bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of presynaptic dopamine receptors in the antihypertensive response to 2-NN-dimetnylamino-5,6-dihydroxy-1,2,3,4-tetrahydronaphthalene(M-7)
Authors: CLAPHAM J C , HAMILTON T C 
Published: April 2011

Abstract
M-7, 1 and 3 mg kg−1 s.c., elicits an antihypertensive response and bradycardia in conscious spontaneously hypertensive rats (SHR) and causes inhibition of stimulation-evoked pressor responses and tachycardia in pithed SHR. Metoclopramide (30 mg kg−1 i.p.), but not piperoxan (5 mg kg−1 i.p.), abolishes the antihypertensive effect and inhibition of stimulation-evoked pressor responses produced by M-7 (1 mg kg−1 s.c.) in SHR. Conversely, piperoxan, but not metoclopramide, reduces the bradycardia and inhibition of stimulation-evoked tachycardia produced by M-7. Metoclopramide (30 mg kg−1 i.p.) did not affect the cardiovascular responses elicited by intracerebroventricular administration of either clonidine (1 μg) or M-7 (3 μg). These results suggest that the antihypertensive effect of M-7 may be mediated by stimulation of presynaptic dopamine receptors on sympathetic nerves to the vasculature and is independent of the bradycardia, which is probably due to stimulation of presynaptic α2-adrenoceptors on cardiac sympathetic nerve endings.
Renal handling of indomethacin and its relationship with the secretory pathway of prostaglandins
Authors: MELENDEZ ESTELA , REYES JOSE L 
Published: April 2011

Abstract
The uptake of prostaglandin E2, one of the main renal prostaglandins and of p-aminohippurate, an indicator of the anion organic transport, by slices of kidney cortex from adult female rats was studied in the presence and in the absence of indomethacin. The drug's inhibitory effect on the uptake of prostaglandin E2 was observed both after in vivo administration as well as when it was present in the bathing media. The effect was more pronounced when the drug was given in vivo and in addition, was present in the bath. [14C]PAH uptake was inhibited by indomethacin in a dose-related pattern and the kinetic analysis of this effect is indicative of a competitive inhibition. As expected, uptake of PAH by medullary slices was not affected by the presence of either indomethacin of PGE2. Indomethacin was more potent in inhibiting PGE2 uptake than PAH uptake.
The kinetics of solubilization of single component non-polar oils by a non-ionic surfactant
Authors: CARROLL B J , O'ROURKE B G C , WARD A J I 
Published: April 2011

Abstract
The kinetics of solubilization of two non-polar oils (hexadecane and 2,6,10,15,19,23 hexamethyl tetracosane) by a pure non-ionic surfactant (n-dodecyl hexaethylene glycol ether) have been investigated using a recently developed technique. A linear dependence of rate upon surfactant concentration above the cmc and a rapid increase in rate at temperatures close to the cloud point were observed. A previously developed theoretical description of the process has been expanded to account for the observation that the rates for the oils in given systems are not in the exact ratio of the equilibrium capacities of the system for the respective oils. If the effects of changes in aggregation number and shape of the micelle/solubilizate complex are considered, the absolute values of the measured and theoretical rates are in good agreement. Furthermore, the activation energies are nearly equal for the two solubilizates, a result which is in accord with theory. The micelle relaxation time τ2 is practically independent of surfactant concentration.
The relationship between chemical structure and the in vivo metabolism of an homologous series of n-alkyl carbamates
Authors: SARGENT NICHOLAS S E , WOOD STUART G , UPSHALL DAVID G , BRIDGES JAMES W 
Published: April 2011

Abstract
The metabolism and pharmacokinetics of carbonyl [14C] labelled ethyl, n-butyl, n-hexyl and n-octyl carbamates has been examined in rats after oral and intravenous administration. Hydrolysis of the carbamate group was a major metabolic fate, particularly of the more water soluble carbamates. Conversely, with increasing lipophilicity increasing amounts of ω-1 oxidation products were found both in plasma and urine. The plasma pharmacokinetic data could not be explained by a simple bi-exponential model, ethyl carbamate in particular showing unexpectedly persistent blood levels. A model has been proposed to explain the pharmacokinetic data for ethyl, n-butyl, n-hexyl and n-octyl carbamates. The essential features of this model are that carbamate is thought not to be in equilibrium between the peripheral and central compartment and that hydrolytic metabolism takes place in the peripheral compartment while oxidative metabolism to urinary metabolites occurs in the central compartment.
Tensile strength and compression of coated pharmaceutical powders
Authors: Malamataris S , Pilpel N 
Published: April 2011

