Search

The selective targeting of protein–protein interactions remains a significant determinant for the proper modulation and regulation of cell apoptosis. Prototypic galectins such as human galectin-7 (GAL-7) are characterized by their ability to form homodimers that control the molecular fate of a cell by mediating subtle yet critical glycan-dependent interactions between pro- and anti-apoptotic molecular partners. Altering the structural architecture of GAL-7 can therefore result in resistance to apoptosis in various human cancer cells, further illustrating its importance in cell survival. In this study, we used a combination of biophysical and cellular assays to illustrate that binding of a water-soluble meso-tetraarylporphyrin molecule to GAL-7 induces protein oligomerization and modulation of GAL-7-induced apoptosis in human Jurkat T cells. Our results suggest that the integrity of the GAL-7 homodimer architecture is essential for its molecular function, in addition to providing an interesting porphyrin binding modulator for controlling apoptosis in mammalian cells.

Although antibodies remain a primary recognition element in all forms of biosensing, functional limitations arising from their size, stability, and structure have motivated the development and production of many different artificial scaffold proteins for biological recognition. However, implementing such artificial binders into functional high-performance biosensors remains a challenging task. Here, we present the design and application of Förster resonance energy transfer (FRET) nanoprobes comprising small artificial proteins (αRep bidomains) labeled with a Tb complex (Tb) donor on the C-terminus and a semiconductor quantum dot (QD) acceptor on the N-terminus. Specific binding of one or two protein targets to the αReps induced a conformational change that could be detected by time-resolved Tb-to-QD FRET. These single-probe FRET switches were used in a separation-free solution-phase assay to quantify different protein targets at sub-nanomolar concentrations and to measure the conformational changes with sub-nanometer resolution. Probing ligand–receptor binding under physiological conditions at very low concentrations in solution is a special feature of FRET that can be efficiently combined with other structural characterization methods to develop, understand, and optimize artificial biosensors. Our results suggest that the αRep FRET nanoprobes have a strong potential for their application in advanced diagnostics and intracellular live-cell imaging of ligand–receptor interactions.

Ce cas clinique illustre l’importance de l’examen clinique ainsi que de l’anamnèse pour le diagnostic et la prise en charge des traumatismes aigus du genou. Un homme âgé de 43 ans se présente aux urgences du centre hospitalier du centre Bretagne suite à une douleur du genou droit au décours d’une chute en escalade en se jetant d’un agrès. L’anamnèse rapporte un mécanisme de traumatisme sans contact avec une contraction musculaire intense excentrique lors d’un mouvement de réception sur la jambe droite en flexion. À ce moment, il a ressenti une vive douleur en regard du genou. L’articulation a immédiatement « gonflé » selon ses termes et est associée d’une impotence fonctionnelle. À l’examen clinique, la patella est remontée le long du quadriceps, il existe un creux entre la patella et la tubérosité tibiale antérieure, l’extension active de la jambe est impossible. Cette triade clinique est un élément qui permet de poser le diagnostic de rupture du tendon patellaire. L’interrogatoire et l’examen clinique semblent suffir à établir le diagnostic de rupture complète du tendon patellaire et orienter le patient en chirurgie.

Proteins are the most specific yet versatile biological self-assembling agents with a rich chemistry. Nevertheless, the design of new proteins with recognition capacities is still in its infancy and has seldom been exploited for the self-assembly of functional inorganic nanoparticles. Here, we report on the protein-directed assembly of gold nanoparticles using purpose-designed artificial repeat proteins having a rigid but modular 3D architecture. αRep protein pairs are selected for their high mutual affinity from a library of 109variants. Their conjugation onto gold nanoparticles drives the massive colloidal assembly of free-standing, one-particle thick films. When the average number of proteins per nanoparticle is lowered, the extent of self-assembly is limited to oligomeric particle clusters. Finally, we demonstrate that the aggregates are reversibly disassembled by an excess of one free protein. Our approach could be optimized for applications in biosensing, cell targeting, or functional nanomaterials engineering.

