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At least 1,207 records · Page 67Linked to original sources
PubMed1998

Vascular approach to gastroduodenal ulceration: new studies with endothelins and VEGF.

Endothelins (ET) and VEGF/VPF (vascular endothelial growth factor/vascular permeability factor) are products mainly of endothelial cells, which are also regulated via autocrine and paracrine pathways by these peptides. As a follow-up to our focus on vascular factors in ulcer pathogenesis and healing, we review here our recent studies with ET-1 and VEGF/VPF in animal models and human subjects. Our new results demonstrated a rapid and time-dependent release of ET-1 into the systemic circulation after intragastric administration of ethanol or HCI in rats, and ethanol in humans. The ET-1 release preceded the development of hemorrhagic erosions in both species and might be used as a diagnostic tool to noninvasively quantify acute gastric mucosal lesions. The development of solitary duodenal ulcers in the rat was preceded only by an organ- (involving only the duodenum and not the stomach) and molecule-specific (induced only by cysteamine and not by the nonulcerogenic analog ethanolamine) rapid local release of ET-1. The severity of cysteamine-induced duodenal ulcers was dose-dependently decreased by pretreatment with ET-1 antibodies or antagonist bosentan. A single intragastric dose of VEGF/VPF resulted in gastroprotection against ethanol, while daily intragastric treatment with the peptide for three weeks stimulated angiogenesis in the base of cysteamine-induced duodenal ulcers and accelerated ulcer healing. Thus, modulation of vascular factors seems to be sufficient for both acute gastroprotection and chronic duodenal ulcer healing.

Animals↗
PubMed1981

Treatment of severe acetaminophen poisoning with intravenous acetylcysteine.

Intravenous (IV) acetylcysteine, cysteamine, and methionine treatments were compared in patients with severe acetaminophen poisoning; a control group consisted of patients receiving supportive therapy only. Acetylcysteine proved the safest and most effective mode of treatment. Acetylcysteine was effective in preventing liver damage, hepatic failure, renal damage, and death when given eight to ten hours after poisoning. When treatment was delayed for ten to 24 hours, results were the same as in the supportive-therapy group. The alanine aminotransferase (ALT) activity remained normal in 76% of the patients treated within ten hours, as compared with 40% in both cysteamine- and methionine-treated groups and with 16% in the supportive-therapy group. The ingestion-treatment interval for complete protection with all three drugs was eight hours; beyond that time, the incidence of damage increased steadily. After 15 hours, all treatments were pointless. Based on my experience, IV administration is preferable, since nausea and vomiting may limit the effectiveness of oral therapy.

Acetaminophen↗
PubMed1999

Electrophoretic analysis of oxidative modification of apolipoprotein E in very low density lipoprotein from fresh human plasma.

Ferrous ion-induced oxidative modification of apoE in lipid peroxidation of human very low density lipoprotein (VLDL) and the role of the cysteinyl group, present in apoE3 but absent in apoE4, were examined. Fresh human VLDL was obtained from healthy volunteers with different apoE phenotypes as determined by isoelectric focusing (IEF). The VLDL was oxidized by incubating with FeSO4. The time course of the lipid peroxidation was determined by thiobarbituric acid (TBA) assay. The sequential oxidative modification of the apoE was demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting with an anti-apoE antibody. To modify the cysteinyl group of apoE3, the VLDL from the apoE3/3 subject was pretreated with cysteamine before the TBA assay and electrophoresis. The ferrous ion-induced peroxidation of the VLDL was pH-dependent, with increased reactivity at acidic pH ranges. In the initial stage of the lipid peroxidation of the VLDL, aggregates were formed involving apoE dimers and apoB via disulfide bonds, followed by the intra- and intermolecular cross-linkings of apoE monomers. The VLDL with apoE3/4 showed a shorter lag time than the VLDL with apoE3/3 in the TBA assay, suggesting a lower antioxidative effect with apoE3/4. The apoE3/3 pretreated with cysteamine showed the patterns of apoE3/4 in IEF and SDS-PAGE with immunoblotting, but it did not show the shortened lag time in the TBA assay. This suggests that factors other than cysteinyl groups contribute to the reduced antioxidative activity of apoE4.

Apolipoproteins B↗
PubMed1979

Studies on the nature and regulation of the cellular thio:disulphide potential.

