Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1524-4741
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Chemoprevention, or intervention with chemical agents at the precancer stage to avoid or slow the development of the carcinogenic process, is one strategy to reduce both the incidence of breast cancer and its mortality. Systematic development of cancer chemopreventive drugs calls for evaluation of pre-clinical efficacy in well-characterized in vitro screens and animal cancer models. Highly promising agents are also included in traditional pre-clinical toxicity tests performed in two species. The most promising and least toxic agents enter clinical trials, including both phase I safety and pharmacokinetics evaluations and phase II and III efficacy studies. The use of populations with defined, measurable biologic alterations in tissue occurring prior to cancer development, i.e. intermediate biomarkers, is important to successful phase II chemoprevention trials. The intermediate biomarkers may be of several types, such as histological/premalignant lesions, proliferative, genetic/regulatory, differentiation-related, or biochemical. For example, ductal and lobular carcinoma in situ are premalignant lesions in the human breast. These lesions are tissue at very high risk of malignant progression and also have the potential to be modulated by chemopreventive agents. In addition, other types of biomarkers may be identified within the lesions. These biomarkers could then serve as surrogate trial end-points, instead of cancer incidence, for use in shorter, less costly trials.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @breast journal 1 (1995), S. 0 
    ISSN: 1524-4741
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Surrogate endpoint biomarkers (SEBs) are tissue changes observed in premalignant disease that highly correlate with cancer risk. They are urgently needed as endpoints in clinical trials of chemopreventive agents for breast premalignant disease because they require less time, money and effort compared to the conventional endpoint of cancer incidence reduction. The program of the Chemoprevention Branch, NCI, is supporting 30 clinical trials of various chemopreventive agents for premalignant disease in different organ systems that are being monitored by the SEBs of DNA aneuploidy, abnormally high proliferative index, abnormal nuclear morphometry (aberrant size, shape, texture, and pleomorphism) and nucleolar number, position in the nucleus, and morphometry. Evidence from the literature permits the expectation that in premalignant breast disease these SEBs, when measured by computer-assisted quantitative image analysis, will accurately predict the risk of recurrence of breast DCIS after lumpectomy.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 Humoral cytotoxic immune responses of mice to inactivated Rauscher (a, b) and Gross virus (c, d) immunogens on the day of virus isolation. Serum titres shown are the means of three pools of sera per group; each pool made up of five to nine individual mouse sera, a And ct serum from C57BL/6 ...
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A virus shedding carrier culture of the Kirsten strain of MSV (Ki-MSV) in human adult fibroblast cells obtained from Dr V. Klement was maintained with Eagle's minimal essential medium (MEM) containing 10 per cent foetal calf serum (FCS) and antibiotics. A strain of FSV obtained from Dr M. Gardner5 ...
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1573-0603
    Keywords: Chemoprevention ; In vitro assays ; Drug screening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This issue reports the methods of twelve in vitro assays currently being used to screen potential chemopreventive agents for activity. These assays provide quantitative data to help determine the efficacy and prioritize agents for further development in whole animal screening. It is essential that such in vitro assays provide accurate, consistent, and relevant data to identify and prioritize agents with the most promise to prevent human cancer. The twelve assays presented in this volume are currently providing such data to the National Cancer Institute's Chemoprevention Program.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1573-0603
    Keywords: Albumin ; Bronchial cells ; Chemoprevention ; Ecto-cervical cells ; Growth inhibition ; Hepatocytes ; Human ; In vitro ; Keratinocytes ; Mammary epithelial cells ; Mitochondrial function ; Normal ; Oral mucosal cells ; PCNA ; Prostate epithelial cells ; Renal cells ; Toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Human Epithelial Cell Cytotoxicity (HECC) Assay for determining organ specific cytotoxicity uses human epithelial cells from eight different human tissues, including: skin, mammary, prostate, renal, bronchial, oral, ecto-cervix, and liver. Although the initial studies using this assay were conducted using cancer chemopreventive agents, the HECC Assay can also be used to evaluate other types of drugs, personal care products, environmental chemicals, and potential toxicants. Human epithelial cells at an early passage are seeded into multi-well dishes. The cells are exposed to multiple concentrations of a test agent for a three day period. The concentration ranges for test agents in the assay are determined in a preliminary assay using an exposure of five days and log dilutions from the highest soluble concentration. At the end of the exposure period, the cultures are evaluated for inhibition of growth. In the HECC Assay, cultures are exposed for three days. At the end of the exposure period, the cultures are evaluated for inhibition of growth, mitochondrial function, and PCNA expression or albumin synthesis (hepatocytes). Data are analyzed to determine the concentration that inhibited and point by 50 percent (TC50). Values for each agent in each target epithelial cell line or culture and the target tissue specific sensitivity are compared to determine the relative sensitivity of each epithelial cell line to the test agent.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 53 (1993), S. 234-241 
