bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tactile coactivation resets age‐related decline of human tactile discrimination
Authors: Dinse Hubert R. , Kleibel Nadine , Kalisch Tobias , Ragert Patrick , Wilimzig Claudia , Tegenthoff Martin 
Published: May 2006

AbstractObjectiveFor young subjects, it is well‐documented that training and practice improve sensorimotor performance. However, little is known about how the typically observed age‐related decline of sensorimotor abilities can be ameliorated by sensory stimulation.MethodsAs an alternative approach to training, we have introduced a tactile coactivation protocol involving Hebbian synaptic plasticity to improve tactile performance on a short timescale of a few hours.ResultsBy applying coactivation on the index finger to drive perceptual learning, we demonstrate that in the elderly, aged 65 to 89 years, the age‐related impairment of tactile two‐point discrimination can be mitigated substantially. In elderly adults, tactile‐acuity thresholds increased to 3.5mm compared with 1.5mm found in young adults, whereas 50‐year‐old subjects showed intermediate performance. As a result of coactivation, discrimination thresholds of the 80‐year‐old adults came to match those typically found at an age of 50, demonstrating that age‐related decline in tactile performance is not irreversible, but rather subject to considerable restoration by specific stimulation protocols.InterpretationBecause the preservation of sufficient tactile acuity into advanced age is an important prerequisite for the maintenance of autonomous living, we believe that the concept of coactivation might turn out to be beneficial in preserving everyday sensorimotor competence in the elderly through new forms of therapeutic interventions. Ann Neurol 2006.
Differential twin concordance for multiple sclerosis by latitude of birthplace
Authors: Islam Talat , Gauderman W. James , Cozen Wendy , Hamilton Ann S. , Burnett Margaret E. , Mack Thomas M. 
Published: May 2006

AbstractObjectiveTo address the inconsistency in the reported concordance of multiple sclerosis (MS) among twins by zygosity, sex, and latitude.MethodsFour hundred eighteen medically documented monozygotic (MZ) and 380 same‐sex dizygotic (DZ) pairs were ascertained from 1980 to 1992 and followed. The study population was representative of twins with multiple sclerosis. Twins from Canada and adjacent US states (at or above 41–42° N) were considered “northern,” and ancestry was dichotomized from descent from high‐risk populations. Diagnosis before median age 29.3 years was considered “early.”ResultsThe MZ/DZ concordance ratio was 2.9 (95% confidence interval [CI], 1.0–8.9) among men and 2.6 (95% CI, 1.5–4.5) among women. The average age at northern diagnosis was independent of ancestry and 2 years earlier for both MZ (p < 0.02) and DZ (p < 0.01) patients. Among DZ twins, concordance was independent of all characteristics. Among MZ twins, concordance was 1.9 times (95% CI, 1.2–3.2) greater among northern twins, 1.9 (95% CI, 1.1–3.6) times greater among twins with high‐risk ancestry, and 2.1 (95% CI, 1.2–3.6) times greater if diagnosis was early. Ancestry and early diagnosis made independent significant contributions to the differential concordance by latitude.InterpretationMultiple sclerosis is similarly heritable by sex, and the apparent variation in MZ concordance by latitude is influenced by environmental and genetic factors. Ann Neurol 2006
Documents and queries as random variables: History and implications
Authors: Bodoff David , Wong Samuel Po‐Shing 
Published: May 2006

AbstractThe view of documents and/or queries as random variables is gaining importance in the theory of information retrieval. We argue that traditional probabilistic models consider documents and queries as random variables, but that newer models such as language modeling and our unified model take this one step further. The additional step is called error in predictors. Such models consider that we don't observe the document and query random variables that are modeled to predict relevance probabilistically. Rather, there are additional random variables, which are the observed documents and queries. We discuss some important implications of this idea for parameter estimation, relevance prediction, and even test‐collection construction. By clarifying the positions of various probabilistic models on this question, and presenting in one place many of its implications, this article aims to deepen our common understanding of the theories behind traditional probabilistic models, and to strengthen the theoretical basis for further development of more recent approaches such as language modeling.
Genomic DNA of leukemic patients: Target for clinical diagnosis of MLL rearrangements
Authors: Meyer Claus , Kowarz Eric , Schneider Björn , Oehm Clarissa , Klingebiel Thomas , Dingermann Theo , Marschalek Rolf 
Published: May 2006