Microsomal fractions separated from homogenates of liver, kidney and corpora lutea contain a monooxygenase (dimethylaniline monooxygenase [N-oxide forming], EC 1.14.13.8) that catalyses NADPH- and oxygen-dependent oxidation of cysteamine to cystamine. The monooxygenase purified to homogeneity from hog liver also catalyses oxygenations of diverse xenobiotics, but it does not catalyse oxidation of any other physiological sulphur- or nitrogen-containing compounds. All the available evidence indicates that cysteamine is the physiological substrate for the monooxygenase, and the oxidation of this thiol to the disulphide may be a significant source of disulphide maintaining the cellular thiol:disulphide potential. The concentration of protein-low molecular weight mixed disulphide is a function of this potential. Changes in concentration of this protein-mixed disulphide reflect changes in thiol:disulphide balance. At constant substrate concentrations the potential would depend primarily on activity of the cytosol glutathione reductase (NAD(P)H: oxidized-glutathione oxidoreductase, EC 1.6.4.2) relative to that of the membrane-bound monooxygenase. In hepatic tissue from adult mice and hamsters there is a correlation between the concentration of protein-mixed disulphide and the activity of the monooxygenase relative to the reductase. Hepatic glutathione reductase is relatively constant in mice, but the monooxygenase is much higher in the female than in the male. After gonadectomy monooxygenase activity decreases in the female and increases in the male. Activities are restored to control levels by treating males with testosterone and females with progesterone. Testosterone decreases and progesterone increases activity. These two hormones apparently regulate the level of this enzyme in hepatic tissue.

Animals↗
PubMed2003

Duodenal ulcer prevalence: research into the nature of possible protective dietary lipids.

The varying geographical prevalence of duodenal ulceration has suggested a relationship to staple diet. Previous experiments on animal peptic ulcer models showed that certain foods, particularly the lipid fraction, are ulceroprotective. This paper reports experiments on animal models further to investigate the nature of the protective substances in the most active lipid, that of horse gram. The free fatty acids and triglycerides, sterols, sterol esters and phospholipids from horse gram were extracted and tested for protective activity on rat peptic ulcer models: the pyloric ligation model which is chronic, involving 14 days pre-feeding, and two acute models using ethanol or cysteamine to induce ulceration. The results showed that sterol esters, but not sterols, were protective in the pyloric ligation model. Sterols were protective in the acute models using ethanol-induced and cysteamine-induced ulceration. Phospholipids were protective in both types of model. The free fatty acids and triglycerides gave no protection using the pyloric ligation model. The presence of sterols, sterol esters and phospholipids in the lipid fraction of foods in staple diets may account for the low prevalence of duodenal ulcer in certain geographical areas, despite a uniformly high prevalence of Helicobacter pylori infection.

Animals↗
PubMed2001

Comparison of different protein immobilization methods on quartz crystal microbalance surface in flow injection immunoassay.

In this study, a quartz crystal microbalance (QCM) system operated repetitively in flow injection analysis (FIA) mode, is reported. Four immobilization approaches of seven different methods include: (i) physical adsorption; (ii) two thioamine thiolation methods, using cysteamine and cystamine for gold chemisorption and further coupling; (iii) two oxidized dextran spacer methods, coupling of cysteamine and cystamine thiolated QCM surface with periodate-oxidized dextran for further Schiff acid-base reaction; and (iv) two thiol-gold chemisorption-based self-assembled monolayer (SAM), applying short-chain, C(3), and long-chain, C(11), mercapto fatty acids to insolubilize human serum albumin (HSA) on QCM surface. Effects of these protein immobilization methods on FIA immunoassay of anti-HSA were compared. At the 0.01 mg/ml anti-HSA level, the lowest analyte concentration tested, the SAM using 11-mercaptoundecanoic acid as QCM surface activating agent generated a larger frequency shift than the other immobilization methods. This implied that the use of thiolated long-chain fatty acid constructed as self-assembled monolayer may thereby potentially be a useful protein immobilization method in QCM-FIA application.

Absorption↗
PubMed1993

Colocalization of organelle-specific proteins to autofluorescent astrocyte granules by laser scanning confocal microscopy.

