Enhanced wound healing by an epigallocatechin gallate‐incorporated collagen sponge in diabetic mice

Kim, HakHee,Kawazoe, Takeshi,Han, Dong‐,Wook,Matsumara, Kazuaki,Suzuki, Shigehiko,Tsutsumi, Sadami,Hyon, Suong‐,Hyu Blackwell Publishing Inc 2008 Wound repair and regeneration Vol.16 No.5

<P><B>ABSTRACT</B></P><P>Epigallocatechin‐3‐<I>O</I>‐gallate (EGCG), the major polyphenolic compound present in green tea, has potent anti‐oxidant and free radical‐scavenging activities. In this study, various concentrations (10, 100, and 1,000 ppm) of EGCG were incorporated into a collagen sponge (CS) in order to investigate its healing effects on full‐thickness wounds created in type 2 diabetic mice. After 14 days, the residual wound size of the mice treated with 10 ppm EGCG‐incorporated collagen sponge (E‐CS) decreased significantly faster than that of the other mice. Moreover, significant increases in the degree of reepithelialization, the thickness of the granulation tissue, and the density of the capillaries were also histologically observed in the wound sites exposed to 10 ppm E‐CS in comparison with the others. Furthermore, 10 ppm E‐CS resulted in significant increases in the immunoreactivity of Ki‐67 (reepithelialization at the wound site), CD31 (formation of blood vessels), and α‐smooth muscle actin (the induction of myofibroblasts across the dermis). These results suggest that a CS incorporated with EGCG at low concentrations can enhance wound healing in diabetic mice by accelerating reepithelialization and angiogenesis as well as improving the cellular reorganization of granulation tissue by triggering the activity of myofibroblasts.</P>

Experimental Investigation of Pulsatility Effect on the Deformability and Hemolysis of Blood Cells

Kang, Yang Jun,Kim, Myoung Gon,Son, Kuk Hui,Lim, Choon Hak,Son, Ho Sung,Yoon, Sang Youl,Kwon, Hyuk Sang,Yang, Sung Blackwell Publishing Inc 2010 Artificial Organs Vol.34 No.4

<P>Abstract</P><P>In this study, we investigated the differences between pulsatile cardiopulmonary bypass (CPB) procedure and nonpulsatile CPB procedure in terms of their effects on hemolysis and deformability of red blood cells (RBCs) under various shear stress conditions. In order to research the effects on hemolysis and deformability, four parameters—free hemoglobin (fHb) concentration, normalized index of hemolysis (NIH), deformability index (DI) of RBCs, and elongation index of RBCs—have been deeply investigated. For these investigations, two randomly assigned adult mongrel dog groups—nonpulsatile group (NP, <I>n</I> = 6) and pulsatile group (P, <I>n</I> = 6)—were examined. According to our results, both types of perfusion did not show any statistical differences in terms of the concentrations of fHb as well as NIH. In addition, there were no significant differences in RBC deformability between perfusion types within an operation time of 3 h. Therefore, our studies suggest that pulsatile perfusion has no significant difference from nonpulsatile perfusion in terms of hemolysis and deformability of RBCs.</P>

DESIGN OF AN ITERATIVE MULTI-ITEM DOUBLE-AUCTION MECHANISM

Roh, Dong H.,Yang, Hyun S. Blackwell Publishing Inc 2008 Computational intelligence Vol.24 No.1

<P>There have been many multi-item auction mechanisms. As it is not allowed for both sellers and buyers to submit bids and offers in nearly all existing multi-item auction mechanisms, the impartial profit distribution for both sellers and buyers cannot be realized in those mechanisms. Although it is possible for both sellers and buyers to submit bids and offers in a combinatorial exchange, the impartial profit distribution for all individual participants cannot be realized due to its pricing mechanism that focuses only on enforcing budget balance. This paper proposes an iterative multi-item unit-demand and unit-supply double-auction mechanism with a new winner determination and pricing mechanism for distributing profit impartially from the viewpoints of individual participants regardless of whether they are buyers or sellers. It also analyzes the theoretical features of the proposed auction mechanism, including those related to its strategic behavior and efficiency.</P>

Neuroprotective effects of the ketogenic diet

Noh, Hae Sook,Kim, Yoon Sook,Choi, Wan Sung Blackwell Publishing Inc 2008 Epilepsia Vol.49 No.suppl8

