bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessment of impact of physico‐chemical drug properties on monitoring drug levels by micellar electrokinetic capillary chromatography with direct serum injection
Authors: Schmutz André , Thormann Wolfgang 
Published: May 2005

AbstractThe impact of physico‐chemical properties of 25 compounds, including antiepileptic, anti‐inflammatory and beta‐blocking drugs, on their determination by micellar electrokinetic capillary chromatography (MECC) with direct serum injection (DSI) is discussed. Having a pH 9.2 buffer containing 75 mM sodium dodecyl sulfate (SDS), elution is dependent on hydrophobicity, the order of emergence being basically according to increasing octanol/water partition coefficients (logP values). Peak shape is determined by the dissociation behavior (expressed by pKa) and plasma protein binding (PPB). Sharp peaks are produced by compounds having low PPB and, independently of PPB, by drugs with pKa values which are similar to the buffer pH. Broad or double peaks are established by drugs of low pKa values and significant (> about 40%) PPB. In order to evaluate the effective amount of a protein‐bound drug measured by MECC‐DSI, serum levels of drugs with different PPB, namely ethosuximide (no PPB), phenobarbital (PPB of about 50%) and naproxen (PPB > 99%) have been determined by both MECC‐DSI and MECC with extract injection (MECC‐EXI). In each case, with more than 40 sera, there is good agreement between the two sets of data. Thus, employing MECC‐DSI, total amounts of drugs are determined, i.e. a complete release of the drugs from the proteins is effected by the impact of dodecyl sulfate on the sampled proteins.
Determination of benzodiazepines by micellar electrokinetic chromatography
Authors: Bechet Isabelle , Fillet Marianne , Hubert Philippe , Crommen Jacques 
Published: May 2005

AbstractA method for the separation and determination of benzodiazepines by micellar electrokinetic chromatography (MEKC) has been developed. Separation buffers consisted of aqueous solutions of glycine and triethanolamine (pH 9.0), containing sodium dodecyl sulfate (SDS) as surfactant and methanol as organic modifier. The effect of the concentration of SDS, methanol, glycine and triethanolamine on migration times and resolution was studied. Ten benzodiazepines were baseline separated at a 25 mM SDS concentration and 20% v/v methanol in a 75mM glycine‐250 mM triethanolamine buffer. Under these conditions, the within‐day reproducibilities were 0.3–0.5% for migration times and 1.7–1.9% for peak areas at a concentration of 10 μg/mL. The limits of detection and quantification for oxazepam were 0.2 and 0.7 μg/mL, respectively, using an injection time of 5s.
Analysis of lower aliphatic aldehydes in water by micellar electrokinetic chromatography with derivatization to 2,4‐dinitrophenylhydrazones
Authors: Takeda Sahori , Wakida Shin‐ichi , Yamane Masataka , Higashi Kunishige 
Published: May 2005

AbstractThe analysis of lower aliphatic aldehydes in water following derivatization to 2,4‐dinitrophenylhydrazones, was investigated by micellar electrokinetic chromatography (MEKC). The effects of the buffer pH and acetonitrile addition on the separation were investigated. Under optimized conditions the 2,4‐dinitrophenylhydrazine (DNPH) reagent was completely separated from four DNPH derivatized aldehydes with high separation efficiency. DNPH‐formaldehyde and DNPH‐acetaldehyde were also completely separated from one another. Their relative standard deviation of migration times and peak areas were within 1.0% and 3.3%, respectively. The reproducibility of peak areas in this MEKC analysis was as good as that of high‐performance liquid chromatography (HPLC) analysis with the same derivatization method. The recovery values from tap and river water were in the range of 97–102%. The detection limits of formaldehyde and acetaldehyde were 0.05 mg/L and 0.08 mg/L respectively.
Enantiomeric separation of drugs by affinity electrokinetic chromatography using dextran sulfate
Authors: Nishi Hiroyuki , Nakamura Kouji , Nakai Hideo , Sato Tadashi , Terabe Shigeru 
Published: May 2005

