bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of ceftibuten transport across Caco‐2 cells and rat jejunum mounted on modified ussing chambers
Authors: Menon R.M. , Barr W.H. 
Published: September 2003

AbstractCeftibuten uptake into Caco‐2 cells and intestinal brush border membrane vesicles is mediated by the dipeptide transport system (PEPT1). The apical to basolateral transport characteristics of ceftibuten across Caco‐2 cells and rat jejunum mounted on a modified Ussing chamber was examined. Mannitol was used as a paracellular marker along with trans‐epithelial electrical resistance (TEER) for monitoring tight junction permeability. Transport across Caco‐2 cells and rat jejunum mounted on a modified Ussing chamber was linear across the concentration range 0.25–10 mm. The net flux of mannitol and ceftibuten was higher across rat jejunum compared with Caco‐2 cells. At a donor concentration of 0.25 mm, ceftibuten transport across Caco‐2 cells was found to be pH dependent. Glycyl proline, a dipeptide, and 2,4‐ dinitrophenol, an energy poison, caused a reduction in the permeability of 0.25 mm ceftibuten across Caco‐2 cells. Benzoic acid and adipic acid also inhibited transcellular transport of ceftibuten. At a donor concentration of 0.25 mm, passive paracellular transport accounts for about 60% and the active carrier mediated mechanism accounts for about 40% of ceftibuten transport across Caco‐2 cells. None of the inhibitors however, had a significant effect on ceftibuten transport across rat jejunum mounted on a modified Ussing chamber at a donor concentration of 0.25 mm. In the concentration range 0.25–10 mm, ceftibuten is predominantly transported by paracellular mechanisms across rat jejunum and a mixture of active and passive transport across Caco‐2 cells. Copyright © 2003 John Wiley & Sons, Ltd.
Development of the second‐order derivative UV spectrophotometric method for direct determination of paracetamol in urine intended for biopharmaceutical characterisation of drug products
Authors: Parojčić Jelena , Karljiković‐Rajić Katarina , Durić Zorica , Jovanović Milica , Ibrić Svetlana 
Published: September 2003

AbstractParacetamol is a widely used nonsalicylate analgesic and antipyretic drug. The existing methods for the determination of paracetamol in biological fluids are mainly HPLC techniques, although there are some reported methods based on spectrophotometric determinations. However, all these methods involve some extraction or derivatisation procedures. In the present study the UV spectra of investigated samples were recorded over the wavelength range 220–400 nm (λ step 0.21 nm; scan speed 60 nm/min) and second‐order derivative spectra were calculated. Second‐order derivative spectra of different blank urine samples displayed the presence of a zero‐crossing point at 245–247 nm defined as λzc. The zero‐order absorption spectra of paracetamol in water displays maximum absorbance at 243 nm, while in second derivative spectra, a minimum peak at 246 nm was observed. Therefore, the application of zero‐crossing technique to the second‐derivative UV absorption spectrum should be useful for the determination of paracetamol using 2Dλzc.The proposed method enables determination of total paracetamol in urine directly and simply by reading the 2Dλzc of the diluted samples. The obtained results were in good accordance with published data on cumulative urinary excretion after per oral administration of paracetamol obtained applying different spectrophotometric methods of determination. It could be useful for biopharmaceutical characterisation of drug products (monitoring of the levels of paracetamol in urine in bioavailability testing, for the evaluation of in vitro–in vivo correlation and screening of different formulations during drug product development). Copyright © 2003 John Wiley & Sons, Ltd.
Bioequivalence evaluation of two brands of enalapril 20mg tablets (narapril and renitec) in healthy human volunteers
Authors: Najib Naji M. , Idkaidek Nasir , Adel Ayman , Admour Isra' , Astigarraga Rafel E. B. , Nucci Gliberto De , Alam S. Mahmood , Dham Ruwayda , Qumaruzaman  
Published: September 2003

