bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐sensitive capillary zone electrophoresis analysis by electrokinetic injection with transient isotachophoretic preconcentration: Electrokinetic supercharging
Authors: Hirokawa Takeshi , Okamoto Hikaru , Gaš Bohuslav 
Published: February 2003

AbstractThe principle of an on‐line preconcentration method for capillary zone electrophoresis (CZE) named electrokinetic supercharging (EKS), is described and based on computer simulation the preconcentration behavior of the method is discussed. EKS is an electrokinetic injection method with transient isotachophoretic process, is a powerful preconcentration technique for the analysis of dilute samples. After filling the separation capillary with supporting electrolyte, an appropriate amount of a leading electrolyte was filled and the electrokinetic injection was started. After a while, terminating electrolyte was filled subsequently and migration current was applied. This procedure enabled the introduction of a large amount of sample components from a dilute sample without deteriorating separation. Computer simulation of the electrokinetic injection revealed that EKS was effective for the preconcentration of analytes with wide mobility ranges by proper choice of transient isotachophoresis (ITP) system and electroosmotic flow (EOF) should be suppressed to increase injectable amount of analytes under constant voltage mode. A test mixture of rare‐earth chlorides was used to demonstrate the uses of EKS‐CZE. When a 100 μL sample was used, the low limit of detectable concentration was 0.3 μg/L (1.8 nM for Er), which was comparable or even better than that of ion chromatography and inductively coupled plasma‐atomic emission spectrometry (ICP‐AES).
Chloride present in biological samples as a tool for enhancement of sensitivity in capillary zone electrophoretic analysis of anionic trace analytes
Authors: Křivánková Ludmila , Pantůčková Pavla , Gebauer Petr , Boček Petr , Caslavska Jitka , Thormann Wolfgang 
Published: February 2003

AbstractEffects originating from the variability of the sample matrix can be efficiently eliminated when the separation conditions are selected so that compounds of like charge with high concentration referred to as macrocomponents are embodied into the system of transient isotachophoresis. For stacking and separation of anionic trace analytes in biological samples, the presence of chloride is shown to be important to balance out effects of other macrocomponents that act against isotachophoretic stacking. Having acetoacetate, malate, citrate, and some drug metabolites in untreated human serum samples, the stacking mechanism of these compounds in an electrolyte system comprising 5 mM mandelic acid and ε‐aminocaproic acid, pH 3.8, is explained. Analytes are monitored by indirect UV‐absorption detection. Attention is paid to the minimum chloride concentration required with respect to the concentration ratio of phosphate (stacker) and lactate (destacker) present in the sample so as to ensure both stacking and separation of trace analytes. Insight into the separation process is given both with computer simulations and experiments. For selected analytes, the effect of chloride concentration on quantitative evaluation, sensitivity and limit of detection is demonstrated as well. Moreover, the applicability of the mobility window between phosphate and lactate for an additional group of metabolites is sketched.
The preparation of background electrolytes in capillary zone electrophoresis: Golden rules and pitfalls
Authors: Beckers Jozef L. , Boček Petr 
Published: February 2003

AbstractIn this article the methodology of the design of suitable background electrolytes (BGEs) in capillary zone electrophoresis (CZE) is described. The principal aspects of the role of a BGE in CZE are discussed with respect to an appropiate migration behavior of analytes, including the transport of the electric current, the buffering of pH, the Joule heat, the electro‐endosmotic flow (EOF) and the principal migration and detection modes. The impact of the composition of the BGE upon migration and detection is discussed. It is shown that the total concentration of the BGE is a principal factor and the adjustment of migrating analyte zones according to the Kohlrausch regulating function (KRF) is the principal effect in most of the sample stacking techniques. The number of co‐ions and their properties are of key importance for peak shapes of the analyte peaks and for the existence of system zones. The detection of UV‐transparent analytes may advanteously be done in the indirect UV mode, by using UV‐absorbing co‐ions, however, both peaks and dips may be expected in the UV trace in case of multiple co‐ionic BGEs. Properties of BGEs can be predicted applying mathematical models and it is shown that with SystCharts, predictions can be given concerning the existence of system zones, detection modes and the peak shapes of analytes for a given BGE. Practical examples of methodological considerations are given in the design of suitable BGEs for four principal combinations of migration and detection modes. The properties of the BGEs selected are exemplified with experimental results. Golden rules are summarized for the preparation of suitable BGEs in CZE.
Ampholytes as background electrolytes in capillary zone electrophoresis: Sense or nonsense? Histidine as a model ampholyte
Authors: Beckers Jozef L. 
Published: February 2003

