The identification of soluble oligomers of Amyloid beta- protein (AB) as diffusible assemblies that are capable of interfering with synaptic function provides an important opening to understand the basis of memory loss in the Alzheimer disease. Whereas, in the second article, a study of the mutation in DISC1 is linked to Schizophrenia, which is a major neuropsychiatric disease. Hundred of years ago, researchers were searching for the causes of such dangerous disorder in order to find solutions and treat them, but no accurate studies were done before that. Nowadays, due to technology, researchers are able to come up with useful information that supports this field, and this is obvious in those two articles. In each article, there is an experiment that studies the causes of each disorder, its effects and syndromes. So the aim of these studies is to discuss deeply Alzheimer and Schizophrenia in a scientific way to clarify the real causes of the two diseases.
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In the text " Soluble Protein Oligomers in Neurodegeneration: lessons from the Alzheimer's Amyloid B_Peptide" published in 2007 the magazine Nature Publishing Group p.101-112 (doi: 10.1038/nrm2101), the authors Christian Haass and Dennis J. Slkoe discuss Alzheimer disease.
In the twentieth century, amyloidoligst found that amyloid fibrils were proteinaceous in origin. By the 1960s, biochemical and ultra structural experiment established the remarkable insolubility of amyloid fibril in aqueous buffers. X-ray diffraction indicates that this protein sheet structure that this protein is rich in B_ Pleated structure that provides an explanation of memory disorder.
The purpose of the new study is to identify the function of this protein in memory disorder. Today, there is more accurate explanation for the role of Amyloid in memory disorder and especially Alzheimer disease. In the Alzheimer disease, a small peptide amyloids proteins (AB), forms long, insoluble amyloid fibrils, which accumulate in spherical microscopic deposits called senile plaques. This study identifies the toxic matter responsible for synaptic dysfunction and neuronal cell loss in AD. The production of these apparent toxic species _ AB oligomers provokes neuronal injury. Researchers found that B amyloid precursor protein (APP) which is a single transmembrane, receptor like protein is expressed in neural cells. During the experiment, researchers stimulated AB region. This stimulation caused a change in AB metabolism.
As a result, an increase in total AB production and reduction of AB degradation is detected. This change enhances oligomer formation that causes severe changes of synaptic function. Then inflammatory responses follow these changes and cause neuronal injury. Then the widespread of neuronal dysfunction and the cell death associated with neurotransmiter deficits cause Alzhaimer.
In the text " DISC1 is Mutated in The 129s6/SvEv strain and Modulates Working Memory in Mice" publisher in march 7, 2006 ( vol. 103, no.10, p.3693-3697) in The national Academy of science of the USA, the authors Hiroko Koike, P. Alexnder Arguello, Mirna Karayiogou and Joseph A. Gogos discuss Schzophrenia.
Schizophrenia is a common and genetically complex psychiatric disorder. Several leading candidate susceptibility genes have been identified including DISC1. Previous experiment of the function of DISC1 was poorly understood, yet researchers didn't identify the real function of DISC1 and its relation with Schizophrenia.
The aim of this early experiment is to find out the role and function of DISC1 in causing Schizophrenia to facilitate the analysis of the effect of DISC1 deficiency on mouse behavior and cognition, researchers transferred a modified mDISC1 allele onto a genetic background. The resultant mDISC1 deficient strain retained > 98%, and demonstrated a specific deficits in working memory performance. Impaired function of the DISC1 gene influences Schizophrenia by affecting the functional integrity of the prefrontal cortex. In addition, the experiment suggests that the absence of full length (normal) DISC1 protein play an important role in changing behaviors and attitudes.
As a result, mice deficient in mDISC1 learned different task and performed well; however mDISC1 deficient mice showed a consistent impairment in the memory test. This impairment was shown in both heterozygous and homozygous mutant mice. Important notice detected during the experiment that no significant changes in locomotors activity.
Any mutation in the DNA chain causes disorder to certain parts of human body. The mutated genes generate new types of protein that kill cells and therefore hurt the body. This procedure was obvious in the two experiments discussed above. Disorder in the B_amyloid causes Alzheimer, and mutation in DISC1 causes Schizophrenia. The discovery of the causes of these dangerous diseases must give researchers answers to find solutions. Yet the question still that why there is no medicine or treatment for Alzheimer and Schizophrenia since the causes of the two diseases are discovered. Usually the most difficult stage in scientific researches is to find the reasons that caused the problem. Whenever these reasons are known, finding solutions is an easy process. I am still wondering why doctors didn't find till now treatment for many disease not only Alzheimer and Schizophrenia but many others like VIH and cancer. Is it because of political decisions that oblige doctors not to introduce these treatments in order to increase the rate of death and therefore decrease the population to protect natural resources or because researchers didn't came till now to the initial causes of these diseases?
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Abstract of the article about Alzheimer:
The distinct protein aggregates that are found in Alzheimer's, Parkinson's, Huntington's and prion diseases seem to cause these disorders. Small intermediates - soluble oligomers - in the aggregation process can confer synaptic dysfunction, whereas large, insoluble deposits might function as reservoirs of the bioactive oligomers. These emerging concepts are exemplified by Alzheimer's disease, in which amyloid -protein oligomers adversely affect synaptic structure and plasticity. Findings in other neurodegenerative diseases indicate that a broadly similar process of neuronal dysfunction is induced by diffusible oligomers of misfolded proteins.
Abstract of the article about Schizophrenia:
Disrupted-In-Schizophrenia (DISC1) is a leading candidate schizophrenia susceptibility gene. Here, we describe a deletion variant in mDisc1 specific to the 129S6/SvEv strain that introduces a termination codon at exon 7, abolishes production of the full-length protein, and impairs working memory performance when transferred to the C57BL/6J genetic background. Our findings provide insights into how DISC1 variation contributes to schizophrenia susceptibility in humans and the behavioral divergence between 129S6/SvEv and C57BL/6J mouse strains and have implications for modeling psychiatric diseases in mice.