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Berlin Brandenburg

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  • 1
    In: Journal of Cardiovascular Magnetic Resonance, 2011, Vol.13(Suppl 1), p.P254-P254
    Description: Gadolinium-based MRI examinations have become essential for the treatment of patients with atrial fibrillation (AF). Gadolinium-based contrast agents can trigger nephrogenic systemic fibrosis (NSF).
    Keywords: Poster Presentation
    ISSN: 1097-6647
    E-ISSN: 1532-429X
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  • 2
    In: Econometric Theory, 2011, Vol.27(3), pp.609-638
    Description: In this paper we are concerned with analyzing the behavior of a semiparametric estimator that corrects for endogeneity in a nonparametric regression by assuming mean independence of residuals from instruments only. Because it is common in many applications, we focus on the case where endogenous regressors and additional instruments are jointly normal, conditional on exogenous regressors. This leads to a severely ill-posed inverse problem. In this setup, we show first how to test for conditional normality. More importantly, we then establish how to exploit this knowledge when constructing an estimator, and we derive the large sample behavior of such an estimator. In addition, in a Monte Carlo experiment we analyze its finite sample behavior. Our application comes from consumer demand. We obtain new and interesting findings that highlight both the advantages and the difficulties of an approach that leads to ill-posed inverse problems. Finally, we discuss the somewhat problematic relationship between endogenous nonparametric regression models and the recently emphasized issue of unobserved heterogeneity in structural models.
    Keywords: Estimating Techniques ; Regression Analysis ; Monte Carlo Simulation ; Econometrics ; Mathematical Models ; Studies ; Experimental/Theoretical ; Management Science/Operations Research ; Economic Theory;
    ISSN: 0266-4666
    E-ISSN: 1469-4360
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  • 3
    Language: English
    In: Science of the Total Environment, 01 September 2018, Vol.634, pp.305-315
    Description: The leaching of P from the upper 20 cm of forest topsoils influences nutrient (re-)cycling and the redistribution of available phosphate and organic P forms. However, the effective leaching of colloids and associated P forms from forest topsoils was so far sparsely investigated. We demonstrated through irrigation experiments with undisturbed mesocosm soil columns, that significant proportions of P leached from acidic forest topsoils were associated with natural colloids. These colloids had a maximum size of 400 nm. By means of Field-flow fractionation the leached soil colloids could be separated into three size fractions. The size and composition was comparable to colloids present in acidic forest streams known from literature. The composition of leached colloids of the three size classes was dominated by organic carbon. Furthermore, these colloids contained large concentrations of P which amounted between 12 and 91% of the totally leached P depending on the type of the forest soil. The fraction of other elements leached with colloids ranged between 1% and 25% (Fe: 1–25%; C : 3–17%; Al: 〈4%; Si, Ca, Mn: all 〈2%). The proportion of colloid–associated P decreased with increasing total P leaching. Leaching of total and colloid-associated P from the forest surface soil did not increase with increasing bulk soil P concentrations and were also not related to tree species. The present study highlighted that colloid-facilitated P leaching can be of higher relevance for the P leaching from forest surface soils than dissolved P and should not be neglected in soil water flux studies.
    Keywords: Colloids ; Forest Soil ; Leaching ; Mesocosm ; Nanoparticles ; Phosphorus ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 4
    Language: English
    In: Journal of Plant Nutrition and Soil Science, August 2016, Vol.179(4), pp.443-453
    Description: Phosphorus (P) is essential for sustainable forest growth, yet the impact of anthropogenic impacts on P leaching losses from forest soils is hardly known. We conducted an irrigation experiment with 128 mesocosms from three forest sites representing a gradient of resin extractable P of the A‐horizon. On each site we selected a and a managed subsite. We simulated ambient rain (AR), anthropogenic nitrogen input (NI) of 100 kg (ha · a) and forest liming (FL) with a dolomite input of 0.3 Mg (ha · a). Soil solution was extracted from the organic layer, 10 cm depth and 20 cm depth of the mesocosms, and analyzed for molybdate reactive phosphorus (MRP) and molybdate unreactive phosphorus (MUP). Additionally, we separated colloids from the soil solution using Asymmetric Field Flow Fractionation for assessing the colloidal fraction of total element concentrations. NI increased MRP and MUP concentrations for all plots with one exception, while FL decreased MRP and MUP with the exception of another plot. While the irrigation treatments had little impact on the P‐richest site, MRP and MUP concentrations changed strongly at the poorer sites. The colloidal fraction of P in the soil solution equaled 38–47% of the total P load. Nitrogen input and liming also affected the Fe, Al, Ca, and Corg contents of the colloidal fraction.
    Keywords: Phosphorus ; Mesocosm ; Random Forest Modelling ; Molybdate ; Soil Colloids
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 5
    In: Journal of Cardiovascular Magnetic Resonance, 2012, Vol.14(Suppl 1), p.P202-P202
    Description: Cardiac MRI (cMRI) has become an effective and feasible tool to identify the anatomy of the left atrium and the pulmonary veins (PV) prior to pulmonary vein ablation (PVI) in patients with atrial fibrillation (AF). It is still difficult to predict the potential success of a PVI.
