Lipids are characterized by:
insolubility in water and solubility in organic solvents.
Which is the most commonly found sterol in humans?
Cholesterol functions in all of the following except:
Cholesterol esters are formed through the esterfication of cholesterol with:
Which of the following is a variant fo LDL associated with an increased risk of coronary heart disease?
The Friedewald formula for estimating LDL cholesterol should not be used when the :
triglceride is greater than 400mg/dL
Which of the following is false concerning bloodcholesterol concentrations?
Increased cholesterol is associated with hyperthyroidism
Which enzyme is used in enzymatic cholesterol determinations to form hydrogen peroxide?
The desirable range for cholesterol levels as determined by the NECP is:
Less than 200mg/dL
Serum lipase catalyzes the :
Hydrolysis of triglyceride to fatty acids and glycerol
The enzymatic determination of glycerol in triglyceride analysis usually involves conversion of glycerol to:
Which of the following lipid results would be expected to be falsely elevated on a serum specimen from a nonfasting patient?
Blood collected about an hour after the patient has eaten a heavy meal often has elevated:
From 60% to 75% of the plasma cholesterol id transported by:
Triglyceride is the main constituent of :
A and B VLDL,and LDL
The lipoprotein that is responsible for the transport of cholesterol from peripheral cells to the liver for excretion is:
The results on a lipid profile on a 40-year-old patient with a history of alcoholism would be:
To produce the most reliable results, a specimen for a lipid profile should be drawn:
fasting 12 to 14 hours after eating
Which of the following is a reagent commonly used to precipitate VLDL and LDL,thereby allowing the measurment of HDL-C?
dextran sulfate and MgCl2
After a meal, the bloodstream transport chylomicrons and VLDL to all tissues of the body. The principal site of uptake is the:
An increase of 10mg/dL of HDL cholesterol would :
decrease the risk of myocardial infraction
Which apolipoprotein has the ability to increase the risk of coronary heart disease?
A 52-year-old man went to his doctor for a physical examination. The patient was overweight and had missed his last two appointments because of business dealings.His blood pressure was elevated, his cholesterol was 210mg/dL, and his triglyceride was 150mg/dL. The result of lan HDL cholesterol test was 23mg/dL(20-60mg/dL) which of the following would be this patient's calculated LDL cholesterol value?
Total Cholesterol -Reaction 1:Cholesterol Esterase
Cholesterol ester + H2O Cholesterol Esterase→Cholesterol + Fatty acid
Total Cholesterol -Reaction 2:Cholesterol Oxidase
Cholesterol + O2 Cholesterol Oxidase→ Cholestenone + H2O2
Total Cholesterol-Reaction 3:Peroxidase
2 H2O2 + Dye Peroxidase→ 4 H2O + color
Triglyceride -The Reaction 1:Lipase (Bacterial)
Triglycerides + H2O z Bacterial Lipase → 3 Fatty acids + glycerol
Triglyceride -The Reaction 2:Glycerol Kinase
Glycerol + ATP Glycerl kinase→ Glycerophosphate + ADP
Triglyceride -The Reaction 3:Glycerophosphate Oxidase
Glycerophosphate + O2 Glycerophosphate oxisase→ dihydroxyacetone + H2O2
Triglyceride -The Reaction 4:Peroxidase
H2O2 + Dye Peroxidase→ Color
Elevated lipoprotein levels-Hypercholesterolemia:
lipid abnormality most closely linked with heart disease. Genetic predisposition—affected individual ↑ LDL levels that are synthesized; but deficient in LDL-receptors.
Elevated lipoprotein levels- Hypertriglyceridemia:
Genetic—Results in an imbalance between synthesis & clearance of VLDL.
Elevated lipoprotein levels- Combined- Hyperlipidproteinemia:
Presence of ↑ Chol & ↑ Trigly = high risk of CAD
Decreased lipoprotein levels- Hypoalphalipoproteinemia:
Isolated ↓ in circulating HDL. (HDL < 40 mg/dL) Without the presence of hypertriglyceridemia. Premature CAD. Tangier Disease - extreme form, HDL 1-2 mg/dL
Decreased lipoprotein levels- Hypobetalipoproteinemia:
Low levels of LDL, but not associated with CAD.
Effects of Hormones:Insulin-
functions to inactivate lipase (enzyme that breaks down triglycerides) causing the reduction free fatty acid delivered to the liver, thus regulating VLDL synthesis. Insulin also regulates LPL activity which is essential for the clearance of triglyceride-rich-lipoproteins from circulation
Effects of Hormones:Growth Hormone-
Increases the production of VLDL by increasing the production of apo E and apoB-48 and by stimulating lipolysis in the adipose tissues and triglyceride synthesis in the liver.
Effects of Hormones:Sex Hormones-
Estrogens appear to raise VLDL levels by accelerating production rate. Dual role—estrogens increase the number of LDL receptors, thus lowering LDL levels—increase apoA-I production, hence increasing HDL levels. Estrogen has both a positive & negative effects on lipid concentration in the blood. Progesterone balances these effects by lowering VLDL and triglyceride levels by increasing the rate of catabolism.
Effects of Hormones:Thyroid Hormone-
Exert multiple effects on the metabolism of fatty acids and glycerol. Thyroid hormone stimulates both LPL and hepatic triglyceride lipase synthesis and also increases LDL receptor production.
HDL Cholesterol -Precipitation Reaction-
• Uses dextran sulfate polyethylene glycol (PEG) or phosphotungstic acid with magnesium chloride (MgCl2) to precipitate LDL & VLDL lipoproteins from the fasting sample, leaving HDL in the supernatant.
• This HDL supernatant is then assayed for cholesterol.