bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of dopaminergic systems in γ-hydroxybutyrate-induced electrocorticogram hypersynchronization in the rat
Authors: Godschalk M , Dzoljic M R , Bonta I L 
Published: April 2011

Abstract
The effects of dopaminergic agonists and antagonists on the duration of hypersynchronization induced in the electrocorticogram (ecog) by γ-hydroxybutyrate (γ-HB) were tested in rats. Apomorphine (0·2–8 mg kg−1), piribedil (2·5–10 mg kg−1) and haloperidol (0·5–1 mg kg−1) had no influence on the duration of the hypersynchrony. Amphetamine (1·5–6 mg kg−1) inhibited the hypersynchrony, while (3,4-dihydroxyphenylamino)-2-imidazoline (DPI; 5, but not 1, mg kg−1) prolonged its duration. The lack of effect of the dopamine receptor agonists apomorphine and piribedil, and the dopamine receptor blocker haloperidol, on the γ-HB-induced hypersynchrony might indicate that the inhibition of the impulse flow in the nigrostriatal dopamine system by γ-HB is not involved in the generation of the hypersynchrony. DPI is thought to be an agonist at a dopamine receptor not sensitive to apomorphine, and its facilitatory effect on γ-HB-hypersynchrony can be interpreted in terms of a possible involvement of another dopamine system in the ecog hypersynchrony induced by γ-HB. The antagonism of γ-HB by amphetamine is possibly due to an indirect stimulatory effect on noradrenergic receptors.
Some antagonists of dantrolene sodium on the isolated diaphragm muscle of the rat
Authors: Bowman W C , Khan H H , Savage A O 
Published: April 2011

Abstract
The effects of a number of potential antagonists of dantrolene sodium have been studied on twitches of the isolated hemidiaphragm preparation of the rat stimulated directly at a frequency of 0·1 Hz, after complete neuromuscular block produced by tubocurarine or erabutoxin a. The substances selected as possible dantrolene antagonists were uranyl ions, thiocyanate ions, adrenaline, caffeine, quazodine, quinine, 4-aminopyridine and the calcium ionophore A23187, all of which facilitate excitation-contraction coupling in one way or another. Contracture was the main feature of the response to A23187, the increase in the tension of the dantrolene-depressed twitches being very slight. All the remaining compounds increased the amplitude of the twitches, but only 4-aminopyridine, quinine, quazodine and caffeine were capable of restoring to the control amplitude twitches that had been maximally depressed by dantrolene. Of these, 4-aminopyridine and quinine were the most potent on a molar basis.
Loss of antibacterial preservatives from contact lens solutions during storage
Authors: Richardson N E , Davies D J G , Meakin B J , Norton D A 
Published: April 2011

Abstract
The preservative content of 34 commercially available contact lens solutions has been determined. Over half of the solutions contained less than 90% of the stated preservative content. Storage tests conducted at 40°, using both simulated and commercially available contact lens solutions in plastics containers of the type used to present these products showed that thiomersal and chlorbutol appeared to be sorbed by these containers in contrast to benzalkonium chloride and chlorhexidine gluconate which interacted mainly by a surface adsorption process. The extent of any interactions was dependent upon the type of plastics material used to fabricate the container.
The adhesion of film coatings to tablet surfaces - the effect of some direct compression excipients and lubricants
Authors: Rowe R C 
Published: April 2011

Abstract
The effect of some direct compression excipients and lubricants on the adhesion of hydroxypropyl methyl cellulose films has been examined using a specially designed tensile testing apparatus (Fisher & Rowe, 1976). The adhesion was found to be influenced by both the roughness, including microporosity, of the tablet surface and its polarity. Tablets prepared from microcrystalline cellulose showed very high adhesions despite having relatively smooth surfaces, owing to the surface being saturated with hydroxyl groups able to form hydrogen bonds with the corresponding groups on the polymer. The addition of magnesium or calcium stearate to the tablet was found to decrease the adhesion, but the addition of stearic acid caused a significant increase. The effect of lubricant concentration on the adhesion could be expressed by an equation similar to that proposed by Hofrichter & McLaren (1948) for the adhesion of vinyl chloride/vinyl acetate copolymers to regenerated cellulose.
The effects of p-chlorophenylalanine and ethanolamine-O-sulphate in an animal test of anxiety
Authors: File Sandra E , Hyde J R G 
Published: April 2011

