bluuebunny/crossref_metadata_2025_split huggingface dataset:
A fluorescence method for the determination of the molecular weight cut-off of alginate-polylysine microcapsules
Authors: Vandenbossche Geert M R , Van Oostveldt Patric , Remon Jean Paul 
Published: April 2011

Abstract
Several applications of microcapsules for the encapsulation of living cells or macromolecules require well defined pore sizes. The molecular weight cut-off of alginate-polylysine microcapsules has been determined using a range of fluorescent labelled dextran molecules. The diffusion of the fluorescein isothiocyanate labelled (FITC)-dextrans into the microcapsules was followed by fluorescence and confocal laser scanning microscopy. The permeability of microcapsules for FITC-dextrans with a molecular weight of 4 700 daltons and the impermeability for FITC-dextrans with a molecular weight of 40 500 daltons was confirmed with both techniques. Determination of the molecular weight cut-off, using confocal laser scanning microscopy was more reliable and required a smaller sample than fluorescence measurements.
Unusual solubility behaviour of cyclosporin A in aqueous media
Authors: Ismailos George , Reppas Christos , Dressman Jennifer B , Macheras Panayotis 
Published: April 2011

Abstract
The solubility of cyclosporin A was determined in water and in Sorensen buffers at pH 1.2 and 6.6 at temperatures ranging from 5 to 37°C. No differences in solubility behaviour were observed among the three aqueous media. Solubility was found to be inversely proportional to the temperature in each medium, indicating that the heat of solution was exothermic in each case.
The inhibitory action of zinc sulphate on the contractile activity of guinea-pig ileum
Authors: Cho C H , Teh G W 
Published: April 2011

Abstract
The present study examines the inhibitory action of zinc sulphate (ZnSO4) on the contractile response of various agonists on guinea-pig isolated ileum. Different doses of agonists were selected to produce similar contractile activity, in order to compare the degree of inhibition produced by ZnSO4 Preincubation of ileum with ZnSO4 1 × 10−3 or 3 × 10−3 M for 10 min dose-dependently and significantly prevented the contraction induced by acetylcholine (1.7 × 10−8 M), 5-HT (2.4 × 10−6 M), histamine (5.4 × 10−7 M) and nicotine (1.7 × 10−6 M) but not by prostaglandin E2 (PGE2, 8.5 × 10−9 M). The same doses of ZnSO4 reduced the twitch contraction produced by electrical field stimulation. These findings indicate that the contractile activity of PGE2 is mediated by a mechanism different from that of other agonists and of electrical field stimulation. It is likely that the contractile activity of PGE2 is acting through the receptors on the ileal muscle which are not blocked by ZnSO4 pretreatment.
A comparison of aminopeptidases from excised human buccal epithelium and primary cultures of hamster pouch buccal epithelium
Authors: Audus Kenneth L , Williams Amos , Tavakoli-Saberi M Reza 
Published: April 2011

Abstract
Aminopeptidase activity associated with human buccal tissue and primary cultures of hamster buccal epithelium homogenates was assayed fluorometrically using 4-methoxy-2-naphthyl-amides of leucine, alanine, and arginine. Kinetic parameters, Km and Vmax. for all substrates were estimated. Aminopeptidase parameters for human tissue were similar to those for the in-vitro system and reported literature values for rodent buccal tissue aminopeptidases. Aminopeptidases of both tissues were also found to be similarly sensitive to typical inhibitors, bestatin and puromycin. Overall results suggest that appropriate in-vitro systems derived from animal tissues may be useful in assessing the role and localization of peptidases associated with buccal tissue.
The effect of nitrous oxide on S-adenosylmethionine levels in mouse brain
Authors: Dorris Roy L 
Published: April 2011

