首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
3.
In a survey of adverse drug reactions in wards of two Belfast hospitals for 52 weeks in 1965–6, 2·9% of 1,268 patients seen were admitted to hospital because of adverse reactions to drugs taken for therapeutic reasons and 2·1% were admitted because of self-poisoning. Patients admitted because of adverse drug reactions were older than those admitted because of self-poisoning and stayed in hospital longer. Among the drugs which caused the adverse reactions were digitalis preparations, antibiotics, corticosteroids, anticoagulants, analgesics, and tranquillizers. Hypersensitivity and side-effect types of reactions were the most common. Barbiturates were the most frequently used drugs in suicidal attempts.  相似文献   

4.
Among the drugs that are used to incapacitate victims such as kids or elderly for sedation or for criminal gain such as sexual offences or robberies, glibenclamide, an antidiabetic was never mentioned. To document the interest of hair testing in such forensic situations, we have developed an original method to test for glibenclamide. A 30-year-old man was admitted to the Emergency Unit for coma and seizures after a party with some members of his family. Blood glucose was 0.40 g/l. A hair specimen was collected several weeks after the event and divided into two segments of 2 cm. Twenty milligrams of each segment cut into small pieces were incubated overnight in a phosphate buffer (pH 5.5), in presence of gliclazide used as internal standard (IS). A liquid/liquid extraction was realized with a mixture of diethyl ether/methylene chloride, and hair extract was separated on a XTerra MS C18 column using a gradient of acetonitrile and formate buffer. Detection of glibenclamide was achieved using two transitions: m/z 493.9 to 168.9 and 493.9 to 368.8. Linearity was observed from 5 to 1000 pg/mg (r2 = 0.956) with a limit of quantification at 5 pg/mg and a clean-up recovery of about 61%. Within-batch precision and bias were 9.0 and 9.5%, respectively. Ion suppression tested on drug-free hair was about 50%. Glibenclamide tested positive in the two consecutive segments (root to 2 cm: 23 pg/mg and 2-4 cm: 31 pg/mg). These findings were in accordance with a repetitive exposure to the drug. The concentrations were compared with those obtained after a single and a daily dose administration. In the hair of a subject receiving a single 5mg dose and collected 4 weeks later, glibenclamide was detected in the proximal segment at 5 pg/mg. After a 20 mg/day dose, the hair concentration of a subject under glibenclamide therapy was 650 pg/mg.  相似文献   

5.
Several techniques have been developed to quantify the degree of embolism of the xylem using hydraulic conductance. Although there have been several improvements to these techniques, their reliability is still questionable and many technical pitfalls persist. We are proposing here a manometric approach to improve the accuracy of xylem cavitation measurement by the original air-injection technique which uses twigs exposed to pressurized air to cause cavitation. The measured parameter is air bubble production (P b) caused by xylem cavitation in birch (Betula pendula Roth) twigs from which the percent increase in bubble production is calculated to quantify xylem cavitation. Data produced by three different methods (bench-drying, air-injection, and manometric approach) are compared. Xylem vulnerability curves (VCs) constructed by the reference and reliable bench-drying technique and the manometric approach show similar sigmoid “S” shape, but a small anomaly appeared in the VC constructed by the original air-injection technique. The xylem pressure inducing 50% of embolism (P 50) was the same with the three techniques. Furthermore, there was a strong positive correlation between the estimators of xylem cavitation measured by the three different methods. For its reliability, precision and ease we recommend the manometric technique as an improved version of the original hydraulic air-injection method.  相似文献   

6.
A report on the 7th European Conference on Computational Biology (ECCB), Cagliari, Italy, 22-26 September 2008.  相似文献   

7.
8.
Campbell PJ 《Cell》2012,148(4):633-635
Telomere attrition unleashes genomic instability, promoting cancer development. Once established, however, the malignant clone often re-establishes genomic stability through overexpression of telomerase. In two papers, one in this issue of Cell and one in the subsequent issue, DePinho and colleagues explore the consequences of telomerase re-expression and its validity as a therapeutic target in mouse models of cancer.  相似文献   

