bluuebunny/crossref_metadata_2025_split huggingface dataset:
Family‐based and case–control study of catechol‐O‐methyltransferase in schizophrenia among Palestinian Arabs
Authors: Kremer I. , Pinto M. , Murad I. , Muhaheed M. , Bannoura I. , Muller D.J. , Schulze T.G. , Reshef A. , Blanaru M. , Gathas S. , Goichman R. , Rietschel M. , Dobrusin M. , Bachner‐Melman R. , Nemanov L. , Belmaker R.H. , Maier W. , Ebstein R.P. 
Published: April 2003

AbstractCOMT is a ubiquitous enzyme crucial to catechol metabolism. The molecular basis of COMT thermolability, that leads to three to fourfold differences in enzyme activity, is due to a substitution of valine with methionine in the Val158/108Met polymorphism. Of special interest is the role of this gene in major psychoses especially since a microdeletion (22q11) containing the COMT gene (velo‐cardio‐facial syndrome) also carries with it several types of behavioral disorders, including an increased prevalence of schizophrenia. Almost 20 genetic studies have examined the role of COMT in schizophrenia with ambiguous results. Towards clarifying the role of this polymorphism in conferring risk for psychosis, we examined a large group of culturally and ethnically akin Palestinian Arab schizophrenic triads (N = 276) using both a case–control and family‐based study. In 194 informative triads with at least one heterozygote parent, no preferential transmission of either COMT allele was observed in this sample (TDT statistic chi‐square = 0.14 NS; 131 COMT valine alleles were transmitted and 125 alleles not transmitted). However, using a case–control design a significant increase (Likelihood ratio = 3.935, P = 0.047) in the valine allele was observed in the group of schizophrenic patients (N = 276) compared to an ethnically matched control group (N = 77). The association was stronger in female patients (P = 0.012) similar to other studies showing that some COMT behavioral effects are gender sensitive. In summary, by case–control design but not by a family‐based study, there is a weak effect in female patients of the high activity COMT allele in conferring risk for schizophrenia. © 2003 Wiley‐Liss, Inc.
Wolfram syndrome and suicide: Evidence for a role of WFS1 in suicidal and impulsive behavior
Authors: Sequeira Adolfo , Kim Caroline , Seguin Monique , Lesage Alain , Chawky Nadia , Desautels Alex , Tousignant Michel , Vanier Claude , Lipp Olivier , Benkelfat Chawki , Rouleau Guy , Turecki Gustavo 
Published: April 2003

AbstractThere is evidence suggesting that subjects affected with the Wolfram syndrome (WFS) and normal carriers present an increased risk of psychiatric disorders, particularly depression and suicidal behavior. We investigated a possible role of the gene involved in WFS (WFS1) in the neurobiology of suicide and the potential modulatory effect on traits associated to suicidal behavior. Genetic variation at WFS1 (H611R, R456H, and I333V) was investigated in 111 suicide victims and 129 normal controls. Possible effects on psychopathology and behavioral traits were investigated in a subsample of suicide cases (N = 31) for whom phenotyping was carried out by means of structured psychiatric interviews and questionnaires adapted for psychological autopsies. We found a significantly higher frequency of the 611R/611R genotype in suicide completers as compared to controls (χ2 = 19.21, df=2, P = 0.001). Suicide completers with this genotype had higher scores on measures of impulsivity (t = −3.15, df = 15.3, P = 0.006); novelty seeking (NS) (t = −3.35, df = 13.8, P = 0.005); and conversely, lower scores of persistence (t = 2.4, df = 16.6, P = 0.028). Scores of impulsivity and NS remained higher in subjects with the associated genotype after adjusting for age, gender, and psychopathology. These results suggest a role for WFS1 in the pathophysiology of impulsive suicide, and are consistent with previous clinical reports suggesting an increased risk of suicidal behavior in WFS homozygotes and heterozygotes. However, these findings are preliminary and should be confirmed in independent samples. © 2003 Wiley‐Liss, Inc.
Nanotechnology with Soft Materials
Authors: Hamley I. W. 
Published: April 2003

