Measurement of plasma renin activity by semi-micro radioimmunoassay of generated angiotensin I

A semi-micro method for determination of plasma renin activity (PRA) by radioimmunoassay of generated angiotensin I (AI) is described. The method permits measurement of PRA on 250 mul of plasma without loss of specificity, sensitivity, accuracy or preision. The small sample size has considerable application in terms of investigation of infants and young children. A reference range was established for healthy children on free diets. There was a 15-fold decline in PRA with age from a mean value of 1404pgAI/ml h-1 (ngAI/1. h-1) in infancy to a mean of 85 pgAI/ml h-1 (ngAI/1. h-1) in adult life.

Hypertension, oedema, and suppressed renin aldosterone system due to unsupervised salt administration

This paper describes an infant with gastroenteritis, who developed hypertension and oedema after administration of inaccurately prepared oral glucose salt solution. The renin aldosterone system was suppressed in this child and it was suggested that this may be a factor in the development of hypernatraemia when abnormal water losses occur in infants fed on hyperosmolar feeds. Unless salt can be given accurately in small amounts it may be safer to advise feeds of glucose only in infants with mild diarrhoea.

Micropenis associated with testicular agenesis

This paper describes 2 male infants who were born with sever micropenis and in whom testicular tissue could not be identified at surgery. HCG stimulation in one infant was not followed by a rise in plasma testosterone. It was decided that both cases would be best raised as females, despite their male chromosomal sex.

Mental retardation, megaloblastic anaemia, methylmalonic aciduria and abnormal homocysteine metabolism due to an error in vitamin B12 metabolism

1. The case is described of a child with retarded physical and mental development, recurrent megaloblastic anaemia, methylmalonic aciduria and abnormal homocysteine metabolism resulting from an inborn error in the metabolism of cobalamins. She died at the age of 7 years. At autopsy there was pulmonary fibrosis and the brain showed lesions typical of those seen in subacute combined degeneration of the cord.

2. A metabolic abnormality was present which resulted in an inability to maintain normal tissue concentrations of the two coenzyme forms of vitamin B12, methylcobalamin and adenosylcobalamin. Lack of methylcobalamin led to deficient activity of N5-methyltetrahydrofolate-homocysteine methyltransferase with reduced ability to methylate homocysteine, and lack of adenosylcobalamin to deficient activity of methylmalonyl-CoA mutase, which accounted for the methylmalonic aciduria.

3. Analyses of total vitamin B12 and of individual cobalamins by a chromatobioautographic technique showed that in organs sampled at autopsy, the content of total vitamin B12 and of methylcobalamin, adenosylcobalamin and hydroxocobalamin were all greatly reduced. The plasma had a high normal total vitamin B12 content, but showed a gross abnormality in the distribution of individual cobalamins, methylcobalamin being decreased and adenosylcobalamin and hydroxocobalamin increased. The erythrocytes showed a reduction in cobalamins resembling that in the solid organs, though less severe.

4. The underlying abnormality in this patient appeared to be either a defect in cellular uptake of vitamin B12, or a defect in a metabolic pathway leading to the formation of a common precursor of methylcobalamin and adenosylcobalamin. Abnormalities in transcobalamins I and II, plasma factors involved in plasma transport and cellular uptake of vitamin B12, were excluded.

5. The clinical and biochemical findings in the patient are compared with those described in three patients previously reported, who had methylmalonic aciduria and homocystinuria, and who were in some respects similar to this patient. The present case is unusual in that previous examples of errors in cobalamin metabolism have not had megaloblastosis or neurological changes typical of vitamin B12 deficiency. It is also the first case in which direct estimations of individual cobalamins have been made.

Epidemic neuromyasthenia: outbreak among nurses at a children's hospital

Between August 1970 and January 1971 nearly 150 of the staff of a London teaching hospital were affected by an illness with features in common with what is currently known as epidemic neuromyasthenia. Symptomatology was protean, clinical findings minimal, relapses frequent, and results of laboratory investigations, including virological studies, were generally negative. Most of the patients were nurses. Care was taken to minimize anxiety and fear in a vulnerable population, and laboratory investigations were limited in number for this reason.