Irritable bowel syndrome and gluten-related disorders

Background: Irritable bowel syndrome (IBS) is frequently associated with celiac disease (CD) and nonceliac gluten/wheat sensitivity (NCGS/NCWS), but epidemiological and pathophysiological aspects are still unclear. Furthermore, a gluten-free diet (GFD) can positively influence IBS symptoms. Methods: A comprehensive online search for IBS related to CD, NCGS and GFD was made using the Pubmed, Medline and Cochrane databases. Results: Although a systematic screening for CD in IBS is not recommended, CD prevalence can be increased in diarrhea-predominant IBS patients. On the other hand, IBS symptoms can be persistent in treated CD patients, and their prevalence tends to decrease on a GFD. IBS symptoms may overlap and be similar to those associated to nonceliac gluten and/or wheat sensitivity. Increased gut permeability could explain the gluten/wheat effects in IBS patients. Finally, a GFD could improve symptoms in a subgroup of IBS patients. Conclusions: The possible interplay between IBS and gluten-related disorders represents a scientifically and clinically challenging issue. Further studies are needed to confirm these data and better clarify the involved pathophysiological mechanisms

Whole genome sequencing and prediction of antimicrobial susceptibilities in non-tuberculous mycobacteria

Non-tuberculous mycobacteria (NTM) are opportunistic pathogens commonly causing chronic, pulmonary disease which is notoriously hard to treat. Current treatment for NTM infections involves at least three active drugs (including one macrolide: clarithromycin or azithromycin) over 12 months or longer. At present there are limited phenotypic in vitro drug susceptibility testing options for NTM which are standardised globally. As seen with tuberculosis, whole genome sequencing has the potential to transform drug susceptibility testing in NTM, by utilising a genotypic approach. The Comprehensive Resistance Prediction for Tuberculosis is a database used to predict Mycobacterium tuberculosis resistance: at present there are no similar databases available to accurately predict NTM resistance. Recent studies have shown concordance between phenotypic and genotypic NTM resistance results. To benefit from the advantages of whole genome sequencing, further advances in resistance prediction need to take place, as well as there being better information on novel drug mutations and an understanding of the impact of whole genome sequencing on NTM treatment outcomes

Gastroparesis: New insights into an old disease

Gastroparesis (Gp) is a chronic disease characterized by a delayed gastric emptying in the absence of mechanical obstruction. Although this condition has been reported in the literature since the mid-1900s, only recently has there been renewed clinical and scientific interest in this disease, which has a potentially great impact on the quality of life. The aim of this review is to explore the pathophysiological, diagnostic and therapeutical aspects of Gp according to the most recent evidence. A comprehensive online search for Gp was carried out using MEDLINE and EMBASE. Gp is the result of neuromuscular abnormalities of the gastric motor function. There is evidence that patients with idiopathic and diabetic Gp may display a reduction in nitrergic inhibitory neurons and in interstitial cells of Cajal and/or telocytes. As regards diagnostic approach, 99-Technetium scintigraphy is currently considered to be the gold standard for Gp. Its limits are a lack of standardization and a mild risk of radiation exposure. The C13 breath testing is a valid and safe alternative method. 13C acid octanoic and the 13C Spirulina platensis recently approved by the Food and Drug Administration are the most commonly used diagnostic kits. The wireless motility capsule is a promising technique, but its use is limited by costs and scarce availability in many countries. Finally, therapeutic strategies are related to the clinical severity of Gp. In mild and moderate Gp, dietary modification and prokinetic agents are generally sufficient. Metoclopramide is the only drug approved by the Food and Drug Administration for Gp. However, other older and new prokinetics and antiemetics can be considered. As a second-line therapy, tricyclic antidepressants and cannabinoids have been proposed. In severe cases the normal nutritional approach can be compromised and artificial nutrition may be needed. In drug-unresponsive Gp patients some alternative strategies (endoscopic, electric stimulation or surgery) are available

SINTESI E PROPRIETÀ MECCANICHE DI LEGHE AMORFE A BASE Mg.

Le leghe amorfe a base Mg hanno suscitato un crescente interesse a causa della elevata resistenza alla corrosione e degli alti carichi di snervamento, proprietà migliorate rispetto alle corrispettive leghe cristalline. In questa ottica vengono analizzati sistemi ternari del tipo Mg-TM-RE (con TM = metallo di transizione quale Cu, Ni; RE = Y e terra rara quale Gd, Nd) a causa dell'ampio intervallo di amorfizzazione che mostrano queste composizioni. Obiettivo di questo lavoro è la sintesi e la caratterizzazione di leghe amorfe con differenti composizioni all'interno di sistemi semplici (Mg-Cu e Mg-Cu-Y) ponendo particolare attenzione alle proprietà meccaniche. Campioni amorfi di Mg87Cu13, Mg85Cu15, Mg80Cu20, Mg75Cu25, Mg65Cu25Y10 sono stati ottenuti in forma di nastro tramite melt spinning. La loro struttura è stata controllata utilizzando la diffrazione di raggi X. La stabilità della fase amorfa è stata studiata tramite calorimetria DSC, mettendo in risalto la presenza per alcune composizioni binarie di una temperatura di transizione vetrosa. La composizione Mg65Cu25Y10 è risultata eutettica ad una analisi metallografica (con temperatura di fusione di 463°C). Sono state inoltre effettuate sintesi di leghe multicomponenti (Mg51Ni11Cu13Zn4Y5Ag7Gd9 e Mg60Ni9Cu9Zn5Y6Ag5Gd6) per cui è stata verificata la migliorata tendenza alla amorfizzazione rispetto ai sistemi semplici e l'aumento della stabilità della fase amorfa. Sui campioni amorfi sono state effettuate delle misure di durezza Vickers ottenendo 2.94 GPa per la lega Mg65Cu25Y10 e valori simili per le leghe multicomponenti (3.10 GPa per le lega Mg51Ni11Cu13Zn4Y5Ag7Gd9 e 2.84 GPa per le lega Mg60Ni9Cu9Zn5Y6Ag5Gd6)

