Abstract: A method is disclosed for reliably stabilizing eukaryotic cells that express the P2X7 receptor channel, particularly mammalian and other vertebrate cells, including human cells, for example mammalian macrophages, or hematopoietic stem cells, in order to introduce otherwise membrane-impermeable compounds that are helpful for stabilizing the cells during drying, chilling, freezing, freeze-drying, or cryopreservation. The cells are exposed to extracellular ATP in concentration sufficient to open pores in the plasma membrane. One or more otherwise membrane-impermeable compounds that aid the survivorship of cells are then introduced, for example, trehalose, and after a brief time the pores are closed—for example, by adding divalent cations, or by diluting the extracellular solution. Once the trehalose or other stabilizing compound has been introduced, the cells may be stably preserved. By taking advantage of an endogenous mammalian receptor and ATP, no antigenic compounds need be introduced.

Abstract: A method of protecting soluble proteins such that their biological activity is preserved after freezing by exposing the protein to an amino acid or trimethylamine-N-oxide and transition metal ion prior to freezing. The protected protein can then be thawed without denaturation or impairment of the protein's biological activity. The protein is preferably exposed to the amino acid or trimethylamine-N-oxide by placing it in a 25-100 mM aqueous solution of organic solute and 1 mM Zn.sup.+2. This method is especially effective in preserving the biological activity of fragile proteins such as the enzyme phosphofructokinase. The present method can be used to preserve pharmaceutically useful proteins in a frozen form for storage and distribution. The treated protein can be thawed and administered directly to a user without removing the cryoprotectant since the amino acid or oxide and trace amounts of many transition metal ions are nontoxic.

Abstract: A method of protecting soluble proteins such that their biological activity is preserved after freezing by exposing the protein to a carbohydrate and transition metal ion prior to freezing. The protected protein can then be thawed or lyophilized and rehydrated without denaturation of impairment of the protein's biological activity. The protein is preferably exposed to the carbohydrate by placing it in a 25-100 mM aqueous solution of carbohydrate and 2 mM Z.sup.+2. This method is especially effective in preserving the biological activity of fragile proteins such as the enzyme phosphofructokinase. The present method can be used to preserve pharmaceutically useful proteins in a frozen or freeze-dried form for storage and distribution. The treated protein can be thawed or rehydrated and administered directly to a user without removing the cryoprotectant since the carbohydrates and trace amounts of many transition metal ions are nontoxic.

Abstract: Sense voltages representative of transmitter power and the temperature of the transmitter output stage are summed and fed to the input of a high gain amplifier. The output of the amplifier provides bias to the transmitter driver stage and, thus, controls the total transmitter developed power. The resulting overall feedback system provides precise transmitter power control and output stage thermal protection.