Vergleich verschiedener Klee-Gras-Mischungen anhand der Wurzel- und Sprossleistung

Zusammenfassung Ziel der Arbeit war es einen Beitrag zur Optimierung der Kleegras-Gemenge im Hinblick auf verbesserte Wurzelleistung, hohen Sprossertrag, höherer Artenvielfalt und Tiergesundheit zu liefern. Im einem Feldversuch (2007) wurde eine handelsübliche Kleegrasmischung (NF3) zwei selbst zusammengestellte Mischungen mit erhöhtem Leguminosen- und Kräuteranteil (FMB und GDM) bei unterschiedlichen Nutzungen (Schnitt und Mulch) gegenübergestellt. Sprossertrag, N-Entzug, symbiontisch fixierte N-Menge, Bestandeszusammensetzung und Wurzelparameter wurden gemessen. Die Bestandeszusammensetzung verschob sich in den Mulchvarianten zu Gunsten des Grasanteils. Einige Kräuter konnten sich während der gesamten Vegetation gut behaupten. Der Sprossertrag war unabhängig von den Mischungs- und Nutzungsvarianten. Die Menge an symbiontisch fixiertem Stickstoff lag in der NF3-Mischung bei jährlich 90 kg N ha-1, in der FMB bei 290 kg N ha-1 und in der GDM bei 340 kg N ha-1. Die GDM wies eine signifikant geringere Wurzellänge als FMB und NF3 auf, die mit dem geringen Grasanteil zu begründen ist. Die Wurzeltrockenmassen nahmen in der Reihenfolge NF3 < GDM < FMB signifikant zu. Eine gleichmäßigere Durchwurzelung aller Bodenschichten wurde in den Varianten FMB und GDM durch die Hinzunahme der tiefwurzelnden Arten erreich

In-situ comparison of the NOy instruments flown in MOZAIC and SPURT

Two aircraft instruments for the measurement of total odd nitrogen (NOy) were compared side by side aboard a Learjet A35 in April 2003 during a campaign of the AFO2000 project SPURT (Spurengastransport in der Tropopausenregion). The instruments albeit employing the same measurement principle (gold converter and chemiluminescence) had different inlet configurations. The ECO-Physics instrument operated by ETH-Zürich in SPURT had the gold converter mounted outside the aircraft, whereas the instrument operated by FZ-Jülich in the European project MOZAIC III (Measurements of ozone, water vapour, carbon monoxide and nitrogen oxides aboard Airbus A340 in-service aircraft) employed a Rosemount probe with 80 cm of FEP-tubing connecting the inlet to the gold converter. The NOy concentrations during the flight ranged between 0.3 and 3 ppb. The two data sets were compared in a blind fashion and each team followed its normal operating procedures. On average, the measurements agreed within 7%, i.e. within the combined uncertainty of the two instruments. This puts an upper limit on potential losses of HNO3 in the Rosemount inlet of the MOZAIC instrument. Larger transient deviations were observed during periods after calibrations and when the aircraft entered the stratosphere. The time lag of the MOZAIC instrument observed in these instances is in accordance with the time constant of the MOZAIC inlet line determined in the laboratory for HNO3

Pulmonary hemorrhage: Imaging with a new magnetic resonance blood pool agent in conjunction with breathheld three-dimensional magnetic resonance angiography

Purpose: To describe the three-dimensional magnetic resonance angiography (3D MRA) imaging appearance of the pulmonary arteries following administration of a superparamagnetic iron oxide blood pool agent to human volunteers, and to demonstrate in an animal model (pigs) how this technique can be used to detect pulmonary parenchymal hemorrhage. Methods: Two volunteers were examined following the intravenous administration of a superparamagnetic iron oxide blood pool agent (NC100150 Injection, Nycomed Amersham Imaging, Wayne, PA, USA). T1-weighted 3D gradient recalled echo (GRE) image sets (TR/TE 5.1/1.4 msec, flip angle 30°) were acquired breathheld over 24 sec. To assess the detectability of pulmonary bleeding with intravascular MR contrast, pulmonary parenchymal injuries were created in two animals under general anesthesia, and fast T1-weighted 3D GRE image sets collected before and after the injury. Results: Administration of the intravascular contrast in the two volunteers resulted in selective enhancement of the pulmonary vasculature permitting complete visualization and excellent delineation of central, segmental, and subsegmental arteries. Following iatrogenic injury in the two animals, pulmonary hemorrhage was readily detected on the 3D image sets. Conclusion: The data presented illustrate that ultrafast 3D GRE MR imaging in conjunction with an intravenously administered intravascular blood pool agent can be used to perform high-quality pulmonary MRA as well as to detect pulmonary hemorrhag

