Brain membrane cholesterol domains,aging and amyloid beta-peptides

Lipids are essential for the structural and functional integrity of membranes. Membrane lipids are not randomly distributed but are localized in different domains. These domains consist of the exofacial and cytofacial leaflets, cholesterol pools, annular lipids, and lipid rafts. Membrane lipid domains have been proposed to be involved in a variety of different functions including e.g. signal transduction, lipid transport and metabolism, and cell growth. Membrane lipid domains have been identified in brain and can be modified by different experimental conditions, aging and certain neurodegenerative diseases. Recent data reveal the very interesting possibility that membrane lipid domains may be a target of Alzheimer's disease. There is a growing body of evidence showing an association between cholesterol and Alzheimer's disease, and cholesterol is a major component of membrane lipid domains. Here we discuss recent data on brain membrane lipid domains emphasizing the structural and functional role of cholesterol. In addition, lipid domains and aging, and the potential interaction of lipid domains and amyloid beta-peptides (Abeta) that are a major component of senile plaques in brains of Alzheimer's patients are considered. We propose that age changes in the asymmetric distribution of cholesterol in contrast to total or bulk cholesterol in neuronal plasma membranes provides a cooperative environment for accumulation of Abeta in plasma membranes and the accumulation of Abeta is due in part to a direct physico-chemical interaction with cholesterol in the membrane exofacial or outer leaflet.     

Morphological and morphometric characteristics of choroid plexus psammoma bodies during the human aging

Psammoma bodies are one of many choroid plexus aging changes which origin is still enigma for the scientists. During our investigation psammoma bodies were studied on 30 postmortem brains by light microscopy. They stained red with HE, and were PAS and AB PAS positive. The largest number of lamellas were stained blue with Mallory's connective tissue stain, except peripheral and next to the center lamella which stained red. During the aging, psammoma bodies became larger and more irregular, which was followed with group area and perimeter, single psammoma body average area and average perimeter, average diameter and contour index increase. Psammoma bodies mearged in the second and the third age group and mearging process led to larger and more irregular structures formation. The results of this investigation suggest that psammoma bodies are more frequent in choroid plexus of healthy older people and during the aging they obtain larger dimensions, more irregular contours, which is the result of their mutual mearging.     

Chromosomal imbalances in diffuse large B-cell lymphoma detected by comparative genomic hybridization.

Diffuse large B-cell lymphoma (DLBCL) is the most common form of non-Hodgkin lymphoma. In contrast to many other hematological malignancies, no chromosomal abnormalities with a diagnostic or prognostic value have been identified in DLBCL. Numerical chromosomal imbalances were characterized by comparative genomic hybridization (CGH) performed on 54 DLBCL tumors from a total of 40 patients. The clonal relatedness was demonstrated in 9 of 11 pairs of matched diagnostic tumors and their relapses as determined by IGH gene rearrangement analysis and/or the CGH profiles. Furthermore, immunohistochemical expression analyses of BCL2 and BCL6/LAZ3 were performed on all cases. Copy number changes were detected in 94% of the diagnostic tumor samples and in all of the relapses. Chromosomal losses in diagnostic tumors were preferentially observed at 8p22-pter (29%), 1p34-pter (26%), 6q23-qter (20%), 17p12-pter (17%) and 22q (17%), 9p23-pter (14%), whereas gains were mainly seen in Xq25-26 (43%), 13q22 (26%), 12cen-q14 (20%), 3q24-25 (11%), 7 (11%), and 18q12-21 (11%). Loss of 22q was significantly more commonly seen in the diagnostic tumor samples with more advanced clinical stage in other words, Stage III-IV compared with Stage I-II, and band 18q21 was significantly more often gained in relapses as compared to diagnostic tumors. None of the recurrent alterations were detected as a single abnormality, suggesting that other genetic lesions below the detection level of CGH may be the initiating event in the tumorigenesis of DLBCL. However, the distribution of CGH alterations support the idea of a progression of genetic events where loss of 8p and 9p and gain of 3q, 13q, and 18q would represent relatively early events because they were distributed in tumors with only two abnormalities.     

Development and validation of a CGH microarray for clinical cytogenetic diagnosis.

PURPOSE: We developed a microarray for clinical diagnosis of chromosomal disorders using large insert genomic DNA clones as targets for comparative genomic hybridization (CGH). METHODS: The array contains 362 FISH-verified clones that span genomic regions implicated in over 40 known human genomic disorders and representative subtelomeric clones for each of the 41 clinically relevant human chromosome telomeres. Three or four clones from almost all deletion or duplication genomic regions and three or more clones for each subtelomeric region were included. We tested chromosome microarray analysis (CMA) in a masked fashion by examining genomic DNA from 25 patients who were previously ascertained in a genetic clinic and studied by conventional cytogenetics. A novel software package implemented in the R statistical programming language was developed for normalization, visualization, and inference. RESULTS: The CMA results were entirely consistent with previous cytogenetic and FISH findings. For clone by clone analysis, the sensitivity was estimated to be 96.7% and the specificity was 99.1%. Major advantages of this selected human genome array include the following: interrogation of clinically relevant genomic regions, the ability to test for a wide range of duplication and deletion syndromes in a single analysis, the ability to detect duplications that would likely be undetected by metaphase FISH, and ease of confirmation of suspected genomic changes by conventional FISH testing currently available in the cytogenetics laboratory. CONCLUSION: The array is an attractive alternative to telomere FISH and locus-specific FISH, but it does not include uniform coverage across the arms of each chromosome and is not intended to substitute for a standard karyotype. Limitations of CMA include the inability to detect both balanced chromosome changes and low levels of mosaicism.     

