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PubMed1985

Effects of 5-acetylspiro[benzofuran-2(3H),1'-cyclopropan]-3-one, a new anti-ulcer agent, on experimental acute and chronic ulcers.

The effects of 5-acetylspiro[benzofuran-2(3H),1'-cyclopropan]-3-one (AG 629), a newly synthesized compound, on various experimentally induced ulcers were investigated. Oral or intraduodenal administration of AG 629 in a dose range of 25-100 mg/kg inhibited water-immersion stress ulcer, exertion ulcer, Shay ulcer, indometacin- and acetylsalicylic acid (ASA)-induced gastric ulcer, and indomethacin-induced small intestinal ulcer in rats, histamine-induced gastric ulcer in guinea pigs, and ASA-induced gastric ulcer in dogs, though it was not effective against cysteamine-induced duodenal ulcer in rats. AG 629 in doses of 6.3-25 mg/kg p.o. twice a day significantly promoted the healing of acetic acid- or thermal-cortisone-induced gastric ulcers and acetic acid-induced duodenal ulcers in rats. AG 629 (25-100 mg/kg i.d.) inhibited the secretion of gastric acid and pepsin in pylorus-ligated rats and the acid secretion stimulated by distension of the rat stomach with air, whereas this compound did not affect acid secretion stimulated by histamine, pentagastrin, carbachol or 2-deoxy-D-glucose. This study shows that AG 629 has both prophylactic and curative effects on various ulcers. The anti-ulcer effect of this agent seems to be mediated primarily by increasing mucosal resistance and secondarily by an antisecretory activity.

Acetates↗
PubMed1977

Comparative studies on the influence of some radioprotectors on the postirradiation hydrolytic function of subcellular fractions of pancreas.

Comparative studies on the influence of the two radioprotectors Fenchlorfos and cysteamine on the hydroproteolytic activity of pancreatic subcellular fractions of rats were carried out. The animals were irradiated with the single dose of 800 R of X-rays. Biochemical estimation of lipase, beta-glucuronidase, acid phosphatase and catheptic (caseinolytic) activity were done 24 hours after exposition. The two radioprotective substances have a lot of common in their action against hydrolytic activity. They induce the decrease of some enzymes of subcellular fractions we checked both in control as well as in irradiated groups. The ambivalent influence of Trichlorfon on the lipase activity in granules and supernatant fraction seems to be of interest.

Animals↗
PubMed1982

A reinterpretation of phosphatase-N.

In order to determine the substrate specificity of the alkaline phosphatase (APase) which appears in murine lymphomas, two substrates were chosen. p-Nitrophenyl phosphatase (pNPP), the standard substrate, has an oxygen-phosphorus (O-P) bond. Cysteamine-S-phosphate (CASP) has a sulfur-phosphorus (S-P) bond. It has been reported that murine lymphoma APase does not cleave the S-P bond of CASP. These results were not confirmed. Under all conditions tested, the murine lymphoma APase showed consistent hydrolysis of CASP at approximately one-third the rate of hydrolysis of pNPP. Biochemical characteristics used to confirm this include pH optimum, heat inactivation, kinetics, magnesium activation, L-homoarginine inhibition, EDTA inhibition, and activity remaining during stages of partial purification. It is concluded that the murine lymphoma APase shows a preference of pNPP as a substrate but does hydrolyse CASP at a lower rate. The conflict between our laboratory and that of Neumann's may be one of interpretation rather than data. Neumann shows similar data to ours in terms of the 3-fold ratio, but considers all hydrolysis of CASP as representative of 'normal' APase. She uses a formula to calculate the amount of lymphoma APase based on the ratio 1.9 which is the ratio of hydrolysis of pNPP to that of CASP in kidney tissue. Our interpretation would be that the same isozyme is hydrolyzing the S-P bond at one-third the rate that it hydrolyzes the O-P bond.

