bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of a Hyper‐cross‐linked Polymer Monolithic Column and Its Application to the Sensitive Determination of Genomic DNA Methylation
Authors: Chen Ming‐Luan , Liu Yu‐Li , Xing Xi‐Wen , Zhou Xiang , Feng Yu‐Qi , Yuan Bi‐Feng 
Published: November 2012

AbstractA hyper‐cross‐linked polymer monolithic column, poly(methacrylatoethyl trimethyl ammonium‐co‐vinylbenzene chloride‐co‐divinylbenzene) (MATE‐co‐VBC‐co‐DVB) with phenyl and quaternary ammonium groups was successfully prepared in the current study. The prepared monolith possesses large specific surface area, narrow mesopore size distribution and high column efficiency. The poly(MATE‐co‐VBC‐co‐DVB) monolithic column was demonstrated to have strong anion exchange/reversed‐phase (SAX/RP) mixed‐mode retention for analytes on capillary liquid chromatography (cLC). By using this monolithic column, we developed a rapid and sensitive method for the detection of DNA methylation. Our results showed that six nucleobases (adenine, guanine, cytosine, thymine, uracil, and 5‐methylcytosine (5‐mC)) can be baseline separated within 15 min by electrostatic repulsion and hydrophobic interactions between nucleobases and the monolithic stationary phase. The limit of detection (LOD, signal/noise=3) of 5‐mC is 0.014 pmol and endogenous 5‐mC can be distinctly detected by using only 10 ng genomic DNA, which is comparable to that obtained by mass spectrometry analysis. Furthermore, by using the method developed here, we found that DNA methylation inhibitor 5‐azacytidine (5‐aza‐C) and 5‐aza‐2′‐deoxycytidine (5‐aza‐CdR) could induce a significant decrease of genome‐wide DNA methylation in human lung carcinoma cells (A549) and cervical carcinoma cells (HeLa).
Template Syntheses of Copper(II) Complexes from Arylhydrazones of Malononitrile and their Catalytic Activity towards Alcohol Oxidations and the Nitroaldol Reaction: Hydrogen Bond‐Assisted Ligand Liberation and E/Z Isomerisation
Authors: Kopylovich Maximilian N. , Mizar Archana , Guedes da Silva M. Fátima C. , Mac Leod Tatiana C. O. , Mahmudov Kamran T. , Pombeiro Armando J. L. 
Published: November 2012

AbstractA one‐pot template condensation of 2‐(2‐(dicyanomethylene)hydrazinyl)benzenesulfonic acid (H2L1, 1) or 2‐(2‐(dicyanomethylene)hydrazinyl)benzoic acid (H2L2, 2) with methanol (a), ethylenediamine (b), ethanol (c) or water (d) on copper(II), led to a variety of metal complexes, that is, mononuclear [Cu(H2O)2(κO1,κN2 L1a] (3) and [Cu(H2O)(κO1,κN3 L1b)] (4), tetranuclear [Cu4(1 κO1,κN2:2 κO1 L2a)3‐(1 κO1, κN2:2 κO2 L2a)] (5), [Cu2(H2O)(1 κO1, κN2:2 κO1 L2c)‐(1 κO1,1 κN2:2 κO1,2 κN1‐ L2c)]2 (6) and [Cu2(H2O)2(κO1,κN2‐ L1dd)‐(1 κO1,κN2:2 κO1 L1dd)(μ‐H2O)]2⋅ 2 H2O (7⋅2 H2O), as well as polymer‐ ic [Cu(H2O)(κO1,1 κN2:2 κN1 L1c)]n (8) and [Cu(NH2C2H5)(κO1,1 κN2:2 κN1L2a)]n (9). The ligands 2‐SO3H‐C6H4‐(NH)NC{(CN)[C(NH2)‐(NCH2CH2NH2)]} (H2L1b, 10), 2‐CO2H‐C6H4‐(NH)N{C(CN)[C(OCH3)‐(NH)]} (H2L2a, 11) and 2‐SO3H‐C6H4‐(NH)NC{C(O)‐(NH2)}2 (H2L1dd, 12) were easily liberated upon respective treatment of 4, 5 and 7 with HCl, whereas the formation of cyclic zwitterionic amidine 2‐(SO3−)C6H4NNC(C(NH+)CH2CH2NH)(CNHCH2CH2NH) (13) was observed when 1 was treated with ethylenediamine. The hydrogen bond‐induced E/Z isomerization of the (HL1d)− ligand occurs upon conversion of [{Na(H2O)2(μ‐H2O)2}(HL1d)]n (14) to [Cu(H2O)6][HL1d]2⋅2 H2O (15) and [{CuNa(H2O)‐(κN1,1 κO2:2 κO1 L1d)2}K0.5(μ‐O)2]n⋅H2O (16). The synthesized complexes 3–9 are catalyst precursors for both the selective oxidation of primary and secondary alcohols (to the corresponding carbonyl compounds) and the following diastereoselective nitroaldol (Henry) reaction, with typical yields of 80–99 %.
Structure Sensitivity of CO Oxidation on Co3O4: A DFT Study
Authors: Pang Xian‐Yong , Liu Chang , Li Dui‐Chun , Lv Cun‐Qin , Wang Gui‐Chang 
Published: November 2012

