Search

Chan Ho Lee, Eun Kyung Goag, Su Hwan Lee, Kyung Soo Chung, Ji Ye Jung, Moo Suk Park, Young Sam Kim, Se Kyu Kim, Joon Chang, Joo Han Song Division of Pulmonology and Critical Care Medicine, Department of Internal Medicine, Institute of Chest Disease, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea Background: Iron-catalyzed oxidative stress contributes to lung injury after exposure to various toxins, including cigarette smoke. An oxidant/antioxidant imbalance is considered to play a critical role in the pathogenesis of COPD. Ferritin is a key protein in iron homeostasis, and its capacity to oxidize and sequester the metal preventing iron prooxidant activity implicates its possible role in the alteration of antioxidant imbalance. We investigated the relationship among cigarette smoking, lung function, and serum ferritin concentration in a large cohort representative of the Korean adult population. Materials and methods: Among 50,405 participants of the Korean National Health and Nutrition Examination Survey from 2010 to 2014, 15,239 adult subjects older than 40years with serum ferritin levels and spirometric data were selected for this study. Results: The mean age was 56.5years for men (43%) and 56.9years for women (57%). The prevalence of airway obstruction was 13.4%, which was significantly higher in men than in women, and increased in former or current smokers. The median levels of serum ferritin were highest in the airway obstruction group, followed by the restrictive pattern group, and lowest in the normal lung function group. The median ferritin levels were increased by smoking status and amounts in each spirometric subgroup. In multivariable regression analysis, serum ferritin was positively associated with forced expiratory volume in 1second and forced expiratory volume in 1second/forced vital capacity, whereas the smoking amount was negatively associated with the adjustment with age, sex, height, and weight. Conclusion: Serum ferritin levels were increased in former or current smokers and were increased with smoking amount in all subgroups of participants categorized according to spirometric results. The result was also evident in the subgroups divided by obstructive severity. While smoking amount was inversely related to lung function, higher levels of serum ferritin were associated with enhanced spirometric results in a representative sample of the general Korean adult population. Future prospective studies will be needed to clarify the causality between serum ferritin and lung functions and their role in COPD morbidity. Keywords: airway obstruction, ferritin, smoking

PURPOSE Acute kidney injury (AKI) is common in critically ill patients. Serum cystatin C has emerged as a reliable marker of AKI. We sought to assess the value of serum cystatin C for early detection and prediction of renal function recovery in patients with sepsis. MATERIALS AND METHODS Sepsis patients (113 AKI patients and 49 non-AKI patients) admitted to the intensive care unit (ICU) were included. Serum creatinine and cystatin C levels and glomerular filtration rate were measured on days 0, 1, 3, and 7. RESULTS Serum cystatin C levels were significantly higher in AKI patients than in non-AKI patients at all time points. Multivariate analysis showed that only serum cystatin C levels on day 0 were associated with AKI development [odds ratio (OR)=19.30; 95% confidence interval (CI)= 2.58-144.50, p

Background Cardiac surgery with cardiopulmonary bypass (CPB) is a known risk factor for acute respiratory distress syndrome (ARDS). We aimed to analyze the treatment outcome in patients who required veno-venous extracorporeal membrane oxygenation (VV-ECMO) for postcardiotomy ARDS despite other rescue modalities. Methods We retrospectively reviewed the outcomes in 13 patients (mean age, 54.7±5.9 years) who received VV-ECMO support for refractory ARDS after cardiac surgery between March 2013 and February 2016 at Severance Hospital, Yonsei University (Seoul, Korea). Results At the start of VV-ECMO, the average lung injury score was 3.0±0.2, and the Respiratory Extracorporeal Membrane Oxygenation Survival Prediction (RESP) score was -4±1.1. Although 7 patients initiated VV-ECMO support within 24 h from operation, the remaining 6 started at a median of 8.5 days (range, 5-16 days). Nine (69.3%) patients were successfully weaned from VV-ECMO. After a median follow-up duration of 14.5 months (range, 1.0-33.0 months) for survivors, the 1-year overall survival was 58.6%±14.4%. The differences in the overall survival from VV-ECMO according to the RESP score risk classes were borderline significant (100% in class III, 50%±25% in class IV, and 20%±17.9% in class V; P=0.088). Conclusions VV-ECMO support can be a feasible rescue strategy for adult patients who develop refractory ARDS after a cardiac surgery. Additionally, the RESP score seems a valuable prognostic tool for post-ECMO survival outcome in this patient population as well.

