Effect of Microstructural Constituents on Hydrogen Embrittlement Resistance of API X60, X70, and X80 Pipeline Steels

This study describes how microstructural constituents affected the hydrogen embrittlement resistance of high-strength pipeline steels. The American Petroleum Institute (API) X60, X70, and X80 pipeline steels demonstrated complicated microstructure comprising polygonal ferrite (PF), acicular ferrite, granular bainite (GB), bainitic ferrite (BF), and secondary phases, e.g., the martensite-austenite (MA) constituent, and the volume fraction of the microstructures was dependent on alloying elements and processing conditions. To evaluate the hydrogen embrittlement resistance, a slow strain rate test (SSRT) was performed after electrochemical hydrogen charging. The SSRT results indicated that the X80 steel with the highest volume fraction of the MA constituent demonstrated relatively high yield strength but exhibited the lowest hydrogen embrittlement resistance because the MA constituent acted as a reversible hydrogen trap site

Gateway RFP-fusion vectors for high-throughput functional analysis of genes

There is an increasing demand for high throughput (HTP) methods for gene analysis on a genome-wide scale. However, the current repertoire of HTP detection methodologies allows only a limited range of cellular phenotypes to be studied. We have constructed two HTP-optimized expression vectors generated from the red fluorescent reporter protein (RFP) gene. These vectors produce RFP-tagged target proteins in a multiple expression system using gateway cloning technology (GCT). The RFP tag was fused with the cloned genes, thereby allowing us localize the expressed proteins in mammalian cells. The effectiveness of the vectors was evaluated using an HTP-screening system. Sixty representative human C2 domains were tagged with RFP and overexpressed in HiB5 neuronal progenitor cells, and we studied in detail two C2 domains that promoted the neuronal differentiation of HiB5 cells. Our results show that the two vectors developed in this study are useful for functional gene analysis using an HTP-screening system on a genome-wide scale.We appreciate the helpful advice of Dr. Tobias Meyer and Dr. Won Do Heo of Stanford University in the construction of the set of entry clones of human C2 domains. This work was supported by a grant from the Basic Research Program of the Korea Science and Engineering Foundation (R01-2002- 000-00128-0), and a Korea Research Foundation Grant (KRF- 2006-005-J04204)

Saussurea lappa induces G2-growth arrest and apoptosis in AGS gastric cancer cells

The molecular effects of Saussurea lappa extracts, a traditional medicine in Eastern Asia, on the fate of gastric carcinoma have not been understood. In this study, its cytostatic effects were examined using gastric AGS cancer cells. Its treatment resulted in apoptosis and G2-arrest in a dose- and time-dependent manner. The effects were attributed to the regulation of cyclins and pro-apoptotic molecules and suppression of anti-apoptotic molecules. Therefore, these results suggest that extracts of S. lappa root may be a candidate to deal with gastric cancers either by traditional herbal therapy or by combinational therapy with conventional chemotherapy

Ab initio study of thallium nanoclusters on Si(111)-7x7

We have studied the stability of a thallium nanocluster of various numbers of atoms (N=1,2,...,10) on a Si(111)-7x7 substrate using density functional theory total energy calculations. We have compared it with clusters of other group III elements (Al, Ga, and In). Thallium is found to be unstable with the triangular cluster, which has been known to be stable for other group III elements. Instead, a slightly different structure, in which Si atop atoms are lower than thallium atoms in height by 2.56 angstrom, was found to be quite stable. Such an abnormal structure originates from the inert pair of 6s(2) electrons due to the significant spin-orbit interaction. The initial relaxed N=6 Tl cluster continues to grow with increasing N up to N=9 in the faulted-half unit cell, which is consistent with experimental observationsclose121

Long-term follow-up of Fanconi anemia: clinical manifestation and treatment outcome

