History of Multiple Sclerosis

1
History of Multiple Sclerosis
Multiple Sclerosis (MS) Lecture 12 Nov. 5, 2008

• Multiple Sclerosis, also known as MS, was given
  its name, multiple because of the numerous sites
  of demyelination and sclerosis means scarring.
• It was in Holland on August 4, 1421, that the
  earliest descriptions were seen, but the history
  of the disease really begins in the 19th century
  with the first illustrations and clear clinical
  description of the disease beginning to appear in
  1838. Even though the previous description, the
  first actual case was diagnosed in 1849.
• It was Jean-Martin Charcot who is credited with
  giving us the first signs and symptoms of
  Multiple Sclerosis.

2
MS Historical perspective
Augustus dEste suffered from MS. His illness
began before the pathology was first depicted by
Carswell in 1838 and ended with death 20 years
before the definitive description by Charcot in
1868.
3
MS Symptoms
Fatigue (MS lassitude) Problems walking
Lack of coordination Abnormal sensations
numbness or "pins and needles Impaired speech
and vision Changes in cognitive function
Bowel and/or bladder disturbances Changes in
sexual function Pain Depression and/or mood
swings
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Multiple Sclerosis
5
Section from MS patients brain

• Luxol fast blue stain reveals myelination in the
  white matter.
• Green arrows indicate demyelination (stain is
  absent).
• Red arrows, 'shadow plaques', shows demyelinated
  axons have undergone partial remyelination.
• Remyelination can occur as a spontaneous
  regenerative response in the adult human brain
  this process does not always occur. Many lesions
  remain demyelinated. Franklin RJM. Nat Rev
  Neurosci 20023705

MRI (Magnetic Resonance Imaging) detects patchy
areas of change in the CNS

6
MS displays variable disability
The plots below depict changes in degree of
disability in various forms of MS
Relapsing/remitting MS. Temporary periods of
disability followed by full or partial recovery.
Recovery is due to re-myelination of axons. The
majority of MS patients are initially diagnosed
with relapsing/ remitting MS.
Progressive relapsing MS. Significant recovery
immediately following a relapse but with a
gradual worsening of symptoms. Affects about 5
of MS patients, and may be a variant of primary
progressive MS.
Primary progressive MS. A gradual progression of
the disease from its onset with no superimposed
relapses and remissions. Onset is typically in
late thirties or early forties initial disease
activity is often in spinal cord and not the
brain.
Secondary progressive MS. A steady progression of
neurological damage with or without superimposed
relapses and minor remissions. MS patients will
have previously had Relapsing/remitting MS which
could have lasted two to forty years or more.
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Progression of disease

• What comes first?
• Inflammatory response
• Demyelination
• Axonal loss and oligodendrocyte death

Causes

• Autoimmune disease (leading theory)
• Pathogen mediated
• Genetics component
• Damage to blood-brain-barrier

Main points
In CNS, immune system attacks myelin, producing
multiple scarring and plaques after BBB has been
compromised Synaptic transmission is
interrupted To remyelinate, Schwann cells
might be used or stem cells developed into
olgliodendrocytes someday, but for now, reducing
inflammation and therapy help
8
MS three components
Oligodendrocyte death also occurs in some MS
patients
9
MS is an Immune-Mediated Disease
BBBblood-brain barrier APCantigen-presenting
cell
Immune system T cells normally in the bloodstream
become activated against components of the brain
myelin. They cause local inflammation in
scattered regions of the brain and spinal cord
once they cross the barrier between the
bloodstream and CNS.
10
Multiple Sclerosis
MS is currently thought to be an autoimmune
disease. Autoimmunity body's own immune system
mistakenly attacks the body's own tissue and
causes damage. Symptoms gt 80 disturbances of
sensitivity, paralysis
Myelin sheath (fatty layer) covers neurons, and
helps neurons carry electrical signals. MS causes
myelin degradation and scar-like tissue forms,
causing problems in signal transmission between
neurons.
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Oligodendrocytes make myelin for neurons
A single oligodendrocyte may support myelin
internodes for 60 or more neighboring axons.
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Schwann cells make myelin for peripheral neurons
Myelinated nerves can conduct impulses at High
speed
The dendrites and axons of sensory neurons and
motor neurons that lie outside of the CNS in the
PNS are myelinated. Myelin sheaths are formed by
Schwann Cells. Schwann cells form multiple layers
of membrane around the neuron and insulate it. In
between the areas of myelin sheath, Nodes of
Ranvier or bare patches exist. The nerve impulse
or action potential will jump from node to node
greatly increasing the speed of nerve
transmission. This node to node transmission,
called saltatory conduction, can produce
transmission speeds of up to 200 m/s (448 mph
720 kmph) and explains the speed at which we can
react to potential stimuli. Internodes are up to
1mm and Ranvier nodes 1µm.
http//www.coolschool.ca/lor/BI12/unit12/U12L03.ht
m
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Myelin structure

