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PubMed1999

Photorheological Effects in Aqueous Micellar Tetramethylammoniumhydrogen-2-dodecyl Malonate via Photodimerization of Acridizinium Bromide.

Aqueous solutions of tetramethylammoniumhydrogen-2-dodecyl malonate (TMHM) were investigated rheologically in the absence and presence of monomeric and photodimerized acridizinium bromide as solubilizates. Upon constant shearing a viscosity increase (accompanied by viscoelasticity) was observed in a certain range of TMHM concentration after an induction period. This indicates the formation of shear induced structures. Viscoelasticity was characterized via stress relaxation experiments revealing a single relaxation process with time constants of 0.2-0.3 s mostly. At certain shear rates a temporal oscillation of viscosity was observed. In the presence of acridizinium bromide the elasticity was reduced and the TMHM concentration range of viscoelastic flow was narrowed while relaxation time constants remained constant. Photodimerization of acridizinium bromide (performed in situ) reverted the effects induced by the monomers. Copyright 1999 Academic Press.

Journal Article↗
PubMed2002

Kinetic micellar effects in tetradecyltrimethylammonium bromide-pentanol micellar solutions.

The reactions 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane + OH(-) and 2-(p-nitrophenyl)ethyl bromide + OH(-) were studied in tetradecyltrimethylamonium bromide, TTAB, and TTAB-pentanol micellar solutions. The influence of changes in the surfactant concentration as well as changes in the hydroxide ion concentration on the observed rate constant was investigated. If changes in the cmc and ionization degree provoked by the presence of the different amounts of n-pentanol in the micellar solutions are taken into account, the experimental kinetic data can be rationalized quantitatively by using the PIE model. Assuming that the ion-exchange equilibrium constant, K(OH(-)/Br(-)), for the competition between the bromide and the hydroxide ions in all TTAB and in TTAB-pentanol micellar solutions studied is the same, a good agreement between the theoretical and the experimental kinetic data was found in all the micellar media for the two processes studied. This assumption was checked by experimentally determining the ion-exchange equilibrium constant K(OH(-)/Br(-)) in TTAB and TTAB-pentanol micellar solutions through a spectroscopic method, results showing that the presence of n-pentanol does not affect substantially the value of K(OH(-)/Br(-)). The second-order rate constants obtained from the fittings decrease slightly when the amount of pentanol increases, being greater than that in aqueous solution. This acceleration can be explained considering that micelles accelerate the reactions in which the charge is delocalized in the transition state.

Chlorobenzenes↗
PubMed1980

Binding kinetics of vinyl chloride and vinyl bromide at very low doses.

Vinyl chloride and vinyl bromide are metabolically activated by liver microsomal enzymes to intermediates that covalently bind to proteins and nucleic acids. Several lines of evidence suggest the involvement of the epoxides, i.e., chloroethylene oxide or bromoethylene oxide. Proven targets for alkylation are adenine, cytosine and guanine moieties in nucleic acids, and sulfhydryl groups of proteins. For all the halogenated ethylenes studied so far, including vinyl chloride and vinyl bromide, metabolism in vivo is a dose-dependent, saturable process. The metabolic capacity of rats is saturated at atmospheric concentrations of 250 ppm vinyl chloride and 55 ppm vinyl bromide. As recent reports describe a diminishment of hepatocellular glutathione in rats after exposure to vinyl chloride concentrations of 50 ppm and more, we carried out a series of experiments measuring covalent binding of vinyl chloride metabolites after exposure to different concentrations of 14C-vinyl chloride. In all of these experiments, including one of an exposure to only 2 ppm vinyl chloride, hepatic covalent protein binding was related to the dose of vinyl chloride which was actually metabolized, and the ratio between bound and metabolized material was constant. This strongly suggests that hepatic glutathione levels must have only a very limited impact on covalent protein binding of vinyl chloride metabolites, an assumption which is supported by a lacking effect of a pretreatment with diethylmaleate. A scheme of hepatocellular compartimentation of metabolic steps is proposed which serves to explain these findings.

Alkylation↗
PubMed1990

Neomycin inhibits mastoparan-induced lactate dehydrogenase release, ethidium bromide accumulation, and intracellular fluorescein depletion in MDCK cells.

Mechanisms of cell death induced by toxins probably involve one or more processes such as inhibition of protein synthesis and impairment of plasma membrane integrity leading to an increase in membrane permeability. Since one of the possible actions of mastoparan, a cationic tetradecapeptide from wasp venom, is to perturb membrane phospholipids resulting in an increase in membrane permeability, we studied the effect of chemically synthesized mastoparan on lactate dehydrogenase release (LDH), ethidium bromide and fluorescein accumulation in Madin-Darby Canine Kidney (MDCK) cultured cells. Our results demonstrated that mastoparan induced cytosolic LDH release, ethidium bromide accumulation and intracellular fluorescein depletion in MDCK cells. Neomycin, a polycationic aminoglycoside, interacts with anionic polyphosphoinositides at the plasma membrane. Since both mastoparan and neomycin are cationic peptides and react with the negatively charged membrane phospholipids, we studied the interaction of these two peptides on membrane permeability. Our results demonstrated that neomycin inhibited mastoparan-induced LDH release, ethidium bromide accumulation and intracellular fluorescein depletion.

