bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid determination of five probe drugs and their metabolites in human plasma and urine by liquid chromatography/tandem mass spectrometry: application to cytochrome P450 phenotyping studies
Authors: Yin Ophelia Q. P. , Lam Sherry S. L. , Lo Cindy M. Y. , Chow Moses S. S. 
Published: November 2004

AbstractA liquid chromatography/mass spectrometry method, for rapid determination of five cytochrome P450 (CYP) probe drugs and their relevant metabolites in human plasma and urine, is described. The five specific probe substrates/metabolites, caffeine/paraxanthine (CYP1A2), tolbutamide/4‐hydroxytolbutamide/carboxytolbutamide (CYP2C9), omeprazole/5‐hydroxyomeprazole (CYP2C19), debrisoquine/5‐hydroxydebrisoquine (CYP2D6) and midazolam/1′‐hydroxymidazolam (CYP3A), together with the internal standards (phenacetin and paracetamol), in plasma and urine, were extracted using solid‐phase extraction. The chromatography was performed using a C18 column with an isocratic mobile phase consisting of acetonitrile and 0.1% formic acid in water (70:30). The triple‐quadrupole mass spectrometer was operated in both positive and negative modes, and multiple reaction monitoring was used for quantification. The method was validated over the concentration ranges 0.05–5 μg/mL for caffeine and paraxanthine, 0.02–2 μg/mL for tolbutamide, 0.1–20 μg/mL for 4‐hydroxytolbutamide, carboxytolbutamide, debrisoquine and 5‐hydroxydebrisoquine, 5–2500 ng/mL for omeprazole and 5‐hydroxyomeprazole, and 1–100 ng/mL for midazolam and 1′‐hydroxymidazolam. The intra‐ and inter‐day precision were 0.3–13.7% and 1.9–14.3%, respectively, and the accuracy ranged from 93.5–107.2%. The lower limit of quantification varied between 1 and 100 ng/mL. The present method provides a robust, fast and sensitive analytical tool for the five‐probe drug cocktail, and has been successfully applied to a clinical phenotyping study in 16 subjects. Copyright © 2004 John Wiley & Sons, Ltd.
Matrix‐assisted and polymer‐assisted laser desorption/ionization time‐of‐flight mass spectrometric analysis of low molecular weight polystyrenes and polyethylene glycols
Authors: Woldegiorgis Andreas , Löwenhielm Peter , Björk Anders , Roeraade Johan 
Published: November 2004

AbstractRecently, matrices based on oligomers of dioxin and thiophene (polymer‐assisted laser desorption/ionization (PALDI)) have been described for mass spectrometric (MS) analysis of low molecular weight compounds (Woldegiorgis A, von Kieseritzky F, Dahlstedt E, Hellberg J, Brinck T, Roeraade J. Rapid Commun. Mass Spectrom. 2004; 18: 841–852). In this paper, we report the use of PALDI matrices for low molecular weight polymers. An evaluation with polystyrene and polyethylene glycol showed that no charge transfer ionization occurs. Ionization is mediated through metal ion adduction. Comparison of matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) data for two very low molecular weight polymers with data obtained from size‐exclusion chromatography (SEC) revealed a systematic difference regarding mean molecular weight and dispersity. Further, the mass spectra obtained with PALDI matrices had a higher signal‐to‐noise ratio than the spectra obtained with conventional matrices. For polymers with higher molecular weights (>1500 Da), the conventional matrices gave better performance. For evaluation of the MALDI spectra, three non‐linear mathematical models were evaluated to model the cumulative distributions of the different oligomers and their maximal values of Mw, Mn and PDI. Models based on sigmoidal or Boltzmann equations proved to be most suitable. Objective modeling tools are necessary to compare different sample and instrumental conditions during method optimization of MALDI analysis of polymers, since the bias between MALDI and SEC data can be misleading. Copyright © 2004 John Wiley & Sons, Ltd.
Tandem (quadrupole‐time‐of‐flight) electrospray mass spectrometry of oligo(vinyl acetates) with isopropylol or (1‐hydroxyethyl)‐2‐oxyisopropanyl end groups
Authors: Collins Steven , Rimmer Stephen 
Published: November 2004

