The study of ZrCl by self-consistent band calculation

A nonrelativistic self-consistent electronic band structure calculation has been performed on zirconium monochloride using the KKR method. The exchange potential was approximated by the X..cap alpha.. method. The compound contains homoatomic layers in the sequence Cl--Zr--Zr--Cl and has the characteristics of a graphite-like two-dimensional metal. A substantial charge transfer is found toward the metallic layers and away from the loosely bonded halogen layer. There is also significant admixture of Zr-d character within the filled Cl-3p bands. The total density of states is in good agreement with the valence band photoemission results

Endomicroscopic and transcriptomic analysis of impaired barrier function and malabsorption in environmental enteropathy

Introduction: Environmental enteropathy (EE) is associated with growth failure, micronutrient malabsorption and impaired responses to oral vaccines. We set out to define cellular mechanisms of impaired barrier function in EE and explore protective mechanisms. Methods: We studied 49 adults with environmental enteropathy in Lusaka, Zambia using confocal laser endomicroscopy (CLE); histology, immunohistochemistry and mRNA sequencing of small intestinal biopsies; and correlated these with plasma lipopolysaccharide (LPS) and a zinc uptake test. Results: CLE images (median 134 for each study) showed virtually ubiquitous small intestinal damage. Epithelial defects, imaged by histology and claudin 4 immunostaining, were predominantly seen at the tips of villi and corresponded with leakage imaged in vivo by CLE. In multivariate analysis, circulating log-transformed LPS was correlated with cell shedding events (β = 0.83; P = 0.035) and with serum glucagon-like peptide-2 (β = -0.13; P = 0.007). Zinc uptake from a test dose of 25mg was attenuated in 30/47 (64%) individuals and in multivariate analysis was reduced by HIV, but positively correlated with GLP-2 (β = 2.72; P = 0.03). There was a U-shaped relationship between circulating LPS and villus surface area. Transcriptomic analysis identified 23 differentially expressed genes in severe enteropathy, including protective peptides and proteins. Conclusions: Confocal endomicroscopy, claudin 4 immunostaining and histology identify epithelial defects which are probably sites of bacterial translocation, in the presence of which increased epithelial surface area increases the burden of translocation. GLP 2 and other protective peptides may play an important role in mucosal protection in EE

A Deficiency in the Autophagy Gene Atg16L1 Enhances Resistance to Enteric Bacterial Infection

SummaryPolymorphisms in the essential autophagy gene Atg16L1 have been linked with susceptibility to Crohn’s disease, a major type of inflammatory bowel disease (IBD). Although the inability to control intestinal bacteria is thought to underlie IBD, the role of Atg16L1 during extracellular intestinal bacterial infections has not been sufficiently examined and compared to the function of other IBD susceptibility genes, such as Nod2, which encodes a cytosolic bacterial sensor. We find that Atg16L1 mutant mice are resistant to intestinal disease induced by the model bacterial pathogen Citrobacter rodentium. An Atg16L1 deficiency alters the intestinal environment to mediate an enhanced immune response that is dependent on monocytic cells, but this hyperimmune phenotype and its protective effects are lost in Atg16L1/Nod2 double-mutant mice. These results reveal an immunosuppressive function of Atg16L1 and suggest that gene variants affecting the autophagy pathway may have been evolutionarily maintained to protect against certain life-threatening infections

Determination of cercosporin (CER) phytotoxin isolated from infected peanut leaves by using adsorptive stripping square wave voltammetry

The adsorptive accumulation of cercosporin (CER) phytotoxin on glassy carbon (GC) electrodes from 1 M HClO4 aqueous solutions is used to detect and quantify the phytotoxin isolated from infected leaf tissue collected from field-grown peanut in five locations in southern regions of the Provinces of Cordoba and San Luis, Argentina. The adsorptive stripping square wave voltammetry (ASSWV) is employed to ´ perform the quantitative determination of CER in naturally infected extracts. Thin layer chromatography (TLC) and HPLC were used to verify the presence of CER in extracts. Values of Rf = 0.23 and Rf = 0.15 were determined for CER by TLC when extracts were dissolved in ethyl acetate (EA) and acetone (Ac), respectively, while a retention time of 6.13 min (Ac) was determined by HPLC. The recovery percentage of CER using ASSWV was determined by employing healthy peanut leaf tissue spiked with standard CER. The application of standard addition method was used to determine the recovery percentage as well as the CER contamination level in infected extracts. A recovery percentage of 93.27% was obtained with a relative standard deviation of 21.8% for a solution concentration of 1.04 × 10−6 mol dm−3 (n = 11). The limit of detection for a signal to noise ratio of 3:1 was about 6 ppb and the quantitation limit was about 50 ppb. The pondered relative standard deviation of 9.5% was calculated for the ASSWV method. Results found for CER contamination level in extracts through the electroanalytical method here proposed are in reasonable agreement with those values determined by using HPLC measurements.Fil: Marchiando, Nancy Cristina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Zon, María Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Fernandez, Hector. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

