bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of Vascular Endothelial Growth Factor Expression and Vascularization in the Myocardium by Insulin Receptor and PI3K/Akt Pathways in Insulin Resistance and Ischemia
Authors: He Zhiheng , Opland Darren M. , Way Kerrie J. , Ueki Kohjiro , Bodyak Natalya , Kang Peter M. , Izumo Seigo , Kulkarni Rohit N. , Wang Bo , Liao Ronglih , Kahn C. Ronald , King George L.
Published: February 2006

Objective—

This study characterized the role of insulin receptors and resistance on vascular endothelial growth factor (VEGF) expression and myocardial vascularization in physiological conditions and after ischemia.

Methods and Results—

Cardiac microvascular density was reduced by 30% in insulin-resistant Zucker fatty rats versus lean controls. This was associated with a parallel 40% inhibition of insulin-stimulated activation of both Akt and VEGF expression in the myocardium and cardiomyocytes. In contrast, the activation of Erk1/2 by insulin remained unchanged. In cultured cardiomyocytes, insulin or insulin-like growth factor (IGF)-1 increased VEGF mRNA and protein expression by 2-fold. Inhibition of PI3K/Akt, especially Akt2-mediated cascades but not the Ras/MEK/Erk pathway, using chemical inhibitors, dominant negative adenoviral constructs, or siRNA approaches suppressed VEGF mRNA expression by insulin. Ventricular tissues from muscle insulin receptor knockout (MIRKO) mice, which lack insulin receptors in the myocardium, have significant reductions in insulin but not IGF-1 signaling, VEGF expression, and vascular density before and after ischemia versus controls.

Conclusions—

Insulin regulates VEGF gene expression and vascularization in the myocardium specifically via insulin receptors and the activation of PI3K/Akt pathway. Selective inhibition of this pathway may lead to the decreases in VEGF expression and capillary density in the myocardium of patients with insulin resistance.
Soluble Adenylyl Cyclase Reveals the Significance of cAMP Compartmentation on Pulmonary Microvascular Endothelial Cell Barrier
Authors: Sayner Sarah L. , Alexeyev Mikhail , Dessauer Carmen W. , Stevens Troy
Published: February 2006

Subtle elevations in cAMP localized to the plasma membrane intensely strengthen endothelial barrier function. Paradoxically, pathogenic bacteria insert adenylyl cyclases (ACs) into eukaryotic cells generating a time-dependent cytosolic cAMP-increase that disrupts rather than strengthens the endothelial barrier. These findings bring into question whether membrane versus cytosolic AC activity dominates in control of cell adhesion. To address this problem, a mammalian forskolin-sensitive soluble AC (sACI/II) was expressed in pulmonary microvascular endothelial cells. Forskolin stimulated this sACI/II construct generating a small cytosolic cAMP-pool that was not regulated by phosphodiesterases or G
αs
. Whereas forskolin simultaneously activated the sACI/II construct and endogenous transmembrane ACs, the modest sACI/II activity overwhelmed the barrier protective effects of plasma membrane activity to induce endothelial gap formation. Retargeting sACI/II to the plasma membrane retained AC activity but protected the endothelial cell barrier. These findings demonstrate for the first time that the intracellular location of cAMP synthesis critically determines its physiological outcome.
Cerebral Microhemorrhages Predict New Disabling or Fatal Strokes in Patients With Acute Ischemic Stroke or Transient Ischemic Attack
Authors: Boulanger Jean-Martin , Coutts Shelagh B. , Eliasziw Michael , Gagnon A.J. , Simon Jessica E. , Subramaniam Suresh , Sohn Chul-Ho , Scott James , Demchuk Andrew M.
Published: February 2006

Background and Purpose—

Cerebral microhemorrhages (MHs) are common among patients presenting with acute ischemic stroke and may predict both subsequent ischemic and hemorrhagic strokes.

Methods—

We prospectively studied patients with and without MHs presenting within 12 hours of their ischemic stroke or transient ischemic attack (TIA). A magnetic resonance (MR) scan was performed within 24 hours of symptom(s) onset. The primary outcome was disabling or fatal stroke at 18 months.

Results—

An MR scan was done in 236 patients with acute ischemic stroke or TIA. Forty-five (19.1%) patients had an MH on a baseline MR scan. Patients with MHs were 2.8× (10.8% versus 4.0%;
P
=0.036) more likely to have a subsequent disabling or fatal stroke than patients without an MH. The risk of symptomatic intracerebral hemorrhage was not statistically significant among MH and non-MH patients (3.3% versus 0.8%;
P
=0.31).