AbstractGenomic DNA is the optimal resource to analyze questions concerning genetic changes that are related to oncogenesis. This article tries to summarize recent efforts to analyze chromosomal changes that trigger the development of human acute myeloid and lymphoblastic leukemias. The aim of this study was to establish an universal method that enables the identification and characterization of chromosomal translocations of the human MLL gene at the genomic nucleotide level. Chromosomal translocations of the MLL gene are the result of illegitimate recombination events in hematopoietic stem or precursor cells, strictly associated with the onset of highly malignant leukemic diseases. The applied technology was able to identify specific fusion alleles that were generated by chromosomal translocations, chromosomal deletions, chromosomal inversions and partial tandem duplications. Moreover, it allowed us to investigate even highly complex genetic changes by applying systematic breakpoint analyses. On the basis of these analyses, patient‐specific molecular markers were established that turned out to be a very good source for monitoring minimal residual disease (MRD). MRD analyses control the efficiency and efficacy of current treatment protocols and have become a very sensitive molecular tool to monitor therapeutic success or failure in individual leukemia patients.
Measurement of two caspase activities simultaneously in living cells by a novel dual FRET fluorescent indicator probe
Authors: Wu Xiaoli , Simone James , Hewgill Derek , Siegel Richard , Lipsky Peter E. , He Liusheng 
Published: May 2006

AbstractBackground:A number of fluorescent caspase substrates and FRET‐based indicators have been developed to study the in vivo activation of caspases, a conserved family of proteases critical in inflammatory, and apoptosis signaling pathways. To date, all substrates have measured only one caspase activity. Here, we describe a FRET‐based probe for simultaneously measuring two distinct caspase activities in living cells.Methods:This probe consists of a CFP‐YFP‐mRFP fusion protein containing a caspase‐3‐cleavage motif, DEVD, between CFP and YFP, and a caspase‐6‐cleavage site, VEID, between YFP and mRFP. DEVDase and VEIDase activities could be assessed simultaneously by monitoring diminished FRET mediated by cleavage of either or both of these protease cleavage sites using flow cytometry.Results:DEVDase and VEIDase activities were completely inhibited by the pan‐caspase inhibitor z‐VAD‐fmk and enhanced by DNA‐damaging drugs or by anti‐Fas stimulation. DEVD and VEID cleavage specificities were validated by using caspase‐3‐deficient MCF7‐Fas cells and a caspase‐6‐specific inhibitor. Kinetic analysis with the FRET probe revealed that caspase‐3 activation consistently preceded caspase‐6 by ∼30 min following induction of apoptosis.Conclusions:We have developed a novel FRET‐based probe for simultaneous detection of two caspase activities in living cells using flow cytometry. Simultaneous detection of two caspase activities using this probe has clearly provided information of the ordering of caspase‐3 and ‐6 in the apoptotic pathway. © 2006 International Society for Analytical Cytology
A Theoretical Rationale for the Formation, Structure and Spin State of Pentacyanochromate(II)
Authors: Deeth Robert J. 
Published: May 2006

AbstractThe pentacyanochromate(II) complex is unusual in two respects. Firstly, it is one of the few homoleptic cyanide species with a high‐spin ground state. Secondly, it was synthesised during an attempt to make the hexacoordinate complex. A combination of qualitative ligand field theory and quantitative density functional theory including solvation effects is applied to rationalise these observations. The spin state depends on the d orbital energy differences and how the promotion energy, PE, associated with a change in spin state compares to the d–d spin pairing energy, SPE. The calculations show that PE > SPE for octahedral [CrII(CN)6]4–, hence it has a spin triplet S = 1 ground state, while PE < SPE for [CrII(CN)5]3–, hence it is high spin with S = 2. The hexacyanide is stabilised in aqueous solution by solvation. In less polar solvents such as acetonitrile, the unfavourable electrostatic interactions dominate and the reaction stops at the pentacyano complex. In both complexes, the cyanide behaves as a strong‐field ligand and is both a good σ donor and π acceptor.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Asymmetric Mannich‐Type Reaction of a Chiral N‐(tert‐Butylsulfinyl) Ketimine with Imines: Application to the Synthesis of Chiral 1,3‐Diamines
Authors: Zhao Cui‐Hua , Liu Li , Wang Dong , Chen Yong‐Jun 
Published: May 2006

