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排序方式: 共有974条查询结果,搜索用时 156 毫秒
1.
Katherina Walz Devon Cohen Paul M. Neilsen Joseph Foster II. Francesco Brancati Korcan Demir Richard Fisher Michelle Moffat Nienke E. Verbeek Kathrine Bjørgo Adriana Lo Castro Paolo Curatolo Giuseppe Novelli Clemer Abad Cao Lei Lily Zhang Oscar Diaz-Horta Juan I. Young David F. Callen Mustafa Tekin 《Human genetics》2015,134(2):181-190
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A T Abakarov Zh A Belousova 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》1991,41(1):113-121
In acute experiments on cats under nembutal-chloralose anaesthesia the evoked potentials and cellular reactions were studied of suprasylvian vestibular and auditory projection zones to stimulation of vestibular, acoustic and visual nerves and frontal paw. It has been shown that the suprasylvian vestibular zone represents the region of convergence of vestibular, auditory, somatic and visual afferentation. Properties of summary and cellular reactions of the vestibular zone and also the character of interaction of the evoked potentials of homo- and heteromodal origin testify to the absence of significant dominance of vestibular input to this area of the cerebral cortex in cats. Limitation of spreading of labyrinth activity in the cerebral cortex and the absence of dominance of homomodal input in the projection zone should, probably, be considered as typical property of the vestibular system presentation in the cortex, determining the disability of monomodal specific reaction in the sensory-perceptive sphere. 相似文献
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Lance J. Miller Moby Solangi Stan A. Kuczaj II 《Ethology : formerly Zeitschrift fur Tierpsychologie》2010,116(12):1127-1137
Many of the threats to bottlenose dolphins are anthropogenic factors including overfishing, high‐speed boats, chemical runoff, and noise pollution. Having a thorough understanding of the behavior and behavioral patterns of these animals can help with conservation plans to protect this species. This study examined the behavioral states and behavioral events of Atlantic bottlenose dolphins (Tursiops truncatus) in the Mississippi Sound. The behavioral states exhibited by dolphins within the Sound were found to vary by both season and time of day. Dolphins socialized more during the spring and spent more time feeding in the fall. Feeding was highest early in the morning and decreased throughout the day, while socializing occurred at low levels in the morning and increased in the early afternoon. Two distinct forms of social behavior and multiple feeding strategies were exhibited by dolphins within the Sound. Results suggest that certain percussive behavioral events may be used to communicate motivation during transitional behavioral states. These results demonstrate the need for a more complete understanding of dolphin behavior that will facilitate the conservation of this species. 相似文献
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Robert Blake II Elizabeth A. Shute James Waskovsky Arthur P. Harrison JR. 《Geomicrobiology journal》2013,30(3-4):173-192
Abstract Microorganisms capable of aerobic respiration on ferrous ions are spread throughout eubacterial and archaebacterial phyla. Phylogenetically distinct organisms were shown to express spectrally distinct redox‐active biomolecules during autotrophic growth on soluble iron. A new iron‐oxidizing eubacterium, designated as strain Funis, was investigated. Strain Funis was judged to be different from other known iron‐oxidizing bacteria on the bases of comparative lipid analyses, 16S rRNA sequence analyses, and cytochrome composition studies. When grown autotrophically on ferrous ions, Funis produced conspicuous levels of a novel acid‐stable, acid‐soluble yellow cytochrome with a distinctive absorbance peak at 579 nm in the reduced state. Stopped‐flow spectrophotometric kinetic studies were conducted on respiratory chain components isolated from cell‐free extracts of Thiobacillus ferrooxidans. Experimental results were consistent with a model where the primary oxidant of ferrous ions is a highly aggregated c‐type cytochrome that then reduces the periplasmic rusticyanin. The Fe(II)‐dependent, cytochrome c‐catalyzed reduction of the rusticyanin possessed three kinetic properties in common with corresponding intact cells that respire on iron: the same anion specificity, a similar dependence of the rate on the concentration of ferrous ions, and similar rates at saturating concentrations of ferrous ions 相似文献
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The levels of cyclic adenosine monophosphate (cAMP) and two forms of cAMP phosphodiesterase with low (PDE1) and high (PDE2) affinity for the substrate were determined in homogenates from mouse liver and transplanted hepatoma 22. The level of cAMP in the tumour is 3 times lower than that in liver. By te kinetic parameters (Vmax, Km, pH optimum) adenylate cyclase from tumour does not show any significant differences as compared to the liver enzyme; the enzyme from hepatoma is, however, more sensitive to activation by F- ions. The activities of adenylate cyclase in liver and tumour cells are the same. Phosphodiesterases of cAMP from tumour and liver cells are similar in their Km values (3,3-10(-4) M for PDE1 and 2-10(-6) M for PDE2); however, the maximal and real rates of cAMP hydrolysis in hepatoma are much higher than in liver. The fact that both cAMP phosphodiesterase activities have similar dependence on Mg2+ and Ca2+ concentrations, suggests that PDE1 is a latent form of PDE2. In tumour cells the equilibrium between these two forms is probably shifted towards the enzyme with high affinity for the substrate. The results suggest that a decreased cAMP level in hepatoma cells (as compared to the liver) is due to the activation of PDE2. 相似文献
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Fabio P. Nunes Vanessa L. Merker Dominique Jennings Paul A. Caruso Emmanuelle di Tomaso Alona Muzikansky Fred G. Barker II Anat Stemmer-Rachamimov Scott R. Plotkin 《PloS one》2013,8(3)
Bevacizumab treatment can result in tumor shrinkage of progressive vestibular schwannomas in some neurofibromatosis 2 (NF2) patients but its effect on meningiomas has not been defined.To determine the clinical activity of bevacizumab against NF2-related meningiomas, we measured changes in volume of meningiomas in NF2 patients who received bevacizumab for treatment of progressive vestibular schwannomas. A radiographic response was defined as a 20% decrease in tumor size by volumetric MRI analysis. In addition, we determined the expression pattern of growth factors associated with tumor angiogenesis in paraffin-embedded tissues from 26 unrelated meningiomas. A total of 48 meningiomas in 15 NF2 patients were included in this study with a median follow up time of 18 months. A volumetric radiographic response was seen in 29% of the meningiomas (14/48). Tumor shrinkage was not durable: the median duration of response was 3.7 months and the median time to progression was 15 months. There was no significant correlation between pre-treatment growth rate and meningioma response in regression models. Tissue analysis showed no correlation between tumor microvascular density and expression of VEGF pathway components. This data suggests that, in contrast to schwannomas, activation of VEGF pathway is not the primary driver of angiogenesis in meningiomas. Our results suggest that a minority of NF2-associated meningiomas shrink during bevacizumab therapy and that these responses were of short duration. These results are comparable to previous studies of bevacizumab in sporadic meningiomas. 相似文献