Cholesterol estimation

B13. Boyd, G. S., The estimation of serum lipoproteins—a micromethod based on zone electrophoresis and cholesterol estimations. Biochem. J. 68, 680 (1954). 

Nanoporous ZnO film has recently been deposited on Au electrode by rf sputtering under high pressure and used it for cholesterol detection. A well preferred c-axis oriented ZnO film with porous surface morphology exhibits linearity as 25-400 mg/dl, response time of 15 s and stability of 75 days [35], Khan et al. have been fabricated a nanocomposite film of ZnO nanoparticles containing chitosan (CH) for cholesterol estimation. This biosensor exhibits linearity from 5-300 mgdL 1 with detection limit of 5mg dF1 and the value of Km as 8.63 mgdL 1 [36]. Sol-gel derived ZnO film has been deposited on Pt electrode for development of an amperometric biosensor to determination of acetylcholine (ACh) and choline (Ch). The resulting biosensor shows linear response from 1.0 x 10"6 to 1.5 x 10 3 M to ACh with detection limit of 6.0 x 10"7 M and a linear response upto 1.6 x 10 3 M to Ch with detection... 

The other basic method used in cholesterol estimation is an enzymic technique based on cholesterol oxidase. This catalyses the reaction ... 

The reaction of cholesterol with acetic anhydride and sulphuric acid to give a green colour. This is the basis of some methods of cholesterol estimation. 

A commercially interesting low calorie fat has been produced from sucrose. Proctor Gamble has patented a mixture of penta- to octafatty acid ester derivatives of sucrose under the brand name Olestra. It was approved by the FDA in January 1996 for use as up to 100% replacement for the oil used in preparing savory snacks and biscuits. Olestra, a viscous, bland-tasting Hquid insoluble in water, has an appearance and color similar to refined edible vegetable oils. It is basically inert from a toxicity point of view as it is not metabolized or absorbed. It absorbs cholesterol (low density Hpoprotein) and removes certain fat-soluble vitamins (A, D, E, and K). Hence, Olestra has to be supplemented with these vitamins. No standard LD q tests have been performed on Olestra however, several chronic and subchronic studies were performed at levels of 15% in the diet, and no evidence of toxicity was found. No threshold limit value (TLV), expressed as a maximum exposure per m of air, has been estabhshed, but it is estimated to be similar to that of an inert hpid material at 5 mg/m. ... 

Insulin resistance has been associated with a number of other cardiovascular risks, including abdominal obesity, hypertension, dyslipidemia, hypercoagulation, and hyperinsulinemia. The clustering of these risk factors has been termed metabolic syndrome. It is estimated that 50% of the United States population older than 60 years of age have metabolic syndrome. The most widely used criteria to define metabolic syndrome were established by the National Cholesterol Education Program Adult Treatment Panel III Guidelines (summarized in Table 40-2). 

In addition to fluorescence methods, another study [27] developed a method to permit electron microscopic localization of Ras anchor domains on cytoplasmic membrane surfaces by immunogold labeling. The particle neighbor distances can be analyzed to obtain information about possible domain structure. Expressing H-Ras and K-Ras in baby hamster kidney cells, a nonrandom particle distribution was obtained from which the estimated mean raft size was 7.5-22 nm and about 35% of the membrane area consists of rafts. The same technique applied to cells that had been incubated with [3-cydodextrin to reduce cholesterol produced completely random distributions of H-Ras. This cholesterol dependence suggests some type of coupling of rafts across the inner and outer membrane leaflets. 

Different classification systems are available to estimate the individual risk of presenting a cardiovascular event in the next 10 years. One of the most frequently used is the Framingham score risk, for which there is also software available online (Third Report of the National Cholesterol Education Program 2002), but recently several organizations involved in cardiovascular care have produced guidelines to identify and manage these risk situations (Mosca 2004). 

The serious drawback of the methods of evaluation of fluidity based on intermolecular quenching or excimer formation is that the translational diffusion can be perturbed in constrained media. It should be emphasized that, in the case of biological membranes, problems in the estimation of fluidity arise from the presence of proteins and possible additives (e.g. cholesterol). Nevertheless, excimer formation with pyrene or pyrene-labeled phospholipids can provide interesting in-... 

Hepatic Effects. Serum markers of liver effects, bilirubin, glucose, cholesterol, and aspartate aminotransferase were not affected in 39 persons exposed to phenol in the drinking water at an estimated dose of 0.14-3.4 mg/kg/day for several weeks (Baker et al. 1978). Because these examinations were completed 7 months after the spill, this study does not provide conclusive evidence that there was no reversible liver damage. 

Cholesterol flip-flop is important for general cholesterol trafficking as well as for lateral domain formation. Using methyl-fi-cyclodextrin as a cholesterol acceptor, Steck et al. [83] estimated the halftime for cholesterol flip-flop in a human red cell bilayer to be <1 s. 

Molecular domains have been observed using the AFM analyses of LB films of a collapsed state (Birdi, 1997, 2003). For example, cholesterol films showed half-but-terfly-shaped domains (each domain consisting of 107 molecules Figure 10.4). This quantity was estimated from the following data the height of the domains was 90 A, which corresponds with six layers of the cholesterol molecule (length of the molecule is found to be 15 A from molecular models). AFM image analysis is capable... 

Accordingly, this algorithm allows one to estimate the solubility of water of an organic substance. The estimated solubility of cholesterol was almost in accord with the experimental data (Birdi, 2008). 

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