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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 36 (1993), S. 159-163 
    ISSN: 1040-452X
    Keywords: Follicular proliferation ; Ovary ; Growth factor ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The factors involved in the inhibition of ovarian follicular cellular growth after the luteinizing hormone (LH) surge are poorly established. The aim of this study was to investigate the production of an inhibitory growth factor by human ovarian cells. Luteinized granulosa cells were obtained from an assisted fertilization program and were cultured in the presence or absence of follicle-stimulating hormone (FSH) and estradiol. Data obtained by cell counting showed that the number of human luteinized granulosa cells cultured in the presence of fetal bovine serum (10%) increased 1.8-fold within a 2-day period. In serum-free medium, human luteinized granulosa cells were able to incorporate 3H-thymidine, measured during consecutive 48 h periods. During all the periods tested (up to 7 days), low basal levels of thymidine incorporation were measured and were further reduced in the presence of FSH (200 ng/ml) and estradiol (500 ng/ml). To elucidate the possible production of an inhibitory growth factor, 3H-thymidine incorporation by rat granulosa cell cultures was measured in the presence of conditioned media (CM; from human granulosa cell cultures). In this system, FSH and estradiol elicited a tenfold increase in thymidine incorporation. The addition of CM (10% v/v collected on day 2) to FSH- and estradiol-treated granulosa cell cultures produced an inhibition (61%) of thymidine incorporation. The active factor in CM withstood freeze-thawing, was stable for several weeks at - 20°C, became unstable at 4°C, and was heat labile and sensitive to proteolysis. Ultrafiltration using membranes with different molecular weight cutoffs suggested that the factor had a molecular weight 〉30,000 dalton. We suggest that an inhibitory growth factor produced by human luteinized granulosa cells could be involved in the differentiation of growing follicles to corpus luteum. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 143 (1990), S. 21-25 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The time-dependent release of superoxide anion (O2-) from bradykinin (Bk)-stimulated human umbilical vein endothelial cells (EC) was measured as the superoxide dismutase-inhibitable reduction of ferricytochrome C employing a novel application of microspectrophotometry. In the absence of Bk, O2- release by EC was not detectable. EC exposure to Bk (10-6 to 10-5 M) resulted in a rapid release of O2-. The release of O2- occurred within 5 minutes of exposure. O2- release was partially inhibited by indomethacin (63 ± 6%), thus suggesting that arachidonic acid metabolism, through cyclooxygenase, contributes to EC O2- production. EC O2- release may be an important component in the pathophysiologic actions of Bk on vascular function.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    BioEssays 19 (1997), S. 277-279 
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Higher plants must undergo a major developmental switch, the transition to flowering, if they are to successfully complete their life cycle. In many plants, the crucial decision of when to begin to produce flowers is primarily controlled by environmental signals. The process of floral induction involves the integration of the activities of two types of genes: those that control flowering time as a response to the environment as well as an endogenous clock, and those that determine the floral identity of the cells. The first direct link between these two classes of genes has now been demonstrated(1). Forced expression of CONSTANS, a flowering-time gene, promotes flowering through the transcriptional activation of LEAFY, a flower-meristem-identity gene.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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