New biomimetic constructs for improved in vivo circulation of superparamagnetic nanoparticles

Superparamagnetic iron oxide nanoparticles (SPIOs) have been produced and used as a potent and versatile contrast media for magnetic resonance imaging (MRI). Despite a number of efforts to improve their surface chemistry and biocompatibility, the SPIOs half life in blood circulation is very short and they are rapidly taken up by the reticuloendothelial system (RES). In this paper we describe a new method that permits to avoid the rapid clearance of SPIOs. Nanoparticles are made biocompatible by encapsulation into autologous red blood cells. These biomimetic constructs preserve the main properties of the cells that escape RES clearance as well as the properties of the nanoparticles that perform even better than in blood suspension with reduced T2*. These SPIO-loaded RBCs are promising intravascular imaging contrast agents and could also be addressed to selected body compartments by an external magnetic field.     

NO2 adsorption behaviour on LaFeO3 electrodes of YSZ-based non-nernstian electrochemical sensors

X-ray photoelectron spectroscopy (XPS) was used to examine the NO₂ adsorption behaviour on the LaFeO₃ and Pt electrodes of planar yttria stabilized zirconia non-Nernstian gas sensors. The electrochemical sensors were exposed to the same gas atmosphere containing 1000 ppm NO₂ at 650°C. XPS of the as-prepared sensors and sensors after exposure to NO₂ revealed bonded nitrogen peaks on the surface of the semiconducting oxide but no nitrogen peaks on the Pt electrode. Therefore, NO₂ adsorption on a LaFeO₃ electrode plays an important role in the NO₂ detection mechanism.     

Carcinogenesis of Pancreatic Adenocarcinoma: Precursor Lesions

Pancreatic adenocarcinoma displays a variety of molecular changes that evolve exponentially with time and lead cancer cells not only to survive, but also to invade the surrounding tissues and metastasise to distant sites. These changes include: genetic alterations in oncogenes and cancer suppressor genes; changes in the cell cycle and pathways leading to apoptosis; and also changes in epithelial to mesenchymal transition. The most common alterations involve the epidermal growth factor receptor (EGFR) gene, the HER2 gene, and the K-ras gene. In particular, the loss of function of tumor-suppressor genes has been documented in this tumor, especially in CDKN2a, p53, DPC4 and BRCA2 genes. However, other molecular events involved in pancreatic adenocarcinoma pathogenesis contribute to its development and maintenance, specifically epigenetic events. In fact, key tumor suppressors that are well established to play a role in pancreatic adenocarcinoma may be altered through hypermethylation, and oncogenes can be upregulated secondary to permissive histone modifications. Indeed, factors involved in tumor invasiveness can be aberrantly expressed through dysregulated microRNAs. This review summarizes current knowledge of pancreatic carcinogenesis from its initiation within a normal cell until the time that it has disseminated to distant organs. In this scenario, highlighting these molecular alterations could provide new clinical tools for early diagnosis and new effective therapies for this malignancy.     

Risk of salmonellosis from consumption of almonds in the North American market

Salmonellosis outbreaks from consumption of raw almonds in 2001 and 2004 led to regulations that require mandatory treatment of almonds sold in North America to give a minimum 4-log reduction of Salmonella. This study aims to: 1) assess the risk of salmonellosis associated with almond consumption in North America, with current treatments in effect; 2) determine the resilience of the current production system to increases in prevalence or concentration of Salmonella on almonds; 3) assess the impact of treating less than 100% of the crop; and 4) investigate conditions that could explain the number of cases associated with the 2001 outbreak. Risk was assessed using a Monte Carlo simulation, based on an established dose–response relationship. Data for almond amounts sold, Salmonella prevalence and concentration on almonds, storage time and temperature at different handling steps, population reductions during storage at various temperatures and with different treatments, and consumer handling were based on data from published sources and almond industry or academic expert opinion. What-if scenarios were evaluated for Salmonella prevalence varying from 1 to 65%, concentrations of Salmonella varying from 1 to 120 MPN/100 g, and portions of untreated crop varying from 0 to 10%. The estimated incidence of salmonellosis in North America from almonds as currently treated is on average 0.008 cases per billion servings (with an estimated 6.6 billion servings consumed annually). Increases in Salmonella prevalence to 25%, mean concentrations above 25 MPN/100 g, or leaving 0.05% of the crop untreated all resulted in an arithmetic mean risk greater than 1 case/year (with geometric means remaining below 1 case/year for all variables). Assuming 4000 kg at a prevalence of 65% (observed in recalled lots) and an average concentration of 120 MPN/100 g in raw almonds (back calculated from levels in recalled almonds) predicted over the 2800 cases estimated for the 2001 outbreak. Applying a 4-log reduction to these almonds reduced the average number of predicted cases to less than a single case. The current regulation is effective in maintaining the risk of salmonellosis from consumption of almonds below an arithmetic mean of 1 case/year, although significant increases in either prevalence or concentration, or small increases in proportion of untreated almonds would frequently lead to exceeding this threshold.     

