117,410 research outputs found
Fractal dimension in mass spectra from herbal extracts: Hypothesis for a new method of phytocomplex characterization
No full textIn order to optimize the quality control of phytochemical products, we propose a non-conventional method of analysis of complex systems, called fractal analysis, applied to ESI (Electrospray Ionisation) mass spectra. The ESI spectra obtained with phytochemical commercial products (Mattoli et al., J. Mass Spectrom. 41: 1534, 2006; Mattoli et al., Metabolomics 7:437, 2011) were submitted to fractal analysis using the “box counting” method. Subsequent cluster analysis permitted to determine a distinctive fractal dimension (DB) for single plant extracts, as well as for mixtures of plant extracts contained in commercial herbal products. On several replicates obtained with different batches, DB tended to display a normal distribution around a mean value, which might be suggested as a typical reference tag for that product. The fractal approach permitted to characterize the repeatability of the instrumental measure too. Changes in DB following thermal treatment of samples, to simulate ageing, indicated the ability of the method also to identify appropriate conditions of storage and to suggest stability control interventions. In conclusion, evaluation of mass spectra DB might be proposed as a new promising technique to be used as a summary measurement of the complexity of the overall composition of a phytochemical product
Electrically responsive photonic crystals: A review
No full textTunable photonic crystals (TPCs) represent an important class of intelligent materials, which can be used as optically active components and as functional technology to change an object's colour. Among these smart structures, electrically responsive photonic crystals are the most promising for real technological applications. Up to now, to transform the electrical stimulus into an optical response several strategies have been adopted that can be classified into (1) electrochemical processes, (2) reorientation of liquid crystal molecules, (3) electrophoretic organization of colloidal suspension and (4) indirect electrically induced modification of the photonic structures. In this review article, these approaches are systematically summarized and analysed with a particular emphasis on the chemistry of materials
Bronchial epithelium and asthma.
No full textThe bronchial epithelium has a number of mechanical functions, including mucociliary clearance and protection against noxious agents. It may also modulate the function of the underlying smooth muscle by metabolism and regulation of mediators and the production of relaxant or constrictor substances, and regulate the activation and differentiation of lymphocytes and mast cells by releasing chemotactic factors and cytokines. It is possible that epithelial structural and functional abnormalities may lead via several mechanisms to increased bronchial responsiveness in asthmatic subjects
The pseudoactive site as a tool for indirect drug design. Application to inhibitors of kynurenine-3-hydroxylase
No full textNanoscaffolds for guided cardiac repair: the new therapeutic challenge of regenerative medicine
No full textCardiovascular diseases represent the leading cause of death and disability in the world. At the end-stage of heart failure, heart transplantation remains the ultimate option. Therefore, due to the numerous drawbacks associated with this procedure, new alternative strategies to repair the wounded heart are required. Cell therapy is a potential option to regenerate functional myocardial tissue. The characteristics of the ideal cardiac cell therapy include the use of the proper cell type and delivery methods as well as the choice of a suitable biomaterial acting as a cellular vehicle. Since traditional delivery methods are characterized by several counter backs, among which low cell survival, new engineered micro- and nanostructured materials are today extensively studied to provide a good cardiac therapy. In this review, we report the most recent achievements in the field of cell therapy for myocardial infarction treatment and heart regeneration, focusing on the most commonly used cell sources, the traditional approaches used to deliver cells at the damaged site, and a series of novel technologies based on recent advancements of bioengineering, highlighting the tremendous potential that nanoscaffolds have in this framework
Micro-wrinkled palladium surface for hydrogen sensing and switched detection of lower flammability limit
No full textWe report the development and testing of a novel hydrogen sensor that shows a very peculiar response to hydrogen exposure, due to its micro-structured palladium surface. The fabrication of the wrinkled Pd surface is obtained using an innovative, fast and cheap technique based on the deposition of a thin Pd film on to a thermo-retractable polystyrene sheet that shrinks to 40% of its original size when heated. The buckling of the Pd surface induced by shrinking of the substrate produces nano and micro-wrinkles on the sensor surface. The micro-structured sensor surface is very stable even after repeated hydrogen sorption/desorption cycles. The hydrogen sensing mechanism is based on the transitory absorption of hydrogen atoms into the Pd layer, leading to the reversible change of its electrical resistance. Interestingly, depending on hydrogen concentration the proposed sensor shows the concurrent effect of both the usually described behaviors of increase or decrease of resistance, related to different phenomena occurring upon hydrogen exposure and formation of palladium hydride. The study reports and discusses evidences for an activation threshold of hydrogen concentration in air switching the behavior of sensor performances from, e.g., poor negative to large positive sensitivity and from slow to fast detection. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights
Non-allergic factors of bronchial asthma
No full textThe functional characteristic of all forms of asthma is the airway hyperresponsiveness to several stimuli. Airway hyperresponsiveness is always present in current asthmatics and can be also documented in some subjects during the symptom-free periods. The mechanisms of the spontaneous or induced increases of airway hyperresponsiveness are probably different from those responsible for stable airway hyperresponsiveness. The transitory increases in airway hyperresponsiveness are associated with an acute inflammatory response of the bronchial mucosa, whereas airway inflammation is not a constant finding in subjects with stable airway hyperresponsiveness. The mechanisms involved in the latter condition might be a functional and/or structural derangement of bronchial epithelium, a functional or structural alteration of airway smooth muscle or alteration in the function of the autonomic nervous system
New frontiers in pharmaceutical analysis: A metabolomic approach to check batch compliance of complex products based on natural substances
No full textAbstractNatural substances, particularly medicinal plants and their extracts, are still today intended as source for new Active Pharmaceutical Ingredients (APIs). Alternatively they can be validly employed to prepare medicines, food supplements or medical devices. The most adopted analytical approach used to verify quality of natural substances like medicinal plants is based still today on the traditional quantitative determination of marker compounds and/or active ingredients, besides the acquisition of a fingerprint by TLC, NIR, HPLC, GC.Here a new analytical approach based on untargeted metabolomic fingerprinting by means of Mass Spectrometry (MS) to verify the quality of grinTuss adulti syrup, a complex products based on medicinal plants, is proposed. Recently, untargeted metabolomic has been successfully applied to assess quality of natural substances, plant extracts, as well as corresponding formulated products, being the complexity a resource but not necessarily a limit. The untargeted metabolomic fingerprinting includes the monitoring of the main constituents, giving weighted relevance to the most abundant ones, but also considering minor components, that might be notable in view of an integrated – often synergistic – effect on the biological system.Two different years of production were investigated. The collected samples were analyzed by Flow Injection ElectroSpray Ionization Mass Spectrometry Analysis (FIA-ESI-MS) and a suitable data processing procedure was developed to transform the MS spectra into robust fingerprints. Multivariate Statistical Process Control (MSPC) was applied in order to obtain multivariate control charts that were validated to prove the effectiveness of the proposed method
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