Search results for "shape"
showing 10 items of 585 documents
Comparative analysis of virtual screening approaches in the search for novel EphA2 receptor antagonists
2015
The EphA2 receptor and its ephrin-A1 ligand form a key cell communication system, which has been found overexpressed in many cancer types and involved in tumor growth. Recent medicinal chemistry efforts have identified bile acid derivatives as low micromolar binders of the EphA2 receptor. However, these compounds suffer from poor physicochemical properties, hampering their use in vivo. The identification of compounds able to disrupt the EphA2-ephrin-A1 complex lacking the bile acid scaffold may lead to new pharmacological tools suitable for in vivo studies. To identify the most promising virtual screening (VS) protocol aimed at finding novel EphA2 antagonists, we investigated the ability of…
A natural-like synthetic small molecule impairs bcr-abl signaling cascades and induces megakaryocyte differentiation in erythroleukemia cells
2013
Over the past years, we synthesized a series of new molecules that are hybrids of spirocyclic ketones as complexity-bearing cores with bi- and ter-phenyls as privileged fragments. Some of these newly-shaped small molecules showed antiproliferative, pro-apoptotic and differentiating activity in leukemia cell lines. In the present study, to investigate more in depth the mechanisms of action of these molecules, the protein expression profiles of K562 cells treated with or without the compounds IND_S1, MEL_T1, IND_S7 and MEL_S3 were analyzed using two-dimensional gel electrophoresis coupled with mass spectrometry. Proteome comparisons revealed several differentially expressed proteins, mainly r…
U937 variant cells as a model of apoptosis without cell disintegration
2012
AbstractThe variant cell line U937V was originally identified by a higher sensitivity to the cytocidal action of tumor necrosis factor alpha (TNFα) than that of its reference cell line, U937. We noticed that a typical morphological feature of dying U937V cells was the lack of cellular disintegration, which contrasts to the formation of apoptotic bodies seen with dying U937 cells. We found that both TNFα, which induces the extrinsic apoptotic pathway, and etoposide (VP-16), which induces the intrinsic apoptotic pathway, stimulated U937V cell death without cell disintegration. In spite of the distinct morphological differences between the U937 and U937V cells, the basic molecular events of ap…
The effect of cadmium on brain cells in culture
2009
Cadmium is a long-living heavy metal, abundantly present in the environment, which accumulates in the body. In this study, we investigated the effects of cadmium on the expression of molecular chaperones, and of certain cell-specific proteins, in a variety of brain cell types in culture, namely primary cultures of rat cortical neurons and astrocytes, a brain capillary endothelial cell line (RB4E.B cells), and pheochromocytoma cells (PC12), induced or not to differentiate by NGF treatment. The metal induces a dose-dependent increase of Hsp70 in all cell types. Responses to the metal are cell-specific in the case of Hsc70 and Hsp90: i) in astrocytes, as well as in PC12 cells, cadmium has no s…
Cell shaping and microtubules in developing mesophyll of wheat (Triticum aestivum L.)
1990
Differentiated mesophyll cells ofTriticum aestivum (cv. Star) exhibit a lobed outline resembling tube-shaped balloons with almost regularly spaced constrictions. It was shown that these constrictions are probably the result of hoops of wall reinforcements laid down during early stages of cell expansion. It appears that these hoops prevent expansion in the corresponding regions and thus give rise to the peculiar cell shape. The comparatively thin cell walls of the bulges are uniformly reinforced after the lobed shape is established. By using immunofluorescence techniques a change in the pattern of cortical microtubule arrangement was observed which corresponded to the pattern of cell wall de…
Umbilical cord versus bone marrow-derived mesenchymal stromal cells.
2012
incetheplacentaisapostnatal tissue and discarded asmedical waste, harvesting stem cells from this organrepresents a noninvasive and ethically conductive proce-dure. Perinatal stem cells isolated from amnion, chorion,umbilical cord, and cord blood are increasingly viewedas reliable sources of mesenchymal stromal cells (MSCs)alternative to bone marrow-derived ones (BM-MSCs),which are currently the most commonly used in clinicalapplications [1–5].Perinatal stem cells are a bridge between embryonic stemcells (ESCs) and adult stem cells (such as BM-MSCs). Theyshare many characteristics of both cells [1,6]. Considering thestructural complexity of the term ‘‘placenta,’’ we have fo-cused our attent…
Neurons of the dentate molecular layer in the rabbit hippocampus.
2012
The molecular layer of the dentate gyrus appears as the main entrance gate for information into the hippocampus, i.e., where the perforant path axons from the entorhinal cortex synapse onto the spines and dendrites of granule cells. A few dispersed neuronal somata appear intermingled in between and probably control the flow of information in this area. In rabbits, the number of neurons in the molecular layer increases in the first week of postnatal life and then stabilizes to appear permanent and heterogeneous over the individuals' life span, including old animals. By means of Golgi impregnations, NADPH histochemistry, immunocytochemical stainings and intracellular labelings (lucifer yellow…
Magnetic field-induced alignment of molecular rotor-shaped cyclophanes
2010
Molecular pinwheels consisting of dipolar substituted cyclophanes in solution can function as free microscopic rotors in the presence of a homogeneous static magnetic field B and a circularly polarized electric field E rotating on a plane containing B. Owing to the high magnetic anisotropy of [26](1,2,3,4,5,6)cyclophane and [36](1,2,3,4,5,6)cyclophane biased by strong ring currents, ∼1 in 105 molecules are expected to align with the C6 symmetry axis perpendicular to a magnetic field of 21 T. The magnetic-field-controlled alignment of rotor-shaped cyclophanes is insignificantly affected by nonpolar solvents, for example, toluene.
El “giro morfológico”: la forma, condición del sentido
2006
This paper starts from the philosophical contradiction that we can call 'apory of logical fundament'. Logic appears, on the one side, as having the metaphysical pretensions of universality and wholeness and, on the other side, as having local efficiency in computers' concrete world. Several alternatives have tried to go over this apory, from alogical philosophies to logic amplifying attempts. René Thom's ontology changes the terms of the question and, instead of looking for the fundament in logic, he does so in topology. His slogan is: 'We have to found, not geometry in logic, but logic in geometry'. The fundamental ontological implication of this morphologic change is to find the sense con…
Prediction of Ductile Fractures Occurrence in Deep Drawing of Square Boxes
1996
Abstract The authors propose a new approach for the prediction of tearing in the deep drawing process of square boxes. Such an approach is based on a damage mechanics formulation and in particular on the yield condition for damaging materials proposed by Tvergaard and Needleman and on a strain controlled nucleation model. The flow rule associated to the yield condition is introduced in a finite element explicit formulation founded on the solution of the dynamic equilibrium equation and on an explicit time integration scheme. By this way the developed model allows to calculate the void volume fraction value during the deep drawing process of square boxes and consequently to predict the insur…