AbstractThe bioequivalence of two brands of enalapril 20 mg tablets was demonstrated in 24 healthy human volunteers after a single oral dose in a randomized cross‐over study, conducted at IPRC, Amman, Jordan. Reference (Renitec, MSD, Netherlands) and test (Narapril, Julphar, UAE) products were administered to fasted male volunteers; blood samples were collected at specified time intervals, plasma separated and analysed for enalapril and its active metabolite (enalaprilat) using a validated LC‐MS/MS method at Cartesius Analytical Unit, Institute of Biomedical Sciences, USP, Sao Paulo, Brazil. The pharmacokinetic parameters AUC0−t, AUC0−∝, Cmax,Tmax,T1/2 and elimination rate constant were determined from plasma concentration‐time profile for both formulations and were compared statistically to evaluate bioequivalence between the two brands, using the statistical modules recommended by FDA. The analysis of variance (ANOVA) did not show any significant difference between the two formulations and 90% confidence intervals fell within the acceptable range for bioequivalence. Based on these statistical inferences it was concluded that the two brands exhibited comparable pharmacokinetic profiles and that Julphar's Narapril is bioequivalent to Renitec of MSD, Netherlands. Copyright © 2003 John Wiley & Sons, Ltd.
Nucleic Acid Aptamers as Tools and Drugs: Recent Developments
Authors: Rimmele Martina 
Published: September 2003

AbstractNucleic acid aptamers are molecules that bind to their ligands with high affinity and specificity. Unlike other functional nucleic acids such as antisense oligonucleotides, ribozymes, or siRNAs, aptamers almost never exert their effects on the genetic level. They manipulate their target molecules such as gene products or epitopes directly and site specifically, leaving nontargeted protein functions intact. In a similar way to antibodies, aptamers bind to many different kinds of target molecules with high specificity and can be made to order, but as a result of their different biochemical nature and size they can also be used complementary to antibodies. In some cases, aptamers might be more suitable or more specific than antibody approaches or small molecules, both as scientific and biotechnological tools and as therapeutic agents. Recent examples of characterization of aptamers as tools for scientific research to study regulatory circuits, as tools in diagnostic or biosensor development, and as therapeutic agents are discussed.
Antisense Inhibition of Escherichia coli RNase P RNA: Mechanistic Aspects
Authors: Gruegelsiepe Heike , Willkomm Dagmar K. , Goudinakis Olga , Hartmann Roland K. 
Published: September 2003

AbstractThe ribonucleoprotein enzyme RNase P catalyzes endonucleolytic 5′‐maturation of tRNA primary transcripts in all domains of life. The indispensability of RNase P for bacterial cell growth and the large differences in structure and function between bacterial and eukaryotic RNase P enzymes comply with the basic requirements for a bacterial enzyme to be suitable as a potential novel drug target. We have identified RNA oligonucleotides that start to show an inhibitory effect on bacterial RNase P RNAs of the structural type A (for example, the Escherichia coli or Klebsiella pneumoniae enzymes) at subnanomolar concentrations in our in vitro precursor tRNA (ptRNA) processing assay. These oligonucleotides are directed against the so‐called P15 loop region of RNase P RNA known to interact with the 3′‐CCA portion of ptRNA substrates. Lead probing experiments demonstrate that a complementary RNA or DNA 14‐mer fully invades the P15 loop region and thereby disrupts local structure in the catalytic core of RNase P RNA. Binding of the RNA 14‐mer is essentially irreversible because of a very low dissociation rate. The association rate of this oligonucleotide is on the order of 104 M−1 s−1 and is thus comparable to those of many other artificial antisense oligonucleotides. The remarkable inhibition efficacy is attributable to the dual effect of direct interference with substrate binding to the RNase P RNA active site and induction of misfolding of the catalytic core of RNase P RNA. Based on our findings, the P15 loop region of bacterial RNase P RNAs of the structural type A can be considered the “Achilles' heel” of the ribozyme and therefore represents a promising target for combatting multiresistant bacterial pathogens.
Heterogeneous trading agents
Authors: Neuberg Luc , Bertels Koen 
Published: September 2003

AbstractIn this article, we present a multiagent system (MAS) simulation of a financial market and investigate the requirements to obtain realistic data. The model consists of autonomous, interactive agents that buy stock on a financial market. Transaction decisions are based on a number of individual and collective elements, the former being risk aversion and a set of decision rules reflecting their anticipation of the future evolution of prices and dividends and the latter the information arriving on the market influencing the decision making process of each trader. We specifically look at this process and the following observations hold: The market behavior is determined by the information arriving at the market and agent heterogeneity is required in order to obtain the right statistical properties of the price and return time series. The observed results are not sensitive to changes in the parameter values. © 2003 Wiley Periodicals, Inc.
The effect of different components of psychological therapy on people with delusions: five experimental single cases
Authors: Jakes Simon C. , Rhodes John E. 
Published: September 2003

