bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of urinary cystine and cysteinyl‐penicillamine in patients with cystinuria
Authors: Sampson D. C. , Stewart P. M. , Hammond J. W. 
Published: May 2005

AbstractA high‐performance liquid chromatographic method with electrochemical detection (LC/EC) was developed to measure cystine and cysteinyl‐penicillamine disulfide in the urine of patients screened or treated for cystinuria. Urine was acidified, centrifuged to remove urinary protein, diluted and injected. The disulfides were separated on a reversed‐phase column, reduced at the upstream electrode of a dual electrochemical detector with gold–mercury amalgam (Au/Hg) electrodes and the resultant thiols measured at the downstream electrode. The sample preparation is simple, the analysis rapid, specimens can be easily batched and the specificity of the method is better than those of two other separative procedures with which it was compared. The coefficient of variation for cystine in cystinuric urine is 6.7%, 5.5% and 3.2% for levels of 0.09, 0.52 and 1.02 mmol/l respectively, and for cysteinyl‐penicillamine disulfide 2.6% and 7.5% for levels of 0.45 and 0.98 mmol/l respectively. Urine for analysis of these disulfides should not be collected within 24 hours of administration of the radiopaque agent diatrizoate but no other interference to the assay has been noted. This method is suitable as a screen for cystinuria in patients with renal tract calculi, for ongoing monitoring of cystinuric patients and to check patient compliance with d‐penicillamine therapy.
Column separation using Bio‐Gel P100 for the characterization of the products of human lung elastin degradation by leucocyte elastase and cathepsin G
Authors: Smyrlaki Marie , Davril Monique , Hayem Annette 
Published: May 2005

AbstractThe solubilization of human lung elastin by leucocyte elastase and cathepsin G is described. Elastolysis kinetic studies clearly show that leucocyte elastase is more efficient in solubilizing elastin fibres than is cathepsin G. Cathepsin G can degrade elastin but at a much slower rate.Characterization of elastase and cathepsin G soluble elastin fragments, obtained after 24 h of digestion (enzyme‐substrate ratio, 1:100), was first performed by isoelectric focusing. Whole digests were focused as 6 bands in a pH range 4.2 to 4.7 and were found to have no significant differences in amino acid compositions.Biogel P‐100 gel filtration of the elastase digested fragments separated a major excluded fraction (Mr's: 80 000 to 30 000) and a small retained one (Mr's: 6000 to 4000). Conversely, cathepsin G digests were eluted as a minor excluded fraction and a more important retarded one (Mr's: 6000 to 4000). Only the high molecular weight fractions of both enzymes digests contain crosslinked amino acids; this assigns a role for desmosines in the resistance of elastin to these proteases. These results are discussed in comparison with the data obtained by others.
An automated direct‐injection HPLC‐method for the electrochemical/fluorimetric quantitation of monoamines and related compounds optimized for the screening of large numbers of animals
Authors: Seyfried C. A. , Adam G. , Greve T. 
Published: May 2005

AbstractAn automated, highly stable HPLC system is described allowing the quantitation of monoamines and related compounds with virtually online data processing and statistical evaluation of the mean values of various differently treated groups of animals. The system is highly suited to the screening of drugs involving large numbers of samples. To ensure long‐term, uninterrupted performance, two robust chromatographic systems were developed optimized to separate neighboring peaks as widely as possible. This was achieved by using mobile phases of relatively low pH to retard acidic compounds, and optimal concentrations of the ion‐pairing reagent to manipulate the retention times of amines on the RP‐18 column, resulting also in clearcut separations from the solvent/tissue peak. Direct injection of deproteinized tissue samples, requiring no clean up procedures is used. One faster system allows measurement of the main biogenic amines, metabolites and TRP, whereas another system allows the simultaneous quantitation of DOPA, 5HTP, NA, MOPEG, NMN, A, MN, VMA, DA, 3MT, OOP AC, HVA, 5HT, 5HIAA and TYR. By pretreatment of animals with a decarboxylase inhibitor the latter system offers the possibility of detecting drug effects in the same animal on either dopamine and serotonin turnover or noradrenaline and serotonin turnover, depending on the brain area chosen. The system described has been running for over a year without major disturbance and with minimal technician attendance.
Direct determination of vanillylmandelic acid in human urine by reversed‐phase HPLC
Authors: Shang Zhen‐Hua , Fang Shu‐Hua , Wang Jun‐De , Zhou Liang‐Mo , Ju Chang‐De 
Published: May 2005