AbstractThe reaction mechanism of CO oxidation on the Co3O4 (110) and Co3O4 (111) surfaces is investigated by means of spin‐polarized density functional theory (DFT) within the GGA+U framework. Adsorption situation and complete reaction cycles for CO oxidation are clarified. The results indicate that 1) the U value can affect the calculated energetic result significantly, not only the absolute adsorption energy but also the trend in adsorption energy; 2) CO can directly react with surface lattice oxygen atoms (O2f/O3f) to form CO2 via the Mars–van Krevelen reaction mechanism on both (110)‐B and (111)‐B; 3) pre‐adsorbed molecular O2 can enhance CO oxidation through the channel in which it directly reacts with molecular CO to form CO2 [O2(a)+CO(g)→CO2(g)+O(a)] on (110)‐A/(111)‐A; 4) CO oxidation is a structure‐sensitive reaction, and the activation energy of CO oxidation follows the order of Co3O4 (111)‐A(0.78 eV)>Co3O4 (111)‐B (0.68 eV)>Co3O4 (110)‐A (0.51 eV)>Co3O4 (110)‐B (0.41 eV), that is, the (110) surface shows higher reactivity for CO oxidation than the (111) surface; 5) in addition to the O2f, it was also found that Co3+ is more active than Co2+, so both O2f and Co3+ control the catalytic activity of CO oxidation on Co3O4, as opposed to a previous DFT study which concluded that either Co3+ or O2f is the active site.
Nanoporous PdTi Alloys as Non‐Platinum Oxygen‐Reduction Reaction Electrocatalysts with Enhanced Activity and Durability
Authors: Liu Yunqing , Xu Caixia 
Published: November 2012

AbstractA nanoporous PdTi (NP‐PdTi) alloy with uniform ligament size and controllable bimetallic ratio was easily fabricated by a one‐step mild dealloying process of PdTiAl (precursor alloy). NP‐PdTi consisted of an interconnected network of nanoscale ligaments with bicontinuous hollow channels extending in all three dimensions. Electrocatalytic measurements indicated that NP‐PdTi had superior electrocatalytic activity in the oxygen reduction reaction (ORR) with enhanced specific and mass activities as well higher methanol tolerance relative to Pt/C. Interestingly, NP‐PdTi showed higher catalytic durability than Pt/C with a lower decrease in the ORR activity and electrochemical surface area of the metal upon 5000 potential cycles in an acidic solution. DFT calculations demonstrated that alloying Pd with Ti could bring favorable electronic perturbation with the downshifted d‐band center of Pd, leading to a weakened PdO bond and improved ORR performance. The excellent electrocatalytic performance in ORR renders NP‐PdTi alloys attractive as efficient cathode electrocatalysts in fuel‐cell‐related technologies.
Gene expression profiling revealed specific spermatogonial stem cell genes in mouse
Authors: Yang Lele , Wu Wei , Qi Huayu 
Published: November 2012

