bluuebunny/crossref_metadata_2025_split huggingface dataset:
Advances in sol‐gel based columns for capillary electrochromatography: Sol‐gel open‐tubular columns
Authors: Malik Abdul 
Published: December 2002

AbstractThe development of sol‐gel open‐tubular column technology in capillary electrochromatography (CEC) is reviewed. Sol‐gel column technology offers a versatile means of creating organic‐inorganic hybrid stationary phases. Sol‐gel column technology provides a general approach to column fabrication for microseparation techniques including CEC, and is amenable to both open‐tubular and monolithic columns. Direct chemical bonding of the stationary phase to the capillary inner walls provides enhanced thermal and solvent stability to sol‐gel columns. Sol‐gel stationary phases inherently possess higher surface area, and thus provide an effective one‐step alternative to conventional open‐tubular column technology. Sol‐gel column technology is applicable to both silica‐based and transition metal oxide‐based hybrid stationary phases, and thus, provides a great opportunity to utilize advanced material properties of a wide range of nontraditional stationary phases to achieve enhanced selectivity in analytical microseparations. A wide variety of stationary phase ligands can be chemically immobilized on the capillary inner surface using a single‐step sol‐gel procedure. Sol‐gel chemistry can be applied to design stationary phases with desired chromatographic characteristics, including the possibility of creating columns with either a positive or a negative charge on the stationary phase surface. This provides a new tool to control electroosmotic flow (EOF) in the column. Column efficiencies on the order of half a million theoretical plates per meter have been reported for sol‐gel open‐tubular CEC columns. The selectivity of sol‐gel stationary phases can be easily fine‐tuned by adjusting the composition of the coating sol solution. Open‐tubular columns have significant advantages over their packed counterparts because of the simplicity in column making and hassle‐free fritless operation. Open‐tubular CEC columns possess low sample capacity and low detection sensitivity. Full utilization of the analytical potential of sol‐gel open‐tubular columns will require a concomitant development in the area of high‐sensitivity detection technology.
Recent progress in the development, characterization and application of polymeric pseudophases for electrokinetic chromatography
Authors: Palmer Christopher P. 
Published: December 2002

AbstractThis review article details the development, characterization and application of polymeric materials as pseudostationary phases for electrokinetic chromatography over the past two years. Recent developments in cationic polymers and anionic siloxane, acrylamide and polymerized surfactants (micelle polymers) are reviewed. Also reviewed is recent progress in the development and characterization of chiral polymeric phases for chiral separations by electrokinetic chromatography, and application of a polymeric pseudophase with electrospray ionization mass spectrometric detection.
Recent progress in enantiomeric separation by capillary electrochromatography
Authors: Kang Jingwu , Wistuba Dorothee , Schurig Volker 
Published: December 2002

AbstractRecent progress in enantiomeric separations by capillary electrochromatography (CEC) is reviewed. The development of simple and robust CEC column technologies plays an important role for popularization of CEC. During the last several years, various approaches for the preparation of enantioselective columns have been reported. Currently, the monolithic column technology (continuous beds) represents the most advanced approach for the preparation of CEC columns. The development of new chiral stationary phase used for CEC is another important issue in this field. Fundamental investigations on electrochromatographic behaviors of various CSPs are necessary in order to understand the separation mechanism and thus improve the separation performance. Some chiral stationary phases performed better under nonaqueous CEC conditions than reversed‐phase conditions. Coupling CEC with mass spectrometry (MS) provides a powerful tool for enantiomeric separation. Finally, some applications of enantiomeric separation by CEC are summarized.
Detection of submicrogram quantities of glycosaminoglycans on agarose gels by sequential staining with toluidine blue and Stains‐All
Authors: Volpi Nicola , Maccari Francesca 
Published: December 2002

