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1.
Alzheimers disease (AD) is a kind of progressive neurodegenerative disease, characterized by intracellularfibrillar tangles and extracellular senile plaques, the main component of the plaques are b-amyloid (Ab), composed of 3943 amino acids[1]. Glenner and Wong first isolated Ab peptide and determined the sequence in 1984, after-wards, a series of researches were done on its production, structure determination, aggregation, hydrophobicity, re-ceptor and cell toxicity. Ab is the abnormal fiss…  相似文献   

2.
Alzheimers disease is the major cause of dementia and the fourth leading cause of death in the developed world after heart disease, cancer and stroke. Pathologi-cally, one of major hallmarks of Alzheimers disease is the formation of insoluble deposits of -amyloid (A) both as diffuse and senile plaques in the brain tissue. The plaques are fibrous masses composed primarily of the 40-42 resi-due A peptides. The two most abundant forms of A are, respectively, the 40 and 42 residue peptide -amylo…  相似文献   

3.
Alzheimer‘s disease is a progressive neurodegenerative disorder characterized by the presence of senile plaques primarily composed of amyloid β in brain. Abnor-mal secretion and aggregation of amyloid β are the key events in pathogenesis of Alzheimer‘s disease. Reduction of amyloid β production and inhibition of amyloid β aggregation to form senile plaques are hopeful strategies for the treatment and prevention of Alzheimer‘s disease. In the present study, the silver and immunohistochemical staining methods were applied to discover senile plaques in the hippocampus of Alzheimer‘s disease patients, and then images were processed and three-dimensionally reconstructed by Matlab and AVS software. The structure characteristics of senile plaques were measured through correlation function calculation and fractal dimension by a computer-aided method. Diffuse plaque had no amyloid center, but classic plaque presented compact central core structure; two types of plaques were both of porous structure, but the sizes of their pores were significantly different. Furthermore, there was difference in fractal dimension value between the diffuse plaque and classic plaque in the two staining methods. The comparison of structure characteristics between two types of plaques indicated that they developed independently. Establishment of the methods for reconstructing the three-dimensional structure of senile plaque and analyzing their structure characteristics is helpful for further study on the aggregation mechanism of senile plaque.  相似文献   

4.
Alzheimer’s disease (AD) is a neurodegenerative dis-order characterized by progressive dementia. The classic neuropathological lesions of Alzheimer’s disease are se-nile plaque (SP) associated with fibrillar and amorphous nonfibrillar amyloid β (Aβ), neurofibrillary tangles (NFTs) and loss of neurons[1,2]. Many studies show that Aβ plays akey role in the pathogenesis of AD, and fibrillar Aβ has relatively high neurotoxic effects[3―5]. Therefore, studying the mechanism of Aβ aggre…  相似文献   

5.
Neurofibrillary tangles (NFTs) are one of the neuropathological hallmarks of Alzheimer‘s disease (AD) and abnormally hyperphosphorylated tau is the major protein of NFTs. It was reported that cyclin-dependent kinase5 (Cdk-5) could phosphorylate tau at most AD-related epitopes in vivo. In this study, we investigated the effect of cdk-5 overexpression on tau hyperphosphorylation in neuroblastoma N2a cells. We demonstrated that overexpression of cdk-5 whieh rcsul-ted in a 3.5-fold Cdk-5 activation in the transfected cells induced a dramatic increase in phosphorylation of tau at several phosphorylation sites. Overexpression of cdk-5 led to a reduced staining with antibody Tau-1 and an enhanced staining with antibody PHF-1, suggesting hyperphosphorylation of tau at Ser199/202 and Ser396/404 sites. It implies that in vitro overexpression of cdk-5 leads to Cdk-5 overactivation and tau hyperphosphorylation may be the underline mechanism.  相似文献   

