Lipids Flashcards
3-hydroxy-5, 6-cholestene
Cholesterol
is the only PHOSPHOLIPID in membranes that is not derived from glycerol.
Sphingomyelin
-derived from amino alcohol SPHINGOSINE
Activator of LCAT?
Function of LCAT?
- Apo-A1
- esterification of cholesterol
*Re esterification of excess cholesterol by ACAT
FORMS of cholesterol.
Cholesterol Ester -70% bound to fatty acid.
Free Cholesterol -30%
Cholesterol increases with age, women has lower values than men except in the age of 50, increased by?
2mg/dl/year 50 to 60 years of age
Principle of chemical methods in cholesterol determination.
Dehydration and Oxidation of cholesterol to form a colored compound.
Cholesterol:
Liebermann Burchardt reaction:
Cholestadienyl Monosulfonic Acid - GREEN COLOR
*Salkowski Reaction- Disulfonic-RED COLOR
Color developer mixture of Leibermann Burchardt reagent. (3)
- Glacial Acetic Acid
- Acetic anhydride
- Concentrated H2SO4
The breakdown of TAG are facilitated by:
Lipoprotein Lipase
Epinephrine
Cortisol
Conditions with DECREASE TAG.
Malabsorption syndrome
Malnutrition
Hyperthyroidism
Brain Infarction
Conditions with DECREASED cholesterol.
Severe hepatocellular disease Malnutrition Severe burns Malabsorption syndrome Hyperthyroidism
Conditions with INCREASED cholesterol.
Hyperlipoproteinemia type 235 Billiary cirrhosis Nephrotic syndrome Poorly controlled DM Alcoholism Primary hypothyroidism
Conditions with INCREASED TAG.
Hyperlipiproteinemia type 12b345 Alcoholism Nephrotic syndrome Hypothyrodism Pancreatitis
Deficiency of this protein will lead to large cholesterol-laden HDL.
This connects forward and reverse cholesterol transport pathways.
Cholesterol Ester Transfer Protein (CETP)
Largest and least dense LPP
<0.95 kg/L
Transports EXOGENOUS TAG
Chylomicrons
ApoB48
with Apo A-1, C and E
90% TAG, + 1-2% protein
CHYLOMICRONS
65% TAG + 16% CE + 6-10% protein
VLDL/ pre-beta lipoprotein
30% PHOSPHOLIPID + 20% CE + 45-50% protein
HDL / alpha LPP
50% CE + 18% protein phospholipid
LDL/ beta LPP
Nascent disk shaped particles
HDL / alpha LPP
Better marker for CHD risk.
LDL
It is the product of VLDL catabolsim.
Migrates either in the pre B or B region
IDL
Known as the ‘sinking pre beta LPP’.
Lipoprotein a
Due to electrophoretic mobility same as VLDL but density like LDL
Abnormal lipoprotein found in ovstructive jaundice and LCAT deficiency. A specific and sensitive indicator of CHOLESTASIS.
Lipoprotein x
Protein portion : Apo C and albumin
Known as:
“Floating B Lipoprotein”
B-VLDL
Density same as VLDL
migration same as LDL in beta region.
Lipoprotein found in type 3 hyperlipoproteinemia and dysbetalipoproteinemia.
B-VLDL
No conversion of VLDL to LDL, does IDL also accumulate.
Preffered anticoagulant for ultracentrifugal and electrophoretic methods in LPP.
EDTA
*Even though Chole and TAG conc are about 3% lower than serum.
Fasting in LIPOPROTEIN determinations.
12 to 14 hours.–> mandatory for LDL and TAG
If non fasting TC and HDL-C can be measured.
Levels of LDL and HDL after eating.
Decreased
Reference method for quantitation of LPP.
Ultracentrifugation.
*expressed in svedverg units (s)
Electrophoretic pattern of LPPs.
HDL , VLDL, LDL, Chylomicrons
VLDL Migrates on a-2 globulin (pre-B)
Most popular method in measuring HDL-C.
Homogenous assay
Formula for LDL-c.
TC - HDL-c - VLDL
*VLDL= TAG/2.175 (friedwald) or 2.825 (de long) –> mmol/ L
If mg/dl –> 5.0 or 6.5 respectively
Apolipoprotein from chromosome 11. (*three)
A-1
A-4
C-3
ApoLipoprotein from chromosome 1 (*one)
A-2
ApoLipoprotein from chromosome 6.
Lipoprotein a
ApoLipoprotein from chromosome 2.
B-100
B-48
ApoLipoprotein from chromosome 19 (*three)
C-1
C-2
E
ApoLipoprotein from chromosome 3.
D
Regulates CETP function.
Apo F
Apolipoprotein associated with CHD, Alzheimer’s dx and hyperlipoprotenemia type 3.
Apo E
E-4 isoforms CHD and Alzheimer
E-2 isoforms hyperlipoproteinemia type 3
Apolipoprotein found in HDL CM LDL VLDL and associated with HDL remodelling.
Apo M
Apolipoprotein homologous to plasminogen, may be prothrombotic; bound to apoB-100 by disulfide linkages
Apo (a)
An autosomal dominant disorder caused by defective or deficient LDL receptors.
Familial hypercholesterolemia (type2a)
*(+) with xanthelasma and planar xanthomas
Involves accumulation of VLDL rich in Chole and chylomicron remnants.
Associated with apo E2.
Involves both the endogenous and exogenous pathway.
Creates a broad beta band electrophoretic pattern. “B-VLDL”–> PATHOGNOMONIC FEATURE.
Familial Dysbetalipoproteinemia/ Type 3 hyperLPPemia
An autosomal recessive disorder; defective apo B synthesis.
VLDL LDL CM–> absent
Chole and TAG–> low
Deficient Fat soluble vitamins ADEK
CHARACTERIZED by cerebullar ataxia, acanthocytosis, fat malabsorption.
Abetalipoproteinemia/ Bassen-Kornzweig syndrome
- vit D not require CM for absorption and therefore typically not deficient.
- vit A and vit K have independent transport systems. Clinical deficiency not severe as seen with vit E.
- vit E relies upon CM for absorption and relies on VLDL /LDL for delivery to tissues. MOST DEFICIENT VITAMIN.
It is an inherited disorder of lipid met. accumulation of sphingomyelin in the BM spleen LNs
Niemann-Pick disease
Autosomal recessive disorder characterized by complete absence of HDL due to mutation in the ABCA1 gene on chromosome 9.
Tangier’s disease.
*clinical findings: orange- yellow discoloration of the tonsils and pharynx.
A rare autosomal recessive disorder that presents abdominal pain and pancreatitis.
It results to inability to clear chylomicron particles, creating the classic “Type 1 chylomicronemia”
Lipoprotein Lipase deficiency
*deficiency in Apo-C-2 also causes chylomicronemia
It is due to mutation in the LCAT gene.
Fish-eye disease is milder form of this.
LCAT deficiency
Deficiency of hexosaminidase A which results in the accumulation of spingolipids in the brain.
Tay-Sachs disease
Distinct from abetalipoproteinemia as only Apo-B48 appears to be affected.
Chylomicron Retention Disease / Anderson’s disease.
*characterized by hypocholesterolemia, chronic diarrhea, failure to thrive and def of ADEK, vit E in particular.
