Water

Rede Wageningen, 25 Mei 193

Reconstructing grazer assemblages for protected area restoration

Protected area management agencies often struggle to reliably reconstruct grazer assemblages due to a lack of historical distribution data for their regions. Wrong predictions of grazing assemblages could potentially affect biodiversity negatively. The objective of the study was to determine how well grazing herbivores have become established since introduction to the Mkambati Nature Reserve, South Africa, how this was influenced by facilitation and competition, and how indigenous grazer assemblages can best be predicted for effective ecological restoration. Population trends of several grazing species were investigated in in order to determine how well they have become established since introduction. Five different conceivable grazing assemblages reflecting a range of approaches that are commonly encountered during conservation planning and management decision making were assessed. Species packing was used to predict whether facilitation, competition or co-existence were more likely to occur, and the species packing of the different assemblages were assessed using ANCOVA. Reconstructing a species assemblage using biogeographic and biological information provides the opportunity for a grazer assemblage that allows for facilitatory effects, which in turn leads to an ecosystem that is able to maintain its grazer assemblage structure. The strength of this approach lies in the ability to overcome the problem of depauperate grazer assemblages, resulting from a lack of historical data, by using biogeographical and biological processes, to assist in more effectively reconstructing grazer assemblages. Adaptive management of grazer assemblage restoration through reintroduction, using this approach would further mitigate management risks

Low Arginine Plasma Levels do not Aggravate Renal Blood Flow after Experimental Renal Ischaemia/reperfusion

AbstractBackground: ischaemic renal dysfunction is present in many clinical settings, including cardiovascular surgery. Renal hypoperfusion seems to be the most important pathophysiologic mechanism. Arginine plasma levels are rate limiting for NO synthesis, and low arginine plasma levels are seen after major vascular surgery. Objective: to establish the effects of low arginine plasma levels on renal blood flow after renal ischaemia/reperfusion. Design: Wistar rats were used in this unilateral renal ischaemia/reperfusion model. After 70 min of ischaemia, the kidney was reperfused for 150 min. Arginase infusion was used to lower arginine plasma levels. Blood flow measurement was performed at the end of the experiment using radiolabelled microspheres. Additional experiments were performed for histopathology. Results: arginase efficiently decreased arginine plasma levels to about 50% of normal. There was a lower blood flow in the ischaemic kidney than the contralateral (non-ischaemic) kidney. Lowering arginine plasma levels did not reduce renal blood flow in the ischaemic kidney. Renal histopathology was not influenced by lowered arginine plasma levels. Conclusions: lowering arginine plasma levels did not affect blood flow or histology following renal ischaemia and reperfusion

Geïntegreerd ruimtelijk evaluatie-instrumentarium voor natuurontwikkelingsscenario's (GREINS); koppeling van ecologische modellen aan de hand van een voorbeeldstudie in het stroomgebied van de Beerze-Reusel

GREINS is een set van gekoppelde procesmodellen die geografisch expliciete informatie bewerken, teneinde uitspraken te doen over de kansrijkdom van natuurontwikkeling op regionale schaal. Vier modellen worden gebruikt om de ontwikkelingen in respectievelijk hydrologie, bodem, vegetatie en natuurbehoudswaarde te beschrijven. Deze modellen zijn gekoppeld door een centrale database. De modelinvoer bestaat uit de regionale abiotiek (bodemkaart, geologische kaart, hoogtekaart, depositie, vegetatiestructuur, beheer); de uitvoer geeft de "natuurbehoudswaarde", een gegeneraliseerde maat voor de botanische biodiversiteit. Dit rapport beschrijft op globale wijze een aantal verbeteringen die zijn aangebracht in het model GREINS. Deze verbeteringen betreffen vooral het ruimtelijk oplossend vermogen, de technische efficiëntie van de koppeling tussen de modellen, en de detaillering van het effect van abiotische condities. Als voorbeelden van mogelijke uitvoer worden kaarten gegeven van een aantal ecologische toestandsvariabelen in het Beerze-Reuselgebied, zoals berekend voor de huidige situatie

Screening for Hepatitis C Virus Reinfection Using a Behaviour-Based Risk Score among Men Who Have Sex with Men with HIV:Results from a Case–Control Diagnostic Validation Study

We assessed the predictive capacity of the HCV-MOSAIC risk score, originally developed for primary early HCV infection, as a screening tool for HCV reinfection in 103 men who have sex with men (MSM) with HIV using data from the MOSAIC cohort, including MSM with HIV/HCV-coinfection who became reinfected (cases, n = 27) or not (controls, n = 76) during follow-up. The overall predictive capacity of the score was assessed using the area under the receiver operating characteristic (AUROC) curve. The effects of covariates on the receiver operating characteristic (ROC) curve were assessed using parametric ROC regression. The score cut-off validated for primary early infection (≥2.0) was used, from which the sensitivity and specificity were calculated. The AUROC was 0.74 (95% confidence interval (CI) = 0.63–0.84). Group sex significantly increased the predictive capacity. Using the validated cut-off, sensitivity was 70.4% (95%CI = 49.8–86.2%) and specificity was 59.2% (95%CI: 47.3–70.4%). External validation from a cohort of 25 cases and 111 controls, all MSM with HIV, resulted in a sensitivity of 44.0% (95%CI = 24.4–65.1) and specificity of 71.2% (95%CI = 61.8–79.4). The HCV-MOSAIC risk score may be useful for identifying individuals at risk of HCV reinfection. In sexual health or HIV-care settings, this score could help guide HCV-RNA testing in MSM with a prior HCV infection.</p

Стратегічне планування як основний інструмент ефективності підприємства

Наук. кер.: А.Ю. Жулавськи