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  • 1
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: In the absence of vitamin K or in the presence of the vitamin K antagonists, abnormal nonfunctional forms of prothrombin circulate in the blood. A reliable and reproducible technique, derived from traditional crossed affinoimmunoelectrophoresis in presence of calcium lactate, was developed and optimized. The technique is based on nondenaturing polyacrylamide gel affinoelectrophoresis, with calcium lactate, of plasma samples, followed by immunoblotting with rabbit anti-human prothrombin serum and detection with an anti-rabbit immunoglobulin peroxidase conjugate. Depending on the plasmas, one or two bands were visualized and quantified by densitometry of the immunoblots. The technique was able detect abnormal des-gamma-carboxylated prothrombins at concentration of 0.1 μg/mL.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0935-6304
    Keywords: Micellar electrokinetic chromatography ; Capillary electrophoresis ; Benzothiazole sulfenamides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0749-503X
    Keywords: RVS161 gene ; Saccharomyces cerevisiae ; stationary phase entry ; viability loss ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In yeast, nutrient starvation leads to entry into stationary phase. Mutants that do not respond properly to starvation conditons have been isolated in Saccharomyces cerevisiae. Among them the rvs161 mutant (RVS for Reduced Viability upon Starvation) is sensitive to carbon, nitrogen and sulphur starvation. When these nutrients are depleted in the medium, mutant cells show cellular viability loss with morphological changes. The mutation rvs161-1 is very pleiotropic, and besides the defects in stationary phase entry, the mutant strain presents other alterations: sensitivity to high salt concentrations, hypersensitivity to amino acid analogs, no growth on lactate or acetate medium. The addition of salts or amino acid analogs leads to the same morphological defects observed in starved cells, suggesting that the gene could be implicated mainly in the control of cellular viability. The gene RVS161 was cloned; it codes for a 30,252 daltons protein. No homology was detected with the proteins contained in the databases. Moreover, Southern analysis revealed the presence of other sequences homologous to the RVS161 gene in the yeast genome.
    Additional Material: 6 Ill.
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  • 4
    ISSN: 0749-503X
    Keywords: Chromosome III ; Saccharomyces cerevisiae ; mating type ; HML ; BUD5 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This paper reports the DNA sequence of a segment of 9·8 kb of the chromosome III. The sequenced DNA contains the MATα locus. The new sequence of the MATα locus differs from the previously reported sequence by six modifications in the W segment. We have found the same modifications in the HML locus. The corrected sequence contains, in HML, an open reading frame (ORF) of 190 codons which ends at the border between the W segment and the flanking DNA. In the MAT locus, this ORF extends in the flanking DNA up to 538 codons. This ORF corresponds to a gene independently identified as BUD5 (Chant et al., 1991). This gene presents homologies with the exchange factors SDC25 and CDC25. A large ORF of 1399 codons is found on the opposite side of MATα (toward the telomere). This ORF corresponds to a new gene YCR724. Next to this gene is a small ORF, YCR725, of 127 codons. The localization of this fragment on chromosome III, originally supposed to be distal from the MAT locus based on genetic distance, illustrates variation in recombination frequency along the chromosome and suggests the existence of hot spots of recombination between MAT and the THR4 locus.
    Additional Material: 5 Ill.
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  • 5
    ISSN: 0741-0581
    Keywords: BrdU incorporation ; Cultured cells DNA replication ; Electron microscopy ; EM immunocytochemistry ; Immunocytochemistry ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: In the present study, we have optimized an immunocytochemical ultrastructural approach for in situ localization of newly synthesized DNA in unsynchronized as well as in synchronized human HeLa cells and in exponentially growing mouse P815 cells, which had incorporated bromodeoxyuridine (BrdU) during short pulses varying from 1 to 20 minues. The incorporated BrdU was detected in hydrolyzed ultrathin cryosections or Lowicryl sections by means of a monoclonal antibody, revealed by secondary colloidal gold-labeled probes. The results demonstrate our ability to study, with high resolution and reproducibility, DNA replication during consecutive periods of the S-phase, which is monitored by the incorporation of tritiated thymidine. In addition, this approach allows one to perform a concomitant mapping of replicated DNA and various enzymes of the replisome.
    Additional Material: 14 Ill.
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  • 6
    ISSN: 0749-1581
    Keywords: 2-Fluoro-2-phenylacetic acid ; Chiral derivatizing agent ; Configuration of secondary alcohols containing substituted-phenyl groups ; Fluorine NMR ; Effect on δF across the space ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of 2-fluoro-2-phenylacetic acid as a chiral derivatizing agent allowed the distinction, by means of fluorine NMR spectroscopy, of enantiomers of alcohols L1CH(OH)L2 converted into the diastereoisomeric esters PhCHFCO2CHL1L2. The δF(RR) and δF(RS) fluorine chemical shifts of diastereoisomeric esters obtained from series of alcohols containing a substituted-phenyl group (L1 or L2 = ZPh), and the ΔδF chemical shift differences, were linearly related to the Hammet σ parameter of Z. The ΔδF originates from the different electronic effects of L1 and L2 groups on the fluorine atom, through space, in a minor conformation. A classification of the ZPh effects on δF with respect to Ph is obtained. The configuration of substituted-phenyl secondary alcohols, ZPhCH(OH)L, can be determined with the aid of the δF values of esters formed with PhCHFCO2H if the configuration of the unsubstituted alcohol PhCH(OH)L is known.