6.
Anthracnose disease is one of the major economic constraints to chilli production worldwide, especially in tropical and subtropical regions. Accurate taxonomic information is necessary for effective disease control management. In the Colletotrichum patho-system, different Colletotrichum species can be associated with anthracnose of the same host. Little information is known concerning the interactions of the species associated with the chilli anthracnose although several Colletotrichum species have been reported as causal agents of chilli anthracnose disease worldwide. The ambiguous taxonomic status of Colletotrichum species has resulted in inaccurate identification which may cause practical problems in plant breeding and disease management. Although the management and control of anthracnose disease are still being extensively researched, commercial cultivars of Capsicum annuum that are resistant to the pathogens that cause chilli anthracnose have not yet been developed. This paper reviews the causal agents of chilli anthracnose, the disease cycle, conventional methods in identification of the pathogen and molecular approaches that have been used for the identification of Colletotrichum species. Pathogenetic variation and population structure of the causal agents of chilli anthracnose along with the current taxonomic status of Colletotrichum species are discussed. Future developments leading to the disease management strategies are suggested.  相似文献   

7.
Although the aggregated amyloid β-protein (Aβ) in senile plaques is one of the key neuropathological features of Alzheimer's disease (AD), soluble forms of Aβ also interfere with synaptic plasticity at the early stage of AD. The suppressive action of acute application of Aβ on hippocampal long-term potentiation (LTP) has been reported widely, whereas the mechanism underlying the effects of Aβ is still mostly unknown. The present study, using the whole-cell patch clamp technique, investigated the effects of Aβ fragments (Aβ25–35 and Aβ31–35) on the LTP induction-related postsynaptic ligand-gated channel currents in isolated hippocampal CA1 neurons. The results showed a rapid but opposite action of both peptides on excitatory and inhibitory receptor currents. Glutamate application-induced currents were suppressed by Aβ25–35 in a dose-dependent manner, and furtherN-methyl-D aspartate(NMDA)receptor-mediated currents were selectively inhibited. In contrast, pretreatment with Aβ fragments potentiated γ-aminobutyric acid (GABA)-induced whole-cell currents. As a control, Aβ35–31, the reversed sequence of Aβ31–35, showed no effect on the currents induced by glutamate,NMDAor GABA. These results may partly explain the impaired effects of Aβ on hippocampal LTP, and suggest that the functional down-regulation of NMDA receptors and up-regulation of GABAA receptors may play an important role in remodeling the hippocampal synaptic plasticity in early AD.  相似文献   

8.
The risks of developing complex diseases are likely to be determined by single nucleotide polymorphisms (SNPs), which are the most common form of DNA variations. Rapidly developing genotyping technologies have made it possible to assess the influence of SNPs on a particular disease. The aim of this paper is to identify the risk/protective factors of a disease, which are modeled as a subset of SNPs (with specified alleles) with the maximum odds ratio. On the basis of risk/protective factor and the relationship between nucleotides and amino acids, two novel risk/protective factors (called k-relaxed risk/protective factors and weighted-relaxed risk/protective factors) are proposed to consider more complex disease-associated SNPs. However, the enormous amount of possible SNPs interactions presents a mathematical and computational challenge. In this paper, we use the Bayesian Optimization Algorithm (BOA) to search for the risk/protective factors of a particular disease. Determining the Bayesian network (BN) structure is NP-hard; therefore, the binary particle swarm optimization was used to determine the BN structure. The proposed algorithm was tested on four datasets. Experimental results showed that the algorithm proposed in this paper is a promising method for discovering SNPs interactions that cause/prevent diseases.  相似文献   

9.
An Analysis and Prevention of Stop Marks in Weaving   总被引:1,自引:0,他引:1  
The cause of stop marks of fabrics in weaving is introduced, and the floating displacement of the cloth fell during loom stoppage is a primary cause of stop marks. The stop marks caused by fabric system are analyzed. A new method to eliminate stop marks by using the electronic let-off system is presented. This new method needn't any special detecting equipment, it can control the fell position by the powerful control program, so the cost is decreased greatly. The method is so flexible that can be applied to weaving all kinds of fabrics.  相似文献   

10.
Mucopolysaccharidosis type II (MPS II) is a disabling, fatal monogenic disease caused by abnormal metabolism of the mucopolysaccharides[1]. Gene mutation is the basic cause of MPS II and investigation of the IDS gene muta-tion is the premise for prenatal gene diagnosis and gene therapy. MPS II is worldwide distributed with high inci-dence and serious results. To study the IDS gene of Chi-nese MPS II patients is important not only in carrying out one-family policy but also in upraisi…  相似文献   

