Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cysteamine”

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 1,369 records · Page 76Linked to original sources

Detectability of pituitary PRL and GH by immunoassay is increased by thiols and suppressed by divalent cations.

The amount of pituitary PRL detected by RIA in extracts of tissue and of secretory granules was augmented by thiols or EDTA in the extractant, and diminished by divalent cations or cysteamine. GH was affected by thiols and cations similarly, but to a lesser extent, and was not influenced by EDTA or cysteamine. For full immunologic detection of tissue PRL and GH, thiol-dependent mechanisms appear to be required to unmask immunoreactive sites from the poorly immunoreactive oligomeric granule storage forms. Interpretation of studies which rely on measurement of tissue PRL and GH content by RIA, immunoprecipitation, or electrophoretic detection should be reassessed in light of these observations.

Animals↗

Stimulation of somatostatin release from median eminence tissue incubated in vitro by taurine and related amino acids.

To determine if the putative amino acid transmitter taurine could affect the release of somatostatin (SRIF) from median eminence fragments, median eminences were incubated in vitro in the presence of various concentrations of taurine and its precursors, hypotaurine, cysteamine, cysteic acid, and L-cysteine sulfinic acid. Taurine was effective in releasing SRIF at doses of 50 microM and higher. Surprisingly, cysteic acid was the most potent stimulant of SRIF release, with a minimal effective dose of 0.1 microM. Cysteamine was effective at a dose of 50 microM, hypotaurine was effective only at 200 microM, and cysteine sulfinic acid was ineffective in stimulating SRIF release at any of the doses tested. To determine if the effect of taurine was mediated by the dopaminergic system, the dopamine receptor blocker pimozide (1 microM) was added to the medium containing either taurine or cysteic acid. Pimozide did not prevent the stimulatory effect of the amino acids. In conclusion, these investigations suggest that taurine and related amino acids may be involved in SRIF release by a nondopaminergic pathway. In view of the high concentrations of taurine in the hypothalamus it must be considered a putative transmitter releasing SRIF.

Amino Acids↗

Protection against ionising radiation and synergism with thiols by zinc aspartate.

Pre-treatment with zinc aspartate protected mice against the lethal effects of radiation and raised the LD50 from 8 Gy to 12.2 Gy. Zinc chloride and zinc sulphate were clearly less active. The radioprotective effect of zinc aspartate was equivalent to cysteamine and slightly inferior to S,2-aminoethylisothiourea (AET). Zinc aspartate displayed a similar therapeutic index to the thiols but could be applied at an earlier time before irradiation. Synergistic effects occurred with the combined administration of zinc aspartate and thiols. By giving zinc aspartate with cysteamine, the LD50 was increased to 13.25 Gy and, by combining it in the optimal protocol with AET, to 17.3 Gy. The radioprotection by zinc and its synergism with thiols is explained by the stabilisation of thiols through the formation of zinc complexes.

Animals↗

Pulmonary dysfunction in adults with nephropathic cystinosis.

OBJECTIVE: To characterize the pulmonary dysfunction in patients with nephropathic cystinosis after renal transplantation. DESIGN: Cross-sectional analysis of consecutive adult patients. PATIENTS: Twelve adult, nephropathic cystinosis patients and 3 adult, ocular, nonnephropathic cystinosis patients admitted to the National Institutes of Health Clinical Center. RESULTS: The 12 nephropathic cystinosis patients (age range, 21 to 40 years) showed an extraparenchymal pattern of restrictive lung disease, with inspiratory and expiratory dysfunction. Specifically, the mean FVC was 58% of predicted, the mean FEV(1) was 57% of predicted, and the mean total lung capacity was 66% of predicted, while the mean residual volume was normal. Furthermore, the mean maximal inspiratory pressure for the eight patients tested was 40% of predicted, and the mean maximal expiratory pressure was 26% of predicted. Two patients died of respiratory insufficiency. All the patients had lived at least 17 years, while lacking compliant cystine-depleting therapy with oral cysteamine. Seven patients had a conical chest, restricting excursion, and 10 of the 12 patients had evidence of the myopathy that typifies late cystinosis. In fact, the severity of pulmonary disease correlated directly with the severity of myopathy in our group of 12 patients. In contrast, the lung parenchyma was essentially normal, as gauged by chest radiographs and CT scans of the lung. The three patients with nonnephropathic cystinosis displayed entirely normal pulmonary function. CONCLUSION: The distal myopathy characteristic of nephropathic cystinosis results in an extraparenchymal pattern of restrictive lung disease in adults who have not received long-term cystine depletion. Whether or not oral cysteamine therapy can prevent this complication remains to be determined.

