LIPIDS

Lipids

Commonly referred to as fats and composed mostly of carbon hydrogen bonds

Blood and water

Lipids are insoluble in what?

Organic solvents

Lipids are soluble in what?

Lipoproteins

Lipids require special transport mechanisms known as what for circulation in the blood?

Primary sources of fuel

Provide stability to cell membrae

Sources of hormones

Major functions of lipids

Phospholipids

Most abundant lipid in plasma

Fat soluble vitamin (ADEK)

Least abundant lipid in plasma

Liver and intestine

Phospholipid originates where?

2 fatty acids and phosphorylated glycerol

Phospholipids are produced from the conjugation of what?

Phospholipid

Amphipathic lipid, meaning it contains polar hydrophilic head and nonpolar hydrophobic fatty acid side chain

Saturated fatty acid

What content of plasma phospholipid is reported to be an independent risk factor for atherosclerosis?

Atherosclerosis

Phospholipids are risk factors of what disease?

Type 2 pneumocytes (lamellar bodies)

In the lungs, phospholipids are produced by what?

150-380 mg/dL

Reference value of phospholipids

Surface tension

Phospholipids alter fluid what?

Decreases surface tension

Does phospholipids decreases or increases surface tension within alveolar space?

Neonatal respiratory distress syndrome (RDS)

Deficiency of surfactant leads to what?

70%

Lecithin percentage

20%

Sphingomyelin percentage

10%

Cephalin percentage

Sphingomyelin

Only phospholipid in membranes that is not derived from glycerol but from an amino alcohol called sphingosine

Sphingosine

Sphingomyelin is derived from an amino alcohol called?

Niemann-pick disease

Accumulation of sphingomyelin in the liver and spleen leads to what?

Lipid-bound phosphate

Only unique structural feature common to all phospholipids is the presence of what?

Sphingomyelin

Reference analyte during the third trimester of pregnancy because its concentration is constant as oppose to lecithin

25

Each mole of phosphorus contributes about 4% to the total phospholipid mass, thus, phospholipid mass can be determined by multiplying the phospholipid phosphorus concentration by what?

4%

Each mole of phosphorus contributes how much to the total phospholipid mass?

Lecithin/sphingomyelin (L/S) ratio

What is used to estimate the status of fetal lung maturation?

Chromatography and fluorescence polarization

What test is used in L/S ratio?

Thin layer chromatography

Method for L/S ratio

Densitometric quantitation

After thin layer chromatography, what follows?

Fluorescence polarization

Microviscosity of amniotic fluid can be measured by what?

Cholesterol

Unsaturated steroid alcohol containing four rings with a single C-H side chain tail

Liver

Where are cholesterol synthesized?

Surface layer of lipoproteins

Cholesterol is found where?

No

Is cholesterol metabolized?

Estrogen

Cholesterol transport and excretion is promoted by what hormone?

<200 mg/dL

Reference value of cholesterol

200-239 mg/dL

Bolderline cholesterol

>240 mg/dl

High cholesterol

Progestin

Glucocorticoids

Mineralocorticoids

Androgens

Estrogens

Precursor of major steroids

Cell membranes and bile acid

Cholesterol is a constituent in the assembly of what?

Atherosclerosis

Myocardial

Coronary arterial occlusions

Cholesterol evaluates the risk of what diseases?

70%

Percentage of cholesterol ester

Serum and plasma

cholesterol ester is found where?

LCAT

Cholesterol ester undergoes esterification by what?

Fatty acid

Cholesterol ester is cholesterol bound to what?

Cholesterol ester

Inactive form of cholesterol with protective property and stored in cells

Cholesterol ester

Classified as a neutral lipid and are not found on the surface of lipid layers but instead are located in the center of lipid drops and lipoproteins

ACAT (acyl-CoA:cholesterol acyltransferase)

Excess cholesterol is re-esterified by what microsomal enzyme?

Plasma

Lecithin-cholesterol acyl transferase (LCAT) is found where?

Liver

LCAT is synthesized where?

LCAT (lecithin-cholesterol acyl transferase)

Catalyzes the esterification of cholesterol by promoting the transfer of fatty acids from lecithin to cholesterol

Apo-1

Activator of LCAT

30%

Unesterified/free cholesterol percentage

Plasma, serum and RBC

Unesterified/free cholesterol is found where?

Unesterified/free cholesterol

Active form of cholesterol with cytotoxic property

Esterification

Detoxification step to reduce the accumulation of free cholesterol through the action of the acyltransferase enzymes

Women

Who has lower levels of cholesterol?

8-12 hours

Fasting requirement for cholesterol

Chemical method

Dehydration and oxidation of cholesterol to form a colored compound

Liebermann-burchardt reaction

End product: cholestadienyl monosulfonic acid (green end color)

Salkowski reaction

End product: cholestadienyl disulfonic acid (red end color)

Pearson, stern and mac gavack : colorimetry

One step method of cholesterol chemical method

Bloors : extraction + colorimetry

Two step method of cholesterol chemical method

Abell-kendal : saponification + extraction + colorimetry

Three step method of cholesterol chemical method

Abell-kendal

Reference method for cholesterol

90%

How much cholesterol is endogenous?

10%

How much cholesterol is dietary?

Schoenheimer, sperry, parekh, jung : saponification + extraction + colorimetry + precipitation

Four step method of cholesterol chemical method

Liebermann-burchardt

Reagent for colorimetry

Petroleum ether

Reagent for saponification

Alcoholic potassium hydroxide

Reagent for saponification

Digitonin

Reagent for precipitation

Enzymatic method

Measures the total cholesterol in serum or plasma

Hydrogen peroxide

The most common method of quantifying the cholesterol oxidase reaction is to measure the amount of what produced?

Hemoglobin

Has a pseudo-peroxidase activity that can diminish the hydrogen peroxide produced in the reaction

Color of hemoglobin

Falsely increases total cholesterol

Cholesterol

What lipid has no need for fasting?

Triglyceride

Most dense lipid

<150 mg/dl

TAG ref:

Normal

<200 mg/dL

TAG ref:

Clear

>300 mg/dl

TAG ref:

Turbid

>600 mg/dl

TAG ref:

Opaque/milky

Fatty acid

Simplest building block of lipid

Triglyceride

Primary cause of turbidity

CDC reference method

It uses hexane extraction after hydrolysis with alcoholic KOH followed by reaction with Liebermann-Burchardt color reagent.

Green

End color of CDC reference method

Isotope dilution mass spectrometry

It is the highest order method for serum cholesterol developed by NIST and gold standard for cholesterol

Triglyceride

Contains three molecules of fatty acid and one molecule of glycerol by ester bonds

Triglyceride

Main storage lipid in humans

Epinephrine and cortisol

Breakdown of TAG is facilitated by what hormones?

10-12 hours

Fasting requirement of TAG

Triglyceride

It evaluates suspected atherosclerosis and measures the body's ability to metabolize fat

>200 mg/dl

Fasting TAG of what value are at risk for coronary artery disease?

Posture

In patient preparation, other than fasting, what else is considered for TAG testing?

Plasma or serum

What can be used for measurement of TAG?

Colorimetric

Van handel method

Formaldehyde

Raw material of van handel

Choromotropic acid

Reagent of van handel