4-Nitrophenylphosphatase↗
PubMed1983

Determination of the radioprotective effects of topical applications of MEA, WR-2721, and N-acetylcysteine on murine skin.

Topical applications of MEA (beta-mercaptoethylamine or cysteamine), WR-2721 [S-2-(3-aminopropylamino)-ethylphosphorothioic acid], and N-acetylcysteine (NAC) were tested for their ability to protect the normal skin of the hind legs of mice against acute and late damage from single doses of 137Cs radiation. No significant protection was observed with either WR-2721 or NAC. MEA was shown to offer significant protection against acute skin damage in both buffered and unbuffered forms, but no significant protection against late contraction. The use of topical MEA on unanesthetized animals breathing carbogen (95% O2, 5% CO2) appears to give an enhanced level of radioprotection over that shown for anesthetized, air-breathing animals.

Acetylcysteine↗
PubMed1983

The effect of naloxone in different gastroduodenal ulcer models.

On the basis of our investigations it seems that: The opiate antagonist naloxone in a dose of 5.0 mg/kg has a significant protective effect in stress-ulcer model in the rat; No such effect was seen in drug (indomethacin) or cysteamine induced (duodenal) ulcer models; The interaction of naloxone with indomethacin seems to show a sex-difference.

Animals↗
PubMed1983

The effects of radioprotectors on DNA polymerase I-directed repair synthesis and DNA strand breaks in toluene-treated and X-irradiated Escherichia coli.

In Escherichia coli made permeable to nucleotides by toluene treatment, a DNA polymerase I-directed repair synthesis is induced by exposure to X rays. This repair synthesis may be amplified and easily measured through inhibition of DNA ligase action. In an effort to learn more of the relationship between X-ray-induced strand breaks in cellular DNA and the extent of this repair synthesis, experiments designed to compare the influence of radioprotectors on both strand-break production and repair synthesis have been carried out. The results show that cysteamine, sodium formate, and glycerol not only protect against strand breaks but also reduce DNA polymerase I-directed repair synthesis. However, I-, an efficient hydroxyl radical scavenger, is not as effective a protective agent against strand breaks and does not measurably affect repair synthesis in our system.

Cysteamine↗
PubMed1984

Gastric cytoprotective properties of SCH 32651, a novel antiulcer agent.

The antisecretory activity of SCH 32651 (3-amino-2-methyl-8-phenylmethoxyimidazo[1,2-a] pyrazine HCl . 1/3 H2O) has been described in a preceding paper. This report describes its gastric cytoprotective properties. SCH 32651 inhibited the gastric lesions due to ethanol in a dose-dependent manner (ID50 = 5 mg/kg p.o.) and exerted its maximal effect when given 30 min before ethanol and had a duration of at least 90 min at 30 mg/kg p.o. The activity of SCH 32651 against ethanol was unaffected by indomethacin pretreatment. Furthermore, SCH 32651 produced significant increases in gastric mucus release (10-100 mg/kg p.o.) and rapidly reversed ethanol-induced (30-100 mg/kg p.o.) fall in gastric potential difference (PD). SCH 32651 displayed significant antiulcer activity in indomethacin-(30-100 mg/kg p.o.), aspirin - (30-100 mg/kg p.o.), "aspirin + acid" - (10-100 mg/kg p.o.), reserpine - (10-100 mg/kg p.o.), stress - (30-100 mg/kg p.o.), and cysteamine (10-100 mg/kg p.o.) ulcers. The present data in conjunction with those reported in a preceding paper indicate that SCH 32651 is an orally effective novel antiulcer drug with both gastric antisecretory and cytoprotective properties.

Administration, Oral↗
PubMed1984

Genetic polymorphism of apolipoprotein E: a variant form of apolipoprotein E2 distinguished by sodium dodecyl sulfate--polyacrylamide gel electrophoresis.

