bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling ssDNA electrophoretic migration with band broadening in an entangled or cross‐linked network
Authors: Chen Zheng , Graham Richard , Burns Mark A. , Larson Ronald G. 
Published: August 2007

AbstractWe use a coarse‐grained model proposed by Graham and Larson based on the temporary network model by Schieber et al.. [1] to simulate the electrophoretic motion of ssDNA and corresponding band broadening due to dispersion. With dimensionless numbers reflecting the experimental physical properties, we are able to simulate ssDNA behavior under weak to moderate electric field strengths for chains with 8–50 entanglements per chain (∼1000–8500 base pairs), and model smoothly the transition from reptation to oriented reptation. These results are fitted with an interpolation equation, which allows the user to calculate dimensionless mobilities easily from input parameters characterizing the gel matrix, DNA molecules, and field strengths. Dimensionless peak widths are predicted from mobility fluctuations using the central limit theorem and the assumption that the mobility fluctuations are Gaussian. Using results from previous studies of ssDNA physical properties (effective charge ξq and Kuhn step length bK) and sieving matrix properties (pore size or tube diameter a), we give scaling factors to convert the dimensionless values to “real” experimental values, including the mobility, migration distance, and time. We find that the interpolation equation fits well the experimental data of ssDNA mobilities and peak widths, supporting the validity of the coarse‐grained model. The model does not account for constraint release and hernia formation, and assumes that the sieving network is a homogeneous microstructure with no temperature gradients and no peak width due to injection. These assumptions can be relaxed in future work for more accurate prediction.
Specific and genotypic identification of Cryptosporidium from a broad range of host species by nonisotopic SSCP analysis of nuclear ribosomal DNA
Authors: Jex Aaron R. , Ryan Una M. , Ng Josephine , Campbell Bronwyn E. , Xiao Lihua , Stevens Melita , Gasser Robin B. 
Published: August 2007

AbstractThe accurate identification of Cryptosporidium (Protozoa: Apicomplexa) species and genotypes is central to the understanding of the transmission and to the diagnosis and control of cryptosporidiosis. In this study, we demonstrate the effectiveness of nonisotopic SSCP analysis of a ∼300 bp region of the small subunit (pSSU) of ribosomal DNA for the specific identification of and delineation among 18 different Cryptosporidium species and genotypes from a wide range of hosts. This mutation scanning approach allowed the rapid and reliable differentiation between species/genotypes differing by as little as 1.3% in the pSSU sequence, with the capacity to detect point mutations. The present findings confirm the usefulness of this tool for the rapid genetic screening of Cryptosporidium samples from any host species, providing a foundation for detailed systematic, epidemiological and ecological studies. Although applied herein to pSSU, this low cost approach should be applicable to a wide range of genetic loci for population genetic investigations of Cryptosporidium.
Low EOF rate measurement based on constant effective mobility in microchip CE
Authors: Wang Wei , Zhao Liang , Zhou Fang , Zhang Jian‐Rong , Zhu Jun‐Jie , Chen Hong‐Yuan 
Published: August 2007

AbstractA new method for quickly determining low EOF rates (μEOF) in microchip CE is described. The measurement is based on the notion that the effective mobility (μeff) of an analyte is a constant in a certain BGE. The μeff of an analyte is determined in a reference fast‐electroosmosis microchip, and the apparent mobility (μapp) of the analyte can be determined in the microchip with unknown low electroosmosis, and then μEOF in the low‐electroosmosis microchip can be calculated according to the equation μEOF = μapp − μeff. By an indirect method or other conventional methods, μeff can be easily measured in the reference microchip. The proposed method is particularly useful for low‐electroosmosis measurements in wall‐modified microchannels.
Fabrication of poly(methyl methacrylate) microfluidic chips by redox‐initiated polymerization
Authors: Chen Jiang , Lin Yuehe , Chen Gang 
Published: August 2007