AbstractDeprotonation of the chiral N‐(tert‐butylsulfinyl) ketimine 1 followed by trapping with imines 2 afforded the β‐aminoimines 3 as the Mannich‐type products in high diastereoselectivities (99:1 dr). As versatile synthons chiral β‐amino imines 3 could be transformed into enantiomeric β‐amino ketone and chiral syn‐ or anti‐1,3‐diamines with high diastereomeric excess by hydrolysis or reduction, respectively. Moreover, the nucleophilic addition of organometallicreagents to chiral β‐amino imines 3 could provide 1,1,3‐trisubstituted 1,3‐diamines with high diastereoselectivities. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Joint data detection and estimation of time‐varying multipath rayleigh fading channels in asynchronous DS‐CDMA systems with long spreading sequences
Authors: Xiao Pei , Ström Erik G. 
Published: May 2006

AbstractIn this paper, we present a joint approach to data detection and channel estimation for the asynchronous direct‐sequence code‐division multiple access (DS‐CDMA) systems employing orthogonal signaling formats and long scrambling codes. Our emphasis is placed on different channel estimation algorithms since the performance of a communication system depends largely on its ability to retrieve an accurate measurement of the underlying channel. We investigate channel estimation algorithms under different conditions. The estimated channel information is used to enable coherent data detection to combat the detrimental effect of the multiuser interference and the multipath propagation of the transmitted signal. In the considered multiuser detector, we mainly use interference cancellation techniques, which are suitable for long‐code CDMA systems. Interference cancellation and channel estimation using soft estimates of the transmitted signal is also proposed in this paper. Different channel estimation schemes are evaluated and compared in terms of mean square error (MSE) of channel estimation and bit error rate (BER) performance. Based on our analysis and numerical results, some recommendations are made on how to choose appropriate channel estimators in practical systems. Copyright © 2006 AEIT
Distribution and magnitude of type I error of model‐based multipoint lod scores: implications for multipoint mod scores
Authors: Xing Chao , Elston Robert C. 
Published: May 2006

AbstractThe multipoint lod score and mod score methods have been advocated for their superior power in detecting linkage. However, little has been done to determine the distribution of multipoint lod scores or to examine the properties of mod scores. In this paper we study the distribution of multipoint lod scores both analytically and by simulation. We also study by simulation the distribution of maximum multipoint lod scores when maximized over different penetrance models. The multipoint lod score is approximately normally distributed with mean and variance that depend on marker informativity, marker density, specified genetic model, number of pedigrees, pedigree structure, and pattern of affection status. When the multipoint lod scores are maximized over a set of assumed penetrances models, an excess of false positive indications of linkage appear under dominant analysis models with low penetrances and under recessive analysis models with high penetrances. Therefore, caution should be taken in interpreting results when employing multipoint lod score and mod score approaches, in particular when inferring the level of linkage significance and the mode of inheritance of a trait. Genet. Epidemiol. 2006. © 2006 Wiley‐Liss, Inc.
Progressive increase of frontostriatal brain activation from childhood to adulthood during event‐related tasks of cognitive control
Authors: Rubia Katya , Smith Anna B. , Woolley James , Nosarti Chiara , Heyman Isobel , Taylor Eric , Brammer Mick 
Published: May 2006

AbstractHigher cognitive inhibitory and attention functions have been shown to develop throughout adolescence, presumably concurrent with anatomical brain maturational changes. The relatively scarce developmental functional imaging literature on cognitive control, however, has been inconsistent with respect to the neurofunctional substrates of this cognitive development, finding either increased or decreased executive prefrontal function in the progression from childhood to adulthood. Such inconsistencies may be due to small subject numbers or confounds from age‐related performance differences in block design functional MRI (fMRI). In this study, rapid, randomized, mixed‐trial event‐related fMRI was used to investigate developmental differences of the neural networks mediating a range of motor and cognitive inhibition functions in a sizeable number of adolescents and adults. Functional brain activation was compared between adolescents and adults during three different executive tasks measuring selective motor response inhibition (Go/no‐go task), cognitive interference inhibition (Simon task), and attentional set shifting (Switch task). Adults compared with children showed increased brain activation in task‐specific frontostriatal networks, including right orbital and mesial prefrontal cortex and caudate during the Go/no‐go task, right mesial and inferior prefrontal cortex, parietal lobe, and putamen during the Switch task and left dorsolateral and inferior frontotemporoparietal regions and putamen during the Simon task. Whole‐brain regression analyses with age across all subjects showed progressive age‐related changes in similar and extended clusters of task‐specific frontostriatal, frontotemporal, and frontoparietal networks. The findings suggest progressive maturation of task‐specific frontostriatal and frontocortical networks for cognitive control functions in the transition from childhood to mid‐adulthood. Hum Brain Mapp, 2006. © 2006 Wiley‐Liss, Inc.
Synthesis of new pterocarpans and rapid O‐alkylation under microwave irradiation
Authors: Evangelista E. A. , Couri M. R. C. , Raslan D. S. , Alves R. B. 
Published: May 2006

