1,720,998 research outputs found
REGULATORY MECHANISMS IMPLICATED IN THE CONTROL OF NUMB ASYMMETRIC PARTITIONING AT MITOSIS OF ADULT MAMMARY STEM CELLS
Full text linkThe cell fate determinant Numb has been recently shown to control the asymmetric outcome of self-renewing divisions in the normal mammary stem cell (MaSC) compartment. Loss of Numb results in the appearance of stem cells (SCs) endowed with an enhanced symmetric self-renewal ability (leading to expansion of the SC compartment) and with tumorigenic potential. The role of Numb in MaSCs is linked to its ability to asymmetrically partition at mitosis into the progeny that retains the SC identity, where it sustains the tumour suppressor activity of p53. Phosphorylation of Numb by the Par Complex (Par3/Par6/atypical PKC) is an evolutionary conserved mechanism to specify Numb asymmetric partitioning at SC mitosis. In this thesis work, we used a molecular genetics approach to demonstrate that a proper cycle of Numb phosphorylation and de-phosphorylation is essential to guarantee the asymmetric partitioning of Numb at mitosis of MaSCs. We also propose a conserved role for the atypical PKC isoenzyme and Par3 in the regulation of these events. Moreover, our preliminary data show that Numb phosphorylation mediated by aPKC impairs Numb interaction with p53, suggesting that the regulation of Numb phosphorylation can be also linked to its tumour suppressor function
Immunodepression induced from Steinernema feltiae (Nematoda, Rhabditida) in Galleria mellonella; interaction between parasite cuticle and host proPO system”
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The epidemiology of multiple pregnancies
No full textOver the last decades the frequency of multiple births has been on the decline in most developed countries. This trend, however, has been restricted to dizygotic twins, while monozygotic rates have remained stable or risen slowly. In more recent years, however, the fall in multiple dizygotic birth rates has ceased and a slight increase is observed. This trend and the increased frequency of triplets or higher-order births, registered from the early 1980s onwards, are essentially related to treatments for infertility. No single risk factor, such as maternal age, parity, oral contraceptive use, or declining fertility rates can explain the overall declining trends. In this paper we review the descriptive epidemiology and the main risk factors for multiple pregnancies
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