Objectives Disruption in the stability of respiratory microbiota is known to be associated with many chronic respiratory diseases. However, only few studies have examined microbiomes in lung cancer. Therefore, we characterized and compared the microbiomes of patients with lung cancer and those with benign mass-like lesions. Materials and methods Bronchoalveolar fluid was collected prospectively to evaluate lung masses in patients who had undergone bronchoscopies from May to September 2015. Twenty-eight patients (20 male, 8 female) were enrolled: 20 diagnosed with lung cancer and 8 diagnosed with benign diseases. Samples were analysed by 16S rRNA-based next-generation sequencing. Results The participants’ mean age was 64 ± 11 years. Bacterial operational taxonomic units were classified into 26 phyla, 44 classes, 81 orders, 153 families, 288 genera, and 797 species. The relative abundance of two phyla (Firmicutes and TM7) was significantly increased in patients with lung cancer (p = 0.037 and 0.035, respectively). Furthermore, two genera (Veillonella and Megasphaera) were relatively more abundant in lung cancer patients (p = 0.003 and 0.022, respectively). The area under the curve of a combination of these two genera used to predict lung cancer was 0.888 (sensitivity = 95.0%, specificity = 75.0% and sensitivity = 70.0%, specificity = 100.0%; p = 0.002). Conclusion The results indicate that differences exist in the bacterial communities of patients with lung cancer and those with benign mass-like lesions. The genera Veillonella and Megasphaera showed the potential to serve as biomarkers to predict lung cancer. Thus, the lung microbiota may change the environment in patients with lung cancer.

Mobility management, which includes location management and handoff management, is essential in cellular wireless networks to provide service to mobile users. Location management enables call delivery to mobile users, while handoff management maintains the connectivity of ongoing calls while users move between cells. In next generation networks, mobile users will avail themselves with terminals capable of accessing wireless networks employing multiple technologies, thus making the task of mobility management more challenging. This paper reviews recent developments in location management, and surveys methods for handoff management between heterogeneous systems. Methods for inter-system handoffs in packet-switched inter-networks are discussed according to the protocol layer in which the handoffs take place, i.e., network layer, transport layer, and application layer. Open problems for mobility management in future wireless networks are also presented. Copyright © 2010 John Wiley & Sons, Ltd.

Purpose Post-operative pulmonary function is an important prognostic factor for lung transplantation. The purpose of this study was to identify factors affecting recovery of forced expiratory volume in 1 second (FEV1) at the first year after lung transplantation. Materials and Methods We retrospectively reviewed the medical records of lung transplantation patients between October 2012 and June 2016. Patients who survived for longer than one year and who underwent pulmonary function test at the first year of lung transplantation were enrolled. Patients were divided into two groups according to whether they recovered to a normal range of FEV1 (FEV1 ≥80% of predicted value vs.

A membrane electrode assembly (MEA) based on a Nafion 115 membrane shows a 29% loss in power density after continuous testing in a single direct methanol fuel cell for 1000 h at 50 °C. One of the main reasons for this behaviour is a deterioration of the membrane, namely, its ion-exchange capacity is reduced by 17%. The thermal decomposition behaviour of an untested and degraded membrane is studied by evolved gas analysis-mass spectrometry, pyrolysis-gas chromatography–mass spectrometry, thermo-gravimetric analysis, differential scanning calorimetry, and in situ FTIR reflectance absorption spectra. The results reveal a decrease in thermal stability of the degraded membrane. The Nafion 115 membrane is suggested to lose ion-exchange capacity after the sulfonic acid group is transformed to a thermally less-stable group, such as the persulfonic acid –SO2OOH group during MEA operation. The structural changes may prevent the formation of ionic clusters.

The IEEE 802.15.4 low rate wireless personal area network is a protocol suitable for wireless sensor networks. There has been growing interest in the IEEE 802.15.4 protocol in the home automation networks. This paper proposes a scheduling scheme obtaining optimal parameters regarding the IEEE 802.15.4 frame and subframes in the home automation networks. Guaranteed time slots (GTS) are exploited for the delivery of home automation traffic. Given a set of the requirements for bandwidths and periods assigned to nodes in the network, the beacon interval and the active/inactive subframe duration satisfying the requirements are selected considering the low duty cycle by the proposed scheme. Based on these parameters, analytic results provide the way to efficient use of network resources including energy.

