bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction of Aromatic Derivatives with Single‐Walled Carbon Nanotubes
Authors: Hung Wei‐Chun , Elias Gracy , Wai Chien M.
Published: September 2010

Fluorescence of semiconducting single‐walled carbon nanotubes (SWNTs) normally exhibits diameter‐dependent oxidative quenching behaviour. This behaviour can be changed substantially to become an almost diameter‐independent quenching phenomenon in the presence of electron‐withdrawing nitroaromatic compounds, including o‐nitrotoluene, 2,4‐dinitrotoluene, and nitrobenzene. This change is observed for SWNTs suspended either in sodium dodecyl sulfate or in Nafion upon titration with hydrogen peroxide. Benzene, toluene, phenol, and nitromethane do not show such change. These findings suggest the possibility of forming an electron donor–acceptor complex between SWNTs and nitroaromatic compounds, resulting in leveling the redox potential of different SWNT species. The observation appears to provide a new method for modifying the electrochemical potentials of SWNTs through donor–acceptor complex formation.
Hydrothermal Synthesis of a Doped Mn‐Cd‐S Solid Solution as a Visible‐Light‐Driven Photocatalyst for H2 Evolution
Authors: Ikeue Keita , Shiiba Satoshi , Machida Masato
Published: September 2010

The effect of metal doping (i.e., with Cr, Fe, Ni, Cu, Zn, Ag and Sn) on the crystal structure of hydrothermally synthesized Mn1−xCdxS (where x≈0.1) is studied with the aim of enhancing photocatalytic activity. In contrast to the low‐crystalline, undoped solid solution Mn1−xCdxS, Ni doping yields a well‐crystallized wurtzite‐type Mn‐Cd‐S solid solution, which precipitates as planar hexagonal facets of several hundred nanometers in size, together with much larger grains of α‐MnS (>10 μm). By removing inactive α‐MnS through sedimentation, a single phase with composition of Ni0.01Mn0.56Cd0.43S is obtained successfully. The Ni doping achieved a threefold higher photocatalytic activity for H2 evolution from a 0.1 M Na2S/0.5 M Na2SO3 solution under visible‐light irradiation (λ≥420 nm). The apparent quantum yield of 1 wt % Pt‐loaded Ni0.01Mn0.56Cd0.43S measured at λ=420 nm reached 25 %. The enhanced photocatalytic activity is most likely the result of a decreased concentration of defects, responsible for electron–hole recombination, in the active solid‐solution phase and a slightly higher bandgap energy (2.4 eV).
Unified BER and optimum threshold analysis of binary modulations in simple and cascaded Rayleigh fading channels with switched combining
Authors: Chandra Aniruddha , Bose Chayanika , Bose Manas Kr.
Published: September 2010

Following a unified analytical framework, the bit error rate (BER) of several coherent and non‐coherent binary modulation schemes is derived for a switched diversity system. The two variants of switched combining that have been investigated are switch and stay combining and switch and examine combining. For channel modelling, at first a simple slow flat fading channel is assumed, where the amplitude attenuation obeys the Rayleigh distribution. Later the BER calculations are repeated for cascaded Rayleigh fading channel case. Rayleigh fading is the most popular model for electromagnetic signal propagation in wireless media when both or either of the transmitter/receiver is fixed. On the other hand, when both the transmitter and the receiver are mobile, a cascaded (or double) Rayleigh fading model is better suited. The applicability of these two models, namely simple and cascaded Rayleigh model, has been indicated by several theoretical studies and their suitability is established by various field measurements. In our paper, simple closed‐form BER expressions as a function of switching threshold have been found and optimum switching thresholds have been computed for both these models as well as for both types of diversity combining described earlier. The results presented in this paper can be very useful for communication system designers to analyze link quality of switched diversity assisted systems in various wireless environments. Copyright © 2010 John Wiley & Sons, Ltd.
Efficient three‐party password‐based key exchange scheme
Authors: Lou Der‐Chyuan , Huang Hui‐Feng
Published: September 2010

In three‐party password‐based key exchange protocol, a client is allowed to share a human‐memorable password with a trusted server such that two clients can negotiate a session key to communicate with each other secretly. Recently, many three‐party password‐based key exchange protocols have been developed. However, these proposed schemes cannot simultaneously achieve security and efficiency. Based on elliptic curve cryptography (ECC), this paper will propose a new simple three‐party password‐based authenticated key exchange scheme. The proposed method not only reduces computation cost for remote users and a trusted server but also is more efficient than previously proposed schemes. It is better suited for resource constrained devices, such as smart cards or mobile units. Copyright © 2010 John Wiley & Sons, Ltd.
Cooperative power allocation with partial channel information in multi‐cell multi‐user dual‐hop MIMO relay systems
Authors: Cho Hee‐Nam , Lee Jin‐Woo , Lee Yong‐Hwan
Published: September 2010

