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81.
Efrat Kliper Einor Ben Assayag Ricardo Tarrasch Moran Artzi Amos D. Korczyn Shani Shenhar-Tsarfaty Orna Aizenstein Hen Hallevi Anat Mike Ludmila Shopin Natan M. Bornstein Dafna Ben Bashat 《PloS one》2014,9(8)
Background and purpose
Stroke is a major cause of cognitive impairment and dementia in adults, however the role of the ischemic lesions themselves, on top of other risk factors known in the elderly, remains controversial. This study used structural equation modeling to determine the respective impact of the new ischemic lesions'' volume, preexisting white matter lesions and white matter integrity on post stroke cognitive state.Methods
Consecutive first ever mild to moderate stroke or transient ischemic attack patients recruited into the ongoing prospective TABASCO study underwent magnetic resonance imaging scans within seven days of stroke onset and were cognitively assessed one year after the event using a computerized neuropsychological battery. The volumes of both ischemic lesions and preexisting white matter lesions and the integrity of the normal appearing white matter tissue were measured and their contribution to cognitive state was assessed using structural equation modeling path analysis taking into account demographic parameters. Two models were hypothesized, differing by the role of ischemic lesions'' volume.Results
Structural equation modeling analysis of 142 patients confirmed the predominant role of white matter lesion volume (standardized path coefficient β = −0.231) and normal appearing white matter integrity (β = −0.176) on the global cognitive score, while ischemic lesions'' volume showed no such effect (β = 0.038). The model excluding the ischemic lesion presented better fit to the data (comparative fit index 0.9 versus 0.092).Conclusions
Mild to moderate stroke patients with preexisting white matter lesions are more vulnerable to cognitive impairment regardless of their new ischemic lesions. Thus, these patients can serve as a target group for studies on cognitive rehabilitation and neuro-protective therapies which may, in turn, slow their cognitive deterioration. 相似文献82.
Variation in plant performance between microhabitats is usually attributed to direct mechanisms, such as plant physiological tolerances or competitive interactions. However, indirect mechanisms, such as differences in herbivore pressure mediated by microhabitat differences, could create the same pattern of variation. In this study, we investigated the effect of insect herbivore pressure on the growth of the grassland cactus Opuntia fragilis under different regimes of grassland canopy cover. Our purpose was to establish the extent to which canopy cover plays a direct, competitive role versus an indirect, mediatory role in cactus growth. We manipulated aboveground microhabitat, specifically the cover of adjacent grasses. The three treatments were: (1) open canopy, with grass pinned down away from the cactus; (2) shaded canopy, with a partial mesh cage staked over the cactus; and (3) ambient grass canopy. We measured seasonal plant growth and recorded changes in insect herbivore occurrence and damage in relation to cover. Cactus growth, defined as the change in number of live cladodes, was higher in the open than under either treatment where the plant was more shaded (P<0.05). However, allocation to new growth, measured as the proportion of new segments (cladodes) in a patch, did not differ among cover treatments. Thus, the hypothesis that physiological constraints, or competition for light, limited cactus performance in grass is rejected. Instead, we found that both cladode mortality, caused by the larvae of a cactus moth borer (Melitara dentata), and occurrence of the moth were lower in the open microhabitat than in either shaded microhabitat. Thus, higher net growth in the open, unshaded treatment, rather than representing a release from competition for light with grasses, was better explained as an indirect effect of grass cover on the activity and impact of the cactus moth. These results show that indirect effects can lead to a misinterpretation of experimental data on direct effects. These data also contribute to an improved understanding of mixed results in the biological control of weedy cacti. Clearly, future evaluations of the relative importance of physiology, competition, and insect herbivory in plant performance must be environmentally explicit. 相似文献
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Two extracellular matrix cell surface proteins which bind the proteoglycan-like aggregation factor from the marine sponge Microciona prolifera (MAF) and which may function as physiological receptors for MAF were identified and characterized for the first time. By probing nitrocellulose blots of nonreducing sodium dodecyl sulfate gels containing whole sponge cell protein with iodinated MAF, a 210- and a 68-kDa protein, which have native molecular masses of approximately 200-400 and 70 kDa, were identified. MAF binding to blots is species-specific. It is also sensitive to reduction and is completely abolished by pretreatment of live cells with proteases, as was cellular aggregation, indicating that the 210- and 68-kDa proteins may be located on the cell surface. The additional observations that the 68 kDa is an endoglycosidase F-sensitive glycoprotein and that antisera against whole sponge cells or membranes can immunoprecipitate the 210 kDa when prebound to intact cells are consistent with a cell surface location. Both proteins can be isolated from sponge cell membranes and from the sponge skeleton (insoluble extracellular matrix), but the 210-kDa MAF-binding protein can also be found in the soluble extracellular matrix (buffer washes of cells and skeleton) as well. A third MAF-binding protein of molecular mass 95 kDa was also found in the sponge extracellular matrix but rarely on cells. Both of the cell-associated 210- and 68-kDa proteins are nonintegral membrane proteins, based on Triton X-114 phase separation, flotation of liposomes containing sponge membrane lysates, and their extraction from membranes by buffer washes. Both proteins bind MAF affinity resins, indicating that they each exhibit a moderate affinity for MAF under native conditions. They can also be separated from each other and from the bulk of the protein in an octylpolyoxyethylene extract of membranes by fast protein liquid chromatography Mono Q anion exchange chromatography, as assessed by native dot blot and denaturing Western blot assays. Although neither protein bound to heparin, gelatin, hexosamine, or uronic acid-Sepharose resins, their affinity for an invertebrate proteoglycan, their roles in sponge cell adhesion, and their peripheral membrane protein natures suggest that they may represent early invertebrate analogs of cell-associated vertebrate extracellular matrix adhesion proteins, such as fibronectin or vitronectin, or else an entirely novel set of cell adhesion molecules. 相似文献
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86.
