Partition cholesterol content

The influence of lipid phase (gel or liquid crystalline), cholesterol content, lipid composition (egg phosphatidylcholine or DPPC), and structure of benzodiazepines determine their localization in the membrane. The strength of benzodiazepine-membrane interaction increases with a decrease in molecular order, molecular packing, and hydration,. The authors point to the pharmacological relevance of theses results because the extent of partitioning of these drags into biomembranes would be coupled to local oscillation of membrane dynamics which may be induced by physiological events. ... 

The shape and fragility of red cell membranes are greatly influenced by their free cholesterol content, and bile salts have been shown to affect the free cholesterol content of red cell membranes in at least two ways (79). Serum cholesterol transesterase activity is inhibited by bile salts, and thus removal of free cholesterol from the membrane, which is facilitated by esterification, is delayed. Bile salts induce a shift in the cell/serum free cholesterol partition ratio in favor of the cell, so that supranormal concentrations of cholesterol occur in the cells. Such cells are flat and osmotically resistant and appear as target cells on stained smears. Patients with jaundice, especially obstructive jaundice, have numerous target cells, and it has been postulated that increased concentrations of bile salts in the serum of such patients may account for the target cell formation (79). 

As with densiometric analysis, methods based on spot size avoid all the difficulties connected with the recovery of the sample and with the extraction of impurities from the adsorbent [31]. An additional advantage is that they may be applied with equal facility to adsorption or partition chromatograms. To illustrate the method, the determination of the cholesterol content of wool wax alcohols by adsorption chromatography will be described. 

In Waldi s simple, semi-quantitative determination of progesterone in serum [179], it is separated from cholesterol by TLC after extraction from 3.5 ml of serum. Comparison with standards is the basis of the evaluation. Luisi et al. [101] have extracted from the serum, purified by liquid/liquid partition and TLC and determined the progesterone quantitatively by gas chromatography. The progesterone content of the serum of 10 normally menstruating women fluctuated during the menstrual cycle between 0.25 and 3.5 (xg/100 ml. 

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