953 resultados para Nucleophilic attack
Resumo:
The hypothesis that constitutive and inducible plant resistance against herbivores should trade-off because they use the same resources and impose costs to plant fitness has been postulated for a long time. Negative correlations between modes of deployment of resistance and defences have been observed across and within species in common garden experiments. It was therefore tested whether that pattern of resistance across genotypes follows a similar variation in patterns of gene expression and chemical defence production. Using the genetically tractable model Arabidopsis thaliana and different modes of induction, including the generalist herbivore Spodoptera littoralis, the specialist herbivore Pieris brassicae, and jasmonate application, constitutive and inducibility of resistance was measured across seven A. thaliana accessions that were previously selected based on constitutive levels of defence gene expression. According to theory, it was found that modes of resistance traded-off among accessions, particularly against S. littoralis, in which accessions investing in high constitutive resistance did not increase it substantially after attack and vice-versa. Accordingly, the average expression of eight genes involved in glucosinolate production negatively predicted larval growth across the seven accessions. Glucosinolate production and genes related to defence induction on healthy and herbivore-damaged plants were measured next. Surprisingly, only a partial correlation between glucosinolate production, gene expression, and the herbivore resistance results was found. These results suggest that the defence outcome of plants against herbivores goes beyond individual molecules or genes but stands on a complex network of interactions.
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New evidences published this year are susceptible to change the management of several medical emergencies. Combined antiplatelet therapy might be beneficial for the management of TIA or minor stroke and rapid blood pressure lowering might improve the outcome in patients with intracerebral hemorrhage. A restrictive red cell transfusion strategy is indicated in case of upper digestive bleeding and coagulation factors concentrates are superior to fresh frozen plasma for urgent warfarin reversal. Prolonged systemic steroid therapy is not warranted in case of acute exacerbation of BPCO, and iterative physiotherapy is not beneficial after acute whiplash. Finally, family presence during cardiopulmonary resuscitation may reduce post-traumatic stress disorder among relatives.
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The occurrence of Helicoverpa armigera (Hübner, 1808) was first reported in citrus orchard in the state of São Paulo (SP). High infestation levels of H. armigera were observed in October 2012, in the city of Botucatu, SP. The larvae was fed of all parts of the plants. The injuries on the leaves caused drastic reduction in the leaf area and the fruits attack occurred from an early stage of development to the ripe fruit. Thus, the first occurrence of H. armigera in this citrus culture adds to the list of hosts of this pest, and is of great importance, because it confirms H. armigera potential dispersion and polyphagia.
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Työn tarkoituksena on tutkia pinon ylikirjoitukseen perustuvien hyökkäysten toimintaa ja osoittaa kokeellisesti nykyisten suojaustekniikoiden olevan riittämättömiä. Tutkimus suoritetaan testaamalla miten valitut tietoturvatuotteet toimivat eri testitilanteissa. Testatut tuotteet ovat Openwall, PaX, Libsafe 2.0 ja Immunix 6.2. Testaus suoritetaan pääasiassa RedHat 7.0 ympäristössä testiohjelman avulla. Testeissä mitataan sekä tuotteiden kyky havaita hyökkäyksiä että niiden nopeusvaikutukset. Myös erityyppisten hyökkäysten ja niitä vastaan kehitettyjen metodien toimintaperiaatteet esitellään seikkaperäisesti ja havainnollistetaan yksinkertaistetuilla esimerkeillä. Esitellyt tekniikat sisältävät puskurin ylivuodot, laittomat muotoiluparametrit, loppumerkittömät merkkijonot ja taulukoiden ylivuodot. Testit osoittavat, etteivät valitut tuotteet estä kaikkia hyökkäyksiä, joten lopuksi perehdytään myös vahinkojen minimointiin onnistuneiden hyökkäysten varalta.
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Under what conditions will a bystander intervene to try to stop a violent attack by one person on another? It is generally believed that the greater the size of the crowd of bystanders, the less the chance that any of them will intervene. A complementary model is that social identity is critical as an explanatory variable. For example, when the bystander shares common social identity with the victim the probability of intervention is enhanced, other things being equal. However, it is generally not possible to study such hypotheses experimentally for practical and ethical reasons. Here we show that an experiment that depicts a violent incident at life-size in immersive virtual reality lends support to the social identity explanation. 40 male supporters of Arsenal Football Club in England were recruited for a two-factor between-groups experiment: the victim was either an Arsenal supporter or not (in-group/out-group), and looked towards the participant for help or not during the confrontation. The response variables were the numbers of verbal and physical interventions by the participant during the violent argument. The number of physical interventions had a significantly greater mean in the ingroup condition compared to the out-group. The more that participants perceived that the Victim was looking to them for help the greater the number of interventions in the in-group but not in the out-group. These results are supported by standard statistical analysis of variance, with more detailed findings obtained by a symbolic regression procedure based on genetic programming. Verbal interventions made during their experience, and analysis of post-experiment interview data suggest that in-group members were more prone to confrontational intervention compared to the out-group who were more prone to make statements to try to diffuse the situation.
