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  • Wiley-Blackwell  (153)
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  • 1
    ISSN: 0899-0042
    Keywords: human serum albumin ; electrokinetic chromatography ; chiral drugs ; ligand-ligand interactions ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When a protein such as human serum albumin is added to the separation buffer in capillary electrophoresis, the mobility of solutes which bind to that protein may be altered. The change in mobility of the solute is a function both of the strength of the binding interaction, and the difference in mobility between the free solute and protein additive. By adding other ligands which themselves bind to the protein, the strength of the solute-protein binding may be modified, leading to a measurable change in the mobility of the solute. These effects are particularly striking for chiral compounds, where enantioselectivity may be completely lost on addition of a competitive ligand. Capillary electrophoresis with human serum ablumin as a buffer additive was used to separate the enantiomers of benzoin and three phenothiazine derivatives. A comparison of the binding of (S)-benzoin to human serum albumin as determined by capillary electrophoresis and by ultrafiltration was made. A variety of other ligands were then added to the buffer along with the protein, and the effects on mobility and enantioselectivity were studied. The displacers included (R)- and (S)-oxazepam hemisuccinate, (R)- and (S)-warfarin, nitrazepam, phenylbutazone, and octanoic acid. From the results obtained, it seems that capillary electrophoresis may be a useful, rapid method to screen for drug-drug interactions. There are some advantages of using this technique to study protein-ligand interactions: Only very small amounts of ligand are needed (useful when dealing with metabolites); for chiral compounds, if protein binding is stereoselective, then the method is also stereoselective, so single enantiomers are not needed; finally, measurements are obtained in solution, without the need for immobilization of the protein. A disadvantage is that the ligand and protein must have significantly different electrophoretic mobilities. © 1994 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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  • 2
    ISSN: 0952-3499
    Keywords: perfluorocarbon ; affinity chromatography ; counter-current ; lysozyme ; triazine dyes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In this work the development of a process capable of extracting proteins from particulate-containing solutions (such as fermentation broths) on a continuous basis, and in which adsorbent and process streams are contacted counter-currently is described. The process consists of four stages, required for the loading, washing, elution and regeneration of the adsorbent. Because of its counter-current nature, it has imporved performance over existing (though not yet commercialized) continuous processes, which have been based on CSTR-type contractors e.g. PERCAS (McCreath et al., 1993). The improved efficiency has been shown by carrying out extraction of lysozyme from a single component feed stream. The adsorbent used in this work is a Procion Red HE-7B-derivatized perfluorocarbon support, which has shown particular suitability for continuous processes due to its inherently high mechanical strength and high density. Results illustrating yields obtained using this equipment are presented and discussed.
    Additional Material: 7 Ill.
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  • 3
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As(Si1BuMe2)3 (1) was prepared by the salt-elimination reaction between (Na/K)3As and 1BuMe2SiCl. Mixing LiAs(SiMe3)2 with Ph3SiCl (1:1) yielded As(SiMe3)2(SiPh3) (2) in a good crystalline yield. Reaction of 2 (1:1) with Et3Ga gave the expected Lewis acid-base adduct Et3Ga · As(SiMe3)2(SiPh3) (3). The 1:1 mole ratio reaction of In(SePh)3 with As(SiMe3)3 resulted in a ligand redistribution around the indium and arsenic centers to afford As(SePh)3 (4) in a low yield. The solid-state structures of 1-4 have been established by single-crystal X-ray analysis. Crystal data for 1, monoclinic space group P 21/c, with a = 11.112(2), b = 17.453(2), c = 14.199(2) Å, β = 114.89° for Z = 4; 2, orthorhombic space group P c21n, with a = 9.236(1), b = 16.612(2), c = 16.803(4) Å for Z = 4; 3, monoclinic space group P 21/c, with a = 16.799(1), b = 11.199(2), c = 19.413(3) Å, β = 112.22(1) for Z = 4; 4, trigonal space group R &3macr;, with a = 12.863(5), c = 18.96(1) Å for Z = 6. © 1996 John Wiley & Sons, Inc.
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  • 4
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The MS80 is a high resolution mass spectrometer of exceptional sensitivity because of new design concepts in ion source technology. The use of hexapoles enables this high sensitivity specification to be maintained throughout the resolution range. This is of prime importance in selected ion monitoring at high resolution. The power of selected ion monitoring as a technique for the detection and estimation of trace compounds in complex samples is greatly increased by the use of new software for the DS55 data system which introduces considerable flexibility in data processing. The data is recorded using a computer controlled sweep superimposed on peak switching. The user may then choose to integrate the data over any portion of the recorded mass range to eliminate interfering materials and also to average over any time interval to improve signal-to-noise ratio. Peak profiles are continuously displayed during acquisition as a guide to the progress of an experiment and available on recall for post-run processing. The use of the MS80 with this new software is exemplified by the detection of TCDD at trace levels in the presence of other chlorinated materials.
