Nutrition-based health: cell-based bioassays for food antioxidant activity evaluation

Food science has progressively evolved and now there are wide evidences that foods have biological activities that are beyond their classical nutritional value. In this field, the antioxidant activity of pure compounds, food, feed, and dietary supplements has been extensively studied and numerous analytical approaches and assay models have been developed, involving various systems from simple chemical assays to animal models and human studies. This article is an overview of different cell-based models that have been used for testing the antioxidant properties of food, feed, and dietary supplements. Advantages, drawbacks, and technical problems to develop and validate suitable, robust, and high-throughput cell-based bioassays for screening food antioxidant activity will be discussed.     

Towards biomimetic models of the reduced [FeFe]-hydrogenase that preserve the key structural features of the enzyme active site; a DFT investigation

[FeFe]-hydrogenases are the most efficient biological catalysts available for the H₂ evolution reaction. Their active site – the H-cluster – features a diiron subsite which has the peculiar characteristic of bearing cyanide groups hydrogen-bonded to the apoprotein as well as carbonyl ligands. Notably, one of the CO ligands is disposed in bridging position between the metal centers. This allows one of the Fe ions to retain a square pyramidal coordination – which determines the assumption of the so-called “rotated structure” – with a vacant coordination site in trans to the μ-CO group, ready to bind protons when the active site is in the Fe^IFe^I state. Many Fe^IFe^I biomimetic models have been synthesized and characterized so far, but most of them fail to reproduce the orientation of the diatomic ligands that is observed in the enzyme active site.     

How small the contacts could be optimal for nanoscale organic transistors?

We report on a study seeking an optimized contact configuration for organic transistors that minimizes contact effects but maintains smallest contact size. We begin with the bulk access resistance in staggered transistors which results from the charge transport through the organic semiconductor film. Bulk access resistance is an intrinsic contributor to the contact resistance which has been little understood due to lack of a reliable study tool. In this work, we utilize the inner transported power inside the semiconductor film as a medium to investigate the contact resistance and the relevant contact effects. We examine the influences of the organic film thickness (t_SC), the channel length (L), the underlying charge transport and various organic semiconductor materials with variable carrier mobility. A roughly optimal contact length (L_C) of L_C0 ≈ 6t_SC is obtained. The results reveal that besides the device architecture the underlying charge transport should be also taken into account in designing organic transistors for practical application.     

Potential Mechanisms Linking Atherosclerosis and Increased Cardiovascular Risk in COPD: Focus On Sirtuins

The development of atherosclerosis is a multi-step process, at least in part controlled by the vascular endothelium function. Observations in humans and experimental models of atherosclerosis have identified monocyte recruitment as an early event in atherogenesis. Chronic inflammation is associated with ageing and its related diseases (e.g., atherosclerosis and chronic obstructive pulmonary disease). Recently it has been discovered that Sirtuins (NAD⁺-dependent deacetylases) represent a pivotal regulator of longevity and health. They appear to have a prominent role in vascular biology and regulate aspects of age-dependent atherosclerosis. Many studies demonstrate that SIRT1 exhibits anti-inflammatory properties in vitro (e.g., fatty acid-induced inflammation), in vivo (e.g., atherosclerosis, sustainment of normal immune function in knock-out mice) and in clinical studies (e.g., patients with chronic obstructive pulmonary disease). Because of a significant reduction of SIRT1 in rodent lungs exposed to cigarette smoke and in lungs of patients with chronic obstructive pulmonary disease (COPD), activation of SIRT1 may be a potential target for chronic obstructive pulmonary disease therapy. We review the inflammatory mechanisms involved in COPD-CVD coexistence and the potential role of SIRT1 in the regulation of these systems.     

