Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «R»:
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Retrospective diagnosis
Retrospective diagnosis: See: Retrodiagnosis....
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Retrospective study
Retrospective study: In medicine, a study that looks backward in time, usually using medical records and interviews with patients who already known to have a disease....
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Retrosternal
Retrosternal:
Behind the sternum (the breastbone)....
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Retrovirus
Retrovirus: An RNA virus (a virus composed
not of DNA
but of RNA). Retroviruses have an enzyme called reverse transcriptase
that gives them the
unique property of transcribing RNA (their RNA) into DNA. The
retroviral DNA can then
integrate into the chromosomal DNA of the host cell to be expressed...
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Rett syndrome
Rett syndrome: An X-linked dominant neurological disorder that affects girls only and is one of the most common causes of mental retardation in females. Girls with the syndrome show normal development during the first 6-18 months of life followed first by a period of stagnation and then by rapid reg...
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Reuptake
Reuptake: The reabsorption of a secreted substance by the cell that originally produced and secreted it. The process of reuptake, for example, affects serotonin.
Serotonin is a neurotransmitter (a chemical messenger). It is produced by nerve cells in the brain and is used by nerves to communicate w...
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Reversal of organs, total
Reversal of organs, total: This condition (medically
called situs inversus totalis) involves complete transposition (right to left reversal) of
the thoracic and abdominal organs. The heart is not in its usual position in the left
chest but is on the right. Specifically related to the heart, this is ...
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Reverse genetics
Reverse genetics:
In classic genetics, the traditional approach was to find a gene product and then try to identify the gene itself. In molecular genetics, the reverse has been done by identifying genes purely on the basis of their position in the genome with no knowledge whatsoever of the gene pro...
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Reverse transcriptase
Reverse transcriptase: The enzyme that permits the human immunodeficiency virus (HIV) and other retroviruses to use their viral RNA as a template to make DNA.
Reverse transcriptase is so-named because it reverses the usual transcription of DNA into RNA and allows RNA to be transcribed into DNA....
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Reverse transcriptase-polymerase chain reaction
Reverse transcriptase-polymerase chain reaction: Abbreviated RT-PCR. See: RT-PCR....
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Reye syndrome
Reye syndrome: A sudden, sometimes fatal,
disease of the brain (encephalopathy) with degeneration of the liver,
occurs in children (most cases 4-12 years of age), comes after the
chickenpox (varicella) or an influenza-type illness, is also
associated with taking medications containing aspirin. ...
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RF
RF: Rheumatoid factor. Rheumatoid factor is an antibody that is measurable
in the blood. It is commonly used as a blood test for the diagnosis of rheumatoid
arthritis. Rheumatoid factor is present in about 80% of adults (but a much lower
proportion of children) with rheumatoid arthritis. It is also...
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RFA
RFA: Radiofrequency ablation....
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RFID
RFID: Radio frequency identification, a system for remotely storing and retrieving data. RFID tags can serve to identify and track medications....
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RFLP
RFLP: Restriction fragment length polymorphism. A
difference in DNA between people that can be recognized by the use of a restriction enzyme....