In vitro image characteristics of an abdominal aortic stent graft: CTA versus 3D MRA

Percutaneous stent-grafting is increasingly employed as a less invasive alternative to surgery for the treatment of infrarenal abdominal aortic aneurysms. It requires long-term imaging follow-up, to document the structural integrity of the device, to exculude perigraft channels and endograft leakages, as well as the shrinkage of the aneurysmal sac. The expectation of severe stent induced artifacts and safety concerns have prevented 3D MRA from being used. The purpose of this in vitro study was to investigate the imaging characteristics of a bifurcated stent graft with 3D MRA (3D Frourier transform fast spoiled GRE) at 1.5 T in comparison to those of CTA. Measurement of the stent wall thickness and luminal diameter were made on a agar gel embedded stent graft at five locations on both CTA and MRA images. The stent graft was depicted as a dark ring on MR images. Wall thickness measurments at the five locations of the stent graft overestimated the true stent thickness, while luminal diameters were slightly underestimated. Measurement differences between MR and CT were not statistically significant (P=0.67;P=0.85). Artifacts emanating from the platinum markers were considerably less severe on the MR-images. A wider area of signal loss was seen only at the insertion of the iliac stent leg into the aortic stent portion due to the overlap of two radio-opaque platinum markers. 3D MRA images should permit a comprehensive assessment of the arterial lumen, and of perivascular tissue

Beyond immune escape:a variant surface glycoprotein causes suramin resistance in Trypanosoma brucei

Suramin is one of the first drugs developed in a medicinal chemistry program (Bayer, 1916), and it is still the treatment of choice for the hemolymphatic stage of African sleeping sickness caused by Trypanosoma brucei rhodesiense. Cellular uptake of suramin occurs by endocytosis, and reverse genetic studies with T. b. brucei have linked downregulation of the endocytic pathway to suramin resistance. Here we show that forward selection for suramin resistance in T. brucei spp. cultures is fast, highly reproducible and linked to antigenic variation. Bloodstream-form trypanosomes are covered by a dense coat of variant surface glycoprotein (VSG), which protects them from their mammalian hosts' immune defenses. Each T. brucei genome contains over 2000 different VSG genes, but only one is expressed at a time. An expression switch to one particular VSG, termed VSGSur , correlated with suramin resistance. Reintroduction of the originally expressed VSG gene in resistant T. brucei restored suramin susceptibility. This is the first report of a link between antigenic variation and drug resistance in African trypanosomes

Factors influencing study engagement during the COVID-19 pandemic: A cross-sectional study among health and social professions students

Background: The aim of this study is to explore factors influencing the study engagement of health and social professions students during the COVID-19 pandemic. While antecedents of study engagement have been studied previously, the factors influencing engagement under pandemic conditions have not yet been investigated. Furthermore, there is a particular need for research among students in health and social professions programs, as these students are particularly affected by the pandemic. As theoretical basis, the study draws on the demands-resources-theory. It is hypothesized that pandemic-related study and personal resources drive engagement during the pandemic, and that pandemic-related demands negatively influence engagement. Method: The study uses a cross-sectional survey to explore the hypothesized effects. The sample consists of 559 university students of health and social professions in Germany. The study was carried out in July 2020, towards the end of the first digital semester and after the first peak in COVID-19 cases. Data are analyzed using linear multiple regression analysis. Results: The findings show that the demands-resources-theory is suitable to explain study engagement even under pandemic conditions. Suitable digital learning formats and social support are identified as important study resources for study engagement during major life events, while emotional resilience, active self-care and academic self-efficacy are identified as important personal resources. Conclusions: Under pandemic conditions academic institutions should focus on providing beneficial teaching formats and innovative ways to support students lacking social networks. Besides, they should consider developing means to help students structuring daily life as well as establishing initiatives to strengthen students' self-efficacy beliefs

Psychological Stress among Students in Health-Related Fields during the COVID-19 Pandemic: Results of a Cross-Sectional Study at Selected Munich Universities

