Elms (Ulmus spp.) have long been appreciated for their environmental tolerance, landscape and ornamental value, and the quality of their wood. Although elm trees are extremely hardy against abiotic stresses such as wind and pollution, they are susceptible to attacks of biotic stressors. Over 100 phytopathogens and invertebrate pests are associated with elms: fungi, bacteria and insects like beetles and moths, and to a lesser extent aphids, mites, viruses and nematodes. While the biology of the pathogen and insect vector of the Dutch elm disease has been intensively studied, less attention has been paid so far to the defence mechanisms of elms to other biotic stressors. This review highlights knowledge of direct and indirect elm defences against biotic stressors focusing on morphological, chemical and gene regulation aspects. First, we report how morphological defence mechanisms via barrier formation and vessel occlusion prevent colonisation and spread of wood- and bark-inhabiting fungi and bacteria. Second, we outline how secondary metabolites such as terpenoids (volatile terpenoids, mansonones and triterpenoids) and phenolics (lignans, coumarins, flavonoids) in leaves and bark are involved in constitutive and induced chemical defence mechanisms of elms. Third, we address knowledge on how the molecular regulation of elm defence is orchestrated through the interaction of a huge variety of stress- and defence-related genes. We conclude by pointing to the gaps of knowledge on the chemical and molecular mechanisms of elm defence against pest insects and diseases. An in-depth understanding of defence mechanisms of elms will support the development of sustainable integrated management of pests and diseases attacking elms. 相似文献
Zinc (Zn) is an essential micronutrient for plants and animals. Unfortunately, deficiency of Zn in humans has increased on a global scale. The main reason of this micronutrient deficiency is dietary intakes of food with low Zn levels. Adoption of biofortification approaches would result in Zn enrichment of target tissue to a considerable extent. However, there is a basic need to understand Zn absorption mechanisms in plants prior to exploitation of such practical approaches. Zn absorption is a complex physiological trait which is mainly governed by Zn transporters and metal chelators of plant system. Plant growth stage, edaphic factors, season etc. also influence Zn efficiency of particular species. Molecular studies in Zn hyperaccumulators have already demonstrated the participation of specific Zn transporters, vacuolar sequestration and detoxification mechanisms in maintenance of Zn homeostasis. These have been described in detail in present review and provide opportunities for utilization in biofortification programmes. However, issues such as lesser bioavailability of Zn in target organ, uptake of toxic divalent cations (Cd, Ni, Pb, As etc.) along with Zn, sink activity and dilution in Zn concentration in response to sink number etc. in biofortified crops need further investigation. In order to design novel strategy in biofortification programmes, future researches should focus on physiological performance and yield penalties in concerned crop, metabolic load in term of organic acid production and crosstalk of Zn with other mineral nutrients under low and high Zn conditions. 相似文献
Marine seaweeds represent an abundant source of natural products and may harbour valuable chemicals. The brown seaweed Sargassum muticum is an invasive species to the coasts of the British Isles, mainland Europe and North America. Attempts at its eradication and control have generally not been successful, although time-consuming and costly. Commercial exploration of this biomass for food, fuel and pharmaceutical products could encourage its harvesting and control. Though S. muticum might be unsuitable as a source of biofuel due to high ash and water content, this rapidly growing macroalga has a naturally high content of antioxidants, carotenoids and phenols, including the well-known anti-cancer compound fucoxanthin, making this species a potential source of a range of pharmaceutically relevant materials. 相似文献
Heart failure with preserved ejection fraction (HFpEF) is common and its management remains difficult. B-type natriuretic peptide (BNP) levels are used to diagnose heart failure, and as an entry criterion for inclusion into trials. We investigated a population of HFpEF patients who had been randomised into a study based on clinical parameters, and compared those with low BNP levels to those with elevated BNP levels.
Methods
We examined patients who had been enrolled in the Coordinating study evaluating Outcomes of Advising and Counselling in Heart Failure (COACH), with preserved left ventricular ejection fraction (LVEF ≥ 40 %), and compared those with low BNP (< 100 pg/ml; n = 30) to those with elevated BNP (≥ 100 pg/ml; n = 127). Baseline characteristics, comorbidities, biomarkers, quality of life, and outcome parameters (hospitalisations and death) were compared between the groups. To validate our findings, we repeated all analyses for NT-proBNP (< 300 pg/ml and ≥ 300 pg/ml).
Results
Patients were similar with regard to most clinical characteristics (including age, sex, and LVEF), biomarkers, and comorbidities. In contrast, patients with a low BNP had higher body mass index levels (31 kg/m2 vs. 27 kg/m2; p < 0.01) and lower cardiac troponin I (9 pg/ml vs. 15 pg/ml; p = 0.02). In addition, these patients were less frequently prescribed diuretics and beta-blockers. No differences in quality of life, heart failure related symptoms and the primary and secondary outcomes were observed between these groups. These observations were confirmed for NT-proBNP.
Conclusion
Among the patients with clinically diagnosed HFpEF, those with low BNP are strikingly similar to those with elevated BNP levels, except for BMI, which was significantly higher in these patients.
Electronic supplementary material
The online version of this article (doi:10.1007/s12471-016-0816-8) contains supplementary material, which is available to authorized users. 相似文献
Advanced treatment of pulmonary arterial hypertension (PAH) in congenital heart disease (CHD) is increasingly applied worldwide following the—mainly Western world based—international PAH-CHD guidelines. However, studies comparing clinical presentation and outcome after the initiation of PAH-specific treatment are lacking. We aimed to analyse this in a Singaporean and Dutch cohort of PAH-CHD patients.