AbstractHerein, it is described five new pterocarpans. Pterocarpans 8 and 9 were synthesized by classical [3 + 2] cycloaddition reaction of 2H‐chromene 7a and 7b with 2‐methoxy‐1,4‐benzoquinone. Pterocarpan 8 was O‐alkylated in the absence of solvents using a domestic microwave oven as a heat source and a classical O‐alkylation method with traditional heating. In this way three more new pterocarpans were obtained. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:239–244, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20175
Synthesis of new bridgehead heterocycles: Pyrimido[3′,2′:3,4]‐1,2,4‐triazino[5,6‐b]indoles
Authors: Bhagat Sunita , Jain Manish , Pandey Mukesh K. , Pragati  , Saxena Anjali , Jain Subhash C. 
Published: May 2006

AbstractA new bridgehead nitrogen hetero‐ cycle viz. 11‐carboethoxy‐9‐oxo‐pyrimido[3′2′:3,4]‐1,2,4‐triazino[5,6‐b]indole 3 has been synthesized from 3‐azido‐5H‐1,2,4‐triazino[5,6‐b]indole 2 by its reaction with diethyl fumerate. The intermediate 2 was obtained by treating 3‐hydrazino‐5H‐1,2,4‐triazino[5,6‐b]indole with NaNO2 in presence of polyphosphoric acid. A plausible mechanism for the formation of 3 has been formulated and discussed. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:272–276, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20199
Highly functionalized dihydrofuran derivatives: Synthesis by diastereoselective intramolecular Wittig reaction
Authors: Azizian Javad , Karimi Ali Reza , Soleimani Ebrahim , Mohammadi Ali A. , Mohammadizadeh Mohammad R. 
Published: May 2006

Abstract3a,8a‐Dihydroxy‐1,3,3a,8a‐tetrahydro‐ indeno[1,2‐d]imidazole‐2,8‐dione 3 reacts with dialkyl acetylenedicarboxylates in the presence of triphenylphosphine to produce some novel interesting dihydrofuran derivatives diastereoselectively. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:277–279, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20202
Utilization of α‐halocarbonyl compounds in the synthesis of thiazole, thiadiazole, and thiophene derivatives
Authors: Abdel‐latif Ehab , Bondock Samir 
Published: May 2006

AbstractThe behavior of ethyl 2‐phenylthiocarb‐ amoyl acetate 1 toward a variety of several α‐halo‐ carbonyl compounds was investigated. Thus, reaction of 1 with α‐bromoketones, hydrazonoyl bromides, and 2‐chloro‐N‐arylacetamides afforded the corresponding dihydrothiazole, 1,3,4‐thiadiazole, and thiophene derivatives, respectively. The synthesis of thiazolidin‐4‐one 11, thiazolidin‐5‐one 12, and some azo derivatives of thiazolidin‐5‐one were described. 5‐Arylazothiazoles 17 and 19 were synthesized by condensation of hydrazonoyl bromides 3 with different thiourea derivatives. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:299–305, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20206
Synthesis of N‐lactosylated thiourea and benzothiazolyl thiourea
Authors: Tale Prashant V. , Deshmukh Shirish P. 
Published: May 2006

AbstractSeveral N‐lactosylated aryl thioureas and benzothiazolyl thioureas have been prepared by the condensation of hepta‐O‐acetyl‐β‐D‐lactosyl isothiocyanate with aryl amines and 2‐aminobenzothiazole/substituted benzothiazoles. Hepta‐O‐acetyl‐β‐D‐lactosyl isothiocyanate was prepared by the interaction of hepta‐O‐acetyl‐α‐D‐lactosyl bromide and lead thiocyanate. The structures of these new N‐lactosides have been established on the basis of IR, NMR, and mass spectral studies. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:306–309, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20207
Chiral activated alkenes induced asymmetric Baylis–Hillman reaction in Me3N/H2O/solvent medium
Authors: He Ke , Zhou Zhenghong , Zhao Guofeng , Tang Chuchi 
Published: May 2006

