bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic unfolding of a regulatory subunit of cAMP‐dependent protein kinase by capillary electrophoresis: Impact of cAMP dissociation on protein stability
Authors: Gavina Jennilee M. A. , Das Rahul , Britz‐McKibbin Philip 
Published: October 2006

AbstractCharacterization of the unfolding dynamics of a recombinant type IA regulatory subunit (RIα) of cyclic adenosine monophosphate (cAMP)‐dependent protein kinase (cAPK) was examined by CE with UV detection. Electrophoretic separation of RIα by CE in a buffer devoid of cAMP resulted in rapid dissociation of the complex from the original sample due to the high negative mobility of the ligand relative to receptor. This process enabled in‐capillary generation of cAMP‐stripped RIα, which was used to estimate the apparent dissociation constant (Kd) of 0.6 ± 0.2 μM. A comparison of RIα dynamic unfolding processes with urea denaturation was performed by CE with (i.e., RIα–cAMP) and without (i.e., cAMP‐stripped RIα) excess cAMP in the buffer during electromigration. The presence of cAMP in the buffer confirmed greater stabilization of the protein, as reflected by a higher standard free energy change (ΔGU°) of 10.1 ± 0.5 kcal·mol+1 and greater cooperativity in unfolding (m) of −2.30 ± 0.11 kcal·mol−1M−1. CE offers a rapid, yet versatile platform for probing the thermodynamics of cAPK and other types of receptor–ligand complexes in free solution.
Modulation of connexin expression and gap junction communication in astrocytes by the gram‐positive bacterium S. aureus
Authors: Esen Nilufer , Shuffield Debbie , SYED Mohsin MD. , Kielian Tammy 
Published: October 2006

AbstractGap junctions establish direct intercellular conduits between adjacent cells and are formed by the hexameric organization of protein subunits called connexins (Cx). It is unknown whether the proinflammatory milieu that ensues during CNS infection with S. aureus, one of the main etiologic agents of brain abscess in humans, is capable of eliciting regional changes in astrocyte homocellular gap junction communication (GJC) and, by extension, influencing neuron homeostasis at sites distant from the primary focus of infection. Here we investigated the effects of S. aureus and its cell wall product peptidoglycan (PGN) on Cx43, Cx30, and Cx26 expression, the main Cx isoforms found in astrocytes. Both bacterial stimuli led to a time‐dependent decrease in Cx43 and Cx30 expression; however, Cx26 levels were elevated following bacterial exposure. Functional examination of dye coupling, as revealed by single‐cell microinjections of Lucifer yellow, demonstrated that both S. aureus and PGN inhibited astrocyte GJC. Inhibition of protein synthesis with cyclohexamide (CHX) revealed that S. aureus directly modulates, in part, Cx43 and Cx30 expression, whereas Cx26 levels appear to be regulated by a factor(s) that requires de novo protein production; however, CHX did not alter the inhibitory effects of S. aureus on astrocyte GJC. The p38 MAPK inhibitor SB202190 was capable of partially restoring the S. aureus‐mediated decrease in astrocyte GJC to that of unstimulated cells, suggesting the involvement of p38 MAPK‐dependent pathway(s). These findings could have important implications for limiting the long‐term detrimental effects of abscess formation in the brain which may include seizures and cognitive deficits. © 2006 Wiley‐Liss, Inc.
The case against JIVE
Authors: Davidson Russell , MacKinnon James G. 
Published: October 2006

AbstractWe perform an extensive series of Monte Carlo experiments to compare the performance of two variants of the ‘jackknife instrumental variables estimator’, or JIVE, with that of the more familiar 2SLS and LIML estimators. We find no evidence to suggest that JIVE should ever be used. It is always more dispersed than 2SLS, often very much so, and it is almost always inferior to LIML in all respects. Interestingly, JIVE seems to perform particularly badly when the instruments are weak. Copyright © 2006 John Wiley & Sons, Ltd.
Estimation and comparison of treasury auction formats when bidders are asymmetric
Authors: Armantier Olivier , SbaÏ Erwann 
Published: October 2006