The apolipoprotein E2 ( apoE2 ) variant that possesses a cysteine substituted for an arginine at residue 158 in the amino acid sequence E2( Arg158 ----Cys) can be distinguished by sodium dodecyl sulfate-polyacrylamide gel electrophoresis from other forms of apoE, including E3 (the parent form), E4( Cys112 ----Arg), E2( Arg145 ----Cys), and E2( Lys146 ----Gln). The E2( Arg158 ----Cys) migrates as a distinctly separable band with a higher apparent molecular weight than the other forms. Chemical modification of apoE2 ( Arg158 ----Cys) with sulfhydryl reagents (2-bromoethyl)-trimethylammonium bromide or cysteamine, which convert cysteine to arginyl or lysyl analogues, respectively, abolishes the difference in apparent molecular weight and results in the co-electrophoresis of E2( Arg158 ----Cys) with other apoE forms. The mobilities of the other apoE variants are not affected by these modifications. These results suggest that the substitution site at residue 158 is a key location, important in modifying the behavior of apoE and in modulating its apparent molecular weight on sodium dodecyl sulfate-polyacrylamide gels. Furthermore, the technique used in this study may be very helpful in distinguishing specific mutant forms of apoE2 .

Amino Acid Sequence↗
PubMed1981

Adrenocortical hemorrhagic necrosis: the role of catecholamines and retrograde medullary-cell embolism.

We investigated the pathogenesis of adrenal necrosis using animal models of the disease (induced by administration of acrylonitrile, cysteamine, or pyrazole) and human cases. Results of electron-microscopic and histochemical time-response studies with rat models revealed an early, retrograde embolization of medullary cells and cell fragments in the cortical capillaries that showed prominent endothelial injury. The experimental adrenal lesions were prevented by surgical removal of the medulla one month before administration of adrenocorticolytic chemicals, or by the administration of the alpha-adrenergic antagonist phenoxybenzamine hydrochloride. Histochemical staining for medullary (argyrophil) granules in human cases of adrenal necrosis demonstrated tissue fragments that stained positively for silver in vascular cortical spaces in nine of ten autopsy specimens and in all four surgical cases we reviewed. Thus, catecholamines released from the adrenal medulla and from the retrograde medullary emboli in the cortex may have a role in the pathogenesis of adrenocortical necrosis.

Acrylonitrile↗
PubMed1980

Characterization of the protective effect of radioprotective substances by means of long-term changes in oxygen consumption.

A comparison of long-term hypothermic effects of radioprotective substances and their protective effectiveness was carried out in mice after acute and prolonged irradiation. As radioprotective substances were used AET, cystamine, serotonine, 5-methoxytryptamine, cysteamine-S-phosphate, sodium fluoroacetate and some double combinations of these substances. The irradiation was carried out with dose rates 38.3 and 612.5 mGy/min, the hypothermic reaction was evaluated according to total oxygen consumption, measured during 5 hours after the drug administration. The results demonstrated the existence of a correlation between the suppression of metabolic processes and both short-term and long-term protective effectiveness of radioprotective substances. The protective effectiveness of a drug is the higher, the greater decrease of oxygen consumption is induced by this substance in the investigated time interval. An analogous dependence was also demonstrated between the duration of hypothermic and radioprotective effects. The found correlation is valid for both acute and prolonged irradiation (correlation coefficient 0.79-0.87; p < 0.01).

5-Methoxytryptamine↗
PubMed1982

[Effect of enkephalin and cimetidine on the occurrence and course of duodenal ulcers in rats].

A study was made of the effect of a synthetic enkephalin analog and cimetidinee on experimental duodenal ulcer in rats induced by cysteamine administration. The ulcers were demonstrated to heal within 4 weeks. It was noted that ulcer occurrence was preceded by the increased serum gastrin level. Administration to rats of the enkephalin analog accelerated ulcer healing to a greater extent than that of cimetidin. It is suggested that one of the mechanisms of enkephalin analog protective action might involve the prevention of the gastrin increased level.