• Myelin is an electrically-insulating phospholipid
  layer that surrounds the axons of neurons.
• Myelinated axons are white in appearance, "white
  matter" of the brain.
• Composition
• Myelin contains 70 of brain cholesterol
• 70-80 lipid
• galactocerebroside a glycolipid and
  hydrocarbon chains of sphingomyelin serve to
  strengthen the myelin sheath.
• 20-30 protein
• Myelin basic protein (MBP),
• Myelin oligodendrocyte glycoprotein,
  (MOG)
• Proteolipid protein (PLP)

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Myelin structure
Myelin basic protein (MBP), proteolipid protein
(PLP), cyclic nucleotide phosphodiesterase (CNP),
and myelin-associated glycoprotein (MAG).
Laule Neurotherapuetics, 4460(2007)
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Myelin sheath and neuregulins
B In mice expressing a reduced amount of Nrg1
type III, the myelin sheath is thinner than
normal and the speed of electrical impulses is
reduced. In contrast, mice that over-express Nrg1
type III produce myelin sheaths of greater
thickness than those of wild-type mice.
A The myelin sheath (blue) surrounding axons
(yellow) is produced by glial cells (Schwann
cells in the PNS, oligodendrocytes in the CNS).
These cells produce large membranous extensions
that ensheath the axons in successive layers that
are then compacted by exclusion of cytoplasm
(black) to form the myelin sheath. The thickness
of the myelin sheath (the number of wraps around
the axon) is proportional to the axon's diameter
(g ratio). The transmembrane protein neuregulin-1
(Nrg1 type III, red) expressed by the axon acts
as a biochemical signal that instructs Schwann
cells in the PNS to form a myelin sheath of the
correct thickness.
ffrench-constant Science, 304688 (2004)
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Hypermyelination
What the physiological or pathological
consequence of hypermyelination is? Will the
conduction gets affected? No there is no real
increase of conduction velocity in the mice we
checked. That is in agreement with theoretical
models published in the 60s. Klaus-Armin
Nave Are there any pathological consequences of
hypermyelination? Difficult to say as NRG1
over-expression under control of the ThyI
promoter has some consequences for synaptic
functions and muscle development. Klaus-Armin Nave
Michailov GV, Science 2004304700.
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Myelin sheath and neuregulins

• In peripheral nerves, neural crestderived
  Schwann cell progenitors (1)
• proliferate and populate axon bundles. Immature
  Schwann cells (2) face two choices
• stay tightly associated with several axons to
  form a Remak bundle (3),
• single out larger axons and differentiate into
  myelinating Schwann cells (4).

• Entire Schwann cell developmental path and
  myelination is remote controlled by the neurons
  through expression of the neuregulin-1 (5) on the
  axonal surface

Abnormalities in nerves with altered NRG1 type
III levels. Alterations in axon ensheathment and
myelination as a function of NRG1 type III levels
are illustrated based on in vivo and in vitro
analysis. Taveggia Neuron 47681 (2005)
Nave Nat NeuroSci, 81420 (2005)
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Role of NRG1 in neural development
a Neuregulin 1 (NRG1) is released from neurons to
promote the formation and maintenance of radial
glial cells necessary for the migration of
neurons from ventricular zones to the pial
surface. b Tangential migration of GABA-ergic
interneurons requires NRG1 in the cortical
region c Myelination and ensheathment of
peripheral nerves are controlled by NRG1 produced
in axons. d NRG1 from axons might regulate
oligodendrocyte development differentiation in
the CNS. e NRG1 is necessary for the formation
of neuromuscular junctions (NMJs). f NRG1
stimulates CNS synapse formation.
DT, dorsal thalamus GP, globus pallidus LGE,
lateral ganglionic eminence MGE, medial
ganglionic eminence.
Mei L, Nat Rev Neurosci 20089437
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Myelin lipids

• Two major classes of lipid found in the myelin
  sheath
• PC (a glycerophospholipid), is based on glycerol
  (shown in red).
• Galactocerebroside and galactosulphocerebroside
  are based on a long-chain sphingosine (also shown
  in red)
• Galactosulphocerebrosides are sulphated (shown in
  green) at carbon three of the galactose ring.

