The ligation and clustering of cell surface ␣ heterodimeric integrins enhances cell adhesion and initiates signaling pathways that regulate such processes as cell spreading, migration, differentiation, proliferation and apoptosis. Here we show that insulin treatment of Chinese hamster ovary cells expressing insulin receptors (CHO-T) markedly promotes cell adhesion onto a fibronectin matrix, but not onto bovine serum albumin or poly-lysine. Incubation of cells with a GRGDSP peptide that specifically binds integrins (but not the nonspecific GRADSP peptide) abolishes this insulin effect, as does the potent phosphoinositide 3-kinase (PI 3-kinase) inhibitor wortmannin. Moreover, a specific blocking monoclonal anti-␣ 5  1 integrin antibody, PB-1, blocks insulin-stimulated cell adhesion onto fibronectin. Conversely, activating ␣ 5  1 integrins on CHO-T cells by adherence onto fibronectin markedly potentiates the action of insulin to enhance insulin receptor and insulin receptor substrate (IRS)-1 tyrosine phosphorylation. Activation of ␣ 5  1 integrin also markedly potentiates the recruitment of p85-associated PI 3-kinase activity to IRS-1 in response to submaximal levels of insulin in CHO-T cells. These data indicate that insulin potently activates integrin ␣ 5  1 mediated CHO-T cell adhesion, while integrin ␣ 5  1 signaling in turn enhances insulin receptor kinase activity and formation of complexes containing IRS-1 and PI 3-kinase. These findings raise the hypothesis that insulin receptor and ␣ 5  1 integrin signaling act synergistically to enhance cell adhesion.The tyrosine kinase activity of the cell surface insulin receptor is required to mediate its many biological actions. Insulin receptor activation promotes the rapid autophosphorylation of its  subunit, as well as tyrosine phosphorylation of proteins involved in insulin signaling, such as insulin receptor substrate (IRS) 1 and Shc proteins (1-4). Insulin-mediated phosphorylation of these proteins is thought to provide tyrosine phosphate docking sites for the recruitment of signaling proteins containing Src homology 2 domains (SH2) (1, 5, 6). One SH2 domaincontaining family of proteins which associates with IRS proteins in response to insulin are isoforms of the p85 regulatory subunit of the p110-type PI 3-kinases (1-4, 7). PI 3-kinase activity in such signaling complexes appears to be required for insulin action on many cellular processes, including glucose transport (8, 9), glycogen synthesis (9, 10), stress fiber breakdown (11), and membrane ruffling (12). Thus, inhibition of PI 3-kinase activity by wortmannin or disruption of PI 3-kinase recruitment to IRS proteins by dominant inhibitory constructs of p85 subunits ablate the actions of insulin on these processes (11-13). Our understanding of the downstream elements that mediate the action of the 3Ј-phosphoinositide products of the PI 3-kinases is incomplete, but appear to include protein kinases such as PDK1 and Akt/protein kinase B (PKB) (14), a family of proteins containing Sec7 homology domains (...
Recently, we proposed a computational design strategy for organic nonlinear optical materials, based on the global minimization of lattice energy to predict the crystal packing from the first principles. Here, we validate this strategy on triiodobenzenes, which include CH···I hydrogen and I···I halogen bonding as the structure-determining components of their intermolecular interactions. To refine the van der Waals (vdW) parameters for an I atom, the ab initio potential surfaces for the model dimers were calculated at the CCSD(T)/cc-pVTZ + CP theory level. The hydrogen bond C–H···I was found to have an interaction energy of −0.5 kcal/mol. The I···I contact of type I (140°–140°) was found to be attractive with a well depth of −0.4 kcal/mol at a 4.6 Å distance, whereas type II contact (180°–90°) was found to be nearly twice more attractive. Its potential well depth reaches −0.7 kcal/mol at an I···I distance of 4.4 Å. These binding energies are therefore weaker than that of the typical hydrogen bonds. The AMOEBA force-field vdW parameters were fit to describe these interactions and used to predict the crystal structures. Our structure prediction, followed by density functional theorymany-body dispersion ranking established the noncentrosymmetric crystal packing to be the global minimum, in agreement with the experimental data. The coupled perturbed Kohn–Sham approach was used to estimate nonlinear susceptibility, and the predicted values were compared to that of the urea standard. The statistical analysis of the angular distribution for the I···I contacts in the predicted virtual polymorphs was compared to that found among the experimental crystal structures of iodoaromatic compounds. In both cases, symmetric (type I) contacts dominate for shorter and longer I···I distances, whereas L-shaped (type II) contacts are preferred for intermediate distances.
