bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of thyroid hormones on monoamine oxidase in the rat heart
Authors: Lyles G A , Callingham B A 
Published: April 2011

Abstract
The administration of thyroxine to young male rats produced an increase in the specific activity of their cardiac monoamine oxidase (MAO). A reduction in the circulating concentrations of thyroid hormones, brought about by 2-thiouracil, led to a decrease. The relative change in activity produced was greater with tyramine than with benzylamine as substrate. By following the time-course of the return of enzyme activity, with tyramine as substrate, after a single injection of pargyline in vivo, it was concluded that both excess and lack of thyroid hormones cause their effects on MAO activity by changing the rate of synthesis of the enzyme and not its degradation rate constant. The degradation rate constant did change with the age of the animal. The MAO activity, which increased towards tyramine as substrate in hyperthyroid rat hearts, behaved in the same way as that of controls to heat treatment, irreversible inhibition by pargyline or by clorgyline and also in Km determinations. The pattern for benzylamine oxidation was similar, except for the effect of the inhibitor clorgyline which shifted the plateau region of the double sigmoid inhibition curve significantly using enzyme from hyperthyroid rat hearts. The plateau region was also shown to be affected by the age of the animal. The possibility is discussed that the increased cardiac MAO activity produced by thyroid hormones and by the growth of the animal is mediated by that form of the enzyme primarily responsible for the oxidation of tyramine. Mixed substrate experiments suggested that tyramine oxidation could be inhibited competitively by benzylamine.
Phenylalanine, brain phenethylamine and motor activity in the rat
Authors: Snodgrass S Robert 
Published: April 2011

Abstract
Varying doses of L-phenylalanine were administered intraperitoneally to rats and motor activity determined by means of photocells in an activity cage. Control rats, and rats whose brain catecholamines were depleted by reserpine, α-methyl-p-tyrosine, or intraventricular 6-hydroxydopamine showed a decrease or no change in motor activity following phenylalanine injections. Injections of the decarboxylase inhibitor, Ro 4–4602, failed to alter the effect of phenylalanine. After injections of [3 H]phenylalanine, [3 H] β-phenethylamine accounted for less than 5 % of brain tritium and radioactivity associated with this amine declined rapidly with time. The proportion of brain radioactivity due to β-phenethylamine was increased by the monoamine oxidase inhibitor, pargyline, and was not affected by the peripheral decarboxylase inhibitor Ro 4–4602. When Ro 4–4602 and pargyline were given together, the increase in radioactive phenethylamine produced by pargyline was prevented, suggesting that a significant proportion of brain phenethylamine may be synthesized in the periphery and can enter brain if monoamine oxidase is inhibited.
Disulphide cross-linking of thiolated α-chymotrypsin to form macromolecules
Authors: Mahbouba M , Pugh W J , Smith H J 
Published: April 2011

Abstract
Thiolation of α-chymotrypsin with N-acetyl homocysteine thiolactone (AHTL) occurs in the presence of Ag+ and imidazole with the introduction of 4–5·5 SH groups per mole. Oxidation of the thiolated enzyme with ferricyanide gave a macromolecule consisting of thiolated enzyme residues cross-linked through intermolecular disulphide bonds. The number of residues linked in this manner varied with each batch of thiolated enzyme but was within the range 16–44 residues. The light scattering data indicated that the macromolecule was rod-shaped.
The uptake of digoxin and digitoxin by some antacids
Authors: Khalil Saleh A H 
Published: April 2011

Abstract
The adsorption of digoxin and digitoxin by some antacids has been investigated. Magnesium trisilicate showed the highest adsorptive effect, the extent of adsorption being up to 99 % for the two glycosides. The calculated values of monolayer adsorption were 0·93 and 1·36 mg g-1 for digoxin and digitoxin respectively. At 37° only partial elution of adsorbed glycosides occurred in 0·2N HCl due to re-adsorption on the hydrated silica gel formed. Antacid preparations containing magnesium trisilicate adsorbed digoxin from a paediatric elixir to the extent of about 95%. Dissolution of digoxin tablets was similarly affected since almost complete suppression of dissolution occurred in the presence of 0·5 g magnesium trisilicate per 0·25 mg digoxin tablet. The effect of antacids, when concurrently administered with oral digoxin, on the bioavailability of the drug, is discussed.
The effect of emetine on myocardial catecholamine metabolism
Authors: Miletich D J , Ivankovic A D , Albrecht R F , Toyooka E T 
Published: April 2011