AbstractThis study is a contribution to the investigation of the active ingredient in psychological therapy for psychosis. Five people with chronic delusions were treated using a single‐case experiment design. The treatment was broken down into components that were administered sequentially. A baseline phase was followed by three different treatment conditions (An A–B–C–D design). The treatments were (1) Solution‐focused Therapy (2) Schema‐focused cognitive therapy (3) Cognitive therapy focused on modification of the delusion. Three of the five clients responded to treatment with a large change in degree of belief in their delusion. Two clients improved during solution‐focused therapy, one client improved during cognitive challenging of the delusion and one client changed during baseline. The implications of this study are discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Tattooing as a means of acute affect regulation
Authors: Anderson Michael , Sansone Randy A. 
Published: September 2003

AbstractIn this report, we describe the case of a 19‐year‐old male who acutely used the process of tattooing, and its associated physical pain, to regulate negative affective states. While tattooing has been described in the literature as serving individuals in a variety of ways (e.g. establishing a sense of individuality, externalizing important feelings), we are unaware of any prior case reports describing this affective function. Indeed, in this case, tattooing may have functioned more like self‐harm behaviour, and we discuss this potential implication. Copyright © 2003 John Wiley & Sons, Ltd.
Cell detection based on protein array using modified glass slides
Authors: Zhang Chun Xiu , Liu He Ping , Tang Zu Ming , He Nong Yue , Lu Zu Hong 
Published: September 2003

AbstractA protein array for cell detection was fabricated by spotting different antibodies on modified glass slides. Glass slides were modified to allow antibodies to be immobilized on it and to selectively bind antigens. Antibodies were specially selected with the cells to be detected as targets, which permitted target cells in samples to bind specifically to the array with little nonspecific binding. Results can be obtained by directly putting the samples onto the array for 1 h or a little longer to let the cells specifically interact with the antibodies. After washing the unbound samples away, images were observed with a microscope and captured with a CCD camera. The assessment of antibody‐cell binding was evaluated by capturing red blood cells (RBCs) in human blood with blood group antibodies (anti‐A and anti‐B). Blood group antibodies were spotted on the modified glass slide and kept at 4<.deg>°C overnight for immobilization. Human blood samples diluted to different concentrations were used to examine the sensitivity and specificity of the method.
Capillary electrophoresis‐ion trap mass spectrometry analysis of Ziagen® and its phosphorylated metabolites
Authors: Cai Zongwei , Fung Eliza N. , Sinhababu Achintya K. 
Published: September 2003

AbstractA capillary electrophoresis‐ion trap mass spectrometry method with a time‐segment program was developed to simultaneously analyze Ziagen® and its phosphorylated metabolites such as carbovir monophosphate, carbovir diphosphate, and carbovir triphosphate. By using the time‐segment program, the positively charged nucleoside analog and negatively charged nucleotides were separated and detected in a single electrophoretic run. The limits of detection were less than 2 μM for all of the analytes. Calibration curves of the compounds showed excellent linearity over the range of 2–100 μM. The capability of the method was demonstrated by analyzing Ziagen® and its phosphorylated metabolites that were spiked in cellular extracts of human peripheral blood mononuclear cells at 20 μM levels. Some endogenous nucleotides such as adenosine 5'‐triphosphate, adenosine 5'‐diphosphate, and adenosine 5'‐monophosphate, were also detected in the cellular extracts.
High‐speed chiral separations on a microchip with UV detection
Authors: Ludwig Martin , Kohler Frank , Belder Detlev 
Published: September 2003

AbstractFast chiral separations of a variety of basic and acidic compounds could be realized on microfluidic quartz chips. A microchip electrophoresis instrument equipped with a linear imaging UV‐detector was used. The usually applied but troublesome fluorescence tagging in order to enable fluorescence detection could be omitted. Using sulfated cyclodextrins as chiral selectors baseline separation of 19 compounds could be achieved in less than 1 min with high reproducibility. The relative standard deviation of migration time was below 7%. The fastest separation could be performed in 2.5 s which is to date the fastest separation of enantiomers reported. It was possible to apply microchip electrophoresis (MCE) for the determination of high enantiomeric excess (ee) values, as exemplarily shown for pseudoephedrin where 2% of the minor enantiomer could reliably be determined beside high amount of the other isomer. Successful separation of a mixture of 3 chiral drugs could be performed in a single run in less than 11 s utilizing a separation length of only 12 mm. These results show that MCE has great potential for fast chiral analysis and high‐throughput screening.
Effect of lipid composition on phospholipase A2‐catalyzed membrane leakage in immobilized liposomes: Sensitization for polychlorinated biphenyls detection with antibody affinity column tandem with fluorescent liposome column
Authors: Liu Xue‐Ying , Nakamura Chikashi , Hasegawa Miki , Miyake Jun 
Published: September 2003