The COVID-19 pandemic has been a challenging period of upheaval for higher education students. This study aims to assess the factors associated with psychological stress during the COVID-19 pandemic among a sample of students in health-related fields at Munich universities in Germany. Students (n = 623) from KSH Munich and LMU Munich completed an online cross-sectional survey. Information on demographics and academic and everyday difficulties due to the COVID-19 pandemic as well as data on physical and mental health were collected. Multivariable logistic regression analyses were performed to identify factors associated with the outcome. The prevalence for higher psychological stress was 44% among the study population. Factors associated with higher psychological stress were: lower overall life satisfaction (p < 0.0001), worsened health situation (p < 0.0001), lack of social support (p = 0.0301) and social interaction (p = 0.0115), worries about financial difficulties due to loss of income (p = 0.0134), stressful thoughts about a second wave (p < 0.0001), feeling unable to positively influence the situation (p = 0.0262) and study-related effects, such as perceived study burden (p = 0.0003) and likely delay in studies (p = 0.0178)). The COVID-19 pandemic is having a significant negative impact on the mental health of students in health-related fields. Proactive efforts to support the mental health and well-being of students are needed

Non-native vascular plant species in strict forest nature reserves in Rhineland-Palatinate

Floristische und vegetationskundliche Daten aus 21 Naturwaldreservaten (NWR) in Rheinland-Pfalz wurden hinsichtlich ihres Anteils an gebietsfremden Gefäßpflanzenarten (Neophyten i. w. S.) ausgewertet und überregional verglichen, um generelle Trends in der Naturnähe und der natürlichen Waldentwicklung - unabhängig von lokal wirkenden Faktoren – aufzuzeigen. Neben überwiegend zonalen, naturnahen Buchenwäldern bodensaurer Standorte umfasst der Datensatz auch drei Auenwald-Standorte und zwei Moorbirken-Bruchwälder. Als Besonderheit im Ver-gleich zu anderen Bundesländern hat Rheinland-Pfalz zwei NWR mit hohen Douglasien-Anteilen ausgewiesen, um deren Entwicklung ohne forstliche Nutzung zu dokumentieren. Von diesen beiden NWR und zwei NWR mit besonderer Dynamik nach Windwurf sowie einem weitgehend ungestörtem NWR im Biosphärenreservat Pfälzer Wald liegen auch Wiederholungsinventuren vor, die erste Hinweise auf die langfristige Entwicklung des Neophyten-Anteils in NWR liefern. Durch einen Vergleich gezäunter und ungezäunter Flächen in NWR konnte der Schalenwildein-fluss, durch den Vergleich mit angrenzenden, weiterhin bewirtschafteten Beständen der Einfluss der forstlichen Nutzung auf den Anteil gebietsfremder Arten an der Vegetation analysiert wer-den. Gebietsfremde Arten spielen in den naturnahen, nicht mehr bewirtschafteten NWR in Rhein-land-Pfalz insgesamt eine untergeordnete Rolle. Vor allem krautige Neophyten sind ausgespro-chen gering vertreten, insbesondere in den naturnahen Buchenwald-NWR. Auch von Impatiens glandulifera, die in allen Auen-NWR am Rhein vorkommt, geht bisher weder ein Verdrängen ein-heimischer Arten noch ein Verlust an Diversität und Naturnähe aus. Den größten Anteil unter den gebietsfremden Arten bilden die nicht-autochthonen Gehölze, die in der Vergangenheit 142 forstlich angebaut wurden und von denen sich vor allem Picea abies, Larix decidua und Pseudotsuga menziesii in den NWR vielfach spontan verjüngen. Wiederholungsinventuren zeigen unterschied-liche Entwicklungen im Anteil gebietsfremder Arten, wobei vorangegangene Störungen (z. B. Windwurf) einen wesentlichen Einfluss ausüben. Im Vergleich der Aufnahmen von zwei Dougla-sien-reichen NWR kam es innerhalb eines Jahrzehnts zu einem starken Rückgang der Douglasie. Sie ist dort vor allem in der Konkurrenz zur Buche unterlegen, so dass sich ohne waldbauliche Unterstützung hier der Naturnähegrad wieder erhöht hat. Ohne Schalenwildeinfluss (hauptsäch-lich Reh- und Rotwild) sind gebietsfremde Arten tendenziell erfolgreicher. Insbesondere Picea abies und Pseudotsuga menziesii waren im Zaun in Strauchschichthöhe stärker vertreten als außer-halb. Im Vergleich mit bewirtschafteten Wäldern ist der Anteil gebietsfremder Arten in unbewirt-schafteten NWR absolut gesehen niedriger. Durch den geringen Artenreichtum an Gefäß-pflanzen und einem geringeren Deckungsgrad der Bodenvegetation im NWR gleichen sich die Unterschiede zwischen (naturnah) bewirtschafteten und nicht bewirtschafteten Wäldern jedoch weitgehend aus.Floristic data and data from vegetation surveys were compared across 21 strict forest nature reserves (SFNR) in Rhineland-Palatinate (south-west Germany) concerning the proportion of non-native plant species (alien plant species or neophytes) in order to detect general trends in the naturalness and dynamics of unmanaged forests in Central Europe. Beside the predominant zonal and close-to-nature oligotrophic beech forests the data set included three eutrophic floodplain forests and two oligotrophic bog woodlands. Apart from other German federal states Rhineland-Palatinate established two SFNR with a high proportion of the alien species Douglas fir in order to study the further development of these stands without forest management. Resurveys of these two SFNR and two further SFNR with a high dynamic after windthrow as well as an undisturbed SFNR in the biosphere reserve Palatinate Forest give the opportunity to analyze long-term trends of alien species. A comparison of fenced and unfenced plots allowed an assessment of browsing effects, a comparison of SFNR with close-by managed forests an assessment of forest manage-ment impacts on the relevance of neophytes in forest vegetation. In a regional context the proportion of non-indigenous plant species in unmanaged SFNR in Rhineland-Palatinate is low. Especially in close-to-nature beech forest SFNR alien herb layer species are rare. Even Impatiens glandulifera – well established in all of the investigated floodplain SFNR of the Rhine valley – seems not to suppress native plant species and shows no negative impact on diversity and the degree of naturalness of the riparian forests. Phanerophytes (woody species) have the highest proportion among aliens in the dataset, mainly introduced by planting in the past. Among them especially Picea abies, Larix decidua, and Pseudotsuga menziesii showed the ability to regenerate naturally in the SFNR. Resurveys of disturbed and undisturbed SFNR indi-cated a divergent development in the proportion of alien species. SFNR stands with Douglas fir Wolfgang Schmidt, Michaela Dölle, Steffi Heinrichs & Patricia Balcar: Gebietsfremde Gefäßpflanzen in Naturwaldreservaten von Rheinland-Pfalz 143 showed a strong decrease of Pseudotsuga menziesii mainly outcompeted by beech within one dec-ade. Therefore, without forest management naturalness of the stands has increased. Without deer browsing (mainly roe and red deer) alien plant species seemed to be more successful. Especially Picea abies and Pseudotsuga menziesii are limited by browsing as fencing increased species frequency and abundance of these woody species within the shrub layer. In general, forest management increased the total number of neophytes. But due to the decreasing species richness and the lower coverage of understorey vegetation in the unmanaged SFNR the differences in the propor-tion of alien species in close-to-nature managed forests and unmanaged forests are negligibl

