Dong-Gyu Kim

A disulphide-linked heterodimer of TWIK-1 and TREK-1 mediates passive conductance in astrocytes

TWIK-1 is a member of the two-pore domain K(+) (K2P) channel family that plays an essential part in the regulation of resting membrane potential and cellular excitability. The physiological role of TWIK-1 has remained enigmatic because functional expression of TWIK-1 channels is elusive. Here we report that native TWIK-1 forms a functional channel at the plasma membrane of astrocytes. A search for TWIK-1-binding proteins led to the identification of TREK-1, another member of the K2P family. The TWIK-1/TREK-1 heterodimeric channel is formed via a disulphide bridge between residue C69 in TWIK-1 and C93 in TREK-1. Gene silencing demonstrates that surface expression of TWIK-1 and TREK-1 are interdependent. TWIK-1/TREK-1 heterodimers mediate astrocytic passive conductance and cannabinoid-induced glutamate release from astrocytes. Our study sheds new light on the diversity of K2P channels.

BACE1 inhibitory effects of lavandulyl flavanones from Sophora flavescens.

In order to access beta-secretase (BACE1), and enzyme strongly implicated in the cause of Alzheimers disease, inhibitors must possess sufficient lipophilicity to traverse two lipid bilayers. Current drug candidates, which are almost totally peptide-derived, are thus inefficient because cell permeability presents a serious limiting factor. In this study, lipophilic alkylated (C(10)-C(5)) flavanones from Sophora flavescens were examined for their inhibitory effects against beta-secretase. Lavandulyl flavanones (1, 2, 5, 6, and 8) showed potent beta-secretase inhibitory activities with IC(50)s of 5.2, 3.3, 8.4, 2.6, and 6.7microM, respectively, while no significant activity was observed in the corresponding hydrated lavandulyl flavanones (4 and 7) and prenylated flavanone (3). As we expected, lavandulyl flavanones reduced Abeta secretion dose-dependently in transfected human embryonic kidney (HEK-293) cells. In kinetic studies, all compounds screened were shown to be noncompetitive inhibitor.

Enhancement of TREK1 channel surface expression by protein–protein interaction with β-COP

TREK1 belongs to a family of two-pore-domain K(+) (K(2P)) channels and produce background currents that regulate cell excitability. In the present study, we identified a vesicle transport protein, beta-COP, as an interacting partner by yeast two-hybrid screening of a human brain cDNA library with N-terminal region of TREK1 (TREK1-N) as bait. Several in vitro and in vivo binding assays confirmed the protein-protein interaction between TREK1 and beta-COP. We also found that beta-COP was associated with TREK1 in native condition at the PC3 cells. When RFP-beta-COP was co-transfected with GFP-TREK1 into COS-7 cells, both proteins were found localized to the plasma membrane. In addition, the channel activity and surface expression of GFP-TREK1 increased dramatically by co-transfection with RFP-beta-COP. Surface expression of the TREK1 channel was also clearly reduced with the addition of beta-COP-specific shRNA. Collectively, these data suggest that beta-COP plays a critical role in the forward transport of TREK1 channel to the plasma membrane.

Diclofenac, a Non-steroidal Anti-inflammatory Drug, Inhibits L-type Ca2+ Channels in Neonatal Rat Ventricular Cardiomyocytes

A non-steroidal anti-inflammatory drug (NSAID) has many adverse effects including cardiovascular (CV) risk. Diclofenac among the nonselective NSAIDs has the highest CV risk such as congestive heart failure, which resulted commonly from the impaired cardiac pumping due to a disrupted excitation-contraction (E-C) coupling. We investigated the effects of diclofenac on the L-type calcium channels which are essential to the E-C coupling at the level of single ventricular myocytes isolated from neonatal rat heart, using the whole-cell voltage-clamp technique. Only diclofenac of three NSAIDs, including naproxen and ibuprofen, significantly reduced inward whole cell currents. At concentrations higher than 3 microM, diclofenac inhibited reversibly the Na(+) current and did irreversibly the L-type Ca(2+) channels-mediated inward current (IC(50)=12.89+/-0.43 microM) in a dose-dependent manner. However, nifedipine, a well-known L-type channel blocker, effectively inhibited the L-type Ca(2+) currents but not the Na(+) current. Our finding may explain that diclofenac causes the CV risk by the inhibition of L-type Ca(2+) channel, leading to the impairment of E-C coupling in cardiac myocytes.