Conclusions—

The presence of cerebral MH(s) in patients with acute ischemic stroke or TIA predicts recurrent disabling and fatal strokes. This risk is mainly assumed by recurrent ischemic strokes.
Association Between Carotid Plaque Characteristics and Subsequent Ischemic Cerebrovascular Events
Authors: Takaya Norihide , Yuan Chun , Chu Baocheng , Saam Tobias , Underhill Hunter , Cai Jianming , Tran Nam , Polissar Nayak L. , Isaac Carol , Ferguson Marina S. , Garden Gwenn A. , Cramer Steven C. , Maravilla Kenneth R. , Hashimoto Beverly , Hatsukami Thomas S.
Published: February 2006

Background and Purpose—

MRI is able to quantify carotid plaque size and composition with good accuracy and reproducibility and provides an opportunity to prospectively examine the relationship between plaque features and subsequent cerebrovascular events. We tested the hypothesis that the characteristics of carotid plaque, as assessed by MRI, are possible predictors of future ipsilateral cerebrovascular events.

Methods—

A total of 154 consecutive subjects who initially had an asymptomatic 50% to 79% carotid stenosis by ultrasound with ≥12 months of follow-up were included in this study. Multicontrast-weighted carotid MRIs were performed at baseline, and participants were followed clinically every 3 months to identify symptoms of cerebrovascular events.

Results—

Over a mean follow-up period of 38.2 months, 12 carotid cerebrovascular events occurred ipsilateral to the index carotid artery. Cox regression analysis demonstrated a significant association between baseline MRI identification of the following plaque characteristics and subsequent symptoms during follow-up: presence of a thin or ruptured fibrous cap (hazard ratio, 17.0;
P
≤0.001), intraplaque hemorrhage (hazard ratio, 5.2;
P
=0.005), larger mean intraplaque hemorrhage area (hazard ratio for 10 mm
2
increase, 2.6;
P
=0.006), larger maximum %lipid-rich/necrotic core (hazard ratio for 10% increase, 1.6;
P
=0.004), and larger maximum wall thickness (hazard ratio for a 1-mm increase, 1.6;
P
=0.008).

Conclusions—

Among patients who initially had an asymptomatic 50% to 79% carotid stenosis, arteries with thinned or ruptured fibrous caps, intraplaque hemorrhage, larger maximum %lipid-rich/necrotic cores, and larger maximum wall thickness by MRI were associated with the occurrence of subsequent cerebrovascular events. Findings from this prospective study provide a basis for larger multicenter studies to assess the risk of plaque features for subsequent ischemic events.
Effect of Posterolateral Scar Tissue on Clinical and Echocardiographic Improvement After Cardiac Resynchronization Therapy
Authors: Bleeker Gabe B. , Kaandorp Theodorus A.M. , Lamb Hildo J. , Boersma Eric , Steendijk Paul , de Roos Albert , van der Wall Ernst E. , Schalij Martin J. , Bax Jeroen J.
Published: February 2006

Background—

Currently, one third of patients treated with cardiac resynchronization therapy (CRT) do not respond. Nonresponse to CRT may be explained by the presence of scar tissue in the posterolateral left ventricular (LV) segments, which may result in ineffective LV pacing and inadequate LV resynchronization. In the present study, the relationship between transmural posterolateral scar tissue and response to CRT was evaluated.

Methods and Results—

Forty consecutive patients with end-stage heart failure (NYHA class III/IV), LV ejection fraction ≤35%, QRS duration >120 ms, left bundle-branch block, and chronic coronary artery disease were included. The localization and transmurality of scar tissue were evaluated with contrast-enhanced MRI. Next, LV dyssynchrony was assessed at baseline and immediately after implantation with tissue Doppler imaging. Clinical parameters, LV volumes, and LV ejection fraction were assessed at baseline and at a 6-month follow-up. Fourteen patients (35%) had a transmural (>50% of LV wall thickness) posterolateral scar. In contrast to patients without posterolateral scar tissue, these patients showed a low response rate (14% versus 81%;
P
<0.05) and did not show improvement in clinical or echocardiographic parameters. In addition, LV dyssynchrony remained unchanged after CRT implantation (84±46 versus 78±41 ms;
P
=NS). Patients without posterolateral scar tissue and severe baseline dyssynchrony (≥65 ms) showed an excellent response rate of 95% compared with patients with a posterolateral scar and/or absent LV dyssynchrony (11%).

Conclusions—

CRT does not reduce LV dyssynchrony in patients with transmural scar tissue in the posterolateral LV segments, resulting in clinical and echocardiographic nonresponse to CRT.
Postconditioning Protects Against Endothelial Ischemia-Reperfusion Injury in the Human Forearm
Authors: Loukogeorgakis Stavros P. , Panagiotidou Anna T. , Yellon Derek M. , Deanfield John E. , MacAllister Raymond J.
Published: February 2006

Background—

Hypoxic cell death follows interruption of blood supply to tissues. Although successful restoration of blood flow is mandatory for salvage of ischemic tissues, reperfusion can paradoxically place tissues at risk of further injury. Brief periods of ischemia applied at the onset of reperfusion have been shown to reduce ischemia-reperfusion (IR) injury, a phenomenon called postconditioning. The aim of this study was to determine whether postconditioning protects against endothelial IR injury in humans, in vivo.

