bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fabrication of Tyrosinase Biosensor Based on Multiwalled Carbon Nanotubes‐Chitosan Composite and Its Application to Rapid Determination of Coliforms
Authors: Cheng Yuxiao , Liu Yajun , Huang Jingjing , Xian Yuezhong , Zhang Zhonghai , Jin Litong 
Published: May 2008

AbstractA tyrosinase (Tyr) biosensor was fabricated by immobilizing Tyr on the surface of multiwalled carbon nanotubes (MWNTs)‐chitosan (Chit) composite modified glassy carbon electrode (GCE). The MWNTs‐Chit composite film provided a biocompatible platform for the Tyr to retain the bioactivity and the MWNTs possessed excellent inherent conductivity to enhance the electron transfer rate. The Tyr/MWNTs‐Chit/GCE biosensor showed high sensitivity (412 mA/M), broad linear response (1.0×10−8–2.8×10−5 M), low detection limit (5.0 nM) and good stability (remained 93% after 10 days) for determination of phenol. The biosensor was further applied to rapid detection of the coliforms, represented by Escherichia coli (E. coli) in this work. The current responses were proportional to the quantity of coliforms in the range of 104–106 cfu/mL. After 5.0 h of incubation, E. coli could be detected as low as 10 cfu/mL.
Electrochemical Immunoassay for Free Prostate Specific Antigen (f‐PSA) Using Magnetic Beads
Authors: Sarkar P. , Ghosh D. , Bhattacharyay D. , Setford S. J. , Turner A. P. F. 
Published: May 2008

AbstractProstate specific antigen (PSA) is a prominent marker for the prostate carcinoma. It is found in human blood in free (f‐PSA) and complex forms. These two forms together are called total PSA (t‐PSA). Estimation of both forms is essential to predict malignancy. In this study we report a unique and effective technique of electrochemical detection of f‐PSA using magnetic beads on a three‐electrode screen‐printed sensor. A magnetic bead enzyme linked immunosorbent assay (ELISA) was performed in a cuvette. Following the immunoassay, magnetic beads were recovered by a magnetic concentrator and transferred on the working electrode of the 3‐electrode assembly. The amperometric response, a measure of the amount of residual enzyme activity on the beads and hence the concentration of analyte in solution, was determined by addition of enzyme substrate. The device has a detection limit of <0.1 ng mL−1 f‐PSA and a linear range of 0 to 1 ng mL−1 f‐PSA.
Voltammetric and DFT Studies on Viloxazine: Analytical Application to Pharmaceuticals and Biological Fluids
Authors: Garrido E. Manuela P. J. , Garrido Jorge M. P. J. , Esteves Mário , Santos‐Silva Alice , Marques M. Paula M. , Borges Fernanda 
Published: May 2008

AbstractThe oxidative behavior of viloxazine was studied at a glassy carbon electrode in different buffer systems using cyclic, differential pulse and square‐wave voltammetry. The oxidation process was shown to be diffusion‐controlled and irreversible over the studied pH. The voltammetric study of the model compounds, 2‐ethoxyanisole and morpholine, associated with quantum mechanical (DFT) calculations, allowed to elucidate the oxidation mechanism of viloxazine. An analytical method was developed for the quantification of viloxazine using an acetate pH 5 buffer solution as a supporting electrolyte. A linear response was obtained in the range 7 to 45 μM, with a detection limit of 0.8 μM. Validation parameters such as sensitivity, precision and accuracy were evaluated. The proposed method was successfully applied to the determination of viloxazine in pharmaceutical formulations and in human serum. The results were statistically compared with those obtained through an established high‐performance liquid chromatography technique, no significant differences having been found between the two methods.
A Solid State Polymer‐Coated Electrode Containing a Chiral Crown Ether Derivative for Enantioselective Detection of Phenylglycine Methyl Ester Isomer
Authors: Piao Ming‐Hua , Hwang Jaeyoung , Won Mi‐Sook , Hyun Myung Ho , Shim Yoon‐Bo 
Published: May 2008