Adult↗

Muramyl-peptide/gastrin conjugates as potential immunogens.

For a selective covalent linkage of muramyl-peptides with human-little-gastrin the maleimide-thiol reaction principle was adopted. For this purpose thiol-functionalized muramyl-peptide derivatives, i.e. N-acetyl-muramyl-alanyl-D-isoglutaminyl-cysteamine and N-acetyl-muramyl-alanyl-D-isoglutaminyl-N epsilon-palmitoyl-lysyl-cysteamine, were reacted with N alpha-maleoyl-beta-alanyl-[15-methoxinine]-human-little-g ast rin-I-[2-17]. The resulting gastrin conjugates were used in immunization experiments on rabbits and mice. Unexpectedly, these gastrin derivatives proved to be poorly immunogenic despite the built-in immunoadjuvanticity. The titers of the antipeptide antibodies as well as of the unspecific immunoglobulins were in the range of those of the control group.

Acetylmuramyl-Alanyl-Isoglutamine↗

Electrocatalytic oxidation and highly selective voltammetric determination of L-cysteine at the surface of a 1-[4-(ferrocenyl ethynyl)phenyl]-1-ethanone modified carbon paste electrode.

A carbon paste electrode (CPE) chemically modified with 1-[4-(ferrocenyl ethynyl)phenyl]-1-ethanone (4-FEPEMCPE) was employed to study the electrocatalytic oxidation of L-cysteine using cyclic voltammetry, differential pulse voltammetry and double potential step chronoamperometry as diagnostic techniques. The diffusion coefficient (D = 7.863 x 10(-6) cm2 s(-1)) of L-cysteine was also estimated using chronoamperometry. The electron-transfer coefficient, alpha (= 0.40), for L-cysteine at the surface of 4-FEPEMCPE was determined using cyclic voltammetry technique. It was found that under an optimum pH (= 7.00), the oxidation of L-cysteine at the surface of such an electrode occurred at a potential of about 350 mV less positive than that of an unmodified CPE. The catalytic oxidation peak currents represented a linear dependence on the L-cysteine concentration. Linear analytical curves were obtained in the ranges of 9.0 x 10(-5) - 4.9 x 10(-3) M and 2.0 x 10(-5) - 2.8 x 10(-3) M of L-cysteine with correlation coefficients of 0.9981 and 0.9982 in cyclic voltammetry and differential pulse voltammetry, respectively. The detection limits (2 sigma) were determined to be 9.9 x 10(-6) M and 5 x 10(-6) M with cyclic voltammetry and differential pulse voltammetry, respectively. The influences of twenty other amino acids, such as glutamine, L-glutamic acid, L-glysine, L-histidine, L-isoleucine, L-leucine, L-arginine hydrochloride, L-aspargine, L-aspartic acid, S-carboxy methyl-L-cysteine, L-methionine, L-phenyl alanine, L-proline, L-serine, L-threonine, L-cystine, cysteamine and gluthathione, on the current response of the sensor were examined. The obtained results did not show any influence on the analytical signal of L-cysteine by these amino acids (except for cysteamine). The method was also used for the selective determination of L-cysteine in patient-blood plasma and some pharmaceutical preparations by using standard addition method.

Amino Acids↗

Influence of the environment in space on the biochemical characteristics of human low density lipoproteins.

The purpose of this experiment was to study the efficiency of protective substances on the effects of cosmic radiation in space on low density lipoproteins. This environment induced modifications in LDL consisting of an increase of lipid peroxidation markers (hydroperoxides, thiobarbituric acid reactive substances). In contrast, apo B was not affected by cosmic radiation as shown by the stability of the trinitrobenzenesulfonic acid reactivity and the tryptophan content. Furthermore, oxidation of LDL was partially inhibited by the addition of cysteamine or/and probucol before the spaceflight experiment. The hydroperoxide formation was almost completely inhibited by cysteamine. It was concluded that antioxidants can exert a protective effect against peroxidative stress induced by the space environment.

