235 Cholesterol Oxidation in Intravenous Lipid Emulsions: Safety of Preparations Before and After Experimental Hyperoxia

Abstract

Background: In this study the possible presence of cholesterol oxidation products in two intravenous lipidic emulsions (ILEs) with different fatty acid compositions (LCT, MCT-LCT) has been investigated. These emulsions are currently employed in neonatal parenteral nutrition and their direct venous introduction might be potentially dangerous because of the possible atherogenic role of cholesterol oxidation products (COPs).Aims: We aimed the present study to onvestigate the possible presence of COPs in both commonly employed intravenous lipidic emulsions.Methods: The emulsions were analyzed when bottles were opened, i.e. under normal condition of administration, and after a 12 hours direct experimental exposure to air and high (90%) oxygen concentrations. 7-ketocholesterol and 5ƒÑ -epoxycholesterol were chosen as markers of direct and indirect cholesterol oxidation, respectively, and detected by Gas Chromatography-Mass Spectrometry of their trimethysilyl ethers.Results: The detected amounts of cholesterol oxidation markers were always very low and in some cases below the detection limit of the analytical method for the two COPs (0.1 and 0.3 ƒÝ g/g) of extracted lipids. When the bottles were opened (° §basic°ï conditions), in both emulsions the concentrations of 5ƒÑ -epoxycholesterol were higher than the concentrations of 7-ketocholesterol. The concentrations of the detected COPs were lower in LCT than in the MCT/LCT ILEs. The differences between air and oxygen exposure were not particularly significant although the content of the detected COPs was higher after oxygen exposure than after air exposure in both MCT/LCT and in LCT ILEs. Nevertheless, in this experimental environment (air or oxygen exposure) the concentration of 5ƒÑ -epoxycholesterol again proved to be higher than the 7-ketocholesterol concentration.Conclusion: In agreement with other authors with regards to the presence and possible intake of preformed amounts of cholesterol oxides in currently used ILEs, the results of the present study are reassuring for the safety of neonates. Samples of intravenous preparations seem to be minimally affected upon opening by the possible oxidative stress derived from industrial manufacturing. Background: Cerebral hypothermia shows promise as a neuroprotective strategy following perinatal hypoxia-ischaemia. A non-invasive technique for the quantification of regional brain temperature is urgently required to assess the cerebral effects of different cooling strategies. We aimed to test the hypothesis that thermometry by proton magnetic resonance spectroscopic imaging ( 1 H-MRSI) is as accurate as invasive monitoring during whole body hypothermia and selective head cooling.Methods: Cerebral magnetic resonance (MR) data was acquired from 6 newborn piglets using a 7 Tesla Bruker Biospec MR system. Mild whole body hypothermia was induced in 3 piglets using a thermally regulated water mattress. For each animal measurements were collected at rectal temperatures (TR) of 38Ϯ1°C and 34Ϯ1°C. Mild hypothermia was induced in 3 pigl...