Methods and Results—

Brachial artery endothelial function was assessed by vascular ultrasound to measure flow-mediated dilation (FMD) in response to forearm reactive hyperemia. FMD was measured before and after IR (20 minutes of arm ischemia followed by 20 minutes of reperfusion) in healthy volunteers. To test the protective effects of postconditioning, 3 cycles of reperfusion followed by ischemia (each lasting 10 or 30 seconds) were applied immediately after 20 minutes of arm ischemia. To determine whether postconditioning needs to be applied at the onset of reperfusion, a 1-minute period of arm reperfusion was allowed before the application of the 10-second postconditioning stimulus. IR caused endothelial dysfunction (FMD 9.1±1.2% pre-IR, 3.6±0.7% post-IR,
P
<0.001; n=11), which was prevented by postconditioning applied as 10-second cycles of reperfusion/ischemia (FMD 9.9±1.7% pre-IR, 8.3±1.4% post-IR,
P
=NS; n=11) and 30-second cycles of reperfusion/ischemia (FMD 10.8±1.7% pre-IR, 9.5±1.5% post-IR,
P
=NS; n=10) immediately at the onset of reperfusion. No protection was observed when the application of the 10-second postconditioning stimulus was delayed for 1 minute after the onset of reperfusion (FMD 9.8±1.2% pre-IR, 4.0±0.9% post-IR,
P
<0.001; n=8).

Conclusions—

This study demonstrates for the first time that postconditioning can protect against endothelial IR injury in humans. Postconditioning might reduce tissue injury when applied at the onset of reperfusion by modifying the reperfusion phase of IR.
Singular Spectrum Analysis of Nonstationary Tidal Currents Applied to ADCP Data from the Northeast Brazilian Shelf
Authors: Vianna Marcio L. , Menezes Viviane V.
Published: February 2006

The development of new tools for the analysis of nonstationary currents, including tidal currents, has been the subject of recent research. In this work a method for studies of nonstationary barotropic or baroclinic currents based on empirical orthogonal function (EOF) and singular spectrum analysis (SSA) is proposed. It represents a new alternative to other methods of analysis of tidal currents in strong interaction with nontidal forcing, for example, the continuous wavelet transform. The advantage of the SSA method resides in the fact that it is fast, easy to implement, efficient for short-time records, and is based on the covariance structure of the data. If significant tidal constituents occur in the measurements, these are determined by the method itself even with short-time-series records. This is in contrast to the harmonic analysis (HA), where a large table of tidal constituents stated a priori are fitted to the data, even if the presence of some of these are spurious and not justified physically. The method is first demonstrated in the analysis of a synthetic current time series and then applied to an hourly current ADCP profile dataset of 410 days from the northeast Brazilian shelf. In both cases the SSA results were compared to the classical HA and the neoclassical short-term HA (STHA). The description of the shelf area where the ADCP was placed, the deployment and data acquisition operations, and the quality control data analysis are included for completeness. Analysis of the full ADCP quality-controlled data was done after a separation of the subtidal from the tidal high-frequency bands, although this traditional separation is not strictly necessary and was only made to better compare with HA and STHA. Analysis of the tidal band obtained from the ADCP data showed that the extracted tidal ellipse constituents present coherent oscillations dominated by the annual and 57-day periods, and changes in the sense of rotation of the current vector from anticyclonic to cyclonic in the ellipses. The subtidal band variability is shown to be also dominated by an annual and a 57-day period component, both polarized along the isobaths, which is suggestive of a nonlinear interaction of the subtidal and the tidal variability.
An Application of Neural Network Technique to Correct the Dome Temperature Effects on Pyrgeometer Measurements
Authors: Oliveira Amauri P. , Soares Jacyra , Božnar Marija Z. , Mlakar Primož , Escobedo João F.
Published: February 2006

This work describes an application of a multilayer perceptron neural network technique to correct dome emission effects on longwave atmospheric radiation measurements carried out using an Eppley Precision Infrared Radiometer (PIR) pyrgeometer. It is shown that approximately 7-month-long measurements of dome and case temperatures and meteorological variables available in regular surface stations (global solar radiation, air temperature, and air relative humidity) are enough to train the neural network algorithm and correct the observed longwave radiation for dome temperature effects in surface stations with climates similar to that of the city of São Paulo, Brazil. The network was trained using data from 15 October 2003 to 7 January 2004 and verified using data, not present during the network-training period, from 8 January to 30 April 2004. The longwave radiation values generated by the neural network technique were very similar to the values obtained by Fairall et al., assumed here as the reference approach to correct dome emission effects in PIR pyrgeometers. Compared to the empirical approach the neural network technique is less limited to sensor type and time of day (allows nighttime corrections).
An OSSE Framework Based on the Ensemble Square Root Kalman Filter for Evaluating the Impact of Data from Radar Networks on Thunderstorm Analysis and Forecasting
Authors: Xue Ming , Tong Mingjing , Droegemeier Kelvin K.
Published: February 2006

A framework for Observing System Simulation Experiments (OSSEs) based on the ensemble square root Kalman filter (EnSRF) technique for assimilating data from more than one radar network is described. The system is tested by assimilating simulated radial velocity and reflectivity data from a Weather Surveillance Radar-1988 Doppler (WSR-88D) radar and a network of four low-cost radars planned for the Oklahoma test bed by the new National Science Foundation (NSF) Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere (CASA). Such networks are meant to adaptively probe the lower atmosphere that is often missed by the existing WSR-88D radar network, so as to improve the detection of low-level hazardous weather events and to provide more complete data for the initialization of numerical weather prediction models.