    Additional Material: 2 Ill.
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  • 7
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The use 4-hydroxybenzenesulfonic acid as reduction-inhibiting and general purpose matrix in fast-atom bombardment liquid secondary-ion mass spectrometry (FAB/LSIMS) is discussed. Results obtained in a comparative study using the disulfide-bridge containing peptide deaminoarginine-vasopressin and several commonly used matrices indicate that the reduction-inhibitaing efficiency of 4-hydroxybenzenesulfonic acid is comparable to that of 3-nitrobenzyl alcohol while recuction is found to be important in matrices such as thioglycerol and glycerold. Experiments conducted on peptides such as met-enkephalin and bradykinin, nucleosides and other polar compounds reveal that 4-hydroxybenzenesulfonic acid is a good solvent and has physical properties which are similar to those of glycerol. This new matrix material is a radical scavenger, surface active, allows persistent secondary-ion beams and produces a low background signal. The matrix, 4-hydroxy-benzenesulfonic acid, generally yields high quality mass spectra which compare well with those obtained in either glycerol or 3-nitrobenzyl alcohol.
    Additional Material: 3 Ill.
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  • 8
    ISSN: 1040-452X
    Keywords: Flow cytometry ; Sperm sorting ; DNA staining ; Bovine Y specific probe ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Flow cytometry is a potential method for the separation of X and Y bearing spermatozoa, on the basis of their relative DNA content evaluated by the fluorescence emission intensity due to specific fluorochrome DNA staining. However, spermatozoa DNA is highly condensed and nuclei exhibit flat non spherical shape, which can produce artefacts impeding accurate analysis. In order to avoid these limitations, decondensation of DNA performed by enzymatic treatment and a modification of the flow cytometer that orients the spermatozoa relative to the laser beam are generally used. In this work, we describe alternative methods and materials for selection of (1) decondensed and thus dead spermatozoa without orientation, sorted on the basis of only the 10% spermatozoa containing the least DNA (expected Y) and the 10% spermatozoa containing the more DNA (expected X), or (2) native spermatozoa homogeneously oriented using a simultaneous measurement of Axial light loss (extinction) and Forward angle light scatter. For testing enrichment of each selected fraction we have worked out a molecular hybridization procedure using X and Y specific DNA probes. We analyse and sort bull spermatozoa on these basis: the purity obtained for these fractions is 80% without orientation after enzymatic treatment, and 70% on live spermatozoa “optically” oriented.
    Additional Material: 6 Ill.
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  • 9
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The biotransformation of 6-benzoyl benzoxazolinone (6-BB), a non-narcotic peripheral analgesic, was studied in eight healthy volunteers after oral administration of a single dose of 1 g. Urinary metabolites were extracted either with ethyl acetate at different pH values or by percolating at pH 5 through Amberlite XAD 2 ion-exchange resin. Eluates were concentrated under vacuum, purified by thin-layer chromatography and analysed by gas chromatography/mass spectrometry or direct insertion probe mass spectrometry. Metabolites were identified with reference to the mass spectra of various synthesized compounds assumed to be metabolites of 6-BB, as N-methylated or monohydroxylated compounds. Another metabolic pathway was cleavage of the benzoxazolinone heterocycle giving 2-amino-5-benzoyl phenol after hydrolysis and decarboxylation. N-methyl, N-acetyl and hydroxylated metabolites having an amino-5-benzoyl phenol structure were also found.
    Additional Material: 6 Ill.
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  • 10
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The results obtained during the isothermal curing of diglycidyl ether of bisphenol-A-based thermosets cross-linked with pure diaminodiphenyl methane and pure diaminodiphenyl sulfone and with their mixtures have been analyzed to determine how the dc conductivity changes with time during the conversion of its liquid to a gel. The complex permittivity data are first analyzed to show that ac measurements can be used to obtain the ionic conductivity over a considerable period of the curing process. The procedure allows one to obtain the dc conductivity without having data as a function of frequency. The shape of the complex plane plots of the electrical modulus are semicircles, but with small deviations that appear at long times during the curing process. The dielectric consequences of the chemical changes with time during the cross-linking of the thermoset are analogous to the frequency dependence of the complex permittivity of a liquid. The analysis shows that the dc conductivity σo of a thermoset during its cure follows a power law, σo∝ (tg - t)x, where t is the curing time (t 〈 tg). The results can also be described equally well by a new equation, σo ∝ exp[ - B/(to - t)], where x, tg, B, and to are empirical constants all of which vary with the temperature of the cure. tg is close to the time for gelation known from independent studies and to is close to but longer than the time for vitrification. These conclusions are discussed in terms of scaling concepts for the gelation phenomenon.
    Additional Material: 8 Ill.
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