bluuebunny/crossref_metadata_2025_split huggingface dataset:
Asymmetric Synthesis of the C(17)–C(28) Subunit of Didemnaketal B
Authors: Li Xue‐Qiang , He Qin , Tu Yong‐Qiang , Zhang Fu‐Min , Zhang Shu‐Yu 
Published: September 2007

AbstractThe stereocontrolled synthesis of the C(17)–C(28) fragment 3 of didemnaketal B was accomplished in 21 steps from the natural (R)‐(+)‐pulegone and (S)‐(−)‐citronellal. The key steps involved diastereoselective construction of two chiral carbon centers through the intramolecular chiral induction and uncommon Julia olefination of ketone forming the E‐trisubstituted C(22)–C(23) double bound.
Single Crystalline SnO Nanosheets as Anode Material for Lithium Secondary Battery
Authors: Pei Yan , Wang Shuai , Zhou Qin , Xie Song‐Hai , Qiao Ming‐Hua , Jiang Zhi‐Yu , Fan Kang‐Nian 
Published: September 2007

AbstractSingle crystalline SnO nanosheets with high aspect ratios have been synthesized by a simple solution‐based chemical route aided with sonication. The dimension and thickness of the SnO nanosheets are controllable by adjusting the amount of cetyltrimethyl ammonium bromide (CTAB) added. The as‐prepared SnO nanosheets have loosely packed {001} surfaces and expanded lattice, thus rendering a high reversible capacity approaching the theoretical value of SnO as anode material in Li secondary battery.
Designed Amyloid β Peptide Fibril—A Tool for High‐Throughput Screening of Fibril Inhibitors
Authors: Dolphin Gunnar T. , Ouberai Myriam , Dumy Pascal , Garcia Julian 
Published: September 2007

AbstractAmyloid β peptide (Aβ) fibril formation is widely believed to be the causative event of Alzheimer’s disease pathogenesis. Therapeutic approaches are therefore in development that target various sites in the production and aggregation of Aβ. Herein we present a high‐throughput screening tool to generate novel hit compounds that block Aβ fibril formation. This tool is an application for our fibril model (Aβ16–37Y20K22K24)4, which is a covalent assembly of four Aβ fragments. With this tool, screening studies are complete within one hour, as opposed to days with native Aβ1–40. A Z′ factor of 0.84±0.03 was determined for fibril formation and inhibition, followed by the reporter molecule thioflavin T. Herein we also describe the analysis of a broad range of reported inhibitors and non‐inhibitors of Aβ fibril formation to test the validity of the system.
Virtual Screening for Selective Allosteric mGluR1 Antagonists and Structure–Activity Relationship Investigations for Coumarine Derivatives
Authors: Noeske Tobias , Jirgensons Aigars , Starchenkovs Igors , Renner Steffen , Jaunzeme Ieva , Trifanova Dina , Hechenberger Mirko , Bauer Tanja , Kauss Valerjans , Parsons Christopher G. , Schneider Gisbert , Weil Tanja 
Published: September 2007

AbstractA virtual screening study towards novel noncompetitive antagonists of the metabotropic glutamate receptor 1 (mGluR1) is described. Alignment‐free topological pharmacophore descriptors (CATS) were used to encode the screening compounds. All virtual hits were characterized with respect to their allosteric antagonistic effect on mGluR1 in both functional and binding assays. Exceptionally high hit rates of up to 26 % were achieved, confirming the applicability of this virtual screening concept. Most of the compounds were found to be moderately active, however, one potent and subtype selective mGluR1 antagonist, 13 (IC50: 0.362 μM, SEM ±0.031; Ki: 0.753 μM, SEM ±0.048), based on a coumarine scaffold was discovered. In a following activity optimization program a series of coumarine derivatives was synthesized. This led to the discovery of potent (60, IC50: 0.058 μM, SEM ±0.008; Ki: 0.293 μM, SEM ±0.022) and subtype selective (rmGluR5 IC50: 28.6 μM) mGluR1 antagonists. From our homology model of mGluR1 we derived a potential binding mode within the allosteric transmembrane region. Potential interacting patterns are proposed considering the difference of the binding pockets between rat and human receptors. The study demonstrates the applicability of ligand‐based virtual screening for noncompetitive antagonists of a G‐protein coupled receptor, resulting in novel, potent, and selective agents.
Racial disparities in breast cancer outcome
Authors: Demicheli Romano , Retsky Michael W. , Hrushesky William J. M. , Baum Michael , Gukas Isaac D. , Jatoi Ismail 
Published: September 2007

