European interlaboratory trial regarding the official microscopic method for the detection of the presence of animal constituents in feedstuffs.

The bovine spongiform encephalopathy epidemic is thought to have occurred as a consequence of feeding prion-infected material to cattle. To avoid the risk of bovine spongiform encephalopathy diffusion, the European Commission (Directive 2003/126/EC) established an official method to detect the presence of animal-derived constituents in feedstuffs, using microscopic examination. This method allows easy identification of bone fragments among other animal constituents. The analysis is based on morphological conformation of the fragments and their characterization (mainly of the shape of lacunae) to discriminate among mammalian, poultry, and fish tissues. The aim of this study was to assess the performances of nine European laboratories through a ring trial of the official microscopic method, and to calculate accuracy and reproducibility of the method. In general the reproducibility of the microscopic method was very good (kappa overall = 0.83), with a high sensitivity for all laboratories. Concerning the analysis on the different animal-derived constituents, the results show values of sensitivity with large variability between fish and poultry or mammal. It was generally more difficult to discriminate between mammalian and poultry tissues than fish tissue.

Agmatine modulates the in vivo biosynthesis and interconversion of polyamines and cell proliferation.

Agmatine has recently gained wide interest as a bioactive arginine metabolite with a multitude of physiological functions. This study evaluates the in vivo role of agmatine in the modulation of metabolism and intracellular level of polyamines. Here, we report that agmatine, administered to mice, differentially affects the renal and liver activity of the two key enzymes regulating polyamine biosynthesis and interconversion/degradation. Thus, agmatine exerts a negative regulation of ODC activity and protein content, and positive regulation of SSAT activity, having no effect on ODC and SSAT transcript level. Agmatine modulation of ODC and SSAT activities is noticeably augmented by the inhibitor of its catabolism, aminoguanidine. Antizyme and eIF4E protein content appears to be affected by agmatine only insignificantly and apparently do not contribute to agmatine-induced down-regulation of ODC content. The homeostasis of spermidine and spermine is preserved after agmatine injection, while the putrescine level decreases. Furthermore, when tested in a mouse kidney injury model, agmatine, partially but significantly, reduces [3H] thymidine incorporation into DNA. This is consistent with suppressed renal tubule epithelial cell proliferation. The findings provide in vivo evidence of a substantial role of agmatine as a modulator of polyamine biosynthesis and degradation and suggest its suppressive effect on cell proliferation.