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991.
Breast cancer is one of the most common cancers in humans and will on average affect up to one in eight women in their lifetime in the United States and Europe. The Women's Health Initiative and the Million Women Study have shown that hormone replacement therapy is associated with an increased risk of incident and fatal breast cancer. In particular, synthetic progesterone derivatives (progestins) such as medroxyprogesterone acetate (MPA), used in millions of women for hormone replacement therapy and contraceptives, markedly increase the risk of developing breast cancer. Here we show that the in vivo administration of MPA triggers massive induction of the key osteoclast differentiation factor RANKL (receptor activator of NF-κB ligand) in mammary-gland epithelial cells. Genetic inactivation of the RANKL receptor RANK in mammary-gland epithelial cells prevents MPA-induced epithelial proliferation, impairs expansion of the CD49f(hi) stem-cell-enriched population, and sensitizes these cells to DNA-damage-induced cell death. Deletion of RANK from the mammary epithelium results in a markedly decreased incidence and delayed onset of MPA-driven mammary cancer. These data show that the RANKL/RANK system controls the incidence and onset of progestin-driven breast cancer.  相似文献   
992.
The earliest record of human activity in northern Europe   总被引:1,自引:0,他引:1  
The colonization of Eurasia by early humans is a key event after their spread out of Africa, but the nature, timing and ecological context of the earliest human occupation of northwest Europe is uncertain and has been the subject of intense debate. The southern Caucasus was occupied about 1.8 million years (Myr) ago, whereas human remains from Atapuerca-TD6, Spain (more than 780 kyr ago) and Ceprano, Italy (about 800 kyr ago) show that early Homo had dispersed to the Mediterranean hinterland before the Brunhes-Matuyama magnetic polarity reversal (780 kyr ago). Until now, the earliest uncontested artefacts from northern Europe were much younger, suggesting that humans were unable to colonize northern latitudes until about 500 kyr ago. Here we report flint artefacts from the Cromer Forest-bed Formation at Pakefield (52 degrees N), Suffolk, UK, from an interglacial sequence yielding a diverse range of plant and animal fossils. Event and lithostratigraphy, palaeomagnetism, amino acid geochronology and biostratigraphy indicate that the artefacts date to the early part of the Brunhes Chron (about 700 kyr ago) and thus represent the earliest unequivocal evidence for human presence north of the Alps.  相似文献   
993.
Rioux JD  Abbas AK 《Nature》2005,435(7042):584-589
Some people inherit an unfortunate combination of genetic sequences, such that exposure to an external trigger causes their immune response to turn on their own tissues. Although mutations in a single gene can cause autoimmunity, most autoimmune diseases are associated with several sequence variants. Marked advances in genetic resources and tools are now making it possible to identify the sequence variants that contribute to autoimmune diseases--promising a better understanding of how we normally remain tolerant of our own tissue components, and how this goes wrong in autoimmune disease.  相似文献   
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Scanlan CN  Offer J  Zitzmann N  Dwek RA 《Nature》2007,446(7139):1038-1045
The sustained effort towards developing an antibody vaccine against HIV/AIDS has provided much of our understanding of viral immunology. It is generally accepted that one of the main barriers to antibody neutralization of HIV is the array of protective structural carbohydrates that covers the antigens on the virus's surface. Intriguingly, however, recent findings suggest that these carbohydrates, which have evolved to protect HIV and promote its transmission, are also attractive therapeutic targets.  相似文献   
996.
Wool top and knitted fabric were treated with ammonia in the presence of sodium chloride (salt-ammonia process). The effectiveness of salt-ammonia process traditionally used as pretreatment for low temperature dyeing has been investigated for conferring shrink-resistance of wool. The pretreatmont of salt-ammonia process followed by enzymatic treatment has been proved that contribute to not only the enhancement of dyeing behavionr but also shrinkage-resistance in the present studies. A novel composition of salt-ammonia pretreatment, oxidized and reduced treatment as well as protease modification was recommended to achieve low temperature dyeing and shrinkage-resistance of wool. At the same time, the process conditions were optimized by orthogonal array and assessed by dye uptake rate, weight loss and area shrinkage. Laboratory experiments showed that the knitted fabric treated according to optimized conditions of the combined process, achieved not only improvement of dye abilities but also the strict requirement of machine-washable, representing a possible alternative to chlorination.  相似文献   
997.
Vibrio cholerae is a globally important pathogen that is endemic in many areas of the world and causes 3-5 million reported cases of cholera every year. Historically, there have been seven acknowledged cholera pandemics; recent outbreaks in Zimbabwe and Haiti are included in the seventh and ongoing pandemic. Only isolates in serogroup O1 (consisting of two biotypes known as 'classical' and 'El Tor') and the derivative O139 can cause epidemic cholera. It is believed that the first six cholera pandemics were caused by the classical biotype, but El Tor has subsequently spread globally and replaced the classical biotype in the current pandemic. Detailed molecular epidemiological mapping of cholera has been compromised by a reliance on sub-genomic regions such as mobile elements to infer relationships, making El Tor isolates associated with the seventh pandemic seem superficially diverse. To understand the underlying phylogeny of the lineage responsible for the current pandemic, we identified high-resolution markers (single nucleotide polymorphisms; SNPs) in 154 whole-genome sequences of globally and temporally representative V. cholerae isolates. Using this phylogeny, we show here that the seventh pandemic has spread from the Bay of Bengal in at least three independent but overlapping waves with a common ancestor in the 1950s, and identify several transcontinental transmission events. Additionally, we show how the acquisition of the SXT family of antibiotic resistance elements has shaped pandemic spread, and show that this family was first acquired at least ten years before its discovery in V. cholerae.  相似文献   
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