Brachydactyly

Brachydactyly ("short digits") is a general term that refers to disproportionately short fingers and toes, and forms part of the group of limb malformations characterized by bone dysostosis. The various types of isolated brachydactyly are rare, except for types A3 and D. Brachydactyly can occur either as an isolated malformation or as a part of a complex malformation syndrome. To date, many different forms of brachydactyly have been identified. Some forms also result in short stature. In isolated brachydactyly, subtle changes elsewhere may be present. Brachydactyly may also be accompanied by other hand malformations, such as syndactyly, polydactyly, reduction defects, or symphalangism

Aluminum magadiite: An acid solid layered material

Aluminum-modified magadiite samples with high concentration of aluminum have been synthesized under hydrothermal conditions by modifying the traditional preparation route of the layered siliceous material. A new synthetic strategy, named aluminum-induced crystallization (AIC) method, was thus developed to introduce different amounts of Al in the siliceous framework. A systematic study of the physicochemical properties and thermal behavior of the produced Al-derived magadiite materials was performed by combining different experimental techniques [infrared spectroscopy (IR) of adsorbed probe molecules, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and solid-state magic-angle spinning nuclear magnetic resonance (SS MAS NMR)]. Al-27 SS MAS NMR showed that the synthesis method allowed us to introduce for the first time Al ions in a magadiite framework in tetrahedral positions. Variable-temperature XRD analysis showed that the introduction of Al in tetrahedral position does not affect the thermal stability of the silica layers. The presence of Al ions led to a modification of the surface acidity of magadiite. Indeed, Fourier transform infrared (FTIR) measurements of CO adsorbed at 100 K indicated the presence of Bronsted acidity similar to that found in highly acidic zeolites. The amount of acid sites is progressively increased by introducing increasing amounts of Al in the framework. Moreover, different families of Bronsted acid sites with different acid strengths are present at higher Al content, thus revealing the possibility to tune the surface acidity of these materials.19174300431

Revisiting the nature of the acidity in chabazite-related silicoaluminophosphates: Combined FTIR and Si-29 MAS NMR study

The acidity of crystalline silicoaluminophosphates with chabazite-related structure (CHA), was studied by using CO and C2H4 probe molecules. SAPO-34 samples with similar silicon concentrations prepared using different structure-directing agents have been studied, and the results have been compared with a silicoaluminophosphate, CAL-1, having a similar structure and much higher silicon concentration. A detailed analysis of the FTIR spectra in the OH stretching region, and of the downward shift of the OH bands upon CO and C2H4 adsorption, evidenced the presence of three distinct acid sites (named OHA, OHB, and OHC) absorbing at 3631, 3617, and 3600 cm(-1), respectively (average values). A multipeak curve-fitting approach, along with hydrogen bond theory, following Makarova et al. (J. Phys. Chem. 1994, 98, 3619), allowed us to compute the fraction of the three sites. While the two main components OHA and OHC were already reported and explained in terms of different crystallographic positions, the existence and nature of the OHB site are here discussed for the first time. Protons at the OHB sites are shown to have an acidity (downward shift upon CO adsorption of ca. 330 cm(-1)) comparable to that usually measured in zeolites, aluminosilicate crystalline materials, which are known to possess stronger acidity than SAPOs. To our knowledge, this is the first clear-cut experimental evidence that such strong acid sites are present in SAPO materials. A combined FTIR and Si-29 MAS NMR study permitted explaining the strong acidity of OHB sites in terms of protons either at the borders of silica patches/islands or inside aluminosilicate domains.111133033

Heme drives hemolysis-induced susceptibility to infection via disruption of phagocyte functions

International audienceHemolysis drives susceptibility to bacterial infections and predicts poor outcome from sepsis. These detrimental effects are commonly considered to be a consequence of heme-iron serving as a nutrient for bacteria. We employed a Gram-negative sepsis model and found that elevated heme levels impaired the control of bacterial proliferation independently of heme-iron acquisition by pathogens. Heme strongly inhibited phagocytosis and the migration of human and mouse phagocytes by disrupting actin cytoskeletal dynamics via activation of the GTP-binding Rho family protein Cdc42 by the guanine nucleotide exchange factor DOCK8. A chemical screening approach revealed that quinine effectively prevented heme effects on the cytoskeleton, restored phagocytosis and improved survival in sepsis. These mechanistic insights provide potential therapeutic targets for patients with sepsis or hemolytic disorders