Historically, Myasthenia Gravis was discovered by Thomas Willis in 1672. It was not until late 19th century that Wilhelm Erb and Samuel Goldflam described the muscle disease due the lack of nervous input. Initially, it was called the Erb-Goldflam syndrome until Friedrich Jolly, a German neurologist coined it as Myasthenia Gravis Pseudoparalytica. He created the Jolly test, which tested for muscle weakness by eliciting faradic stimulations for continuous muscular contractions that caused fatigue (Ropper & Samuels 2009).
Myasthenia Gravis (MG) is an autoimmune disease that causes antibodies to destroy the signal transduction in neuromuscular transmission. In an autoimmune disease such as myasthenia Gravis, the immune system cannot differentiate between healthy cells and antigens. The host’s antibodies block the acetylcholine nicotinic receptors resulting in inhibition of the excitatory effects of the neurotransmitter acetylcholine. It also degrades the acetylcholine receptors. Normally, the antibodies do not attack normal healthy acetylcholine receptors on the postsynaptic end of the neuromuscular junction. Acetylcholine is released from the vesicles from the presynaptic end into the synaptic cleft where it binds to the acetylcholine nicotinic receptors eliciting an excitatory effect for muscle contraction. Once this action is inhibited, muscle contraction in that cell cannot be elicited. These nicotinic acetylcholine receptors are found on the motor end plate of the muscle cell. Acetylcholine binding allows a cascade of events to release calcium into the muscle cell. This allows the movement of actin and myosin based on the sliding filament theory to power stroke causing the cell to contract (Ropper & Samuels 2009).
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In conclusion, immunosuppressive agents and acetylcholinesterase inhibitors help in reducing the symptoms of Myasthenia Gravis. While acetylcholinesterase inhibitors have a short half-life accompanied by various side effects, it is the best solution at this time to alleviate muscle weakness and fatigue. Pyridostigmine is the most commonly used drug with the lowest toxicity amongst these inhibitors because of its limited bioavailability. Immunosuppressive drugs inhibit antibody release reducing the amount of malfunctioning T-cells that attack the nicotinic acetylcholine receptors. While its effects are not immediate with poor absorption, it provides longer periods of symptom relief. The immunological agents are only reduced and not destroyed and thus regenerate to elicit myasthenic symptoms. Further research is necessary to continue the search for a cure.
In the beginning phases of muscle contraction, a “cocked” motor neuron in the spinal cord is activated to form a neuromuscular junction with each muscle fiber when it begins branching out to each cell. An action potential is passed down the nerve, releasing calcium, which simultaneously stimulates the release of acetylcholine onto the sarcolemma. As long as calcium and ATP are present, the contraction will continue. Acetylcholine then initiates the resting potential’s change under the motor end plate, stimulates the action potential, and passes along both directions on the surface of the muscle fiber. Sodium ions rush into the cell through the open channels to depolarize the sarcolemma. The depolarization spreads. The potassium channels open while the sodium channels close off, which repolarizes the entire cell. The action potential is dispersed throughout the cell through the transverse tubule, causing the sarcoplasmic reticulum to release
...st the sacrolemma will depolarized, thus activation potentials along the T-tubules. This signal will transmit from along the T-tubules to sarcroplasmic reticulum's terminal sacs. Next, sarcoplasmic reticulum will release the calcium into the sarcroplasm leading to the next second event called contraction. The released calcium ions will now bind to troponin. This will cause the inhibition of actin and mysoin interaction to be released. The crossbridge of myosin filaments that are attached to the actin filaments, thus causing tension to be exerted and the muscles will shorten by sliding filament mechanism. The last event is called Relaxation. After the sliding of the filament mechanism, the calcium will be slowly pumped back into the scaroplasmic reticulum. The crossbridges will detach from the filaments. The inhibition of the actin and myosin will go back to normal.
It has been shown that intrathecal administriton of GABA receptor antagonists cause hyperalgesia and allodynia. Constitutive, the increase in the endogenous GABA activity in the spinal cord alleviate pain resulting from noxious and innoxious mechanical and thermal stimuli. Different GABA receptors have different roles in alleviating thermal and mechanical pain in different animal pain models. There is no study to date that has examined the involvement of GABA A and GABA B in sensory dimension of neuropathic pain resulting from compression of spinal cord. The current study tests the hypothesis that GABA A or GABA B receptors contributes to the allodynia and hyperalgesia observed after spinal cord injury. The results showed that the effect of GABA A and GABA B receptors on mechanical hyperalgesia is similar but these receptors have different effects on thermal hyperalgesia. While using baclofen as GABA B receptor agonist does not affect the thermal pain, thermal hyperalgesia resulting from spinal cord injury was greatly alleviated by different doses of GABA A agonist, muscimol. Both Baclofen and muscimol are able to reduce the mechanical and cold allodynia has been seen after spinal cord injury but the effect of baclofen is dose dependent with no effect in higher doses used in this study. While almost all doses of muscimol were used in this study reduce the amount of cold and mechanical allodynia. The other result obtained in this study is the short term effect of GABA agonist. The anitinociceptive effect of Baclofen and muscimol appear to be maxium at 15 min after injection and gradually diminished by time and their analgesic effect disappeared 3 hours after injection.
Physiological Basis of disease: DMD is the commonest and most serious form of the dystrophies. The gene responsible for dystrophin which, when absent, causes DMD. Amount of dystrophin correlates with the severity of the disease (i.e., the less dystrophin present, the more severe the phenotype). Since the gene is on the X chromosome, it primarily affects males, and females who are carriers have milder symptoms ( www.nlm.nih.gov/medlineplus/ency/article/000705.htm).