AbstractAll solid‐state enantioselective electrode (ASESE) based on a newly synthesized chiral crown ether derivative ((R)‐(−)‐(3,3′‐diphenyl‐1,1′‐binaphthyl)‐23‐crown‐6 incorporating 1,4‐dimethoxybenzene) was prepared and characterized by potentiometry. The ASESE clearly showed enantiomer discrimination for methyl esters of alanine, leucine, valine, phenylalanine, and phenylglycine, where the enantioselectivity for phenylglycine methyl ester was the highest (KR,S=8.5±7.1%). Experimental parameters of ASESE for the analysis of (R)‐(−)‐phenylglycine methyl ester were optimized. The optimized ASESE showed a slope of 55.3±0.2 mV/dec for (R)‐(−)‐phenylglycine methyl ester in the concentration range of 1.0×10−5–1.0×10−2 M and the detection limit was 9.0×10−6 M. The ASESE showed good selectivity for (R)‐(−)‐phenylglycine methyl ester against inorganic cations and various amino acid methyl esters. The concentration of (R)‐(−)‐phenylglycine methyl ester was determined in the mixture of (R)‐(−) and (S)‐(+)‐phenylglycine methyl ester, which ratios varied from 2 : 1 to 1 : 9. The lifespan of the electrode was alleged to be 30 days.
Poly(neutral red): Electrosynthesis, Characterization, and Application as a Redox Mediator
Authors: Pauliukaite Rasa , Brett Christopher M. A. 
Published: May 2008

AbstractThe synthesis by electropolymerization, the characterization, and applications of poly(neutral red) (PNR), including as a redox mediator, are reviewed. PNR's high electrical conductivity and its redox characteristics have led to special applications of the polymer, and it has been used for the development of electrochemical and optical sensors. Moreover, the attractive properties of PNR allow it to be applied in the development of electrochemical biosensors. Future perspectives are indicated.
The Mediated Electrochemical Method for Rapid Fermentation Ability Assessment
Authors: Zhao Jinsheng , Wang Zhong , Fu Chonggang , Wang Min , He Qingpeng 
Published: May 2008

AbstractThe mediated electrochemical method characterized by the combinational utilization of two double mediator systems was proposed to assess the fermentation efficiency of three yeasts. The mediator systems selected were the menadione/ferricyanide system and the 2,6‐dichlorophenolindophenol (DCPIP)/ferricyanide system. Both the electrochemical responses and succinate dehydrogenase assay suggested that the menadione/ferricyanide system made the yeasts switch to anaerobic respiration and, the DCPIP/ferricyanide system let the yeasts remain in theirs fermentative mode. The ethanol yields (g ethanol/g glucose) and the RD/RM (RD and RM refer to the electrochemical response from the menadione/ferricyanide system and the DCPIP/ferricyanide system, respectively) values are 0.47 and 0.38, 0.24 and 0.75, 0.23 and 0.81, respectively, for Saccharomyces cerevisiae, Pachysolen tannophilus and Pichia stipitis. The results showed that there was a negative correlation between the ethanol yields and the RD/RM values of the three yeasts, which showed the feasibility of the mediated electrochemical method in rapid fermentation ability assay.
Novel Studies about the Electrooxidation of a Deoxynivalenol (DON) Mycotoxin Reduction Product Adsorbed on Glassy Carbon and Carbon Paste Electrodes
Authors: Molina Patricia Gabriela , Zón María Alicia , Fernández Héctor 
Published: May 2008

AbstractA novel and fast square‐wave adsorptive anodic stripping voltammetric procedure on glassy carbon and carbon paste electrodes is described for the indirect trace quantitation of deoxynivalenol (DON) mycotoxin that frequently contaminates soya and foodstuff. The in situ homogeneous reduction of the toxin by product/s of dissolved oxygen electroreduction in pH 8 buffer solution makes the quantitation of DON possible through a simple electroanalytical technique. Moreover, its potential use for the analysis of real samples was demonstrated using a soya flour sample spiked with DON without previous separating procedures. The DON detection limits were 3.6 and about 6 ppb from standard solutions and soya flour matrix, respectively.
Arsenite Determination in Phosphate Media at Electroaggregated Gold Nanoparticle Deposits
Authors: Rassaei Liza , Sillanpää Mika , French Robert W. , Compton Richard G. , Marken Frank 
Published: May 2008

AbstractCompared to bulk gold, highly reactive mesoporous gold film deposits are prepared on a boron‐doped diamond electrode surface. An electroaggregation process causing 5 nm diameter gold nanoparticles to deposit cathodically from aqueous solution is implemented to control the amount of mesoporous gold at the electrode surface. The resulting electrode surface is characterized by electron microscopy and by cyclic voltammetry.
Use of collision shear walls to minimize seismic separation and to protect adjacent buildings from collapse due to earthquake‐induced pounding
Authors: Anagnostopoulos S. A. , Karamaneas C. E. 
Published: May 2008