AbstractA lot of phenomena, occuring in capillary zone electrophoresis (CZE), are linked with the ionic concentration of the background electrolyte (BGE). If weak bases and acids are used as BGEs in CZE, at a pH where they are scarcely ionized, the ionic concentration of the BGE is very low and this brings a strong peak broadening, limited sample stacking and low sample load. Because the electromigration dispersion increases extremely, moreover, the existence of low‐conductivity BGEs in CZE is a contradiction in terms. The behavior of ampholytes as BGE in CZE is examined, by means of histidine as a model ampholyte. For BGEs consisting of histidine, important parameters, including the ionic concentrations, buffer capacity, transfer ratio, and the indicator for electromigration dispersion E1m1/E2m2, are calculated at various pH. Although the transfer ratio is fairly constant over the whole pH traject, the ionic concentration and buffer capacity decrease whereas the electromigration dispersion strongly increases near the pI of histidine. I.e., that ampholytes can be applied as BGEs in CZE, however, just not at pH near their pI value, except as the difference between the pK values of the basic and acidic group, the δpK value, is very small. For ampholytes with a low δpK value or at high concentrations, all the before‐mentioned effects are less fatal, but in that case we can not speak of a real low‐conductivity BGE. If ampholytes are used at pH near their pK values, the use of ampholytes as BGE is not advantageously compared with simple weak bases and acids. This has been confirmed by calculations and experiments.
Sensitive indirect photometric detection of inorganic and small organic anions by capillary electrophoresis using Orange G as a probe ion
Authors: Johns Cameron , Shaw Matthew J. , Macke Miroslav , Haddad Paul R. 
Published: February 2003

AbstractThis study addresses the two major problems in the use of dyes as highly absorbing probes for indirect photometric detection in capillary electrophoresis (CE). First, effective electroosmotic flow (EOF) modification or suppression to allow separation and detection of a wide mobility range of analytes is not straightforward when electrolytes containing increased dye concentrations are used. The suppression of EOF to less than + 5×10−9 m2V−1s−1 was achieved with a combination of a poly(ethylenimine) (PEI)‐coated capillary and the addition of the neutral polymer hydroxypropylmethylcellulose (HPMC) to the background electrolyte. Second, the deterioration of baselines due to adsorption of the dye probe to the capillary wall is generally a problem. In this work, baseline quality at higher probe concentrations was significantly improved by a rather unusual but highly effective combination of a simultaneous application of a slight overpressure (25 mbar) at the injection end during the separation, and the use of a relatively narrow capillary of 50 μm inner diameter. Both measures would appear to be counterproductive. Optimisation of the probe concentration with regard to signal‐to‐noise ratio resulted in an electrolyte of 4 mM Orange G, 0.05% HPMC buffered at pH 7.7 by the addition of 10.0 mM histidine isoelectric buffer. Very high separation efficiencies of 128 000–297 000 plates were made possible by the relatively high probe concentration. Combined with excellent detection sensitivity, even with the introduction of hydrodynamic flow and a reduced optical path length, these measures resulted in limits of detection ranging from 0.216 to 0.912 μM with a deuterium lamp light source (248 nm) and from 0.147 to 0.834 μM with a 476 nm blue light‐emitting diode (LED) light source. Reproducibility over 30 consecutive runs without changing the electrolyte was excellent, with relative standard deviation (RSD) values of 0.14–0.80% for migration time, 1.27–3.36% for peak area and 0.88–5.12% for peak heights. The optimised electrolyte was used for the analysis of inorganic anions in air filter samples, providing good agreement with results obtained by ion chromatography.
Indirect laser‐induced fluorescence detection for capillary electrophoresis using a frequency‐doubled diode laser
Authors: Ragozina Natalia , Pütz Michael , Faubel Werner , Pyell Ute 
Published: February 2003

