Won-Cheoul Jang

Carbon Nanotubes in Nanocomposites and Hybrids with Hydroxyapatite for Bone Replacements

Hydroxyapatite (HA), as a bone mineral component, has been an attractive bioceramic for the reconstruction of hard tissues. However, its poor mechanical properties, including low fracture toughness and tensile strength, have been a significant challenge to the application of HA for the replacement of load-bearing and/or large bone defects. Among materials studied to reinforce HA, carbon nanotubes (CNTs: single-walled or multiwalled) have recently gained significant attention because of their unprecedented mechanical properties (high strength and toughness) and physicochemical properties (high surface area, electrical and thermal conductivity, and low weight). Here, we review recent studies of the organization of HA-CNTs at the nanoscale, with a particular emphasis on the functionalization of CNTs and their dispersion within an HA matrix and induction of HA mineralization. The organization of CNTs and HA implemented at the nanoscale can further be developed in the form of coatings, nanocomposites, and hybrid powders to enable potential applications in hard tissue reconstruction.

Physical properties and biological effects of activated carbon fibers treated with the herbs

Abstract Activated carbon fibers (ACFs) were treated with various medicinal materials. The physical properties and biological effects of these ACFs were examined. In order to investigate the properties, adsorption isotherms, BET surface area and pore analysis for the herb material treated ACFs must be obtained. The pore size distribution of the samples was obtained by a regularization method on the basis of the non-local and smoothed density function theory approximation support these findings. To investigate the surface of treated ACFs, the surface morphology of the resulting samples by S.E.M. show that many of the treated herbs were distributed irregularly on the surface of the fiber. In results of biological effects in the treated herbs, most all of samples showed excellent antibacterial effects after 200–400 min.

Ionic and thermo-switchable polymer-masked mesoporous silica drug-nanocarrier: High drug loading capacity at 10 °C and fast drug release completion at 40 °C

The preparation of the ideal smart drug-delivery systems were successfully achieved by the in situ co-polymerization of a vinyl group-functionalized mesoporous silica nanoparticle (f-MSN) with 1-butyl-3-vinyl imidazolium bromide (BVIm) and N-isopropylacrylamide (NIPAAm) monomers. The thickness of the capping copolymer layer, poly(NIPAAm-co-BVIm) (p-NIBIm), was controlled at between 2.5nm and 5nm, depending on the monomers/f-MSN ratio in the reaction solution. The finally obtained smart drug-delivery systems are named as p-MSN2.5 and p-MSN5.0 (MSNs integrated by 2.5nm and 5nm p-NIBIm layer in thickness). The key roles of the mesoporous-silica-nanoparticle (MSN) core and the p-NIBIm shell are drug-carrying (or containing) and pore-capping, respectively, and the latter has an on/off function that operates in accordance with temperature changes. According to the swelling- or shrinking-responses of the smart capping copolymer to temperature changes between 10°C and 40°C, the loading and releasing patterns of the model drug cytochrome c were studied in vitro. The developed system showed interesting performances such as a cytochrome-c-loading profile (loading capacity for 3h=26.3% and 19.8% for p-MSN2.5 and p-MSN5.0, respectively) at 10°C and a cytochrome-c-releasing profile (releasing efficiency=>95% within 3 days and 4 days for p-MSN2.5 and p-MSN5.0, respectively) at 40°C. The cytotoxicity of the drug delivery systems, p-MSN2.5 and p-MSN5.0 (in the concentration range of <0.125mg/mL without drug), for human embryonic kidney (HEK 293) cells were minimal in vitro compared with that of a blank MSN. These results may be reasonably applied in the field of specified drug delivery.

Loop-mediated Isothermal Amplification Assay to Rapidly Detect Wheat Streak Mosaic Virus in Quarantined Plants.

We developed a loop-mediated isothermal amplification (LAMP) method to rapidly diagnose Wheat streak mosaic virus (WSMV) during quarantine inspections of imported wheat, corn, oats, and millet. The LAMP method was developed as a plant quarantine inspection method for the first time, and its simplicity, quickness, specificity and sensitivity were verified compared to current reverse transcription-polymerase chain reaction (RT-PCR) and nested PCR quarantine methods. We were able to quickly screen for WSMV at quarantine sites with many test samples; thus, this method is expected to contribute to plant quarantine inspections.

Polymorphisms of small ubiquitin-related modifier genes are associated with risk of Alzheimer's disease in Korean: A case-control study

Sumoylation regulates transcription factor transactivation, protein-protein interactions, and appropriate subcellular localization of certain proteins. Previous studies have shown that sumoylation of amyloid precursor protein (APP) is associated with decreased levels of amyloid beta (Aβ) proteins, suggesting that sumoylation may play a role in the pathogenesis of Alzheimers disease (AD). We investigated the association between polymorphisms of the SUMO genes and the risk of AD. Our study subjects consisted of 144 AD patients and 335 healthy controls without dementia. We focused on tagged single nucleotide polymorphisms (tagSNPs) of the SUMO1 and SUMO2 genes. The tagSNPs were amplified by PCR and sequenced. We used binary logistic regression to calculate odds ratios (ORs) with 95% confidence intervals (CIs) for the associations between SUMO gene polymorphisms and the risk of AD. We found that rs12472035 polymorphism of SUMO1 was significantly associated with an increased risk of AD in male group (the CT genotype of rs12472035: adjusted OR=8.737, 95% CI=2.041-37.41, p-value=0.003). In addition, two polymorphisms of SUMO2 were significantly associated with an increased risk of AD in female group (the GA genotype of rs35271045: adjusted OR=2.879, 95% CI=1.399-5.924, p-value=0.004; and the TC genotype of rs9913676: adjusted OR=2.460, 95% CI=1.197-5.057, p-value=0.014). Furthermore, three combinations were associated with an increased risk of AD. Our data suggest that three individual polymorphisms and three combinations may be potential risk factors for AD in Korean population.

