Multiple Sclerosis A Research Paper

This essay has a total of 4246 words and 18 pages.

Multiple Sclerosis A Research Paper



Introduction
Multiple Sclerosis
By:
Stephanie ****

Multiple Sclerosis (MS) is a chronic, often disabling disease that randomly attacks the
central nervous system (brain and spinal cord). The progress, severity and specific symptoms of
the disease can not be predicted; symptoms may range from tingling and numbness to paralysis
and blindness. MS is a devastating disease because people live with its unpredictable physical and
emotional effects for the rest of their lives.
MS is a well-known disease, but poorly understood. In the United States there are
approximately 200 new cases diagnosed each week; MS is a common disease and not always
caused by genetics. Therefore, I feel we all need to have a better understanding of this disease that
has no cure yet. I hope to make MS more understanding in my paper.
In my paper I will explain what MS is, who gets MS, what MS has to do with the
metabolism, some new techniques being used to pinpoint genetic factors, what some of the
symptoms of MS is, and some treatments for MS.

Multiple Sclerosis

Multiple sclerosis (MS) is a progressive disabling illness that affects nerve cells in the brain and spinal
cord (Bernard). Under normal conditions these nerve cells are surrounded by an insulating sheath made of fatty
"myelin," which speeds the passage of nerve impulses. In MS, this myelin sheath is inflamed or damaged,
disrupting nerve impulses and leaving areas of scarring (sclerosis). The disruption of nerve signals within the
brain and spinal cord causes a variety of symptoms that may affect vision, sensation, and body movements. “These
symptoms usually wax and wane through a series of relapses (episodes when symptoms suddenly get worse)
alternating with remissions (periods of recovery, when symptoms improve).” (Brunnscheiler) For many patients,
a long history of MS attacks over several decades leads to slowly progressing disability, but for others the
disability is more rapid and severe.
MS is a life-long chronic disease diagnosed primarily in young adults who have a virtually normal life
expectancy. Consequently, the economic, social, and medical costs associated with the disease are significant.
Estimates place the annual costs of MS in the United States in excess of $2.5 billion. (Melvin)
No one knows exactly how many people have MS. It is believed that, currently, there are approximately
250,000 to 350,000 people in the United States with MS diagnosed by a physician. (Boyden) This estimate
suggests that approximately 200 new cases are diagnosed each week.
Also, MS is the most common nerve disease to develop in young persons after birth, and it affects over 1
million young adults worldwide. “Close relatives of a person with MS are 8 times more likely than average to
develop the disease themselves, and children of a person with MS run 30 to 50 times the average risk.”
(Waxman)
Most people experience their first symptoms of MS between the ages of 20 and 40, but a diagnosis is often
delayed. This is due to both the transitory nature of the disease and the lack of a specific diagnostic test--specific
symptoms and changes in the brain must develop before the diagnosis is confirmed. (Health Central)
Although scientists have documented cases of MS in young children and elderly adults, symptoms rarely
begin before age 15 or after age 60. Whites are more than twice as likely as other races to develop MS. In general,
women are affected at almost twice the rate of men; however, among patients who develop the symptoms of MS at
a later age, the gender ratio is more balanced. (Waxman)