Nonlinear fast growth of water waves under wind forcing

In the wind-driven wave regime, the Miles mechanism gives an estimate of the growth rate of the waves under the effect of wind. We consider the case where this growth rate, normalised with respect to the frequency of the carrier wave, is of the order of the wave steepness. Using the method of multiple scales, we calculate the terms which appear in the nonlinear Schr\"odinger (NLS) equation in this regime of fast-growing waves. We define a coordinate transformation which maps the forced NLS equation into the standard NLS with constant coefficients, that has a number of known analytical soliton solutions. Among these solutions, the Peregrine and the Akhmediev solitons show an enhancement of both their lifetime and maximum amplitude which is in qualitative agreement with the results of tank experiments and numerical simulations of dispersive focusing under the action of wind.Comment: 7 pages, 4 figures, accepted in Phys. Lett.

Deciphering the complex signalling systems that regulate intestinal epithelial cell death processes and shedding

Intestinal epithelial cells play a fundamental role in maintaining homeostasis. Shedding of intestinal cells in a controlled manner is critical to maintenance of barrier function. Barrier function is maintained during this shedding process by a redistribution of tight junctional proteins to facilitate closure of the gap left by the shedding cell. However, despite the obvious importance of epithelial cell shedding to gut health a central question is how the extrusion of epithelial cells is achieved, enabling barrier integrity to be maintained in the healthy gut and restored during inflammation remains largely unanswered. Recent studies have provided evidence that excessive epithelial cell shedding and loss of epithelial barrier integrity is triggered by exposure to lipopolysaccharide (LPS) or tumour necrosis factor (TNF). Subsequent studies have provided evidence of the involvement of specific cellular components and signalling mechanisms as well as the functionality of microbiota that can be either detrimental or beneficial for intestinal barrier integrity. This review, will focus on the evidence and decipher how the signalling systems through which the mucosal immune system and microbiota can regulate epithelial cell shedding and how these mechanisms interact to preserve the viability of the epithelium

Cryptosporidium Priming Is More Effective than Vaccine for Protection against Cryptosporidiosis in a Murine Protein Malnutrition Model

Cryptosporidium is a major cause of severe diarrhea, especially in malnourished children. Using a murine model of C. parvum oocyst challenge that recapitulates clinical features of severe cryptosporidiosis during malnutrition, we interrogated the effect of protein malnutrition (PM) on primary and secondary responses to C. parvum challenge, and tested the differential ability of mucosal priming strategies to overcome the PM-induced susceptibility. We determined that while PM fundamentally alters systemic and mucosal primary immune responses to Cryptosporidium, priming with C. parvum (106 oocysts) provides robust protective immunity against re-challenge despite ongoing PM. C. parvum priming restores mucosal Th1-type effectors (CD3+CD8+CD103+ T-cells) and cytokines (IFNγ, and IL12p40) that otherwise decrease with ongoing PM. Vaccination strategies with Cryptosporidium antigens expressed in the S. Typhi vector 908htr, however, do not enhance Th1-type responses to C. parvum challenge during PM, even though vaccination strongly boosts immunity in challenged fully nourished hosts. Remote non-specific exposures to the attenuated S. Typhi vector alone or the TLR9 agonist CpG ODN-1668 can partially attenuate C. parvum severity during PM, but neither as effectively as viable C. parvum priming. We conclude that although PM interferes with basal and vaccine-boosted immune responses to C. parvum, sustained reductions in disease severity are possible through mucosal activators of host defenses, and specifically C. parvum priming can elicit impressively robust Th1-type protective immunity despite ongoing protein malnutrition. These findings add insight into potential correlates of Cryptosporidium immunity and future vaccine strategies in malnourished children

Models, measurement and inference in epithelial tissue dynamics

The majority of solid tumours arise in epithelia and therefore much research effort has gone into investigating the growth, renewal and regulation of these tissues. Here we review different mathematical and computational approaches that have been used to model epithelia. We compare different models and describe future challenges that need to be overcome in order to fully exploit new data which present, for the first time, the real possibility for detailed model validation and comparison

Engineering models for the design of long-lasting, sustainable, cost-efficient and climate-responsive pavements for Ashghal road projects in the State of Qatar

The planning, design, construction and management of modern transportation infrastructures is based on the use of continuously updated methodologies that consider, among others, the concept of sustainability. In such a context, for the specific case of road pavements, it is of crucial importance to carry out quantitative analyses based on the use of optimized engineering models. These models explicitly consider environment-pavement interactions, environmental impacts generated by all the components involved in the supply chain, and financial flows associated to pavement construction and maintenance. Such an approach is being adopted by the Public Works Authority (Ashghal) of the State of Qatar, that is developing and implementing models tailored for its infrastructure projects and local environmental conditions. This paper provides an overview of some of the employed models and methodologies that are based on the physics of pavement structures and on the assessment of environmental and economic indicators. It is shown that such an approach leads to significant improvements to current practice and to the enhanced use of recycled materials, while still guaranteeing required pavement performance