Characterization of Impaired Cerebrovascular Structure in APP/PS1 Mouse Brains

Alzheimers disease (AD) is defined by senile plaques, tauopathy and neuronal cell death in specific area of the brain. Recent studies suggest that neurovascular dysfunction may be an integral part of AD pathogenesis, contributing to the onset and development of AD pathologies such as neuronal death, inflammatory response, and breakdown of blood-brain barrier (BBB). In addition, vascular complications caused by age-related metabolic diseases such as diabetes and high blood pressure have high incidence in development of dementia and AD. We previously reported that astrocytes, essential components of BBB, were chronically activated and some deteriorated in the brain of 5xFAD, an amyloid precursor protein/presenilin1 (APP/PS1) transgenic mouse model. Thus, it is rational to investigate if any vascular dysfunction is associated with considerable activation of astrocytes in APP/PS1 mouse model. In this study, we observed that cerebrovascular pathology was associated with large scale of reactive astrocytes and neurodegeneration in an Aβ plague-generating mouse model. Using 5xFAD mouse brains, we demonstrate damaged brain vessels and reduced expression of glucose transporter 1 (GLUT1), the main glucose transporter, and a tight junction protein zonula occludens-1 (ZO-1) of cerebrovascular endothelial cells. This vascular pathology was closely associated with astrocytic deterioration and neuronal loss due to buildup of Aβ plaques in 5xFAD mouse brains.

Roles of 5-HT on phase transition of neurite outgrowth in the identified serotoninergic neuron C1, Helisoma trivolvis

Neurite outgrowth is a morphological marker of neuronal differentiation and neuroregeneration, and the process includes four essential phases, namely initiation, elongation, guidance and cessation. Intrinsic and extrinsic signaling molecules seem to involve morphological changes of neurite outgrowth via various cellular signaling cascades phase transition. Although mechanisms associated with neurite outgrowth have been studied extensively, little is known about how phase transition is regulated during neurite outgrowth. 5-HT has long been studied with regard to its relationship to neurite outgrowth in invertebrate and vertebrate culture systems, and many studies have suggested 5-HT inhibits neurite elongation and growth cone motility, in particular, at the growing parts of neurite such as growth cones and filopodia. However, the underlying mechanisms need to be investigated. In this study, we investigated roles of 5-HT on neurite outgrowth using single serotonergic neurons C1 isolated from Helisoma trivolvis. We observed that 5-HT delayed phase transitions from initiation to elongation of neurite outgrowth. This study for the first time demonstrated that 5-HT has a critical role in phase-controlling mechanisms of neurite outgrowth in neuronal cell cultures.

Past, Present and Future Molecular Approaches to Improve Yield in Wheat

This chapter addresses the development and use of molecular markers for yield enhancement in wheat. Since their key goal for breeding is to maximize yield, extensive efforts have been made toward the improvement of yield. Agronomic traits related to yield, yield-related, disease resistance, and abiotic stresses are considered to be quantitative traits (QTLs), also known as complex traits, because they are controlled by numerous genes and are affected by environmental factors. Researchers have been studying such traits in the past decades for the development of molecular markers which can be used in various wheat breeding studies mainly involving restriction fragment length polymorphism (RFLP), simple sequence repeat (SSR), single nucleotide polymorphism (SNP), random amplified polymorphic DNA (RAPD), and amplified fragment length polymorphism (AFLP). Furthermore, the advent of next-generation sequencing (NGS) has accelerated the discovery of agronomically important genes. All of the technologies have enabled great advances for increasing the productivity of wheat. Here, the past history of first-generation sequencing, present status of second-generation sequencing, and future potential of translational genomics linked to the yield will be discussed.

Development of Simple and Rapid Diagnostic Method for StrawberryLatent Ring-spot Virus in Plants Using Loop-Mediated IsothermalAmplification Assay

Strawberry Latent Ring-spot Virus (SLRSV) is seed or nematodes-transmitted viruses, and causes quantitative and qualitative loss of various crops. SLRSV is a non-reported, potentially control able virus, which is managed at the national level. Currently, RT-PCR and nested PCR system are the standard methods of detecting SLRSV, but more effective methods are required. In this study, loop-mediated isothermal amplification (LAMP) assay was used for detection of SLRSV. As a result, the LAMP assay showed sensitivity similar to that of the currently used method, but is more rapid (approximately 8 hrs), simple and specific. In addition, results can be verified by restriction fragment length polymorphism (RFLP) using BfaI, or sequencing after the LAMP reaction. Therefore, we have shown that the LAMP assay developed in this study is a potential marker for the facilitation of rapid and simple screening of SLRSV in plants, which will ultimately be useful for the diagnosis of SLRSV infected plants and quarantine.

Levels of Salivary Chromogranin-A Secreted During Simulated Monotonous Driving Stress

Salivary Chromogranin-A (CgA) was recently reported to be a useful biochemical marker of stress. The purpose of the present study was to evaluate the use of salivary CgA, which is already used in general as a mental stress marker, in response to the stressful situation created by simulated monotonous driving. After informed consent 25 healthy male & female subjects were studied, under constant environment-controlled conditions. We measured the following physiological variables: blood pressure (BP), cardiac output (CO), total peripheral resistance (TPR), normalized pulse volume (NPV) and levels of CgA during monotonous driving. The induced stress led to the expected decreases in NPV and in-creases in TPR and BP caused by peripherally-related sympathetic acceleration. However, CgA levels were found to fall gradually in accordance with the gradual increase of subjective rating of stress (SRS) and significantly (p<0.01) decreased over the period of the simulated monotonous driving.