bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrophoresis studies on the contaminating glycosaminoglycans in commercially available hyaluronic acid products
Authors: Matsuno Yu‐Ki , Kakoi Naotaka , Kinoshita Mitsuhiro , Matsuzaki Yuji , Kumada Jun‐Ichi , Kakehi Kazuaki 
Published: September 2008

AbstractHyaluronic acid (HA) samples showing inhibition effect on digestion with testicular hyaluronidase (HAase) were found from 16 commercially available HA products, which were supplied from 11 different manufacturers. Most of these HA samples (six samples) were derived from the rooster comb, and one sample was derived from the human umbilical cord. HA oligosaccharides produced by exhaustive digestion of these HA samples with testicular HAases were monitored by capillary electrophoresis, and we found that a few HA samples gave no oligosaccharide products. Detailed analysis of HA samples by cellulose acetate membrane electrophoresis revealed that the HA samples were not digested with HAase because of the presence of a small amount of dermatan sulfate (DS). Analysis of disaccharide units of these HA samples produced by digestion with chondroitinase ABC supported the observations. And the content of DS in the sample was estimated to be ca. 8%. In contrast, these HA samples were easily digested with bacterial hyaluronate lyases from Streptomyces hyalurolyticus and Streptococcus dysgalactiae and gave endproducts of unsaturated disaccharide or unsaturated tetra‐ or hexasaccharides. The results suggested that the inhibitory effect of DS on HAase is specific to endo‐type hydrolase (i.e. testicular HAase). In addition, pharmaceutical preparations of HA derived from rooster comb were easily digested with testicular HAase. These findings will be useful information for clinical or cosmetic use of HA preparations in terms of their half‐life.
A highly sensitive CE‐UV method with dynamic coating of silica‐fused capillaries for monitoring of nucleotide pyrophosphatase/phosphodiesterase reactions
Authors: Iqbal Jamshed , Lévesque Sébastien A. , Sévigny Jean , Müller Christa E. 
Published: September 2008

AbstractA new highly sensitive capillary electrophoresis (CE) method applying dynamic coating and on‐line stacking for the monitoring of nucleotide pyrophosphatases/phosphodiesterases (NPPs) and the screening of inhibitors was developed. NPP1 and NPP3 are membrane glycoproteins that catalyze the hydrolysis nucleotides, e.g. convert adenosine 5′‐triphosphate to adenosine 5′‐monophosphate (AMP) and pyrophosphate. Enzymatic reactions were performed and directly subjected to CE analysis. Since the enzymatic activity was low, standard methods were insufficient. The detection of nanomolar AMP and other nucleotides could be achieved by field‐enhanced sample injection and the addition of polybrene to the running buffer. The polycationic polymer caused a dynamic coating of the silica‐fused capillary, resulting in a reversed electroosmotic flow. The nucleotides migrated in the direction of the electroosmotic flow, whereas the positively charged polybrene molecules moved in the opposite direction, resulting in a narrow sample zone over a long injection time. Using this on‐line sensitivity enhancement technique, a more than 70‐fold enrichment was achieved for AMP (limit of detection, 46 nM) along with a short migration time (5 min) without compromising separation efficiency and peak shape. The optimized CE conditions were as follows: fused‐silica capillary (30 cm effective length×75 μm), electrokinetic injection for 60 s, 50 mM phosphate buffer pH 6.5, 0.002% polybrene, constant current of −60 μA, UV detection at 210 nm, uridine 5′‐monophosphate as the internal standard. The new method was used to study enzyme kinetics and inhibitors. It opens an easy way to determine the activities of slowly metabolizing enzymes such as NPPs, which are of considerable interest as novel drug targets.
Analysis of the molecular size distribution of polyethylene glycols by CE‐UV versus HPLC with evaporative light scattering detection
Authors: Brinz Daniela , Holzgrabe Ulrike 
Published: September 2008

AbstractA simple capillary zone electrophoresis method has been developed for the separation of polyethylene glycols (PEGs) consisting of differing amounts of polymers with different monomer numbers up to an average molecular mass of 1500. To provide both charge and detectability, the analytes were derivatized with phthalic anhydride according to a conventional method and a newly developed microwave‐assisted method. While obtaining nearly equal amounts of single and double esterificated PEGs with the conventional method, the fraction of single derivatized PEGs is considerably reduced by microwave‐assisted reaction. In order to compare the capillary zone electrophoresis results, an HPLC method with evaporative light scattering detection has been established. This method was successfully applied to the analysis of underivatized PEG 400, 1000 and 1500.
Fast assay of glucosamine in pharmaceuticals and nutraceuticals by capillary zone electrophoresis with contactless conductivity detection
Authors: Jáč Pavel , Los Petr , Spáčil Zdeněk , Pospíšilová Marie , Polášek Miroslav 
Published: September 2008