This paper considers cooperative power allocation with the use of partial channel state information (CSI) in a multi‐user dual‐hop relay system with multiple antennas. The end‐to‐end capacity can be improved by dynamically allocating the transmit power of the base station and relay according to co‐channel interference caused by the adjacent relays. The proposed scheme allocates the transmit power in association with the eigenvalues and angle difference between the eigenvectors of transmit correlation matrices of the desired and interference channel. It is shown by means of upper‐bound analysis that the end‐to‐end capacity of the proposed scheme can be maximized in highly correlated channel environments when the principal eigenvectors of transmit correlation matrices of the desired and interference channel are orthogonal to each other. It is also shown that the proposed scheme is robust to the channel estimation error. Finally, the performance of the proposed scheme is verified by the computer simulation. Copyright © 2010 John Wiley & Sons, Ltd.
Some analysis of call blocking probabilities in hierarchical WDM networks offering multiclass service
Authors: Kuppuswamy Kalyan , Lee Daniel C.
Published: September 2010

We envision a large‐scale multiclass optical network in which lightpaths are dynamically set up and terminated between source and destination nodes and these lightpaths traverse through a number of interconnected WDM networks in different administrative domains. In this envisioned multiclass network, calls are classified by the number of wavelengths demanded per call and the statistics of call holding times (or service subscription periods). We present an approximation method for the performance analysis of such a large‐scale multiclass optical WDM network. We model the large‐scale optical network as a two‐level hierarchical multiclass loss network; the lower level of hierarchy consists of individual optical WDM networks (network segments). Each of these network segments is abstracted to a logical node at the higher level of hierarchy, and these logical nodes are connected to each other through logical links. We also assume that the call processing mechanism in this large‐scale optical network resorts to hierarchical routing. The algorithms presented in this paper computeper‐class end‐to‐end approximate blocking probabilities. Our experiments show that the simulation results match closely with the results of the proposed analytical approximation methods, thus validating the proposed methodology. Copyright © 2010 John Wiley & Sons, Ltd.
Tournament‐based congestion control protocol for multimedia streaming in ubiquitous sensor networks
Authors: Lee Chongdeuk , Jeong TaegWon , Lian Shiguo
Published: September 2010

Congestion in the ubiquitous sensor network occurs when traffic load exceeds available capacity at any point in a network. Congestion causes overall channel quality to degrade and loss rates to rise, leads to buffer drops and increases latencies. Therefore, congestion and latency have effects on energy efficiency, memory size, buffer size, and throughput. This paper proposes a new method, called TCCP (Tournament‐based Congestion Control Protocol), to minimize congestion in the ubiquitous sensor network. In this paper, the winner is the stream with the highest importance level in the competition of ubiquitous sensor network. In general, there are a lot of congestion and delay in the continuous streaming of multimedia streams with lower importance level. The proposed method consists of three parts: tournament decision, best‐fit control strategy and service differentiation. The final winner in the tournament controls congestion effectively, minimizes packet loss due to congestion, decreases energy consumption, and improves QoS. The simulation result shows that the proposed method is more effective and has better performance compared with those of CCF (congestion control and fairness), PCCP (priority based congestion control protocol), and CODA (congestion detection and avoidance). Copyright © 2010 John Wiley & Sons, Ltd.
Downlink multiple access schemes for transmitted reference pulse cluster UWB systems
Authors: Liang Zhonghua , Jin Li , Dong Xiaodai
Published: September 2010

Transmitted reference pulse cluster (TRPC) signaling was recently proposed for low data rate ultra‐wideband communications. Compared with the conventional transmitted reference (TR), TRPC has a more compact and uniform spacing for the reference and data pulses and therefore solves the implementation problem posed by the long delay line requirement in the conventional TR. In this paper, downlink multiple access issue is further investigated for TRPC systems. According to the TRPC signaling structure, both code division multiple access (CDMA) and time division multiple access (TDMA) methods are discussed. Theoretical analysis and simulation results show that TDMA outperforms CDMA in both bit error rate performance and throughput. Copyright © 2010 John Wiley & Sons, Ltd.
Physical activity levels of patients undergoing hemodialysis
Authors: Nakamura Mayumi , Yamabe Hideaki , Kitajima Maiko , Kudo Umi , Urushizaka Mayumi , Tomisawa Toshiko , Itaki Chieko , Kawasaki Kumiko , Noto Yuka , Akaishi Sachiko , Shimada Kimiko
Published: September 2010

BACKGROUND

High levels of physical activity improve the prognosis and quality of life (QOL) for patients undergoing hemodialysis (HD). The aims of this study were to measure physical activity using a pedometer and to explain the relationship between physical activity and clinical outcomes in HD patients.

METHODS

The study population comprised 38 patients (17 men and 21 women; mean age: 56.1 years; range, 41–69 years) who underwent HD 3 days/week. Physical activity was measured with a pedometer. The relationships between the clinical data and levels of physical activity were examined.

RESULTS

The mean number of steps taken per day for 1 week was 4,157.4 ± 2,068.1, and the mean value for all‐consumption calories per day for 1 week was 1,623.0 ± 240.5 kcal. The mean daily value for all‐consumption calories showed positive correlations with basal metabolic calorie and serum creatinine levels, as well as the Physical Functioning score in the Kidney Disease Quality of Life‐Short Form instrument (KDQOL‐SF), whereas it showed negative correlations with the levels of total cholesterol and low‐density lipoprotein (LDL) cholesterol and the cardiothoracic ratio. The mean calorie consumption by action, subtracting basic metabolism calories from all‐consumption calories, also showed positive correlations with the number of steps and the Physical Functioning score in the KDQOL‐SF, while it showed negative correlations with the total cholesterol and LDL cholesterol levels.