AbstractA blue (452 nm) frequency‐doubled diode laser with a quasi‐cw optical output power of 10 μW is used for indirect laser‐induced fluorescence detection in combination with the capillary electrophoretic separation of inorganic anions. As fluorescing probe ion the anion of 8‐hydroxypyrene‐1,3,6‐trisulfonic acid (HPTS) was selected having an absorption maximum of 454 nm in alkaline medium. Employing a capillary coated with linear acrylamide, baseline separation of eight inorganic anions was possible within 5 min. With a separation buffer containing 50 μmol·L‐1 HPTS and 10 mmol·L‐1 lysine the limits of detection for sulfate, nitrite, nitrate, azide, thiocyanate, and chlorate were between 0.9 and 4.7 μmol·L‐1. Separation of chloride and sulfate was achieved by adding 0.25 mmol·L‐1 calcium hydroxide to the separation buffer. Inorganic anions in several mineral and tap water samples have been determined with the technique developed and results are compared to data obtained by ion chromatography in combination with conductivity detection after conductivity suppression.
Cutting the Wastewater Peaks for Cyclic Batch Production Plants
Authors: Hui C.‐W. , Li B. , Smith R. 
Published: February 2003

AbstractThis paper proposes systematic approaches for cutting the wastewater peaks generated in cyclic batch production plants in which wastewater generation rates and concentration are varied with time. To reduce the investment for the wastewater treatment unit or not to violate the discharge limits, the fluctuations of both flow rate and concentration of the wastewater generated need to be controlled or equalized. Buffer tanks (or basin) are commonly used to regulate the wastewater flow and concentration before the wastewater is sent to treatment units or discharge. The size of the buffer tank needs to be designed properly so that its size is minimized and still has enough capacity to handle various operating conditions. In this paper, conceptual approaches are presented to minimize the size of the buffer tank for either controlling wastewater flow rate or concentration. Mathematical models are proposed for controlling both flow rate and concentration.
Cell adhesion and matrix remodeling genes identified by co‐expression analysis
Authors: Walker Michael G. , Volkmuth Wayne 
Published: February 2003

AbstractCell adhesion and matrix remodeling are elements in many diseases, ranging from atherosclerosis and fibrosis to metastatic cancer. However, many genes that participate in these processes have not yet been identified. To find such genes, we looked for previously uncharacterized genes that are co‐expressed with known cell adhesion and matrix remodeling genes. The known genes in this study included MMP2, TIMP3, BM‐40, chondroitin, connective tissue growth factor, fibromodulin, IGFBP5, laminin, MGP, myosin light chain kinase, several collagens, and other matrix and adhesion proteins. We found eight previously uncharacterized genes, here named MXRA1 through MXRA8, that were strongly co‐expressed with these known adhesion and matrix genes. Five of the MXRA genes have a significant similarity to uncharacterized cDNA sequences or predicted proteins listed in the Genbank database, but otherwise show distant or no sequence similarity to genes with known function. Subsequent to our entry of the MXRA gene sequences in the Genbank, three of the eight genes have been independently described by other researchers: MXRA2 is α‐parvin, a cell‐matrix adhesion protein, MXRA4 is a C1 complement component receptor involved in cell adhesion, and MXRA5 is adlican, an adhesion proteoglycan. The analysis described here provides further evidence for the role of these genes in adhesion and matrix remodeling.
Structural variation in a novel zinc finger protein and investigation of its role in Hirschsprung disease
Authors: Andrew Scott D. , Kuiper Michael J. , Wride Michael A. , Mansergh Fiona C. , Rancourt Derrick E. , Mulligan Lois M. 
Published: February 2003

