Priority evaluation factors for blockchain application services in public sectors.

Blockchain is rapidly becoming established as the core technology of the Fourth Industrial Revolution. By combining blockchain to improve processes in existing industries, innovative new services will emerge, but services not effectively applied by blockchain will also develop. This study investigated the factors to be considered when applying the characteristics of blockchain technology to business. We developed a framework of blockchain service utility evaluation indexes using the analytic hierarchy process method. The Delphi method is used to identify highly effective blockchain application service cases by applying the evaluation framework to actual use cases in the public sector. By proposing a framework of utility evaluation factors for blockchain application services, this study provides a systematic foundation for blockchain business review. We address the question of "why blockchain should be applied to this service" by providing a more comprehensive approach than existing research, such as a fragmentary decision tree. Blockchains are expected to become more active along with the full-scale digital transformation of industries, and thus, we must examine the ways to broadly use blockchain as a base technology in a form applicable to the diverse industries and societies constituting the digital economy. Accordingly, this study presents an evaluation solution for promoting efficient policies and developing successful blockchain application services.

Stabilization of Lipid Lamellar Bilayer Structure of Stratum Corneum Modulated by Poly (2-methacryloyloxyethyl phosphorylcholine) in Relation to Skin Hydration and Skin Protection.

BACKGROUND: One crucial factor in skin tissue engineering is to understand the hydration and barrier property of skin. We investigated the skin hydration and stabilization strategy of inter-lamellar structure of stratum corneum (SC) using poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC). METHODS: The unique hydration and stabilization potency of PMPC on the barrier function of the SC examined using freshly excised hairless mouse skin as a model membrane and the relationship between the stabilization of the lipid lamellar bilayer (LLB) and its enhanced water holding capacity was established. RESULTS: Differential scanning calorimeter based on the phase-transition temperature of lipid domain of SC demonstrated that PMPC stabilized the LLB. The ratio of the heat of lipid phase transition (△H) of SC exposed to water and PMPC for 24 h was 1.51. X-ray crystallography showed the presence of well- organized lipids in intercellular membranes exhibiting short and long periodicity of lamellar phases. The peak at 4.4 nm attributed to the long periodicity phase (LPP) was missing in water-treated SC, where, the presence of 4.2- 4.4 nm peak in PMPC treated SC indicated that PMPC stabilized LPP. Transmission electron microscopy study demonstrated that the LLB structure became more rigid and orderly in PMPC treated SC. CONCLUSION: The unique ion paired structure of PMPC enhances the barrier function of the SC by stabilizing LLB structure and hydration by inducing weakly bound water. The unique hydration state and stabilization effect from extended water exposure could provide a valuable information to prepare reliable artificial skin matrix and skin tissue.

The relationship between ground reaction force components and peak power according to induced fatigue during 16-km walking.

The previous reviewed studies on inducement of fatigue through long-time walking were not only very confined, but also not cleared on relationship among variables of fatigue inducement active force, decay rate, and power. This study analyzed relationship between power and component of ground reaction force after fatigue being induced through 16-km walking. The fatigue of adult males and females (n=16) was induced through 16-km walking. Then power, measured for pre and post of fatigue inducement, was evaluated by maximal vertical jump on ground reaction force plate. Variables of vertical jump heights, active force, power, and decay rate showed decreased tendency after fatigue inducement, which followed significant difference (P<0.05) and also positive correlation of r=0.628 (R 2=39%) of between vertical jump heights and power and r=0.589 (R 2=34%) of between active force and decay rate respectively. That is, long-time walking for pursuing of exercise rehabilitation, health promotion and leisure activity has been preferred. In the view of this, this study suggested the necessity to understand the relation between fatigue and power to prevent a potential possibility of injury during long-time walking.

Effect of muscle mass asymmetric between upper and lower limbs on the postural stability and shock attenuation during landing.