CONCLUSIONS

The parameter of all‐consumption calories per day, measured with a pedometer, is useful for evaluating the levels of physical activity of HD patients and for formulating exercise recommendations.
Calciphylaxis—Case report and review of the literature
Authors: Kirschberg Oliver , Saers Thomas , Krakamp Bernd
Published: September 2010

We report on a 78‐year‐old female patient who suffered from end‐stage renal disease (ESRD) and received intermittent hemodialysis for 9 years. In the late progression of ESRD, she developed very painful ulcerations on both legs. The ulcerations were diagnosed as an early stage of calciphylaxis. In line with the high mortality of this disease, she lived only 5 months after initial diagnosis.

Up to now, the pathology of calciphylaxis has been poorly understood. Hence no truly successful treatment regime has been available. Treatment should focus on the patient's pain, a major manifestation of the illness.

This case report looks at a rare and seldom seen illness in patients with end‐stage renal disease.
One‐Pot Stereoselective Double Intramolecular Oxymercuration: Synthesis of Four Isomers of an Unsymmetrical Bis‐Tetrahydrofuran Ring System
Authors: Mohapatra Debendra K. , Naidu P. Ramesh , Reddy D. Srinivas , Nayak Sabita , Mohapatra Seetaram
Published: September 2010

Stereoselective one‐pot double intramolecular oxymercuration has been demonstrated to be the key reaction in the efficient preparation of the mono‐hydroxylated bis‐tetrahydrofuran ring system present in asimitrin and salzmanolin, two naturally occurring biologically active nonclassical acetogenins.
Optimization of the procedure to burn textile fabrics by cone calorimeter: Part I. Combustion behavior of polyester
Authors: Tata Jennifer , Alongi Jenny , Carosio Federico , Frache Alberto
Published: September 2010

The aim of this study was the optimization of cone calorimeter to determine the burning behavior of textile fabrics. In particular, the combustion behavior of commercial polyester textile fabrics with varying densities was studied in terms of time to ignition (TTI), heat release rate (HRR), and relative peak (pkHRR) were monitored. Reproducibility and repeatability of the data have been verified by the influence of instrument variable including incident heat flux, the temperature of ceramic backing pads and retaining grid used during sample mounting as well as sample weight (as the number of fabric layers), the density of textiles, and the relative humidity. A low reproducibility has been obtained when a wire grid was not used to stabilize samples during the tests. The effects of these variables on TTI and pkHRR were observed. Copyright © 2010 John Wiley & Sons, Ltd.
Use of a chewing device to perform a mass balance on chewing gum components
Authors: Krause Andrea J. , Henson Lulu S. , Reineccius Gary A.
Published: September 2010

A mechanical device was fabricated to simulate mastication of chewing gum; this device allowed us to perform a mass balance on the volatiles and non‐volatiles added to chewing gum during simulated mastication. Model volatiles (ethyl butyrate, isoamyl acetate and limonene) released from the gum into the gas phase were quantified using a proton transfer reaction mass spectrometer (PTR‐MS). The chewing device was equipped to simulate salivation (saliva in) and swallowing (saliva out) using water as simulated saliva. The model compounds released into simulated saliva were extracted and quantified using gas chromatography. Sugar alcohols (sorbitol and xylitol) and glycerin were quantified using HPLC‐MS. High‐potency sweeteners (acesulfame‐K, sucralose, rebaudioside A and sodium saccharin) were quantified using UPLC‐MS. The model volatiles initially added to the chewing gum were distributed in two or three fractions: the masticated gum (43–84%); the simulated saliva (ethyl butyrate and isoamyl acetate were recovered from the water at 9–11% and 14–17%, respectively) and the gas phase (ethyl butyrate and isoamyl acetate were recovered from the gas phase at 7–10% and 29–40%, respectively). Limonene could not be detected in the simulated saliva, and >80% remained in the gum after mastication. Almost all (>90%) of the water‐soluble polyols and high‐potency sweeteners were extracted from the gum into the simulated saliva by mastication. Given the presented validation of the device, we feel the device could be used to evaluate and potentially screen and evaluate ingredients in chewing gum formulations. By using a device to circumvent the variability of human subjects, a more consistent and efficient throughput of samples could be achieved.
Nested and parallel sparse algorithms for arterial fluid mechanics computations with boundary layer mesh refinement
Authors: Manguoglu Murat , Takizawa Kenji , Sameh Ahmed H. , Tezduyar Tayfun E.
Published: September 2010

Arterial fluid–structure interaction (FSI) computations involve a number of numerical challenges. Because blood flow is incompressible, iterative solution of the fluid mechanics part of the linear equation system at every nonlinear iteration of each time step is one of those challenges, especially for computations over slender domains and in the presence of boundary layer mesh refinement. In this paper we address that challenge. As test cases, we use equation systems from stabilized finite element computation of a bifurcating middle cerebral artery segment with aneurysm, with thin layers of elements near the arterial wall. We show how the preconditioning techniques, we propose for solving these large sparse nonsymmetric systems, perform at different time steps of the computation over a cardiac cycle. We also present a new hybrid parallel sparse linear system solver ‘DD‐Spike’ and demonstrate its scalability. Copyright © 2010 John Wiley & Sons, Ltd.
A generalized view on Galilean invariance in stabilized compressible flow computations
Authors: Scovazzi G. , Love E.
Published: September 2010

