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1.
在麻醉的32只猫记录了电刺激颌下腺神经支引起的上涎核平均场电位和单位放电。逆行电刺激颌下腺神经支引起的上涎核平均场电位分布在同侧脑干背面闩部头端5.5—8mm处,与过去的组织学结果大致符合。用微电极在上涎核记录了68个对刺激颌下腺神经支有反应的单位,其中33个单位作了碰撞试验。有9个单位符合逆向反应标准,它们是真正的颌下腺节前神经元,逆行反应的潜伏期为14.4±2.5ms,其轴突传导速度为2.9±0.1m/s。其他不符合逆向反应标准的单位,对刺激颌下腺神经支仍能发生反应,估计多为中间神经元。在一部分单位观察了电刺激舌神经或味觉刺激舌引起的反应。根据这些观察对上涎核内存在复杂神经元回路的可能性作了讨论。 相似文献
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Leonardus W. J. E. Beurskens Lieske H. Schrijver Dick Tibboel Mark F. Wildhagen Maarten F. C. M. Knapen Jan Lindemans Jeanne de Vries Régine P. M. Steegers‐Theunissen 《Birth defects research. Part A, Clinical and molecular teratology》2013,97(1):60-66
BACKGROUND
Vitamin A has been related to the etiology of congenital diaphragmatic hernia (CDH). We performed a case‐control study to investigate whether maternal dietary vitamin A intake is related to CDH in the offspring.METHODS
Thirty‐one pregnancies diagnosed with CDH and 46 control pregnancies were included during the study. After CDH diagnosis and inclusion of controls by risk set sampling, maternal vitamin A intake was investigated with a food frequency questionnaire. Serum retinol and retinol‐binding protein were determined. Univariable and multivariable logistic regression models were used to calculate risk estimates with adjustment for potential confounders.RESULTS
We found no significant differences in the overall nutrient and vitamin A intake between case and control mothers. After stratification in body mass index (BMI) categories, case mothers with normal weight showed a lower energy adjusted vitamin A intake (685 vs. 843 μg retinol activity equivalents [RAEs] / day; p = 0.04) and a slightly lower serum retinol (1.58 vs. 1.67 μmol/L; p = 0.08) than control mothers. Vitamin A intake <800 μg retinol activity equivalents (recommended daily intake) in normal weight mothers was associated with a significantly increased CDH risk (odds ratio [OR], 7.2; 95% confidence interval [CI], 1.5–34.4; p = 0.01). Associations were not significantly different in underweight and overweight mothers.CONCLUSIONS
In normal‐weight mothers, dietary vitamin A intake during pregnancy below the recommended daily intake is significantly associated with an increased risk of a child with CDH. This finding supports the retinoid hypothesis in human CDH, but warrants further investigation in larger study populations. Birth Defects Research (Part A), 2013. © 2013 Wiley Periodicals, Inc. 相似文献5.
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Background
The incidence and prevalence of diabetes are increasing all over the world. Complications of diabetes constitute a burden for the individuals and the whole society. 相似文献7.
Background
When a drug is applied on the skin surface, the concentration of the drug accumulated in the skin and the amount of the drug eliminated into the blood vessel depend on the value of a parameter, r. The values of r depend on the amount of diffusion and the normalized skin-capillary clearence. It is defined as the ratio of the steady-state drug concentration at the skin-capillary boundary to that at the skin-surface in one-dimensional models. The present paper studies the effect of the parameter values, when the region of contact of the skin with the drug, is a line segment on the skin surface. 相似文献8.