AbstractIn this report, a method based on the redox‐initiated polymerization of methyl methacrylate (MMA) has been developed for the rapid fabrication of poly(methyl methacrylate) (PMMA) microfluidic chips. MMA containing 2‐2′‐azo‐bis‐isobutyronitrile was allowed to prepolymerize in a water bath to form a viscous prepolymer solution that was subsequently mixed with MMA containing a redox‐initiation couple of benzoyl peroxide/N,N‐dimethylaniline. The dense molding solution was sandwiched between a silicon template and a piece of 1‐mm‐thick PMMA plate. The polymerization could complete within 50 min under ambient temperature. The images of raised microfluidic structures on the silicon template were precisely replicated into the synthesized PMMA substrate during the redox‐initiated polymerization of the molding solution. The chips were subsequently assembled by the thermal bonding of the channel plates and the covers. The new fabrication approach obviates the need for special equipment and significantly simplifies the process of fabricating PMMA microdevices. The attractive performance of the novel PMMA microchips has been demonstrated in connection with contactless conductivity detection for the separation and detection of ionic species.
Improvement of transient stability by unified power flow controller based on Hamiltonian system theory
Authors: Hao J. , Shi Li‐Bao , Ni Yi‐Xin , Chen C. 
Published: August 2007

AbstractIn this paper we propose a novel Hamiltonian theory based controller design methodology for unified power flow controller (UPFC) control to improve the dynamic performance of power systems. The Hamiltonian theory of the differential‐algebraic (DA) system is described and a simple control strategy is deduced to stabilize the system. Furthermore, the influence of the control law on the stability region of the system is discussed as well. It can be proved that the stability region of the system can indeed be enlarged under the control strategy. The UPFC control scheme of multi‐machine power system is developed, and a classical three‐generator system is used to validate the effectiveness of the control law. Copyright © 2007 John Wiley & Sons, Ltd.
On estimating an asset's implicit beta
Authors: Husmann Sven , Stephan Andreas 
Published: August 2007

AbstractA.F. Siegel (1995) has developed a technique with which the systematic risk of a security (beta) can be estimated without recourse to historical capital market data. Instead, beta is estimated implicity from the current market prices of exchange options that enable the exchange of a security against shares on the market index. Because this type of exchange options is not currently traded on the capital markets, Siegel's technique cannot yet be used in practice. This study will show that beta can also be estimated implicitly from the current market prices of plain vanilla options, based on the capital asset pricing model. Empirical evidence on implicit betas is provided using prices of exchange options from the European Derivatives Exchange Market (EUREX) over years 2000 to 2004. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27:961–979, 2007
Short/long heterozygotes at 5HTTLPR and white matter lesions in geriatric depression
Authors: Steffens David C. , Taylor Warren D. , McQuoid Douglas R. , Krishnan K. Ranga R. 
Published: August 2007

AbstractObjectiveWe examined the relationship between 5HTTLPR genotype and volume of magnetic resonance imaging (MRI) brain lesions.MethodWe studied 217 older depressed patients and 141 individuals in the comparison group using a standard brain MRI protocol to calculate lesion volumes. Genotype at 5HTTLPR was determined for each subject.ResultsIn age‐adjusted models, the l/s genotype was associated with increased volume of total and white‐matter lesions among depressed patients. This relationship lost significance in models controlling for reported hypertension.ConclusionsThe finding that 5HTTLPR heterozygotes have higher vascular lesion volumes may be related to development of hypertension. Copyright © 2007 John Wiley & Sons, Ltd.
Diagnosing dementia ‐ ICD‐10 not so bad after all: a comparison between dementia criteria according to DSM‐IV and ICD‐10
Authors: Naik Mala , Nygaard Harald A. 
Published: August 2007

