CC PT.2

• Lipoproteins


  They are NOT lipids; they are proteins
• Main Function of lipoproteins


  Transport lipids
• Lipids are immiscible (do not mix with water) thus, they need lipoproteins for: Cholesterol → Adrenal Gland → Sex Hormone, Cortisol; Triglyceride → Skin → Adipose Tissue
• Patient Preparation / Specimen Collection and Preparation

  • Fasting: 12-14 hours (10-12 hrs according to Rodriguez)
  • Storage for Delayed Analysis: 4° (ref temperature) for several days (Proteins are not affected too much to changes in plasma or serum)
• Lipoprotein Methodologies


  1. Ultracentrifugation

  2. Electrophoresis

  3. Chemical Precipitation

  4. Immunochemical Methods
• Ultracentrifugation


  • Reference method for lipoprotein
  • Separates lipoproteins according to density
  • Chylomicrons (Chyle) – seen in patients that did not fast; least dense
  • LPA (Minor lipoprotein)
  • BVLDL (Beta VLDL) – abnormal lipoprotein
  • HDL – most dense
• Electrophoresis


  • Origin contains serum; all migrate towards the anode (+ charge)
  • 5 distinct bands will be seen after electrophoresis
  • Albumin → fastest aside from prealbumin, followed by a1, a2, B, Y
  • HDL (alpha lipoprotein) → because it migrates to alpha 1, hence the fastest lipoprotein
  • VLDL (pre beta lipoprotein) → in alpha 2; before beta region = pre beta
  • LDL (beta lipoprotein) → in beta region
  • Chylomicron (origin) → does NOT move
• Chemical Precipitation


  • Purpose: to separate LPP
  • Use Heparin and Dextran Sulfate
  • Use Magnesium or Manganese
  • Used especially for HDL because it is usually at the bottom
• Immunochemical Methods


  • Uses antibodies on solid supports specific to apolipoproteins
  • Serology: Solid supports such as: Agarose gel, Microtiter – where we can attach antibodies
  • Apolipoproteins: Directs lipid to target organ, Maintains lipoprotein structure
• • If you consume dietary TAG, it will be carried by chylomicron (produced from the intestine)
  • TAG + CM will be carried to the tissue, will pass through lymphatic duct → becomes adipose
  • TAG may also be carried to the liver (2 routes: tissue and liver) with VLDL
  • Cholesterol will be carried by LDL
• Chylomicrons (CM)


  • Delivers TAG to tissues (passes through duct) → to become adipose
  • Largest and least dense
  • EXOgenous TAG transport (dietary intake)
  • Apolipoprotein: APO B-48
• Very Low Density Lipoprotein/ Pre-Beta Lipoprotein (VLDL)


  • TAG in liver will be delivered by VLDL to the tissue
  • Catabolism: VLDL → IDL → LDL
  • ENDOgenous TAG transport
  • Apolipoprotein: APO B-100
• Low Density Lipoprotein (LDL)


  1. Product of VLDL

  2. LDL will carry cholesterol to organs to produce hormones

  3. LDL can be deposited into the subendothelial and be eaten my macrophage (Normal person)

  4. If a person eats more cholesterol → macrophage release cytokines, which may cause inflammation → increase CRP (early indicator of AMI) → bump

  5. Once damaged → clot

  6. Atherosclerotic Plaque: combination of LDL, WBCs, clot, etc. → inflammation → obstruction of blood vessels

  7. If clot fragments/dislodges (without the help of plasmin) → may travel to the brain → stroke

  8. If clot fragments/dislodges (without the help of plasmin) → may travel to the heart → cardiac arrest
• Low Density Lipoprotein (LDL)


  • Most atherogenic lipoprotein
  • Marker of atherosclerosis/CHD for diagnosis or treatment
  • Forward cholesterol pathway (always goes to the tissues)
  • Apolipoprotein: APO B-100
• LDL-C Reference Values


  • <100 mg/dL = optimal
  • 100-129 mg/dL = near/above optimal
  • 130-159 mg/dL = borderline high
  • 160-189 mg/dL = high
  • ≥190 mg/dL = very high
• Friedewald Method (indirect method) for LDL-C


  • VLDL (mmol/L) = Plasma TAG / 2.175
  • VLDL (mg/dL) = Plasma TAG / 5
• De Long Method (indirect method) for LDL-C


  • VLDL (mmol/L) = Plasma TAG / 2.825
  • VLDL (mg/dL) = Plasma TAG / 6.5
• Beta quantification


  Most common research method for LDL-C
• High Density Lipoprotein (HDL)