Analysis of adverse drug reactions collected by an electronic reporting system in a single hospital

T applied anaesthetics are employed in order to eliminate pain caused by needle insertion and injection, thus ameliorating patient compliance. Furthermore, they are devoid of symptoms of superficial trauma and local reaction. Therefore, the aim of this work was to develop a new formulation of lidocaine, proposed to improve its clinical effectiveness in topical anaesthesia in terms of both enhanced anaesthesia and a prolonged duration of action. For this purpose, we incorporated lidocaine in nanostructured lipid carriers (NLC). Particle size and zeta potential measurements, Fourier transform infrared spectroscopy and Raman spectroscopy were performed to characterize the NLC system. Furthermore, DSC and XRD measurements were conducted to investigate lipid crystallization which plays a very important role in the performance of NLC carriers. Additionally, membrane diffusion and penetration studies were completed in vitro and ex vivo, followed by measurements on skin hydration and transepidermal water loss in vivo. Our results lead us to the conclusion that the developed nanostructured lipid carrier is a promising vehicle for the topical delivery of lidocaine. The penetration of the NLC formulation was remarkable through heat separated epidermis after 24 hours, and the observed skin hydrating and occlusive effect also makes this formulation a favourable dermal carrier system.Statement of the Problem: Day by day, the demand for biotherapeutics and recombinant proteins is increasing. Herein, cytoplasmic expression in prokaryotic and eukaryotic hosts has been widely accepted. However, there are several obstacles in the large-scale production of recombinant proteins. Recombinant proteins might form inclusion bodies or be degraded by proteases. Endogenous proteins might also interfere with the folding of a recombinant secretory protein. These factors, as well as the complicated downstream purification process, will result in loss of protein yield. Moreover, the yield of recombinant protein is not only related to expression levels, but also to translocation efficiency. Thus, the translocation efficiency could be increased by using signal peptides. Phenylalanine ammonialyase (PAL), involved in the first step of the phenylpropanoid pathway, catalyzes the deamination of phenylalanine to cinnamate and ammonia. PALs are ubiquitous in plants and also commonly found in fungi; however, animal lacks it. They are of special interest in several medical and industrial applications, including preparation of low phenylalanine diet, treatment of phenylketonuria and certain neoplastic tumors. Although several methods have been applied in the production of PAL, the final titers of PAL are still low, thereby impeding considerable industrialization of this enzyme.Background/Aims: The recent introduction of computerized surveillance systems has promoted the monitoring of adverse drug reactions (ADRs), a feature that facilitates voluntary reports and enables prompt feedback. To investigate the causative agents and severity of ADRs that occurred in a single hospital, we analyzed the features of 980 ADRs that occurred over 14 months after developing a computerized ADR reporting system in Hallym Sacred Heart Hospital. Methods: ADR data collected prospectively from September 2007 to October 2008 by a computerized reporting system were analyzed. The World Health Organization-Uppsala Monitoring Center (WHO-UMC) criteria were used to determinate causality for each ADR. Results: The number of ADR cases reported voluntarily increased rapidly since the introduction of the computerized ADR reporting system. Of the 980 cases, antibiotics (34.5%) were the most common causative drugs, followed by analgesics such as tramadol and its compound (15.2%), radiocontrast media (7.0%), narcotics (5.9%), and nonsteroidal anti-inflammatory drugs (NSAIDs) (5.5%). Fifty-nine (6.0%) and 206 (21.0%) cases were classified as severe and moderate reactions, respectively. The mean age was older in patients with severe ADRs than in patients with non-severe ADRs. The most common clinical features were skin manifestations, such as pruritus, skin eruptions, and urticaria. Gastrointestinal symptoms including nausea, vomiting, and diarrhea were the second most frequently reported ADRs. Among antibiotics, first-generation cephalosporins were the most frequently reported causative drugs, followed by second-generation cephalosporins, penicillin/β-lactamase inhibitors, and third-generation cephalosporins. While 11.6% of ADRs related to penicillin/β-lactamase inhibitors