Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CYSTAMINE”

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 865 records · Page 48Linked to original sources
PubMed1985

[Dalargin--a peptide preparation with cytoprotective action].

The role and possible clinical use of regulatory peptides, a new type of regulatory substances, is discussed. Special attention is paid to the opioid peptides and their analogues. The new drug dalargin has been developed on the basis of the endogenous opioid peptide leucine-encephalin. Its action has been studied using experimental models. It has been established that the optimal dose (10 micrograms/kg) of dalargin is effective in preventing ulceration in the cystamine duodenal ulcer rat model and the development of stomach erosive lesions in immobilization stress, reducing the degree of liver degeneration in CCl4 poisoning, etc. With an increase of the dose of dalargin the effect "escapes". Dalargin is primarily bound by delta-receptors, it produces no analgetic effect and does not enter the brain. Dalargin exhibits a pronounced cytoprotective and regeneratory action and may take an important place in treating the internal organ diseases.

Animals↗
PubMedDate not supplied

Proteolysis in human erythrocytes is triggered only by selected oxidative stressing agents.

Human erythrocytes have been treated with different agents producing oxidative stress. Diamide, tetrathionate, chromate, cystamine and iodate preferentially influenced the cellular redox state by oxidation of free and protein thiol groups leaving the redox state of hemoglobin virtually unaffected. None of these compounds was able to stimulate the proteolysis. By contrast, phenylhydrazine, nitrite, hydrogen peroxide, ter-butylhydroperoxide, cumene hydroperoxide and copper-ascorbate caused a noticeable oxidation of hemoglobin to methemoglobin. These latter agents, except nitrite and copper-ascorbate, triggered proteolysis. Identical results have been obtained in a ghost-free hemolysate. The fraction containing the proteolytic activity was isolated from hemolysate and tested on native or oxidant-treated hemoglobin. The proteolysis was stimulated by all agents able to produce methemoglobin. It is concluded that proteolysis correlated to an unbalance of cellular redox state. The results obtained with isolated and recombined fractions suggests that increased proteolysis does not depend on the removal of the effect of protease(s) inhibitor(s). Since all agents stimulating proteolysis are able to generate free radicals, it seems that protein breakdown is triggered by the direct effect of these intermediates on proteins (mostly hemoglobin) without the involvement of radical species produced in the membranes by action of organic hydroperoxides. In addition, since nitrite and copper-ascorbate, which also oxidize hemoglobin by radical generation, are unable to stimulate proteolysis, it should be concluded that protein degradation induced by oxidative stress is a complex event induced only by specific agents.

Erythrocytes↗
PubMed1988

Radioprotection of DNA by thiols: relationship between the net charge on a thiol and its ability to protect DNA.

Release of free bases from calf thymus DNA upon irradiation in aerated 0.1 mol dm-3NaClO4 at pH 7 has been measured by HPLC and shown to be markedly influenced by the presence of thiols during irradiation. The ability of thiols to protect DNA was shown to depend upon the net charge (Z) at pH 7 in the order WR 1065 (Z = +2) greater than cysteamine (Z = +1) greater than 2-mercaptoethanol (Z = 0) approximately equal to dithiothreitol (Z = 0) greater than GSH (Z = -1) approximately equal to 2-mercaptoethanesulfonic acid (Z = -1) approximately equal to 2-mercaptosuccinate (Z = -2). A similar dependence of protection upon net charge was found for disulfides: cystamine (Z = +2) greater than 2-mercaptoethyl disulfide (Z = 0) greater than GSSG (Z = -2). Protection by WR 1065, but not by 2-mercaptoethanol or GSH, was found to decrease significantly with increasing ionic strength. Protection by WR 1065 and GSH was not markedly dependent upon pH between pH 6 and 8. The results are explained in terms of electrostatic interaction of the thiols with DNA, leading to high concentrations of cations near DNA, which allow them to scavenge hydroxyl radicals and repair DNA radicals effectively and to low concentrations of anionic thiols near DNA, which limit their effectiveness as protectors. Poly(dG,dC) and calf thymus DNA exhibited comparable release of G and C upon changing from 0.1 to 0.7 mol dm-3 MgSO4. Since this change causes poly(dG,dC), but not calf thymus DNA, to undergo a change from the B-form to the Z-form of DNA, both forms must have a comparable susceptibility to radiation-induced base release.

