• Mass Spectrometry Letters
• /
• v.5 no.1
• /
• pp.1-11
• /
• 2014

Lipids play important roles in biological systems; they store energy, play a structural role in the cell membrane, and are involved in cell growth, signal transduction, and apoptosis. Phospholipids (PLs) in particular have received attention in the medical and lipidomics research fields because of their involvement in human diseases such as diabetes, obesity, atherosclerosis, and many cancers associated with lipid metabolic disorders. Here I review experimental strategies for PL analysis based on nanoflow liquid chromatography-electrospray ionization-tandem mass spectrometry (nLC-ESI-MSn). In particular, discussed are lipid extraction methods, nanoflow LC separation of PLs, effect of ionization modifiers on the ESI of PLs, influence of chain lengths and unsaturation degree of acyl chains of PLs on MS intensity, structural determination of the molecular structure of PLs and their oxidized products, and quantitative profiling of PLs from biological samples such as tissue, urine, and plasma in relation to cancer and coronary artery disease.

• Translational and Clinical Pharmacology
• /
• v.25 no.2
• /
• pp.67-73
• /
• 2017

Glimepiride, a third generation sulfonylurea, is an antihyperglycemic agent widely used to treat type 2 diabetes mellitus. In this study, an untargeted urinary metabolomic analysis was performed to identify endogenous metabolites affected by glimepiride administration. Urine samples of twelve healthy male volunteers were collected before and after administration of 2 mg glimepiride. These samples were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and then subjected to multivariate data analysis including principal component analysis and orthogonal partial least squares discriminant analysis. Through this metabolomic profiling, we identified several endogenous metabolites such as adenosine 3', 5'-cyclic monophosphate (cAMP), quercetin, tyramine, and urocanic acid, which exhibit significant metabolomic changes between pre- and posturine samples. Among these, cAMP, which is known to be related to insulin secretion, was the most significantly altered metabolite following glimepiride administration. In addition, the pathway analysis showed that purine, tyrosine, and histidine metabolism was affected by pharmacological responses to glimepiride. Together, the results suggest that the pharmacometabolomic approach, based on LC-MS/MS, is useful in understanding the alterations in biochemical pathways associated with glimepiride action.

• Journal of Microbiology and Biotechnology
• /
• v.24 no.5
• /
• pp.714-718
• /
• 2014

Apoptosis is the process of programmed cell death executed by specific proteases, the caspases, which mediate the cleavage of various vital proteins. Elucidating the consequences of this endoproteolytic cleavage is crucial to understanding cell death and other related biological processes. Although a number of possible roles for caspase-6 have been proposed, the identities and functions of proteins that interact with caspase-6 remain uncertain. In this study, we established a cell line expressing tandem affinity purification (TAP)-tagged caspase- 6 and then used LC-MS/MS proteomic analysis to analyze the caspase-6 interactome. Eight candidate caspase-6-interacting proteins were identified. Of these, five proteins (hnRNP-M, DHX38, ASPP2, MTA2, and UACA) were subsequently examined by co-immunoprecipitation for interactions with caspase-6. Thus, we identified two novel members of the caspase-6 interactome: hnRNP-M and MTA2.

• Journal of Ginseng Research
• /
• v.43 no.1
• /
• pp.86-94
• /
• 2019

Background: Ginseng is believed to have antitumor activity. Autophagy is largely a prosurvival cellular process that is activated in response to cellular stressors, including cytotoxic chemotherapy; therefore, agents that inhibit autophagy can be used as chemosensitizers in cancer treatment. We examined the ability of Korean Red Ginseng extract (RGE) to prevent autophagic flux and to make hepatocellular carcinoma (HCC) cells become more sensitive to doxorubicin. Methods: The cytotoxic effects of total RGE or its saponin fraction (RGS) on HCC cells were examined by the lactate dehydrogenase assay in a dose- or time-dependent manner. The effect of RGE or RGS on autophagy was measured by analyzing microtubule-associated protein 1A/1B-light chain (LC)3-II expression and LC3 puncta formation in HCC cells. Late-stage autophagy suppression was tested using tandem-labeled green fluorescent protein (GFP)-monomeric red fluorescent protein (mRFP)-LC3. Results: RGE markedly increased the amount of LC3-II, but green and red puncta in tandem-labeled GFP-mRFP-LC3 remained colocalized over time, indicating that RGE inhibited autophagy at a late stage. Suppression of autophagy through knockdown of key ATG genes increased doxorubicin-induced cell death, suggesting that autophagy induced by doxorubicin has a protective function in HCC. Finally, RGE and RGS markedly sensitized HCC cells, (but not normal liver cells), to doxorubicin-induced cell death. Conclusion: Our data suggest that inhibition of late-stage autophagic flux by RGE is important for its potentiation of doxorubicin-induced cancer cell death. Therapy combining RGE with doxorubicin could serve as an effective strategy in the treatment of HCC.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.11a
• /
• pp.278-280
• /
• 2007