Different from earlier OSSE work with ensemble Kalman filters, the radar data are sampled on the radar elevation levels and a more realistic forward operator based on the Gaussian power-gain function is used. A stretched vertical grid with high vertical resolution near the ground allows for a better examination of the impact of low-level data. Furthermore, the impacts of storm propagation and higher-volume scan frequencies up to one volume scan per minute on the quality of analysis are examined, using a domain of a sufficient size. The generally good analysis compared to earlier work indicates that the filter can effectively handle the non-uniform-resolution data on the radar elevation levels.

The assimilation of additional data from a well-positioned (relative to the storm) CASA radar improves the analysis of a supercell storm system that uses data from one WSR-88D radar alone; and the improvement is most significant at the low levels. When data from a single CASA radar are assimilated and when the radar does not provide full coverage of the storm system, significant errors develop in the analysis that cannot be effectively corrected. The combination of three CASA radars produces analyses of similar quality as the combination of one WSR-88D radar and one well-positioned CASA radar.

The most significant effect of storm propagation speed appears to be on the data coverage, which in turn affects the analysis quality. It is generally true that the more observations, the better the analysis. The results of the EnSRF assimilation are not very sensitive to the propagation speed. The quality of analysis can be improved by employing faster volume scans. The sensitivity of the EnSRF analysis to the volume scan interval is however much less than that of traditional velocity and thermodynamic retrieval schemes, suggesting the superiority of the EnSRF method compared to traditional methods. The very frequent update of the model state by the filter, even at 1-min intervals, does not show any negative effect, indicating that the analyzed fields are well balanced.
Closed-form Solutions for the Overall Coefficient of Thermal Expansion of n-phase Fiber Composites with Arbitrary Fiber Orientation
Authors: Ng Ernest T. Y. , Wood G. M. , Suleman Afzal
Published: February 2006

The coefficient of thermal expansion (CTE) is an important physical property of fiber composites. In the past, researchers have provided closed-form expressions for CTE for 2D and 3D random fiber composite structures. In this study, closed-form solutions for the overall CTE of n-phase fiber composites with arbitrary fiber orientation angles are derived based on the volume-weighted averaging equation. The overall unidirectional (fully aligned fibers) thermoelastic properties are developed using the transformation field analysis (TFA) method. In addition, the mechanical concentration factors are estimated using the Eshelby-Mori-Tanaka (EMT) theory. The proposed model allows for varying the fiber volume fraction, aspect ratio, geometry of the fibers, and fiber orientations while designing to meet different criteria. The results obtained using the derived equations are compared and validated with the results published in the literature. Also, a numerical study for an epoxy/graphite composite structure with a range of orientation angles is presented.
A Novel Method for the Manufacturing of Thick Composites
Authors: Jiang Yijun , Hoa Suong V.
Published: February 2006

Pre-catalyzing fabric method is a newly developed technique applied in manufacturing thick composites with hand layup process. By applying a peroxide catalyst to the fabric instead of mixing it into the bulk resin system, this technique can slow down the polymerization reaction rate and subsequently reduce the internal temperature of thick composites. In this study, two kinds of pre-catalyzing methods are developed: one uses polystyrene as the catalyst binder; another uses epoxy resin as the binder. The experimental results indicate that the pre-catalyzing method using polystyrene binder can eliminate the peak exothermic temperature, and the method using epoxy binder can limit this temperature to be below 39 C. The latter method has shorter curing time than the former one. The degree of cure for both methods can be more than 87% with low exothermic temperature after cure, and with this degree of cure, the laminate is rigid enough for further post cure. The degree of cure can be improved to be more than 97% by leaving the samples for more than five weeks in ambient temperature. Compared with the polystyrene binder which made the interlaminar shear strength decrease by 12.4%, the epoxy resin binder has the better characteristic, not to exhibit this decrease.
Managerial Culture, Workplace Culture and Situated Curricula in Organizational Learning
Authors: Raz Aviad E. , Fadlon Judith
Published: February 2006

Seen from a perspective of symbolic interaction and social constructivism, organizational learning is a practical accomplishment that takes place among and through other organizational members. This study sets out to explore the social construction of organizational learning by examining the responses of members to a management-imposed teaching curriculum that contradicted basic assumptions regarding professional identity. We build on the results of recent ethnographic fieldwork which has investigated the incorporation of communication skills training in an Israeli medical school. This professional socialization is examined in terms of its theoretization by the management, its implementation in the curriculum, and its interpretation by supervising physicians and medical students. These various facets of meaning and their mismatches provide a concrete example for the study of situated learning in organizations. We conclude by exploring the meaning and interplay of managerial ideology, workplace culture and situated curricula in organizational learning.
Double-Loop Suture Repair for Acute Acromioclavicular Joint Disruption
Authors: Dimakopoulos Panayotis , Panagopoulos Andreas , Syggelos Spyros A. , Panagiotopoulos Elias , Lambiris Elias
Published: February 2006

Background

Although it has been established that surgical treatment for acromioclavicular joint disruption (types IV-VI and type III in overhead throwing athletes and heavy laborers) is preferred, the literature is inconclusive about the best type of surgery.