Animals↗
PubMed1990

Effects of cimetropium bromide on gallbladder contraction in response to oral and intraduodenal olive oil.

To evaluate the influence of the stomach and the cholinergic system on gallbladder contraction induced by physiological stimuli, the reduction in gallbladder volume in 7 healthy volunteers has been studied by real-time ultrasonography after the oral and intraduodenal administration of olive oil, preceded by pretreatment with cimetropium bromide or placebo. After an overnight fast, each subject swallowed 50 ml olive oil or it was administered through a naso-duodenal tube in the proximal duodenum. Cimetropium bromide 5 mg or placebo was given intravenously under double-blind control. After the placebo pretreatment, gallbladder contraction was greater and faster after intraduodenal oil than after oral oil. Cimetropium bromide decreased the extent, velocity and duration of gallbladder contraction induced by intraduodenal olive oil but it only reduced the velocity of the contraction induced by oil given orally. It is concluded that in normal human subjects the stomach modulates the extent and velocity of postprandial gallbladder contraction and that anticholinergic agents antagonize the gastric and duodenal phases of the response of the gallbladder to a meal.

Administration, Oral↗
PubMed1990

A comparative investigation of the metabolism of methyl bromide and methyl iodide in human erythrocytes.

Human erythrocyte cytoplasm was incubated in head space vials with either methyl bromide or methyl iodide. The decline in concentration of the two methyl halides was monitored by gas chromatography. Simultaneously, the production of S-methylglutathione was determined by thin layer chromatography. In parallel experiments, boiled erythrocyte cytoplasm was used in order to determine non-enzymatic conjugation. Furthermore, inhibition experiments with sulfobromophthalein were performed. The results were compared with previous findings on the metabolism of methyl chloride. In contrast to methyl chloride, both methyl bromide and methyl iodide showed a significant non-enzymatic conjugation with glutathione. In addition, an enzymatic conjugation could be observed in the erythrocyte cytoplasm of the majority of the population, whereas a minority lacks this enzymatic activity. This is consistent with findings on methyl chloride. Inhibition experiments show that a minor form of the erythrocyte glutathione transferase may be responsible for the enzymatic conjugation. Of the three monohalogenated methanes, methyl bromide is the substrate with the highest affinity for the conjugating enzyme(s). In the case of methyl iodide, non-enzymatic reaction overweighs the enzymatic process. There are possible implications of the results for occupational health and the toxicity of the substances.

Cytoplasm↗
PubMed1987

Comparison of the effects of inhaled calcium antagonist verapamil, sodium cromoglycate and ipratropium bromide on exercise-induced bronchoconstriction in children with asthma.

Fifteen children with exercise-induced asthma (EIA) participated in a double-blind trial comparing the protective effects of inhaled sodium cromoglycate (20 mg/2 ml), ipratropium bromide (500 micrograms/2 ml) and verapamil (5 mg/2 ml). Saline was used as control. There was no significant difference in base line pulmonary function before and after the administration of each agent. After exercise the maximal percentage fall in the forced expiratory volume in 1 s (FEV-1) (means and SD) were 40.9 +/- 17.2 after inhalation of saline, 15.3 +/- 11.7 after sodium cromoglycate, 36.2 +/- 21.4 after verapamil and 21.7 +/- 17.7 after ipratropium bromide. The inhibitory effects of sodium cromoglycate and ipratropium bromide were significant whereas verapamil failed to produce any effect. To see if a double dose of verapamil is more effective, nine different children with EIA were provoked by the same standardized treadmill running after giving a placebo (4 ml saline) and after verapamil (10 mg in 4 ml). Despite the double dose, again verapamil was ineffective even though the protection index doubled that obtained with the lower dose. The results suggest that the calcium antagonist (verapamil) had almost no effect on the prevention of EIA in the children studied.

Administration, Inhalation↗
PubMed1976

Tissue distribution of 14C-heteronium bromide: radioactivity levels at different time intervals after oral administration in the rat.

