bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of the Affinity of Drugs toward Serum Albumin by Measurement of the Quenching of the Intrinsic Tryptophan Fluorescence of the Protein
Authors: Epps Dennis E , Raub Thomas J , Caiolfa Valeria , Chiari Augusto , Zamai Moreno 
Published: July 2003

Abstract
Binding of new chemical entities to serum proteins is an issue confronting pharmaceutical companies during development of potential therapeutic agents. Most drugs bind to the most abundant plasma protein, human serum albumin (HSA), at two major binding sites. Excepting fluorescence spectroscopy, existing methods for assaying drug binding to serum albumin are insensitive to higher-affinity compounds and can be labour-intensive, time-consuming, and usually require compound-specific assays. This led us to examine alternative ways to measure drug-albumin interaction.
One method described here uses fluorescence quenching of the single tryptophan (Trp) residue in HSA excited at 295 nm to measure drug-binding affinity. Unfortunately, many compounds absorb, fluoresce, or both, in this UV wavelength region of the spectrum. Several types of binding phenomenon and spectral interference were identified by use of six structurally unrelated compounds and the equations necessary to make corrections mathematically were derived and applied to calculate binding constants accurately. The general cases were: direct quenching of Trp fluorescence by optically transparent ligands with low or high affinities; binding of optically transparent, non-fluorescent ligands to two specific sites where both sites or only one site result in Trp fluorescence quenching; and chromophores whose absorption either overlaps the Trp emission and quenches by energy transfer or absorbs light at the Trp fluorescence excitation wavelength producing absorptive screening as well as fluorescence quenching.
Unless identification of the site specificity of drug binding to serum albumin is desired, quenching of the Trp fluorescence of albumin by titration with ligand is a rapid and facile method for determining the binding affinities of drugs for serum albumin.
Protein Binding of Piroxicam Studied by Means of Affinity Chromatography and Circular Dichroism
Authors: Russeva Veska , Zhivkova Zvetanka , Prodanova Krassimira , Rakovska Rositza 
Published: July 2003

Abstract
The protein binding of piroxicam, a widely used non-steroidal anti-inflammatory drug has been investigated by high-performance liquid affinity chromatography, with phenylbutazone and diazepam used as markers for binding-site characterization, and by circular dichroism titration.
It was found that piroxicam binds to high-affinity phenylbutazone-binding sites and to high-affinity diazepam-binding sites. No binding to the low-affinity sites of either marker was established. High values of the primary (high-affinity) binding constants corresponding to both types of binding site were obtained by means of a mathematical method cited in the literature. The circular dichroic spectra of piroxicam were studied at a given albumin concentration and various drug concentrations. A new Cotton effect was observed and was ascribed to the binding of piroxicam to the protein molecule. The values of differential molar ellipticity (δθ)were treated by a new mathematical procedure for analysis of the data obtained. A high affinity constant was calculated for one class of binding site. Its value is in good agreement with the values obtained by affinity chromatography.
These results reveal that circular dichroism is an acceptable method for investigation of protein binding.
Identification of Urinary Metabolites of Clemastine after Oral Administration to Man
Authors: Choi Man Ho , Jung Byung Hwa , Chung Bong Chul 
Published: July 2003

Abstract
The metabolism of clemastine, 2-{2-[1-(4-chlorophenyl)-1-phenylethoxy]ethyl}-1-methylpyrrolidine, has been studied in three adult male volunteers after a single oral dose of 20 mg as the fumarate. After enzymatic hydrolysis solvent extracts of urine were derivatized with N-methyl-N-trimethylsilyltrifluoroacetamide-ammonium iodide and analysed by gas chromatography-mass spectrometry. The structures of metabolites were determined on the basis of electron impact and chemical ionization mass spectra and the identities of some (e.g. carbinol, 4-chlorobenzophenone and 4-chlorophenylstyrene) were confirmed by use of authentic standards.
The principal route of metabolism of clemastine in man involves direct oxidation, O-dealkylation (fission of the ether bond), aromatic hydroxylation, aliphatic oxidation, alcoholic dehydration, and then enzymatic hydrolysis. Of the total amount of metabolites excreted in the urine 35% was carbinol (metabolite M3, major metabolite), 15% was M1, 17% was M2, 11% was M4, 9% was M5, 8% was M6 and 5% was M7.
Possible Influences of Ginseng on the Pharmacokinetics and Pharmacodynamics of Warfarin in Rats
Authors: Zhu M , Chan K W , Ng L S , Chang Q , Chang S , Li R C 
Published: July 2003

