Comparison of the physicochemical properties of MCT-containing fat emulsions in total nutrient admixtures.
ABSTRACT The physical stability of two types of MCT-emulsions made by different technologies - physical mixture vs. structured lipids - was studied as a function of storage time and temperature. Particle size analysis, zeta potential and dynamic surface tension measurements were carried out to evaluate the possible changes in the kinetic stability of the emulsions. Our results indicate that the physical mixture technology of MCT-emulsions resulted in impaired physicochemical stability compared to the ones containing structured triglycerides. In the case of structured lipids, both medium and long chain fatty acids can be found in one triglyceride molecule, leading to a favorable interfacial location of structured triglycerides. Besides the advantageous metabolic effects of structured triglycerides, their application is recommended to improve the physical stability of TPN admixtures.
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ABSTRACT: Parenteral nutrition-a form of administering nutrients, electrolytes, trace elements, vitamins, and water-is a widely used mode of therapy applied in many diseases, in patients of different ages both at home and in hospital. The success of nutritional therapy depends chiefly on proper determination of the patient's energetic and electrolytic needs as well as preparation and administration of a safe nutritional mixture. As a parenterally administered drug, it is expected to be microbiologically and physicochemically stable, with all of the components compatible with each other. It is very difficult to obtain a stable nutritional mixture due to the fact that it is a complex, two-phase drug. Also, the risk of incompatibility between mixture components and packaging should be taken into consideration and possibly eliminated. Since parenteral nutrition is a part of therapy, simultaneous use of drugs may cause pharmacokinetic and pharmacodynamic interactions as well as those with the pharmaceutical phase. The aim of this paper is to discuss such aspects of parenteral nutrition as mixture stability, methodology, and methods for determining the stability of nutritional mixtures and drugs added to them.The Scientific World Journal 12/2013; 2013:415310. · 1.73 Impact Factor
Conference Paper: Ray tracing on the electron optical bench[Show abstract] [Hide abstract]
ABSTRACT: In the design of electrostatic lenses, a rapid and reliable method of determining electron trajectories is required. This paper describes a demountable vacuum system incorporating an electron gun, deflection plates, clyindrical lenses and a pair of phosphor coated mesh structures. The various parts are assembled on heavy bases which rest on precision ground and graduated glass rods. A vacuum sealed push-rod permits adjusting the relative positions of the lenses during testing. The electron beam passes through the parallel phosphor coated meshes and the lighted spots are observed by means of a cathodometer to determine beam landing angle. The complete device thus provides a tool for measuring not only the effects of changing the potentials of electrostatic lens elements but of changing their relative positions as well during a single test. The complete system is called an "electron optical bench" and also includes a simple 9 × 9 dot pattern generator. The pattern of dots viewed on the phosphor meshes will quickly reveal aberration due to lens distortion.Electron Devices Meeting, 1961 Internationa; 02/1961
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ABSTRACT: Abstractin English, Spanish INTRODUCTION: Pediatric parenteral nutrition enables normal growth even of preterm infants. Those children require, however, tailored parenteral nutrition and the creation of such can be challenging due to the risk of instability and shortages. OBJECTIVE: Prototypical parenteral admixtures were created using different calcium salts (organic and inorganic) and different lipid emulsions and tested for stability. 36 of parenteral admixtures containing two types of calcium salts: chloride or gluconolactobionate and different lipid emulsions (SMOFlipid® or Lipofundin MCT/LCT®) were under investigation. METHODS: Preliminary admixtures were prepared in two-chamber bags whereas lipid emulsions were placed separately in the second chamber. Pre-admixtures were stored for up to 21 days at +4ºC. Contents of the two chambers were combined at t = 0 or after 21 days of storage. Physical analysis of completed admixtures (visual inspection, microscopic observation, pH measurement and determination of the size distribution of oily droplets) was carried out after 21 days of the storage. Stability of lipid, commercial emulsions stored in ethylene vinyl acetate (EVA) bags for 42 days was also studied. RESULTS: Irrespectively of the time of storage of preadmixtures and type of calcium salt and different lipid emulsions among 36 total parenteral admixtures only one showed signs of destabilization after preparation and one was unstable when stored for longer than 14 days. All other formulations were qualified to be stable during the study. All investigated commercial lipid emulsions were physically stable in EVA bags even when stored at room temperature. CONCLUSION: The study proved that it was possible to store pre-admixture in EVA bags for 21 days at 4°C as well as that CAN (critical aggregation number) and CaxP (the products of multiplication of calcium and phosphate ions concentration) should not be used as reliable indicators of admixture physical stability. No influence of the type of calcium salts on stability of admixtures was observed.Nutricion hospitalaria: organo oficial de la Sociedad Espanola de Nutricion Parenteral y Enteral 07/2014; 30(n01):84-93. · 1.31 Impact Factor