bluuebunny/crossref_metadata_2025 huggingface dataset:
Promises and pitfalls of first trimester sonographic markers in the detection of fetal aneuploidy
Authors: Borrell Antoni
Published: December 2008

First trimester sonographic markers are the only markers achieving detection rates above 50% in the prenatal detection of fetal aneuploidy. Although potentially they are the best markers, some concerns have arisen about its clinical application. Pitfalls may be due to inability to examine the markers, incorrect assessment, or incorrect interpretation of the findings. Markers may be unable to be examined due to maternal (maternal body habitus, previous surgery) or fetal reasons (incompatible fetal position or fetal movements). Causes of incorrect interpretation may be insufficient image magnification, incorrect caliper placement (nuchal translucency), incorrect insonation angle (nasal bone), venous contamination (ductus venosus), or arterial contamination (tricuspid regurgitation), among others. Venous contamination in ductus venosus waveforms may mimic an abnormal blood flow when it is normal, and the opposite can also occur. Finally, incorrect interpretation of a substantially increased nuchal translucency may lead to a false impression of an ominous fetal prognosis or may be confounded with a cystic hygroma. Copyright © 2008 John Wiley & Sons, Ltd.
First‐trimester contingent screening for Down syndrome can reduce the number of nuchal translucency measurements required
Authors: Vadiveloo Thenmalar , Crossley Jennifer A. , Aitken David A.
Published: December 2008

Background

To assess the performance of a two‐stage screening protocol for Down syndrome based on initial serum marker analysis for all women and nuchal translucency (NT) measurement only in women with intermediate risks.

Methods

Biochemical marker and NT data in 10 189 women who had had combined ultrasound and biochemical (CUB) screening, were re‐analysed using the contingent model. A risk was calculated from the results of the pregnancy‐associated plasma protein A (PAPP‐A) and free β human chorionic gonadotrophin (FβhCG) measurements and maternal age. For risks between 1 in 42 and 1 in 1000, the likelihood ratio from the NT measurement was incorporated and assessed against a final cut‐off risk of 1 in 250.

Results

A total of 3.1% unaffected and 61.4% Down syndrome pregnancies had risks ≥ 1: 42. In women with risks < 1 in 42 and > 1 in 1000 (29%), a further 2.7% unaffected pregnancies and 27.3% Down syndrome pregnancies had risks above 1 in 250 when NT was incorporated. Overall detection rate was 88.6%, and false positive rate 5.8% (compared with 90.9% and 6.4% for CUB screening). NT measurements were required in 29% of women.

Conclusions

Within first‐trimester, contingent screening provides good sensitivity and specificity with the potential for considerable saving in ultrasound resources. Copyright © 2008 John Wiley & Sons, Ltd.
Planar aqueous electrode technique for polymer impedance spectroscopy
Authors: Bai T. , Bradshaw R.D. , Ramanathan T. , Nunalee F.N. , Shull K.R. , Mason T.O. , Brinson L.C.
Published: December 2008

In this article, we develop an aqueous electrode technique that can adapt to complex sample geometries while maintaining perfect contact between the electrodes and the measured sample. In contrast to surface deposited electrodes, the aqueous electrode technique measures the ionic conduction of the polymer sample instead of the inherent dielectric properties of the polymer. Polymer ionic conduction is often related to the polymer thermodynamic state, which itself is closely linked to many other polymer properties. As such, the aqueous electrode method provides an approach to conduct in situ monitoring of polymer samples subjected to degradation; changes in the impedance provide an indication of polymer sample degradation. This article presents the aqueous electrode setup and discusses experimental results obtained using it. Changes in the impedance response of PVC and polyimide films due to moisture absorption, ionic conduction, pinholes, chemical degradation, and temperature are presented. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers
Prescribing melatonin for ADHD
Authors: Ilves Peter
Published: December 2008

Dr Peter Ilves describes the challenge of prescribing melatonin in primary care for the treatment of ADHD in children, an off‐licence indication, and the lack of available guidance. Copyright © 2008 Wiley Interface Ltd
Cephalosporins – do they still have a role in primary care?
Authors: Thompson Angus
Published: December 2008

Cephalosporins are barely mentioned in the HPA's guidance on treating infection and there is rising concern over their role in the development of C. difficile. Angus Thompson argues that, with suitable alternatives available, there is little reason to continue prescribing them. Copyright © 2008 Wiley Interface Ltd
Guide to the management of bacterial skin infections
Authors: Ni Riain Una
Published: December 2008

Bacterial skin infections are usually caused by Staph. aureus or Strep. pyogenes and can be successfully managed with topical or, for more severe disease, systemic antibiotics. Our Drug review discusses their features and recommended treatment, followed by sources of further information. Copyright © 2008 Wiley Interface Ltd
Characterization of silver selenide thin films grown on Cr‐covered Si substrates
Authors: Mohanty Bhaskar Chandra , Malar P. , Osipowicz Thomas , Murty B. S. , Varma Shikha , Kasiviswanathan S.
Published: December 2008

