bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid chiral separation of metoprolol in plasma—application to the pharmacokinetics/pharmacodynamics of metoprolol enantiomers in the conscious goat
Authors: Leloux M. S. 
Published: May 2005

AbstractThe plasma concentrations of metoprolol enantiomers have been determined by means of a direct phenyl carbamate‐cellulose‐based chiral high performance liquid chromatography assay using fluorimetric detection. This assay has been used to investigate the pharmacokinetics and pharmacodynamics of metoprolol enantiomers in the conscious goat. There is evidence that the pharmacokinetics of metoprolol in the goat occurs stereoselectively and that enantiomer–enantiomer pharmacokinetic interactions occur. R‐Metoprolol is less effective in reducing the mean arterial blood pressure than S‐ and R/S‐metoprolol.
Dissolution assay of theophylline, diprophylline and proxyphylline from a sustained release dosage form by high performance thin layer chromatography
Authors: Agbaba D. , Živanov‐Stakić D. , Vukićević N. 
Published: May 2005

AbstractThe content and dissolution rate of theophylline, diprophylline and proxyphylline from a sustained release formulation were determined by UV in situ densitometry. After separation the chromatographic zones corresponding to the spots of theophylline, diprophylline and proxyphylline on the high performance thin layer chromatographic plates were scanned in reflectance/absorbance mode at 275 nm. Quantification was performed with a second degree polynomial function over the range 40–200 ng for theophylline and 60–300 ng for diprophylline and proxyphylline. Percentages of dissolved theophylline, diprophylline and proxyphylline were monitored over 1, 3 and 6 h. The method was found to be simple, accurate, reliable, time‐saving (up to 18 samples can be determined simultaneously) and low‐cost.
Chiral separation by high performance liquid chromatography. I. Review on indirect separation of enantiomers as diastereomeric derivatives using ultraviolet, fluorescence and electrochemical detection
Authors: Srinivas Nuggehally R. , Igwemezie Linus N. 
Published: May 2005

AbstractThe increased attention on the therapeutic implications of stereoisomerism has provided an impetus for the development of analytical methods for enantiomeric separation. The indirect method of separation of enantiomers as diastereomers using high performance liquid chromatography (HPLC) has emerged as an efficient and versatile approach. This is due mainly to the availability of numerous chiral derivatization reagents (CDRs). This article reviews CDRs useful for the development of an indirect HPLC method using ultraviolet, fluoresence and electrochemical detection. In addition, factors crucial for the development of the indirect method are discussed.
Use of immobilized metal ions as a negative adsorbent for purification of enzymes: Application to phosphoglycerate mutase from chicken muscle extract and horseradish peroxidase
Authors: Chaga Grigory , Andersson Lennart , Ersson Bo , Berg Mikael 
Published: May 2005

AbstractTwo enzymes, phosphoglycerate mutase and peroxidase, were purified by using an immobilized metal ion adsorbent for the removal of unwanted proteins. The mutase was obtained pure from a single column, whereas the purification of peroxidase required the use of a thiophilic adsorbent in a tandem. The capacity was 2.5 mg pure peroxidase per mL gel.
Liquid chromatographic determination of hyoscine (scopolamine) in urine using solid phase extraction
Authors: Whelpton Robin , Hurst Peter R. , Metcalfe Roger F. , Saunders Sally A. 
Published: May 2005

AbstractA sensitive method for the determination of hyoscine (scopolamine) in urine is described. After concentration and “clean‐up” on C18 and CN solid phase extraction columns, hyoscine was quantified by high performance liquid chromatography with coulometric detection (oxidation at +0.9 V). The limit of detection was 5 ng per sample and the precision for 5 mL samples containing 2 ng/mL was 12.3%. The method was applied to urine samples collected from 12 volunteers wearing Scopoderm TTS patches. The mean excretion rate of unmetabolized hyoscine was 0.45 μg/h and 87% of the total hyoscine was present as conjugates. Apohyoscine (aposcopolamine) was identified as a urinary metabolite. The significance of this with regard to hyoscine assays is discussed.
High performance liquid chromatographic determination of 3α, 5β‐tetrahydroaldosterone and cortisol in human urine with fluorescence detection
Authors: Yoshitake Takashi , Ishida Junichi , Sonezaki Shinji , Yamaguchi Masatoshi 
Published: May 2005