AbstractThe structural parameters of a share‐auction model accounting for asymmetries across bidders, as well as supply uncertainty, are estimated with a sample of French Treasury auctions. We find evidence of both informational and risk aversion asymmetries across bidders. A counter‐factual analysis also suggests that, in the context of the French Treasury auctions, a shift from the discriminatory to the uniform‐price format would simultaneously benefit the French Treasury and the auctions' participants. Copyright © 2006 John Wiley & Sons, Ltd.
Wealth dynamics: reducing noise in panel data
Authors: Hill Daniel H. 
Published: October 2006

AbstractAlthough the asset data from the Health and Retirement Study (HRS) is of very high quality, there is sufficient noise to frustrate attempts to study saving behaviour by examining wave‐to‐wave change in wealth. In this research, we attempt to reduce noise by means of reactive‐dependent interviewing in which respondents with large inexplicable changes in assets between 1998 and 2000 are called back by HRS interviewers, presented with their prior reports and asked to reconcile the data. We achieved reconciliation for 1255 households (2479 net‐worth components) and, as a result, the variance in measured change for the entire sample of 11,583 households with the same financial respondents in both waves was cut in half. The empirical validity of the data also appears to have been improved. The correlation of gross change in net worth and income, for instance, increased from an insignificant negative to a highly significant positive value. Although reconciliation of large asset changes marginally improves the goodness of fit of multivariate models, there remains sufficient noise in the asset‐change data to require analysts to employ additional methods to reduce the influence of outliers. Copyright © 2006 John Wiley & Sons, Ltd.
Assessing the effects of measurement errors on the estimation of production functions
Authors: Ornaghi Carmine 
Published: October 2006

AbstractThis article explores to what extent the poor results that are often found when estimating parameters of production functions can be attributed to measurement errors, due to the use of common price deflators across firms. Because of the lack of detailed micro‐economic data, econometricians have to rely on industry‐wide deflators when computing outputs and intermediate inputs. A unique feature of the longitudinal data used in this paper is that it reports firm‐level prices. This allows for a comparative assessment of production function parameters where the outputs and intermediate inputs are computed using both firm‐specific prices and industry‐wide deflators. The empirical results presented in this paper show that the use of common deflators across firms leads to lower scale estimates, mainly because of a large downward bias in the estimated coefficients for labour. Copyright © 2006 John Wiley & Sons, Ltd.
Introduction to the special issue: Youth mentoring: Bridging science with practice
Authors: DuBois David L. , Rhodes Jean E. 
Published: October 2006

AbstractInitiatives to promote mentoring relationships in the lives of young people have become immensely popular in recent years. Programs with this aim now number well into the thousands and benefit from significant levels of governmental, corporate, and philanthropic support. The research base that is necessary to inform the practice of mentoring, by comparison, has lagged behind. To address the field's need for a stronger scientific foundation, MENTOR/National Mentoring Partnership convened the National Research Summit on Mentoring in 2003. A policy brief that resulted from the summit identified several priority areas for future research on youth mentoring, as well as strategic mechanisms to support this work. This special issue features reports from working groups at the summit that were organized around the following themes: evaluation and research methodology, relationships, programs, contexts, special populations, developmental and cultural perspectives, and community organizing and advocacy. Collectively, the reports highlight the need for research to clarify a wide range of important theoretical and pragmatic issues in efforts to promote effective mentoring of youth. © 2006 Wiley Periodicals, Inc.
Research methodology and youth mentoring
Authors: DuBois David L. , Doolittle Fred , Yates Brian T. , Silverthorn Naida , Tebes Jacob Kraemer 
Published: October 2006