Cosmic Radiation↗

Inhibition by antiserum to rat growth hormone-releasing factor of growth hormone secretion induced by a met5-enkephalin analog, FK33-824, in rats.

A Met5-enkephalin analog, FK33-824 (5, 10 and 20 micrograms/100 g body wt, iv) caused a dose-related increase in plasma growth hormone (GH) in urethane-anesthetized male rats. Pretreatment with cysteamine (30 mg/100 g body wt, sc), a depletor of hypothalamic somatostatin, increased the plasma GH response to FK33-824 (10 micrograms/100 g body wt, iv). Antiserum specific for rat GH-releasing factor (GRF) (0.5 ml/rat, iv) blunted GH release induced by FK33-824 (10 micrograms/100 g body wt, iv) in rats with or without cysteamine pretreatment. These results suggest that GH secretion induced by the opioid peptide is mediated, at least in part, by hypothalamic GRF in the rat.

Animals↗

Cimetidine transport in brush-border membrane vesicles from rat small intestine.

In previous studies, sulfoxide metabolite was observed in animal and human intestinal perfusions of cimetidine and other H2-antagonists. A sequence of follow-up studies is ongoing to assess the intestinal contributions of drug metabolism and drug and metabolite transport to variable drug absorption. An evaluation of these contributions to absorption variability is carried out in isolated fractions of the absorptive cells to uncouple the processes involved. In this report, data is presented on the drug entry step from a study on [3H]cimetidine uptake into isolated brush-border membrane vesicles from rat small intestine. A saturable component for cimetidine uptake was characterized with a Vmax and Km (mean +/- S.E.M.) of 6.1 +/- 1.5 nmol/30s/mg protein and 8.4 +/- 2.0 mM, respectively. Initial binding, and possibly intravesicular uptake, was inhibited by other cationic compounds including ranitidine, procainamide, imipramine, erythromycin, and cysteamine but not by TEA or by the organic anion, probenecid. Initial uptake was not inhibited by amino acids methionine, cysteine, or histidine, by the metabolite cimetidine sulfoxide, or by inhibitors of cimetidine sulfoxidation, methimazole, and diisothiocyanostilbene-2,2'-disulfonic acid. Equilibrium uptake was inhibited by ranitidine, procainamide, and cysteamine but not by erythromycin or imipramine. Initial cimetidine uptake was stimulated by an outwardly directed H+ gradient, and efflux was enhanced by an inwardly directed H+ gradient. Collapse of the H+ gradient as well as voltage-clamping potential difference to zero significantly reduced initial cimetidine uptake. The data is supportive of both a cimetidine/H+ exchange mechanism and a driving-force contribution from an inside negative proton or cation diffusion potential.

Animals↗

[Studies on urease from the seeds of Citrullus vulgaris: action of chemical agents and ionizing radiations].

Urease obtained from seeds of Citrullus vulgaris fruits has been studied under three points of view: a) the effect of the urea analogs acetamide and hydroxi-urea on the enzyme kinetic b) the action of the sulfhydryl reagents and the reactivation agents on the enzyme c) the effect of X-rays and the protective action of the cysteamine. The Berthelot reaction for the determination of the liberated NH3 was used enzyme activity. Acetamide has no effect on urease kinetic. Hidroxy-urea which produces a typical green color when it is mixed with the Berthelot reagents at high concentrations, when properly diluted acts a aompetitive inhibitor of urease. Spectrophotometric experiments suggest that the studied urease decomposes hydroxi-urea with liberation of hydroxilamine. The sulphydril reagent, p-hydroxi-mercuribenzoate inhibits the enzime. Cysteine and dithiotreitol reactivate the enzyme activity in no more then 50% even when excess of the substances is used. Probably only in the first step of the urea hydrolysis, the enzyme behaves as a typical SH-enzyme. Urease is very sensitive to X-rays. Cysteamine acts as a protective agent of the enzyme. Dithiotreitol reinforces this protective action. This effect is clearly observed when the Fisbein catalytic method for urease is employed.

