Early variations of plasma somatomedin activity in the newborn.

In neonates, plasma somatomedin as measured by the porcine cartilage assay was very low during the first day of life. A striking increase was observed on day 4 and 5, with a return to lower values at a later age. These findings indicate an early capacity to generate somatomedin activity in newborns.

Development of a purified cholera toxoid. II. Preparation of a stable, antigenic toxoid by reaction of purified toxin with glutaraldehyde.

Evidence is presented which confirms that cholera toxoids obtained by reaction of purified toxin with Formalin possess the ability to partially reactivate both in vivo and in vitro. At the same time, conditions are presented for the preparation of stable, antigenic cholera toxoids by reaction of purified toxin with glutaraldehyde. Treatment of purified cholera toxin with approximately 200 mol of glutaraldehyde per mol of toxin at pH 7.

Development of a purified cholera toxoid. I. Purification of toxin.

The enterotoxin from Vibrio cholerae is selectively concentrated from cell-free culture supernatant by co-precipitation with hexametaphosphate and is further purified by adsorption on aluminum hydroxide powder. The bulk of residual somatic antigen becomes insoluble upon lyophilization of the toxin preparation and is removed by centrifugation of the rehydrated material. Other contaminants are eliminated by treatment with activated carbon.