bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metabolic profiling of opioid peptides in canine pituitary and selected brain regions using HPLC with a radioreceptor assay detector
Authors: Takeshita Hisayoshi , Desiderio Dominic M. , Fridland Genevieve 
Published: May 2005

AbstractA combination of gradient reversed‐phase high performance liquid chromatography (RP/HPLC) with a radioreceptor assay detector that uses two ligands is used to obtain effectively the metabolic profile of endogenous receptoractive opioid peptides in the canine pituitary and in seven selected brain regions including the hypothalamus, caudate nucleus, mid‐brain, amygdala, thalamus, pons‐medulla, and the hippocampus. Gradient RP/HPLC separates a mixture of endogenous peptides over a wide range of hydrophobicities. A novel opioid preparation from canine limbic system synaptosomes is utilized in a radioreceptorassay screen; tritiated etorphine (ET) or D‐2ala, D‐5leu‐leucine enkephalin (DADL) is used as the competitively displaced ligand. This receptor‐rich preparation contains several receptor types, and thus serves well as a screen with the required low level of specificity. Subsequent analysis with other detectors of high specificity (MS, RIA) will follow this screen in other studies. Etorphine interacts with several of the opioid peptide‐preferring receptors, whereas DADL is more specific towards the delta receptor that preferentially binds the smaller pentapeptides of the enkephalin family. The highest amount of peptide receptor activity found in this study is in the pituitary tissue, a smaller amount in the hypothalamus and caudate nucleus, and still lower amounts in the other five brain tissue extracts. This variation in peptide concentration most probably reflects three separate factors that operate in this biologic system: differential tissue‐specific processing patterns of the large peptide precursors; distribution of the three opioid peptide systems; and the receptor preparation and the radioligand used in the assay. The structures of the receptoractive compounds in each RP/HPLC peak await mass spectrometric confirmation.
Improved TLC systems for rapid resolution of phenyl thiohydantoin amino acids
Authors: Bhushan R. , Mahesh V. K. , Mallikharjun P. V. 
Published: May 2005

AbstractTwo new solvent systems, n‐hexane + propionic acid (26:5, v/v) and chloroform + acetone (29:3, v/v), for the rapid resolution and identification of an 18‐component mixture of phenylthiohydantoin amino acids are reported. Using these systems certain difficult combinations of phenylthiohydantoin amino acids are resolved. Two more solvent systems, viz chloroform+acetic acid (27:3, v/v) and chloroform + methanol (30:4, v/v), are developed to resolve phenylthiodantoin derivatives of aspartic and glutamic acids.
Determination of bile acids and their conjugates in serum by HPLC using immobilized 3α‐hydroxysteroid dehydrogenase for detection
Authors: Campbell G. R. , Odling‐Smee G. W. , Rowlands B. J. , Irvine G. B. 
Published: May 2005

AbstractA method is described for the separation of unconjugated bile acids and their glycine and taurine conjugates in a single step with adequate sensitivity for analysis of serum samples. Separation was carried out over a period of 80 min using a linear gradient with increasing concentrations of methanol in aqueous ammonium dihydrogen phosphate buffer, on an ODS Spherisorb column. Spectrofluorometric detection of NADH, formed as the column eluate passed through a column of immobilized 3α‐hydroxysteroid dehydrogenase, enabled amounts less than 40 pmol to be quantified. The reaction was carried out at neutral pH so that the lifetime of the enzyme column was increased, compared to other methods where a pH nearer 9.0 is commonly used. Flow rates were optimized to give comparable peak area for both primary and secondary bile acids.
Determination of urinary 5‐hydroxy‐3‐indoleacetic acid by an automated HPLC method
Authors: Koel Marlies , Nebinger Peter 
Published: May 2005

AbstractA HPLC method for the quantitative determination of 5‐hydroxy‐3‐indoleacetic acid (5‐HIAA) in urine is described. The method is based on ion‐pair chromatography, reversed phase (RP) column material and specific fluorimetric detection at 300 nm and 355 nm. Sample preparation and gradient elution were avoided by using a column‐switching technique. The sensitivity of the assay was excellent for clinical routine analysis, with a detection limit of 0.2 mg/L 5‐HIAA. No endogenous or exogenous interference problems arose. Intra‐ and interassay precision was good, with observed coefficients of variation of 1.5 to 2.6% and 2.1%, respectively. Recoveries were 93 to 98%. The system described can be used for clinical diagnosis and therapy follow‐up of carcinoid tumors. It has been running for over a year without disturbances and with a minimum of technical attendance.
Determination of estriol and creatinine in urine by high performance liquid chromatography
Authors: Ke Li , Yisheng Yuan 
Published: May 2005

