Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CYSTINOSIS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39Linked to original sources
PubMed1990

Depletion of cystine in cystinotic fibroblasts by homocysteine. Synergism of cysteamine with various reducing agents in depletion of cystine from cystinotic fibroblasts.

The present study shows that homocysteine depleted cystine from cystinotic fibroblasts in vitro. No toxic effects were noted as judged by morphology and growth patterns. Efflux of radioactivity from cystinotic cells prelabeled with [35S]cystine was greater in homocysteine-treated cystinotic cells than in untreated controls. This radioactivity was found, by high voltage electrophoresis separation of effluxed products, to consist mainly of [35S]cystine, along with smaller amounts of [35S]homocysteine-cysteine mixed disulfide. When homocysteine and cysteamine were presented together to cystinotic cells at dose levels individually ineffective in removing cystine from these cells, a marked synergistic effect was observed and cystine content fell to 10% of that seen in untreated cystinotic fibroblasts. Similarly, synergistic effects of cystine depletion from cystinotic cells were demonstrated when cells were treated with a combination of cysteamine and dithiothreitol or glutathione. Incubation of cystinotic cells with homocysteine, dithiothreitol, or cysteamine in combination with vitamin C did not yield synergistic effects. The above findings suggest a novel way to probe metabolic processes in these mutant cells. Exploration of these synergistic effects may lead to more efficacious therapeutic protocols for cystinosis.

Ascorbic Acid↗
PubMed1977

Activities of acid hydrolases in fibroblasts from normal and cystinotic children.

A study of the lysosomal hydrolases bete-galactosidase, beta-glucuronidase, N-acetyl-beta-D-glucosaminidase, and arylsulphatases A and B has been carried out on fibroblasts cultured from seven patients with cystinosis and eight control subjects. beta-Galactosidase activity was found to be consistently lower in cells derived from cystinotics, while the other enzymes studied showed no significant differences between normals and cystinotics.

Arylsulfatases↗
PubMed1984

Cystine accumulation and clearance in normal and cystinotic fibroblasts exposed to cystine dimethyl ester.

Exposure of cultured skin fibroblasts of normals and cystinotic patients to 0.5 mmol/l[35S]cystine dimethyl ester for 30 min resulted in an accumulation of cystine in excess to that naturally occurring in cystinotic skin fibroblasts. These equal levels of cystine accumulation achieved in both cystinotic and normal cells, permitted comparative experiments to look for differences in cystine disposal between normal and cystinotic cells. Cystinotic fibroblasts demonstrated very low cystine clearance with a lower ratio of cysteine-N-ethylmaleimide to cystine than normal. The results on cystinotic fibroblasts are consistent with those observed in leucocytes, suggesting that fibroblasts can be useful in further studies to elucidate the clearance defect of cystine in cystinosis as well as its potential in antenatal diagnosis.

Cells, Cultured↗
PubMed1988

Urinary excretion of aldosterone metabolite Kelly-M1 in patients with adrenal dysfunction.

Using tetrahydroaldosterone antibody a radioimmunoassay was developed to measure substance Kelly-M1 (K-M1) in human urine. The normal values were lower than observed by Kelly et al. who discovered the catabolite after giving large doses of exogenous aldosterone. While in essential hypertension the excretion of K-M1 was predominantly within the normal range, elevated values were found in most cases of 21-hydroxylase deficiency, both the simple virilizing and salt losing form, primary aldosteronism, renal hypertension and cystinosis. Our findings suggest that K-M1 may be formed from 21-deoxyaldosterone and/or by microbial intervention from aldosterone or its metabolites.

Adrenal Gland Diseases↗
PubMed1987

Effect of cystine dimethylester on renal solute handling and isolated renal tubule transport in the rat: a new model of the Fanconi syndrome.

