1. Discussion on the normal function of the neuromuscular junction
Introduction
Gravis
Myasthenia gravis (MG) is the most common primary disorder of neuromuscular transmission. The usual cause is an acquired immunological abnormality, but some cases result from genetic abnormalities at the neuromuscular junction. Much has been learned about the pathophysiology and immunopathology of myasthenia gravis during the past 20 years. What was once a relatively obscure condition of interest primarily to neurologists is now the best characterized and understood autoimmune disease. A wide range of potentially effective treatments are available, many of which have implications for the treatment of other autoimmune disorders.
The function of the neuromuscular response in skeletal muscle
Small vesicles about 40 nanometres (40×10-9 M) in size are formed by the Golgi apparatus in the cell body of the motor neuron in the spinal cord. These vesicles are then transported by streaming of the axoplasm through the core of the axon from the central cell body of the spinal cord all the way to the neuromuscular junction at the tips of the nerve fibres. About 300,000 of these small vesicles collect in the nerve terminals of a single skeletal muscle end plate.
Acetylcholine is synthesized in the cytosol of the terminal nerve fibres but is then transported through the membranes of the vesicles to their interior, where it is stored in highly concentrated form, with about 10,000 molecules of acetylcholine in each vesicle.
Under resting conditions, an occasional vesicle fuses with the surface membrane of the nerve terminal and releases it's acetylcholine into the synaptic gutter. When this occurs, a so-called miniature end plate potential, about 0.4 mV in intensity and lasting for a few milliseconds, occurs in the local area of the muscle fibre because of the action of this 'packet' of 10,000 acetylcholine molecules.
When an action potential arrives at the nerve terminal, it opens many calcium channels in the membrane of the terminal because this terminal has an abundance of voltage-gated calcium channels. As a result, the calcium ion concentration in the terminal increases about 100-fold, which in turn increases the rate of fusion of the acetylcholine vesicles with the terminal membrane about 10,000-fold. As each vesicle fuses, its fusion surface ruptures through the cell membrane, thus causing exocytosis of acetylcholine into the synaptic space. About 125 vesicles usually rupture with each action potential. The acetylcholine is then split by acetylcholinesterase into acetate ion and choline and the choline is reabsorbed actively into the neural terminal to be reused in forming new acetylcholine. This sequence of events occurs within a period of 5 to 10 milliseconds.
Those acetylcholine able to make contact with the protein receptors on the motor end plate of the sarcolemma (the sheath surrounding a muscle fibre) activate the sodium channel and thus allow sodium ions to flow through the ion gate. This sets up a voltage difference on each side of the sarcolemma, an alternating polarity on the outside and inside. This potential difference spreads immediately along the muscle fibre inducing calcium to be released from the cisternae of the sarcoplasmic reticulum. The calcium binds to troponin on the thin filament exposing the site for myosin which binds to actin swivels and releases. The calcium is actively pumped back into the cisternae when the ion channel closes and the muscle contraction ceases.
The number of vesicles available in the nerve ending is sufficient to allow transmission of only a few thousand nerve-to-muscle impulses. Therefore, for continued function of the neuromuscular junction, the vesicles need to be reformed rapidly. Within a few seconds after the action potential is over, coated-pits appear in the terminal nerve membrane, caused by contractile proteins in the nerve ending, especially the protein clathrin, attached to the membrane in the area of the original vesicles. Within about 20 seconds, the proteins contract and cause the pits to break away to the interior of the membrane, forming new vesicles. Within another few seconds, acetylcholine is transported to the interior of these vesicles and they are then ready for a new cycle of acetylcholine release.
Smooth Muscle
Skeletal Muscle fibres are activated exclusively by the nervous system, whereas, smooth muscle can be stimulated to contract by multiple types of signals such as nervous signals, hormonal stimulation, stretch of the muscle and some other ways. The main reason for the difference is that the smooth muscle membrane contains many types of receptor proteins that can initiate the contractile process. Other receptor proteins inhibit smooth muscle contraction, which is another difference from skeletal muscle. Smooth muscle is not subject to Myasthenia Gravis as contraction does not rely on the acetylcholine -acetylcholinesterase 'make-break' relationship
Cardiac Muscle
Purkinje fibres which discharge between 15 to 140 times per minute stimulate the heart. It is not subject to the acetylcholine -acetylcholinesterase 'make-break' relationship and is not subject to Myasthenia Gravis.
