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The transport of L-proline was studied in brush-border membrane vesicles isolated from the kidneys of newborn rats. In contrast with the rapid initial uptake with an ‘overshoot’ observed in adult vesicles, uptake by the newborn vesicle was slow, showed no ‘overshoot’, and proline continued to accumulate at a time when the adult vesicle had already equilibrated. L-Proline transport in the newborn rat occurs by Na+-dependent and independent mechanisms. There appeared to be essentially no uptake by anti-luminal vesicles isolated from newborn rat kidney. These observations may help to explain the prolinuria that occurs in the newborn animal.

The recent developments in cofactor therapy of inherited biochemical disease has awakened interest in biotin as a therapeutic agent. This review briefly details the physiological and biochemical aspects of human biotin metabolism. The role of biotin in therapy of human disease is critically examined and the relevant literature extensively reviewed. It is our hope that this review will stimulate further clinical interest in the treatment of biotin-responsive human disorders.

3-Methylglutaconic aciduria has been found in two distinct syndromes. In one there is deficient activity of 3-methylglutaconyl coenzyme A hydratase, and the only clinical manifestation observed has been retardation of speech development. In the other, which includes a majority of the patients studied, we document that the activity of this enzyme in fibroblast extracts is normal. The phenotype of this disorder is one of profound neurological impairment with retarded psychomotor development, hypotonicity and/or spasticity, convulsions or EEG abnormalities, and sensorineural changes in the eye and ear.