AbstractA simple and sensitive method for the simultaneous determination of 3α, 5β‐tetrahydroaldosterone (THALD) and cortisol in human urine is described. The method uses high performance liquid chromatography with fluorescence detection. THALD and cortisol, released by enzyme hydrolysis, and fludrocortisone (internal standard) are isolated by a Sephadex G‐25M column and a Bond‐Elut C18 cartridge, and then oxidized by cupric acetate to form the corresponding glyoxal derivatives. The glyoxal derivatives are converted into the fluorescent quinoxalines by reaction with 1,2‐diamino‐4,5‐methylenedioxybenzene. The quinoxalines are successfully separated on a reversed phase column (L‐column ODS) with isocratic elution and monitored fluorimetrically. The detection limits for THALD and cortisol are 0.45 and 1.18 ng/mL urine (0.65 and 2.65 pmol/100 μL injection volume), respectively, at a signal‐to‐noise ratio of 3 in a 100 μL injection volume. This method permits the precise and sensitive determination of THALD and cortisol in human urine (2 mL).
Detection of abnormal haemoglobin by capillary electrophoresis and structural identification
Authors: Ishioka Noriaki , Iyori Naoko , Noji Jun , Kurioka Susumu 
Published: May 2005

AbstractHaemoglobin obtained from a male adult Ghanian with retinopathy, which was probably caused by haemoglobinopathy was analysed by capillary electrophoresis (CE) for clinical diagnosis. Two major peaks, which were in the ratio of nearly one, were detected. The elution times of these peaks (HbXI and HbXII) were faster than that of normal haemoglobin (HbA). The existence of two different abnormal types of haemoglobin was clear in the patient blood. The following sequence analysis revealed that the first peak (HbXI) was HbC and the second (HbXII) was HbS on the electropherogram, and that the patient was a heterozygote of HbS and HbC (HbSC disease). One of the diagnostic processes in a haemoglobin disease was shown by the combined use of CE, HPLC and a protein sequencer.
Detection of gangliosides with the fluorochrome NBD dihexadecylamine and its application for preparative high performance thin layer chromatography
Authors: Müthing Johannes , Unland Frank 
Published: May 2005

AbstractA new method for the detection of gangliosides based on the lipophilic fluorescence agent 4‐(N,N‐dihexadecyl)amino‐7‐nitrobenz‐2‐oxa‐1,3‐diazole (NBD dihexadecylamine) and its application for preparative high performance thin layer chromatography is described. Brain gangliosides were chromatographed on silica gel coated thin layer plates and located with non‐destructive fluorochrome under longwave ultraviolet light. The fluorescent zones were scraped off and the gangliosides were extracted with a mixture of chloroform/methanol/water (30/60/8; v/v/v). The gangliosides were separated from uncharged NBD dihexadecylamine by anion exchange chromatography and impurities were removed by Iatrobeads chromatography. The method described offers a simple and succesful preparative thin layer chromatographic strategy to obtain pure gangliosides in microgram and milligram quantities.
The retention behaviour of conjugated bile acids in reversed phase high performance liquid chromatography
Authors: Zhang Y. K. , Chen N. , Zao R. H. , Li T. , Wang Z. Y. , Lu P. C. 
Published: May 2005

AbstractThe retention behaviour of conjugated bile acids has been studied in a reversed phase high performance liquid chromatographic (RP‐HPLC) system by using the mixture of methanol and aqueous phosphate buffer as the mobile phase. The retentions of the conjugates in RP‐HPLC have been found to be mainly controlled by the glycine and taurine groups. The selectivity between five different glycine and taurine conjugated bile acids is a constant in RP‐HPLC. This selectivity has been used for peak identification in the practical separation of conjugated bile acids.
Determination of MDL 201,012 at femtomole/millilitre levels in human plasma by liquid chromatography with electrochemical detection
Authors: Reynolds Donald L. , Eichmeier Larry S. , Giesing Dennis H. 
Published: May 2005