The tissue distribution of radioactivity after oral administration to rats of 14C-heteronium bromide is measured by liquid scintillation counting and the results expressed as specific activity and percentage of administered radioactivity. From the data obtained in blood, liver, kidney. stomach, duodenum, cecum, large intestine and stool some conclusions can be drawn. Heteronium bromide undergoes a rapid systemic absorption, the radioactivity being present as early as 15 min from the administration, in all the tested organs. The blood levels show two peaks: one at 120 min and a second at 360 min. This diphasic behaviour can be explained either by the presence of an active enterohepatic circulation, as indirectly indicated by the data from liver and duodenum, or by a transient shift of the molecule from blood to other tissues, rich in polysulfuronic acids. The principal route of excretion is represented by the kidney, where consistent levels are reached at 120 min, while the intestinal route becomes evident at 240 min and reaches its maximum at 720 min. The complete metabolic cycle of the compound is long lasting, since in all the tested tissues, marked radioactivity levels are still present after 720 min. The pharmacokinetic profile obtained, suggesting a long persistence of the drug and/or of its metabolites in the organism, is in agreement with previous pharmacodynamic data showing a long lasting action for heteronium bromide.

Administration, Oral↗
PubMed1984

Protective effect of oral oxyphenonium bromide, terbutaline and theophylline against the bronchial obstructive effects of inhaled histamine, acetylcholine and propranolol.

The protective effects of oxyphenonium bromide, terbutaline and theophylline were compared in 8 asthmatic patients by determination of the degree of non-specific airway reactivity after 1 week of oral treatment according to a fixed dose scheme in a double-blind random order: oxyphenonium bromide 3 X 10 mg; terbutaline 3 X 5 mg; theophylline 2 X 300 mg and placebo. Controlled, standardized inhalation provocation tests were carried out with histamine, acetylcholine and propranolol. The study was monitored by measuring blood concentrations of the 3 drugs, and their effect on the plasma cAMP concentration was also determined. Significant protection by oxyphenonium bromide against the bronchial obstructive effects of acetylcholine and propranolol was observed, but not against the effect of inhaled histamine. The other two drugs provided no significant protection against the inhaled agents. The absence of any protective effect of terbutaline and theophylline might have resulted from too low a blood concentration. The observed differences in protection could not be explained by changes in pulmonary function. The study suggests dissociation between the bronchodilating effect of a drug and its protective effect against inhaled substances.

Acetylcholine↗
PubMed1987

Airway response to salbutamol and to ipratropium bromide after non-selective and cardioselective beta-blocker.

Eight healthy men were randomly assigned in a latin square order to receive single doses of placebo, tertatolol 5 mg, propranolol 80 mg and atenolol 100 mg at 7-day intervals. Resting heart rate and pulmonary function were measured 10 min before and over the 240 min following dosing, and then 15 min after inhalation of salbutamol 200 micrograms and ipratropium bromide 40 micrograms. The three beta-blockers caused similar reductions in resting heart rate throughout the study, whereas placebo had no effect. The three beta-blockers, like placebo, produced no significant change in pulmonary function during the 240 min after dosing. The bronchodilator response to salbutamol after atenolol and placebo was preserved, whereas it was reduced after administration of either of the non-selective beta-blockers, tertatolol and propranolol. An unequivocal response of the airways to ipratropium bromide was observed after tertatolol and propranolol, which was much greater than after atenolol. No response was observed after placebo. Thus, despite bronchial beta 2-blockade, by non-selective beta-blockers, bronchodilatation was definitely produced by ipratropium bromide, confirming the predominant role of the parasympathetic system in the autonomic innervation of normal human airways.

Adrenergic beta-Antagonists↗
PubMed1977

The action of structural analogues of ethidium bromide on the mitochondrial genome of yeast.

We have studied the effects on the yeast mitochondrial genome of four analogues of ethidium bromide, in which the phenyl moieyt has been replaced by linear alkyl chains of lengths varying from seven to fifteen carbon atoms. These analogues are more efficient than ethidium bromide in inducing petite mutants in Saccharomyces cervisiae. The drugs also cause a loss of mtDNA from the cells in vivo; however these analogues are in fact less effective inhibitors of mitochondrial DNA replication per se, as shown by direct in vitro studies. It is concluded that these analogues are more efficient than ethidium bromide in causing the fragmentation of mitochondrial DNA in S. cervisiae.

DNA, Mitochondrial↗
PubMed1985

Encapsulation potential of a trypanocidal drug homidium bromide in bovine carrier erythrocytes.

Bovine red blood cells (RBC) were made to entrap homidium bromide, a trypanocidal drug. Hypotonic dialysis resulted in 0.3 mg drug encapsulated per milliliter of RBC. Homidium bromide had no untoward effects on the encapsulation of a marker 14C-sucrose. However, RBC containing homidium bromide had a mean cell volume (MCV) larger than that of sham-loaded cells. EDTA did not reverse the effects of the drug on the MCV. The in vitro drug efflux rate was 0.097 mg/h. The effects of drug on the 24-h circulating survival was determined, and 24-h cell survival was reduced from 80% to 50%.

Animals↗
PubMed1980

Fusion of liposome membranes by the n-alkyl bromides.

