Complex Lipids

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Complex Lipids
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Vignette 3

• Introduction A 3 week premature baby boy born to
  a diabetic mother by cesarean section.
• Presenting complaints Bluish discoloration of
  the skin and mucus membranes (cyanosis) with
  apnea.
• Examination Unusual breathing movement --
  drawing back of chest muscles with breathing.
  APGAR score less than 5
• Investigations lecithin/sphingomyelin ratio of
  amniotic fluid at 34th week of gestation 1.2
• Laboratory investigations Blood gas analysis of
  baby indicates low oxygen and excess acid in the
  body fluids. Blood culture negative for
  infection.
• Diagnosis Acute respiratory distress syndrome
  (ARDS)/ Infant respiratory distress syndrome
  (IRDS)

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Classification - (Structure)

• LIPIDS

SIMPLE LIPIDS
COMPLEX LIPIDS
Fats and Oils
Waxes
Phospholipids
Glycolipids
Glycero- phospho- lipids
Sphingo- phospho lipids
Cerebro- sides
Globo- sides
Ganglio- sides
Sulfa-tides
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Simple Lipids
GLYCEROL
Triacylglyceride
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Complex lipids phospholipids
Glycerophospholipids
Ether Glycerolipids
O
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Complex lipids Phospholipids
Glycerophospholipids
Ether Glycerolipids
Sphingophospholipids
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Complex lipids Sphingophospholipids
O
SINE
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Glycerophospholipids
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Phosphatidic acid
GLYCEROL
P
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Glycerophospholipids
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Phosphatidylcholine
Lung surfactant 90 lipids (Dipalmitoylphosphati
dyl-choline, DPPC Dipalmitoylecithin) 10
protein
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Cardiolipin
Diphosphatidylglycerol
Distribution Inner mitochondrial
membrane Function Maintenance of respiratory
complexes
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Ether Glycerolipids
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Plasmalogens
Distribution Phosphatidalethanolamine (in nerve
tissue) Phosphatidalcholine (in heart
muscle) Function More resistant to oxidative
stress therefore provides protection to tissues
with active aerobic metabolism
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Platelet-activating factor
Distribution Released by a variety of cell types,
including platelets, neutrophils, basophils, and
endothelial cells. Functions PAF activates
inflammatory cells and mediates hypersensitivity,
acute inflammatory, and anaphylactic reactions.
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Phosphatidylinositol (PI)
Distribution present in all tissues and cell
types. Especially abundant in brain tissue, (10
of the phospholipids). Functions Cell
signaling, Reservoir of arachidonic acid Protein
anchoring
Stearic acid (180)
Arachidonic acid (204)
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Phosphatidylinositol 4, 5 bisphosphate (PIP2)
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Protein anchoring
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Sphingophospholipids
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Sphingophospholipids
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Sphingosine
2-amino-4-octadecene-1,3-diol C-18 alcohol
containing two OH groups, one amino group and
one double bond
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Sphingomyelin
Distribution Constituent of the myelin sheath of
nerve fibers. Functions Building block of myelin
sheath Primary source of ceramide Signal
transduction
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Phospholipids - Degradation
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Niemann-Pick disease

• autosomal recessive disease
• inability to degrade sphingomyelin.
• deficiency of sphingomyelinase - a type of
  phospholipase C.

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Glycolipids/glycosphingolipids
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Glycolipids/glycosphingolipids

SPHING
O
SINE
CARBOHYDRATE
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Glycolipids/glycosphingolipids
Distribution essential components of all
membranes in the body. greatest amounts in nerve
tissue Functions regulation of cellular
interactions, growth, and development Blood group
antigens
CEREBROSIDES GLOBOSIDES GANGLIOSIDES SULFATIDES
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Cerebrosides

• ceramide monosaccharides -simplest neutral
  glycosphingolipids
• Galactocerebroside - the most common cerebroside
  found in membranes
• Glucocerebroside - serves primarily as an
  intermediate in the synthesis and degradation of
  the more complex glycosphingolipids.
• cerebrosides are found predominantly in the brain
  and peripheral nervous tissue, with high
  concentrations in the myelin sheath

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Galactocerebroside
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Globosides

• Ceramide oligosaccharides
• Addition of monosaccharides (including GalNAc) to
  a glucocerebroside
• e.g.
• Cer-Glc-Gal (lactosylceramide)
• Cer-Glc-Gal-Gal-GalNac-GalNac (Forssman
  antigen)

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Gangliosides

• Negatively charged at physiological pH
• Glycolipids containing sialic acid
  (N-acetylneuraminic acid, NANA)
• found primarily in the ganglion cells of the
  central nervous system, particularly at the nerve
  endings

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Gangliosides

• Nomenclature
• is based on the number of sialic acid residues
• 'GM' a single (mono) sialic acid,
• GD, GT and GQ two, three and four sialic acid
  residues in the molecule, respectively
• on the sequence of the carbohydrates.
• The number after the GM, e.g. GM1 refers to the
  structure of the oligosaccharide.
• These numbers were derived from the relative
  mobility of the glycolipids on thin layer
  chromatograms the larger, GM1, gangliosides
  migrate the most slowly.

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Sulfatides

• cerebrosides that contain sulfated galactosyl
  residues
• negatively charged at physiologic pH
• found predominantly in nerve tissue and kidney

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Sphingolipidosis

• Defects in sequential degradation of glycolipids
  lead to a number of lysosomal storage diseases,
  Sphingolipidosis (cerebrosidoses and
  gangliosidoses)
• A specific lysosomal hydrolytic enzyme is
  deficient in each disorder. Therefore, usually
  only a single sphingolipid (the substrate for the
  deficient enzyme) accumulates in the involved
  organs in each disease

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THE END!