AbstractA sensitive and selective liquid chromatographic method to quantitate MDL 201,012 in human plasma was developed and validated. MDL 201,012 (I), diethyl‐MDL 201,012 (internal standard, II) and desmethyldiol‐MDL 201,012 (masking agent, III) were isolated from basified plasma (2 mL) by solid phase extraction using Bond‐Elut® C‐18 cartridges. Endogenous components were selectively removed prior to eluting the analytes from the sorbent. Components were separated using on‐line LC column switching with a cyanopropyl precolumn and a phenyl analytical column. The analytical column effluent was monitored electrochemically at a glassy carbon electrode at a potential of + 1025 mV vs. Ag/AgCI. Peak‐height ratios were proportional to the amount of MDL 201,012 added to plasma over the range 125–7500 pg/mL MDL 201,012. Absolute recovery of MDL 201,012 from human plasma was >94% across the calibration range. The minimum quantitation limit was 125 pg/mL. Assay precision (%RSD) ranged from 5.2 to 13% based on the analysis of quality control standards containing 125, 250, 500, 1000, 2500, 5000 and 7500 pg/mL MDL 201,012. Corresponding assay accuracy (% relative error) was ±8.5%. The method has been successfully used to quantitate MDL 201,012 in samples from acute dose tolerance studies in human volunteers.
Lead and the terminal mitochondrial enzymes of haem biosynthesis
Authors: Rossi E. , Taketani S. , Garcia‐Webb P. 
Published: May 2005

AbstractLead exposure causes increases in urinary coproporphyrin excretion and the accumulation of zinc protoporphyrin in red cells. In the conventional view of the effect of lead on haem biosynthesis, the accumulation of these metabolites results from lead inhibition of two of the mitochondrial enzymes of haem biosynthesis, corproporphyrinogen oxidase (EC 1.3.3.3.) and ferrochelatase (EC 4.99.1.1). This review critically assesses the evidence for the inhibition of these enzymes. We consider this evidence to be inconclusive and alternative explanations for the increased concentrations of coproporphyrin and zinc protoporphyrin are proposed.
Biodegradation of a carbamate pesticide, propoxur, in rat tissues
Authors: Kumar Reena , Madhavi N. B. Bindu , Sharma C. B. 
Published: May 2005

AbstractPropoxur (Baygon, 2‐isopropoxyphenyl N‐methylcarbamate) is a carbamate pesticide commonly used against house insects. When the insecticide was administered intramuscularly in rats it was converted to a new metabolite which was found to be present in the serum, liver, kidney and brain 6 h after the administration of the pesticide. The metabolite was purified by high performance liquid to chromatography and comparison of the infrared spectra of Propoxur and the metabolite showed that a deamination reaction was responsible for the formation of the metabolite from the parent pesticide. The pesticide also induced haematological changes such as an increased level of total bilubrin, amylase and glutamic–oxalacetic transaminase and decrease of cholinesterase activity, indicating damage of the liver and nervous system in rats.
Simultaneous determination of salbutamol and terbutaline at overdose levels in human plasma by high performance liquid chromatography with electrochemical detection
Authors: Sagar Kamal A. , Kelly Mary T. , Smyth Malcolm R. 
Published: May 2005

AbstractA multidimensional column chromatographic method involving electrochemical detection using a carbon fibre microelectrode flow cell was optimized and successfully applied to the simultaneous determination of salbutamol and terbutaline in plasma at overdose levels. This method performs, in a single step, an efficient extraction and clean‐up of salbutamol and terbutaline from human plasma. The calibration graphs over three days were linear over the calibration range 20–100 ng/mL plasma with a limit of detection of 1 ng and 0.8 ng/mL plasma for salbutamol and terbutaline, respectively. The intra‐ and inter‐assay coefficients of variation were less than 8% and the recoveries ranged from 94 to 96%. The accuracy of the assay, which was defined as the percentage difference between the mean concentration found and the theoretical concentration, was 7% or better. The proposed method combines the advantages of being simple, reproducible and selective in the presence of other sympathomimetic and commonly ingested drugs and is suitable for routine analyses to obtain valuable information about the clinical effects and treatment of overdose with these drugs. The whole procedure takes ca. 10 min and compares favorably with detection at a conventional glassy carbon electrode.
Studies on silica‐bonded monoclonal antibody packing material for separation of recombinant interferon by high performance immunoaffinity chromatography
Authors: Feng Wenke , Geng Xindu 
Published: May 2005

AbstractA method for the preparation of a new packing material for high performance liquid chromatography by bonding an anti‐interferon monoclonal antibody to the surface of silica gel is described. The high coupling efficiency and activity of the interferon‐αA‐monoclonal antibody (IFN‐αA‐McAb) column were obtained by activated diol‐silica gel with an activating agent. After purification with this packing material, the specific activity of recombinant human interferon‐αA rose by up to 1.03 × 107IU/mg protein and the purification efficiency was increased by approximately 100 times.
Use of blue‐sepharose for purification of immunotoxin containing type 1 ribosome‐inactivating protein, gelonin
Authors: Masuda Kazuyoshi , Hirano Koichiro , Takagishi Yasushi 
Published: May 2005

