Preservation of myocyte contractile function after hypothermic, hyperkalemic cardioplegic arrest with 2, 3-butanedione monoxime

One proposed contributory mechanism for depressed ventricular performance after hypothermic, hyperkalemic cardioplegic arrest is a reduction in myocyte contractile function caused by alterations in intracellular calcium homeostasis. Because 2,3-butanedione monoxime decreases intracellular calcium transients, this study tested the hypothesis that 2,3-butanedione monoxime supplementation of the hyperkalemic cardioplegic solution could preserve isolated myocyte contractile function after hypothermic, hyperkalemic cardioplegic arrest. Myocytes were isolated from the left ventricles of six pigs. Magnitude and velocity of myocyte shortening were measured after 2 hours of incubation under normothermic conditions (37 degrees C, standard medium), hypothermic, hyperkalemic cardioplegic arrest (4 degrees C in Ringer's solution with 20 mEq potassium chloride and 20 mmol/L 2,3-butanedione monoxime). Because beta-adrenergic agonists are commonly employed after cardioplegic arrest, myocyte contractile function was examined in the presence of the beta-agonist isoproterenol (25 nmol/L). Hypothermic, hyperkalemic cardioplegic arrest and rewarming reduced the velocity (32%) and percentage of myocyte shortening (27%, p < 0.05). Supplementation with 2,3 butanedione monoxime normalized myocyte contractile function after hypothermic, hyperkalemic cardioplegic arrest. Although beta-adrenergic stimulation significantly increased myocyte contractile function under normothermic conditions and after hypothermic, hyperkalemic cardioplegic arrest, contractile function of myocytes exposed to beta-agonist after hypothermic, hyperkalemic cardioplegic arrest remained significantly reduced relative to the normothermic control group. Supplementation with 2,3-butanedione monoxime restored beta-adrenergic responsiveness of myocytes after hypothermic, hyperkalemic cardioplegic arrest. Thus, supplementation of a hyperkalemic cardioplegic solution with 2,3-butanedione monoxime had direct and beneficial effects on myocyte contractile function and beta-adrenergic responsiveness after cardioplegic arrest. A potential mechanism for the effects of 2,3-butanedione monoxime includes modulation of intracellular calcium transients or alterations in sensitivity to calcium. Supplementation with 2,3-butanedione monoxime may have clinical utility in improving myocardial contractile function after hypothermic, hyperkalemic cardioplegic arrest.     

Output feedback control based on a high-order sliding manifold approach

In this note, we address the problem of output feedback control of multiple-input-multiple-output plants. The proposed approach is based on a high-order sliding manifold strategy. The resulting controller exhibits strong robustness properties, similar to high-gain control laws, but avoids peaking phenomena, thanks to the adoption of a time-varying sliding surface. Moreover, the dynamic control law is continuous and differentiable, thus avoiding chattering problems.     

Self-nucleation of isotactic poly(1-butene) in the trigonal modification

Isotactic poly(1-butene) (i-PBu) is a polyolefin of industrial relevance which exhibits an interesting polymorphism. Upon cooling from the relaxed melt at atmospheric pressure, a tetragonal phase (Form II) develops. However, being metastable, this structure slowly evolves upon aging in the stable trigonal modification (Form I). Another trigonal modification, denoted Form I′, can also crystallize directly from the melt if proper conditions are met, e.g., high pressure, low tacticity, ultrathin samples etc. In this work, we aim to verify whether, by acting on the nucleation stage via a proper thermal history, the direct formation of the trigonal polymorph from the melt in a bulk sample is possible. Nucleation of i-PBu has been tailored by means of the self-nucleation technique, imposed on previously aged samples (Form I). DSC and temperature-resolved WAXS show that different crystallization pathways can be observed, depending on the residual concentration of Form I self-nuclei. With decreasing self-nucleation temperature we first encounter “cross-nucleation” of the tetragonal crystal on trigonal nuclei, followed by concomitant crystallization of Form II and Form I′ and eventually the sole formation of the trigonal modification (Form I′).     

Exploitation of the Antibacterial Properties of Photoactivated Curcumin as ‘Green’ Tool for Food Preservation

In the search for non-chemical and green methods to counteract the bacterial contamination of foods, the use of natural substances with antimicrobial properties and light irradiation at proper light waves has been extensively investigated. In particular, the combination of both techniques, called photodynamic inactivation (PDI), is based on the fact that some natural substances act as photosensitizers, i.e., produce bioactive effects under irradiation. Notably, curcumin is a potent natural antibacterial and effective photosensitizer that is able to induce photodynamic activation in the visible light range (specifically for blue light). Some practical applications have been investigated with particular reference to food preservation from bacterial contaminants.     

New Insights in the Control of Fat Homeostasis: The Role of Neurotensin

Neurotensin (NT) is a small peptide with pleiotropic functions, exerting its primary actions by controlling food intake and energy balance. The first evidence of an involvement of NT in metabolism came from studies on the central nervous system and brain circuits, where NT acts as a neurotransmitter, producing different effects in relation to the specific region involved. Moreover, newer interesting chapters on peripheral NT and metabolism have emerged since the first studies on the NT-mediated regulation of gut lipid absorption and fat homeostasis. Intriguingly, NT enhances fat absorption from the gut lumen in the presence of food with a high fat content, and this action may explain the strong association between high circulating levels of pro-NT, the NT stable precursor, and the increased incidence of metabolic disorders, cardiovascular diseases, and cancer observed in large population studies. This review aims to provide a synthetic overview of the main regulatory effects of NT on several biological pathways, particularly those involving energy balance, and will focus on new evidence on the role of NT in controlling fat homeostasis, thus influencing the risk of unfavorable cardio–metabolic outcomes and overall mortality in humans.     