AbstractMammalian spermatogenesis originates from spermatogonial stem cells (SSCs), which undergo mitosis, meiosis and spermiogenesis in order to generate mature spermatozoa. SSCs are adult stem cells that can both self‐renew and differentiate. To maintain pluripotency, SSCs are regulated by both extrinsic factors secreted from surrounding somatic cells and intrinsic factors including specific gene expression programs. Using fluorescent labeled germ line stem cells, mouse gonocytes and SSCs were purified up to 97% by improved FACS method. Through microarray analyses, global gene expression profiles of gonocytes, SSCs, and differentiated cells were compared. A large number of distinctive genes were found to be enriched in respective cell populations, indicating different functional requirements of each cell type. Functional clustering analyses revealed that while gonocytes and SSCs preferentially express genes implicated in gene expression regulation and epigenetic modifications, differentiated cells including somatic cells are enriched with genes encoding proteins involved in various cellular activities. Further in situ hybridization and RT‐PCR experiments confirmed SSC specific expression of several genes of which functions have not been characterized in SSCs. The comparative gene expression profiling provides a useful resource for gene discovery in relation to SSC regulation and opens new avenues for the study of molecular mechanisms underlying SSC self‐renewal and differentiation. genesis 51:83–96, 2013. © 2012 Wiley Periodicals, Inc.
Optimization of dry‐season sap flow measurements in an oak semi‐arid open woodland in Spain
Authors: Reyes‐Acosta J. Leonardo , Lubczynski Maciek W. 
Published: November 2012

ABSTRACTIn sap flow studies, there is no method complying with high efficiency and versatility of sap flow measurements. To improve that, we propose combining two methods: (1) thermal dissipation probe (TDP) known to be efficient and cost effective and (2) heat field deformation (HFD) known to be versatile. For that purpose, we used a step‐wise TDP sap flux density (Jp) optimization method consisting of (1) natural temperature gradient (NTG) correction applying the cyclic heat dissipation (CHD) method, (2) night flow ΔTmax correction using HFD data as reference and (3) radial‐azimuthal correction using HFD as reference. We applied this optimization method on Quercus ilex (Q.i.) and Quercus pyrenaica (Q.p.) trees in a Spanish semi‐arid open woodland during dry season. The NTG correction resulted in substantial reduction of Jp as compared with standard TDP. The subsequent ΔTmax night flow correction resulted in the increase of NTG‐corrected Jp and good agreement with the outermost 2 cm of HFD measurements for both species. The final radial‐azimuthal adjustment of TDP Jp resulted not only, in a good agreement with HFD Jp, but also provided novel ecohydrological insights such as: (1) evidence of continuous night flow in all Q.p. trees and some Q.i. trees, (2) exponential reduction of Jp with sapwood depth for both species, (3) significantly larger Jp in the outermost 1 cm of sapwood for Q.p. than for Q.i. and (4) high azimuthal Jp variability for both species. The presented study offers efficient and versatile method of tree sap flow measurements that contributed to a better understanding of water‐related dynamics of Q.i. and Q.p. under water‐stress conditions. Copyright © 2012 John Wiley & Sons, Ltd.
Switching between MIMO‐TDMA and MIMO‐CDMA
Authors: Wang Jui Teng 
Published: November 2012