AbstractSince the 1970s, overall age‐adjusted breast cancer mortality rates in the U.S. have been higher among African American (AA) women than among Caucasian American (CA) women. The racial disparity is not fully explainable based on socioeconomic factors. Suspected biologic factors underlying this trend may be interpreted by both epidemiologic and clinical perspectives. Descriptive epidemiologic studies suggest that breast cancer may be a mixture of at least 2 main diseases and/or causal pathways. The first breast cancer is early‐onset, with peak incidence near age 50 years and generally more aggressive outcome. The second breast cancer is late‐onset, with peak incidence near age 70 years and more indolent course. The early‐onset type of breast cancer is overrepresented among AA women compared with CA women. Clinical studies suggest that the course of breast cancer may be characterized by a common pathway through sequential dormant and active states eventually resulting in clustered appearance of clinical metastases. A balance between tumor and host traits influences the pace of the common pathway. Therefore, the recurrence risk profile of a single patient is seemingly determined by a specific mix of hierarchical prognostic factors, resulting from the unique genetic, environmental, or behavioral traits of that individual, which may be affected by race‐related factors. We suggest that the components of the AA versus CA disparity not attributable to socioeconomic factors are a particular case of the more general issue of host‐tumor interaction and that epidemiologic and clinical views are complementary; each is observing biologic parameters, which are not completely captured by the other. A ‘unifying hypothesis’ incorporating findings from genetics, epidemiology, and clinical studies should be aggressively pursued. Cancer 2007. © 2007 American Cancer Society.
Race, biochemical disease recurrence, and prostate–specific antigen doubling time after radical prostatectomy
Authors: Hamilton Robert J. , Aronson William J. , Presti Joseph C. , Terris Martha K. , Kane Christopher J. , Amling Christopher L. , Freedland Stephen J. 
Published: September 2007

AbstractBACKGROUND.Whether black men are at increased risk for biochemical disease recurrence after radical prostatectomy (RP) is debatable. Once black men have developed disease recurrence, it is unknown whether they have more aggressive disease than white men. To address this issue, the authors examined racial differences in pathologic features, time to disease recurrence, and prostate–specific antigen (PSA) doubling time (PSADT) among a cohort of patients treated with RP.METHODS.The authors analyzed 953 white and 659 black men who were treated at 5 medical centers comprising the Shared Equal Access Regional Cancer Hospital (SEARCH) Database between 1988 and 2006. The association between race, adverse pathologic features, and biochemical disease recurrence was examined. Among those patients who developed disease recurrence, time to recurrence and PSADT were compared between the races.RESULTS.Black men were on average 2.1 years younger (P < .001) and had higher median preoperative PSA levels (7.6 ng/mL vs 7.0 ng/mL; P < .001), yet presented with a lower clinical stage of disease (T1: 62% vs 44%; P < .001) and similar biopsy Gleason scores (P = .59). After adjusting for multiple clinical characteristics, black men were found to be as likely as white men to have adverse pathologic features (Gleason score ≥7, positive surgical margins, and seminal vesicle invasion) in the RP specimen and were less likely to have extracapsular extension (P = .03). Black men were more likely to have a biochemical disease recurrence (hazards ratio [HR] of 1.28; 95% confidence interval [95% CI, 1.07–1.54 [P = .006]). This increased risk was reduced slightly after adjustment for multiple clinical and pathologic features, and no longer achieved statistical significance (HR of 1.19; 95% CI, 0.97–1.45 [P = .09]). Among men who developed disease recurrence, the median PSADT was found to be similar among black men (17.0 months) and white men (14.6 months) (P = .26).CONCLUSIONS.Despite presenting with earlier clinical stage and similar pathologic features at RP, black men were found to be at a slightly increased risk for biochemical disease recurrence. However, these recurrences appear to be no more aggressive than those found in white men. Cancer 2007;110:2202–9. © 2007 American Cancer Society.
Dipeptide Structure Determination by Vibrational Circular Dichroism Combined with Quantum Chemistry Calculations
Authors: Lee Kyung‐Koo , Oh Kwang‐Im , Lee Hochan , Joo Cheonik , Han Hogyu , Cho Minhaeng 
Published: September 2007