AbstractNature exploits self‐organization of soft materials in many ways, to produce cell membranes, biopolymer fibers and viruses, to name just three. Mankind is now able to design materials at the nanoscale, whether through atom‐by‐atom or molecule‐by‐molecule methods (top‐down) or through self‐organization (bottom‐up). The latter method encompasses soft nanotechnology. Self‐organization of soft materials can be exploited to create a panoply of nanostructures for diverse applications. The richness of structures results from the weak ordering because of noncovalent interactions. Thus, thermal energy is important as it enables transitions between phases with differing degrees of order. The power of self‐organization may be harnessed most usefully in a number of nanotechnology applications, which include the preparation of nanoparticles, the templating of nanostructures, nanomotor design, the exploitation of biomineralization, and the development of functionalized delivery vectors.
Nonparametric Tests for Interval‐Censored Failure Time Data
Authors: Lim Hee‐Jeong , Sun Jianguo 
Published: April 2003

AbstractThis paper discusses two sample nonparametric comparison of survival functions when only interval‐censored failure time data are available. The problem considered often occurs in, for example, biological and medical studies such as medical follow‐up studies and clinical trials. For the problem, we present and study several nonparametric test procedures that include methods based on both absolute and squared survival differences as well as simple survival differences. The presented tests provide alternatives to existing methods, most of which are rank‐based tests and not sensitive to nonproportional or nonmonotone alternatives. Simulation studies are performed to evaluate and compare the proposed methods with existing methods and suggest that the proposed tests work well for nonmonotone alternatives as well as monotone alternatives. An illustrative example is presented.
Tests for Trend in Binary Response
Authors: Salanti Georgia , Ulm Kurt 
Published: April 2003

AbstractTests for trend are important in analyzing data where the binary response in ordered categories is of interest. An example is in toxicology where the response in various dose groups is observed. For testing an association between the dose and the response the approach from Cochran and Armitage is widely used. However the result of this test is highly dependent on the scores assigned to the dose groups. Various dose assignments can lead to different outcomes. As an alternative the isotonic regression, a nonparametric method, is proposed. The outcome of this approach is independent of the quantification of the dose. Both methods (Cochran‐Armitage test and isotonic regression) are compared within a simulation study to an isotonic version of the Pearson's Chi‐squared test and the Wilcoxon rank sum test.
Choice of Scores in Trend Tests for Case‐Control Studies of Candidate‐Gene Associations
Authors: Zheng Gang , Freidlin Boris , Li Zhaohai , Gastwirth Joseph L. 
Published: April 2003

AbstractWhen applying the Cochran‐Armitage (CA) trend test for an association between a candidate allele and a disease in a case‐control study, a set of scores must be assigned to the genotypes. Sasieni (1997, Biometrics 53, 1253–1261) suggested scores for the recessive, additive, and dominant models but did not examine their statistical properties. Using the criteria of minimizing the required sample size of the CA trend test to achieve prespecified type I and type II errors, we show that the scores given by Sasieni (1997) are optimal for the recessive and dominant models and locally optimal for the additive one. Moreover, the additive scores are shown to be locally optimal for the multiplicative model. The tests are applied to a real dataset.
Estimation of Linkage and Association from Allele Transmission Data
Authors: Malley James D. , Redner Richard A. , Severini Thomas A. , Badner Judith A. , Pajevic Sinisa , Bailey‐Wilson Joan E. 
Published: April 2003

AbstractThe TDT provides a hypothesis test for the presence of linkage or association (linkage disequilibrium). However, since the TDT is a single test statistic, it cannot be used to separate association and linkage. The importance of this difficulty, following a significant TDT result, has been recently emphasized by Whittaker, Denham and Morris (2000), who alert the community to the possibility that a significant TDT may result from loose linkage and strong association, or from tight linkage and weak association.To attack this problem we start with the parametric model for family‐based allele transmission data of Sham and Curtis (1995) (or Sham (1998)) and find that the parameters in the model are not always identifiable. So we introduce a reparameterization that resolves the identifiability issues and leads to a valid likelihood ratio (LR) test for linkage.Since the linkage and association parameters are both of interest, we next introduce and apply an integrated likelihood (IL) approach to provide separate point estimates and confidence intervals for these parameters. The estimates are shown to have generally small bias and mean square error, while the confidence intervals have good average length and coverage probabilities. We compare the power of the IL approach for testing linkage and, separately association, with the TDT and LR.
Spatial Point Pattern Analysis by using Voronoi Diagrams and Delaunay Tessellations – A Comparative Study
Authors: Chiu S.N. 
Published: April 2003