AbstractThe use of collision shear walls (bumper‐type), acting transversely to the side subject to pounding, as a measure to minimize damage of reinforced concrete buildings in contact, is investigated using 5‐story building models. The buildings were designed according to the Greek anti‐seismic and reinforced concrete design codes. Owing to story height differences potential pounding in case of an earthquake will occur between floor slabs, a case specifically chosen because this is when pounding can turn out to be catastrophic. The investigation is carried out using nonlinear dynamic analyses for a real earthquake motion and also a simplified solution for a triangular dynamic force of short duration, comparable to the forces caused by pounding. For such analyses, nonlinear, prismatic beam–column elements are used and the effects of pounding are expressed in terms of changes in rotational ductility factors of the building elements. The local effects of pounding on the collision shear walls are investigated using a detailed nonlinear finite element model of the shear walls and results are expressed in terms of induced stresses. It is found that pounding will cause instantaneous acceleration pulses in the colliding buildings and will somewhat increase ductility demands in the members of the top floor, but all within tolerable limits. At the same time the collision walls will suffer repairable local damage at the points of contact, but will effectively protect both buildings from collapse, which could occur if columns were in the place of the walls. Copyright © 2008 John Wiley & Sons, Ltd.
Direct use of PGV for estimating peak nonlinear oscillator displacements
Authors: Akkar Sinan , Küçükdoğan Bilge 
Published: May 2008

AbstractA predictive model is presented for estimating the peak inelastic oscillator displacements (Sd,ie) from peak ground velocity (PGV). The proposed model accounts for the variation of Sd,ie for bilinear hysteretic behavior under constant ductility (µ) and normalized lateral strength ratio (R) associated with postyield stiffness ratios of α=0 and 5%. The regression coefficients are based on a ground‐motion database that contains dense‐to‐stiff soil site recordings at distances of up to 30 km from the causative fault. The moment magnitude (M) range of the database is 5.2⩽M⩽7.6 and the ground motions do not exhibit pulse‐dominant signals. Confined to the limitations imposed by the ground‐motion database, the model can estimate Sd,ie by employing the PGV predictions obtained from the attenuation relationships (ground‐motion prediction equations). In this way, the influence of important seismological parameters can be incorporated to the variation of Sd,ie in a fairly rationale manner. This feature of the predictive model advocates its implementation in the probabilistic seismic hazard analysis that employs scalar ground‐motion intensity indices. Various case studies are presented to show the consistent estimations of Sd,ie by the proposed model. The error propagation in the Sd,ie estimations is also discussed when the proposed model is associated with attenuation relationships. Copyright © 2008 John Wiley & Sons, Ltd.
Genomewide linkage scan reveals novel loci modifying age of onset of Huntington's disease in the Venezuelan HD kindreds
Authors: Gayán Javier , Brocklebank Denise , Andresen J. Michael , Alkorta‐Aranburu Gorka , Zameel Cader M. , Roberts Simone A. , Cherny Stacey S. , Wexler Nancy S. , Cardon Lon R. , Housman David E. 
Published: May 2008

AbstractThe age of onset of Huntington's disease (HD) is inversely correlated with the CAG length in the HD gene. The CAG repeat length accounts for 70% of the variability in HD age of onset. However, 90% of individuals worldwide with expanded alleles possess between 40 and 50 CAG repeat lengths in their HD gene. For these people, the size of their repeat only determines 44% of the variability in their age of onset. Once the effect of the CAG repeat has been accounted for, the residual variance in age of onset is a heritable trait. Targeted candidate gene studies and a genome scan have suggested some loci as potential modifiers of the age of onset of HD. We analyzed the large Venezuelan kindreds in which the HD gene was originally identified. These kindreds offer greater analytic power than standard sib‐pair designs. We developed novel pedigree‐member selection procedures to maximize power. Using a 5,858‐single‐nucleotide‐polymorphism marker panel, we performed a genomewide linkage analysis. We discovered two novel loci on chromosome 2. Chromosome 2p25 (logarithm of the odds ratio (LOD)=4.29) and 2q35 (LOD=3.39) may contain genes that modify age of onset. A third linkage peak on chromosome 6q22 (LOD=2.48) may confirm the most promising locus from a previous genome scan. Two other candidate loci are suggestive on chromosome 5 (LOD=3.31 at 5p14 and LOD=3.14 at 5q32). All these regions harbor candidate genes that are potential HD modifier genes. Finding these modifier genes can reveal accessible and promising new therapeutic pathways and targets to ameliorate and cure HD. Genet. Epidemiol. 2008. © 2008 Wiley‐Liss, Inc.
On the utility of gene set methods in genomewide association studies of quantitative traits
Authors: Chasman Daniel I. 
Published: May 2008