Defining the flow and distribution of fluids in porous media has always been of key importance in modeling and predicting the performance of oil and gas reservoirs. Based upon the rock-fluid interactions, reservoir rocks have to be classified into separate flow units called rock types. This task is particularly complex in carbonates as they are generally impacted by diagenesis and cannot be represented by a single porosity permeability relationship per litho-facie. Establishing accurate rock types in carbonates, therefore, requires integration of various petrophysical data with the available rock, fluid and geological information. Various techniques have evolved in the industry for formulating rock-types (Pittman, RQI, FZI, Lucia, Winland, etc.), each technique offering its benefit depending on the nature and variety of data available. This paper presents a newly adopted workflow to formulate an RRT definition for a carbonate reservoir by integrating data from MICP, CCA, petrophysical logs and lithofacies information. The workflow involves associating the pore throat size distribution evaluated using MICP data with the measured porosity and permeability values utilizing the Winland R35 equation. Hydraulic flow units are identified using the Stratigraphic Lorenz Plot, based on the change of flow and storage capacity slopes. Pc, PTR, Phi and K discriminators were established and were used to as cut-offs for defining intervals representing good and poor facies. The new methodology helped to achieve a very good match (>80%) of water saturation from the initialized model with the log derived saturations in all wells drilled thus far in Reservoir-A. The methodology further helped optimize the number of effective rock types required to effectively delineate the field dynamic characteristics, helping reduce run time and anticipated convergence issues.
The aim of this study is to propose a stratigraphic and sedimentary framework though the integration of available sedimentary, diagenetic and petrophysical data, which will be utilized in the construction of a high resolution stratigraphic framework, as an input into comprehensive review and update of an existing model of heterogeneous carbonate reservoir in a mature field in Abu Dhabi, UAE. Depositional facies have been defined in cored wells, subsequently were associated taking into account the biologic and sedimentary processes in response of carbonate growing and sea level changes, allowing the identification of the main stratigraphic surfaces. Surfaces can extend the correlation along the field and define the model of facies that, with the evidence provided by cores, can recreate and predict the different regressive-transgressive cycles in high resolution which the carbonate platform were undergone during its evolution. Diagenetic evolution, interpreted through laboratory observations, was integrated with facies and petrophysical evaluation allowing the understanding of the spatial distribution of petrophysical properties within a heterogeneous reservoir and define a new set of facies which will be used in the generation of geological static model. Application of sequence stratigraphy methods in cores, and extended in logs allowed the identification of six depositional sequences, with thicknesses of 2 to 4 meters each, corresponding to the phases of carbonate platform growth. Within each depositional sequences, typical cycles were defined that support the understanding in the association of facies and their relationship during the deposition. The identification of sedimentological cycles not only genetically organizes the facies and predicts the stacking pattern, but also makes possible to find an excellent correspondence between cycles from lowstand system track intervals with good to excellent permeability values, and cycles from transgressive system track intervals with low permeabilities. Many of the sequence stratigraphy published articles driven for the most important reservoirs along the Arabian Plate, provide an excellent tool in the regional correlation. However, they are not enough to be used in the reservoir characterization in detail that is required during the development of the field neither as input data in the generation of geological static models that use the sedimentary trends as constrain to populate the petrophysical properties.
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