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The Notch signaling pathway has been implicated in homeostasis and disease, including cancer, in various tissues. Moreover, it has been involved both in stem cell maintenance and differentiation, in a context-dependent manner. Stem/progenitor cells, on the other hand, have long been suspected to be the cells of origin in various malignancies. In order to gain insight in the role of the Notch ligand Dll1 in mouse development, we generated a knock-in line expressing an inducible Cre recombinase. We have employed in vivo approaches in mice to genetically mark rare subpopulations of cells expressing Dll1 in various adult tissues. Moreover, we conditionally expressed a constitutively active Ras oncoprotein in these cells and showed that within days, mice develop squamous neoplasias in the skin, as well as in the stomach.  相似文献   
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One reason for observing in practice a false positive or negative correlation between two random variables, which are either not correlated or correlated with a different direction, is the overrepresentation in the sample of individuals satisfying specific properties. In 1946, Berkson first illustrated the presence of a false correlation due to this last reason, which is known as Berkson's paradox and is one of the most famous paradox in probability and statistics. In this paper, the concept of weighted distributions is utilized to describe Berskon's paradox. Moreover, a proper procedure is suggested to make inference for the population given a biased sample which possesses all the characteristics of Berkson's paradox. A real data application for patients with dementia due to Alzheimer's disease demonstrates that the proposed method reveals characteristics of the population that are masked by the sampling procedure.  相似文献   
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Analyses of the mtDNA control region sequence variation of the brown trout Salmo trutta through its distribution range have demonstrated five distinct phylogenetic lineages. In this work we report the design and implementation of a rapid and accurate molecular diagnostic procedure which allows the assignment of all major phylogenetic lineages. Our method relies on multiplex PCR that discriminates diagnostic single nucleotide polymorphisms (SNPs) characteristic of each lineage. The method is straightforward and easy to set up, involves a single reaction, yields data easy to interpret and does not pose significant risk for false positive/negative lineage assignment of a given individual. Panagotis K. Apostolou and Andreas Georgiadis contributed equally to this work.  相似文献   
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The case of a premature infant with bacteriologically proved klebsiella pneumonia in the first week of life is reported. The clinical course was complicated by the early formation of pneumatoceles and subsequent recurrent pneumothoraces. Treatment consisted of antibiotic therapy and chest tube drainage. Satisfactory clinical recovery, growth and psychomotor development were noted at 1 year of age, despite the persistence of a pneumatocele in the right lung.  相似文献   
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Human Ecology - Our research addresses knowledge integration for the good governance of the environment and the oceans: (a) through a comprehensive legal, political science, and anthropological...  相似文献   
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