Anions↗
PubMedDate not supplied

On the product of the reaction between cysteamine and 3-bromopyruvate.

Some properties of TZCA, the addition compounds of cysteamine and 3-bromopyruvate, have been investigated. From the behaviour of the UV absorption spectra in acidic and alkaline solutions in the presence or absence of oxygen, it was shown that the instability of TZCA was imputable to an oxidative degradation. It was further shown that TZCA undergoes in alkali spontaneous oxidative decarboxylation, and that the arising product may be hydrolyzed to cystamine and glyoxylic acid. Some chemical reactions and the paper chromatographic behaviour of TZCA are reported. It was shown that TZCA, despite its great instability, may be the reactions described, and thus differentiated from other adducts of bromopyruvate and different aminothiols.

Chemical Phenomena↗
PubMed1988

[Highly effective complementary addressed laser modification (cleavage) of oligodeoxynucleotides].

Complementary addressed nonlinear photomodification of oligodeoxynucleotide dAGAGTATTGACTTA ("target") has been carried out by means of fluorescent derivatives of oligonucleotide dpAATACTCT ("addressed chromophore"). Three different ethidium derivatives were used as a chromophore. The photomodification was induced by nitrogen laser radiation (337 nm, 15 MW/cm2), which led to the target cleavage in the addressation region with the yield of the main fragment (8 bases long) about 10%, formation of specific covalent adduct target-addressed chromophore with the yield 20-70%, "hidden" (not revealed by gel electrophoresis) target damages with 7-27% yield (for different chromophores). The total yield of specific (i. e. localized in the vicinity of the addressation site) modification was 50-80%. The target cleavage and hidden damage generation are optically nonlinear processes. Piperidine treatment of the irradiated samples caused addressed cleavage of the target with up to 40% yield. All kinds of observed modification are not effected by high concentrations of free radical scavengers, 1,3 M t-BuOH or 10 mM cystamine. The bulk of the data is in agreement with the mechanism of nonlinear photomodification (the cleavage and hidden damage generation) based on the transfer of two-photon excitation energy from the chromophore to the target.

Base Sequence↗
PubMed1987

[Effect of amines on the binding, internalization and degradation of epidermal growth factor and the induction of DNA synthesis in a 3T3 cell culture].

The role of intracellular processing of epidermal growth factor (EGF) in the induction of proliferation of quiescent Swiss 3T3 cells was studied using various inhibitors. The number of amines (dansylcadaverine, chloroquine, cystamine, 5-methoxytryptamine) dimethylurea and monensin were shown to block the mitogenic effect of EGF. The majority of these substances while used in concentrations sufficient to inhibit the proliferation do not significantly influence 125I-EGF binding and internalization. The level of EGF degradation was reduced only by chloroquine. The inhibitory effect of amines and monensin on the generation of proliferative signal was supposed to take place at the stages of EGF processing in "specialized" endosomes and in Golgi apparatus.

Amines↗
PubMedDate not supplied

[Effect of radiomodifiers on lipid peroxidation and the structural-functional state of irradiated mitochondria].

SH-Containing radioprotective agents, for instance, cysteine, cystamine, dithiothreitol, exert an antioxidant effect on gamma-radiation-induced lipid peroxidation in mitochondrial membranes and, concurrently, uncouple oxidation from phosphorylation. A radiosensitizer, N-ethylmaleimide, on the contrary, being a pro-oxidant of lipid peroxidation couples oxidation and phosphorylation. At the same time, changes in the lipid peroxidation system and in the energy production processes, observed after irradiation of a mitochondrion suspension containing modifiers, are accompanied by the increased destruction of mitochondrial membranes as compared to irradiated controls.

Animals↗
PubMed1987

[Effect of vagotomy, alpha-tocopherol and arachidene on lipid peroxidation in various areas of the gastroduodenal zone in rats with experimental peptic ulcer].