Astrocytes in aging periventricular brain regions and in cysteamine-treated neonatal brain cell cultures contain cytoplasmic inclusions that exhibit an affinity for Gomori stains, orange-red autofluorescence, and non-enzymatic peroxidase activity. In order to delineate the cellular constituents participating in the biogenesis of these astrocytic inclusions, colocalization of FITC-immunolabeled organelles to the red autofluorescent granules was analyzed using a laser scanning confocal imaging system. Areas of true colocalization exhibited yellow fluorescence which persisted in Z-axis image reconstructions. We observed no colocalization of catalase- and PMP70-positive peroxisomes or the Golgi apparatus to the autofluorescent inclusions. The rough endoplasmic reticulum exhibited infrequent dot-like regions of colocalization consistent with previous electron microscopic observations. A minority of early endosomes colocalized to the autofluorescent inclusions in perinuclear cytoplasm. There was extensive colocalization of lgp120-labeled lysosomes to larger autofluorescent granules in close proximity to the nucleus whereas smaller autofluorescent granules often remained unlabeled. A macroautophagic process involving lysosomes and to lesser extent, early endosomes and the rough endoplasmic reticulum, may participate in the biogenesis of autofluorescent astrocytic inclusions in cysteamine-treated glial cultures and in the aging periventricular brain.

Aging↗
PubMed1997

A cellular stress model for the differential expression of glial lysosomal cathepsins in the aging nervous system.

Activation of the endosomal-lysosomal system and altered expression of various lysosomal hydrolases have been implicated in several senescence-dependent neurodegenerative disorders and occurs, to a lesser extent, in the course of normal brain aging. The progressive accumulation of autofluorescent, peroxidase-positive astrocytic granules represents a highly consistent biomarker of aging in the vertebrate CNS. The sulfhydryl agent cysteamine greatly accelerates the accumulation of these glial inclusions in situ and in primary brain cell cultures. We previously determined that these glial inclusions are derived from abnormal mitochondria which undergo fusion with lysosomal elements in a complex autophagic process. In the present study, we demonstrate that cysteamine suppresses cathepsin B mRNA levels and immunoreactive protein in cultured astroglia, whereas cathepsin D mRNA and protein levels are significantly augmented by CSH exposure in these cells. Moreover, cathepsin D (but not cathepsin B) exhibits robust colocalization to the red autofluorescent inclusions. Concordant with our in vitro observations, cathepsin B immunoreactivity is prominent in the hypothalamic ventromedial nucleus which accumulates few autofluorescent glial inclusions during aging and is relatively inapparent in the heavily granulated hypothalamic arcuate nucleus. Conversely, cathepsin D is prominent in the aging arcuate nucleus where it colocalizes to the autofluorescent inclusions and exhibits scant immunoreactivity in the adjacent ventromedial nuclear complex. In senescent astroglia, oxidative stress may down-regulate the cathepsin B gene as part of a concerted cellular stress (heat shock) response. Glial cathepsin D, on the other hand, resists stress-related inhibition and may play an important role in disposing of oxidatively modified mitochondria in the aging and degenerating nervous system.

Aging↗
PubMed1985

Central nervous system actions of somatostatin-related peptides.

Somatostatin-related peptides act within the central nervous system to influence adrenomedullary epinephrine secretion and thermoregulation. Cysteamine-induced depletion of brain somatostatin-related peptides or central administration of a somatostatin receptor antagonist alters adrenomedullary epinephrine secretion and thermoregulation in a predictable manner. The actions of cysteamine and the somatostatin receptor antagonist are reversed by administration of somatostatins into the central nervous system, supporting the hypothesis that endogenous brain somatostatin-related peptides are involved in the regulation of adrenomedullary epinephrine secretion and thermoregulation.

Adrenal Medulla↗
PubMed1981

Radioprotecting action of chemical compounds on gamma-irradiated yeast cells of various genotypes.

The radioprotective efficiency of cysteamine and cysteine has been studied on haploid and diploid, Saccharomyces cerevisiae, wild-type and various X-ray repair deficient rad mutants. The correlation between the radioprotecting action of cysteamine and cell repair capacity was demonstrated for diploid yeasts; such a correlation was not expressed for wild-type and rad mutant haploid yeast cells. It was concluded that the radioprotective action may involve cellular recovery processes, which may be mediated by a recombination-like mechanism, for which the diploid state is required. Liquid holding recovery was shown not to participate in radioprotection, judged by the absence of the influence of cysteine on the delay of the first postradiation budding as well as by the additive action of cysteine and liquid holding recovery.

Cysteamine↗
PubMed1976

Comparative studies on the specificity of anticlastogenic action in human lymphocytes in culture.