Abstract
Mice were exposed to nitrous oxide (50%) for up to 24 h and S-adenosylmethionine (SAMe) levels measured in corpus striatum and cerebellum, areas with high and low catecholamine turnover rates, respectively. After 4 h, levels were 21 and 8% and after 6 h, 33 and 14% lower than controls in striatum and cerebellum, respectively. Thus, the effect was more pronounced in corpus striatum, the area with the presumed higher rate of catecholamine O-methylation. With continued exposure to nitrous oxide SAMe concentrations in the two areas returned to nearly normal at 24 h. The observation that levels did not continue to decline, and even returned towards control levels, while animals were still in the presence of the gas suggests that a mechanism other than that of methionine synthase inhibition may have been responsible for the initial effect. Alternatively, some other source of SAMe may have become available to compensate for the inhibition of the enzyme.
α1-Adrenoceptor Subtypes in the Rat Ventricular Muscle
Authors: Kinami Junji , Tsuchihashi Hiroshi , Baba Shoko , Mano Fumie , Maruyama Keiko , Nagatomo Takafumi 
Published: April 2011

Abstract
Scatchard analyses of [3H]prazosin binding in rat ventricular muscle membranes showed biphasic curves, which identified α1High- and α1Low-affinity sites. The α1High-affinity site was completely inhibited by 1 μm phenoxybenzamine. The displacement potencies of α1-adrenergic antagonists were characterized by [3H]prazosin binding to α1High. and α1Low-affinity sites in the absence and presence of 1 μm phenoxybenzamine. The affinities of most chemicals for α1Low-affinity sites were significantly lower than those for α1High-affinity sites, but WB-4101 (2-(2,6-dimethoxy-phenoxyethyl)aminomethyl-1,4-benzodioxane), arotinolol, cinanserin, nifedipine, and p-aminoclonidine had the same affinities for both α1Low- and α1High-affinity sites. These results show that two α1-adrenoceptor subtypes, α1High- and α1Low-affinity, are present in the rat heart, and that there are physical variations in α1-adrenoceptor binding sites, based on their selectivity to antagonists.
Absorption kinetics of cyclosporin in the rat
Authors: Hedayati Shahram , Bernareggi Alberto , Rowland Malcolm 
Published: April 2011

Abstract
Cyclosporin was administered (6 mg kg−1, i.v.) over 15 min, or (10 mg kg−1) by gavage, to two groups of 5 rats. Following i.v. infusion, cyclosporin exhibited triphasic behaviour with mean ± s.e.m. disposition half-lives of 9·0 ± 1·3 min, 4·0 ± 0·5 h and 16·0 ± 1·7 h. Following oral administration, peak blood concentration (Cmax) of 1290 ± 93 ng mL−1 was reached after 5 h, when cyclosporin absorption essentially ceased. The absolute bioavailability (F) of cyclosporin was 24·0%. Standard laboratory rat chow consisting of 2% corn oil did not appear to alter cyclosporin absorption kinetics.
Supersensitivity of isolated atria from diabetic rats to adenosine and methacholine: modulation by pertussis toxin
Authors: Li Xiao-Jiang 
Published: April 2011

Abstract
The chronotropic response of isolated right atria obtained from rats made diabetic 14–15 weeks previously by streptozotocin, was compared with age-matched controls. Diabetic rat atria are significantly more sensitive to the negative chronotropic actions of adenosine and of methacholine. Pretreating both control and diabetic rats with 2·5 mg kg−1 pertussis toxin attenuated the negative chronotropic effects of methacholine and adenosine on isolated atria, although diabetic atria still displayed a significantly greater sensitivity to these agonists (P &lt; 0·05–0·001). The negative chronotropic effects of methacholine and adenosine on both control and diabetic atria were abolished following pretreatment with higher doses of pertussis toxin (10 mg kg−1). These results suggest that pertussis toxin-sensitive G proteins may be involved in the supersensitivity of diabetic hearts to methacholine and adenosine.
A Possible Mechanism of Endothelium-dependent Relaxation Induced by Pirarubicin and Carbachol in Rat Isolated Aorta
Authors: Hirano Shin-Ichi , Agata Naoki , Hara Yutaka , Iguchi Hiroshi , Shirai Masataka , Tone Hiroshi , Urakawa Norimoto 
Published: April 2011