Abstract
p-Chlorophenylalanine, which produces a depletion of brain 5-HT concentration, had effects qualitatively similar to those previously found with chronic chlordiazepoxide and with acute ethanol in the social interaction test of anxiety. This result is compatible with the idea that a reduced turnover of 5-HT is important in anxiety reduction. On the same test, ethanol-amine-O-sulphate, which raises brain γ-aminobutyric acid, was without effect, suggesting raised concentrations of this acid are not essential for anxiety reduction.
Renal clearance procedure for the rat: effect of dopamine and standard saluretics
Authors: Brennan Francis T , Sosnowski Genevieve F , Mann William A , Sulat Lynn , Wiebelhaus Virgil D 
Published: April 2011

Abstract
Four standard diuretic compounds were evaluated for electrolyte output, effects on glomerular filtration rate (GFR), and effective renal plasma flow (RPF) in an anaesthetized rat preparation. Triamterene, hydrochlorothiazide, acetazoleamide and furosemide exerted their characteristic diuretic effects at doses which did not significantly change GFR or RPF. Regulation of the rate of a 3% mannitol-0·9% NaCl infusion to rats permitted the establishment of GFR and RPF values which were approximately in the middle of the reported range for this species. A significant increase in RPF without a concurrent rise in GFR was produced with dopamine. This was effectively blocked by the peripheral dopamine inhibitor, bulbocapnine.
Effect of drugs on rats exposed to cold—restraint stress
Authors: Beattie Doreen 
Published: April 2011

Abstract
The extent of protection afforded by over 40 drugs of various pharmacological groups against the development of gastric erosions induced in rats by a combination of cold and restraint has been investigated. Some drugs offered good protection, others had no effect on, or exacerbated, the lesions. Attempts are made to explain the mode of action of the protective drugs.
Identification of the in vitro N-oxidized metabolites of (+)- and (−)-N-benzylamphetamine
Authors: Beckett A H , Gibson G G 
Published: April 2011

Abstract
This study has identified (+)- and (-)-N-benzyl-N-hydroxyamphetamine as metabolites after incubation of both (+)- and (-)-N-benzylamphetamine with fortified rabbit liver homogenates. The isomeric hydroxylamine metabolites were identified using the techniques of g.l.c., t.l.c. and combined g.l.c.-mass spectrometry (ms) and by comparison with results from reference samples. An additional novel metabolic product was identified after incubation of N-benzylamphetamine which had properties consistent with that of N-benzyl-amphetamine nitrone.
Temperature dependence of the disintegration times of compressed tablets containing hydroxypropyl-cellulose as binder
Authors: Stafford J W , Pickard J F , Zink R 
Published: April 2011

Abstract
The dependence of the disintegration times of placebo and active tablets containing hydroxy-propylcellulose (HPC), as binder on the temperature of the test medium in the region of 37° is reported. The degree of temperature dependence varied with the HPC lot and concentration in the formulations. These dependences could be accentuated by the presence in the formulation of certain drugs, such as caffeine. The extent of the temperature dependence could be diminished by reducing the HPC concentration in the formulations. Corresponding trends were observed in drug release behaviour from some of these formulations. The effects observed were interpreted in terms of the thermodynamic behaviour of HPC systems and a specific drug-HPC interaction.
The effect of drug concentration on the thermal (dark) degradation of promethazine hydrochloride in aqueous solution
Authors: Meakin B J , Stevens John , Davies D J G 
Published: April 2011

Abstract
The thermal (dark) degradation of promethazine hydrochloride in aqueous solution presents a complex kinetic picture. The process is oxygen dependent and is modified by EDTA. In citrate buffer, pH 4·0, ionic strength 0·5m, containing 0·1 % EDTA, the thermal degradation at 90° can be fitted to first order rate plots at drug concentrations up to 1·56 × 10−2m (0·5%) and to zero order rate plots at drug concentrations greater than 9·35 × 10−2m (3·0%). At intermediate concentrations no simple equation can describe the data. These effects have been correlated with the formation of drug micelles and the rate data have been interpreted on the basis of a first order monomer process and a half order micellar process occurring simultaneously.
The determination of salicylic acid and benzoic acid in pharmaceutical formulations by spectrofluorimetry
Authors: Adams S , Miller J H Mc B 
Published: April 2011