AbstractPoly(vinyl acetates) with either isopropylol or (1‐hydroxyethyl)‐2‐oxyisopropanyl end groups were analysed by tandem mass spectrometry using a quadrupole‐time‐of‐flight (Q‐TOF) instrument. Random scission along the polymer backbone was not observed. Instead the initial scissions were derived from the cleavage of end‐group species. The resultant macrocations were subject to further elimination reactions that eventually produced polyene macrocations. A smaller fraction of the initial macrocations also reacted by loss of ketene and this reaction produced macrocations containing vinyl alcohol units. Copyright © 2004 John Wiley & Sons, Ltd.
Water quality before and after dam building on a heavily polluted river in semi‐arid Algeria
Authors: Taleb Amina , Belaidi Nouria , Gagneur James 
Published: November 2004

AbstractThe impact of the construction and management of a reservoir on a polluted stream in a semi‐arid region has been highlighted using physico‐chemical indicators. The Tafna river (Algeria) collects heavily polluted wastewater from the town of Maghnia and from several factories. Organic pollution comes from domestic sewage and from food industries. Ore treatment industries discharge very acidic wastewater. Temperature, pH, conductivity, chloride, dissolved oxygen, biological oxygen demand (BOD), and nitrogen compounds have been surveyed between 1996 and 2001, before and after the construction of the dam. The change in each parameter is compared between sites located upstream and downstream from the dam.The spatio‐temporal evolution of the organic pollution indicators was highlighted by ANOVA and principal component analysis. By enhancing sedimentation of the organic matter, the reservoir makes possible a significant decline in the BOD downstream of the dam, but increases NH4 concentration at the downstream sites. The pollution is diluted during high flows and dam releases. Conversely, during low flow periods, mineralization of organic matter is higher in the lower Tafna. Copyright © 2004 John Wiley & Sons, Ltd.
Movements of wild atlantic salmon parr in relation to peaking flows below a hydropower station
Authors: Berland G. , Nickelsen T. , Heggenes J. , Økland F. , Thorstad E. B. , Halleraker J. 
Published: November 2004

AbstractMovements of 20 radio‐tagged wild Atlantic salmon (Salmo salar) parr were studied 1.3 km downstream of a hydropower station. Ten parr were free‐ranging and ten were restricted to an area near the river bank by a 75 m2 rectangular containment pen that was flooded at high flow, but dry at low flow except for a small refuge at the low end. The positions of contained parr were continuously recorded within a four‐cell uniform grid by continuous data logging, while free‐ranging fish were positioned by manual tracking four times per day. River discharge was manipulated to run five pseudo‐replicated series of three step changes from 30 to 70 to 110 m3 s−1, with slow (2 h) and rapid (0 h) increase and decrease in discharge, as well as during day and night. No differences in movements or home ranges (mean 2770 m2 ± 1759 SD) were detected related to manipulated discharge variations or time of day or night for the free‐ranging parr. No free‐ranging parr were stranded during rapid flow reductions. In the containment pen, the parr distributed themselves relatively evenly among the cells. They moved significantly more at changing than at stable flows. In the containment pen, most of the fish that were stranded were observed during rapid flow reductions at night. Rapid reductions in water flow may cause increased mortality in large parr in shallow habitats if movements are restricted; however, rapid fluctuations did not appear to influence movements or cause stranding by free‐ranging Atlantic salmon parr, which moved considerable distances regardless of discharge. Copyright © 2004 John Wiley & Sons, Ltd.
X‐ray photoelectron spectroscopy analysis of the stability of platinized catalytic electrodes in dye‐sensitized solar cells
Authors: Wang Guiqiang , Lin Yuan , Xiao XuRui , Li XuePing , Wang Weibo 
Published: November 2004

AbstractThe stability of platinized catalytic electrodes prepared by thermal decomposition of hexachloroplatinic acid was investigated. The platinum on the electrode did not dissolve in the presence of the electrolyte containing an iodide/triiodide redox couple, even under anodic bias. The electrocatalytic activity of platinized catalytic electrodes sealed in a cell with oxygen‐free electrolyte did not decrease within 23 weeks. However, the charge transfer resistance value of platinized catalytic electrodes increased tenfold when the electrodes were heated at 150° for 15 min in air during the sealing process and doubled when the electrodes were reused. The XPS analysis results showed that part of the platinum catalyst on the surface of the electrode was transformed to Pt[II] and Pt[IV] during the thermal sealing process, which led to the decrease of catalytic activity of the platinized catalytic electrodes for the reduction of triiodide. A large amount of inactive iodine absorbed on the surface of the reused electrode, which was confirmed by XPS, also decreased the electrocatalytic activity of the electrodes. The electrocatalytic activity of reused electrodes can be recovered by heating again at 390 °C or removing the platinum oxide and inactive iodine by the electrochemical method. Copyright © 2004 John Wiley & Sons, Ltd.
The use of quantile regression in health care research: a case study examining gender differences in the timeliness of thrombolytic therapy
Authors: Austin Peter C. , Tu Jack V. , Daly Paul A. , Alter David A. 
Published: November 2004