Lipid peroxidation (LPO) was investigated in the mucosa of different gastroduodenal areas in rats with ulcer. The animals were subject to various types of vagotomy and given various drugs. The ulcerogenic agent--cystamine--was shown to have a different degree effect on the activation of free radical reactions, most pronounced in duodenal mucosa. Selective proximal vagotomy was most effective in decreasing LPO activity, as compared to total and partial vagotomy. The use of an antioxidant--alpha-tocopherol, particularly its combination with arachidene, a preparation of polyunsaturated fatty acids, prevented the development of duodenal ulcer in 75% of cases and markedly decreased both ascorbate- and NADP X H-dependent LPO. It is suggested that LPO is directly involved in the pathogenesis of ulcer and that factors attenuating the process of LPO may prevent ulcerogenesis.

Animals↗
PubMedDate not supplied

[Effect of radioprotective agents on the epithelium of small intestine mucosa in irradiated animals].

In experiments on irradiated (10 Gy) mice a study was made of the morphological changes in the small intestine mucosa and in its functional status estimated by absorption of stain uranine. It was shown that the preventive administration of cystamine and S-(omega)-aminopropyl-beta-aminoethylthiophosphoric acid to the exposed mice increased the proliferation processes in the crypt and the cell movement per villus providing a favourable effect of the radioprotective agents on the absorption function.

Animals↗
PubMedDate not supplied

Oxidative deamination of thialysine by snake venom L-aminoacid oxidase.

Thialysine is oxidatively deaminated by snake venom L-aminoacid oxidase at alkaline pH. The oxygen consumption curves show a characteristic diphasic course: the quick uptake of half a mole of oxygen per mole of substrate, in aggreement with a typical oxidative deamination, is followed by a slow extra oxygen consumption. The first product of the reaction is the corresponding alpha-oxo-epsilon-amino acid, which spontaneously cyclizes to the internal Schiff base 5-6-dihydro-delta 3,1,4-thiazin-3-carboxylic acid (TZCA). This latter has been identified by its UV absorption spectrum, by some chemical reactions, by paper chromatography, and by the production of cystamine and glyoxylic acid after prolonged oxidation of thialysine followed by acid hydrolysis. The possibility of an alpha-beta elimination reaction giving rise to cysteamine from thialysine, coupled to the oxidative deamination, has been excluded.

Amino Acid Oxidoreductases↗
PubMed1985

[Amine inhibition of serum-induced DNA synthesis in 3T3 and 3T6 cell cultures].

Several amines were shown to inhibit growth stimulation in quiescent confluent and sparse cultures of Swiss 3T3 and 3T6 cells by changing for a fresh medium containing 10-20% serum. Proliferation was inhibited by dansylcadaverine (0.1 mM), chloroquine (0.05 mM), 5-methoxytryptamine (0.1 mM), cystamine (0.1 mM), dimethylurea (100 mM), methylurea (100 mM), and in some experiments--by urea (100 mM). The inhibitory activity was not associated with a direct influence of amines on DNA synthesis or thymidine phosphorylation. The findings suggest that amines may influence the process of clustering of growth factor-receptor complexes, or the fusion of plasma membrane and intracellular vesicles containing some components required for cell proliferation.

Amines↗
PubMed1985

Isolation and characterization of methionine synthetase from human placenta.

The cobalamin-dependent enzyme, methionine synthetase, has been purified approximately 1000-fold to apparent homogeneity from human placenta with a 19% recovery. The final two steps of the purification utilized two different affinity columns. The first was a N5-methyltetrahydrofolate-cystamine-agarose column, and the second was a S-adenosylhomocysteine-agarose column. The enzyme was eluted from the first affinity column by buffer containing reducing agent which released the folate and the enzyme while elution from the second affinity column was accomplished with buffer containing 0.5 M sodium chloride. Criteria for purity were the observations that single peaks of enzyme activity, protein, and cobalamin with an apparent molecular weight of 160,000 were obtained by gel filtration and that holomethionine synthetase contained 1 mol of cobalamin/mol of protein. Furthermore, analysis by high performance liquid chromatography using a molecular weight sizing column demonstrated a single peak of protein with a corresponding cobalamin peak. This single peak of protein was progressively converted to a second protein peak that was enzymatically inactive, and this conversion was associated with a directly proportional loss of enzyme activity and cobalamin from the first peak. Methionine synthetase appeared to have a molecular weight of 160,000 on unreduced sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis and subunits of Mr 90,000, 45,000, and 35,000 on reduced sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1982

Neutralization of native human gamma interferon (HuIFN gamma) by antibodies to a synthetic peptide encoded by the 5' end of HuIFN gamma cDNA.