AbstractThe throughput analyses for MIMO‐TDMA (multiple‐input multiple‐output with time division multiple access) and MIMO‐CDMA (multiple‐input multiple‐output with code division multiple access) are performed. These analyses show that there is a crossover in the throughput for MIMO‐TDMA and MIMO‐CDMA. Also, they show that the signal‐to‐noise ratio (SNR) and the number of co‐channel users under multiple access control can determine that either MIMO‐TDMA or MIMO‐CDMA has the advantage in the throughput. We solve one equation that equalizes the upper bounds of throughput and use its solution as the threshold of SNR for the threshold‐based switching algorithm, which switches to MIMO‐TDMA if the received SNR is larger than the threshold of SNR and switches to MIMO‐CDMA otherwise. Simulation results show that the threshold of SNR approximates the crossover SNR (for which MIMO‐TDMA and MIMO‐CDMA have the same throughput) so that the threshold‐based switching scheme (which adopts the threshold based switching algorithm) can switch to the scheme (MIMO‐TDMA or MIMO‐CDMA) that has the largest throughput. Copyright © 2012 John Wiley & Sons, Ltd.
Circulating stem cell–like epithelial cell adhesion molecule–positive tumor cells indicate poor prognosis of hepatocellular carcinoma after curative resection
Authors: Sun Yun-Fan , Xu Yang , Yang Xin-Rong , Guo Wei , Zhang Xin , Qiu Shuang-Jian , Shi Ruo-Yu , Hu Bo , Zhou Jian , Fan Jia 
Published: November 2012

Abstract

Epithelial cell adhesion molecule–positive (EpCAM+) hepatocellular carcinoma (HCC) cells may constitute a tumor-initiating subpopulation in tumorigenic cell lines and HCC specimens. In the present study, EpCAM+ circulating tumor cells (CTCs) were identified prospectively in HCC patients undergoing curative resection, and the prognostic significance and their stem cell–like characteristics were investigated further. Blood samples from 123 HCC patients were tested prior to resection and 1 month thereafter. CTCs were present in 66.67% of patients, and the cell count measured in 7.5 mL of blood (CTC7.5) ranged between 1 and 34. Fifty-one patients had CTC7.5 of ≥2 preoperatively, and these patients developed tumor recurrence earlier than those with CTC7.5 of <2 CTCs (

P

< 0.001). A preoperative CTC7.5 of ≥2 was an independent prognostic factor for tumor recurrence (

P

< 0.001). Its prognostic significance also applied to patients with alpha-fetoprotein (AFP) levels of ≤400 ng/mL or subgroups with low recurrence risk (all

P

< 0.05). A significant decrease of CTC-positive rates (66.67% to 28.15%,

P

< 0.05) and CTC7.5 values (2.60 ± 0.43 to 1.00 ± 0.36,

P

< 0.05) was observed 1 month after resection. Patients with consistent CTC7.5 <2 had lower recurrence rates than those with values consistently ≥2 (15.5% versus 87.50%,

P

< 0.001). EpCAM+ CTCs displayed cancer stem cell biomarkers (CD133 and ABCG2), epithelial-mesenchymal transition, Wnt pathway activation, high tumorigenic potential, and low apoptotic propensity.

Conclusion

: Stem cell–like phenotypes are observed in EpCAM+ CTCs, and a preoperative CTC7.5 of ≥2 is a novel predictor for tumor recurrence in HCC patients after surgery, especially in patient subgroups with AFP levels of ≤400 ng/mL or low tumor recurrence risk. EpCAM+ CTCs may serve as a real-time parameter for monitoring treatment response and a therapeutic target in HCC recurrence.
Chronic intermittent hypoxia aggravates intrahepatic endothelial dysfunction in cirrhotic rats
Authors: Hernández-Guerra Manuel , de Ganzo Zaida Adrián , González-Méndez Yanira , Salido Eduardo , Abreu Pedro , Moreno Miguel , Felipe Vanesa , Abrante Beatriz , Quintero Enrique 
Published: November 2012