AbstractInvestigators are frequently interested in determining patient and system characteristics associated with delays in the provision of essential medical treatment. Investigators have typically used either multiple linear regression or Cox proportional hazards models to assess the impact of patient and system characteristics on the timeliness of medical treatment. A drawback to the use of these two methods is that they allow, at best, a partial exploration of how a distribution of delays in treatment or of waiting times changes with patient characteristics. In contrast, quantile regression models allow one to assess how any quantile of a conditional distribution changes with patient characteristics. We illustrate the utility of quantile regression by examining gender differences in the delivery of thrombolysis in patients with an acute myocardial infarction. We demonstrate that richer inferences can be drawn through the use of quantile regression. Females were more likely to experience delays in treatment compared to males. Furthermore, gender had a greater impact upon those patients who had the greatest delays in treatment. Investigators who want to determine how a distribution of delays in treatment or of waiting times changes with patient or system characteristics should consider complementing their analyses with the use of quantile regression. Copyright © 2004 John Wiley & Sons, Ltd.
On simultaneous assessment of sensitivity and specificity when combining two diagnostic tests
Authors: Tang Man‐Lai 
Published: November 2004

AbstractDiagnostic tests are seldom adopted in isolation. Few tests have high sensitivity and specificity simultaneously. In these cases, one can increase either the sensitivity or the specificity by combining two component tests under either the ‘either positive’ rule or the ‘both positive’ rule. However, there is a tradeoff between sensitivity and specificity when these rules are applied. We propose three statistical procedures to simultaneously assess the sensitivity and specificity when combining two component tests. Measurements of interest include rate difference and rate ratio. Our empirical results demonstrate that (i) the asymptotic test procedures for both measurements and approximate test procedure for rate difference possess inflated type I error rate; (ii) the exact test procedures for both measurements possess deflated type I error rate; and (iii) the approximate (unconditional) test procedure for rate ratio becomes an reliable alternative and nicely controls the actual type I error rate in small to moderate sample sizes. Moreover, the approximate (unconditional) test procedure is computationally less intensive than the exact (unconditional) test procedure. We illustrate our methodologies with a real example from a residual nasopharyngeal carcinoma (RNP) study. Copyright © 2004 John Wiley & Sons, Ltd.
Study of the Thermoplastic Wheat Starch Cationisation Reaction under Molten Condition
Authors: Ayoub Ali , Berzin Françoise , Tighzert Lan , Bliard Christophe 
Published: November 2004

AbstractThis paper deals with the functionalization of thermoplastic wheat starch with cationic groups under the action of thermo‐mechanical energy. Two reagents, leading to the same reactive species, are used: 3‐chloro‐2‐hydroxypropyltrimethylammonium chloride and 2‐epoxypropyltrimethylammonium chloride. An experimental study and a theoretical approach for reactive extrusion operations were carried out in a bench‐top twin‐screw microcompounder. The theoretical model developed is in satisfactory agreement with the experimental results obtained in the molten state, with low water content. Reaction kinetic studies, performed at different temperatures between 100 and 140°C, show that starch cationisation follows a second order reaction, with rate constants following the Arrhenius law. The obtained results allow calculation of the values of activation energy. The analysis of the thermoplastic unmodified and modified cationic starches by size exclusion chromatography (SEC) shows a decrease of the excluded fraction, which is attributed to the effect of the thermo‐mechanical melting process. The X‐ray diffraction spectra typical of molten starches were obtained.
Studies on the composition of ancient Indian punch‐marked silver coins
Authors: Vijayan V. , Rautray T. R. , Nayak P. K. , Basa D. K. 
Published: November 2004

