The Desiccation of Sera and Other Biological Products (Including Micro?rganisms) in the Frozen State with the Preservation of the Original Qualities of Products So Treated

摘要

1. 1. Methods and apparatus for the drying of biological products in the frozen state are described in detail.2. 2. These differ from procedures hitherto recorded in that they involve the use of manifolds and individual containers in the drying process and storage of the dried product in vacuo.3. 3. Both chemicals and refrigerants in combination with a high vacuum were used for the disposal of water vapors arising in the course of the desiccating process.4. 4. The use of refrigerants for the condensation of the water vapor has many advantages. Large volumes of biological material can be desiccated in a comparatively short time which brings the method into the realm of practical procedures for the preservation of therapeutic agents.5. 5. A method of processing larger volumes of sera in bulk is described in which the rate of evaporation in vacuo and the removal of the water vapor by means of refrigerants is relied upon not only to freeze the material, but also to maintain the product in the frozen state until drying is complete.6. 6. The materials thus secured exhibit features which have a great practical value. Clear sera when treated in this manner yield a product which shows no material reducation in volume; is porous in texture; breaks up readily into a fine powder; is readily soluble in water; and yields, when restored to the fluid state, a clear solution—all features of importance where the preservation of sera designed for therapeutic use is concerned.7. 7. When suitable precautions are adopted the product, if originally free from microbic contaminations, is sterile.8. 8. Antisera and antigens as well as certain related products when dried in the frozen state by these methods and stored in vacuo suffer no deterioration in numerical values and the dried products when reclaimed after a number of years show no loss in potency.9. 9. Bacteria and yeasts have been preserved unchanged by the procedures described and in no instance have the strains shown any changes even in minor particulars. Such highly sensitive micro?rganisms as the gonococcus and meningococcus have been preserved by the method for a period of eighteen years.10. 10. Protozoa and spirochaeta have been recovered after drying in the frozen state but only in a few instances.11. 11. These investigations did not include viruses as we were aware that others were engaged in this work.