排序方式: 共有84条查询结果,搜索用时 15 毫秒
41.
Reina JA de Kinderen Danielle AJE Lambrechts Debby Postulart Alfons GH Kessels Jos GM Hendriksen Albert P Aldenkamp Marian HJM Majoie 《BMC neurology》2011,11(1):10
Background
Epilepsy is a neurological disorder, characterized by recurrent unprovoked seizures which have a high impact on the individual as well as on society as a whole. In addition to the economic burden, epilepsy imposes a substantial burden on the patients and their surroundings. Patients with uncontrolled epilepsy depend heavily on informal care and on health care professionals. About 30% of patients suffer from drug-resistant epilepsy. The ketogenic diet can be a treatment of last resort, especially for children. The beneficial effect of the ketogenic diet has been proven, but information is lacking about its cost-effectiveness. In the current study we will evaluate the (cost-) effectiveness of the ketogenic diet in children and adolescents with intractable epilepsy. 相似文献42.
Robert S. Fritz Bernadette M. Roche Steven J. Brunsfeld Colin M. Orians 《Oecologia》1996,108(1):121-129
We studied herbivory of two species of willows (Salix sericea and S. eriocephala) and their interspecific hybrids to test alternative hypotheses concerning the effects of hybridization on plant resistance. Individually marked plants were identified using morphological traits in the field and random amplified polymorphic DNA (RAPD) band analysis was used to verify the genetic status of many parental and hybrid plants. The desities of 12 herbivore species on plants in the field were compared between two parents and their F2-type hybrids. We found about equal support for the additive, dominance, and hybrid susceptibility hypotheses over 4 years. In one year, one species supported the hybrid resistance hypothesis. Guild membership was not a good predictor of similar responses of species to hybrid versus parental plants. There were marked differences in support for particular hypotheses among years for four herbivore species. This study demonstrates the diversity of responses of phytophages in response to interspecific hybridization, and indicates that year-to-year variation in relative resistance of hybrid plants can be important. 相似文献
43.
Sandplain heathlands are disturbance-dependent plant communities that occur infrequently in coastal areas of the northeastern United States. We hypothesize that salt spray plays a role in maintaining the composition of the heathland community by excluding salt-intolerant species close to the ocean. We examined the distributions of Solidago nemoralis, Myrica pensylvanica, Pinus rigida, and Quercus spp. in heathlands and conducted greenhouse studies to determine whether different levels of salt spray tolerance explain patterns found in the field. We found that common heathland forb and shrub species grow closer to the ocean than successional woody species. In greenhouse experiments, these species differ in their water status, necrosis, and growth responses to salt spray. The tree species P. rigida and Q. rubra are more susceptible to salt spray than the common heathland species M. pensylvanica. Our results suggest that salt spray may prevent tree species in heathlands from growing close to the ocean and therefore might be an important factor in maintaining the characteristic community composition of these dwarf shrublands in coastal habitats. 相似文献
44.
Schakowski F Buttgereit P Mazur M Märten A Schöttker B Gorschlüter M Schmidt-Wolf IG 《Genetic vaccines and therapy》2004,2(1):1-11
BACKGROUND: Tumor cells such as leukemia and lymphoma cells are possible targets for gene therapy. However, previously leukemia and lymphoma cells have been demonstrated to be resistant to most of non-viral gene transfer methods. METHODS: The aim of this study was to analyze various methods for transfection of primary leukemia cells and leukemia cell lines and to improve the efficiency of gene delivery. Here, we evaluated a novel electroporation based technique called nucleofection. This novel technique uses a combination of special electrical parameters and specific solutions to deliver the DNA directly to the cell nucleus under mild conditions. RESULTS: Using this technique for gene transfer up to 75% of primary cells derived from three acute myeloid leukemia (AML) patients and K562 cells were transfected with the green flourescent protein (GFP) reporter gene with low cytotoxicity. In addition, 49(+/- 9.7%) of HL60 leukemia cells showed expression of GFP. CONCLUSION: The non-viral transfection method described here may have an impact on the use of primary leukemia cells and leukemia cell lines in cancer gene therapy. 相似文献
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The age- and cytomegalovirus (CMV)-seropositivity-related changes in subsets and differentiation of circulating T cells were investigated in end-stage renal disease (ESRD) patients (n = 139) and age-matched healthy individuals. The results show that CMV-seropositivity is associated with expansion of both CD4+ and CD8+ memory T cells which is already observed in young healthy individuals. In addition, CMV-seropositive healthy individuals have a more differentiated memory T cell profile. Only CMV-seropositive healthy individuals showed an age-dependent decrease in CD4+ naïve T cells. The age-related decrease in the number of CD8+ naïve T cells was CMV-independent. In contrast, all ESRD patients showed a profound naïve T-cell lymphopenia at every decade. CMV-seropositivity aggravated the contraction of CD4+ naïve T cells and increased the number of differentiated CD4+ and CD8+ memory T cells. In conclusion, CMV-seropositivity markedly alters the homeostasis of circulating T cells in healthy individuals and aggravates the T cell dysregulation observed in ESRD patients. 相似文献
47.
Orians TM 《American journal of botany》2006,93(6):884-890
While carbon transport and partitioning is largely determined by phloem source-sink relationships, it may be constrained by vascular connections. Tomato (Lycopersicon esculentum) plants exhibit a high degree of sectoriality, with restricted movement of nutrients from particular roots to orthostichous leaves. In this experiment we investigated the manner in which sectoriality influences source-sink phloem partitioning from shoots to roots in tomatoes and whether the size of the sink (root) modifies the pattern of carbon movement outside sectored pathways. Using (13)C, we determined that shoot-to-root carbon transport in tomatoes is sectored even from upper leaves. Sink size also influenced carbon partitioning. Specifically, when a lateral root was grown in isolation (using a split-pot technique), it grew more and acquired significantly more (13)C from an orthostichous, exposed leaf than did any other single root. Vascular constraints were evident. (13)C accumulation in a large, isolated lateral root was very low when a leaf opposite the isolated lateral root was exposed. Thus sink size did not overcome vascular constraints. Because carbon assimilates are needed for nutrient acquisition and assimilation, these vascular constraints may affect the ability of sectored plants to utilize heterogeneously distributed soil resources. If so, future studies should compare species that differ in sectoriality to determine whether vascular constraints affect competitive hierarchies when soil resource availability is patchy. 相似文献
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A characteristic feature of the sperm P1 protamines of eutherian mammals is
the constant presence of six to nine cysteine residues per molecule. During
spermiogenesis these residues become oxidized to form a three-dimensional
network of disulfide bridges between, and within, protamine molecules in
the sperm chromatin. This covalent cross linking strongly stabilizes
eutherian sperm nuclei. In contrast, protamines sequenced from teleost
fish, birds, monotremes, and marsupials all lack cysteine residues and
their sperm nuclei, without the stabilizing cross links, are easily
decondensed in vitro. We have now found that one genus of tiny, shrewlike
dasyurid marsupials, the Planigales, possess P1 protamines containing five
to six cysteine residues. These residues appear to have evolved since the
divergence of Planigales from other members of the family Dasyuridae, such
as the marsupial mouse, Sminthopsis crassicaudata. We believe this
constitutes a case of convergent evolution in a subfamily of dasyurid
marsupials toward the cysteine-rich eutherian form of sperm protamine P1.
相似文献
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Nicole E. Soltis Sara Gomez Gary G. Leisk Patrick Sherwood Evan L. Preisser Pierluigi Bonello Colin M. Orians 《Annals of botany》2014,113(4):721-730