AbstractThe solution structure and the local solvation environments of alanine dipeptide (AD, 1 a) and its isotopomer (AD*, 1 b, 13C on the acetyl end CO) are studied by using infrared (IR) spectroscopy and vibrational circular dichroism (VCD). From the amide I IR spectra of AD* in various protic solvents, it is found that each of the two carbonyl groups is fully H‐bonded to two water molecules. However, the number of alcohol molecules H‐bonded to each CO varies from one to two, and the local solvation environments are asymmetric around the two peptides of AD* in alcohol solutions. The amide I VCD spectra of AD and AD* in D2O are also measured, and a series of density functional theory (DFT, B3LYP/6‐311++G**) calculations are performed to obtain the amide I normal‐mode rotational strengths of AD and the intrinsic rotational strengths of its two peptide fragments. By combining the VCD‐measurement and DFT‐calculation results and employing a coupled oscillator theory, we show that the aqueous‐solution structure of the dipeptide can be determined. We believe that the present method will be of use in building up a library of dipeptide solution structures in water.
Spectral analysis and design approach for high force‐to‐volume extrusion damper‐based structural energy dissipation
Authors: Rodgers Geoffrey W. , Mander John B. , Chase J. Geoffrey , Dhakal Rajesh P. , Leach Nicholas C. , Denmead Caleb S. 
Published: September 2007

AbstractHigh force‐to‐volume extrusion damping devices can offer significant energy dissipation directly in structural connections and significantly reduce seismic response. Realistic force levels up to 400 kN have been obtained experimentally validating this overall concept. This paper develops spectral‐based design equations for their application. Response spectra analysis for multiple, probabilistically scaled earthquake suites are used to delineate the response reductions due to added extrusion damping. Representative statistics and damping reduction factors are utilized to characterize the modified response in a form suitable for current performance‐based design methods. Multiple equation regression analysis is used to characterize reduction factors in the constant acceleration, constant velocity, and constant displacement regions of the response spectra.With peak device forces of 10% of structural weight, peak damping reduction factors in the constant displacement region of the spectra are approximately 6.5 ×, 4.0 ×, and 2.8 × for the low, medium, and high suites, respectively. At T = 1 s, these values are approximately 3.6 ×, 1.8 ×, and 1.4 ×, respectively. The maximum systematic bias introduced by using empirical equations to approximate damping reduction factors in design analyses is within the range of +10 to −20%. The seismic demand spectrum approach is shown to be conservative across a majority of the spectrum, except for large added damping between T = 0.8 and 3.5 s, where it slightly underestimates the demand up to a maximum of approximately 10%. Overall, the analysis shows that these devices have significant potential to reduce seismic response and damage at validated prototype device force levels. Copyright © 2007 John Wiley & Sons, Ltd.
Seismic isolation by rubber–soil mixtures for developing countries
Authors: Tsang Hing‐Ho 
Published: September 2007

AbstractThis paper proposes a promising seismic isolation method particularly suitable for developing countries, which makes use of rubber–soil mixtures. Apart from reducing the level of shaking in the horizontal direction, the distinctive advantage of the proposed method is that it can also significantly reduce the shaking level of vertical ground motion, to which an increasing attention has been paid in the earthquake engineering community. On the other hand, the use of scrap tires as the rubber material can provide an alternative way to consume the huge stockpile of scrap tires all over the world. Moreover, the low cost of this proposed seismic protection scheme can greatly benefit those developing countries where resources and technology are not adequate for earthquake mitigation with well‐developed, yet expensive, techniques. The proposed method has been demonstrated through a series of numerical simulations and a parametric study has also been carried out. Lastly, five important issues regarding the concept and feasibility have been discussed. Copyright © 2007 John Wiley & Sons, Ltd.
The effect of temperature and ventilation condition on the toxic product yields from burning polymers
Authors: Stec A. A. , Hull T. R. , Lebek K. , Purser J. A. , Purser D. A. 
Published: September 2007