The effect of cystine dimethylester on the renal handling of phosphate, glucose, alpha-amino nitrogen, amino acids, and protein in vivo and on the uptake of lysine, glycine, taurine, and alpha-methyl glucoside by isolated renal tubules in vitro was studied in adult male rats. Parenteral administration of 400 mumol twice a day for four days of cystine dimethylester led to an increased urine volume, and excretion of phosphate, glucose, alpha-amino nitrogen, and the amino acids glutamine, proline, alanine, 1/2 cystine, ornithine, lysine, histidine, and glycine. Cystine dimethylester treatment did not affect the creatine clearance nor were any renal anatomic abnormalities noted. Intracellular cysteine, but not cystine, was increased in the kidney after the four days of treatment. Pre-incubation of isolated renal tubules with 2 mmol/L cystine dimethylester for ten minutes markedly inhibited the uptake of 0.025 mmol/L lysine, 0.1 mmol/L glycine, 0.01 mmol/L taurine, and 2 mmol/L alpha-methyl glucoside. Incubation with 2 mmol/L cystine dimethylester for ten minutes did not affect the ability of the renal tubule to exclude trypan blue dye, although longer incubation times did lead to significant staining. The intracellular cystine concentration of the renal tubule did rise significantly after incubation with cystine dimethylester, a biochemical correlate of the human disease cystinosis. These studies indicate that cystine dimethylester can induce an experimental form of the Fanconi syndrome both in vivo and in vitro and offers a new model for investigating the mechanisms underlying this enigmatic disorder.

Amino Acids↗
PubMed1989

The effects of decreased growth temperature on the cystine content of cystinotic fibroblasts.

Cystinotic fibroblasts transferred from 37 degrees C to 28 degrees C accumulated additional cystine over the period from 4 to 7 days of incubation at 28 degrees C, after which the additional cystine was lost; warming (to 37 degrees C) of cells with elevated cystine stores led to rapid cystine loss. These results, taken together with previously published data showing cystine release from cystinotic fibroblasts incubated at above-normal temperature, are interpreted as indicating the presence in the cystinotic fibroblast lysosome membrane of a cystine-porter whose efficacy is increased by an increase in membrane fluidity. This porter may be the residual activity of the cystine porter that is known to be deficient in cystinosis, or it may be a second as yet unrecognized porter. It is further proposed that this porter is responsible for the presumed efflux of cystine from cystinotic lysosomes.

Cell Division↗
PubMed2004

Glutathione precursors replenish decreased glutathione pool in cystinotic cell lines.

Cystinosis is an inherited disorder due to mutations in the CTNS gene which encodes cystinosin, a lysosomal transmembrane protein involved in cystine export to the cytosol. Both accumulation of cystine in the lysosome and decreased cystine in the cytosol may participate in the pathogenic mechanism underlying the disease. We observed that cystinotic cell lines have moderate decrease of glutathione content during exponential growth phase. This resulted in increased solicitation of oxidative defences of the cell denoted by concurrent superoxide dismutase induction, although without major oxidative insult under our experimental conditions. Finally, decreased glutathione content in cystinotic cell lines could be counterbalanced by a series of exogenous precursors of cysteine, denoting that lysosomal cystine export is a natural source of cellular cysteine in the studied cell lines.

Adolescent↗
PubMed1976

Effect of selenium compounds on selenium content, growth and 35S-cystine metabolism of skin fibroblasts from normal and cystinotic individuals.