Abstract
The effects of emetine on the uptake and release of noradrenaline from the isolated, perfused, rat heart and on the in vivo myocardial retention of noradrenaline have been studied. Hearts were removed from animals under light ether anaesthesia, transferred to a modified Langendorff perfusing apparatus and perfused with Krebs-Ringer bicarbonate solution at a rate of 5 ml min−1. The effect of emetine on the uptake of noradrenaline was determined by perfusing hearts for a period of 6 min with perfusate containing various concentrations of emetine and 100 ng ml−1 of [14C]noradrenaline (14C-NA). After 6 min, the emetine-treated hearts contained less (±)−14C-NA than control hearts. The degree of reduction increased with increasing concentrations of emetine. The release of noradrenaline was determined after first perfusing hearts with 14C-NA followed by perfusion with solution containing emetine (0–01 mg ml−1) but free of labelled noradrenaline for periods of 10, 20 and 60 min. It was found that by 60 min emetine significantly decreased myocardial 14C-NA. In the intact animal myocardial concentrations of 14C-NA were reduced 90 min after intravenous 14C-NA, followed immediately by intraperitoneal emetine (1 mg kg−1). These results suggest that the cardiac arrhythmia and irritability seen after emetine treatment in man may be partly due to alterations in catecholamine metabolism.
Effect of chronic intoxication with (+)-amphetamine on its concentration in liver and brain and on [14C] leucine incorporation into microsomal and cytoplasmic proteins of rat liver
Authors: Magour S , Coper H , Fähndrich Ch 
Published: April 2011

Abstract
Rats were treated with increasing concentrations of (+)-amphetamine sulphate in drinking water for 90 days. The ingested dose of amphetamine was found to increase from 16 mg kg−1 on the first day up to 90 mg kg−1 on the 32nd day of treatment. The rats were maintained on the highest dose regime for a further 58 days without any deaths, which showed that tolerance to the overall toxicity of the drug developed. The concentrations of [3H]amphetamine in liver and brain of chronically treated rats were significantly higher than those of controls. Chronic treatment with amphetamine significantly reduced body and liver weight of rats, but did not influence the relative liver to body weight. A marked inhibition of [14C]leucine incorporation into liver microsomal and cytoplasmic proteins was observed after 90 days of treatment with amphetamine. The relation between inhibition of microsomal protein synthesis and the increase of amphetamine concentrations in liver and brain is discussed.
Role of the central autonomic nervous system in the hypotension and bradycardia induced by (-)-Δ9-trans-tetrahydrocannabinol
Authors: Vollmer R R , Cavero I , Ertel R J , Solomon T A , Buckley J P 
Published: April 2011

Abstract
(-)-Δ9-trans-Tetrahydrocannabinol (Δ9-THC), when given intravenously (2 mg kg−1) to cats, produced marked decreases in blood pressure and heart rate which developed gradually and were of prolonged duration. Cervical spinal transection (C1-C2) abolished these effects whereas surgical removal of neurogenic tone to the myocardium selectively eliminated the bradycardia. Bilateral vagotomy alone did not modify the action of Δ9-THC upon heart rate or blood pressure. Recordings of spontaneous sympathetic outflow in the inferior cardiac nerve indicated a rapid reduction in neural discharge rate after Δ9-THC administration. These observations support the hypothesis that Δ9-THC produces a cardiodecellerator and hypotensive effect by acting at some level within the sympathetic nervous system. Experiments conducted to investigate transmission in the superior cervical and stellate ganglia demonstrated that Δ9-THC did not alter ganglionic function. Also, responses to intravenous isoprenaline and noradrenaline were unchanged which suggested that Δ9-THC did not interact with α- or β- adrenoceptors. The possible action of Δ9-THC on central sympathetic structures was investigated by perfusion of Δ9-THC into the lateral cerebral ventricle. Δ9-THC so administered produced a significant reduction in heart rate without a substantial lowering of blood pressure. Tritiated or 14C-Δ9-THC perfused into the lateral ventricle demonstrated that the amount of radioactive compound passing into the peripheral circulation was insignificant and could not account for the decrease in heart rate. The current data are in agreement with the proposal that Δ9-THC produces cardiovascular alterations by an action on the central nervous system which results in a decrease in sympathetic tone.
Infrared spectroscopy using attenuated total reflection
Authors: Kang I P S , Kendall C E , Lee R W 
Published: April 2011

