1. The effect of an infusion of sodium β-hydroxybutyrate on leucine and alanine metabolism was investigated in dogs starved for 12 h. To determine whether the metabolic changes produced by this infusion were due to the resultant alkalaemia the effect of an equimolar infusion of sodium bicarbonate was also studied. 2. The sodium β-hydroxybutyrate infusion reduced alanine concentration as a result of a decrease in alanine production rate and an increase in alanine metabolic clearance rate. The sodium bicarbonate infusion induced a small decrease in alanine concentration which was due to an increased metabolic clearance rate. Alanine production rate showed no change. This demonstrates that the fall in alanine concentration after a sodium β-hydroxybutyrate infusion is due both to a ketone-specific inhibitory effect on alanine production rate and an increased metabolic clearance rate caused by the alkalaemia. 3. Leucine concentration was increased after the ketone infusion due to a small increase in production rate and there was a small increase in the rate of leucine incorporation into protein. Alkalaemia had no effect on leucine concentration or metabolism.

1. Isoelectric focusing of parotid saliva from 33 patients with rheumatoid arthritis but without clinical evidence of salivary gland involvement revealed multiple abnormal proteins of pI 3.95–4.25 in all cases, whereas only two out of 16 samples from normal healthy individuals exhibited any similar bands. 2. Although rheumatoid factors of abnormally low isoelectric point and restricted heterogeneity were detected in this pI region in five of the diseased samples, these could not account for all of the bands even in these cases. The abnormal proteins did not otherwise cross-react with antisera to immunoglobulin (Ig) G, IgA or albumin. 3. Analysis of rheumatoid arthritis parotid saliva by a method involving adsorption of rheumatoid factors to immobilized rabbit immunoglobulin revealed the presence of salivary rheumatoid factors (in seven patients) of all the major immunoglobulin classes, including secretory-IgA in two patients. 4. Although these abnormal proteins are as yet uncharacterized, their presence could form the basis of a non-invasive procedure in the diagnosis of salivary gland and connective tissue disorders.