A multi-scale clutch model for adhesion complex mechanics.

Cell-matrix adhesion is a central mechanical function to a large number of phenomena in physiology and disease, including morphogenesis, wound healing, and tumor cell invasion. Today, how single cells respond to different extracellular cues has been comprehensively studied. However, how the mechanical behavior of the main individual molecules that form an adhesion complex cooperatively responds to force within the adhesion complex is still poorly understood. This is a key aspect of cell adhesion because how these cell adhesion molecules respond to force determines not only cell adhesion behavior but, ultimately, cell function. To answer this question, we develop a multi-scale computational model for adhesion complexes mechanics. We extend the classical clutch hypothesis to model individual adhesion chains made of a contractile actin network, a talin rod, and an integrin molecule that binds at individual adhesion sites on the extracellular matrix. We explore several scenarios of integrins dynamics and analyze the effects of diverse extracellular matrices on the behavior of the adhesion molecules and on the whole adhesion complex. Our results describe how every single component of the adhesion chain mechanically responds to the contractile actomyosin force and show how they control the traction forces exerted by the cell on the extracellular space. Importantly, our computational results agree with previous experimental data at the molecular and cellular levels. Our multi-scale clutch model presents a step forward not only to further understand adhesion complexes mechanics but also to impact, e.g., the engineering of biomimetic materials, tissue repairment, or strategies to arrest tumor progression.

Impact of the reaction pathway on the final product in on-surface synthesis.

On-surface synthesis provides a very promising strategy for creating stable functional structures on surfaces. In the past, classical reactions known from solution synthesis have been successfully transferred onto a surface. Due to the presence of the surface, on-surface synthesis provides the potential of directing the reaction pathway in a manner that might not be accessible in classical solution synthesis. In this work, we present evidence for an acetylene polymerization from a terminal alkyne monomer deposited onto calcite (10.4). Strikingly, although the dimer forms on the surface as well, we find no indication for diacetylene polymerization. This is in sharp contrast to what is observed when directly depositing the dimers on the surface. The different pathways are linked to the specific arrangement of the dimers on the surface. When forming stripes along the [-4-21] direction, the diacetylene polymerization is prohibited, while when arranged in stripes aligned along the [010] direction, the dimers can undergo diacetylene polymerization. Our work thus constitutes a demonstration for controlling the specific reaction pathway in on-surface synthesis by the presence of the surface.

Simple and economic elaboration of high purity CaCO3 particles for bone graft applications using a spray pyrolysis technique.

Materials for bone grafting are a major health stake today. The existing synthetic materials only partially answer to the requirements for such uses and do not provide a real alternative solution to the classical way consisting of the reuse of natural osseous materials, known to create other problems. In the present work, we have prepared calcium carbonate powders using spray pyrolysis in the perspective to realize ideal and multi-purposed bricks to form bone graft materials, by bottom-up approaches, using classical techniques. The chemical reactions involved in the synthesis process consist in the thermal decomposition of calcium acetate. This precursor, a classical food additive, is known to be non toxic, easy to use and very cheap. Morphological and chemical characterization was conducted on the obtained materials. Depending on the pyrolysis temperature, we observed partial decomposition of calcium acetate or lime formation. An annealing step is consequently required to finalize the transformation. Finally, it appears that annealed products are pure calcite particles, having a spherical morphology and possessing a low dispersity in the micron size range. These particles exhibit an original internal structure, reinforcing and ensuring the preservation of their morphological characteristics during the sintering process. Furthermore, a porosity value compatible with drug carrier capabilities was measured on the obtained products. All these qualities allow us to consider a multi-purpose use of these particles in almost all types of bone graft materials.

Crystal structure of 3-ethynyl-benzoic acid.

In the title compound, C9H6O2, the carb-oxy-lic acid group is almost in the plane of the benzene ring, making a dihedral angle of 2.49 (18)°. In the crystal, mol-ecules are linked by pairs of O-H⋯O hydrogen bonds, forming classical acid-acid inversion dimers, with an R 2 (2)(8) ring motif. The dimers are linked by pairs of C-H⋯O hydrogen bonds forming chains, enclosing R 2 (2)(16) ring motifs, propagating along the c-axis direction.

Effect of the alkyl chains and of the headgroups on the thermal behavior of ascorbic acid surfactants mixtures.

The role of the alkyl chain length and of the headgroup on the thermal behavior of mixtures of ASC8 (ascorbyl octanoate) and ASC16 (ascorbyl hexadecanoate) was investigated through differential scanning calorimetry, small- and wide-angle X-ray scattering, and Fourier transform infrared spectroscopy experiments. The formation of two eutectics and of a peritectic point was found from the phase diagram, and their structural properties were studied. The results were compared by investigating the thermal behavior of mixtures of octanoic acid and hexadecanoic acid. The findings provide insights into the role of the ascorbyl headgroups on the intermolecular interactions that determine the phase behavior of the two ascorbic acid based surfactants in the solid state.

[Usefulness of an audiovisual support to informed consent before percutaneous coronary intervention procedures]. / Utilità di un supporto audiovisivo nella preparazione del paziente alle procedure di cardiologia invasiva.

BACKGROUND: Informed consent must be obtained from all patients undergoing medical procedures, especially when these imply a significant risk of severe adverse events. However, as for interventional cardiology, recall of information has been shown to be poor. In this study we evaluated the usefulness of an audiovisual support, in adjunct to the standard written informative form, in obtaining: (a) effective patient information before invasive coronary procedures, and (b) patient familiarization with the cath lab team, equipment, and the main procedural phases. METHODS: The audiovisual informative support was carried out through explicative interviews to the operators of the cath lab, animations, and realistic visualization of the procedural phases. Patient information was evaluated with a multiple-choice questionnaire. Self-assessment of the patient's emotional state was also evaluated using a semiquantitative scale. RESULTS: Patients receiving the audiovisual support in adjunct to written informative form showed a significantly lower rate of erroneous answers at the multiple-choice questionnaire with respect to patients receiving just written informative form (1.1 +/- 1.0 vs. 3.2 +/- 1.7; p < 0.001). Moreover, patients informed through the audiovisual support showed a slight, although statistically significant, reduction in semiquantitative indexes of anxiety (p = 0.0021) and experienced pain (p = 0.034). CONCLUSIONS: The use of an audiovisual support may favor patient's adequate information prior to written consent and, when prepared by the cath lab team operators, it may optimize his emotional state through a "familiarization effect".