Thermal stability of silver selenide thin films formed from the solid‐state reaction of Ag‐Se diffusion couples on Si substrates covered with a thin Cr film, is investigated. Glancing angle X‐ray diffraction (GXRD), XPS, atomic force microscopy (AFM) and Rutherford backscattering spectrometry (RBS) are used to characterize the as‐deposited films and those annealed at 100, 200, 300, and 400 °C. The results reveal the formation of polycrystalline orthorhombic silver selenide films that remain stable without compositional change upon thermal annealing, in marked contrast to the agglomeration exhibited by silver selenide films deposited on Si without Cr film. The improvement in the thermal stability is attributed to compressive stress relief by a grainy morphology with large surface area, the formation of which is promoted by partially oxidized Cr adhesion film. Copyright © 2008 John Wiley & Sons, Ltd.
Overlayer thickness determination by XPS using the multiline approach
Authors: Jablonski A. , Zemek J.
Published: December 2008

An important analytical application of x‐ray photoelectron spectroscopy is the possibility of determining the overlayer thickness in the nanometer range. The relevant procedure should be based on a realistic theoretical model relating the photoelectron signal intensities, measured for the overlayer and for the substrate, to the overlayer thickness. In the most frequently used procedure, we derive the thickness from the ratio of intensity measured for the overlayer and intensity measured for the substrate. We may expect that the resulting thickness depends on the pair of intensities selected for analysis. This is due to the fact that each calculated intensity has a certain systematic error associated with accuracy of parameters used in calculations.

We consider here a possibility of using more than two intensities, for a given element, in the procedure of thickness determination. In this way, we expect that the analysis is more accurate due to the fact that the systematic errors are averaged. In the past, similar approach has been successfully applied to the procedure of surface composition determination. To test the proposed multiline approach, the Au 4f, Ni 2p, and Ni 3p intensities were measured for a series of Ni overlayers deposited on the Au substrate. It has been found that the proposed approach well performs at relatively large overlayer thicknesses. It provides values that are averages of values obtained from other methods. At small overlayer thicknesses, we observe a scatter of thicknesses obtained from different methods which can be due to the discontinuity of the overlayer. Copyright © 2008 John Wiley & Sons, Ltd.
Fear‐avoidance‐ and endurance‐related responses to pain: Development and validation of the Avoidance‐Endurance Questionnaire (AEQ)
Authors: Hasenbring Monika I. , Hallner Dirk , Rusu Adina C.
Published: December 2008

Aim of investigation: Recent research indicated wide variability regarding pain‐related cognitive/affective and behavioral responses to pain, showing that fear‐avoidance responses (FAR) and endurance‐responses (ER) play a prominent role in the maintenance of low back pain (LBP). Until now, there is a lack of reliable and valid instruments covering FAR and ER.

Methods: A pool of 60 items, derived from the Kiel Pain Inventory was answered by 191 LBP patients. Principle components analyses (PCA) was used to explore the factor structure creating the Avoidance‐Endurance Questionnaire (AEQ). Validity was calculated using the criteria variables pain intensity, disability, chronic pain grades (CPG) and number of sick days, further self‐report measures (Fear‐Avoidance Beliefs Questionnaire FABQ, Pain Anxiety Symptoms Scale PASS, Tampa Scale of Kinesiophobia TSK and Beck Depression Inventory BDI) evaluating construct validity.

Results: PCA revealed five AEQ–FAR scales with anxiety/depression, catastrophizing, help‐/hopelessness, avoidance of social activities, avoidance of physical activities, and four AEQ–ER scales with positive mood, thought suppression, pain persistence behavior and humor/distraction. All scales revealed high internal consistency. As expected, FAR scales showed positive associations with pain, disability and other FAR variables (correlations between r=.26 and r=.58), whereas ER scales showed negative associations (between r=−.19 and −.48). The only exception referred to positive correlations between both, FAR and ER and pain intensity.

Conclusions: The AEQ has shown as a reliable and valid measure to assess pattern of fear‐avoidance and endurance‐related responses to pain. Both aspects seem to play a role in the maintenance of LBP.
Cortical changes in complex regional pain syndrome (CRPS)
Authors: Swart C.M.A. Karin , Stins John F. , Beek Peter J.
Published: December 2008