AbstractA novel capillary electrophoresis (CE) method with contactless conductivity detection suitable for the determination of glucosamine (GlAm) and K+ in pharmaceuticals was devised. Under the optimum conditions (aqueous 30 mM acetate buffer of pH 5.2 as the background electrolyte; voltage 30 kV; 25°C), GlAm (migrating as glucosaminium cation) was well separated from K+ that could occur in the dosage forms as excipient. The CE analysis was performed in fused‐silica capillaries (50 µm i.d., 75 cm total length, 27 cm to detector) and the separation took <3 min. The calibration graphs were linear for both GlAm (100–300 µg/mL; r2=0.997) and K+ (15–75 µg/mL; r2=0.997) when using ethanolamine (100 µg/mL) as the internal standard. The LOD values (S/N=3) were 9.3 µg/mL for GlAm and 2.9 µg/mL for K+. The method was applied to the assay of GlAm content in various dosage forms. Intermediate precision evaluated by determining the content of GlAm in a single formulation on 3 consecutive days was characterized by RSD 2.35% (n=15). Acceptable accuracy of the CE method was confirmed by the added/found GlAm recovery experiments (recoveries 94.6–103.3%) and by statistical comparison of the results attained by the proposed CE and a reference HPLC method.
Cyclodextrin‐based nonaqueous electrokinetic chromatography with UV and mass spectrometric detection: Application to the impurity profiling of amiodarone
Authors: Mol Roelof , de Jong Gerhardus J. , Somsen Govert W. 
Published: September 2008

AbstractThe potential of nonaqueous electrokinetic chromatography (NAEKC) using cyclodextrins (CD) for the analysis of basic drugs and related compounds was evaluated. Both UV absorbance and mass spectrometric (MS) detection were employed. Addition of neutral CD to the NA background electrolyte did not significantly enhance the separation of a test mixture of basic drugs, and no change in selectivity was observed. In contrast, anionic single‐isomer‐sulfated CD strongly added to the selectivity of the NAEKC system inducing an improved resolution among the test compounds and increasing the migration time window. The applicability of the NAEKC system using anionic CD is demonstrated by the profiling of a sample of the drug amiodarone that had been stored for 1 year at room temperature. Amiodarone is poorly soluble in water. NAEKC‐UV analysis indicated the presence of at least seven impurities in the amiodarone sample. In order to identify these compounds, the NAEKC system was coupled directly to electrospray ionization (ESI) ion‐trap MS. The total of detected impurities increased to 12 due to the added sensitivity and selectivity of MS detection. Based on the acquired MS/MS data, three sample constituents could be identified as ‘known’ impurities (British Pharmacopoeia), whereas for three unknown impurities molecular structures could be proposed. Estimated limits of detection for amiodarone using the NAEKC method were 1 μg/mL with UV detection and 15 ng/mL with ESI‐MS detection (full‐scan). Based on relative responses, the impurity content of the stored drug substance was estimated to be 0.33 and 0.47% using NAEKC‐UV and NAEKC‐ESI‐MS, respectively.
Strategies in method development to quantify enantiomeric impurities using CE
Authors: El Deeb Sami , Hasemann Phillip , Wätzig Hermann 
Published: September 2008