Methods
Adult CHD patients starting PAH-specific therapy, enrolled in two nationwide registries, were analysed. Patients received phosphodiesterase-type-5 inhibitors, endothelin receptor antagonists, or a combination. Change in six-minute walk test (6MWT) during follow-up was analysed using linear mixed model analysis. Determinants for mortality were assessed using Cox proportional hazard analyses.
Results
A total of 74 patients, 45 Dutch (mean age 47?±?14 years) and 29 Singaporean (mean age 41?±?14 years) were analysed. Despite a lower 6MWT (312 versus 395 metres, p?=?0.01) and peak VO2 (35 versus 49?% of predicted, p?=?0.01) at baseline in Singaporean patients, the treatment effect was similar in the two populations. Age at initiation of therapy (per 5 year lower age, β?=?+?4.5, p?=?0.017) was the strongest predictor of improvement in exercise capacity, corrected for ethnicity, baseline 6MWT, sex and CHD defect.
Conclusions
Patients from Singapore had a worse clinical performance at baseline compared with the PAH-CHD patients from the Netherlands. No relation between ethnicity and improvement in 6MWT after PAH-specific therapy was found. Age at initiation of PAH-specific therapy was the strongest predictor of treatment efficacy and mortality, emphasising the need for early initiation of treatment in these patients.
The current outcome of out-of-hospital cardiac arrest (OHCA) patients in the Maastricht region was analysed with the prospect of implementing extracorporeal cardiopulmonary resuscitation (E-CPR).
Methods
A retrospective analysis of adult patients who were resuscitated for OHCA during a 24-month period was performed.
Results
195 patients (age 66 [57–75] years, 82 % male) were resuscitated for OHCA by the emergency medical services and survived to admission at the emergency department. Survival to hospital discharge was 46.2 %. Notable differences between non-survivors and survivors were observed and included: age (70 [58–79] years) vs. (63 [55–72] years, p = 0.01), chronic heart failure (18 vs. 7 %, p = 0.02), shockable rhythm (67 vs. 99 %, p < 0.01), and return of spontaneous circulation (ROSC) at departure from the site of the arrest (46 vs. 99 %, p < 0.01) and on arrival to the emergency department (43 vs. 98 %, p < 0.01), respectively. Acute coronary syndrome was diagnosed in 32 % of non-survivors vs. 59 % among survivors, p < 0.01. Therapeutic hypothermia was provided in non-survivors (20 %) vs. survivors (43 %), p < 0.01. Percutaneous coronary intervention (PCI) was performed in 14 % of non-survivors while 52 % of survivors received PCI (p < 0.01). No statistical significance was observed in terms of gender, witnessed arrest, bystander CPR, or automated external defibrillator deployed among the cohort. At hospital discharge, moderately severe neurological disability was present in six survivors.
Conclusion
These observations are compatible with the notion that a shockable rhythm, ROSC, and post-arrest care improve survival outcome. Potentially, initiating E-CPR in the resuscitation phase in patients with a shockable rhythm and no ROSC might serve as a bridge to definite treatment and improve survival outcome. 相似文献
The Central Texas endemic freshwater mussel, Quadrula mitchelli (Simpson in Dall, 1896), had been presumed extinct until relict populations were recently rediscovered. To help guide ongoing and future conservation efforts focused on Q. mitchelli we set out to resolve several uncertainties regarding its evolutionary history, specifically its unknown generic position and untested species boundaries. We designed a molecular matrix consisting of two loci (cytochrome c oxidase subunit I and internal transcribed spacer I) and 57 terminal taxa to test the generic position of Q. mitchelli using Bayesian inference and maximum likelihood phylogenetic reconstruction. We also employed two Bayesian species validation methods to test five a priori species models (i.e. hypotheses of species delimitation). Our study is the first to test the generic position of Q.mitchelli and we found robust support for its inclusion in the genus Fusconaia. Accordingly, we introduce the binomial, Fusconaia mitchelli comb. nov., to accurately represent the systematic position of the species. We resolved F. mitchelli individuals in two well supported and divergent clades that were generally distinguished as distinct species using Bayesian species validation methods, although alternative hypotheses of species delineation were also supported. Despite strong evidence of genetic isolation within F. mitchelli, we do not advocate for species-level status of the two clades as they are allopatrically distributed and no morphological, behavioral, or ecological characters are known to distinguish them. These results are discussed in the context of the systematics, distribution, and conservation of F. mitchelli. 相似文献
Aminopeptidase N (APN) is a zinc-dependent ectopeptidase involved in cell proliferation, secretion, invasion, and angiogenesis, and is widely recognized as an important cancer target. However, the mechanisms whereby ligands leave the active site of APN remain unknown. Investigating ligand dissociation processes is quite difficult, both in classical simulation methods and in experimental approaches. In this study, random acceleration molecular dynamics (RAMD) simulation was used to investigate the potential dissociation pathways of ligand from APN. The results revealed three pathways (channels A, B and C) for ligand release. Channel A, which matches the hypothetical channel region, was the most preferred region for bestatin to dissociate from the enzyme, and is probably the major channel for the inner bound ligand. In addition, two alternative channels (channels B and C) were shown to be possible pathways for ligand egression. Meanwhile, we identified key residues controlling the dynamic features of APN channels. Identification of the dissociation routes will provide further mechanistic insights into APN, which will benefit the development of more promising APN inhibitors.