AbstractGiven a spatial point pattern, we use various characteristics of its Voronoi diagram and Delaunay tessellation to extract information of the dependence between points. In particular, we use the characteristics to construct statistics for testing complete spatial randomness. It is shown that the minimum angle of a typical Delaunay triangle is sensitive to both regularity and clustering alternatives, whilst the triangle's area or perimeter is more sensitive to clustering than regularity. These statistics are also sensitive to the Baddeley‐Silverman cell process.
Support Vector Machines for Protein Fold Class Prediction
Authors: Markowetz Florian , Edler Lutz , Vingron Martin 
Published: April 2003

AbstractKnowledge of the three‐dimensional structure of a protein is essential for describing and understanding its function. Today, a large number of known protein sequences faces a small number of identified structures. Thus, the need arises to predict structure from sequence without using time‐consuming experimental identification. In this paper the performance of Support Vector Machines (SVMs) is compared to Neural Networks and to standard statistical classification methods as Discriminant Analysis and Nearest Neighbor Classification. We show that SVMs can beat the competing methods on a dataset of 268 protein sequences to be classified into a set of 42 fold classes. We discuss misclassification with respect to biological function and similarity. In a second step we examine the performance of SVMs if the embedding is varied from frequencies of single amino acids to frequencies of tripletts of amino acids. This work shows that SVMs provide a promising alternative to standard statistical classification and prediction methods in functional genomics.
Nonenzymatic protocol for Pseudomonas aeruginosa DNA preparation and rapid subtyping by mini pulsed‐field gel electrophoresis
Authors: López‐Cánovas Lilia , Sánchez‐Alonso Axel , Higginson David , Ariosa Concepcion , Clark Hilda , Riverón Ana Maria 
Published: April 2003

AbstractThe fastest protocol for Pseudomonas aeruginosa subtyping by contour clamped homogeneous electric field (CHEF) electrophoresis takes around 20 h. It includes enzymatic sample preparation, DNA restriction and fragment separation. Here, P. aeruginosa cells embedded in agarose miniplugs were lysed and deproteinized by incubating the miniplugs for 30 min in a single nonenzymatic solution. DNA molecules were digested for 2 h with 5 U of XbaI, and fragments were separated in 4.96 h by miniCHEF electrophoresis at 10 V/cm. Total time for P. aeruginosa subtyping was 8 h. Control experiments included DNA preparation by enzymatic or nonenzymatic protocols, different times of DNA restriction and comparisons of DNA separations done by miniCHEF or CHEF electrophoresis. Both methods and chambers gave similar results, but the rapid nonenzymatic method and the miniCHEF gave them in less time. Cells grown in broth or on plates were useful for nonenzymatic DNA preparation. Thirteen P. aeruginosa isolates were successfully fingerprinted using the protocol described here.
Poly‐N‐hydroxyethylacrylamide as a novel, adsorbed coating for protein separation by capillary electrophoresis
Authors: Albarghouthi Methal N. , Stein Thomas M. , Barron Annelise E. 
Published: April 2003

AbstractWe present the polymer poly‐N‐hydroxyethylacrylamide (PHEA) (trade name, polyDuramide™) as a novel, hydrophilic, adsorbed capillary coating for electrophoretic protein analysis. Preparation of the PHEA coating requires a simple and fast (30 min) protocol that can be easily automated in capillary electrophoresis instruments. Over the pH range of 3–8.4, the PHEA coating is shown to reduce electroosmotic flow (EOF) by about 2 orders of magnitude compared to the bare silica capillary. In a systematic comparative study, the adsorbed PHEA coating exhibited minimal interactions with both acidic and basic proteins, providing efficient protein separations with excellent reproducibility on par with a covalent polyacrylamide coating. Hydrophobic interactions between proteins and a relatively hydrophobic poly‐N,N‐dimethylacrylamide (PDMA) adsorbed coating, on the other hand, adversely affected separation reproducibility and efficiency. Under both acidic and basic buffer conditions, the adsorbed PHEA coating produced an EOF suppression performance comparable to that of covalent polyacrylamide coating and superior to that of adsorbed PDMA coating. The protein separation performance in PHEA‐coated capillaries was retained for 275 consecutive protein separation runs at pH 8.4, and for more than 800 runs at pH 4.4. The unique and novel combination of hydrophilicity and adsorptive coating ability of PHEA makes it a suitable wall coating for automated microscale analysis of proteins by capillary array systems.
Laser‐induced quenched phosphorescence detection in capillary electrophoresis
Authors: Kuijt Jacobus , Ariese Freek , Brinkman Udo A. T. , Gooijer Cees 
Published: April 2003