Recent research suggests that changes in cortical structures can contribute to the pathophysiology of Complex Regional Pain Syndrome (CRPS). This review provides an overview of studies showing cortical involvement in CRPS, including mislocalizations of tactile stimuli, changes in size and organization of the somatosensory map, changes in motor cortex representation and body perception disturbances. In addition, we review experimental treatment approaches, such as mirror therapy and motor imagery programs, aimed at restoring the integrity of neural processing in the sensory‐motor cortex in individuals with CRPS. The intervention effects are promising and can be theoretically motivated on the basis of established principles of neural organization, although important questions concerning the precise neural mechanisms of action remain unanswered.
Psychotherapy for personality disorders: Short-term day hospital psychotherapy versus outpatient individual therapy – a randomized controlled study
Authors: Arnevik Espen , Wilberg Theresa , Urnes Øyvind , Johansen Merete , Monsen Jon T. , Karterud Sigmund
Published: December 2008

This article describes the results of an eight-month follow-up investigation from a randomized controlled trial of day hospital psychotherapy (DHP) compared with outpatient individual psychotherapy (OIP) for patients with personality disorders (N = 114). The patients were randomly assigned to either 18 weeks of day hospital treatment followed by long-term conjoint group and individual therapy (DHP), or outpatient individual psychotherapy (OIP). The main outcome measures were attrition rate, suicide attempts, suicidal thoughts, self-injury, psychosocial functioning, symptom distress, and interpersonal and personality problems. The study showed a low dropout rate and a moderate improvement on a broad range of clinical measures for both treatments. However, there was no indication of the superiority of one treatment over the other. Neither was there any indication that day hospital treatment was better for the most poorly functioning patients. Further studies will follow this group of patients for the next few years, the results of which may have implications for resource allocation and the organization of mental health services for patients with personality disorders.
Suicide attempts in bulimia nervosa: Personality and psychopathological correlates
Authors: Forcano Laura , Fernández-Aranda Fernando , Álvarez-Moya Eva , Bulik Cynthia , Granero Roser , Gratacòs Mònica , Jiménez-Murcia Susana , Krug Isabel , Mercader Josep M. , Riesco Nadine , Saus Ester , Santamaría Juan José , Estivill Xavier
Published: December 2008

Background

Little evidence exists about suicidal acts in eating disorders and its relation with personality. We explored the prevalence of lifetime suicide attempts (SA) in women with bulimia nervosa (BN), and compared eating disorder symptoms, general psychopathology, impulsivity and personality between individuals who had and had not attempted suicide. We also determined the variables that better correlate with of SA.

Method

Five hundred sixty-six BN outpatients (417 BN purging, 47 BN non-purging and 102 subthreshold BN) participated in the study.

Results

Lifetime prevalence of suicide attempts was 26.9%. BN subtype was not associated with lifetime SA (p= 0.36). Suicide attempters exhibited higher rates on eating symptomatology, general psychopathology, impulsive behaviors, more frequent history of childhood obesity and parental alcohol abuse (p< 0.004). Suicide attempters exhibited higher scores on harm avoidance and lower on self-directedness, reward dependence and cooperativeness (p< 0.002). The most strongly correlated variables with SA were: lower education, minimum BMI, previous eating disorder treatment, low self-directedness, and familial history of alcohol abuse (p< 0.006).

Conclusion

Our results support the notion that internalizing personality traits combined with impulsivity may increase the probability of suicidal behaviors in these patients. Future research may increase our understanding of the role of suicidality to work towards rational prevention of suicidal attempts.
Perceptions of Job Stress and Satisfaction Among School-Based SLPs: Challenges Versus Rewards
Authors: Caesar Lena G. , Nelson Nickola Wolf
Published: December 2008

This study utilized a survey design to gather information regarding caseload and employment factors affecting school-based speech-language pathologists' (SLP) perceptions of job stress and job satisfaction. Results indicated that respondents experienced relatively low levels of job stress and high levels of job satisfaction. The majority of respondents (95%) reported being somewhat satisfied or very satisfied with their jobs, while only one-third of respondents (35%) reported experiencing serious work problems. With the exception of caseload size, no significant relationships were found between caseload factors and job stress or satisfaction. However, one employment factor (paperwork) was a consistent predictor of all three stress measures. An analysis of open-ended responses indicated that responding SLPs were more challenged by employment-related factors than by student-related issues. Implications regarding the critical shortage of SLPs will be presented.
What? You Want Me to Do a Language Sample?
Authors: Ford Jane H. , Gaskill Mary Jo , Lemp Janice
Published: December 2008

The Speech Language Program in Orange County Public Schools (OCPS) in Orlando, FL, encourages and supports the use of language sampling as part of the diagnostic and therapeutic planning process. This article describes the protocol used for eliciting and analyzing a language sample used in OCPS. The protocol was developed with the goal of reducing reliance on self-designed analysis procedures and incorporating research information about collection and analysis procedures.
Interprofessional Approach to Auditory Processing Disorders
Authors: Lagacé Josée , Bélanger-Schaadt Margaret , Savard Jacinthe , Dubouloz Claire-Jehanne
Published: December 2008

