Zwavelvoorziening graslandpercelen varieert sterk binnen bedrijven

Uit vers-gras onderzoek in 1999 bleek dat op alle Koeien&Kansen bedrijven enkele of meerdere percelen in de eerste snede een risico van S-tekort hadden ongeacht de grondsoort. Vaststelling van S-gehalten via vers-grasanalyse of het opstellen van een zwavelbalans dus gewenst

Naar een zwavelbemestingsadvies op zand-grasland

Zwavelbemesting kan vooral op zandgrasland in Noord- en Oost-Nederland een hogere opbrengst geven. Voorlopig wordt aangeraden om met uitzondering van veengrond maximaal 25-35 kg S per ha te geven. Bij voorkeur te verdelen over de eerste en tweede snede, om te hoge gehalten aan S in gras te vermijde

Zwavelbemesting in voorjaar kan hogere grasopbrengst geven

Het blijkt dat er op bijna 35 % van de graslandpercelen een risico op zwaveltekort is. Aanvullen van een tekort aan S leidt tot een betere N-benutting en lagere nitraatgehaltes in gras

Vernieuwd Tsom advies goed voor grasopbrengst en N-benutting

Het optimale tijdstip van bemesten van de eerste snede is afhankelijk van de streefopbrengst. Voor een vroege weidesnede ligt dit tijdstip bij Tsom 200, voor een maaisnede bij Tsom 300

A Performance Assessment of a Tactical Airborne Separation Assistance System using Realistic, Complex Traffic Flows

This paper presents the results from a study that investigates the performance of aspects of an Airborne Separation Assistance System (ASAS) under varying demand levels using realistic traffic patterns. This study only addresses the tactical aspects of an ASAS using aircraft state data (latitude, longitude, altitude, heading and speed) to detect and resolve projected conflicts. The main focus of this paper is to determine the extent to which sole reliance on the proposed tactical ASAS can maintain aircraft separation at demand levels up to three times current traffic. The effect of mixing ASAS equipped aircraft with non-equipped aircraft that do not have the capability to self-separate is also investigated

Stikstofbemesting: goed plannen, beter benutten

Is vanwege MINAS de stikstofjaargift lager dan landbouwkundig optimaal, dan is een andere interpretatie van de adviesbasis nodig

Bij zodebemesting toevoegmiddelen aan mest te duur

Er bestaat veel onduidelijkheid over de werking en de economische meerwaarde van het gebruik van toevoegmiddelen aan mest

Tumor microenvironmental changes induced by the sulfamate carbonic anhydrase IX inhibitor S4 in a laryngeal tumor model

BACKGROUND AND PURPOSE: Carbonic anhydrase IX (CAIX) plays a pivotal role in pH homeostasis, which is essential for tumor cell survival. We examined the effect of the CAIX inhibitor 4-(3'(3",5"-dimethylphenyl)-ureido)phenyl sulfamate (S4) on the tumor microenvironment in a laryngeal tumor model by analyzing proliferation, apoptosis, necrosis, hypoxia, metabolism and CAIX ectodomain shedding. METHODS: SCCNij202 tumor bearing-mice were treated with S4 for 1, 3 or 5 days. CAIX ectodomain shedding was measured in the serum after therapy. Effects on tumor cell proliferation, apoptosis, necrosis, hypoxia (pimonidazole) and CAIX were investigated with quantitative immunohistochemistry. Metabolic transporters and enzymes were quantified with qPCR. RESULTS: CAIX ectodomain shedding decreased after treatment with S4 (p<0.01). S4 therapy did neither influence tumor cell proliferation nor the amount of apoptosis and necrosis. Hypoxia (pimonidazole) and CAIX expression were also not affected by S4. CHOP and MMP9 mRNA as a reference of intracellular pH did not change upon treatment with S4. Compensatory mechanisms of pH homeostasis at the mRNA level were not observed. CONCLUSION: As the clinical and biological meaning of the decrease in CAIX ectodomain shedding after S4 therapy is not clear, studies are required to elucidate whether the CAIX ectodomain has a paracrine or autocrine signaling function in cancer biology. S4 did not influence the amount of proliferation, apoptosis, necrosis and hypoxia. Therefore, it is unlikely that S4 can be used as single agent to influence tumor cell kill and proliferation, and to target primary tumor growth

The prognostic value of the hypoxia markers CA IX and GLUT 1 and the cytokines VEGF and IL 6 in head and neck squamous cell carcinoma treated by radiotherapy ± chemotherapy

BACKGROUND: Several parameters of the tumor microenvironment, such as hypoxia, inflammation and angiogenesis, play a critical role in tumor aggressiveness and treatment response. A major question remains if these markers can be used to stratify patients to certain treatment protocols. The purpose of this study was to investigate the inter-relationship and the prognostic significance of several biological and clinicopathological parameters in patients with head and neck squamous cell carcinoma (HNSCC) treated by radiotherapy ± chemotherapy. METHODS: We used two subgroups of a retrospective series for which CT-determined tumoral perfusion correlated with local control. In the first subgroup (n = 67), immunohistochemistry for carbonic anhydrase IX (CA IX) and glucose transporter-1 (GLUT-1) was performed on the pretreatment tumor biopsy. In the second subgroup (n = 34), enzyme linked immunosorbent assay (ELISA) was used to determine pretreatment levels of the cytokines vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) in serum. Correlation was investigated between tumoral perfusion and each of these biological markers, as well as between the markers mutually. The prognostic value of these microenvironmental parameters was also evaluated. RESULTS: For CA IX and GLUT-1, the combined assessment of patients with both markers expressed above the median showed an independent correlation with local control (p = 0.02) and disease-free survival (p = 0.04) with a trend for regional control (p = 0.06). In the second subgroup, IL-6 pretreatment serum level above the median was the only independent predictor of local control (p = 0.009), disease-free survival (p = 0.02) and overall survival (p = 0.005). CONCLUSION: To our knowledge, we are the first to report a link in HNSCC between IL-6 pretreatment serum levels and radioresistance in vivo. This link is supported by the strong prognostic association of pretreatment IL-6 with local control, known to be the most important parameter to judge radiotherapy responses. Furthermore, the combined assessment of CA IX and GLUT-1 correlated independently with prognosis. This is a valuable indication that a combined approach is important in the investigation of prognostic markers