    Additional Material: 5 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 9 (1997), S. 122-125 
    ISSN: 0899-0042
    Keywords: enantiomeric excess determination ; polarimetry ; HPLC ; enantiomers ; solvent effects ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations into the parameters affecting the sensitivity of polarimetric detectors for the determination of enantiomeric excess by achiral HPLC are presented. The results obtained showed that the specific optical rotation of an analyte was highly sensitive to the methanol content of the mobile phase. The purpose of this short communication is to demonstrate that “off-line” optical rotation measurements are a necessary part of the method development process for successful use of polarimetric detectors. Chirality 9:122-125, 1997, © 1997 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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  • 6
    ISSN: 0741-0581
    Keywords: Neurotransmitters ; Hair cells ; Inner ear efferents ; Amino acid uptake ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The cochlea is well suited for studies of the uptake properties of auditory neurons and nonneuronal supporting cells. Probe concentrations of radioisotopically labeled amino acids, including putative neurotransmitters and their precursors, breakdown products, and blockers, can be introduced via the natural, fluid-filled channels of the inner ear. Uptake patterns can be mapped at cellular and intracellular levels using light and electron microscopic autoradiographic methods. The procedures for introduction of label, fixation, plastic embedment, and light and electron microscopic autoradiography are described with special reference to the cochlea. Labeling patterns observed with over 20 amino acids are summarized for hair cells, spiral ganglion neurons, efferents, and nonneural elements of the stria vascularis, limbus, and modiolus. Limitations on the interpretation of results and their implications for the general usefulness of the methods are discussed.
    Additional Material: 12 Ill.
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  • 7
    ISSN: 0749-503X
    Keywords: yeast ; elongation factor-3 ; EF-3 ; homolog ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A paralog (intraspecies homolog) of the Saccharomyces cerevisiae YEF3 gene, encoding elongation factor-3, has been sequenced in the course of the yeast genome project, and identified by database searching; this gene has been designated HEF3. Bioinformatic and Northern blot analysis indicate that the HEF3 gene is not expressed during vegetative growth. Deletion of the HEF3 gene reveals no growth defects, nor any defects in mating or sporulation. A high copy 2μ clone of HEF3 was constructed, and was shown to be unable to complement a null allele of yef3. Finally, an in vitro assay for ribosome-stimulated ATPase activity was performed with isogenic HEF3 and Δhef3 strains; no difference in biochemical activity could be detected in these strains. From these results, we conclude that the HEF3 gene does not encode a functional homolog of YEF3. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
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  • 8
    ISSN: 0736-0266
    Keywords: Biosynthesis ; Intervertebral disc ; Proteoglycan aggregation ; Proteoglycan subunit structure ; Spinal fusion ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Posterior lumbar two-level spinal fusion was undertaken in 10 mature beagles. The animals were sacrificed 6 and 12 months later. Two months before sacrifice control and experimental animals received intravenously Na235 (1 mCi/Kg). Discs encompassed by the fusion and those adjacent to it were dissected into the nucleus pulposus and annulus fibrosus (AF), which were analysed separately. Proteoglycans (PGs) were extracted with 4.0 M guanidine HCL and purified by CsCL density gradient ultracentrifugation. The hydrodynamic size and ability of the PG subunits to aggregate in the presence of hyaluronic acide were investigated by Sepharose CL-2B chromatography. The PG subunits were analysed for their galactosamine (galN), glucosamine (glcN), hexuronic acid, and protein content or were subjected to digestion with papain or chondroitin -ABC-lyase to establish the size of the chrondroitin (CS) and keratan (KS) sulphate chains and the KS-PG core protein complex. Decreased ability to aggregate of PGs isolated from discs 6 and 12 months was generally the same or smaller than those in control tissues, the PG population present after 12 months was larger, particularly in the AF. Analysis of PG subunits from fusion discs afforded galN/glcN, galN/protein, and hexuronic acid/protein rotios that were compatible with the presence in these tissues of PGs in which the proportion of CS attached to core protein was greater than in control tissues. These. These studies provide the first experimental evidence that a metabolic response of discs in a fused segment may be accompanied by the biosynthesis of a new PG population whose structure is similar to that present in immature tissues.
    Additional Material: 7 Ill.
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  • 9
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dispersion of a pulse of O(3P) atoms in flowing helium has been analyzed by a modification of Taylor's method in order to determine the diffusion coefficient. Atoms of O(3P) were produced in a flowing stream of helium by a pulsed microwave discharge of molecular oxygen. After traversing a known length of the flow tube, the arrival time distribution of the O(3P) atoms was obtained using a mass spectrometer. The value obtained for D0 at 294 K, where D0 = D[He], is (2.40 ± 0.06) × 1019 cm-1 ·s-1, which corresponds to a diffusion coefficient of (731 ± 18) cm2/s at 1 torr. In addition to D0, analysis of the arrival time distributions gives an estimate of the mean flow velocity for O atoms in helium. There was no significant difference between the value of the velocity found this way and that obtained from the mean bulk gas flow measurement. Thus for this system there is no evidence for a chromatographic effect for O(3P) atoms on the walls of the flow tube.
    Additional Material: 6 Ill.
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  • 10
    ISSN: 0749-159X
    Keywords: Mathematics and Statistics ; Numerical Methods
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: While alternating direction implicit (ADI) collocation methods have been used for several years to solve parabolic problems in several space variables, no convergence analysis has been derived for any of these methods. We formulate and rigorously analyze ADI collocation schemes applied to the inhomogeneous heat and wave equations on the unit square subject to homogeneous Dirichlet boundary conditions and appropriate initial conditions. We prove that each method is second-order accurate in time and of optimal accuracy in space in the L2 and H01 norms. Numerical experiments confirm the predicted rates of convergence. © 1993 John Wiley & Sons, Inc.
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