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Soybean (Glycine max. L.) nodular senescence results in the dismantling of the peribacteroid membrane (PBM) and in an increase of soybean isocitrate lyase (ICL; EC 4.1.3.1) and malate synthase (MS; EC 4.1.3.2) mRNA and protein levels. This suggests that in senescing soybean nodular cells, the specific glyoxylate cycle enzyme activities might be induced to reallocate carbon obtained from the PBM degradation. In order to evaluate as well the carbon metabolism of the nitrogen-fixing Bradyrhizobium japonicum endosymbiotic bacteroids during nodular senescence, their glyoxylate cycle activities were also investigated. To this end, partial DNA sequences were isolated from their icl and ms genes, but the corresponding mRNAs were not detected in the microorganisms. It was also observed that the bacteroid ICL and MS activities were negligible during nodular senescence. This suggests that glyoxylate cycle activities are not reinitiated in the bacteroids under these physiological conditions. In case the microorganisms nevertheless feed on the PBM degradation products, this might occur via the citric acid cycle exclusively.
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BACKGROUND AND PURPOSE: The best time for administering anticoagulation therapy in acute cardioembolic stroke remains unclear. This prospective cohort study of patients with acute stroke and atrial fibrillation, evaluated (1) the risk of recurrent ischemic event and severe bleeding; (2) the risk factors for recurrence and bleeding; and (3) the risks of recurrence and bleeding associated with anticoagulant therapy and its starting time after the acute stroke. METHODS: The primary outcome of this multicenter study was the composite of stroke, transient ischemic attack, symptomatic systemic embolism, symptomatic cerebral bleeding and major extracranial bleeding within 90 days from acute stroke. RESULTS: Of the 1029 patients enrolled, 123 had 128 events (12.6%): 77 (7.6%) ischemic stroke or transient ischemic attack or systemic embolism, 37 (3.6%) symptomatic cerebral bleeding, and 14 (1.4%) major extracranial bleeding. At 90 days, 50% of the patients were either deceased or disabled (modified Rankin score ≥3), and 10.9% were deceased. High CHA2DS2-VASc score, high National Institutes of Health Stroke Scale, large ischemic lesion and type of anticoagulant were predictive factors for primary study outcome. At adjusted Cox regression analysis, initiating anticoagulants 4 to 14 days from stroke onset was associated with a significant reduction in primary study outcome, compared with initiating treatment before 4 or after 14 days: hazard ratio 0.53 (95% confidence interval 0.30-0.93). About 7% of the patients treated with oral anticoagulants alone had an outcome event compared with 16.8% and 12.3% of the patients treated with low molecular weight heparins alone or followed by oral anticoagulants, respectively (P=0.003). CONCLUSIONS: Acute stroke in atrial fibrillation patients is associated with high rates of ischemic recurrence and major bleeding at 90 days. This study has observed that high CHA2DS2-VASc score, high National Institutes of Health Stroke Scale, large ischemic lesions, and type of anticoagulant administered each independently led to a greater risk of recurrence and bleedings. Also, data showed that the best time for initiating anticoagulation treatment for secondary stroke prevention is 4 to 14 days from stroke onset. Moreover, patients treated with oral anticoagulants alone had better outcomes compared with patients treated with low molecular weight heparins alone or before oral anticoagulants.
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This thesis studies techniques used for detection of distributed denial of service attacks which during last decade became one of the most serious network security threats. To evaluate different detection algorithms and further improve them we need to test their performance under conditions as close to real-life situations as possible. Currently the only feasible solution for large-scale tests is the simulated environment. The thesis describes implementation of recursive non-parametric CUSUM algorithm for detection of distributed denial of service attacks in ns-2 network simulator – a standard de-facto for network simulation.