AbstractA major cause of death or permanent injury in fires is inhalation of toxic gases. Moreover, every fire is unique, and the range of products, highly dependant on fire conditions, produces a wide variety of toxic and irritant species responsible for the most fire fatalities. Therefore, to fully understand each contribution to the toxicity it is necessary to quantify the decomposition products of the material under the test.Fires can be divided into a number of stages from smouldering combustion to early well‐ventilated flaming through to fully developed under‐ventilated flaming. These stages can be replicated by certain bench‐scale physical fire models using different fuel‐to‐oxygen ratios, controlled by the primary air flow, and expressed in terms of the equivalence ratio (the actual fuel/air ratio divided by the stoichiometric fuel/air ratio).This work presents combustion product yields generated using a small‐scale fire model. The Purser Furnace apparatus (BS7990 and ISO TS 19700) enables different fire stages to be created. Identification and quantification of combustion gases and particularly their toxic components from different fire scenarios were undertaken by continuous Fourier transform infrared spectroscopy. The relationship between type of the fire particularly the temperature and ventilation conditions and the toxic product yields for four bulk polymers, low‐density polyethylene, polystyrene (PS), Nylon 6.6 and polyvinyl chloride (PVC) is reported.For all the polymers tested, except PVC, there is a dramatic increase in the yield of products of incomplete combustion (CO and hydrocarbons) with increase in equivalence ratio, as might be expected. For PVC there is a consistently high level of products of incomplete combustion arising both from flame inhibition by HCl and oxygen depletion. There is a low sensitivity to furnace temperature over the range 650–850°C, except that at 650°C PS shows an unexpectedly high yield of CO under well‐ventilated conditions and PVC shows a slightly higher hydrocarbon yield. This demonstrates the dependence of toxic product yields on the equivalence ratio, and the lack of dependence on furnace temperature, within this range. Copyright © 2007 John Wiley & Sons, Ltd.
Role of Kir4.1 channels in growth control of glia
Authors: Higashimori Haruki , Sontheimer Harald 
Published: September 2007

AbstractThe inwardly rectifying potassium channel Kir4.1 is widely expressed by astrocytes throughout the brain. Kir4.1 channels are absent in immature, proliferating glial cells. The progressive expression of Kir4.1 correlates with astrocyte differentiation and is characterized by the establishment of a negative membrane potential (> −70 mV) and an exit from the cell cycle. Despite some correlative evidence, a mechanistic interdependence between Kir4.1 expression, membrane hyperpolarization, and control of cell proliferation has not been demonstrated. To address this question, we used astrocyte‐derived tumors (glioma) that lack functional Kir4.1 channels, and generated two glioma cell lines that stably express either AcGFP‐tagged Kir4.1 channels or AcGFP vectors only. Kir4.1 expression confers the same K+ conductance to glioma membranes and a similar responsiveness to changes in [K+]o that characterizes differentiated astrocytes. Kir4.1 expression was sufficient to move the resting potential of gliomas from −50 to −80 mV. Importantly, Kir4.1 expression impaired cell growth by shifting a significant number of cells from the G2/M phase into the quiescent G0/G1 stage of the cell cycle. Furthermore, these effects could be nullified entirely if Kir4.1 channels were either pharmacologically inhibited by 100 μM BaCl2 or if cells were chronically depolarized by 20 mM KCl to the membrane voltage of growth competent glioma cells. These studies therefore demonstrate directly that Kir4.1 causes a membrane hyperpolarization that is sufficient to account for the growth attenuation, which in turn induces cell maturation characterized by a shift of the cells from G2/M into G0/G1. © 2007 Wiley‐Liss, Inc.
Modafinil and nicotine interactions in abstinent smokers
Authors: Sofuoglu Mehmet , Waters Andrew J. , Mooney Marc 
Published: September 2007