2. Pathophysiology of Myasthenia Gravis
The normal neuromuscular junction releases acetylcholine (ACh) from the motor nerve terminal in discrete packages or quanta. The ACh quanta diffuse across the synaptic cleft and bind to receptors on the folded muscle end-plate membrane. Stimulation of the motor nerve releases many ACh quanta that depolarize the muscle end-plate region and then the muscle membrane causing muscle contraction. In acquired myasthenia gravis, the post-synaptic muscle membrane is distorted and simplified, having lost its normal folded shape. The concentration of ACh receptors on the muscle end-plate membrane is reduced and antibodies are attached to the membrane. ACh is released normally, but its effect on the post-synaptic membrane is reduced. The post-junctional membrane is less sensitive to applied ACh, and the probability that any nerve impulse will cause a muscle action potential is reduced.
Diagnosis
A delay in diagnosis of one or two years is not unusual in cases of myasthenia gravis. Because weakness is a common symptom of many other disorders, the diagnosis is often missed in people who experience mild weakness or in those whose weakness is restricted to only a few muscles.
The first steps of diagnosing myasthenia gravis include a review of the individual's medical history, and physical and neurological examinations. The signs a practitioner must look for are impairment of eye movements or muscle weakness without any changes in the individual's ability to feel things. If the practitioner suspects myasthenia gravis, several tests are available to confirm the diagnosis.
A special blood test can detect the presence of immune molecules or acetylcholine receptor antibodies. Most patients with myasthenia gravis have abnormally elevated levels of these antibodies. However, antibodies may not be detected in patients with only ocular forms of the disease.
Another test is called the edrophonium test. This test requires the intravenous administration of edrophonium chloride or Tensilon, a drug that blocks the degradation or breakdown of acetylcholine and temporarily increases the levels of acetylcholine at the neuromuscular junction. In people with myasthenia gravis involving the eye muscles, edrophonium chloride will briefly relieve weakness. Other methods to confirm the diagnosis include a version of nerve conduction study which tests for specific muscle "fatigue" by repetitive nerve stimulation. This test records weakening muscle responses when the nerves are repetitively stimulated. Repetitive stimulation of a nerve during a nerve conduction study may demonstrate decrements of the muscle action potential due to impaired nerve-to-muscle transmission.
A different test called single fiber electromyography (EMG), in which single muscle fibers are stimulated by electrical impulses, can also detect impaired nerve-to-muscle transmission. EMG measures the electrical potential of muscle cells. Muscle fibers in myasthenia gravis, as well as other neuromuscular disorders, do not respond as well to repeated electrical stimulation compared to muscles from normal individuals. Computed tomography (CT) may be used to identify an abnormal thymus gland or the presence of a thymoma.
A special examination called pulmonary function testing - which measures breathing strength - helps to predict whether respiration may fail and lead to a myasthenic crisis.
The importance of the Thymus Gland
Thymic abnormalities are clearly associated with myasthenia gravis but the nature of the association is uncertain.
Although all the lymphocytes of the body originate from the lymphocytic committed stem cells of the embryo, these stem cells themselves are incapable of forming directly either activated T lymphocytes or antibodies. They must be further differentiated in appropriate processing areas in the thymus or in B-cell processing areas.
The T-lymphocytes, after their origin in the bone marrow, first migrate to the thymus gland. Here they divide rapidly and at the same time develop extreme diversity for reacting against different specific antigens. For example, one of the thymic lymphocytes develops specific reactivity against one antigen. Then the next lymphocyte develops specificity against another antigen. This continues until there are different types of thymic lymphocytes with specific reactivities against millions of different antigens. These different types of processed T lymphocytes leave the thymus and spread by blood throughout the body to lodge in all lymphoid tissue.
The thymus also makes certain that any T lymphocyte leaving the thymus will not react against proteins or other antigens that are present in the body's own tissues, otherwise that T lymphocyte would be lethal to the person's own body in only a few days. The thymus selects which T lymphocytes will be released by first mixing them with virtually all the specific self antigens from the body's own tissues. If a T lymphocyte reacts it is destroyed and phagocytized instead of being released - this happens to about 90% of cells. The cells that are released are those that are nonreactive against the body's own antigens - that is they react only with antigens from an outside source such as from a bacterium, a toxin or transplanted tissue.
Most of the preprocessing of the T lymphocytes in the thymus occurs shortly before birth and a few months after birth. After birth, removal of the thymus gland diminishes but doesn't eliminate the lymphocytic immune system.
Removal of the thymus several months before birth can prevent development of all cell mediated immunity. So performing an organ transplant after that time will not result in organ or tissue rejection.
