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"Yi, Kiho"
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Friction Anisotropy—Driven Domain Imaging on Exfoliated Monolayer Graphene
Graphene produced by exfoliation has not been able to provide an ideal graphene with performance comparable to that predicted by theory, and structural and/or electronic defects have been proposed as one cause of reduced performance. We report the observation of domains on exfoliated monolayer graphene that differ by their friction characteristics, as measured by friction force microscopy. Angle-dependent scanning revealed friction anisotropy with a periodicity of 180° on each friction domain. The friction anisotropy decreased as the applied load increased. We propose that the domains arise from ripple distortions that give rise to anisotropic friction in each domain as a result of the anisotropic puckering of the graphene.
Journal Article
Assessment of Anti-Inflammatory and Antioxidant Effects of Citrus unshiu Peel (CUP) Flavonoids on LPS-Stimulated RAW 264.7 Cells
Citrus unshiu is a popular medicinal herb in several Asian countries, in particular South Korea. C. unshiu peel (CUP) has several biologically active compounds, including flavonoids. Hence, this research aimed to label the flavonoids from CUP by HPLC-MS/MS analysis and examine their anti-inflammatory and antioxidant potential on LPS-stimulated RAW 264.7 macrophages. A total of four flavonoids (Rutin, naringin, hesperidin, and poncirin) were characterized, and their contents were quantified from CUP. It showed that the naringin is rich in CUP. Further, treatment with the flavonoids at concentrations of 2.5 and 5 μg/mL had no effect on the cell viability of RAW 264.7 macrophages. On the other hand, it decreased the production and expression of inflammatory mediators and pro-inflammatory cytokines such as NO, PGE2, TNF-α, IL-1β, iNOS, and COX2 in the LPS-stimulated RAW 264.7 macrophages. In addition, flavonoids treatment inhibited the NF-κB activation by downregulating the p-p65 and p-IκBα proteins expression. Furthermore, reactive oxygen species (ROS) production considerably decreased at the same concentrations while antioxidant enzyme activity increased in the LPS-stimulated RAW 264.7 macrophages. Collectively, our results show that CUP flavonoids have the potential to decrease inflammation and oxidative damage.
Journal Article
Association of Increased Hair Calcium Levels and Enhanced Augmentation Index (AIx): a Marker of Arterial Stiffness
Arterial stiffness is involved in the pathophysiology of cardiovascular disease, and the degree of arterial stiffness is associated with the extent of vascular calcification. This study aimed to investigate the association of hair calcium levels with augmentation index (AIx), a simple, non-invasive measurement for arterial stiffness. Healthy Koreans (male, n = 34, female, n = 70) were enrolled in this study. Anthropometric parameters, lipid profiles, fasting glucose, hair mineral levels, and AIx were measured. Pearson/partial correlations and multivariate linear regression analyses were used to assess the relationship between hair calcium levels and AIx. AIx positively correlated with hair calcium levels (r = 0.275, p = 0.005), age (r = 0.283, p = 0.004), systolic blood pressure (r = 0.282, p = 0.004), low-density lipoprotein (LDL)-cholesterol (r = 0.255, p = 0.009), and hair magnesium (r = 0.196, p = 0.046), and negatively correlated with heart rate (r = -0.563, p < 0.001) and fasting glucose (r = -0.262, p = 0.005). Hair calcium levels significantly correlated with hair magnesium (r = 0.926, p < 0.001). Significant relationship between AIx and hair calcium levels was maintained after adjustment for sex, age, height, hear rate, blood pressure, total cholesterol, LDL-cholesterol, fasting glucose, and hair magnesium (r = 0.244, p = 0.018). Logistic regression model showed that AIx increased with the increment of hair calcium levels; log-AIx increased by 0.403% (95% CI: 0.139-0.515, p = 0.001) per unit change in log-hair calcium level (sex-adjusted). After adjustment for all the variables above together with triglyceride and high-density lipoprotein-cholesterol, increased significance of the association was 0.513% (p = 0.016)]. This study supports the presence of the independent positive relationship between hair calcium levels and AIx. It suggests the possibility that hair calcium levels may be a useful index for reflecting arterial stiffness.