    Keywords: Poster Presentation
    ISSN: 1097-6647
    E-ISSN: 1532-429X
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  • 6
    Language: English
    In: Climatic Change, 2013, Vol.116(3), pp.827-850
    Description: The impact of climate-induced discharge change on fish habitats, based on 1951–2008 time series, was investigated within the crystalline catchment of the Grosse Mühl River in Northern Austria. A significant trend change of air temperature, based on Mann–Whitney statistical testing, was recorded for spring 1989 ( P  = 98.9 %) and summer 1990 ( P  = 99.9 %). This led to a pronounced increase in summer low flow periods. Hydrodynamic-numerical (one-dimensional/two-dimensional) modelling was applied to simulate the changing habitat characteristics due to decreasing discharge in relation to various morphological patterns (riffle-pool/plane-bed reaches). Using bathymetric data, which were sampled on cross sectional measurements, we clearly determined that plane-bed reaches (featureless bed forms) are sensitive to climate-related, reduced discharge, whereas riffle-pool reaches continued to exhibit suitable physical fish habitats even under extreme low-flow conditions. The impact of the decreased summer discharge on instream habitats was strong for subadult and adult grayling which have been used as target fish species. In situ measurements in microhabitats (velocity/depth) revealed habitat suitabilities. These values were taken as biotic input for habitat evaluation on the micro scale. The findings clearly show that river morphology is a decisive parameter in terms of habitat preservation and restoration in the context of the future impacts of climate change (decreased discharge).
    Keywords: Bedforms -- Analysis ; Hydrology -- Analysis ; Environmental Management -- Analysis ; Global Temperature Changes -- Analysis ; Ecosystems -- Analysis;
    ISSN: 0165-0009
    E-ISSN: 1573-1480
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  • 7
    Language: English
    In: Journal of Cardiovascular Magnetic Resonance, 01 January 2013, Vol.15(Suppl 1), p.P207
    Description: The presens of myocardial scar tissue as a potential arrhythmogen substrate may influence the treatment of patients with coronary artery disease (CAD). Delayed enhancement MRI (DE-MRI) allows accurate detection and visualization of myocardial scar tissue. We thought to detect myocardial scar tissue in patients with CAD and preserved left ventricular (LV) function without regional wall motion abnormalities (RWMA) in transthoracic echocardiography (TTE) using DE-MRI.
    Keywords: Medicine
    ISSN: 1097-6647
    E-ISSN: 1532-429X
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  • 8
    In: Journal of Cardiovascular Electrophysiology, October 2011, Vol.22(10), pp.1092-1098
    Description: Renal Dysfunction and Atrial Fibrillation Recurrence. Background: No previous study has assessed the role of renal impairment in predicting the long‐term risk of atrial fibrillation recurrence after cardioversion Methods: One hundred and fifty‐nine consecutive patients with persistent atrial fibrillation undergoing successful cardioversion were enrolled. Renal function was assessed based on the estimated glomerular filtration rate (eGFR) at baseline and during follow‐up. Patients were prospectively followed up for eGFR and recurrence of atrial fibrillation up to 1 year. Results: Patients were divided into 4 groups based upon their eGFR (group 1 〉90 mL/min: 33 patients, group 2: 60–90 mL/min: 55 patients, group 3: 30–59 mL/min: 53 patients, group 4: 〈30 mL/min: 18 patients). Overall, 101 out of 159 (64%) patients experienced atrial fibrillation recurrence within 1 year follow‐up. Atrial fibrillation recurrence was independently associated with the level of reduction of eGFR at baseline (eGFR 〈 30 mL/min: hazard ratio [HR] 6.82, P 〈 0.001; eGFR 30–59 mL/min: HR 3.31, P = 0.01; eGFR 60–90 mL/min: HR 2.10, P = 0.13; eGFR 〉 90 mL/min reference group). In patients with maintained sinus rhythm after 12‐month follow‐up eGFR was increased (8.46 ± 9.49 mL/min [range −7 to 43]), whereas patients with atrial fibrillation recurrence showed a decrease in eGFR over time (−5.75 ± 9.4 [range −32 to 25], P 〈 0.001).  