Abstract
We evaluated the significance of a reported clinical case of drug-drug interaction between ginseng and warfarin using a robust pharmacokinetic/pharmacodynamic approach in a rat model.
The influence of ginseng on the pharmacokinetics and pharmacodynamics of oral warfarin after a single dose (2 mg kg−1) and at steady state (0.2 mg kg−1 daily × 6 days) was studied in male Sprague-Dawley rats. Prothrombin time was employed as a pharmacodynamic index. Warfarin plasma concentration and vitamin K content in the ginseng extract were assessed by validated HPLC assays.
The pharmacokinetics of warfarin after a single dose were not altered in the presence of ginseng; peak plasma concentration (control 7.8 ± 0.5; ginseng 7.3 ± 2.5 μg mL−1), time to peak (control 2.6 ± 1.0; ginseng 3.1 ± 1.1h), elimination half-life (control 14.3 ± 5.8; ginseng 10.6 ± 3.1h), and oral clearance (control 17.5 ± 3.3; ginseng 20.2 ± 5.5 mL h−1) were not significantly different (P &gt; 0–05). Similarly, alterations in the pharmacokinetics of warfarin were not detected under the multiple dosing paradigm. Under both dosing conditions, ginseng also showed no significant impact on the pharmacodynamics of warfarin as assessed by the area under the prothrombin time vs time curve (multiple dosing; control 3776 ± 619, ginseng 3830 ± 362 s h) and maximum prothrombin time (control 57.2 ± 11.8, ginseng 63.3 ± 9.1 s). Furthermore, the content of vitamin K was undetectable in the ginseng decoction.
In conclusion, current data obtained in the rat showed no significant impact of ginseng on the pharmacokinetics/pharmacodynamics of warfarin when they are concomitantly administered.
Forskolin Reverses Tachyphylaxis to the Bronchodilator Effects of Salbutamol: An In-vitro Study on Isolated Guinea-pig Trachea
Authors: Yousif Mariam H , Thulesius Olav 
Published: July 2003

Abstract
The objective of this study was to assess the relaxant responses of salbutamol, a β2 agonist, and forskolin, an activator of adenylate cyclase, and the possible role of forskolin in reversing tachyphylaxis to salbutamol.
The in-vitro bronchodilator effects of salbutamol and forskolin (10−9-10−5M) were tested on isolated guinea-pig tracheal rings precontracted with carbachol (10−7M). Both salbutamol and forskolin elicited concentration-dependent relaxation. Potency (EC50; the dose resulting in 50% relaxation) was determined from cumulative concentration-response curves. Salbutamol was more potent than forskolin in relaxing the tracheal preparations (-log molar EC50 7.68 ± 0.14 and 6.3 ± 0.17, respectively). Reproducible relaxant responses to salbutamol could be elicited after 24h incubation in Krebs solution. Tachyphylaxis to the relaxant effects of salbutamol was experimentally induced by incubation (24h) of the preparations in Krebs solution containing salbutamol (10−6, 3 × 10−6 or 10−5M). This pretreatment of the tissues resulted in a significant reduction in the potency of salbutamol. The potency of salbutamol was reduced to 6.85 ± 0.2, 6.8 ± 0.1 and 5.9 ± 0.27 after 24h incubation with salbutamol 10−6, 3 × 10−6 or 10−5M, respectively. The potency of salbutamol was increased from 7.35 ± 0.2 to 7.76 ± 0–28 by addition of forskolin (3 × 10−7M) under control conditions. Moreover, forskolin (3 × 10−7M) reversed the development of tachyphylaxis to salbutamol-induced relaxation in tissues pretreated with salbutamol. The potency of salbutamol was increased to 7.29 ± 0.41, 7.37 ± 0.17 and 7.23 ± 0.35 after the addition of forskolin (3 × 10−7M) to preparations pre-incubated (24h) with salbutamol 10−6, 3 × 10−6 or 10−5M respectively.
These results show that in guinea-pig tracheal ring preparations, forskolin shares with salbutamol the ability to relax airway smooth muscle and produces an apparent reversal of tachyphylaxis to the bronchodilator effects of salbutamol, particularly in the low concentration range. This effect could provide an alternative therapy for long term use, particularly with high doses of β2 agonists in bronchial asthma.
Characterization of Dopamine Receptor Subtypes Involved in Experimentally Induced Gastric and Duodenal Ulcers in Rats
Authors: Desai Jagruti K , Goyal Ramesh K , Parmar Narayan S 
Published: July 2003

