bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mass transfer characteristics of plasmids in monoliths
Authors: Zöchling Alfred , Hahn Rainer , Ahrer Karin , Urthaler Jochen , Jungbauer Alois 
Published: July 2004

AbstractThe hydrodynamic properties and pore‐structure of monoliths based on functionalized poly(glycidyl methacrylate‐ethylene dimethacrylate) were characterised by pulse response experiments using different probes representing a wide range of molecular mass. On a small scale, band spreading was found to be caused to the extent of more than 90% by extra‐column effects. These monoliths have large channel diameters, providing a suitable chromatography adsorbent for processing of large molecules. Dynamic and static binding capacity for plasmid DNA was investigated. For our model plasmid, consisting of 4.9 kbp, a capacity of 7 mg/mL was observed in comparison to 0.3 mg/mL for a conventional medium designed for protein separation. When plasmids were loaded on the monolith a gradual increase in pressure drop was observed. The channels filled up and the cross‐sectional area available for liquid flow decreased. Therefore, a higher pressure drop was observed during elution. This is caused by (i) shrinking of the channels as effect of the high salt concentration, (ii) high viscosity of the mobile phase due to high concentration of plasmids, and (iii) an increase of the hydrodynamic radius of the plasmid with salt concentration from 45 nm at 150 mM to 70 nm at 2 M NaCl, as measured by dynamic light scattering. These types of monoliths are considered to be the preferred adsorbents for plasmid separation.
Comparison of monolithic silica and polymethacrylate capillary columns for LC
Authors: Moravcová Dana , Jandera Pavel , Urban Jiří , Planeta Josef 
Published: July 2004

AbstractOrganic polymer monolithic capillary columns were prepared in fused‐silica capillaries by radical co‐polymerization of ethylene dimethacrylate and butyl methacrylate monomers with azobisisobutyronitrile as initiator of the polymerization reaction in the presence of various amounts of porogenic solvent mixtures and different concentration ratios of monomers and 1‐propanol, 1,4‐butanediol, and water. The chromatographic properties of the organic polymer monolithic columns were compared with those of commercial silica‐based particulate and monolithic capillary and analytical HPLC columns. The tests included the determination of H‐u curves, column permeabilities, pore distribution by inversed‐SEC measurements, methylene and polar selectivities, and polar interactions with naphthalenesulphonic acid test samples. Organic polymer monolithic capillary columns show similar retention behaviour to chemically bonded alkyl silica columns for compounds with different polarities characterized by interaction indices, Ix, but have lower methylene selectivities and do not show polar interactions with sulphonic acids. The commercial capillary and analytical silica gel‐based monolithic columns showed similar selectivities and provided symmetrical peaks, indicating no significant surface heterogeneities. To allow accurate characterization of the properties of capillary monolithic columns, the experimental data should be corrected for extra‐column contributions. With 0.3 mm ID capillary columns, corrections for extra‐column volume contributions are sufficient, but to obtain true information on the efficiency of 0.1 mm ID capillary columns, the experimental bandwidths should be corrected for extra‐column contributions to peak broadening.
Characterization of methacrylate monoliths for purification of DNA molecules
Authors: Benčina Mojca , Podgornik Aleš , Štrancar Aleš 
Published: July 2004

AbstractThe suitability of methacrylate based anion exchange monolithic supports for the separation and purification of plasmid and genomic DNA has been explored. The effect of the size of the channels, ionic strength of the solution, and ligand density on the dynamic binding capacity has been investigated. The dynamic binding capacity was found to be flow independent, at least up to a linear velocity of 700 cm h–1, and exceeded 9 mg mL–1 for all types of DNA. The recovery depends on the pH value of the mobile phase and its ionic strength as well as on the density of the active groups. Under optimal conditions recoveries exceeding 80% were obtained even for genomic DNA. Finally, the suitability of this approach is demonstrated by purification of a real‐life sample.
Rapid, low pressure, and simultaneous ion chromatography of common inorganic anions and cations on short permanently coated monolithic columns
Authors: Connolly Damian , Victory Danielle , Paull Brett 
Published: July 2004