AbstractPunch‐marked coins are the oldest known numismatic objects used in ancient India. Seven punch‐marked silver coins were analysed by using the non‐destructive multi‐elemental PIXE technique. A 3 MeV proton beam from a pelletron accelerator was used for irradiation of these samples to obtain the spectral data and GUPIX software was employed to derive the elemental concentrations. The results reveals that silver, copper, gold and lead are significant constituents of the punch‐marked silver coins and there are also traces of elements such as Ti, Cr, Mn, Fe, Co, Ni, As and Y, which seems to imply that PIXE can be used effectively for the non‐destructive quantitative analysis of ancient coins. Copyright © 2004 John Wiley & Sons, Ltd.
Spectrum function of polarizer‐scattered x‐ray tube radiation
Authors: Kitov B. I. 
Published: November 2004

AbstractAn equation was derived to calculate the x‐ray tube spectrum from a massive anode and scattered from a homogeneous flat target. The spectrum function of molybdenum anode radiation scattered from a boron carbide polarizer was calculated. Copyright © 2004 John Wiley & Sons, Ltd.
Nitric oxide synthase inhibition impairs myocardial efficiency and ventriculo‐arterial matching in acute ischemic heart failure
Authors: Nordhaug Dag , Steensrud Tor , Aghajani Ebrahim , Korvald Christian , Myrmel Truls 
Published: November 2004

AbstractBackground and aims:The effect of nitric oxide (NO) manipulation in acute heart failure has not been sufficiently investigated. Therefore, we assessed the impact of NO‐synthase (NOS) inhibition on left ventricular (LV) function and energetics as well as overall hemodynamics, in a porcine model of acute ischemic LV failure.Methods:Acute heart failure was induced by left coronary artery microembolization in fourteen anesthetized pigs. LV pressure–volume relationships and mechanical work (PVA) were assessed 30 min after stable heart failure, using pressure‐conductance catheters. Myocardial oxygen consumption (MVO2) was determined from coronary flow and coronary arteriovenous oxygen difference. Microembolization led to a significant decrease in cardiac output, arterial pressure and LV systolic and diastolic performance. Animals were then randomized to a control group (n=7) or to receive 15 mg/kg Nω‐Nitro‐l‐arginine‐metyl ester (n=7), an inhibitor of NO synthase (NOS).Results:Measurements 15 min later revealed that NOS inhibited animals had significantly reduced cardiac output (1.53±0.45 vs. 2.13±0.49 l/min, P=0.003) and stroke work (1054±461 vs. 1296±348 mmHg ml, P=0.03), and also displayed a significant increase in the slope of the MVO2–PVA relationship (2.57±0.53 vs. 1.92±0.15, P=0.008), i.e. an inefficient chemomechanical coupling. NOS inhibition did not alter contractility, diastolic function or arterial pressure, but afterload was significantly increased compared to controls (arterial elastance 6.03±1.48 vs. 2.74±0.34 mmHg/ml, P=0.009).Conclusion:Inhibition of NOS in experimental acute heart failure increased afterload without altering left ventricular systolic and diastolic function. Consequently, cardiac output was reduced. Furthermore, mechanoenergetic efficiency was severely impaired. NOS inhibition in acute heart failure and cardiogenic shock warrants further investigations.
The value of the electrocardiogram and chest X‐ray for confirming or refuting a suspected diagnosis of heart failure in the community
Authors: Fonseca Cândida , Mota Teresa , Morais Humberto , Matias Fernando , Costa Catarina , Oliveira António G. , Ceia Fátima ,   on behalf of the EPICA Investigators
Published: November 2004

AbstractBackgroundThere is a common assumption that a normal ECG or a normal heart size on chest X‐ray virtually rules out a diagnosis of heart failure.AimsTo assess the value of the electrocardiogram and chest X‐ray in identifying patients with chronic heart failure in the community.Methods and resultsThis study was a secondary analysis of data prospectively collected at the time of patient's enrolment in the EPICA study, an epidemiological study of the prevalence of heart failure in Portugal. A total of 6300 subjects were clinically evaluated. Patients who presented with symptoms or signs of heart failure, and/or were receiving diuretics for chronic heart failure (CHF) had a chest X‐ray, ECG, and echocardiogram. The diagnosis of heart failure was confirmed in 551 cases. Patients with right atrial enlargement, atrial flutter, atrial fibrillation, 2nd degree‐Mobitz I atrioventricular block, 1st degree atrioventricular block, left bundle branch block, lung interstitial oedema, and bilateral pleural effusion were more likely to be diagnosed with heart failure. For the diagnosis of heart failure, in the Portuguese population aged over 25 years, an abnormal electrocardiogram had an estimated sensitivity of 81%, and negative predictive value of 75%; an abnormal chest X‐ray had an estimated sensitivity of 57%, and negative predictive value of 83%. Twenty five percent of patients with CHF had a normal ECG or chest X‐ray.ConclusionOur results show that electrocardiographic and roentgenographic features are not sufficient to allow heart failure to be reliably predicted in the community and support the recommendation that all patients with suspected heart failure should undergo echocardiography.
Reducing postpartum hemorrhage in Africa
Authors: Lazarus J.V. , Lalonde A. 
Published: November 2004