AbstractDextran sulfate (sodium salt), which is a mixture of a linear α‐(1,6)‐linked D‐glucose polymer having a sulfate group in the molecule, has been employed as a chiral selector in affinity electrokinetic chromatography (EKC) for the separation of enantiomers of drugs. Enantiomers of trimetoquinol hydrochloride and its positional isomer have been successfully separated by the method using a 3–5% dextran sulfate buffer solution of pH 5.5 within 20 min. The effects of buffer pH, concentration of dextran sulfate, and additives (such as an organic solvent, urea and a surfactant) on the enantioselectivity were investigated. The choice of pH and the concentration of dextran sulfate has been important for the improvement in selectivity.
Altered electrophoretic behavior of DNA due to short‐time UV‐B irradiation
Authors: Mäueler Winfried , Kyas Andreas , Bröcker Frank , Epplen Jörg T. 
Published: May 2005

AbstractUV‐B irradiation is often inevitable for visualization of DNA fragments after ethidium bromide staining. Three different simple‐repeat‐containing, double‐stranded genomic DNA fragments were analyzed for UV‐B (312 nm) damage using different gel electrophoretic systems. The effects of UV‐B light were obvious after 5 min (31.5 kJ/m2) of irradiation in native polyacrylamide gel electrophoresis (PAGE). Standard single‐strand conformation analyses revealed no alterations while a modification did. Sodium dodecyl sulfate (SDS)‐PAGE was found to be highly sensitive with regard to the detection of damages and their time/dosage dependency. In addition, SDS‐PAGE analysis pointed to different events occurring during UV‐B irradiation. Alterations in DNA conformation were detected in every single strand analyzed after 1 min (6.3 kJ/m2) of UV‐B exposure. Gel retardation analyses revealed significant changes of protein binding to target DNAs after 2 min of irradiation – possibly stemming from structural modifications and/or originating from binding sites for proteins involved in DNA repair.
Capillary electrophoresis separation of oligosaccharides: I. Effect of operational variables
Authors: Guttman András , Cooke Nelson , Starr Christopher M. 
Published: May 2005

AbstractThe influence of operating variables on the separation of labeled oligosaccharide molecules in capillary electrophoresis with polymer networks is presented. In this study, an equation was derived that relates the effects of electrophoresis variables such as field strength, temperature, molecular weight and gel concentration to the migration velocity. As a model system, 8‐aminonaphthalene‐1,3,6‐trisulfonate ANTS‐labeled wheat starch digest was examined to show the validity of the equation. As an illustration of the high resolving power achievable with capillary electrophoresis, oligosaccharide molecules up to the degree of polymerization of 25 were separated with the very high efficiency of N>106 and efficiency generation rate of 3500 plates/m/s for maltose. Separation based on the size of the oligosaccharides was not obtained with either entangled or unentangled polymer solutions.
Isoelectrc focusing in immobilized pH gradient of melon (Cucumis melo L.) seed protein: Methodical and genetic aspects, and application in breeding
Authors: van den Berg Bartel M. , Gabillard Daniel 
Published: May 2005

AbstractGenetic variability of melon seed proteins was studied by separation of seed protein by isoelectric focusing in immobilized pH gradient (IEF‐IPG) under denaturing conditions. A routine procedure was developed for IEF‐IPG of hundreds of individual melon seeds per day. A group of 74 accessions from 19 morphologically distinct groups and from different geographic origin were studied by IEF‐IPG using pH gradients of 4–10, 4–7 and 6–10. The electrophoretic analysis of the 74 accessions showed 270 reproducible seed protein bands of which 70 were variable. Genetic evaluation led to the conclusion that at least 20 loci govern the variation found. The phylogenetic trees constructed using the protein data on one hand and the morphological data on the other hand were compared and their use was evaluated. A number of commercial Cantaloup F1 hybrid descendants derived from the F1 hybrids by diplohaploidization or single plot descent were studied by IEF‐IPG using pH gradients of 4–7 and 6–10. Among the F1 hybrids and their descendants 265 reproducible protein bands could be identified of which 72 were variable as to presence versus absence. The genetic interpretation of the protein pattern as found by IEF‐IPG and the use of IEF‐IPG in plant breeding was discussed. It was concluded that IEP‐IPG of melon seed proteins is a valuable tool in breeding.
Response of bacteria and fungi to high‐pressure stress as investigated by two‐dimensional polyacrylamide gel electrophoresis
Authors: Groß Michael , Kosmowsky Ilona J. , Lorenz Rainer , Molitoris Hans Peter , Jaenicke Rainer 
Published: May 2005

