Server: Microsoft-IIS/3.0 Date: Thu, 18 Dec 1997 17:56:21 GMT Content-Type: text/html Accept-Ranges: bytes Last-Modified: Wed, 12 Nov 1997 19:04:45 GMT Content-Length: 5941 NTI: GLOSSARY

Glossary


cerebral edema - Swelling in the brain, commonly associated with brain tumors, head injury and stroke. Swelling within the closed space of the skull can damage brain tissue and restrict blood flow to the brain.

anti-edema effect - Reduction of fluid buildup and associated swelling in damaged body tissues.

calcium channel - A doughnut-shaped protein imbedded in the membrane of neurons (see neuron). Charged calcium molecules, called ions, flow through the channel into the neuron, causing the neuron to change electrical charge and fire. When too much calcium enters the neuron, however, it may be injured. The NMDA receptor controls a calcium channel.

channel blocker - Compound which remains for a long period of time in a receptor channel or prevents the channel from opening. Such compounds may interfere with normal receptor activity.

dementia - A condition common in Alzheimer's patients and patients with AIDS, characterized by loss of coordination, forgetfulness, confusion, changes in personality, and inability to concentrate.

edema - The accumulation of fluid in damaged tissues, causing painful and dangerous swelling

excitotoxicity - A cascading cycle of neuronal injury and death in the central nervous system. Injured neurons release excessive amounts of glutamate which cause toxic levels of calcium flow into neighboring cells through NMDA receptor calcium channels. These cells swell and rupture, releasing more glutamate into the cellular environment (see "neuron" and "glutamate").

glutamate - The principal excitatory neurotransmitter in the brain. Neurons release glutamate in order to excite neighboring cells; they receive a "wake up" signal when glutamate binds with NMDA receptors imbedded in their cell membrane (see NMDA receptor and neuron). When excessive levels of glutamate are present, neurons are overexcited and suffer injury and death.

intracranial pressure - A dangerous condition which frequently develops after a severe head injury, often associated with cerebral edema. Fluid accumulates in the brain, causing the brain to swell and press against the skull. Brain swelling is more dangerous than other types of swelling in the body because the skull cavity is an enclosed space.

ischemia - Prolonged absence of blood flow to an area in the body (stroke is ischemia to the brain, heart attack is ischemia to the heart).

modulator - Compound which acts like a "volume control" to regulate a natural process in the body, such as receptor activity. The company believes that Memantine is a modulator of the NMDA receptor calcium channel because it regulates the flow of calcium ions through the channel (see "calcium channel").

neurological - Pertaining to the function of the nervous system (as in neurological disease).

neuron - Nerve cell which generates and conducts electrical signals. Neurons are concentrated in the brain and spinal cord.

neuropathic pain - Persistent, chronic pain without an obvious cause. Often associated with damage to nerves or nerve fibers. Such pain in the hands and feet is associated with the transmission of abnormal pain signals from injured peripheral nerves to neurons in the brain and spinal cord.

neuroprotection - The effect of potential drugs which may inhibit nerve cell injury and death. Usually refers to protection against nerve cell death as a result of glutamate-induced overexcitation (see glutamate). More generally, refers to protection against nerve cell death in the aftermath of a stroke or injury to the brain.

NMDA receptor - A protein molecule imbedded in the membrane of nerve cells which binds with glutamate, the principal excitatory neurotransmitter in the brain (see glutamate).

peptide - A molecule similar to but smaller than a protein. Peptides are made of amino acids, the building blocks of proteins. Many peptides occur naturally in the body, including a variety of hormones.

peritumoral brain edema - Swelling in the brain caused by a tumor. Plasma fluids and white blood cells build up in the tissues surrounding the tumor, causing life-threatening pressure within the skull.

traumatic brain injury (TBI) - A severe head injury of sufficient force to bruise the brain and generated edema. TBI is commonly associated with concussion and reduction of blood flow to the brain (ischemia).

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