Most of the school-aged children referred in audiology for the assessment of their central auditory functions are experiencing a variety of learning challenges. Research using neuroimaging techniques indicates that even the simplest auditory task like passive listening results in activation of multiple areas of the brain (Bellis, 2003). According to the same author, this interaction among different areas of the brain reflects an incredible degree of integration and interdependency throughout the central auditory nervous system. With that perspective in mind, interpretation of central auditory findings and intervention strategies should reflect this interdependency. The interprofessional approach—an approach that takes into account a child's auditory, language, learning, and associated characteristics—appears to ensure appropriate interpretation and management. This article illustrates an interprofessional model of intervention that is used to deliver services to school-aged children presenting with Auditory Processing Disorders (APD) and associated learning difficulties. The interprofessional team is composed of an audiologist, a speech-language pathologist (SLP), and an occupational therapist. This project is one of the initiatives at the Interprofessional University Clinic of the University of Ottawa (Canada) and has been implemented to provide rehabilitation services to children with APD using a framework based on social participation and interprofessionalism.
Speech-Language-Hearing Health Disparities in Young Children
Authors: Chase Patricia A. , Boggs Teresa L.
Published: December 2008

Communication disorders are among the most prevalent disabilities in young children. This research examined the effectiveness of a consultative model for providing speech, language, and hearing health services to preschool children in a rural Appalachian community. Outcomes from this project may be useful in other disadvantaged or underserved communities.
Cleft Palate and/or Velopharyngeal Dysfunction: Assessment and Treatment
Authors: LeDuc Judith A.
Published: December 2008

Children with cleft palate and/or velopharyngeal dysfunction often exhibit complicated clinical findings. In order to differentiate a resonance disorder from an articulatory/phonological disorder, the speech-language pathologist must be able to evaluate the function of the velopharyngeal mechanism and have knowledge of aberrant articulatory postures that create compensatory articulations. This paper will address current assessment techniques and treatment strategies for this clinical population. Methods for collaborating with the transdisciplinary cleft palate/craniofacial team will be provided.
The balance between tailoring and standardizing control
Authors: Dooms Eric , van Oijen Aswin A.
Published: December 2008

Abstract In multibusiness firms, control of subsidiaries by the corporate headquarters is shaped by two levels of factors: subsidiary‐specific factors and corporate‐wide factors. Subsidiary‐specific factors imply control that is tailor‐made to the characteristics of each individual subsidiary. Corporate‐wide factors imply control that is standardized across the subsidiaries within a firm. We argue that the balance between tailoring and standardization depends on the nature of the control mechanisms that corporate management uses to control its subsidiaries. Some mechanisms are more suited for tailoring, whereas others are more susceptible to standardization. Findings from a study of Dutch corporations reveal that control of subsidiaries can be characterized as tailored standardization. Autonomy is tailored to the individual subsidiaries within a firm. Integration, formalization, and communication are also subject to a corporate effect. Therefore, these three mechanisms are tailored to individual subsidiaries as well as standardized across the subsidiaries of a firm.
Comment: Right signals to applicants, wrong incentives for deans: business school rankings and the challenges to management education
Authors: Mau Vladimir A. , Mansilya‐Kruz Alexander V.
Published: December 2008

Abstract Based on the findings by Dewinney, Dowling and Perm‐Ajchariyawong, we point out that, while MBA rankings provide useful signals to students about their salary prospects, they also create misleading incentives for business school administrators. The inbuilt bias in favor of the traditional model of business education discourages innovation and therefore stifles responses to major challenges – such as the globalization of the business education market, the advent of life‐long education and the need for more relevance to management practice.
On the survey-propagation equations in random constraint satisfiability problems
Authors: Parisi Giorgio
Published: December 2008

In this paper we study the existence of a solution of the survey-propagation equations for a given instance of a random problem in the framework of constraint satisfiability. We consider the concrete examples of K-satisfiability and coloring. We conjecture that when the number of variables goes to infinity, the solution of the survey-propagation equations for a given instance can be obtained by finding the (supposed unique) solution of the corresponding equations on an infinite tree. We conjecture that the survey-propagation equations on a random infinite tree have a unique solution in the suitable range of parameters. We also present analytic arguments that indicate that the survey-propagation equations do have solutions in the satisfiable phase. For simplicity of notation the argument is presented in the case of the coloring problem. The same results extend to other optimization problems where exist configurations that have cost zero, i.e., in the satisfiable phase. On a random graph the solutions of the belief-propagation equations are associated with the existence of many well separated clusters of configurations (clustering states). We argue that on a random graph the belief-propagation equations have solutions almost everywhere: the statement may be sharpened by introducing the concept of quasisolution of the belief-propagation equations.
Thermally activated field assisted carrier generation and transport in N,N′-di-[(1-naphthalenyl)-N,N′-diphenyl]-(1,1′ biphenyl)-4,4′-diamine doped with 2,3,5,6-tetrafluoro-7,7′,8,8′-tetracyanoquinodimethane
Authors: Chauhan Gayatri , Srivastava Ritu , Rai Virendra Kumar , Kumar Arunandan , Bawa S. S. , Srivastava P. C. , Kamalasanan M. N.
Published: December 2008

