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  • Biochemistry and Biotechnology  (7)
  • Cell & Developmental Biology  (4)
  • Mn species  (3)
  • 1
    ISSN: 1573-5117
    Keywords: pore water ; lake sediments ; Fe species ; Mössbauer ; Mn species ; heavy metals ; authigenic mineral phases ; Lac Léman
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pore fluids of the sediments collected at the deepest point of Lac Léman (Switzerland) are supersaturated with respect to vivianite and siderite. In the presence of sulphide, the iron solubility is controlled entirely by the amorphous iron sulphides. As the iron (II) becomes dominant, the formation of siderite occurs and evidence of this, in the solid phase, can be obtained by the use of Mössbauer spectroscopy and some sequential chemical extractions. The amount of ‘siderite iron’ decreases from about 10% near the sediment surface to a few percent in the lower levels of the sediment (〈10 cm). Evidence for vivianite formation could not be obtained even in the lower layers, despite the precautions taken to avoid oxidation. Although the trace metal behaviour in the solid phase is well correlated with the iron and manganese, availability in the pore fluid is dependent on the adsorption on, or co-precipitation with, finely dispersed colloids, which pass through a 0.45 µg filter. Trace metal concentrations in pore fluid were not directly related to total elemental concentrations in the solid phase, and did not reflect cumulative trends associated with anthropogenic enrichment.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-5117
    Keywords: pore water ; lake sediments ; Fe species ; Mössbauer ; Mn species ; heavy metals ; authigenic mineral phases ; Lac Léman
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pore fluids of the sediments collected at the deepest point of Lac Léman (Switzerland) are supersaturated with respect to vivianite and siderite. In the presence of sulphide, the iron solubility is controlled entirely by the amorphous iron sulphides. As the iron (II) becomes dominant, the formation of siderite occurs and evidence of this, in the solid phase, can be obtained by the use of Mössbauer spectroscopy and some sequential chemical extractions. The amount of ‘siderite iron’ decreases from about 10% near the sediment surface to a few percent in the lower levels of the sediment (〈10 cm). Evidence for vivianite formation could not be obtained even in the lower layers, despite the precautions taken to avoid oxidation. Although the trace metal behaviour in the solid phase is well correlated with the iron and manganese, availability in the pore fluid is dependent on the adsorption on, or co-precipitation with, finely dispersed colloids, which pass through a 0.45 µg filter. Trace metal concentrations in pore fluid were not directly related to total elemental concentrations in the solid phase, and did not reflect cumulative trends associated with anthropogenic enrichment.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5117
    Keywords: pore water ; lake sediments ; Fe species ; Mössbauer ; Mn species ; heavy metals ; authigenic mineral phases ; Lac Léman
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pore fluids of the sediments collected at the deepest point of Lac Léman (Switzerland) are supersaturated with respect to vivianite and siderite. In the presence of sulphide, the iron solubility is controlled entirely by the amorphous iron sulphides. As the iron (II) becomes dominant, the formation of siderite occurs and evidence of this, in the solid phase, can be obtained by the use of Mössbauer spectroscopy and some sequential chemical extractions. The amount of ‘siderite iron’ decreases from about 10% near the sediment surface to a few percent in the lower levels of the sediment (〈10 cm). Evidence for vivianite formation could not be obtained even in the lower layers, despite the precautions taken to avoid oxidation. Although the trace metal behaviour in the solid phase is well correlated with the iron and manganese, availability in the pore fluid is dependent on the adsorption on, or co-precipitation with, finely dispersed colloids, which pass through a 0.45 µg filter. Trace metal concentrations in pore fluid were not directly related to total elemental concentrations in the solid phase, and did not reflect cumulative trends associated with anthropogenic enrichment.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 45 (1991), S. 207-212 
    ISSN: 0730-2312
    Keywords: hyposmolarity ; swelling ; free amino acids ; DIDS ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Rabbit lymphocytes exposed to hyposmotic media first swell and then recover their initial volume within 6 min. During volume recovery, free amino acids (FAA) decrease from 451.1 to 208 nmoles/mg protein. Taurine was the dominating FAA, accounting for 70% of the FAA pool. The time course of 3H-taurine release induced by hyposmolarity followed that of volume recovery. Efflux of 3H-taurine in an 8 min period was 17.8% (of total labeled taurine accumulated during loading) in an isosmotic medium. Reducing osmolarity to 0.87, 0.75, 0.62, and 0.5 increased this release to 24.8%, 38.1%, 56.4% and 70.9%, respectively. The volume-sensitive release of 3H-taurine was unaffected by omission of external Na+ or Ca++ and was reduced by 23% in the absence of Cl-. It was unaffected by agents disrupting the cytoskeleton or by tetraethylammonium, barium, quinidine, and gadolinium, but was 26% reduced by DIDS. Taurine release was inhibited at 4°C, but was unchanged at 15°C or 25°C. An involvement of FAA, particularly taurine, in lymphocyte volume regulation is suggested.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 2 (1988), S. 121-128 
    ISSN: 0884-3996
