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排序方式: 共有408条查询结果,搜索用时 390 毫秒
1.
Joshua R Edwards Evangelos A Diamantakos Jacob D Peuler Peter C Lamar Walter C Prozialeck 《BMC physiology》2007,7(1):1
Background
Ethidium homodimer is a cell-membrane impermeant nuclear fluorochrome that has been widely used to identify necrotic cells in culture. Here, we describe a novel technique for evaluating necrosis of epithelial cells in the proximal tubule that involves perfusing ethidium homodimer through the intact rat kidney. As a positive control for inducing necrosis, rats were treated with 3.5, 1.75, 0.87 and 0.43 mg/kg mercuric chloride (Hg2+, intraperitoneal), treatments which have previously been shown to rapidly cause dose-dependent necrosis of the proximal tubule. Twenty-four h after the administration of Hg2+, ethidium homodimer (5 μM) was perfused through the intact left kidney while the animal was anesthetized. The kidney was then removed, placed in embedding medium, frozen and cryosectioned at a thickness of 5 μm. Sections were permeabilized with -20°C methanol and then stained with 4',6-diamidino-2-phenylindole (DAPI) to label total nuclei. Total cell number was determined from the DAPI staining in random microscopic fields and the number of necrotic cells in the same field was determined by ethidium homodimer labeling. 相似文献2.
The groundbreaking technologies of induced pluripotency and lineage conversion have generated a genuine opportunity to address fundamental aspects of the diseases that affect the nervous system. These approaches have granted us unrestricted access to the brain and spinal cord of patients and have allowed for the study of disease in the context of human cells, expressing physiological levels of proteins and under each patient's unique genetic constellation. Along with this unprecedented opportunity have come significant challenges, particularly in relation to patient variability, experimental design and data interpretation. Nevertheless, significant progress has been achieved over the past few years both in our ability to create the various neural subtypes that comprise the nervous system and in our efforts to develop cellular models of disease that recapitulate clinical findings identified in patients. In this Review, we present tables listing the various human neural cell types that can be generated and the neurological disease modeling studies that have been reported, describe the current state of the field, highlight important breakthroughs and discuss the next steps and future challenges. 相似文献
3.
A sperm penetrates an egg by extending a long, actin-filled tube known as the acrosomal process. This simple example of biomotility is one of the most dramatic. In Thyone, a 90 m process can extend in less than 10 s. Experiments have shown that actin monomers stored in the base of the sperm are transported to the growing tip of the acrosomal process where they add to the ends of the existing filaments.The force that drives the elongation of the acrosomal process has not yet been identified although the most frequently discussed candidate is the actin polymerization reaction. Developing what we believe are realistic moving boundary models of diffusion limited actin fiber polymerization, we show that actin filament growth occurs too slowly to drive acrosomal elongation. We thus believe that other forces, such as osmotically driven water flow, must play an important role in causing the elongation. We conjecture that actin polymerization merely follows to give the appropriate shape to the growing structure and to stabilize the structure once water flow ceases.Work partially supported by the United States Department of Energy 相似文献
4.
Cross-activation of the Rex proteins of HTLV-I and BLV and of the Rev protein of HIV-1 and nonreciprocal interactions with their RNA responsive elements 总被引:22,自引:0,他引:22
The Rex regulatory proteins of human T-cell leukemia virus type I (HTLV-I) and bovine leukemia virus (BLV), and the Rev protein of human immunodeficiency virus type 1 (HIV-1), promote the cytoplasmic accumulation and translation of viral messenger mRNAs encoding structural proteins. Rev and Rex act through cis-acting elements on the viral RNA; these elements are named Rev- and Rex-responsive elements, or RRE and RXRE, respectively. We show that the Rex proteins of HTLV-I and BLV are interchangeable, but only the Rex protein of HTLV-I can substitute for Rev of HIV-1. Rex of HTLV-I and Rev of HIV-1 appear to act on RRE by similar mechanisms. Rev of HIV-1 does not act on the RXRE of HTLV-I or BLV. The nonreciprocal action of Rev and Rex suggests that these factors interact directly with the cis-acting RNA elements of the two viruses. 相似文献
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Ernst Weber Evangelos Papamokos Wolfram Bode Robert Huber Ikunoshin Kato Michael Laskowski 《Journal of molecular biology》1981,149(1):109-123
The third domain of Japanese quail ovomucoid, a Kazal type inhibitor, has been crystallized and its crystal structure determined at 2.5 Å resolution using multiple isomorphous replacement techniques. The asymmetric unit contains four molecules. In the crystal the molecules are arranged in two slightly different octamers with approximate D4 symmetry. The molecules are held together mainly by interactions of the N-terminal residues, which form a novel secondary structural element, a β-channel.The molecule is globular with approximate dimensions 35 Å × 27 Å × 19 Å. The secondary structural elements are a double-stranded anti-parallel β-sheet of residues Pro22 to Gly32 and an α-helix from Asn33 to Ser44. The reactive site Lys18-Asp19 is located in an exposed loop. It is close to Asn33 at the N terminus of the helical segment. The polypeptide chain folding of ovomucoid bears some resemblance to other inhibitors in the existence of an anti-parallel double strand following the reactive site loop. 相似文献
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Gregor Leicht Stefan Troschütz Christina Andreou Evangelos Karamatskos Matthias Ertl Dieter Naber Christoph Mulert 《PloS one》2013,8(12)