Purpose

With the goal of avoiding the potential complications of hardware use, the authors present a coracoclavicular functional stabilization technique with the intention to restore the anteroposterior and superior displacement of the clavicle.

Study Design

Case series; Level of evidence, 4.

Methods

From 1999 to 2003, 38 patients with an acute, complete acromioclavicular joint separation (34 men, 4 women; mean age, 33.5 years) underwent surgical reconstruction with the described coracoclavicular loop stabilization technique. With this technique, the superior and anteroposterior displacement of the clavicle can be easily controlled using 2 pairs of Ethibond No. 5 nonabsorbable sutures—one passed in front and the other behind the clavicle, through a central drill hole, 2 cm from its lateral end, directly above the base of the coracoid process (at the corresponded attachment of coracoclavicular ligaments). Passive shoulder motion was encouraged by the second postoperative day.

Results

Thirty-four patients were available for the last clinical and radiologic evaluation. At a mean follow-up of 33.2 months (range, 18-59 months), the mean Constant-Murley score was 93.5 points (range, 73-100 points), and 2 cases with slight loss of reduction (less than half of the width of the clavicle) were detected. Complications included 1 case with superficial infection and 1 patient (basketball player) with persistent tenderness in the acromioclavicular joint without signs of secondary arthritis. The incidence of periarticular ossification was 17.6% and did not affect the final outcome. Secondary degenerative changes were not detected.

Conclusion

Considering the nearly anatomical reconstruction, the avoidance of hardware complications, and the low rate of recurrence, this technique may be an attractive alternative to the management of acute acromioclavicular joint separations.
Measuring the Adoption of Local Sprawl
Authors: Brody Samuel D. , Carrasco Virginia , Highfield Wesley E.
Published: February 2006

While sprawling growth patterns have become a major issue for planners and environmental managers, little empirical research has been conducted on the adoption of sprawl-reduction policies in local plans. The authors systematically evaluate the comprehensive plans of fortysix local jurisdictions in southern Florida for the presence of five sprawl-reduction planning policies (SRPPs) using planevaluation techniques. Results indicate a clear statistical and spatial pattern of SRPPs across the study area and show that specific socioeconomic and demographic characteristics influence the adoption of SRPPs in comprehensive plans.
Dividing Lines and Bottom Lines
Authors: Thomas John V.
Published: February 2006

Over the past decade, planners and policy makers have increasingly raised concerns about the undue influence of fiscal criteria on development patterns. However, realestate conditions, local practices, state policies, and community characteristics also shape land-use patterns. This study seeks to unpack these complex relationships through an explanatory model evaluating the construction patterns of mediumsized U.S. cities. The results reveal that although market conditions do help explain development patterns, the fiscal and demographic profiles of cities are also significant factors. In particular, rising public expenditures, statewide revenuelimitation policies, and other fiscal pressures are more strongly associated with certain patterns of development. Specifically, these factors were associated with cities that developed primarily high-value residential units, excluded multifamily units, and developed proportionately more retail than housing. This suggests that fiscal conditions, including those generated by statewide policy, do seem related to the land-use outcomes highlighted by the critics.
Learning from Europe? EU Studies and the Re-thinking of ‘International Relations’
Authors: Warleigh Alex
Published: February 2006

This article argues that European Union Studies (EUS) provides a useful resource for scholars engaged in the rethinking of international relations in the era of an emerging global polity which has been neglected for reasons of what might be called discipline blindness. More precisely, my claim is that EUS can help IR scholars ask new and useful questions about the nature, development and functioning of the emerging global polity. This is because EUS has already drawn on, and adapted, comparative politics to produce a significant body of work which can act as a transmission belt for ideas, concepts and approaches between the study of ‘domestic politics’ and the study of ‘international relations’, and thus begin to show IR scholars how these tools can be adapted and used to study politics in post- and transnational contexts.
Positive self-worth is not enough: some implications of a two-dimensional model of self-esteem for primary teaching®
Authors: Miller David J. , Moran Teresa
Published: February 2006

This article focuses on self-esteem in the primary classroom in the light of new understandings from the psychological literature. Recent theoretical and empirical work suggests our previous conception of self-esteem has been limited in some important respects. There is a growing awareness of the two-dimensional nature of self-esteem, and this indicates that the creation of a sense of self-worth has to be complemented by a similar emphasis on self-competence. Employing a two-dimensional model of self-esteem as a framework for analysis, and incorporating other recent research in this area, we consider implications for practice. We focus in particular on the messages we give children, the use of praise and the processes of formative assessment. It is argued that teachers and teacher educators now need to take more account of the competence dimension of self-esteem.
Building teacher leadership in Hertfordshire®
Authors: Mylles Joanne , Frost David
Published: February 2006