AbstractA quantitative method for the determination of estriol (E3) and creatinine (C) in random urine by high performance liquid chromatography is described. The mobile phase was a mixed solution of methanol and phosphate buffer (0.025 M, pH 6.5) and the detection wavelength was at 205 nm. The method was simple, rapid and accurate. The OCV for E3 and C using this method were 1.7 – 3.4% and 2.2 – 2.5%, respectively. The RCV for E3 and C were 6.2 – 7.0% and 4.5 – 6.9%, respectively. The recoveries were 87 – 104% for E3 and 98 – 103% for C, respectively. The method has been used for clinical determinations.
Quinidine oxidative metabolism. Identification and biosynthesis of quinidine 10,11‐dihydrodiol stereoisomers
Authors: Leroyer R. , Varoquaux O. , Advenier C. , Pays M. 
Published: May 2005

AbstractThe isocratic reversed phase high performance liquid chromatographic method proposed for quinidine metabolic studies facilitates particularly the separation of 10(R) and (S) isomers of quinidine 10,11‐dihydrodiols. The finding of each of these forms following a new synthetic pathway allows us to identify and quantify them in biological fluids. These two isomers have especially been observed in rat bile and hepatocyte secretions. The metabolic inducing effect of phenobarbital on the oxidative metabolism of quinidine is verified in rat isolated hepatocytes. Simultaneous secretion of the two dihydrodiols is also verified in human urine by a gas chromatography/mass spectrometry procedure.
Qualitative and quantitative high performance liquid chromatographic analysis of monoamine neurotransmitters and metabolites in cerebrospinal fluid and brain tissue using reductive electrochemical detection
Authors: Schmidt Dennis , Roznoski Molly , Ebert Michael H. 
Published: May 2005

AbstractThe application of reductive coulometric electrochemical detection for analysis of the monoamine neurotransmitters norepinephrine, dopamine, and serotonin and their common metabolites in brain and cerebrospinal fluid following separation by isocratic high performance liquid chromatography is described. The high sensitivity and screening capabilities of coulometric electrodes permits the accurate quantitation of as little as 3–5 pg of these compounds in tissue following a simple single step purification procedure. Moreover, comparison of peak height ratios obtained from analysis of authentic reference standards and tissue samples at selected multiple electrode potentials provides a straightforward means for qualitative evaluation of peak identification and purity during analysis of biological samples. The method is comparatively inexpensive and precise within and between day coefficients of variation for most compounds range from 2–5%. Thirty samples can be run in duplicate in a 24 h period.
Isocratic high performance liquid chromatographic analysis of S‐adenosylmethionine and S‐adenosy ihomocysteine in animal tissues: the effect of exposure to nitrous oxide
Authors: Bottiglieri Teodoro 
Published: May 2005

AbstractA simple isocratic high performance liquid chromatographic method for the simultaneous measurement of S‐adenosylmethionine (SAM) and S‐adenosylhomocysteine (SAH) in animal tissues is described. The direct injection of perchloric acid tissue extracts and rapid resolution of both compounds in a single run reduces any sampling and analytical errors in determining the SAM/SAH ratio, a measure of methylation reactions. The method has been used to determine changes in brain SAM/SAH ratios after exposure of rats to nitrous oxide.
Simultaneous determination of gemfibrozil and its metabolites in plasma and urine by a fully automated high performance liquid chromatographic system
Authors: Nakagawa Akihiko , Shigeta Akemi , Iwabuchi Haruo , Horiguchi Masaaki , Nakamura Kan‐ichi , Takahagi Hidekuni 
Published: May 2005

AbstractSensitive and specific methods for the simultaneous determination of gemfibrozil (Lopid®), a lipid‐lowering agent, and its metabolites in plasma and urine are described. The methods are based on a fully automated high performance liquid chromatographic (HPLC) system with fluorescence detection. Urine samples, diluted with acetonitrile, were directly analysed by HPLC using a flow and eluent programming method. In the case of plasma, gemfibrozil and its main metabolites were extracted from acidified samples and the resulting extracts injected into the chromatographic system. The sensitivity was approximately 100 ng/mL for gemfibrozil and its four metabolites using 0.5 mL plasma or urine. An acyl glucuronide of gemfibrozil excreted in human urine after oral administration of the drug was isolated and its structure and stability examined.
High performance liquid chromatography with chemiluminescence detection of methamphetamine and its related compounds using 4‐(N,N‐dimethylaminosulphonyl)‐7‐fluoro‐2,1,3‐benzoxadiazole
Authors: Nakashima Kenichiro , Suetsugu Keiko , Yoshida Kazunori , Akiyama Shuzo , Uzu Sonoko , Imai Kazuhiro 
Published: May 2005