The aim of the study was to analyze the effect of muscle mass asymmetric between upper and lower limbs on postural stability and shock attenuation during landing. Twenty adults (without lower limb disorders and who could land from a 35-cm height) participated in this study (mean age, 21.85±2.97 years; mean height, 1.68±0.10 m; mean weight: 68.64±17.36 kg). Subjects performed one-leg landing from 36-cm vertical heights. Ground reaction force components and medial-lateral, anterior-posterior, vertical and dynamic postural stability index were obtained from force platform recordings. We found that muscle mass in right limbs more increased than that of left limbs. Medial-lateral force, vertical force, vertical stability index, and dynamic postural stability index in left leg showed higher value than that of right leg during landing. The asymmetry of muscle mass (%) and ground reaction force variables showed a similar correlation, including dynamic postural stability index (r=0.316). These findings allow us to conclude that the factor of muscle mass asymmetric is a contributor to impulse control and dynamic postural stability index asymmetry. Therefore, knowledge of bilateral limbs asymmetry may provide insights into exercise rehabilitation and performance.

Alteration of microRNA 340-5p and Arginase-1 Expression in Peripheral Blood Cells during Acute Ischemic Stroke.

Acute stroke alters the systemic immune response as can be observed in peripheral blood; however, the molecular mechanism by which microRNA (miRNA) regulates target gene expression in response to acute stroke is unknown. We performed a miRNA microarray on the peripheral blood of 10 patients with acute ischemic stroke and 11 control subjects. Selected miRNAs were quantified using a TaqMan assay. After searching for putative targets from the selected miRNAs using bioinformatic analysis, functional studies including binding capacity and protein expression of the targets of the selected miRNAs were performed. The results reveal a total of 30 miRNAs that were differentially expressed (16 miRNAs were upregulated and 14 miRNAs were downregulated) during the acute phase of stroke. Using prediction analysis, we found that miR-340-5p was predicted to bind to the 3'-untranslated region of the arginase-1 (ARG1) gene; a luciferase reporter assay confirmed the binding of miR-340-5p to ARG1. miR-340-5p was downregulated whereas ARG1 mRNA was upregulated in peripheral blood in patients experiencing acute stroke. Overexpression of miR-340-5p in human neutrophil and mouse macrophage cell lines induced downregulation of the ARG1 protein. Transfection with miR-340-5p increased nitric oxide production after LPS treatment in a mouse macrophage cell line. Our results suggest that several miRNAs are dynamically altered in the peripheral blood during the acute phase of ischemic stroke, including miR-340-5p. Acute stroke induces the downregulation of miR-340-5p, which subsequently upregulates ARG1 protein expression.

Local Silencing of Connective Tissue Growth Factor by siRNA/Peptide Improves Dermal Collagen Arrangements.

BACKGROUND: Collagen organization within tissues has a critical role in wound regeneration. Collagen fibril diameter, arrangements and maturity between connective tissue growth factor (CTGF) small interfering RNA (siRNA) and mismatch scrambled siRNA-treated wound were compared to evaluate the efficacy of CTGF siRNA as a future implement for scar preventive medicine. METHODS: Nanocomplexes of CTGF small interfering RNA (CTGF siRNA) with cell penetrating peptides (KALA and MPG∆NLS) were formulated and their effects on CTGF downregulation, collagen fibril diameter and arrangement were investigated. Various ratios of CTGF siRNA and peptide complexes were prepared and down-regulation were evaluated by immunoblot analysis. Control and CTGF siRNA modified cells-populated collagen lattices were prepared and rates of contraction measured. Collagen organization in rabbit ear 8 mm biopsy punch wound at 1 day to 8 wks post injury time were investigated by transmission electron microscopy and histology was investigated with Olympus System and TS-Auto software. CONCLUSION: CTGF expression was down-regulated to 40% of control by CTGF siRNA/KALA (1:24) complexes (p < 0.01) and collagen lattice contraction was inhibited. However, down-regulated of CTGF by CTGF siRNA/MPG∆NLS complexes was not statistically significant. CTGF KALA-treated wound appeared with well formed-basket weave pattern of collagen fibrils with mean diameter of 128 ± 22 nm (n = 821). Mismatch siRNA/KALA-treated wound showed a high frequency of parallel small diameter fibrils (mean 90 ± 20 nm, n = 563). CONCLUSION: Controlling over-expression of CTGF by peptide-mediated siRNA delivery could improve the collagen orientation and tissue remodeling in full thickness rabbit ear wound.