AbstractBackgroundThe discrepancy between results of diagnosing dementia with ICD‐10 and DSM‐IV has been shown by several studies. Our aim was to show that the two diagnostic systems are more or less alike if ICD‐10 is interpreted in the way we believe is in the intention of the ICD‐10 authors.MethodsTwo hundred and seven patients consecutively referred patients and their caregivers were interviewed and the patients were clinically examined. Algorithms using criteria for the World health Organization's International classification of Diseases, 10th revision (ICD‐10) and the American Psychiatric Association's, the fourth edition (DSM‐IV) were followed to diagnose dementia.ResultsA diagnosis of dementia was made for 198 patients and there was 100% agreement (kappa = 1,0) between ICD‐10 and DSM‐IV diagnosis.ConclusionIn the ICD‐10 criteria ‘decline in other cognitive abilities such as abstraction, judgement, problem solving’ has been interpreted in a way that all the above executive functions must be impaired for diagnosing dementia. According to our interpretation these are meant to be examples of functions which may be compromised in demented patients.The results of our study demonstrate that this interpretation of ICD‐10 has shown that the authors of ICD‐10 and DSM‐IV have succeeded in harmonising the two systems. However, the ICD‐10 criteria are phrased in a way that leaves much to individual interpretation. WHO has to define the ICD criteria in such a way that there is uniformity in its interpretation. Copyright © 2007 John Wiley & Sons, Ltd.
Calcium‐independent phospholipase A2 influences AMPA‐mediated toxicity of hippocampal slices by regulating the GluR1 subunit in synaptic membranes
Authors: Ménard Caroline , Chartier Émilie , Patenaude Christian , Robinson Pierre , Cyr Michel , Baudry Michel , Massicotte Guy 
Published: August 2007

AbstractWe have recently documented that phosphorylation of the GluR1 subunit of α‐amino‐3‐hydroxy‐5‐methylisoxazole‐propionate (AMPA) glutamate receptors is influenced by calcium‐independent forms of phospholipase A2 (iPLA2) activity in the brain. Given the importance of GluR1 subunit phosphorylation in the control of AMPA receptor delivery to synaptic membranes, we tested the influence of iPLA2 activity on AMPA receptor distribution between neuronal compartments, using organotypic cultured hippocampal slices. In agreement with earlier reports, the iPLA2 inhibitor bromoenol lactone (BEL) markedly enhanced the phosphorylation of the GluR1 subunit at both Ser831 and Ser845 residues. GluR1 subunit phosphorylation levels were selectively increased by (R)‐BEL, an enantio‐selective inhibitor of iPLA2γ, but not by (S)‐BEL, an iPLA2β inhibitor. The iPLA2γ inhibitor R‐BEL also promoted the insertion of new GluR1 subunits into synaptic membranes and exacerbated AMPA‐mediated cell death in the CA1 region of the hippocampus. The latter effect was selectively abolished by IEM 1460 and philanthotoxin‐433, two antagonists specific for AMPA receptors lacking GluR2 subunits. These results provide evidence that iPLA2γ‐related regulation of AMPA receptor GluR1 subunit phosphorylation could represent an important mechanism modulating hippocampal cell death induced by AMPA receptor overstimulation. © 2007 Wiley‐Liss, Inc.
Evidence for episodic memory in a pavlovian conditioning procedure in rats
Authors: O'Brien Jamus , Sutherland Robert J. 
Published: August 2007

AbstractIn an effort to evaluate episodic memory processes in the rat, we developed a novel Pavlovian conditioning procedure. Rats explored two distinctive contexts, one in the morning and the other in the evening. Subsequently, either in the morning or the evening, they received a foot shock immediately upon entry into a third context that equally resembled the two explored contexts. When conditioned freezing was measured at an intermediate time of day, rats showed significantly more fear of the context congruent with the time of day of the foot shock. Thus, rats automatically form an integrated time–place memory that can be flexibly updated by future events, essential characteristics of episodic memory. © 2007 Wiley‐Liss, Inc.
Perirhinal and hippocampal contributions to visual recognition memory can be distinguished from those of occipito‐temporal structures based on conscious awareness of prior occurrence
Authors: Danckert S.L. , Gati J.S. , Menon R.S. , Köhler S. 
Published: August 2007