AbstractPostpartum hemorrhage (PPH) is the leading cause of maternal mortality in sub‐Saharan Africa. This is being addressed by leading professional organizations, which point to the importance of a skilled attendant at birth. But they also emphasize that the active management of the third stage of labor is proven to reduce the incidence of PPH. In low‐income settings, the prostaglandin misoprostol should be considered as it is low‐cost, stable at room temperature and easy to administer.
Operon prediction without a training set
Authors: Westover B. P. , Buhler J. D. , Sonnenburg J. L. , Gordon J. I. 
Published: November 2004

Abstract
Motivation: Annotation of operons in a bacterial genome is an important step in determining an organism's transcriptional regulatory program. While extensive studies of operon structure have been carried out in a few species such as Escherichia coli, fewer resources exist to inform operon prediction in newly sequenced genomes. In particular, many extant operon finders require a large body of training examples to learn the properties of operons in the target organism. For newly sequenced genomes, such examples are generally not available; moreover, a model of operons trained on one species may not reflect the properties of other, distantly related organisms. We encountered these issues in the course of predicting operons in the genome of Bacteroides thetaiotaomicron (B.theta), a common anaerobe that is a prominent component of the normal adult human intestinal microbial community.
Results: We describe an operon predictor designed to work without extensive training data. We rely on a small set of a priori assumptions about the properties of the genome being annotated that permit estimation of the probability that two adjacent genes lie in a common operon. Predictions integrate several sources of information, including intergenic distance, common functional annotation and a novel formulation of conserved gene order. We validate our predictor both on the known operons of E.coli and on the genome of B.theta, using expression data to evaluate our predictions in the latter.
Availability: The software is available online at http://www.cse.wustl.edu/~jbuhler/research/operons
Contact: jbuhler@cse.wustl.edu
NetAcet: prediction of N-terminal acetylation sites
Authors: Kiemer Lars , Bendtsen Jannick Dyrløv , Blom Nikolaj 
Published: November 2004

Abstract
Summary: We present here a neural network based method for prediction of N-terminal acetylation—by far the most abundant post-translational modification in eukaryotes. The method was developed on a yeast dataset for N-acetyltransferase A (NatA) acetylation, which is the type of N-acetylation for which most examples are known and for which orthologs have been found in several eukaryotes. We obtain correlation coefficients close to 0.7 on yeast data and a sensitivity up to 74% on mammalian data, suggesting that the method is valid for eukaryotic NatA orthologs.
Availability: The NetAcet prediction method is available as a public web server at http://www.cbs.dtu.dk/services/NetAcet/
Contact: nikob@cbs.dtu.dk
Supplementary information: http://www.cbs.dtu.dk/services/NetAcet/
Detection of low level genomic alterations by comparative genomic hybridization based on cDNA micro-arrays
Authors: Bilke Sven , Chen Qing-Rong , Whiteford Craig C. , Khan Javed 
Published: November 2004

Abstract
Motivation: The accumulation of genomic alterations is an important process in tumor formation and progression. Comparative genomic hybridization performed on cDNA arrays (cDNA aCGH) is a common method to investigate the genomic alterations on a genome-wide scale. However, when detecting low-level DNA copy number changes this technology requires the use of noise reduction strategies due to a low signal to noise ratio.
Results: Currently a running average smoothing filter is the most frequently used noise reduction strategy. We analyzed this strategy theoretically and experimentally and found that it is not sensitive to very low level genomic alterations. The presence of systematic errors in the data is one of the main reasons for this failure. We developed a novel algorithm which efficiently reduces systematic noise and allows for the detection of low-level genomic alterations. The algorithm is based on comparison of the biological relevant data to data from so-called self–self hybridizations, additional experiments which contain no biological information but contain systematic errors. We find that with our algorithm the effective resolution for ±1 DNA copy number changes is about 2 Mb. For copy number changes larger than three the effective resolution is on the level of single genes.
Contact: bilkes@mail.nih.gov