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  • 1
    ISSN: 1435-2451
    Keywords: Key words Pancreatic cancer ; p53 ; Antisense oligodeoxynucleotides ; Cell culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Introduction: Pancreatic adenocarcinomas are largely resistant to apoptosis. More than 50% of pancreatic tumors reveal mutations in the p53 tumor suppressor gene. Methods: We investigated the growth of pancreatic tumor cells after downregulation of p53 protein expression by antisense oligodeoxynucleotides. Results: Proliferation and p53 expression of PancTu-I cells overexpressing mutant p53 protein were inhibited by antisense oligodeoxynucleotide treatment. When analyzed, two of three other pancreatic tumor cell lines with mutated p53 were also inhibited in their growth. Two of two wild-type (wt) p53 pancreatic tumor cells were not significantly influenced by p53 expression and were, only to a lesser extent, affected in their proliferation. K562 cells (lacking p53 mRNA) and normal human skin fibroblasts used as a target mismatch control showed no changes in proliferation rates with treatment. The different biological effects in the various cells were not caused by differences in the uptake of the oligodeoxynucleotides as monitored by confocal laser-scanning microscopy. Conclusions: Truncation and 5′- and 3′-lipophilic modifications of the oligodeoxynucleotides drastically enhanced the growth inhibition of PancTu-I cells, which were resistant to apoptosis-inducing agents. Furthermore, a higher sequence-specificity of the observed effects was achieved with these compounds.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0947-3440
    Keywords: Enediynes ; [2 + 2] Cycloaddition ; Bicyclo[3.2.0]heptanes ; Fragmentation ; Ring closing metathesis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two routes to 1,4-difunctionalized cycloheptenes are described. The first one is based on a fluoride-induced fragmentation reaction of the bicyclic [3.2.0]heptanesilyl monosulfate 10. This compound in turn was prepared by a ketene-cyclopentene cycloaddition route. An alternative strategy took advantage of a ring-closing metathesis (RCM) reaction of the diolefin 18 with the ruthenium catalyst 21. This reaction proved to be reliable even on a larger scale and allowed the isolation of the cycloheptene 19a in reasonably good yield.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 340 (1998), S. 175-177 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bromination of the disubstituted 4,5-dimethyl-1,3-cyclohexanedione (6) followed by oxidation of the resulting 3-bromo-5,6-dimethyl-2-cyclohexen-1-ones (7) gave 5-bromo-2,3-dimethylphenol (1) together with its constitutional isomer 3. The structure of 1 was secured by a x-ray analysis of its tosyl derivative 8.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 2043-2046 
    ISSN: 0947-3440
    Keywords: Dihydroxylation ; Tetrol ; Oxirane ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Double asymmetric dihydroxylation of 1,5-hexadiene gave in one step a mixture of the d,l/meso tetrols 6 in a ratio of 3.4:1. From this ratio a facial selectivity of 6.65:1 for each double bond can be calculated. As a consequence of the double reaction the d/l ratio can be estimated to be 44:1. Compound 6 served then as starting material for the preparation of the bis-epoxide 12 and the 2,5-dihydroxyhexane (13). While the separation of the diastereomers was not possible so far, this route for the preparation of 6, 12 and 13 might still be useful because it is very short and products derived from them might allow the crucial separation.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1-13 
    ISSN: 1434-193X
    Keywords: Dynemicin ; Enediynes ; Antitumor agents ; Antibiotics ; Cross-coupling ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Dynemicin A is a member of the family of enediyne natural products. It is unique in that it combines a ten-membered enediyne with an anthraquinone substructure. These features stimulated the development of synthetic approaches to the natural product itself and of analogs thereof. This review summarizes the total syntheses of dynemicin A. In addition, an overview of the known analogs is presented. The analogs can be classified according to the designed trigger mechanism. Most of the analogs contain a removable carbamate on the nitrogen atom. Others are quite similar to the natural lead in that they contain a quinone substructure, which upon reduction causes opening of the oxirane ring. In addition, there are analogs that contain an aromatic sector, the enediyne, and the oxirane ring but lack the nitrogen heterocycle. In these compounds the aryl ring assumes a different conformation from that in dynemicin A. Many of the simplified analogs proved to be quite active in vitro as well in vivo against murine tumor models. A highlight is compound 30 which is much more active than dynemicin A itself. However, looking at all analogs there is no clear-cut correlation between the DNA-cleaving ability at neutral pH and the in vitro results. From this one might conclude that there are possibly two mechanisms for antitumor activity. One involves diradical formation whereas the other might be due to a ligand-receptor interaction.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 340 (1998), S. 656-661 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Starting from the benzylidene lactone 3 of D-(-)-quinic acid the cyclohexyl fragment 15 (C-28-C-34 part) of the immunosuppressant FK506 was synthesized. Key steps include homolytic deoxygenation reactions on compounds 4 and 6 as well as a regioselective opening of the benzylidene acetal 5. Opening of the lactone 7 to provide the methyl ester 8 was followed by methylation of the hydroxy group to give 9. Further steps provided the aldehyde 12 which was elongated to the alkyne 15. This sequence provides 15 in gram quantities.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 109 (1997), S. 1854-1854 
    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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