Dr Biggs made a number of pertinent criticisms, notably that the FVIII content of the Standards was too low to Sirolimus cost be considered normal, that the reports of the collaborative studies, written by a statistician, were ‘incomprehensible’, and that insufficient quantities were available. I instituted a number of changes to deal with these criticisms, in particular to avoid losses of FVIII I shortened the time between blood collection and freeze

drying (this involved transport of the plasma in my own vehicle). Tom Kirkwood and I tried to write the reports so that they could be understood by laboratory scientists without specialized statistical knowledge, and I distributed the standards in larger amounts, particularly to smaller labs to use as a working standard. The increased usage meant frequent replacements, almost on an annual basis, but the wider availability of the Standards was much appreciated, and hopefully contributed to improved agreement on FVIII assays between laboratories in the UK. The other main function of NIBSC apart from making national and International Standards was to act as the National Control Laboratory for testing Biological Products, and I soon found increasing numbers of batches of FVIII concentrates coming in for testing (the Therapeutic Substances Act of 1968 had laid down mandatory testing of each batch of biological products by

NIBSC before it could be marketed). The numbers Panobinostat nmr increased further when samples started to arrive from the national fractionation laboratories at Elstree and Edinburgh (they had previously been exempt from testing), and it became impractical to use the IS directly to assay all these products. We needed a working standard, and I contacted the Fractionation Laboratories at Elstree and Edinburgh to see if they would support the creation of a British Working Standard for FVIII concentrate, to

be shared among all three laboratories. The two centres took up this idea enthusiastically, and it became a longstanding and mutually satisfactory arrangement, whereby one of the two manufacturers selleck screening library would supply the concentrate, and NIBSC would arrange the ampouling and calibration by collaborative study. In keeping with general practice in standardization, once the first IS for FVIII had been established, successive batches of British Standards (both plasma and concentrates) were calibrated against it. The assays of the plasma standards were much more variable among labs than those of the concentrates, and when analysing a series of studies, Tom Kirkwood and I noticed that there was a significant discrepancy between the results from one-stage and two-stage assays; the one-stage method gave higher potencies than the two-stage method, by 20% on average [16]. This is another example of the ‘like vs. like’ principle and it became clear that a separate International Plasma Standard for FVIII would be desirable to calibrate local and commercial plasma standards.