Current density-voltage (J-V) characteristics of N,N′-di-[(1-naphthalenyl)-N,N′-diphenyl]-(1.1′ biphenyl)-4,4′-diamine (α-NPD) doped with 2,3,5,6-tetrafluoro-7,7′,8,8′-tetracyanoquinodimethane have been studied as a function of doping concentration (0–0.8 wt %) and temperature (105–300 K). The current density was found to increase with increase in doping concentration. In the doped samples as field increases above 3.3×104 V/cm the current abruptly starts increasing at a higher rate, which is ascribed as due to increased free charge carrier generation in the bulk. The enhanced free charge carrier generation is due to field assisted thermal dissociation of donor-acceptor pairs (Poole–Frenkel process) as well as charge injection at the interface. The released carriers increase the charge carrier density which brings the Fermi level near the highest occupied molecular orbital level of the α-NPD and reduces the space charge region near the interface favoring the tunneling of charge carrier across the interface, which is enough to support Ohmic conduction. The carrier generation has been found to be a thermally activated process. At higher fields (i.e., above 1.52×105 V/cm) the nonlinear J-V characteristics have been explained as due to field dependent mobility of holes.
Activity-independent and subunit-specific recruitment of functional AMPA receptors at neurexin/neuroligin contacts
Authors: Heine Martin , Thoumine Olivier , Mondin Magali , Tessier Béatrice , Giannone Grégory , Choquet Daniel
Published: December 2008

A combination of cell culture and animal studies has recently shown that adhesion between neurexins and neuroligins played important roles in synapse initiation, maturation, and function. Binding of neurexin-1β to neuroligin-1 triggers the postsynaptic clustering of the scaffold postsynaptic density protein 95, but the composition and timing of accumulation of glutamate receptors at those nascent contacts remain unclear. Using glutamate iontophoresis and patch-clamp recordings, we identified functional AMPA receptors (AMPARs) and NMDA receptors at postsynaptic density protein 95 clusters induced by neurexin-1β coated microspheres on primary hippocampal neurons. The recruitment of AMPARs occurred as early as 2 h after initial contact, and was not blocked by TTX/2-amino-5-phosphovaleric acid (APV) treatment. The differential recruitment of recombinant subunits GluR1 and GluR2, as well as the absence of rectification in voltage/current curves, further indicate that neurexin/neuroligin contacts primarily recruit GluR2-containing AMPARs. Finally, by using glutamate un-caging and calcium imaging, we show that AMPARs participate in calcium entry at neurexin-1β induced post-synapses, most likely through the activation of voltage-gated calcium channels. Such rapid and activity-independent accumulation of functional AMPARs at neurexin-1β-induced postsynapses points to a new role of AMPARs in synaptogenesis.
Origin of the sharp boundary that discriminates positive and negative selection of thymocytes
Authors: Prasad Ashok , Zikherman Julie , Das Jayajit , Roose Jeroen P. , Weiss Arthur , Chakraborty Arup K.
Published: December 2008

T lymphocytes play a key role in adaptive immunity and are activated by interactions of their T cell receptors (TCR) with peptides (p) derived from antigenic proteins bound to MHC gene products. The repertoire of T lymphocytes available in peripheral organs is tuned in the thymus. Immature T lymphocytes (thymocytes) interact with diverse endogenous peptides bound to MHC in the thymus. TCR expressed on thymocytes must bind weakly to endogenous pMHC (positive selection) but must not bind too strongly to them (negative selection) to emerge from the thymus. Negatively selecting pMHC ligands bind TCR with a binding affinity that exceeds a sharply defined (digital) threshold. In contrast, there is no sharp threshold separating positively selecting ligands from those that bind too weakly to elicit a response. We describe results of computer simulations and experiments, which suggest that the contrast between the characters of the positive and negative selection thresholds originates in differences in the way in which Ras proteins are activated by ligands of varying potency. The molecular mechanism suggested by our studies generates hypotheses for how genetic aberrations may dampen the digital negative selection response, with concomitant escape of autoimmune T lymphocytes from the thymus.
Stochasticity and bistability in horizontal transfer control of a genomic island in
Pseudomonas
Authors: Minoia Marco , Gaillard Muriel , Reinhard Friedrich , Stojanov Milos , Sentchilo Vladimir , van der Meer Jan Roelof
Published: December 2008