AbstractA reversed‐phase HPLC method for the determination of epinephrine, norepinephrine, dopamine, and vanillylmandelic acid (VMA) has been developed. The concentration of VMA in the urine of hypertensive patients was measured by direct injection after centrifugation. The method is useful for the diagnosis of pheochromocytoma.
Determination of artemether in plasma and whole blood using HPLC with flow‐through polarographic detection
Authors: Huang Yuexian , Xie Guanghua , Zhou Zhongming , Sun Xiaomiao , Wang Yanli 
Published: May 2005

AbstractAn HPLC method with polarographic detection for the trace determination of artemether in plasma and whole blood was developed and applied to pharmacokinetic and clinical pharmacological studies. The method showed high sensitivity and selectivity because of the easy reduction of the peroxide linkage of artemether at the mercury drop electrode. The detection limit was 10 ng and the detector response was linear over the range of 10 ng to 1 μg artemether injected onto the column. The largest relative standard deviation of 10 replicate measurements of standard solutions (concentrations of 10 ng/mL–1 μg/mL) was 8%. The recovery from whole blood and plasma of added drug (concentrations of 15–48 ng/mL) was 71–100%.
Routine clinical determination of carotene, vitamin E, vitamin A, 25‐hydroxy vitamin D3 and trans‐vitamin K1 in human serum by straight phase HPLC
Authors: Van Haard Paul M. M. , Engel Roel , Postma Tjeerd 
Published: May 2005

AbstractA universal extraction procedure is described for fat‐soluble vitamins in human serum. Methods are presented for routine quantitative analysis by isocratic straight phase HPLC with UV‐detection of (α + β)‐carotene, vitamin E. (α‐tocopherol) and vitamin A (all‐trans‐retinol) in one single run, and of vitamin K1 (trans‐phylloquinone) and 25‐hydroxy vitamin D3 after sample clean‐up using disposable reversed‐phase cartridges. The limits of detection, precisions and selectivities of the developed assays are shown to be satisfactory after more than three years' experience. The routine clinical determination of fat‐soluble vitamins can be performed in less than 5 mL of serum. Analyses of external quality control and randomly taken outpatient samples are shown to be of great value in assessing laboratory performance.
Simple and rapid GLC method for the determination of orphenadrine in human plasma
Authors: Contin Manuela , Riva Roberto , Albani Fiorenzo , Baruzzi Agostino 
Published: May 2005

AbstractA rapid and specific method has been developed for the determination of orphenadrine concentration in plasma. It involves a one‐step sample preparation using n‐hexane/isopropyl alcohol (98:2) extraction, and analysis by gas chromatography on a wide bore capillary column using nitrogen/phosphorus detection. This procedure considerably simplifies previously reported assays and is specific and sensitive enough for the determination of orphenadrine in plasma of patients on chronic therapy.
HPLC determination of cis‐diamminedichloroplatinum(II) in plasma and urine with UV detection and column‐switching
Authors: Kizu Ryoichi , Hayakawa Kazuichi , Miyazaki Motoichi 
Published: May 2005

AbstractA method for determining cis‐diamminedichloroplatinum(II) (CDDP), an anticancer drug, in plasma and urine by HPLC with UV detection and column‐switching has been developed. Typical conditions were as follows. An apparatus was composed of two columns, two pumps, a UV detector, a sample injector with a 100 μL loop, a switching valve, a column oven and a recorder. A Rheodyne model 7125 sample injector was used as the switching valve. A precolumn (4.6 mm ID × 25 cm) was packed with MCI GEL CK10S (a strong cation exchanger), and an analytical column (4.6 mm ID × 5 cm) was packed with MCI GEL CDR10 (a strong anion exchanger). Both columns were connected in series via the switching valve. The CDDP‐containing fraction of the effluent from the precolumn was loaded to the analytical column by column‐switching and the effluent from the analytical column was monitored at 210 nm. An eluent of 0.3 M sodium dihydrogen phosphate was pumped at a flow rate of 1 mL/min and the columns were maintained at 40°C. CDDP was eluted at about 11 min and the identity of the peak of CDDP on the chromatogram was confirmed by its 3‐dimensional chromatogram and analysis of platinum in the column effluent. Under the conditions described above, a linear relationship was obtained between peak height and concentration of CDDP up to 100 μM. Correlation efficients were 0.998 for plasma and 0.999 for urine. The detection limit was 0.1 μM for CDDP in both plasma and urine (S/N = 3, 0.005 AUFS). The reproducibility was within 3% for 10 determinations. The CDDP concentrations in plasma and urine of a patient with ovarian carcinoma receiving CDDP treatment could be determined.
A simple method for the characterization of photoproducts from DNA applied to the cis‐syn thymine dimer
Authors: Salter L. F. , Thomas R. C. 
Published: May 2005