AbstractShort permanently coated reversed‐phase silica based monolithic columns have been investigated for the rapid separation of inorganic anions and cations. One 2.5×0.46 cm column was permanently coated with didodecyldimethylammonium (DDAB), for anion analysis; and a second 5.0×0.46 cm column was coated with dioctylsulphosuccinnate (DOSS), for cation analysis. The use of a single combined eluent of 2.5 mM phthalate/1.5 mM ethylenediamine, at flow rates of between 4.0 and 8.0 mL/min, resulted in the rapid separation of 8 anions (in under 100 s) and 5 cations (in under 100 s) on the above columns when used individually, with detection limits for common anions ranging from approximately 0.25 to 5 mg/L, and between 2.5 and 50 mg/L for alkaline earth metals, by direct and indirect conductivity detection, respectively. However, with both columns subsequently connected in parallel, with the eluent delivered using a flow splitter from a single isocratic pump, the simultaneous analysis of anions and cations was also possible, based on a single conductivity detector. The potential of this system for the rapid, complete screening of water samples for multiple common anions and cations is shown.
A computational study of the porosity effects in silica monolithic columns
Authors: Gzil Piotr , Vervoort Nico , Baron Gino V. , Desmet Gert 
Published: July 2004

AbstractWe report on a theoretical study of the influence of the through‐pore porosity on the main chromatographic performance parameters (reduced theoretical plate height, flow resistance, and separation impedance) of silica monoliths. To investigate this problem devoid of any structural uncertainties, computer‐generated structural mimics of the pore geometry of silica monolithic columns have been studied. The band broadening in these synthetic monoliths was determined using a commercial Computational Fluid Dynamics (CFD) software package. Three widely differing external porosities (ε = 0.38, ε = 0.60, and ε = 0.86) are considered and are compared on the basis of an identical intra‐skeleton diffusivity (D s = 5×10–10m2/s), internal porosity (εint = 0.5), and for the same phase retention factor (k ´ = 1.25). Since the data are obtained for perfectly ordered structures, the calculated plate heights and separation impedances constitute the ultimate performance ever to be expected from a monolithic column. It is found that, if silica monoliths could be made perfectly homogeneous, domain size‐based reduced plate heights as small as h min ≈ 0.8 (roughly independent of the porosity) and separation impedances as small as Emin ≈ 130 (ε = 0.60) and Emin ≈ 40 (ε = 0.86) should be achievable with pure water as the working fluid. The data also show that, although the domain size is a much better reduction basis than the skeleton size, the former is still not capable of bringing the van Deemter curves of different porosity columns into perfect agreement in the C term dominated velocity range. It is found that, in this range, large porosity monoliths can be expected to yield smaller domain size‐based reduced plate heights than small porosity monoliths.
Ion exchange properties of monolithic and particle type iminodiacetic acid modified silica
Authors: Sugrue Edel , Nesterenko Pavel , Paull Brett 
Published: July 2004

AbstractA 10 cm silica monolith has been modified with iminodiacetic acid (IDA) groups and characterised for its selectivity toward alkali, alkaline earth, and selected transition metal cations. Physical characterisation of the modified monolith found non‐homogeneous modification along the length of the monolith, although sufficient capacity was achieved to facilitate significant retention of alkaline earth and transition/heavy metal ions over a range of eluent pH and ionic strength conditions. For alkaline earth and transition/heavy metal ions, selectivity of the 10 cm IDA monolith closely matched that seen with a 25 cm IDA modified silica gel particle packed column, although the separation of alkali metal ions was noticeably poorer on the monolithic column. Peak efficiencies for most metal ions were of a similar order for both column types, except for Zn(II), which showed significant peak broadening on the IDA monolithic column.
Enzyme immobilization on epoxy‐ and 1,1′‐carbonyldiimidazole‐activated methacrylate‐based monoliths
Authors: Benčina Katja , Podgornik Aleš , Štrancar Aleš , Benčina Mojca 
Published: July 2004

