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Biomedical subjects

A de Vries

Publications and source records attributed to A de Vries.

At least 91 records · Page 5Linked to original sources
PubMed1979

Inborn hypouricemia due to isolated renal tubular defect.

Inborn hypouricemia due to isolated renal tubular defect is a rare disorder. Thus far eight documented families with this condition have been reported. In reviewing the data on these families, hyperuricosuria was found to be a constant associate of the hypouricemia, and hypercalciuria, mainly of the absorptive type, was frequently associated. Urolithiasis appears to be common. The mode of inheritance of this hypouricemia was autosomal, probably recessive. The magnitude of renal urate clearance and the effects on it of probenecid and pyrazinamide suggest the inborn renal hypouricemia to be of two types, due to defective re-secretory tubular urate reabsorption and to total defective tubular urate reabsorption. The question of the renal tubular abnormality for urate transport being the primary defect or secondary to an abnormal metabolite is discussed.

Adult↗
PubMed1978

Urine xanthine oxidase activity in urinary tract infection.

Xanthine oxidase (XO) activity was found to be negligible in sterile human urines (less than 480 units, as presently defined, per litre). Significant XO activity was found in all urines containing more than 10(5) bacteria/ml, except for urines infected with Staphylococcus aureus, in which XO activity ranged from 347 to 714 units per litre. Plasma XO is not transferred to the urine, as demonstrated by the negligible XO activity found in sterile urines from patients with raised plasma XO activity. Determination of urinary XO activity is a suitable procedure for the detection of urinary tract infection.

Bacteriuria↗
PubMed1978

Overproduction disease in man due to enzyme feedback resistance mutation. Purine overproduction in gout due to excessive activity of mutant feedback-resistant phosphoribosylpyrophosphate synthetase.

Physiologically superactive phosphoribosylpyrophosphate (PRPP) synthetase, due to feedback resistance mutation, was found in a family with excessive purine production, gout and uric acid lithiasis. The superactivity of the mutant enzyme was manifest in the propositus' erythrocytes and cultured fibroblasts, in increased generation, content and metabolic availability of PRPP, leading in the fibroblasts to acceleration of the rate of purine synthesis de novo. One of the propositus' two siblings was similarly affected, but the propositus' father, his second brother and four sons, were all clinically and biochemically normal. The mother was clinically normal and normouricemic, but hyperuricosuric. Cultured fibroblasts from her skin exhibited variability in PRPP content and availability and in the rate of purine synthesis de novo. The mother's cultures were found to contain a mosaicism of two cell populations, one with normal and the other with mutant PRPP synthetase, indicating an X-linked pattern of inheritance of the PRPP synthetase abnormality in this gouty family.

Adolescent↗
PubMed1977

Superactivity of phosphoribosylpyrophosphate synthetase, due to feedback resistance, causing purine overproduction and gout.

A mutant feedback-resistant, physiologically superactive, phosphoribosylpyrophosphate (PP-ribose-P) synthetase was found in a family with purine overproduction, gout and uric acid lithiasis. In haemolysates and cultured fibroblasts from the propositus, the mutant enzyme exhibited resistance to feedback inhibition by normal cell constituents, such as ADP and GDP; normal affinity to substrates and to activator Pi was demonstrated in the haemolysate. In both erythrocytes and cultured fibroblasts, the superactivity of the mutant enzyme was manifest in increased PP-ribose-P content and availability for nucleotide synthesis, leading to an acceleration of the rate of purine synthesis de novo in the fibroblasts. The enzyme abnormality and the resulting increase in PP-ribose-P content and generation were demonstrated in the erythrocytes of one of the propositus' two siblings who was similarly affected but not in the propositus' father, his second brother and four sons, who were all clinically and biochemically normal, nor in the erythrocytes of the clinically normal hyperuricosuric mother. However, cultured fibroblasts from her skin exhibited variability in PP-ribose-P content and availability and in the rate of purine synthesis de novo, these parameters being increased in most cultures. The mother's fibroblast cultures were found to contain two cell populations, one with normal and the other with mutant PP-ribose-P synthetase, indicating an X-linked pattern of inheritance of the synthetase superactivity in this gouty family.

Adolescent↗
PubMed1977

Implications of disorders of purine metabolism for the kidney and the urinary tract.

The spectrum of kidney and urinary tract disorders related to purines comprises acute hyperuricosuric nephropathy, chronic urate nephropathy and urolithiasis. Two factors in the development of acute hyperuricosuric nephropathy are increased uric acid concentration and low pH in the tubular fluid. Chronic urate nephropathy still possess several problems: incidence (although this seems to be decreasing, presumably owing to effective prevention), the source of interstitial urate, the cause of the interstitial deposition of urate, and the role of urate deposits in the pathogenesis of the interstitial nephropathy. The relation of the experimental nephropathy to the pathogenesis of chronic urate nephropathy in the human is not yet clear but a model is proposed according to which interstitial urate derives from two sources: hyperuricaemic plasma and hyperuricosuric tubular fluid. Urolithiasis related to purines leads to uric acid-urate stones, xanthine stones, 2,8-dihydroxyadenine stones, iatrogenic xanthine and oxipurinol stones, and possibly calcium stones. Pathogenetic factors in uric acid lithiasis are hyperuricosuria (whether due to an inborn enzyme abnormality or of unknown aetiology) and low urinary pH; oliguria is a contributory factor. There remain several open questions about uric acid lithiasis: incidence, the shift of its location from lower to upper urinary tract, the interplay of pathogenetic factors, and the role of compounds which inhibit crystallization.

Adenine Phosphoribosyltransferase↗