1,721,142 research outputs found
Regression of atherosclerosis and platelet stabilization: Therapeutic objectives to confront
No full textAtherosclerosis is a systemic disease where atheromatous plaque is the basic lesion. A number of studies have shown that atherosclerotic lesions progress over time, when risk factors such as arterial hypertension and hyperlipidemia are present. Many clinical trials have been conducted in the last decade, both with antihypertensive and lipid-lowering drugs. These trials demonstrated that progression of atherosclerosis can be halted and even regression can be achieved. In studies with lipid-lowering drugs, the best results were achieved with a dramatic decrease in LDL cholesterol levels, obtained with statins, particularly when combined with a concomitant increase in HDL cholesterol. The treatment of hypertension provided better results on the endpoint atheromatous plaque with antihypertensive drugs belonging to the class of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers or calcium antagonists. Some studies were conducted both with antihypertensive and lipid-lowering drugs, and a better control of lesion progression, together with its partial regression, was obtained. The best approach seems to be achieved with the combination of a specific intervention on lipid profile together with a targeted control of blood pressure. © 2009 AIM Publishing Srl
Adhesion, mobility and aggregation of nanoclusters at surfaces: Ni and Ag on Si, HOPG and graphene
Full text linkAbstract: An experimental investigation of Ag and Ni nanoparticles (NPs) deposited on Silicon with its native oxide, on highly oriented pyrolytic graphite and on graphene flakes is reported. The NPs were physically synthesized with a magnetron based gas aggregation source and the produced beam was mass-filtered and deposited in vacuum on the substrates. The study was concentrated on the morphology for the different cases, shedding some light on the interaction of pre-formed NPs with surfaces, a crucial aspect both of technological and scientific relevance. The nature of adhesion can be strongly influenced by the intrinsic properties of the surface (like for instance the energetics of interaction between the NP surface atoms and the first layers of the substrate) and/or the extrinsic properties, like the presence of defects, step edges, impurities and other irregularities. After adhesion, the NPs mobility and their mutual interaction are very relevant. In this work, the study was concentrated on NP/surface morphology, by using atomic force microscopy, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Article highlights: Morphology of physically synthesized metal Nano-Particles (NPs) on Si, HOPG and Graphene was investigated. The NPs were pure Ag and Ni. Coalescence, diffusion and self-aggregation and preferential adhesion were observed, with possible applications in sensor technology.Possible explanations are: NP softness, NP/surface bonding interaction and presence of contaminant species molecules between NP
Growth of epitaxial Yb silicide on Si(100) studied by metastable atom deexcitation spectroscopy and photemission
Full text linkFilms of different Yb thickness are deposited on Si(100) 2x1 and are annealed at increasing high temperature. The evolution of the valence-band electronic properties is followed with metastable deexcitation spectroscopy and photoemission. Different surface-structure phases are observed at progressively high annealing temperature. A 3x1 ordered phase is observed by low-energy electron diffraction (LEED) after annealing of the films at about 640 degreesC and it is associated to the formation of a stable silicide. Correspondingly, electronic states assigned to the Yb 6s-5d hybridized band and to Si 3s and 3p bands in the compound are observed. A further increase of the annealing temperature causes the system to evolve rapidly. At T>650 degreesC the LEED pattern shows a 3x2 periodicity. Above 700 degreesC, the films present a character similar to that of the Si substrate.Films of different Yb thickness are deposited on (formula presented) and are annealed at increasing high temperature. The evolution of the valence-band electronic properties is followed with metastable deexcitation spectroscopy and photoemission. Different surface-structure phases are observed at progressively high annealing temperature. A (formula presented) ordered phase is observed by low-energy electron diffraction (LEED) after annealing of the films at about 640 °C and it is associated to the formation of a stable silicide. Correspondingly, electronic states assigned to the Yb (formula presented) hybridized band and to Si (formula presented) and (formula presented) bands in the compound are observed. A further increase of the annealing temperature causes the system to evolve rapidly. At (formula presented) the LEED pattern shows a (formula presented) periodicity. Above 700 °C, the films present a character similar to that of the Si substrate. © 2002 The American Physical Society
A Randomized, Double-Blinded, Placebo-Controlled, Clinical Study of the Effects of a Nutraceutical Combination (LEVELIP DUO ®) on LDL Cholesterol Levels and Lipid Pattern in Subjects with Sub-Optimal Blood Cholesterol Levels (NATCOL Study)