AbstractIn genomewide genetic association studies, prior biological knowledge may help distinguish variation that is truly associated with a quantitative trait from the vast majority of unassociated variation that may be significant in hypothesis testing due to chance. However, formal methods for integrating prior biological knowledge into association studies have only been proposed recently, and their potential utility has not been thoroughly evaluated. Herein, gene set methods from genomewide analysis of gene expression data are adapted for application to genomewide genetic analysis of quantitative traits. The proposed gene set method was tested in simulations with gene sets that included up to 500 total variants, among which up to 20 collectively explained 5% of the variance. In a population of 1,000 individuals, the gene set method was largely more efficient at detecting truly associated variants in these gene sets than a comparably calibrated conventional approach relying on P‐values alone. While extremely strong associations remain best identified by conventional methods, the gene set approach may provide a complementary mode of analysis for revealing the full spectrum of genes that influence a quantitative trait. Genet. Epidemiol. 2008. © 2008 Wiley‐Liss, Inc.
A general method for linkage disequilibrium correction for multipoint linkage and association
Authors: Kurbasic Azra , Hössjer Ola 
Published: May 2008

AbstractLately, many different methods of linkage, association or joint analysis for family data have been invented and refined. Common to most of those is that they require a map of markers that are in linkage equilibrium. However, at the present day, high‐density single nucleotide polymorphisms (SNPs) maps are both more inexpensive to create and they have lower genotyping error. When marker data is incomplete, the crucial and computationally most demanding moment in the analysis is to calculate the inheritance distribution at a certain position on the chromosome. Recently, different ways of adjusting traditional methods of linkage analysis to denser maps of SNPs in linkage disequilibrium (LD) have been proposed. We describe a hidden Markov model which generalizes the Lander‐Green algorithm. It combines Markov chain for inheritance vectors with a Markov chain modelling founder haplotypes and in this way takes account for LD between SNPs. It can be applied to association, linkage or combined association and linkage analysis, general phenotypes and arbitrary score functions. We also define a joint likelihood for linkage and association that extends an idea of Kong and Cox (1997 Am. J. Hum. Genet. 61: 1179–1188) for pure linkage analysis. Genet. Epidemiol. 2008. © 2008 Wiley‐Liss, Inc.
The power of independent types of genetic information to detect association in a case‐control study design
Authors: Won Sungho , Elston Robert C. 
Published: May 2008

AbstractThere have been many single nucleotide polymorphism‐based tests suggested for association analysis in a case‐control design. The possible evidence for association comprises three types of information: differences between cases and controls in allele frequencies, in parameters for Hardy Weinberg disequilibrium (HWD) and in parameters for linkage disequilibrium (LD). Here, first we find the pairwise covariances between statistics that measure these three types of information and show that the statistics are asymptotically trivariate normally distributed. Then we compare their power analytically to determine the most informative statistics according to the disease model. Our results show that differences in parameters for HWD are informative for dominant and recessive disease models, while differences in allele frequencies and in parameters for LD are generally informative except for rare recessive disease models. There is mutual independence of the statistics that detect these three differences under Hardy Weinberg equilibrium at the marker locus and linkage equilibrium between markers in the population. Knowing the pairwise covariances between the statistics makes it possible to define statistics that are mutually independent. This allows us to perform sequential analyses of the same data without the need to adjust significance levels for all the multiple analyses being performed on the same data set. As a result we can have improved flexible strategies to increase the power of genome‐wide association studies without requiring the collection of a new, independent sample. Genet. Epidemiol. 2008. © 2008 Wiley‐Liss, Inc.
Age and region‐specific responses of microglia, but not astrocytes, suggest a role in selective vulnerability of dopamine neurons after 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine exposure in monkeys
Authors: Kanaan Nicholas M. , Kordower Jeffrey H. , Collier Timothy J. 
Published: May 2008