Abstract
A study has been made of the tensile strength and compression of loosely packed beds of lactose, sodium chloride and calcium phosphate powders after they had been coated with small amounts of stearic acid, polyethylene glycols and polyvinylpyrrolidones. The properties of the systems were measured over a range of temperatures. Only when the coatings were continuous and durable did they produce reductions in both tensile strength and resistance to compression. Marked changes occurred in tensile strength at temperatures 20 ° — 40 °C below the conventional melting points of the coatings. The tensile strength results have been expressed in terms of the range and magnitude of the interparticle forces which depend on the surface free energy of the coated powders and on the Brinell hardness of the coating materials employed.
Presynaptic and postsynaptic sites of action of enhydrotoxin-a (EsNTx-a) isolated from Enhydrina schistosa venom
Authors: Gawade Shivaji P , Gaitonde Bhikaji B 
Published: April 2011

Abstract
Enhydrotoxin-a (EsNTx-a), one of the three toxins isolated from the venom of Enhydrina schistosa produced an irreversible blockade of indirect stimulation of rat phrenic nerve hemidiaphragm preparation in concentration of 0.5 to 1 μg ml−1. The response to direct stimulation was not affected over a 4 h period. The neuromuscular blockade produced by EsNTx-a was antagonized in so far as twitches evoked by indirect stimulation are concerned, when the preparation was treated with approximately double the concentration of purified sea snake antivenin. The tension of tetanic contractions, although depressed in amplitude by the toxin, was sustained. However, it was converted to a twitch-like response in toxin-antivenin treated preparations. In the presence of eserine (1 × 10−6 g ml−1), the twitch-like tetanus was dramatically restored in toxin-antivenin treated rat phrenic nerve hemidiaphragm preparations. Intracellular recordings showed that the frequency of spontaneous miniature end plate potentials (m.e.p.ps) recorded in EsNTx-a poisoned (1.24 × 10−6 g ml) rat phrenic nerve hemidiaphragm preparations decreased to zero, while the m.e.p.p. amplitude was decreased in the later phase of block. The evoked end plate potentials (e.p.p.) in EsNTx-a poisoned (1.24 × 10−1 g ml−1) preparations progressively diminished to zero. The antivenin molecules may have an easy access to bind to the toxin receptor complexes at the postsynaptic site while the presynaptic binding site by the toxin may be relatively inaccessible due to their being intracellular. The presynaptic effect of the toxin was revealed only when the postsynaptic effect was abolished.
Modulating effects of opioids, purine compounds, 5-hydroxytryptamine and prostaglandin E2 on cholinergic neurotransmission in a guinea-pig oesophagus preparation
Authors: Kamikawa Yuichiro , Shimo Yasuo 
Published: April 2011

Abstract
The submucous plexus-longitudinal muscularis mucosae preparation of the guinea-pig oesophagus was used to study the actions of morphine, opioid peptides, purine compounds, 5-hydroxytryptamine (5-HT) and prostaglandin E2 (PGE2) on electrically-induced twitch contractions which are probably mediated by cholinergic nerve stimulation. The twitch contractions were inhibited by morphine (1–100 μM), methionine-enkephalin (1–100 μM) and β-endorphin (0.1–1 μM), but increased by adenosine (1–30 μM), adenosine 5′-triphosphate (1–30 μM), 5-HT (0.01–3 μM) and PGE2 (1–10 nM). The submaximal contraction induced by acetylcholine (12 or 20 nM) which is nearly equivalent to the twitch contractions was unaffected by morphine, methionine-enkephalin, β-endorphin and 5-HT, but augmented by purine compounds and PGE2. It is concluded that cholinergic neurotransmission in the submucous plexus-longitudinal muscularis mucosae of the guinea-pig oesophagus is inhibited by morphine and opioid peptides acting at prejunctional opiate receptors, and facilitated by 5-HT, purine compounds and PGE2 via prejunctional or postjunctional mechanisms.
The vibratory consolidation of particle size fractions of powders
Authors: Woodhead P J , Chapman S R , Newton J M 
Published: April 2011