Kidney samples from children with the inborn metabolic disease cystinosis contain 4 times more selenium (Se) than do kidney samples from normal individuals (p = 0.1). However, when cultured skin fibroblasts from cystinotic patients and normal control individuals are incubated in Se-D,L-methionine, Se-D,L-cystine, Se-cystamine X HCl, Se-urea, selenite or in medium without added selenium, only the cystinotic fibroblasts grown in Se-urea or selenite (SeO3=) contain more selenium than do the corresponding normal cells (p less than 0.05). In both types of cultured fibroblasts, the order of descending toxicity per ppm selenium is: Se-urea greater than Se-cystamine greater than Se-cystine greater than or equal to SeO3= much greater than Se-methionine. High (apparently toxic) concentrations of Se-urea and Se-cystamine lower the elevated intracellular free (nonprotein) cystine content of cystinotic fibroblasts to less than 60% of control values; at lower concentrations, these compounds raise the cystine content of these cells to over 140% of control values. Appropriate concentrations of SeO3=, Se-cystine and Se-methionine also elevate the free cystine content of the cystinotic cells. During a 75 minute incubation in 35S-cystine, the incorporation of 35S into the acid precipitable (protein) fraction of both cell types is significantly inhibited by Se-cystamine (approximately 55% control; p less than 0.05). The incorporation of 35S-cystine into glutathione is inhibited by Se-cystine (approximately 40% control) in both fibroblast types (p less than 0.05). In cystinotic cells, Se-cystamine significantly reduces incorporation of 35S-cystine into the cystine pool (40% control) as does SeO3= (67% control; p less than 0.05). Protein and glutathione synthesis in cystinotic fibroblasts are more strongly inhibited by Se-cystine and SeO3=, respectively, than in normal fibroblasts (p less than 0.05). These studies demonstrate that selenium compounds exhibit a different sequence of toxicity in fibroblasts than in the intact animal and that some previously unreported metabolic effects (i.e. inhibition of glutathione synthesis) may contribute to their toxicity.

Amino Acids↗
PubMed2003

At the acidic edge: emerging functions for lysosomal membrane proteins.

It has recently become clear that lysosomes have more complex functions than simply being the end-point on a degradative pathway. Similarly, it is now emerging that there are interesting functions for the limiting membranes around these organelles and their associated proteins. Although it has been known for several decades that the lysosomal membrane contains several highly N-glycosylated proteins, including the lysosome-associated membrane proteins LAMP-1 and LAMP-2 and lysosomal integral membrane protein-2/lysosomal membrane glycoprotein-85 (LIMP-2/LGP85), specific functions of these proteins have only recently begun to be recognized. Although the normal functions of LAMP-1 can be substituted by the structurally related LAMP-2, LAMP-2 itself has more specific tasks. Knockout of LAMP-2 in mice has revealed roles for LAMP-2 in lysosomal enzyme targeting, autophagy and lysosomal biogenesis. LAMP-2 deficiency in humans leads to Danon disease, a fatal cardiomyopathy and myopathy. Furthermore, there is evidence that LAMP-2 functions in chaperone-mediated autophagy. LIMP-2/LGP85 also seems to have specific functions in maintaining endosomal transport and lysosomal biogenesis. The pivotal function of lysosomal membrane proteins is also highlighted by the recent identification of disease-causing mutations in cystine and sialic acid transporter proteins, leading to nephropathic cystinosis and Salla disease.

Animals↗
PubMed2000

Lysosomal transport disorders.

In the group of lysosomal storage diseases, transport disorders occupy a special place because they represent rare examples of inborn errors of metabolism caused by a defect of an intracellular membrane transporter. In particular, two disorders are caused by a proven defect in carrier-mediated transport of metabolites: cystinosis and the group of sialic acid storage disorders (SASD). The recent identification of the gene mutations for both disorders will improve patient diagnosis and shed light on new physiological mechanisms of intracellular trafficking.

Animals↗
PubMed2003

Mutational spectrum of the CTNS gene in Italy.

Classic nephropathic or infantile cystinosis (NC) is an autosomal recessive disorder; the gene coding for the integral membrane protein cystinosin, which is responsible for membrane transport of cystine (CTNS), was cloned. Mutation analysis of the CTNS gene of Caucasian patients revealed a common 57-kb deletion, and several other mutations spread throughout the entire gene. In the present study, we report the CTNS mutations identified in 42 of 46 Italian families with NC. The percentage of mutations characterized in this study is 86%. The mutational spectrum of the Italian population is different from that of populations of North European origin: the 57-kb deletion is present in a lower percentage, while the splicing mutations represent 30% of mutation detected in our sample. In all, six novel mutations have been identified, and the origin of one recurrent mutation has been traced.