AbstractZinc finger transcription factors play essential roles in neural crest cell development. Even subtle disruptions of the function of these genes could contribute significantly to complex developmental phenotypes such as the multigenic disorder Hirschsprung disease (HSCR), a congenital failure of enteric neurogenesis. Although germline mutations in the RET proto‐oncogene are the most common cause of familial disease, at least 8 genes including transcription factors have been implicated in sporadic HSCR to date. Thus, a further group of candidate genes are those involved in regulating expression of known HSCR genes. In this study, we have characterized the ZNF358 zinc finger gene, a human orthologue of the mouse gene zfend, which is expressed in early developmental stages in the gut and in the neural folds at the time of neural crest differentiation. ZNF358 represents a putative transcription factor with DNA binding activity confered by 9 Cys2His2 zinc fingers. Although we did not detect disease associated mutations in a panel of HSCR patients, we did identify a novel variable sequence within the coding region of ZNF358 that would result in a deletion of nine amino acids from a polyalanine domain. Our molecular model suggests that this variant could alter protein tertiary structure and the ability of ZNF358 to regulate transcription. Together, our data suggest that, while ZNF358 may be involved in the regulation of genes such as those necessary for development or differentiation of neural crest cells, it does not play an obvious role in HSCR.
Single Nucleotide Polymorphism analysis of the human adenosine A2B receptor gene: prevalence of SNPs in asthmatics and normal subjects
Authors: van Heeke Gino , Seamons Rachael , Metais Jean‐Yves , Fozard John R. , Goff Stephen , Wheatley Amanda , Dewar Jane , Hall Ian P. 
Published: February 2003

AbstractThe adenosine A2B receptor is found on human lung mast cells and is believed to mediate the bronchoconstriction in response to adenosine characteristic of asthmatics. As such it represents an attractive therapeutic target for asthma and allergic rhinitis. As genetic variability in drug targets may affect an individual's response to treatment, the adenosine A2B receptor gene was analyzed for polymorphisms and their prevalence defined in a Caucasian population. The coding region of the A2B receptor gene as well as the intron‐exon boundaries of the gene were found to be free of genetic variation. Three single nucleotide polymorphisms were identified in the promoter region of the gene, one of which created a BamHI restriction fragment length polymorphism. The prevalence of the three single nucleotide polymorphisms in an unselected population was <5%. The prevalence of the BamHI polymorphism was investigated in a British population of 40 asthmatics and 40 non‐asthmatics: no excess of the BamHI variant was observed in asthmatic subjects. The data indicates that any variability in drug response would likely not be due to direct structural variation of the A2B receptor protein. Further, polymorphism at the A2B receptor genomic locus is unlikely to contribute to the population risk of developing asthma.
Quantitation of inflammatory und proliferative genes as disease markers in laser‐microdissected, formalin‐fixed and paraffinized glomeruli from human renal biopsies
Authors: Fries Jochen Walter Ulrich , Pakula Alexandra , Roth Tanja , Dienes Hans‐Peter , Odenthal Margarete 
Published: February 2003

AbstractOrgan biopsies from kidney, liver, intestine or heart are presently only evaluated for pathologic lesions using formalin‐fixation and paraffin‐embedding. Changes in pattern and levels of gene expression underlying and preceding these lesions have been disregarded, since a quantitative assay system using minute paraffinized tissue samples with minimal amounts of RNA is currently unavailable. This paper describes such an assay using formalin‐fixed, paraffinized biopsies from human glomeruli after laser‐microdissection. Choosing proliferative glomerular lesions expected to express platelet‐derived growth factor‐β receptor (PDGF‐βR), we investigated whether vascular cell adhesion molecule‐1 (VCAM‐1), a marker of the inflammatory signal pathway, was coexpressed, indicating the potential to progress an already existing lesion. RNA extraction procedures including DNAse pretreatment were pretested on microdissected mouse glomeruli. β‐actin, not upregulated in cell culture by TNF (tumor necrosis factor) or PDGF stimulation, served as housekeeping gene. By qualitative real‐time (RT)‐PCR, transcription of both genes was detectable using only one microdissected glomerular section. Quantitative PCR for VCAM‐1 revealed unsuspected increased levels in the same cases positive by qualitative RT‐PCR, not detectable by morphologic analysis or immunohistochemistry. Thus, quantitative gene expression analysis is possible in paraffinized biopsies from minute tissue samples and will provide such important information as unexpected gene expression causing a potential progression of an existing lesions.
Molecular Recognition of an Amino Acid by a Novel Macrocyclic Monoxo‐tetraamine and Its ZnII Complex
Authors: Gao Jian , Martell Arthur E. , Reibenspies Joseph 
Published: February 2003