Abstract
There are conflicting reports about the role of dopamine in gastric and duodenal ulcers. This investigation was undertaken to characterize the specific subtypes of dopamine receptor involved in gastric and duodenal ulceration.
Administration of dopamine D1 agonist fenoldopam and dopamine D2 antagonist sulpiride elicited a significant decrease in acid secretion, total acid output, pepsin output and histamine content in the gastric juice, and reduced ulcer-index values, in pylorusligated rats. However, dopamine D1 receptor antagonist SCH 39166 ((-)-trans-6,7, 7a,8,9,13b-hexahydro-3-chloro-2-hydroxy-N-methyl-5H-benzo (d) naptho - (2,1-b) azepine) and the D2 receptor agonist quinpirole led to significant augmentation of these parameters compared with respective controls. In the restraint plus water-immersion stress model the score for intraluminal bleeding and the cumulative gastric lesion length was significantly lower for rats treated with fenoldopam and sulpiride. The opposite effects were observed after pretreatment of rats with SCH 39166 and quinpirole. In the cysteamine-induced duodenal ulcer model the mean ulcer area and the score for intensity were significantly lower for fenoldopam and sulpiride and higher for SCH 39166 and quinpirole.
Our data suggest that the dopamine D1 and D2 receptors have opposite effects on gastric and duodenal ulcers. Whereas stimulation of dopamine D1 receptors inhibits the formation of gastric and duodenal ulcers, stimulation of dopamine D2 receptors has a pro-ulcerogenic effect.
Isolation, Purity Analysis and Stability of Hyperforin as a Standard Material from Hypericum perforatum L.
Authors: Orth H C J , Rentel C , Schmidt P C 
Published: July 2003

Abstract
In 1996 131.5 million daily doses of preparations containing extracts of Hypericum perforatum L. were prescribed in Germany for treating mild to moderately severe depressive disorders. New pharmacological and clinical results focus on hyperforin as the main active ingredient of the drug.
Hyperforin (C35H52O4) is one of the main components (2–4%) of the dried herb Hypericum perforatum L. It was isolated after six consecutive steps: extraction of deep-frozen blossoms (-20°C) with n-hexane by means of an Ultra Turrax at room temperature; separation of lipophilic substances on a silica gel column; purification of the relevant fraction by preparative HPLC; evaporation of the mobile phase under reduced pressure; removal of the remaining water by freeze-drying; and storage of hyperforin at −20°C under nitrogen. The identity and purity of the isolated substance were determined by highperformance thin-layer chromatography (HPTLC), high-performance liquid chromatography (HPLC) with diode-array and ultraviolet detection (DAD and UV), Fourier-transformed infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopy, and liquid chromatography coupled with positive-ion electrospray-ionization tandem mass spectrometry (LC-ESI(+)-MS-MS). By use of these methods the purity of hyperforin was shown to be &gt;99-9%. Peroxides present at each step of the isolation were detected by titration and by means of Merckoquant analytical peroxide test-strips. Elimination of the peroxides and stabilization of hyperforin was achieved by consistent protection from oxidation—the mobile phases were protected by use of ascorbic acid; evaporation and freeze-drying were performed under nitrogen; and the mobile phase used for preparative HPLC was sparged with helium. Stability testing was performed by HPLC—the samples were stored at −30°C in a normal atmosphere and at −20, 4, and 20°C in a normal atmosphere or under nitrogen. Results were compared with those obtained after storage under liquid nitrogen (-196°C).
Because of its high sensitivity to oxidation, hyperforin was more stable under nitrogen under all test conditions. There was no statistically significant difference between results obtained after 8 months at −20°C under nitrogen or at −30°C under a normal atmosphere and those from the reference sample stored under liquid nitrogen (-196°C). Despite this, because of the tendency of hyperforin to degrade, long-term storage at −70°C under nitrogen is recommended.
A Novel Image-analysis Technique for Measurement of Bacterial Cell Surface Tension
Authors: Hanlon G W , Olliff C J , Brant J A , Denyer S P 
Published: July 2003