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Myelin composition
Plasmalogens are ether lipids made in peroxisomes
21
The Nerve Impulse

• At each node of Ranvier, the action potential is
  regenerated by a chain of positively charged ion
  pushed along by the previous segment.
• Saltatory conduction (jumping of the action
  potential from node to node).
• Provides rapid conduction of impulses
• Conserves energy for the cell

An action potential is a wave of electrical
discharge that travels along the membrane of a
cell. Action potentials are an essential feature
of animal life, rapidly carrying information
within and between tissues.
Fig. 2-19, p. 46
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Role of sodium channels in the axon degeneration
cascade
A number of factors contribute to energy failure
and subsequent rundown of the Na, K-ATPase
pump, with subsequent depolarization and loss of
capacity to maintain transmembrane ion gradients.
The depolarization activates sodium channels
(e.g. Nav 1.6), which provide a route for
persistent sodium influx. This process, in turn,
drives the Na/Ca2 exchanger to operate in a
calcium-importing mode. The rise in intracellular
calcium induces a further increase in calcium
levels via calcium-induced calcium release.
Increased intra-axonal calcium also injures
mitochondria, and activates nitric oxide synthase
and harmful proteases and lipases.
Waxman Nat Clin Pract Neurol (2008) 4, 159
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Voltage gated Na channels and MS

• Voltage-gated sodium channels can contribute to
  axonal injury in MS by providing a pathway for
  sustained Na influx that drives the Na/Ca2
  exchanger to import Ca2 to axons
• Sodium channel blockers protect axons from
  degeneration in several in vitro models of axonal
  injury, and they prevent axon degeneration,
  maintain impulse conduction, and improve clinical
  status in EAE, a mouse model of MS
• Sodium channels regulate the function of
  macrophages and microglia, so, in addition to a
  direct protective effect on axons, Na channel
  blockers might have an immunomodulatory action
• Sudden withdrawal of the Na channel blockers
  phenytoin and carbamazepine from mice with EAE
  results in acute clinical exacerbation,
  accompanied by increased inflammatory infiltrate
  within the CNS
• Clinical studies should monitor patients closely
  both in terms of neurological function and axonal
  loss and with respect to immune and inflammatory
  status
• If withdrawal of the Na channel blocker
  (carbamazepine or phenytoin) is necessary in
  patients with MS, these medications should be
  discontinued via a gradual taper.

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Peroxisomes
Use O2 and H2O2 to perform the oxidation
reactions. They may resemble lysosomes, however,
they are not formed in the Golgi
complex. Peroxisomes are present in myelin
sheaths surrounding axons and are also present in
the axons. Also shown are nodes of Ranvier, which
are small unmyelinated axonal regions. Peroxisomes
are important organelles for detoxification of
ROS Plasmalogens (ether lipids) an essential
component of myelin are made in peroxisomes
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Peroxisomal deficiency causes axonal degeneration

• Progressive axonal loss is a major cause of
  clinical impairment in MS
• Myelinating oligodendrocytes may provide
  metabolic support for axons and detoxification of
  ROS
• Peroxin-5 (Pex5), the peroxisomal targeting
  signal type-1 receptor, is essential for
  importing majority of proteins into the
  peroxisomal matrix
• Defect in PEX5 (a peroxin, proteins essential for
  peroxisomal protein import) can affect the enzyme
  transport to peroxisomes
• Null mutations of Pex5 are lethal in patients
  with Zellweger syndrome
• In a mouse model, Pex5 gene was selectively
  inactivated in oligodendrocytes
• Absence of functional peroxisomes from
  oligodendrocytes caused widespread axonal
  degeneration and subcortical demyelination

Kassmann CM, et al. Nat Genet 200739969
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Cholesterol synthesis
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Cholesterol and myelination

• Inactivation of cholesterol synthesis via
  deletion of gene for HMG-CoA or squalene synthase
  is embryonically lethal
• Mutant mice were created in which squalene
  synthase (SQS) was inactivated in
  oligodendrocytes via conditional mutation of the
  gene (SQS mutants)
• SQS mutant mice
• Developed motor function deficits at 2 weeks of
  age, time of peak CNS myelination
• 1/3 of mice died between 20 and 30 days, however,
  mutants that survived past one month rarely died
  prematurely
• At day 20, spinal cord white matter was nearly
  devoid of myelin
• Corpus callosum and cerebellar white matter had
  marked myelination reduction
• Grey matter, however, myelination was nearly
  normal
• By day 100, surviving mutant mice showed no
  substantial difference in myelination compared to
  wild type
• Conclusions
• Normally, oligodendrocytes synthesize the
  cholesterol for myelination
• Mutant oligodendrocytes could overcome the defect
  in cholesterol synthesis through transfer from
  neighboring wild-type cells such as astrocytes
• Transfer of cholesterol was less effective than
  synthesis and limited myelination
• Cholesterol is essential and rate-limiting in
  myelin formation