Journal Article
Porcine testicular extract inhibits T cell proliferation by blocking cell cycle transition from G1 phase to S phase
Since T cells express diverse sex steroid hormone receptors, they might be a good model to evaluate the effects of sex steroid hormones on immune modulation. Porcine testicular extract contains several sex steroid hormones and may be useful to study the effects of sex steroid hormones during T cell activation. We have examined the effects of the porcine testicular extract on T cell activation: proliferation and secretion of cytokines (IL-2 and IFN-γ) by activated T cells were severely decreased after treatment with porcine testicular extract. The extract produced an immunosuppressive effect and inhibited the proliferation of activated T cells by blocking the cell cycle transition from the G
1
phase to S phase. These effects were mediated by a decrease in the expression of cyclin D1 and cyclin E and constitutive expression of p27
KIP1
after T cell activation.
Journal Article
Effect of Saururus chinensis leaves extract on type II collagen-induced arthritis mouse model
Background Saururus chinensis leaves have been used as traditional medicine in Korea for pain, intoxication, edema, and furuncle. According to previous reports, these leaves exert renoprotective, neuroprotective, and antioxidant effects by attenuating inflammatory responses. However, the beneficial effect of Saururus chinensis leaves on arthritis has not been elucidated. Thus, we evaluated the water extract of Saururus chinensis leaves (SHW) using type II collagen-induced arthritis (CIA) mice models. Methods Quantitative analysis of major components from SHW was performed by HPLC. Arthritis was induced by injection of type II collagen. Each group was orally administered SHW (100 mg/kg and 500 mg/kg). Methotrexate (MTX) was used as a positive control. Serum levels of interleukin-6, TNF-alpha, and type II collagen IgG in the animal models were measured using ELISA. Histological features were observed by H&E staining. Results Quantitative analysis of SHW showed the contents as 56.4 ± 0.52 mg/g of miquelianin, 7.75 ± 0.08 mg/g of quercetin 3-O-(2”-O-β -glucopyranosyl)-α-rhamnopyranoside, and 3.17 ± 0.02 mg/g of quercitrin. Treatment with 500 mg/kg SHW decreased the serum level of Interleukin-6 (IL-6), TNF-alpha, and collagen IgG in the CIA model. Moreover, SHW treatment diminished the swelling of hind limbs and monocyte infiltration in blood vessels in CIA animal models. The results indicate that SHW could decrease CIA-induced arthritis in vivo. Conclusions The results indicate that SHW could be used to improving arthritis by reducing inflammatory factors (IL-6 and TNF-alpha). However, further experiments are required to determine how SHW influences signal transduction in animal models.
Journal Article
Gene expression profiles analyzed by DNA sequencing of cDNA clones constructed from porcine preadipocytes and adipocytes
As a step towards understanding the molecular mechanism of adipogenesis in pigs, preadipocytes purified from the back fat of 1 day-old female piglets were used for in vitro culture. Normalized cDNA libraries were constructed with 1.6×107 and 1.1×107 independent clones from preadipocyte and mature adipocyte mRNAs, respectively. Polymerase chain reaction (PCR) result using primers T3 and T7 (universal primer) confirmed the presence of the insert in the vector. Sequencing of 2,112 randomly selected clones from each cDNA library identified 217 clusters, 1,169 singletons, and 216 contigs in preadipocytes and 231 clusters, 1,100 singletons, and 233 contigs in mature adipocytes. Expressed sequence tag (EST) identified 24 genes with known annotation highly expressed in adipocytes and 21 in preadipocytes by at least four EST number. Among those 45 genes, when analyzed by real time RT-PCR, 76% of the gene showed significant difference between preadipocytes and mature adipocytes. Highly expressed genes in mature adipocytes were related to adipogenesis, extracellular matrix control and oncogenes, whereas cytoskeleton-related genes were down-regulated. An interesting similarity found during gene profile studies indicated a correlation between cancer and adipogenesis.
Journal Article
Bionic artificial skin with a fully implantable wireless tactile sensory system for wound healing and restoring skin tactile function
Tactile function is essential for human life as it enables us to recognize texture and respond to external stimuli, including potential threats with sharp objects that may result in punctures or lacerations. Severe skin damage caused by severe burns, skin cancer, chemical accidents, and industrial accidents damage the structure of the skin tissue as well as the nerve system, resulting in permanent tactile sensory dysfunction, which significantly impacts an individual’s daily life. Here, we introduce a fully-implantable wireless powered tactile sensory system embedded artificial skin (WTSA), with stable operation, to restore permanently damaged tactile function and promote wound healing for regenerating severely damaged skin. The fabricated WTSA facilitates (i) replacement of severely damaged tactile sensory with broad biocompatibility, (ii) promoting of skin wound healing and regeneration through collagen and fibrin-based artificial skin (CFAS), and (iii) minimization of foreign body reaction via hydrogel coating on neural interface electrodes. Furthermore, the WTSA shows a stable operation as a sensory system as evidenced by the quantitative analysis of leg movement angle and electromyogram (EMG) signals in response to varying intensities of applied pressures.