Chemical Phenomena↗

[Gastrointestinal damage induced by celecoxib and rofecoxib in rats].

UNLABELLED: Five experimental models were carried out in different groups of Wistar rats (n = 15) in order to study selective (cyclo-oxygenase) COX-2 non-steroid antiinflammatory inhibitors, such as celecoxib and rofecoxib, as follows: 1) Dose-dependent oral celecoxib and rofecoxib for 5 days, and 24 hours after oral indomethacin. 2) Same as 1, but subcutaneously. 3) Gastric ulcer induced by means of glacial acetic acid. 4) Duodenal ulcer induced by means of cysteamine. 5) Stress due to being kept under restraint and immersion in water at 15 degrees C for 6 hours. Celecoxib and rofecoxib, either orally or subcutaneously, did not produce necrotic injuries in healthy gastrointestinal mucosa (0%), showing normal histology. On the other hand, the injuries previously induced by indomethacin worsened (90%, p < 0.001). Total necrosis of small intestine as well as increased ulcer and perforation of gastric and duodenal ulcers induced by acetic acid and cysteamine were observed. There was also worsening of gastric necrotic area with stress (60-90%, p < 0.05). Celecoxib and rofecoxib showed neutrophilia (5,000/mm3) similar to that presented by indomethacin, but there was no leukocyte infiltration in the gastric mucosa; thus we can consider it a COX-2 selective NSAID (non-steroidal anti-inflammatory drug). CONCLUSION: Dose-dependent administration of celecoxib and rofecoxib as COX-2 inhibitors and non-COX-1 inhibitors, respectively, did not produce toxic injuries on healthy gastrointestinal mucosa, thus providing a broad therapeutic spectre. On the other hand, when administered in presence of altered gastrointestinal mucosa, they worsened and complicated gastric ulcers, and also induced necrosis in the small intestine, thereby restricting their clinical use.

Animals↗

Effect of SR 58611A, a beta-3 receptor agonist, against experimental gastro-duodenal ulcers.

The present study was designed to study the effect of SR 58611A, a selective beta 3-adrenoceptor agonist against gastric ulcers: pylorus ligation, water immersion plus restraint stress (WIRS), ethanol, aspirin-induced and on cysteamine-induced duodenal ulcers, in rats. SR 58611A (10 mg/kg, p.o.) was found to be effective in attenuating gastric ulceration and the results were comparable with those from standard cimetidine-treated group. Apart from reducing ulcer index, SR 58611A significantly decreased total acidity and thereby exhibited antisecretory activity in pylorus ligation model. SR 58611A showed significant reduction in ulcer index alongwith significant rise in the gastric wall mucus content in WIRS model. Further it showed significant cytoprotective activity against ethanol insult, that was evident from significant reduction in ulcer index. It showed significant reduction in gastric ulceration in aspirin-treated rats. The drug was found to be ineffective in inhibiting the cysteamine-induced duodenal ulcers as evident from the ulcer index and total lesion area parameters. It is concluded that SR 586111A possesses significant gastroprotective activity. This activity could be attributed to the inhibition of gastric acidity, increase in gastric wall mucus content and the reversal of gastric microvascular injury resulting into protection of the vascular integrity.

Adrenergic beta-3 Receptor Agonists↗

Determination of acrylamide formed in asparagine/D-glucose maillard model systems by using gas chromatography with headspace solid-phase microextraction.

A gas chromatographic method, along with a headspace solid-phase microextraction (HS-SPME), was developed for the determination of acrylamide formed in Maillard reaction model systems. The developed method was validated by liquid chromatography/mass spectrometry. A headspace sample was collected from an aqueous acrylamide solution (100 microg/mL) by SPME and directly injected into a gas chromatograph equipped with a nitrogen-phosphorus detector. The recovery of acrylamide from an aqueous solution was satisfactory, i.e, >93% under the conditions used. Acrylamide formed in an asparagine/D-glucose (molar ratio, 1/2) Maillard reaction model system heated at 150 and 170 degrees C for 20 min was collected and analyzed by the newly developed method using gas chromatography with nitrogen-phosphorus detection and HS-SPME. The amounts of acrylamide were 318 +/- 33 microg/g asparagine from a sample heated at 150 degrees C and 3329 +/- 176 microg/g asparagine from a sample heated at 170 degrees C. Addition of cysteamine or glutathione to the above model system reduced acrylamide formation. Acrylamide formation was not observed when cysteamine or glutathione was added to asparagine in the above model systems to obtain equimolar concentrations of both compounds. This newly developed method is simple and sensitive, and requires no solvent extraction.