Comparative studies on human lymphocyte cultures yielded a certain specificity of the anticlastogenic action of the SH compounds l-cysteine, cysteamine, and beta-aminoethylisothiouronium (AET) as well as of the amide l-asparagine and the amino acid l-methionine. This specific anticlastogenic activity manifested itself in specific changes of the spectrum of aberration types induced by the clastogens and of the pattern of intercellular distribution of the induced aberrations. It was clearly dependent on the concentration of the anticlastogens but was also influenced by the used clastogen. The use of different culture media yielded some quantitative influences on the anticlastogenic activity, but fundamental changes in the spectrum of anticlastogenic action have not been observed except with cysteamine. The patterns of activity ascertained for the different anticlastogens specifically differed from those changes in the spectrum and pattern of distribution of aberrations induced by a mere reduction of the concentration for instance of Trenimon. Therefore a direct reaction between the protectors and the clastogen Trenimon as the cause of the observed anticlastogenic action was again excluded. The presented data are also discussed under the aspects of the hypotheses of aberration induction as well as of their importance for further antimutagen research.

Asparagine↗
PubMed1989

Somatostatin: a hypothalamic transmitter for thermoregulation in rats.

The changes in both the thermoregulatory responses and brain somatostatin (SS) levels produced by ambient temperature (Ta) changes were assessed in rats after they had been equilibrated to each of the Ta for a period of about 90 min. Cold exposure, in addition to elevating hypothalamic SS-levels, led to increased metabolism and cutaneous vasoconstriction at Ta = 8 degrees C. In contrast, heat exposure, in addition to lowering hypothalamic SS-levels, resulted in decreased metabolism and cutaneous vasodilation at Ta = 30 degrees C. Rats were chronically implanted with a hypothalamic cannula to allow intrahypothalamic injection of SS on the conscious rats. Direct administration of SS (0.1-0.3 micrograms) into the preoptic anterior hypothalamic area caused a dose-related rise in colon temperature at three Ta tested. The SS-induced hyperthermia was produced by increased metabolism at Ta = 8 degrees C, whereas at Ta = 30 degrees C, it was caused by cutaneous vasoconstriction. At Ta = 22 degrees C, the hyperthermia was caused by increased metabolism and cutaneous vasoconstriction. Systemic administration of cysteamine, in addition to lowering hypothalamic SS-levels, produced a dose-related fall in colon temperature at Ta of 8 degrees C and 22 degrees C. The hypothermia induced by cysteamine was produced by decreased metabolism at Ta = 8 degrees C, whereas at Ta = 22 degrees C, it was caused by both decreased metabolism and cutaneous vasodilation. The data indicate that the hypothalamic SS-levels mediate normal body temperature responses in rats.

Animals↗
PubMed1984

Iodination of myofibrils and myosin.

The relative reactivity of the tyrosine side chains in the proteins of skeletal muscle myofibrils was determined using iodination techniques. The destruction of ATPase activity of myofibrils and myosin by lactoperoxidase and chloramine-T iodination could be prevented by the attachment of cysteamine to the sulphydryl groups prior to the iodination reaction and subsequent regeneration with thioglycolate or dithiothreitol. Iodination using 1,3,4,6-tetrachloro-3 alpha, 6 alpha-diphenylglycoluril did not require cysteamine treatment for retention of full enzymatic activity. The specific activity of the different proteins varied markedly with desmin, troponin-T, and tropomyosin having the highest labelling with all three iodination procedures. In contrast the myosin light chains had low specific activity when labelled in myofibrils or intact myosin. The isolated light chains, however, were much more highly iodinated. It appears that iodination may be a useful technique for examining protein-protein interactions in the myofibril.

Adenosine Triphosphatases↗
PubMed1987

Early myoelectrical activity changes during gastric or duodenal ulceration in dogs.

Antroduodenal myoelectric activity and gastric transmural potential difference were recorded before and during fundic, antral, or duodenal ulceration in dogs. Gastric injury was obtained by electrocoagulation of the fundic or antral mucosa. Duodenal ulceration was induced by cysteamine injection which was accompanied by nausea or vomiting. Both antral electrocoagulation and cysteamine injection were also accompanied by antral dysrhythmia and a transient decrease of the gastric transmural potential difference. Effects of antral electrocoagulation were prevented by selective vagotomy. Since antral dysrhythmia disappeared as soon as the antral or duodenal ulcers became active, ie, within three days and 24 hr respectively, it is suggested that antral dysrhythmia is the result of antroduodenal stimulation and could thus not be assessed as a criterion of active ulceration.

Animals↗
PubMed1993

Effects of compound U74500A in animal models of gastric and duodenal ulceration.