Abstract
The mechanism of endothelium-dependent relaxation induced by pirarubicin, (2″R)-4′-O-tetrahydropyranyladriamycin, THP, or carbachol was investigated in the rat isolated aorta. The relaxant effect of THP (1·5 × 10−6-4·5 × 10−5 m) or carbachol (10−8-10−4 m) on the aorta with endothelium was decreased by lowering Ca2+ in the medium. The relaxation induced by THP was not inhibited by pretreatment with verapamil (10−6–10−5 m), and that induced by carbachol was only partially inhibited. However, on replacement of all but 20 Mm Na+ with either Li+ or choline, the THP- or carbachol-induced relaxation was inhibited. Furthermore, the relaxing effect of THP or carbachol was inhibited by pretreatment with amiloride (10−4-3 × 10−4 m), with ouabain (10−4-10−3 m), or with K+-depletion. These results suggest that the THP- or carbachol-induced relaxation depending on endothelium was affected by modifying the calcium ion concentration, and that a Na+–Ca2+ exchange process is involved.
Increase in susceptibility to EcoRII restriction of bacteriophage λ produced by propagation on host cells growing in 5-azacytidine: a new in-vivo method for demonstration of DNA-methylation inhibition
Authors: Radnedge L , Pinney R J 
Published: April 2011

Abstract
The efficiency of plating on EcoRII-restricting cells of bacteriophage λvir propagated on an Escherichia coli K-12 dcm+ host decreased with increase in concentration of 5-azacytidine (5-azaC) in the propagating medium. This illustrates, in-vivo, the inhibition of DNA-cytosine methylation induced by 5-azaC and provides a simple system for the detection of DNA-methylation inhibitors.
Prediction of Skin Permeability of Drugs: Comparison of Human and Hairless Rat Skin
Authors: Morimoto Yasunori , Hatanaka Tomomi , Sugibayashi Kenji , Omiya Harumi 
Published: April 2011

Abstract
Relationships between skin permeability and physicochemical properties of drugs were examined to establish a predictive method for the steady-state permeation rate of drugs through human skin. Human skin permeation properties fell into two categories: one in which the permeability coefficient is correlated to the partition coefficient, revealed with lipophilic drugs; and the other in which the permeability coefficients are almost constant, shown with hydrophilic drugs. The stratum corneum, the main barrier in skin, could be considered as a membrane with two parallel permeation pathways: lipid and pore pathways, and an equation for predicting the steady-state permeation rate of drugs was derived. The skin permeabilities of drugs for man were compared with those for hairless rat. The species difference in skin permeability found was suggested to be due to the difference in skin permeation pathways, since lipid content and water uptake of the stratum corneum varied between human and hairless rat skin.
Concentration-dependent Exsorption of Quinidine in the Rat Intestine
Authors: Bair Chi-Horng , Tang Ming-Jer , Huang Jin-Ding 
Published: April 2011