AbstractA high performance liquid chromatographic assay of methamphetamine (MP) and its related compounds, i.e. ephedrine (EP), norephedrine (NE), p‐hydroxymethamphetamine (p‐HMP), p‐hydroxyamphetamine (p‐HAP) and amphetamine (AP), with peroxyoxalate chemiluminescence detection has been developed. 4‐(N,N‐Dimethylaminosulphonyl)‐7‐fluoro‐2,1,3‐benzoxadiazole (DBD‐F) was used as a fluorescent labelling reagent. A mixture of hydrogen peroxide and bis[4‐nitro‐2(3,6,9‐trioxadecyloxycarbonyl)phenyl] oxalate in acetonitrile was used as a postcolumn chemiluminogenic reagent. DBD derivatives of MP and its related compounds were separated by a gradient elution with acetonitrile and 0.01 M imidazole buffer (pH 7.0) within 65 min. The detection limits (S/N = 3) for the proposed method for MP, AP, EP, NE, p‐HMP and p‐HAP were 27, 100, 40, 133, 25 and 133 fmol on column, respectively. The recoveries of these compounds with normal urine samples were 87.4–106.4%. The method was successfully applied to the assay of MP and its metabolites in urine samples from MP addicts. A good linear correlation for the resulted amounts of MP or AP between the proposed method and gas chromatography was obtained (r = 0.993 for MP or 0.991 for AP).
Simple determination of hydrochlorothiazide in human plasma and urine by high performance liquid chromatography
Authors: de Vries J. X. , Voss A. 
Published: May 2005

AbstractThe diuretic drug hydrochlorothiazide (HCT) is used mainly for treatment of mild to moderate hypertension and is usually administered with other drugs. An assay for the determination of HCT in human plasma and urine by high performance liquid chromatography (HPLC) has been developed. Samples were purified by solvent extraction and analysed by reversed phase HPLC with ultraviolet detection, using hydroflumethiazide as the internal standard; plasma was eluted using gradient elution and urine was analysed isocratically. The method is simple to perform, is sensitive (detection limit 0.01 μg/mL in plasma and 0.2 μg/mL for urine); it showed good reproducibility (3–8%). A great number of drugs did not interfere with the assay and the method was used for pharmacokinetic studies in healthy subjects, but samples from patients can also be analysed with high selectivity.
Study of chemobiological reactions. 1. Selectivity of aromatic amino compounds and saccharides in glycosylation reactions
Authors: Kinoshita Toshio , Miyayama Miyoko , Kyodo Yukiko , Kamitani Yoshie , Miyamasu Misato , Nimura Noriyuki , Hanai Toshihiko 
Published: May 2005

AbstractThe reactivities between saccharides and primary amino compounds were studied by liquid chromatography on an amino‐bonded column and by measurement of the reaction rates of aromatic amines with saccharides. The recoveries from the column and the reaction rates were correlated with their physicochemical properties calculated by the CACheTM program. The reactivities between amines and saccharides correlated well with their hydrogen bonding energies calculated by molecular mechanics.
Simultaneous determination of NK611, a novel water‐soluble derivative of etoposide, and its metabolite (DeNK611) in dog plasma by column‐switching high performance liquid chromatography
Authors: Machida Megumi , Tanaka Shigeo , Nakamori Kota 
Published: May 2005

AbstractA simple, selective, reversed phase liquid chromatographic method using a column‐switching technique has been developed for the simultaneous determination of a novel derivative of etoposide (NK611) and its O‐demethyl metabolite in dog plasma. A good linear response was obtained for both drugs in the range 0.1‐12.0 μg/mL. The mean recoveries were within 100±5%. The within‐ and between‐day precisions were within 3.5% and 4.6%, respectively. This method was used in a pharmacokinetic study following intravenous and oral administration of NK611 to beagle dogs.
Thin‐layer chromatographic determination of brain catecholamines and 5‐hydroxytryptamine
Authors: Alemany G. , Nicolau M. C. , Gamundí A. , Rial R. 
Published: May 2005

AbstractA simple and sensitive (up to nanogram level) method to determine norepinephrine, serotonine and dopamine in rat brain is described. The amines are acetyled and the derivatives are resolved by thin layer chromatography (TLC) on silica high performance thin layer chromatography (HPLC) plates. Quantification is achieved by fluorescence densitometry at 415 nm excitation wavelength.
Direct enantioselective separation of bevantolol by high‐performance liquid chromatography on normal and reverse cellulose chiral stationary phases
Authors: Aboul‐Enein Hassan Y. , Serignese Vince 
Published: May 2005