A synthetic peptide corresponding to the N-terminal amino acid sequence of human gamma-interferon (HuIFN gamma), based on the cDNA sequence, was used to produce antibodies in rabbits that were reactive with native HuIFN gamma. Antibodies from all immunized rabbits neutralized the antiviral activity of HuIFN gamma. Significant neutralization of other HuIFN and mouse IFN was not observed. The peptide had the sequence Cys-Tyr-Cys-Gln-Asp-Pro-Tyr-Val-Lys-Glu-Ala-Glu-Asn-Leu-Lys-Lys-Tyr-Phe-Asn-Ala ,and was coupled to keyhole limpet hemocyanin by disulfide linkage with the use of cystamine. The specificity of the antibodies produced to the peptide was compared to that of antibodies produced to native HuIFN gamma by neutralization of HuIFN gamma and by reactivity with peptide in the enzyme-linked immunosorbent assay (ELISA). The ratio of anti-peptide antibody neutralization of HuIFN gamma vs reactivity with peptide in the ELISA was at least 28-fold lower than for anti-HuIFN gamma antibody. Thus the antibodies to peptide and to HuIFN gamma were directed primarily against different determinants on native HuIFN gamma or the anti-HuIFN gamma antiserum probably contained antibodies to additional determinants. The anti-peptide antibodies should be useful for further characterization and purification of HuIFN gamma.

Amino Acid Sequence↗
PubMed1983

Qualitative and quantitative differences between the postsynaptic alpha adrenoceptors of rabbit ear artery and thoracic aorta.

The alpha adrenoceptor properties of the rabbit ear artery and thoracic aorta were assessed using isolated blood vessel rings mounted in tissue baths. Labetalol, an alpha and beta receptor antagonist, caused dose-dependent contractions in control, reserpinized and surgically denervated ear arteries. This contraction was inhibited by phentolamine and abolished by the irreversible alpha receptor antagonist, N,N'-bis-(O-methoxy-benzylaminohexyl) cystamine tetrahydrochloride. Thoracic aorta failed to respond to labetalol. Using labetalol as an antagonist against methoxamine, labetalol pA2 values were 7.4 +/- 0.3 (95% confidence interval) and 7.13 +/- 0.25 in ear artery and aorta, respectively. Thus, labetalol had the same affinity for the alpha receptors of these two vessels but was an alpha agonist only in the ear artery. Norepinephrine ED50 values and dissociation constants (KA) were determined by analysis of dose-response data with and without partial inactivation of alpha receptors by phenoxybenzamine. Ear artery and aorta norepinephrine ED50 values, 4.24 (2.24-8.03) X 10(-8) M and 2.48(1.64-3.76) X 10(-8) M, respectively, were not significantly different. In contrast, norepinephrine KA values differed by a factor of 32, 4.11 (3.02-5.60) X 10(-6) M and 1.29 (0.85-1.94) X 10(-7) M, respectively. Receptor reserves were also markedly different in these vessels. Thus, ED50 was achieved with 1% receptor occupancy in ear artery as compared to 16% receptor occupancy in aorta. It is concluded that the alpha receptors of ear artery and aorta are both qualitatively and quantitatively different.

Animals↗
PubMed1984

Production of thymine base damage in ultrasound-exposed EMT6 mouse mammary sarcoma cells.