Abstract
An ATR method is given for the examination of pharmaceuticals in the solid state as a layer of crystals on adhesive tape. Representative spectra are chosen to compare with, and to indicate advantages over, disc and mull techniques. Application of the method to pharmaceutical formulations is illustrated by the direct spectral identification of amodiaquine hydrochloride in tablet formulation.
Growth and sporulation characteristics of Bacillus megaterium under different conditions of nutrient limitation
Authors: Brown M R W , Hodges N A 
Published: April 2011

Abstract
The quantitative nutritional requirements to achieve specific cell densities have been studied for B. megaterium. Growth of batch cultures was separately limited by depletion of glucose, ammonium, sulphate, potassium, phosphate, manganese and magnesium. Maximum population density (E420) for graded concentrations of each limiting nutrient was plotted against nutrient concentration and a linear plot was obtained below a critical concentration. Under conditions of magnesium depletion, two phases of growth occurred separated by a plateau. Proposals are made for the use of these cultures in drug resistance studies. Sporulation occurred in all cultures except those limited by potassium, manganese or magnesium. Spores were produced in magnesium-limited cultures provided that glucose was simultaneously depleted. Spores produced under different conditions of nutrient depletion varied in germination characteristics, heat resistance and spore volume.
Competitive interaction of preservative mixtures with cetomacrogol
Authors: Crooks M J , Brown K F 
Published: April 2011

Abstract
The binding of various preservatives, alone and in pairs, to cetomacrogol has been investigated. Data for the compounds alone indicate that all preservatives combined with two distinct classes of sites in the cetomacrogol micelle. The data were expressed in the form of Scatchard plots and the association constant and number of sites in each class were calculated. All combinations of preservatives were shown to exhibit substantial competition resulting in diminished binding, however the nature of the competitive process is not the same in all cases. Chloroxylenol and dichloroxylenol do not compete significantly with methyl paraben in the first class of sites, but substantial competition was observed in the second class. In contrast, methyl paraben and propyl paraben compete strongly for the first class of sites. Competition with these compounds also occurred in the second class of sites but this was coincident with a large increase in the number of secondary binding sites which tended to increase binding.
Adsorption of atropine and hyoscine on magnesium trisilicate
Authors: El-Masry Sawsan , Khalil Saleh A H 
Published: April 2011

Abstract
The adsorption of atropine and hyoscine by magnesium trisilicate has been studied. At relatively low initial concentrations the adsorption data were shown to fit a Langmuir plot and values for monolayer adsorption were 14·9 and 3·8 mg g−1 for atropine and hyoscine respectively. The extent of adsorption was increased at higher initial concentrations due to multilayer formation. The presence of either sodium citrate or sodium phosphate suppressed the adsorption. Elution of the adsorbed alkaloid was dependent on the pH of medium used and followed the order: 0·05n HCl (pH 1·5) &gt;0·01n HCl (pH 2·1) &gt; water (pH 5·5). Due to the dissolution of magnesium trisilicate, at 37° in 0·05n HCl, neither the rate of acid uptake nor the acid absorption test of the adsorbent were significantly reduced by the adsorption of either alkaloid. In the B.P.C. mixture of magnesium trisilicate and belladonna, almost complete adsorption of hyoscyamine occurred and the elution of the adsorbed alkaloid depended on the level of hydrochloric acid in the elution medium used.
Metabolism of isoprenaline in the intestine
Authors: George C F , Blackwell E W , Davies D S 
Published: April 2011

Abstract
A method for the study of drug metabolism in isolated canine gut loops is described. This technique has been used to study the conjugation of isoprenaline with ethereal sulphate. After intraluminal injection of tritiated isoprenaline only 3·6% of the radioactivity in venous effluent appeared as free isoprenaline, and 68·0% as a sulphate conjugate. After pretreatment with salicylamide the proportion of free isoprenaline rose to 73·7% and only 3·3% was accounted for as sulphate conjugate. The significance of these findings is discussed in relation to a possible source of drug interaction.
The depressant action of morphine on transmission at a skeletal neuromuscular junction is non-specific
Authors: Bell Kathryn M , Rees J M H 
Published: April 2011

