Structure analysis of CCR5 from human and primates

It is well known that the chemokine receptor CCR5 plays very important roles in HIV-1 virus infection. A three-dimensional molecular model of human CCR5 was generated by SYBYL, a distance geometry-based homologous modeling package, using the corresponding transmembrane domain of bacteriorhodopsin as the template. On the basis of human CCR5 model, we also built 18 3D molecular models of CCR5 in primates from Pongo pygmaeus, Pygathrix nemaeus, Macaca assameniss, Trachy-pithecus phayrei, T. francoisi, M. arotoides, Rhinopithecus roxellance, R, bieti, R. avunculus, Hylobates leucogenys, Pan troglodytes, Gorilla gorilla, Cercopithecus aethiops 1, C. aethiops 2, Papio hamadryas M. mulatta, M. fascicularis and M. nemestrina. Structural analyses and statistics results suggested that the main-chains of the primate CCR5 were similar to that of the human CCR5 and that the fit-RMS deviation values of these primate CCR5 were less than 0.1 Angstrom. Moreover, the structures of these CCR5 proteins, except those of the African green monkey 1 (C.aet1), do not have a remarkable difference. It is proved that the 14th residue is possibly very important in the inhibition infections by M-tropic HIV-1, and it is also demonstrated that the 13th residue of human CCR5 was changed from asparagine into aspartic acid in all these primates. It means that the primate CCR5 no longer depend on CD4 for efficient entry, but human CCR5 may have evolved subsequently due to the use of CD4 as a receptor, allowing the high-affinity chemokine receptor-binding site of HIV to be sequestered from host immune surveillance. (C) 2000 Elsevier Science B.V. All rights reserved.

基于手势输入构造三维概念模型的研究进展

综述了国内外基于手势输入构造三维概念模型的最新研究进展,讨论分析了手势交互过程及其关键技术:手势设计、手势识别、手势交互的层次结构以及手势交互的三维实现·最后对今后的发展方向进行了展望·

Comparisons of static, quasi-static and dynamic 3D porous media scale network models for two-phase immiscible flow in porous media

A dynamic 3D pore-scale network model is formulated for investigating the effect of interfacial tension and oil-water viscosity during chemical flooding. The model takes into account both viscous and capillary forces in analyzing the impact of chemical properties on flow behavior or displacement configuration, while the static model with conventional invasion percolation algorithm incorporates the capillary pressure only. From comparisons of simulation results from these models. it indicates that the static pore scale network model can be used successfully when the capillary number is low. With the capillary increases due to the enhancement of water viscosity or decrease of interfacial tension, only the quasi-static and dynamic model can give insight into the displacement mechanisms.

Microfluidic effects of transporting signaling components in cell coculture chips

A theoretical model has been developed to investigate the microfluidic transport of the signaling chemicals in the cell coculture chips. Using an epidermal growth factor (EGF)-like growth factor as the sample chemical, the effects of velocities and channel geometry were studied for the continuous-flow microchannel bioreactors. It is found that different perfusion velocities must be applied in the parallel channels to facilitate the communication, i.e., transport of the signaling component, between the coculture channels. Such communication occurs in a unidirectional way because the signaling chemicals can only flow from the high velocity area to the low velocity area. Moreover, the effect of the transport of the signaling component between the coculture channels on the growth of the monolayer cells and the multicellular tumor spheroid (MTS) in the continuous-flow coculture environment were simulated using 3D models. The numerical results demonstrated that the concentration gradients will induce the heterogeneous growth of the cells and the MTSs, which should be taken into account in designing the continuous-flow perfusion bioreactor for the cell coculture research.

A Trabecular Bone Explant Model of Osteocyte–Osteoblast Co-Culture for Bone Mechanobiology

The osteocyte network is recognized as the major mechanical sensor in the bone remodeling process, and osteocyte-osteoblast communication acts as an important mediator in the coordination of bone formation and turnover. In this study, we developed a novel 3D trabecular bone explant co-culture model that allows live osteocytes situated in their native extracellular matrix environment to be interconnected with seeded osteoblasts on the bone surface. Using a low-level medium perfusion system, the viability of in situ osteocytes in bone explants was maintained for up to 4 weeks, and functional gap junction intercellular communication (GJIC) was successfully established between osteocytes and seeded primary osteoblasts. Using this novel co-culture model, the effects of dynamic deformational loading, GJIC, and prostaglandin E-2 (PGE(2)) release on functional bone adaptation were further investigated. The results showed that dynamical deformational loading can significantly increase the PGE(2) release by bone cells, bone formation, and the apparent elastic modulus of bone explants. However, the inhibition of gap junctions or the PGE(2) pathway dramatically attenuated the effects of mechanical loading. This 3D trabecular bone explant co-culture model has great potential to fill in the critical gap in knowledge regarding the role of osteocytes as a mechano-sensor and how osteocytes transmit signals to regulate osteoblasts function and skeletal integrity as reflected in its mechanical properties.

