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1.
Michael J Stobart Debra Parchaliuk Sharon LR Simon Jillian LeMaistre Jozef Lazar Richard Rubenstein J David Knox 《Molecular neurodegeneration》2007,2(1):1-13
Background
Alzheimer's disease (AD) is characterized by a decline in cognitive function and accumulation of amyloid-β peptide (Aβ) in extracellular plaques. Mutations in amyloid precursor protein (APP) and presenilins alter APP metabolism resulting in accumulation of Aβ42, a peptide essential for the formation of amyloid deposits and proposed to initiate the cascade leading to AD. However, the role of Aβ40, the more prevalent Aβ peptide secreted by cells and a major component of cerebral Aβ deposits, is less clear. In this study, virally-mediated gene transfer was used to selectively increase hippocampal levels of human Aβ42 and Aβ40 in adult Wistar rats, allowing examination of the contribution of each to the cognitive deficits and pathology seen in AD.Results
Adeno-associated viral (AAV) vectors encoding BRI-Aβ cDNAs were generated resulting in high-level hippocampal expression and secretion of the specific encoded Aβ peptide. As a comparison the effect of AAV-mediated overexpression of APPsw was also examined. Animals were tested for development of learning and memory deficits (open field, Morris water maze, passive avoidance, novel object recognition) three months after infusion of AAV. A range of impairments was found, with the most pronounced deficits observed in animals co-injected with both AAV-BRI-Aβ40 and AAV-BRI-Aβ42. Brain tissue was analyzed by ELISA and immunohistochemistry to quantify levels of detergent soluble and insoluble Aβ peptides. BRI-Aβ42 and the combination of BRI-Aβ40+42 overexpression resulted in elevated levels of detergent-insoluble Aβ. No significant increase in detergent-insoluble Aβ was seen in the rats expressing APPsw or BRI-Aβ40. No pathological features were noted in any rats, except the AAV-BRI-Aβ42 rats which showed focal, amorphous, Thioflavin-negative Aβ42 deposits.Conclusion
The results show that AAV-mediated gene transfer is a valuable tool to model aspects of AD pathology in vivo, and demonstrate that whilst expression of Aβ42 alone is sufficient to initiate Aβ deposition, both Aβ40 and Aβ42 may contribute to cognitive deficits. 相似文献2.
Claudia G Petersen Fabiana C Massaro Ana L Mauri Joao BA Oliveira Ricardo LR Baruffi Jose G FrancoJr 《Reproductive biology and endocrinology : RB&E》2010,8(1):149
Background
The present study aimed to evaluate the efficacy of the hyaluronic acid (HA) binding assay in the selection of motile spermatozoa with normal morphology at high magnification (8400x). 相似文献3.
4.
Stephen LR Ellison Claire A English Malcolm J Burns Jacquie T Keer 《BMC biotechnology》2006,6(1):33-11
Background
Accurate quantification of DNA using quantitative real-time PCR at low levels is increasingly important for clinical, environmental and forensic applications. At low concentration levels (here referring to under 100 target copies) DNA quantification is sensitive to losses during preparation, and suffers from appreciable valid non-detection rates for sampling reasons. This paper reports studies on a real-time quantitative PCR assay targeting a region of the human SRY gene over a concentration range of 0.5 to 1000 target copies. The effects of different sample preparation and calibration methods on quantitative accuracy were investigated. 相似文献5.
6.
The 18S ribosomal RNAs of 21 tetrapods were sequenced and aligned with five
published tetrapod sequences. When the coelacanth was used as an outgroup,
Lissamphibia (living amphibians) and Amniota (amniotes) were found to be
statistically significant monophyletic groups. Although little resolution
was obtained among the lissamphibian taxa, the amniote sequences support a
sister-group relationship between birds and mammals. Portions of the 28S
ribosomal RNA (rRNA) molecule in 11 tetrapods also were sequenced, although
the phylogenetic results were inconclusive. In contrast to previous
studies, deletion or down- weighting of base-paired sites were found to
have little effect on phylogenetic relationships. Molecular evidence for
amniote relationships is reviewed, showing that three genes
(beta-hemoglobin, myoglobin, and 18S rRNA) unambiguously support a
bird-mammal relationship, compared with one gene (histone H2B) that favors
a bird- crocodilian clade. Separate analyses of four other genes (alpha-
crystallin A, alpha-hemoglobin, insulin, and 28S rRNA) and a combined
analysis of all sequence data are inconclusive, in that different groups
are defined in different analyses and none are strongly supported. It is
suggested that until sequences become available from a broader array of
taxa, the molecular evidence is best evaluated at the level of individual
genes, with emphasis placed on those studies with the greatest number of
taxa and sites. When this is done, a bird-mammal relationship is most
strongly supported. When regarded in combination with the morphological
evidence for this association, it must be considered at least as plausible
as a bird-crocodilian relationship.