This article draws upon small scale research carried out by an Assistant Head Teacher. It focuses on strategies to enable teachers to exercise learning centred leadership in secondary schools. There is a brief account of the ‘Teacher-led Development Work’ programme supported by a partnership between the University of Cambridge Faculty of Education and the local authority in Hertfordshire. This account is located within a discussion about school improvement and distributed leadership. At the centre of the article are two case studies of teachers who develop their leadership capacity through participation in the programme.
Debond Detection using Embedded Piezoelectric Elements in Reinforced Concrete Structures - Part I: Experiment
Authors: Wu Fan , Chang Fu-Kuo
Published: February 2006

An investigation is performed to detect debond in reinforced concrete structures. This study utilizes built-in piezoelectric discs as sensors and actuators in a pitch-catch mode to generate sensor data, which are sensitive to debond in reinforced concrete. A comparison of sensor measurements or signal changes before and after maintenance or inspection can be correlated to debonding. Both experimental and analytical works are performed during the study. Experimental study and test data are presented in this article. The test results clearly indicate that debond between concrete and rebar and yielding in rebar can be detected with built-in piezoelectric sensors and actuators in a pitch-catch mode.
Integrated Virtual Instrumentation and Wireless Monitoring for Infrastructure Diagnostics
Authors: Farhey Daniel N.
Published: February 2006

This article presents the research, development, and field testing of a computer-controlled integrated instrumentation and monitoring system for rapid-response infrastructure testing and evaluation. The system eliminates both stand-alone laboratory benchtop equipment sets and cable-based, hard-wired, on-site networking for individual sensors. A software-based virtual instrumentation program package is developed to replace conventional data acquisition and monitoring equipment and control all system components through a user-friendly graphical user interface. In addition, a multiple-channel wireless site network throughout the structure is developed to substitute cable networking and integrated in the modular system. Concept and design characterizations, validation testing, and practical field use for experimental live-load bridge test monitoring are also presented. The tests verify the computer-controlled operation of the system integrating virtual instrumentation with multiple-channel wireless site network. The results are compared with conventional instrumentation system and found to be consistent.
Multilevel Decision Fusion in a Distributed Active Sensor Network for Structural Damage Detection
Authors: Wang Xiaoming , Foliente Greg , Su Zhongqing , Ye Lin
Published: February 2006

Distributed sensor networks are emerging as a critical technical driver in the application of structural health monitoring for large-scale structures as a result of their excellent abilities to enhance the reliability and robustness of monitoring systems. One of the key technical opportunities in the implementation of a distributed sensor network is the application of information fusion. Not only does this enable the integration of data from all sensors for the comprehensive assessment of structural conditions, but it also facilitates the combination of decisions or perceptions from multiple sources or different approaches. In this article, the feasibility of combining a distributed sensor network and several techniques of multilevel decision fusion are demonstrated for damage detection. The level-one decision fusion is first implemented by individual active sensors to create their own perceptions on structural health status. During the fusion process, the active sensors first interrogated local physical sensor nodes in the network, and then combined the perceptions of the local sensors in terms of correlation between features extracted from raw signals and damage scenarios in a knowledge database. Meanwhile, the perceptions of active sensors on structural health status are integrated to represent the decision fusion at level two. Considering the level-two decisions made from different technical approaches, a further combination of all decisions is conducted with implication of information fusion at a higher decision level. As a consequence, the risks of a malfunction of individual sensors or the inappropriateness of individual assessment procedures are significantly reduced, and a robust and error-tolerant structural health monitoring system can be developed. Such an approach is successfully validated by an experimental case study of damage detection in CF/EP composite structures.
Automated Characterization of Structural Disbonds by Statistical Examination of Bond-line Strain Distribution
Authors: Li H. C.H. , Herszberg I. , Mouritz A. P.
Published: February 2006

This article outlines a statistical damage detection engine for the automated characterization of disbonds in bonded structural joints. Unlike other complex pattern recognition algorithms, the statistical technique described in this article is model-independent. This avoids the need to generate accurate numerical models of the structure which is time and resource intensive. Instead, the training data for the damage detection engine is derived from actual measurements of the virgin (undamaged) structure using embedded sensors. The sensor measurements are normalized to remove the effect of varying loads acting on the structure and desensitized to reduce the probability of false alarm before being used to train the statistical engine. Damage detection is based on box plot outlier analysis, and damage location is determined by knowing the absolute spatial positions of the embedded sensors. This technique has been applied to both simulated and experimental data for joints made of glass fiber reinforced polymer composite, and has been shown to be effective in the automated characterization of disbonds with an acceptable level of accuracy.
Functional analysis of zebrafish microfibril-associated glycoprotein-1 (Magp1) in vivo reveals roles for microfibrils in vascular development and function
Authors: Chen Eleanor , Larson Jon D. , Ekker Stephen C.
Published: February 2006

