Enzymatic Determination Of Total Cholesterol Research Articles

ALCOHOL ARTERY INTIMAL INJURY HIGH FAT DIET PRODUCED ATHEROSCLEROSIS MODEL

ObjectivesTo promote atherosclerosis through alcohol artery intimal injury, additional high-fat feeding produced atherosclerosis model, in order to create a convenient, reliable, inexpensive, uniform endothelial injury, operative technique is easy to...

Peroxisome proliferator-activated receptor delta activation leads to increased transintestinal cholesterol efflux

Peroxisome proliferator-activated receptor delta (PPARdelta) is involved in regulation of energy homeostasis. Activation of PPARdelta markedly increases fecal neutral sterol secretion, the last step in reverse cholesterol transport. This phenomenon can neither be explained by increased hepatobiliary cholesterol secretion, nor by reduced cholesterol absorption. To test the hypothesis that PPARdelta activation leads to stimulation of transintestinal cholesterol efflux (TICE), we quantified it by intestine perfusions in FVB mice treated with PPARdelta agonist GW610742. To exclude the effects on cholesterol absorption, mice were also treated with cholesterol absorption inhibitor ezetimibe or ezetimibe/GW610742. GW601742 treatment had little effect on plasma lipid levels but stimulated both fecal neutral sterol excretion ( approximately 200%) and TICE ( approximately 100%). GW610742 decreased intestinal Npc1l1 expression but had no effect on Abcg5/Abcg8. Interestingly, expression of Rab9 and LIMPII, encoding proteins involved in intracellular cholesterol trafficking, was increased upon PPARdelta activation. Although treatment with ezetimibe alone had no effect on TICE, it reduced the effect of GW610742 on TICE. These data show that activation of PPARdelta stimulates fecal cholesterol excretion in mice, primarily by the two-fold increase in TICE, indicating that this pathway provides an interesting target for the development of drugs aiming at the prevention of atherosclerosis.

Simple enzymatic determination of total cholesterol in gallstones compared with intrared spectrophotometry method

Simple enzymatic determination of total cholesterol in gallstones compared with intrared spectrophotometry method

A comparison of willingness to follow U.S. dietary guidelines with actual compliance in 14- and 15-year old adolescents during summer months

Adolescents will often acknowledge to following certain behaviors when in fact the actual behavior suggests otherwise. Chronic disease risk factors were assessed in 54 14- and 15-year-old adolescents by the use of diet records, a modified Harvard step test for assessment of physical fitness and anthropometric measurements. A questionnaire with a 5-point Likert-type scale was used to assess perceived ability and willingness to follow U.S. Dietary Guidelines. A serum sample for enzymatic determination of total cholesterol and lipoprotein concentrations also was taken. Males (n=29) had an average score of 2.5 and 2.4 for perceived ability and willingness, respectively, to follow U.S. Dietary Guidelines while females (n=25) had average scores of 2.4 and 2.3 for perceived ability and willingness, respectively. Assessment of risk factors indicated that 46% (n=25) of subjects were classified as obese (≥ 85th percentile for triceps skinfold thickness). Males had a higher fitness score than females (P<.001), however, the means for both groups were below average. Evaluation of dietary intake revealed that, in comparison to Recommended Dietary Allowances, females had low intakes of vitamin D, calcium and magnesium while males had a low intake of vitamin D. Average sodium intake from food was 3667 milligrams (mg) for males and 2801 mg for females (p<.02) Females had a higher percentage of dietary fat per 1000 kilocalories than males (p=.0116). Fifty-two percent (n=27) and 27% (n=14) of subjects had total- and LDL-cholesterol levels, respectively, above the U.S. mean for adolescents. Nearly one-fifth of the subjects acknowledged that they consume alcohol. Because this study was conducted during summer months, the authors think these results should be good indicators of adolescent diet and health behaviors, as summer vacation should be a time of increased independence for members of this population. These results indicate that adolescents may be willing to follow U.S. Dietary Guidelines, however, their current behaviors conflict with this statement.

Simple enzymatic determination of total cholesterol in gallstones.

