Category: Aq-Ar

A class of viruses transmitted to humans by arthropods such as mosquitoes and ticks. The first two letters of the words arthropod’ and borne, make up the ‘arbo’ that now designates this group of viruses as arthropod-borne. The name arbovirus was coined in part by Dr. William C. Reeves (1916-2004) to connote the class of viruses carried by insects and…

Inflammation of the brain (encephalitis) caused by infection with an arbovirus, a virus transmitted by a mosquito, tick or another arthropod. Infection of vertebrates, including humans, occurs when an infected arthropod feasts upon them for a blood meal. There are a number of types of arboviral encephalitis. Those that occur in the US include LaCrosse…

An arrangement in which the patient waives the right to sue the physician and, instead, agrees to submit any dispute to arbitration. Arbitration agreements are legal and binding. The arguments in their favor are that, for patients, the case can be settled faster, and more money can go to the patient (rather than to a…

An abnormal and persistent fear of spiders. Sufferers from arachnophobia experience undue anxiety, even though they realize that the risk of encountering a spider and being harmed by it is small or nonexistent. They may avoid going barefoot and may be especially alert when taking showers or getting into and out of bed.

Inflammation of the middle layer of membranes covering the brain and spinal cord. Arachnoiditis can occur as a complication of procedures such as myelograms, spinal operations, epidural steroid injections, and injury to the spine.

Long spider-like fingers and toes, a frequent finding in Marfan syndrome, a heritable disorder of connective tissue. “Arachnodactyly” is derived from the Greek “arachne” (spider) and “daktylos” (finger). The Greek word was derived from the name “Arachne,” a maiden in Greek mythology whom the goddess Athena turned into a spider after the girl, a skilled weaver,…

All of the genetic information contained in Arabidopsis thaliana, a plant belonging to the mustard family. The genomes of particular nonhuman organisms such as Arabidopsis have been studied for a number of reasons including the need to improve sequencing and analysis techniques. These nonhuman genomes also provide powerful sets of data against which to compare…

A plant belonging to the mustard family. Arabidopsis was the first plant genome to be sequenced, and is a popular tool for understanding the molecular biology of many plant traits, including flower development and light sensing. See also: Arabidopsis thaliana genome.

In medicine, humor refers to a fluid (or semifluid) substance. Thus, the aqueous humor is the fluid normally present in the front and rear chambers of the eye. It is a clear, watery fluid that flows between and nourishes the lens and the cornea; it is secreted by the ciliary processes. The humors were part of an ancient…

A canal that communicates between the third and fourth ventricles in a system of four communicating cavities within the brain that are continuous with the central canal of the spinal cord. The four ventricles consist of the two lateral ventricles, the third ventricle and the fourth ventricle: Lateral ventricles: The lateral ventricles are in the cerebral hemispheres.…