Genomic islands (GEI) comprise a recently recognized large family of potentially mobile DNA elements and play an important role in the rapid differentiation and adaptation of bacteria. Most importantly, GEIs have been implicated in the acquisition of virulence factors, antibiotic resistances or toxic compound metabolism. Despite detailed information on coding capacities of GEIs, little is known about the regulatory decisions in individual cells controlling GEI transfer. Here, we show how self-transfer of ICE
clc
, a GEI in
Pseudomonas knackmussii
B13 is controlled by a series of stochastic processes, the result of which is that only a few percent of cells in a population will excise ICE
clc
and launch transfer. Stochastic processes have been implicated before in producing bistable phenotypic transitions, such as sporulation and competence development, but never before in horizontal gene transfer (HGT). Bistability is instigated during stationary phase at the level of expression of an activator protein InrR that lays encoded on ICE
clc
, and then faithfully propagated to a bistable expression of the IntB13 integrase, the enzyme responsible for excision and integration of the ICE
clc
. Our results demonstrate how GEI of a very widespread family are likely to control their transfer rates. Furthermore, they help to explain why HGT is typically confined to few members within a population of cells. The finding that, despite apparent stochasticity, HGT rates can be modulated by external environmental conditions provides an explanation as to why selective conditions can promote DNA exchange.
Palmitoylation gates phosphorylation-dependent regulation of BK potassium channels
Authors: Tian Lijun , Jeffries Owen , McClafferty Heather , Molyvdas Adam , Rowe Iain C. M. , Saleem Fozia , Chen Lie , Greaves Jennifer , Chamberlain Luke H. , Knaus Hans-Guenther , Ruth Peter , Shipston Michael J.
Published: December 2008

Large conductance calcium- and voltage-gated potassium (BK) channels are important regulators of physiological homeostasis and their function is potently modulated by protein kinase A (PKA) phosphorylation. PKA regulates the channel through phosphorylation of residues within the intracellular C terminus of the pore-forming α-subunits. However, the molecular mechanism(s) by which phosphorylation of the α-subunit effects changes in channel activity are unknown. Inhibition of BK channels by PKA depends on phosphorylation of only a single α-subunit in the channel tetramer containing an alternatively spliced insert (STREX) suggesting that phosphorylation results in major conformational rearrangements of the C terminus. Here, we define the mechanism of PKA inhibition of BK channels and demonstrate that this regulation is conditional on the palmitoylation status of the channel. We show that the cytosolic C terminus of the STREX BK channel uniquely interacts with the plasma membrane via palmitoylation of evolutionarily conserved cysteine residues in the STREX insert. PKA phosphorylation of the serine residue immediately upstream of the conserved palmitoylated cysteine residues within STREX dissociates the C terminus from the plasma membrane, inhibiting STREX channel activity. Abolition of STREX palmitoylation by site-directed mutagenesis or pharmacological inhibition of palmitoyl transferases prevents PKA-mediated inhibition of BK channels. Thus, palmitoylation gates BK channel regulation by PKA phosphorylation. Palmitoylation and phosphorylation are both dynamically regulated; thus, cross-talk between these 2 major posttranslational signaling cascades provides a mechanism for conditional regulation of BK channels. Interplay of these distinct signaling cascades has important implications for the dynamic regulation of BK channels and physiological homeostasis.
Single-molecule DNA detection with an engineered MspA protein nanopore
Authors: Butler Tom Z. , Pavlenok Mikhail , Derrington Ian M. , Niederweis Michael , Gundlach Jens H.
Published: December 2008

Nanopores hold great promise as single-molecule analytical devices and biophysical model systems because the ionic current blockades they produce contain information about the identity, concentration, structure, and dynamics of target molecules. The porin MspA of
Mycobacterium smegmatis
has remarkable stability against environmental stresses and can be rationally modified based on its crystal structure. Further, MspA has a short and narrow channel constriction that is promising for DNA sequencing because it may enable improved characterization of short segments of a ssDNA molecule that is threaded through the pore. By eliminating the negative charge in the channel constriction, we designed and constructed an MspA mutant capable of electronically detecting and characterizing single molecules of ssDNA as they are electrophoretically driven through the pore. A second mutant with additional exchanges of negatively-charged residues for positively-charged residues in the vestibule region exhibited a factor of ≈20 higher interaction rates, required only half as much voltage to observe interaction, and allowed ssDNA to reside in the vestibule ≈100 times longer than the first mutant. Our results introduce MspA as a nanopore for nucleic acid analysis and highlight its potential as an engineerable platform for single-molecule detection and characterization applications.
Adaptive protein evolution grants organismal fitness by improving catalysis and flexibility
Authors: Tomatis Pablo E. , Fabiane Stella M. , Simona Fabio , Carloni Paolo , Sutton Brian J. , Vila Alejandro J.
Published: December 2008

