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At least 829 records · Page 46Linked to original sources
PubMed1981

Chronic progressive renal failure. Rate of progression monitored by change of serum creatinine concentration.

The rise of serum creatinine levels during were renal failure progressing to end-stage renal disease was studied in 30 children. In 20 patients the rise was a steady one and followed a mathematical model, best expressed by the regression line calculated from reciprocal values. Ten patients had widely fluctuating values that did not fit any of the available mathematical models; however, in three patients, the curve had two slopes. The initially slow rate of progression changed to a more rapid, steady rise when a creatinine level of 2 to 3 mg/dL was reached. Therefore, in 23 of 30 patients, the time at which a serum creatinine values of 10 mg/dL would be reached could be predicted with acceptable accuracy based on this calculation or using a graphic plot. In the terminal phase of renal failure, the serum creatinine value progressed from 7 to 10 mg/dL in less than four months in 80% of the cases.

Adolescent↗
PubMed1990

Mechanism of cystine reaccumulation by cystinotic fibroblasts in vitro.

It is well established that when cystine-depleted cystinotic cells are cultured in cystine-containing medium, they reaccumulate cystine within their lysosomes more rapidly than when cultured in cystine-free medium. This has been a puzzling result, since the lysosome membrane of cystinotic cells is impermeable to cystine. To probe the mechanism of cystine reaccumulation, we have measured reaccumulation in the presence of colchicine, an inhibitor of pinocytosis, or of glutamate, a competitive inhibitor of cystine transport into human fibroblasts. Colchicine had no effect, thus eliminating pinocytosis as a putative mechanism for cystine translocation from the culture medium to the lysosomes. Glutamate, however, strongly inhibited cystine reaccumulation. It is concluded that the true mechanism is as follows. 1. Exogenous cystine crosses the plasma membrane on the cystine-glutamate porter. 2. Cystine is reduced in the cytoplasm by GSH. 3. The cysteine that is generated enters the lysosome, where it becomes cystine by participating in the reduction of cystine residues during intralysosomal proteolysis, or by autoxidation.

Biological Transport↗
PubMed1990

Effect of cystine loading and cystine dimethylester on renal brushborder membrane transport.

The effect of loading renal tubule cells with cystine was studied by incubating them with cystine dimethylester. Proline uptake into brushborder membrane vesicles isolated from the cystine loaded cells was not different from that observed into brushborder vesicles isolated from tubules incubated in buffer alone. Incubating brushborder membranes with 2 mM cystine dimethylester for 10 minutes reduced the uptake of proline by 27% after 15 seconds of incubation and by 21% after 60 seconds of incubation. There was no effect after 20 minutes of incubation. Pre-incubating brushborder membrane vesicles with cystine dimethylester had no statistically significant effect on the affinity of proline for the carrier, but did reduce the maximal rate of proline uptake by 49%.

Animals↗
PubMed1980

Cystinotic and normal fibroblasts: differential susceptibility to cysteine toxicity in vitro.

Extracellular cysteine concentrations between 0.5 and 2.5 mM resulted in death of normal but not cystinotic cells grown in Eagle's minimal essential medium containing supplemental fetal bovine serum and antibiotics. Differential cell survival was determined by viable cell counting using Trypan Blue dye exclusion. In cocultivation experiments of [3H]thymidine-labelled cystinotic fibroblasts with nonradioactive normal fibroblasts, autoradiography confirmed the selective survival of cystinotic cells in medium containing 1 mM cysteine. At this concentration of 1 mM cysteine, intracellular cystine content increased slightly in surviving normal cells but not in cystinotic cells, which normally contain a high level of intracellular cystine. This comparative resistance of cystinotic fibroblasts to elevated extracellular cysteine concentrations forms the basis for an in vitro selective system for these mutant human cells. Further exploration of this resistance phenomenon may well expand the understanding of the molecular defect in cystinotic cells.

Cell Count↗
PubMed2003

Lip hypertrophy secondary to cyclosporin treatment.

Gingival hypertrophy is a well-documented side effect of cyclosporin therapy, but severe lip enlargement is less frequently recognised. This can lead to poor body image, low self-esteem and non-compliance, especially in the older childhood and adolescent age groups. We describe two paediatric renal transplant recipients who had marked lip hypertrophy as a consequence of cyclosporin (Neoral) treatment. On changing the immunosuppression to tacrolimus (Prograf), this resolved. We recommend that a change in immunosuppressant therapy be considered in children with significant changes to facial appearance.

Child↗
PubMed2006

Glutathione depletion and increased apoptosis rate in human cystinotic proximal tubular cells.

We have determined levels of glutathione (GSH), ATP, mitochondrial complex activity and apoptosis rate in proximal tubular cells (PTCs) exfoliated from urine in cystinotic (n=9) and control (n=9) children. Intracellular GSH was significantly depleted in cystinotic PTCs compared with controls (6.8 nmol GSH/mg protein vs 11.8 nmol GSH/mg protein; P<0.001), but there were no significant differences in mitochondrial complex activities or ATP levels under basal conditions. Cystinotic PTCs showed significantly increased apoptosis rate. After PTCs had been stressed by hypoxia, there was further depletion of GSH in cystinotic and control PTCs (2.4 nmol GSH/mg protein vs 7.2 nmol GSH/mg protein; P<0.001). Hypoxic stress led to increased complex I and complex IV activities in control but not in cystinotic PTCs. ATP levels were significantly reduced in cystinotic PTCs after hypoxic stress (12.2 nmol/mg protein vs 26.9 nmol/mg protein; P<0.001). GSH depletion occurs in this in vitro model of cystinotic PTCs, is exaggerated by hypoxic stress and may contribute to reduced ATP and failure to increase complex I/IV activities. Apoptotic rate is also increased, and these mechanisms may contribute to cellular dysfunction in cultured, human cystinotic PTCs.

Apoptosis↗
PubMed1983

Handling of L-[35S]cystine by cysteamine-pretreated cystinotic and normal fibroblasts.

In short incubations with 0.1 mM L-[35S]cystine in phosphate-buffered saline medium, and long incubations with label in complete minimum Eagle's medium with Earle salts, cystine-depleted cystinotic cells reaccumulate labeled cystine more rapidly than pretreated normal cells. Cysteamine pretreatment of both normal and cystinotic cells resulted in an initial increased conversion of exogenous cystine to intracellular cysteine. In 24-h incubations in complete medium, cysteamine-pretreated cells showed enhanced conversion of 0.1 mM L-[35S]cystine to cysteine and reduced glutathione. Addition of cycloheximide to the incubation media decreased the incorporation of 35S into cellular protein by more than 90% but did not affect the accumulation of intracellular labeled cystine in cystinotic cells. Therefore, the incorporation and release of cystine from protein is not an obligatory source of accumulated cystine and we speculate that there may be early extralysosomal entrapment of cystine in cystinotic cells.

Cell Line↗