Full text linkPhytosterols and red yeast rice are largely studied cholesterol-lowering nutraceuticals, respectively inhibiting the bowel absorption and liver synthesis of cholesterol. Our aim was to test the effect of combined nutraceutical-containing phytosterols and red yeast rice vs. a placebo on the lipid profile. We performed a parallel arms, double-blind, placebo-controlled clinical trial, randomizing 88 moderately hypercholesterolemic subjects to treatment with a combined nutraceutical containing phytosterols (800 mg) and red yeast rice, standardized to contain 5 mg of monacolins from Monascus purpureus, with added niacin (27 mg) and policosanols (10 mg) (LEVELIP DUO®), or placebo. The mean LDL-Cholesterol (LDL-C) change at Week 8 was -32.5 ± 30.2 mg/dL (-19.8%) in the combined nutraceutical group and 2.5 ± 19.4 mg/dL (2.3%) in the placebo group. The estimated between-group difference of -39.2 mg/dL (95% CI: -48.6; -29.8) indicates a statistically significant difference between treatments in favor of the combined nutraceutical (p < 0.0001). Total Cholesterol (TC), non-HDL cholesterol (non-HDL-C), Apolipoprotein B, TC/HDL-C and LDL-C/HDL-C improved in a similar way in the combined nutraceutical group only. No significant changes in other clinical and laboratory parameters were observed. In conclusion, the tested combined nutraceutical was well tolerated, while significantly reducing the plasma levels of LDL-C, TC, non-HDL-C, ApoB, TC/HDL-C and LDL-C/HDL-C ratios in mildly hypercholesterolemic patient
Structure properties of nanostructured Fe films grown on c(2x2)N/Cu(100) self organised surface
No full textThe growth of Fe on the c(2x2)N/Cu(100) surface was studied with XAFS assisted by LEED. Previous STM work had shown that atomic N on Cu(100) forms periodic arrays of c(2x2) N islands with a size of about 5x5 nm channelling the growth of Fe onto the clean Cu areas. From XAFS multishell analysis we describe the growth in terms of fcc phase with strong lattice distortion, deviation from the layer by layer growth, and presence of surface complex phases, some with different geometry. The differences between the Fe growth on the clean and N saturated Cu(100) surface are explained in terms of Fe-N atoms interaction, and we could obtain the adsorption geometry of Fe on N-saturated surface
Is the 2020 Sampson equation the best formula for LDL-C estimation?
No full textMore than 4 million deaths in Europe are caused by cardiovascular disease (CVD) each year. Low-density lipoprotein-cholesterol (LDLC) has been demonstrated to be one of the major eterminants of atherogenesis and CVD burden, resulting the most important modifiable risk factor for CVD prevention strategies. According to the last European Guidelines, both direct and indirect assessment of LDL-C can be used in clinical practice. However, the direct measurement techniques are time consuming, expensive, not fully standardized, and not worldwide available. Thus, the most used method for LDL-C quantification continues to be the 1972 old, landmark Friedewald formula (FF): LDL-C = Total cholesterol – High-Density Lipoprotein cholesterol (HDL-C) – riglycerides/5. FF is based on the two assumptions that, in chylomicron absence, most plasma TG are contained in triglyceride-rich Very-Low Density Lipoproteins (VLDL), and the ratio of TG mass to that of VLDL is relatively constant and roughly equal to 5:1 in normal subjects as well as patients with all types of hyperlipoproteinemia, excluding the rare Type III. FF results in reasonably
approximated LDL-C estimations, however it suffers from some limitations: it is not applicable for patient with chylomicronemia, overestimates LDL-C values in patients with Type III ypercholesterolemia
and leads to LDL-C underestimation in patients with plasma TG ≥ 400
mg/dl [3,4]. Moreover, LDL-C underestimation has also been reported
for subjects with low TG levels [5]. For this reason, different research
groups have developed new equations for LDL-C estimation during the
last decades [6–8]. Although promising, the efficacy and potential
clinical role of these new formulae have not been thoroughly validated
and while one formula should be preferred to another is still being
debatin
Plasmonic properties and stability of Au and Cu nanoparticles embedded in cerium oxide
Full text linkWith the aim of sensitizing cerium oxide—a very important catalytic material—to visible light, its coupling with Au and Cu nanoparticles is investigated. The samples are grown by physical synthesis by embedding a layer of nanoparticles between two cerium oxide films. The films are controlled in composition by in-situ x-ray photoemission spectroscopy and in morphology by ex-situ scanning electron microscopy. The optical properties as a function of the oxide thickness, investigated by spectrophotometry in the UV-Vis range, are interpreted based on the results of the morphological characterization and of simulations based on the Maxwell Garnett model. The stability of chemical and optical properties after air exposure is also investigated. The results, indicating that stable materials with tuneable optical properties can be obtained, are important in view of the potential application of the investigated systems in photocatalysis
Mapping the local stoichiometry in Cu nanoparticles during controlled oxidation by STEM-EELS spectral imaging
Full text linkCopper nanoparticles (NPs) can be coupled with cuprous oxide, combining photoelectrocatalytic properties with a broad-range optical absorption. In the present study, we aimed to correlate changes in morphology, electronic structure and plasmonic properties of Cu NPs at different stages of oxidation. We demonstrated the ability to monitor the oxidation of NPs at the nanometric level using STEM-EELS spectral maps, which were analyzed with machine learning algorithms. The oxidation process was explored by exposing Cu NPs to air plasma, revealing systematic changes in their morphology and composition. Initial plasma exposure created a Cu2O shell, while prolonged exposure resulted in hollow structures with a CuO shell. This study identified procedures to obtain a material with Cu2O surface stoichiometry and absorption extended into the near-infrared range. Moreover, this study introduced a novel application of machine learning clustering techniques to analyze the morphological and chemical evolution of a nanostructured sample
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