AbstractA direct, isocratic and simple chromatographic method is described for the enantiomeric separation of bevantolol (BEV) using normal and reverse cellulose tris (3,5‐dimethylphenylcarbamate) chiral stationary phases (CSPs) known as Chiralcel OD and Chiralcel OD‐R, respectively. The effect of various alcohols present in the mobile phase on the separation factor (α) and resolution factor (Rs) has been studied.The method has been used to determine and identify the BEV enantiomers in human urine after oral administration of racemic BEV. The chiral recognition mechanism(s) between the analyte and these chiral stationary phases is proposed.
High performance liquid chromatographic determination of methacrylate in blood serum
Authors: Bereznowski Zdzislaw , Marlewski Maciej , Smolenski Ryszard T. 
Published: May 2005

AbstractMethacrylic acid is a hydrolytic breakdown product of methylmethacrylate which is widely used in orthopaedic surgery, dentistry and in the chemical industry for fabrication of acrylic resins. Information on the toxicity of methacrylic acid and its metabolism is limited. To facilitate studies in this field we developed a liquid chromatographic procedure allowing determination of methacrylate in blood serum. The procedure was based on reversed‐phase HPLC using a gradient elution with UV detection at 210 or 240 nm. The method was linear up to 5 mM concentration with a detection limit of 0.5 μM. The procedure was applied to determination of methacrylate in rat blood serum after administration of sodium methacrylate solution into the stomach. A peak of this compound was demonstrated in the chromatogram 10 min after administration which disappeared after 60 min, confirming suitability of the method for biological applications.
Studies on standardization of folium strobilanthis, radix strobilanthis and their preparations
Authors: Ling Li , Tong‐Yi Dong , Xiu‐Lu Li , Chuan‐Zhuo Qiao 
Published: May 2005

AbstractDetermination of 4(3H)‐quinazolinone, a newly found antiviral and immunopatentiating constituent was proposed as a method of evaluating the quality of two antiviral Chinese herbal drugs Daqingye (Folium Strobilanthis) and Banlangen(Radix Strobilanthis) and their preparations (‘Antipyretic and common cold granules’, ‘Banlangen granules’). An HPLC method for determining the content of 4(3H)‐quinazolinone was established with satisfactory results. The method showed good linearity (r = 0.9998, n = 5) in the range of 0.25–50 μg/mL of 4(3H)‐quinazolinone, the average recovery was above 99% with RSD < 0.78% (n = 3).
Immunoaffinity capillary electrophoretic analysis of cyclosporin in tears
Authors: Phillips Terry M. , Chmielinska Joanna J. 
Published: May 2005

AbstractAn immunoaffinity capillary electrophoresis technique has been developed for the analysis of cyclosporin A in human tear fluid following topical application of the drug. The technique combines the selectivity of immunoaffinity separation with the high‐resolution of capillary electrophoresis by immobilizing monoclonal antibody fragments directly onto the internal surface of the capillary. This technique was used to measure cyclosporin levels in tears obtained from corneal transplant patients during normal and drug toxicity episodes in the course of their treatment. Comparison of this technique with HPLC detection of cyclosporin in tears showed a good correlation, with the immunoaffinity CE technique having the advantage of being able to simultaneously detect toxic metabolites of cyclosporin in the same sample.
Direct determination of free phenylacetic acid in human plasma and urine by column‐switching high performance liquid chromatography with flurescence detection
Authors: Iwata Tetsuharu , Ishimaru Takayuki , Nakamura Masaru , Yamaguchi Masatoshi 
Published: May 2005

AbstractA simple and highly sensitive column‐switching high performance liquid chromatographyic method with fluorescence detection for the determination of free phenylacetic acid (PAA) in human plasma and urine is described. The method is based on the direct derivatization of plasma and urine PAA with 6,7‐dimethoxy‐1‐methyl‐2(1H)‐quinoxalinone‐3‐propionylcarboxylic acid hydrazide (DMEQ‐hydrazide). The derivatization reaction proceeds in aqueous solution in the presence of pyridine and 1‐ethyl‐3‐(3‐dimethylaminopropyl)‐carbodiimide at 37°C. The resulting DMEQ derivative of PAA is separated from endogenous interfering substances by a column‐switching chromatographic system consisting of a precolumn (YMC‐Pack C4) for sample clean‐up and an analytical column (L‐Column ODS) for the complete separation of the derivative. The derivative is detected fluorimetrically at 445 nm wih excitation at 367 nm. The detection limits (signal to noise ratio = 3) for PAA is 10 fmol in a 10 μL injection volume. The recoveries from plasma and urine are 75 and 96%, respectively. The present method is highly sensitive and simple compared to conventional liquid‐liquid extraction procedures. The sensivity allows the direct determination of free PAA in an extremely small amount (5 μL) of plasma and urine.
Determination of glutathione in biological samples by high performance liquid chromatography with fluorescence detection
Authors: Gotti Roberto , Andrisano Vincenza , Gatti Rita , Cavrini Vanni , Candeletti Sanzio 
Published: May 2005