AIM: To examine incidence of tuberculosis (TB) in gastrectomy patients and investigate the risk factors for developing TB after gastrectomy in patients with gastric cancer. METHODS: A retrospective cohort study of gastrectomy patients with gastric cancer was performed at a university-affiliated hospital in Seoul, South Korea between January 2007 and December 2009. We reviewed patient medical records and collected data associated with the risk of TB, surgery, and gastric cancer. Standardized incidence ratios (SIRs) of TB were calculated to compare the incidence of TB in gastrectomy patients with that in the general Korean population, and risk factors for TB after gastrectomies were analyzed. RESULTS: Among the 1776 gastrectomy patients, 0.9% (16/1776) developed post-gastrectomy TB, with an incidence of 223.7 cases per 100000 patients per year. The overall incidence of TB in gastrectomy patients, adjusted by sex and age, was significantly higher than that in the general population (SIR = 2.22, 95%CI: 1.27-3.60). Previous TB infection [odds ratio (OR) = 7.1, P < 0.001], lower body mass index (BMI) (kg/m2; OR = 1.21, P = 0.043) and gastrectomy extent (total gastrectomy vs subtotal gastrectomy) (OR = 3.48, P = 0.017) were significant risk factors for TB after gastrectomy in a multivariate analysis. CONCLUSION: TB incidence after gastrectomy is higher than that in the general population. Previous TB infection, lower BMI, and total gastrectomy are risk factors for TB after gastrectomy in patients with gastric cancer.

A new method to analyze deteriorated direct methanol fuel cells (DMFCs) by combining electrochemical impedance analysis and physicochemical investigations is proposed. To make a comparison, one pristine membrane electrode assembly (MEA) and one deteriorated MEA, following 1000 h of continuous operation, were prepared. A unique impedance analysis enabled the separation of the impedance values for the cathode and the anode, and it was possible to determine that the deterioration of the MEA mainly came from the deterioration of the cathode. Several physicochemical investigations were made to show the relationship between the electrochemical properties and the deterioration of the MEA.

In this paper, we consider a mobile ad hoc wireless access network in which mobile nodes can access the Internet via one or more stationary gateway nodes. Mobile nodes outside the transmission range of the gateway can continue to communicate with the gateway via their neighboring nodes over multihop paths. On-demand routing schemes are appealing because of their low routing overhead in bandwidth restricted mobile ad hoc networks, however, their routing control overhead increases exponentially with node density in a given geographic area. To control the overhead of on-demand routing without sacrificing performance, we present a novel extension of the ad hoc on-demand distance vector (AODV) routing protocol, called LB-AODV, which incorporates the concept of load-balancing (LB). Simulation results show that as traffic increases, our proposed LB-AODV routing protocol has a significantly higher packet delivery fraction, a lower end-to-end delay and a reduced routing overhead when compared with both AODV and gossip-based routing protocols.

This study investigated the effects of salt in a SynChropak column using peptides which are structurally simpler than proteins. Contrary to the established explanation of salt type by molal surface tension increment, the study attempted to explain salt effects by two retention parameters, S and log kw. S was considered to be related to surface tension effect, log kw to salting in effect. From the dependence of S and log kw on temperature and the stationary phase ligand type, these parameters turned out to be useful in explaining the characteristics of hydrophobic interaction chromatography (HIC) which are different from those of reversed phase chromatography (RPC). We examined enthalpy-entropy compensation because of the similar tendency of enthalpic and entropic values in the retention process. The uses and characteristics of five different salts were also discussed.

To investigate immunity-related guanosine triphosphatase family M (IRGM) genetic variants associated with susceptibility to tuberculosis (TB) in a Korean population.We conducted a prospective case-control study including 193 patients with active TB in Severance Hospital and 230 age- and sex-matched unrelated controls registered in Yonsei Cardiovascular Genome Center. Based on associations with other chronic inflammatory conditions, we analyzed the allele and genotype frequencies of rs72553867, rs10065172, and rs12654043 among patients with TB and healthy controls.The T allele of rs10065172 was significantly associated with protection against developing TB based on allele frequency [P = 0.042; odds ratio (OR) 0.75] and genotype distribution in the codominant model (P = 0.036; OR 0.73).This is the first study to identify a significant association between the IRGM single-nucleotide polymorphism (SNP) rs10065172 and susceptibility to active TB disease in an Asian population. The results suggest that IRGM genetic variants could be associated with susceptibility to active TB disease in the Korean population.

In this paper, we examine one of the security issues in vehicular ad-hoc network (VANETs): position-spoofing attack. We propose a novel Secure Location Verification (SLV) scheme to detect and prevent position-spoofing attack. SLV uses distance bounding, plausibility checks, and ellipse-based location estimation to verify the claimed location of a vehicle. Simulation results show that our proposed SLV scheme has a better performance than both autonomous position verification (APV) and greedy forwarding algorithms.