AbstractMentoring programs for youth have grown tremendously in popularity in recent years and in many important respects reflect core principles of community psychology. Mentoring of youth is a complex phenomenon, however, with a range of significant processes occurring at the levels of individual youth and their mentors, youth–mentor relationships and other interpersonal systems, programs, and the larger policy context. The research methods used to study youth mentoring need to be well suited to capturing this complexity. In this article, we argue, furthermore, that investigations of youth mentoring relationships and programs should be tailored to address concerns associated with each major phase of the intervention research cycle (i.e., preintervention, intervention, and preventive service systems research). Existing research pertinent to these differing phases frequently has not employed state‐of‐the‐art methodology in the areas of sampling, design, assessment, and analysis. We also find that there are important gaps in the types of research conducted, and that in many instances, needed linkages across phases of the research cycle are lacking. Recommendations for strengthening future research on youth mentoring are discussed. © 2006 Wiley Periodicals, Inc.
Positive youth development, willful adolescents, and mentoring
Authors: Larson Reed 
Published: October 2006

AbstractThis article describes positive youth development as a process in which young people's capacity for being motivated by challenge energizes their active engagement in development. The first part of the article discusses the conditions under which this motivation is activated and considers obstacles to its activation in daily life. The second part discusses ways in which caring adults, including mentors, can support this process of positive development. Several frameworks that provide models of how adults can provide needed structure and guidance while supporting youth's development as agents of their own growth are discussed. © 2006 Wiley Periodicals, Inc.
A model for the influence of mentoring relationships on youth development
Authors: Rhodes Jean E. , Spencer Renée , Keller Thomas E. , Liang Belle , Noam Gil 
Published: October 2006

AbstractAnecdotal reports of the protective qualities of mentoring relationships for youth are corroborated by a growing body of research. What is missing, however, is research on the processes by which mentors influence developmental outcomes. In this article, we present a conceptual model of the mentoring process along with a delineation of some of the current research on what makes for more effective mentoring relationships. A set of recommendations for future research is offered. © 2006 Wiley Periodicals, Inc.
Mentoring programs: A framework to inform program development, research, and evaluation
Authors: Karcher Michael J. , Kuperminc Gabriel P. , Portwood Sharon G. , Sipe Cynthia L. , Taylor Andrea S. 
Published: October 2006

AbstractAs mentoring programs have proliferated, considerable variation in approaches to programmatic mentoring has emerged. Concomitant confusion exists about the context, structure, and goals that constitute mentoring as a distinct intervention. This article presents a brief summary of what is currently known about different approaches to mentoring and proposes a framework that identifies both the common and the specific elements among different youth mentoring approaches. Rather than focusing solely on the participants and contexts of mentoring programs, such as peer‐ or school‐based mentoring, as the key elements that differentiate programs, the authors suggest that more fruitful program development and research will result from a closer examination of the context, structure, and goals of programs, as well as of three critical program elements: content, infrastructure, and dosage. To understand better how and under what conditions mentoring works, program developers and researchers should test hypotheses regarding the influences of these program elements based on theory‐driven expectations about the interrelationships among proximal, enabling, and distal outcomes of mentoring programs. © 2006 Wiley Periodicals, Inc.
Community contexts for mentoring
Authors: Hamilton Stephen F. , Agnes Hamilton Mary , Hirsch Barton J. , Hughes Jan , King Jacqueline , Maton Kenneth 
Published: October 2006

AbstractMentoring programs attempt to foster a relationship that is too often missing from the lives of disadvantaged children and youth. However, in view of both the power and the limitations of mentoring programs, it is important to understand how mentoring occurs naturally. Assuming an ecological perspective, we examine mentoring in four contexts: classrooms, youth development organizations, work and service‐learning, and faith‐ based organizations. Although none has been studied in sufficient depth, and no research has been found on natural mentoring in faith‐based organizations, available evidence indicates that such mentoring adds to young people's intellectual, psychological and emotional, social, and, to a lesser extent, physical assets. This review poses many questions for future research, including fundamental ones about the prevalence of mentoring in these contexts, the circumstances in which it arises, and its risks and benefits. Nonetheless, the evidence is sufficient to encourage practitioners to promote mentoring relationships of youth and adults in all of these contexts. © 2006 Wiley Periodicals, Inc.
Anatomy of the frontal gland and ultramorphology of the frontal tube in the soldier caste of species of Nasutitermitinae (Isoptera, Termitidae)
Authors: A. Santos Conceicao , M. Costa‐Leonardo Ana 
Published: October 2006

