Freezing procedure

With most single cells so far examined, the survivals obtained with nonequilibrium freezing procedures and vitrification are no better than those obtainable with equilibrium freezing procedures. But vitrification procedures may be necessary for the successful preservation of tissues and organs, which appear not to be able to tolerate the formation of ice in capillaries and other spaces between the cells. 

Surface tension (0.25%, dynes/cm) 32.14 Viscosity, Brookfield (25C, LV 1, 100rpm, cps) 5.1 Freeze thaw stable freezing point (C) Did not freeze Procedure ... 

It is advisable to maintain a small culture of cells until the viability of the cell bank is validated. This ensures survival of the line should the freezing procedure fail. 

The main problem encountered in applying freeze-drying to this type of matrix is the occasional loss of species. A conventional freezing procedure will be more efficient than freeze-drying if it results in smaller losses of volatile elements — a combination of the two may be the ideal choice [60]. In some cases, however, freeze-drying is the best choice for example, it results in the smallest losses of amino acids and amine nitrogen [61]. 

The infected cell culture is brought into 50-mL tubes and the cells are pelleted, and the supernatant is carefully distributed in aliquots of 1 mL in cryotubes. The cryotubes are labeled with a virus stock number. The number and the content are indexed on the list of virus stocks and the tubes are stored at -80°C. For delicate strains, the freezing procedure might damage the virus. Therefore, the titration of the virus stock should be done on a similar frozen aliquot as for the susceptibility testing. In rare cases, freezing abolishes infec-tivity, and virus has to be left at room temperature for a few days until the susceptibility test can be initiated. 

USDA. Code of Federal Regulations—Poultry Products Temperatures and Chilling and Freezing Procedures—Title 9, Part 381.66 Office... 

If using frozen PBMC, resuspend cells in RPMI with 10 % serum and incubate them overnight in a cell incubator. The next day, cells that were damaged by the freezing procedure will be dead, and the viable, intact cells can be counted from a culture aliquot. Percentage of recovered cells after freezingthawing is about 70 %. 

During the freezing procedure the crystal water expands, therefore the crystal is somewhat damaged. Since X-ray pictures on the precession camera were also obtained after freezing, the crystal remained satis-... 

Fig. 14 Initial rate Vo of the decrease of thiol groups in aqueous solutions of thiol-containing poly (acrylamide) plotted against temperature. Freezing procedures were conventional (curve 1) and low-temperature quenching (curve 2). Polymer concentration in the initial solution was 2 g/L. (From [28] with permission from Elsevier)...

Turov, V.V, Leboda, R., Bogillo, VI., and Skubiszewska-Zi ba, J. 1996b. Surface properties of carbonaceous solids as examined by H NMR spectroscopy using the bulk freezing procedure. Adsorp. Sci. Technol. 14 319-330. 

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