[Radial artery occlusion ofter coronarography: is it really a problem?] / L'occlusion de l'artère radiale après cathétérisme cardiaque : est-ce réellement un problème ?

The use of transradial access for cardiac procedures has increased worldwide over the past two decades. Despite the many advantages this technique offers, there remains some concern that radial artery occlusion, a potential complication of radial cannulation, might lead to significant ischemic sequelae in the hand. This paper reviews the major causes, its possible consequences and the strategies for its prevention and treatment. It appears however from multiple studies that there is little or no correlation between radial occlusion and symptomatic hand ischemia.

Single-atom vibrational spectroscopy in the scanning transmission electron microscope.

Single-atom impurities and other atomic-scale defects can notably alter the local vibrational responses of solids and, ultimately, their macroscopic properties. Using high-resolution electron energy-loss spectroscopy in the electron microscope, we show that a single substitutional silicon impurity in graphene induces a characteristic, localized modification of the vibrational response. Extensive ab initio calculations reveal that the measured spectroscopic signature arises from defect-induced pseudo-localized phonon modes-that is, resonant states resulting from the hybridization of the defect modes and the bulk continuum-with energies that can be directly matched to the experiments. This finding realizes the promise of vibrational spectroscopy in the electron microscope with single-atom sensitivity and has broad implications across the fields of physics, chemistry, and materials science.

Phonon Spectroscopy at Atomic Resolution.

Advances in source monochromation in transmission electron microscopy have opened up new possibilities for investigations of condensed matter using the phonon-loss sector of the energy-loss spectrum. Here, we explore the spatial variations of the spectrum as an atomic-sized probe is scanned across a thin flake of hexagonal boron nitride. We demonstrate that phonon spectral mapping of atomic structure is possible. These results are consistent with a model for the quantum excitation of phonons and confirm that Z-contrast imaging is based on inelastic scattering associated with phonon excitation.

Tissue Lignification, Cell Wall p-Coumaroylation and Degradability of Maize Stems Depend on Water Status.

Water supply and valorization are two urgent issues in the utilization of maize biomass in the context of climate change and replacement of fossil resources. Maximizing maize biomass valorization is of interest to make biofuel conversion competitive, and to increase forage energetic value for animal fodder. One way to estimate biomass valorization is to quantify cell wall degradability. In this study, we evaluated the impact of water supply on cell wall degradability, cell wall contents and structure, and distribution of lignified cell types in maize internodes using dedicated high-throughput tools to effectively phenotype maize internodes from 11 inbred lines under two contrasting irrigation scenarios in field trials over three years. Overall, our results clearly showed that water deficit induced significant changes in lignin content and distribution along with a reduction in lignin p-coumaroylation, thereby impacting cell wall degradability. Additionally, we also observed that responses to a water deficit varied between the lines examined, underscoring biochemical and histological target traits for plant breeding.

Visualizing surface plasmons with photons, photoelectrons, and electrons.

Both photons and electrons may be used to excite surface plasmon polaritons, the collective charge density fluctuations at the surface of metal nanostructures. By virtue of their nanoscopic and dissipative nature, a detailed characterization of surface plasmon (SP) eigenmodes in real space-time ultimately requires joint nanometer spatial and femtosecond temporal resolution. The latter realization has driven significant developments in the past few years, aimed at interrogating both localized and propagating SP modes. In this mini-review, we briefly highlight different techniques employed by our own groups to visualize the enhanced electric fields associated with SPs. Specifically, we discuss recent hyperspectral optical microscopy, tip-enhanced Raman nano-spectroscopy, nonlinear photoemission electron microscopy, as well as correlated scanning transmission electron microscopy-electron energy loss spectroscopy measurements targeting prototypical plasmonic nanostructures and constructs. Through selected practical examples from our own laboratories, we examine the information content in multidimensional images recorded by taking advantage of each of the aforementioned techniques. In effect, we illustrate how SPs can be visualized at the ultimate limits of space and time.

[Platypnea-orthodeoxia revealed by recurrent syncope episodes]. / Platypnée-orthodéoxie révélée par des syncopes à répétition.

Platypnea-orthodeoxia is a rare clinical condition which must be examined as a differential diagnosis for any bout of faintness occurring during standing or dyspnea that is exacerbated by standing. This syndrome is often associated with a patent foramen ovale. Its physiopathology is not univocal and the association of many anatomical criteria seems to be mandatory. Contrast echocardiography confirms diagnosis and closure of the patent foramen ovale during interventional catheterization and is currently the therapeutic method of choice. After closure of the foramen ovale, clinical improvement is spectacular and durable.

C-reactive protein and hypertension.

C-reactive protein (CRP), the prototypical acute-phase reactant, is one of the most widely known biomarkers of cardiovascular disease. Circulating levels of CRP are clinically used to predict the occurrence of cardiovascular events and to aide in the selection of therapies based on more accurate risk assessment in individuals who are at intermediate risk. This paper reviews the role of CRP in hypertension. In hypertensive individuals, CRP levels associate with vascular stiffness, atherosclerosis and the development of end-organ damage and cardiovascular events. Data suggest that some anti-hypertensive medications may lower CRP levels in a manner independent of their effect on blood pressure. In individuals who are normotensive at baseline, CRP levels have been shown in multiple cohorts to foretell the development of hypertension on follow-up. Whether genetic variability that influences circulating levels of CRP independent of environmental and behavioral factors can also be used in a similar manner to predict the change in blood pressure and development of hypertension is controversial. In addition to its role as a biomarker, experimental studies have unraveled an active direct participation of CRP in the development of endothelial dysfunction, vascular stiffness and elevated blood pressure. CRP has also been implicated as a mediator of vascular remodeling in response to injury and cardiac remodeling in response to pressure overload. Emerging data may reveal novel vascular inflammatory pathways and identify new targets for treatment of vascular pathology.