AbstractThe growing number of chiral new drug substances requires increasing efforts in developing enantioselective methods. According to International conference on Harmonization guidelines, one should quantify the enantiomeric impurity of 0.1% relative to the major constituent. Capillary electrophoresis has evolved into an important tool for the separation of chiral drugs. The common strategies consist of two steps: firstly, initial separation conditions are evaluated. This screening usually focuses on the selection of the appropriate chiral selector. In our study 22 neutral, anionic or cationic cyclodextrins were dissolved in phosphate buffer (pH 2.5, 50 mM, CD conc.: 2.0%). Then they were investigated for the separation of 14 chiral compounds. Secondly, the obtained initial conditions for the enantiomeric separation were optimized in terms of resolution and analysis time. In our approach, important optimized factors including the concentration of the chiral selector (1–10%), the pH of the buffer (2.0–9.0), and the percentage of organic modifier (0–15%) were studied.This common strategy was completed by elaborating final requirements for the quantification of the enantiomeric impurity. A resolution between 3 and 4 was found to be necessary for the racemic mixture during the screening and optimization steps, in order to later allow for peak overloading and thus to sufficiently increase the signal‐to‐noise ratio. The complete strategy was conducted for atenolol, isoprenaline, verapamil and mandelic acid.
A simple micellar electrokinetic capillary chromatographic method for the quantitative analysis of organic expectorants
Authors: Lin Yu‐Ting , Kou Hwang‐Shang , Wu Hsin‐Lung 
Published: September 2008

AbstractA simple and rapid micellar electrokinetic capillary chromatographic method is described for the separation and quantification of five expectorant drugs, including ambroxol (AMB), bromhexine (BRM), carbocysteine, guaiacol and guaifenesin. The drugs were separated in a mixed solution of phosphate buffer (35 mM; pH 3.90) and acetonitrile (75:25, v/v) with sodium dodecylsulfate (120 mM) as the micellar source, and the separated drugs were directly monitored with UV detector (200 nm). Several key parameters affecting the separation and analysis of the drugs were studied and optimized. Based on the corrected peak‐area ratios of the drugs to an internal standard (7‐hydroxy‐4‐methyl‐coumarin) versus the concentration of the drugs, the established method is applicable to quantify AMB and BRM each over 20–150 µM, carbocysteine over 100–1500 µM, guaiacol and guaifenesin each over 10–150 µM. The detection limits (S/N=3; 0.5 psi, 5 s injection) of the method for the analytes are in the range of 3.0–5.0 µM (except that of carbocysteine at 30 µM). The precision (relative standard deviation) and accuracy (relative error) of the method for the intra‐day (n=3) and inter‐day (n=5) analyses of the analytes at three levels are all below 4%. The method is speedy with a run time of about 6 min for the analysis of the five analytes. Application of this method to the analysis of AMB and BRM in pharmaceutical preparations or AMB in the urine of a dosed subject proved simple and effective.
Sensitive analysis of donepezil in plasma by capillary electrophoresis combining on‐column field‐amplified sample stacking and its application in Alzheimer's disease
Authors: Yeh Hsin‐Hua , Yang Yuan‐Han , Ko Ju‐Yun , Chen Su‐Hwei 
Published: September 2008

AbstractField‐amplified sample stacking (FASS) in capillary electrophoresis (CE) was used to determine the concentration of donepezil, an acetylcholinesterase inhibitor, in human plasma. A sample pretreatment by liquid–liquid extraction with isopropanol/n‐hexane (v/v 3:97) and subsequent quantification by FASS‐CE was used. Before sample loading, a water plug (0.5 psi, 6 s) was injected to permit FASS. Electrokinetic injection (7 kV, 90 s) was used to introduce sample cations. The separation condition for donepezil was performed in electrolyte solutions containing Tris buffer (60 mM, pH 4.0) with sodium octanesulfonate 40 mM and 0.01% polyvinyl alcohol as a dynamic coating to reduce analytes' interaction with capillary wall. The separation was performed at 28 kV and detected at 200 nm. Using atenolol as an internal standard, the linear ranges of the method for the determination of donepezil in human plasma were over a range of 1–50 ng/mL. The limit of detection was 0.1 ng/mL (S/N=3, sampling 90 s at 7 kV). One female volunteer (54 years old) was orally administered a single dose of 10 mg donepezil (Aricept®, Eisai), and blood samples were drawn over a 60 h period for pharmacokinetic study. The method was also applied successfully to monitor donepezil in sixteen Alzheimer's disease patients' plasmas.
Hybrid simulation of a zipper‐braced steel frame under earthquake excitation
Authors: Yang T. Y. , Stojadinovic B. , Moehle J. 
Published: September 2008