AbstractThis paper describes a method suitable for purifying immunotoxin containing type 1 ribosome‐inactivating protein, gelonin. The separation of free (unreacted) 80G, a monoclonal antibody against α‐fetoprotein (AFP), from semipurified 80G–gelonin conjugate was unsuccessful by conventional CM‐Sepharose ion‐exchange chromatography because the isoelectric point of the conjugate did not increase enough to reach that of gelonin alone. In contrast, Blue Sepharose affinity chromatography could efficiently separate free 80G from the semipurified conjugate because the conjugate was bound to the column by its gelonin moiety while free 80G was not in buffer containing NaCl of a particular concentration range. However, a small amount of conjugate containing gelonin modified with N‐succinimidyl 3‐(2‐pyridyldithio)propionate, but not with 2‐iminothiolane, could not bind to the column. The conjugate purified by the use of Blue Sepharose showed selective cytotoxicity against AFP‐producing human hepatoma cells.
Charge‐transfer chromatographic study on the interaction of amino acids with ethoxylated stearic acid surfactants
Authors: Cserháti Tibor 
Published: May 2005

AbstractThe interaction of amino acids with ethoxylated stearic acid nonionic surfactants was studied by charge‐transfer reversed‐phase thin‐layer chromatography and the relative strength of interaction was calculated. In the majority of cases the surfactant has a negligible effect on the hydrophobicity of amino acids. Only the binding of Asn, Cys, Gln, Leu, Lys, Met, Nle, Phe, Ser, Trp and Tyr to the surfactants was observed, however, the strength of interaction was fairly low. Stepwise regression analysis proved that the electronic parameters of the amino acids have the highest impact on the strength of interaction. This finding supports the hypothesis that the binding of ethoxylated stearic acid nonionic surfactants to proteins involves more than one amino acid residues and that the hydrophilic forces have a considerable impact on the interaction.
Automated HPLC analyses of drugs of abuse via direct injection of biological fluids followed by simultaneous solid‐phase extraction and derivatization with fluorescence detection
Authors: Bourque A. J. , Krull I. S. , Feibush B. 
Published: May 2005

AbstractAn automated system is described for the simultaneous extraction and derivatization of nucleophilic compounds from various biological media. The method includes the use of a solid‐phase reagent containing a 9‐fluorenylacetate activated ester. The reagent is based on a controlled pore, polystyrene divinylbenzene support prepared through a silica template procedure. An X‐Y‐Z robotic arm equipped with a needle is used in conjunction with a syringe pump for aspirating and dispensing samples and standards into the HPLC system. A precolumn cartridge containing the solid‐phase reagent is put on‐line in place of the fixed‐volume injection loop. Injections of biological fluids such as urine or plasma with minimal sample treatment and handling are made directly into this reactor. The analytes are dervatized as they are extracted, allowing virtually unlimited sample volumes to be injected. The polymeric cartridge can be used for up to 100 injections without accruing unacceptable reductions in sensitivity. A detection limit of 500 p.p.t. (parts per trillion) of amphetamine in urine was achieved with this system.
Improved thin layer chromatographic resolution of PTH amino acids with some new solvent systems
Authors: Bhushan R. , Mahesh V. K. , Varma A. 
Published: May 2005

AbstractThree new solvent systems, pyridine: benzene (2.5:20, v/v), methanol: carbon tetrachloride (1:20, v/v) and acetone : dichloromethane (0.3:8, v/v), for the resolution of a mixture of 18 PTH amino acids have been reported. Using these solvent systems, various combinations of PTH amino acids which had previously posed resolution problems have been resolved and identified.
UV‐transparent, replaceable agarose gels for molecular‐sieve (capillary) electrophoresis of proteins and nucleic acids
Authors: Hjertén Stellan , Srichaiyo Tasanee , Palm Anders 
Published: May 2005