This article presents a generalized analysis on the significance of Galilean invariance in compressible flow computations with stabilized and variational multi‐scale methods. The understanding of the key issues and the development of general approaches to Galilean‐invariant stabilization are facilitated by the use of a matrix‐operator description of Galilean transformations. The analysis of invariance for discontinuity capturing operators is also included. Published in 2010 by John Wiley & Sons, Ltd.
Variable viscosity effects on the peristaltic motion of a third‐order fluid
Authors: Hayat T. , Abbasi F. M.
Published: September 2010

The effect of variable viscosity on the peristaltic motion of MHD third‐order fluid in a channel is studied using slip condition. The series solution for stream function, longitudinal velocity and pressure gradient are first derived and then discussed in detail. The pressure rise and frictional forces are monitored through numerical integration. Copyright © 2010 John Wiley & Sons, Ltd.
Meta‐analysis of genetic association studies and adjustment for multiple testing of correlated SNPs and traits
Authors: Conneely Karen N. , Boehnke Michael
Published: September 2010

Meta‐analysis has become a key component of well‐designed genetic association studies due to the boost in statistical power achieved by combining results across multiple samples of individuals and the need to validate observed associations in independent studies. Meta‐analyses of genetic association studies based on multiple SNPs and traits are subject to the same multiple testing issues as single‐sample studies, but it is often difficult to adjust accurately for the multiple tests. Procedures such as Bonferroni may control the type‐I error rate but will generally provide an overly harsh correction if SNPs or traits are correlated. Depending on study design, availability of individual‐level data, and computational requirements, permutation testing may not be feasible in a meta‐analysis framework. In this article, we present methods for adjusting for multiple correlated tests under several study designs commonly employed in meta‐analyses of genetic association tests. Our methods are applicable to both prospective meta‐analyses in which several samples of individuals are analyzed with the intent to combine results, and retrospective meta‐analyses, in which results from published studies are combined, including situations in which (1) individual‐level data are unavailable, and (2) different sets of SNPs are genotyped in different studies due to random missingness or two‐stage design. We show through simulation that our methods accurately control the rate of type I error and achieve improved power over multiple testing adjustments that do not account for correlation between SNPs or traits. Genet. Epidemiol. 34: 739‐746, 2010. © 2010 Wiley‐Liss, Inc.
CAPL: a novel association test using case‐control and family data and accounting for population stratification
Authors: Chung Ren‐Hua , Schmidt Michael A. , Morris Richard W. , Martin Eden R.
Published: September 2010

The recent successes of GWAS based on large sample sizes motivate combining independent datasets to obtain larger sample sizes and thereby increase statistical power. Analysis methods that can accommodate different study designs, such as family‐based and case‐control designs, are of general interest. However, population stratification can cause spurious association for population‐based association analyses. For family‐based association analysis that infers missing parental genotypes based on the allele frequencies estimated in the entire sample, the parental mating‐type probabilities may not be correctly estimated in the presence of population stratification. Therefore, any approach to combining family and case‐control data should also properly account for population stratification. Although several methods have been proposed to accommodate family‐based and case‐control data, all have restrictions. Most of them require sampling a homogeneous population, which may not be a reasonable assumption for data from a large consortium. One of the methods, FamCC, can account for population stratification and uses nuclear families with arbitrary number of siblings but requires parental genotype data, which are often unavailable for late‐onset diseases. We extended the family‐based test, Association in the Presence of Linkage (APL), to combine family and case‐control data (CAPL). CAPL can accommodate case‐control data and families with multiple affected siblings and missing parents in the presence of population stratification. We used simulations to demonstrate that CAPL is a valid test either in a homogeneous population or in the presence of population stratification. We also showed that CAPL can have more power than other methods that combine family and case‐control data. Genet. Epidemiol. 34:747‐755, 2010.© 2010 Wiley‐Liss, Inc.
The constitutive production of the endocannabinoid 2‐arachidonoylglycerol participates in oligodendrocyte differentiation
Authors: Gomez Oscar , Arevalo‐Martin Angel , Garcia‐Ovejero Daniel , Ortega‐Gutierrez Silvia , Cisneros Jose Antonio , Almazan Guillermina , Sánchez‐Rodriguez María Alejandra , Molina‐Holgado Francisco , Molina‐Holgado Eduardo
Published: September 2010