AbstractHybrid simulation is a testing methodology that combines laboratory and analytical simulation to evaluate seismic response of complex structural framing systems. One or more portions of the structure, which may be difficult to model numerically or have properties that have not been examined before, are tested in one or more laboratories, whereas the remainder of the structure is modeled in software using one or more computers. These separate portions are assembled such that combined dynamic response of the hybrid model to excitation is computed using a time‐stepping procedure.A hybrid simulation conducted to examine the seismic response of a type of steel concentrically braced frame, the suspended‐zipper‐braced frame, is presented. The hybrid simulation testing architecture, hybrid model, test setup, solution algorithm, and the seismic response of the suspended‐zipper‐braced frame hybrid model are discussed. Accuracy of this hybrid simulation is examined by comparing hybrid and computer‐only simulations and the errors are quantified using an energy‐based approach. This comparison indicates that the deployed hybrid simulation method can be used to accurately model the seismic response of a complex structural system such as the zipper‐braced frame. Copyright © 2008 John Wiley & Sons, Ltd.
Capn4 overexpression underlies tumor invasion and metastasis after liver transplantation for hepatocellular carcinoma #
Authors: Bai Dou-Sheng , Dai Zhi , Zhou Jian , Liu Yin-Kun , Qiu Shuang-Jian , Tan Chang-Jun , Shi Ying-Hong , Huang Cheng , Wang Zheng , He Yi-Feng , Fan Jia 
Published: September 2008

Abstract
Liver transplantation (LT) is one of the best therapeutic options for nonresectable hepatocellular carcinoma (HCC). Unfortunately, some HCC patients succumb to the disease after LT, which reduces long- and medium-term survival. To identify the proteins associated with HCC invasion and metastasis, HCC patients undergoing LT with complete follow-up data were included in this study and were categorized into recurrence and nonrecurrence groups. We extracted the total protein from the acquired homogeneous tumor cells and applied a cleavable isotope-coded affinity tag technology to quantitate relative changes in protein levels between the two groups. We identified a total of 149 proteins with two-dimensional liquid chromatography coupled with tandem mass spectrometry, including 52 differentially expressed proteins by at least two-fold. Among them, calpain small subunit 1 (Capn4), a protein with relevant interactions with many migration–invasion-related proteins, has attracted more attention. First, Capn4 overexpression in the recurrence group was confirmed via real-time polymerase chain reaction and western blotting in another cohort of 40 HCC patients undergoing LT. Second, Capn4 was associated with enhanced invasiveness in vitro. The small interfering RNA–mediated knockdown expression of Capn4 in HCC cell lines significantly inhibited its mobile and invasive ability. Tissue microarray in a further 192 cases revealed that Capn4 significantly correlated with invasive phenotype of HCC, and univariate and multivariate analyses indicated that Capn4 is an independent prognostic factor for recurrence and survival of HCC patients. Conclusion: Our study revealed that Capn4 overexpression underlies invasion and metastasis after LT for HCC and might be a candidate biomarker for future diagnosis and a target for therapy. (Hepatology 2008.)
Relationship of SNCG, S100A4, S100A9 and LCN2 gene expression and DNA methylation in bladder cancer
Authors: Dokun Olusola Y. , Florl Andrea R. , Seifert Hans‐Helge , Wolff Ingmar , Schulz Wolfgang A. 
Published: September 2008

AbstractMicroarray analysis of paired cultures of normal and cancerous urothelial cells revealed differences in cytokeratin and adhesion gene expression. Normal cells expressed autocrine growth factor genes more strongly whereas carcinoma cells were distinguished by concomitant expression of urothelial and epidermal differentiation markers. Expression of SNCG, S100A9 and LCN2 was also enhanced. In other cancers, overexpression of SNCG, LCN2 and S100A4 has been ascribed to DNA hypomethylation. We therefore investigated expression and methylation of SNCG, S100A4, S100A9 and LCN2 in urothelial cancer cell lines and tissues. SNCG and S100A4 were overexpressed in some cancer tissues and cell lines, but downregulated in others, whereas LCN2 and S100A9 were upregulated in few cancer cell lines, but regularly in tissues. Normal and cancerous urothelial cells expressing SNCG lacked promoter methylation. SNCG downregulation was associated with hypermethylation and could be reversed by the DNA methyltransferase inhibitor 5‐aza‐2′‐deoxycytidine. S100A4 methylation at regulatory intronic sites and in the promoter region was lowest in leukocytes and fibroblasts, and denser in urothelial cells. Gene expression responded to 5‐aza‐2′‐deoxycytidine. LCN2 promoter methylation was variable and even less consistently related to expression. The S100A9 promoter was partially methylated in nonexpressing cells, but 5‐aza‐2′‐deoxycytidine had no effect. Our data indicate that SNCG methylation is cell type‐specific and the gene is hypermethylated in some urothelial cancers. S100A4, S100A9 and LCN2 are genes with moderate CpG‐density that show a less stringent relationship between DNA methylation and gene expression. Therefore, changes in methylation of these genes in cancer should be interpreted cautiously. © 2008 Wiley‐Liss, Inc.
Chemoresistant tumor cell lines display altered epidermal growth factor receptor and HER3 signaling and enhanced sensitivity to gefitinib
Authors: Servidei Tiziana , Riccardi Anna , Mozzetti Simona , Ferlini Cristiano , Riccardi Riccardo 
Published: September 2008