AbstractThe ability of humans to distinguish consciously between new and previously encountered objects can be probed with visual recognition memory tasks that require explicit old–new discriminations. Medial temporal‐lobe (MTL) lesions impair performance on such tasks. Within the MTL, both perirhinal cortex and the hippocampus have been implicated. Cognitive processes can also be affected by past object encounters in the absence of conscious recognition, as in repetition priming tasks. Past functional neuroimaging findings in healthy individuals suggest that even in tasks that require conscious recognition decisions for visual stimuli, posterior cortical structures in the ventral visual pathway distinguish between old and new objects at a nonconscious level. Conclusive evidence that differentiates the neural underpinnings of conscious from nonconscious processes in recognition memory, however, is still missing. In particular, functional magnetic resonance imaging (fMRI) findings for the MTL have been inconsistent towards this end. In the present fMRI study, we tested whether perirhinal and hippocampal contributions to recognition memory can be distinguished from those of occipito‐temporal structures in the ventral visual pathway based on the participants' reported conscious awareness of prior occurrence. Images of objects with a large degree of feature overlap served as stimuli; they were selected to ensure an involvement of perirhinal cortex in the present recognition task, based on evidence from past lesion‐based research. We found that both perirhinal cortex and occipito‐temporal cortex showed a differential old–new response that reflected a repetition‐related decrease in activity (i.e., new > old). Whereas in perirhinal cortex this decrease was observed with respect to whether subjects reported objects to be old or new, irrespective of the true item status, in occipito‐temporal cortex it occurred in relation to whether objects were truly old or new, irrespective of the participants' conscious reports. Hippocampal responses differed in their exact pattern from those of perirhinal cortex, but were also related to the conscious recognition reports. These results indicate that both perirhinal and hippocampal contributions can be distinguished from those of occipito‐temporal structures in the ventral visual pathway based on the participants' reported conscious awareness of prior occurrence. © 2007 Wiley‐Liss, Inc.
The hippocampal indexing theory and episodic memory: Updating the index
Authors: Teyler Timothy J. , Rudy Jerry W. 
Published: August 2007

AbstractA little over 20 years ago, (Teyler and DiScenna,1986; Behav Neurosci 100:147–152) proposed the hippocampal memory index theory. It offered an account of episodic memory based on the intrinsic organization of the hippocampus, its synaptic physiology and its anatomical relationship to other regions of the brain. The essence of their idea was that the hippocampus was functionally designed and anatomically situated to capture information about neocortical activity generated by the individual features of behavioral episode. Moreover, because the hippocampus projects back to these neocortical regions the information it stored could serve as an index to the pattern of neocortical activity produced by the episode. Consequently, a partial cue that activated the index could activate the neocortical patterns and thus retrieve the memory of the episode. In this article we revisit and update indexing theory. Our conclusion is that it has aged very well. Its core ideas can be seen in many contemporary theories and there is a wealth of data that support this conceptual framework. © 2007 Wiley‐Liss, Inc.
Dysregulation of growth factor receptor‐bound protein 2 and fascin in hippocampus of mice polytransgenic for chromosome 21 structures
Authors: Shin Joo‐Ho , Guedj Fayçal , Delabar Jean‐Maurice , Lubec Gert 
Published: August 2007

AbstractNonchimeric polytransgenic 152F7 mice encompassing four human chromosome 21 genes (DSCR3, DSCR5, TTC3, and DYRK1A) within the Down syndrome critical region present with learning and memory impairment. However, no abnormalities were shown by in vitro electrophysiological or neuroanatomical findings in hippocampus of 152F7 mice. To search for molecular changes that may be linked to cognitive impairment, we compared hippocampal protein levels between nontransgenic (WT) and 152F7 mice by a proteomic approach. Protein extracts were run on two‐dimensional gel electrophoresis, protein spots were analyzed by mass spectrometry (MALDI‐TOF‐TOF) followed by quantification by specific software. Three hundred and nineteen different gene products were identified, and 48 proteins were assigned as signaling‐related proteins. Stringent statistical analysis considering P < 0.005 as statistically significant based upon multiple testing revealed that growth factor receptor‐bound protein 2 (Grb2) levels were decreased and an expression form of fascin 1 was increased in 152F7 mice when compared with WT. A series of proteins showed trends for increased and decreased hippocampal levels (P > 0.005 and P < 0.05). Only 2 out of 319 different gene products were dysregulated, pointing to the specificity of the analysis. Decreased Grb2 levels in the hippocampus of 152F7 mice may contribute to impaired cytoskeleton functions because dynamin 1 binds to Grb2 and involved in the formation of the endocytic process. Fascin dysregulation is of relevance for actin bundling in vesicle trafficking and may represent or lead to impaired neurotransmission that, in turn, may lead to the cognitive defect observed in this mouse model of Down syndrome. © 2007 Wiley‐Liss, Inc.
Differential involvement of the dorsal hippocampus in passive avoidance in C57bl/6J and DBA/2J mice
Authors: Baarendse Petra J.J. , van Grootheest Gerard , Jansen René F. , Pieneman Anton W. , Ögren Sven Ove , Verhage Matthijs , Stiedl Oliver 
Published: August 2007