Abstract
During intravenous infusion, the luminal concentration of quinidine was higher than the plasma concentration. The intestinal clearance (CLi) of the drug was measured by dividing the rate of appearance of the drug in the intestinal luminal perfusate by the plasma concentration. The CLi of quinidine was therefore much higher than the rate of luminal perfusion. Over the infusion dose range of 0·1–2 mg h−1, the CLi of quinidine decreased with increasing plasma concentration of quinidine. Adding quinidine into the luminal perfusate had little effect on the CLi of quinidine. Co-administration of quinidine with other agents intravenously did not alter the CLi of salicylic acid and urea, while the same treatment decreased the CLi of theophylline and 5-disopyramide. In-vitro experiments on brush-border membrane vesicles showed that quinidine decreased the rate of Na+ uptake and H+ efflux. The inhibition was significant at quinidine concentrations above 20 μm. Quinidine was a more potent inhibitor than amiloride. At quinidine infusion rates less than 2 mg h−1, quinidine concentration in plasma or in the luminal perfusate was at the lower limit of the inhibitory concentration. Microclimate pH at the intestinal surface was also measured. At mid-jejunum, the microclimate pH increased 0·3 pH units by infusing 2 mg h−1 of quinidine, while the microclimate pH at most other measuring sites was not significantly altered by quinidine infusion. It was concluded that quinidine is exsorbed from blood into the intestinal lumen by a carrier-mediated pathway in addition to the passive diffusion. At high plasma concentration, quinidine exsorption becomes saturated. Quinidine inhibited the intestinal exsorption of theophylline and S-disopyramide possibly by competition on the carrier.
Vasorelaxation of Rat Thoracic Aorta Caused by Two Ca2+-Channel Blockers, HA-22 and HA-23
Authors: Yu Sheu-Meei , Kuo Sheng-Chu , Huang Li-Jiau , Sun Selma Siu-Man , Huang Tur-Fu , Teng Che-Ming 
Published: April 2011

Abstract
The pharmacological effects of HA-22 (2-(4′methoxyphenylmethyl)-3,4-dimethylpyrano[2,3-c]pyrazol-6(2H)-one) and HA-23 (2-(2′-thienylmethyl)-3,4-dimethylpyrano[2,3-c]pyrazol-6(2H)-one) on rat isolated thoracic aorta have been examined. In high potassium medium (60 Mm), Ca2+ (0·03–3 Mm)-induced vasoconstriction was inhibited by HA-22 and HA-23 (10–100 μg mL−1). Cromakalim-relaxed aortic rings precontracted with 15 Mm but not 60 Mm K+. However, HA-22, HA-23 and verapamil produced a greater relaxation in 60 Mm than in 15 Mm K+-induced contraction. The tonic contractions elicited by KCl (60 Mm) and Bay K 8644 (10−7 m) were also relaxed by the addition of HA-22 and HA-23. The phenylephrine concentration-response curves displayed antagonism by HA-22 and HA-23 (10–100 μg mL−1) in a non-competitive manner. The caffeine (10 Mm)-induced contraction and cAMP or cGMP levels were not affected by HA-22 or HA-23. It is concluded that HA-22 and HA-23 relaxed the rat aorta by suppressing the Ca2+ influx through both voltage-dependent and receptor-operated Ca2+ channels.
Urinary Excretion of Ephedrine After Nasal Application in Healthy Volunteers
Authors: Lefebvre R A , Surmont F , Bouckaert J , Moerman E 
Published: April 2011

Abstract
The urinary excretion of ephedrine after intranasal administration of the drug was studied in 8 healthy volunteers. Ephedrine (6 drops of a commercial 0·75% nasal ephedrine solution in each nasal cavity) was administered 4 times at intervals of 2 h (total amount applied equivalent to approximately 14 mg ephedrine), and urine was collected each hour for 10 h; the volunteers exercised on a bicycle ergometer at 50% of their V&#x030a;O2max for 2 h after the last ephedrine application. Ephedrine was detected in all urine samples. The urinary ephedrine concentration ranged from 0·9 to 16–5 μg mL−1; the number of urine samples with an ephedrine concentration exceeding 5 μg mL−1 ranged from 1/10 (volunteer 2) to 9/10 (volunteers 1 and 3). The mean percentage of dose recovered within 10 h was 33% (range 23–50%). There was a weak but significant negative correlation between urinary pH and amount of ephedrine in the urine; exercise did not consistently influence the urinary amount. These results illustrate the systemic availability of ephedrine upon intranasal administration and show that the therapeutic use of a nasal ephedrine formulation by an athlete on the day of a competition can lead to a urinary ephedrine concentration above 5 μg mL−1, which is considered positive in current doping regulations of the International Union of Cyclists.
Comparison of salivary fluoride concentrations after administration of a bioadhesive slow-release tablet and a conventional fluoride tablet
Authors: Bottenberg P , Cleymaet R , De Muynck C , Remon J P , Coomans D , Slop D 
Published: April 2011