Emery-Dreifuss muscular dystrophy is a rare form of muscular dystrophy characterized by early onset contractures of the elbows, achilles tendons and post-cervical muscles with progressive muscle wasting and weakness It is also associated with heart complications like cardiomyopathy and arrhythmia which in both cases can lead to death. Cardiomyopathy is a heart disease which affects the muscles of the heart. In cardiomyopathy is muscles get rigid, enlarged or thick. They also sometimes changed by scar tissues. On the other hand arrhythmia is a disorder with the rhythm or rate of heartbeat. The heart can beat fast, which is called tachycardia or it could be beating too slow, which is called bradycardia. Emery-Dreifuss muscular dystrophy is characterized by early onset of contractures and humeroperoneal distribution. Humeroperoneal refers to effects on the humerus and fibula. The genes known to be responsible for EDMD encode proteins associated with the nuclear envelope: the emerin and the lamins A and C.
...cz-Towalska, O., Rzodkiewicz, P., Maslinska, D., Szukiewicz,D. & Maslinski, S. (2009) “Cryotherapy decreases histamine levels in the blood of patients with rheumatoid arthritis”, Inflammation Research , 59(2), pp.253–255. ResearchGate [Online]. Available at http://www.researchgate.net/publication/40697605_Cryotherapy_decreases_histamine_levels_in_the_blood_of_patients_with_rheumatoid_arthritis (Accessed: 12th May 2014).
1. James suffers from a condition called Duchenne muscular dystrophy. Explain the full meaning of this name.
Turnpenny, P., Clark, C., Kelly, K. Intelligence quotient profile in myotonic dystrophy, intergenerational deficit, and correlation with CTG amplification. J. Med. Genet. 31: 300-305, 1994.
The human genome is a remarkable system composed of over 3 billion DNA base pairs that encode for the characteristics that makes people distinctly human and unique themselves. Without the genome’s nearly flawless ability to self-replicate the human species would cease to exist. As incredible as this replication methodology is, it is not without its faults. Genetic mutations, though rare and typically harmless, can strike at any time and in various ways. Still, when they do cause harm the effects can be profound and impossible to ignore. Hutchinson-Gilford Progeria Syndrome (HGPS) is an instance where the mutation of just one nucleotide has devastating results. The Mayo Clinic defines progeria as a progressive genetic disorder that causes children to age rapidly, beginning in their first two years of life. This study defines the disease of progeria by outlining symptoms and identifying causes that lead to its diagnosis. In addition, treatment methods and extensive research that give those affected by the disease hope for a brighter future are highlighted.
The Autonomic Nervous System is responsible for the functions of the body that are not thought about to control. When this system dysfunctions, it can cause havoc on the human body. One example of this would be Dysautonomia. Dysautonomia is a rare but serious disease that affects the autonomic nervous system, has many symptoms, and offers few treatment options.
It is estimated that 1 out of every 5,600-7,700 boys ages 5-24 have Duchene or Becker muscular dystrophy. (“Data & Statistics,” 2012 April 6) Muscular dystrophy is a group of genetic diseases defined by muscle fibers that are unusually susceptible to damage. There are several different types of muscular dystrophy some of which shorten the affected person’s lifespan. (“Muscular dystrophy: Types and Causes of each form,” n.d.) There is a long history of the disorder but until recently there wasn’t much knowledge of the cause. (“Muscular Dystrophy: Hope through Research,” 16 April 2014) Symptoms are obvious and can be seen as soon as a child starts walking. (“Muscular Dystrophy,” 2012 January 19) Although muscular dystrophy mostly affects boys, girls can get it too. (“Muscular Dystrophy,” 2012 January 19) There is no cure for muscular dystrophy but there are several types of therapy and most types of muscular dystrophy are still fatal. (“Muscular Dystrophy: Hope through Research,” 16 April 2014)
Duchenne Muscular Dystrophy, also known as DMD, is the most common form of muscular dystrophy. Muscular dystrophy is a condition that is inherited, and it is when muscles slowly become more and more weak and wasted. Duchenne muscular dystrophy is a form of muscular dystrophy that is very rapid and is most commonly found in boys. In muscle, there is a protein named dystrophin. Dystrophin is encoded by the DMD gene. When boys have Duchenne muscular dystrophy, they do not produce enough dystrophin in their muscles. This causes weakness in their muscles. Parents can tell if their child has duchenne muscular dystrophy by looking for various symptoms.
Rationale: Therapeutic use of self by the nurse and concrete task definition and assignment reinforce positive coping strategies and allow caregivers to feel less guilty when tasks are delegated to multiple caregivers. Ackley and Ladwig p. 286
Synaptic transmission is the process of the communication of neurons. Communication between neurons and communication between neuron and muscle occurs at a specialized junction called synapses. The most common type of synapse is the chemical synapse. Synaptic transmission begins when the nerve impulse or action potential reaches the presynaptic axon terminal. The action potential causes depolarization of the presynaptic membrane and it will initiate the sequence of events leading to release the neurotransmitter and then, the neurotransmitter attaches to the receptor at the postsynaptic membrane and it will lead to the activation of the postsynaptic membrane and continue to send the impulse to other neurons or sending the signal to the muscle for contraction (Breedlove, Watson, & Rosenzweig, 2012; Barnes, 2013).
3- Provide a brief outline of the therapeutic applications of H1, H2 and H3 receptor antagonists.