|
| |
AMYOTROPHIC LATERAL SCLEROSIS.
Term Paper ID:23214
|
|
|
Essay Subject:
Degeneration of nervous system. Symptoms, theories on cause, research, types.... More...
|
7 Pages / 1575 Words
6 sources, 21 Citations,
APA Format
$28.00
Return to List of Papers
|
Paper Abstract:
Degeneration of nervous system. Symptoms, theories on cause, research, types.
Paper Introduction:
Amyotrophic Lateral Sclerosis
Although amyotrophic lateral sclerosis is a relatively uncommon disorder, it has been the focus of considerable scientific scrutiny. First described by Charcot in 1869, the condition involves degeneration and loss of motor neurons in the cerebral cortex, brainstem, and spinal cord. Although different forms of the disease have been described, a definitive pathologic mechanism has yet to be delineated.
Various synonyms for amyotrophic lateral sclerosis (ALS) include Lou Gehrig's disease, Charcot disease, and motor neuron disease (Rowland, 1995, pp. 1251-1252). The disorder is caused by non-specific degenerative changes of the bulbar and spinal motor neurons and their corresponding cortico-spinal tracts. Moreover, other neuronal systems may become progressively
Text of the Paper:
The entire text of the paper is shown below. However, the text is somewhat scrambled. We want to give you as much information as we possibly can about our papers and essays, but we cannot give them away for free. In the text below you will find that while disordered, many of the phrases are essentially intact. From this text you will be able to get a solid sense of the writing style, the concepts addressed, and the sources used in the research paper.
Spencer andassociates (cited in Rowland, 1991, p. Finally, the heat shock protein, ubiquitin, mayassociate with intermediate filament inclusion bodies to form eitheraggregates or skein-like cytoplasmic arrays. The study identified a basic amino acid, ß-N-methylamino-L-alanine (BMAA),with the potential to act as an excitatory neurotoxin. (cited in Swash & Schwartz, 1992, p. 1 )observed that cooked food has fairly low quantities of active BMAA. Such changes, however, are highly variable. Journal of the Neurological Sciences, 124 Supplement: 38- 51.Rowland, L. Perhaps the most innovative hypothesis for ALS pathogenesis, however,involves genetics. Patten et al. 4-13) found that patients with bulbar involvementsurvived for a mean period of 2.2 years; median survival for all ALS casesis 3-4 years. Technologicaladvances in molecular biology have provided researchers with innovativeapproaches to the disease. 14-15) consideredhumoral immune mechanisms. In addition,various other studies have made similar observations (e.g., Mulder andHoward 1976; Engel et al. Ratherit results from an apparent gain of function. P. This free radical, which is generated during normal oxidativereactions, is dismutated to form hydrogen peroxide and oxygen. F. Magnetic resonance imaging studies havedemonstrated high intensity lesions widely distributed within the centralnervous system white matter. About a third ofpatients present with bulbar symptoms. These can include the spinocerebellar pathways andnuclei, the frontal cortex, and the substantia nigra (Swash & Schwartz,1992, pp. Given the inherent heterogeneity of ALS, it seems likely thatmultiple pathologic processes are involved. For example, ALSpatients' skeletal muscle may exhibit signs of denervation andreinnervation. However, there issome doubt as to whether the compound is actually capable of inducingneurologic degeneration. G.; Engelhardt, J. Various synonyms for amyotrophic lateral sclerosis (ALS) include LouGehrig's disease, Charcot disease, and motor neuron disease (Rowland, 1995,pp. Symptomatic modalities include gastrostomy feeding andventilatory support. Based on speculative etiological ideas, various attempts have beenmade to treat ALS. Gurney and colleagues(cited in Appel, Smith, Englehardt, & Stefani, 1994, pp. Moreover, this syndrome has been associatedhistologically with degeneration and loss of spinal cord motor neurons.The pathology, however, is not due to a loss of dismutase activity. The ALSsyndromes observed in these areas are generally associated with otherneurodegenerative syndromes (e.g., the ALS/parkinsonism/dementia complex).These diseases' causation has been a topic of some controversy. Despiteconsiderable locus heterogeneity, almost 2 percent of familial ALS caseswere additionally mapped to the copper/zinc superoxide dismutase type 1(SOD1) gene. For example, there aresporadic, familial, and Western Pacific forms of the disease (Lowe, 1994,p. Bunina (cited in Swash & Schwartz, 1992, p. Perhapsthe location which has been most thoroughly studied is Guam. Moreover, noconsistent differences in cellular immunity have been observed amongpatients. For the most part though, such experimental therapieshave had disappointing results. In 1991, Siddique and Brown (cited in Rowland, 1995, p.1251) mapped the familial ALS subtype to chromosome 21. 