Abstract
Cell-surface hydrophobicity is different for Staphylococcus epidermidis cells grown under different environmental conditions; this might influence attachment and colonization of surfaces. Although a wide variety of techniques has been employed to measure bacterial surface hydrophobicity, including contact angle determinations, adherence to hydrocarbons, hydrophobic-interaction chromatography and salt aggregation, many of these either require large numbers of cells or do not yield comparable quantitative data. This study describes a novel, quantitative method for the determination of bacterial surface tension on the basis of image analysis of cell-cell interactions.
S. epidermidis (strains 900 and 901) were suspended in different concentrations of propanol of known surface tension and examined by bright-field microscopy linked via a charge-couple device (CCD) camera to an image analyser. Frames were chosen randomly and the data recorded as a ratio of count/percentage coverage for each frame. The results showed that for strains 900 and 901 this ratio was maximum at surface tensions of 67 and 61 mN m−1 respectively. At these values of minimal interaction the surface tension of the liquid was equal to the bacterial cell surface tension. The results were in close agreement with those obtained from contact angles. The advantage of surface tension measurements is that, irrespective of the method used, the results generated are quantitative values and are therefore directly comparable.
The method reported is reliable, reproducible and is of particular value because the number of cells required is, typically, at least two orders of magnitude lower than is required for commonly used alternative methods.
Effect of the Chloroform Extract of Tanacetum vulgare and one of its Active Principles, Parthenolide, on Experimental Gastric Ulcer in Rats
Authors: Tournier Horacio , Schinella Guillermo , De Balsa Elba M , Buschiazzo Héctor , Mañez Salvador , De Buschiazzo Perla Mordujovich 
Published: July 2003

Abstract
This study examines the anti-ulcerogenic activity of a chloroform extract of Tanacetum vulgare and purified parthenolide, the major sesquiterpene lactone found in the extract.
Gastric ulcers induced by oral administration of absolute ethanol to rats were reduced dose-dependently by oral pretreatment of animals with the chloroform extract (2.5–80 mg kg−1) or parthenolide (5–40 mgkg−1). When administered 30 min before challenge with the alcohol the protection ranged between 34 and 100% for the extract and 27 and 100% for parthenolide. When the products were administered orally 24h before treatment with ethanol, 40 mg kg−1 of the extract and of the lactone reduced the mean ulcer index from 4.8 ± 0.3 for control animals to 1.4 ± 0.2 and 0.5 ± 0.1, respectively. The products also prevented alcohol-induced reduction of the number of sulphydryl groups within the gastric mucosa (50.6 ± 2.3 μg (mg protein)−1 for normal animals compared with 17.7 ± 3.0 μg (mg protein)−1 for alcohol-treated animals). Administration of the extract (80 mg kg−1) or parthenolide (40 mg kg−1) 24h before ethanol treatment restored the numbers of mucosal -SH groups to values near those found for normal animals.
These results suggest that the products assayed, in particular parthenolide, might find therapeutic application, although further work is required to establish their profit/risk ratio.
Lavender Oil Inhibits Immediate-type Allergic Reaction in Mice and Rats
Authors: Kim Hyung-Min , Cho Seong-Hoon 
Published: July 2003

Abstract
We studied the effects of lavender oil on mast cell-mediated immediate-type allergic reactions in mice and rats.
Lavender oil (1:500, 1:100, 1:10, 1:1, 1:0) inhibited concentration-dependently mast cell-dependent ear swelling response induced by compound 48/80 in mice by both topical and intradermal application. Lavender oil (1:500, 1:100, 1:10, 1:1, 1:0) inhibited concentration-dependently passive cutaneous anaphylaxis induced by anti-dinitrophenyl (DNP) IgE in rats by both topical and intradermal application.
Lavender oil (1:500, 1: 100, 1: 10, 1:1, 1:0) also inhibited concentration-dependently the histamine release from the peritoneal mast cells by compound 48/80 or anti-DNP IgE. Moreover, lavender oil (1:1000, 1:100, 1:10, 1:0) had a significant inhibitory effect on anti-DNP IgE-induced tumour necrosis factor-α secretion from peritoneal mast cells.
These results indicate that lavender oil inhibits immediate-type allergic reactions by inhibition of mast cell degranulation in-vivo and in-vitro.
Effects of Fosfomycin and Imipenem-Cilastatin on the Nephrotoxicity of Vancomycin and Cisplatin in Rats
Authors: Nakamura Tsutomu , Kokuryo Toshiyuki , Hashimoto Yukiya , Inui Ken-Ichi 
Published: July 2003