To understand what is happening when a person has MS, it is first necessary to know a little about how
the healthy immune system works. The immune system -- a complex network of specialized cells and organs --
defends the body against attacks by "foreign" invaders such as bacteria, viruses, fungi, and parasites. It does this
by seeking out and destroying the interlopers as they enter the body. Substances capable of triggering an immune
response are called antigens. (Hofmann)
“The immune system displays both enormous diversity and extraordinary specificity.” (Hofmann) It can
recognize millions of distinctive foreign molecules and produce its own molecules and cells to match up with and
counteract each of them. In order to have room for enough cells to match the millions of possible foreign
invaders, the immune system stores just a few cells for each specific antigen. When an antigen appears, those few
specifically matched cells are stimulated to multiply into a full-scale army. Later, to prevent this army from
overexpanding, powerful mechanisms to suppress the immune response come into play.
T-cells, so named because they are processed in the thymus, appear to play a particularly important role in
MS. They travel widely and continuously throughout the body patrolling for foreign invaders. In order to
recognize and respond to each specific antigen, each T cell's surface carries special receptor molecules for
particular antigens.
T cells contribute to the body's defenses in two major ways. “Regulatory T cells help orchestrate the
elaborate immune system. “ ( Kaser) For instance, they assist other cells to make antibodies, proteins programmed
to match one specific antigen much as a key matches a lock. Antibodies typically interact with circulating
antigens, such as bacteria, but are unable to penetrate living cells. Chief among the regulatory T cells are those
known as helper (or inducer) cells. “Helper T cells are essential for activating the body's defenses against foreign
substances. “ (Kaser) Yet another subset of regulatory T cells acts to turn off, or suppress, various immune
system cells when their job is done.
Killer T cells, on the other hand, directly attack diseased or damaged body cells by binding to them and
bombarding them with lethal chemicals called cytokines. ( Kaser) Since T cells can attack cells directly, they
must be able to discriminate between "self" cells (those of the body) and "nonself" cells (foreign invaders). To
enable the immune system to distinguish the self, each body cell carries identifying molecules on its surface. T
cells likely to react against the self are usually eliminated before leaving the thymus; the remaining T cells
recognize the molecular markers and coexist peaceably with body tissues in a state of self-tolerance.
“In autoimmune diseases such as MS, the detente between the immune system and the body is disrupted
when the immune system seems to wrongly identify self as nonself and declares war on the part of the body
(myelin) it no longer recognizes.” (Hauser) Through intensive research efforts, scientists are unraveling the
complex secrets of the malfunctioning immune system of patients with MS.
Components of myelin such as myelin basic protein have been the focus of much research because, when
injected into laboratory animals, they can precipitate experimental allergic encephalomyelitis (EAE), a chronic
relapsing brain and spinal cord disease that resembles MS. The injected myelin probably stimulates the immune
system to produce anti-myelin T cells that attack the animal's own myelin. (Leuven)
Investigators are also looking for abnormalities or malfunctions in the blood/brain barrier, a protective
membrane that controls the passage of substances from the blood into the central nervous system. It is possible
that, in MS, components of the immune system get through the barrier and cause nervous system damage.
“Scientists have studied a number of infectious agents (such as viruses) that have been suspected of
causing MS, but have been unable to implicate any one particular agent.” (Mayo Clinic) Viral infections are
usually accompanied by inflammation and the production of gamma interferon, a naturally occurring body
chemical that has been shown to worsen the clinical course of MS. It is possible that the immune response to
viral infections may themselves precipitate an MS attack.
“The genes a person inherits may help determine whether that person is at increased risk for developing
MS.” ( Melvin) While there is evidence from studies that this genetic component exists, it appears to be only one
factor among several. Most likely an individual’s genetic blueprint ultimately determines if that individual will be
susceptible to a triggering factor, which in turn initiates the autoimmune process that leads to the development of
MS.
In the past few years, scientists have developed a set of tools that gives them the ability to pinpoint the
genetic factors that make a person susceptible to MS. “These tools are the methods of molecular
genetics—techniques used to isolate and determine the chemical structure of genes.” (Colin)
In the 1980s, scientists began to apply the tools of molecular genetics to human diseases caused by defects
in single genes. This work led to major advances in understanding diseases such as Duchenne muscular dystrophy
and cystic fibrosis. The situation for diseases such as multiple sclerosis is more complicated. Scientists now believe