Abstract

Chronic intermittent hypoxia (CIH) occurs with obstructive sleep apnea syndrome (OSAS) and provokes systemic endothelial dysfunction, which is associated with oxidative stress and low nitric oxide (NO) bioavailability. Cirrhotic livers exhibit intrahepatic endothelial dysfunction, which is characterized by an impaired endothelium-dependent response to vasodilators and hyperresponse to vasoconstrictors. We hypothesized that CIH may also contribute to intrahepatic endothelial dysfunction in cirrhosis. Normal and cirrhotic rats were exposed for 14 days to repetitive cycles of CIH mimicking OSAS in humans, or caged with room air (handled controls [HC]). Hepatic endothelial function was assessed in isolated and perfused rat livers by dose-response curves to acetylcholine (ACh) and methoxamine (Mtx). In a group of cirrhotic rats,

in vivo

systemic and hepatic hemodynamic parameters were evaluated at baseline and after volume expansion. In addition, liver samples were obtained to assess endothelial nitric oxide synthase (eNOS), phosphorylated eNOS (p-eNOS), NO bioavailability, and nitrotyrosinated proteins as a marker of oxidative stress. Cirrhotic rats exposed to CIH exhibited an attenuated vasodilatory response to ACh and hyperresponse to Mtx compared with HC rats. During volume expansion, similar portal pressure increases were observed in CIH and HC rats, although the mean arterial pressure increase was lower after CIH. These functional responses were associated with the presence of increased hepatic oxidative stress without changes in p-eNOS after CIH exposure. In normal rats, no hemodynamic changes were found.

Conclusion

: CIH exacerbates intrahepatic endothelial dysfunction in cirrhotic rats, which is associated with increased oxidative stress that may reduce NO bioavailability. Clinical studies are needed to assess whether OSAS contributes to endothelial impairment in human patients with cirrhosis.
Enhancement of tumor-associated antigen-specific T cell responses by radiofrequency ablation of hepatocellular carcinoma
Authors: Mizukoshi Eishiro , Yamashita Tatsuya , Arai Kuniaki , Sunagozaka Hajime , Ueda Teruyuki , Arihara Fumitaka , Kagaya Takashi , Yamashita Taro , Fushimi Kazumi , Kaneko Shuichi 
Published: November 2012

Abstract

Radiofrequency ablation (RFA) is one of the treatments for hepatocellular carcinoma (HCC) and is known to enhance host immune response. However, the epitopes to which enhanced immune responses occur, the impact on patient prognosis, and the functions and phenotype of T cells induced are still unclear. To address these issues, we analyzed immune responses before and after RFA in 69 HCC patients using 11 tumor-associated antigen (TAA)-derived peptides that we identified to be appropriate to analyze HCC-specific immune responses. The immune responses were analyzed using enzyme-linked immunospot (ELISPOT) assay and tetramer assays using peripheral blood mononuclear cells. An increase in the number of TAA-specific T cells detected by interferon-γ ELISPOT assays occurred in 62.3% of patients after RFA. The antigens and their epitope to which enhanced T cell responses occur were diverse, and some of them were newly induced. The number of TAA-specific T cells after RFA was associated with the prevention of HCC recurrence, and it was clarified to be predictive of HCC recurrence after RFA by univariate and multivariate analyses. The number of TAA-specific T cells after RFA was inversely correlated with the frequency of CD14+HLA-DR−/low myeloid-derived suppressor cells (MDSCs). The modification of T cell phenotype was observed after RFA. The number of TAA-specific T cells at 24 weeks after RFA was decreased.

Conclusion

: Although RFA can enhance various TAA-specific T cell responses and the T cells induced contribute to the HCC recurrence-free survival of patients, besides immunosuppression by MDSCs, the memory phenotype and lifetime of TAA-specific T cells are not sufficient to prevent HCC recurrence completely. Additional treatments by vaccine or immunomodulatory drugs might be useful to improve the immunological effect of RFA.
Sal-like protein 4 (SALL4), a stem cell biomarker in liver cancers
Authors: Oikawa Tsunekazu , Kamiya Akihide , Zeniya Mikio , Chikada Hiromi , Hyuck Ahn Dong , Yamazaki Yuji , Wauthier Eliane , Tajiri Hisao , Miller Lance D. , Wang Xin Wei , Reid Lola M. , Nakauchi Hiromitsu 
Published: November 2012