were classified as severe, there was only one severe ADR (1.1%) for first-generation cephalosporins. Most ADRs were reported equally in men and women, although female cases constituted aboutDietary supplement market is growing in Turkey. Local and multinational companies develop and introduce many new products for Turkish dietary supplements market. However, in marketing literature, a few academic researchers could be found regarding Turkish consumers’ behavior about dietary supplements. Understanding the awareness and utilization rates of nutritional support products is important at the point of designing strategies for producers, the state and related organizations. This general exploratory research was carried out in 60 different pharmacies located in different regions of Turkey (Mediterranean, Black Sea, Eastern Anatolia, Southeastern Anatolia, Central Anatolia Region). Face-to-face interviews were conducted with 253 people aged 18 years and over from September 2017 to February 2018 (5 months). The data collected by the questionnaire includes the factors that affect the use of nutritional support products by respondents in the study, the recognition and consumption rates, the product content and how regularly they use it. Respondents were found to use products for immunity (21.03%) at the beginning of their nutritional support products usage. Omega 3 fish oil (26.98%), multivitamins (17.86%) and CoQ10 (7.94%) were the most preferred products. The rate of natural supplements usage by individuals who thought that use of natural supplements is crucial, is around %71.43.. We believe this study will lead to more detailed research on healthy lifestyle market in the future.T aim of the present study was to establish the relation that exists between the striatal dopamine levels and urine dopamine content in hemiparkinsonism rat model. 20 Wistar rats were used and were randomized into two groups as follows: a) control group and b) lessoned injured group induced by (6-OHDA). All animals were re-tested on the same battery of motor tests that before lesion. The rotation test behavior test was assessed and striatal DA levels and urine DA were determined by HPLC, motor behavior fine tests were done and finally immunohistochemical (Hir+) striatum was done. We found a positive correlation between the dopamine levels in the striatum and the content dopamine in urine of rats (control vs. 6-OHDA group). Respect motor performance, the 6-OHDA group showed a significant fine motor impairment (grasp and advance) vs. control group (p<0.01). Immunostaining for tyrosine hydroxylase (TH) expression revealed no TH-immunoreactive (THir) neurons in any 6-OHDA animals vs. control group (p<0.01). Positive correlation between the dopamine levels in the striatum and the content dopamine in urine could be talking also, about a major proportion of urinary dopamine could be derived from the renal decarboxylation of circulating dopa and not dopaminergic system disturbance. The other hand, alterations of a forelimb motor function in rats could be only due to more vulnerability of striatal dopaminergic depletion and not to low periphery dopamine levels.Polyamidoamine (PAMAM) dendrimers as synthetic gene vectors are efficient gene delivery systems. In this study, a kind of α-cyclodextrin-PAMAM conjugates polymer (Cy D-G1) was synthesized as a gene delivery vector. Based on ~1H NMR detectation, about 6.4 PAMAM-G1 molecules was grafted onto an α-CD core. Agarose gel electrophoresis revealed that Cy D-G1 could efficiently bind with DNA to condense them into nano-scale particles, which showed a similar binding capacity of PEI-25 K. Besides, it could protect DNA from DNase I degradation in a low N/P ratio. When N/P ratio in the CyD-G1/DNA polyplex was 40, the average particle size of CyD-G1/DNA polyplex was about 120 nm, and zeta potential was +21 mV. This polyplex could maintain its particle size in serum-containing solution within 360 min. In comparison with PEI-25 K carrier, CyD-G1 showed low cytotoxicity in various cell lines. Cell transfection results showed that CyD-G1 efficiently delivered DNA into cells at N/P = 80 compared with Lipofectamine 2000 and PEI-25 K. Unlike Lipofectamine 2000 and PEI-25 K, in serum-containing test condition, CyD-G1/DNA polyplex could maintain the transgene activities. The results of confocal laser scanning microscopy indicated that most DNA entered into cell nuclei within 4 h, and this phenomenon was consistent with the results calculated by flow cytometry. Taken together, CyD-G1 showed good transgene activities and the gene delivery vector could be used not only in vitro but also in vivo.