1251-1252). At least 24 missense mutations and one deletion have beenidentified for the SOD1 gene. Evidence for autoimmunity in amyotrophic lateral sclerosis. (1994, July). Unfortunately, though, thepathogenesis and significance of these intraneuronal inclusions remainunknown. Histological analyses have found numerous intraneuronal inclusionsassociated with ALS. Advances in Neurology, 56, 3-23.Swash, M., & Schwartz, M. Excessaccumulation of the cation could also have toxic consequences (Rowland,1995, pp. Furthermore, this trend has also been observed for age-specific and age-adjusted rates (Kurtzke, 1991, pp. Advances in Neurology, 56, 245-27 .Lowe, J. Tucker and associates (cited in Swash &Schwartz, 1992, pp. The disorder is caused by non-specific degenerativechanges of the bulbar and spinal motor neurons and their correspondingcortico-spinal tracts. For example, the disease couldresult from some combination of molecular mechanisms. Moreover, the widespread loss of anterior hornneurons suggests that interneurons may also be affected. Journal of the Neurological Sciences, 124 Supplement: 14-19.Kurtzke, J. Finally, "there is no direct evidence for autoimmune factors inALS" (Appel et al., 1994, pp. 4-13). Someresearchers have postulated, therefore, that the disease is influenced byboth environmental and genetic factors. More recently,scientific investigations have turned up antibodies to gangliosides in ALSpatients without monoclonal gammopathies. 245-267). (1995, February 28). The researchers focused on a presumed novelgrowth factor that was supposedly produced by denervated muscle.Unfortunately though, the compound under investigation was eventually foundto be nothing more than glucose-6-phosphate isomerase. 11)described intracytoplasmic acidophilic inclusions, 2-3 (m in diameter.These amorphous, vesicular Bunina bodies are often found in the perikarya,axon, and soma of ALS patients' motor neurons. New pathological findings in amyotrophic lateral sclerosis. H.; Smith, R. 14-15). Other neural systems that may be affectedinclude the cord and brainstem spinocerebellar pathways. If somesubstrate that does not normally interact with the SOD1 enzyme were thensuddenly able to, the result might be a new and toxic species of oxygen.Alternatively, the altered enzyme might bind copper differently. Amyotrophic Lateral Sclerosis Although amyotrophic lateral sclerosis is a relatively uncommondisorder, it has been the focus of considerable scientific scrutiny. 1251-1252). (1992, November). Journal of the Neurological Sciences, 113, 4-16.----------------------- 1 The investigations are hampered bylack of an adequate animal model and few human subjects. Forexample, monomelic motor neuron disease affects the distal upper limbs.Moreover, patients with wasted leg syndrome experience diffuse wasting ofone leg. With good patient management, these measures canincrease patient survival. Within thecerebral cortex, there is typically a loss of Betz cells and degenerationof the corticospinal tracts. 5) foundthat the muscles of longer surviving patients showed type 1 fiber grouping;further, a poor prognosis was associated with the clustering of smallatrophic fibers. Proceedings of the National Academy of Sciences of the United States of America, 92, 1251-1253.Rowland, L. Genes forhuman mutant SOD1 enzymes have been introduced into strains of mice.Researchers have observed that the SOD1 genes produce a clinical syndromeof hind limb paralysis. Of these, considerable allelic heterogeneity was alsoobserved. S. Firstdescribed by Charcot in 1869, the condition involves degeneration and lossof motor neurons in the cerebral cortex, brainstem, and spinal cord.Although different forms of the disease have been described, a definitivepathologic mechanism has yet to be delineated. ReferencesAppel, S. Moreover, other neuronal systems may becomeprogressively involved. Moreover, it seemsto be more common among Caucasians. 