AbstractThe macrocycle monoxo‐tetraamine, 1,4,8,11‐tetraazacyclotridecane‐5‐one (mota), was found to be extremely efficient in the recognition of the amino acid, glycine (Gl), in aqueous solution. The single‐crystal structure of a five‐coordinated mota‐ZnII complex is reported. This ZnII complex acts as host for Gl to form a stable ternary complex. The recognition constants and the recognition mechanism for the binary and ternary complexes are based on potentiometric data.
Rapid Cleavage of Oligodeoxyribonucleotides from cis‐Diol‐Bearing Universal Polymer Support
Authors: Kumar Pradeep , Gupta Kailash C. 
Published: February 2003

AbstractTwo sets of conditions have been proposed for the cleavage of oligodeoxyribonucleotides from cis‐diol‐bearing polymer supports and their complete deprotection. The first condition involves the use of spermine in the presence of Zn2+ ions in aqueous NH3 at 60° for 1 h, while the second one employs the use of 0.5M LiOH in conjunction with 3.5M Et3N/MeOH at 75° for 40–60 min, or under microwaves for 5–8 min, depending on the protection employed for nucleic bases.
Synthesis, Enantiomeric Conformations, and Stereodynamics of Aromatic ortho‐Substituted Disulfones
Authors: Lacour Jérôme , Monchaud David , Mareda Jiri , Favarger France , Bernardinelli Gérald 
Published: February 2003

AbstractAromatic ortho‐disulfone derivatives are readily accessible from diiodide precursors by CuI‐mediated reaction with sodium sulfinate salts (DMF, 110°). The sulfonyl substituents adopt in solution and in the solid state two enantiomeric conformations (λ and δ) as evidenced by 31P‐ and 1H‐NMR data of the chiral D3‐symmetric tris{4,5‐bis[(4‐methylphenyl)sulfonyl]benzene‐1,2‐diolato(2−)‐κO,κO′}phosphate(v) anion (3a) and 1,2‐bis(camphor‐10‐sulfonyl)‐4,5‐dimethoxybenzene ((=1,2‐bis{{[(1S,4R)‐7,7‐dimethyl‐2‐oxobicyclo[2.2.1]hept‐1‐yl]methyl}sulfonyl}‐4,5‐dimethoxybenzene; 6c). X‐Ray structure analysis of 1,2‐dimethoxy‐4,5‐bis(methylsulfonyl)benzene (6a) and 1,2‐dimethoxy‐4,5‐bis(4‐methylphenyl)sulfonyl]benzene (6b) confirmed in the solid state the preferred chiral orientation of the sulfonyl groups. Dynamic conformational isomerism was detected for 6c in its 1H‐NMR in the temperature range of 110°, the corresponding free energy being 19.8 kcal⋅mol−1.
Novel Enantioselective Synthesis of Both Enantiomers of Furan‐2‐yl Amines and Amino Acids
Authors: Demir Ayhan S. , Sesenoglu Özge , Ülkü Dinçer , Arıcı Cengiz 
Published: February 2003

AbstractA new enantioselective synthesis of furan‐2‐yl amines and amino acids is described, in which the key step is the oxazaborolidine‐catalyzed enantioselective reduction of O‐benzyl (E)‐ and (Z)‐furan‐2‐yl ketone oximes to the corresponding chiral amines. The chirality of the furan‐2‐yl amines is fully controlled by the appropriate choice of the geometrical isomer of the O‐benzyl oxime. Oxidation of the furan ring furnished amino acids in high yields.
Breast cancer cell line proliferation blocked by the Src‐related Rak tyrosine kinase
Authors: Meyer Tanya , Xu LiHui , Chang Jinli , Liu Edison T. , Craven Rolf J. , Cance William G. 
Published: February 2003

AbstractRak is a 54 kDa protein tyrosine kinase originally isolated from breast cancer cells and expressed in epithelial cells. It resembles the protooncogene Src structurally but lacks an amino‐terminal myristylation site and localizes to the nuclear and perinuclear regions of the cell. We report here that expression of Rak in 2 different breast cancer cell lines inhibits growth and causes G1 arrest of the cell cycle. This growth inhibition is kinase‐dependent but does not require the Rak SH2 or SH3 domain. Rak also binds to the pRb tumor‐suppressor protein but inhibits growth even in cells that lack pRb. These results suggest that Rak regulates cell growth by phosphorylating perinuclear proteins and has a function that is distinct from the Src‐related kinase family. © 2002 Wiley‐Liss, Inc.