AbstractA selective and sensitive high performance liquid chromatographic (HPLC) method has been developed for the determination of reduced glutathione (GSH) in biological samples (rat liver, spleen and plasma). The method involved a prechromatographic thiol derivatization with methyl 4‐(6‐methoxynaphthalen‐2‐yl)‐4‐oxo‐2‐butenoate; the reaction was rapid (5 min) under mild conditions (pH 7.5 and ambient temperature) and selective for the sulphydryl group. The thiol adducts were separated on a reversed‐phase C‐18 column using acetonitrile: 0.05 M triethylammonium (TEA) phosphate (pH 4) solution 32:68 (v/v) as the mobile phase. Fluorescence detection (λem = 450 nm; λexc = 310 nm) was used and the detection limit (S/N = 3) was about 0.5 pmole of the injected GSH adduct. The method was also applied to the determination of total glutathione in rat plasma after a preliminary reduction with dithiothreitol.
Direct separation of tranylcypromine enantiomers and their profile in an atypical depressive patient
Authors: Aboul‐Enein Hassan Y. , Serignese Vince 
Published: May 2005

AbstractAn isocratic and simple high‐performance liquid chromatographic method is developed for the diirect resolution of the tranylcypromine (TCP) enatiomers. The method involves the use of an S‐18‐crown‐6‐ether chiral stationary phase known as the Crownpak CR (+) column. The stereochemical separation factor (α) obtained was 1.30 and the stereochemical resolution factor (Rs) was 0.69 when using a mobile phase consisting of 0.1 N perchloric acid containing 12% methanol at 23°C. The method has been used to monitor and identify, qualitatively, the profile of enantiomers of TCP in urine of an atypical depressive patient. It was found that the (−)‐S‐TCP concentration is significantly higher than the (+)‐R‐enantiomer.
Enzyme analysis and subcellular fractionation of human peripheral blood lymphocytes with special reference to the localization of putative plasma membrane enzymes
Authors: Shah Tarulata , Webster A. D. B. , Peters Timothy J. 
Published: May 2005

AbstractHuman lymphocytes were isolated from defibrinated blood by Ficoll‐Hypaque centrifugation with erythrocyte hypotonic lysis. Homogenates of mixed lymphocytes were subjected to analytical subcellular fractionation by sucrose gradient centrifugation in a Beaufay automatic zonal rotor. The principal organelles were characterized by their marker enzymes: cytosol (lactate dehydrogenase), plasma membrane (5′‐nucleotidase), endoplasmic reticulum (neutral α‐glucosidase), mitochondria (malate dehydrogenase), lysosomes (N‐acetyl‐β‐glucosaminidase), peroxisomes (catalase). γ‐Glutamyl transferase was exclusively localized to the plasma membrane. Leucine amino‐peptidase, especially when assayed in the presence of Co2+, was also partially localized to the plasma membrane. Experiments with diazotized sulphanilic acid, a non‐permeant enzyme inhibitor, showed that these plasma membrane enzymes are present on the cell surface. No detectable alkaline phosphatase was found in the lymphocytes. Acid phosphatase and β‐glucuronidase were localized to lysosomes and there was some evidence for lysosomal heterogeneity. Leucine amino peptidase, optimal at pH 8.0, showed a partial localization to intracellular vesicles, possibly lysosomes, especially when assayed in the presence of EDTA. These studies provide a technique for determining the intracellular distribution of hitherto unassigned lymphocyte constituents and serve as a basis for investigating the cell pathology of lymphocytic disorders.
Thiols and pancreatic β‐cell function: A review
Authors: Ammon H. P. T. , Mark M. 
Published: May 2005

AbstractIn pancreatic islets insulin secretion in response to a variety of stimulators is sensitive to the redox state of extracellular and intracellular thiols. In this connection variations of plasma glutathione (GSH) may also be of importance. In the process of stimulus‐secretion coupling, membrane thiols play an important role. One major localization of critical thiols appears to be related to the influx of calcium through the voltage‐dependent channel.Other transmembranal ion movements and the cAMP system seem to be less sensitive to thiol oxidation than calcium influx via voltage‐dependent Ca channels.