It has been found that the n-alkyl bromides are capable of inducing the fusion of unilamellar liposomes. These compounds can bring about fusion of liposomes composed of either pure phosphatidylcholine or phosphatidycholine+phosphatidic acid. Fusion of unilamellar liposomes gives rise to multilamellar structures, the morphology of which has been examined by negative staining and freeze-fracture techniques. It has been shown by microelectrophoresis that the n-alkyl bromides have no effect on the surface charge of liposomes, and fusion has been further characterized by use of light scattering and differential scanning calorimetry, the latter indicating that true mixing of the fatty acyl chains occurs upon fusion. Finally, fusion occurs at n-alkyl bromide levels below that required to saturate the aqueous phase of the system.

Calorimetry, Differential Scanning↗
PubMed1993

Polymorphism of glutathione conjugation of methyl bromide, ethylene oxide and dichloromethane in human blood: influence on the induction of sister chromatid exchanges (SCE) in lymphocytes.

A hitherto unknown glutathione-S-transferase in human erythrocytes displays polymorphism: three quarters of the population ("conjugators") possess, whereas one quarter ("non-conjugators") lack this specific activity. A standard method for the identification of conjugators and non-conjugators with the use of methyl bromide and gas chromatography (head space technique) is described. Three substrates of the polymorphic enzyme, methyl bromide, ethylene oxide and dichloromethane (methylene chloride), were incubated in vitro with individual whole blood samples of conjugators and non-conjugators. All three substances led to a marked increase of sister chromatid exchanges (SCE) in the lymphocytes of the non-conjugators but not in those of conjugators. A protective effect of the glutathione-S-transferase activity in human erythrocytes for the cytogenetic toxicity of these chemicals in vitro is thus confirmed. Since the enzyme activity is not found in erythrocytes of laboratory animals, species extrapolations for risk assessment of methyl bromide, ethylene oxide and dichloromethane should be reconsidered.

Erythrocytes↗
PubMed1981

Anti-spasmodic effect of prifinium bromide on the proximal and distal colon in patients with diverticular disease.

In 5 patients with diverticular disease, colonic motilities of the proximal and distal colon were recorded using the ERBI method. The motilities were studied during resting, after prostigmin 0.5 mg i.m. injection and after prifinium bromide 7.5 mg i.m. injection, with the following results: After prostigmin colonic motility of the proximal colon became significantly greater than that of the distal colon. Prifinium bromide inhibited the prostigmin-induced hypermotility markedly. It was demonstrated that this drug has an antispasmodic action not only on the distal colon but also on the proximal colon. Prifinium bromide was an antispasmodic drug which brought about a rapid effect which appears within 3 minutes after injection. The effect persisted for about 1 hour.

Colon↗
PubMed1982

Neostigmine reversal of D-tubocurarine and pancuronium bromide combinations in man.

This study measured the neostigmine reversal of a non-depolarizing block in 17 patients, each given d-tubocurarine and pancuronium bromide in an alternating sequence. Reversal times were similar to those previously reported for pancuronium bromide alone. It is concluded that the anaesthetist may alternate between d-tubocurarine and pancuronium bromide without fear of difficulty with neostigmine reversal.

Adult↗
PubMed1990

Homidium bromide as a chemoprophylactic for cattle trypanosomiasis in Kenya.

Homidium bromide was used in a strategic chemoprophylactic regime to control trypanosomiasis in Boran cattle in Kenya. Trypanosome infection rates in cattle receiving homidium bromide prophylaxis were compared with those in control cattle which received no prophylaxis but were treated with diminazene aceturate when infected. Homidium bromide was administered twice during the year after which no infections were detected for periods of nineteen weeks and seventeen weeks respectively. The drug sensitivity of the infecting trypanosomes is believed to be a major factor in determining the duration of prophylaxis.

Animals↗
PubMed1986

Effect of ipratropium bromide on airway mucociliary function.

Airway mucociliary dysfunction leading to a depression of mucus transport has been demonstrated in patients with acute and chronic bronchitis, cystic fibrosis, and bronchial asthma; use of bronchodilators that might further impair mucociliary function, therefore, generally has been discouraged. Atropine and ipratropium bromide are cholinergic antagonists that are effective bronchodilators in various clinical settings. Atropine has been shown to block the production of respiratory secretions in response to cholinergic stimulation, but to have no effect on baseline secretions. Atropine has also been clearly demonstrated to depress ciliary beat frequency and to slow airway mucociliary clearance, whereas the short-term and long-term administration of ipratropium bromide at higher than clinically recommended doses seems to lack these effects. No satisfactory explanation has thus far been offered for this difference between the two cholinergic antagonists. Nevertheless, with respect to airway mucociliary function, ipratropium bromide appears to be preferable to atropine in the treatment of obstructive airways disease.

Animals↗