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121.
122.
《Biotechnic & histochemistry》2013,88(4):272-279
AbstractProtein–protein interactions play fundamental roles in most biological processes. Bimolecular fluorescence complementation (BiFC) is a promising method for its simplicity and direct visualization of protein–protein interactions in cells. This method, however, is limited by background fluorescence that appears without specific interaction between the proteins. We report here a point mutation (V150L) in one Venus BiFC fragment that efficiently decreases background fluorescence of BiFC assay. Furthermore, by combining this modified BiFC and linear expression cassette (LEC), we develop a simple and rapid method (LEC–BiFC) for protein interaction analysis that is demonstrated by a case study of the interaction between Bcl–XL and Bak BH3 peptide. The total analysis procedure can be completed in two days for screening tens of mutants. LEC–BiFC can be applied easily in any lab equipped with a fluorescence microscope. 相似文献
123.
Jesús Jiménez-Barbero Juan L. Asensio G. Cuevas A. Canales M. C. Fernández-Alonso F. Javier Cañada 《Biocatalysis and Biotransformation》2013,31(1-2):13-22
This review focuses, in a non-exhaustive manner, on the essential structural and conformational features of protein–carbohydrate interactions and on some applications of NMR spectroscopy to deal with this topic from different levels of complexity. 相似文献
124.
LoÏc Fin Reinhard Grebe 《Computer methods in biomechanics and biomedical engineering》2013,16(3):163-170
A computational fluid dynamics (CFD) method is presented to investigate the flow of cerebro-spinal fluid (CSF) in the cerebral aqueduct. In addition to former approaches exhibiting a rigid geometry, we propose a model which includes a deformable membrane as the wall of this flow channel. An anatomical shape of the aqueduct was computed from magnetic resonance images (MRI) and the resulting meshing was immersed in a marker-and-cell (MAC) staggered grid for to take into account fluid–structure interactions. The time derivatives were digitized using the Crank–Nicolson scheme. The equation of continuity was modified by introducing an artificial compressibility and digitized by a finite difference scheme. Calculations were validated with the simulation of laminar flow in a rigid tube. Then, comparisons were made between simulations of a rigid aqueduct and a deformable one. We found that the deformability of the walls has a strong influence on the pressure drop for a given flow. 相似文献
125.
Zachary J. Domire John H. Challis 《Computer methods in biomechanics and biomedical engineering》2013,16(6):693-699
The maximum velocity of shortening of a muscle is an important parameter in musculoskeletal models. The most commonly used values are derived from animal studies; however, these values are well above the values that have been reported for human muscle. The purpose of this study was to examine the sensitivity of simulations of maximum vertical jumping performance to the parameters describing the force–velocity properties of muscle. Simulations performed with parameters derived from animal studies were similar to measured jump heights from previous experimental studies. While simulations performed with parameters derived from human muscle were much lower than previously measured jump heights. If current measurements of maximum shortening velocity in human muscle are correct, a compensating error must exist. Of the possible compensating errors that could produce this discrepancy, it was concluded that reduced muscle fibre excursion is the most likely candidate. 相似文献
126.
R. Balossino G. Pennati F. Migliavacca L. Formaggia A. Veneziani M. Tuveri 《Computer methods in biomechanics and biomedical engineering》2013,16(1):113-123
This work addresses the problem of prescribing proper boundary conditions at the artificial boundaries that separate the vascular district from the remaining part of the circulatory system. A multiscale (MS) approach is used where the Navier–Stokes equations for the district of interest are coupled to a non-linear system of ordinary differential equations which describe the circulatory system. This technique is applied to three 3D models of a carotid bifurcation with increasing stenosis resembling three phases of a plaque growth. The results of the MS simulations are compared to those obtained by two stand-alone models. The MS shows a great flexibility in numerically predicting the haemodynamic changes due to the presence of a stenosis. Nonetheless, the results are not significantly different from a stand-alone approach where flows derived by the MS without stenosis are imposed. This is a consequence of the dominant role played by the outside districts with respect to the stenosis resistance. 相似文献
127.