AbstractGels of methoxylated agarose (gelling point 25.6 °C) and other low‐melting agarose derivatives compare favorably with cross‐linked polyacrylamide gels for capillary and slab molecular‐sieve electrophoresis of proteins and DNA. These agarose gels can be pressed out of the capillary following a run and replaced by an agarose solution with a temperature of 35–40 °C. Gelation occurs upon lowering the temperature and the same capillary can thus be reused for another analysis with a fresh gel. The methoxylated, non UV‐absorbing agarose gels are, accordingly, replaceable, which makes them very attractive for series analyses with modern, automated capillary electrophoresis apparatus. The high resolution of these agarose gels is demonstrated with a separation of an albumin sample into monomers, dimers, trimers, tetramers, pentamers, hexamers, heptamers, and of DNA fragments.
A simple method for the determination of YM060 in plasma and urine by high performance liquid chromatography
Authors: Miura Hiroya , Takeshige Tetsuo , Kobayashi Shin‐Ichiro , Higuchi Saburo 
Published: May 2005

AbstractWe developed a simple method for the determination of YM060, a new 5‐HT3 receptor antagonist, in plasma and urine. The method has good accuracy and precision, and sufficient sensitivity to allow use in pharmacokinetic studies of YM060 in humans and laboratory animals.
Theoretical consideration on polarized photometric detection
Authors: Hayakawa Kazuichi , Yamamoto Atsushi , Matsunaga Akinobu , Mizukami Eiichi , Nishimura Masayuki , Miyazaki Motoichi 
Published: May 2005

AbstractPreviously, we developed a novel detector, a polarized photometric detector for optically active compounds, where two polarizers are set on either side of the UV‐visible absorbance detector flow cell. In this paper, we present theoretical considerations on this method with several equations. If the inclined angle of the second polarizer is defined as α (left when α > 0°), the following equation is obtained: ΔAbs = 2 log e · tan α · β, where ΔAbs is the change in absorbance and β (|β| ≪ α) is the angle of rotation of light passing through the cell containing the optically active compound. This equation suggests that ΔAbs is proportional to the analyte concentration and that the dextro‐ and laevorotatory compounds are detected as positive and negative absorbance changes, respectively. The theoretical maximum signal to noise (S/N) ratio is obtained when α = 45° (=0.8 rad) and the smallest detection limit is 5 × 10−5° (S/N = 3) when the path length of the flow cell is 10 mm. This detector was successfully used in flow injection analysis (FIA) as well as HPLC for optically active compounds.
A new matrix for affinity chromatography and its application in the separation of a human monoclonal antibody
Authors: Guo Wei , Shang Zhenhua , Yu Yinian , Zhou Liangmo 
Published: May 2005

AbstractA method for the preparation of a p‐aminobenzene sulphonyl ethyl containing crosslinked Sepharose 4B (ABSE‐Sepharose 4B‐CL) is described. trypsin, bovine serum albumin (BSA) and concanavalin A (Con A) were immobilized onto this matrix by diazotization. Conditions for the coupling reaction were investigated. The activity of immobilized trypsin reached 1.4 × 104U/g, and 25 mg BSA can be coupled onto 1 g ABSE‐Sepharose 4B‐CL under the optimal conditions. An affinity medium with immobilized Con A as ligand was prepared by this method, and was used in the separation of a human monoclonal antibody.
Separation and identification of proteins obtained from Agkistrodon acutus snake venom by capillary zone electrophoresis and laser desorption/ionization mass monitoring
Authors: Zhang Yukui , Chen Nong , Wang Lei , Yang Boyu , Qian Xiaohong , Ma Liran 
Published: May 2005

AbstractFractions of seven protein principles with fibrinolytic or thrombin‐like activities obtained from Agkistrodon acutus snake venom purified by two steps of normal pressure chromatography were separated further by capillary zone electrophoresis (CZE). Mass determination for these fractions were achieved by performing laser desorption/ionization mass monitoring (LDIM). The comparative study between CZE and LDIM on the separation of these fractions was made.
Continuous beds. Their applicability for immobilization of proteins
Authors: Mohammad Jamil , Hjertén Stellan 
Published: May 2005

AbstractAn epoxy‐activated continuous bed can be prepared for immobilization of Proteins in a simple, rapid, and cost‐effective way. The concentration of epoxy groups on the continuous bed was as high as 600 μmol/mL compressed bed (compression of the bed decreases the peak broadening). Human transferrin, human serum albumin and particularly urease were employed as model proteins. The immobilization of urease was virtually completed within 1h in 1 M potassium phosphate, pH 7.4. The binding capacity was 97 mg of urease/mL compressed bed. This bed is of clinical interest, since it is inexpensive to prepare and permits reproducible enzymatic determination of urea in serum and urine (the chromatographic step is finished within 1–2 min).