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  • 1
    Keywords: RECEPTOR ; SPECTRA ; ANGIOGENESIS ; CANCER ; GROWTH ; GROWTH-FACTOR ; IN-VITRO ; INHIBITOR ; proliferation ; SURVIVAL ; tumor ; ADVANCED SOLID TUMORS ; AGENTS ; ANGIOSTATIN ; BLOOD ; carcinoma ; CELL ; CELL LUNG-CANCER ; CELL-PROLIFERATION ; CLINICAL-TRIAL ; COMBINATION ; DOPPLER ; ENDOTHELIAL GROWTH-FACTOR ; evaluation ; FACTOR RECEPTOR ; Germany ; human ; IN-VIVO ; INHIBITION ; KINASE ; LUNG ; MICROSCOPY ; MICROVESSEL DENSITY ; MODEL ; MODELS ; neoplasms ; PATHWAY ; PATHWAYS ; PERFUSION ; PHASE-I ; PROSTATE ; RECOMBINANT HUMAN ENDOSTATIN ; THERAPY ; TOXICITY ; tumor growth ; TYROSINE KINASE ; VITRO ; VIVO
    Abstract: The multifaceted nature of the angiogenic process in malignant neoplasms suggests that protocols that combine antiangiogenic agents may be more effective than single-agent therapies. However it is unclear which combination of agents would be most efficacious and will have the highest degree of synergistic activity while maintaining low overall toxicity. Here we investigate the concept of combining a "direct" angiogenesis inhibitor (endostatin) with an "indirect" antiangiogenic compound [SU5416, a vascular endothelial growth factor receptor 2 (VEGFR2) receptor tyrosine kinase (RTK) inhibitor]. These angiogenic agents were more effective in combination than when used alone in vitro (endothelial cell proliferation, survival, migration/invasion, and tube formation tests) and in vivo. The combination of SU5416 and low-dose endostatin further reduced tumor growth versus monotherapy in human prostate (M), lung (A459), and glioma (U87) xenograft models, and reduced functional microvessel density, tumor microcirculation, and blood perfusion as detected by intravital microscopy and contrast-enhanced Doppler ultrasound. One plausible explanation for the efficacious combination could be that, whereas SU5416 specifically inhibits vascular endothelial growth factor signaling, low-dose endostatin is able to inhibit a broader spectrum of diverse angiogenic pathways directly in the endothelium. The direct antiangiogenic agent might be able to suppress alternative angiogenic pathways up-regulated by the tumor in response to the indirect, specific pathway inhibition. For future clinical evaluation of the concept, a variety of agents with similar mechanistic properties could be tested
    Type of Publication: Journal article published
    PubMed ID: 14695206
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  • 2
    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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  • 3
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Absorbance-temperature profiles have been determined for the following self-complementary oligonucleotides or equimolar paris of complementary oligonucleotides containing GC base pairs: A2GCU2, A3GCU3, A4GCU4, A6CG + CGU6, A8CG + CGU8, A4G2 + C2U4, A5G2 + C2U5, A4G3 + C3U4, and A5G3 + C3U5. In all cases cooperative melting transitions indicate double-helix formation. As was found previously, the stability of GC containing oligomer helices is much higher than that of AU helices of corresponding length. Moreover, helices with the same length and base composition but different sequences also have quite different stabilites. The melting curves were andlyzed using a zipper model and the thermodynamic parameters for the AU pairs determined previously. The effect of single-strand stacking was considered separately. According to this model, the formation of a GC pair from unstacked single strands is associated with an ethalpy change of -15 kcal/mole. Due to the high degree of single-strand stacking at room temperature the enthalpy change for the formation of GC pairs from unstacked single strands is only -5 to -6 kcal/mole. (The corresponding parameters for AU pairs are -10.7 kcal/mole and -5 to -6 kcal/mole.) The sequence dependence of helix stability seems to be primarily entropic since no differences in ΔH were seen among the sequence isomers.The kinetics of helix formation was investigated for the same molecules using the temperature jump technique. Recombination of strands is second order with rate constants in the range of 105 to 107M-1 sec-1 depending on the chain length and the nucleotide sequence. Within a series of oligomers of a given type, the rates of recombination decrease with increasing chain length. Oligomers with the sequence AnGCUn recombine six to eight times slower than the other oligomers of corresponding chain length. The experimental enthalpies of activation of 6 to 9 kcal/mole suggest a nucleation length of one or two GC base pairs. The helix dissociation process has rate constants between 0.5 and 500 sec-1 and enthalpies of activation of 25 to 50 kcal/mole. An increase of chain length within a given nucleotide series leads to decreased rates of dissociation and increased enthalpies of activation. An investigation of the effect of ionic strength on AnGCUn helix formation showed that the rates of recombination increase considerably with increased ionic strength.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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