Fat globule membranes in ewes' milk: The main enzyme activities during lactation

A trial was carried out on seven Massese ewes, from which individual milk samples were taken during lactation. All the enzyme activities investigated (oxidase activity of xanthine oxidoreductase, gamma-glutamyltranspeptidase, alkaline phosphatase and 5′-nucleotidase) were affected by the lactation phase, with the exception of the dehydrogenase activity of xanthine oxidoreductase (XOR). A higher oxidase activity (XO) of XOR was found when the diameter of milk fat globules was smaller. In addition, the absence of XO in colostrum led to the hypothesis that its antibacterial role is independent of its activity. The increase in alkaline phosphatase activity during lactation requires further research to better define the criteria for pasteurised sheep milk.     

An IR molding system for direct shaping of thermoplastics

A new molding technique is proposed to directly mold small parts from thermoplastic pellets. A small molding machine was designed and fabricated: the mold consisted of a transparent glass and a metallic frame; an infrared (IR) lamp provided the heat for the pellet melting. Molding tests were carried out by using three commercial thermoplastics and two metallic molds. Molding time and IR lamp power were changed to extract a moldability window for each combination of material and metallic mold. In the best process conditions, a high quality of the samples was obtained in terms of mold filling and surface aesthetics. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Novel Heterogenized Palladium(II) Complexes Anchored to Polymer Matrices Functionalized with Bis(diphenylphosphino)methane Moieties

The synthesis and structural characterization of a novel bidentate ligand such as bis(diphenylphosphino) methane bound to a cross-linked styrene/divinylbenzene resin and to linear poly(styrene) are reported. Moreover, the anchoring of palladium acetate to the above polymeric ligands is described and the structure of the heterogenized palladium(II) complexes obtained is proposed.     

Detection of antibody classes and subpopulations in myasthenia gravis patients using a new nonradioactive enzyme immunoassay

To investigate the presence of antibodies in myasthenia gravis (MG) patients, we have developed a new reproducible and sensitive enzyme immunoassay (EIA-AChR), in which a beta subunit-specific monoclonal antibody (mAb 73) immobilizes fetal calf acetylcholine receptors (AChRs). We tested 92 MG patients (42 with positive and 50 with negative antibody titers), 60 healthy controls, and 40 controls with other autoimmune diseases. EIA-AChR detected immunoglobulin G (IgG) titers in all of the seropositive samples, with a significant correlation between these and those obtained using the traditional immunoprecipitation method. Moreover, 5 seronegative patients at immunoprecipitation assay were positive at EIA-AChR. EIA-AChR was also useful in revealing: (1) a seropositive patient subpopulation with generalized MG who had Abs directed against alpha-Bungarotoxin binding sites; and (2) patients with IgM directed against fetal calf AChR (detected in 13 seronegative and 16 seropositive MG patients, and in 6 of the patients with other autoimmune diseases).     

Analytical models of subthreshold swing and threshold voltage forthin- and ultra-thin-film SOI MOSFETs

Analytical models are proposed for thin- and ultra-thin film silicon-on-insulator (SOI) MOSFETs operating in weak or strong inversion. The models take into account all the device parameters. The cases of two and three interfaces with a silicon substrate are considered in the modeling and compared with one another. These models give the main electrical MOSFET parameters in ohmic operation (subthreshold swing and threshold voltage) for these structures. The basic approximation is the consideration of a linearly varying potential in the Si film, which has been inferred on the basis of numerical simulations. Various behaviors depending on the Si film and the buried insulator thickness as well as the interface charges, Si film doping, or substrate regime are simulated to assess the properties and the performances of SOI MOS transistors and to validate the analytical models     

A new hot carrier degradation law for MOSFET lifetime prediction

We propose in this paper a new hot carrier degradation law for a reliable MOSFET lifetime prediction. We show that the proposed exponential function can describe all kind of curve concavity (saturating or non-saturating shapes) and can fit very well with the experimental data for the whole duration of the stress. Finally, it gives a more accurate lifetime value as compared to previous modelings because it accounts for the concavity of the saturating degradation law.