AbstractA sensitive method has been developed for the visualization of nonradiolabelled glycosaminoglycans resolved by agarose gel electrophoresis using staining with toluidine blue followed by Stains‐All procedure. This method, which can detect as little as 10 ng of a single species, can be used to stain a few micrograms of a complex polysaccharide mixture. The combination of agarose gel electrophoresis and sequential toluidine blue/Stains‐All staining can be applied to the analysis of all the complex glycosaminoglycans (i.e., heparin, heparan sulfate, chondroitin/dermatan sulfate) and nonsulfated polyanions (i.e., hyaluronate, defructosylated capsular polysaccharide K4) as well as to comparisons of specificities of the glycosaminoglycan‐degrading enzymes and the identification and quantification of the contaminations of other polysaccharides within glycosaminoglycan preparations with great sensitivity (about 0.1%). Furthermore, this method can be used to stain low‐molecular‐mass fractions and oligosaccharides derived from the natural polyanions, such as heparin. This procedure may be particularly valuable in situations where the availability of glycosaminoglycan is very limited.
Revisiting electroblotting of immobilized pH gradient gels: A new protocol for studying post‐translational modification of proteins
Authors: Poland Julia , Böhme Axel , Schubert Kathrin , Sinha Pranav 
Published: December 2002

AbstractCurrently, one of the most important techniques in proteome analysis is two‐dimensional electrophoresis that is widely used for separation of thousands of different protein spots. Nevertheless, characterization of special aspects in protein patterns, e.g., separation of protein isoforms generated by post‐translational modifications, requires individual detection methods, e.g., immunoblotting. Blotting of proteins after fractionation in immobilized pH gradients has always caused some problems. In this paper we present an optimized protocol for immunoblotting after isoelectric focusing using immobilized pH gradient (IPG) strips cast on Net‐Fix as an internal support that is permeable to electric current. The focusing procedure can be carried out in commonly used IPG systems, e.g., the IPGphor by Amersham Biosciences, where electrically assisted rehydration can be performed. This may be of interest for many laboratories, because the same system as used for the first dimension of two‐dimensional polyacrylamide gel electrophoresis (2‐D PAGE) is involved. As an example, we describe separation and detection of up to seven isoforms of recombinant erythropoietin β using semidry blotting of IPG strips and visualization by chemiluminescence detection.
Analysis of benzo[a]pyrene diol epoxide‐DNA adducts by capillary zone electrophoresis‐ electrospray ionization‐mass spectrometry in conjunction with sample stacking
Authors: Willems An V. , Deforce Dieter L. , Van den Eeckhout Elfriede G. , Lambert Willy E. , Van Peteghem Carlos H. , De Leenheer André P. , Van Bocxlaer Jan F. 
Published: December 2002

AbstractBenzo[a]pyrene diol epoxide (BPDE) was reacted in vitro with (2'‐deoxy)nucleotides and with calf thymus DNA. The modified DNA was enzymatically hydrolyzed to the 5'‐monophosphate nucleotides using deoxyribonuclease I (DNA‐ase I), nuclease P1 and snake venom phosphodiesterase (SVP). Most of the unmodified nucleotides were removed using solid phase extraction (SPE) in a polystyrene divinylbenzene copolymer. Three adducts could be detected and identified using capillary zone electrophoresis(negative)‐ion electrospray ionization‐mass spectrometry (CZE‐(—)‐ESI‐MS) in conjunction with sample stacking. This way, not only a BPDE‐dGMP adduct [(M—H)— at m/z 648], a well‐known nucleotide adduct, could be retrieved, but also a BPDE‐dAMP [(M—H)— at m/z 632] and a BPDE‐dCMP adduct [(M—H)— at m/z 608] could be detected for the first time. The presence of the prominent ion at m/z 195 (the deoxyribose‐phosphate ion) in the three low‐energy collision‐activated decomposition (CAD) spectra indicated that the adducts were formed through base‐alkylation. CZE‐positive ion ESI‐MS/MS experiments were performed to obtain further information on base‐alkylation. The absence of the loss of NH3 from the nucleobase in each CAD spectrum points to an alkylated exocyclic NH2 position of the nucleobase. So, the three adducts could be identified as BPDE‐N2‐dGMP, BPDE‐N6‐dAMP and BPDE‐N4‐dCMP using CZE‐ESI‐MS and CZE‐ESI‐MS/MS.
Enantioseparation of chiral aromatic amino acids by capillary electrophoresis in neutral and charged cyclodextrin selector modes
Authors: La Sookie , Ahn Sungyeon , Kim Jung‐Han , Goto Junichi , Choi One‐Kyun , Kim Kyoung‐Rae 
Published: December 2002

