Lysine transport in human kidney: evidence for two systems

Experiments with slices of human kidney cortex from two control subjects demonstrated two distinct transport systems for lysine (alpha and beta) which differ greatly in affinity and capacity. Both systems were found in kidney from two patients with cystinuria. Studies with rat kidney confirmed these findings. These experiments defined only a single transport system for cystine in kidney from both control and cystinuric subjects.

Intestinal transport of cystine and cysteine in man: evidence for separate mechanisms

Cystine and cysteine are transported by energy-dependent, mediated processes in human gut. When either of these amino acids is transported, only cysteine is recovered intracellularly, indicating that cystine is reduced to cysteine after achieving an intracellular location. In contrast to results with cystine, cysteine uptake is not defective in gut from cystinuric patients, nor do lysine and arginine compete with cysteine for transport. It is, therefore, concluded that cystine and cysteine are transported by different mechanisms, and that only the cystine transport mechanism is defective in cystinuria.

Electrophoretic heterogeneity of mammalian galactose dehydrogenase

Electrophoretically distinct forms of galactose dehydrogenase were demonstrated in various tissues of the rat. Phylogenetic comparisons revealed considerable variation with species in mammalian liver zymograms; virtually no activity was demonstrable in fish, pigeon, and frog liver. Ontogenetic studies of the rat revealed sequential appearance of liver isoenzymes.

Galactose conversion to D-xylulose: an alternate route of galactose metabolism

Galactose dehydrogenase, a soluble enzyme of the mammalian liver, catalyzes the conversion of galactose to galactonic acid. This reaction, together with the subsequent formation of 3-ketogalactonic acid which can be decarboxylated to yield d-xylulose, is a newly discovered pathway for the metabolism of galactosee. This pathway may account for the oxidation of galactose observed in pathients with galactosemia.

Cystinuria: biochemical evidence for three genetically distinct diseases

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Oxidation of Carbon-14 Labeled Galactose by Subjects with Congenital Galactosemia

Galactose-1-C(14) oxidation was studied in eight individuals with congenital galactosemia. Although two of these subjects fulfilled the usual diagnostic criteria for this disorder, they oxidized the intravenously administered sugar to C(14)O(2) in a nearly normal fashion.

Congenital Deformity of the Arm (Hemiectromelia), with total absence of Hand and Rudimentary Radius and Ulna

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