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1.
《American anthropologist》1976,78(3):746-746
The Editorial Board of the American Anthropologist has prepared and the Executive Board approved the following guidelines for Articles and Discussion and Debate .  相似文献   

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Cell growth and differentiation in developing tissues are, at first impression, quite different endeavors from readjusting synaptic strength during activity-dependent synaptic plasticity in mature neurons. Nevertheless, it is becoming increasingly clear that these two distinct processes share multiple intracellular signaling events. How these common pathways result in cell division (during proliferation), large-scale cellular remodeling (during differentiation) or synapse-specific changes (during synaptic plasticity) is only starting to be elucidated. Here we review the latest findings on two prototypical examples of these shared mechanisms: the Ras-PI3K pathway and the intracellular signaling elicited by neural cell adhesion molecules interacting with growth factor receptors.  相似文献   

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Biobanks include biological samples and attached databases. Human biobanks occur in research, technological development and medical activities. Population genomics is highly dependent on the availability of large biobanks. Ethical issues must be considered: protecting the rights of those people whose samples or data are in biobanks (information, autonomy, confidentiality, protection of private life), assuring the non-commercial use of human body elements and the optimal use of samples and data. They balance other issues, such as protecting the rights of researchers and companies, allowing long-term use of biobanks while detailed information on future uses is not available. At the level of populations, the traditional form of informed consent is challenged. Other dimensions relate to the rights of a group as such, in addition to individual rights. Conditions of return of results and/or benefit to a population need to be defined. With 'large-scale biobanking' a marked trend in genomics, new societal dimensions appear, regarding communication, debate, regulation, societal control and valorization of such large biobanks. Exploring how genomics can help health sector biobanks to become more rationally constituted and exploited is an interesting perspective. For example, evaluating how genomic approaches can help in optimizing haematopoietic stem cell donor registries using new markers and high-throughput techniques to increase immunogenetic variability in such registries is a challenge currently being addressed. Ethical issues in such contexts are important, as not only individual decisions or projects are concerned, but also national policies in the international arena and organization of democratic debate about science, medicine and society.  相似文献   

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The dissociation constants (pKa) for the pteridine ring system of dihydrofolate (H2folate) have been redetermined, and those for dihydrobiopterin (H2biopterin) have been determined. Determination of the pKa for N5 of H2folate is complicated by the low solubility and instability of H2folate at pH 2-4, and other complicating factors. The initial rate of absorbance change due to degradation is a maximum at pH 2.5, and the products depend on the oxygen concentration: under aerobic conditions, (p-aminobenzoyl)glutamic acid and 7,8-dihydropterin-6-carboxaldehyde are major products. H2Biopterin is much more soluble and more stable at low pH. For protonation of N5, the pKa is 2.56 +/- 0.01 for H2biopterin and 2.59 +/- 0.03 for H2folic acid. Spectrophotometric determination of the pKa for the N3-O4 amide group of H2folate is subject to serious errors when a wavelength between 220 and 235 nm is used. These errors arise from the pH-dependent absorbance of mercaptoethanol often present in the preparation. The amide group has a pKa of 10.41 +/- 0.04 in H2biopterin and 10.85 +/- 0.04 in H2folate. The redetermined value for the pKa of N5 of H2folate has implications for mechanistic models for dihydrofolate reductase, and revised kinetic constants have been calculated for one model.  相似文献   

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Modern transplantation of cells, tissues and organs has been practiced within the last century achieving both life saving and enhancing results. Associated risks have been recognized including infectious disease transmission, malignancy, immune mediated disease and graft failure. This has resulted in establishment of government regulation, professional standard setting and establishment of vigilance and surveillance systems for early detection and prevention and to improve patient safety. The increased transportation of grafts across national boundaries has made traceability difficult and sometimes impossible. Experience during the first Gulf War with miss-identification of blood units coming from multiple countries without standardized coding and labeling has led international organizations to develop standardized nomenclature and coding for blood. Following this example, cell therapy and tissue transplant practitioners have also moved to standardization of coding systems. Establishment of an international coding system has progressed rapidly and implementation for blood has demonstrated multiple advantages. WHO has held two global consultations on human cells and tissues for transplantation, which recognized the global circulation of cells and tissues and growing commercialization and the need for means of coding to identify tissues and cells used in transplantation, are essential for full traceability. There is currently a wide diversity in the identification and coding of tissue and cell products. For tissues, with a few exceptions, product terminology has not been standardized even at the national level. Progress has been made in blood and cell therapies with a slow and steady trend towards implementation of the international code ISBT 128. Across all fields, there are now 3,700 licensed facilities in 66 countries. Efforts are necessary to encourage the introduction of a standardized international coding system for donation identification numbers, such as ISBT 128, for all donated biologic products.  相似文献   

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Deoxyribonucleic acid (DNA) extracted from phage SPP1 is highly infectious on Bacillus subtilis competent cells; the efficiency of infection is 5 x 10(3) to 6 x 10(3) phage equivalents per plaque-forming unit. This DNA was used to study the relationship between competence for transfection and for transformation. The experiments were concerned with the frequency of infection and transformation in mutants exhibiting different levels of competence, the effect of periodate on competence for infection and for transformation, the competition between phage and bacterial DNA, the transformation of cells preinfected with phage DNA, and the infection of cells pretreated with bacterial DNA. The data show that B. subtilis cells competent for transformation are also competent for transfection and vice versa; transfection with phage DNA represents, therefore, a simple way to measure the total number of competent cells in a culture. The fraction of competent cells, determined by SPP1 DNA infection, varied from 10(-2) to 7 x 10(-2).  相似文献   

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