AbstractA method for the unambiguous characterization of DNA photoproducts has been developed. It does not require radio‐labelled DNA, or specialized techniques. In the preliminary step, UV‐irradiated DNA is hydrolysed to its constituent bases and photoproducts. The photoproducts are then separated from nucleic acid bases using low pressure ion‐exchange chromatography on a Dowex 1 × 8 200–400, and an Amberlite CG–50–H+ column. Further separation and purification of photoproducts is carried out on the HPLC Whatman Partisil ODS2 column, using 15% MeOH. The procedure is simple, reproducible and versatile.
A rapid and specific HPLC‐electrochemical method for the determination of endogenous 5‐methyltetrahydrofolic acid in plasma using solid phase sample preparation with internal standardization
Authors: Lucock M. D. , Hartley R. , Smithells R. W. 
Published: May 2005

AbstractA rapid and specific HPLC‐electrochemical method for determining endogenous 5‐methyltetrahydrofolic acid (5MeTHF) in plasma is described. Quantitative solid phase extraction of 5MeTHF and internal standard, β‐hydroxyethyltheophylline, was carried out using proprietary phenyl bonded‐silica columns (Bond Elut Phenyl cartridges, 1.0 mL capacity). Chromatographic separation was achieved using a mobile phase consisting of 15% (v/v) methanol in 0.05 M KH2PO4, pH 3.5 at a flow rate of 2.0 mL/min in conjunction with a Waters Assoc. radially compressed Nova‐Pak phenyl column (10 cm × 8 mm, 4 μm bonded silica). The internal standard was measured by UV detection at 254 nm. A Bioanalytical Systems Inc. LC‐17 glassy carbon oxidative flow cell with a potential held at +0.35 V vs Ag/AgCl using the LC‐4A amperometric controller allowed levels of 1–2 ng/mL 5MeTHF to be measured in 500 μL of plasma. Daily appraisal of the ratio produced by authentic materials clearly demonstrated that quantitation using dual detection was not subject to problems of differential response. Inter‐day variation of the differential detector response is cited. Comparison of the Lactobacillus casei bioassay with HPLC demonstrates good agreement between methods but at the same time highlights the drawback of using such non‐specific methods to measure samples where more than one folylmonoglutamate may be present. Antoxidant free storage for three months at −70± C in darkness resulted in no deterioration of 5MeTHF. A comparison of the means and range of values for plasma folate obtained using HPLC, L. casei bioassay and the radiometric binding assay is reported.
HPLC method for simultaneous determination of clobazam and N‐desmethylclobazam in human serum, rat serum and rat brain homogenates
Authors: Gaźik Wieslaw R. , Podleśany Jerzy , Filipek Marian 
Published: May 2005

AbstractA method for simultaneous determination of clobazam (CBZ) and its active metabolite N‐desmethylclobazam (DCBZ) in various biological samples by RP‐HPLC with UV detection is described. The determination of both CBZ and DCBZ is performed without derivatization. The internal standard is diazepam. The method is rapid and simple with sensitivity limits of 10 ng/mL for both CBZ and DCBZ and is suitable for routine analysis as well as for animal studies.
Electronic interaction chromatography on porous graphitic carbon. Separation of [99mtc]pertechnetate and perrhenate anions
Authors: Lim C. K. 
Published: May 2005

AbstractThe oxo anions of technetium‐99m and rhenium, pertechnetate (TcO) and perrhenate (ReO), have been separated by high performance liquid chromatography on porous graphitic carbon with aqueous trifluoroacetic acid or salt solutions as eluent. Chromatographic retention was a result of electronic interaction between the lone pair electrons of the anions and the delocalised ±‐electron clouds of the porous graphitic carbon. Retention and resolution can be controlled by the concentration and/or species of eluents which can compete with the solutes for electronic interaction being used for elution.
Direct determination of unconjugated HVA in human plasma filtrates by HPLC coupled with dual‐electrode coulometric electrochemical detection
Authors: Gerhardt Greg A. , Drebing Carla J. , Stephen Christopher , Freedman Robert 
Published: May 2005