a-Si:H/${\mu}$c-Si:H 적층형 태양전지의 효율향상을 위해 상부전지와 하부전지간의 접합특성은 매우 중요하다. 본 연구에서는, 접합특성을 향상하기 위하여 아몰퍼스 보다 전도도가 높은 마이크로화된 n층 또는 ZnO:Al을 중간층으로 삽입한 태양전지를 제조하였으며, 그 특성을 전기적, 광학적 방법으로 분석하였다. 전기적 특성에서, 상부전지 n층에 아몰퍼스를 적용한 태양전지의 경우, 상부전지와 하부전지 간의 직렬저항이 $500{\Omega}-cm^2$ 이상으로 높게 측정되었고, 이에 따라 AM 1.5 상태의 I-V 특성에서 비틀림 현상이 발생하여 곡선인자(Fill Factor : FF)가 낮게 측정되었다. 이에 반하여, 상부전지 n층에 마이크로층을 적용하거나, ZnO:Al 중간층을 삽입한 시편의 경우, 상부전지와 하부전지간의 직렬저항이 $1{\Omega}-cm^2$ 이하로 감소하였으며, 이와 같은 계면간의 접합특성 향상으로 I-V특성에서 비틀림 현상이 사라지고, FF가 70% 까지 증가하였다. 또한, 마이크로층과 ZnO:Al 중간층을 동시에 적용한 태양전지의 경우, FF가 75%까지 가장 높게 증가하였다. 광학적 특성의 경우, 같은 두께의 아몰퍼스 n층에 비하여 마이크로 n층이 투과도는 더 높게, 반사도는 낮게 측정되었으며, 이는 하부전지의 단락전류 (Short circuit current : Jsc)를 높여줄 것으로 판단된다.

• Current Photovoltaic Research
• /
• v.6 no.2
• /
• pp.31-38
• /
• 2018

Multijunction solar cells present a practical solution towards a better photovoltaic conversion for a wider spectral range. In this review, we compare different types of multi-ijunction solar cell. First, we introduce thin film multijunction solar cell include to the thin film silicon, III-V material and chalcopyrite material. Until now the maximum reported power conversion efficiencies (PCE) of solar cells having different component sub-cells are 14.0% (thin film silicon), 46% (III-V material), 4.4% (chalcopyrite material) respectively. We then discuss the development of multijunction solar cell in which c-Si is used as bottom sub-cell while III-V material, thin film silicon, chalcopyrite material or perovskite material is used as top sub-cells.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 1993.05a
• /
• pp.53-59
• /
• 1993

The interests on GaAs solar cell grown on Ge substrates as an alternative of GaAs substrate arises from its very close lattice parameters, very small difference in thermal expansion coefficients, and much higher fracture toughness between GaAs and Ge. In addition, for many space power application, it would be a most attractive solar cell with high radiation resistance of GaAs and high reliability for the reverse current damage of Ge, and expecting the theoretical efficiency limit of the tandem GaAs/Ge solar cell is 34% under 1 Sun, AM 0, and 28$^{\circ}C$ condition. In this report, we have reviewed the performance and the manufacturing technics of GaAs/Ge solar cell, and current status of research in GaAs/Ge solar cell.

• Journal of Microbiology and Biotechnology
• /
• v.30 no.5
• /
• pp.662-667
• /
• 2020

Epidermal growth factor receptor (EGFR) mutations are not only genetic markers for diagnosis but also biomarkers of clinical-response against tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC). Among the EGFR mutations, the in-frame deletion mutation in EGFR exon 19 kinase domain (EGFR exon 19-del) is the most frequent mutation, accounting for about 45% of EGFR mutations in NSCLCs. Development of sensitive method for detecting the EGFR mutation is highly required to make a better screening for drug-response in the treatment of NSCLC patients. Here, we developed a fluorometric tandem gene amplification assay for sensitive detection of low-abundance EGFR exon 19-del mutant genomic DNA. The method consists of pre-amplification with PCR, thermal cycling of ligation by Taq ligase, and subsequent rolling circle amplification (RCA). PCR-amplified DNA from genomic DNA samples was used as splint DNA to conjugate both ends of linear padlock DNA, generating circular padlock DNA template for RCA. Long stretches of ssDNA harboring multiple copies of G-quadruplex structure was generated in RCA and detected by thioflavin T (ThT) fluorescence, which is specifically intercalated into the G-quadruplex, emitting strong fluorescence. Sensitivity of tandem gene amplification assay for detection of the EGFR exon 19-del from gDNA was as low as 3.6 pg, and mutant gDNA present in the pooled normal plasma was readily detected as low as 1% fraction. Hence, fluorometric detection of low-abundance EGFR exon 19 deletion mutation using tandem gene amplification may be applicable to clinical diagnosis of NSCLC patients with appropriate TKI treatment.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.23 no.1
• /
• pp.17-28
• /
• 1998

This study suggests a procedure for designing cellular manufacturing systems (CMS) which are combined with automated guided vehicles (AGVs) using a tandem configuration. So far most of the previous studies have dealt with conventional design problems not considering the layout and the characteristics of transporters used in CMS. A mathematical model is developed using the service time to perform material transfers as a suitable meassure. The service capacity of AGVs and space limitations are also reflected in this model. As the model can be shown strongly NP-hard, a heuristic algorithm is presented, in which each cell is temporarily formed using both the set covering model and similarity coefficients, and then locations of the cells are determined by means of tabu search and finally machine perturbations are carried out. An example problem is solved to demonstrate the algorithm developed.

• Proceedings of the PSK Conference
• /
• 2003.04a
• /
• pp.288.3-289
• /
• 2003

Sphingolipid species are important second messengers due to their role in the mitogenesis, differentiation and apoptosis. We developed a new column liquid chromatography-triple quadrupole tandem mass spectrometry (LC-MS/MS) in combination with multiple reaction monitoring (MRM) method for the rapid, simultaneous and quantitative determination of unambiguous detecting sphingolipids in cell culture of human cancer cells (HL-60). (omitted)