Bietti crystalline dystrophy: A genetic eye disease that leads to progressive night blindness and visual field constriction and is characterized by the formation of crystals in the cornea (the clear covering of the eye), yellow shiny deposits on the retina, and progressive atrophy of the retina and choroid (the back layers of the eye). Average age of onset is 29. Lipid inclusions are present not only in the cornea but also in blood lymphocytes, suggesting a systemic disorder of lipid metabolism. There is no known treatment. The disease is an autosomal recessive trait (the gene is on chromosome 4q35-qter) and is named for G. B. Bietti, an Italian ophthalmologist, who described it in 1937. Also called Bietti crystalline corneoretinal dystrophy.
- Bifid uvula
Bifid uvula: The anatomic structure that dangles downward at the back of the mouth and is attached to the rear of the soft palate.
- Big toe sign
Big toe sign: An important neurologic examination based upon what the big toe (and other toes) do when the sole of the foot is stimulated. If the big toe goes up, that may mean trouble. The big toe response, also called the Babinski reflex, is obtained by stimulating the external portion (the outside) of the […]
Bilateral: Affecting both sides. For example, bilateral arthritis affects joints on both the left and right sides of the body.
Bile: Bile is a yellow-green fluid that is made by the liver, stored in the gallbladder and passes through the common bile duct into the duodenum where it helps digest fat. The principal components of bile are cholesterol, bile salts, and the pigment bilirubin. An imbalance between these components of bile leads to the formation […]
- Bile acid
Bile acid: An acid made by the liver that works with bile to break down fats. On a more technical level, bile acids are steroid carboxylic acids derived from cholesterol. The primary bile acids are cholic and chenodeoxycholic acids. They are conjugated with glycine or taurine before they are secreted into the bile.