Abstract
The depressant actions of apomorphine, etorphine, dextromoramide, laevomoramide, naloxone, codeine, morphine and nalorphine have been examined on the rat diaphragm preparation. Their descending order of potency (in the order given above) differed greatly from that published for activity at specific opiate receptors. The depressant action of morphine was not antagonized by naloxone. The stereoisomers dextro- and laevomoramide were equipotent in depressing the preparation. On the transmurally stimulated guinea-pig ileum preparation the depressant action of dextromoramide was antagonized by naloxone. Laevomoramide was 10 000 times less potent than its (+)-isomer, and was not antagonized by naloxone. It is concluded that the effects of narcotic analgesics on transmission at a skeletal neuromuscular junction are not mediated via opiate receptors.
Conditions affecting the interaction of cholinergic agents on the longitudinal muscle of the guinea-pig ileum—unexpected effects with hexamethonium
Authors: Geddes Barbara A , Bogart Laurie F , Hamilton John T 
Published: April 2011

Abstract
Affinity constants were determined for atropine and N-methyl atropine, using both acetylbetamethylcholine and carbaminoylcholine as agonists, on plexus-containing and plexus-free preparations of the guinea-pig ileum. Hexamethonium (1 times 10−4M) decreased the apparent affinity constant of atropine on the plexus-free preparation when carbaminoylcholine but not acetylbetamethylcholine was the agonist. With the latter agonist both antiacetylcholine drugs were equiactive. Hexamethonium’s selective action was associated with a significant shift to the left of the log dose-response curve to carbaminoylcholine on the plexus-free preparation. While others have observed that hexamethonium may be atropine-like, samples of hexamethonium have been reported as being contaminated with a “depolarizing compound”, which may account for the results presented in this study. Nevertheless, the present results are consistent with an allosteric rather than a direct binding mechanism in the blocking action of atropine. The observation that the agonist, acetylbetamethylcholine, was not similarly affected by hexamethonium (or any possible contaminant) suggests that agents with primarily muscarinic activity may not be so affected. This study is another example emphasizing the care needed in interpreting data obtained with the aid of “pharmacological tools”.
Glucose intolerance in thiamine-deficient rats
Authors: Iwata H , Baba A , Baba T , Nishikawa T 
Published: April 2011

Abstract
The mechanism of glucose intolerance in thiamine-deficient rats has been examined. Deficient rats showed marked glucose intolerance. However, the hypoglycaemic effect of insulin (1 i.u. kg−1, i.p.) was similar in the deficient, pair-fed and normal groups, though somewhat weaker in the normal group than in the other two groups. After injection of tolbutamide (40 mg kg−1, i.p.), the hypoglycaemic effects in the three groups were the same. Tyramine (10 mg kg−1, s.c.) restored the impaired glucose tolerance of deficient rats to normal, but not that of alloxan diabetic rats. Furthermore, tyramine did not restore the intolerance of deficient rats pretreated with alloxan. These results suggest that the main factor causing glucose intolerance in the deficient rats may be suppressed insulin secretion.
A pharmacokinetic investigation of the distribution and elimination of diethylpropion and its metabolites in man
Authors: Mihailova D , Rosen A , Testa B , Beckett A H 
Published: April 2011

Abstract
Analogue and digital computing techniques have been used to elucidate the pharmacokinetic parameters involved in the metabolism and excretion of diethylpropion and its metabolites in man. Rate constants for the various processes have been evaluated for the complex reaction scheme. The values of the rate constants are used as a basis for discussion of the relative importance of some of the metabolic routes.
Anthracene derivatives in tissue culture of Cassia senna L.
Authors: Rai P P , Turner T D , Greensmith S L 
Published: April 2011

Abstract
Tissue cultures from Cassia senna L. have been established. Chryso-phanol, physcion, emodin, rhein and aloe emodin have been identified in the oxidative-hydrolysate of the callus. Chrysophanol was the major component. With the exception of physcion all of these compounds were found in the glycosidic as well as the free form. The concentration in the dried callus of the free anthraquinones was 0·8% w/w and of the glycosidic (combined) anthraquinones 0·4% w/w. These results and the absence of sennosides in the cultures emphasize the variation in the anthracene derived constituents of the derived callus and the parent plant.
A kinetic study of human urinary excretion results for butobarbitone and its metabolites
Authors: Gilbert J N T , Natunen T , Powell J W , Saunders L 
Published: April 2011