Endocannabinoids have recently emerged as instructive cues in the developing central nervous system, and, based on the expression of their receptors, we identified oligodendrocytes as potential targets of these molecules. Here, we show that the enzymes responsible for the synthesis of the endocannabinoid 2‐arachidonoylglycerol (2‐AG), diacylglycerol lipase alpha (DAGLα) and beta (DAGLβ), and degradation, monoacylglycerol lipase (MAGL), can be found in oligodendrocytes at different developmental stages. Moreover, cultured oligodendrocyte progenitor cells (OPCs) express DAGLα and β abundantly, resulting in the stronger production of 2‐AG than in differentiated oligodendrocytes. The opposite is observed with MAGL. CB1 and CB2 receptor antagonists (SR141716 and AM630) impaired OPC differentiation into mature oligodendrocytes and likewise, inhibiting DAGL activity with RHC‐80267 or tetrahydrolipstatin also blocked oligodendrocyte maturation, an effect reversed by the addition of exogenous 2‐AG. Likewise, 2‐AG synthesis disruption using specific siRNAs against DAGLα and DAGLβ significantly reduced myelin protein expression in vitro, whereas a pharmacological gain‐of‐function approach by using cannabinoid agonists or MAGL inhibition had the opposite effects. ERK/MAPK pathway is implicated in oligodendrocyte differentiation because PD98059, an inhibitor of MEK1, abrogated oligodendrocyte maturation. The cannabinoid receptor antagonists and RHC‐80267 all diminished basal ERK1/2 phosphorylation, effects that were partially reversed by the addition of 2‐AG. Overall, our data suggest a novel role of endocannabinoids in oligodendrocyte differentiation such that constitutive release of 2‐AG activates cannabinoid receptors in an autocrine/paracrine way in OPCs, stimulating the ERK/MAPK signaling pathway. © 2010 Wiley‐Liss, Inc.
Growth factors upregulate astrocyte [Ca2+]i oscillation by increasing SERCA2b expression
Authors: Morita Mitsuhiro , Kudo Yoshihisa
Published: September 2010

Previously, we reported upregulation of astrocyte [Ca2+]i oscillation by growth factors (i.e., conversion of glutamate‐induced sustained [Ca2+]i increase in astrocytes cultured in a defined medium to [Ca2+]i oscillation by EGF and bFGF treatment over 48 h) (Morita et al., (2003) J Neurosci 23:10944–10952). As our previous study also showed that these growth factors increase intracellular Ca2+ stores, this study was performed to investigate the mechanism underlying loading of intracellular Ca2+ stores in astrocytes, especially sarco‐endoplasmic reticulum Ca2+ ATPase (SERCA), as a candidate mechanism by which growth factors upregulate [Ca2+]i oscillation. The results indicated that the growth factors upregulated a SERCA inhibitor‐sensitive component of [Ca2+]i clearance, and increased expression of the SERCA subtype, SERCA2b. Furthermore, treating the growth factor‐treated astrocytes with a low concentration of SERCA inhibitor to partially inhibit SERCA reduced the level of intracellular Ca2+ storage and reversed glutamate‐induced [Ca2+]i oscillations to sustained [Ca2+]i increases. Thus, the upregulation of [Ca2+]i oscillations was attributed to the upregulation of SERCA activities. These results indicated that these growth factors regulate the pattern of glutamate‐induced astrocyte [Ca2+]i increases via SERCA2b expression. © 2010 Wiley‐Liss, Inc.
Foot pad skin biopsy in mouse models of hereditary neuropathy
Authors: Dacci Patrizia , Dina Giorgia , Cerri Federica , Previtali Stefano Carlo , Lopez Ignazio Diego , Lauria Giuseppe , Feltri Maria Laura , Bolino Alessandra , Comi Giancarlo , Wrabetz Lawrence , Quattrini Angelo
Published: September 2010

Numerous transgenic and knockout mouse models of human hereditary neuropathies have become available over the past decade. We describe a simple, reproducible, and safe biopsy of mouse skin for histopathological evaluation of the peripheral nervous system (PNS) in models of hereditary neuropathies. We compared the diagnostic outcome between sciatic nerve and dermal nerves found in skin biopsy (SB) from the hind foot. A total of five animal models of different Charcot‐Marie‐Tooth neuropathies, and one model of congenital muscular dystrophy associated neuropathy were examined. In wild type mice, dermal nerve fibers were readily identified by immunohistochemistry, light, and electron microscopy and they appeared similar to myelinated fibers in sciatic nerve. In mutant mice, SB manifested myelin abnormalities similar to those observed in sciatic nerves, including hypomyelination, onion bulbs, myelin outfolding, redundant loops, and tomacula. In many strains, however, SB showed additional abnormalities—fiber loss, dense neurofilament packing with lower phosphorylation status, and axonal degeneration—undetected in sciatic nerve, possibly because SB samples distal nerves. SB, a reliable technique to investigate peripheral neuropathies in human beings, is also useful to investigate animal models of hereditary neuropathies. Our data indicate that SB may reveal distal axonal pathology in mouse models and permits sequential follow‐up of the neuropathy in an individual mouse, thereby reducing the number of mice necessary to document pathology of the PNS. © 2010 Wiley‐Liss, Inc.
The P2X7‐Egr pathway regulates nucleotide‐dependent inflammatory gene expression in microglia
Authors: Friedle S. A. , Brautigam V. M. , Nikodemova M. , Wright M. L. , Watters J. J.
Published: September 2010