4-13). (1994, July). For example, the most common point mutationis an "Ala6Val substitution at codon 4 (A4V); this mutation accounts for38% of all familial ALS" (Rowland, 1995, pp. 8) proposed a neurotoxic hypothesis. Finally, although the topic is controversial, there are reports ofspontaneous ALS remission. Although most patients present withthe core syndrome, considerable variation exists among ALS variants. Neuronal loss mayeven occur within Clarke's column, the thalamus, the corpus callosum, andthe superior colliculi. There are various theoriesas to how such a "dominant-negative" effect might occur. 4-13) described four patients with ALS-like syndromewho experienced a complete recovery 5-12 months after onset. Jokelainen (cited in Swash &Schwartz, 1992, pp. In addition, sural nerve biopsies have shownevidence of axonal atrophy and remyelination involving, in particular, thelarger diameter nerve fibers (Swash & Schwartz, 1992, pp. In addition, spheroidscomposed of individually arranged or bundled neurofilamentous material havealso been observed. 4-13). At present, there is no specific ALStreatment. What do we really know about amyotrophic lateral sclerosis? Nonspecific pathological changes associated with ALS generally resultfrom the degeneration of patients' central neurons. This complaint can involve only a few adjacent muscles:Leg weakness is slightly more common than hand weakness. 1251-1252). Despite considerable research, a definitive mechanism for ALSpathogenesis has yet to become evident. One characteristic feature of thedisease is arm muscle fasciculation. Duncan (cited in Swash & Schwartz, 1992, p. The pathologic features of ALS are generally asymmetrical and includethe loss of both lower cranial nerve nuclei somatic motor neurons andanterior horn cells. Themorbidity and mortality data, however, seem to suggest a recent increase inALS deaths. Despite the fact that amyotrophic lateral sclerosis has alreadyreceived much attention, more work needs to be done. The disease's onset is insidious, and its outcome is typically fatal. Different forms of ALS have been described. In addition, no significant associationshave been demonstrated between ALS and either life-style, social class,occupation, dietary habits, or another disease. Although therehave been many epidemiological studies involving ALS, these have notdelineated any noteworthy trends. In addition to the neurotoxic hypothesis, several immunologicaltheories have been postulated for ALS pathogenesis. These techniques may soon result in rationaltreatment approaches to the neurodegenerative diseases. However, these anti-gangliosideantibodies do not appear to be responsible for ALS. Amyotrophic lateral sclerosis: human challenge for neuroscience. Some of these mightinvolve peroxidation; whereas, others could have nothing to do with freeradicals (Rowland, 1995, pp. (1991). While epidemiologic studies have shown no global trends or generaltendencies, researchers have identified certain high prevalence areas(e.g., Guam, the Kii peninsula of Japan, and Western New Guinea). Juvenile ALS may occur in childhood or adolescence.Additionally, familial ALS can have either an adult or a juvenile onset.Comprising 5-1 % of cases, familial ALS is transmitted according to anautosomal dominant pattern of inheritance (Swash & Schwartz, 1992, pp. In fact, Rowland (1991) noted that 16 different syndromes of ALSwith dementia have been recognized. Amyotrophic lateral sclerosis patients often present with asymmetrical andfocal weakness. For example,alteration of the enzyme could increase access to its active site. 1969; Rowland 198 ) (cited in Swash & Schwartz,1992, p. I., & Stefani, E. 38). The disease's annual incidence isabout 1.3/1 , per year (Swash & Schwartz, 1992, pp. Risk factors in amyotrophic lateral sclerosis. Ten central themes in a decade of ALS research. P. 5). (1991). Men seem to be more vulnerable to ALS than women. 4-13). 1251-1252). Subsequent investigations have found that this copper/zinc superoxidedismutase enzyme catalyzes the dismutation of the cytoplasmic free radical,superoxide.
If this paper is not what you are looking for, you can search again:
or
Click here to request an essay written just for you.
|
|
|