AbstractWe report a procedure for the rapid determination of unconjugated homovanillic acid (HVA) in human plasma by cartridge filtration followed by direct injection into an isocratic HPLC system coupled with dual‐electrode coulometric electrochemical detection. Sample preparation is rapid and more than 72 samples can be studied in 24 h using an automated HPLC system. The intra‐ and interassay precisions of the assay equal or exceed previously reported methods. While this methodology has been employed to study plasma free HVA, the concept of the technique may be applicable to other compounds, as well as different assay procedures, to greatly decrease sample preparation time.
Chromatography as a reference technique for the determination of clinically important steroids
Authors: Robards K. , Towers P. 
Published: May 2005

AbstractChromatographic methods (paper chromatography, thin layer chromatography, high performance liquid chromatography, gas chromatography and gas chromatography‐mass spectrometry) for the determination of clinically important steroids in biological specimens are reviewed. The emphasis is on the use of gas chromatography, gas chromatography‐mass spectrometry and high performance liquid chromatography as reference rather than routine techniques. Chromatographic methods are compared with colorimetric, fluorimetric and radioimmunoassay procedures in terms of simplicity of operation, cost and ability to analyse large numbers of specimens. The importance of correct specimen collection and storage are discussed. Sample preparation techniques for the various analytical methods are described. These include extraction of free and conjugated steroids from serum, plasma, urine and saliva by solvent partition, with polymer‐based resins such as Amberlite XAD‐2, DEAE‐Sephadex and Sephadex resins bonded with various other function groups and, more recently, with chemically bonded reversed‐phase silicas.
The determination of total and unbound midazolam in human plasma. A comparison of high performance liquid chromatography, gas chromatography and gas chromatography/mass spectrometry
Authors: de Vries J. X. , Rudi J. , Walter‐Sack I. , Conradi R. 
Published: May 2005

AbstractMidazolam concentrations in patients' plasma was determined after extraction with high performance liquid chromatography (HPLC), gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). GC was selected for routine plasma assays in terms of selectivity, simplicity, precision, accuracy and sensitivity (0.02 μg/ml); HPLC analysis was less sensitive (0.1 μg/mL) than GC; GC/MS was used for analysis validation. Plasma protein binding of midazolam was determined by GC in patients' plasma after in vitro incubation with midazolam, ultrafiltration and extraction; 5% of the drug was unbound to plasma proteins. Midazolam distribution in lipoprotein fractions separated by ultracentrifugation of plasma obtained from patients on prolonged midazolam treatment was also assayed by GC.
Oxalate/hydrogen peroxide chemiluminescence reaction. A 19F NMR probe of the reaction mechanism
Authors: Chokshi Hitesh P. , Barbush Michael , Carlson Robert G. , Givens Richard S. , Kuwana Ted , Schowen Richard L. 
Published: May 2005

AbstractThe mechanism of the oxalate/hydrogen peroxide chemiluminescence reaction has been examined by magnetic resonance techniques. Investigation of the reactive intermediates involved in chemiluminescence was carried out with bis(2,6‐difluorophenyl)oxalate (DFPO) using 19F NMR to probe its reactions with aqueous hydrogen peroxide. Formation and reactions of the intermediate hydroperoxy oxalate ester B along with the formation of the half ester product C and difluorophenol D were monitored by 19F NMR. When the reaction of DFPO and aqueous hydrogen peroxide was carried out in the presence of dansylphenylalanine, a typical fluorescent analyte, the intensity of the resonance due to the intermediate B was diminished in direct proportion to the concentration of the analyte. Comparison of the time/intensity profile of the chemiluminescence emission with that of the 19F NMR transient suggests that the hydroperoxy oxalate ester B is the likely ‘reactive’ intermediate, capable of participating in a chemically initiated electron exchange luminescence mechanism.
High performance liquid chromatographic measurement of bisoprolol in plasma
Authors: Eastwood R. J. , Jerman J. C. , Bhamra R. K. , Holt D. W. 
Published: May 2005

