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Experiments are reviewed that indicate embryonic fields arecapable of regulating the neoplastic attributes of their closelyrelated carcinomas. In the case of blastocyst regulation ofembryonal carcinoma cells the reaction is mediated by contactof the cancer cells with trophectodermal cells in the presenceof blastocele fluid. In the case of regulation of melanoma,the reaction is mediated in the embryonic skin at the time normalmelanocytes migrate into it. A diffusible factor that inhibitscell division and seems to affect differentiation is involved.In the case of neuroblastoma, a degree of regulation is demonstrablein the neural crest migratory pathway, but the maximal effectis found in the adrenal, renal, and testicular primordia. Afactor inhibitory of mitosis for adenocarcinoma of the breastcan be demonstrated in the breast primordium. It is concludedthat there must be an embryonic field capable of regulatingevery kind of carcinoma: understanding of the phenomena maylead to a noncytotoxic cure for carcinoma, and through the useof cancer cells as probes of embryonic development to an understandingof embryonic induction.  相似文献   

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The plurality of definitions of life is often perceived as an unsatisfying situation stemming from still incomplete knowledge about ‘what it is to live’ as well as from the existence of a variety of methods for reaching a definition. For many, such plurality is to be remedied and the search for a unique and fully satisfactory definition of life pursued. In this contribution on the contrary, it is argued that the existence of such a variety of definitions of life undermines the very feasibility of ever reaching a unique unambiguous definition. It is argued that focusing on the definitions of specific types of ‘living systems’—somehow in the same way that one can define specific types of ‘flying systems’—could be more fruitful from a heuristic point of view than looking for ‘the’ right definition of life, and probably more accurate in terms of carving Nature at its joints.  相似文献   

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Genome-wide association studies in canine models may help locate genomic susceptibility regions that are relevant to human disease. See related Research: http://genomebiology.com/2014/15/3/R25  相似文献   

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Mathematical Talent is Linked to Autism   总被引:1,自引:0,他引:1  
A total of 378 mathematics undergraduates (selected for being strong at “systemizing”) and 414 students in other (control) disciplines at Cambridge University were surveyed with two questions: (1) Do you have a diagnosed autism spectrum condition? (2) How many relatives in your immediate family have a diagnosed autism spectrum condition? Results showed seven cases of autism in the math group (or 1.85%) vs one case of autism in the control group (or 0.24%), a ninefold difference that is significant. Controlling for sex and general population sampling, this represents a three- to sevenfold increase for autism spectrum conditions among the mathematicians. There were 7 of 1,405 (or 0.5%) cases of autism in the immediate families of the math group vs 2 of 1,669 (or 0.1%) cases in the immediate families of the control group, which again is a significant difference. These results confirm a link between autism and systemizing, and they suggest this link is genetic given the association between autism and first-degree relatives of mathematicians.  相似文献   

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Withdrawing life support is always difficult. When patients and health professionals are from different ethnic backgrounds, value systems that form the basis for such decisions may conflict. Many cultural groups do not place the same emphasis on patient autonomy and self-determination that Western society does and find the idea of terminating life support offensive. Although physicians should never assume patients will respond in a particular way because of their ethnic background, issues of life support should be discussed in a culturally sensitive way. African-American, Chinese, Jewish, Iranian, Filipino, Mexican-American, and Korean patients were surveyed about their views on life support. The findings reported here, although not meant to be definitive, should add to health professionals'' understanding about diverse beliefs around life-and-death issues. By becoming aware of this diversity of beliefs, health professionals can avoid the damage to the physician-patient relationship caused by conflicting value systems.  相似文献   

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Three structurally related protein complexes, the COP9 signalosome, the proteasome lid, and the eukaryotic translation initiation factor 3, are revealing new insights into developmental processes and into cell cycle control in healthy cells and cells exposed to genotoxic stress. Newly discovered cullin-RING E3 ubiquitin ligases assembled on the CUL4 platform may provide links between DNA replication, chromatin, and proteolysis.  相似文献   

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Plasma aluminum is bound to transferrin   总被引:5,自引:0,他引:5  
G A Trapp 《Life sciences》1983,33(4):311-316
Aluminum ion is bound to at least one of the two specific iron binding sites of serum transferrin and also to serum albumin, as shown by in vivo competition studies with 67-Ga, gel filtration chromatography and ultraviolet difference spectroscopy. Binding of aluminum to transferrin requires CO2 and therefore involves a specific iron site. Samples of commercial transferrin contained large amounts of aluminum. Aluminum may cause anemia by entering pathways of iron distribution and metabolism.  相似文献   

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Urea transporters (UTs) in the ureotelic vertebrates have been well-characterized, but little is known about those of the ammonotelic teleost fishes. To clarify the physiological roles of UTs in the ammonotelic teleosts, we determined the structure, tissue and cellular localizations, and regulation of expression of eel UT (eUT) by cDNA cloning, Northern analysis, and immunohistochemistry. A full-length cDNA (approximately 1.9 kb) coding for a UT of 486 amino acid residues was isolated from a seawater eel gill cDNA library. Sequence comparison with those of other species indicated that the eUT is a short isoform with 10 transmembrane spans and has longer NH2- and COOH-terminal cytoplasmic tails compared with the mammalian counterparts. Northern blot analysis demonstrated high expression of eUT mRNA confined in the gill and a substantial increase of its levels when eels were transferred from freshwater to seawater. Immunohistochemistry showed that eUT is localized on the basolateral membranes of the chloride cells, establishing, at the cellular level, the site of urea excretion in the eel, an ammonotelic teleost.  相似文献   

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Abstract — The T-PTP test for monophyly can attribute significance to entirely unsupported groups and even to both of two contradictory alternatives. The method of evaluating “support” after replacing selected groups of terminals with reconstructed ancestors has similar drawbacks. The proposed placement of Onychophora among Arthropoda is unsupported by 12S data, and strongly refuted by other evidence. Attempts to justify T-PTP on Popperian grounds rest entirely on misunderstanding Popper's ideas. The PTP test assesses neither Popperian corroboration nor statistical confidence of phylogenetic conclusions. It can attribute high significance to data that support no resolved grouping. Efforts to salvage PTP by proposing new interpretations share the weakness that none of the proposed interpretations generally holds. None of these methods seems useful in phylogenetic  相似文献   

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What is (and is not) vital to advancing cellulosic ethanol   总被引:1,自引:0,他引:1  
Ethanol made biologically from cellulosic biomass, including agricultural and forestry residues, portions of municipal waste, and herbaceous and woody crops, is finally being widely recognized as a unique transportation fuel with powerful economic, environmental and strategic attributes. Although underfunded, it has been advanced to be competitive with corn ethanol; however, government policies are needed to overcome the perceived risk of first applications if we are to realize its societal benefits soon. Costs below those for fossil sources are foreseeable, with advances in pretreatment, enzyme production, and enzymatic hydrolysis - the steps that overcome the natural resistance of plants to biological breakdown - offering, by far, the greatest economic leverage. We must also build on the wisdom gained from past experience to avoid directing limited funds to projects that offer little new insight, could have marginal impact on commercial outcomes, or could be better improved through the power and wisdom of the learning curve.  相似文献   

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