Mutations in fibrillin-1 (FBN1) result in Marfan syndrome, demonstrating a critical requirement for microfibrils in vessel structure and function. However, the identity and function of many microfibril-associated molecules essential for vascular development and function have yet to be characterized. In our morpholino-based screen for members of the secretome required for vascular development, we identified a key player in microfibril formation in zebrafish embryogenesis. Microfibril-associated glycoprotein-1 (MAGP1) is a conserved protein found in mammalian and zebrafish microfibrils. Expression of magp1 mRNA is detected in microfibril-producing cells. Analysis of a functional Magp1-mRFP fusion protein reveals localization along the midline and in the vasculature during embryogenesis. Underexpression and overexpression analyses demonstrate that specific Magp1 protein levels are critical for vascular development. Integrin function is compromised in magp1 morphant embryos, suggesting that reduced integrin–matrix interaction is the main mechanism for the vascular defects in magp1 morphants. We further show that Magp1 and fibrillin-1 interact in vivo. This study implicates MAGP1 as a key player in microfibril formation and integrity during development. The essential role for MAGP1 in vascular morphogenesis and function also supports a wide range of clinical applications, including therapeutic targets in vascular disease and cardiovascular tissue engineering.
Relation between air pollution and allergic rhinitis in Taiwanese schoolchildren
Authors: Hwang Bing-Fang , Jaakkola Jouni JK , Lee Yung-Ling , Lin Ying-Chu , Leon Guo Yue-liang
Published: February 2006

Background

Recent findings suggest that exposure to outdoor air pollutants may increase the risk of allergic rhinitis. The results of these studies are inconsistent, but warrant further attention. The objective of the study was to assess the effect of relation between exposure to urban air pollution and the prevalence allergic rhinitis among school children.

Methods

We conducted a nationwide cross-sectional study of 32,143 Taiwanese school children. We obtained routine air-pollution monitoring data for sulphur dioxide (SO2), nitrogen oxides (NOx), ozone (O3), carbon monoxide (CO), and particles with an aerodynamic diameter of 10 μm or less (PM10). A parent-administered questionnaire provided information on individual characteristics and indoor environments (response rate 92%). Municipal-level exposure was calculated using the mean of the 2000 monthly averages. The effect estimates were presented as odds ratios (ORs) per 10 ppb change for SO2, NOx, and O3, 100 ppb change for CO, and 10 μg/m3change for PM10.

Results

In two-stage hierarchical model adjusting for confounding, the prevalence of allergic rhinitis was significantly associated with SO2(adjusted odds ratio (OR) = 1.43, 95% confidence interval (CI): 1.25, 1.64), CO (aOR = 1.05, 95% CI: 1.04, 1.07), and NOx (aOR = 1.11, 95% CI: 1.08, 1.15). Contrary to our hypothesis, the prevalence of allergic rhinitis was weakly or not related to O3(aOR = 1.05, 95% CI: 0.98, 1.12) and PM10(aOR = 1.00, 95% CI: 0.99, 1.02).

Conclusion

Persistent exposure to NOx, CO, and SO2may increase the prevalence of allergic rhinitis in children.
Release of Ca2+ and Mg2+ from yeast mitochondria is stimulated by increased ionic strength
Authors: Bradshaw Patrick C , Pfeiffer Douglas R
Published: February 2006

Background

Divalent cations are required for many essential functions of mitochondrial metabolism. Yet the transporters that mediate the flux of these molecules into and out of the mitochondrion remain largely unknown. Previous studies in yeast have led to the molecular identification of a component of the major mitochondrial electrophoretic Mg2+uptake system in this organism as well as a functional mammalian homolog. Other yeast mitochondrial studies have led to the characterization of an equilibrative fatty acid-stimulated Ca2+transport activity. To gain a deeper understanding of the regulation of mitochondrial divalent cation levels we further characterized the efflux of Ca2+and Mg2+from yeast mitochondria.

Results

When isolated mitochondria from the yeastSaccharomyces cerevisiaewere suspended in a salt-based suspension medium, Ca2+and Mg2+were released from the matrix space. Release did not spontaneously occur in a non-ionic mannitol media. When energized mitochondria were suspended in a mannitol medium in the presence of Ca2+they were able to accumulate Ca2+by the addition of the electrogenic Ca2+ionophore ETH-129. However, in a KCl or choline Cl medium under the same conditions, they were unable to retain the Ca2+that was taken up due to the activation of the Ca2+efflux pathway, although a substantial membrane potential driving Ca2+uptake was maintained. This Ca2+efflux was independent of fatty acids, which have previously been shown to activate Ca2+transport. Endogenous mitochondrial Mg2+was also released when mitochondria were suspended in an ionic medium, but was retained in mitochondria upon fatty acid addition. When suspended in a mannitol medium, metal chelators released mitochondrial Mg2+, supporting the existence of an external divalent cation-binding site regulating release. Matrix space Mg2+was also slowly released from mitochondria by the addition of Ca2+, respiratory substrates, increasing pH, or the nucleotides ATP, ADP, GTP, and ATP-gamma-S.