Abstract
The use of controlled sinusoidal vibration as a means of consolidating packings of lactose within small containers has been examined. Vertical vibration was found significantly more effective and reproducible than horizontal vibration in terms of the degree of consolidation achieved. An optimum frequency range was identified within which the densification was greatest, and this range was largely independent of particle size for particle size fractions of mean volume diameters ranging from 15.6 to 155 μm. The consolidation increased with increasing vibration acceleration up to a level beyond which no further decrease in porosity resulted. Typical effective vibration conditions were characterized by amplitudes of an order of magnitude similar to the particle sizes studied. For particle size fractions of mean diameters 17·8, 37·5 and 80·8 μm, there is evidence that an optimum particle size range exists, within which energy requirements for consolidation are at a minimum.
Gastric blood flow responses to autonomic nerve stimulation and related pharmacological studies in rats
Authors: Yano S , Fujiwara A , Ozaki Y , Harada M 
Published: April 2011

Abstract
The effects of autonomic nerve stimulation on rat gastric blood flow (GBF) were studied using a cross thermocouple method. Stimulation of the periarterial nerve bundles along the left gastric artery produced a decrease in GBF which was antagonized by phenoxybenzamine (0·05 mg kg−1 i.v.), but not by propranolol (1 mg kg−1 i.v.). Stimulation of the vagus nerves elicited an increase in GBF, within a latency of 20 s, which was not apparently affected by atropine (0·15 and 1·5 mg kg−1 i.v.) but was completely blocked by hexamethonium (10 mg kg−1 i.v.). The GBF increase due to acetylcholine (0·25 μg rat−1 i.a.) was markedly blocked by atropine (0·15 mg kg−1 i.v.). Vagal stimulation also produced both the cholinergic excitation and non-cholinergic inhibition of gastric motility. The vagally induced GBF increase was little affected by any pretreatment with phentolamine, propranolol, indomethacin or aprotinin. These results suggest that sympathetic nerve stimulation decreases GBF through α-adrenoceptors and parasympathetic nerve stimulation increases GBF through a non-cholinergic mechanism in rats and that the GBF increase may result from a primary dilator effect of vagal stimulation on the blood vessels because of the immediate initiation of the response.
Pre-junctional α2-adrenoceptor activity of B-HT920
Authors: Mottram D R 
Published: April 2011

Abstract
An in-vitro study has been carried out on the pre-junctional α2-adrenoceptor activity of the thiazoloazepine derivative B-HT 920 (6-allyl-2-amino-5,6,7,8-tetrahydro-4H-thiazolo-[4,5-d]-azepine) using isolated, field-stimulated rat vas deferens and guinea-pig ileum. The α2-selective agonists clonidine (an imidazoline derivative) and α-methyl noradrenaline (a β-phenethylamine derivative) were compared. Results show that B-HT 920 is a potent agonist on pre-junctional α2-adrenoceptors and is competitively antagonized by the selective α2-adrenoceptor antagonist yohimbine. The characteristics of the pharmacological responses obtained with B-HT920 indicate that it interacts with the receptor in an imidazoline-like, rather than a β-phenethylamine-like, manner.
Morphine concentrations in serum, brain and cerebrospinal fluid in the rat after intravenous administration of a single dose
Authors: Bolander Hans , Kourtopoulos Harry , Lundberg Sven , Persson Sven-Åke 
Published: April 2011

Abstract
Morphine has been determined in serum, cerebrospinal fluid (c.s.f.) and in five brain regions in the rat after a single intravenous dose, using high performance liquid chromatography with an electrochemical detector. In pure solution 50 pg morphine and 200 pg naloxone could be detected. Maximal concentrations of morphine were observed in serum and in most brain regions 5 min after administration of morphine. There was a rapid decline in morphine concentrations during the first 30 min, in serum and in all brain regions studied. The morphine concentration in the c.s.f. was constant for the first 30 min, but 30 min later there was a dramatic increase, suggesting that elimination through the c.s.f. could be an important way of eliminating morphine in the central nervous system.
Effect of dithiothreitol on agonist and antagonist actions in frog muscle
Authors: Bleehen Tirza , Clark Amanda L , Hobbiger F 
Published: April 2011