Pretreatment with U74500A (up to 0.65 mg/100 g) failed to affect gastric lesions induced by 100% EtOH gavage in Sprague-Dawley rats. Topical application of U74500A did not reduce lesions induced by 40% EtOH in ex vivo gastric chamber preparations. However, pretreatment of rats with U74500A (0.65 g/100 g per os) reduced the incidence and severity of experimental duodenal ulcer induced by cysteamine HCl, and duodenal ulcer induced by cysteamine-HCl plus GABA. These results show U74500A to have powerful and specific antiduodenal ulcer actions. Pharmacologic analysis of organ-bath preparations of the small intestine show this compound to reduce intestinal contractility to applied cholinergic and serotonergic agonists. However, relaxations induced by electrical or nicotinic ganglionic stimulation were unaffected. U74500A itself caused concentration-dependent contractions.

Analysis of Variance↗
PubMed1993

Effects of epidermal growth factor on alkaline secretion and mucus formation in rat duodenum exposed to luminal acid.

The effect of epidermal growth factor (EGF) on alkaline secretion and mucus formation which serve as defenses against mucosal injury was investigated using a perfusion system of the proximal duodenum in rats in situ. In control rats, intravenous or intraduodenal administration of EGF (1 or 10 micrograms/kg/hr) had no effect on mucosal alkaline secretion at high (pH 2.5-3.0) or low (pH 3.0-5.5) luminal acidities. In cysteamine-treated rats (250 mg/kg weight, intramuscular injection), mucosal alkaline secretion by intravenous EGF (10 micrograms/kg/hr) increased significantly only at levels of high luminal acidity, whereas that by intraduodenal EGF (10 micrograms/kg/hr) increased greatly at both high and low luminal acidities. Analysis by a color image processor revealed that cysteamine greatly reduced the PAS-stained mucus in the duodenal mucosa and in Brunner's glands. Intraduodenal administration of EGF significantly increased the PAS-stained mucus in the duodenal mucosa, but not in Brunner's glands. These results indicate that EGF exerts the cytoprotective effect by stimulating alkaline secretion and mucus formation in the duodenal mucosa.

Animals↗
PubMedDate not supplied

Stimulation of mucosal uptake of selenium from selenite by some thiols at various sites of rat intestine.

The influence of several thiols (conc. 1 mmol/L) on mucosal uptake of 75Se from 75Se-labeled selenite (conc. 10 mumol/L) across the brush border of rat jejunum and cecum was investigated in vitro using a short-term uptake technique. L-Cysteine (L-Cys) stimulated 75Se uptake in the mid- and distal jejunum and cecum, but not in the proximal jejunum. The effect was maximal in the distal jejunum. D-Cys was less effective in the jejunum and similarly effective in the cecum. L-Leucine (L-Leu) and L-glutamic acid significantly reduced the stimulatory effect of L-Cys on Se uptake in the distal jejunum, whereas the respective effect of D-Cys was not diminished by L-Leu. Cysteamine stimulated mucosal 75Se uptake at all intestinal sites tested, whereas the effect of mercaptopyruvate was restricted to the distal jejunum. Thioglycolate also enhanced 75Se uptake in the distal jejunum. The stimulatory effects of L-Cys, mercaptopyruvate, and thioglycolate were Na(+)-dependent, whereas the effect of cysteamine also occurred in the absence of Na+. Mercaptosuccinate, D-penicillamine, ergothioneine, and thiosulfate did not enhance mucosal 75Se uptake. It is concluded from these findings that the reaction of some thiols with selenite results in Se compounds that are rapidly absorbed by the intestinal epithelium through various Na(+)-dependent and Na(+)-independent mechanisms. The high bioavailability of Se from selenite found by others might thus be the result of the presence of thiols in the gastrointestinal tract.

Analysis of Variance↗
PubMed2005

Hydrogen peroxide sensor based on horseradish peroxidase immobilized on a silver nanoparticles/cysteamine/gold electrode.

A third-generation hydrogen peroxide biosensor was prepared by immobilizing horseradish peroxidase (HRP) on a gold electrode modified with silver nanoparticles. A freshly-cleaned gold electrode was first immersed in a cysteamine-ethanol solution, and then silver nanoparticles were immobilized on the cysteamine monolayer, and finally HRP was adsorbed onto the surfaces of the silver nanoparticles. This self-assemble process was examined via atomic force microscopy (AFM). The immobilized horseradish peroxidase exhibited an excellent electrocatalytic response toward the reduction of hydrogen peroxide. The linear range of the biosensor was 3.3 microM to 9.4 mM, and the detection limit was estimated to be 0.78 microM. Moreover, the biosensor exhibited a fast response, high sensitivity, good reproducibility, and long-term stability.

Biosensing Techniques↗