相似文献
7.
Human haemoglobin was immobilized by cross-linking with glutaraldehyde as soluble polymers and artificial membranes. Effects of pH and 2,3-diphosphoglycerate on oxygen binding and cross-linking were studied with haemoglobin immobilized in both the oxy and deoxy states. The cooperativity is suppressed and the affinity is increased when compared with native haemoglobin. Haemoglobin immobilized in the oxy state exhibited a higher oxygen affinity than that immobilized in the deoxy state. The alkaline Bohr effect is not significantly different from that of native haemoglobin. The 2,3-diphosphoglycerate influence on oxygen binding was reduced by one third with immobilization. In order to separate the chemical and the "conformation freezing' effects on the properties of immobilized haemoglobin, glutaraldehyde-modified haemoglobin in oxy and deoxy states was produced. Oxygen binding was studied and chemical modifications were checked by electrophoresis and gel filtration. This chemically modified haemoglobin without polymerization and without intra-chain bridging exhibits a behaviour similar to that of cross-linked soluble polymers or membranes of haemoglobin. 相似文献
8.
Didier Guillochon Bernard Cambou Laurent Esclade Daniel Thomas 《Enzyme and microbial technology》1984,6(4):161-164
Aniline hydroxylase activity of ascorbic acid and dihydroxyfumaric acid-haemoglobin systems has been studied. Hydroxylase activity of haemoglobin immobilized by crosslinking with glutaraldehyde as insoluble particles is reported. Activity yields after immobilization and kinetic constants were estimated. A peroxidative mechanism is postulated in which ascorbic acid and dihydroxyfumaric acid are electron donors as well as competitive substrates. 相似文献
9.
Kate L E Phillips Neil Chiverton Anthony LR Michael Ashley A Cole Lee M Breakwell Gail Haddock Rowena AD Bunning Alison K Cross Christine L Le Maitre 《Arthritis research & therapy》2013,15(6):R213
Introduction
The aims of these studies were to identify the cytokine and chemokine expression profile of nucleus pulposus (NP) cells and to determine the relationships between NP cell cytokine and chemokine production and the characteristic tissue changes seen during intervertebral disc (IVD) degeneration.Methods
Real-time q-PCR cDNA Low Density Array (LDA) was used to investigate the expression of 91 cytokine and chemokine associated genes in NP cells from degenerate human IVDs. Further real-time q-PCR was used to investigate 30 selected cytokine and chemokine associated genes in NP cells from non-degenerate and degenerate IVDs and those from IVDs with immune cell infiltrates (‘infiltrated’). Immunohistochemistry (IHC) was performed for four selected cytokines and chemokines to confirm and localize protein expression in human NP tissue samples.Results
LDA identified the expression of numerous cytokine and chemokine associated genes including 15 novel cytokines and chemokines. Further q-PCR gene expression studies identified differential expression patterns in NP cells derived from non-degenerate, degenerate and infiltrated IVDs. IHC confirmed NP cells as a source of IL-16, CCL2, CCL7 and CXCL8 and that protein expression of CCL2, CCL7 and CXCL8 increases concordant with histological degenerative tissue changes.Conclusions
Our data indicates that NP cells are a source of cytokines and chemokines within the IVD and that these expression patterns are altered in IVD pathology. These findings may be important for the correct assessment of the ‘degenerate niche’ prior to autologous or allogeneic cell transplantation for biological therapy of the degenerate IVD. 相似文献10.
João Batista A Oliveira Mario Cavagna Claudia G Petersen Ana L Mauri Fabiana C Massaro Liliane FI Silva Ricardo LR Baruffi Jose G Franco Jr 《Reproductive biology and endocrinology : RB&E》2011,9(1):1-7