Dictionary

levocardia Reversal of all the abdominal and thoracic organs (situs inversus) except the heart, which is still in its usual location on the left. Levocardia virtually always is associated with a congenital heart disease.

levodopa A drug (brand names include: Dopar, Larodopa) that is used to treat Parkinson’s disease, Parkinsonian symptoms in other disorders, restless legs syndrome, and herpes zoster. Levodopa converts to the neurotransmitter dopamine in the brain.

levothyroxine sodium A synthetic thyroid hormone (brand names include: Eltroxin, Levothroid, Levoxine, Levoxyl, Synthroid) that is used as a thyroid hormone replacement drug to treat an underactive thyroid gland (hypothyroidism). Because not all brands of levothyroxine sodium are equivalent, it is important not to switch between brand names or generic formulations.

LHRH Luteinizing hormone-releasing hormone.

LHRH agonist A compound that is similar to luteinizing hormone-releasing hormone (LHRH) in structure and can act like LHRH.

libido 1 Sexual drive. 2 In psychoanalysis, the psychic energy from all instinctive biological drives.

library In genetics, an unordered collection of cloned DNA from a particular organism (for example, an E. coli library, a human DNA library). The relationships between these clones can be established with physical mapping. See also genomic library.

lichen planus A common skin disease that features small, itchy pink or purple spots on the arms or legs. The abnormal areas on the skin in lichen planus are typically flat-topped (hence the term planus), itchy, and frequently have a polygonal or angular shape. Lichen planus can occur anywhere on the body but is characteristically…

ligament A tough band of connective tissue that connects various structures, such as two bones.

ligaments, knee The four strong, elastic bands of tissue that connect bone to bone in the knee. They provide strength and stability to the joint. These four ligaments connect the femur (the bone in the thigh) with the tibia (the larger bone in the lower leg); the medial collateral ligament (MCL), which provides stability to…

ligand A molecule that binds to another. Often, a soluble molecule such as a hormone or neurotransmitter that binds to a receptor.

ligate To tie, as in to ligate (tie off) an artery.