AbstractIn this study, we examined the effects of a wakefulness‐promoting medication, modafinil, alone and with the nicotine lozenge, on subjective, physiological and cognitive measures as well as on nicotine withdrawal in overnight abstinent cigarette smokers. Nineteen smokers, 13 male and 6 female, participated in a double‐blind, placebo‐controlled, crossover study. In each of three experimental sessions, subjects were treated orally with a single 200 mg or 400 mg dose of modafinil or placebo. Two hours and 10 min following the medication treatment, subjects received a single 2 mg nicotine lozenge. Both doses of modafinil alone increased the rating of elated‐depressed on the Profile of Mood States (POMS) subscale in the direction of depressed and increased ratings of negative affect on the Positive and Negative Affect Schedule (PANAS). In contrast, the 200 mg modafinil dose combined with a 2 mg nicotine lozenge, increased the rating of energetic‐tired in the direction of energetic on the POMS subscale. Modafinil attenuated self‐reported rating of ‘drug strength’ in response to the nicotine lozenge. Modafinil, alone or in combination with the nicotine lozenge, did not affect tobacco withdrawal symptoms. There was an increase in baseline heart rate and systolic blood pressure under modafinil treatment. In addition, modafinil speeded reaction times on a modified Stroop task. The clinical utility of modafinil for smoking cessation needs to be determined in future studies. Copyright © 2007 John Wiley & Sons, Ltd.
Loudness dependence of evoked dipole source activity during acute serotonin challenge in females
Authors: Norra Christine , Becker Stefanie , Bröcheler Anno , Kawohl Wolfram , Kunert Hanns Jürgen , Buchner Helmut 
Published: September 2007

AbstractObjectivesDirect challenge of cortical serotonergic (5‐hydroxytryptamine, 5‐HT) availability by tryptophan depletion test (TDT) was used to assess the hypothesized inverse relationship between central 5‐HT function and loudness dependence of auditory evoked potentials (LDAEPs). Gender must be taken into particular account here, since there are gender differences in 5‐HT brain synthesis, with women reacting more strongly to TDT.MethodsIn a double‐blind, controlled cross‐over study, 16 healthy females were ingested two highly concentrated amino acid mixtures with (+TRP) or without TRP (−TRP). While monitoring TRP levels and mood states, the AEP of different loudness stimuli were recorded, followed by dipole source analysis.ResultsUnder the −TRP condition, free plasma TRP levels decreased by 81.10% (±5.14). Most of the loudness change rates of the relevant N1/P2 tangential dipole activities were significantly increased under −TRP, but calculated LDAEP did not differ significantly between treatments. LDAEP and states of mood were not correlated.ConclusionsDespite strong TRP depletion, the results did not reach sufficient evidence that LDAEP is a valid biological marker of central 5‐HT activity in females when using TDT. This agrees with the literature and supports the view that LDAEP indicates predominantly biological vulnerability in predisposed individuals. Copyright © 2007 John Wiley & Sons, Ltd.
Caffeine, sleep and wakefulness: implications of new understanding about withdrawal reversal
Authors: James Jack E. , Keane Michael A. 
Published: September 2007

AbstractThe broad aim of this review is to critically examine the implications of new understanding concerning caffeine withdrawal and withdrawal reversal in the context of research concerned with the effects of caffeine on sleep and wakefulness. A comprehensive search was conducted for relevant experimental studies in the PubMED and PsycINFO databases. Studies were assessed with particular reference to methodological adequacy for controlling against confounding due to caffeine withdrawal and withdrawal reversal. This assessment was used to clarify evidence of effects, highlight areas of ambiguity and derive recommendations for future research. It was found that researchers have generally failed to take account of the fact that habitual use of caffeine, even at moderate levels, leads to physical dependence evidenced by physiological, behavioural and subjective withdrawal effects during periods of abstinence. Consequently, there has been near‐complete absence of adequate methodological controls against confounding due to reversal of withdrawal effects when caffeine is experimentally administered. The findings of what has been a substantial research effort to elucidate the effects of caffeine on sleep and wakefulness, undertaken over a period spanning decades, are ambiguous. Current shortcomings can be redressed by incorporating suitable controls in new experimental designs. Copyright © 2007 John Wiley & Sons, Ltd.