9.
In neutral solutions polyamines are fully protonated, and hence are really polyammonium cations (PAC). Spermine, for example, carries four positive charges in a linear system, H3N+(CH2)3N+H2(CH2)4N+H2 (CH2)3N+H3. There is a very powerful coulombic interaction between aqueous DNA and such cations, thus the cations are attracted to the DNA over large distances, and once close to the DNA normally remain there for long periods. A key issue is; are the cations mobile, or do they remain at one preferred site for significant periods? The latter is the currently preferred concept, but NMR and EPR evidence will be presented in favour of the former. If the former is correct, then PACs may be able to act as good drug delivery systems. In its simple form the concept is that any drug that acts directly on DNA can be chemically bound to a PAC. Once in the cell, this PAC-drug complex (PAC-D) will be carried to DNA and will move very rapidly along the exposed strands until it recognises the site of action. This may be some special base sequence region, a damaged site, or the PAC-D unit may simply be present prior to potential damage, so that this can be repaired very rapidly. Some of our current studies on these systems are described.  相似文献   

10.
Attending to remember and remembering to attend   总被引:1,自引:0,他引:1  
Dudukovic NM  Wagner AD 《Neuron》2006,49(6):784-787
Attention and memory are intimately linked. Two functional imaging studies in this issue of Neuron provide novel evidence for this powerful, reciprocal relationship. Turk-Browne and colleagues report that attention simultaneously facilitates the formation of both implicit and explicit memories, while Summerfield and colleagues demonstrate that memory for the past can guide the allocation of attention in the present. Together, these elegant studies reveal bidirectional interactions between attention and memory.  相似文献   

11.
《Trends in microbiology》2023,31(3):222-224
The distinct risk factors to deadly infections by Aspergillus fumigatus (Af) in intensive care unit (ICU) patients are well known; however, so far, the mechanistic link between these predisposing conditions has been unknown. Sarden et al. recently unraveled a shared B1a lymphocyte–natural antibody–neutrophil defense pathway to Af, opening new perspectives in diagnostics and therapeutics.  相似文献   

12.
This contribution stems from the personal experience of the author regarding how he became acquainted with embryology and how he finally entered the field of developmental biology. It reports his feelings as a student of the Histology and Embryology course as it was taught in the late 1970s, and his present efforts in teaching developmental biology to university students. In the Developmental Biology course at Pisa University today, students are taught the tissue, molecular and genetic mechanisms that regulate development of several model systems. Drosophila is introduced at the beginning, because of the great knowledge that it has brought to the unraveling of the molecular aspects of development and because it allows several basic concepts to be introduced, and vertebrate systems follow. Other topics include the classic experiments on amphibian systems, which are explained in the light of recent molecular advances, as well as the genetically more versatile vertebrate systems such as the mouse.  相似文献   

