Lipids determination

Lipid Screening. The problems of lipid analysis in the newborn is difficult because of the fact that most methods for analysis for lipids require substantial amounts of serum, yet a total lipid determination is very important in various types of disease. This problem can be solved by thin-layer chromatography (59). Figure 38 shows a typical pattern obtained when an extract 7rom 10 microliters of serum is subjected to thin-layer chromatography. If these specimens are scanned, and an internal standard is run, one can obtain a rough approximation of the distribution of the various lipids in the serum. This is shown in Figure 39, in which a normal specimen is run in an adult. 

Preparative TLC of crude Mycobacterium leprae lipids determination of the molecular 68... 

This chapter gives an overview of GC/MS analytical procedures used for lipid determination, and a summary of the complex issue of lipid chromatographic data interpretation in paintings and archaeological objects. Some examples and case studies are also included. 

PRAVASTATIN SODIUM Pravastatin can be administered as a single dose at any time of the day, with or without food. Because the maximal effect of a given dose is seen within 4 weeks, perform periodic lipid determinations at this time and adjust dosage according to the patient s response to therapy and established treatment guidelines. 

Hypertriglyceridemia Hypertriglyceridemia in excess of 800 mg/dL occurred in approximately 25% of patients approximately 15% developed a decrease in high density lipoproteins (HDL) and approximately 7% showed an increase in cholesterol levels. Perform blood lipid determinations before isotretinoin is given and then at intervals until the lipid response to isotretinoin is established, which usually occurs within 4 weeks. 

Phase behavior of lipid mixtures is a much more difficult problem, due to nonideal mixing of lipid components. Ideal mixing implies like and unlike lipids have the same intermolecular interactions, while nonideal mixing results from differential interactions between lipid types. If the difference is too great, the two components will phase separate. While phase separation and lateral domain formation have been observed in many experiments, we lack a molecular-level physical description of the interactions between specific lipids that cause the macroscopic behavior. The chemical potential of a lipid determines phase separation, as phase coexistence implies the chemical potential of each type of lipid is equal in all phases of the system [3,4],... 

The information includes location of double bonds In fatty acids, indentlficatlon of components in complex lipids, determination of compositions of anionic and cationic surfactants, and identification of long-chained alkyl substituents on phosphonium and ammonium ions. 

The Physical State of the Lipids Determines the Properties of a Lipid Membrane or... 

THE PHYSICAL STATE OF THE LIPIDS DETERMINES THE PROPERTIES OF A LIPID MEMBRANE OR BARRIER... 

The Lipid Determination of Fish by the Modified Biight and Dyer Method... 

The most popular and generally effective method for lipid determination of fish is the modified BHght and Dyer method [44] see also [42]. The extraction of lipids is performed with a mixture of chloroform and methanol (1 1). For the procedure of this method see [42, 44]. Unfortunately, methanol is distinctly toxic, producing headaches if the laboratory is inadequately ventilated, and chloroform has been suspected of being carcinogenic. It is assumed that for these reasons this method was not accepted as an official OECD Guideline, although it was proposed for review panel in 1980. Therefore, this method should be used only if the results of extraction have to be compared with those of other laboratories. 

Instead of using a mixture of chloroform and methanol, the extraction of lipids by a mixture of hexane and acetone (2 1) is recommended. This mixture has almost all desirable extraction properties and is superior to the other mixtures with respect to the undesirable properties of these. However, this method for lipid determination is very time consuming. Therefore, in the following section, a fast and easy method for the determination of the lipid content of fish on a fresh weight basis by the modified procedure of Ernst et al. [45], Beck and Mathar [46], and Schmitt et al. [47] is described. 

This cold extraction method is successfully performed in our and other laboratories for more than 20 years. Because hexane is neurotoxic, isohexane or heptane can be used as a hydrophobic solvent. A modified method can also be used as a semi-micro method for the lipid determination in fish, mussels, oysters, Daphnia, and other aquatic organisms or tissues. 

Satoh I (1988) Biomedical Applications of the Enzyme Thermistor in Lipid Determinations. In Mosbach K (ed) Methods in Enzymology, vol 137. Immobilized Enzymes and Cells, Part D. Academic Press, Orlando, p 217... 

Fig. 2. Total lipid in cultured Atlantic salmon (Salmo salar) over their life cycle. Adapted from ref. 123. Data points 1 -8 represent doubling of degree days from fertilization until near hatching 12-26 represent approximate doubling of body weight at each point. Lipids determined gravimetrically after Soxhlet extraction from dried tissues.

In the past 10 years there has been an increasing emphasis on the relationship of various lipids to atherosclerotic heart disease. The clinical laboratory is performing a greater number of lipid determinations as well as a larger variety of procedures. In order to meet these demands, laboratories are increasingly turning to automated instrumentation and methodology. This review will discuss one automated instrumental system, and the lipid techniques that have been adapted to it. 

Lipides, Determination of Inositol, Ethanolamine, and Serine in (McKibbin). 7 111... 

Lipophilic organic contaminants accumulate in the lipid tissue of the species studied. Therefore, concentrations should be provided on wet weight as well as lipid weight basis or the lipid content of the sample should be provided together with the analytical results. It is important to state whether total lipids or extractable lipids have been determined, and to specify the method for lipid determination. Whether or not a normalisation should be performed has to be adjusted to the objective of the monitoring. 

The extracts of biological samples usually contain high concentration of lipids which must be removed before the analysis. Particularly if GC is used in the analysis, efficient removal of lipids is crucial. As the concentrations of many liphophilic FRs are related to the amount of lipids, the lipid content is often measured gravimetrically prior to the cleanup, or determined separately by a total lipid determination. Lipids can be removed by destructive or nondestructive methods. For serum or plasma samples, the lipid determination can be conveniently done on separate aliquots by enzymatic tests. 

Other laboratory evaluations should include a complete blood count, liver function tests, and fasting lipid determination before initiating therapy. Testing should be repeated after 1 month of therapy and thereafter only as abnormalities indicate. 

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