AbstractThe feasibility of laser‐based excitation for quenched phosphorescence detection in capillary electrophoresis (CE) was explored for the first time by using a small‐size, quadrupled Nd‐YAG laser emitting 266 nm pulses (duration, 0.4 ns) at a repetition rate of 7.8 kHz. To provide a continuous phosphorescence background, the phosphorophore 1‐bromo‐4‐naphthalene sulfonic acid (BrNS) was added to the separation buffer. Both experiments and theory show that in laser‐induced phosphorescence (LIP) – in contrast with lamp‐excited phosphorescence – one normally deals with such high triplet‐state phosphorophore concentrations that triplet‐triplet annihilation is the major deactivation pathway. This results in a lower quantum yield of the analyte‐induced bimolecular quenching interaction and, thus, the observed quenching signal. The situation can be improved by using a cylindrical lens for excitation in order to reduce the irradiance. In this case limits of detection (LODs) similar to those obtained using lamp excitation (1×10–8 M) were achieved, while the width of the detection window was reduced from about 4 mm to 1 mm. Even under exclusion of triplet‐triplet annihilation, i.e., under conditions of low irradiance, for our setup the quenching yields in LIP were smaller than in lamp‐based phosphorescence detection. This is due to the repetition rate of the laser (7.8 kHz), which is too high in view of the phosphorescence lifetime (ca. 300 μs at low irradiance). Theory shows that this disadvantageous effect will be fully eliminated if the repetition rate is decreased to 1 kHz.
Evaluation of diabetic ketoacidosis‐related ionic metabolites in human blood serum by capillary electrophoresis
Authors: Jager Alessandra V. , Tavares Marina F. M. 
Published: April 2003

AbstractThree methodologies are presented to contemplate the analysis of sodium, potassium, chloride, bicarbonate, lactate, acetoacetate, and β‐hydroxybutyrate in blood serum samples of diabetic patients using free solution capillary electrophoresis with indirect detection (214 nm for cations and 254 nm for anions). The cations were analyzed in less than 6 min in an electrolyte comprised of 15 mmol·L–1 imidazole, 5 mmol·L–1 lactate and 1 mmol·L–1 18‐crown‐6‐ether, adjusted to pH 4.5. Chloride and bicarbonate were analyzed in 2 min in a 5 mmol·L–1 chromate, 0.1 mmol·L–1 cetyltrimethylammonium bromide (CTAB), pH 9.0 electrolyte solution. Ketoacids and lactate were analyzed in less than 11 min in an electrolyte composed of 15 mmol·L–1 3,5‐dinitrobenzoate, 0.1 mmol·L–1 CTAB, at pH 3.5. All methodologies were validated with respect to linearity, selectivity, sensitivity, precision and accuracy performing adequately for clinical purposes.
Strategies for the determination of cefazolin in plasma and microdialysis samples by short‐end capillary zone electrophoresis
Authors: Mayer Bernhard X. , Petsch Martina , Tschernko Edda M. , Müller Markus 
Published: April 2003

AbstractCapillary zone electrophoresis was employed to determine cefazolin, a first‐generation cephalosporin antibiotic, in plasma and microdialysis samples from patients. To shorten the analysis, the samples were injected from the short end of the capillary, resulting in a separation time of < 3 min. Due to a high ionic strength of the biological matrices it was necessary to optimize the stacking conditions. For microdialysis samples a 1:10 dilution with water before injection was sufficient to obtain good peak shape. For plasma samples a protein removal step was required to obtain clean electropherograms and a good peak shape. Acetonitrile was used as precipitant resulting in an enhanced sample stacking in comparison to water dilution. The disadvantage of using acetonitrile was severe evaporation loss making quantitation impossible. A self‐sealing film was used to seal each individual sample vial to suppress evaporation during long‐term sequences. The calibration curves for spiked plasma and cefazolin in Ringer's solutions were linear in the range from 2–500 and 2.5–100 μg/mL, respectively. Limits of detection were 1.0 and 2.0 μg/mL in plasma and microdialysis samples, respectively. The assay was successfully applied to plasma and microdialysis samples obtained in vivo from the interstial space fluid of subcutaneous adipose and muscle tissue of patients undergoing cardiac surgery.
Quantitative analysis of aglycone quercetin in mulberry leaves (Morus alba L.) by capillary zone electrophoresis
Authors: Suntornsuk Leena , Kasemsook Saowapak , Wongyai Surapote 
Published: April 2003