Abstract

Liver cancers, including hepatocellular carcinomas (HCCs), cholangiocarcinomas (CCs), and fibrolamellar HCCs (FL-HCCs) are among the most common cancers worldwide and are associated with a poor prognosis. Investigations of genes important in liver cancers have focused on Sal-like protein 4 (SALL4), a member of a family of zinc finger transcription factors. It is a regulator of embryogenesis, organogenesis, pluripotency, can elicit reprogramming of somatic cells, and is a marker of stem cells. We found it expressed in normal murine hepatoblasts, normal human hepatic stem cells, hepatoblasts and biliary tree stem cells, but not in mature parenchymal cells of liver or biliary tree. It was strongly expressed in surgical specimens of human HCCs, CCs, a combined hepatocellular and cholangiocarcinoma, a FL-HCC, and in derivative, transplantable tumor lines in immune-compromised hosts. Bioinformatics analyses indicated that elevated expression of SALL4 in tumors is associated with poor survival of HCC patients. Experimental manipulation of SALL4′s expression results in changes in proliferation versus differentiation in human HCC cell lines

in vitro

and

in vivo

in immune-compromised hosts. Virus-mediated gene transfer of SALL4 was used for gain- and loss-of-function analyses in the cell lines. Significant growth inhibition

in vitro

and

in vivo

, accompanied by an increase in differentiation occurred with down-regulation of SALL4. Overexpression of SALL4 resulted in increased cell proliferation

in vitro

, correlating with an increase in expression of cytokeratin19 (CK19), epithelial cell adhesion molecules (EpCAM), and adenosine triphosphate (ATP)-binding cassette-G2 (ABCG2).

Conclusion:

SALL4′s expression is an indicator of stem cells, a prognostic marker in liver cancers, correlates with cell and tumor growth, with resistance to 5-FU, and its suppression results in differentiation and slowed tumor growth. SALL4 is a novel therapeutic target for liver cancers.
Oxidative stress plays a major role in chlorpromazine-induced cholestasis in human HepaRG cells
Authors: Anthérieu Sébastien , Azzi Pamela Bachour-El , Dumont Julie , Abdel-Razzak Ziad , Guguen-Guillouzo Christiane , Fromenty Bernard , Robin Marie-Anne , Guillouzo André 
Published: November 2012

Abstract

Drugs induce cholestasis by diverse and still poorly understood mechanisms in humans. Early hepatic effects of chlorpromazine (CPZ), a neuroleptic drug known for years to induce intrahepatic cholestasis, were investigated using the differentiated human hepatoma HepaRG cells. Generation of reactive oxygen species (ROS) was detected as early as 15 minutes after CPZ treatment and was associated with an altered mitochondrial membrane potential and disruption of the pericanalicular distribution of F-actin. Inhibition of [3H]-taurocholic acid efflux was observed after 30 minutes and was mostly prevented by N-acetyl cysteine (NAC) cotreatment, indicating a major role of oxidative stress in CPZ-induced bile acid (BA) accumulation. Moreover, 24-hour treatment with CPZ decreased messenger RNA (mRNA) expression of the two main canalicular bile transporters, bile salt export pump (BSEP) and multidrug resistance protein 3 (MDR3). Additional CPZ effects included inhibition of Na+-dependent taurocholic cotransporting polypeptide (NTCP) expression and activity, multidrug resistance-associated protein 4 (MRP4) overexpression and CYP8B1 inhibition that are involved in BA uptake, basolateral transport, and BA synthesis, respectively. These latter events likely represent hepatoprotective responses which aim to reduce intrahepatic accumulation of toxic BA. Compared to CPZ effects, overloading of HepaRG cells with high concentrations of cholic and chenodeoxycholic acids induced a delayed oxidative stress and, similarly, after 24 hours it down-regulated BSEP and MDR3 in parallel to a decrease of NTCP and CYP8B1 and an increase of MRP4. By contrast, low BA concentrations up-regulated BSEP and MDR3 in the absence of oxidative stress.

Conclusion

: These data provide evidence that, among other mechanisms, oxidative stress plays a major role as both a primary causal and an aggravating factor in the early CPZ-induced intrahepatic cholestasis in human hepatocytes.