AbstractIn an attempt to generalize previous observations (Jaenicke et al., Appl. Environ. Microbiol. 1988, 54, 2375–2380) and to find a convenient model system for studies of the pressure response, we tested the suitability of Escherichia coli and Thermotoga maritima (bacteria), and of five different eukaryotic species including the filamentous fungi Asteromyces cruciatus and Dendryphiella salina., and the marine yeasts Debaryomyces hansenii, Rhodosporidium sphaerocarpum, and Rhodotorula rubra. Using two‐dimensional polyacrylamide gel electrophoresis, detailed investigations on the pressure response were carried out with E. coli and Rhodosporidium sphaerocarpum. In the former organism, major pressure response proteins could not be detected, although there are significant differences in expression of some proteins as well as some minor components that are found in all of the high pressure cell extracts but not in extracts from cultures grown at atmospheric pressure. In Rhodosporidium sphaerocarpum, no change in protein expression patterns was observed between 0.1 and 20 MPa. However, approaching the limit of viability of 50 MPa, additional protein spots became detectable at 45 MPa. This finding correlates with the observation of abnormal growth forms of the organism at this pressure (Lorenz, R. et al. manuscript in preparation).
Protein studies of human non‐Hodgkin's B‐lymphoma: Appraisal by two‐dimensional gel electrophoresis
Authors: Mohammad Ramzi M. , Maki Auday , Vistisen Kerry , Al‐Katib Ayad 
Published: May 2005

AbstractWe have utilized two‐dimensional polyacrylamide gel electrophoresis (2‐D PAGE) coupled with silver stain to identify cellular proteins in human non‐Hodgkin's B‐lymphoma (NHL). Five cell lines (SKDHL2B, WSU‐DLCL2, WSU‐NHL, WSU‐FSCCL and SKLN1), representing four different NHL maturational stages and a normal Epstein‐Barr virus (EBV)‐transformed line of B‐cell origin (SKLN1) were studied. The NHL lines were immunophenotyped using flow cytometry with lineage associated monoclonal antibodies. Whole cell lysates of the cell lines were subjected to 2‐D PAGE analyses. The gels were analyzed with an image scanning computer and the qualitative differences of protein patterns were studied. Results revealed great similarities in patterns of the NHL lines. A master map containing common NHL‐protein spots was constructed. When the map of each tumor line was compared to the master map, several protein spots were associated with each NHL‐grade. Search for these proteins in the normal EBV‐transformed B‐cell line showed that only one of the proteins (S3; Mr/pI 19/5.9) was present. Proteins that were detected in malignant NHL, but not in the normal EBV‐line, could provide important information regarding the human NHL B‐lymphocyte databases. Whether or not these proteins are definite malignant markers to distinguish between different NHL maturational stages needs further exploration through electroblotting and microsequencing.
Sponge‐like electrophoresis media: Mechanically strong materials compatible with organic solvents, polymer solutions and two‐dimensional electrophoresis
Authors: Harrington Michael G. , Lee Kelvin H. , Bailey James E. , Hood Leroy E. 
Published: May 2005

AbstractA new range of sponge‐like media, called “electrophoresis sponges”, is presented. They differ from electrophoresis gels primarily in that they are mechanically stronger, providing a permanent structure of directly measurable pore size dimensions. The new media are similar to capillary electrophoresis in terms of pore size range, they are mechanically strong with directly definable walls, and are compatible with polymer solutions. The sponges differ from capillary electrophoresis in that they provide large numbers of channels, with a corresponding high load capacity for simultaneous runs in multiple channels and they are compatible directly with multi‐dimensional separations, such as high resolution two‐dimensional electrophoresis. Furthermore, they can be molded (or cut) to any shape and retain that shape, they can be handled more easily than gels, they can be reused if necessary, they can be distributed in the same format between labs easily, and they can be stored indefinitely. Chemically, they can be hydrophilic or hydrophobic, with capability ranging from inert to reactive surfaces. Pore sizes can range from the sub‐nanometer to 100 micron scale. Results with various hydrophobic sponges are reported for the carrier ampholyte‐based isoelectric focusing of proteins. Broad and narrow pH gradients are established in the sponges that are more linear than those achieved with polyacrylamide gels. One‐ and two‐dimensional electrophoresis of proteins has been achieved, for example with high resolution of the charge isomers of the haptoglobin beta chain, using sponge‐based isoelectric focusing. Isoelectric focusing is about threefold faster in the tested sponges than in equivalent polyacrylamide gels. This improved speed is probably related to the larger sponge pores. Moreover, both the quantity of sample entry of the hydrophobic protein zein and its resolution after isoelectric focusing in the electrophoresis sponges (in the presence of organic solvent) was superior to that achieved in polyacrylamide gels. Experimentation and the application of these electrophoresis sponges is still preliminary, but the sponges appear to have potential as alternatives to the existing media used for electrophoresis.
Capillary electrophoresis combined with 252Cf plasma desorption and electrospray mass spectrometry for the structural characterization of hydrophobic polypeptides using organic solvents
Authors: Weinmann Wolfgang , Parker Carol E. , Baumeister Kerstin , Maier Claudia , Tomer Kenneth B. , Przybylski Michael 
Published: May 2005