Wireless ad-hoc networks can experience significant performance degradation under fading channels. Spatial diversity has been shown to be an effective way of combating wireless fading with the multiple-input multiple-output (MIMO) technique by transmitting correlated information through multiple antennas. The virtual MIMO technique, which allows multiple wireless stations with single antenna to form a virtual transmission array, is shown to be a viable solution from several recent studies. In this paper, we propose a complete system framework for wireless ad-hoc networks utilizing two different cooperative relaying techniques at the physical layer: the repetition coding and the space-time coding. In the data link layer, two medium access control protocols are proposed to accommodate the corresponding physical layer cooperative diversity schemes. In the network layer, diversity-aware routing protocols are proposed to determine the routing path and the relaying topology. Simulations with both constant bit rate and TCP (transmission control protocol) traffic show significant performance gains of the proposed cooperative relaying schemes.

In large and dense mobile ad hoc networks, position-based routing protocols can offer significant performance improvement over topology-based routing protocols by using location information to make forwarding decisions. However, so far security issues in position-based routing protocols has not been widely considered. In this paper, we identify several security problems of position-based routing protocols in mobile ad hoc networks. To avoid these problems, we propose the Secure Grid Location Service (SGLS), which enhances the original GLS protocol with secure features. Countermeasures employed by SGLS against feasible attacks use both a broadcast authentication protocol and a reputation system for monitoring. Simulation results showed that SGLS can detect and isolate message dropping attackers efficiently.

In this paper, we consider a mobile ad-hoc wireless access network in which mobile nodes can access the Internet via a stationary gateway node or access point. Mobile nodes that are outside the transmission range of the gateway can continue to communicate with the gateway via a multi-hop connection with their neighboring nodes. The ad-hoc on-demand distance vector (AODV) routing protocol is extended by incorporating the concept of load-balancing (LB). We call this the LB-AODV routing protocol. Simulation results show that in a congested network environment, our proposed LB-AODV has a higher packet delivery fraction, a lower end-to-end delay and control overhead when compared with both AODV and gossip-based routing protocols.

Multimedia synchronization is one of the key issues to be resolved in order to provide a good quality of multimedia related services, such as video on demand (VoD) and lecture on demand (LoD). The authors introduce the Adaptive Buffer-Level Synchronization Algorithm, which is modeled and analyzed by ExSpect, a Petri net based simulation tool. In the suggested algorithm, the audio and video buffers are divided to 5 different levels, and the pre-defined play-out speed controller tries to make the buffer level normal in different temporal relations between multimedia streams. The suggested algorithm is able to handle and support various communication restrictions between providers and users, and offers little jitter play-out to many users in networks having limited transmission capability. The performance of the developed algorithm is analyzed in various network conditions using a Petri net simulation tool. Some important aspects of simulation results compared to other approaches are also presented.

연구배경: 암세포는 빠른 증식 속도로 인하여 상대적인 저산소증에 노출되면서 비정상적인 종양 혈관을 형성하여 치명적인 병인을 형성한다. EGCG는 녹차의 추출물로 간세포암주 및 전립선암주에서 HIF-1α의 발현을 억제하는 것으로 알려져 있다. 그러나 EGCG의 비혈관 증식성 효과에 대해서는 아직 정확히 규명되어 있지 않다. 본 연구에서는 EGCG가 비소세포폐암주에서 HIF-1α 및 VEGF의 발현에 대한 억제 가능성을 확인하여 보고자 하였다. 방법: 비소세포폐암주인 A549를 RPMI배지에서 계대 배양하였다. 저산소 유사 상태는 Modular Incubator Chamber(MIC-101)을 이용하였고 5% 이산화탄소와 95% 질소 혼합 가스를 5분 동안 공급하여 저산소 상태를 만들었으며 세포 배양액을 채취하여 혈액가스분석기(Blood Gas Analyzer ABL725)로 세포 배양 상태를 측정하였다. 세포의 증식 상태는 MTT 방법을 실시하였다. EGCG는 0, 12.5, 25, 50,100 μmol/L로 농도 변화를 주어 실험을 시행하였으며 16시간 동안 저산소 상태를 만든 뒤 HIF-1α, VEGF, β-actin mRNA에 대해 Real time PCR을 시행하였다. 결과: 48시간과 72시간에서 저산소 상태에 놓인 A549 세포의 증식능력은 대조군에 비하여 억제되었다. EGCG는 저산소화에 의해 유도된 HIF-1α의 mRNA의 전사를 유의하게 억제하였다. 그러나 이러한 억제 효과는 VRGF mRNA 발현에는 미치지 못하였다. 결론: EGCG는 HIF-1α의 발현을 억제함으로써 비소 세포암주에서의 예방적 항암요법이나 항암 치료요법 시의 주요 작용 목표로 사용될 수 있을 것으로 보인다.