PurposeThe aim of this study was to characterize Korean patients with Fanconi anemia (FA), which is a rare but very challenging genetic disease.MethodsThe medical records of 12 FA patients diagnosed at Chonnam National University Hospital from 1991 to 2012 were retrospectively reviewed.ResultsThe median age at diagnosis was 6.2 years. All patients showed evidence of marrow failure and one or more physical stigmata. Chromosome breakage tests were positive in 9 out of 11 available patients. The median follow-up duration was 69.5 months. The Kaplan-Meier (KM) survival of all patients was 83.3% at 10 years and 34.7% at 20 years, respectively. Seven patients underwent 9 stem cell transplantations (SCTs). Among them, 5 were alive by the end of the study. Ten-year KM survival after SCT was 71.4% with a median follow-up of 3.4 years. All 5 patients treated with supportive treatment alone died of infection or progression at the median age of 13.5 years, except for one with short follow-up duration. Acute leukemia developed in 2 patients at 15.4 and 18.1 years of age. Among 6 patients who are still alive, 3 had short stature and 1 developed insulin-dependent diabetes mellitus.ConclusionWe provide information on the long-term outcomes of FA patients in Korea. A nation-wide FA registry that includes information of the genotypes of Korean patients is required to further characterize ethnic differences and provide the best standard of care for FA patients

Surgical Results of Endoscopic Dacryocystorhinostomy and Lacrimal Trephination in Distal or Common Canalicular Obstruction

ObjectivesTo evaluate the surgical outcomes of endoscopic dacryocystorhinostomy followed by canalicular trephination and silicone stenting in patients with distal or common canalicular obstructions.MethodsThe medical records of 29 patients (31 eyes) from January 2001 to December 2009 who underwent endoscopic dacryocystorhinostomy followed by canalicular trephination and silicone tube insertion for the treatment of distal or common canalicular obstructions were retrospectively reviewed. The level of obstruction was confirmed by intraoperative probing. The outcome of the surgery was categorized as a complete success, partial success, or failure according to the functional and anatomic patency.ResultsThe average age of the patients was 52 years. The duration of silicone intubation ranged from 4 to 11 months with an average of 5.7±1.6 months. The follow-up period after stent removal ranged from 4 to 15 months with an average of 8.2±3.3 months. Complete success was achieved in 25 out of 31 eyes (80.6%), partial success in 4 out of 31 eyes (12.9%), and failure in 2 out of 31 eyes (6.5%).ConclusionEndoscopic dacryocystorhinostomy followed by canalicular trephination and silicone stent intubation may be safe and considered as an initial treatment of patients with distal or common canalicular obstructions

Transtorming Growth Factor β1 Induces Epithelial-to-Mesenchymal Transition of A549 Cells

Idiopathic pulmonary fibrosis (IPF) comprises an aggregate of mesenchymal cells. However, the cellular origin of these mesenchymal phenotypes remains unclear. Transforming growth factor β1 (TGF-β1) has been known as the main cytokine involved in the pathogenesis of IPF. We examined whether the potent fibrogenic cytokine TGF-β1 could induce the epithelial-to-mesenchymal transition (EMT) in the human alveolar epithelial cell line, A549, and determined whether snail expression is associated with the phenotypic changes observed in the A549 cells. EMT was investigated with cells morphology changes under phase-contrast microscopy, western blotting, and indirect immunofluorescence stains. E-cadherin and transcription factor, snail, were also evaluated by measuring mRNA levels using reverse transcriptase-polymerase chain rection (RT-PCR) analysis. The data showed that TGF-β1 induced A549 cells with epithelial cell characteristics to undergo EMT in a concentration-dependent manner. Following TGF-β1 treatment, A549 cells induced EMT characterized by cells morphological changes, loss of epithelial markers E-caherin and cytokeratin, increased stress fiber reorganization by F-actin, and cytokeratin replacement by vimentin. Although IL-1β failed to induce A549 cells to undergo EMT, the combination of TGF-β1 and IL-1β showed synergy effects in cells morphology changes and the expression of mesenchymal markers. The snail expression study using RT-PCR analysis provided that loss of E-cadherin expression was associated with snail expression. Stimulation of A54 cells with TGF-β1 plus IL-1β revealed a higher level of snail expression. Our data showed that EMT of A549 cells might be closely associated with snail expression