Mouse mammary sarcoma cells, line EMT6/Ro, were exposed for 1 min to 1 MHz continuous wave ultrasound over a range of intensities from 0.5 to 30 W/cm2 (spatial peak). The presence of thymine base damage (TBD) products of the 5,6-dihydroxydihydrothymine type was determined by an alkali degradation assay. Production of damage was found to be greatest (approximately 2.7 X 10(-3%) t'/T) at an intensity of 10 W/cm2 and fell off rapidly above and below this intensity. The amount of base damage produced at 10 W/cm2 ultrasound was approximately equivalent to the damage produced by a gamma-ray absorbed dose of 12 krad. Assay of cells immediately after sonication at 10 W/cm2 showed that approximately 14% of the cells had been lysed. Tests showed that it was the DNA of the intact cells, however, which sustained all of the TBD. Survival data demonstrated that of the remaining unlysed cell population approximately 5% were viable, whereas cells exposed to 12 krad showed no survival. Additionally, cells were exposed for up to 5 min at 5 W/cm2. An increase in TBD was demonstrated with increasing time of exposure such that the rate of production at 5 min was approximately three times greater than that of a 1-min exposure. TBD was found to be completely suppressed when cells were sonicated at 10 W/cm2 for 2 min under 4 bar of hydrostatic pressure. Addition of the radical scavengers beta-MEA and cystamine eliminated TBD but had minimal effect on survival. The pressure and scavenger experiments demonstrate that TBD results from cavitation-induced free radicals. Based on the values for both the half-life and diffusion distance of such radicals, our results indicate that at least part of the bubble collapse occurs intracellularly.

Animals↗
PubMed1984

Glutathione disulfide inactivates, destabilizes, and enhances proteolytic susceptibility of fructose-1,6-bisphosphate aldolase.

Disulfides (glutathione disulfide, cystine, cystamine) caused a first-order inactivation of rabbit-muscle fructose-1,6-bisphosphate aldolase at pH values of 7.4 and above. Inactivation by glutathione disulfide was partially reversed by reducing agents, but the enzyme became irreversibly inactivated with time. The disulfide-inactivated aldolase had a lower transition temperature and enthalpy of denaturation than the native enzyme. In addition, the disulfide-inactivated enzyme was extensively degraded by proteinases, whereas the native enzyme was resistant. Mixed disulfides were formed; a maximum ratio of 4-5 mol of glutathione/mol of the aldolase tetramer was found. The number of titratable--SH groups on aldolase decreased by 16 (out of 32 total on the control enzyme) after inactivation by glutathione disulfide, indicating that other oxidation reactions in addition to those resulting in mixed disulfides occurred. The substrate, fructose 1,6-bisphosphate, prevented inactivation of aldolase by glutathione disulfide, the formation of glutathione-enzyme mixed disulfides, thermodynamic destabilization of the enzyme, and a decrease of--SH groups on the enzyme. These data indicate that covalent modification of aldolase by biological disulfides is important in modulating enzyme stability and vulnerability to proteinases as well as enzyme activity and that the substrate protects against modification by disulfides.

Animals↗
PubMed1982

[A new technic for the study of the physiology of erythrocytes: measurement of their deformability as a function of osmolarity. Results obtained by an automatized Ektacytometer in normal blood and in various hemolytic anemias].

A system has been added to the Ektacytometer to allow continuous variation and measurement of the osmolarity of the suspension medium from 50 to 500 mosm kg-1 permitting the analysis of erythrocyte deformability over a range varying from hypo- to hypertonicity. The curves are obtained automatically in 7 min. from a blood sample of 150 microliters. The "minimum index" observed in hypotonicity indicates that the cells are non-deformable at this point just preceding hemolysis. The osmolarity at which this index occurs provides a measure of the osmotic fragility of the sample. In hypertonicity there is a zero index, corresponding to non-deformable cells, which occurs at an osmolarity dependent on the original internal viscosity of the cells. This "null index" introduces the notion of erythrocyte resistance to deformation in hypertonicity. This new technique permits the evaluation of the erythrocyte response to various factors affecting their shape, internal viscosity or membrane flexibility. We present and discuss examples of curves obtained with normal blood before and after fractionation by density and after treatment with cystamine, as well as pathological bloods from two hemolytic anemias (hereditary spherocytosis and sickle cell anemia).

Anemia, Hemolytic↗