Genetic basis for individual variations in pain perception and the development of a chronic pain condition

Pain sensitivity varies substantially among humans. A significantpart of the human population develops chronic pain conditionsthat are characterized by heightened pain sensitivity. We identifiedthree genetic variants (haplotypes) of the gene encoding catecholamine-O-methyltransferase(COMT) that we designated as low pain sensitivity (LPS), averagepain sensitivity (APS) and high pain sensitivity (HPS). We showthat these haplotypes encompass 96% of the human population,and five combinations of these haplotypes are strongly associated(P=0.0004) with variation in the sensitivity to experimentalpain. The presence of even a single LPS haplotype diminishes,by as much as 2.3 times, the risk of developing myogenous temporomandibularjoint disorder (TMD), a common musculoskeletal pain condition.The LPS haplotype produces much higher levels of COMT enzymaticactivity when compared with the APS or HPS haplotypes. Inhibitionof COMT in the rat results in a profound increase in pain sensitivity.Thus, COMT activity substantially influences pain sensitivity,and the three major haplotypes determine COMT activity in humansthat inversely correlates with pain sensitivity and the riskof developing TMD.     

Yellow fever virus strains Asibi and 17D-204 infect human umbilical cord endothelial cells and induce novel changes in gene expression

Yellow fever (YF) is a zoonotic infection with more than 200,000 cases reported annually. Relatively little is known about YF pathogenesis in humans. In this study, we demonstrate that human vascular endothelial cells are susceptible to infection with wild-type and vaccine strains of the YFV and that these infections lead to a differential cellular response to infection. The infection of endothelial cells with either virus resulted in a significant induction of interferon-inducible genes p 78 and Cig 5 while wild-type virus induced a much more pronounced IL 6 and Bc l2 response than did the vaccine strain. Both viruses induced RANTES gene expression, but only the wild-type virus had corresponding increases in RANTES protein expression. The results demonstrate that the wild-type and vaccine strains of YFV elicit significantly different responses to infection in endothelial cells, despite being nearly identical genetically. These differences may account for the attenuated phenotype of the YFV vaccine strain, though the mechanism remains unclear. These data also point to a role for vascular endothelial cells in YF hemorrhagic fever and also suggest that IL 6 may play a role in increased viral pathogenesis, perhaps by influencing coagulation via release of coagulation co-factors such as fibrin or fibrinogen.     

Neutrophil differentiated HL-60 cells model Mac-1 (CD11b/CD18)-independent neutrophil transepithelial migration

During active intestinal inflammation granulocytes accumulate in the lumen of the gut where they damage the epithelium through the release of various products such as reactive oxygen species and proteolytic enzymes. Previously, using function blocking monoclonal antibodies, we showed that neutrophil migration across intestinal epithelial monolayers in response to various chemoattractants was partially beta(2) integrin Mac-1 (CD11b/CD18)-independent. Here, we show that treating neutrophils with intact monoclonal antibody (mAb) to CD18 activates the cells to express more CD11b. Thus our goal now was to determine whether neutrophil Mac-1-independent transepithelial migration proceeds independently of prior cell activation through Mac-1. We took two approaches, one using blocking Fab' fragments of mAb to CD18 and the second was to develop a neutrophil differentiated HL-60 cell line which is Mac-1 deficient to further study neutrophil/epithelial cell interaction. Anti-CD18 Fab' minimally activated neutrophils but inhibited approximately 75% of transepithelial migration to fMLP while having a minimal effect (相似文献   

Assessment of stem cell/biomaterial combinations for stem cell-based tissue engineering

Biomaterials are used in tissue engineering with the aim to repair or reconstruct tissues and organs. Frequently, the identification and development of biomaterials is an iterative process with biomaterials being designed and then individually tested for their properties in combination with one specific cell type. However, recent efforts have been devoted to systematic, combinatorial and parallel approaches to identify biomaterials, suitable for specific applications. Embryonic and adult stem cells represent an ideal cell source for tissue engineering. Since stem cells can be readily isolated, expanded and transplanted, their application in cell-based therapies has become a major focus of research. Biomaterials can potentially influence e.g. stem cell proliferation and differentiation in both, positive or negative ways and biomaterial characteristics have been applied to repel or attract stem cells in a niche-like microenvironment. Our consortium has now established a grid-based platform to investigate stem cell/biomaterial interactions. So far, we have assessed 140 combinations of seven different stem cell types and 19 different polymers performing systematic screening assays to analyse parameters such as morphology, vitality, cytotoxicity, apoptosis, and proliferation. We thus can suggest and advise for and against special combinations for stem cell-based tissue engineering.