AbstractChiral‐activated alkenes, L‐menthyl acrylate and (+)‐N‐α‐phenylethyl acrylamide, induced asymmetric Baylis–Hillman reaction of aromatic aldehydes was realized at 25°C for 7 days in Me3N/H2O/solvent homogeneous medium. The corresponding Baylis–Hillman adducts were obtained in good chemical yield with moderate to excellent diastereoselectivity (up to 99% de). © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:317–321, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20209
Maternal anxiety at amniocentesis and plasma cortisol
Authors: Sarkar P. , Bergman K. , Fisk N.M. , Glover V. 
Published: May 2006

AbstractObjectivesTo assess whether anticipation of amniocentesis is linked with maternal anxiety, and whether this anxiety is associated with increased maternal plasma cortisol.MethodsTwo hundred and fifty‐four women awaiting a morning amniocentesis for karyotyping (gestation range 15–37 weeks, median 17 weeks) completed Spielberger state and trait anxiety inventory (STAI) questionnaires, and provided blood samples immediately before the procedure for cortisol assay. Six hundred and five women at mean gestation of 20 weeks, attending the same hospital for routine ultrasound but not for amniocentesis, also completed Spielberger STAI questionnaires and served as a comparison group for the anxiety ratings.ResultsMean state and trait anxiety scores (± SD) in the comparison group of 605 women at mean gestation of 20 weeks were 36.1 ± 10.2 (range 20–70) and 35.6 ± 8.9 (range 20–73), respectively. The mean state anxiety score (±SD) of 49.8 ± 14.0 (range 20–77) of the amniocentesis group was considerably higher than the comparison group (p < 0.001), although the mean trait anxiety score in the amniocentesis group was similar at 36.4 ± 8.6 (range 21–60). The state, but not trait, anxiety correlated with plasma cortisol (r = 0.176, p = 0.005). Maternal cortisol in the amniocentesis group increased with gestational age (r = 0.310, p < 0.001), whereas state anxiety scores showed no significant change with increase in gestational age (r = − 0.042, ns). Multivariate analysis demonstrated that maternal state anxiety was positively correlated with plasma cortisol independent of gestation and time of collection.ConclusionWomen awaiting amniocentesis experience a high state anxiety associated with modestly increased plasma cortisol. Copyright © 2006 John Wiley & Sons, Ltd.
Theoretical study of cation doping effect on the electronic conductivity of Li4Ti5O12
Authors: Liu Daotan , Ouyang Chuying , Shu Jie , Jiang Jun , Wang Zhaoxiang , Chen Liquan 
Published: May 2006

AbstractThe electronic band structures of pristine and Cr‐, Fe‐, Ni‐ or Mg‐doped Li4Ti5O12 have been calculated by first‐principles local‐density calculations. Analysis is carried out for the band gaps and density of states of these materials. It is shown that Cr or Mg doping can improve the electronic conduction of Li4Ti5O12, but Ni or Fe doping does not have such an effect. The mechanism for the improved electronic conduction is also proposed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two‐dimensional electron gas in cubic Alx Ga1–xN/GaN heterostructures
Authors: Potthast S. , Schörmann J. , Fernandez J. , As D. J. , Lischka K. , Nagasawa H. , Abe M. 
Published: May 2006

AbstractWe report on the optical and electrical properties of cubic AlxGa1–xN/GaN heterostructures. The optical properties were investigated by photoluminescence measurements. A luminescence band at 3.250 eV was observed with our cubic AlxGa1–xN/GaN heterostructures. The emission lies between the excitonic emission of c‐GaN at 3.276 eV and the donor‐acceptor transition at about 3.135 eV. With increasing excitation power we find a characteristic blue shift of 4.5 meV/decade. To confirm the existence of a two‐dimensional electron gas the transition energy versus externally applied voltage has been investigated. A 1.3 meV/V shift was measured and quantitatively verified by a self consistent solution of the Schrödinger and Poisson equation. The electrical properties were determined by capacity‐voltage (CV)‐measurements. The measured carrier profile is in excellent agreement with theoretical simulations and showed a sheet carrier concentration up to n = 1.6 × 1012 cm–2 at the AlxGa1–xN/GaN interface. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)