Biomedical Engineering Reference
In-Depth Information
4. Alzheimer's disease (AD) is among the leading causes of dementia in the
elderly; it is suggested that up to 70% of dementia cases are due to AD.
5. AD is incurable and its diagnosis can only be coni rmed on autopsy, by the
presence of amyloid plaque, neuroi brillary tangles, neuronal and synaptic
loss and brain atrophy in specii c areas.
6. AD is characterized by defects in the remodeling of synapses (where
nerve cells communicate), neuronal loss or dysfunction with implications
for memory and other functions, and changes in the responses of non-
neuronal cells (such as glial cells) involved in neuron survival and brain
plasticity.
7. AD pathology involves molecules critical for the regulation of synaptic
function, growth-inducing and growth-associated molecules, cytoskeletal
proteins, synaptic molecules and adhesion molecules, among others.
8. A combination of cell culture and animal studies has recently shown that
adhesion molecules play important roles in synapse initiation, maturation,
and function.
9. Functional studies of individual adhesion molecules have begun to provide
information on their role in synapse assembly and synaptic plasticity.
Definition of Terms
Adherens junctions:
Junctions characterized by the presence of transmembrane, calcium-
dependent cadherins that link to the actin cytoskeleton via catenins, and visible by
electron microscopy as a focal subsurface change in density on plasma membranes.
Alzheimer`s disease:
h e most common form of dementia. h is incurable, degenerative,
and terminal disease was i rst described by the German psychiatrist Alois Alzheimer in
1906 and was named at er him.
Amyloid peptide (Aβ)
: A peptide of 39-43 amino acids, the main constituent of amyloid
plaques in the brains of patients with Alzheimer's disease. Similar plaques appear in
some variants of Lewy body dementia and in inclusion body myositis, a muscle disease.
Aβ also forms aggregates coating cerebral blood vessels in cerebral amyloid angiopathy.
Amyloid precursor protein (APP):
A transmembrane glycoprotein of undetermined function.
h e cleavage of AAP by the β and γ secretases generates Aβ protein.
Cerebral blood l ow:
A blood supply to the brain per unit time.
Cognitive decline:
A decline in memory and cognitive (thinking) function, considered to be
a normal consequence of aging. Assessment of cognitive function among older adults
requires specialized training and rei ned psychometric tools.
Focal adhesions:
h e specii c types of large macromolecular assemblies through which both
mechanical force and regulatory signals are transmitted.
Long-term potentiation:
h e long-lasting improvement in communication between two
neurons that results from stimulating them simultaneously. Since neurons communicate
via chemical synapses, and because memories are believed to be stored within these
synapses, LTP is considered one of the major cellular mechanisms that underly learning
and memory.
