Performance of secondary P-fertilizers in pot experiments analyzed by phosphorus X-ray absorption near-edge structure (XANES) spectroscopy.

A pot experiment was carried out with maize to determine the phosphorus (P) plant-availability of different secondary P-fertilizers derived from wastewater. We analyzed the respective soils by P K-edge X-ray absorption near-edge structure (XANES) spectroscopy to determine the P chemical forms that were present and determine the transformation processes. Macro- and micro-XANES spectroscopy were used to determine the chemical state of the overall soil P and identify P compounds in P-rich spots. Mainly organic P and/or P adsorbed on organic matter or other substrates were detected in unfertilized and fertilized soils. In addition, there were indications for the formation of ammonium phosphates in some fertilized soils. However, this effect was not seen in the maize yield of all P-fertilizers. The observed reactions between phosphate from secondary P-fertilizers and co-fertilized nitrogen compounds should be further investigated. Formation of highly plant-available compounds such as ammonium phosphates could make secondary P-fertilizers more competitive to commercial phosphate rock-based fertilizers with positive effects on resources conservation.

Mast cell tryptase in sera of patients with Crohn's disease and mastocytosis.

INTRODUCTION: The pathogenesis of Crohn's disease is unclear, but an abnormal immune response seems to play an important role. This study investigated whether serum tryptase could be shown in Crohn's disease as a marker of disease. MATERIALS AND METHODS: Mast cell tryptase was detected in sera of 48 patients with active Crohn's disease, 31 patients with inactive Crohn's disease, 17 patients with mastocytosis, and 50 controls. Tryptase detection was carried out by UniCap System. Tryptase levels are given as U/l x m2 body surface area to overcome variations of body weight, height, etc. between malnourished and normal persons. RESULTS: Serum tryptase levels (U/l x m2 body surface area) of controls were 2.4+/-1.0, of patients with Crohn's disease 2.5+/-2.0. In contrast, serum tryptase values were significantly increased in untreated patients with mastocytosis (21.19+/-18.55). DISCUSSION: Mast cell tryptase is not elevated in sera of Crohn's disease. It might thus be speculated that this highly mast cell associated mediator might only contribute to local symptoms of Crohn's disease such as diarrhea, abdominal pain, etc., but not to its systemic inflammatory effects (Th 1 cytokine pattern). Tryptase may be well used for the screening of patients with mastocytosis.