AbstractMonolithic Convective Interaction Media (CIM) have been activated with epoxide and imidazole carbamate functionalities and used as supports for covalent immobilization of protein A, deoxyribonuclease I, and trypsin. The efficiency of immobilization for these proteins was determined from the amount of bound IgG, degradation of DNA, and hydrolysis of Nα‐benzoyl‐L‐arginine ethyl ester, respectively. The respective biological activities of trypsin and the binding capacity of protein A immobilized via imidazole carbamate groups were 11.45 and 2.25 times higher than those obtained for epoxide matrix while they were practically equal for deoxyribonuclease I. The kinetics of immobilization was studied in detail for trypsin under dynamic conditions and revealed that the enzyme immobilized via imidazole carbamate groups already reached its highest activity in 5 min. In contrast, a much longer time was required for immobilization via epoxy groups.
Structural formation of hybrid siloxane‐based polymer monolith in confined spaces
Authors: Kanamori Kazuyoshi , Yonezawa Hideyuki , Nakanishi Kazuki , Hirao Kazuyuki , Jinnai Hiroshi 
Published: July 2004

AbstractStructural deformation of phase‐separated methylsiloxane gel under the influence of a surface has been studied. Competitive wetting of siloxane gel phase on a surface during phase formation is found to significantly affect the final morphology in a confined space. When the spinodal wavelength is sufficiently shorter than the size of the available space, a uniform bicontinuous structure forms in confined geometry. However, gel skeletons in the vicinity of a surface are elongated with decreasing size of the space, and finally when the size of the space becomes shorter than the spinodal wavelength, all the gel phase wets on a surface, showing a “wetting transition”. Homogeneous bicontinuous methylsiloxane gels were successfully prepared, avoiding such structural deformation, in a long cylindrical fused silica capillary and used for capillary HPLC. The capillary gels exhibited excellent separation efficiency of nitrobenzenes and it was found that the surface character can be altered by incorporating surfactants, which will enable more advanced and extended control of surface character, depending on the analytes.
High‐performance liquid chromatographic enantioseparations on capillary columns containing monolithic silica modified with cellulose tris(3,5‐dimethylphenylcarbamate)
Authors: Chankvetadze Bezhan , Yamamoto Chiyo , Tanaka Nobuo , Nakanishi Kazuki , Okamoto Yoshio 
Published: July 2004

AbstractMonolithic capillary columns containing native silica gel were modified with cellulose tris(3,5‐dimethylphenylcarbamate) (CDMPC) and used for enantioseparations in capillary liquid chromatography. The method adopted for in situ enantioselective modification of monolithic fused silica capillary columns by coating with CDPMC appears to be fairly simple and fast. High efficiency enantioseparations of test racemic compounds and several chiral drugs were achieved in a short time. It was possible to increase the amount of chiral selector present by multiple coating of monoliths with CDMPC. The baseline enantioseparation of 2,2,2‐trifluoro‐1‐(9‐anthryl)ethanol was achieved in an analysis time less than 30 s with this capillary column. In addition, reproducible enantioseparations were obtained when the chiral selector was removed from the monolithic column by flushing it with appropriate solvent and the column recoated.
Monolithic columns with a gradient of functionalities prepared via photoinitiated grafting for separations using capillary electrochromatography
Authors: Pucci Vincenzo , Raggi Maria Augusta , Svec Frantisek , Fréchet Jean M.J. 
Published: July 2004

AbstractStationary phases for capillary electrochromatography with a longitudinal gradient of functionalities have been prepared via photoinitiated grafting of polymer chains onto the pore surface of a porous polymer monolith. In order to achieve the desired retention and electroosmotic flow, the hydrophobic poly(butyl methacrylate‐co‐ethylene dimethacrylate) monolith with optimized porous properties was grafted with a layer of ionizable polymer, poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid). A moving shutter and a neutral density filter were used to control the dose of UV light received at different locations along the monolith in order to create the longitudinal gradient of functionalities. Formation of the desired gradients was confirmed using electron probe microanalysis of different locations along the column. The preparation technique significantly affects performance in the CEC mode as demonstrated on the separations of a model mixture using columns both with homogeneous distribution of grafts and with a gradient of functionality. Columns grafted with the gradient of functionalities were found superior to those functionalized uniformly. A comparison of the performance of the gradient column with another containing evenly distributed functionalities showed the performance benefits of the “gradient” column.
Simple 2D‐HPLC using a monolithic silica column for peptide separation
Authors: Kimura Hiroshi , Tanigawa Tetsuya , Morisaka Hironobu , Ikegami Tohru , Hosoya Ken , Ishizuka Norio , Minakuchi Hiroyoshi , Nakanishi Kazuki , Ueda Mitsuyoshi , Cabrera Karin , Tanaka Nobuo 
Published: July 2004