128.
Jaykrishna Singh Fazle Hussain 《Computer methods in biomechanics and biomedical engineering》2013,16(3):282-292
Cell–cell and cell–matrix adhesions are fundamental to numerous physiological processes, including angiogenesis, tumourigenesis, metastatic spreading and wound healing. We use cellular potts model to computationally predict the organisation of cells within a 3D matrix. The energy potentials regulating cell–cell (JCC) and cell–matrix (JMC) adhesive interactions are systematically varied to represent different, biologically relevant adhesive conditions. Chemotactically induced cell migration is also addressed. Starting from a cluster of cells, variations in relative cell adhesion alone lead to different cellular patterns such as spreading of metastatic tumours and angiogenesis. The combination of low cell–cell adhesion (high JCC) and high heterotypic adhesion (low JMC) favours the fragmentation of the original cluster into multiple, smaller cell clusters (metastasis). Conversely, cellular systems exhibiting high-homotypic affinity (low JCC) preserve their original configuration, avoiding fragmentation (organogenesis). For intermediate values of JCC and JMC (i.e. JCC/JMC ~ 1), tubular and corrugated structures form. Fully developed vascular trees are assembled only in systems in which contact-inhibited chemotaxis is activated upon cell contact. Also, the rate of secretion, diffusion and sequestration of chemotactic factors, cell deformability and motility do not significantly affect these trends. Further developments of this computational model will predict the efficacy of therapeutic interventions to modulate the diseased microenvironment by directly altering cell cohesion. 相似文献
129.
J. Müller O. Sahni X. Li K. E. Jansen M. S. Shephard C. A. Taylor 《Computer methods in biomechanics and biomedical engineering》2013,16(5):295-305
In this study, we present an adaptive anisotropic finite element method (FEM) and demonstrate how computational efficiency can be increased when applying the method to the simulation of blood flow in the cardiovascular system. We use the SUPG formulation for the transient 3D incompressible Navier–Stokes equations which are discretised by linear finite elements for both the pressure and the velocity field. Given the pulsatile nature of the flow in blood vessels we have pursued adaptivity based on the average flow over a cardiac cycle. Error indicators are derived to define an anisotropic mesh metric field. Mesh modification algorithms are used to anisotropically adapt the mesh according to the desired size field. We demonstrate the efficiency of the method by first applying it to pulsatile flow in a straight cylindrical vessel and then to a porcine aorta with a stenosis bypassed by a graft. We demonstrate that the use of an anisotropic adaptive FEM can result in an order of magnitude reduction in computing time with no loss of accuracy compared to analyses obtained with uniform meshes. 相似文献
130.
Valérie Abécassis Philippe Urban Lawrence Aggerbeck Gilles Truan Denis Pompon 《Biocatalysis and Biotransformation》2013,31(2):55-66
AbstractTwo complementary methods are described that associate in vitro and in vivo steps to generate sequence diversity by segment directed saturated mutagenesis and family shuffling. A high-throughput DNA chip-based procedure for the characterization and potentially the equalization of combinatorial libraries is also presented. Using these approaches, two combinatorial libraries of cytochrome P450 variants derived from the CYP1A subfamily were constructed and their sequence diversity characterized. The results of functional screening using high-throughput tools for the characterization of membrane P450-catalyzed activities, suggest that the 204–214 sequence segment of human CYP1A1 is not critical for polycyclic aromatic hydrocarbon recognition, as was hypothesized from previous data. Moreover, mutations in this segment do not alter the discrimination between alkoxyresorufins, which, for all tested mutants, remained similar to that of wild-type CYP1A1. In contrast, the constructed CYP1A1–CYP1A2 mosaic structures, containing multiple crossovers, exhibit a wide range of substrate preference and regioselectivity. These mosaic structures also discriminate between closely related alkoxyresorufin substrates. These results open the way to global high-throughput analysis of structure–function relationships using combinatorial libraries of enzymes together with libraries of structurally related substrates. 相似文献