Abstract
The in-vitro and in-vivo fluoride release of bioadhesive, slow-release tablets prepared from a mixture of polyethylene glycol polymers, containing 0·1 mg of fluoride as NaF was studied, and their ability to sustain fluoride levels in saliva were compared with conventional fluoride tablets with the same fluoride content. In-vitro release experiments showed that the bioadhesive tablets needed 8 h to release all their fluoride compared with &lt; 1 h for the conventional fluoride tablets. In-vivo, the bioadhesive tablets had a retention period of 6 h and could sustain a salivary fluoride level of more than 10 μm above the baseline for 7 h. The conventional fluoride tablets achieved a peak concentration of 0·5 Mm directly after dissolution in the mouth, but the fluoride level could not be sustained for longer than 1 h. A good agreement was found between the in-vitro swelling behaviour of the bioadhesive tablets and their in-vitro and in-vivo release characteristics and their in-vivo retention time.
HI-6 pharmacokinetics in rabbits after intravenous and intramuscular administration
Authors: Lukey B J , Woodard C L , Clark C R , Mccluskey M P 
Published: April 2011

Abstract
The pharmacokinetics of HI-6 ((4-carboxamidopyridinium (1) methyl)-(2′-hydroxyiminomethyl-pyridinium (1′) methyl) ether dichloride) have been studied in rabbits receiving an intramuscular (50 μg kg−1) or intravenous (12·5 μg kg−1) dose. The plasma concentration-time profile for the intramuscular dose (n = 8) fits a one-compartment open model with first-order absorption and elimination. The absorption half-life was 2 min and maximum concentration (51 μg mL−1) was reached in 9 min. The pharmacokinetics for the intravenous dose (n = 8) was described by a two-compartment open model with first-order distribution and elimination. The apparent volume of distribution was 0·1 Lkg−1. Half-lives of distribution and elimination were 5 and 38 min, respectively. The results indicate HI-6 is rapidly absorbed, distributed and eliminated in rabbits receiving an intramuscular dose.
The pH Dependent Uptake of Enoxacin by Rat Intestinal Brush-border Membrane Vesicles
Authors: Iseki Ken , Hirano Takeshi , Fukushi Yuko , Kitamura Yukie , Miyazaki Shozo , Takada Masahiko , Sugawara Mitsuru , Saitoh Hiroshi , Miyazaki Katsumi 
Published: April 2011

Abstract
The mechanism of the intestinal transport of enoxacin, an orally active fluoroquinolone antibiotic, has been investigated using brush-border membrane vesicles isolated from rat small intestine. The initial rate and time-course of enoxacin uptake were considerably dependent upon the medium pH (pH 5·5 &gt; pH 7·5) and upon the percent ionization of the carboxyl group (pKa 6·2, anionic charge), namely, the degree of uptake of cationic form was higher than that of the zwitterionic form. There was evidence of transport into the intravesicular space as shown by the effect of extravesicular medium osmolarity on enoxacin uptake at steady state (30 min). This transport across the brush-border membrane was stimulated by the valinomycin-induced K+-diffusion potential (interior negative) and an outward H+-diffusion potential. Furthermore, changing the pH of the medium from 5·5 to 7·5 significantly decreased the effect of valinomycin-induced K+-diffusion potential on the enoxacin uptake. These results suggest that the uptake behaviour of the cationic form of enoxacin plays an important role in the intestinal absorption process of enoxacin.
Distribution of antipyrine in the rat liver
Authors: Hussein Ziad , Rowland Malcolm 
Published: April 2011

