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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Planta 152 (1981), S. 1-7 
    ISSN: 1432-2048
    Keywords: Auxin ; Cytokinin ; DNA ; Nicotiana RNA ; Protoplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tobacco mesophyll protoplasts cultivated in vitro do not synthesize a measurable quantity of chloroplastic ribosomal RNA, but actively synthesize cytoplasmic ribosomal RNA, polyadenylated RNA, and proteins. These syntheses are essentially independent of the presence of hormones in the culture medium and are thus related to the ageing phenomenon induced by isolation from the plant and in-vitro culture. At all stages of culture and in all culture media, protoplasts incorporate low levels of thymidine into their DNA. However, the incorporation of considerable quantities of thymidine, indicative of the S phase, only takes place after 25–30 h and requires the presence of auxin and cytokinin.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 276 (1984), S. 52-56 
    ISSN: 1432-069X
    Keywords: Fluorometry ; DNA ; 4′-6-Diamidino-2-phenylindole ; Fibroblasts ; Epidermis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 4′-6-diamidino-phenylindole (DAPI) which is used for the detection of mycoplasmic infections of cell cultures or cytofluorometric investigations proved to be a sensitive agent for the fluorometric assay of alkali extracted DNA in cultured cells and human epidermis. Various experiments to optimize assay conditions led to the following procedure: 1 part of freeze dried tissue (1 mg/ml) and 1 part of 0.2 mol/l NaOH (w/v) were heated at 95° for 40 min. After cooling for 1 h to room temperature, 0.1 ml alkaline extract was mixed with 2.9 ml DAPI-solution (0.2 μg/ml in McIlvaine buffer containing 1 mmol/l MgCl2). After 10 min in the dark the emitted fluorescence was estimated at 453 nm with an excitation at 360 nm. This assay procedure allowed a detection limit of 25 ng DNA.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 4 (1984), S. 79-88 
    ISSN: 1573-7217
    Keywords: breast ; carcinoma ; DNA ; kinetics ; ploidy ; receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The S-phase fraction (SPF) measured by flow cytometry of DNA and the thymidine labeling index (TLI) measured autoradiographically indicate the proportion of carcinoma cells currently synthesizing DNA and reflect the rate of proliferation. The TLI and SPF are lognormally distributed. The median TLI performed to maximize precursor uptake is near 5% (5 labeled carcinoma cells per 100), the mean near 7%, and the range from less than 1% to near 40%. Corresponding values for the SPF measured by DNA flow cytometry are slightly higher when appropriate measures are taken to reduce background debris counts and other artefacts. Residual elevation of SPF above TLI may result from S-phase arrested cells. Flow cytometric histograms show that clearly aneuploid cell lines exist in 50–80% of primary breast carcinomas. Aneuploid breast carcinomas have higher mean TLI than diploid breast carcinomas, and therefore proliferate more rapidly. They also more frequently lack estrogen receptor (ER). Carcinomas with minimal nuclear anaplasia, particularly those of tubular, mucinous, infiltrating lobular and adenocystic types have low TLI and SPF, whereas carcinomas with highly anaplastic nuclei, including medullary carcinomas, have high TLI and SPF. TLI and SPF correlate inversely with ER and PgR content, have no relationship to axillary lymph nodal status, and have a weak positive correlation with tumor size and a weak negative correlation with age. High TLI predicts a high risk of early relapse after primary therapy for both node-negative and node-positive carcinomas. Carcinomas that produce brain metastases have particularly high TLI. Current evidence suggests that high SPF and aneuploidy may prove to have prognostic significance like TLI.
    Type of Medium: Electronic Resource
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