Adolescent↗
PubMed1981

The effect of chloroquine on the metabolism of [35S]cystine in normal and cystinotic human skin fibroblasts.

The present study concerns the effect of the lysosomotropic drug chloroquine on the uptake and metabolism of [35S]cystine in vitro by normal human fibroblasts and those from patients suffering from the lysosomal storage disease cystinosis. When the cells were cultured with [35S]cystine for periods in excess of 4 h, it was found that chloroquine considerably increased (up to 30-fold) the labelling of the intracellular cystine pool in cystinotic cells, with no increase or a much smaller increase in normal cells. For this effect chloroquine had an optimum concentration of 20 microM, with a small effect still being noticeable at 1 microM. A quinoline analogue, 4-(dimethylaminoethylamino)-7-iodoquinoline, had a similar effect to chloroquine. However, NH4Cl at concentrations of between 100 microM and 50 mM showed either no effect (at the lower concentrations) or a depression of intracellular cystine labelling (at the higher concentrations). The differences between the effects of the quinolines on cystinotic acid normal cells were not due to differences in total cell uptake of drug.

Aminoquinolines↗
PubMed1986

Impaired clearance of free cystine from lysosome-enriched granular fractions of I-cell-disease fibroblasts.

Cultured fibroblasts from patients with I-cell disease (mucolipidosis II) accumulate excessive amounts of free cystine, similarly to cells from patients with nephropathic cystinosis, a disorder of lysosomal cystine transport. To clarify whether the intralysosomal accumulation of cystine in I-cell-disease fibroblasts was due to a defective disposal mechanism, we measured the rates of clearance of free [35S]cystine from intact normal, cystinotic and I-cell-disease fibroblasts. Loss of radioactivity from the two mutant cell types occurred slowly (t 1/2 = 500 min) compared with the rapid loss from normal cells (t 1/2 = 40 min). Lysosome-rich granular fractions isolated from three different cystine-loaded normal, cystinotic and I-cell-disease fibroblast strains were similarly examined for non-radioactive cystine egress. Normal granular fractions lost cystine rapidly (mean t 1/2 = 43 min), whereas cystinotic granular fractions did not lose any cystine (mean t 1/2 = infinity). I-cell-disease granular fractions displayed prolonged half-times for cystine disposal (mean = 108 min), suggesting that I-cell-disease fibroblasts, like cystinotic cells, possess a defective carrier mechanism for cystine transport.

Cells, Cultured↗
PubMed1986

Disulphide reduction in lysosomes. The role of cysteine.

Published evidence indicates that cystine-containing proteins have their disulphide bonds reduced during proteolysis in lysosomes. However, the intralysosomal accumulation of cystine in the cells of patients with cystinosis has been seen as evidence that protein cystine residues are not reduced. The data are reconcilable and fully in harmony if it is postulated that cysteine from the cytoplasm is the physiological reducing agent.

Cysteine↗
PubMed1995

[1H-NMR spectroscopic study of cysteamine eyedrops].

BACKGROUND: The efficiency of cysteamine eye drops in the treatment of cystinosis has been demonstrated in several studies: Corneal cystine crystals can be removed by topical cysteamine. Cysteamie 0.5% eye drops were superior to a 0.1% solution. It is not clear how fast cysteamine is oxidized to cystamine under the influence of atmospheric oxygen. MATERIAL AND METHODS: Samples of a new bottled cysteamine 0.5% solution were analysed 1H-NMR-spectroscopically over a period of several weeks (AM 400/WB-NMR-instrument, Bruker/Karlsruhe; 400.15 MHz). Samples bottled in an argon atmosphere were compared to samples bottled without inert gas. Definite samples were opened four times a day (A). The remainder of the samples was stored closed (B). RESULTS: In sample A a 1:1 weight ratio between cysteamine and cystamine was reached after 38 days. In samples B cysteamine was not oxidized to cystamine. The initial amount of cystamine was something lower in samples with argon, but argon could not prevent the decrease of the cysteamine concentration in sample A. CONCLUSIONS: The preparation of cysteamine solution in an argon atmosphere is useful. One bottle can be used for about one week, if less than 10% of the oxidation product cystamine is accepted.