Raman spectra and vibrational analysis of CsPbI3: a fast and reliable technique to identify lead halide perovskite polymorphs

A major issue in the development of Lead halide perovskites is the assessment of the crystal structure of the samples, due to their typically limited time-stability, and the understanding of the role of external factors that can induce a crystal phase transformation (such as humidity, intense light flux, temperature, etc.). In this perspective, it is of utmost importance to have at disposal a fast and reliable experimental tool able to give an immediate indication of the polymorph of the sample with the possibility to integrate in-situ measurements for constant monitoring. In this paper we propose Raman spectroscopy as the ideal technique to solve this problem. The vibrational analysis of CsPbI3 in the α-phase and δ-phase and of the Cs4PbI6 secondary phase is reported and all the vibrational modes are assigned by comparing experimental spectra of the phases to Raman modes calculated within the DFT framework. Finally, the mechanism of laser induced phase degradation was studied using in-situ Raman measurements providing new insights on the secondary phase generated during the process

Honey bees increase social distancing when facing the ectoparasite Varroa destructor

Social distancing in response to infectious diseases is a strategy exhibited by human and nonhuman animals to counteract the spread of pathogens and/or parasites. Honey bee (Apis mellifera) colonies are ideal models to study this behavior because of the compartmentalized structure of these societies, evolved under exposure to parasite pressure and the need to ensure efficient functioning. Here, by using a combination of spatial and behavioral approaches, we investigated whether the presence of the ectoparasite mite Varroa destructor induces changes in the social organization of A. mellifera colonies that could reduce the spread of the parasite. Our results demonstrated that honey bees react to the intrusion of V. destructor by modifying space use and social interactions to increase the social distancing between young (nurses) and old (foragers) cohorts of bees. These findings strongly suggest a behavioral strategy not previously reported in honey bees to limit the intracolony parasite transmission

Formation mechanisms and phase stability of solid-state grown cspbi3 perovskites

CsPbI3 inorganic perovskite is synthesized by a solvent-free, solid-state reaction, and its structural and optical properties can be deeply investigated using a multi-technique approach. X-ray Diffraction (XRD) and Raman measurements, optical absorption, steady-time and time-resolved luminescence, as well as High-Resolution Transmission Electron Microscopy (HRTEM) imaging, were exploited to understand phase evolution as a function of synthesis time length. Nanoparticles with multiple, well-defined crystalline domains of different crystalline phases were observed, usually surrounded by a thin, amorphous/out-of-axis shell. By increasing the synthesis time length, in addition to the pure α phase, which was rapidly converted into the δ phase at room temperature, a secondary phase, Cs4PbI6, was observed, together with the 715 nm-emitting γ phase

Electronic and optical properties of LiBC

LiBC, a semiconducting ternary borocarbide constituted of the lightest elements only, has been synthesized and characterized by x-ray powder diffraction, dielectric spectroscopy, and conductivity measurements. Utilizing an infrared microscope the phonon spectrum has been investigated in single crystals. The in-plane B-C stretching mode has been detected at 150 meV, noticeably higher than in AlB2, a non-superconducting isostructural analog of MgB2. It is this stretching mode, which reveals a strong electron-phonon coupling in MgB2, driving it into a superconducting state below 40 K, and is believed to mediate predicted high-temperature superconductivity in hole-doped LiBC [H. Rosner, A. Kitaigorodsky, and W. E. Pickett, Phys. Rev. Lett. 88, 127001 (2002)].Comment: 4 pages, 4 figure

Theoretical evidences for enhanced superconducting transition temperature of CaSi2_2 in a high-pressure AlB2_2 phase

By means of first-principles calculations, we studied stable lattice structures and estimated superconducting transition temperature of CaSi$_2$ at high pressure. Our simulation showed stability of the AlB$_2$ structure in a pressure range above 17 GPa. In this structure, doubly degenerated optical phonon modes, in which the neighboring silicon atoms oscillate alternately in a silicon plane, show prominently strong interaction with the conduction electrons. In addition there exists a softened optical mode (out-of-plan motion of silicon atoms), whose strength of the electron-phonon interaction is nearly the same as the above mode. The density of states at the Fermi level in the AlB$_2$ structure is higher than that in the trigonal structure. These findings and the estimation of the transition temperature strongly suggest that higher $T_{\rm c}$ is expected in the AlB$_2$ structure than the trigonal structures which are known so far.Comment: 6 pages and 11 figure