Microglial hyperactivity contributes to neuronal damage resulting from CNS injury and disease. Therefore, a better understanding of endogenous microglial receptor systems that can be exploited to modulate their inflammatory functions is important if better, neuroprotective therapeutics are to be designed. Previous studies from our lab and others have demonstrated that the P2X7 purinergic receptor agonist BzATP attenuates microglial inflammatory mediator production stimulated by lipopolysaccharide (LPS), suggesting that purinergic receptors may be one such receptor system that can be used for manipulating microglial activation. However, although P2X7 receptor activation is well recognized to regulate processing and release of cytokines, little is known concerning its role in regulating the transcription of inflammatory genes, nor the molecular mechanisms underlying these transcriptional effects. In the present studies, we identify that the transcription factors early growth response (Egr)−1, −2 and −3 are downstream signaling targets of P2X7 receptors in microglia, and that their activation is sensitive to MEK and p38 mitogen‐activated protein kinase (MAPK) inhibitors. Moreover, using RNAi, we demonstrate that Egr factors and P2X7 receptors are necessary for BzATP‐mediated attenuation of iNOS, and stimulation of TNF‐α and IL‐6 gene expression. BzATP also attenuates neuronal death induced by LPS conditioned medium, and P2X7 receptors are required for this effect. These studies are the first to identify Egr factors as regulators of inflammatory gene expression following P2X7 receptor activation, and suggest that P2X7 receptors may utilize the MAPK‐Egr pathway to exert differential effects on microglial inflammatory activities which are beneficial to neuron survival. © 2010 Wiley‐Liss, Inc.
Augmenting antidepressant medication with modular CBT for geriatric generalized anxiety disorder: a pilot study
Authors: Wetherell Julie Loebach , Stoddard Jill A. , White Kamila S. , Kornblith Sander , Nguyen Hoang , Andreescu Carmen , Zisook Sidney , Lenze Eric J.
Published: September 2010

Objective

Generalized anxiety disorder (GAD) is a prevalent psychiatric condition in older adults with deleterious effects on health and cognition. Although selective serotonin reuptake inhibitor (SSRI) medications have some efficacy as acute treatments for geriatric GAD, incomplete response is the most common outcome of monotherapy. We therefore developed a novel sequential treatment strategy, using personalized, modular cognitive‐behavioral therapy (mCBT) to augment SSRI medication.

Method

In an open label pilot study (N = 10), subjects received a sequenced trial of 12 weeks of escitalopram followed by 16 weeks of escitalopram augmented with mCBT. We also examined the maintenance effects of mCBT over a 28‐week follow‐up period following drug discontinuation and termination of psychotherapy.

Results

Results suggest that (1) adding mCBT to escitalopram significantly reduced anxiety symptoms and pathological worry, resulting in full remission for most patients and (2) some patients maintained response after all treatments were withdrawn.

Conclusion

Findings suggest that mCBT may be an effective augmentation strategy when added to SSRI medication and provide limited support for the long‐term benefit of mCBT after discontinuation of pharmacotherapy. Copyright © 2010 John Wiley & Sons, Ltd.
Presence and quality of kindergarten children's friendships: concurrent and longitudinal associations with child adjustment in the early school years
Authors: Engle Jennifer M. , McElwain Nancy L. , Lasky Nicole
Published: September 2010

The presence and quality of friendships are posited to have developmental significance, yet little is known about the extent to which children without friends versus low‐quality friendships compare on socioemotional adjustment. The current study utilized data from a subsample of 567 children (289 boys) participating in the NICHD Study of Early Child Care and Youth Development. Based on maternal reports at kindergarten, four friendship groups were formed: no friends, low quality, average quality, and high quality, and these groups were used to predict teacher‐reported behaviour problems and social skills concurrently (in kindergarten) and longitudinally (in first and third grade). Concurrently, low‐quality friendships were associated with greater externalizing behaviour, whereas high‐quality friendships were associated with greater social skills. Longitudinally, having no friends in kindergarten was associated with higher levels of externalizing behaviour for boys, but lower levels for girls. Children without friends also showed more internalizing problems at first grade. Lastly, having a high‐quality friendship in kindergarten was associated with greater social skills in first and third grades, but only for boys. Results underscore high‐quality friendship as a context for the development of social skills and indicate different trajectories of problem behaviour for kindergarten children with no friends versus low‐quality friendships. Copyright © 2010 John Wiley & Sons, Ltd.
Combining random forest and copula functions: A heuristic approach for selecting assets from a financial crisis perspective
Authors: De Luca Giovanni , Rivieccio Giorgia , Zuccolotto Paola
Published: September 2010

In this paper we propose a heuristic strategy aimed at selecting and analysing a set of financial assets, focusing attention on their multivariate tail dependence structure. The selection, obtained through an algorithmic procedure based on data mining tools, assumes the existence of a reference asset we are specifically interested to. The procedure allows one to opt for two alternatives: to prefer those assets exhibiting either a minimum lower tail dependence or a maximum upper tail dependence. The former could be a recommendable opportunity in a financial crisis period. For the selected assets, the tail dependence coefficients are estimated by means of a proper multivariate copula function. Copyright © 2010 John Wiley & Sons, Ltd.
Active shape modeling of the hip in the prediction of incident hip fracture
Authors: Baker-LePain Julie C , Luker Kali R , Lynch John A , Parimi Neeta , Nevitt Michael C , Lane Nancy E
Published: September 2010