Vanessa Julie Roden Imelda M. Hausmann Alexander Nützel Barbara Seuss Mike Reich Max Urlichs Hans Hagdorn Wolfgang Kiessling 《Palaeontology》2020,63(1):85-102
With 1429 animal species, the Triassic Cassian Formation in the Dolomites, Southern Alps (Italy), yields the highest species richness reported from any spatially constrained pre-Quaternary formation known to science. The high preserved diversity is partly attributable to a high primary diversity governed by the tropical setting, increasing alpha diversity, and the breadth of habitats spurring beta diversity. More important is the excellent preservation of fossils and the ease with which they can be extracted from the poorly lithified sediments. We propose the term ‘liberation Lagerstätten’ to capture this preservational window. In contrast to conservation Lagerstätten, liberation Lagerstätten like the Cassian Formation originate from normal marine conditions but low-grade diagenesis. Molluscs contribute substantially to species richness, comprising 67% of all invertebrate species in the Cassian Formation. The gastropod dominance (39% of all species) is nearly as great as in Recent tropical settings, contradicting the concept of a substantial Cenozoic rise. 相似文献
87.
Zhu W Frost EE Begum F Vora P Au K Gong Y MacNeil B Pillai P Namaka M 《Journal of cellular and molecular medicine》2012,16(8):1856-1865
Multiple sclerosis (MS) is characterized by focal destruction of the white matter of the brain and spinal cord. The exact mechanisms underlying the pathophysiology of the disease are unknown. Many studies have shown that MS is predominantly an autoimmune disease with an inflammatory phase followed by a demyelinating phase. Recent studies alongside current treatment strategies, including glatiramer acetate, have revealed a potential role for brain-derived neurotrophic factor (BDNF) in MS. However, the exact role of BDNF is not fully understood. We used the experimental autoimmune encephalomyelitis (EAE) model of MS in adolescent female Lewis rats to identify the role of BDNF in disease progression. Dorsal root ganglia (DRG) and spinal cords were harvested for protein and gene expression analysis every 3 days post-disease induction (pdi) up to 15 days. We show significant increases in BDNF protein and gene expression in the DRG of EAE animals at 12 dpi, which correlates with peak neurological disability. BDNF protein expression in the spinal cord was significantly increased at 12 dpi, and maintained at 15 dpi. However, there was no significant change in mRNA levels. We show evidence for the anterograde transport of BDNF protein from the DRG to the dorsal horn of the spinal cord via the dorsal roots. Increased levels of BDNF within the DRG and spinal cord in EAE may facilitate myelin repair and neuroprotection in the CNS. The anterograde transport of DRG-derived BDNF to the spinal cord may have potential implications in facilitating central myelin repair and neuroprotection. 相似文献
88.
Joanna Burger Michael Gochfeld Christian Jeitner Taryn Pittfield Meredith Marchioni 《EcoHealth》2012,9(4):399-410
Activity patterns and perceptions play a key role in human health risk, management, and planning. A sample of 233 people attending a Native American festival in Cookeville, Tennessee was interviewed to determine the types, percent participation, and outdoor activities rates, and their perceptions of the importance of characteristics of nuclear sites. Results indicate that: (1) a high percentage of respondents used outdoor environments, (2) they used them for consumptive (hunting, fishing), non-consumptive (hiking, walking, bird-watching), and religious/sacred activities, (3) a higher percentage of respondents engaged in non-consumptive than consumptive activities, (4) praying or meditating, communing with nature, and bird-watching had the highest uses rates (5) the environmental characteristics rated the highest were lack of radionuclides that presented a health risk, no visible smog, clean air, and unpolluted water, (6) the presence of people, buildings and roads were rated the lowest, and (7) Native Americans had higher outdoor participation rates, participated more frequently, and evaluated environmental characteristics higher than did Caucasians. This information can be used by managers to create and maintain outdoor habitats that fit the needs of local people. Planning and management require information on public policy, human needs and requirements, and human perceptions and evaluations of environmental characteristics. 相似文献
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