AbstractPhospholipase A2 (PLA2)‐catalyzed membrane leakage can be detected by immobilized liposomes containing a self‐quenching fluorescent dye, calcein, on an open column using off‐line analysis with a fluorescent spectrophotometer. The calcein release was found to be affected by the pH value, incubation time, and liposome compositions. The fluorescent signal from the negatively charged liposomes hydrolyzed by PLA2 was 5 times higher than that from neutral liposomes. We utilized this enzymatic reaction to amplify signal to detect polychlorinated biphenyls (PCBs). To achieve this goal, we conjugated an analogue of PCB, 3,4‐dichloroaniline, to PLA2. The competitive immunoreaction between the 3,4‐dichloroaniline‐PLA2 conjugate and PCB samples on the anti‐PCB antibody column caused the release of the bound PLA2 conjugates in proportion to the PCB concentration. The released PLA2 conjugates was then passed through the tandem fluorescent liposome column causing release of fluorescent dye from the liposomes. Therefore, the signal of immunocompetitive assay was amplified on the fluorescent liposome column. The tandem column system achieves a high sensitivity by detecting the PCB concentration as low as 0.5 ng/mL in less than 20 min. It has great potential in detecting other pollutants, and has been used for sensitive immunoassays.
Trypsin activity assay in substrate‐specific one‐ and two‐dimensional gels: A powerful method to separate and characterize novel proteases in active form in biological samples
Authors: Zhao Zhenjun , Russell Pamela J. 
Published: September 2003

AbstractTo separate and identify the proteases, a substrate‐specific, sensitive assay in sodium dodecyl sulfate (SDS)‐polyacrylamide gels after two‐dimensional (2‐D) electrophoresis has been developed. This method allows simultaneous determination of protease cleavage specificity, molecular weight, isoelectric point, and if necessary, amino acid sequencing. After isoelectric focusing in immobilized pH gradient (IPG) strips (pH 6–11) (first dimension), trypsin was electrophoresed in 12% SDS polyacrylamide gels (second dimension) copolymerized with Boc‐Gln‐Ala‐Arg‐MCA (4‐methyl‐coumaryl‐7‐amide). The gels were washed in cold 2.5% Triton X‐100 and water, and incubated in assay buffer (6.3 mM Bicine, 100 mM NaCl). Trypsin cleavage of the peptide‐MCA generated fluorescent 7‐amino‐4‐methyl‐coumarin. In 1‐D gels, as low as 500 pg trypsin could be detected and trypsin band volumes correlated linearly with the amounts of trypsin (R2 = 0.999). In 2‐D gels, the lowest amount of trypsin detected was 1 ng. The linear regression of spot volume and loading amount was still good (R2 = 0.974). To optimize renaturation conditions, 5×5 min washes with 2.5% Triton X‐100 and water, respectively, gave the strongest band volume. For fluorescence development, an assay buffer at pH 9 was the best; incubation at 37°C for 30 min was sufficient. The method has application for identifying novel proteases as it does not rely on antibodies.
On‐line biosensors for simultaneous determination of glucose, choline, and glutamate integrated with a microseparation system
Authors: Shi Guoyue , Yamamoto Katsunobu , Zhou Tianshu , Xu Fan , Kato Takeshi , Ji‐ye Jin , Jin Litong 
Published: September 2003