Dielectric response of pentagonal defects in multilayer graphene nano-cones.

The dielectric response of pentagonal defects in multilayer graphene nano-cones has been studied by electron energy loss spectroscopy and ab initio simulations. At the cone apex, a strong modification of the dielectric response is observed below the energy of the π plasmon resonance. This is attributed to π → π* interband transitions induced by topology-specific resonant π bonding states as well as π*-σ* hybridization. It is concluded that pentagonal defects strongly affect the local electronic structure in such a way that multi-walled graphene nano-cones should show great promise as field emitters.

[Is the Allen test still useful in patients undergoing transradial cardiac coronary angiography?]. / Faut-il encore faire le test d'Allen chez les patients devant avoir une voie d'abord transradiale pour un cathétérisme cardiaque ?

The last decade has seen an increasing use of the radial artery access for coronary angiography as it combines low rates of vascular complications and early mobilization. Since its description by Campeau the percutaneous transradial access was associated with low rates of occlusion but although the incidence of ischemia is uncommon, consequences can be disastrous. That's why assessment of collateral circulation of the hand is required. Traditionally the modified Allen test was used as a tool to assess palmar arch collaterals but no consensus exists about its proper role. So the purpose of our review is to see if the modified Allen test can predict ischemic complications of the hand and if it still should be done.

Characterisation of dendritic cell subsets in lung cancer micro-environments.

The aim of the current study was to seek evidence for a correlation between mediators present in lung cancer micro-environments and subsets of dendritic cells (DCs) infiltrating these tumours. Immunohistochemistry and recently available antibodies were used to define the phenotype of DCs present in surgical biopsies from 12 patients with lung carcinomas, and the local expression of chemokines potentially involved in the recruitment of these cells was evaluated, both at mRNA and protein levels. Real-time PCR was used to analyse the expression of mRNA coding for cytokines known to influence the maturation of DCs in vitro. Different subsets of myeloid DCs were present in lung cancers, but no plasmocytoid DCs were identified. Both Langerhans cells and CD1a+/Langerin cells were interspersed among tumour cells, in numbers that were correlated to the amounts of CC chemokine ligand 20 produced in these tumours. In most specimens, DC-specific intercellular adhesion molecule-grabbing nonintegrin-positive DCs were also present at the periphery of the tumour beds. No DC-lysosomal associated membrane protein-positive DCs were identified and CD83+ DCs were rarely present in the tumour stroma. All tumours expressed interleukin (IL)-10, transforming growth factor-beta and vascular endothelial growth factor, whereas IL-12 was virtually absent. Thus, various types of dendritic cells infiltrate lung carcinomas and display an immature phenotype, presumably because of the inhibitory cytokine micro-environment.

Direct phase determination for the molecular envelope of tryptophanyl-tRNA synthetase from Bacillus stearothermophilus by X-ray contrast variation.

Monoclinic crystals of Bacillus stearothermophilus tryptophanyl-tRNA synthetase grown in the presence of substrate tryptophan (space group P2(1)) display evidence of a low-resolution trigonal space group (P321). The origin and averaging transformations for the local 32 point group of this unusually clear sixfold non-crystallographic symmetry may be inferred without prior estimation of the electron density. This local symmetry was exploited in conjunction with solvent density contrast variation to determine the shape of the molecular envelope. X-ray intensities measured from crystals equilibrated in mother liquors of three different electron densities were used to estimate three parameters for each reflection: the modulus of the envelope transform, [Gh]; and components, Xh and Yh, relative to Gh, of the structure-factor vector for the transform of intramolecular density fluctuations. The moduli ([Gh]) behave somewhat like structure-factor amplitudes from small-molecule crystals, and estimation of their unknown phases was successfully carried out by statistical direct methods. Reflections to 18 A resolution, which obey rather well the symmetry of space group P321, were merged to produce an asymmetric unit in that space group. [Gh] values for the 34 strongest of these were phased using the small-molecule direct-methods package MITHRIL [Gilmore (1984). J. Appl Cryst. 17, 42-46]. The best phase set was expanded back to the P2(1) lattice and negative density was truncated to generate initial phases for all reflections to 18 A resolution. Phase refinement by iterative imposition of the local 32 symmetry produced an envelope with convincing features consistent with known properties of the enzyme. The envelope implies that the tryptophanyl-tRNA synthetase dimer is an elongated structure with an axial ratio of about 4:1, in which the monomers have two distinct domains of unequal size. The smaller of these occurs at the dimer interface, and resembles the nucleotide binding portion of the tyrosyl-tRNA synthetase. It may therefore contain the amino-terminal one hundred or so residues, including all three cysteines, previously suggested to comprise a nucleotide-binding domain in the tryptophanyl enzyme. A purely crystallographic test of the overall features of this envelope was carried out by transporting it to a tetragonal crystal form of the same protein in which the asymmetric unit is a monomer. The small domain fits snugly inside three mercury and one gold heavy-atom binding sites for this crystal form; and symmetry-related molecules provide excellent, but very different, lattice contacts in nearly all directions.