Saher G, Nat Neurosci 20058468
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Lyso-PC (LPC) triggers demyelination

• Myelin degradation was artificially induced with
  lyso-phosphatidylcholine (LPC)
• 15-min after LPC injection, imaged real-time
  using a new imaging technique Coherent
  Anti-stokes Raman Scattering microscopy (CARS).
• Recorded real-time in live mice an influx of Ca2
  as the myelin began to degrade.
• This can further accelerate activation of PLA2
  that hydrolyzes PC to LPC ArAc, amplifying the
  effect and further degrading the myelin.
• Ca2 influx also activated calpain to degrade
  myelin proteins
• This insight could promote early detection of
  conditions such as multiple sclerosis.
• LPC induces macrophage recruitment and activation
  

Normal
LPS
Fu Y et al J Neurosci Res. 2007 85 2870.
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Lyso-PC (LPC) triggers demyelination
LPC 20 µg injected into spinal cord acute
demyelination
Intact demyelinated
LPC induces Ca2 influx, which can stimulate
cPLA2 (enhances PC hydrolysis) and calpain
breaks down myelin lipids and proteins. Calpain
or cPLA2 inhibitors significantly reduced
demyelination.
Fu Y et al J Neurosci Res. 2007 852870
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EAE is model for MS,.. but

• Experimental autoimmune encephalomyelitis (EAE)
  is the experimental model for MS
• cPLA2 hydrolysis products LPC (demyelination,
  chemokine/cytokine expression) and ArAc
  (pro-inflammatory)
• EAE was induced in female C57/BL6 mice by
  injecting myelin oligodendrocyte glycoprotein
  together with Freund's adjuvant (inactivate
  mycobacterium tuberculosis emulsified in mineral
  oil, used as an immunopotentiator, BBB breaker).
  cPLA2 knockout mice are resistant to MS

MS and EAE differences
Sriram S, Ann Neurol 200558939
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cPLA2a null mice are resistant to EAEIL-12
treatment reverted the resistance

• EAE was induced in mice by myelin oligodendrocyte
  glycoprotein (MOG) immunization.
• Th1 cell differentiation is impaired in cPLA2a-/-
  animals
• T cells from MOG-immunized cPLA2a-/- mice
  produced less interferon-gamma (IFN-gamma) and
  TNF-a compared to cPLA2a/-
• exposure of cultured cPLA2a-/- T cells to
  interleukin-12 (IL-12) partially restored
  production of IFN-gamma but not TNF-a.
• IL-12 is potent inducer of Th1 differentiation
• IL-12 administration along with MOG immunization
  made cPLA2a -/- susceptible to EAE
• Does cPLA2 regulate IL-12 expression through LPC?
• PLA2 product lyso-PC (LPC) induces IL-12 in
  peripheral blood mononuclear cells (Guo-Zhong,
  Atheroscler. 200316977)
• Besides release of Ca2 and activation of calpain
  and caspases, IL-12 induction may enhance the
  myelin degradation
• LPC induces macrophage recruitment and activation

Marusic J Exp Med. 202841 (2005)
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cPLA2a null mice are resistant to EAE

• EAE was also induced by the passive transfer of T
  cells specifically reactive to these myelin
  antigens from immunized syngenic donor animals
  (adoptive transfer)
• Helper T (Th) cells have no phagocytic activity
  but are involved in activating and directing
  other immune cells Th1 cells stimulate
  macrophage phagocytosis, Th2 cells stimulate B
  cell antibody production
• Injection of myelin-specific Th1, but not Th2,
  cells induces EAE
• EAE is considered the prototype for
  T-cell-mediated autoimmune disease
• cPLA2a -/- mice were resistant to induction of
  EAE compared to cPLA2a/-
• Transfer of T cells from MOG-immunized cPLA2a -/-
  mice induced less severe EAE in wild-type mice,
  indicating cPLA2a has a role in EAE induction
• T cells from MOG-immunized wild-type mice induced
  less severe EAE in cPLA2a -/- mice, indicating
  that cPLA2a has a role in the effector phase of
  EAE
• Besides MS cPLA2 null mice are resistant to
• Stroke (Bonventre Nature 1997) Parkinsons
  disease (MPTP model) AD
• C57BL6/SV129 mice naturally lack sPLA2IIA gene

Marusic J Exp Med. 202841 (2005)
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sPLA2 activity in EAE and MS

• sPLA2 activity increased in the urine after the
  induction of EAE in rat
• Nonapeptide CHEC-9, an uncompetitive inhibitor of
  sPLA2, reduced the activity.
• CHEC-9 reduced the clinical symptoms of EAE and
  presence of macrophages/activated microglia (60
  reduction in ED1 ve cells).
• MS patients with active (relapsing) disease
  showed 6-fold elevated urinary levels of sPLA2,
  4-fold increase in remission compared to healthy
  controls.

