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排序方式: 共有364条查询结果,搜索用时 31 毫秒
41.
42.
Seidl K Solis NV Bayer AS Hady WA Ellison S Klashman MC Xiong YQ Filler SG 《PloS one》2012,7(6):e39633
Endothelial cells are important in the pathogenesis of bloodstream infections caused by Candida albicans and Staphylococcus aureus. Numerous investigations have used human umbilical vein endothelial cells (HUVECs) to study microbial-endothelial cell interactions in vitro. However, the use of HUVECs requires a constant supply of umbilical cords, and there are significant donor-to-donor variations in these endothelial cells. The use of an immortalized endothelial cell line would obviate such difficulties. One candidate in this regard is HMEC-1, an immortalized human dermal microvascular endothelial cell line. To determine if HMEC-1 cells are suitable for studying the interactions of C. albicans and S. aureus with endothelial cells in vitro, we compared the interactions of these organisms with HMEC-1 cells and HUVECs. We found that wild-type C. albicans had significantly reduced adherence to and invasion of HMEC-1 cells as compared to HUVECs. Although wild-type S. aureus adhered to and invaded HMEC-1 cells similarly to HUVECs, an agr mutant strain had significantly reduced invasion of HMEC-1 cells, but not HUVECs. Furthermore, HMEC-1 cells were less susceptible to damage induced by C. albicans, but more susceptible to damage caused by S. aureus. In addition, HMEC-1 cells secreted very little IL-8 in response to infection with either organism, whereas infection of HUVECs induced substantial IL-8 secretion. This weak IL-8 response was likely due to the anatomic site from which HMEC-1 cells were obtained because infection of primary human dermal microvascular endothelial cells with C. albicans and S. aureus also induced little increase in IL-8 production above basal levels. Thus, C. albicans and S. aureus interact with HMEC-1 cells in a substantially different manner than with HUVECs, and data obtained with one type of endothelial cell cannot necessarily be extrapolated to other types. 相似文献
43.
Ahlqvist KJ Hämäläinen RH Yatsuga S Uutela M Terzioglu M Götz A Forsström S Salven P Angers-Loustau A Kopra OH Tyynismaa H Larsson NG Wartiovaara K Prolla T Trifunovic A Suomalainen A 《Cell metabolism》2012,15(1):100-109
Somatic stem cell (SSC) dysfunction is typical for different progeroid phenotypes in mice with genomic DNA repair defects. MtDNA mutagenesis in mice with defective Polg exonuclease activity also leads to progeroid symptoms, by an unknown mechanism. We found that Polg-Mutator mice had neural (NSC) and hematopoietic progenitor (HPC) dysfunction already from embryogenesis. NSC self-renewal was decreased in vitro, and quiescent NSC amounts were reduced in vivo. HPCs showed abnormal lineage differentiation leading to anemia and lymphopenia. N-acetyl-L-cysteine treatment rescued both NSC and HPC abnormalities, suggesting that subtle ROS/redox changes, induced by mtDNA mutagenesis, modulate SSC function. Our results show that mtDNA mutagenesis affected SSC function early but manifested as respiratory chain deficiency in nondividing tissues in old age. Deletor mice, having mtDNA deletions in postmitotic cells and no progeria, had normal SSCs. We propose that SSC compartment is sensitive to mtDNA mutagenesis, and that mitochondrial dysfunction in SSCs can underlie progeroid manifestations. 相似文献
44.
Gaál EI Salo P Kristiansson K Rehnström K Kettunen J Sarin AP Niemelä M Jula A Raitakari OT Lehtimäki T Eriksson JG Widen E Günel M Kurki M von und Zu Fraunberg M Jääskeläinen JE Hernesniemi J Järvelin MR Pouta A;International Consortium for Blood Pressure Genome-Wide Association Studies Newton-Cheh C Salomaa V Palotie A Perola M 《PLoS genetics》2012,8(3):e1002563
Although genome-wide association studies (GWAS) have identified hundreds of complex trait loci, the pathomechanisms of most remain elusive. Studying the genetics of risk factors predisposing to disease is an attractive approach to identify targets for functional studies. Intracranial aneurysms (IA) are rupture-prone pouches at cerebral artery branching sites. IA is a complex disease for which GWAS have identified five loci with strong association and a further 14 loci with suggestive association. To decipher potential underlying disease mechanisms, we tested whether there are IA loci that convey their effect through elevating blood pressure (BP), a strong risk factor of IA. We performed a meta-analysis of four population-based Finnish cohorts (n(FIN) = 11 266) not selected for IA, to assess the association of previously identified IA candidate loci (n = 19) with BP. We defined systolic BP (SBP), diastolic BP, mean arterial pressure, and pulse pressure as quantitative outcome variables. The most significant result was further tested for association in the ICBP-GWAS cohort of 200 000 individuals. We found that the suggestive IA locus at 5q23.2 in PRDM6 was significantly associated with SBP in individuals of European descent (p(FIN) = 3.01E-05, p(ICBP-GWAS) = 0.0007, p(ALL) = 8.13E-07). The risk allele of IA was associated with higher SBP. PRDM6 encodes a protein predominantly expressed in vascular smooth muscle cells. Our study connects a complex disease (IA) locus with a common risk factor for the disease (SBP). We hypothesize that common variants in PRDM6 can contribute to altered vascular wall structure, hence increasing SBP and predisposing to IA. True positive associations often fail to reach genome-wide significance in GWAS. Our findings show that analysis of traditional risk factors as intermediate phenotypes is an effective tool for deciphering hidden heritability. Further, we demonstrate that common disease loci identified in a population isolate may bear wider significance. 相似文献
45.
