644 research outputs found

    Root foraging and avoidance in hyperaccumulator and excluder plants: a rhizotron experiment

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    Aims: Metal hyperaccumulation is a rare phenomenon described for an increasing number of plant taxa. In this study we investigated the root growth responses of the well-known nickel, zinc, cadmium hyperaccumulator Noccaea caerulescens and of the metal tolerant (non-accumulator) Stellaria media, in order to observe root foraging vs avoidance responses to nickel. Methods: To allow for observations of root growth and foraging preferences, two accessions of Noccaea caerulescens and two accessions of Stellaria media orginating from high nickel and low nickel habitats were grown in rhizotrons with localized nickel enrichment. Results: The root density in the control and nickel-enriched soil areas in the rhizotrons with different N. caerulescens accessions had distinct responses: moderate nickel avoidance was recorded for the non-nickel accession, while a clear foraging response was observed in N. caerulescens from the nickel accession. In contrast, nickel rooting avoidance was observed for both S. media accessions and was more pronounced in the non-nickel accession. Conclusions: This study shows that N. caerulescens originating from different accessions responded differently to soil nickel enrichment, with the nickel accession of N. caerulescens actively foraging for nickel, suggesting a physiological adaptation and demand for this metal. In contrast, a clear nickel avoidance response by a metal tolerant species, S. media, was observed in this study, a phenomenon which has not been previously described; this suggests that root avoidance responses might play a role in the adaptation of metal tolerant species to Ni-rich soils

    Ultramafic geoecology of South and Southeast Asia

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    Globally, ultramafic outcrops are renowned for hosting foras with high levels of endemism, including plants with specialised adaptations such as nickel or manganese hyperaccumulation. Soils derived from ultramafic regoliths are generally nutrient-deficient, have major cation imbalances, and have concomitant high concentrations of potentially phytotoxic trace elements, especially nickel. The South and Southeast Asian region has the largest surface occurrences of ultramafic regoliths in the world, but the geoecology of these outcrops is still poorly studied despite severe conservation threats. Due to the paucity of systematic plant collections in many areas and the lack of georeferenced herbarium records and databased information, it is not possible to determine the distribution of species, levels of endemism, and the species most threatened. However, site-specific studies provide insights to the ultramafic geoecology of several locations in South and Southeast Asia. The geoecology of tropical ultramafic regions differs substantially from those in temperate regions in that the vegetation at lower elevations is generally tall forest with relatively low levels of endemism. On ultramafic mountaintops, where the combined forces of edaphic and climatic factors intersect, obligate ultramafic species and hyperendemics often occur. Forest clearing, agricultural development, mining, and climate change-related stressors have contributed to rapid and unprecedented loss of ultramafic-associated habitats in the region. The geoecology of the large ultramafic outcrops of Indonesia’s Sulawesi, Obi and Halmahera, and many other smaller outcrops in South and Southeast Asia, remains largely unexplored, and should be prioritised for study and conservation

    Recent advances in developing tropical nickel agromining

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    Hyperaccumulator plants can be utilized as ‘metal crops’ in agromining operations. This emerging technology produces ‘bio-ore’ by growing ‘metal crops’ on sub-economic ore materials, such as natural ultramafic soils. In a typical application plant material is periodically harvested, followed by air-drying and incineration to produce the bio-ore intermediate. The bio-ore is of very high grade (>15 wt. % nickel), and of high purity, and may be processed into a number of different products (including nickel metal, nickel-based catalysts and pure nickel salts). Current research efforts from our team focus on Mediterranean climate field trials (Albania, Spain) and tropical climate field trials (Malaysia, Indonesia). Field-scale demonstrations are required to provide evidence of real-life performance and of economic viability. If the trials are successful, agromining may in the near future support local livelihoods with income opportunities as an alternative type of agriculture: to farm nickel