Abstract
Methods of extraction from pharmaceutical formulations and subsequent determination of benzoic acid and salicylic acid by spectrofluorimetry are described. The recovery of benzoic acid, in the presence of salicylic acid, was 99·3%, with a coefficient of variation of 1·04%, while the recovery of salicylic acid, in the presence of benzoic acid, was 97·7%, with a coefficient of variation of 0·68%.
Gastric erosions induced by analgesic drug mixtures in the rat
Authors: Seegers A J M , Jager L P , van Noordwijk J 
Published: April 2011

Abstract
Gastric erosions after oral administration of analgesics separately and in admixture have been examined in adult rats. After administration of acetylsalicylic acid (aspirin), phenacetin, paracetamol and caffeine as single drugs, gastric erosions were only observed with aspirin. The combination of aspirin with phenacetin did not change, that of aspirin with caffeine significantly increased, and aspirin with paracetamol significantly decreased the incidence of gastric lesions compared with aspirin alone. The results for aspirin with paracetamol did not differ from those for the vehicle. Addition of caffeine to the combination of aspirin and phenacetin caused a significant increase in erosions, but when given with aspirin and paracetamol no erosions occurred. The mechanisms underlying the effects of these drugs on aspirin-induced erosions are discussed.
Effect of tolerance to morphine, ethanol and barbiturate on amphetamine circling in rats with a striatal dopamine lesion
Authors: Slater P 
Published: April 2011

Abstract
The (+)-amphetamine circling rate of rats with unilateral 6-OHDA lesions in the striatum was recorded. Morphine tablets were implanted subcutaneously for chronic treatment. In the morphine-dependent animal the circling rate to amphetamine given 4 days after morphine was first implanted was depressed but after withdrawal with naloxone a day later the rate increased, returning to normal after 21 days. Barbiturate physical dependence was induced by adding increasing amounts of barbitone to the drinking water of lesioned rats over four weeks after which the amphetamine circling response was depressed and remained so after the barbiturate was withdrawn. Ethanol tolerance was induced by adding ethanol to the drinking water of lesioned rats for four weeks. Neither the induction of tolerance over this period nor ethanol withdrawal had any effect on the circling response to amphetamine. The change in the response of striatal dopamine neurons to amphetamine that occurs after chronic morphine treatment, cannot be produced by chronic treatment with either barbitone or ethanol. The neurochemical bases of barbiturate and ethanol tolerance are different from morphine tolerance.
A membrane model of the human oral mucosa as derived from buccal absorption performance and physicochemical properties of the β-blocking drugs atenolol and propranolol
Authors: Schürmann W , Turner P 
Published: April 2011

Abstract
The buccal absorption characteristics and physicochemical properties of the β-adrenoceptor blocking agents propranolol and atenolol have been investigated to evaluate their permeation properties across biological lipid membranes. The dissociation constants, solubilities of free base, and n-heptane partition coefficients show that propranolol in its unionized form is much more lipophilic than atenolol, both drugs being bases with a similar pKa. Buccal absorption was studied under conditions of varying drug concentration, contact time, and pH, and controlled through the use of a non-absorbable marker. The absorption findings are in general agreement with the pH-partition theory. A new compartmental diffusional model that includes membrane storage and a hypothetical ‘aqueous pH-buffering surface system’ allowed a more exhaustive interpretation to be made. A method for the estimation of the intrinsic pH and buffer capacity of the postulated surface system from drug pH-absorption data and partition coefficients alone is described. With human oral mucosa the intrinsic pH was near 6·7, and the buffering capacity of the system (expressed as the ratio ΔpH/ΔpH eff) about 2·86. The method was validated using published absorption data from the rat small intestine. Absorption of unionized drug through pores is shown to be negligible in the buccal absorption situation. The time course of absorption suggests membrane storage of lipophilic compounds; the in vivo partition coefficient of unionized propranolol relative to the mucous membrane could be calculated for the peusdo-steady state of absorption, i.e. the partition equilibrium between mouth content and membrane, to be approximately 776; this value is of the same order as the in vitro partition coefficient for the erythrocyte/plasma system. The lipid biophase of the buccal membrane is estimated semiquantitatively to be of intermediate polarity (ɛ = 3–4).
Possible differences in α-adrenoceptors in rabbit ileum and spleen
Authors: Harper Barbara , Hughes I E , Noormohamed F H 
Published: April 2011