Cornea↗
PubMed1977

Cystinotic fibroblasts accumulate cystine from intracellular protein degradation.

Fibroblasts derived from patients with cystinosis, an autosomal recessive condition, accumulate the disulfide amino acid cystine within lysosomes. The metabolic defect leading to the cystine accumulation and the source from which the cystine is derived are unknown. In this report we present data showing that cystine in these cells accumulates from the degradation of endogenous protein. This conclusion is based upon: (i) no demonstrable synthesis of cystine from serine; (ii) no difference in cystine reaccumulation between glutathione-depleted and non-glutathione-depleted cystinotic cells; (iii) recovery of labeled cystine only when the protein pool is labeled; (iv) reversible inhibition of cystine reaccumulation by known inhibitors of lysosomal protein degradation (chloroquine and NH4Cl).

Biodegradation, Environmental↗
PubMed1982

Cystine accumulation and loss in normal, heterozygous, and cystinotic fibroblasts.

Cystinotic fibroblasts contain approximately 100 times more cystine than do normal control fibroblasts. When cystinotic fibroblasts were placed in the presence of 30 mM cysteine-glutathione mixed disulfide (CSSG) for 24 hr, their cystine content increased about 3-fold. Similar treatment of normal fibroblasts and fibroblasts from patients heterozygous for cystinosis resulted in a 6- to 7-fold increase in cystine content. In all three cell types, the intracellular free cystine is located within lysosomes. When placed in cystine-free medium after 24 hr in CSSG-containing medium, the normal and heterozygous fibroblasts rapidly lost their lysosomal cystine (t 1/2 = 20 min), but the cystine content of the cystinotic cells remained stable for over 90 min. In contrast to the findings in intact fibroblasts, cystine loss could not be demonstrated from isolated, cystine-loaded lysosomes from any of the three cell types.

Cell Survival↗
PubMed2007

Pharmacokinetics of cysteamine bitartrate following gastrointestinal infusion.

AIMS: Although cysteamine was first used in the treatment of cystinosis in 1976 and approved by the FDA as cysteamine bitartrate (Cystagon) in 1994, surprisingly little pharmacological data are available for this compound. Cysteamine and its related drugs are currently being evaluated for the treatment of Huntington's and Parkinson's disease. The aim of te study was to understand the pharmacokinetics of cysteamine bitartrate following gastrointestinal infusion. METHOD: Cysteamine bitartrate was delivered through a naso-enteric catheter into the stomach (n = 8), small intestine (n = 8) and caecum (n = 4) of normal subjects. Plasma cysteamine concentrations were determined using LC-MS/MS. RESULTS: The rate and extent of drug absorption were assessed by comparing AUC(0, infinity), C(max) and t(max), among the gastrointestinal infusion sites. Total cysteamine exposure, expressed as area under the curve (AUC(0, infinity)) was greatest when the drug was infused into the small intestine (4331.3 +/- 1907.6 min x microM) followed by stomach (3901.9 +/- 1591.9 min x microM) and caecum (3141.4 +/- 1627.6 min x microM). Cysteamine infusion into the small intestine resulted in the most rapid rise to maximal plasma concentrations (t(max) = 21 +/- 0.56 min); t(max) was delayed to 50 +/- 26 min and 64 +/- 26 min after gastric and caecal infusion, respectively. The maximum cysteamine plasma concentration (C(max)) was reached after infusion of the drug into the small intestine (51 +/- 21 microM), which was higher than plasma C(max) concentrations after gastric (39 +/- 16 microM) and caecal infusion (23 +/- 15 microM). CONCLUSIONS: The pharmacokinetic data generated help extend our understanding of cysteamine.

Adult↗