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(rī″bō-flā′vĭn) C17H20N4O6; a water-soluble vitamin of the B complex group. It is an orange-yellow crystalline powder. Symptoms of riboflavin deficiency are photophobia, cheilosis, glossitis, and seborrheic dermatitis, esp. of the face and scalp. SYN: vitamin B2.

FUNCTION: Riboflavin is a constituent of certain flavoproteins that function as coenzymes in cellular oxidation. It is essential for tissue repair.

SOURCES: Riboflavin is found in milk and milk products, leafy green vegetables, liver, beef, fish, and dry yeast. It is also synthesized by bacteria in the body.

DAILY REQUIREMENT: Adults require 0.6 mg/1000 kcal of food intake. Infants, children, and pregnant and lactating women require increased amounts.


(rī″bō-nū′klē-ās) ABBR: RNase. An enzyme that catalyzes the depolymerization of ribonucleic acid (RNA) with formation of mononucleotides.


(rī″bō-noo″klē-ō-prō′tē(-ĭ)n) ABBR: RNP. A compound containing both protein and ribonucleic acid.


(rī″bō-nū′klē-ō-tīd) A nucleotide in which the sugar ribose is combined with the purine or pyrimidine base.


(rī′bŏ-prōb″) A short, radioactively labeled nucleotide sequence used in molecular hybridization to identify specific RNA or DNA sequences.


(rī′bōs) C5H10O5, a pentose sugar present in ribonucleic acids, riboflavin, and some nucleotides.


(rī′bō-sōm) A cell organelle made of ribosomal RNA and protein. Ribosomes may exist singly, in clusters called polyribosomes, or on the surface of rough endoplasmic reticulum. In protein synthesis, they are the site of messenger RNA attachment and amino acid assembly in the sequence ordered by the genetic code carried by mRNA.


(rī′bō-sĭl) The compound glycosyl, C5H9O4, formed from ribose.


(rī′bō-zīm) An RNA (ribonucleic acid) molecule that functions as an enzyme (catalyst) and either cleaves (breaks down) other forms of RNA or catalyzes other biochemical reactions occurring within cells. SYN: catalytic RNA.


(rīs) Acronym for rest, ice, compression, and elevation, the elements of management of acute soft tissue injuries.

Richter transformation, Richter syndrome

(rik′tĕr) In patients with chronic lymphocytic leukemia, the development of an aggressive lymphoma from a relatively indolent B-cell leukemia. Symptoms include rapid enlargement of lymph nodes, elevated serum tumor marker levels, drenching night sweats, and massive weight loss.


(rī′sĭn) A white, amorphous, highly toxic protein present in the seed of the castor bean, Ricinus communis. It has been used as a ...

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