Acrylamide↗

Protective effect of centrally-injected glucagon-like peptide-1 on reserpine-induced gastric mucosal lesions in rat: possible mechanisms.

BACKGROUND/AIMS: Intracerebroventricular glucagon-like peptide- 1 (GLP-1) has been shown to prevent the gastric mucosal lesions induced by reserpine. In the present study, we aimed to investigate the contribution of 1- the cholinergic pathway, 2- the sympathetic pathway, 3- somatostatin and 4- endogenous nitric oxide to this gastroprotective effect. METHODS: Rats were equipped with intravenous and intracerebroventricular cannulas under ether anesthesia for drug delivery. Rats were pretreated with mecamylamine (5 mg/kg; i.p.) and atropine sulfate (1 mg/kg; i.p.), yohimbine (1 mg/kg; i.p.), cysteamine (280 mg/kg; s.c.), and NG-nitro-L-arginine methyl ester (3 mg/kg; i.v.) to investigate the role of the cholinergic pathway, sympathetic pathway, somatostatin and endogenous nitric oxide, respectively, in the gastroprotective effect of GLP-1. To produce gastric mucosal lesions, reserpine was administered intraperitoneally at a dose of 25 mg/kg in 10 ml/kg of 0.5% acetic acid solution. Four hours later, the animals were decapitated, and their stomachs were removed and scored for mucosal damage. RESULTS: Glucagon- like peptide-1 (100 ng/10 microl; i.c.v.) inhibited the reserpine-induced gastric mucosal damage by 90% (p<0.01). Neither the nicotinic receptor antagonist mecamylamine (5 mg/kg; i.p.) nor the muscarinic receptor antagonist atropine sulfate (1 mg/kg; i.p) affected the gastroprotective activity of GLP-1. On the other hand, pretreatment with yohimbine, an alpha2-adrenergic receptor antagonist (1 mg/kg; i.p.), cysteamine, a somatostatin depletor (280 mg/kg; s.c.), and NG-nitro-L-arginine methyl ester, a nitric oxide synthase inhibitor (3 mg/kg; i.v.), significantly abolished the protective effect of GLP-1 on reserpine-induced gastric mucosal lesions (p<0.001, p<0.01 and p<0.01, respectively). CONCLUSIONS: We conclude that the sympathetic pathway, somatostatin and nitric oxide, but not the cholinergic pathway, contribute to the gastroprotective effect of intra-cerebroventricular GLP-1 on reserpine-induced gastric mucosal lesions.

Adrenergic Uptake Inhibitors↗

The effect of some anti-ulcer agents on the early vascular injury of gastric mucosa induced by ethanol in rats.

The effect of some gastroprotective agents cysteamine, sodium salicylate, atropine, cimetidine, and pyrido-pyrimidine derivatives, rimazolium, Ch-127 and a mast cell stabilizer, BMY-26517-31 was studied on the enhanced vascular permeability of gastric mucosa induced by 100% ethanol, on the enhanced vascular permeability of peritoneal blood vessels due to 0.3% acetic acid and on carrageenin edema test. We found that cysteamine, sodium salicylate, rimazolium and BMY-26517-31 inhibited the alcohol-induced enhanced vascular permeability. They also decreased the carrageenin-induced edema and--with the exception of BMY-26517-31--the acetic-acid-induced enhanced vascular permeability of the peritoneal vessels. These results suggest that similar events are present in the early phase of acute inflammation and chemically induced mucosal lesions. Consequently, antiinflammatory activity might play role in the protective mechanism of some anti-ulcer agents.

Acetates↗

Phenotyping of human apolipoprotein E from whole blood plasma by immunoblotting.