Deep Resequencing of 9 Candidate Genes Identifies a Role for ARAP1 and IGF2BP2 in Modulating Insulin Secretion Adjusted for Insulin Resistance in Obese Southern Europeans

Type 2 diabetes is characterized by impairment in insulin secretion, with an established genetic contribution. We aimed to evaluate common and low-frequency (1–5%) variants in nine genes strongly associated with insulin secretion by targeted sequencing in subjects selected from the extremes of insulin release measured by the disposition index. Collapsing data by gene and/or function, the association between disposition index and nonsense variants were significant, also after adjustment for confounding factors (OR = 0.25, 95% CI = 0.11–0.59, p = 0.001). Evaluating variants individually, three novel variants in ARAP1, IGF2BP2 and GCK, out of eight reaching significance singularly, remained associated after adjustment. Constructing a genetic risk model combining the effects of the three variants, only carriers of the ARAP1 and IGF2BP2 variants were significantly associated with a reduced probability to be in the lower, worst, extreme of insulin secretion (OR = 0.223, 95% CI = 0.105–0.473, p < 0.001). Observing a high number of normal glucose tolerance between carriers, a regression posthoc analysis was performed. Carriers of genetic risk model variants had higher probability to be normoglycemic, also after adjustment (OR = 2.411, 95% CI = 1.136–5.116, p = 0.022). Thus, in our southern European cohort, nonsense variants in all nine candidate genes showed association with better insulin secretion adjusted for insulin resistance, and we established the role of ARAP1 and IGF2BP2 in modulating insulin secretion.     

Contingency management for smoking cessation in adolescent smokers.

This pilot study evaluated the use of contingency management (CM) procedures in combination with cognitive-behavioral therapy (CBT) for smoking cessation in adolescents. Twenty-eight treatment-seeking adolescent smokers participated in a 1-month, school-based smoking cessation program and were randomly assigned to receive either CM with weekly CBT or CBT alone. In the CM+CBT group, biochemical verification of abstinence was obtained twice daily during the first 2 weeks, followed by daily appointments during the 3rd week and once every other day during the 4th week. Participants were monetarily reinforced for abstinence on an escalating magnitude schedule with a reset contingency. At the end of 1 week and 1 month of treatment, abstinence verified using quantitative urine cotinine levels was higher in participants in the CM+CBT group (1 week: 76.7%; 1 month: 53.0%) when compared with the CBT-alone group (1 week: 7.2%; 4 weeks: 0%). These preliminary results provide a strong initial signal supporting the utility of CM techniques for smoking cessation in adolescents and demonstrate the feasibility of implementing such a program in a school setting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Distance perception of vehicle rear lights in fog

Perceptual difficulty is one of the main explanations given for the behavioral modifications and high accident rate associated with driving in fog. The present study investigates how fog and the characteristics of vehicle rear lights affect distance perception. Two experiments in a fog chamber (meteorological visibility range of 5-15 m) were run under conditions simulating nighttime fog. The participants gave verbal estimates of the distance (8-28 m) of vehicles simulated by rear-light arrangements. The results revealed an average increase of 60% in the perceived distance of vehicles in fog as compared with normal visibility conditions. Distance overestimation was particularly pronounced when the vehicle had only 1 fog light instead of 2 and when the lights were close together. No effect of light height was observed. These results suggest that the perception of vehicle distance in nighttime fog could be significantly improved by the presence of 2 lights with maximal spacing. Actual or potential applications of this research include vehicle rear light design.     

Free vibration analysis of reinforced thin-walled plates and shells through various finite element models

Abstract

This article deals with free vibration analysis of thin-walled structures reinforced by longitudinal stiffeners using refined one-dimensional (1D) models.The 1D theory, which is used in the present article, has hierarchical features and it is based on the Carrera Unified Formulation (CUF). The displacement field over the cross section is obtained by means of Taylor (TE) or Lagrange (LE) expansions. Finite element (FE) method is applied along the beam axis to obtain weak form solutions of the related governing equations. The obtained results are compared with those from classical finite element formulations based on plate and shell (2D), beam (1D), and solid (3D) elements that are available in commercial software. When solid formulation is used to build the FE solutions, stringers and skin are modeled with only 3D elements while, in the 2D-1D FE models, shell and beam elements are used for skin and stringers, respectively. Three benchmark problems are analyzed: a flat plate, a curved panel, and a thin-walled cylinder. When TE models are used, different orders of expansion, N, are considered, where N is a free parameter of the formulation. As far as Lagrange expansions are concerned, four-node (LE 4) and nine-node (LE 9) elements are used to build different meshes on the cross section. The results show that the present 1D models are able to analyze the dynamic behavior of complex structures and can detect 3D effects as well as very complex shell-like modes typical of thin-walled structures. Moreover, the 1D-CUF elements yield accurate results with a low number of degrees of freedom.     

Polymeric fluorine-free electrolyte for application in DMFC

We present latest results on the development of a new solid electrolyte for DMFC application. Films are obtained through fluorine-free chemistry consisting of grafting reaction between polyethylene film, preliminary irradiated, and styrene monomers. This reaction proceeds through the formation of hydroperoxide groups activated by ferrous catalyst that initiates the polymerization reaction with styrene. Sulfonic groups are then introduced on the aromatic rings by sulfonation with chlorosulfonic acid. Functional properties of membranes are then characterized out of cell through ion conductivity and methanol permeability measurements. Obtained results are very promising for application in DMFC.