AbstractAll termite species (Isoptera) are eusocial. These insects live in societies where the division of labor is a predominant characteristic, conditioned by the presence of castes with different morphology, ontogeny, and development. The soldier caste is unique among social insects and it is responsible for colony defense. Soldiers belonging to the Nasutitermitinae subfamily are very peculiar, since they may be polymorphic and present a nasus in addition to either developed or vestigial mandibles. The defensive secretions of soldiers of the neotropical Nasutitermitinae have been the aim of several chemical studies, but few data exist concerning the anatomy and histology of the exocrine glands. This article presents a comparative study on the anatomy of the frontal gland of soldiers of several Nasutitermitinae species:Syntermes dirus(Burmeister),Syntermes nanus(Constantino),Constrictotermes cyphergaster(Silvestri),Nasutitermes corniger(Motschulsky) andVelocitermes heteropterus(Silvestri), with emphasis on the ultramorphology and ultrastructure of the frontal tube. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
The tri‐segmented limbs of therian mammals: kinematics, dynamics, and self‐stabilization—a review
Authors: Fischer Martin S. , Blickhan Reinhard 
Published: October 2006

AbstractThe evolution of therian mammals is to a large degree marked by changes in their motion systems. One of the decisive transitions has been from the sprawled, bi‐segmented to the parasagittal, tri‐segmented limb. Here, we review aspects of the tri‐segmented limb in locomotion which have been elucidated in our research groups in the last 10 years. First, we report the kinematics of the tri‐segmented therian limb from mouse to elephant in order to explore general principles of the therian limb configuration and locomotion. Torques will be reported from a previous paper (Witte et al., 2002. J Exp Biol 205:1339–1353) for a better understanding of the anti‐gravity work of all limb joints. The stability of a limb in z‐configuration will be explained and its advantage with respect to other potential solutions from modeling will be discussed. Finally, we describe how the emerging concept of self‐stability can be explained for a tri‐segmented leg template and how it affects the design of the musculoskeletal system and the operation of legs during locomotion. While locomotion has been considered as mainly a control problem in various disciplines, we stress the necessity to reduce control as much as possible. Central control can be cheap if the limbs are “intelligent” by means of their design. Gravity‐induced movements and self‐stability seem to be energy‐saving mechanisms. J. Exp. Zool. 305A, 2006. © 2006 Wiley‐Liss, Inc.
Analysis of strategies to improve cost effectiveness of blood cultures
Authors: Zwang Oren , Albert Richard K. 
Published: October 2006

AbstractBACKGROUNDApproximately 90% of all blood cultures grow no organisms (ie, are true negatives), and 5% are thought to represent contaminants (ie, are false positives). The cost effectiveness of blood cultures could therefore be improved by developing rules that safely decreased the number of cultures drawn from patients with a low likelihood of having bacteremia and/or by improving the process of obtaining cultures, thereby decreasing the number of contaminants. We analyzed the potential effects of these two approaches.METHODSWe annualized the hospital costs and lengths of stay for patients with true‐negative and false‐positive blood cultures from a retrospective analysis of 939 sets of cultures drawn in January 2002.RESULTSOf the 939 blood culture sets, 816 (87%) were true negatives and generated annualized costs of approximately $750,000. Although only 56 (6%) of the blood culture sets were false positives, they resulted in annualized costs of $1.4‐$1.8 million and added an estimated 1450‐2200 extra hospital days/year.CONCLUSIONSDespite there being nearly 15 times as many true‐negative blood cultures as false positive ones, far greater improvements in resource utilization would result from reducing the number of contaminated blood cultures than by reducing the number of true negatives. The potential savings from this approach are of sufficient magnitude to justify investing considerable resources to attaining this goal. Journal of Hospital Medicine 2006;1:272–276. © 2006 Society of Hospital Medicine.
Magnetic resonance angiography reveals therapeutic enlargement of collateral vessels induced by VEGF in a murine model of peripheral arterial disease
Authors: Greve Joan M. , Chico Timothy J. , Goldman Hope , Bunting Stuart , Peale Franklin V. , Daugherty Ann , van Bruggen Nicholas , Williams Simon P. 
Published: October 2006

