Interplay of Doping and Structural Modulation in Superconducting Bi2Sr2-xLaxCuO6+d thin films

We have studied the evolution of the structural modulation in epitaxial, c-axis oriented, Bi2Sr2-xLaxCuO6+d thin films when varying the La content x and for a given x as a function of oxygen content. A series of thin films with 0<x<0.8 have been prepared in-situ by rf magnetron sputtering and characterized by R(T) measurements and RBS, TEM and X-Ray diffraction techniques. The oxygen content of each individual film was varied by thermal annealing across the phase diagram. The evolution of the structural modulation has been thoroughly studied by X-Ray diffraction in determining the variation of the amplitude of satellite reflections in special 2 axes 2theta /theta-theta scans (reciprocal space scans). It is shown that the amplitude of the modulation along the c-axis decreases strongly when x increases from 0 to 0.2. It is demonstrated that this variation is essentially governed by La content x and that changing the oxygen content by thermal treatments has a much lower influence, even becoming negligible for x>0.2. Such study is important to understand the electronical properties of Bi2Sr2-xLaxCuO6+d thin films.Comment: 25 pages with 10 figures, accepted for publication in Phys.Rev.

Structural tale of two novel (Cr, Mn)C carbides in steel

Chromium (Cr), manganese (Mn) and carbon (C) are well known alloying elements used in technologically important alloy steels and advanced high strength steels. It is known that binary CrCx and MnCx carbides can be formed in steels, but in this study we reveal for the first time that Cr and Mn were found combined in novel ternary cementite type (Cr, Mn)C carbides. Electron diffraction experiments showed that Cr, Mn and C formed two distinct carbide phases possessing orthorhombic and monoclinic crystal structures. Density functional theory calculations were performed on these phases and excellent agreement was found between calculations and experiments on the lattice parameters and relative atomic positions. The calculations showed that the combination of Mn and Cr resulted in a very high thermodynamic stability of the (Cr, Mn)C carbides, and that local structural relaxations are associated with carbon additions. Possible implications of these ternary carbides for novel applications in steel design and manufacturing are discussed

Impact of protozoan cell death on parasite-host interactions and pathogenesis

PCD in protozoan parasites has emerged as a fascinating field of parasite biology. This not only relates to the underlying mechanisms and their evolutionary implications but also to the impact on the parasite-host interactions within mammalian hosts and arthropod vectors. During recent years, common functions of apoptosis and autophagy in protozoa and during parasitic infections have emerged. Here, we review how distinct cell death pathways in Trypanosoma, Leishmania, Plasmodium or Toxoplasma may contribute to regulation of parasite cell densities in vectors and mammalian hosts, to differentiation of parasites, to stress responses, and to modulation of the host immunity. The examples provided indicate crucial roles of PCD in parasite biology. The existence of PCD pathways in these organisms and the identification as being critical for parasite biology and parasite-host interactions could serve as a basis for developing new anti-parasitic drugs that take advantage of these pathways

Macrophage Depletion in Hypertensive Rats Accelerates Development of Cardiomyopathy

Inflammation contributes to the process of ventricular remodeling after acute myocardial injury. To investigate the role of macrophages in the chronic process of cardiac remodeling, they were selectively depleted by intravenous administration of liposomal clodronate in heart failure-prone hypertensive Ren-2 rats from the age of 7 until 13 weeks. plain liposomes were used for comparison. Liposomal clodronate treatment reduced the number of blood monocytes and decreased the number of macrophages in the myocardium. Compared to plain liposomes, liposomal clodronate treatment rapidly worsened left ventricular ejection function in hypertensive rats. Liposomal clodronate-treated Ren-2 rat hearts showed areas of myocyte loss with abundant inflammatory cell infiltration, predominantly comprising CD4 positive T lymphocytes. The current-study showed that lack of macrophages vas associated with earlier development of myocardial dysfunction in hypertensive rats. Modulation of macrophage function may be of value in the evolution of cardiomyopath

Efficient Capture of Infected Neutrophils by Dendritic Cells in the Skin Inhibits the Early Anti-Leishmania Response

Neutrophils and dendritic cells (DCs) converge at localized sites of acute inflammation in the skin following pathogen deposition by the bites of arthropod vectors or by needle injection. Prior studies in mice have shown that neutrophils are the predominant recruited and infected cells during the earliest stage of Leishmania major infection in the skin, and that neutrophil depletion promotes host resistance to sand fly transmitted infection. How the massive influx of neutrophils aimed at wound repair and sterilization might modulate the function of DCs in the skin has not been previously addressed. The infected neutrophils recovered from the skin expressed elevated apoptotic markers compared to uninfected neutrophils, and were preferentially captured by dermal DCs when injected back into the mouse ear dermis. Following challenge with L. major directly, the majority of the infected DCs recovered from the skin at 24 hr stained positive for neutrophil markers, indicating that they acquired their parasites via uptake of infected neutrophils. When infected, dermal DCs were recovered from neutrophil depleted mice, their expression of activation markers was markedly enhanced, as was their capacity to present Leishmania antigens ex vivo. Neutrophil depletion also enhanced the priming of L. major specific CD4+ T cells in vivo. The findings suggest that following their rapid uptake by neutrophils in the skin, L. major exploits the immunosuppressive effects associated with the apoptotic cell clearance function of DCs to inhibit the development of acquired resistance until the acute neutrophilic response is resolved

Supine MRI for regional breast radiotherapy: Imaging axillary lymph nodes before and after sentinel-node biopsy

Regional radiotherapy (RT) is increasingly used in breast cancer treatment. Conventionally, computed tomography (CT) is performed for RT planning. Lymph node (LN) target levels are delineated according to anatomical boundaries. Magnetic resonance imaging (MRI) could enable individual LN delineation. The purpose was to evaluate the applicability of MRI for LN detection in supine treatment position, before and after sentinel-node biopsy (SNB). Twenty-three female breast cancer patients (cTis-3N0M0) underwent 1.5 T MRI, before and after SNB, in addition to CT. Endurance for MRI was monitored. Axillary levels were delineated. LNs were identified and delineated on MRI from before and after SNB, and on CT, and compared by Wilcoxon signed-rank tests. LN locations and LN-based volumes were related to axillary delineations and associated volumes. Although postoperative effects were visible, LN numbers on postoperative MRI (median 26 LNs) were highly reproducible compared to preoperative MRI when adding excised sentinel nodes, and higher than on CT (median 11, p < 0.001). LN-based volumes were considerably smaller than respective axillary levels. Supine MRI of LNs is feasible and reproducible before and after SNB. This may lead to more accurate RT target definition compared to CT, with potentially lower toxicity. With the MRI techniques described here, initiation of novel MRI-guided RT strategies aiming at individual LNs could be possible

The influence of the accessory genome on bacterial pathogen evolution

Bacterial pathogens exhibit significant variation in their genomic content of virulence factors. This reflects the abundance of strategies pathogens evolved to infect host organisms by suppressing host immunity. Molecular arms-races have been a strong driving force for the evolution of pathogenicity, with pathogens often encoding overlapping or redundant functions, such as type III protein secretion effectors and hosts encoding ever more sophisticated immune systems. The pathogens’ frequent exposure to other microbes, either in their host or in the environment, provides opportunities for the acquisition or interchange of mobile genetic elements. These DNA elements accessorise the core genome and can play major roles in shaping genome structure and altering the complement of virulence factors. Here, we review the different mobile genetic elements focusing on the more recent discoveries and highlighting their role in shaping bacterial pathogen evolution