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PubMed1978

Simplified typing of mouse hemoglobin (Hbb) phenotypes using cystamine.

Cellulose acetate electrophoresis of mouse hemoglobins modified with the disulfide reagent cystamine permits rapid, unequivocal discrimination of all combinations of the codominant mouse hemoglobin "single" (Hbbs) and "diffuse" (Hbbd and Hbbp) alleles. The single, diffuse major, diffuse d-minor, and diffuse p-minor adult hemoglobins are all resolved by this method, which depends on the presence of a cysteine in the beta chains of "diffuse" mice which is not found in the beta chain of "single" mice.

Alleles↗
PubMed2002

A piezoelectric immunoassay based on self-assembled monolayers of cystamine and polystyrene sulfonate for determination of Schistosoma japonicum antibodies.

A piezoelectric immunosensor based on an improved immobilization strategy combining self-assembled monolayers (SAM) of cystamine (Cys) and polystyrene sulfonate (PSS) has been developed for the determination of Schistosoma japonicum antibodies (SjAb) in rabbit serum. Cys SAM were first applied to the gold electrode surface of the crystal, serving as a positively-charged base. Schistosoma japonicum antigen (SjAg) was then electrostatically immobilized on the crystal by means of a negatively-charged PSS layer. When sealed by use of an appropriately selected blocking reagent for BSA and normal rabbit serum (NRS), non-specific adsorption could be substantially reduced. The immunosensor was used to determine SjAb in optimized buffer medium with addition of poly(ethylene glycol) (PEG), which served as an immunoreaction enhancer. It was shown experimentally that SjAg immobilized by the Cys-PSS adsorption procedure had higher immunological activity or binding efficiency than those immobilized by the glutaraldehyde (GLU) binding or direct attachment procedures. The immunosensor developed had satisfactory sensitivity and detection limit, and regeneration of the piezoelectric quartz-crystal was easy. Analytical results obtained with infected rabbit serum samples indicated that the proposed immunosensor is a promising alternative for qualitative and quantitative determination of SjAb in clinical diagnosis of infection with Schistosoma japonicum.

Adsorption↗
PubMed2005

Pharmacokinetics and tissue retention of (Gd-DTPA)-cystamine copolymers, a biodegradable macromolecular magnetic resonance imaging contrast agent.

PURPOSE: To investigate the pharmacokinetics, long-term tissue retention of Gd(III) ions, and magnetic resonance imaging (MRI) contrast enhancement of extracellular biodegradable macromolecular Gd(III) complexes, (Gd-DTPA)-cystamine copolymers (GDCC), of different molecular weights. METHODS: The pharmacokinetics of blood clearance and long-term Gd(III) retention of GDCC were investigated in Sprague-Dawley rats. Pharmacokinetic parameters were calculated by using a two-compartment model. The blood pool contrast enhancement of GDCC was evaluated in Sprague-Dawley rats on a Siemens Trio 3T MR scanner. Gd-(DTPA-BMA) was used as a control. RESULTS: The alpha phase half-life of Gd-(DTPA-BMA) and GDCC with molecular weights of 18,000 (GDCC-18) and 60,000 Da (GDCC-60) was 0.48 +/- 0.16 min, 1.08 +/- 0.24 min, and 1.74 +/- 0.57 min, and the beta phase half-life was 21.2 +/- 5.5 min, 26.5 +/- 5.9 min, and 53.7 +/- 15.9 min, respectively. GDCC had minimal long-term Gd tissue retention comparable to that of Gd-(DTPA-BMA). GDCC resulted in more significant contrast enhancement in the blood pool than Gd-(DTPA-BMA). CONCLUSIONS: GDCC provides a prolonged blood pool retention time for effective MRI contrast enhancement and then clears rapidly with minimal accumulation of Gd (III) ions. It is promising for further development as a blood pool MRI contrast agent.

Animals↗
PubMed1985

Structure of the Escherichia coli 16 S ribosomal RNA. Psoralen crosslinks and N-acetyl-N'-(p-glyoxylylbenzoyl)cystamine crosslinks detected by electron microscopy.