Abstract
The effects of the disulphide bond reducing agent dithiothreitol (DTT) in the frog rectus abdominis preparation have been investigated. DTT, 1 mM, reduced the potency of the monoquaternary agonists acetylcholine, carbachol and tetramethylammonium and the response to electrical field stimulation; the same applied to nicotine, but the action of edrophonium was unaffected and that of the bisquaternary agonist, decamethonium, was increased. The potency of tubocurarine and gallamine as antagonists was unaltered or slightly reduced by DTT when monoquaternary agonists were used and increased when decamethonium was used as agonist. All these effects of DTT were reversed by the oxidizing agent 5-5′dithiobis(2-nitrobenzoic acid) and can be explained by a reduction of a disulphide bond in the vicinity of the anionic site of the nicotinic cholinoceptor. Comparison between these results and published data indicate that there are species differences between nicotinic cholinoceptors at motor endplates. In the guinea-pig ileum preparation DTT reduced the potency of nicotine acting at ganglionic nicotinic cholinoceptors, but had no effect on the agonist response mediated via muscarinic cholinoceptors.
Ascorbic acid and membrane ageing: critical determinants of the in-vitro binding of [3]ADTN to rat striatal tissue
Authors: Bradbury A J , Costall B , Naylor R J 
Published: April 2011

Abstract
Tritiated(±)-2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene ([3H]ADTN), binding (0˙125-4˙0 nM) to rat striatal membranes was investigated using Tris-HCl buffer containing Na2EDTA, nialamide and varying concentrations of ascorbic acid. In the absence of ascorbic acid [3H]ADTN exhibited a high affinity (KD 1˙26 nm) saturable binding (Bmax 138 fmol mg−1 protein) (Scatchard analysis). This was not modified by 10−6 or 10−5 m ascorbic acid used immediately or 60 min after preparation. However, 10−4 m ascorbic acid added (within) 15 min after its preparation reduced the number of bindings sites and added 60 min after it also reduced affinity. Ascorbic acid 5.7 mm reduced affinity whether used within 15 min or 60 min of its preparation. When ascorbic acid 10−4 m was used within 15 min of preparation, and membranes were used immediately, the binding of 2 nm [3H]ADTN was specifically displaceable by nm or sub-nm concentrations of dopamine agonists and antagonists. However, when membranes were used 1–2 h after their preparation there was an increasing loss of the high affinity binding sites displaceable by sub-nm concentrations of (±)-ADTN. Thus, [3H]ADTN can be shown to exhibit high affinity stereoselective binding to rat striatal membranes when these are freshly prepared and the assay is performed using Tris-HCl buffer containing nialamide, Na2EDTA and 10−4 m ascorbic acid prepared within 15 min of use. The characteristics of this binding can be markedly modified if the concentration of ascorbic acid is increased, if its preparation time is extended, or if the membranes are allowed to ‘age’.
Work of friction and net work during compaction
Authors: Ragnarsson Gert , Sjögren John 
Published: April 2011

Abstract
Series of tablets were compressed in a reciprocating tablet machine with a gradually increasing die wall friction. The force needed on the upper punch to maintain the tablet dimensions constant increased with the die wall friction while the lower punch force decreased. The change in punch forces due to differences in die wall friction had no effect on the tablet strength. The net work of compaction should be constant under these circumstances. The net work calculated by subtracting the work of friction and the expansion work from the gross work input was constant when the frictional work was calculated according to one of the two equations proposed in the literature (Järvinen & Juslin 1974) while the other appears to give an overestimation of the work of friction.
Thermal behaviour and dissolution properties of phenylbutazone polymorphs
Authors: Tuladhar M D , Carless J E , Summers M P 
Published: April 2011

Abstract
Five different polymorphic forms of phenylbutazone were prepared and characterized by differential scanning calorimetry (D.S.C.). Rapid heating rates produced single endothermic peaks due to melting but slower heating rates resulted in interconversion of three of the polymorphs to the more stable form. Interconversion on grinding the polymorphs was also observed. From equilibrium solubility and intrinsic dissolution rates it was concluded that the dissolution process could be described by the Berthoud model. The effect of some tablet excipients on the dissolution process is briefly reported.
Effects of ultraviolet light on lecithin monolayers in the presence of fluorescein dyes and tetracycline drugs
Authors: Riaz M , Pilpel N 
Published: April 2011

Abstract
A Langmuir trough was employed to measure the effects of u. v. irradiation on the force area characteristics of monolayer films of lecithin spread on aqueous solutions of some dyes and tetracycline drugs both in the absence and presence of Ca2+ and Ni2+. Irradiation caused photochemical reactions which resulted in the expansion of the films and the extent of reaction was measured by the Photosensitive Indices. The reaction with tetracyclines was inhibited by adding Cu2+ or Ni2+ to the substrate. The kinetic orders of the reactions are given.
Tensile strength and compression of coated pharmaceutical powders: tablets
Authors: Malamataris S , Pilpel N 
Published: April 2011

