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  • 1
    ISSN: 0935-6304
    Keywords: Epoxytriacylglycerols ; high temperature gas chromatography ; hydroxytriacylglycerols ; ketotriacylglycerols ; lipids ; negative chemical ionization mass spectrometry ; SOP-50 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Five seed oils consisting of unusual triacylglycerols have been examined by high temperature gas chromatography using glass capillary columns coated with the stationary phase SOP-50 (50%-diphenyl-50%-dimethylpolysiloxane, methoxy-terminated). The investigated hydroxy, epoxy, and ketokonjuene triacylglycerols were first derivatized in order to permit analysis by high temperature gas chromatography. Structural elucidation of the intact triacylglycerols was performed with high temperature gas chromatography/negative chemical ionization-mass spectrometry using NH3 as a reagent gas. Individual derivatized lipid species with a molecular weight up to 1176 g/mol could be identified.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0935-6304
    Keywords: cis-13-Eicosenoic Acid (Paullinic Acid) ; Cyanolipids ; Fatty acids ; GLC-MS ; NMR spectroscopy ; Oxazoline derivatives ; Paullinia elegans Sapindaceae ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fatty acids of the total lipids, triglycerides, and the cyanolipid of Paullinia elegans (Sapindaceae) have been analyzed as their methyl esters and 4,4-dimethyloxazoline derivatives by gas chromatography-mass spectrometry. It was shown that the gas chromatographic separation of the oxazoline derivatives was sufficient to ensure the correct identification of the monoenic fatty acid positional isomers. Stereochemistry of the double bonds has been confirmed by infrared and 13C-nuclear magnetic resonance (NMR) spectroscopy. cis-13-Eicosenoic Acid (Paullinic acid) (44.4%) and cis-11-octadecenoic acid (cis-vaccenic acid) (19.8%) were found to be the main components beside other monoenoic acid positional isomers. The cyanolipid of P. elegans was identified as 2,4-dihydroxy-3-methylenebutyronitrile derivative by IR, 1H-NMR, 13C-NMR spectroscopy and was quantified by 1H-NMR spectroscopy (71.4%).
    Additional Material: 3 Ill.
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  • 3
    ISSN: 0935-6304
    Keywords: α-Monoacetotriacylglycerides ; Celastraceae ; Fatty acids ; GLC ; GLC-(NCI)MS ; Maytenus seed oils ; OV-225-OH, OH-terminated ; SOP-50, methoxy-terminated ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The seed oils of three Maytenus species have been examined by high temperature GLC using SOP-50 (methoxy-terminated) and OV-225-OH (OH-terminated) glasscapillary columns. The main compounds (71-76%) could be identified as α-mono-acetotriacylglycerols by a combination of high temperature GLC-MS in negative chemical ionization mode with a CH4/N2O mixture as reactant gas and other spectroscopical methods (infrared, 1H- and 13C-nuclear magnetic resonance spectroscopy). The OV-225-OH phase demonstrated better separation properties that the SOP-50 phase for this substance class and up to eight species of α-monoacetotriacylglycerols could be separated. The content of usual triacyclglycerols was below 1%. The results of the analysis of the individual fatty acids as their methyl esters by GC and GC-MS are also presented.
    Additional Material: 2 Ill.
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  • 4
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The synthesis of 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) is the first commitment of resources toward aromatics production in Escherichia coli. DAHP is produced during a condensation reaction between phosphoenolpyruvate (PEP) and erythrose 4-phosphate (E4P) catalyzed by DAHP synthases (coded by aroF, aroG, and aroH). Stoichiometric analysis has shown a severe PEP limitation in the theoretical yield of DAHP production from glucose due to the phosphotransferase system (PTS) for sugar uptake. This limitation can be relieved by (i) the recycling of pyruvate from PEP using PEP synthase (Pps) or (ii) use of non-PTS sugars such as xylose. Previous studies have shown the usefulness of overexpressing tktA (encoding transketolase), aroG, and pps (PEP synthase) for DAHP production in an aroB strain unable to utilize DAHP further. In the present study we confirm the predictions of the stoichiometric analysis by introducing pps, tktA, and aroG into vectors under independently controlled promoters. In glucose medium, although TktA has some positive effect on the final DAHP concentration, it has no effect on the yield (percent conversion). With Pps overexpression, the DAHP concentration produced from glucose is increased almost twofold and the yield is approaching the theoretical maximum, as predicted by the stoichiometric analysis. However, this Pps effect is observed only in the presence of both increased AroG and TktA. In xylose mimimal medium, the final DAHP concentration and the yield are completely determined by the AroG activity. TktA and Pps play no or insignificant roles, and the yield can reach the theoretical maximum without overexpression of these two enzymes. The results shown here are important for both rational design of metabolic pathways and industrial production of aromatics such as tryptophan, phenylalanine, indigo, quinic acid, and catechol.