Effect of Palmitoyl-Pentapeptide (Pal-KTTKS) on Wound Contractile Process in Relation with Connective Tissue Growth Factor and α-Smooth Muscle Actin Expression.

To evaluate whether Palmitoyl-pentapeptide (Pal-KTTKS), a lipidated subfragment of type 1 pro-collagen (residues 212-216), plays a role in fibroblast contractility, the effect of Pal-KTTKS on the expression of pro-fibrotic mediators in hypertropic scarring were investigated in relation with trans-differentiation of fibroblast to myofibroblast, an icon of scar formation. α-SMA was visualized by immunofluorescence confocal microscopy with a Cy-3-conjugated monoclonal antibody. The extent of α-SMA-positive fibroblasts was determined in collagen lattices and in cell culture study. Pal-KTTKS (0-0.5 µM) induced CTGF and α-SMA protein levels were determined by western blot analysis and fibroblast contractility was assessed in three-dimensional collagen lattice contraction assay. In confocal analysis, fibroblasts were observed as elongated and spindle shapes while myofibroblast observed as squamous, enlarged cells with pronounced stress fibers. Without Pal-KTTKS treatment, three quarters of the fibroblasts differentiates into the myofibroblast; α-SMA-positive stress fibers per field decreased twofold with 0.1 µM Pal-KTTKS treatment (75 ± 7.1 vs 38.6 ± 16.1%, n = 3, p < 0.05). The inhibitory effect was not significant in 0.5 µM Pal-KTTKS treatment. Stress fiber level and collagen contractility correlates with α-SMA expression level. In conclusion, Pal-KTTKS (0.1 µM) reduces α-SMA expression and trans-differentiation of fibroblasts to myofibroblast. The degree of reduction is dose-dependent. An abundance of myofibroblast and fibrotic scarring is correlated with excessive levels of α-SMA and collagen contractility. Delicate balance between the wound healing properties and pro-fibrotic abilities of pentapeptide KTTKS should be considered for selecting therapeutic dose for scar prevention.

Inhibition of fibrotic contraction by C-phycocyanin through modulation of connective tissue growth factor and α-smooth muscle actin expression.

The effects of C-phycocyanin (C-pc), a phycobiliprotein, on the expression of pro-fibrotic mediators in hyper-tropic scarring such as connective tissue growth factor (CTGF) and α-smooth muscle actins (α-SMA) were investigated in relation to trans-differentiation of fibroblast to myo-fibroblast, an icon of scar formation. C-pc was isolated from Spirulina Platensis extract using sonication method and C-pc concentration was determined by Bennet and Bogorad equation. α-SMA and CTGF levels in wounded primary human dermal fibroblasts were determined by western blot analysis and immuno-fluorescence confocal microscope was employed. Fibroblast contractility was examined by three-dimensional collagen lattice contraction assay. There was an elevation of α-SMA (121%) and CTGF (143%) levels in wound cells as compared with non-wound cells. The does-response profiles of down regulation demonstrated that the maximum inhibitions of α-SMA by 63% (p<0.05) and CTGF by 50% (p<0.1) were achieved by C-pc (6 nM) treated cells. In confocal assay, non-wound fibroblasts exhibited basal level of α-SMA staining, while wounded cells without C-pc treatment showed strong up-regulation of α-SMA by 147% (p<0.05). C-pc (6 nM) inhibited α-SMA expression by 70% (p<0.05) and reduced collagen contraction by 29% (p<0.05). C-pc seemed to lessen the over expression of CTGF, α-SMA, subsequently alleviating the fibrotic contracture. This study suggests the potential application of C-pc to regulation of the expression of pro-fibrotic mediators in scarring process and its potential usage as an efficient means for anti-fibrosis therapy.