A comparison between the efficiency of the Xpert MTB/RIF assay and nested PCR in identifying Mycobacterium tuberculosis during routine clinical practice

OBJECTIVES Polymerase chain reaction (PCR) for the detection of Mycobacterium tuberculosis (MTB) is more sensitive, specific, and rapid than the conventional methods of acid-fast bacilli (AFB) smear and culture. The aim of this study was to determine if the Xpert MTB/rifampicin (RIF) assay had additional advantages over nested PCR for the detection of MTB in a geographical area with intermediate tuberculosis (TB) incidence. METHODS Between February and December 2013, the Xpert MTB/RIF assay and MTB nested PCR, as well as AFB smear and culture, were simultaneously performed on 198 clinical samples (160 pulmonary and 38 non-pulmonary specimens) collected from 171 patients hospitalized at Hallym University Medical Center for possible TB. The accuracy of the diagnosis of MTB culture-positive TB and the turnaround time of reporting laboratory results were calculated and compared. Rifampin resistance by the Xpert MTB/RIF assay was reviewed with that of conventional drug susceptibility testing (DST). RESULTS The sensitivity, specificity, and positive and negative predictive values of the Xpert MTB/RIF assay and MTB nested PCR for diagnosis of MTB culture-positive pulmonary TB were 86.1% vs. 69.4% (P=0.1563), 97.8% vs. 94.1% (P=0.2173), 91.2% vs. 75.8% (P=0.1695), and 96.4% vs. 92.0% (P=0.2032), respectively. The median turnaround times of the Xpert MTB/RIF assay and MTB nested PCR were 0 [0-4] days and 4 [1-11] days, respectively (P<0.001). Two cases of rifampin resistance, as determined by the Xpert MTB/RIF assay, were found to be multi-drug resistant (MDR) pulmonary TB by DST. CONCLUSIONS The Xpert MTB/RIF assay seemed to be sensitive, specific, and comparable to nested PCR for identifying MTB among clinically suspected TB patients, and the assay can be valuable in giving a timely identification of resistance to rifampin.

A Novel Cytosolic Isoform of Mitochondrial Trans-2-Enoyl-CoA Reductase Enhances Peroxisome Proliferator-Activated Receptor α Activity.

Background Mitochondrial trans-2-enoyl-CoA reductase (MECR) is involved in mitochondrial synthesis of fatty acids and is highly expressed in mitochondria. MECR is also known as nuclear receptor binding factor-1, which was originally reported with yeast two-hybrid screening as a binding protein of the nuclear hormone receptor peroxisome proliferator-activated receptor α (PPARα). However, MECR and PPARα are localized at different compartment, mitochondria, and the nucleus, respectively. Therefore, the presence of a cytosolic or nuclear isoform of MECR is necessary for functional interaction between MECR and PPARα. Methods To identify the expression pattern of MECR and the cytosolic form of MECR (cMECR), we performed reverse transcription polymerase chain reaction (RT-PCR) with various tissue samples from Sprague-Dawley rats. To confirm the interaction between cMECR and PPARα, we performed several binding assays such as yeast two-hybrid, coimmunoprecipitation, and bimolecular fluorescence complementation. To observe subcellular localization of these proteins, immunocytochemistry was performed. A luciferase assay was used to measure PPARα activity. Results We provide evidence of an alternatively spliced variant of the rat MECR gene that yields cMECR. The cMECR lacks the N-terminal 76 amino acids of MECR and shows uniform distribution in the cytoplasm and nucleus of HeLa cells. cMECR directly bound PPARα in the nucleus and increased PPARα-dependent luciferase activity in HeLa cells. Conclusion We found the cytosolic form of MECR (cMECR) was expressed in the cytosolic and/or nuclear region, directly binds with PPARα, and enhances PPARα activity.

PEBP1, a RAF kinase inhibitory protein, negatively regulates starvation-induced autophagy by direct interaction with LC3.