Animals↗
PubMed1982

beta-hydroxyisobutyryl coenzyme A deacylase deficiency: a defect in valine metabolism associated with physical malformations.

An infant, born to parents who were first cousins had multiple physical malformations. An associated biochemical abnormality was suggested by the urinary excretion of cysteine and cysteamine conjugates of methacrylic acid. The coenzyme A (CoA) ester of this compound is an intermediate in the pathway of valine oxidation. Subsequent investigation revealed a deficiency of beta-hydroxyisobutyryl-CoA deacylase, an enzyme unique to valine metabolism. The enzyme defect results in accumulation of methacrylyl-CoA, a highly reactive compound, which readily undergoes addition reactions with free sulfhydryl groups. Tissue damage due to reactions between methacrylyl-CoA and important sulfhydryl-containing enzymes and cofactors may account for the teratogenic effects seen in this patient.

Abnormalities, Multiple↗
PubMed1982

On the cytoprotective action of sulfhydryl-containing substances.

Sulfhydryl substances (cysteine, glutathione, cysteamine and BAL) provide protection against experimental gastric ulcer induced by indomethacin while being ulcerogenous in stress-ulcer. Experimental data indicate the necessity to distinguish between "real" and "occasional" cytoprotective drugs.

Animals↗
PubMed1981

The oxidative half-reaction of liver microsomal FAD-containing monooxygenase.

The reactions of reduced forms of liver microsomal FAD-containing monooxygenase both with oxygen and with several oxygenatable substrates have been investigated using rapid reaction techniques. It was first shown that the pH optimum was at about 8.8 and that at pH values below 8 the stoichiometry was very nearly 1:1:1 for NADPH/(cysteamine or methimazole)/oxygen consumption, with only traces of H2O2 forming. Low temperatures (approximately 4 degrees C) were employed to better resolve kinetic intermediates occurring in the reaction. It was shown that in the absence of NADP+, substrate has no effect on the rate of reoxidation of reduced enzyme by O2. However, in the presence of NADP+ and the absence of substrate, the reduced enzyme reacts with O2 to form a remarkably stable C(4a)-hydroperoxyflavin species. This occurs in a reaction that saturates with respect to O2, implying the formation of a reversible complex with oxygen prior to the formation of the hydroperoxyflavin. This has been predicted by the steady state kinetics (Poulsen, L. L., and Ziegler, D. M. (1979) J. Biol. Chem. 254, 6449-6455). In the presence of NADP+, substrate increases the rate of reoxidation (by destabilizing the hydroperoxyflavin), but the rate is much slower than the reaction of reduced enzyme with O2 in the absence of NADP+. The stability of the hydroperoxyflavin permitted its preparation on the stopped flow apparatus for subsequent reaction with various substrates. This reaction involved the rapid formation of a species with a new spectrum which was indicative of a C(4a)-substituted flavin. Since this new species converts to oxidized flavin at about 2 min-1, which is equivalent to Vmax, it must be the rate-limiting step in the catalytic reaction. This new spectrum is likely due either to a substrate-hydroperoxyflavin species or to a product-hydroxyflavin species.

Aniline Compounds↗
PubMed1980

Nuclear magnetic resonance relaxation times for tissues of mice given radioprotective compounds.

The pharmacological actions of chemical radioprotective substances (superoxide dismutase, cysteamine, beta-aminoethylisothiouronium Br-HBr, and propylene glycol) on mouse tissues were studied by measurement of proton NMR relaxation times. Changes in 1/T1 and 1/T2 values were observed but could not be correlated in any simple manner with the radioprotective actions of the administered compounds. Small but statistically significance correlations between water content and 1/T1 or 1/T2 value were observed.

Animals↗
PubMed1981

Praomys (Mastomys) natalensis: animal model for study of histamine-induced duodenal ulcers.