AbstractA simple high performance liquid chromatographic method has been devised for the measurement of bisoprolol in plasma or serum. The sample (200 μL) is vortex mixed for 30 s with 2 M Tris solution (50 μL), aqueous internal standard (benzimidazole, 2.0 mg/L, 50 μL) and methyl t‐butyl ether (200 μL). After centrifugation (9950 × g, 2 min), a portion of the resulting extract is analysed on a microparticulate (5 μm) silica column using 1 mM camphorsulphonic acid in methanol as the mobile phase. Detection is by fluorescence at an excitatioh wavelength of 215 nM. The lower limit of accurate measurement for the assay is 10 μ/L (CV% = 8.9, n = 9) with a lower limit of detection of 5 μg/L. There is minimal interference from either commonly prescribed drugs or endogenous compounds.
Separation of glycoprotein‐N‐glycans by high‐pH anion‐exchange chromatography
Authors: Pfeiffer Günter , Geyer Hildegard , Geyer Rudolf , Kalsner Inge , Wendorf Petra 
Published: May 2005

AbstractA series of high‐mannose and complex type glycoprotein‐N‐glycans was subjected to high‐pH anion‐exchange chromatography. The results revealed that this method represents a useful tool for analytical characterization of single oligosaccharides as well as preparative separation of complex mixtures of carbohydrate side‐chains. On the other hand, it became evident that in several cases a combination of different chromatographic techniques is required for efficient separation of individual oligosaccharide species.
Microsomal Δ9, Δ6 and Δ5 desaturase activities and liver membrane fatty acid profiles in alcohol‐fed rats
Authors: Venkatesan S. , Rideout J. M. , Simpson K. J. 
Published: May 2005

AbstractIn experimentally produced alcoholic fatty liver microsomal fatty acid composition was measured using gas chromatography. The results showed an increase in linoleic acid (18:2, n‐6) and hexadecaenoic acid (22:6, n‐3) and a decrease in arachidonic acid (20:4, n‐6) in alcohol‐fed rats. Using high performance liquid chromatographic separation of radiolabelled substrate and products, Δ9, Δ6 and Δ5 desaturase enzymes were assayed. The activity of Δ9 and Δ5 desaturase was decreased in alcohol‐fed rats and Δ6 desaturase activity was similar in control and alcohol‐fed groups. These results indicated there was no causal relationship between desaturase activity and membrane fatty acid changes. Increased amounts of eicosatrienoic acid (20:3, n‐9) in rats fed <5% fat were observed in both control and alcohol‐fed rats. The results indicated that essential fatty acid deficiency was not due to alcohol consumption.
A new high performance liquid chromatographic method for the simultaneous measurement of S‐adenosylmethionine and S‐adenosylhomocysteine concentrations in pig tissues after inactivation of methionine synthase by nitrous oxide
Authors: Molloy Anne M. , Weir Donald G. , Kennedy Glenn , Kennedy Seamus , Scott John M. 
Published: May 2005

AbstractA rapid gradient method has been established to measure simultaneously the tissue levels of S‐adenosylmethionine (AdoMet) and S‐adenosylhomocysteine (AdoHcy). The method involves application of a 15%–25% linear gradient of methanol over a period of 10 min to an initial mobile phase of 15% methanol with 25 mM sodium phosphate, 10 mM 1‐heptanesulfonic acid solution at pH 3.2 and a flow rate of 1 mL/min. AdoHcy elutes at 9.5 min and AdoMet at 12.6 min. The assay has a detection limit of 10 pmol and is linear in the concentration range 30–800 pmol. The method was used to assess changes in AdoMet and AdoHcy concentrations of pig tissues after seven days exposure to the anaesthetic gas nitrous oxide which irreversibly inactivates methionine synthase and induces an inability to recycle homocysteine, particularly in neural tissues. The treatment caused significant alterations in cellular AdoMet: AdoHcy ratios which were principally due to a dramatic rise in AdoHcy concentrations.
Identification of peroxyacetic acid uroporphyrin I in the urine of patients with congenital erythropoietic porphyria by liquid chromatography and mass spectrometry
Authors: Guo Rong , Rideout J. M. , Chai W. , Lawson A. M. , Lim C. K. 
Published: May 2005

AbstractA new porphyrin, peroxyacetic acid uroporphyrin I, has been isolated from the urine of patients with congenital erythropoietic porphyria by reversed phase high performance liquid chromatography. The porphyrin was characterized by high resolution mass spectrometry and by typical chemical reactions of a peroxyacid.