Saarelainen KS Ranna M Rabe H Sinkkonen ST Möykkynen T Uusi-Oukari M Linden AM Lüddens H Korpi ER 《Journal of neurochemistry》2008,105(2):338-350
The behavioral and functional significance of the extrasynaptic inhibitory GABA(A) receptors in the brain is still poorly known. We used a transgenic mouse line expressing the GABA(A) receptor alpha6 subunit gene in the forebrain under the Thy-1.2 promoter (Thy1alpha6) mice ectopically expressing alpha6 subunits especially in the hippocampus to study how extrasynaptically enriched alphabeta(gamma2)-type receptors alter animal behavior and receptor responses. In these mice extrasynaptic alpha6beta receptors make up about 10% of the hippocampal GABA(A) receptors resulting in imbalance between synaptic and extrasynaptic inhibition. The synthetic GABA-site competitive agonist gaboxadol (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol; 3 mg/kg) induced remarkable anxiolytic-like response in the light : dark exploration and elevated plus-maze tests in Thy1alpha6 mice, while being almost inactive in wild-type mice. The transgenic mice also lost quicker and for longer time their righting reflex after 25 mg/kg gaboxadol than wild-type mice. In hippocampal sections of Thy1alpha6 mice, the alpha6beta receptors could be visualized autoradiographically by interactions between gaboxadol and GABA via [(35)S]TBPS binding to the GABA(A) receptor ionophore. Gaboxadol inhibition of the binding could be partially prevented by GABA. Electrophysiology of recombinant GABA(A) receptors revealed that GABA was a partial agonist at alpha6beta3 and alpha6beta3delta receptors, but a full agonist at alpha6beta3gamma2 receptors when compared with gaboxadol. The results suggest strong behavioral effects via selective pharmacological activation of enriched extrasynaptic alphabeta GABA(A) receptors, and the mouse model represents an example of the functional consequences of altered balance between extrasynaptic and synaptic inhibition. 相似文献
46.
Water-borne seed transport and seed deposition during flooding in a small river-valley in Northern Germany 总被引:1,自引:0,他引:1
Water-borne seed transport and seed deposition during flooding were studied in the Upper Eider river (N-Germany) by direct sampling of the rivers seed content with aquatic seed traps and by analysing the number of deposited seeds on sedimentation mats which were exposed near the river on the soil surface during a flooding period of approx. three weeks.The number of seeds which were transported at the surface of the river Eider was continuously analysed by four aquatic seed traps for a period of 20 weeks (July–December 2000). To test the capture rate of these traps, a recapture experiment with colour marked seeds of Helianthus annuus L. was carried out. During the investigation period approx. 9000 seeds of 76 species were captured by the four aquatic seed traps. The number of trapped seeds varied both spatially (across the river profile) and temporally. Considering this variation and the capture rate of the traps, the water-borne seed transport was estimated to be 3139 seeds per week and meter of the river profile.The seed deposition during a flood in early spring 2002 was analysed by using 20 sedimentation mats. To distinguish effects of seed dispersal into patches from outside from seed rearrangement within patches, the water-borne seed transport was excluded from one half of the mats by fencing them with a woven fabric which was permeable for water but not for floating seeds. Outside of the exclosures 152 viable seeds of 26 species were deposited on the sedimentation mats while only one single seedling was found on mats from which water-borne seed transport was excluded.The results demonstrate that hydrochorous dispersal processes might play an important role in connecting otherwise fragmented populations in periodically flooded habitats along rivers. 相似文献
47.