AbstractThe inferior performance of DBA/2 mice when compared to C57BL/6 mice in hippocampus‐dependent behavioral tasks including contextual fear conditioning has been attributed to impaired hippocampal function. However, DBA/2J mice have been reported to perform similarly or even better than C57BL/6J mice in the passive avoidance (PA) task that most likely also depends on hippocampal function. The apparent discrepancy in PA versus fear conditioning performance in these two strains of mice was investigated using an automated PA system. The aim was to determine whether these two mouse strains utilize different strategies involving a different contribution of hippocampal mechanisms to encode PA. C57BL/6J mice exhibited significantly longer retention latencies than DBA/2J mice when tested 24 h after training irrespective of the circadian cycle. Dorsohippocampal NMDA receptor inhibition by local injection of the selective antagonist DL‐2‐amino‐5‐phosphonovaleric acid (AP5, 3.2 μg/mouse) before training resulted in impaired PA retention in C57BL/6J but not in DBA/2J mice. Furthermore, nonreinforced pre‐exposure to the PA system before training caused a latent inhibition‐like reduction of retention latencies in C57BL/6J, whereas it improved PA retention in DBA/2J mice. These pre‐exposure experiments facilitated the discrimination of hippocampal involvement without local pharmacological intervention. The results indicate differences in PA learning between these two strains based on a different NMDA receptor involvement in the dorsal hippocampus in this emotional learning task. We hypothesize that mouse strains can differ in their PA learning performance based on their relative ability to form associations on the basis of unisensory versus multisensory contextual/spatial cues that involve hippocampal processing. © 2007 Wiley‐Liss, Inc.
Estradiol enhances long term potentiation in hippocampal slices from aged apoE4‐TR mice
Authors: Yun Sung Hwan , Park Kyung A. , Kwon Sung , Woolley Catherine S. , Sullivan Patrick M. , Pasternak Joseph F. , Trommer Barbara L. 
Published: August 2007

AbstractHormone replacement therapy to treat or prevent Alzheimer Disease (AD) in postmenopausal women is controversial because it may pose other health risks such as cancer and thromboembolism. ApoE status is thought to influence the nootropic efficacy of hormone therapy, but findings are neither consistent nor well understood. We used a known in vitro memory model (long‐term potentiation, LTP) in aged (24–27 month) female targeted replacement mice expressing human apoE3 or E4 to compare the effects of exogenous estradiol. Recording medial perforant path evoked field potentials in dentate gyrus of hippocampal slices, we found that both strains exhibited comparable basal synaptic transmission as assessed by input/output functions and paired pulse depression, and that these measures were not affected by estradiol. Vehicle‐treated groups from both strains showed comparable LTP. Estradiol had no effect on LTP in apoE3‐TR, but selectively increased LTP magnitude in apoE4‐TR. The estradiol induced enhancement of LTP in aged female apoE4‐TR is consistent with recent clinical observations that estrogen replacement decreases AD risk in some women with apoE4. Elucidating the mechanism of this selective enhancement may lead to more informed treatment decisions as well as to the development of safer alternatives to hormone therapy. © 2007 Wiley‐Liss, Inc.