Ten percent of patients with myasthenia gravis have a thymic tumor and 70% have hyperplastic changes (germinal centers) that indicate an active immune response. These are areas within lymphoid tissue where B-cells interact with helper T-cells to produce antibodies.
Because the thymus is the central organ for immunological self-tolerance, it is reasonable to suspect that thymic abnormalities cause the breakdown in tolerance that causes an immune-mediated attack on acetylcholine receptors (AChR) in myasthenia gravis.
The thymus contains all the necessary elements for the pathogenesis of myasthenia gravis: myoid cells that express the AChR antigen, antigen presenting cells, and immunocompetent T-cells.
Thymus tissue from patients with myasthenia gravis produces AChR antibodies when implanted into immunodeficient mice. However, it is still uncertain whether the role of the thymus in the pathogenesis of myasthenia gravis is primary or secondary.
Most thymic tumors in patients with myasthenia gravis are benign, well-differentiated and encapsulated, and can be removed completely at surgery. It is unlikely that thymomas result from chronic thymic hyperactivity because myasthenia gravis can develop years after thymoma removal. Patients with thymoma usually have more severe disease and higher levels of AChR antibodies. Almost 20% of patients with myasthenia gravis whose symptoms began between the ages of 30 and 60 years have thymoma; the frequency is much lower when symptom onset is after age 60.
Myasthenia Gravis, like many other autoimmune diseases is an acquired deficiency disease. Like AIDS, HIV, Lupus, Chronic Fatigue (Epstein Barr Virus) and many other acquired issues.
The body has a history of coping with many incidences of cancer and there is proof that at certain times autopsy has shown that the body has handled cancer while the host was unaware.
Sometimes the body needs some help in order for the system to regain balance and return to a homeostatic balance. Certain machines such as the electric pulsers, electromagnetic pulsers and high energy from multiwave oscillators can help kill pathogens within the body. Although no treatment is certain, it is preferable to have many tools available for treatment.
Treatment
Current medical treatment is the administration of alkaloids such as neostigmine and physostigmine. These wear off in a few hours. Antibodies to acetylcholine-receptor protein function at the motor end plate on the sarcolemma causes muscle inoperability. This eventually results in fibre atrophy. Atrophied fibres have actually been rebuilt as satellite cells on the sarcolemma have the ability to rebuild muscle fibre. Myasthenia Gravis is an autoimmune disease and as such may be reversed by appropriate treatment.
Discoveries in treating thymic disorders (where T-lymphocytes differentiate) may well be the starting place to recover the immune system. EM Pulse to thymus/lymph glands, blood electrification and mwo may be a reasonable starting point. This is an opinion and is not medical advice - you must do your homework relating to your own health issue as an individuals health is not equal to everyone.
However it is the authors opinion that Chinese Medicine may be very helpful in the hands of an experienced practitioner in determining the cause of the illness. If we treat the symptom of an illness it is like putting on makeup - the illness will stay and may get worse, whereas finding the root cause of the problem will lead to health. Then it is important to maintain a correct lifestyle - this is not understood in most countries. Correct lifestyle means just that - if you do not feel good then you must speak with a practitioner who is competent at looking at the root cause of your health issue.
Myasthenia Gravis - A Neuromuscular Disease
Ron Campeanu
References:
Textbook of Medical Physiology, Guyton,A.C. and Hall, J.E, 10th edn., WB Saunders
Anatomy and Physiology, Tortora, G.J. and Grabowski, S.R., 10th ed., Wiley
Merck Manual of Diagnosis and Therapy
Ron Campeanu - Industrial Chemist, studying an Advanced Diploma in Acupuncture, designed the Q10Sport formula in 2003 in Australia. It is a Listed Medicine and a very potent energy formula which helps the immune system as it helps the body create ATP (adenosine triphosphate) - raw energy.
Actives Q10 and lipoic acid are naturally occuring in the body. The formula helps rebuild cells to allow the body more energy capacity when needed - in times of stress, training, work. Lipoic acid has long been recognized as a support for nerves - it is used to help with peripheral neuropathy. It has been the authors personal experience that lipoic acid has helped with nerve damage after surgery (on a family member).
It is the only antioxidant that regenerates coenzyme Q10, glutathione and vitamin C and stands in for vitamin E when it is deficient. This has scope for all autoimmune disorders, but it is only one tool of the many that are needed if the immune system has a chance for restoration.
For more information please visit the website at http://www.realhealthproducts.com where you can read more information in the various health articles.