AbstractSeparation of peptides by fast and simple two‐dimensional (2D)‐HPLC was studied using a monolithic silica column as a second‐dimension (2nd‐D) column. Every fraction from the first column, 5 cm long (2.1 mm ID) packed with polymer‐based cation exchange beads, was subjected to separation in the 2nd‐D using an octadecylsilylated (C18) monolithic silica column (4.6 mm ID, 2.5 cm). A capillary‐type monolithic silica C18 column (0.1 mm ID, 10 cm) was also employed as a 2nd‐D column with split flow/injection. Effluent of the first dimension (1st‐D) was directly loaded into an injector loop of 2nd‐D HPLC. UV and MS detection were successfully carried out at high linear velocity of mobile phase at 2nd‐D using flow splitting for the 4.6 mm ID 2nd‐D column, or with direct connection of the capillary column to the MS interface. Two‐minute fractionation in the 1st‐D, 118‐second loading, and 2‐second injection by the 2nd‐D injector, allowed one minute for gradient separation in the 2nd‐D, resulting in a maximum peak capacity of about 700 within 40 min. The use of a capillary column in the 2nd‐D led to less solvent consumption and better MS detectability compared to a larger‐sized column. This kind of fast and simple 2D‐HPLC utilizing monolithic silica columns will be useful for the separation of complex mixtures in a short time.
Cover Picture: Macromol. Mater. Eng. 7/2004
Authors: Ding Shi‐You , Rumbles Garry , Jones Marcus , Tucker Melvin P. , Nedeljkovic Jovan , Simon Martha N. , Wall Joseph S. , Himmel Michael E. 
Published: July 2004

Cover: Graphical representation of a novel bioconjugate consisting of a genetically modified cohesin/dockerin polymer surrounding a single (CdSe)ZnS colloidal quantum dot (QD). Strong binding between protein monomers to form polymers and also with QDs provides a method of producing stable, water‐soluble and luminescent QD species amenable to chromatographic separation.Further details can be found in the Full Paper by S.‐Y. Ding, G. Rumbles, M. Jones, M. P. Tucker, J. Nedeljkovic, M. N. Simon, J. S. Wall, and M. E. Himmel* on page 622.
Toxicity and efficacy of intensive chemotherapy for children with acute lymphoblastic leukemia (ALL) after first bone marrow or extramedullary relapse
Authors: Thomson Blythe , Park Julie R. , Felgenhauer Judy , Meshinchi Soheil , Holcenberg John , Geyer J. Russell , Avramis Vassilios , Douglas James G. , Loken Michael R. , Hawkins Douglas S. 
Published: July 2004

AbstractBackgroundApproximately 25% of children newly diagnosed with acute lymphoblastic leukemia (ALL) will eventually experience leukemic relapse, with bone marrow being the most common site of recurrence. The ability to achieve a durable second remission is complicated by toxicity and resistant disease. We report a novel combination of chemotherapy for relapsed pediatric ALL.ProcedureThirty pediatric patients with relapsed medullary (n = 18) and extra‐medullary (n = 12) ALL were enrolled at three pediatric institutions. Following receipt of induction and the first Block A and Block B of intensification, each patient was evaluated for toxicity, efficacy in achieving remission, and long‐term survival. Additionally, minimal residual disease (MRD) detection by multidimensional flow cytometry (MDF) was performed.ResultsDuring induction, the major non‐hematopoeitic toxicities were mucositis (30% of patients) and bacteremia (50% of patients). Two patients (7%) died of toxicity during induction. Toxicity during intensification Block 1A and 1B was markedly reduced. Eight‐nine percent of patients with marrow disease achieved a remission following induction and intensification. The event‐free survival (EFS) for all patients at 2 and 4 years were 60% (95% CI: 42–78%) and 49% (95% CI: 30–68%), respectively.ConclusionsThis regimen for patients with relapsed ALL was successful in achieving a second remission for the majority of patients with acceptable toxicity. © 2004 Wiley‐Liss, Inc.
Health status of young children during therapy for advanced neuroblastoma
Authors: Nathan P.C. , Furlong W. , De Pauw S. , Horsman J. , Van Schaik C. , Rolland M. , Weitzman S. , Feeny D. , Barr R.D. 
Published: July 2004

