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The first order approximation of the theory of the so-called simple material describes the viscoelastic behavior of soft polymers in large deformations with twelve time-dependent material functions and three material constants, all functions of the three invariants of the deformation tensor. Restricting consideration to deformations in which time shift invariance is preserved, a series of models was developed which describe the time dependence of the stress through the Boltzmann superposition integral incorporating into it a suitable nonlinear measure of strain. The theory was developed in its most general three-dimensional form. Its predictions for homogeneous deformations were tested in a series of experiments on an uncrosslinked styrene-butadiene copolymer.

For the prediction of the viscoelastic behavior of soft polymers the simplest form of the theory requires only one time function, the relaxation modulus. In addition, it requires a strain parameter which is a characteristic material constant. The dependence of this parameter on temperature and other material and experimental variables was examined on hand of estimates from published data as well as from the experimental results reported here.

ERYtech Pharma has been chosen to present the initial results obtained with its preclinical product GR-ARA1 on sickle cell anemia at the 50th annual congress of the American Society of Hematology (ASH), to be held in San Francisco (United States) from 6 to Dec. 9, 2008.

Sickle cell disease is a genetic disease characterized by the presence of sickle red blood cells in patients suffering from hypoxia (about 100,000 cases in Europe and North America).

Investigators from the Consejo Superior de Investigaciones Científicas (CSIC) and the University of Las Palmas de Gran Canaria and California (USA) have discovered a molecular mechanism involved in the development of autoimmune diseases like lupus. These are the receptors LXR (Liver X Receptors) that regulate the removal of the remains of dead cells by apoptosis, a process that, when it fails, it causes inflammation of surrounding tissue and the body's immune response. The research, conducted with mice, opens the door to the use of these receptors as therapeutic targets for these diseases.

Antonio Castrillo, CSIC researcher at the Institute for Biomedical Research (Joint CSIC and Universidad Autónoma de Madrid) and director of research, explains: "The research in mice has shown that in the absence of these receptors, the process of removal of dead cells is severely compromised. "According to the research, these receptors, proteins residing in the cell nucleus and known so far for its role in cholesterol metabolism, regulate the expression of an important gene involved in removal of cellular debris.