Escherichia coli 16 S ribosomal RNA in reconstitution buffer has been photochemically crosslinked with aminomethyltrimethylpsoralen and chemically crosslinked with N-acetyl-N'-(p-glyoxylylbenzoyl)cystamine. The positions of crosslinking have been detected by viewing the molecules in the electron microscope. DNA restriction fragments that contain psoralen mono-adducts were hybridized and crosslinked to the samples so that the orientations of the crosslinked molecules were seen directly. A two-dimensional histogram method has been used to classify the different types of looped crosslinked molecules. These methods allow the identification of 13 distinct types of loops in the photochemically crosslinked molecules and 31 distinct types of loops in the chemically crosslinked molecules. The psoralen experiments are a reinvestigation of some of our earlier results. Some of the crosslinks were previously reported in the incorrect orientation; with the corrected orientation, seven of the psoralen crosslinks can now be correlated with complementarities in the proposed secondary-structure models. However, there are still six other psoralen crosslinks that indicate additional contacts not found in the current models. The chemical crosslinks indicate pairs of single-stranded regions that must be close in the folded molecule. Many of these crosslinks occur between regions that are distant in the secondary structure; these crosslinks indicate part of the three-dimensional form of the folded molecule.

Cross-Linking Reagents↗
PubMed1998

S-methylthio-cysteine and cystamine are potent stimulators of thiol production and glutathione synthesis.

The effects of methylthio-cysteine disulfide (MT-Cy) and cystamine (CAM) on the thiol production and glutathione content of a human T cell line (CEM-SS) have been investigated. MT-Cy per se and CAM in the presence of cystine greatly enhanced thiol production and glutathione content of cells while cystine alone exerted no or slight influence in the first hours. The MT-Cy- or CAM-induced extracellular SH-generation was observed both in a complete nutrient medium and even more in SH-free D-PBS. The acid-soluble thiol level and glutathione content of cells elevated markedly (up to 5-6 fold in two hours) when incubating cells in complete medium. Inhibition of glutathione synthesis by DL-buthionine (S,R)-sulfoximine did not alter the MT-Cy- or CAM-induced extracellular thiol production indicating that glutathione synthesis is not involved in this effect. The results suggest that MT-Cy easily enters the cells thus accelerating the thiol cycle in SH-poor medium while CAM promotes cystine uptake into the cells. Phenylalanine and leucine inhibited both MT-Cy- and CAM-dependent thiol production in D-PBS most effectively suggesting the involvement of the L membrane transport system in these effects.

Cell Line↗
PubMed1989

Synthesis and radioprotective activity of dipeptide cysteamine and cystamine derivatives.

Some N-(dipeptidyl)-S-acetylcysteamine and N,N'-(dipeptidyl)cystamine salt derivatives were synthesized and evaluated as candidate radioprotector agents. Toxicity and radioprotective activity as the dose reduction factor (DRF) were determined in vivo on mice and compared to N-glycyl-S-acetylcysteamine trifluoroacetate. One of the most interesting compounds of this series was N-glycylglycyl-S-acetylcysteamine trifluoroacetate (8).

Animals↗
PubMed1986

Synthesis and radioprotective activity of new cysteamine and cystamine derivatives.

A variety of N-(aminoalkanoyl)-S-acylcysteamine and N,N'-bis(aminoalkanoyl)cystamine salt derivatives were synthesized. Toxicity and radioprotective activity (as the dose reduction factor DRF) were determined in vivo on mice and compared to WR 2721 and S-acetylcysteamine hydrochloride. One of the most interesting compounds of this series was N-glycyl-S-acetylcysteamine trifluoroacetate (16, I 102). Structure-activity relationships are discussed.

Amifostine↗
PubMedDate not supplied

Contrast-enhanced magnetic resonance angiography with biodegradable (Gd-DTPA)-cystamine copolymers: comparison with MS-325 in a swine model.

The purpose of this study is to evaluate the use of (Gd-DTPA)-cystamine copolymers (GDCC), a novel biodegradable intravascular polydisulfide-based macromolecular gadolinium(III) contrast agent, for first-pass and steady-state contrast-enhanced magnetic resonance angiography (MRA) in a swine model. A breath-hold background-suppressed 3D MRA of the thorax was performed for first-pass imaging and repeated every 10 min after GDCC injection to monitor the tissue enhancement time course. A navigator-gated 3D MRA of the coronary arteries was performed during steady state following the first-pass imaging. Imaging with intravascular agent MS-325 approximately 1 h after GDCC injection was also included for comparison. Experimental results indicated that GDCC provided significant blood signal-to-noise ratio (SNR) improvement, approximately 1633% for first-pass and 33% for steady-state contrast-enhanced MRA. Compared to MS-325, GDCC provided similar blood enhancement for first-pass and steady-state imaging but with a different tissue enhancement time course. The blood SNR enhancement half-time was 10 +/- 6 min for GDCC and 46 +/- 33 min for MS-325. GDCC provided less enhancement in the liver, bone growth plates, and muscle than MS-325.