Abstract
In isolated tissues from reserpinized rabbits (5 mg kg−1, i.m. 20 h before experiment) and in the presence of cocaine (3 × 10−5 m), corticosterone (2·8 × 10−5 m), tropolone (3 × 10−5m), propranolol (4 × 10−6m) and disodium EDTA (3 × 10−5m), the potency ratios (relative to (—)-noradrenaline) of (—)adrenaline, (—)-phenylephrine and (±)-methoxamine were (m ± s.e.) 203 ±0·13, 0·045 ± 0·003 and 0·0062 ± 0·0018 respectively in splenic strips and 1·77 ± 0·41, 0·093 ± 0·018 and 0·029 ± 0·004 respectively in isolated ileum. Although the pA2 values for phentolamine and thymoxamine against (—)-noradrenaline in the two tissues were very similar there was a statistically significant difference when using yohimbine as the α-adrenoceptor blocking agent (pA2 = 6·80 ± 0·30 in spleen; 5·60 ± 0·12 in ileum). These differences suggest that the α-adrenoceptor in the two tissues is not identical. The pA2 value of phentolamine in rabbit ileum was not significantly different whether (—)-noradrenaline or (±)-methoxamine was used as agonist (7·91 ± 0·07 and 7·97 ± 0·06 respectively) while that of yohimbine was 5·56 ± 0·10 using (—)-noradrenaline and 6·19 ± 0·12 using (±)-methoxamine. In the light of this latter result and, considering the scatter of the experimentally determined values, there may be two α-adrenoceptors in rabbit ileum and either or both may not be identical in all respects to the α-adrenoceptor found in rabbit spleen.
Aggregation of antidepressant drugs in aqueous solution
Authors: Attwood D , Gibson J 
Published: April 2011

Abstract
Light scattering, conductivity and pH methods have been used to examine the aggregation in aqueous solution of a series of antidepressant drugs. The drugs investigated included the hydrochlorides of amitriptyline, butriptyline, protriptyline, nortriptyline, imipramine, desipramine, clomipramine, dothiepin, dibenzepin, opipramol, iprindole, doxepin, mianserin and maprotiline. No significant association of dibenzepin, mianserin or maprotiline hydrochlorides could be detected up to their respective solubility limits. A micellar pattern of association was established for all other compounds. Critical micelle concentrations and micellar properties are reported.
Formation of liquid crystal and other non-fluid phases in emulsions containing non-ionic surfactants
Authors: Ali A A , Mulley B A 
Published: April 2011

Abstract
The relation between the phase distribution of components and the nature and properties of dispersions formed in a four-component system containing dodecane, water and two homogeneous non-ionic surfactants has been investigated by phase-rule techniques. Phase equilibrium diagrams for the four ternary systems were investigated and the phase boundaries for the various regions formed in these systems were defined by synthetic and analytical methods. In some of the ternary diagrams a narrow three-phase region occurs where ‘gel’ or liquid crystal as well as two isotropic liquid phases are present. Dispersions containing the gel phase were very stable. The four-component system has not been fully investigated due to the presence of extensive liquid crystal phases and three-phase regions. However, some distribution data for the quaternary system was obtained. In the presence of sufficient amounts of the short chain non-ionic surfactant C10H21(O.CH2.CH2)3OH, a three-liquid phase region occurs where multiple drops readily form.
Factors affecting the disintegration and dissolution of chloroquine phosphate/starch tablets
Authors: Pilpel N , Otuyemi S O , Kurup T R R 
Published: April 2011

Abstract
A study has been made of the effects produced on the disintegration and dissolution times of chloroquine phosphate tablets by varying their moisture and starch contents and the distribution of the starch in the formulation. 3 to 5% w/w of moisture produces a maximum in the disintegration and dissolution times. Starch added externally as a powder acts only as a disintegrating agent for the tablets, but starch added internally as a paste during granulation acts both as a binding agent and as a disintegrant.
Control of the composition of gentamicin sulphate by proton magnetic resonance spectrometry
Authors: Calam D H , Gilbert J N T , Lightbown J W , Powell J W , Thomas A H 
Published: April 2011

