Background: Preterm infants need high amounts of calcium and phosphorus for bone mineralization, which is difficult to obtain with parenteral feeding due to the low solubility of these salts. The objective of this study was to evaluate the physicochemical compatibility of high concentrations of calcium associated with organic phosphate and its influence on the stability of AIO admixtures for neonatal use.

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ObjectiveThe present study aimed to evaluate the influence of the relative composition of trace elements and vitamins in physicochemical stability of neonatal parenteral nutrition.Material and methodsThree formulations for neonatal administration were selected; the main variable was the presence of trace elements and vitamins. The analyses where carried out immediately after preparation and at 24 h, 48 h, 72 h and 7 days after preparation. Three methods were selected to determine globule size: light obscuration, dynamic light scattering and optical microscopy. Complementary evaluation including visual inspection, determination of pH and osmolarity, peroxide levels and measurements of zeta potential were also performed.ResultsThere was an observable alteration in color and phase separation in the PN stored at 25°C and 40°C. Neither globule size pattern, nor any other physicochemical characteristic evaluated appeared to be considerably altered in any of the analyzed formulations even after 7 days of storage at 5°C. Globule size in all the PN studied was consistent with the established limit, below 500 nm by DLS measurement, and PFAT5 was below 0.05% under all storage temperatures.ConclusionConcomitant presence of trace elements and vitamins in the same neonatal formulation did not alter the evaluated aspects of stability.

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Lipoproteins are responsible for the general transport of lipids in the body via the circulation. Their primary role is to deliver triglycerides (TG), stored in the lipoprotein core to adipose and muscle tissue. This TG is hydrolysed by the action of lipoprotein lipase (LPL) in the tissues. and the released fatty acids are normally taken up by the cells of these tissues. This enzyme is catalytically active against TG-rich lipoproteins such as chylomicrons and very low density lipoproteins (VLDL). After hydrolysis, lipoprotein composition changes, becoming TG-poor, smaller and more dense. These lipoproteins, called low density lipoprotein (LDL) and remnants, are then taken out of the circulation primarily by the liver. High density lipoproteins (HDL) are also associated with the breakdown of TG-rich lipoproteins and contains little TG. These TGpoor lipoproteins are important in the excretion of unwanted lipids, mainly cholesterol, and other lipophilic substances.It is important to maintain the right lipoprotein balance since accumulation can occur in the body and diseases such as hyperlipidemia and atherosclerosis could develop [ 11. Additionally, there is evidence suggesting that modifications in lipid uptake and metabolism can influence a whole range of other pathologies such as diabetes, obesity, inflammatory conditions and even could be relevant in cancer [2].LPL IS a key enzyme in lipoprotein metabolism but can also be a factor in the retention and accumulation of LDL [I]. To separate these two functions it is thus important to be able to measure and understand how each lipoprotein is hydrolysed by LPL. Here we have used a continuous fluorescence displacement assay to study this hydrolysis. The assay monitors the release of long chain fatty acids from natural substrates and has been used previously to measure LPL activity [3].Human lipoproteins isolated from normolipemic healthy volunteers by differential gradient centrifugation, were used as substrate in this assay. Triglyceride concentrations in the samples were determined by a method previously described [4]. The enzyme assay (Iml) contained 0.1 M tris-HCI, 0.1 M NaCI, 1 FM 1 1 -(dansylamino)undecanoic acid (DAUDA), 0 5 nmol TG / ml lipoprotein sample and 8pg of fatty acid binding protein (FABP). To this cocktrul lOOng of LPL was added. The initial rate of enzyme activity was measured by monitoring fluorescence drop with time using a Hitachi F2000 fluorimeter. Extent of hydrolysis was assessed for up to 240s when the reaction plateaued. The assay was carried out at 37°C and assayed in triplicate. The system was calibrated by additions of known amounts of oleic acid (OA) [3]. Lipoprotein lipase show differential activity against the different lipoproteins used as substrate (Figure 1). Blank 100 -. -_ I _ x LDL -HDL 0 Chylo 60 LL n c 40 1 '\___ VLDL H 20 I 0 50 100 150 2 Time (s) 0.0 0.2 s 0 0 0.4 -! ? 0.6 f n 0.8 1 .o I Figure 1 Time deoendent hvdrolvsis of different liuooroteins bv LPL.Results are representative values of three identical measurements and a...