Animals↗
PubMed1980

Synthesis and properties of N-acetyl-N'-(p-glyoxylylbenzoyl)cystamine, a new reagent for RNA-RNA and RNA-protein cross-linking.

The synthesis of N-acetyl-N'-(p-glyoxylylbenzoyl)cystamine (Gbz-Cyn2-Ac) is described. Like other glyoxal-type reagents it reacts with guanine and arginine. The kinetics and pH dependence of these reactions are studied. (Gbz-Cyn2-Ac) reacts with non-base-paired guanines at about 20 sites in 16-S rRNA. After reduction of disulfide bonds each derivatized guanine residue carries a free -- SH group which can be used to create RNA-RNA bridges or, after introducing an additional photoactivatable derivative, RNA-protein bridges.

Arginine↗
PubMed1987

The effect of cysteamine, cystamine, and the structurally related compounds taurine, N-acetyl-cysteine, and D-penicillamine on plasma prolactin levels in normal and estrogen-primed hyperprolactinemic rats.

Studies were undertaken to evaluate the effects of cysteamine (CSH), cystamine (CS-S), N-acetyl-cysteine, D-penicillamine, and a major metabolite of CSh, taurine, on plasma PRL levels in normal and estrogen-primed hyperprolactinemic rats. Both CSH and CS-S caused a marked decrease in plasma PRL concentration in hyperprolactinemic rats. The effects of CSH and CS-S lasted for at least 6 h but returned toward pretreatment levels 24 h later. In normal rats a fall in basal plasma PRL concentration was not readily observed but after stimulation with TRH or metaclopramide, PRL secretion elicited by these stimuli was markedly inhibited by CSH and CS-S. The response to TRH or MCP 24 h after treatment with CSH was variable with CS-S appearing to cause an unexpected increase in PRL release in response to TRH or metaclopramide. The structurally related compounds, taurine, N-acetyl-cysteine, and D-penicillamine did not cause any reduction of plasma PRL levels in hyperprolactinemic rats. This may be due, in the case of taurine, to a loss of the free sulfydryl group, in the case of N-acetyl-cysteine, a change in basicity because of a carboxyl group and derivatization of the amino group and D-penicillamine, again a change in basicity due to a free carboxyl group as well as an altered structural relationship between the free amino and sulfydryl groups. These studies indicate that CSH and CS-S by possible reduction to CSH cause a reversible depletion in plasma PRL in normal and hyperprolactinemic rats. Because both substances inhibit different receptor-mediated stimuli, their mechanism of action is likely to be mediated at a common locus involved with the synthesis and release of PRL.

Acetylcysteine↗
PubMed1989

The effect of a cystamine derivative, bis[2-(E-2-hexenoylamino)ethyl] disulfide, on rat platelet aggregation.

Bis[2-(E-2-alkenoylamino)ethyl] disulfides (compds. I), synthesized from cystamine and 2-trans fatty acids, inhibited collagen-induced rat and rabbit platelet aggregation. The most potent compound was bis[2-(E-2-hexenoylamino)ethyl] disulfide (compd. I-1), and this compound suppressed thromboxane B2 formation from arachidonic acid in rat platelets. The results suggested that compd. I-1 has an inhibitory effect on cyclooxygenase.

Alkenes↗
PubMed1975

Protective effect of a mixture of radioprotector substances (mexamine and cystamine) on the haematopoietic stem cells of mice.

A protective effect of the mixture of radioprotectors (mexamine and cystamine) on the haematopoietic stem cells of the spleen and bone marrow was studied in mice irradiated by a dose 700 R in different time intervals after intraperitoneal injections of the substances. The protective effect of the mixture against the lethal radiation effects outlasts till the 90th minute after the injection, as well as the protection of the haematopoietic stem cells in the bone marrow. D0 of the regression lines of the survival of endogenous colonies in the spleen (ESC) increases up to 340 R after irradiating the mice in the 15 min interval after the injection of the protective substances with a subsequent decrease to the level of the control group (100 R). The D0 values of CFU survival in the bone marrow does not change; however, in the interval up to 60 min after the injection complete reparation of the radiation damage takes place after an exposure to 100 R. The recovery from the damage to the erythropoiesis followed by an incorporation of 59Fe into the bone marrow and spleen is the faster the higher a number of CFU survived the used radiation dose. The importance of a decrease of the radiation damage to the small intestine for the total protective effect of the mixture of radioprotectors is discussed.