AbstractPurposeTo quantify spontaneous and therapeutic arteriogenesis in vivo in a murine model of peripheral arterial disease using magnetic resonance angiography.Materials and MethodsMale, 8–12‐week‐old, C57/BL6 mice underwent femoral artery ligation; 21 days later, 2 mg/kg recombinant murine VEGF165, formulated for slow release, was injected into the ipsilateral gastrocnemius. The spontaneous (following ligation) and therapeutic (following vascular endothelial growth factor (VEGF)) formation of collateral vessels was quantified using 3D magnetic resonance angiography on a small‐bore 4.7T system. Therapeutically induced angiogenesis and blood flow were quantified using an in situ anti‐platelet endothelial cell adhesion molecule (PECAM) 1 radioimmunoassay and radiolabeled microsphere deposition, respectively.ResultsSpontaneous arteriogenesis was visible in all animals five days after ligation. VEGF treatment doubled the arteriogenic response five days after treatment compared to vehicle (cross‐sectional area of vessels: 0.96 vs. 0.46 mm2,P< 0.01). VEGF also induced angiogenesis (PECAM1 levels 191% of vehicle,P< 0.05) and increased blood flow specific to the injection site (57 vs. 7 mL/minute/100 g,P< 0.05).ConclusionThe presented methodology allowed in vivo quantification of spontaneous arteriogenesis in a murine model of peripheral arterial disease and demonstrated that therapeutic enlargement of collateral vessels is possible with VEGF. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Asymptotic domination of operators on Köthe function spaces and convergence of sequences
Authors: Sánchez Pérez E. A. 
Published: October 2006

AbstractWe study the asymptotic behavior of Maurey–Rosenthal type dominations for operators on Köthe function spaces which satisfy norm inequalities that define weak q ‐concavity properties. In particular, we define and study two new classes of operators that we call α ‐almost q ‐concave and qα ‐concave operators (1 ≤ q < ∞, 0 ≤ α < 1). We also provide a factorization theorem through real interpolation spaces for qα ‐concave operators. We also discuss some direct consequences of these results regarding the strong convergence of sequences on Köthe function spaces. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Longitudinal study of the motor response to levodopa in Parkinson's disease
Authors: Clissold Benjamin G. , McColl Craig D. , Reardon Katrina R. , Shiff Mark , Kempster Peter A. 
Published: October 2006

AbstractIn this prospective study of 34 patients with Parkinson's disease, measurements of the short duration levodopa motor response have been performed in defined off states at 3 yearly intervals over a mean period of 11.4 years from the point of commencement of levodopa treatment. Twenty‐two patients were still available for study; 10 had died and 2 were lost to follow‐up. The levodopa motor response amplitude increases over the first 5 years of treatment, and thereafter, on and off scores worsen in parallel with conservation of the response. Patients who developed motor fluctuations within the first 5 years of treatment had, on average, a stronger response to levodopa with significantly better on phase motor function (P = 0.003). Although the proportion of “midline” motor disability (affecting gait, balance, and cranial motor function) increases with time, these deficits do not actually become unresponsive to levodopa. Patients who developed dementia had a significantly more rapid decline in motor function. The latest graph of serial scores for the whole cohort shows an upward curving or exponential increase in motor disability after the first decade of treatment. Applying a notional untreated disability line to this graph—an estimate of the disability that would have accrued if drugs had never been given—we suggest that the long‐duration response to levodopa eventually runs down with disease progression. © 2006 Movement Disorder Society