Solution combustion synthesis of Mo-Fe/MgO: Influence of the fuel composition on the production of doped catalyst nanopowder

Among the techniques for producing oxide catalysts, the solution combustion synthesis (SCS) has been widely used to produce high-quality nanostructured powders at low-cost. Through SCS, due to the high exothermic energy liberated by the reaction between the transition metal nitrate and the fuel, it is possible to homogeneously incorporate dopant ions into the catalyst. Besides, SCS allows the production of nanopowders with sizes in the decimal scale, which is extremely important for powdered catalysts. The smaller the particle is, the larger the surface area is. Based on these possibilities, the aim of this work is to produce Fe-Mo/MgO nanopowders by SCS. The influence of concentration and composition of the fuels glycine and polyethylene glycol (PEG) on the final product were investigated. The morphology and the physicochemical properties were characterized by X-ray diffraction (XRD), electron microscopy (SEM), granulometry and surface area analysis. The results indicated high crystallinity for the samples produced with PEG and a wide variation on the nanoparticles sizes depending on the fuel properties.

Cleaning oil paintings: NMR relaxometry and SPME to evaluate the effects of green solvents and innovative green gels

NMR relaxometry together with SPME allow evaluation of the effects of new green gels for the cleaning of paintings.

Abstract P3-06-05: Not presented

This abstract was not presented at the symposium.

Correlation between in vivo stresses and oxidation of UHMWPE in total hip arthroplasty

The possibility of in vivo, stress-induced oxidation in orthopaedic UHMWPE has been investigated. EtO sterilised, uncrosslinked UHMWPE liners, explanted or shelf-aged, have been collected. Linear wear and wear rate were assessed and FTIR spectroscopy was employed to detect oxidation and to build up oxidation products spatial maps across the liners section. Oxidation profiles have been compared to stress distribution profiles, resulting from a FE analysis conducted on the same liners geometries and couplings. It was found that oxidised and stressed areas followed the same asymmetrical, localized distribution profile. It was therefore possible to establish a correlation between stressed areas and observed oxidation.

Inhibition of acyl-CoA: cholesterol acyltransferase decreases apolipoprotein B-100-containing lipoprotein secretion from HepG2 cells

There is evidence that the overproduction of apoB-100-containing lipoproteins by the liver is the underlying event in some forms of dyslipoproteinemia. This metabolic status is associated to an increased risk of developing premature coronary artery disease CAD. The conclusions from previous studies suggested that the availability to the hepatocytes of cholesterol that is readily esterified is an important determinant for VLDL and LDL secretion. In the present study, we set out to investigate the effect of the specific stimulation and inhibition of the rate-limiting enzyme of the cholesterol esterification, acyl-CoA:cholesterol acyltransferase (ACAT, E.C. 2.3.1.26), on the lipid and on the apoB-100 secretion rate from a human hepatoma cell line (HepG2). When the specific ACAT inhibitor FCE 27677 (10-5 M) was added to the cultures, a decrease of the cellular cholesteryl ester content and at the same time a significant reduction of the neutral lipids and of the apoB-100 secretion rate were noticed. The stimulation of ACAT by 25-hydroxycholesterol (20 microgram/ml) caused a 4-fold increase of the cellular cholesteryl ester content and a 2-fold increase of the lipoprotein secretion rate. FCE 27677 (10-5 M to 10-7 M) prevented the effects elicited by the oxysterol. On the contrary, lovastatin (10-6 M) and gemfibrozil (10-6 M) had no effect. The analysis of the lipid and of the apolipoprotein composition of the lipoproteins secreted in the medium revealed that ACAT inhibition had the dual effect of both decreasing the number of apoB-100-containing lipoproteins secreted as well as their cholesteryl ester load. Altogether, these data support the idea of a close relationship between ACAT activation, leading to increased cholesteryl ester availability, and apoB-100-containing lipoprotein secretion. It is speculated that ACAT inhibitors may prove useful for the treatment of human dyslipoproteinemias caused by the hepatic overproduction of apoB-100-containing lipoproteins.

FCE 27677: a novel inhibitor of acyl-CoA: cholesterol acyltransferase with potent oral hypolipidemic activity

FCE 27677 ([(-)N-[2,6-bis(1-methylethyl)phenyl]-N'-[(4R,5R)-2- (4-dimethylaminophenyl)-4,5 dimethyl-dioxolan-2-yl]methylurea) is a new systemically available ACAT inhibitor belonging to the class of ketalic disubstituted ureas. When tested in microsomes from rabbit intestine, aorta and liver, it inhibited the enzyme with IC50 of 9.31, 6.99 and 92.2 nM, respectively. It had no effect on plasma LCAT and intestinal cytosolic cholesterol esterases and, when tested in a tissue culture system, it did not interfere with the synthesis of cholesterol, triglycerides, and phospholipids. Enzyme inhibition kinetics indicated that FCE 27677 is a non-competitive inhibitor of the enzyme with respect to acylCoA and to cholesterol. When administered mixed to a 1.5% cholesterol and 0.5% sodium cholate-enriched diet to rats, it prevented the development of hypercholesterolemia with ED50 of 0.35 mg kg-1 day-1. Given in a single oral dose to hypercholesterolemic rats it significantly reduced both the plasma lipid levels and the hepatic cholesteryl ester content within 6 h from gavage. VLDL and LDL levels and composition were also significantly affected. Similar effects were observed when the drug was given mixed to a regular chow diet for 4 weeks to hypercholesterolemic rabbits. These results are consistent with the idea that systemically available ACAT inhibitors can affect the composition and the metabolism of the atherogenic cholesteryl ester-rich VLDL and LDL. ACAT inhibitors appear promising for the correction of dyslipoproteinemias secondary to lipoprotein overproduction, and in reducing the atherogenic index of apoB-100 containing lipoproteins.

Oxidatively modified HDLs are potent inhibitors of cholesterol biosynthesis in human skin fibroblasts

Several biological properties of lipoproteins are modified by oxidative reactions. Modified lipoproteins are rapidly degraded by macrophages, and this is likely to be a major pathway for the formation of foam cells in the early phases of atherosclerosis. The effect of modification on other aspects of cholesterol homeostasis has, however, received lesser attention. In this study, the influence of copper ion- as well as rat aortic smooth muscle cell-oxidation-modified high density lipoprotein (HDL) on cholesterol biosynthesis in human skin fibroblasts has been investigated. Modified lipoproteins eluted at higher ionic strength than did control HDL on a Mono-Q 5/5 anion-exchange column. However, only copper ion-modified HDLs displayed greater electrophoretic mobility than did control lipoproteins on agarose gel electrophoresis. Both control and modified HDLs decreased cholesterol esterification in fibroblasts. On the other hand, whereas control HDLs were virtually ineffective in modulating cholesterol biosynthesis, modified HDLs had a significant suppressing effect. This was observed in normal as well as low density lipoprotein (LDL) receptor-defective fibroblasts, which are unresponsive to the LDL-mediated downregulation of cholesterol synthesis. These results are consistent with the concept that oxidative modification of HDLs drastically alters their effect on cholesterol homeostasis in fibroblasts. The data furthermore suggest the existence of a lipoprotein pathway for cholesterol biosynthesis regulation that is independent of the LDL receptor-mediated pathway. Downregulation of cholesterol biosynthesis would be a new function for oxidatively modified lipoproteins.