5-Methoxytryptamine↗
PubMed1975

Acute cardiovascular responses to radioprotective mixture of cystamine and 5-methoxytryptamine in rats.

I.p. administration of radioprotective mixture of cystamine (18 mg base/kg) and 5-methoxytryptamine (3 mg base/kg) to anesthetized rats induced the depression of hemodynamics. Decrease of cardiac output, hypotension, bradycardia, increase in peripheral vascular resistance, the escape of plasma from the vascular stream, pronounced diminution of blood flow in the spleen and other tissues were determined. Pharmacological properties of the protective can contribute to its radioprotective efficiency in the whole mammalian organism.

5-Methoxytryptamine↗
PubMed1976

Hemodynamic changes in rats after radioprotective combination of cystamine administered subcutaneously and 5-methoxytryptamine injected intramuscularly.

Administration of cystamine (20 mg base/kg s.c.) and 5-methoxytryptamine (10 mg base/kg i.m.) with 12 minutes delay to anesthetized rats induced the depression of whole cardiovascular system, hemoconcentration and great blood flow decrease in the radiosensitive tissues. Distributionof lowered cardiac output preferred the fractions to brain, heart, liver and lungs. Hemodynamic responses to protective combination may participate in its radioprotective action.

5-Methoxytryptamine↗
PubMed1975

Dimethylnitrosamine-induced inhibition of hepatic protein synthesis in vitro and the effect of pretreatment with cystamine or pregnenolone-16alpha-carbonitrile.

Hepatic protein synthesis was investigated using a postmitochondrial supernatant system derived from the livers of rats that were given injections of a single dose of dimethylnitrosamine (DMN), 30 mg/kg. The time course and extent of DMN-induced inhibition in vitro were identical to those reported for the incorporation of amino acids into liver proteins in vivo, maximum inhibition being about 70% at 5 hr. Addition of specific inhibitors of chain initiation (polyinosinic acid and aurin tricarboxylic acid) to the postmitochrondrial supernatant system from DMN-treated rats caused only a slight additional inhibition, indicating that DMN predominantly affects translation by a block of initiation. Treatment with cystamine prior to DMN administration completely abolished the depression of protein synthesis and reduced by more than 90% the methylation by [14C]DMN of purine bases in liver DNA. Pretreatment with pregnenolone-16alpha-carbonitrile stimulated protein synthesis in controls but had no preventive effect in DMN-treated rats and did not reduce the extent of DNA alkylation in vivo.

Alkylation↗
PubMed1976

A radioprotective effect of calcium chloride in combination with cystamine, mexamine, and hypoxemic hypoxia in mice.

A mild protective effect of a solution of CaCl2 (3.21 g%) injected in a volume of 0.2 ml i.p. 30 minutes prior to irradiation was demonstrated in experiments with male mice in the strain C 57 B1/10. The pre-irradiation administration of CaCl2 increased the LD50/30 by approximately 60R as compared with control animals, to which an isoosmotic NaCl solution was injected. A more pronounced decrease of the post-irradiation mortality of the animals was reached by combined administration of CaCl2 with chemical protectors- cystamine or mexamine administered in relatively low s.c. doses, as well as by a combination of CaCl2 with the protective action of hypoxemic hypoxia. Under the conditions of combined protection, the administration of CaCl2 increased LD50/30 by approximately 100 to 130R. A higher rate of formation of endogenous spleen hematopoietic colonies was observed in the animals protected by calcium. Possible mechanisms of the radioprotective effect of calcium on the level of the hematopoietic stem cells are discussed.

Animals↗
PubMedDate not supplied

[The mechanism of the radioprotective action of cystamine and mexamine].

It was found that at the time when cystamine and mexamine exert their maximum radioprotective action DNA synthesis rate decreases in bone marrow cells, the ratio between the colony-forming units in the bone marrow and peripheral blood changes, and functional activity of neutrophils increases.

5-Methoxytryptamine↗