AbstractCapillary electrophoresis (CE) conditions have been developed for the separation of hydrophobic polypeptides, such as fatty acid‐acylated peptides, and their subsequent structural identification by 252Cf plasma desorption (PDMS) and electrospray mass spectrometry (ESMS). Salt‐ and detergent‐free aqueous acetic acid buffers containing up to 20% 2‐propanol or 25% acetonitrile were employed for CE separations of hydrophobic peptides with (i) untreated, and (ii) 3‐aminopropyltrimethoxysilane‐derivatized fused silica capillaries. For both capillary types, electroosmotic flow rates suitable for sample isolation and transfer were determined, and CE separations of polypeptide mixtures were compared for aqueous buffers containing 2‐propanol or acetonitrile. For the mass spectrometric identification of CE‐separated peptides, a sheath flow sample isolation method was developed for subsequent transfer to PDMS. This procedure enabled the efficient isolation of peptide fractions for PDMS analysis, or alternative microanalytical techniques.Presented in part at the International Electrophoresis Forum, Munich, October 26–28, 1992.
Native electrophoresis to monitor chemical modifications of human interleukin‐3
Authors: Smit Victor 
Published: May 2005

AbstractNative electrophoresis on the Pharmacia PhastSystem using a new buffer system is used to monitor chemical modifications of human interleukin‐3. The method is faster, more gentle and more convenient than amino acid analysis. Micrograms of protein suffice in contrast with milligrams required in spectro‐photometric methods. As compared to generally used native electrophoresis, the combination of a changed conductivity, lower pH and the low density matrix results in a much better separation and detection of both the reaction products containing a high charge and the reaction products containing a low charge. This enables monitoring of extensive modifications as well as mild modifications. Our method also provides indications for denaturation of the protein. It has proven to be highly reproducible for at least 10 different modification reactions. Information can be obtained about the presence of the various distinct forms of the modified molecule, for instance leading to the average number of groups on the molecule. It also detects modifications not detectable with generally used native electrophoresis.
Glucose, fructose, mannose and/or glucose‐1‐phosphatereleasing activity stains for glycosidases and glycosyltransferases in gels after isoelectric focusing
Authors: Mukasa Hidehiko , Tsumori Hideaki , Uezono Yoshiko 
Published: May 2005

Abstractβ‐Fructofuranosidase, α‐glucosidase, β‐glucosidase, α‐mannosidase, β‐mannosidase, sucrose phosphorylase, glucosyltransferase and fructosyltransferase were separated by isoelectric focusing and sensitively detected to be slightly diffuse and insoluble spots in thin‐layer gels, supported by a glass plate, by release of monosugars or a sugar phosphate, followed by conversion to glucose‐6‐phosphate (G6P) and then by reduction of NADP+ to NADPH, terminated by the formation of reduced Nitroblue Tetrazolium (NBT). Approximately 1‐10 mU of enzyme was focused and the gel, after washing with a buffer, was partially dried and directly stained by uniformly spreading on the gel surface a staining medium containing sucrose or nitrophenyl glycosides as substrates, intermediary enzymes such as hexokinase, mutase and/or isomerase, NADP+, ATP, Mg+, phenazine methosulfate (PMS) and NBT. Specific staining procedures for each of these activities, on sucrose or on the glycosides as substrates, and staining procedures for multiple activities are described, with the conditions necessary for optimal development.
Analysis of cellular phosphoproteins by two‐dimensional gel electrophoresis: Applications for cell signaling in normal and cancer cells
Authors: Guy Graeme R. , Philip Robin , Tan Y. H. 
Published: May 2005

