ABORTION

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Abstract

The cryo was prepared by a rapid thaw procedure in agitated water bath and the supernatant was syphoned off completely leaving bahind from 4 mL to 6 mL of precipitate. The connecting tubing was sealed off 4 cm from the cryo bagswhich were then immersed briefly in luke-warm water to dissolve the contents.The bagswere next inserted in to parallel rows of three into acrylic trayswith vertical conpanmentsmeasuring 150 mmx 100 mmx 25 mm. After cutting off the sealed ends of the tube tails tha bagswereinflatedin situ with filteredair or nitrogen, closedoff with lubricated caps, and the whole assembly was turned on its side in order to spread the contents on tha walls of the bags which were to be frozen in this position. For obviousreasons freeze-drying of inflatedbagsrequires a relatively largespace, but only a very modest pumping and condenser capacity. In our laboratory aspecially constructad 50 litreacrylicextension to an Edwards EF03 model freeze-dryer served well to accomodate 60 bags and, with furthar extensions, the original system should be able to handla batches at least three times this number. To facilitate rapid removal. rows of the sealing caps wareconnected to a rip cordandcould ba extracted with one movement. Specially modified bags (courtesy of Tuta Laboratories) with 7 mm-wida tube attachments could befitted with lubricated capswhich did not require manual removal, but which wereblown off automatically when the chamber was evacuated. Efficient freeze-drying would not be possible if the bags were allowed to collapse. but this was.prevented by their rigidity whan frozen and the fact that the supponing compartments were a little narrower in width than the collapsed bags. Altar drying to a constanttemperature the chamber was fillad with dry, sterile nitrogan, the bags collapsed by connecting individuallyto a vacuum manifoldand sealed undersuctionafter 15 to 30 minutes. Clinical trials ware conducted on suitable patients at the Royal Prince Allred Hospital. Camperdown. The straw-coloured plaques of dried cryo were easily reconstituted with to mL to 20 mL of physiological saline andpooledsamples werekeptfor assays. Whilesystematic studies of optimal conditions for long-term storage are still to be completed,our preliminary experience indicates good stability for some months at 4'C and for days to weeks at roomtemperature. Reconstitution is rapidwithin several minutesand may be aided by workingthe material with fingers through the wall of the bags. The preparation was well tolerated by patients and produced an expected rise in Factor VIII. Unlike pooledconcentrates, individualbagscannotbetaggedwith the precise number of Factor VIII units and we have to rely on the mean contentsof a batch. According to our present experience thereis no morethana 5%to t 0% lossof yield,compared with the usualfrozen material,so that the expectedmean yield per donation was at least 100 I.U. of Factor VIII, or almost double the yield obtained in intermediate purity preparations. Economy of production together with relatively high yield makes freeze-dried cryo an attractive alternative to the more refined products. We thank Dr H. Kronenberg and staff members at the Royal Prince Alfred Hospital for their collaboration in clinical trials. J. MARGOLIS, P, RHOADES. Red Cross Blood Transfusion Service, 153 Clarence Street, Sydney, N.S.w. 2000.