Biochemistry

Prostaglandins are eicosanoids derived from arachidonic acid (20-carbon polyunsaturated fatty acid). They act as paracrine and autocrine signaling molecules.

Severe hypertriglyceridemia (>1000 mg/dL) significantly increases the risk of acute pancreatitis due to pancreatic inflammation caused by triglyceride-rich lipoproteins.

Carnitine, via carnitine palmitoyltransferase (CPT), transfers long-chain fatty acyl groups across the inner mitochondrial membrane, enabling their oxidation in the matrix.

Acetoacetate is the first ketone body formed from two molecules of Acetyl-CoA via HMG-CoA synthase. It can be reduced to beta-hydroxybutyrate or decarboxylated to acetone.

Deficiency of lipoprotein lipase or its cofactor apoC-II results in severe hypertriglyceridemia with elevated chylomicrons and VLDL but relatively normal LDL levels.

Myelin contains approximately 80% lipid by weight, with cholesterol being the most abundant lipid (27% of total myelin mass), followed by galactocerebroside.

LDL carries cholesterol into arterial walls and can be oxidized, promoting atherosclerosis. HDL mediates reverse cholesterol transport, removing cholesterol from tissues and delivering it to the liver.

Tangier disease results from mutations in the ABCA1 gene, which encodes a cholesterol transporter. This leads to severe HDL deficiency and accumulation of cholesterol esters in tissues.

Approximately 70-80% of body cholesterol is synthesized de novo, primarily in the liver. The remaining 20-30% comes from dietary sources.

Saturated fatty acids have higher melting points and are typically solid at room temperature due to tight packing. They are more stable and less prone to oxidation than unsaturated fatty acids.