11.
Objective: To know the prevalence rate of the acute severe altitude disease of the crowds who are working on the high altitude and the influential foctors upon the people. Method By epidemiology, a survey of 27606 persons who are working on the plateau has been made in the past three years, of which 229 persons had got the disease. 8175 persons who had received finer basic preventions in the group (Group A), has been compared with 19430 persons who had a weak or no basic provention in the group ( Group B) ; the groups working on the plateau with 3 different elevations of above - 3600, - 4600 & 5072 meters sea level have been compared. Resuts: The prevalence rate is 0.83 % in total groaps, of wich, high altitude pulmonary edema is 0.50%, high altitude cerebral edema is 0.28%, the patients who has got both the above diseases is 0.05%. The prevalance rates of the above in Group B and those of higher elevation are higher than those in Group A. 0.32% in Group A, and 1.04% in Group B. (x^2 = 36.95, p 〈 0.001) ;the prevalence rate on the 3 different high elevations are 0.00%, 0.68% and 1.34% in proper order. The prevalence rate of individuals groups in the highest 4.82% (the first year) and 2.26% (the next year ) and all the diseases came on the groups working on the highest elevation areas. Conclusion: The prevalence rate of acute severe plateau disease is very stem, the main influential factors are the height above the sea level, and the level of basic prvention for the crowds. Enhancing the protection of the labourers and medical safeguard, and social psychological adaption can cut down the prevalence rate, and this is the first important problem to solve for the plateau medicine and support from the society.  相似文献   

12.
Dengue virus (DEN), a single positively stranded RNA virus, is a family member of Flaviviridae; it uses the mosquito Aeodes aegypti as its principle vector to cause what is known as Dengue fever. Its genome is -10.8-kb in size and has one open reading frame encoding three structural proteins: capsid (C), precursor of the membrane (prM) and envelope (E), as well as seven non-structural proteins from a single polypeptide. The immature DEN particles are assembled on the inner surface of the endoplasmic reticulum(ER) and budded into the lumen of the ER.  相似文献   

13.
A thermoplastic based composite material is suitable for automobile and aerospace applications. The recyclability of thermoplastic and clean processing further enhance its use. The only limitation encountered in using this material is its high-melt viscosity. Various techniques have been developed to overcome this problem. Commingled materials are one of such methods adopted for making proper use of thermoplastic. A major problem observed during the use of a commingled material is its de-commingling, wherein, the uniform distribution of fiber and thermoplastic yam gets disturbed and affects the final quality of the composite. The effects of the braiding process on laminate quality were investigated. Flat plaques were produced by braiding the commingled yam, using a 48-carrier braiding machine. The braids (and control woven samples) were subsequently heated and consolidated in a nonisothermal compression molding operation. Prior to the manufacture of the ‘best quality’ plaques, a series of moldings were produced under different consolidation conditions, to study the dependence of properties on the process variables. This enabled a processing window to be established for each material and helped to separate the respective effects of yam handling, textile processing, and consolidation on laminate properties.  相似文献   

14.
The prediction theories for complex systems with a hierarchial structure and their applications to the climate process are a significant and forward-looking field of research.However,up to the present,they are yet not known and understood very well. This paper presents a preliminary theoretical frame for them.As a normal example,the basic behaviors and the dynamic strructure of the climate system are discussed in detail.The conclusions indicate that the climate system may be considered as a cascade of several subsystems located in different hierarchies.Such a dynamic structure is just the cause resulting in the nonstationarity.The conclusions also indicate that the main barrier of the climate prediction in theory derives from the contrary between the stationarity hypothesis for the current prediction theory and the nonstationary behavior of the real climate process.In addition,some work is disussed for detecting the nonstationarity in climate and other geophysical data and predicting the nonstationary process developed in recent years.These works may construct a preliminary base for applying to the climate predictions.  相似文献   

15.
Shengmaisan is a recipe of traditional Chinese medicine, which is composed of three herbs. The interaction among the components from the three herbs of Shengmaisan is investigated using FT-IR, Matrix Assistant Laser Desorption/Ionization Time of flight mass spectrometry (MALDI TOF MS) and TEM observation. Interactions among various components from different herbs cause enhancement of the solubility of some component and suppression of the solubility of others. Results from MALDI-TOF MS show that some components found in the decoction from a single herb disappear when different herbs are decocted together. On the other hand, new substances are produced when two and/or three herbs of Shengmaisan are decocted together. TEM showed that vacuoles formed in the decoction from two and/or three herbs of Shengmaisan but did not occur in any decoction from a single herb. This result provides us direct evidence that the solubilized structure is formed by the interaction among the components from different herbs. This knowledge helps us to understand the therapeutical effects of traditional Chinese medicine.  相似文献   