Abstract
The proportions of the main components present in gentamicin sulphate complex, gentamicins C1, C1a and C2, can be monitored by 1H nuclear magnetic resonance (nmr) spectrometry. The method depends on measurement of the peak heights of signals for N-methyl and C-methyl groups present in all three components and of those present in C1 and C2 only, followed by calculation of peak height ratios to control composition within acceptable limits. The precision and reproducibility of the method have been established through two collaborative studies each involving seven laboratories. In the second study, with an improved procedure, the mean variance between laboratories with 10 samples was 3·4 × 10−4 for the N-methyl ratio of the peak at δ 2·75 to that at δ 2·95, and 1·25 × 10−3 for the C-methyl ratio of the peak at δ 1·25 to that at δ 1·35. Within laboratories the mean variance for triplicate determinations was 7·4 × 10−5 and 8·9 × 10−5 respectively. The data presented here form the experimental basis for the test controlling the composition of gentamicin sulphate in the British Pharmacopoeia 1973: Addendum 1975, and for the introduction into the British Pharmacopoeia of nmr spectrometry as an analytical technique. The reference standards and all batches of gentamicin sulphate intended for therapeutic use in the United Kingdom examined by this procedure comply with the limits laid down.
The mechanism of the hypothermic effect of amantadine in rats and mice
Authors: Brown F , Davies J A , Redfern P H 
Published: April 2011

Abstract
Amantadine (25–100 mg kg−1, i.p.) given to rats at an ambient temperature of 4°, or mice at 21°, caused a marked fall in rectal temperature. Prior administration of pimozide (1–2 mg kg−1, s.c.) did not block hypothermia due to amantadine in rats or mice; in contrast, hypothermia due to apomorphine (2 mg kg−1, i.p.) and piribedil (10–40 mg kg−1, i.p.) in rats was blocked by pimozide pretreatment. Amphetamine (5 mg kg−1, i.p.) given 2 h after reserpine (2 mg kg−1, i.p.) caused a reversal of the hypothermic effect of reserpine in mice, but a reversal was not obtained with amantadine (50 mg kg−1, i.p.). Direct injection of amantadine (4–8 mg kg−1) into the cerebral ventricles (i.c.v.) of mice caused marked hypothermia which was not blocked by pimozide, but intravenous injection of the same dose of amantadine did not cause hypothermia. Rimantadine, a congener of amantadine but without anti-parkinsonian activity, also caused pimozide insensitive hypothermia in mice at doses of 50 mg kg−1, intraperitoneally or 2–4 mg kg−1, intracerebroventricularly. The main conclusion drawn from these results is that in causing hypothermia amantadine acts in the cns but not on dopamine receptors.
A mammalian muscle with the pharmacological characteristics of slow tonic muscle
Authors: Dale M Maureen , Muid R 
Published: April 2011

Abstract
The guinea-pig isolated cremaster muscle gave tetrodotoxin-resistant dose-related contractures with acetylcholine, carbachol and the depolarizing neuromuscular blocking agents. The dose-response curve to suxamethonium in tetrodotoxin 2 × 10−7m could be shifted to the right with tubocurarine 10−6m. KCl, 0·1 m, produced slow sustained contractures of the muscle. With the cremaster nerve-muscle preparation tetanic contractions at 20 Hz were maintained over several minutes. Tetrodotoxin eliminated the twitch response to single shock nerve stimulation but not the sustained increase in tension produced by suxamethonium. The results suggest either that there is a component of slow tonic muscle in the guinea-pig cremaster or that the cremaster consists of a type of focally innervated muscle which has pharmacological responses qualitatively different from those of most focally innervated muscles so far described.
Effect of carbenoxolone on lipolysis in rat adipose tissue
Authors: Lambert B , Godard C , Jacquemin C 
Published: April 2011

Abstract
Carbenoxolone slightly but significantly decreased the release of FFA from rat epididymal fat pads. The antilipolytic action of carbenoxolone was not blocked by 10−3m 3-isobutyl-1-methylxanthine, a potent inhibitor of phosphodiesterase. The findings suggest that carbenoxolone exerts its antilipolytic activity by acting on adenylate cyclase, thereby decreasing cyclic AMP concentrations and the activity of the hormone-sensitive lipase in adipose tissue.
The inhibition by clorgyline of 5-hydroxytryptamine deamination by the rat liver
Authors: Fowler C J , Callingham B A 
Published: April 2011

Abstract
The inhibition of the monoamine oxidase activity in the rat liver by the substrate selective inhibitor clorgyline has been investigated with 5-hydroxytryptamine as substrate. The results obtained are consistent with a theoretical model whereby the inhibition of enzyme activity by clorgyline follows a reversible association phase leading to an irreversible ‘suicide’ reaction. The relative concentrations of enzyme and inhibitor are of the same order, and can account both for the failure of the reaction to go to completion, and for the differences in the apparent sensitivity of enzyme preparations to inhibition by clorgyline. The possible value of this type of inhibition as a means of assay for monoamine oxidase active centres is discussed.