De Quervain's tenosynovitis is inflammation of tendons on the side of the wrist at the base of the thumb. These tendons include the extensor pollicis brevis and the abductor pollicis longus tendons, which extend the joints of the thumb. De Quervain's tenosynovitis can be brought on by simple strain injury to the extensor pollicis longus and abductor pollicis tendons. Typical causes include stresses such as lifting young children into car seats, lifting heavy grocery bags by the loops, and lifting gardening pots up and into place.
double helix. n. The coiled structure of double-stranded DNA in which strands linked by hydrogen bonds form a spiral configuration, with the two strands oriented in opposite directions.
1 The double helix structure of DNA was discovered by Dr. James Watson and Francis Crick in 1953. 2  If you unraveled all the DNA molecules in your body and placed them end to end, it would stretch to the Sun and back several times. 3  DNA is organized into structures called chromosomes within the cell.