Cryoprotectant

Sugar alcohols have also found appHcation in foods containing sugars. Sorbitol is an effective cryoprotectant in surimi, preventing denaturation of the muscle protein during fro2en storage. 

The presence of cryoprotectant, however, does reduce the concentrations of salt at the given temperature according to the relation M aci M aCi /(I where... 

MNaci 2nd M iaci 3re osmolal concentrations of electrolyte in the presence and absence of additive and R is osmolal ratio of cryoprotectant to electrolyte. 

Anchordoguy, T.J., Rudolph, A.S., Carpenter, J.F., Crowe, J.H. (1987). Modes of interaction of cryoprotectants with membrane phospholipids during freezing. Cryobiol. 24,324-331. 

Khirobadi, B.S., Fahy, G.M., Saur, J., Meryman, H.T. (1993). Perfusion of rabbit kidneys with 8 molar cryoprotectant (V52). Cryobiol. 30,611-612 (abstract). 

Rudolph, A. S., and Crowe, J. H. (1985). Membrane stabilization during freezing The role of two natural cryoprotectants, trehalose and proline, Cryobiology, 22, 367-377. 

Lack of repeatability of the results of metabolic studies using laboratory strains that have been maintained by repeated transfer for long periods under nonselective conditions may be encountered. These strains may no longer retain their original metabolic capabilities, and this may be particularly prevalent when the strains carry catabolic plasmids that may have been lost under nonselective conditions. For these reasons, strains should be maintained in the presence of a cryoprotectant such as glycerol at low temperatures (-70°C or in liquid Nj) as soon as possible after isolation. Freeze-drying is also widely adopted, and is recommended. 

Most proteins are not sufficiently stable in aqueous solution to allow formulation as a sterile solution. Instead, the protein is freeze-dried and reconstituted before use. Development of a freeze-dried protein formulation often requires special attention to the details of the freezing process (potential pH shifts and ionic strength increase with freezing) as well as to potential loss of activity with drying. Formulation additives, such as sugars and polyhydroxy compounds, are often useful as cryoprotectants and lyoprotectants. Residual moisture may also be critical to the stability of the dried preparation [33],... 

DMSP (21) is produced by many marine micro- and macroalgae and is especially prominent in dinoflagellates and haptophytes. The nontoxic DMSP (21) fulfills multiple cellular functions including cryoprotection, the involvement as osmolyte in osmoregulation and as a methyl donor in transmethylation reactions [18]. 

Park, Y.S., and Huang, L. (1992) Cryoprotective activity of synthetic glycophospholipids and their interactions with trehalose. Biochim. Biophys. Acta 1124, 241-248. 

Talsma, H., van Steenberg, M.J., and Crommelin, D.J.A. (1991) The cryopreservation of liposomes 3. Almost complete retention of a water-soluble marker in small liposomes in a cryoprotectant containing dispersion after a freezing/thawing cycle. Int. J. Pharm. 77, 119-126. 

Freeze-drying is a relatively gentle way of removing water from proteins in solution. However, this process can promote the inactivation of some protein types, and specific excipients (cryopro-tectants) are usually added to the product in order to minimize such inactivation. Commonly used cryoprotectants include carbohydrates (such as glucose and sucrose), proteins (such as HSA), and amino acids (such as lysine, arginine or glutamic acid). Alcohols/polyols have also found some application as cryoprotectants. 

Influence of Exipients Growers of Structures and Cryoprotectant Agents (CPAs)... 

The stability of moisture-sensitive drugs has been studied by Vromans and Schalks [1.143] using amorphous vecuronium bromide. Its decomposition in a formulation depends more on the water activity aw (see Chapter 4, point 2) than on the water content. Glass-forming excipients may not only be cryoprotective but also stabilizing. 

Rasmussen, D., Luyet, B. Contribution to the establishment of the temperature concentration curves of homogeneous nucleation in solutions of some cryoprotective agents. Biodynamica., Vol. 11, No. 225, p. 33-44, 1970... 

Sutton, R. L. Critical cooling rates to avoid ice cristallisation in solutions of cryoprotective agents. Journ. Chem. Soc. Faraday Trans. Vol. 87, p. 101-106, 1991... 

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