    ISSN: 0730-2312
    Keywords: Breast cancer risk ; chemoprevention ; intermediate biomarkers ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Early phase chemoprevention trials differ from standard therapeutic clinical trials because asymptomatic, healthy people are treated with a potentially toxic intervention for a prolonged period of time. Current subject selection protocols have relied upon epidemiological methods to identify highrisk individuals. Most available data provide risk estimates for various individual risk factors, but few have reported risk estimates for combinations of risk factors. Selection criteria for the large tamoxifen intervention trial (NSABP P1) were developed from the work of Gail et al. [1]. The Gail model takes into account non-genetic factors (e.g., nulliparity, age at menarche, preexisting pathological conditions) and genetic factors (family history). Using a lifetime risk of 10% of developing breast cancer as a standard to intervention trial. This approach has been criticized for being insufficiently selective (i.e., all women ≥60 yrs), but appears to be the best available method to select subjects for a chemoprevention trial. Other approaches have been based on identification of very high-risk women with acknowledged pathologic conditions [lobular carcinoma in situ, ductal carcinoma in situ (DCIS)]. Attempting to use these proliferative lesions as pathologic endpoints for drug effect has not been attempted. DCIS as a risk factor for tamoxifen intervention was excluded because of controversies over its management and because of frequent difficulties in distinguishing microinvasive from non-invasive lesions. Women treated for early stage breast cancer (Stage I) may be subjects for early stage chemopreventive interventions.We propose the use of intermediate endpoint biomarkers and genetic markers as entry criteria for early phase chemoprevention trials. For colorectal cancer chemoprevention, we have used a two-step selection process. The first step was based on epidemiologic risk assessment. Entry into the study required that a potential intermediate biomarker be positive and quantifiable. The relationship between modulation of a pre-transformational biomarker and development of cancer ultimately needs proof in a primary interventional trial; however, this methodology may permit screening of potential chemopreventive agents at lower cost and more rapid turn-around times. In early chemopreventive agent testing for breast cancer chemoprevention, we propose a similar two-step procedure. Epidemiological and/or pathological criteria for risk would be followed by a procedure to obtain cellular material. The cellular material would be assayed for pre-transformational cellular change.Identifying predictive genes in familial breast cancer cohorts such as the modified BRCA1 gene promises to select individuals at high familial and potentially physiological or environmental risk. The identification of the abnormal gene product in individuals and families will provide another important group of subjects for chemopreventive interventions. The identification of high-risk subjects for breast cancer chemoprevention, particularly those with familial genetic risk, carries important ethical problems. Such women may have difficulties obtaining health and life insurance, deciding to have children, and obtaining work. Chemoprevention trials with genetic selection criteria will need to develop methods of dealing with these issues.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 0730-2312
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A major determinant of progress in human breast cancer prevention is the identification of agents with significant anticarcinogenic activity and acceptable levels of toxicity in experimental animals. Over the past 20 years, more than 50 experimental regimens have been shown to have significant chemopreventive activity in the rat mammary gland. The most effective approaches to mammary cancer chemoprevention in rats involve surgical endocrine ablations such as bilateral ovariectomy. However, prophylactic surgical ablations are unlikely to be acceptable to the majority of the general public. All chemicals evaluated to date are less effective, and none has been shown to reduce mammary cancer incidence to zero. As a result, efforts continue to identify chemical agents whose protective activity is comparable to that of endocrine ablation. DHEA is an adrenal steroid with chemopreventive activity in several animal models for human cancer. In the present studies, the chemopreventive efficacy of DHEA was evaluated in rats exposed to the mammary gland carcinogen, N-methyl-N-nitrosourea (MNU). Groups of 20 female Sprague-Dawley rats were fed an AIN-76A diet supplemented with 0, 400, or 800 mg DHEA per kg diet; one week later, all rats received a single i.p. injection of 35 mg MNU per kg body weight. Animals were palpated weekly to monitor mammary tumor development, and all mammary tumors were histologically confirmed. When administered at 800 mg/kg diet, DHEA reduced mammary cancer incidence in controls from 95% to 15%; carcinoma multiplicity in rats receiving 800 mg DHEA per kg diet was reduced by more than 85% from control levels. In a separate study, the 400 mg/kg diet dose of DHEA reduced the incidence of mammary cancer to 5% from 80% found in controls fed the basal diet. Reductions in mammary cancer incidence and multiplicity associated with DHEA administration were accompanied by large increases in cancer latency. Evaluation of mammary gland wholemounts from animals fed DHEA demonstrated a massive induction of lobuloalveolar differentiation. These results indicate the dietary supplementation with non-toxic dose levels of DHEA has chemopreventive efficacy approaching that of endocrine ablation. This protection may be mediated by the induction of differentiation in the mammary gland, during which sensitive mammary parenchymal structures (terminal end buds) are stimulated to develop into structures (alveolar buds) less sensitive to carcinogenic insult.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...