13.
14.
15.
David Woods 《CMAJ》1984,131(2):95-96
  相似文献   

16.
No abstract available.  相似文献   

17.
18.
19.
Understanding plant response to wind is complicated as this factor entails not only mechanical stress, but also affects leaf microclimate. In a recent study, we found that plant responses to mechanical stress (MS) may be different and even in the opposite direction to those of wind. MS-treated Plantago major plants produced thinner more elongated leaves while those in wind did the opposite. The latter can be associated with the drying effect of wind as is further supported by data on petiole anatomy presented here. These results indicate that plant responses to wind will depend on the extent of water stress. It should also be recognized that the responses to wind may differ between different parts of a plant and between plant species. Physiological research on wind responses should thus focus on the signal sensing and transduction of both the mechanical and drought signals associated with wind, and consider both plant size and architecture.Key words: biomechanics, leaf anatomy, phenotypic plasticity, plant architecture, signal transduction thigmomorphogenesis, windWind is one of the most ubiquitous environmental stresses, and can strongly affect development, growth and reproductive yield in terrestrial plants.13 In spite of more than two centuries of research,4 plant responses to wind and their underlying mechanisms remain poorly understood. This is because plant responses to mechanical movement themselves are complicated and also because wind entails not only mechanical effects, but also changes in leaf gas and heat exchange.57 Much research on wind has focused primarily on its mechanical effect. Notably, several studies that determine plant responses to mechanical treatments such as flexing, implicitly extrapolate their results to wind effects.810 Our recent study11 showed that this may lead to errors as responses to wind and mechanical stimuli (in our case brushing) can be different and even in the opposite direction. In this paper, we first separately discuss plant responses to mechanical stimuli, and other wind-associated effects, and then discuss future challenges for the understanding of plant responses to wind.It is often believed that responses to mechanical stress (thigmomorphogenesis) entail the production of thicker and stronger plant structures that resist larger forces. This may be true for continuous unidirectional forces such as gravity, however for variable external forces (such as wind loading or periodic flooding) avoiding such mechanical stress by flexible and easily reconfigurable structures can be an alternative strategy.1214 How plants adapt or acclimate to such variable external forces depends on the intensity and frequency of stress and also on plant structures. Reduced height growth is the most common response to mechanical stimuli.15,16 This is partly because such short stature increases the ability of plants to both resist forces (e.g., real-locating biomass for radial growth rather than elongation growth), and because small plants experience smaller drag forces (Fig. 1). Some plant species show a resistance strategy in response to mechanical stress by increasing stem thickness1,10 and tissue strength.7 But other species show an avoidance strategy by a reduction in stem or petiole thickness and flexural rigidity in response to MS.11,1518 These different strategies might be associated with plant size and structure. Stems of larger plants such as trees and tall herbs are restricted in the ability to bend as they carry heavy loads7,10,19 (Fig. 1). Conversely short plants are less restricted in this respect and may also be prone to trampling for which stress-avoidance would be the only viable strategy.18,20 Systematic understanding of these various responses to mechanical stress remains to be achieved.Open in a separate windowFigure 1A graphical representation of how wind effects can be considered to entail both a drying and a mechanical effect. Adaptation or acclimation to the latter can be through a force resistance strategy or a force avoidance strategy, the benefit of which may depend on the size and architecture of plants as well as the location of a given structure within a plant.Wind often enhances water stress by reducing leaf boundary layers and reduces plant temperature by transpiration cooling. The latter effect may be minor,11 but the former could significantly affect plant development. Anten et al. (2010) compared phenotypic traits and growth of Plantago major that was grown under mechanical stimuli by brushing (MS) and wind in the factorial design. Both MS and wind treatments reduced growth and influenced allocation in a similar manner. MS plants, however, had more slender petioles and narrower leaf blades while wind exposed plants exhibited the opposite response having shorter and relatively thicker petioles and more round-shaped leaf blades. MS plants appeared to exhibit stress avoidance strategy while such responses could be compensated or overridden by water stress in wind exposure.11 A further analysis of leaf petiole anatomy (Fig. 2) supports this view. The vascular fraction in the petiole cross-section was increased by wind but not by MS, suggesting that higher water transport was required under wind. Our results suggest that drying effect of wind can at least to some extent override its mechanical effect.Open in a separate windowFigure 2Representative images of petiole cross-sections of Plantago major grown in 45 days in continuous wind and/or mechanical stimuli (A–D). Petiole cross-section area (E) and vascular bundle fraction in the cross-section of petiole (F). mean + SD (n = 12) are shown. Significance levels of ANOVA; ***p < 0.001, **p < 0.01, *p < 0.05, ns p > 0.05.Physiological knowledge on plant mechanoreception and signal transduction has been greatly increased during the last decades. Plants sense mechanical stimuli through membrane strain with stretch activated channels21 and/or through some linker molecules connecting the cell wall, plasma membrane and cytoskeleton.4,22,23 This leads to a ubiquitous increase in intracellular Ca2+ concentration. The increased Ca2+ concentration is sensed by touch induced genes (TCHs),24,25 which activates downstream transduction machineries including a range of signaling molecules and phytohormones, consequently altering physiological and developmental processes.26 Extending this knowledge to understand plant phenotypic responses to wind however remains a challenge. As responses to wind have been found to differ among parts of a plant (e.g., terminal vs. basal stem) and also across species, physiological studies should be extended to the whole-plant as integrated system rather than focusing on specific tissue level. Furthermore to understand the general mechanism across species, it is required to study different species from different environmental conditions. Advances in bioinformatics, molecular and physiological research will facilitate cross-disciplinary studies to disentangle the complicated responses of plants to wind.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号