Effect of freeze dried bovine amniotic membrane extract on full thickness wound healing.

This study explored the feasibility of development of solubilized amniotic membrane extract (AME) as a potential wound healing substrate with improved efficacy. Bovine amniotic membrane was extracted using a mixture of acetic acid and 2-mercaptopropionic acid under sonication, which was followed by the frozen, and then lyophilized processes. The effects of AME on cell migration and growth properties were evaluated from 0 to 24 h of post injury using primary human foreskin fibroblast monolayer culture with one line scratch as an in vitro wound model. Its wound healing efficacy and scar preventive effects were investigated using whole thickness biopsy punch (8 mm) wound model obtained from rabbit ear. Intra dermal injections of AME fluid (10 µl of 1.2 µg/µl) on four wound sites were performed at 1 h pre injury, post 1, 2 and 3 day. The processes and levels of re-epithelialization and dermal regeneration were examined through histological assessment with H-E staining. In cell migration study conducted at 24 h post injury, AME (1.7 µg/ml) treated cells significantly increased wound closure with 54.9 % compared to control. Histological image analysis on AME treated wound sites at 36 days post injury showed properly developed epidermal basal cell layers and weave-like dermal collagen bundles, whereas those of untreated control skin showed over-proliferation of epidermis and aggregated collagen bundles with defected dermal regeneration. The results of this study verified the feasibility of dermal injections of freeze dried AME as a potential wound healing substrate which can promote epidermal and dermal regeneration, while avoiding undesirable hyper-proliferation of damaged tissue.

Optimum scratch assay condition to evaluate connective tissue growth factor expression for anti-scar therapy.

To evaluate a potential anti-scar therapy, we first need to have a reliable in vitro wound model to understand dermal fibroblast response upon cell injury and how cytokine levels are changed upon different wound heal phases. An in vitro wound model with different scratch assay conditions on primary human foreskin fibroblast monolayer cultures was prepared and cytokine levels and growth properties were evaluated with the aim of determining optimum injury conditions and observation time. Morphological characteristics of differently scratched fibroblasts from 0 to 36 h post injury (1 line, 2 lines and 3 lines) were investigated. The expression of connective tissue growth factor, CTGF, which is a key mediator in hyper-tropic scarring, and relative intensity of CTGF as a function of time were determined by western blot and gelatin Zymography. After injury (1 line), CTGF level was increased more than 2-fold within 1 h and continuously increased up to 3-fold at 6 h and was leveled down to reach normal value at 36 h, at which cell migration was complete. In more serious injury (2 lines), higher expression of CTGF was observed. The down regulation of CTGF expression after CTGF siRNA/lipofectamine transfection in control, 1 line and 2 lines scratch conditions were 40%, 75% and 55%, respectively. As a model anti-CTGF based therapy, CTGF siRNA with different ratios of linear polyethyleneimine (PEI) complexes (1:1, 1:5, 1:10, 1:20 and 1:30) were prepared and down-regulation efficacy of CTGF was evaluated with our optimized scratch assay, which is 1 line injury at 6 h post injury observation time. As the cationic linear PEI ratio increased, the down regulation efficacy was increased from 20% (1:20) to 55% (1:30). As CTGF level was increased to the highest at 6 h and leveled down afterwards, CTGF level at 6 h could provide the most sensitive response upon CTGF siRNA transfection. The scratch assay in the present study can be employed as a useful experimental tool to differentiate between anti-scar therapies for their down regulation efficacy of CTGF.

Prophylactic effect of dexamethasone in reducing postoperative sore throat.