AbstractBackgroundThe purpose of this study was to describe the health status experienced by young children during various phases of therapy for advanced neuroblastoma.MethodsNineteen patients aged 2.00–4.99 years at the time of diagnosis of neuroblastoma (stages 3 or 4) who received active therapy between 1996 and 2000 were enrolled on the study. Their parents provided proxy assessments of their health status at a maximum of 10 assessment points during therapy using the Comprehensive Health Status Classification System for Pre‐school Children (CHSCS‐PS), which assesses level of function on 10 separate health domains.ResultsEighty‐six assessment questionnaires were completed. Maximum morbidity was reported immediately following diagnosis and in the 2–3 weeks following bone marrow transplantation. The greatest morbidity was observed in the pain, self‐care, mobility, and emotion domains.ConclusionsIn addition to facing a high risk of mortality, young children being treated for advanced neuroblastoma also experience considerable morbidity. © 2004 Wiley‐Liss, Inc.
Identification of metastasis‐associated proteins in a human tumor metastasis model using the mass‐mapping technique
Authors: Kreunin Paweena , Urquidi Virginia , Lubman David M , Goodison Steve 
Published: July 2004

AbstractFor most cancer cell types, the acquisition of metastatic ability leads to clinically incurable disease. The identification of molecules whose expression is specifically correlated with the metastatic spread of cancer would facilitate the design of therapeutic interventions to inhibit this lethal process. In order to facilitate metastasis gene discovery we have previously characterized a pair of monoclonal cell lines from the human breast carcinoma cell line MDA‐MB‐435 that have different metastatic phenotypes in immune‐compromised mice. In this study, serum‐free conditioned media was collected from the cultured monoclonal cell lines and a mass mapping technique was applied in order to profile a component of each cell line proteome. We utilized chromatofocusing in the first dimension to obtain a high resolution separation based on protein pI, and nonporous silica reverse‐phase high performance liquid chromatography was used for the second dimension. Selected proteins were identified on the basis of electrospray ionization time of flight mass spectrometry (ESI‐TOF MS) intact protein mapping and matrix‐assisted laser desorption/ionization time of flight mass spectrometry (MALDI‐TOF MS) peptide mass fingerprinting. Using this approach we were able to map over 400 proteins and plot them as a 2‐D map of pI versus accurate Mr. This was performed over a pI range of 4.0–6.2, and a mass range of 6–80 kDa. ESI‐TOF MS data and further analysis using MALDI‐TOF MS confirmed and identified 27 differentially expressed proteins. Proteins associated with the metastatic phenotype included osteopontin and extracellular matrix protein 1, whereas the matrix metalloproteinase‐1 and annexin 1 proteins were associated with the non‐metastatic phenotype. These findings demonstrate that the mass mapping technique is a powerful tool for the detection and identification of proteins in complex biological samples and which are specifically associated with a cellular phenotype.
Wheat leaf proteome analysis using sequence data of proteins separated by two‐dimensional electrophoresis
Authors: Bahrman Nasser , Negroni Luc , Jaminon Odile , Le Gouis Jacques 
Published: July 2004

AbstractIdentifying wheat leaf protein expression is a major challenge of functional genomics. Using two‐dimensional gel electrophoresis 541 wheat leaf proteins were separated and 55 of them were sequenced by nano liquid chromatography‐tandem mass spectrometry. Peptide sequence data were screened against protein banks and expressed sequence tag public banks. Among these 55 spots, 20 proteins were found in wheat and 21 in other grass families (http://www.ncbi.nlm.nih.gov/). Twelve proteins showed similarities with other eukaryotic plant species. One protein showed homology to a bacterial sequence and another protein remained unknown. In 18 cases a significant score was found for the wheat TUC (Tentative Unique Contigs) of the PlantGDB (http://www.plantgdb.org/) data. In several cases, different spots were identified as corresponding to the same protein that can probably be attributed to the hexaploid structure of wheat. The identified proteins were classified in six groups and their role is discussed. Most of them (31/55) are involved in carbohydrate metabolism.