AbstractSimultaneous enantioseparations of 15 racemic aromatic amino acids and L‐mimosine for their chiral discrimination were achieved by neutral selector‐modified capillary electrophoresis (CE) and by charged selector‐modified CE. Among the diverse cyclodextrins (CDs) examined, hydroxypropyl (HP)‐α‐CD as the neutral selector and highly sulfated (HS)‐γ‐CD as the charged selector provided best chiral environments of different enantioselectivities. Fairly good enantiomeric resolutions were achieved with the HP‐α‐CD mode except for racemic 6‐hydroxy‐3,4‐dihydroxyphenylalanine, threo‐3,4‐dihydroxyphenylserine and homophenylalanine while high‐resolution separations of all the enantiomeric pairs were achieved in the HS‐γ‐CD mode except that L‐mimosine was not detected and a partial resolution (0.6) for threo‐3,4‐dihydroxyphenylserine enantiomers. Relative migration times to that of internal standard under the respective optimum conditions were characteristic of each enantiomer with good precision (% RSD: 0.7–3.8), thereby enabling to cross‐check the chemical identification of aromatic amino acids and also their chiralities. The method linearity was found to be adequate (r> 0.99) for the chiral assay of the aromatic amino acids investigated. When applied to extracts of three plant seeds, nonprotein amino acids such as L‐mimosine (42 νg/g) from Mimosa pudica Linné, and L‐3,4‐dihydroxyphenylalanine (268 νg/g) from Vicia faba were positively detected along with L‐tryptophan, L‐phenylalanine and L‐tyrosine.
What cardiovascular defect does my prenatal mouse mutant have, and why?
Authors: Conway Simon J. , Kruzynska‐Frejtag Agnieszka , Kneer Paige L. , Machnicki Michal , Koushik Srinagesh V. 
Published: December 2002

AbstractSummary: Since the advent of mouse targeted mutations, gene traps, an escalating use of a variety of complex transgenic manipulations, and large‐scale chemical mutagenesis projects yielding many mutants with cardiovascular defects, it has become increasingly evident that defects within the heart and vascular system are largely responsible for the observed in utero lethality of the embryo and early fetus. If a transgenically altered embryo survives implantation but fails to be born, it usually indicates that there is some form of lethal cardiovascular defect present. A number of embryonic organ and body systems, including the central nervous system, gut, lungs, urogenital system, and musculoskeletal system appear to have little or no survival value in utero (Copp, 1995). Cardiovascular abnormalities include the failure to establish an adequate yolk‐sac vascular circulation, which results in early lethality (E8.5–10.5); poor cardiac function (E9.0–birth); failure to undergo correct looping and chamber formation of the primitive heart tube (E9.0–11.0); improper septation, including division of the common ventricle and atria and the establishment of a divided outflow tract (E11.0–13.0); inadequate establishment of the cardiac conduction system (E12.0–birth); and the failure of the in utero cardiovascular system to adapt to adult life (birth) and close the interatrial and aorta‐pulmonary trunk shunts that are required for normal fetal life. Importantly, the developmental timing of lethality is usually a good indicator of both the type of the cardiovascular defect present and may also suggest the possible underlying cause/s. The purpose of this review is both to review the literature and to provide a beginner's guide for analysing cardiovascular defects in mouse mutants. genesis 35:1–21, 2003. © 2002 Wiley‐Liss, Inc.
Consequences of knocking out BMP signaling in the mouse
Authors: Zhao Guang‐Quan 
Published: December 2002

AbstractSummary: During the past two decades, a significant amount of data has been accumulated revealing the intriguing functions of bone morphogenetic proteins (BMPs) in all aspects of embryonic development and organogenesis. Numerous genes encoding BMPs, BMP receptors, and their downstream signal transducers have been mutated in the mouse through targeted mutagenesis. This review focuses on what is known about the role of BMP signaling in gastrulation, mesoderm formation, left–right asymmetry, neural patterning, skeletal and limb development, organogenesis, and gametogenesis as revealed by BMP‐signaling mutants. genesis 35:43–56, 2003. © 2002 Wiley‐Liss, Inc.
Prediction of seasonal snow accumulation in cold climate forests
Authors: Pomeroy J. W. , Gray D. M. , Hedstrom N. R. , Janowicz J. R. 
Published: December 2002