    Keywords: Chemiluminescence ; acridinium ester ; surfactants ; proteins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: In order to establish optimum conditions for the chemiluminescent (CL) reaction of two acridinium ester labelled proteins (human albumin and rabbit anti-human albumin IgG), we investigated the effects of the following factors known to influence the CL emission: pH, presence of proteins, relative concentrations of components of CL reaction and presence of surfactants. Under optimal conditions of pH and hydrogen peroxide concentration, hexadecyl trimethyl ammonium chloride (CTAC) increased the intensity of the CL reaction of the acridinium ester labelled albumin by 42-fold. Triton X-100, Tween-20, 23 lauryl ether (Brij 35) and sodium dodecyl sulphate (SDS) exerted a much smaller effect. In the case of the acridinium ester labelled antibody, the greatest increase was obtained with Triton X-100 (15-fold) followed by CTAC, Brij 35 and Tween 20 (SDS decreased the emission intensity).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 10 (1995), S. 175-184 
    ISSN: 0884-3996
    Keywords: Luminol ; enhanced chemiluminescence ; phenolic acid ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We explored the behaviour of a series of phenolic acids used as enhancers or inhibitors of luminol chemiluminescence by three different methods to determine if behaviour was associated with phenolic acid structure and redox character. All the phenolic acids inhibited chemiluminescence when hexacyanoferrate(III) was reacted with the phenolic acids before adding luminol. The redox character of these compounds was clearly related to structure. When hexacyanoferrate(III)-luminol-O2 chemiluminescence was initiated by phenolic acid-luminol mixtures some phenolic acids behaved as enhancers of chemiluminescence, and others as inhibitors. We propose a mechanism to explain these findings. We found direct relationships between the redox character of the phenolic acids and the enhancement or inhibition of the chemiluminescence of the luminol-H2O2-peroxidase system and we propose mechanism to explain these phenomena.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 12 (1997), S. 199-205 
    ISSN: 0884-3996
    Keywords: luminol ; fluorescein ; enhancement chemiluminescence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The chemiluminescence of the luminol-H2O2-horseradish peroxidase system is increased by fluorescein. Fluorescein produces an enhancement of the luminol chemiluminescence similar to that of phenolphthalein, by an energy transfer process from luminol to fluorescein. The maximum intesity and the total chemiluminescence emission (between 380 and 580 nm) of luminol with fluorescein was more than three times greater than without fluorescein; however, the emission duration was shorter. The emission spectra in the presence of fluorescein had two maxima (425 and 535 nm) and the enhancement was dependent on pH and fluorescein concentration. A mechanism is proposed to explain these effects. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 75-84 
    ISSN: 0884-3996
    Keywords: luminol ; enhanced chemiluminescence ; phenol ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Systematic studies on phenol derivatives facilitates an explanation of the enhancement or inhibition of the luminol-H2O2-horseradish peroxidase system chemiluminescence. Factors that govern the enhancement are the one-electron reduction potentials of the phenoxy radicals (PhO•/PhOH) vs. luminol radicals (L•/LH-) and the reaction rates of the phenol derivatives with the compounds of horseradish peroxidase (HRP-I and HRP-II). Only compounds with radicals with a similar or greater reduction potential than luminol at pH 8.5 (0.8 V) can act as enhancers. Radicals with reduction potentials lower than luminol behave in a different way, because they destroy luminol radicals and inhibit chemiluminescence. The relations between the reduction potential, reaction rates and the Hammett constant of the substituent in a phenol suggest that 4-substituted phenols with Hammett constants (σ) for their substituents similar or greater than 0.20 are enhancers of the luminol-H2O2-horseradish peroxidase chemiluminescence. In contrast, those phenols substituted in position 4 for substituents with Hammett constants (σ) lower than 0.20 are inhibitors of chemiluminescence. On the basis of these studies, the structure of possible new enhancers was predicted. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 3 Ill.
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  • 9
    ISSN: 0003-276X
    Keywords: Dental crest ; cartilago mandibularis ; foramen mentale ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A correlation was sought between the organization of the dental crest and the ossification of the corpus mandibulae in 14 human embryos and 13 human fetuses. The different types of ossification between the corpus and the ramus mandibulae suggest that the cartilago mandibularis (meckeliensis) guides the formation of the mandibula, while the dental crest acts as a coorganizer. In the area of the foramen mentale, the lamina dentalis begins to invaginate (to give rise to the dental crest), and at this level intramembranous ossification of the corpus mandibulae commences. These findings, together with the presence of the cartilago mandibularis before the appearance of the dental crest, and the fact that the former is seen along the entire length of the mandibula (from the symphysis mandibulae to the capsula otica), support the hypothesis that the dental crest, rather than the cartilago mandibularis, acts as the coorganizer in the corpus mandibulae. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 10 (1995), S. 285-289 
    ISSN: 0884-3996
    Keywords: Cholinesterase ; luminol ; pro-enhancer ; chemiluminescence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: 2-Naphthyl acetate acts as a pro-enhancer of the luminol-H2O2-horseradish peroxidase reaction. Cholinesterase hydrolyses the bound acetyl group and produces 2-naphthol, and this compound is an enhancer of the chemiluminescent reaction. We studied the kinetics of chemiluminescent emission and the influence of 2-naphthyl acetate and cholinesterase enzyme concentration. The cholinesterase concentration versus chemiluminescence intensity maximum was linear for cholinesterase between 0 and 181 μU/mL, with a detection limit of 8 μU/mL and a relative standard deviation of 9.5% (n = 3), for a sample containing 90.67 μU/mL of cholinesterase.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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