• Specialty
  • Cardiology
  • Dentistry
  • Dermatology
  • General Medicine
  • GI/GU
  • Hematology
  • Immunology
  • Lab Medicine & Pathology
  • Neuro-Psych
  • OB-Gyn
  • Oncology
  • Ophthalmology
  • Orthopaedic
  • Otolaryngology - ENT
  • Radiology
  • Surgery

• GI/GU
  • Cancers & Tumors - GI/GU
  • Digestive Terms
  • Diseases - GI/GU
  • Feedings - GI/GU
  • Herbs - GI/GU
  • STD Terms
  • Syndromes - GI/GU
  • Tubes - GI/GU
  • Sample Reports - Urology
  • Sample Reports - Gastroenterology

• STD Terms

- R -

• Radiation Oncologist

A doctor who specializes in using radiation to treat cancer.



• Radiation Therapy

Treatment with high-energy rays to kill cancer cells. External radiation is the use of a machine to aim high-energy rays at the cancer. Internal radiation therapy is the placement of radioactive material inside the body as close as possible to the cancer.



• Randomization

The process by which patients in a clinical trial are randomly assigned to different treatments. Randomization minimizes the differences among groups by equally distributing people with particular characteristics among all the trial arms.



• Randomized Trial

A trial in which the participants are randomly assigned to receive one of the treatments under study or a placebo. See Randomization.



• Rash

A general term applied to any eruption of the skin, especially those pertaining to communicable diseases. A rash is usually a shade of red, which varies with disease and is usually temporary.



• Recombinant

Refers to compounds produced by laboratory or industrial cultures of genetically engineered living cells. The cells' genes have been altered to give them the capability of producing large quantities of the desired compound for use as a medical treatment. Recombinant compounds often are versions of naturally occurring substances.



• Rectum

The last 6 to 8 inches of the large intestine. The rectum stores solid waste until it leaves the body through the anus.



• Recurrence

The return of symptoms after a remission (time without symptoms). An example of this is outbreaks of herpes after periods of time without herpes lesions.



• Regimen

Regulation of diet, sleep, exercise, and manner of living to improve or maintain health.



• Reiter's syndrome

A group of symptoms which appear as a complication of nonspecific urethritis. Symptoms include urethritis, arthritis, and conjunctivitis.



• Remission

Disappearance of the signs and symptoms of cancer. When this happens, the disease is said to be 'in remission.' A remission can be temporary or permanent.



• Reproductive system

In women, the organs that are directly involved in producing eggs and in conceiving and carrying babies.



• Resectoscope

A slender telescope with an electrical wire loop or rollerball tip used to remove or destroy tissue inside the uterus.



• Resistance

Reduction in a pathogen's sensitivity to a particular drug. Resistance is thought to result usually from a genetic mutation. In HIV, such mutations can change the structure of viral enzymes and proteins so that an antiviral drug can no longer bind with them as well as it used to. Resistance detected by searching a pathogen's genetic makeup for mutations thought to confer lower susceptibility is called genotypic resistance. Resistance found by successfully growing laboratory cultures of the pathogen in the presence of a drug is called phenotypic resistance. High-level resistance reduces a drug's virus-suppressing activity hundreds of times. Low-level resistance represents only a few-fold reduction in drug effectiveness. Depending on the toxicity of the drug, low-level resistance may be overcome by using higher doses of the drug in question.



• Retrovirus

A type of virus that, when not infecting a cell, stores its genetic information on a single-stranded DNA. HIV is an example of a retrovirus. After a retrovirus penetrates a cell, it constructs a DNA version of its genes using a special enzyme, reverse transcriptase (see). This DNA then becomes part of the cell's genetic material.



• Reverse Transcriptase (RT)

A viral enzyme that constructs DNA from an RNA template, which is an essential step in the life-cycle of a retrovirus such as HIV.



• Risk factor

Something that increases the chance of developing a disease.



• RNA (RIBONUCLEIC ACID)

A single-stranded molecule composed of nucleotide sequences that is similar to the double-stranded DNA. In cells, RNA transmits the code that instructs the cells' chemical machinery to produce structural proteins and enzymes. The RNA segments in the cells represent copies of portions of the DNA sequences in the nucleus. In retroviruses (see), RNA is the sole repository of the viral genes.



• Roseola

Skin condition marked by red spots of varying sizes on the skin. Measles or German measles.