Design and characterization of fenretinide containing organogels

The stable, transparent, organogels, which are prepared by adding a minute amount of water to a solution of lecithin in biocompatible oil, are here studied as matrices for solubilization and percutaneous delivery of fenretinide (4 hydroxypropyl phenyl retinamide, 4HPR), a retinoic acid derivative. The influence of different types of oil, content of water and presence of hyaluronic acid was studied on gel properties. Rheology studies were carried out in order to detect the effect of these variables on gel viscosity. 4HPR diffusion from the different organogels was determined by in vitro Franz cell.It was found that diffusion coefficients (J_n) of 4HPR incorporated in organogels are about five fold lower than J_n of 4HPR in organic solution.Stability and shelf life stability studies demonstrate that 4HPR incorporated in organogels does not degrade and that organogels maintain 90% of 4HPR stability for periods up to 4 months.     

What type of information displayed on digital scheduling software facilitates reflective planning tasks for students? Contributions to the design of a school task management tool

To facilitate an efficient homework planning strategy, scheduling software tools should take students’ needs into consideration, in order to provide information that is useful for planning homework and that minimizes cognitive load.     

Learning methods for melanoma recognition

Melanoma is the most deadly skin cancer. Early diagnosis is a challenge for clinicians. Current algorithms for skin lesions' classification focus mostly on segmentation and feature extraction. This article instead puts the emphasis on the learning process, testing the recognition performance of three different classifiers: support vector machine (SVM), artificial neural network and k‐nearest neighbor. Extensive experiments were run on a database of more than 5000 dermoscopy images. The obtained results show that the SVM approach outperforms the other methods reaching an average recognition rate of 82.5% comparable with those obtained by skilled clinicians. If confirmed, our data suggest that this method may improve classification results of a computer‐assisted diagnosis of melanoma. © 2010 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 20, 316–322, 2010     

Hot vs. cold water steeping of different teas: Do they affect antioxidant activity?

A new popular way of making tea, especially in Taiwan, is to steep leaves in cold water. Here we investigate whether antioxidant activity of teas may be affected by hot or cold water steeping and if this correlates with their polyphenol content and metal-chelating activity. A set of five loose tea samples, consisting of unblended and blended teas, was analysed following their infusion in either hot water (90 °C, 7 min) or cold water (room temperature, 2 h). Antioxidant activity, measured as hydrogen-donating ability, using the ABTS· and DMPD assays, showed no significant differences among hot or cold teas, except in the case of white tea, where significantly higher values were obtained after cold water steeping, a recurrent finding in this study. The antioxidant activity of the teas correlates well with their total phenolic content and metal-chelating activity. Cold teas were, however, generally better inhibitors of in vitro LDL conjugated diene formation and of loss in tryptophan fluorescence. The results of this study contribute to gaining further knowledge on how the potential health benefits of this popular beverage may be maximised by the different methods of preparation.     

A survey of applications of second-order sliding mode control to mechanical systems

The effective application of sliding mode control to mechanical systems is not straightforward because of the sensitivity of these systems to chattering. Higher-order sliding modes can counteract this phenomenon by confining the switching control to the higher derivatives of the mechanical control variable, so that the latter results are continuous. Generally, this approach requires the availability of a number of time derivatives of the sliding variable, and, in the presence of noise, this requirement could be a practical limitation. A class of second-order sliding mode controllers, guaranteeing finite-time convergence for systems with relative degree two between the sliding variable and the switching control, could be helpful both in reducing the number of differentiator stages in the controller and in dealing with unmodelled actuator dynamics. In this paper different second-order sliding mode controllers, previously presented in the literature, are shown to belong to the above cited class, and some challenging control problems involving mechanical systems are addressed and solved. Simulations and experimental results are provided throughout the paper.     

Cell proliferation’ differentiation’ and apoptosis are modified by n−3 polyunsaturated fatty acids in normal colonic mucosa

Supplementation with low doses of eicosapentaenoic (EPA) or docosahexaenoic (DHA) acid was used here to investigate changes in epithelial proliferation’ differentiation’ and apoptosis in normal rat colonic mucosa. ACI/T rats received by oral administration low doses of purified EPA or DHA ethyl esters (1g/kg body weight) and colonic mucosa was analyzed for cell proliferation’ differentiation’ and apoptosis. n−3 Polyunsaturated fatty acid incorporation into membrane phospholipids was investigated as reflections of fatty acid metabolism. Both EPA and DHA suppressed colonocyle proliferation and increased the numbers of differentiating and apoptotic cells without modification of the crypt morphology and the number of cells per crypt columns. A significant incorporation of the supplemented fatty acids into total phospholipids was observed. This enrichment was accompanied by a decreased content in arachidonic acid. The observation that EPA and DHA do not alter crypt morphology although they modify cell turnover in normal colonic mucosa suggests a possible use of these fatty acids as dietary chemopreventive agents.