Fucoidan Does Not Exert Anti-Tumorigenic Effects on Uveal Melanoma Cell Lines

Background. The polysaccharide fucoidan is widely investigated as an anti-cancer agent. Here, we tested the effect of fucoidan on uveal melanoma cell lines. Methods. The effect of 100 µM fucoidan was investigated on five cell lines (92.1, Mel270 OMM1, OMM2.3, OMM2.5) and of 1 µg/mL–1 mg/mL fucoidan in two cell lines (OMM1, OMM2.3). Cell proliferation and viability were investigated with a WST-1 assay, migration in a wound healing (scratch) assay. Vascular Endothelial Growth Factor (VEGF) was measured in ELISA. Angiogenesis was evaluated in co-cultures with endothelial cells. Cell toxicity was induced by hydrogen-peroxide. Protein expression (Akt, ERK1/2, Bcl-2, Bax) was investigated in Western blot. Results. Fucoidan increased proliferation in two and reduced it in one cell line. Migration was reduced in three cell lines. The effect of fucoidan on VEGF was cell type and concentration dependent. In endothelial co-culture with 92.1, fucoidan significantly increased tubular structures. Moreover, fucoidan significantly protected all tested uveal melanoma cell lines from hydrogen-peroxide induced cell death. Under oxidative stress, fucoidan did not alter the expression of Bcl-2, Bax or ERK1/2, while inducing Akt expression in 92.1 cells but not in any other cell line. Conclusion. Fucoidan did not show anti-tumorigenic effects but displayed protective and pro-angiogenic properties, rendering fucoidan unsuitable as a potential new drug for the treatment of uveal melanoma