ABSTRACT Autophagy plays a critical role in maintaining cell homeostasis in response to various stressors through protein conjugation and activation of lysosome-dependent degradation. MAP1LC3B/LC3B (microtubule- associated protein 1 light chain 3 β) is conjugated with phosphatidylethanolamine (PE) in the membranes and regulates initiation of autophagy through interaction with many autophagy-related proteins possessing an LC3-interacting region (LIR) motif, which is composed of 2 hydrophobic amino acids (tryptophan and leucine) separated by 2 non-conserved amino acids (WXXL). In this study, we identified a new putative LIR motif in PEBP1/RKIP (phosphatidylethanolamine binding protein 1) that was originally isolated as a PE-binding protein and also a cellular inhibitor of MAPK/ERK signaling. PEBP1 was specifically bound to PE-unconjugated LC3 in cells, and mutation (WXXL mutated to AXXA) of this LIR motif disrupted its interaction with LC3 proteins. Interestingly, overexpression of PEBP1 significantly inhibited starvation-induced autophagy by activating the AKT and MTORC1 (mechanistic target of rapamycin [serine/threonine kinase] complex 1) signaling pathway and consequently suppressing the ULK1 (unc-51 like autophagy activating kinase 1) activity. In contrast, ablation of PEBP1 expression dramatically promoted the autophagic process under starvation conditions. Furthermore, PEBP1 lacking the LIR motif highly stimulated starvation-induced autophagy through the AKT-MTORC1-dependent pathway. PEBP1 phosphorylation at Ser153 caused dissociation of LC3 from the PEBP1-LC3 complex for autophagy induction. PEBP1-dependent suppression of autophagy was not associated with the MAPK pathway. These findings suggest that PEBP1 can act as a negative mediator in autophagy through stimulation of the AKT-MTORC1 pathway and direct interaction with LC3.

Identification and characterization of a truncated isoform of NELL2

NELL2 is a neuron-specific secreted glycoprotein containing an N-terminal thrombospondin I-like domain (TSP-N). In this study, we describe NELL2-Tsp, a novel alternative splice variant of rat NELL2. NELL2-Tsp uses an alternate stop codon resulting in a C-terminal truncated form of NELL2, containing a signal peptide and a TSP-N domain. NELL2-Tsp is a glycosylated protein specifically expressed in brain tissue. NELL2-Tsp and NELL2 are secreted, likely due to the putative signal peptide. However, due to the truncation, the secreted portion of NELL2-Tsp is smaller than that of NELL2. Immunoprecipitation analysis confirmed that NELL2-Tsp was able to associate with NELL2 and with itself. In addition, expression of NELL2-Tsp notably reduced secretion of NELL2 and inhibited NELL2-mediated neurite outgrowth. These results suggest that NELL2-Tsp may act as a negative regulator of wild-type NELL2.

Pulmonary function assessment in the early phase of patients with smoke inhalation injury from fire

OBJECTIVES Fire smoke contains toxic gases and numerous chemical compounds produced by incomplete combustion, and may cause injury to the airways. Increased airway reactivity, as well as a decrease in lung function, has been reported as a sequela of smoke inhalation injury. This study was undertaken to assess lung functions in the early phase of patients with smoke inhalation damage from fires. METHODS A total of 15 patients with fire smoke inhalation (fire smoke group) and 15 subjects with chronic cough but no previous history of lung disease (chronic cough group) were enrolled. For diagnosis of inhalation injury, we performed bronchoscopy, high-resolution computed tomography (HRCT), as well as arterial carboxyhemoglobin (COHb) at admission. Clinical characteristics, pulmonary function tests (PFTs) and mannitol bronchial provocation tests (BPTs) were analyzed and compared between the two groups. RESULTS In fire smoke group, initial COHb levels and the PaO2/FiO2 ratio were (14.8±18.49)% and 425.7±123.68, respectively. Of seven patients performing HRCT, 4 (57.1%) showed the CT findings compatible with lung involvement of inhalation injury. Post bronchodilator value of the percent of forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) were (76.0±24.27)% and (79.8±27.82)%, respectively. Pre-and post- bronchodilator forced expiratory flow between 25% and 75% of the FVC (FEF25-75) and the percent predicted FEF25-75 were 2.41±1.47 vs. 2.65±1.45 L (P=0.045), and (68.7±37.29)% vs. (76.4±36.70)% (P=0.031), respectively. Two patients (13.3%) had positive bronchodilator response (BDR). In fire smoke and chronic cough group, all the subjects showed mannitol BPTs within normal limits. CONCLUSIONS Fire smoke inhalation leads to mild obstructive small airway disease pattern of pulmonary function in the early phase of patients with fire smoke damage. Further studies, however, need to be followed to identify the relationship between airway narrowing to inhaled mannitol and smoke inhalation injury.