Although artificial skins can facilitate the healing of damaged skin, the restoration of tactile functions remain a challenge. Here, Kang et al. report an artificial skin with an implantable tactile sensor that can simultaneously replace the tactile function by nerve stimulation and promote skin regeneration.
Journal Article
Edge‐Site‐Free and Topological‐Defect‐Rich Carbon Cathode for High‐Performance Lithium‐Oxygen Batteries
The rational design of a stable and catalytic carbon cathode is crucial for the development of rechargeable lithium‐oxygen (LiO2) batteries. An edge‐site‐free and topological‐defect‐rich graphene‐based material is proposed as a pure carbon cathode that drastically improves LiO2 battery performance, even in the absence of extra catalysts and mediators. The proposed graphene‐based material is synthesized using the advanced template technique coupled with high‐temperature annealing at 1800 °C. The material possesses an edge‐site‐free framework and mesoporosity, which is crucial to achieve excellent electrochemical stability and an ultra‐large capacity (>6700 mAh g−1). Moreover, both experimental and theoretical structural characterization demonstrates the presence of a significant number of topological defects, which are non‐hexagonal carbon rings in the graphene framework. In situ isotopic electrochemical mass spectrometry and theoretical calculations reveal the unique catalysis of topological defects in the formation of amorphous Li2O2, which may be decomposed at low potential (∼ 3.6 V versus Li/Li+) and leads to improved cycle performance. Furthermore, a flexible electrode sheet that excludes organic binders exhibits an extremely long lifetime of up to 307 cycles (>1535 h), in the absence of solid or soluble catalysts. These findings may be used to design robust carbon cathodes for LiO2 batteries. An edge‐site‐free and topological‐defect‐rich graphene mesosponge (GMS) is proposed as a carbon cathode for lithium‐oxygenbatteries. The GMS is highly stable, with high discharge capacity, low charge plateau and enhanced electrochemical stability compared to other commercial carbon materials. The table of contents image shows the formation of easily‐decomposable Li2O2 at the topological defects on GMS.
Journal Article
Pigs lacking Natural Killer T cells have altered cellular responses to influenza
It is increasingly recognized that innate T cells such as natural killer T (NKT) cells, mucosal associated invariant T (MAIT) cells, and γδ T cells play an important role in shaping adaptive immune responses following influenza infection or vaccination. This is largely through the multiple cytokines these cells release upon activation, which have downstream effects on the scope and magnitude of virus-specific T and B cells, and antibodies which they form. Here, we examined the contribution of NKT cells using pigs, which are considered a highly translational model of human influenza A infection. CD1D -expressing and CD1D -deficient pigs that respectively possess and lack NKT cells, were infected with the swine influenza virus H3N2 A/Swine/Colorado/23619/1999 (CO99), with or without prior mucosal immunization with a recombinant H3N2 A/Swine/Texas/4199–2/1998 (TX98) modified live vaccine encoding a truncated NS1 protein (TX98 NS1Δ126). Vaccination reduced virus load and pulmonary pathology by similar amounts in both genotypes. However, NKT cell status had a significant impact on the underlying immune response: Contrary to the post vaccination period, virus-specific T cell expansion after infection was greater in CD1D -deficient than CD1D -expressing pigs, indicating that NKT cells play opposing roles in different phases of the immune response. NKT cell-deficient pigs also had reduced T cell cuffing around airways. Furthermore, paired single-cell and immune receptor profiling revealed altered gene expression and higher numbers of expanded T and B cell clones in the absence of NKT cells. Our newly established assay using porcine-specific γ and δ chain primers provided new insights into the TCR repertoire of various pulmonary γδ Τcell subsets. Overall, our results indicate a homeostatic role for NKT cells in regulating several important features of the influenza immune response, particularly virus-specific T cell dynamics.
Journal Article