AbstractLittle is known about the effects of aging, the strongest risk factor for Parkinson's disease (PD), on glial responses to dopamine (DA) neuron degeneration in midbrain subregions that display selective vulnerability to degeneration. We evaluated the impact of aging on astrocytes and microglia in a regionally specific manner in a monkey model of PD. 1‐Methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) was delivered unilaterally via the internal carotid artery of young, middle‐aged, and old‐aged rhesus monkeys. Astrocytes and microglia were identified using glial fibrillary acidic protein and human leukocyte antigen‐DR (HLA‐DR) immunolabeling, respectively. Glial reactivity was assessed using (1) stereological cell counting, (2) fluorescence intensity, and (3) a morphology rating scale. In the midbrain contralateral and ipsilateral to the MPTP injection, astrocyte number and intensity did not change with age. In both sides of the midbrain, cellular morphology suggested astrocyte hypertrophy in middle‐age dissipated in old‐age, irrespective of DA subregion and regional differences in vulnerability to degeneration. In the contralateral midbrain, microglia became mildly activated (increased cell number and intensity, and morphological changes) with advancing age. Inflammation was evident at 3 months postlesion by severe microglial activation in the ipsilateral midbrain. HLA‐DR fluorescence intensity and an abundance of activated microglia (based on morphological criteria) were consistently exacerbated in the vtSN of both sides of the midbrain. These results suggest the glial responses accompanying aging and DA neuron degeneration following a toxic insult represent persistent alterations in the microenvironment of surviving DA neurons that are important factors in understanding regional differences in susceptibility to degeneration. © 2008 Wiley‐Liss, Inc.
Schwann cell precursors transplanted into the injured spinal cord multiply, integrate and are permissive for axon growth
Authors: Agudo M. , Woodhoo A. , Webber D. , Mirsky R. , Jessen K.R. , Mcmahon S.B. 
Published: May 2008

AbstractThere is a strong current interest in the use of cell transplantation for the treatment of spinal cord injuries. We report here the novel and potentially useful properties of an early cell in the Schwann cell lineage, the Schwann cell precursor (SCP). The experiments reveal a striking difference between these cells and Schwann cells when transplanted into the CNS. Unlike Schwann cells, SCPs thrive in the CNS where they initially proliferate rapidly but then fall out of division, thus effectively filling up the large cystic cavities formed following crush injury, while avoiding tumor formation. By 8 weeks, SCPs had started to express S100β protein, a marker that differentiates Schwann cells from SCPs and had formed an apparently stable, vascularized cell mass, which created a continuous cellular bridge across the cystic cavities. The formation of the surrounding glial scar was reduced by local spread of the transplanted cells into the surrounding CNS tissue, where the cells integrated intimately with astrocytes and attenuated the physical barrier they normally form. SCP transplantation also altered and reduced the expression of chondroitin sulfate proteoglycans around the injury site. Caudal to the SCP transplants there was a large increase in the number of axons, compared with that seen in nontransplanted control tissue, showing that the implants effectively support axonal growth or sprouting. SCPs have advantageous attributes for CNS repair, despite the fact that sticky tape removal and ladder crossing tests at 8 weeks did not reveal significant functional improvements when compared with control animals. © 2008 Wiley‐Liss, Inc.
Women and international assignments: Taking stock—a 25‐year review
Authors: Altman Yochanan , Shortland Susan 
Published: May 2008

AbstractWomen's progress into management and, more specifically, into the world of expatriates, is the subject of this review. Despite advances in equal opportunities legislation, women failed to embark on expatriate missions in significant numbers during the 1980s. In the 1990s, more women were offered international assignment opportunities but they remained a negligible minority compared to men. The first decade of the twenty‐first century has witnessed a gradual increase in the number and visibility of women in international assignments. Through a comprehensive review of the literature over the period from 1980 to now, this article charts the emerging themes and changes in the tone of dis‐course: from when organizations were debating whether to “give women a chance” through attempts to identify and remove “blockages” to women's progress to, most recently, structural changes in the expatriate assignment and claims for women's superior affinity to operating internationally. We highlight gaps in the current literature and propose a platform for future research. We conclude with recommendations for practice. © 2008 Wiley Periodicals, Inc.