AbstractA capillary zone electrophoresis method was established for analysis of aglycone quercetin in mulberry leaves (Morus alba L.). The influence of, e.g., background electrolyte concentrations and pH, surfactant concentrations, organic solvents, temperature, and voltage on the separation of aglycone quercetin, rutin, quercitrin, kaempferol, catechin, and gallic acid was systematically investigated. The optimum condition providing baseline separation of all compounds within 16.5 min was obtained in 150 mM boric acid (pH 10.0) using a fused‐silica capillary with an effective length of 42.5 cm (50 μm inner diameter), temperature of 32°C, and voltage of 15 kV. Method assessment was performed by standard addition method using rutin as an internal standard. Linearity of the method was excellent (r2 > 0.999) over the concentration tested (40–160 μg/mL). The relative standard deviations (%RSDs) from injection, intraday, and interday precision were less than 2.5%. Recoveries were good (≈︁ 100.0%,%RSD = 0.8%) with a limit of detection (LOD) and limit of quantitation (LOQ) of 0.86 and 3.16 μg/mL (%RSD = 1.8%), respectively. The aglycone quercetin found in the mulberry leaves was 0.452 g/100 g (%RSD = 0.6%) on dry weight.
Low‐voltage driven control in electrophoresis microchips by traveling electric field
Authors: Fu Lung‐Ming , Yang Ruey‐Jen 
Published: April 2003

AbstractThis paper presents the use of a physical model and numerical simulation in the investigation of traveling electric fields on capillary electrophoresis (CE) chips. The principal material transport mechanisms of electrokinetic migration, ionic concentration, fluid flow, and diffusion are all taken into consideration. Traditionally, the high electric field strength required for the separation of biological samples by microfluidic devices has involved the application of high external voltages. In contrast, this study presents a proposal for samples separation by means of a moving electric field within a low voltage‐driven CE chip. Under this proposal, the separation channel is partitioned into a series of smaller separation zones by means of electrode pairs. This paper considers two different electrode configurations, namely arranged along a single side of the separation channel, and arranged on two sides of the separation channel. The quality of the separation achieved with these two configurations is then compared with the traditional straight separation channel approach. The results confirm that the proposed method is successful in maintaining an adequate field strength for separation purposes in a low‐voltage driven CE chip. Furthermore, it is determined that the best separation results are obtained using electrodes arranged along both sides of the separation channel.
Towards a microchip‐based chromatographic platform. Part 2: Sol‐gel phases modified with polyelectrolyte multilayers for capillary electrochromatography
Authors: Breadmore Michael C. , Shrinivasan Sushil , Karlinsey James , Ferrance Jerome P. , Norris Pamela M. , Landers James P. 
Published: April 2003

AbstractThe potential for using polyelectrolyte multilayers (PEMs) to provide chromatographic functionality on continuous silica networks created from sol‐gel chemistry has been evaluated by capillary electrochromatography (CEC). Construction of the PEM was achieved by flushing the column with polyelectrolytes of alternative charge, with variation of the properties of the exposed polyelectrolyte providing a unique means to vary the chromatographic surface. Variation of the exposed polyelectrolyte from poly(diallyldimethylammonium chloride) (PDDAC) to dextran sulfate (DS) allowed the direction of the electroosmotic flow (EOF) to be changed and also provided a means to vary the chromatographic capacity. Variation of negative polymer from DS to poly(styrene sulfonate) (PSS) significantly altered the EOF and the migration of peptides, with both the reversed‐phase and ion‐exchange capacities increasing. An alternative method for changing the column capacity was to change the thickness of the PEM, which was evaluated by anion‐exchange CEC. A 70–80% increase in retention was observed for all anions without any increase in EOF suggesting significant penetration of the analytes through the PEM and interaction with buried charges within the PEM.