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BACKGROUND AND PURPOSE: Thromboxane prostaglandin receptors have been implicated to be involved in the atherosclerotic process. We assessed whether Terutroban, a thromboxane prostaglandin receptor antagonist, affects the progression of atherosclerosis, as measured by common carotid intima-media thickness and carotid plaques. METHODS: A substudy was performed among 1141 participants of the aspirin-controlled Prevention of Cerebrovascular and Cardiovascular Events of Ischemic Origin with Terutroban in Patients with a History of Ischemic Stroke or Transient Ischemic Attack (PERFORM) trial. Common carotid intima-media thickness and carotid plaque occurrence was measured during a 3-year period. RESULTS: Baseline characteristics did not differ between Terutroban (n=592) and aspirin (n=549) treated patients and were similar as in the main study. Mean study and treatment duration were similar (28 and 25 months, respectively). In the Terutroban group, the annualized rate of change in common carotid intima-media thickness was 0.006 mm per year (95% confidence interval, -0.004 to 0.016) and -0.005 mm per year (95% confidence interval, -0.015 to 0.005) in the aspirin group. There was no statistically significant difference between the groups in the annualized rate of change of common carotid intima-media thickness (0.011 mm per year; 95% confidence interval, -0.003 to 0.025). At 12 months of follow-up, 66% of Terutroban patients had no emergent plaques, 31% had 1 to 2 emergent plaques, and 3% had ≥3 emergent plaques. In the aspirin group, the corresponding percentages were 64%, 32%, and 4%. Over time, there was no statistically significant difference in the number of emergent carotid plaques between treatment modalities (rate ratio, 0.91; 95% confidence interval, 0.77-1.07). CONCLUSIONS: Compared with aspirin, Terutroban did not beneficially affect progression of carotid atherosclerosis among well-treated patients with a history of ischemic stroke or transient ischemic attacks with an internal carotid stenosis <70%. CLINICAL TRIAL REGISTRATION URL: http://www.controlled-trials.com. Unique identifier: ISRCTN66157730.
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BACKGROUND AND PURPOSE: Medial temporal lobe abnormalities on DWI and functional imaging are occasionally observed in patients with transient global amnesia. We used CTP to study these patients during or briefly after resolution of their amnesic syndrome. MATERIALS AND METHODS: From 2002 onward, patients satisfying clinical criteria for transient global amnesia who underwent CTP were included. Patients with additional clinical features suggesting transient ischemic attack or stroke and those with an ischemic lesion on subsequent DWI were excluded. If deemed necessary by the clinician, DWI was performed within 10 days. RESULTS: Thirty patients with transient global amnesia underwent CTP at a median latency of 5.9 hours (interquartile range, 4.3-9.7 hours) after symptom onset. All findings, except for those in 1 patient, were normal, including those in the 14 patients with well-imaged hippocampi. In the patient with abnormal findings, CTP and PWI showed hypoperfusion in both lentiform nuclei extending into the insulae, with normalization on the repeat CTP 6 days later. In 10 patients, DWI was performed at a median latency of 2 days (interquartile range, 0-9 days). Of these, 2 showed punctate hippocampal lesions, often seen in transient global amnesia. In 2 patients excluded because of mildly atypical transient global amnesia and ischemic lesions on subsequent DWI, acute CTP findings were also normal. CONCLUSIONS: Patients with transient global amnesia had normal CTP findings in the acute phase with the exception of 1 patient with transient hypoperfusion in both basal ganglia. If imaging is performed for typical and atypical transient global amnesia, DWI should be the preferred method.
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Background: Cardiovascular disease (CVD), mainly heart attack and stroke, is the leading cause of premature mortality in low and middle income countries (LMICs). Identifying and managing individuals at high risk of CVD is an important strategy to prevent and control CVD, in addition to multisectoral population-based interventions to reduce CVD risk factors in the entire population. Methods: We describe key public health considerations in identifying and managing individuals at high risk of CVD in LMICs. Results: A main objective of any strategy to identify individuals at high CVD risk is to maximize the number of CVD events averted while minimizing the numbers of individuals needing treatment. Scores estimating the total risk of CVD (e.g. ten-year risk of fatal and non-fatal CVD) are available for LMICs, and are based on the main CVD risk factors (history of CVD, age, sex, tobacco use, blood pressure, blood cholesterol and diabetes status). Opportunistic screening of CVD risk factors enables identification of persons with high CVD risk, but this strategy can be widely applied in low resource settings only if cost effective interventions are used (e.g. the WHO Package of Essential NCD interventions for primary health care in low resource settings package) and if treatment (generally for years) can be sustained, including continued availability of affordable medications and funding mechanisms that allow people to purchase medications without impoverishing them (e.g. universal access to health care). This also emphasises the need to re-orient health systems in LMICs towards chronic diseases management.
