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911.
Crystallization and preliminary x-ray diffraction studies of recombinant human interleukin-1 beta 总被引:3,自引:0,他引:3
Recombinant human interleukin-1 beta has been crystallized into a tetragonal cell. The unit cell constants are a = b = 54.9 A, c = 76.8 A, and alpha = beta = gamma = 90 degrees. The crystals diffract to better than 1.9 A and are suitable for high resolution data collection. The crystallization conditions and general crystal data are presented. 相似文献
912.
Ribosome specificity of archaebacterial elongation factor 2. Studies with hybrid polyphenylalanine synthesis systems 总被引:2,自引:0,他引:2
Polyphenylalanine synthesis with ribosomes and two separated, partially purified elongation factors (EF) was measured in cell-free systems from the archaebacteria Thermoplasma acidophilum and Methanococcus vannielii, in an eukaryotic system from rat liver and an eubacterial one with Escherichia coli ribosomes and factors from Thermus thermophilus. By substitution of heterologous EF-2 or EF-G, respectively, for the homologous factors, ribosome specificity was shown to be restricted to factors from the same kingdom. In contrast, EF-1 from T. thermophilus significantly cooperated with ribosomes from T. acidophilum. 相似文献
913.
Lukas Leten Majda Azermai Maarten Wauters Jan De Lepeleire 《Tijdschrift voor gerontologie en geriatrie》2017,48(4):177-186
Background
Although guidelines put forward non-pharmacological therapies and advise against the chronic use of psychotropic drugs, these are still being prescribed regularly in Belgian nursing homes.Goal
To explore the reasons for initiation, continuation and cessation of psychotropic drug treatment of elderly with dementia and behavioral problems, residing in the nursing home.Method
Twenty-seven interviews from an earlier project were used, in which a semi-structured interview was conducted with the nursing staff, the physicians and the caretakers of eleven randomly selected residents from three nursing homes. A qualitative analysis was performed by three independent researchers according to ‘The Qualitative Analysis Guide of Leuven (QUAGOL)’. A first analysis focused on the process of initiation, continuation and cessation of medication. A second analysis compared the different participants of each interview and looked for similarities and differences.Results
Seventeen codes were developed for four themes: (1) To initiate, to continue or to cease?; (2) Behavior; (3) Therapy; and (4) Alternatives. The reasons for initiating psychotropic drugs were reducing disruptive behavior and improving the quality of life of the resident. A comparison between the interviewed showed that psychotropic drugs were initiated at the request of the nursing staff. Neither doctors nor nurses considered the monitoring of the drug therapy their task, and tended to pass on this responsibility. Once psychotropic drugs were started, the treatment was chronic but remained part of a dynamic process in which a balance was sought between benefits and adverse effects. More insights into the behavior of the resident led to a better treatment of the behavioral problems.Conclusion
Nurses play an important role in the initiation and continuation of psychotropic drugs. Physicians should take a more active role in the process of indication and monitoring of psychopharmaceuticals. Discontinuation of psychotropic drugs and the use of non-pharmacological alternatives are important bottlenecks in nursing homes. Education and training, updated practice guidelines, appropriate research, professionalization and management elements can, in a complex interaction, change this situation for the better.914.
Il-Chan Oh A.-L. Anderberg J. Schönenberger A. A. Anderberg 《Plant Systematics and Evolution》2008,271(3-4):177-197
Summary We investigated seed morphology in 34 species of the genus Lysimachia and in 14 species and two subspecies of six additional genera (Anagallis, Ardisiandra, Asterolinon, Glaux, Pelletiera, Trientalis), which have been shown to be closely related to, or are placed within Lysimachia in previous molecular studies. We studied seed shape, seed coat structure, and seed coat surface patterns. Three major types
of seed shape were identified: (1) sectoroid, (2) polyhedral, and (3) coarsely rugose with concave hilar area. In addition,
seeds may be keeled or winged. The outer layer of the seed coat is either sponge-like and adhering only loosely to the inner
seed coat or it is thin and tightly adhering to the underlying tissue. Seed surface patterns can be divided into six main
types: (1) reticulate, (2) tuberculate, (3) vesiculose, (4) colliculate, (5) undulate, or (6) poroid-alveolate. Seed surface
patterns are mostly congruent with molecular phylogenetic relationships. A reticulate surface pattern is diagnostic of, e.g.
Lysimachia subgenera Palladia and Hawaiian Lysimachiopsis. Mapping seed characters onto a recent phylogenetic tree, reveals that they provide potentially synapomorphic character states
for various subclades of Lysimachia. Salient examples include a rugose seed shape, which turns out to be synapomorphic for the clade comprising the genus Pelletiera plus Asterolinon linum-stellatum and a sponge-like outer seed coat layer, which characterizes a clade with Lysimachia vulgaris, L. thyrsiflora, and L. terrestris, with an analogue that apparently evolved in parallel in Trientalis europaea. We also discuss possible habitat factors that may have favored the independent evolution of particular seed types such as
winged seeds in various lineages. 相似文献
915.
