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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 267 (1977), S. 620-621 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Female rats of the Sprague-Dawley strain were obtained when 42 days of age. All the animals initially received stock diet (Wayne Lab Meal) and tap water ad libitum. NMU was dissolved in physiological saline (20mgml1) which had been adjusted to pH 5.0 with a few drops of 3% acetic acid. Rats ...
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-7217
    Keywords: vorozole ; aromatase inhibitors ; mammary tumors ; apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Vorozole (Vz) is a competitive non-steroidal inhibitor of aromatase, which has been used to treat breast cancer in postmenopausal women and in various chemoprevention pre-clinical studies. Recently, we assessed the inhibitory effect of Vz on Mnu-induced mammary carcinogenesis (Lubet et al., 1994), as well as on the progression of mammary tumors (Lubet et al., 1998). In this study we evaluated the effects of Vz on tumor growth, serum estradiol, cell proliferation, apoptotic and non-apoptotic cell death to determine whether any of these 'surrogate’ markers might reflect the efficacy of various doses of Vz. Vz at doses of 2.5 (Hi), 0.32 (Md), and 0.08 (Lo) mg/kg body weight induced complete (100%), 60%, and 20% regression of mammary tumors, respectively. Vz at Hi and Md doses caused a decrease in serum estradiol within the first two days of treatment, and the estradiol values remained low with additional treatment for 4 and 10 days. When Vz was administered to animals bearing palpable tumors a time and dose-dependent decrease in the proliferating cells (BrdU-LI) was observed. The percentage of apoptotic cells (Al) sharply increased 2 days after initiation of Vz treatment and then decreased followed by an increase in non-apoptotic dead cells. Interestingly even the Lo dose of Vz, which was only moderately effective in suppressing tumor growth, decreased cell proliferation and increased cell death in the peripheral tumor areas at 4 and 10 days after initiation of treatment. The time- and dose-dependent alterations in various cell parameters suggest two different phases of Vz-induced cellular responses: (1) an early phase (2–4 days of treatment) with a sharp increase in apoptotic cells and decrease in proliferating cells, and (2) a later phase (10 days) with disintegration of tumor parenchyma, increase in non-apoptotic dead cells, and decrease in apoptotic cells. The dose-dependent decrease in proliferating cells and increase in apoptotic and non-apoptotic cell death in Vz-treated animals suggest that these biomarkers might be used as potential surrogate endpoints for efficacy in breast cancer chemoprevention and therapy studies with aromatase inhibitors.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0730-2312
    Keywords: Animal models ; carcinogenesis ; chemoprevention ; drug development ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: In the NCI, Chemoprevention Branch drug development program, potential chemopreventive agents are evaluated for efficacy against chemical carcinogen-induced tumors in animal models. This paper summarizes the results of 144 agents in 352 tests using various animal efficacy models. Of these results, 146 were positive, representing 85 different agents.The target organs selected for the animals model are representative of high-incidence human cancers. The assays include inhibition of tumors induced by MNU in hamster trachea, DEN in hamster lung, AOM in rat colon (including inhibition of AOM-induced aberrant crypts), MAM in mouse colon, DMBA and MNU in rat mammary glands, DMBA promoted by TPA in mouse skin, and OH-BBN in mouse bladder.The agents tested may be classified into various pharmacological and chemical structural categories that are relevant to their chemopreventive potential. These categories include antiestrogens, antiinflammatories (e. g., NSAIDs), antioxidants, arachidonic acid metabolism inhibitors, GST and GSH enhancers, ODC inhibitors, protein kinase C inhibitors, retinoids and carotenoids, organosulfur compounds, calcium compounds, vitamin D3 and analogs, and phenolic compounds (e. g., flavonoids). The various categories of compounds have different spectra of efficacy in animal models. In hamster lung, GSH-enhancing agents and antioidants appear to have high potential for inhibiting carcinogenesis. In the colon, NSAIDs and other antiinflammatory agents appear particularly promising. Likewise, NSAIDs are very active in mouse bladder. In rat mammary glands, retinoids and antiestrogens (as would be expected) are efficacious. Several of the chemicals evaluated also appear to be promising chemopreventive agents based on their activity in several of the animal models. Particularly, the ODC inhibitor DFMO was active in the colon, mammary glands, and bladder models, while the dithiolthione, oltipraz, was efficacious in all the models listed above (i. e., lung, colon, mammary glands, skin, and bladder). 1994 Wiley-Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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