Molecular mechanics calculations performed on calix[4]arene crown-6 ethers predict that the 1,3-dihydro derivatives will exhibit greater complementarity for potassium and cesium ions than the parent 1,3-bis(alkyloxy) calixcrowns. The X-ray crystal structures of 1,3-alt-bis(octyloxy)calix[4]arene benzocrown-6 ether, dihydrocalix[4]arene benzocrown-6 ether, and the cesium nitrate complex of dihydrocalix[4]arene benzocrown-6 ether were determined. The structure of the cesium complex corresponds closely to the structure predicted by molecular mechanics. The dihydrocalix[4]arene crown-6 ethers exhibit enhanced cesium selectivity in the extraction of alkali-metal salts. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Molecular mechanics calculations performed on calix[4]arene crown-6 ethers predict that the 1,3-dihydro derivatives will exhibit greater complementarity for potassium and cesium ions than the parent 1,3-bis(alkyloxy) calixcrowns. The X-ray crystal structures of 1,3-alt-bis(octyloxy)calix[4]arene benzocrown-6 ether, dihydrocalix[4]arene benzocrown-6 ether, and the cesium nitrate complex of dihydrocalix[4]arene benzocrown-6 ether were determined. The structure of the cesium complex corresponds closely to the structure predicted by molecular mechanics. The dihydrocalix[4]arene crown-6 ethers exhibit enhanced cesium selectivity in the extraction of alkali-metal salts. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

ABSTRACTThe extraction of cesium nitrate from a mixture of alkali metal nitrates by calix7lsqb;4]arene crown-6 ethers in 1,2-dichloroethane diluent has been surveyed at 25 °C. The results reveal that smaller substituents (but larger than C2,) at the phenolic positions of the calixarene opposite the crown ether increase both the extraction efficiency and the cesium selectivity. Benzo substituents on the crown ether tend to decrease extraction strength while increasing cesium-to-sodium selectivity. Conversely, a cyclohexano group on the crown ether has a negative impact on both extraction strength and selectivity.

Diaphragmatic paralysis, a difficult diagnosis in the pediatric age group, has classically been made by fluoroscopy or B-mode ultrasound. We report our experience with TM-mode exploration. Twenty-seven patients suspected to have diaphragmatic paralysis were examined by means of inspiratory and expiratory chest radiography, fluoroscopy and B-mode ultrasound. The diaphragmatic echo was recorded on TM-tracing during spontaneous breathing using coronal oblique scans. Direction, excursion and the pattern of the transition between inspiration and expiration were analysed. In 7 patients examination was normal and TM mode demonstrated movement of normal direction and excursion with a sharp aspect of the transition zone. Diaphragmatic paralysis was present in 11 patients: unilateral in 9 and bilateral in 2 cases. TM mode demonstrated paradoxical movement, reduced excursion and a smooth transition zone. In 9 patients with diaphragmatic dysfunction TM mode demonstrated movement in the normal direction but with reduced excursion and a smooth transition zone. Compared to other imaging modalities, TM-mode records diaphragmatic movements more objectively. It can identify direction of the movement even if they are fast and of weak amplitude and in the case of bilateral paralysis. TM can differentiate paralysis from dysfunction. Moreover, this low-cost, non-irradiating made of imaging can be performed at the bedside and is available on all basic devices.

Calix[4]arene crown-6 ethers derived from dideoxygenated calix[4]arene exhibit enhanced extraction selectivity for caesium over potassium; the crystal stucture of the uncomplexed calix[4]arene monobenzocrown-6 ether exists in the 1,3-alt conformation in the solid state.

Calix[4]arene crown-6 ethers derived from dideoxygenated calix[4]arene exhibit enhanced extraction selectivity for caesium over potassium; the crystal stucture of the uncomplexed calix[4]arene monobenzocrown-6 ether exists in the 1,3-alt conformation in the solid state.

Thymic hemorrhage related to coagulopathy by vitamin K deficiency is a rare condition. We report a case in a 4-week-old boy presenting with acute onset of respiratory distress and anemia. Ultrasound examination of a compressive anterior mediastinal mass established the diagnosis of thymic hemorrhage and allowed us to follow resolution under medical treatment.