Renaud Jolivet Felix Schürmann Thomas K. Berger Richard Naud Wulfram Gerstner Arnd Roth 《Biological cybernetics》2008,99(4-5):417-426
As large-scale, detailed network modeling projects are flourishing in the field of computational neuroscience, it is more and more important to design single neuron models that not only capture qualitative features of real neurons but are quantitatively accurate in silico representations of those. Recent years have seen substantial effort being put in the development of algorithms for the systematic evaluation and optimization of neuron models with respect to electrophysiological data. It is however difficult to compare these methods because of the lack of appropriate benchmark tests. Here, we describe one such effort of providing the community with a standardized set of tests to quantify the performances of single neuron models. Our effort takes the form of a yearly challenge similar to the ones which have been present in the machine learning community for some time. This paper gives an account of the first two challenges which took place in 2007 and 2008 and discusses future directions. The results of the competition suggest that best performance on data obtained from single or double electrode current or conductance injection is achieved by models that combine features of standard leaky integrate-and-fire models with a second variable reflecting adaptation, refractoriness, or a dynamic threshold. 相似文献
916.
917.
Frequent genes in rare diseases: panel‐based next generation sequencing to disclose causal mutations in hereditary neuropathies 下载免费PDF全文
Maike F. Dohrn Nicola Glöckle Lejla Mulahasanovic Corina Heller Julia Mohr Christine Bauer Erik Riesch Andrea Becker Florian Battke Konstanze Hörtnagel Thorsten Hornemann Saranya Suriyanarayanan Markus Blankenburg Jörg B. Schulz Kristl G. Claeys Burkhard Gess Istvan Katona Andreas Ferbert Debora Vittore Alexander Grimm Stefan Wolking Ludger Schöls Holger Lerche G. Christoph Korenke Dirk Fischer Bertold Schrank Urania Kotzaeridou Gerhard Kurlemann Bianca Dräger Anja Schirmacher Peter Young Beate Schlotter‐Weigel Saskia Biskup 《Journal of neurochemistry》2017,143(5):507-522
918.
919.
Plant responses to abiotic stresses: heavy metal-induced oxidative stress and protection by mycorrhization 总被引:32,自引:0,他引:32
The aim of this review is to assess the mode of action and role of antioxidants as protection from heavy metal stress in roots, mycorrhizal fungi and mycorrhizae. Based on their chemical and physical properties three different molecular mechanisms of heavy metal toxicity can be distinguished: (a) production of reactive oxygen species by autoxidation and Fenton reaction; this reaction is typical for transition metals such as iron or copper, (b) blocking of essential functional groups in biomolecules, this reaction has mainly been reported for non-redox-reactive heavy metals such as cadmium and mercury, (c) displacement of essential metal ions from biomolecules; the latter reaction occurs with different kinds of heavy metals. Transition metals cause oxidative injury in plant tissue, but a literature survey did not provide evidence that this stress could be alleviated by increased levels of antioxidative systems. The reason may be that transition metals initiate hydroxyl radical production, which can not be controlled by antioxidants. Exposure of plants to non-redox reactive metals also resulted in oxidative stress as indicated by lipid peroxidation, H(2)O(2) accumulation, and an oxidative burst. Cadmium and some other metals caused a transient depletion of GSH and an inhibition of antioxidative enzymes, especially of glutathione reductase. Assessment of antioxidative capacities by metabolic modelling suggested that the reported diminution of antioxidants was sufficient to cause H(2)O(2) accumulation. The depletion of GSH is apparently a critical step in cadmium sensitivity since plants with improved capacities for GSH synthesis displayed higher Cd tolerance. Available data suggest that cadmium, when not detoxified rapidly enough, may trigger, via the disturbance of the redox control of the cell, a sequence of reactions leading to growth inhibition, stimulation of secondary metabolism, lignification, and finally cell death. This view is in contrast to the idea that cadmium results in unspecific necrosis. Plants in certain mycorrhizal associations are less sensitive to cadmium stress than non-mycorrhizal plants. Data about antioxidative systems in mycorrhizal fungi in pure culture and in symbiosis are scarce. The present results indicate that mycorrhization stimulated the phenolic defence system in the Paxillus-Pinus mycorrhizal symbiosis. Cadmium-induced changes in mycorrhizal roots were absent or smaller than those in non-mycorrhizal roots. These observations suggest that although changes in rhizospheric conditions were perceived by the root part of the symbiosis, the typical Cd-induced stress responses of phenolics were buffered. It is not known whether mycorrhization protected roots from Cd-induced injury by preventing access of cadmium to sensitive extra- or intracellular sites, or by excreted or intrinsic metal-chelators, or by other defence systems. It is possible that mycorrhizal fungi provide protection via GSH since higher concentrations of this thiol were found in pure cultures of the fungi than in bare roots. The development of stress-tolerant plant-mycorrhizal associations may be a promising new strategy for phytoremediation and soil amelioration measures. 相似文献
920.
Summary Cell recovery by means of continuous flotation of the Hansenula polymorpha cultivation medium without additives was investigated as a function of the cultivation conditions as well as of the flotation equipment construction and flotation operational parameters. The cell enrichment and separation is improved at high liquid residence times, high aeration rates, small bubble sizes, increasing height of the aerated column, and diameter of the foam column. Increasing cell age and cultivation with nitrogen limitation reduce the cell separation.Symbols CP
cell mass concentration in medium g·l–1
- CR
cell mass concentration in residue g·l–1
- CS
cell mass concentration in foam liquid g·l–1
-
V
equilibrium foam volume cm3
- V
gas flow rate through the aerated liquid column cm3·s–1
- VF
feed rate to the flotation column ml/min
-
1
V
S/V foaminess s
-
mean liquid residence time in the column s 相似文献