Dopa: A precursor (forerunner) of dopamine, a key neurotransmitter (messenger) in the brain.
Dopa is used in the treatment of Parkinson disease. Parkinson disease is believed to be related to low levels of dopamine in certain parts of the brain. When dopa is taken by mouth, it crosses through the blood-brain barrier. Once it has crossed from the bloodstream into the brain, it is converted to dopamine. The resulting increase in dopamine concentrations in the brain is thought to improve nerve conduction and to assist in lessening the movement disorders in Parkinson disease.
In 1970 the FDA (Food and Drug Administration) approved dopa in the form of L-Dopa, or levodopa, for use in the US. The drug revolutionized the treatment of Parkinson disease.
- Dopa-responsive dystonia (DRD)
Dopa-responsive dystonia (DRD): A condition that typically begins in childhood or adolescence with progressive difficulty in walking and, in some cases, spasticity and can be successfully treated with drugs. Segawa dystonia is an important variant of dopa-responsive dystonia. In Segawa dystonia, the symptoms fluctuate during the day from relative mobility in the morning to increasing […]
Dopamine: An important neurotransmitter (messenger) in the brain. Dopamine is classified as a catecholamine (a class of molecules that serve as neurotransmitters and hormones). It is a monoamine (a compound containing nitrogen formed from ammonia by replacement of one or more of the hydrogen atoms by hydrocarbon radicals). Dopamine is a precursor (forerunner) of adrenaline […]
- Doppler ultrasound
Doppler ultrasound: A form of ultrasound that can detect and measure blood flow. Doppler ultrasound depends on the Doppler effect, a change in the frequency of a wave resulting here from the motion of a reflector, the red blood cell. There are several kinds of Doppler ultrasound: Color Doppler — This technique estimates the average […]
Doraphobia: An abnormal and persistent fear of fur. Sufferers of this fear avoid fur-bearing animals such as dogs, cats, foxes, beavers and rabbits because fur is repulsive to them. Perhaps some of these phobics associate fur with childhood stories about “the big bad wolf” and other fur-bearing predators. Their fear is not always unfounded, for […]
- Dorian Gray effect
Dorian Gray effect: Sudden aging, an abrupt change from seeming youthfulness to the reality and ravages of age, as can occur naturally or when the effects of plastic surgery and Botox treatments wear off. Named after “The Picture of Dorian Gray” (1890), the novel by Oscar Wilde, in which Dorian gives his soul to remain […]