Lander Baeten Margot Vanhellemont Pieter De Frenne An De Schrijver Martin Hermy Kris Verheyen 《Oecologia》2010,163(4):1021-1032
The differential ability of forest herbs to colonize secondary forests on former agricultural land is generally attributed
to different rates of dispersal. After propagule arrival, however, establishing individuals still have to cope with abiotic
soil legacies from former agricultural land use. We focused on the plastic responses of forest herbs to increased phosphorus
availability, as phosphorus is commonly found to be persistently bioavailable in post-agricultural forest soils. In a pot
experiment performed under field conditions, we applied three P levels to four forest herbs with contrasting colonization
capacities: Anemone nemorosa, Primula elatior, Circaea lutetiana and Geum urbanum. To test interactions with light availability, half of the replicas were covered with shade cloths. After two growing seasons,
we measured aboveground P uptake as well as vegetative and regenerative performance. We hypothesized that fast-colonizing
species respond the most opportunistically to increased P availability, and that a low light availability can mask the effects
of P on performance. All species showed a significant increase in P uptake in the aboveground biomass. The addition of P had
a positive effect on the vegetative performances of two of the species, although this was unrelated to their colonization
capacities. The regenerative performance was affected by light availability (not by P addition) and was related to the species’
phenology. Forest herbs can obviously benefit from the increased availability of P in post-agricultural forests, but not all
species respond in the same way. Such differential patterns of plasticity may be important in community dynamics, as they
affect the interactions among species. 相似文献
9.
De Schrijver A Geudens G Augusto L Staelens J Mertens J Wuyts K Gielis L Verheyen K 《Oecologia》2007,153(3):663-674
Converting deciduous forests to coniferous plantations and vice versa causes environmental changes, but till now insight into
the overall effect is lacking. This review, based on 38 case studies, aims to find out how coniferous and deciduous forests
differ in terms of throughfall (+stemflow) deposition and seepage flux to groundwater. From the comparison of coniferous and
deciduous stands at comparable sites, it can be inferred that deciduous forests receive less N and S via throughfall (+stemflow)
deposition on the forest floor. In regions with relatively low open field deposition of atmospheric N (<10 kg N ha−1 year−1), lower NH4+ mean throughfall (+stemflow) deposition was, however, reported under conifers compared to deciduous forest, while in regions
with high atmospheric N pollution (>10 kg N ha−1 year−1), the opposite could be concluded. The higher the open field deposition of NH4+, the bigger the difference between the coniferous and deciduous throughfall (+stemflow) deposition. Furthermore, it can be
concluded that canopy exchange of K+, Ca2+ and Mg2+ is on average higher in deciduous stands. The significantly higher stand deposition flux of N and S in coniferous forests
is reflected in a higher soil seepage flux of NO3−, SO42−, K+, Ca2+, Mg2+ and Al(III). Considering a subset of papers for which all necessary data were available, a close relationship between throughfall
(+stemflow) deposition and seepage was found for N, irrespective of the forest type, while this was not the case for S. This
review shows that the higher input flux of N and S in coniferous forests clearly involves a higher seepage of NO3− and SO42− and accompanying cations K+, Ca2+, Mg2+ and Al(III) into the groundwater, making this forest type more vulnerable to acidification and eutrophication compared to
the deciduous forest type. 相似文献
10.
De Frenne P Kolb A Graae BJ Decocq G Baltora S De Schrijver A Brunet J Chabrerie O Cousins SA Dhondt R Diekmann M Gruwez R Heinken T Hermy M Liira J Saguez R Shevtsova A Baskin CC Verheyen K 《Plant biology (Stuttgart, Germany)》2011,13(3):493-501
The nutrient concentration in seeds determines many aspects of potential success of the sexual reproductive phase of plants, including the seed predation probability, efficiency of seed dispersal and seedling performance. Despite considerable research interest in latitudinal gradients of foliar nutrients, a similar gradient for seeds remains unexplored. We investigated a potential latitudinal gradient in seed nutrient concentrations within the widespread European understorey forest herb Anemone nemorosa L. We sampled seeds of A. nemorosa in 15 populations along a 1900-km long latitudinal gradient at three to seven seed collection dates post-anthesis and investigated the relative effects of growing degree-hours >5 °C, soil characteristics and latitude on seed nutrient concentrations. Seed nitrogen, nitrogen:phosphorus ratio and calcium concentration decreased towards northern latitudes, while carbon:nitrogen ratios increased. When taking differences in growing degree-hours and measured soil characteristics into account and only considering the most mature seeds, the latitudinal decline remained particularly significant for seed nitrogen concentration. We argue that the decline in seed nitrogen concentration can be attributed to northward decreasing seed provisioning due to lower soil nitrogen availability or greater investment in clonal reproduction. This pattern may have large implications for the reproductive performance of this forest herb as the degree of seed provisioning ultimately co-determines seedling survival and reproductive success. 相似文献