<P><SMALL>SUMMARY</SMALL></P><P><B>The ketogenic diet (KD) is an alternative treatment for medically refractory epilepsy. Despite numerous mechanistic hypotheses advanced to explain the anticonvulsant action of the KD, few studies to date have addressed the molecular changes in brain following KD treatment. Here, we present recent experimental results based on systemic administration of kainic acid (KA) in rodents. KA typically induces acute limbic seizures and results in cellular and molecular alterations, accompanied by neuronal death mainly in limbic structures, similar to what has been observed in surgically resected temporal lobe tissue in epileptic patients. We have reported that neuronal degeneration induced by KA is ameliorated by KD treatment via diverse protective mechanisms, including inhibition of caspase-3-mediated apoptosis in hippocampal neurons. Neuroprotective strategies such as the KD, if implemented early, might exert an antiepileptogenic effect, and could prevent associated learning and memory deficits.</B></P>

Ictal Hyperperfusion Patterns in Relation to Ictal Scalp EEG Patterns in Patients with Unilateral Hippocampal Sclerosis: A SPECT Study

Kim, Ji Hyun,Im, Ki Chun,Kim, Jae Seung,Lee, Sang-Ahm,Lee, Jung Kyo,Khang, Shin Kwang,Kang, Joong Koo Blackwell Publishing Inc 2007 Epilepsia Vol.48 No.2

<P>Summary</P><P><I>Purpose:</I> The aims of the present study were to explore the relation between ictal scalp EEG patterns and ictal hyperperfusion patterns in patients with unilateral hippocampal sclerosis–associated mesial temporal lobe epilepsy (HS-MTLE) by using semiquantitative single-photon emission computed tomography (SPECT) analysis and to assess clinical significance of ictal hyperperfusion patterns.</P><P><I>Methods:</I> We studied retrospectively 39 consecutive patients with surgically proven HS-MTLE. All had both interictal and ictal SPECTs with the tracer injection during a complex partial seizure (CPS) typical of MTLE semiology. According to initial ictal discharge (IID) frequency on scalp EEG, two lateralizing patterns were identified: (a) a sustained regular 5- to 9-Hz rhythm with a restricted temporal or subtemporal distribution (group 1); and (b) an irregular 2- to 5-Hz rhythm with a widespread distribution (group 2). We performed group analysis by using statistical parametric mapping (SPM) of paired ictal–interictal SPECTs to identify regions of significant ictal hyperperfusion and compared clinical characteristics, tracer-injection time, semiology, pathologic HS grade, and surgical outcome between two groups.</P><P><I>Results:</I> Of the 39 patients, 19 patients (10 males, nine right HS) were designated as group 1, and the remaining 20 patients (eight males, seven right HS), group 2. Group 1 showed hyperperfusion mainly confined to the ipsilateral temporal lobe, whereas group 2 showed widespread hyperperfusion in the extratemporal structures such as ipsilateral basal ganglia, brainstem, and bilateral thalamus, in addition to the ipsilateral temporal lobe. No significant difference was found between two groups in clinical characteristics, injection time, pathologic HS grade, and surgical outcome. Among semiologic features, dystonic limb posturing was more frequently observed in group 2 (p = 0.006).</P><P><I>Conclusions:</I> Scalp EEG IID frequency in HS-MTLE can be an important determining factor of ictal hyperperfusion patterns. The lack of difference in surgical outcome between two groups implies that different hyperperfusion patterns, according to their IID frequencies, reflect only preferential pathways of ictal propagation rather than intrinsic epileptogenic region.</P>

Transplantation of Reconstructed Corneal Layer Composed of Corneal Epithelium and Fibroblasts on a Lyophilized Amniotic Membrane to Severely Alkali-burned Cornea

Jang, In-Keun,Ahn, Jae-Il,Shin, Jun-Seop,Kwon, Young-Sam,Ryu, Yang-Hwan,Lee, Jeong-Kyu,Park, Jung-Keug,Song, Kye-Yong,Yang, Eun-Kyung,Kim, Jae-Chan Blackwell Publishing Inc 2006 Artificial Organs Vol.30 No.6