AbstractTwo‐dimensional (2‐D) gel electrophoresis has been used to map proteins from various cell types in an effort to eventually link such, maps to the sequencing of the entire human genome. While this analysis indicates the cellular disposition and expression of proteins, another application of 2‐D gels, the analysis of phosphoproteins, can provide much information as to the assembly and “wiring” of the signal transduction circuits within cells which appear to be enervated by phosphate exchange. The preparation and separation of 32P‐labeled proteins is described, as well as various analytical methods, including: the variety of gel systems available for specialist types of analyses, comparing 33P‐ and 32P‐labeling of proteins, imaging techniques, phosphoamino analysis, phosphopeptide separation, identifying the amino acid groups that are phosphorylated, and the identification of phosphoproteins on 2‐D gels by immunoprecipitation, corunning of purified proteins, comparative mapping and micro‐sequencing, and by Western blotting. Examples (in brackets) are given of applications in which 2‐D phosphogels can be applied, which offer advantages over other techniques. These include: (i) identifying in vivo substrates for kinases (protein kinase C activated by phorbol myristate acetate), (ii) investigating cytokine signaling pathways (tumor necrosis factor and interleukin −1), (iii) investigating the effects of drugs on signaling pathways (okadaic acid, menadione and cyclooxygenase inhibitors), (iv) characterization of specific phosphoproteins (heat‐shock protein Hsp27 and stathmin), (v) comparing normal and transformed cells (MRC‐5 human lung fibroblasts and their SV‐40‐transformed counterparts, MRC‐5 SV1 cells), (vi) purifying phosphoproteins, (vii) investigating the relationship of protein phosphorylation to stages in the cell cycle (stathmin), (viii) investigating protein/protein interactions, (ix) mapping in vitro kinase substrates (protein kinase C, protein kinase A, and mitogen activated protein kinase activated protein kinase 2), and (x) locating and identifying cellular phosphatases (Hsp27 phosphatase). It is possible that the mapping of phosphoproteins can be linked to other 2‐D gel databases and that information derived from these can be used in the future to better understand the signaling mechanisms of normal and cancerous cells.
Electrophoretic analysis of proteins associated with tumor cell invasion
Authors: Seftor Richard E. B. 
Published: May 2005

AbstractPolyacrylamide gel electrophoresis is an extremely powerful tool for separating and analyzing proteins associated with different diseases and has been invaluable in the identification and analysis of proteins associated with characteristics unique to tumor cells. This study presents data demonstrating the application of conventional sodium dodecyl sulfate (SDS)‐polyacrylamide gel electrophoresis and substrate‐incorporated SDS‐polyacrylamide gel electrophoresis (zymography) to obtain information about the proteins and catalytically active (or activatable) proteases associated with the process of tumor cell invasion using established human melanoma and breast carcinoma cell lines. Conventional SDS‐polyacrylamide gel electrophoresis was used to show that cells sequentially selected from a low invasive human melanoma cell line on the basis of their ability to invade in vitro have an increase and/or addition of six unique proteins on their cell surface. In a different application of SDS‐polyacrylamide gel electrophoresis, zymography was used to demonstrate that there is an increase in the levels of gelatinase A in the conditioned medium from three differently invasive human melanoma cell lines coincident with their ability to invade in vitro. Furthermore, the conditioned medium from the most invasive melanoma cell line demonstrated the greatest amount of gelatinase B activity. While the conditioned medium from three human breast carci noma cell lines contained low levels of both gelatinase A and B, one breast cell line also contained activity associated with stromelysin(s) not seen in the melanoma cell lines. The most invasive melanoma and breast cell lines contained appreciable levels of urokinase, while the less invasive melanoma cell lines contained low levels of tissue‐type plasminogen activator and the less invasive breast cell lines contained little‐to‐no plasminogen activator(s) activity. These observations can contribute to our understanding of the invasive process and the electrophoretic techniques used to monitor, test and analyze therapeutic approaches for metastatic diseases.
Two‐dimensional gel mapping of small GTPases reveals transformation‐specific changes during oncogenesis
Authors: Huber Lukas A. , Beug Hartmut , Simons Kai , Reichmann Ernst 
Published: May 2005

AbstractEpithelial cells transformed by oncogenes in vitro change their gene expression program, thereby losing features of cell polarity and cell adhesion. Using ras‐transformed mammary epithelial cells, we have investigated the expression of other small GTP‐binding proteins by high‐resolution two‐dimensional gel electrophoresis and direct GTP ligand binding after renaturing transfer onto nitrocellulose, Ras‐transformed cells lost the expression of one epithelial‐specific GTP‐binding protein (21–22 kDa, pI 4.5–4.8) and instead expressed a fibroblast GTP‐binding protein (21–22 kDa, pI 4.8–5.0).