AbstractAccumulation of snow under forest canopies is known to decline with increasing canopy density and leaf area because of snow interception and sublimation in the canopy. Seasonal snow accumulation measurements, collected over a decade from various forest stands in western Canada, were used to test and develop methods to relate forest snow accumulation to stand properties and observations of either small‐clearing seasonal snow accumulation or seasonal snowfall. At sub‐stand scales, the variability of seasonal snow accumulation was not well related to stand leaf area, seasonal interception or small‐clearing seasonal snow accumulation. At the stand scale, physically based snow interception equations predicted seasonal snow accumulation from the stand leaf area and the seasonal snow accumulation or snowfall in adjacent clearings. A simple parametric form of these equations showed the sensitivity of seasonal snow accumulation to leaf area at the forest stand scale and suggested a relationship to extrapolate snow accumulation or snowfall measurements from clearings to forests. These relationships, developed from Canadian boreal forest observations, are consistent with Kuz'min's (1960. Formirovanie Snezhnogo Pokrova i Metody Opredeleniya Snegozapasov. Gidrometeoizdat: Leningrad) relationship between accumulation and canopy density derived from Russian observations, suggesting a good degree of transferability. Copyright © 2002 Crown in the right of Canada. Published by John Wiley & Sons Ltd.
Simulation of ice phenology on Great Slave Lake, Northwest Territories, Canada
Authors: Ménard Patrick , Duguay Claude R. , Flato Greg M. , Rouse Wayne R. 
Published: December 2002

AbstractA one‐dimensional thermodynamic lake ice model (Canadian Lake Ice Model or CLIMo) is used to simulate ice phenology on Great Slave Lake (GSL) in the Mackenzie River basin, Northwest Territories, Canada. Model simulations are validated against freeze‐up and break‐up dates, as well as ice thickness and on‐ice snow depth measurements made in situ at three sites on GSL (Back Bay near Yellowknife, 1960–91; Hay River, 1965–91; Charlton Bay near Fort Reliance, 1977–90). Freeze‐up and break‐up dates from the lake ice model are also compared with those derived from SSM/I 85 GHz passive microwave imagery over the entire lake surface (1988–99).Results show a very good agreement between observed and simulated ice thickness and freeze‐up/break‐up dates over the 30–40 years of observations, particularly for the Back Bay and Hay River sites. CLIMo simulates the ice thickness and annual freeze‐up/break‐dates with a mean error of 7 cm and 4 days respectively. However, some limitations have been identified regarding the rather simplistic approach used to characterize the temporal evolution of snow cover on ice. Future model improvements will therefore focus on this particular aspect, through linkage or coupling to a snow model. Copyright © 2002 John Wiley & Sons, Ltd.
The influence of thermal, hydrologic, and snow deformation mechanisms on snow water equivalent pressure sensor accuracy
Authors: Johnson Jerome B. , Schaefer Garry L. 
Published: December 2002

AbstractA 5 year field study was conducted to determine the mechanisms that cause snow water equivalent (SWE) pressure sensor measurement errors. The objective is to establish design and installation criteria to develop an accurate electronic SWE pressure sensor that minimizes errors. We monitored a 3 m snow pillow and installed three prototype electronic SWE sensors of our own design to examine how SWE errors occur. We also measured the heat flux through the prototype sensors and the soil, snow temperature, soil moisture content, and soil thermal conductivity. The SWEs of snow cores were used to assess the accuracy of the snow pillow and prototype sensors. Experimental results indicate that SWE measurement errors occur only when the snow–SWE sensor and/or the snow–soil interfaces are at the melting temperature. The magnitude of SWE errors is related to the diameter of the sensor and the difference in heat flux through the sensor and the surrounding soil. SWE over‐measurement errors occur when the heat flux through the sensor is less than through the surrounding soil, producing a snowmelt rate on the sensor that is less than on the adjacent soil. SWE under‐measurement errors occur when the heat flux through the sensor is greater than through the surrounding soil. The most severe SWE measurement errors occur during the transition from winter to spring, when the snow cover first reaches an isothermal condition causing a maximum difference in snowmelt rate between an SWE sensor and the surrounding soil. SWE measurement errors are reduced by increasing the SWE sensor diameter, matching the thermal properties of the soil and SWE sensor, allowing water to flow through the sensor, and using a surface cover to diffuse heat into the adjacent soil. SWE measurement errors relax through snow creep mechanisms that redistribute the snow load equally between the sensor and surrounding soil. Published in 2002 by John Wiley & Sons Ltd.
Simulating wind fields and snow redistribution using terrain‐based parameters to model snow accumulation and melt over a semi‐arid mountain catchment
Authors: Winstral Adam , Marks Danny 
Published: December 2002

