A Complex Growth Factor in Duodenal Tissue

A commercial preparation of dry duodenal tissue was hydrolyzed and fractionated to determine whether this material contained thyroid hormones. Five fractions, capable of reinstating growth of growth-arrested, sulfaguanidine-fed rats, were obtained. All were stable to acid hydrolysis and insoluble in 0.1 N HCl. They differed from each other with respect to their solubility in benzene, acetone and methanol, and their stability to alkaline hydrolysis. Neither thyroxine nor triiodothyronine could be detected in four of the fractions. It was concluded that the ability of duodenal powder to reinstate growth of thyroid hormone-deficient rats was not due to thyroxine or triiodothyronine but to unknown factors.