Abstract
The nephrotoxicity of vancomycin and cisplatin and the protective effects of fosfomycin and imipenem-cilastatin on renal function have been studied in rats. The renal clearance of vancomycin after the induction of renal dysfunction was also evaluated by calculating the glomerular filtration rate (GFR) and its secretory clearance.
Plasma concentrations of creatinine and urea nitrogen increased dose-dependently after vancomycin injection. No such increases were observed after co-treatment with fosfomycin or imipenem-cilastatin. Changes of N-acetyl-β-D-glucosaminidase activity in the urine of vancomycin-treated rats were not remarkable compared with those in cisplatin-treated animals. The reduced renal clearance of vancomycin in rats with acute renal failure induced by vancomycin was because of a decrease in both GFR and secretory clearance. However, the changes in GFR and secretory clearance were not proportional—the change in GFR was more pronounced than that of secretory clearance in the experimental groups. In addition, the renal clearance of vancomycin was maintained at the control level after co-administration of fosfomycin or imipenem-cilastatin with vancomycin.
These results suggest that vancomycin impairs glomerular filtration more markedly than renal tubular function as compared with cisplatin. Co-administration with fosfomycin or imipenem-cilastatin confers significant protection against the nephrotoxic effects of vancomycin.
A New Method for Monitoring the Contamination of Glycerol with Diethylene Glycol
Authors: Gomes M T S R , Veríssimo M I S , Oliveira J A B P 
Published: July 2003

Abstract
A quartz crystal microbalance has been used to check the purity of glycerol.
The experimental procedure involves no derivatization or other preliminary step except determination of water content. The protocol consists of the direct reading of the frequency of a quartz crystal with one face in contact with an aqueous solution of the glycerol to be tested.
The method is inexpensive, simple, rapid, and highly sensitive; diethylene glycol contamination at the 3.61% level could be detected.
Discovery of New Antimalarial Compounds by use of Molecular Connectivity Techniques
Authors: Gozalbes R , Gálvez J , Moreno A , García-Domenech R 
Published: July 2003

Abstract
Molecular connectivity has been applied to the search for new compounds with antimalarial activity. Linear discriminant analysis and connectivity functions were used to select several potentially suitable drugs which were tested for antimalarial properties by use of an in-vitro micro test which estimates parasite growth by measurement of incorporation of [3H]hypoxanthine.
Hexetidine stands out among the compounds selected. Activity assays were performed with Plasmodium falciparum passou and 3CD7 strains, for which the IC50 values (doses resulting in 50% inhibition) were 320 and 400 ng mL−1 respectively. These results are comparable with those obtained for quinine chlorhydrate (IC50 = 60 and 107.8 ng mL−1) and chloroquine sulphate (IC50 = 231 and 415 ng mL−1), the drugs used for reference.
These results demonstrate the usefulness of our topological approach for the selection and design of new lead drugs active against Plasmodium falciparum.
A New Insulin-mimetic Vanadyl Complex, (N-Pyridylmethylaspartate)oxovanadium(IV) with VO(N2O2) Coordination Mode, and Evaluation of its Effect on Uptake of D-Glucose by Ehrlich Ascites Tumour Cells
Authors: Tawa Riichi , Uchida Keiko , Taniyama Junko , Fujisawa Yae , Fujimoto Seiki , Nagaoka Takashi , Kanamori Kan , Sakurai Hiromu 
Published: July 2003

Abstract
Because it has been confirmed that the vanadyl(IV) ion and its complexes act as insulin mimetics, a new organic vanadyl complex, (N-pyridylmethylaspartate)oxovanadium (VOPASP) with VO(N2O2) coordination mode, was prepared. Development of a simple and rapid in-vitro assay is needed for recognition of potent insulin-mimetic complexes.
Treatment of Ehrlich ascites tumour cells with 2-deoxyglucose in the presence of vanadyl sulphate, or other vanadyl complexes with the same coordination mode (VOPASP, bis(picolinate)oxovanadium (VOPA) and bis(6-methyl picolinate)oxovanadium (VOMPA)), in the presence of 2-deoxy-D-[1-3H]glucose ([3H]deoxyglucose), resulted in concentration-dependent uptake of 2-deoxyglucose by the cells. The responses of the cells to the vanadyl complexes were reflected, in part, by results obtained from the free fatty acid-releasing assay using rat adipocytes.
These results show that the in-vitro assay with Ehrlich ascites tumour cells provides an accurate and rapid assessment of glucose uptake by the cells. The assay is proposed as a means of predicting the insulin-mimetic activity of the vanadyl complexes and for studying the mechanism of action of the complexes.