Abstract
The rate and extent of hepatic distribution of antipyrine was examined in the rat isolated perfused liver. Tritiated water and [14C]antipyrine were injected simultaneously into the portal vein as a bolus using either Krebs-Ringer bicarbonate or rat plasma as the perfusate. The effluent profiles of each compound using the two perfusates were superimposable, a finding expected for water and consistent for antipyrine, which was negligibly bound in rat plasma. Although full recovery (97%) of administered material was achieved with both compounds, the fractional output profile for antipyrine peaked at a lower value (0·10 mL−1) and at a later time (24 s) than water (0·14 mL−1, 17·5 s), due to antipyrine having a larger volume of distribution (water 0·61 mL (g liver)−1); antipyrine 0·81 mL (g liver)−1). This observation is explained by antipyrine binding to, or partitioning into cellular components. Nonetheless, like water, distribution of antipyrine into hepatic cells is perfusion rate limited as evidenced by the superimposition of the dimensionless plots of fractional output vs time normalized to mean residence time.
Accumulation of Polyvinylpyrrolidone within the Inflamed Paws of Adjuvant-induced Arthritic Rats
Authors: Seale L , Love W G , Amos N , Williams B D , Kellaway I W 
Published: April 2011

Abstract
125I-Labelled polyvinylpyrrolidone ([125I]PVP) of a range of molecular weights (mol. wt 10, 40 and 360 kDa) was injected i.v. into adjuvant-induced arthritic and normal rats and the blood clearance and tissue distribution of the polymers determined. The half-life of PVP in the circulation increased with increasing mol. wt; 10, 40 and 360 kDa polymers had mean terminal half-lives of 2·2, 6·9 and 16·4 h, respectively. Tissue uptake was also found to be mol. wt dependent, the largest PVP molecule accumulating to a greater extent in the spleen, liver, lungs and paws in both normal and arthritic rats (P &lt; 0·01) than the two lower mol. wt polymers. Accumulation of the polymer in inflamed paws (g tissue)−1 greatly exceeded that of normal paws (P &lt; 0·01). This difference was particularly noticeable with 360 kDa PVP, where arthritic paws amassed 7 times more PVP than normal paws.
Diuretic Action of the Novel Loop Diuretic Torasemide in the Presence of Angiotensin II or Endothelin-1 in Anaesthetized Dogs
Authors: Uchida Takeshi , Hayashi Kazutaka , Kido Hideaki , Watanabe Masahiro 
Published: April 2011

Abstract
The effects of torasemide (0·1 and 1 mg kg−1, i.v.) and furosemide (3 mg kg−1) on renal haemodynamics and excretory responses in the presence of angiotensin II and endothelin-1 was examined in anaesthetized dogs. Angiotensin II or endothelin-1 was continuously infused into the renal artery throughout the experiment and a bolus of torasemide or furosemide was injected into the bracheal vein. Continuous intrarenal arterial (i.r.a.) infusion of angiotensin II, at a dose of 5 ng kg−1 min−1, increased renal vascular resistance (RVR) and decreased renal blood flow (RBF) and glomerular filtration rate (GFR), but had no effect on systemic mean arterial pressure (MAP). Urinary excretion of sodium (UNaV) and urine flow (UF) were significantly decreased during angiotensin II infusion. Intravenous injections of torasemide in the presence of angiotensin II caused a dose-dependent increase in UF, UNaV and urinary excretion of potassium (UKV), while a decrease in RVR was accompanied by an increase in RBF. UKV was greater in the furosemide group than in the torasemide group, despite both groups having the same degree of aquaresis and natriuresis. Continuous i.r.a. infusion of endothelin-1, 1·5 ng kg−1 min−1, produced effects similar to those of angiotensin II on renal haemodynamics; however, the onset of action was extremely slow compared with the effects produced by angiotensin II. Endothelin-1 caused a significant decrease in UF, UNaV and UKV only at a later period, despite a relatively early depression of renal haemodynamics. Torasemide and furosemide also produced a sufficient diuretic action in this model. Overall, kaliuresis was greater in the furosemide group than in the torasemide group. The present study demonstrates that torasemide exhibited a significant diuretic action in the angiotensin II- or endothelin-1 -induced renal impairment model, with less kaliuresis than furosemide at a concentration which caused the same degree of natriuresis.