    CFTR Expression Analysis in Human Nasal Epithelial Cells by Flow Cytometry

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    Rationale: Unbiased approaches that study aberrant protein expression in primary airway epithelial cells at single cell level may profoundly improve diagnosis and understanding of airway diseases. We here present a flow cytometric procedure to study CFTR expression in human primary nasal epithelial cells from patients with Cystic Fibrosis (CF). Our novel approach may be important in monitoring of therapeutic responses, and better understanding of CF disease at the molecular level. Objectives: Validation of a panel of CFTR-directed monoclonal antibodies for flow cytometry and CFTR expression analysis in nasal epithelial cells from healthy controls and CF patients. Methods: We analyzed CFTR expression in primary nasal epithelial cells at single cell level using flow cytometry. Nasal cells were stained for pan-Cytokeratin, E cadherin, and CD45 (to discriminate epithelial cells and leukocytes) in combination with intracellular staining of CFTR. Healthy individuals and CF patients were compared. Measurements and Main Results: We observed various cellular populations present in nasal brushings that expressed CFTR protein at different levels. Our data indicated that CF patients homozygous for F508del express varying levels of CFTR protein in nasal epithelial cells, although at a lower level than healthy controls. Conclusion: CFTR protein is expressed in CF patients harboring F508del mutations but at lower levels than in healthy controls. Multicolor flow cytometry of nasal cells is a relatively simple procedure to analyze the composition of cellula

    The 3^3He(e, e′'d)p Reaction in qω\omega-constant Kinematics

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    The cross section for the 3^3He(e, e′'d)p reaction has been measured as a function of the missing momentum pmp_m in qω\omega -constant kinematics at beam energies of 370 and 576 MeV for values of the three-momentum transfer qq of 412, 504 and 604 \mevc. The L(+TT), T and LT structure functions have been separated for qq = 412 and 504 \mevc. The data are compared to three-body Faddeev calculations, including meson-exchange currents (MEC), and to calculations based on a covariant diagrammatic expansion. The influence of final-state interactions and meson-exchange currents is discussed. The pmp_m-dependence of the data is reasonably well described by all calculations. However, the most advanced Faddeev calculations, which employ the AV18 nucleon-nucleon interaction and include MEC, overestimate the measured cross sections, especially the longitudinal part, and at the larger values of qq. The diagrammatic approach gives a fair description of the cross section, but under(over)estimates the longitudinal (transverse) structure function.Comment: 17 pages, 7 figure

    Encouraging survival rates in patients with acute myocardial infarction treated with an intra-aortic balloon pump

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    Objective To evaluate a 30-day and long-term outcome of patients with acute myocardial infarction (AMI) treated with intra-aortic balloon pump (IABP) counterpulsation and to identify predictors of a 30-day and long-term all-cause mortality. Methods Retrospective cohort study of 437 consecutive AMI patients treated with IABP between January 1990 and June 2004. A Cox proportional hazards model was used to identify predictors of a 30-day and long-term all-cause mortality. Results Mean age of the study population was 61±11 years, 80% of the patients were male, and 68% had cardiogenic shock. Survival until IABP removal after successful haemodynamic stabilisation was 78% (n=341). Cumulative 30-day survival was 68%. Median follow-up was 2.9 years (range, 6 months to 15 years). In patients who survived until IABP removal, cumulative 1-, 5-, and 10-year survival was 75%

    Measurements of interrupter resistance: reference values for children 3-13 yrs of age

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    The interrupter technique is a convenient and sensitive technique for studying airway function in subjects who cannot actively participate in (forced) ventilatory function tests. Reference values for preschool children exist but are lacking for children >7 yrs. Reference values were obtained for expiratory interrupter resistance (R(int,e)) in 208 healthy Dutch Caucasian children 3-13 yrs of age. A curvilinear relationship between R(int,e) and height was observed, similar to published airways resistance data measured by plethysmography. No significant differences in cross-sectional trend or level of R(int,e) were observed according to sex. It was found that Z-scores could be used to express individual R(int,e) values and to describe intra- and interindividual differences based on the reference equation: 10logR(int,e)=0.645-0.00668x standing height (cm) kPa x L(-1) x s(-1) and residual SD (0.093 kPa x L(-1) x s(-1)). Expiratory interrupter resistance provides a tool for clinical and epidemiological assessment of airway function in a large age range

