The effect of freezing on formation of soluble and insoluble aggregates of human growth hormone (hGH) was studied. The amount of soluble aggregates was affected very little by freezing regardless of the cooling rate. In contrast, the formation of insoluble aggregates (particulates), as determined by light scattering in the 340- to 360-nm range, was found to increase sharply with increasing cooling rates. The amount of these particulates was also dependent on the pH of the solution. Freezing hGH solutions formulated at pH 7.4 resulted in highly scattering solutions, whereas pH 7.8 formulations showed significantly less scattering. These results emphasize the importance of understanding the freezing phenomenon for protein solutions and suggest that the formation of soluble aggregates and insoluble particulates may have different mechanisms.

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Dopa-decarboxylase, acetylcholinesterase, sodium plus potassium stimulated adenosine triphosphatase (Na+ + K+-ATPase), and membrane-bound protein kinase were compared in the erythrocytes of patients with Huntington's disease and normal controls. All these enzymes also exist in the basal ganglia. The Na+ +K+-ATPase level was elevated (p less than 0.05) in Huntington's disease, while no significant changes were observed in the other enzymes. This finding is consistent with the concept that Huntington's disease is associated with a general membrane abnormality.

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