    Additional Material: 9 Ill.
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  • 5
    ISSN: 0730-2312
    Keywords: explant culture ; stimulation of DNA synthesis ; inhibition of functional differentiation ; endogenous TGFα ; arachidonic acid release ; phospholipase A2 ; metabolic inhibitors ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Epidermal growth factor (EGF) has been suggested to be involved in mammary gland development by mitogenic stimulation of the ductal and alveolar epithelium in virgin mice. The present studies demonstrate that also in late-pregnant mice EGF leads to proliferation of the ductal, ductular, and alveolar epithelium. The mitogenic effect is associated with structural and functional dedifferentiation of alveolar cells as revealed by analysis of morphology, expression of cytosolic and secretory proteins, and fatty acid synthesis. Using a combination of metabolic inhibitors, the dedifferentiating effect of EGF could be blocked while the mitogenic action was not influenced. This finding demonstrates that the signal transduction pathway leading to dedifferentiation and mitosis can be separated, and that the dedifferentiating effect of EGF is independent of its mitogenic properties, but is probably mediated by activation of the arachidonic acid-dependent pathways (cyclo- and lipoxygenase pathways). Release of arachidonic acid from the endogenous phospholipid pool was found to be an early response of the explants to EGF. Accordingly, arachidonic acid itself proved to be capable of inducing epithelial dedifferentiation but failed to stimulate proliferation. TGFα showed qualitatively similar effects as EGF but was generally a stronger agonist. It is suggested that EGF and TGFα also play a role in mammary gland physiology during pregnancy by final developing and maintanance of the lobulo-alveolar structure in the mammary gland and prevention of premature onset of lactation, and that this is mediated through the PLA2-arachidonic acid signalling cascade.
    Additional Material: 4 Ill.
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  • 6
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Antiprogestins possess a potent antitumor activity in hormone-dependent experimental breast cancer models. Though the underlying mechanism is not clear, induction of functional differentiation seems to be a major event. This study attempts to test directly for antiproliferative and differentiation promoting activities of antiprogestins on the normal mammary gland. To this end, whole organ cultures of mammary glands from estradiol/progesterone-primed virgin mice maintained in a serum-free medium with aldosterone, prolactin, insulin, and hydrocortisone were exposed to the antiprogestin ZK114043. A 4-day treatment of organ cultures led to a strong inhibition of epithelial DNA synthesis. In parallel, ZK114043 caused alveolar cells to acquire a more differentiated phenotype distinguished by secretory active alveoli composed of single cell layers with increased fat droplet accumulation and enhanced expression of the milk proteins b̃-casein and whey acidic protein (WAP). Particularly strong effects were found on the expression of mammary-derived growth inhibitor (MDGI). Both half-maximal inhibition of epithelial DNA synthesis and stimulation of MDGI mRNA expression were found at about 5 ng/ml of ZK114043. Presence in the medium of 5 m̈g/ml hydrocortisone rendered antiglucocorticoid effects of ZK114043 highly unlikely. Furthermore, prevention of action of ZK114043 by the progesterone agonist R5020 and ZK114043 stimulated expression of b̃-casein and MDGI mRNA in cultured glands of 10-week-old unprimed virgin mice suggest a progesterone receptor-mediated mechanism of antiprogestin action. Two other antiprogestins, Mifepristone and Onapristone, likewise stimulated MDGI expression. The data provide direct evidence that antiprogestins act like a differentiation factor in the normal mammary gland. © 1995 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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