Conclusion

In isolated yeast mitochondria Ca2+and Mg2+release was activated by increased ionic strength. Free nucleotides, metal ion chelators, and increased pH also stimulated release. In yeast cells this release is likely an important mechanism in the regulation of mitochondrial matrix space divalent cation concentrations.
PDB-UF: database of predicted enzymatic functions for unannotated protein structures from structural genomics
Authors: von Grotthuss Marcin , Plewczynski Dariusz , Ginalski Krzysztof , Rychlewski Leszek , Shakhnovich Eugene I
Published: February 2006

Background

The number of protein structures from structural genomics centers dramatically increases in the Protein Data Bank (PDB). Many of these structures are functionally unannotated because they have no sequence similarity to proteins of known function. However, it is possible to successfully infer function using only structural similarity.

Results

Here we present the PDB-UF database, a web-accessible collection of predictions of enzymatic properties using structure-function relationship. The assignments were conducted for three-dimensional protein structures of unknown function that come from structural genomics initiatives. We show that 4 hypothetical proteins (with PDB accession codes: 1VH0, 1NS5, 1O6D, and 1TO0), for which standard BLAST tools such as PSI-BLAST or RPS-BLAST failed to assign any function, are probably methyltransferase enzymes.

Conclusion

We suggest that the structure-based prediction of an EC number should be conducted having the different similarity score cutoff for different protein folds. Moreover, performing the annotation using two different algorithms can reduce the rate of false positive assignments. We believe, that the presented web-based repository will help to decrease the number of protein structures that have functions marked as "unknown" in the PDB file.

Availability

http://paradox.harvard.edu/PDB-UF and http://bioinfo.pl/PDB-UF
A methodology for the structural and functional analysis of signaling and regulatory networks
Authors: Klamt Steffen , Saez-Rodriguez Julio , Lindquist Jonathan A , Simeoni Luca , Gilles Ernst D
Published: February 2006

Background

Structural analysis of cellular interaction networks contributes to a deeper understanding of network-wide interdependencies, causal relationships, and basic functional capabilities. While the structural analysis of metabolic networks is a well-established field, similar methodologies have been scarcely developed and applied to signaling and regulatory networks.

Results

We propose formalisms and methods, relying on adapted and partially newly introduced approaches, which facilitate a structural analysis of signaling and regulatory networks with focus on functional aspects. We use two different formalisms to represent and analyze interaction networks: interaction graphs and (logical) interaction hypergraphs. We show that, in interaction graphs, the determination of feedback cycles and of all the signaling paths between any pair of species is equivalent to the computation of elementary modes known from metabolic networks. Knowledge on the set of signaling paths and feedback loops facilitates the computation of intervention strategies and the classification of compounds into activators, inhibitors, ambivalent factors, and non-affecting factors with respect to a certain species. In some cases, qualitative effects induced by perturbations can be unambiguously predicted from the network scheme. Interaction graphs however, are not able to capture AND relationships which do frequently occur in interaction networks. The consequent logical concatenation of all the arcs pointing into a species leads to Boolean networks. For a Boolean representation of cellular interaction networks we propose a formalism based on logical (or signed) interaction hypergraphs, which facilitates in particular a logical steady state analysis (LSSA). LSSA enables studies on the logical processing of signals and the identification of optimal intervention points (targets) in cellular networks. LSSA also reveals network regions whose parametrization and initial states are crucial for the dynamic behavior.

We have implemented these methods in our software tool CellNetAnalyzer (successor of FluxAnalyzer) and illustrate their applicability using a logical model of T-Cell receptor signaling providing non-intuitive results regarding feedback loops, essential elements, and (logical) signal processing upon different stimuli.

Conclusion

The methods and formalisms we propose herein are another step towards the comprehensive functional analysis of cellular interaction networks. Their potential, shown on a realistic T-cell signaling model, makes them a promising tool.
FastGroupII: A web-based bioinformatics platform for analyses of large 16S rDNA libraries
Authors: Yu Yanan , Breitbart Mya , McNairnie Pat , Rohwer Forest
Published: February 2006

Background

High-throughput sequencing makes it possible to rapidly obtain thousands of 16S rDNA sequences from environmental samples. Bioinformatic tools for the analyses of large 16S rDNA sequence databases are needed to comprehensively describe and compare these datasets.

Results

FastGroupII is a web-based bioinformatics platform to dereplicate large 16S rDNA libraries. FastGroupII provides users with the option of four different dereplication methods, performs rarefaction analysis, and automatically calculates the Shannon-Wiener Index and Chao1. FastGroupII was tested on a set of 16S rDNA sequences from coral-associated Bacteria. The different grouping algorithms produced similar, but not identical, results. This suggests that 16S rDNA datasets need to be analyzed in multiple ways when being used for community ecology studies.

Conclusion

FastGroupII is an effective bioinformatics tool for the trimming and dereplication of 16S rDNA sequences. Several standard diversity indices are calculated, and the raw sequences are prepared for downstream analyses.