Uncompetitive inhibition takes place when an
inhibitor binds only to the enzyme-substrate
complex (not to the free enzyme). CHEC-9
(CHEASAAQC) is a putative sPLA2 inhibitor that
has been identified as an internal fragment of
the survival-promoting, anti-inflammatory
polypeptide DSEP/Dermcidin/PIF. Dermcidin gene
encodes a secreted protein that is subsequently
processed into mature peptides of distinct
biological activities. The C-terminal peptide is
constitutively expressed in sweat and has
antibacterial and antifungal activities. The
N-terminal peptide, also known as diffusible
survival evasion peptide, promotes neural cell
survival under conditions of severe oxidative
stress.
Cunningham J Neuroinflamm. 2006
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Cuprizone causes demyelination
A

• Copper chelator cuprizone is used as a model for
  demyelination/remyelination.
• Standard protocol is 6 wks cuprizone diet (0.2)
  to induce demyelination, followed by normal diet,
  allowing remyelination.
• Cuprizone administration specifically leads to
  death of oligodendrocytes

B

• Cuprizone administration leads to
• Reduction in activities of brain mitochondrial
  cytochrome oxidase and monoamine oxidase.
• Cuprizone-induced copper deficit might be
  detrimental to mitochondrial function in brain,
  as well as in liver.
• It is believed that disturbance of energy
  metabolism in oligodendroglia leads to
  demyelination
• Administration of copper does not reduce
  cuprizone toxicity

• T2-weighted magnetic resonance imaging (MRI) of
  control C57BL/6 mouse brain. The white arrow
  indicates the area for corpus callosum.
• T2-weighted MRI of mouse brain from C57BL/6 mouse
  after 5 weeks of cuprizone treatment, showing
  demyelination and an enlarged ventricular system.
  The white arrow indicates the area for corpus
  callosum.

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OxPC in multiple-sclerosis brains
EO6 antibody recognizes specifically OxPC and
OxPC-modified protein(s) Macrophage/microglia
activation induces oxidative stress leading to
oxidation of PC
Qin J J Neurosci Res 200785977
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Drug development design or accident
All drugs (and many drugs for other diseases) in
common use today are derivatives of treatments
that were originally discovered by accident. None
were developed based on a scientific
understanding of the causes or pathophysiology of
mental illness, neurodegeneration or CNS
injury. Nature Med Oct 2007
37
Some immuno-modulatory approaches to MS
PML ( Progressive Multifocal Leucoencephalopathy
white matter disease of the brain ) is a viral
infection
Friese MA, Brain. 2006 129 1940
38
Treatments for MS.
Glatiramer acetate (Copaxone or Copolymer 1).
Immunomodulator therapy for relapsing-remitting
MS. Glatiramer acetate is a random polymer (6.4
kD) composed of 4 amino acids found in MBP.
Administration of glatiramer shifts the T cells
from pro-inflammatory Th1 cells to regulatory Th2
cells, suppressing inflammation. Given its
resemblance to MBP, glatiramer acts as a decoy,
diverting an autoimmune response against myelin.
The integrity of the BBB, however is not
affected. Natalizumab (Tysabri) is a humanized
monoclonal antibody against the cellular adhesion
molecule a4-integrin.
Fingolimod (FTY720, an analog of myriocin/ISP-1)
is phosphorylated by sphingosine kinase 2 and
acts as a sphingosine-1-phosphate receptor 1
modulator. It is currently in phase III clinical
trials as monotherapy for relapsing-remitting MS
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Drugs for MS treatment in clinical trials
Linker RA Trends Pharmacol Sci 2008In Press
40
Future considerations for improving animal models
for MS

• Validate therapeutic effect in more than one
  model
• Consider dissimilarities in immune systems of
  rodents vs humans
• Consider treatment after disease onset
• Record disease course for as long as possible
  (feasible)
• Establishment of spontaneous disease models
• Establishment of a two-stage disease course in
  EAE (first relapsingremitting, later
  chronic-progressive)
• Incorporate human disease risk factors
• Incorporate human immune system and modifying
  human CNS factors

Friese MA, Brain. 2006 129 1940
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End of Multiple Sclerosis Lecture