabecular bone around the implant in the OVX with screw BMP group compared to the OVX with screw group. Conclusion : Biodegradable screws containing BMP-2 improve nearby bone conditions and enhance ostoeintegration between the implant and the osteoporotic bone.

Copper thin films on PET prepared at ambient temperature by ECR-CVD

Ko, Hyungduk,Jhin, J.,Byun, Dongjin,Lee, Joongkee,Park, D. Institute of Electrical and Electronics Engineers, 2005 IEEE transactions on components and packaging tech Vol.28 No.4

Metallized polymers were prepared at ambient temperature by an electron-cyclotron-resonance (ECR) chemical vapor deposition system equipped with (-) DC bias from the Cu (hfac)<SUB>2</SUB>-Ar-H<SUB>2</SUB> system. X-ray difraction (XRD) results showed that the Cu (111) peaks were clearly observed when H<SUB>2</SUB> was introduced to the plasma. The surface morphology showed that larger Cu grains were formed in the metal-organic composite films with the introduction of H<SUB>2</SUB> to the plasma. AES depth profiles showed that H<SUB>2</SUB> gas introduction to the plasma led to the formation of copper-rich films with a homogeneous composition. Also, the sheet resistance was strongly dependent on the H<SUB>2</SUB> content of the plasma. This means that hydrogen may lead to both the formation of stable volatile organic compounds and the reduction of copper, which influences both the crystallographic structure and the composition of films. As a result, crystalline copper films with a sheet resistance of 2-3Ω<SUP>2</SUP> can be prepared on poly ethylene terephthalate with the addition of H<SUB>2</SUB> to the plasma.

연속 ECR-CVD 조업하에 RF-magnetron-sputter의 싸이클조업을 통해 PET위에 올려진 구리박막의 특성

명종윤,전법주,변동진,이중기,Myung JongYun,Jeon Bupju,Byun Dongjin,Lee Joongkee 한국재료학회 2005 한국재료학회지 Vol.15 No.7

Preparation of copper film on PET substrate was carried out by cyclic operation of RF-magnetron­sputtering under continuous operation of ECR-CVD. The purpose of this study is aimed to an increase in deposition rate with keeping excellent adhesion between copper film and PET. In order to optimize the sputtering time under continuous ECR-CVD, cyclic operation concept is employed. By changing parameters of cyclic operation such as split of e and cycle time of A, the characteristics and thickness of the deposited copper film are controlled. As $\theta$ value increase, film thickness could confirm to increase and its surface resistivity value decreases. The highest adhesive strength appears at $\theta=0.33$ and cycle time of 30 min. The uniformity of copper film shows $5\%$ in our experimental range.

PET 기질의 전처리효과가 상온 ECR 화학증착법에 의해 증착된 구리박막의 계면접착력에 미치는 영향

현진,전법주,변동진,이중기,Hyun Jin,Jeon Bupju,Byun Dongjin,Lee Joongkee 한국재료학회 2004 한국재료학회지 Vol.14 No.3

Effects of various pretreatments on the adhesion of copper-coated polymer films were investigated. Copper-coated polymer films were prepared by an electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD) coupled with a DC bias system at room temperature. PET(polyethylene terephthalate) film was employed as a substrate material and it was pretreated by industrially feasible methods such as chromic acid, sand-blasting, oxygen plasma and ion-implantation treatment. Surface characterization of the copper-coated polymer film was carried out by AFM(Atomic Force Microscopy) and FESEM(Field Emission Scanning Electron Microscopy). Surface energy was calculated by based on the value of the contact angle measured. The adhesion of copper/PET films was determined by a pull-off test according to ASTM D-5179. It was found that suitable pretreatment of the PET substrate was required for obtaining good adhesion property between copper films and the substrate. In this study the highest adhesion was observed in sand-blasting, and then followed by those of acid and oxygen plasma treatment. However, the effect of surface energy was insignificant in our experimental range. This is probably due to compensating the difference in surface energy from various pretreatments by exposing substrate to ECR plasma for 5 min or longer at the early stage of the copper deposition. Therefore, it can be concluded that surface roughness of the polymer substrate plays an important role to determine the adhesion of copper-coated polymer for the deposition of copper by ECR-MOCVD.

The Effect of Biocomposite Screws on Bone Regeneration in a Rat Osteoporosis Model

Jeong, Je Hoon,Jin, Eun-Sun,Kim, Ji Yeon,Lee, Bora,Min, JoongKee,Jeon, Sang Ryong,Lee, Minsu,Choi, Kyoung Hyo Elsevier 2017 World neurosurgery Vol.106 No.-

<P><B>Objective</B></P> <P>To evaluate the efficacy of biocomposite screws used in ovariectomy (OVX)-induced osteoporotic rats.</P> <P><B>Methods</B></P> <P>Twenty-four female Wistar rats (250–300 g, 12 weeks old) were divided into 4 groups: sham group (control), OVX-induced osteoporosis group (OVX), OVX and biodegradable poly(lactic-<I>co</I>-glycolic acid) (PLGA) without tricalcium phosphate (β-TCP) screw insertion group (OVX/BSR), and OVX and biocomposite (PLGA with β-TCP) screw insertion group (OVX/CSR). Three groups underwent bilateral OVX, and of these, 2 groups had 2 different types of screw inserted at the proximal tibia. At 25 weeks after OVX, the bilateral tibias were extracted. The extracted tibiae were scanned by ex vivo micro-computed tomography (CT) and stained with hematoxylin and eosin (H&E) and with Masson's trichrome stain for pathological assessment.</P> <P><B>Results</B></P> <P>Compared with the ovariectomized groups, the control group had the highest values for bone mineral density (BMD), bone volume (BV)/total volume (TV), and trabecular number (Tb.N) and the lowest values for trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp). In the pairwise comparison among ovariectomized groups, the OVX/CSR group had significantly higher BMD, BV/TV, and Tb.N values than the other 2 groups (OVX and OVX/BSR) and significantly lower Tb.Sp. Micro-CT scans showed clear evidence of new trabecular formation near the screw insertion site in the OVX/CSR group only. Analyses of H&E- and Masson's trichrome–stained sections showed more and thicker trabecular bone around the implant in the OVX/CSR group compared with the OVX and OVX/BSR groups.</P> <P><B>Conclusions</B></P> <P>Biocomposite screws can improve local bone quality and facilitate osteoconductivity in an osteoporotic rat model.</P>