<P>Abstract: </P><P>The purpose of this article was to evaluate the graft efficacy of reconstructed corneal layer, composed of autologous corneal epithelium and fibroblasts on a lyophilized amniotic membrane (LAM), in a severely alkali-burned corneal model. After biopsy specimens were obtained from the left eyes of 24 rabbits, the corneal epithelial cells and fibroblasts were expanded in vitro and the corneal layer was reconstructed on LAM. Thirty-six eyes of rabbits underwent alkali burn (1 N NaOH, 30 s) to create a limbal deficiency and a deeply damaged corneal stroma. Four weeks later, group 1 underwent a graft of the reconstructed corneal layer composed of autologous corneal epithelium and fibroblasts on LAM. Group 2 was transplanted with a graft of the reconstructed autologous corneal epithelium, and group 3 served as a control without surgery. Wound healing and stabilization of the ocular surfaces occurred much faster in group 1 than in groups 2 and 3. The eyes in group 3 revealed typical limbal deficiencies with conjuctivalization and persistent corneal epithelial defects. However, the corneas in group 1 developed only mild peripheral neovascularization. Immunohistochemical staining in group 1 demonstrated that p63, cytokeratin 3, E-cadherin, transforming growth factor (TGF)-&bgr;1, and collagen IV were expressed strongly in the corneal epithelium and basement membrane. On the basis of these results, transplantation of the reconstructed corneal layer, composed of autologous corneal epithelium and fibroblasts on LAM, partially accelerated the recovery of the alkali-injured rabbit ocular surface, and might be useful therapeutically for the treatment of patients with severely damaged cornea.</P>

Scaffold-Free, Engineered Porcine Cartilage Construct for Cartilage Defect Repair—In Vitro and In Vivo Study

Park, Kwideok,Huang, Jinsong,Azar, Frederick,Jin, Ri L.,Min, Byoung-Hyun,Han, Dong K.,Hasty, Karen Blackwell Publishing Inc 2006 Artificial Organs Vol.30 No.8

<P>Abstract: </P><P>This study introduces an implantable scaffold-free (SF) cartilage tissue construct that is composed of chondrocytes and their self-produced extracellular matrix (ECM). Chondrocytes were isolated from the articular cartilages from knees of domestic pigs (2-week old) and monolayer-cultured for 3–4 days in Dulbecco’s modified Eagle’s medium supplemented with 10% fetal calf serum and 50 µg/mL of ascorbic acid. Briefly treated with 0.25% trypsin–ethylenediaminetetraacetic acid (EDTA), an intact chondrocytes/ECM membrane, as a cell sheet was released from the plate bottom and subsequently centrifuged into a pellet-type construct. Each was grown in vitro for up to 5 weeks and subjected to various assays at different time points (1, 7, 14, 21, and 35 days). For in vivo implantation, full-thickness defects (<I>n</I> = 4) were manually created on the femoro-patellar groove of the left porcine knee and 1-week-cultured SF construct was implanted as an allograft for a month. One defect (♯1) was an empty control and the remaining three received different recipes; construct only (♯2) or 0.25% trypsin/EDTA-treated first and then construct and collagen gel (♯3) or construct and collagen gel (♯4). While the total cell numbers significantly increased by 2 weeks and then remained stable, cell viability stayed in the mid-70% range through the entire culture period. Biochemical assay found continuous glycosaminoglycan (GAG) accumulation. Histology exhibited that cell distribution was even in the construct and GAG intensity became stronger and uniform with time. Real-time reverse transcription polymerase chain reaction (RT-PCR) results showed that phenotypic stability peaked at 2 weeks, which was arable to that of freshly isolated chondrocytes. Upon analysis of the retrieved implants, some promising results were witnessed in the defects (♯3) retaining not only their intact mass but also chondrocytic morphology with lacuna formation. </P>

Multiresolution Random Accessible Mesh Compression

Kim, Junho,Choe, Sungyul,Lee, Seungyong Blackwell Publishing, Inc 2006 Computer graphics forum Vol.25 No.3

<P>Abstract</P><P><I>This paper presents a novel approach for mesh compression, which we call</I> multiresolution random accessible mesh compression<I>. In contrast to previous mesh compression techniques, the approach enables us to progressively decompress an arbitrary portion of a mesh without decoding other non-interesting parts. This simultaneous support of random accessibility and progressiveness is accomplished by adapting selective refinement of a multiresolution mesh to the mesh compression domain. We present a theoretical analysis of our connectivity coding scheme and provide several experimental results. The performance of our coder is about 11 bits for connectivity and 21 bits for geometry with 12-bit quantization, which can be considered reasonably good under the constraint that no fixed neighborhood information can be used for coding to support decompression in a random order.</I></P><P>Categories and Subject Descriptors (according to ACM CCS): I.3.5 [Computer Graphics]: Computational Geometry and Object Modeling</P>