Genetic evidence supports demic diffusion of Han culture

The spread of culture and language in human populations is explained by two alternative models: the demic diffusion model, which involves mass movement of people; and the cultural diffusion model, which refers to cultural impact between populations and in

Stocking models of Chinese mitten crab (Eriocheir japonica sinensis) in Yangtze lakes

The fanning of Chinese mitten crab, a quality aquatic product in China and neighbouring Asian countries, has been developing rapidly in China since last decade. It reached a total yield of 3.4 X 10(5) tonnes in 2002. Due to the successive over-stocking year after year, many lakes in the mid-lower Yangtze Basin, the main farming area, are under deterioration, leading to a reduction of crab yield and quality, and, subsequently, a loss of fanning profits. Aiming at a normal development of crab culture and the sustainable use of lakes, an annual investigation dealing with lake environmental factors in relation to stocked crab populations was carried out at 20 farms in 4 lakes. The results show that the submersed macrophyte biomass (B-Mac) is the key factor affecting annual crab yield (CY). Using the ratio of Secchi depth to mean depth (Z(SD)/Z(M)), an easily measured parameter closely correlated to BMac, as driving variable, 10 regression models of maximal crab yields were generated (r(2) ranging 0.49-0.81). Based on the theory of MSY (Maximum Sustainable Yield), in combination with body-weight (BW) and recapture rate (RR) of adult crabs, a general optimal stocking model was eventually formulated. All models are simple and easy to operate. Comments on their applications and prospects are given in brief. (c) 2006 Elsevier B.V. All rights reserved.

Effects of Ionizing Radiation on Three-Dimensional Human Vessel Models: Differential Effects According to Radiation Quality and Cellular Development

Little is known about the effects of space radiation on the human body. There are a number of potential chronic and acute effects, and one major target for noncarcinogenic effects is the human vasculature. Cellular stress, inflammatory response, and other radiation effects on endothelial cells may affect vascular function. This study was aimed at understanding the effects of space ionizing radiation on the formation and maintenance of capillary-like blood vessels. We used a 3D human vessel model created with human endothelial cells in a gel matrix to assess the effects of low-LET protons and high-LET iron ions. Iron ions were more damaging and caused significant reduction in the length of intact vessels in both developing and mature vessels at a dose of 80 cGy. Protons had no effect on mature vessels up to a dose of 3.2 Gy but did inhibit vessel formation at 80 cGy. Comparison with gamma radiation showed that photons had even less effect, although, as with protons, developing vessels were more sensitive. Apoptosis assays showed that inhibition of vessel development or deterioration of mature vessels was not due to cell death by apoptosis even in the case of iron ions. These are the first data to show the effects of radiation with varying linear energy transfer on a human vessel model. (C) 2011 In Radiation Research Society

Comparison of steroid substrates and inhibitors of P-glycoprotein by 3D-QSAR analysis

Steroid derivatives show a complex interaction with P-glycoprotein (Pgp). To determine the essential structural requirements of a series of structurally related and functionally diverse steroids for Pgp-mediated transport or inhibition, a three-dimensional quantitative structure activity relationship study was performed by comparative similarity index analysis modeling. Twelve models have been explored to well correlate the physiochemical features with their biological functions with Pgp on basis of substrate and inhibitor datasets, in which the best predictive model for substrate gave cross-validated q(2) = 0.720, non-cross-validated r(2) = 0.998, standard error of estimate SEE = 0.012, F = 257.955, and the best predictive model for inhibitor gave q(2) = 0.536, r(2) = 0.950, SEE = 1.761 and F = 45.800. The predictive ability of all models was validated by a set of compounds that were not included in the training set. The physiochemical similarities and differences of steroids as Pgp substrate and inhibitor, respectively, were analyzed to be helpful in developing new steroid-like compounds. (C) 2004 Elsevier B.V. All rights reserved.