In this simple method for rapid enzymatic determination of total cholesterol in human gallstones, gallstone powder is dissolved in an 80/20 by vol mixture of N,N-dimethylformamide and dimethyl sulfoxide and reacted directly with the aqueous enzymatic reagent, without further treatment. The organic solvents do not interfere with enzymatic activities of cholesterol oxidase, esterase, and peroxidase in the assay mixture. The method is reproducible (CVs 3.7% to 6.6%), analytical recoveries ranged from 98.6% to 102%, and linearity is good. Furthermore, results correlated well with those obtained by infrared spectroscopic measurements.

Enzymatic determination of total cholesterol in serum by flow injection analysis

Several methods are proposed for the enzymatic determination of total cholesterol in serum by flow injection analysis (FIA). The use of the merging-zones mode, with or without halting of the reacting plug in the photometric or fluorimetric detector, has allowed the development of four precise methods for the determination of this analyte; calibration curves were linear for ranges of 0.02-0.2 and 0.005-0.05 gl(-1). These methods have been applied to the determination of cholesterol in serum with excellent results.

The activity of cholesterol ester hydrolase in the enzymatic determination of cholesterol: Comparison of five enzymes obtained commercially

The use of five cholesterol ester hydrolases (CEH), numbered 1 to 5, for the enzymatic determination of total cholesterol of human and rat serum are compared. All CEH gave approximately the same value (no statistical difference) for human serum. However, when rat serum cholesterol was determined, CEH-2 yielded a value significantly lower when compared to the four other CEH. The ability of each CEH to hydrolyze individual cholesterol esters was tested. During a 15-min incubation, all CEH were capable of hydrolyzing nearly 100% of cholesteryl oleate and linoleate. In contrast, the hydrolysis of cholesteryl arachidonate was only partial and varied from 20 to 80% depending on the CEH used. The highest hydrolysis was obtained by CEH-1 while the value given by CEH-2 was only 22% of that obtained by CEH-1. The rate of hydrolysis of cholesteryl arachidonate differed markedly among the CEH. The CEH-2-hydrolyzed the cholesteryl arachidonate at a rate seven times lower than the rate obtained with CEH-1. The data suggest that, Under our incubation conditions, CEH-2 did not properly hydrolyze the cholesteryl arachidonate. This phenomenon may be crucial whenever total cholesterol has to be determined enzymatically in the serum of species that contain large amount of cholesteryl arachidonate such as rat, mouse, or dog serum.

Improved enzymatic determination of total cholesterol in tissues.

In this improved method for rapid enzymatic determination of total cholesterol, the lipid extracts from tissues are dissolved in an equal volume of peroxide-free dioxane/isopropanol (50/50 by vol) solution, and are reacted directly with the aqueous enzymatic reagent, without further treatment. The presence of organic solvents, such as dioxane and isopropanol, does not interfere with enzymatic activity. This simpler procedure eliminates the tedious solubilization of tissue lipid extracts into an aqueous medium. The method is reproducible, and results correlate well with those by a chemical (FeCl3/H2SO4) method.

Fluorometric Enzymatic Determination of Total Cholesterol in Serum

We describe a fluorometric enzymatic method for determining total serum cholesterol, based on hydrolysis of cholesterol esters to free cholesterol by cholesterol ester hydrolase (EC 3.1.1.13). The free cholesterol formed, as well as that initially present, is then oxidized by cholesterol oxidase (EC 1.1.3.6) to cholest-4-en-3-one with simultaneous production of hydrogen peroxide. The latter catalytically oxidizes homovanillic acid in the presence of peroxidase (EC 1.11.1.7) to form the highly fluorescent 2,2'-dihydroxy-3,3'-dimethoxy-biphenyl-5,5'-diacetic acid. A calibration curve is constructed from data on a series of standard cholesterol solutions vs. the corresponding fluorescence change (deltaf/5 min). This curve is linear up to 4.0 g of total serum cholesterol per liter of serum. The method is specific, precise, accurate, rapid, and simple, and results correlate well with those obtained by both the Liebermann-Burchard procedure and the colorimetric enzymatic method (correlation coefficients, 0.984 and 0.981, respectively).

Enzymatic Determination of Total Cholesterol in Serum

Enzymatic Determination of Total Cholesterol in Serum