Forest classification in an Amazonian rainforest landscape using pteridophytes as indicator species 总被引:1,自引:0,他引:1
Habitat classification systems are poorly developed for tropical rainforests, where extremely high plant species richness causes numerous methodological difficulties. We used an indicator species approach to classify primary rainforest vegetation for purposes of comparative wildlife habitat studies. We documented species composition of pteridophytes (ferns and fern allies) in 635 plots (2×100 m) along 8 transects within a continuous rainforest landscape in northeastern Peruvian Amazonia. Considerable floristic variation was found when the data were analyzed using multivariate methods. The obtained forest classification was interpreted with the help of indicator value analysis and known soil preferences of the pteridophyte species. The final classification included four forest types: 1) inundated forests, 2) terrace forests, 3) intermediate tierra firme forests and 4) Pebas Formation forests. This rapid and relatively simple vegetation classification technique offers a practical, quantitative method for large-scale vegetation inventory in complex rainforest landscapes. 相似文献
48.
Nielsen Kristian Fog Huttunen Kati Hyvärinen Anne Andersen Birgitte Jarvis Bruce B. Hirvonen Maija-Riitta 《Mycopathologia》2002,154(4):201-206
The metabolite profiles of 20 Stachybotrys spp.isolates from Finnish water-damaged buildings were compared with their biological activities. Effects of purified compounds
on cytotoxicity and production of inflammatory mediators such as nitric oxide, IL-6 and TNFα in murine RAW264.7 macrophage
cells were studied. The 11isolates belonging to the satratoxin-producing chemotype were highly cytotoxic to the macrophages.
The isolates inducing inflammatory mediators all belonged to the atranone-producing chemotype, but pure atranones B, and D
did not elicit a response in the bioassay. Altogether, cytotoxicity ofStachybotrys sp. isolates appear to be related to satratoxin production whereas the specific component inducing inflammatory responses
in atranone-producing isolates remains obscure.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
49.
Konstantina Zografou George C. Adamidis Marjan Komnenov Vassiliki Kati Pavlos Sotirakopoulos Eva Pitta Maria Chatzaki 《Journal of Insect Conservation》2017,21(3):531-543
Our understanding of arthropod responses to environmental pressures is limited, especially for the poorly studied Mediterranean region. In the light of likely further environmental change and the need for protocols for rapid biodiversity assessment, we measured how the abundance and species richness of two taxa, ground spiders and Orthoptera, belonging to different functional groups, fluctuates intra- seasonally (early-mid-late summer) and across habitat types (grasslands, maquis, forests). We also tested their surrogate value. Spiders were found to have higher species richness and abundance almost throughout the investigation. Orthoptera had lower species richness and abundance in forests compared to grasslands and maquis, while no significant difference between habitats was revealed for spiders. Early-summer was the richest period for spiders while mid-summer was the richest for Orthoptera. Canopy cover was found to significantly influence community composition of both groups, while herb height and cover of stones was a determinant factor for Orthoptera only. There was a significant congruence between the two groups and Orthoptera provided the best complementary network. Our results show that diversity patterns of both spiders and Orthoptera are sensitive to environmental changes even over short time-scales (e.g. within the summer period) and space (e.g. across different habitat types), suggesting that small inexpensive experimental designs may still reveal community dynamics. For conservation purposes, we advise a focus on variables regulating habitat heterogeneity and microhabitat characteristics. We provide a list of the most influential species and propose the most effective network for obtaining information on the local fauna. 相似文献
50.
Rapid environmental fluctuations are ubiquitous in the wild, yet majority of experimental studies mostly consider effects of slow fluctuations on organism. To test the evolutionary consequences of fast fluctuations, we conducted nine independent experimental evolution experiments with bacteria. Experimental conditions were same for all species, and we allowed them to evolve either in fluctuating temperature alternating rapidly between 20°C and 40°C or at constant 30°C temperature. After experimental evolution, we tested the performance of the clones in both rapid fluctuation and in constant environments (20°C, 30°C and 40°C). Results from experiments on these nine species were combined meta‐analytically. We found that overall the clones evolved in the fluctuating environment had evolved better efficiency in tolerating fluctuations (i.e., they had higher yield in fluctuating conditions) than the clones evolved in the constant environment. However, we did not find any evidence that fluctuation‐adapted clones would have evolved better tolerance to any measured constant environments (20°C, 30°C, and 40°C). Our results back up recent empirical findings reporting that it is hard to predict adaptations to fast fluctuations using tolerance curves. 相似文献