Protein evolution is crucial for organismal adaptation and fitness. This process takes place by shaping a given 3-dimensional fold for its particular biochemical function within the metabolic requirements and constraints of the environment. The complex interplay between sequence, structure, functionality, and stability that gives rise to a particular phenotype has limited the identification of traits acquired through evolution. This is further complicated by the fact that mutations are pleiotropic, and interactions between mutations are not always understood. Antibiotic resistance mediated by β-lactamases represents an evolutionary paradigm in which organismal fitness depends on the catalytic efficiency of a single enzyme. Based on this, we have dissected the structural and mechanistic features acquired by an optimized metallo-β-lactamase (MβL) obtained by directed evolution. We show that antibiotic resistance mediated by this enzyme is driven by 2 mutations with sign epistasis. One mutation stabilizes a catalytically relevant intermediate by fine tuning the position of 1 metal ion; whereas the other acts by augmenting the protein flexibility. We found that enzyme evolution (and the associated antibiotic resistance) occurred at the expense of the protein stability, revealing that MβLs have not exhausted their stability threshold. Our results demonstrate that flexibility is an essential trait that can be acquired during evolution on stable protein scaffolds. Directed evolution aided by a thorough characterization of the selected proteins can be successfully used to predict future evolutionary events and design inhibitors with an evolutionary perspective.
Determination of cell fate selection during phage lambda infection
Authors: St-Pierre François , Endy Drew
Published: December 2008

Bacteriophage lambda infection of
Escherichia coli
can result in distinct cell fate outcomes. For example, some cells lyse whereas others survive as lysogens. A quantitative biophysical model of lambda infection supports the hypothesis that spontaneous differences in the timing of individual molecular events during lambda infection leads to variation in the selection of cell fates. Building from this analysis, the lambda lysis–lysogeny decision now serves as a paradigm for how intrinsic molecular noise can influence cellular behavior, drive developmental processes, and produce population heterogeneity. Here, we report experimental evidence that warrants reconsidering this framework. By using cell fractioning, plating, and single-cell fluorescent microscopy, we find that physical differences among cells present before infection bias lambda developmental outcomes. Specifically, variation in cell volume at the time of infection can be used to help predict cell fate: a ≈2-fold increase in cell volume results in a 4- to 5-fold decrease in the probability of lysogeny. Other cell fate decisions now thought to be stochastic might also be determined by pre-existing variation.
Functional comparison of RGS9 splice isoforms in a living cell
Authors: Martemyanov Kirill A. , Krispel Claudia M. , Lishko Polina V. , Burns Marie E. , Arshavsky Vadim Y.
Published: December 2008

Two isoforms of the GTPase-activating protein, regulator of G protein signaling 9 (RGS9), control such fundamental functions as vision and behavior. RGS9–1 regulates phototransduction in rods and cones, and RGS9–2 regulates dopamine and opioid signaling in the basal ganglia. To determine their functional differences in the same intact cell, we replaced RGS9–1 with RGS9–2 in mouse rods. Surprisingly, RGS9–2 not only supported normal photoresponse recovery under moderate light conditions but also outperformed RGS9–1 in bright light. This versatility of RGS9–2 results from its ability to inactivate the G protein, transducin, regardless of its effector interactions, whereas RGS9–1 prefers the G protein-effector complex. Such versatility makes RGS9–2 an isoform advantageous for timely signal inactivation across a wide range of stimulus strengths and may explain its predominant representation throughout the nervous system.
Bidirectional Ca
2+
-dependent control of mitochondrial dynamics by the Miro GTPase
Authors: Saotome Masao , Safiulina Dzhamilja , Szabadkai György , Das Sudipto , Fransson Åsa , Aspenstrom Pontus , Rizzuto Rosario , Hajnóczky György
Published: December 2008

Calcium oscillations suppress mitochondrial movements along the microtubules to support on-demand distribution of mitochondria. To activate this mechanism, Ca
2+
targets a yet unidentified cytoplasmic factor that does not seem to be a microtubular motor or a kinase/phosphatase. Here, we have studied the dependence of mitochondrial dynamics on the Miro GTPases that reside in the mitochondria and contain two EF-hand Ca
2+
-binding domains, in H9c2 cells and primary neurons. At resting cytoplasmic [Ca
2+
] ([Ca
2+
]
c
), movements of the mitochondria were enhanced by Miro overexpression irrespective of the presence of the EF-hands. The Ca
2+
-induced arrest of mitochondrial motility was also promoted by Miro overexpression and was suppressed when either the Miro were depleted or their EF-hand was mutated. Miro also enhanced the fusion state of the mitochondria at resting [Ca
2+
]
c
but promoted mitochondrial fragmentation at high [Ca
2+
]
c
. These effects of Miro on mitochondrial morphology seem to involve Drp1 suppression and activation, respectively. In primary neurons, Miro also caused an increase in dendritic mitochondrial mass and enhanced mitochondrial calcium signaling. Thus, Miro proteins serve as a [Ca
2+
]
c
-sensitive switch and bifunctional regulator for both the motility and fusion-fission dynamics of the mitochondria.
Two-step oligoclonal development of male germ cells
Authors: Ueno Hiroo , Turnbull Brit B. , Weissman Irving L.
Published: December 2008