BACKGROUND: This study was performed to compare the effectiveness of prophylactic dexamethasone and postintubation dexamethasone in reducing the incidence and severity of postoperative sore throat (POST). METHODS: This was a prospective, randomized, double-blind clinical trial. The study population consisted of 70 patients between 20 and 60 years old who were classified as American Society of Anesthesiologists I-II and were scheduled for elective laparoscopic cholecystectomy. The patients were divided randomly into two groups. Patients in the prophylactic and postintubation groups received intravenous injection of 10 mg of dexamethasone 30 min before or after tracheal intubation, respectively. The patients were interviewed 1, 6, and 24 h after the operation. The incidence and severity of POST were recorded. RESULTS: The severity scores of POST at 1 and 6 h after the operation were significantly lower in the prophylactic group than in the postintubation group. There were no significant differences in the incidence of POST during the 24 h after the operation between the two groups (22/32 in the prophylactic group vs. 27/34 in the postintubation group, P = 0.403). CONCLUSIONS: Intravenous injection of 10 mg of dexamethasone was more effective in reducing the severity of POST when administered before tracheal intubation compared with after tracheal intubation.

Gravimetric analysis and differential scanning calorimetric studies on glycerin-induced skin hydration.

A thermal gravimetric analysis (TGA) and a differential scanning calorimetry (DSC) were carried out to characterize the water property and an alteration of lipid phase transition of stratum corneum (SC) by glycerin. In addition, the relationship between steady state skin permeation rate and skin hydration in various concentrations of glycerin was investigated. Water vapor absorption-desorption was studied in the hairless mouse stratum corneum. Dry SC samples were exposed to different conc. of glycerin (0-50%) followed by exposure to dry air and the change in weight property was monitored over time by use of TGA. In DSC study, significant decrease in DeltaH of the lipid transition in 10% glycerin and water treated sample: the heat of lipid transition of normal, water, 10% glycerin treated SC were 6.058, 4.412 and 4.316 mJ/mg, respectively. In 10% glycerin treated SCs, the Tc of water shifts around 129 degrees C, corresponding to the weakly bound secondary water. In 40% glycerin treated SC, the Tc of water shifts to 144 degrees C corresponding to strongly bound primary water. There was a good correlation between the hydration property of the skin and the steady state skin flux with the correlation coefficient (r2=0.94). As the hydration increased, the steady state flux increased. As glycerin concentration increased, hydration property decreased. High diffusivity induced by the hydration effect of glycerin and water could be the major contributing factor for the enhanced skin permeation of nicotinic acid (NA).

Comparison of antibiogram, staphylococcal enterotoxin productivity, and coagulase genotypes among Staphylococcus aureus isolated from animal and vegetable sources in Korea.

Staphylococcal food poisoning is caused by enterotoxin-producing Staphylococcus aureus. We investigated the prevalence of such organisms in samples of bovine mastitic milk (n = 714), raw meat (n = 139), and vegetables (n = 616). We determined the degrees of relatedness of isolates as indicated by antibiogram, staphylococcal enterotoxin (SE) productivity, and coagulase gene restriction fragment length polymorphism analysis. We examined 297 S. aureus isolates and found SE production in 57 (31.8%), 4 (7.8%), and 49 (73.1%) isolates from raw milk, raw meat, and vegetables, respectively. A high proportion of the isolates obtained from milk produced more than two types of toxins (mainly SEA, SEB, and/or SEC), whereas isolates from raw meat and vegetables primarily produced SEA alone. Most isolates were sensitive to cephalothin (97.6%), gentamicin (80.8%), erythromycin (79.5%), and tetracycline (72.7%), but were resistant to penicillin (90.2%) and ampicillin (88.9%). The proportion of antibiotic-resistant isolates differed according the source of the bacteria; the milk and vegetable isolates were more resistant to penicillin and ampicillin than were the meat isolates (P < 0.05), whereas tetracycline resistance was limited to the milk and vegetables isolates. The coagulase genotypes (I to XII) varied with the source of the organism, and only a few genotypes prevailed in each source: II (42.4%) and IV (24%) types in isolates from milk, IX (35.3%) and XI (45%) from raw meat, and III (40.3%) and XII (32.8%) from vegetables. These findings suggest that remarkable differences exist in antibiogram, SE productivity, and coagulase genotypes, resulting in limited clonal transmission of S. aureus into various food sources. As enterotoxin production only occurs when S. aureus grows to high numbers, staphylococcal food poisoning can be prevented by proper refrigeration.

