In vitro characterization of commercial Factor VIII concentrates: long-term follow-up

Fifty batches of Factor VIII concentrates from 12 producers were characterized in a long-term follow-up. The following parameters were measured: Factor VIII: C, Factor VIIIR: AG, Factor VIII: Rcof, specific activity (U Factor VIII: C/mg protein), fibrinogen, IgG, IgM, IgA, isoagglutinins, Hbs-AG, heparin-like activity, thrombin-like activity, antithrombin III, Factor VIII-stability at room temperature, and the rate of complete dissolution of the lyophilizate. In most preparations there was an unacceptable batch-to-batch variation of both Factor VIII complex and contaminating proteins, which exceeded the inter-assay coefficient of variation of the applied test systems. Nevertheless, different brands could be recognized by their typical protein pattern. The results obtained suggest that the standardization of Factor VIII concentrates of unknown composition is still accompanied by considerable risks.     

A test for top-down cascade in a detritus-based food web by litter-dwelling web spiders

A top-down cascade in detritus-based food webs has the potential to alter ecosystem functioning but its prevalence in terrestrial systems remains unclear. We manipulated the density of the dominant web spider Neriene brongersmai for 1.5 years to see whether the cascading effect would propagate down to the litter decomposition rate in the forest-floor of a Japanese cedar forest. Decreasing spider abundance increased collembolan density, but it did not change the biomass of microorganisms or the litter decomposition rate. We propose possible explanations for the absence of a top-down cascade and discuss the difficulty in generalizing the presence and absence of a cascading effect in soil ecosystems.