    Keywords: Atrial Fibrillation ; Cardioversion ; Kidney Dysfunction ; Anticoagulation ; Antiarrhythmic Drugs
    ISSN: 1045-3873
    E-ISSN: 1540-8167
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  • 9
    Language: English
    In: American Journal of Kidney Diseases, 2012, Vol.59(2), pp.186-195
    Description: Vascular calcification is a predictor of cardiovascular morbidity and mortality. Hemodialysis patients experience severe vascular calcifications. Matrix Gla protein (MGP) is a central calcification inhibitor of the arterial wall; its activity depends on vitamin K–dependent γ-glutamate carboxylation. Uncarboxylated MGP, formed as a result of vitamin K deficiency, is associated with cardiovascular disease. Recent studies suggest poor vitamin K status in hemodialysis patients. We therefore aimed to investigate whether daily vitamin K supplementation improves the bioactivity of vitamin K–dependent proteins in hemodialysis patients, assessed by circulating dephosphorylated-uncarboxylated MGP, uncarboxylated osteocalcin, and uncarboxylated prothrombin (PIVKA-II [protein induced by vitamin K absence II]). Interventional randomized non–placebo-controlled trial with 3 parallel groups. 53 long-term hemodialysis patients in stable conditions, 18 years or older. 50 healthy age-matched individuals served as controls. Menaquinone-7 (vitamin K ) treatment at 45, 135, or 360 μg/d for 6 weeks. Plasma levels of dephosphorylated-uncarboxylated MGP, uncarboxylated osteocalcin, and PIVKA-II. Plasma levels were assessed using enzyme-linked immunosorbent assays. At baseline, hemodialysis patients had 4.5-fold higher dephosphorylated-uncarboxylated MGP and 8.4-fold higher uncarboxylated osteocalcin levels compared with controls. PIVKA-II levels were elevated in 49 hemodialysis patients. Vitamin K supplementation induced a dose- and time-dependent decrease in circulating dephosphorylated-uncarboxylated MGP, uncarboxylated osteocalcin, and PIVKA-II levels. Response rates in the reduction in dephosphorylated-uncarboxylated MGP levels were 77% and 93% in the groups receiving 135 μg and 360 μg of menaquinone-7, respectively. Small sample size. This study confirms that most hemodialysis patients have a functional vitamin K deficiency. More importantly, it is the first study showing that inactive MGP levels can be decreased markedly by daily vitamin K supplementation. Our study provides the rationale for intervention trials aimed at decreasing vascular calcification in hemodialysis patients by vitamin K supplementation.
    Keywords: Dialysis ; Vascular Calcification ; Vitamin K ; Matrix Gla Protein (Mgp) ; Osteocalcin ; Protein Induced By Vitamin K Absence II (Pivka-II) ; Medicine
    ISSN: 0272-6386
    E-ISSN: 1523-6838
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  • 10
    Language: English
    In: American journal of kidney diseases : the official journal of the National Kidney Foundation, February 2012, Vol.59(2), pp.186-95
    Description: Vascular calcification is a predictor of cardiovascular morbidity and mortality. Hemodialysis patients experience severe vascular calcifications. Matrix Gla protein (MGP) is a central calcification inhibitor of the arterial wall; its activity depends on vitamin K-dependent γ-glutamate carboxylation. Uncarboxylated MGP, formed as a result of vitamin K deficiency, is associated with cardiovascular disease. Recent studies suggest poor vitamin K status in hemodialysis patients. We therefore aimed to investigate whether daily vitamin K supplementation improves the bioactivity of vitamin K-dependent proteins in hemodialysis patients, assessed by circulating dephosphorylated-uncarboxylated MGP, uncarboxylated osteocalcin, and uncarboxylated prothrombin (PIVKA-II [protein induced by vitamin K absence II]). Interventional randomized non-placebo-controlled trial with 3 parallel groups. 53 long-term hemodialysis patients in stable conditions, 18 years or older. 50 healthy age-matched individuals served as controls. Menaquinone-7 (vitamin K(2)) treatment at 45, 135, or 360 μg/d for 6 weeks. Plasma levels of dephosphorylated-uncarboxylated MGP, uncarboxylated osteocalcin, and PIVKA-II. Plasma levels were assessed using enzyme-linked immunosorbent assays. At baseline, hemodialysis patients had 4.5-fold higher dephosphorylated-uncarboxylated MGP and 8.4-fold higher uncarboxylated osteocalcin levels compared with controls. PIVKA-II levels were elevated in 49 hemodialysis patients. Vitamin K(2) supplementation induced a dose- and time-dependent decrease in circulating dephosphorylated-uncarboxylated MGP, uncarboxylated osteocalcin, and PIVKA-II levels. Response rates in the reduction in dephosphorylated-uncarboxylated MGP levels were 77% and 93% in the groups receiving 135 μg and 360 μg of menaquinone-7, respectively. Small sample size. This study confirms that most hemodialysis patients have a functional vitamin K deficiency. More importantly, it is the first study showing that inactive MGP levels can be decreased markedly by daily vitamin K(2) supplementation. Our study provides the rationale for intervention trials aimed at decreasing vascular calcification in hemodialysis patients by vitamin K supplementation.
    Keywords: Dietary Supplements ; Renal Dialysis ; Kidney Diseases -- Therapy ; Vitamin K 2 -- Administration & Dosage ; Vitamin K Deficiency -- Drug Therapy
    ISSN: 02726386
    E-ISSN: 1523-6838
    Source: MEDLINE/PubMed (U.S. National Library of Medicine)
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