16.
A new interlacer is used in this paper to investigate the effect of processing conditions on the properties of interlaced yarn. The experimental results show that number of tangles of interlaced yarn changes little with air pressure from 0.2 MPa to 0.5 MPa, and the number of tangles has a maximum value with yarn speed changing. For two yarn directions of entering and leaving yarn guide of interalcer, the yarn speed for the maximum number of tangles is 400 m/rain and 600 m/rain, respectively. The number of tangles changes with air pressure and yarn speed for two yarn directions is compared.  相似文献   

17.
Reconstruction and analysis of time series of ENSO for the last 500 years   总被引:3,自引:0,他引:3  
This paper reports the classification of ENSO into seven categories according to annual (March to February of next year) mean SST of Ni(n)o 3.4 and composite index (ΔI) for the period of 1861~2000. Categories +3, +2, and +1 denote very strong, strong and weak warm episodes (E), -3, -2, and -1 mean very strong, strong and weak cold episodes (A). Absolute SST anomalies are about 1.5 ℃, 1.0 ℃ and 0.5 ℃ respectively for the categories 3, 2, and 1 (or -3, -2, and -1). The normal years are expressed as category 0. Annual categories of ENSO are estimated on the basis of proxy data from AD 1501 to 1860. And a series of ENSO category is established for the period of 1501~2000 in conjunction with the observational data. Comparison of proxy data with observations for 1874~1973 indicates that about 80% of the El Ni(n)o years and La Ni(n)a years can be reconstructed from proxy data, and the reliability of the reconstruction is verified. Analysis of the power spectrum of the reconstructed ENSO series shows significant peaks at QBO, 3~4a (year), 5~6a, and 10a period, the former three are in accordance with the observations for the last 100 years or more. Studies on long term variability of ENSO indicates that ENSO frequency is relatively stationary during the last 500 years, including the Little Ice Age (LIA) (1550~1850) and Modern Warming Period (the 20th century). However, the frequency of E is a little higher in the 20th century and that of A is somewhat higher during the LIA.  相似文献   

18.
Hardy's masterpiece Tess of The D'urbevilles depicts the heroine's miserable life,revealing out the objective cause of society reality and subjective cause of heroine's own character.Society objective reality cause is a hypocritical capitalism morality standard,heroine's own weck character is but:Dare to resist tradition morality being not able to shake off that,and whose double character were yoke her completely.  相似文献   

19.
Kilns are the key equipment in the metallurgy,architectural and chemistry industry. It is the statically indeterminate system with over load, large torque and multi-support. The kiln move axis warp resulting in that the load distribution is asymmetry, cause many mechanical failure and safe accidents and the interruption of the produce, which bring a great losses. Treating the distribution of the kiln load and the complexity of the stiffness change, the all-purpose model and matrix, used to solve the variable-stiffness beam upon complex load, are established in this paper. The resultant force of kiln in vertical and horizontal direction is calculated. Accordingly, the liner formulas for calculating the supporting force of the support wheels are obtained, and the wheel supporting force also can be easily obtained based on each shell warp. This will provide theory conference for safety management and rational maintenance.  相似文献   

20.
Fault diagnosis studying on piston engine , crankshaft and gearbox is focused in this paper .The thrust bearing abrasion caused by axial movement of the crankshaft will affect the force of timing gears and oil pump gears , which will result in the fracture of gears , abnormal ignition, connecting rod cracking and collision of cylinder .Simulation based on CREO software is done to build three-di-mensional models of crankshaft and gears of a WP 10 diesel engine .The models are imported into ADAMS to complete multi-body dynamics simulations .The force analysis of gears in different kinds of axial movements is finished and variations rules of gear dynamic load is obtained .The presented results show that the crankshaft axial movement can cause overload and vibration on gears .Com-bined with the realistic case data , the fault feature through simulation research is validated and early warming parameters of gear fault are proposed .  相似文献   

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