Cholesterol In Lipid Extracts Research Articles

Characterization of lipid extracts from brain tissue and tumors using Raman spectroscopy and mass spectrometry

Brain tissue is characterized by high lipid content. The amount of lipids decreases, and its composition changes in the most frequent primary brain tumor, the glioma. Scope of the current paper was to extract quantitatively lipids from porcine and human brain tissue as well as from five human gliomas using a modified protocol according to Folch. The lipid extracts were studied by Raman spectroscopy with 785 nm excitation and by mass spectrometry with electron impact ionization. Porcine and human brain tissues have similar water and lipid content and show similar Raman and mass spectra. In contrast, gliomas are characterized by increased water content and decreased lipid content. Elevated phosphatidylcholine to cholesterol ratios in lipid extracts of gliomas were indicated by Raman bands of the choline group and cholesterol. Due to its higher sensitivity, mass spectrometry detected increased levels of cholesterol ester relative to cholesterol in lipid extracts of gliomas. For comparison, thin tissue sections were prepared from the glioma specimens before lipid extraction; infrared spectroscopic images were recorded and analyzed by a supervised classification model. This study demonstrates how to improve the analysis of brain tumors and to complement the diagnosis of brain pathologies using a multimodal approach.

Lipid Extraction and Cholesterol Quantification: A Simple Protocol

A fast and simple protocol for lipid extraction from egg yolk and walnut is presented. Students learn to extract total lipids from both sources and to assess the quantity of cholesterol in lipid extracts by the Liebermann–Buchard method, in a semi-quantitative way. This experiment is easily done in a two-hour lab period, except for the evaporation of lipid extracts to dryness, which proceeds overnight and is weighed by the students the following day. Although enzymatic methods are currently used to measure cholesterol levels, the method described here has the advantage of being simple and quite inexpensive.

Cholesterol quantitation by GLC: artifactual formation of short-chain steryl esters.

A simple and rapid method for the quantitation of total cholesterol in lipid extracts using gas-liquid chromatography is presented here as a modification of an earlier saponification procedure (Ishikawa, T. T., J. MacGee, J. A. Morrison, and C. J. Glueck. 1974. Quantitative analysis of cholesterol in 5 to 20 microliters of plasma. J. Lipid Res. 15: 286-291). Using the original method, as well as a slightly modified version, we found a systematic loss of cholesterol measured as total cholesterol that was attributable to the formation of a byproduct during the procedure. Depending on the nature of the solvent mixture used for extraction after saponification, different byproducts were produced that had longer retention times than cholesterol. The byproducts were identified as cholesteryl butyrate (produced when methyl butyrate was included in the solvent mix) and cholesteryl propionate (with ethyl propionate in the solvent mix) by comparison to authentic standards using gas chromatography-mass spectroscopy. Using mixtures of cholesterol standards, we compared several solvents in lieu of the solvent mixture used in the original extraction procedure to identify those that eliminate the formation of the byproducts. Our optimized microsaponification procedure uses a single solvent, tetrachloroethylene, to extract lipids after the saponification reaction, and improves the accuracy of the cholesterol determination.

Adaptation of an enzymatic kit for the assay of cholesterol in tissue lipid extracts.

In the assay for total cholesterol in lipid extracts by enzymatic methods, it was found necessary to redissolve the lipid prior to the reagent addition. Isopropyl alcohol was found to be best at promoting the colorimetric reaction. As little as 1.45 micrograms free cholesterol and 1.8 micrograms esterified cholesterol could be determined after 15 min incubation with the isopropyl alcohol-reagent. Using a formula for the correction of pigment absorbance, it was also possible to apply the enzymatic kit method to red blood cell lipid extracts.

Indices of free-radical oxidation of lipids and antiradical protection of the brain ? Neurochemical correlates of development of the general adaptation syndrome

1. The stage of long-term adaptation of rats to chronic emotional-pain stress is characterized by an increase in the Superoxide dismutase activity of the brain and the superoxidescavenging activity of the blood serum, the accumulation of fluorescent products of freeradical oxidation, and a decrease in the content of phospholipids and cholesterol in lipid extracts of the brain. 2. Three stages of long-term adaptation of animals to prolonged chronic emotional-pain stress were detected. 3. The first stage of long-term adaptation — a transition from immediate to long-term adaptation — is characterized by increased lability of the arterial pressure, inhibition of orientative-exploratory behavior with predominance of fear reactions, a decrease in the intensity of free-radical oxidation in the brain and blood, and an increase in the Superoxide dismutase activity of the brain and Superoxide-scavenging activity of the blood and in the cholesterol/phospholipid ratio in the brain. 4. The second stage of formed long-term adaptation is characterized by stabilization of the arterial pressure at an elevated level, a low level of free-radical oxidation, and normalization of the antioxidant activity of the brain. 5. The third stage — transition from adaptation to exhaustion — is characterized by a sharp decrease in the arterial pressure and an increase in the intensity of free-radical oxidation.

A sensitive enzymatic assay for determination of cholesterol in lipid extracts

A procedure for the determination of free and total cholesterol in lipid extracts is described. The method for free cholesterol employs cholesterol oxidase to generate H 2O 2 and peroxidase to catalyze the reaction of H 2O 2 with o-dianisidine to yield a colored product. For the determination of total cholesterol, cholesterol ester hydrolase is included.

Procedure for determination of free and total cholesterol in micro- or nanogram amounts suitable for studies with cultured cells.

Procedures for the determination of free and total cholesterol in lipid extracts or sonicates of 10(4) cultured human skin fibroblasts are described. The method for free cholesterol employs cholesterol oxidase to generate H2O2 and peroxidase to catalyze the reaction of H2O2 with p-hydroxyphenylacetic acid to yield a stable fluorescent product. Cholesterol ester hydrolase is included for determination of total cholesterol. When samples of sonified cell suspensions are used directly, the extraction of lipids is avoided, permitting one person to carry out analyses of 30 or more subcultures in one day.

Free and Esterified Cholesterol Content of Animal Muscles and Meat Products

SUMMARY—A method was perfected for the precise, accurate measurement of total and free cholesterol in lipid extracts of raw beef and pork muscle and meat products. The average total cholesterol content of beef and pork muscles was estimated to be 58 and 65 mg % (mg per 100 g), respectively. Both beef and pork muscles had an average cholesterol ester concentration of about 6% of the total cholesterol. Regression equations indicated that the total cholesterol content of muscle increased very slightly as the percent lipid value rose. Extramuscular adipose fat from beef and pork carcassess had total cholesterol values between about 43 and 68 mg %. Total cholesterol was estimated for some meat products. During the broiling of ground chuck samples, up to 15% of the total cholesterol in raw meat was lost in the cook drip.