AbstractDeregulated signaling through the epidermal growth factor receptor (EGFR) is involved in chemoresistance. To identify the molecular determinants of sensitivity to the EGFR inhibitor gefitinib (Iressa, ZD1839) in chemoresistance, we compared the response of matched chemosensitive and chemoresistant glioma and ovarian cancer cell lines. We found that chemoresistant cell lines were 2‐ to 3‐fold more sensitive to gefitinib growth‐inhibitory effects, because of decreased proliferation rather than survival. Sensitivity to gefitinib correlated with overexpression and constitutive phosphorylation of HER2 and HER3, but not EGFR, altered HER ligand expression, and enhanced activation of EGF‐triggered EGFR pathway. No activating mutations were found in EGFR. Gefitinib fully inhibited EGF‐induced and constitutive Akt activation only in chemoresistant cells. In parallel, gefitinib downregulated constitutively phosphorylated HER2 and HER3, and activated GSK3β with a concomitant degradation of cyclin D1. Ectopically overexpressed HER2 on its own was insufficient to sensitize chemonaive cells to gefitinib. pHER3 coimmunoprecipitated with p85‐PI3K in chemoresistant cells and gefitinib dissociated these complexes. siRNA‐mediated inhibition of HER3 decreased constitutive activation of Akt and sensitivity to gefitinib in chemoresistant cells. Our study indicates that in chemoresistant cells gefitinib inhibits both an enhanced EGF‐triggered pathway and a constitutive HER3‐mediated Akt activation, indicating that inhibition of HER3 together with that of EGFR could be relevant in chemorefractory tumors. Furthermore, in combination experiments gefitinib enhanced the effects of coadministered drugs more in chemoresistant than chemosensitive ovarian cancer cells. Combined treatment might be therapeutically beneficial in chemoresistant tumors from ovary and likely from other tissues. © 2008 Wiley‐Liss, Inc.
Endoglin (CD105) as a urinary and serum marker of prostate cancer
Authors: Fujita Kazutoshi , Ewing Charles M. , Chan David Y.S. , Mangold Leslie A. , Partin Alan W. , Isaacs William B. , Pavlovich Christian P. 
Published: September 2008

AbstractWe have previously shown that endoglin (CD105) is upregulated in prostatic fluid of men with large volume prostate cancer. We chose to assess endoglin levels in urine and serum from men with prostate cancer or at increased risk for the disease: Urine samples were collected after digital rectal examination (DRE) from 99 men whose cancer status was confirmed by biopsy, and serum samples were collected from 20 men without prostate cancer at low risk for the disease and from 69 men diagnosed with prostate cancer that subsequently underwent radical prostatectomy (30 pT2, 39 pT3). Endoglin levels were assessed by ELISA. Urinary endoglin was elevated in men with biopsy‐positive prostate cancer compared to biopsy‐negative men (p = 0.0014). Urinary endoglin levels in men with prostate cancer correlated with radical prostatectomy tumor volume. The area under the receiver operating characteristic (ROC) curve was 0.72 for urinary endoglin and 0.50 for serum prostate‐specific antigen (PSA; sensitivity for cancer detection 73%, specificity 63%). There were no differences in serum endoglin between normal and cancer cases, but there were increases in serum endoglin in non‐organ confined (NOC, pT3+) versus organ‐confined (OC, pT2) cases (p = 0.0004). The area under the ROC curve was 0.75 for serum endoglin and 0.63 for PSA for predicting NOC status, with a sensitivity of 67% and a specificity of 80%. In conclusion, elevations in post‐DRE urinary endoglin suggest there may be value in further studying endoglin as a urinary biomarker of prostate cancer. Endoglin levels in both urine and serum may aid in prostate cancer detection and prognostication. © 2008 Wiley‐Liss, Inc.