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Significant Structural (significant + structural)

Distribution by Scientific Domains
Medical Sciences50%
Chemistry50%

Terms modified by Significant Structural

  • significant structural change
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  • significant structural difference
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    Selected Abstracts

    Structural and functional differences between the promoters of independently expressed killer cell Ig-like receptors

    EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 7 2005
    Bergen, Jeroen van
    Abstract Killer Ig-like receptors (KIR) are important for the recognition and elimination of diseased cells by human NK cells. Myeloid leukemia patients given a hematopoietic stem cell transplantation, for example, benefit from KIR-mediated NK alloreactivity directed against the leukemia cells. To establish an effective NK cell repertoire, most KIR genes are expressed stochastically, independently of the others. However, the sequences upstream of the coding regions of these KIR genes are highly homologous to the recently identified KIR3DL1 promoter (91.1,99.6% sequence identity), suggesting that they are regulated by similar if not identical mechanisms of transcriptional activation. We investigated the effects of small sequence differences between the KIR3DL1 promoter and other KIR promoters on transcription factor binding and promoter activity. Surprisingly, electrophoretic mobility shift assays and promoter-reporter assays revealed significant structural and functional differences in the cis-acting elements of these highly homologous KIR promoters, suggesting a key role for transcription factors in independent control of expression of specific KIR loci. Thus, the KIR repertoire may be shaped by a combination of both gene-specific and stochastic mechanisms. [source]

    Influence of Sulfonation on the Properties of Expanded Extrudates Containing 32% Whey Protein

    JOURNAL OF FOOD SCIENCE, Issue 2 2006
    David P. Taylor
    ABSTRACT Whey protein concentrate (WPC) was treated with sodium sulfite to achieve 4 levels of disulfide bond sulfonation (0%, 31%, 54%, and 71% mole/mole). The WPCs were blended with cornstarch to a 32% (weigh/weight) protein content and extruded into an expanded product. Extrudates were collected at 160 °C and 170 °C and analyzed for physical (air cell diameter, expansion ratio, breaking strength, and density) and chemical (water adsorption index [WAI], water solubility index, moisture content, soluble protein, and carbohydrates) properties. The control and 54% sulfonated samples had larger expansion ratios and air cell diameters and smaller densities and breaking strengths than the 31% and 71% samples. Expansion increased at 170 °C in the sulfonated samples. The WAI was influenced by both sulfonation and temperature, whereas the other chemical properties (except moisture content) were influenced only by sulfonation level. Soluble protein and carbohydrate were highest in the control and 54% samples. The anomalous behavior of the 54% sample may have been the result of significant structural and functional changes of ,-lactalbumin that are predicted to occur at approximately 50% sulfonation. Many functional properties of the WPCs were measured and were significantly correlated to the extrudate properties, particularly those related to protein unfolding and flexibility The increased ability for the proteins to become unfolded during extrusion may have promoted protein-starch interactions, which led to decreases in expansion and overall quality Disulfide bond content did influence the chemical and physical properties of an extruded-expanded whey protein products. [source]

    Mitochondrial displacements in response to nanomechanical forces

    JOURNAL OF MOLECULAR RECOGNITION, Issue 1 2008
    Yaron R. Silberberg
    Abstract Mechanical stress affects and regulates many aspects of the cell, including morphology, growth, differentiation, gene expression and apoptosis. In this study we show how mechanical stress perturbs the intracellular structures of the cell and induces mechanical responses. In order to correlate mechanical perturbations to cellular responses, we used a combined fluorescence-atomic force microscope (AFM) to produce well defined nanomechanical perturbations of 10,nN while simultaneously tracking the real-time motion of fluorescently labelled mitochondria in live cells. The spatial displacement of the organelles in response to applied loads demonstrates the highly dynamic mechanical response of mitochondria in fibroblast cells. The average displacement of all mitochondrial structures analysed showed an increase of ,40%, post-perturbation (,160,nm in comparison to basal displacements of ,110,nm). These results show that local forces can produce organelle displacements at locations far from the initial point of contact (up to ,40,µm). In order to examine the role of the cytoskeleton in force transmission and its effect on mitochondrial displacements, both the actin and microtubule cytoskeleton were disrupted using Cytochalasin D and Nocodazole, respectively. Our results show that there is no significant change in mitochondrial displacement following indentation after such treatments. These results demonstrate the role of the cytoskeleton in force transmission through the cell and on mitochondrial displacements. In addition, it is suggested that care must be taken when performing mechanical experiments on living cells with the AFM, as these local mechanical perturbations may have significant structural and even biochemical effects on the cell. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Loss of cartilage structure, stiffness, and frictional properties in mice lacking PRG4

    ARTHRITIS & RHEUMATISM, Issue 6 2010
    Jeffrey M. Coles
    Objective To assess the role of the glycoprotein PRG4 in joint lubrication and chondroprotection by measuring friction, stiffness, surface topography, and subsurface histology of the hip joints of Prg4,/, and wild-type (WT) mice. Methods Friction and elastic modulus were measured in cartilage from the femoral heads of Prg4,/, and WT mice ages 2, 4, 10, and 16 weeks using atomic force microscopy, and the surface microstructure was imaged. Histologic sections of each femoral head were stained and graded. Results Histologic analysis of the joints of Prg4,/, mice showed an enlarged, fragmented surface layer of variable thickness with Safranin O,positive formations sometimes present, a roughened underlying articular cartilage surface, and a progressive loss of pericellular proteoglycans. Friction was significantly higher on cartilage of Prg4,/, mice at age 16 weeks, but statistically significant differences in friction were not detected at younger ages. The elastic modulus of the cartilage was similar between cartilage surfaces of Prg4,/, and WT mice at young ages, but cartilage of WT mice showed increasing stiffness with age, with significantly higher moduli than cartilage of Prg4,/, mice at older ages. Conclusion Deletion of the gene Prg4 results in significant structural and biomechanical changes in the articular cartilage with age, some of which are consistent with osteoarthritic degeneration. These findings suggest that PRG4 plays a significant role in preserving normal joint structure and function. [source]