The urinary excretion of 1-methylimidazole-4-acetic acid, a histamine metabolite, by healthy and asthmatic children

1. The excretion of 1-methylimidazole-4-acetic acid (MeIAA) in urine was measured in three groups of asthmatic children (acute-symptoms, quiescent and steroid-treated) and a control group of hospitalized non-asthmatic children all on the same restricted diet.

2. There was no statistical difference between the excretion of MeIAA in urine in any of the groups. There was therefore no evidence of impairment of the methylation pathway of histamine metabolism in asthma.

Immunoglobulins in haemolytic disease of the newborn

Concentrations of IgG, IgA and IgM were measuredin the sera of infants with haemolytic disease of the newborn and I control infants from birth to the age of 6 months. No significant Differences were found between the IgG, IgA and IgM concentrations in haemolytic disease and control infants of comparable birth weight. Inhibition of IgG synthesis in the infant from the presence of antiglobulins in transfused blood or from interference with a feed-back control mechanism based on Gm phenotype could not be demonstrated.

Gm antigenic titres in adults with Down's syndrome (mongolism), non-mongoloid mental defectives and healthy blood donors

IgG was studied in adults with Down's syndrome, non-mongoloid mental defectives accommodated in the same institution and in healthy blood donors. Total serum IgG concentration was significantly higher in Down's syndrome than in the other two groups. Maximal inhibiting titres of Gm factors 1, 4, 5, 10 and 11 were measured by haemagglutination inhibition tests. Higher Gm titres were found in homozygotes than heterozygotes. In mongols the titres of Gm 4, and to a greater extent, Gm 5, 10 and 11, were higher than would be expected from the rise in total IgG concentration. The findings suggest that in mongolism an uneven increase occurs in the H chain subgroups and allotypes of IgG. In non-mongoloid mental defectives, although total IgG concentration was similar to that found in healthy normal subjects the Gm titre findings more closely resembled those in mongols.