    Infarct-related chronic total coronary occlusion and the risk of ventricular tachyarrhythmic events in out-of-hospital cardiac arrest survivors

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    Introduction: Chronic total coronary occlusion (CTO) has been identified as a risk factor for ventricular arrhythmias, especially a CTO in an infarct-related artery (IRA). This study aimed to evaluate the effect of an IRA-CTO on the occurrence of ventricular tachyarrhythmic events (VTEs) in out-of-hospital cardiac arrest survivors without ST-segment elevation. Methods: We conducted a post hoc analysis of the COACT trial, a multicentre randomised controlled trial. Patients were included when they survived index hospitalisation after cardiac arrest and demonstrated coronary artery disease on coronary angiography. The primary endpoint was the occurrence of a VTE, defined as appropriate implantable cardioverter-defibrillator (ICD) therapy, sustained ventricular tachyarrhythmia or sudden cardiac death. Results: A total of 163 patients from ten centres were included. Unrevascularised IRA-CTO in a main vessel was present in 43 patients (26%). Overall, 61% of the study population received an ICD for secondary prevention. During a follow-up of 1 year, 12 patients (7.4%) experienced at least one VTE. The cumulative incidence rate of VTEs was higher in patients with an IRA-CTO compared to patients without an IRA-CTO (17.4% vs 5.6%, log-rank p = 0.03). However, multivariable analysis only identified left ventricular ejection fraction < 35% as an independent factor associated with VTEs (adjusted hazard ratio 8.7, 95% confidence interval 2.2–35.4). A subanalysis focusing on CTO, with or without an infarct in the CTO territory, did not change the results. Conclusion: In out-of-hospital cardiac arrest survivors with coronary artery disease without ST-segment elevation, an IRA-CTO was not an independent factor associated with VTEs in the 1st year after the index event

    Introduction of a breast cancer care programme including ultra short hospital stay in 4 early adopter centres: framework for an implementation study

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    <p>Abstract</p> <p>Background</p> <p>Whereas ultra-short stay (day care or 24 hour hospitalisation) following breast cancer surgery was introduced in the US and Canada in the 1990s, it is not yet common practice in Europe. This paper describes the design of the MaDO study, which involves the implementation of ultra short stay admission for patients after breast cancer surgery, and evaluates whether the targets of the implementation strategy are reached. The ultra short stay programme and the applied implementation strategy will be evaluated from the economic perspective.</p> <p>Methods/design</p> <p>The MaDO study is a pre-post-controlled multi-centre study, that is performed in four hospitals in the Netherlands. It includes a pre and post measuring period of six months each with six months of implementation in between in at least 40 patients per hospital per measurement period.</p> <p>Primary outcome measure is the percentage of patients treated in ultra short stay. Secondary endpoints are the percentage of patients treated according to protocol, degree of involvement of home care nursing, quality of care from the patient's perspective, cost-effectiveness of the ultra short stay programme and cost-effectiveness of the implementation strategy. Quality of care will be measured by the QUOTE-breast cancer instrument, cost-effectiveness of the ultra short stay programme will be measured by means of the EuroQol (administered at four time-points) and a cost book for patients. Cost-effectiveness analysis will be performed from a societal perspective. Cost-effectiveness of the implementation strategy will be measured by determination of the costs of implementation activities.</p> <p>Discussion</p> <p>This study will reveal barriers and facilitators for implementation of the ultra short stay programme. Moreover, the results of the study will provide information about the cost-effectiveness of the ultra short stay programme and the implementation strategy.</p> <p>Trial registration</p> <p>Current Controlled Trials ISRCTN77253391.</p
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