AbstractAn effective microseparation system integrated with ring‐disc electrodes and two microfluidic devices was fabricated for in vivo determination using a microdialysis pump. The major interference of ascorbic acid (AA) was excluded by direct oxidation with ascorbate oxidase. Glucose, glutamate, and choline were successfully determined simultaneously through the biosensors modified with a bilayer of osmium‐poly(4‐vinylpyridine)gel‐horseradish peroxidase (Os‐gel‐HRP)/glucose oxidase (GOD), glutamate oxidase (GlutaOD) or choline oxidase (ChOD). To stabilize the biosensors, 0.2% polyethylenimine (PEI) was mixed with the oxidases. The cathodic currents of glucose, glutamate, and choline biosensors started to increase after the standard solutions were injected into the microseparation system. The on‐line biosensors show a wide calibration range (10−7–10−5 mol/L) with a detection limit of 10−8 mol/L at the working potential of −50 mV. The variations of glucose, glutamate, and choline were determined simultaneously in a free moving rat when we perfused the medial frontal cortex with 100 μmol/L N‐methyl‐D‐aspartate (NMDA) solution, which is the agonist of the NMDA receptor.
Fabrication and characterization of poly(methyl methacrylate) microchannels by in situ polymerization with a novel metal template
Authors: Chen Zhifeng , Gao Yunhua , Su Rongguo , Li Chengwu , Lin Jinming 
Published: September 2003

AbstractA stainless steel template for the fabrication of plastic microfluidic devices has been developed by photolithography and chemical etching technique. The preparation process of the template is simple, rapid, and low‐cost. The cross sectional profiles of raised microchannels on the template are trapezoidal. The surface roughness of the templates was controlled down to 190 nm. The template can be used repeatedly to generate devices reproducibly. The microfluidic devices of poly(methyl methacrylate) (PMMA) were fabricated by in situ polymerization using the templates. The reproducibility of the fabricated microchannel is high and the relative standard deviation is 0.7% by the in situ polymerization approach. Some physical properties of the polymerized microchannels were characterized including the transparency, the thermal deformation temperature, and the dimensional information. Current monitoring was used to evaluate the electroosmotic flow within the microchannels under the electric field strength of 300 V/cm.
Analysis of organic acids and inorganic anions in beverage drinks by capillary electrophoresis
Authors: Fung Ying Sing , Lau Kap Man 
Published: September 2003

AbstractTo meet the need for a new and validated analytical method for simultaneous determination of inorganic and organic acid anions in beverage drinks, a capillary zone electrophoresis (CZE) procedure had been developed based on a new background electrolyte (BGE) system containing 3 mmol/L 1,3,5‐benzenetricarboxylic acid (BTA), 15 mmol/L tris(hydroxymethyl)aminomethane and 1.5 mmol/L tetraethylenepentamine (TEPA) at pH 8.4. Baseline separation of anions commonly found in beverage drinks could be achieved in less than 14 min with indirect UV detection at 240 nm. Comigration problems for hydroxycarboxylic acids could be solved using TEPA as BGE additive. The results indicate excellent repeatability for migration time (RSD, 0.27–0.67%, n = 5) and good precision for both peak height (RSD, 3.2–4.2%, n = 5) and peak area (RSD, 3.1–4.5%, n = 5). Under the optimized conditions and using corrected peak area for quantitation, an excellent linear dynamic range (with correlation coefficient > 0.997 in a concentration range from 0.005 to 2.0 mmol/L) and low detection limit (1–4 μmol/L) were obtained for all the anions investigated. The applicability and reliability of the CE procedure developed were established by parallel method determination using established ion chromatography procedure for the analysis of inorganic and organic acid anions in orange juice and wine samples. Our CZE procedure provided a sensitive and economic technique for simultaneous determination of inorganic and organic acid anions in orange juice, red and white wine samples.
Signal denoising and baseline correction by discrete wavelet transform for microchip capillary electrophoresis
Authors: Liu Bi‐Feng , Sera Yoichi , Matsubara Norio , Otsuka Koji , Terabe Shigeru 
Published: September 2003

AbstractSignal denoising and baseline correction using discrete wavelet transform (DWT) are described for microchip capillary electrophoresis (MCE). DWT was performed on an electropherogram describing a separation of nine tetramethylrohodamine‐5‐isothiocyanate labeled amino acids, following MCE with laser‐induced fluorescence detection, using Daubechies 5 wavelet at a decomposition level of 6. The denoising efficiency was compared with, and proved to be superior to, other commonly used denoising techniques such as Fourier transform, Savitzky‐Golay smoothing and moving average, in terms of noise removal and peak preservation by directly visual inspection. Novel strategies for baseline correction were proposed, with a special interest in baseline drift that frequently occurred in chromatographic and electrophoretic separations.