Human apolipoprotein E (apoE) exists in the population in three common genetically determined isoforms, apoE-2, E-3, and E-4, that are coded for by three alleles epsilon-2, epsilon-3 and epsilon-4 at the apoE structural gene locus resulting in six phenotypes, three homozygotes (E 2/2, E 3/3, and E 4/4) and three heterozygotes (E 2/3, E 2/4, and E 3/4). A new procedure is described that allows identification of apoE isoforms and phenotypes from whole plasma or serum without the need for isolating apoE-containing lipoproteins or two-dimensional gel electrophoresis of serum. This rapid method combines cysteamine treatment of apoE in plasma, separation in parallel of cysteamine-treated and untreated hydrophobic serum proteins by charge-shift electrophoresis, and isoelectric focusing of apolipoproteins with immunoblotting. Compared to phenotyping of apoE after isolation of VLDL, the new procedure agreed in most cases and may be of special value in detecting apoE mutants that differ in their cysteine residues or either are spun off during isolation of lipoproteins or cofocus with other apoproteins and thus escape detection by conventional one-dimensional techniques. The method provides a simple tool to screen apoE isoforms that are known to have a major impact on individual plasma cholesterol levels.

Apolipoproteins E↗

Significance of sulfhydryl compounds in the manifestation of fluoroacetate toxicity to the rat, brush-tailed possum, woylie and western grey kangaroo.

Levels of citrate in kidneys and livers of rats with normal glutathione levels increased 6.8 and 1.7-fold respectively 2 h after dosing with 1.5 mg of compound 1080 (= 95% sodium fluoroacetate) per kilogram body weight. In animals with liver glutathione levels 15% of normal, increases in plasma and liver citrate levels after dosing with fluoroacetate were significantly greater than those of control animals. Cysteamine and N-acetylcysteine, like glutathione, partially protected aconitate hydratase from fluorocitrate inhibition in rat liver preparations but were unable to replace glutathione as a substrate for the defluorination of fluoroacetate in vitro. N-Acetylcysteine did not diminish plasma citrate levels of glutathione-deficient rats dosed with fluoroacetate, while cysteamine inhibited the rate of in vivo defluorination in glutathione-deficient brush-tailed possums. It is suggested that non-physiological sulfhydryl compounds are ineffective antidotes to fluoroacetate intoxication in vivo. The in vivo defluorination patterns of four mammal species with differing sensitivities to fluoroacetate did not indicate a direct relationship between tolerance and rate of defluorination and it is also suggested that a high level of activity of the glutathione-S-transferase responsible for the defluorination of fluoroacetate is not the major mechanism for circumventing fluoroacetate toxicity in resistant mammals.

Animals↗

Gamma-glutamylcysteine synthetase. Interactions of an essential sulfhydryl group.

gamma-Glutamylcysteine synthetase (isolated from rat kidney) has one sulfhydryl group that reacts with 5,5'-dithiobis-(2-nitrobenzoate). This single exposed sulfhydryl group is not required for enzyme activity. The enzyme is potently inactivated by cystamine, which apparently interacts with a sulfhydryl group at the active site to form a mixed disulfide. 5,5'-Dithiobis-(2-nitrobenzoate) does not interact with the sulfhydryl group that reacts with cystamine. After the enzyme was 90% inactivated by reaction with cystamine, 3.4 mol of 5,5'-dithiobis-(2-nitrobenzoate) reacted per mol of enzyme, indicating that binding of cystamine exposes sulfhydryl groups which are apparently buried or unreactive in the native enzyme. L-Glutamate (but not D-glutamate or L-alpha-aminobutyrate) protected against inactivation by cystamine. In contrast, ATP enhanced the rate of inactivation by cystamine, and the apparent Km value for this effect is similar to that for ATP in the catalytic reaction. Studies on the structural features of cystamine that facilitate its interaction with the enzyme showed that selenocystamine, monodansylcystamine, and N-[2[2-aminoethyl)-dithio)ethyl]-4-azido-2-nitrobenzeneamine are also good inhibitors. Whereas S-(S-methyl)cysteamine-Sepharose does not interact with the enzyme (Seelig, G. F., and Meister, A. (1982) J. Biol. Chem. 257, 5092-5096), S-(S-methyl)cysteamine is a potent inhibitor; 1 mol of this compound completely inactivated 1 mol of enzyme. In the course of this work, a useful modification of the method for isolating this enzyme from kidney was developed.

Animals↗