Module 2 Neuroanatomy

What does it mean where there is a dark-line and a light-line in electron microscope images of a cross-section of myelin?

dark-line = where the cytoplasm will wrap and squeeze itself

light0line = where the extracellular matrix is compressed together

What are some characteristics of myelin associated glycoprotein (MAG)?

protein that is uniquely expressed by oligodendrocytes in CNS myelin

cell-adhesion molecule, useful during myelin "wrapping"

help form interaction between myelin membrane and oligodendrocyte

What are some characteristics of CNP?

protein that is uniquely expressed by oligodendrocytes in CNS myelin

interact with axons - if absent, oligo will lose supportive function which leads to degeneration of neuron

biomarker for oligo

What are some characteristics of proteolipid protein (PLP)?

protein that is uniquely expressed by oligodendrocytes in CNS myelin

hold adjacent myelin membrane sheets together - forms a bond

needed for developing of oliogodendrocytes

mutation = jumpy mouse --> defective myelin where it isn't wrapped very tight

What is the human leukodystrophy associated with the gene mutation that normally codes for proteolipid protein?

Pelizaeus-Merzbacher disease - progressive loss of white matter, CNS can't develop properly; causes neurological and developmental issues, motility, feeding, GI

What is the animal model of MS, experimental allergic encephalitis (EAE)?

inject into the blood stream - develop immune response and immune cells appear and travel out of blood stream and activate to destroy MBP, therefore destroying CNS myelin

What are the four proteins uniquely expressed by oligodendrocytes that might be used to positively identify a brain tumor as an oligodendroglioma?

MAG, Wolfgram, PLP, MBP

What is the human peripheral neuropathy associated with a gene mutation in the PMP-22 gene?

charcot marie tooth disease

Describe the cellular composition of the blood brain barrier?

astrocyte feet will almost "attach" to outside of BV so we can be specific about what is let in --> BV forms attachment to astrocyte feet

What is reactive astrogliosis in the CNS?

they repair damaged CNS tissue --> will migrate to areas of injury to fill in the space after trauma/injury

What is a major function of radial glial cells in the embryonic brain?

guidance for neuronal migration during development; guiding mechanism for developing neuron to form the layers of cerebral cortex

What is the function of the astrocyte in the tri-parte synapse?

reuptake of NT

What proteins are uniquely expressed by astrocytes that might be used to positively identify an astrocytoma brain tumor and/or as a biomarker for injuries to the brain?

glial fibrillary acidic protein (GFAP) --> decreased for protoplasmic astrocytes, increased for fibrous astrocytes

biomarkers of these = TBI, astrocytoma, glioblastoma

increased levels = injury/trauma occurred

the more there is, the more severe it is

less = recovery of trauma

What is the function of satellite cells?

support neuronal cell bodies in dorsal root ganglia

What is the origin of oligodendrocytes?

neuroectoderm

What protein regulates the g-ratio in normal range? What happens when there is too much or too little myelin?

neuroregulin protein; too little = neuromuscular disorders such as MS

regulates how many wraps of myelin there is around an axon

What are the functions of these two lipids in the myelin surrounding an axon?

form calcium bridge which helps to maintain structural integrity of myelin wrapping

What human leukodystrophy is associated with a deletion in the gene that normally codes for the enzyme, arylsulfatase A?

metachromatic leukodystrophy --> genetic mutation with death of white matter in the CNS, causing neurological deficits, hind limb paralysis in animal models

What is the approach for treating people with metachromatic leukodystrophy?

harvest stem cells that are normal and have viral vector - put them into human and bone marrow will produce normal gene, which will halt the disease

What is the human leukodystrophy that is associated with a defect in metabolism of very long chain fatty acids?

adrenoleukodystrophy - degeneration of white matter in CNS and the adrenal gland that causes behavior, sensory, and physical issues

Which human peripheral demyelinating disorder is modeled in animals with experimental allergic neuritis?

Guillain-Barre

What type of astrocyte contains less glial fibrillary acid protein (GFAP) and is principally found in gray matter?

protoplasmic astrocytes

What are the three cellular elements forming the "tri-parte" synapse?

astrocyte, pre and post synaptic neuron

What major part of the human brain develops aa medulloblastoma and what is the malignant cell?

cerebrum, external granule cells

PET scan

electron emission from radioactive substrate, physical or metabolic processes

What is the origin of Schwann cells?

neural crest

What is the location of Schwann cells?

PNS

What are the functional characteristics of Schwann cells?

myelinate axons in the PNS by wrapping around them, only can do one axon at a time; one Schwann cell per internode of myelin

Internode

segment of an axon that is covered in myelin; only one Schwann cell

Node of Ranvier

segment of an axon that is unmyelinated, where ion transports are present

Where are satellite cells located?

PNS - cell bodies of dorsal root ganglia

What is the location of oligodendrocytes?

CNS

What are the functional characteristics of oligodendrocytes?

myelinate more than one axon at a time; they have multiple processes that go to different axons so they can myelin up to at least 40 at a time

What factors are being compared in the g-ratio?

axon diameter / width of myelin

Is the g-ratio maintained during the process of remyelination of axons affected by MS?

as long as there is an axon present and the oligodendrocytes are unharmed and working, then remyelination of axons can occur

What is the relationship of the organic structure sulfatide and galactorcerebroside?

they have the same molecular structure (galactolipid) besides for one piece

What are the two approaches to treating a person with adrenoleukodystrophy?

Lucas oil and stem cell/gene therapy

What are some characteristics of myelin based protein (MBP)?

protein that is uniquely expressed by oligodendrocytes in CNS myelin

cytoplasmic compartment - keep cytoplasmic forces together, compaction; dark line seen

What is a proposed mechanism of action of how the drug, Copaxone, might work to decrease sensitized T-lymphocytes from attacking CNS myelin in a person with MS?

it resembles myelin based protein --> go into blood stream and the t-cells want CNS MBP, but this is already in blood stream, so they will bind to this instead and not CNS MBP

What are some characteristics about proteins expressed in PNS myelin?

they are similar to CNS proteins but function in the PNS

What is the human peripheral neuropathy associated with a gene mutation in the gene coding for P0 protein?

Guillain-Barre

What type of astrocyte contains more GFAP and is principally found in white matter?

fibrous astrocytes

What are some normal functions of the blood brain barrier?

controls what comes in and out of brain --> drug, nutrients, etc

Where are ependymal cells located in the brain and spinal cord?

brain: ventricles - choroid plexus

spinal cord: central canal

Where are ependymoma brain tumors most commonly found in the CNS?

ventricles of the brain --> cells lining open cavities

children = fourth ventricle

adults = SC

What are the characteristics of high grade brain tumors?

high cellularity, fast growing, highly malignant, decreased survival rates

What are the characteristics of low grade brain tumors?

low cellularity, slow growing, less malignant, increased survival rates

What is the degree of aggressiveness of a glioblastoma multiformes and a patient's prognosis compared to low-grade brain tumors?

high malignancy, 7-12 month survival after diagnosis, only 10% alive after 2 years compared to low malignancy for low grade tumors

What is the significance of the ring-enhancing mass found on a CT scan of the human brain?

With contrast, the edge is brighter and enhances the lesion that is the result of necrosis of center of lesion and neovascularization without BBB at the edge of the periphery

CT scan

tissue densities, seeing tumors, vascular abnormalities/traumas

MRI

amazing detail, differentiate white vs. gray matter

Angiogram

openness, location, size, flow pattern of BV

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