Enhancing dermal matrix regeneration and biomechanical properties of 2nd degree-burn wounds by EGF-impregnated collagen sponge dressing.

To better define the relationship between dermal regeneration and wound contraction and scar formation, the effects of epidermal growth factor (EGF) loaded in collagen sponge matrix on the fibroblast cell proliferation rate and the dermal mechanical strength were investigated. Collagen sponges with acid-soluble fraction of pig skin were prepared and incorporated with EGF at 0, 4, and 8 microg/1.7 cm2. Dermal fibroblasts were cultured to 80% confluence using DMEM, treated with the samples submerged, and the cell viability was estimated using MTT assay. A deep, 2nd degree- burn of diameter 1cm was prepared on the rabbit ear and the tested dressings were applied twice during the 15-day, post burn period. The processes of re-epithelialization and dermal regeneration were investigated until the complete wound closure day and histological analysis was performed with H-E staining. EGF increased the fibroblast cell proliferation rate. The histology showed well developed, weave-like collagen bundles and fibroblasts in EGF-treated wounds while open wounds showed irregular collagen bundles and impaired fibroblast growth. The breaking strength (944.1 +/- 35.6 vs. 411.5 +/- 57.0 Fmax, gmm(-2)) and skin resilience (11.3 +/- 1.4 vs. 6.5 +/- 0.6 mJ/mm2) were significantly increased with EGF-treated wounds as compared with open wounds, suggesting that EGF enhanced the dermal matrix formation and improved the wound mechanical strength. In conclusion, EGF-improved dermal matrix formation is related with a lower wound contraction rate. The impaired dermal regeneration observed in the open wounds could contribute to the formation of wound contraction and scar tissue development. An extraneous supply of EGF in the collagen dressing on deep, 2nd degree-burns enhanced the dermal matrix formation.

Reversal of silver sulfadiazine-impaired wound healing by epidermal growth factor.

Silver sulfadiazine (Ag-SD) is a useful antibacterial agent for wound treatment. However, recent findings indicate that the compound delays the wound-healing process. That delay may be reversed by treatment with growth factors. The purpose of this study, was to evaluate the cyto-protective effect of epidermal growth factor (EGF) against Ag-SD treated keratinocytes and to investigate the reversibility of the impaired wound-healing process by the co-supplementation of EGF. Four types of drug-loaded collagen sponge dressings with different concentrations of Ag-SD, EGF and Ag-SD + EGF were prepared. An immortalized keratinocyte, HaCaT cells, were cultured in 35-mm Petri-dish using Dulbecco's Modified Eagle's Minimal Essential Medium (DMEM) with 10% FBS. Cultures were treated with the samples submerged, and viabilities of cultures were evaluated using MTT assay. The wound heal efficacy was evaluated in a partial thickness burn mouse model. Cells treated with EGF showed a cyto-protective effect on 1% Ag-SD treated cells with significant increase in viable cell numbers at concentrations ranging from 1 to 50 microg/ml. The cytotoxicity of Ag-SD impaired wound healing, while the addition of EGF could reverse the impairment. This evidence suggests that EGF is a useful agent in the retardation of wound healing caused by Ag-SD. Therefore, a drug delivery system containing both EGF and Ag-SD, such as that used in the study, may be clinically relevant.

Phospholipid polymer, 2-methacryloyloxyethyl phosphorylcholine and its skin barrier function.