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Technical developments have made it possible to analyze very low amounts of DNA. This has many advantages, but the drawback of this technological progress is that interpretation of the results becomes increasingly complex: the number of mixed DNA profiles increased relatively to single source DNA profiles and stochastic effects in the DNA profile, such as drop-in and drop-out, are more frequently observed. Moreover, the relevance of low template DNA material regarding the activities alleged is not as straightforward as it was a few years ago, when for example large quantities of blood were recovered. The possibility of secondary and tertiary transfer is now becoming an issue. The purpose of this research is twofold: first, to study the transfer of DNA from the handler and secondly, to observe if handlers would transfer DNA from persons closely connected to them. We chose to mimic cases where the offender would attack a person with a knife. As a first approach, we envisaged that the defense would not give an alternative explanation for the origin of the DNA. In our transfer experiments (4 donors, 16 experiments each, 64 traces), 3% of the traces were single DNA profiles. Most of the time, the DNA profile of the person handling the knife was present as the major profile: in 83% of the traces the major contributor profile corresponded to the stabber's DNA profile (in single stains and mixtures). Mixture with no clear major/minor fraction (12%) were observed. 5% of the traces were considered of insufficient quality (more than 3 contributors, presence of a few minor peaks). In that case, we considered that the stabber's DNA was absent. In our experiments, no traces allowed excluding the stabber, however it must be noted that precautions were taken to minimize background DNA as knives were cleaned before the experiments. DNA profiles of the stabber's colleagues were not observed. We hope that this study will allow for a better understanding of the transfer mechanism and of how to assess and describe results given activity level propositions. In this preliminary research, we have focused on the transfer of DNA on the hand of the person. Besides, more research is needed to assign the probability of the results given an alternative activity proposed by the defense, for instance when the source of the DNA is not contested, but that the activities are.
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Cerebral energy dysfunction has emerged as an important determinant of prognosis following traumatic brain injury (TBI). A number of studies using cerebral microdialysis, positron emission tomography, and jugular bulb oximetry to explore cerebral metabolism in patients with TBI have demonstrated a critical decrease in the availability of the main energy substrate of brain cells (i.e., glucose). Energy dysfunction induces adaptations of cerebral metabolism that include the utilization of alternative energy resources that the brain constitutively has, such as lactate. Two decades of experimental and human investigations have convincingly shown that lactate stands as a major actor of cerebral metabolism. Glutamate-induced activation of glycolysis stimulates lactate production from glucose in astrocytes, with subsequent lactate transfer to neurons (astrocyte-neuron lactate shuttle). Lactate is not only used as an extra energy substrate but also acts as a signaling molecule and regulator of systemic and brain glucose use in the cerebral circulation. In animal models of brain injury (e.g., TBI, stroke), supplementation with exogenous lactate exerts significant neuroprotection. Here, we summarize the main clinical studies showing the pivotal role of lactate and cerebral lactate metabolism after TBI. We also review pilot interventional studies that examined exogenous lactate supplementation in patients with TBI and found hypertonic lactate infusions had several beneficial properties on the injured brain, including decrease of brain edema, improvement of neuroenergetics via a "cerebral glucose-sparing effect," and increase of cerebral blood flow. Hypertonic lactate represents a promising area of therapeutic investigation; however, larger studies are needed to further examine mechanisms of action and impact on outcome.
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This article aims to explain how newspapers commented on the movie Good Night, and Good Luck before its release. The media coverage anticipated George Clooney's film as a partisan attack launched against George W. Bush's policy since 9/11. Clooney advocates another reading: the historic confrontation between journalist Edward Murrow and Senator Joseph McCarty permits to reflect on the crucial role that the media play for democracy. Such reflection tries to prevent the dividing of the public sphere into antagonistic camps opposing "friends" to "foes," a division that undermines the possibility of a true pluralism. Our socio-semiotic analysis will focus on the critical work accomplished by the media, and on the way that work determines the collective meaning of a cultural object. Simultaneously, we will discuss the necessary conditions for pluralism in a public sphere.
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STUDY OBJECTIVES: Narcolepsy with cataplexy is tightly associated with the HLA class II allele DQB1*06:02. Evidence indicates a complex contribution of HLA class II genes to narcolepsy susceptibility with a recent independent association with HLA-DPB1. The cause of narcolepsy is supposed be an autoimmune attack against hypocretin-producing neurons. Despite the strong association with HLA class II, there is no evidence for CD4+ T-cell-mediated mechanism in narcolepsy. Since neurons express class I and not class II molecules, the final effector immune cells involved might include class I-restricted CD8+ T-cells. METHODS: HLA class I (A, B, and C) and II (DQB1) genotypes were analyzed in 944 European narcolepsy with cataplexy patients and in 4,043 control subjects matched by country of origin. All patients and controls were DQB1*06:02 positive and class I associations were conditioned on DQB1 alleles. RESULTS: HLA-A*11:01 (OR = 1.49 [1.18-1.87] P = 7.0*10(-4)), C*04:01 (OR = 1.34 [1.10-1.63] P = 3.23*10(-3)), and B*35:01 (OR = 1.46 [1.13-1.89] P = 3.64*10(-3)) were associated with susceptibility to narcolepsy. Analysis of polymorphic class I amino-acids revealed even stronger associations with key antigen-binding residues HLA-A-Tyr(9) (OR = 1.32 [1.15-1.52] P = 6.95*10(-5)) and HLA-C-Ser(11) (OR = 1.34 [1.15-1.57] P = 2.43*10(-4)). CONCLUSIONS: Our findings provide a genetic basis for increased susceptibility to infectious factors or an immune cytotoxic mechanism in narcolepsy, potentially targeting hypocretin neurons.