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  • 1
    ISSN: 1432-1335
    Keywords: Onapristone ; Progesterone antagonist ; T61 mammary carcinoma ; Progesterone receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The progesterone antagonist Onapristone proved to possess strong tumour-inhibiting activity in a panel of experimental mammary carcinomas. Its underlying mechanism of action is due to a progesterone-receptor-mediated induction of terminal differentiation and a specific blockade of the cell cycle and is also present in the absence of progesterone as was shown in the MXT mammary tumour. To prove this further, the tumour-inhibiting activity of Onapristone was investigated in the human postmenopausal T61 mammary tumour implanted in castrated male nude mice. Whereas Onapristone given alone had no effect on growth of established tumours, after stimulation of the relatively low progesterone receptor content of this tumour line with an oestrogen, Onapristone significantly inhibited tumour growth. Thus, we suggest that Onapristone exerts its antitumour action via progesterone receptors. As there is no endogenous progesterone in these mice, the tumour-inhibiting activity of Onapristone is not primarily due to a classical antihormonal effect.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-7330
    Keywords: spermatozoa ; zona pellucida ; zona binding ; structure of zona ; human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose A total of 86 fresh and salt-stored immature human oocytes derived from postmortem ovarian tissue were used for this study. Methods Oocytes were randomly incubated either in synthetic human tubal fluid medium (untreated zonae) or in a chemically defined medium (treated zonae). Results Sperm binding experiments using hemizona assay conditions exhibited a 10-fold increased binding of sperm to treated compared to untreated oocytes (272.7±43 versus 24.3±15 sperm bound, respectively; P〈0.0001). pH recordings during incubation showed elevated pH levels of 8.1 compared to pH 7.2 among treated and untreated zonae, respectively. Ultrastructural examination showed a spongy appearance of the surface of treated zonae, whereas untreated zonae appeared compact with smooth surface. Conclusions The marked increase in sperm binding among treated zonae, together with the ultrastructural findings, suggest that the altered zona surface enhances sperm binding. The physiological maturational process of the zona pellucida might be manipulated in vitro, thus increasing sperm binding to the zona.
    Type of Medium: Electronic Resource
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