Abstract
A study has been made of the tensile strength and compression during tableting of lactose, sodium chloride and calcium phosphate powders after they had been coated with small amounts of stearic acid, polyethylene glycols and polyvinylpyrrolidones. The properties of the systems were measured over a range of temperatures. The tensile strength and the compression behaviour depended not only on the amount and type of the coating material but also on the homologous temperature of processing. The changes in tensile strength have been explained in terms of changes in interparticle separation, changes in interparticle forces and the formation of welded bonds by the coatings. The compression results have been analysed in terms of the Heckel and the Cooper & Eaton equations.
Assay of 6-thioguanine nucleotide, a major metabolite of azathioprine, 6-mercaptopurine and 6-thioguanine, in human red blood cells
Authors: Lennard L , Maddocks J L 
Published: April 2011

Abstract
An assay for 6-thioguanine (6-TG) nucleotide, a major metabolite of the cytotoxic drugs azathioprine, 6-mercaptopurine and 6-thioguanine in human red blood cells (RBCs) has been developed. The metabolite was not detected in RBCs when azathioprine or 6-mercaptopurine was incubated with whole blood in-vitro. The assay for intracellular 6-TG nucleotide is specific and requires 8 times 108 RBCs (100 μl packed cells) for which the limit of sensitivity is 30 pmole 6-TG nucleotide. Pre-dose blood samples were obtained, 12 h after the last azathioprine dose, from 10 renal transplant recipients with stable functioning cadaver grafts on a total daily dose of 150 mg azathioprine. The mean 6-TG nucleotide concentration was 171 pmole/8 times 108 RBCs(s.d. = 84). The assay is also suitable for use in measuring 6-TG nucleotide in the RBCs of leukaemic children undergoing 6-mercaptopurine treatment.
Moment analysis for disposition kinetics of several cephalosporin antibiotics in rats
Authors: Yamaoka Kiyoshi , Nakagawa Terumichi , Uno Toyozo 
Published: April 2011

Abstract
Disposition kinetics of cefamandole, cefoperazone, cefotiam, cefmenoxime and cefmetazole following rapid intravenous injection into rats is investigated. The plasma concentrations of the antibiotics are determined by the high performance liquid chromatographic method, and the pharmacokinetic behaviours of the cephalosporins are evaluated by moment analysis which is a model-independent method. Analysis of variance (ANOVA) followed by the paired t-test reveals that cefmetazole and cefmenoxime have greater mean residence time (MRT) than cefotiam, cefamandole and cefoperazone, and that cefamandole and cefmetazole show larger steady-state volume of distribution (Vss) than the other cephalosporins. Cefamandole has the greatest total body clearance (40.2 ml kg−1 min−1) and cefmenoxime the smallest (7.72 ml kg−1 min−1).
Physicochemical characterization of the human nail: permeation pattern for water and the homologous alcohols and differences with respect to the stratum corneum
Authors: Walters Kenneth A , Flynn Gordon L , Marvel John R 
Published: April 2011

Abstract
In order to develop a basic concept of the permeability of the human nail plate and thus create a better understanding of the toxic potentials and therapeutic possibilities of substances applied to the nail, avulsed cadaver nails have been placed in specially constructed diffusion chambers and their permeation by water and the n-alkanols through dodecanol, all in high aqueous dilution, has been investigated. The permeability coefficient of water is 16.5 times 10−3 cm h−1 and that for methanol is 5.6 times 10−3 cm h−1. Ethanol’s permeability coefficient measured 5.8 times 10−3 cm h−1. Permeability coefficients decreased systematically thereafter to a low value of 0.27 times 10−3 cm h−1 at n-octanol. The middle chain length alkanols, n-pentanol through n-octanol, have similar permeability coefficients but n-decanol and n-dodecanol show higher rates of permeation. The data suggest that, as a membrane, the hydrated human nail plate behaves like a hydrogel of high ionic strength to the polar and semipolar alcohols. Declining permeability rates appear linked to decreased partitioning into the complex matrix of the plate as the compounds become hydrophobic. The results for n-decanol and n-dodecanol introduce the possibility that a parallel lipid pathway exists which favours the permeation of these exceedingly hydrophobic species.