Defective Uptake of Basic Amino Acids and l-Cystine by Intestinal Mucosa of Patients with Cystinuria *

Transport of Neutral and Dibasic Amino Acids by Human Leukocytes: Absence of Defect in Cystinuria*

“…Recent in vitro studies have demonstrated defective transport of lysine and arginine by human gut and kidney in cystinuria (7)(8)(9). Cystine uptake was also defective in intestinal mucosa (8,9) but, surprisingly, not in kidney cortex from cystinuric subjects (7).…”

“…Cystine uptake was also defective in intestinal mucosa (8,9) but, surprisingly, not in kidney cortex from cystinuric subjects (7). To characterize the transport systems for the dibasic amino acids and cystine in a third human tissue and to determine if defects in amino acid transport exist in tissues other than gut and kidney, the present studies with isolated peripheral leukocytes were undertaken.…”

Transport and Intracellular Fate of Cysteine-35S in Leukocytes from Normal Subjects and Patients with Cystinosis

“…Regardless of the cause of the decrease in specific activity, the experimental results mean that the true distribution ratio of cysteine is greater than the value simply determined by the ratio of intracellular to extracellular radioactivity in cysteine- 35 S. Since the decrease in intracellular specific activity was approximately the same in the types of leukocytes studied, a comparison between these groups remains valid. This may not be true, however, in other instances in which distribution ratios were compared on the basis of radioactivity alone [11,17,21,29].…”

“…In cystinuria, such a difference has been taken as evidence for an altered transport mechanism [11,17,26,29]. The interpretation of such data in these studies, however, was complicated by the high initial content of cystine in the cystinotic cells.…”

“…The cystine is these children [4], suggested a defect in the transport thought to cause both the renal tubular defects of the of cyst(e)ine (cystine and/or cysteine) in cystinotic Fanconi syndrome which appear during the first year of cells, analogous to the apparent defect in cystine translife, and the progressive renal glomerular damage which port in cells of the renal tubules in the otherwise unleads to death of affected children [12,20]. Careful related disease, cystinuria [11,17,26,29]. The lack of studies of postmortem tissue from these patients have suitable tissue from infants and small children with revealed normal activity of all enzymes tested, which this disease has been a major obstacle to definitive included most of those known to be necessary for cys-studies of transport.…”