The objective of this study was to evaluate right proximal femur shape as a risk factor for incident hip fracture using active shape modeling (ASM). A nested case-control study of white women 65 years of age and older enrolled in the Study of Osteoporotic Fractures (SOF) was performed. Subjects (n = 168) were randomly selected from study participants who experienced hip fracture during the follow-up period (mean 8.3 years). Controls (n = 231) had no fracture during follow-up. Subjects with baseline radiographic hip osteoarthritis were excluded. ASM of digitized right hip radiographs generated 10 independent modes of variation in proximal femur shape that together accounted for 95% of the variance in proximal femur shape. The association of ASM modes with incident hip fracture was analyzed by logistic regression. Together, the 10 ASM modes demonstrated good discrimination of incident hip fracture. In models controlling for age and body mass index (BMI), the area under receiver operating characteristic (AUROC) curve for hip shape was 0.813, 95% confidence interval (CI) 0.771–0.854 compared with models containing femoral neck bone mineral density (AUROC = 0.675, 95% CI 0.620–0.730), intertrochanteric bone mineral density (AUROC = 0.645, 95% CI 0.589–0.701), femoral neck length (AUROC = 0.631, 95% CI 0.573–0.690), or femoral neck width (AUROC = 0.633, 95% CI 0.574–0.691). The accuracy of fracture discrimination was improved by combining ASM modes with femoral neck bone mineral density (AUROC = 0.835, 95% CI 0.795–0.875) or with intertrochanteric bone mineral density (AUROC = 0.834, 95% CI 0.794–0.875). Hips with positive standard deviations of ASM mode 4 had the highest risk of incident hip fracture (odds ratio = 2.48, 95% CI 1.68–3.31, p < .001). We conclude that variations in the relative size of the femoral head and neck are important determinants of incident hip fracture. The addition of hip shape to fracture-prediction tools may improve the risk assessment for osteoporotic hip fractures. © 2011 American Society for Bone and Mineral Research.
Influence of long-term postmenopausal hormone-replacement therapy on estimated structural bone strength: A study in discordant monozygotic twins
Authors: Mikkola Tuija M , Heinonen Ari , Kovanen Vuokko , Cheng Sulin , Kujala Urho M , Suominen Harri , Alén Markku , Puolakka Jukka , Ankarberg-Lindgren Carina , Ronkainen Paula HA , Koskenvuo Markku , Kaprio Jaakko , Rantanen Taina , Sipilä Sarianna
Published: September 2010

Although postmenopausal hormone-replacement therapy (HRT) is known to prevent fractures, knowledge on the influence of long-term HRT on bone strength and its determinants other than areal bone mineral density is scarce. This study used a genetically controlled design with 24 monozygotic female twin pairs aged 54 to 72 years in which one cotwin was using HRT (mean duration 8 years) and the other had never used HRT. Estimated bone strength, cross-sectional area, volumetric bone mineral density, bone mineral mass, and cross-sectional density and mass distributions were assessed in the tibial shaft, distal tibia, and distal radius with peripheral computed tomography (pQCT). In the tibial shaft, HRT users had 9% [95% confidence interval (CI) 3%–15%] higher estimated bending strength than their nonusing cotwins. Larger cortical area and higher cortical bone mineral density accounted for this difference. The cortex was larger in the HRT users in the endocortical region. In the distal tibia, estimated compressive strength was 24% (95% CI 9%–40%) higher and in the distal radius 26% (95% CI 11%–41%) higher in the HRT users than in their nonusing cotwins owing to higher volumetric bone mineral density. No difference between users and nonusers was observed in total bone cross-sectional area in any measured bone site. The added mineral mass in the HRT users was distributed evenly within and between bone sites. In postmenopausal women, long-term HRT preserves estimated bone strength systemically by preventing bone mineral loss similarly in body weight–loaded and non-weight-loaded bone. © 2011 American Society for Bone and Mineral Research.
Association of menopausal vasomotor symptoms with increased bone turnover during the menopausal transition
Authors: Crandall Carolyn J , Tseng Chi-Hong , Crawford Sybil L , Thurston Rebecca C , Gold Ellen B , Johnston Janet M , Greendale Gail A
Published: September 2010

The purpose of this study was to determine the longitudinal association between menopausal vasomotor symptoms (VMS) and urinary N-telopeptide level (NTX) according to menopausal stage. We analyzed data from 2283 participants of the Study of Women's Health Across the Nation, a longitudinal community-based cohort study of women aged 42 to 52 years at baseline. At baseline and annually through follow-up visit 8, participants provided questionnaire data, urine samples, serum samples, and anthropometric measurements. Using multivariable repeated-measures mixed models, we examined associations between annually assessed VMS frequency and annual NTX measurements. Our results show that mean adjusted NTX was 1.94 nM of bone collagen equivalents (BCE)/mM of creatinine higher among early perimenopausal women with any VMS than among early perimenopausal women with no VMS (p < .0001). Mean adjusted NTX was 2.44 nM BCE/mM of creatinine higher among late perimenopausal women with any VMS than among late perimenopausal women with no VMS (p = .03). Among premenopausal women, VMS frequency was not significantly associated with NTX level. When NTX values among women with frequent VMS (≥6 days in past 2 weeks) were expressed as percentages of NTX values among women without frequent VMS, the differences were 3% for premenopausal women, 9% for early perimenopausal women, 7% for late perimenopausal women, and 4% for postmenopausal women. Adjustment for serum follicle-stimulating hormone (FSH) level greatly reduced the magnitudes of associations between VMS and NTX level. We conclude that among early perimenopausal and late perimenopausal women, those with VMS had higher bone turnover than those without VMS. Prior to the final menstrual period, VMS may be a marker for risk of adverse bone health. © 2011 American Society for Bone and Mineral Research.
Conserved regulatory motifs in osteogenic gene promoters integrate cooperative effects of canonical Wnt and BMP pathways
Authors: Rodríguez-Carballo Edgardo , Ulsamer Arnau , Susperregui Antonio RG , Manzanares-Céspedes Cristina , Sánchez-García Eva , Bartrons Ramon , Rosa José Luis , Ventura Francesc
Published: September 2010