Fabrication of Myomucosal Flap Using Tissue-engineered Bioartificial Mucosa Constructed With Oral Keratinocytes Cultured on Amniotic Membrane

Ahn, Kang-Min,Lee, Jong-Ho,Hwang, Soon-Jung,Choung, Pill-Hoon,Kim, Myung-Jin,Park, Hee-Jung,Park, Jung-Keug,Jahng, Jeongwon,Yang, Eun-Kyung Blackwell Publishing Inc 2006 Artificial Organs Vol.30 No.6

<P>Abstract: </P><P>The purpose of this study was to fabricate bioartificial mucosa using cultured oral keratinocytes (OKCs) on an amniotic membrane (AM), and to evaluate the possibility of developing a prelaminated myomucosal flap using the fabricated bioartificial mucosa and local muscle flap. Buccal mucosa was harvested from male New Zealand rabbits (<I>n</I> = 40, 2.5–3.0 kg) and primary cultivation was performed. The cultured OKCs were seeded on the AM and a submerged culture was performed. Prelamination of the bioartificial mucosa was performed on the latissimus dorsi (LD) muscle of rabbits. Survival rate, layer of OKCs, and Cinamon’s score (CS) based on macroscopic and microscopic examinations were evaluated 7, 10, 14, and 21 days after prelamination (<I>n</I> = 10 per day). The OKCs cultured on AM showed multiple layers (3.85 ± 1.32) and cells were tightly adhered with desmosomes. Basal layer cells adhered to the AM with hemidesmosomes. In addition, the AM played an excellent role as a substrate for the OKCs and simplified handling during prelamination. A myomucosal flap with OKCs cultured on AM was fabricated within 2 weeks (CS: 11.05 ± 2.63). The basement component of laminin was observed 2 weeks after prelamination and showed enough strength to adhere to the underlying fascia. A myomucosal flap was successfully developed using prelamination of bioartificial mucosa on the LD muscle between 10 and 14 days.</P>

Reconstruction of Rabbit Corneal Epithelium on Lyophilized Amniotic Membrane Using the Tilting Dynamic Culture Method

Ahn, Jae-Il,Lee, Doo-Hoon,Ryu, Yang-Hwan,Jang, In-Keun,Yoon, Mun-Young,Shin, Youn Ho,Seo, Young-Kwon,Yoon, Hee-Hoon,Kim, Jae-Chan,Song, Kye-Yong,Yang, Eun-Kyung,Kim, Ki-Ho,Park, Jung-Keug Blackwell Publishing Inc 2007 Artificial Organs Vol.31 No.9

<P>Abstract: </P><P>Rabbit corneal epithelium was reconstructed using tilting dynamic culture with a self-manufactured, amniotic membrane (AM) supporter and a lyophilized amniotic membrane (LAM). Rabbit corneal epithelial (RCE) cells were cultured and cryopreserved after isolation from the limbus. The second- and third-passage RCE cells were plated onto the epithelial side of the LAM of Ahn's AM supporter. Two days later, the air–liquid interface culture was maintained with third-passage RCE cells for 6 days and second-passage corneal epithelial cells for 9 days. The average viability of thawed RCE cells, assessed using trypan blue dye exclusion, was 77.42%. The reconstructed corneal epithelium was characterized by histological (hematoxylin and eosin) and immunohistochemical staining (proliferating cell nuclear antigen) for light microscopy, and by reverse transcriptase-polymerase chain reaction, glucose assay, and transmission electron microscopy. The basal layer of the reconstructed corneal epithelium was well formed, and the epithelium was tightly constructed due to the increase in cell proliferation and differentiation caused by the tilting dynamic culture, as opposed to static culture. Tilting dynamic culture was useful for the reconstruction of the epithelium using easily damaged epithelial cells and resulted in more stratum cell layers. Moreover, cytokeratin (CK3) mRNA expression in tilting dynamic cultured third-passage RCE cells seeded onto AM was greater than in static cultured third-passage RCE cells. The morphology of the reconstructed corneal epithelium on LAM by tilting dynamic culture for 9 days resembled that of the skin epidermis. This was thought to be because the tilting dynamic culture not only accelerated the proliferation and differentiation of cells by physical or mechanical stimulation, but also ensured that the supply of medium was delivered to the basal cells more efficiently. Thus, the reconstruction of the corneal epithelium using LAM and tilting dynamic culture was considered to be a good in vitro model for autologous or allogeneic transplantation of corneal epithelium and skin epidermis in patients with damaged epithelia. </P>