Promotion of oxidative stress in kidney of rats loaded with cystine dimethyl ester.

Cystinosis is a systemic genetic disease caused by a lysosomal transport deficiency accumulating cystine in most tissues. Although tissue damage might depend on cystine accumulation, the mechanisms of tissue damage are not fully understood. Studies performed in fibroblasts of cystinotic patients and in kidney cells loaded with cystine dimethyl ester (CDME) suggest that apoptosis is enhanced in this disease. Considering that oxidative stress is a known apoptosis inducer, our main objective was to investigate the effects of CDME loading on several parameters of oxidative stress in the kidney of young rats. Animals were injected twice a day with 1.6 micromol/g body weight CDME and/or 0.26 micromol/g body weight cysteamine (CSH) from the 16th to the 20th postpartum day and killed after 1 or 12 h. CDME induced lipoperoxidation and protein carbonylation and stimulated superoxide dismutase, glutathione peroxidase (GPx), and catalase activities, probably through the formation of superoxide anions, hydrogen peroxide, and hydroxyl free radicals. Coadministration of CSH, the drug used to treat cystinotic patients, prevented, at least in part, those effects, possibly acting as a scavenger of free radicals. These results suggest that the induction of oxidative stress might be one of the mechanisms leading to tissue damage in cystinotic patients.

Early occurrence of end-stage renal disease in a patient with infantile nephropathic cystinosis.

We report the case of a patient with infantile nephropathic cystinosis who required renal transplantation at age 30 months. Exhaustive evaluation did not identify a cause of progressive renal failure other than cystinosis. The patient's genetic lesion was allelic with those of other patients with cystinosis; fusion of this patient's fibroblasts with fibroblasts from another patient with infantile nephropathic cystinosis did not demonstrate complementation of the biochemical defect.

Endocrine studies in cystinosis: compensated primary hypothyroidism.

Children with nephropathic cystinosis exhibit marked growth retardation. Improved medical management and renal transplantation have increased their life expectancy beyond the second decade. We have studied endocrine function in seven patients with cystinosis and reviewed autopsy findings of four patients and medical records of 24 others. One 10-year-old boy was overtly hypothyroid. The six other patients had normal studies of peripheral thyroid function but two had borderline and two had frankly elevated serum TSH levels. Stimulation tests of cortisol and growth hormone secretion and basal levels of serum NSILA-s were normal. Postmortem histology of the thyroid glands revealed extensive destruction and infiltration of the epithelium with cystine crystals. Despite the presence of cystine crystals in other endocrine tissues, there was no destruction of epithelium in glands other than in the thyroid. We conclude that in nephropathic cystinosis "compensated" primary hypothyroidism occurs frequently and early and may be diagnosed by measurement of serum TSH concentrations.