Praomys (Mastomys) natalensis, an African rodent ranging in size between a mouse and a rat, is more susceptible to the induction of duodenal ulcers by constant infusion of exogenous histamine through an osmotic minipump implanted subcutaneously than other rodent species tested such as mouse, rat, or guinea-pig. By increasing the doses of infused histamine, there were increases in the incidence, intensity, and perforation rate of duodenal ulcers in Mastomys. The induction of duodenal ulcers in Mastomys by tetra- and pentagastrins was unsuccessful, probably because of the limited releasing capacity of the present minipump for use of these two peptides which were sparingly soluble in water. More soluble human synthetic gastrin I was approximately three to four times as potent as histamine for inducing duodenal ulcers in Mastomys. The susceptibility of Mastomys to the induction of duodenal ulcer by cysteamine appears to be comparable to that of rat. The complete suppression of histamine-induced duodenal ulcers of Mastomys was possible by repeated subcutaneous injections of cimetidine.

Animals↗
PubMed1995

DNA repair by thiols in air shows two radicals make a double-strand break.

Using agarose gel electrophoresis, we have measured the yields of DNA single- and double-strand breaks (SSBs and DSBs) for plasmid DNA gamma-irradiated in aerobic aqueous solution. The presence during irradiation of either of the thiols cysteamine or N-(2-thioethyl)-1,3-diaminopropane (WR-1065) resulted in a concentration-dependent decrease in the yield of SSBs and a much greater decrease in the yield of DSBs. This large differential protective effect was not produced by thioethers or an alcohol of structural similarity to the two thiols, suggesting that repair of DSB radical precursors by thiols is more efficient than for SSB precursors. These observations suggest the existence of a diradical intermediate in the formation of DSBs. The results argue against a major contribution by a single radical mechanism involving interstrand radical transfer via hydrogen abstraction by a peroxyl intermediate, since the half-life of this radical transfer reaction appears to be significantly greater than the lifetime of the intermediate.

Cysteamine↗
PubMed1975

[Phalloidin antagonists 4th communication: Thioctic acid, SH-compounds, rifampicin, choleretics, dexamethasone, estradiol, unspecific inhibitors, and ineffective compounds (author's transl)].

1. Thioctic acid used clinically in poisoning by A. phalloides, protected perfused livers and also isolated hepatocytes against phalloidin, when given in high concentrations. 2. Some SH-compounds like coenzyme A, dimercaprol, cysteine and cysteamine were found to be protective in different concentrations. 3. Rifampicin protects mice against lethal doses of phalloidin, and inhibits poisoning of isolated hepatocytes at low concentrations. 4. Some choleretic drugs like dehydrocholate, temoebilin (extr. cucumae xanth.), ethacrynic acid influenced phalloidin poisoning by inhibition of binding. 5. Doses of 0.2 to 4.0 mg dexamethasone added to 100 ml of perfusion medium did not protect perfused rat livers against 0.5 mg phalloidin. 6. Pretreatment of female rats with estrogens effected protection against phalloidin in vivo. The same procedure resulted in moderate decrease of phalloidin effects when the livers of pretreated animals were poisoned in vitro. In male rats estrogen pretreatment was less effective. Castration did not augment the protective effect. 7. Secophalloidin, a biologically inactive derivative, did not influence phalloidin poisoning in perfused livers, even when applied in excessive concentrations. 8. Concanavalin A, probably bound in the neighborhood of binding sites for phalloidin, did not protect perfused livers against phalloidin. 9 Diethyldithiocarbamate, a compound protecting livers against carbon tetrachloride and halothane, was ineffective in phalloidin poisoning. 10. Further protective actions of Evans blue, of some phenanthrolines and of EDTA are discussed. 11. Pretreatment of animals with hepatotoxic compounds (CCl4, CHCl3, cinchophen) decreased the toxicity of phalloidin in vivo. Possible mechanisms are discussed.

Animals↗