  • Smallest but most dense
  • Reverse cholesterol transport
  • Cardioprotective
  • Apolipoprotein: APO A-1
• HDL Reference Values


  • 40 mg/dL - cut off level
  • <35 mg/dL - high risk for CHD
  • >60 mg/dL - high (protective)
• Lipoprotein A/ LPa Sinking Pre-B Lipoprotein


  • Independent risk factor for atherosclerosis
  • Similar to plasminogen in structure
• Intermediate Density Lipoprotein (IDL)


  • VLDL catabolic product
  • High in Type 3 hyperlipoproteinemia
• Lipoprotein X


  • Obstructive jaundice and LCAT deficiency
  • Specific and sensitive indicator of cholestasis
• 1. VLDL


  • Abnormally migrating B-VLDL
  • "FLOATING Beta Lipoprotein"
  • Found in dysbetalipoproteinemia / type 3-hyperlipoproteinemia
  • Xanthoma (yellow fat deposits in skin) in children, if found in adults it is a liver problem
• • Beta VLDL has the same weight with VLDL BUT has the same speed as LDL
  • Mobility: LDL
  • Density: VLDL
  • This is dangerous, candidate for HEART TRANSPLANT, Premature coronary heart disease → can be found in infants (manifests xanthoma)
• Familial Hypercholesterolemia (Type 2A)


  • Defective LDL receptors
  • TC and LDL C (2-3x above normal)
  • Consequence: High chole and high LDL = high total chole → no receptors
• Familial Dysbetalipoprotenemia/ Type 3 Hyperlipoproteinemia


  • Pathognomonic (unique) Feature: broad abnormal band between VLDL and LDL (B-VLDL)
  • In electrophoresis: B-VLDL: in a2, LDL: in beta. B-VLDL is a thick band between VLDL and LDL.
• Abetalipoproteinemia


  • Defective Apo B synthesis
  • VLDL, LDL, And chylomicrons = absent
  • Chole and TAG: LOW
  • Function of apolipoprotein: maintain structure of lipoprotein → defective structure → absent
• Hypobetalipoproteinemia


  • Apo-B: deficient
  • LDL-chole and total cholesterol: LOW
  • VLDL-Chole and Total TAG: LOW to NORMAL
• Tangier's Disease


  • Absent HDL: Due to mutation in ABCA1
  • No clearing of cholesterol
  • Called "Tangier" because of "tangerine tonsils" (orange tonsils) because of FATS
• Lecithin Cholesterol Acyl Transferase Deficiency (LCAT)


  Fish eye disease
• Tay-Sachs Disease


  Deficiency of the enzyme Hexosaminidase A → sphingolipid accumulation
• Lipoprotein Lipase (LPL) Deficiency


  Inability to clear chylomicrons particles
• NCEP (National Cholesterol Education Program) Values

  • Total Cholesterol: 3% CV
  • HDL - C (>42 mg/dl): 4% CV
  • LDL-C: 4% CV
  • TAG: 5% CV
• Proteins


  • Amphoteric: Has weak negative and weak positive charge due to pH
  • Synthesized: Liver except immunoglobulins (Plasma cells)
  • Four Protein Structures: Primary Structure - Linear sequence of the amino acid. It determines the identity of protein, Secondary - Winding of polypeptide chain. For strength & flexibility, Tertiary - 3-dimensional configuration. Physical and chemical properties, Quaternary - 2 or more polypeptide chains
• Hormones that influence protein synthesis/Anabolism

  • T4 - metabolism
  • Growth hormone (GH) - tissue growth
  • Insulin - energy
  • Testosterone - male secondary characteristic
• Hormones for Protein Catabolism

  • Cortisol
  • Glucagon
• Prealbumin (Transthyretin)


  • Transthyretin: Trans - Transport, Thy - Thyroxine, Retin - Vitamin A
  • Vitamin A and Thyroxine
  • Malnutrition - Marker
  • CSF landmark
  • Increased: Alcoholism, Chronic renal failure, Steroid treatment
  • Decreased: Poor nutrition, Hepatic damage, Tissue necrosis, Inflammatory response
• Albumin


  • Highest concentration - ½ of the protein and strongly negative
  • General transport protein
  • Maintains osmotic pressure
  • pH buffer
  • Negative APR; Also transferrin, transthyretin (Prealbumin)
  • Indicator of nutritional status
  • Prognostic marker of Cystic fibrosis
  • Analbuminemia: hereditary absence of albumin
  • Bisalbuminemia: 2 albumin bands
• Dye binding Methods for Albumin

  • Bromcresol Green (BCG) - most common
  • Bromcresol Purple - most specific
  • Methyl orange - nonspecific
  • HABA - low sensitivity, more specific to albumin