that a person is susceptible to multiple sclerosis only if he or she inherits an unlucky combination of several genes.
(Colin)
Advances in molecular genetics and the identification of large families in which several members have
MS—"multiplex" MS families—have made possible research to uncover MS susceptibility genes. “Since 1991, the
National MS Society has supported an international project searching for these genes.” ( National Multiple
Sclerosis Society)
However, even though genetic (inherited) factors seem to play a large role in the development of MS, no
single MS gene has been identified so far. Instead, scientists suspect that MS develops because of the influence of
several genes acting together.
Many multiplex families from throughout the world have agreed to participate in these studies. The
researchers are looking for patterns of genetic material that are consistently inherited by people with MS. These
recognizable patterns are called "DNA markers." (Melvin)
When one of these markers is identified, scientists focus on that area, seeking additional markers closer
to that gene. Eventually the location of that gene can be identified. This process of moving closer to the gene until
it is identified has to be repeated for each of the marker regions from the multiplex families. (Melvin)
By 1996, as many as 20 locations that may contain genes contributing to MS were identified, but no
single gene was shown to have a major influence on susceptibility to MS. (Melvin) Research will likely find
that other, as yet unidentified, genes contribute to MS.
After the location of each susceptibility gene is identified, the role that the gene plays in the immune
system and neuralgic aspects of people with MS will have to be determined. Because the immune system is so
involved in MS, many scientists think at least some of the susceptibility genes are related to the immune system.
Already there have been reports linking some immune system genes to MS.
Further indications that more than one gene is involved in MS susceptibility comes from studies of
families in which more than one member has MS. Several research teams found that people with MS inherit
certain regions on individual genes more frequently than people without MS. Of particular interest is the human
leukocyte antigen (HLA) or major histocompatibility complex region on chromosome 6. HLAs are genetically
determined proteins that influence the immune system. ( Kaser)
The HLA patterns of MS patients tend to be different from those of people without the disease.
Investigations in northern Europe and America have detected three HLAs that are more prevalent in people with
MS than in the general population. Studies of American MS patients have shown that people with MS also tend
to exhibit these HLAs in combination--that is, they have more than one of the three HLAs--more frequently than
the rest of the population. Furthermore, there is evidence that different combinations of the HLAs may correspond
to variations in disease severity and progression. ( Kaser)
Studies of families with multiple cases of MS and research comparing genetic regions of humans to those
of mice with EAE suggest that another area related to MS susceptibility may be located on chromosome 5. Other
regions on chromosomes 2, 3, 7, 11, 17, 19, and X have also been identified as possibly containing genes
involved in the development of MS. (Hauser)
These studies strengthen the theory that MS is the result of a number of factors rather than a single gene
or other agent. Development of MS is likely to be influenced by the interactions of a number of genes, each of
which (individually) has only a modest effect. Additional studies are needed to specifically pinpoint which genes
are involved, determine their function, and learn how each gene's interactions with other genes and with the
environment make an individual susceptible to MS. “In addition to leading to better ways to diagnose MS, such
studies should yield clues to the underlying causes of MS and, eventually, to better treatments or a way to prevent
the disease.” (Ronthal)
Finding the genes responsible for susceptibility to MS may lead to the development of new
and more effective ways to treat the disease. Such research could also uncover the basic cause of the disease and
help predict the course of the disease in an individual. This would make it easier for physicians to tailor therapies
and provide information to help people make life decisions.
Another possible benefit may be the early diagnosis of people in families where one or more member
already has MS. Many physicians believe that the earlier MS is diagnosed and treatment begun, the better the
outcome will be.
Symptoms of MS may be mild or severe, of long duration or short, and may appear in various
combinations, depending on the area of the nervous system affected. Complete or partial remission of symptoms,
especially in the early stages of the disease, occurs in approximately 70 percent of MS patients.
“The initial symptom of MS is often blurred or double vision, red-green color distortion, or even
blindness in one eye.” (Brunnscheiler) Inexplicably, visual problems tend to clear up in the later stages of MS.
Inflammatory problems of the optic nerve may be diagnosed as retrobulbar or optic neuritis. Fifty-five percent of
MS patients will have an attack of optic neuritis at some time or other and it will be the first symptom of MS in
approximately 15 percent. This has led t

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