AbstractIn mountainous regions, wind plays a prominent role in determining snow accumulation patterns and turbulent heat exchanges, strongly affecting the timing and magnitude of snowmelt runoff. In this study, digital terrain analysis was employed to quantify aspects of the upwind topography related to wind shelter and exposure, to efficiently develop a distributed time‐series of snow accumulation rates and wind speeds to force a distributed snow model. Parameters are presented that determined each grid cell's topographic exposure and potential for drift development relative to observed winds. Using meteorological data taken from both an exposed and a sheltered site in the Reynolds Mountain East watershed (0·38 km2) in southwestern Idaho, the terrain parameters were used to distribute rates of snow accumulation and wind speeds at an hourly time step for input to ISNOBAL, an energy and mass balance snow model. Model runs were initiated prior to the development of the seasonal snow cover and continued through complete meltout for the 1986 (precipitation 128% of average), 1987 (66%), and 1989 (108%) water years. A comprehensive dataset consisting of a time series of aerial photographs taken during meltout, measured runoff, and snow data from the sheltered meteorological site were used to validate the simulations. ISNOBAL forced with accumulation rates and wind fields generated from the applied terrain parameterizations accurately modelled the observed snow distribution (including the formation of drifts and scoured wind‐exposed ridges) and snowmelt runoff for all three years of study. By contrast, ISNOBAL forced with spatially constant accumulation rates and wind speeds taken from the sheltered meteorological site, a typical snow‐monitoring site, overestimated peak snowmelt inputs and tended to underestimate snowmelt inputs prior to the runoff peak. Published in 2002 by John Wiley & Sons, Ltd.
Melatonin inhibits the contractile effect of vanadate in the isolated pulmonary arterial rings of rats: Possible role of hydrogen peroxide
Authors: Nagi Mahmoud N. , Mansour Mahmoud A. , Al‐shabanah Othman A. , El‐Kashef Hassan A. 
Published: December 2002

AbstractThe effect and possible mechanism of action of vanadate on the isolated pulmonary arterial rings of normal rats were studied. Pulmonary arterial rings contracted in response to vanadate (0.1–1 mM) in a concentration‐dependent manner. Preincubation of the pulmonary arterial rings with 1 mM melatonin significantly reduced the contractile effect of vanadate by more than 60%. Furthermore, addition of hydrogen peroxide (50 μM) or enzymatic generation of hydrogen peroxide by the addition of glucose oxidase (10 U/mL) to the medium containing glucose produced remarkable increases in the pulmonary arterial tension, 46.2 ± 7.3 and 78.7 ± 9.7 g tension/g tissue, respectively. Similarly, incubation of the pulmonary arterial rings with 1 mM melatonin significantly reduced the contractile responses of the arterial rings to hydrogen peroxide and glucose/glucose oxidase to 25.7 ± 2.9 and 24.7 ± 4.4 g tension/g tissue, respectively. Vanadate, in vitro, significantly stimulated the oxidation of NADH by xanthine oxidase, and the rate of oxidation was increased by increasing either time or vanadate concentration. Similarly, addition of melatonin to a reaction mixture containing xanthine oxidase and vanadate significantly inhibited the rate of NADH oxidation in a concentration‐dependent fashion. The results of the present study indicated that vanadate induced contraction in the isolated pulmonary arterial rings, which was significantly reduced by melatonin. Furthermore, the contractile effect of vanadate on the pulmonary arterial rings may be attributed to the intracellular generation of hydrogen peroxide. © 2002 Wiley Periodicals, Inc. J Biochem Mol Toxicol 16:273–278, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10049