Abstract
Experimentally determined concentrations of butobarbitone, and three or its metabolites, in the urine of two volunteers, have been studied using a computer technique, which tests the data for limited capacity or first order kinetics. In both volunteers, the 3′-hydroxy and the 3′-oxo metabolites follow limited capacity kinetics for the first few days of excretion, and unchanged butobarbitone follows first order kinetics. Differing results were found for the two persons with the 3′-carboxylic acid metabolite. An additional calculation is proposed when applying the Levy method for interpreting limited capacity kinetics to data where drug recovery is incomplete.
Application of polarography to the development of a stability-indicating assay method for a new indole derivative and its tablet formulations
Authors: Chan H K 
Published: April 2011

Abstract
A polarographic method has been developed for the determination of an antidepressant, 10-(m-chlorophenyl)-2,3,4,10-tetrahydropyrimido [1, 2a] indol-10-ol hydrochloride. The method is not subject to interference from the immediate precursor in the synthetic route of drug preparation or the products of thermal degradation of the active drug substance. The method may be used to monitor storage stability studies.
The mechanical properties of some binders used in tableting
Authors: Healey J N C , Rubinstein M H , Walters V 
Published: April 2011

Abstract
Films of acacia, gelatin, methylhydroxyethyl cellulose, polyvinylpyrrolidone (PVP) and starch have been prepared with moisture levels of 2·0 to 20·0% w/w obtained by equilibration at relative humidities from 0 to 90%. Tensile strengths of 60 mm × 2 mm strips of these films have been determined by stressing to failure at a constant rate of 6·6 times 10−5 ms−1 in a tensile strength apparatus. From the stress-strain curves the modulus of elasticity, yield strength and the work done in breaking unit cross-sectional area of the films have been calculated. This has given an indication of the binders’ mechanical behaviour over the range of moisture contents likely to be encountered in tableting.
The effects of moisture content and gelatin binding agent on the mechanical and failure properties of an Oxytetracycline formulation
Authors: Esezobo S 
Published: April 2011

Abstract
N PILPEL
A study has been made of the effects of gelatin as a binding agent and of moisture content on the mechanical and failure properties of an oxytetracycline tablet formulation, using measurements of the shear strengths and tensile strengths. As the concentration of gelatin at any moisture level between 0 and 25 % w/w is increased, the tensile strength of the formulation increases. Its cohesion and angle of internal friction also increase with gelatin concentration at moisture levels between 2 and 4% w/w. The results are discussed in the light of current theories concerning the bonding of particles by moisture and binding agents.
Improvement of solubility and dissolution rate of poorly water-soluble salicylic acid by a spray-drying technique
Authors: Kawashima Y , Saito M , Takenaka H 
Published: April 2011

Abstract
Spray drying techniques have been applied to improve the solubility and dissolution rate of poorly water-soluble salicylic acid. Spray drying of the acid dispersed in acacia solutions resulted in as much as a 50% improvement in the solubility of the product. Solubility improvement was closely related not only to the concentration of acacia but also the amount of amorphous material in the spray-dried products. The heat of solution was inversely related to these parameters. The dissolution rate of spray-dried product was almost instantaneous being about 60 times faster than that of the original powder. A great improvement in the wettability of the spray-dried material seemed to be mainly responsible for the increase of dissolution rate.
A crystallographic and theoretical study of the conformation of DOET and its significance for the hallucinogenic amphetamines
Authors: Horn Alan S , Post Michael L , Kennard Olga , di Sanseverino L Riva 
Published: April 2011

Abstract
The crystal and molecular structure of 2,5-dimethoxy-4-ethyl-α-methyl-phenylethylamine (DOET) has been determined by X-ray crystallography and the conformation of the side chain has been examined theoretically by the use of a potential energy calculation. There is no indication in the solid state of any intra or inter-molecular hydrogen bonding. The isopropylamine side chain is staggered to the plane of the benzene ring. The α-methyl group is fully extended (antiplanar) whereas the amino group is orientated back towards the ring (synclinal). The potential energy calculations show the existence of 6 minima, one of which corresponds to the crystal position. The calculations also show that the energy differences between the various minima of the side chain are very small. The relationship of these data to the conformations of the hallucinogens, mescaline and 2,4,5,-trimethoxyamphetamine is discussed.