The effect of poly[2-methacryloyloxyethyl phosphorylcholine] (pMPC) on the skin permeation property was investigated by performing in vitro skin permeation study of a model drug, nicotinic acid (NA). Effect of pMPC polymer in donor solution on skin permeation rates was evaluated using side-by-side diffusion cells. Also, the structural alterations in the stratum corneum (SC), inter-lamellar bilayer (ILB) and dermis layers in pMPC-treated and -untreated skin sections were investigated with transmission electron microscopy (TEM). The permeation profile of NA without pMPC in donor solution showed biphasic mode: initial 1st phase and 2nd hydration phase. The sudden, more than 10-fold increase in flux from the initial steady state (43.5 microg/cm2/hr) to the 2nd hydration phase (457.3 microg/cm2/h) suggests the disruption of skin barrier function due to extensive hydration. The permeation profile of NA with 3% pMPC in the donor solution showed monophasic pattern: the steady state flux (10.9 microg/cm2/h) without abrupt increase of the flux. The degree of NA permeation rate decreased in a concentration-dependent manner of pMPC. TEM of skin equilibrated with water or 2% pMPC for 12 h showed that corneocytes are still cohesive and epidermis is tightly bound to dermis in 2% pMPC-treated skin, while wider separation between corneocytes and focal dilations in inter-cellular spaces were observed in water-treated skin. This result suggests that pMPC could protect the barrier property of the stratum corneum by preventing the disruption of ILB structure caused by extensive skin hydration during skin permeation study.

Molecular typing of enterotoxigenic Staphylococcus aureus isolated from bovine mastitis in Korea.

One hundred and sixty-six Staphylococcus aureus isolates from mastitic milk samples from different cows on 26 farms were investigated for staphylococcal enterotoxins(SEs) and toxic shock syndrome toxin-1(TSST-1) by polymerase chain reaction(PCR) and reverse passive latex agglutination assay(RPLA). SEs and the TSST-1 gene were detected in thirty-seven isolates based on a multiplex PCR; SEA was detected in 32 isolates, SEB in 3 isolates, SEC in 1 isolate, and SEA and the TSST-1 gene in 1 isolate. Of the 37 enterotoxigenic isolates, thirty-three isolates were enterotoxigenic according to RPLA, where 29 isolates produced SEA, 3 isolates produced SEB, and 1 isolate produced SEC. The enterotoxin-producing S. aureus isolates were further characterized by pulsed-field gel electrophoresis(PFGE). A macrorestriction analysis revealed 11 PFGE patterns. Among the 33 enterotoxigenic S. aureus isolates, 45.4% exhibited the same PFGE pattern I. Accordingly, although the enterotoxin-producing S. aureus isolates from bovine mastitis were genetically diverse, 1 common genotype prevailed on the farms, indicating that PFGE pattern I isolates may be the most disseminated in Korea.

Effect of topically applied silver sulfadiazine on fibroblast cell proliferation and biomechanical properties of the wound.

The effect of silver sulfadiazine (SSD) on the proliferation of human dermal fibroblast (HDF) was studied to determine the impact of the drug on the wound healing process and dermal mechanical strength. Human dermal fibroblasts were cultured to 80% confluency using DMEM with 10% FBS and viability of the cell was estimated using neutral red assay. In addition, the 2nd degree burn wound was prepared on the anterior part of rabbit ear skin and dressings containing SSD were applied for 96 h. Presence of inflammatory cells and degree of re-epithelialization were investigated in the wound. After 15 day of the induction of burn wounds, the treated area was excised and dermal mechanical strength was quantitatively measured with a constant speed tensiometer. SSD was found to be highly cyto-toxic in cultured HDF cells. The topical application of SSD (2%) could control the infection as evidenced by the lack of accumulation of inflammatory cells in histological evaluation. Therefore, these observations suggested that the impairment of dermal regeneration and decreased mechanical strength of dermal tissue was resulted from the cyto-toxic effect of SSD on dermal cells. Since the decreased mechanical strength may lead to reduction in resilience, toughness and maximum extension of the tissue, the identification of optimum dose for SSD that limits infection while minimizes the cyto-toxic effect may be clinically relevant.