Osteoblast differentiation depends on the coordinated network of evolutionary conserved transcription factors during bone formation and homeostasis. Evidence indicates that bone morphogenetic protein (BMP) and Wnt proteins regulate several steps of skeletal development. Here, we provide a molecular description of the cooperative effects of BMP and Wnt canonical pathway on the expression of the early osteogenic genes Dlx5, Msx2, and Runx2 in C2C12 cells, primary cultures of bone marrow–mesenchymal stem cells, and organotypic calvarial cultures. Coordinated regulation of these genes leads to the cooperative activation of their downstream osteogenic target gene osterix. Induction of these genes is mediated through enhancer regions with an evolutionary conserved structure encompassing both Smad and TCF/LEF1 DNA-binding sites. Formation of a cooperative complex is mediated through DNA binding of Smads and TCF4/β-catenin to their cognate sequences, as well as protein-protein interactions between them. The formation of these cooperative transcriptional complexes results in a more efficient recruitment of coactivators such as p300. We propose that evolutionary conserved regulatory regions in specific osteogenic master genes are key integrative modules during osteogenesis. © 2011 American Society for Bone and Mineral Research.
A methodology for Raman structural quantification imaging and its application to iron indoor atmospheric corrosion products
Authors: Monnier Judith , Bellot‐Gurlet Ludovic , Baron Denis , Neff Delphine , Guillot Ivan , Dillmann Philippe
Published: September 2010

Raman structural imaging can extract original information in order to answer new questions raised in the recent studies on iron and low alloy steel corrosion. Up to now, this technique has allowed the extraction of the qualitative distribution of the compounds constituting the corrosion product layers. We propose here a methodology to extract quantitative parameters from Raman hyperspectral maps, executed by a home‐developed software: LADIR‐CAT. Specifically developed for iron corrosion quantitative component imaging, the approach and program operation are described. The LADIR‐CAT is applied on ancient corroded iron samples originating from the Amiens cathedral (France) to establish the description and the composition of the corrosion system through quantitative compound imaging. Copyright © 2010 John Wiley & Sons, Ltd.
UV resonance Raman study of cation–π interactions in an indole crown ether
Authors: Schlamadinger Diana E. , Daschbach Megan M. , Gokel George W. , Kim Judy E.
Published: September 2010

UV resonance Raman (UVRR) spectroscopy is used to probe changes in vibrational structure associated with cation–π interactions for the most prevalent amino acid π–donor, tryptophan. The model compound studied here is a diaza crown ether with two indole substituents. In the presence of sodium or potassium sequestered in the crown ether, or a protonated diaza group on the compound, the indole moieties participate in a cation–π interaction in which the pyrrolo group acts as the primary π‐donor. Systematic shifts in relative intensity in the 760–780 cm−1 region are observed upon formation of this cation–π interaction; we propose that these modifications reflect shifts of the delocalized, ring‐breathing W18 and hydrogen‐out‐of‐plane (HOOP) vibrational modes in this spectral region. The observed changes are attributed to perturbations of the π‐electron density as well as of normal modes that involve large displacement of the hydrogen atom on the C2 position of the pyrrole ring. Modest variations in the UVRR spectra for the three complexes studied here are correlated to differences in cation–π strength. Specifically, the UVRR spectrum of the sodium‐bound complex differs from those of the potassium‐bound or protonated‐diaza complexes, and may reflect the observation that the C2 hydrogen atom in the sodium‐bound complex exhibits the greatest perturbation relative to the other species. Normal modes sensitive to hydrogen‐bonding, such as the tryptophan W10, W9, and W8 modes, also undergo shifts in the presence of the salts. These shifts reflect the strength of interaction of the indole NH group with the iodide or hexafluorophosphate counteranion. The current observation that the W18 and HOOP normal mode regions of the indole crown ether compound are sensitive to cation–pyrrolo π interactions suggests that this region may provide reliable spectroscopic evidence of these important interactions in proteins. Copyright © 2010 John Wiley & Sons, Ltd.
Structural and nonlinear optical properties of cross‐conjugated system benzophenone thiosemicarbazone: a vibrational spectroscopic study
Authors: Ravikumar C. , Hubert Joe I.
Published: September 2010

The nonlinear optical (NLO) compound of interest benzophenone thiosemicarbazone (BTSC) was grown and the molecular structure generated with the aid of density functional theory (DFT). FT‐Raman and IR spectra were recorded and analyzed. The harmonic wavenumbers and IR and Raman intensities were computed with the B3LYP method. The observed vibrational wavenumbers were compared with the calculated results. The assignments of the experimental spectra were made with the help of normal coordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The electronic structure of the most important molecular fragments is described in terms of natural bond orbital (NBO) analysis. Copyright © 2010 John Wiley & Sons, Ltd.