During mouse development, primordial germ cells (PGCs) that give rise to the entire germ line are first identified within the proximal epiblast. However, long-term tracing of the fate of the cells has not been done wherein all cells in and around the germ-cell lineage are identified. Also, quantitative estimates of the number of founder PGCs using different models have come up with various numbers. Here, we use tetrachimeric mice to show that the progenitor numbers for the entire germ line in adult testis, and for the initiating embryonic PGCs, are both 4 cells. Although they proliferate to form polyclonal germ-cell populations in fetal and neonatal testes, germ cells that actually contribute to adult spermatogenesis originate from a small number of secondary founder cells that originate in the fetal period. The rest of the “deciduous” germ cells are lost, most likely by apoptosis, before the reproductive period. The second “actual” founder germ cells generally form small numbers of large monoclonal areas in testes by the reproductive period. Our results also demonstrate that there is no contribution of somatic cells to the male germ cell pool during development or in adulthood. These results suggest a model of 2-step oligoclonal development of male germ cells in mice, the second step distinguishing the heritable germ line from cells selected not to participate in forming the next generation.
Structural basis for cross-resistance to ribosomal PTC antibiotics
Authors: Davidovich Chen , Bashan Anat , Yonath Ada
Published: December 2008

Clinically relevant antibiotics that target the ribosomal peptidyl transferase center (PTC), a highly conserved ribosomal region, exert their inhibitory action by exploiting the flexibility of PTC nucleotides, which trigger modulations of the shape of the antibiotic binding pocket. Resistance to these antibiotics was observed clinically and in vitro. Based on the crystal structures of the large ribosomal subunit from eubacterium suitable to represent pathogens in complex with these antibiotics, it was found that all nucleotides mediating resistance to PTC antibiotics cluster on one side of the PTC. Over half of the nucleotides affecting resistance reside in regions of lower sequence conservation, and are too distal to make Van der Waals interactions with the bound drugs. Alterations of the identity of these nucleotides may not lethally affect ribosome function, but can hamper antibiotic binding through changes in the conformation and flexibility of specific PTC nucleotides. Comparative analysis revealed properties likely to lead to cross-resistance and enabled their parameterization. As the same nucleotides are frequently involved in resistance to more than a single family of antibiotics, the common pattern explains medically observed cross-resistance to PTC antibiotics and suggests the potential for a wider clinical threat.
Discovery and revision of
Arabidopsis
genes by proteogenomics
Authors: Castellana Natalie E. , Payne Samuel H. , Shen Zhouxin , Stanke Mario , Bafna Vineet , Briggs Steven P.
Published: December 2008

Gene annotation underpins genome science. Most often protein coding sequence is inferred from the genome based on transcript evidence and computational predictions. While generally correct, gene models suffer from errors in reading frame, exon border definition, and exon identification. To ascertain the error rate of
Arabidopsis thaliana
gene models, we isolated proteins from a sample of
Arabidopsis
tissues and determined the amino acid sequences of 144,079 distinct peptides by tandem mass spectrometry. The peptides corresponded to 1 or more of 3 different translations of the genome: a 6-frame translation, an exon splice-graph, and the currently annotated proteome. The majority of the peptides (126,055) resided in existing gene models (12,769 confirmed proteins), comprising 40% of annotated genes. Surprisingly, 18,024 novel peptides were found that do not correspond to annotated genes. Using the gene finding program AUGUSTUS and 5,426 novel peptides that occurred in clusters, we discovered 778 new protein-coding genes and refined the annotation of an additional 695 gene models. The remaining 13,449 novel peptides provide high quality annotation (>99% correct) for thousands of additional genes. Our observation that 18,024 of 144,079 peptides did not match current gene models suggests that 13% of the
Arabidopsis
proteome was incomplete due to approximately equal numbers of missing and incorrect gene models.
The interpersonal function of clefts in English and Swedish
Authors: Herriman Jennifer
Published: December 2008

Seen from an interpersonal perspective, within the framework of Appraisal (Martin and White 2005), cleft constructions in English and Swedish function in the system of Engagement as a heteroglossic rhetorical device by which speakers and writers negotiate an authorial position for themselves while implicitly acknowledging the existence of alternative positions. The cleft clause opens up the utterance to heteroglossic negotiation by representing one of its clause elements as a semantic gap. The identity of the semantic gap is then identified by the clefted constituent in the superordinate clause. It-clefts and reversed wh-clefts have different clefting possibilities in English and Swedish, which means that it-clefts and reversed wh-clefts are used to negotiate different types of authorial positions.
Hybrid verbs in Yorùbá-English code-mixing
Authors: Lamidi MufutauTemitayo
Published: December 2008

This paper studies the verbs that result from contact between English and Yorùbá languages. Using data generated from informal discussions, it discusses two of the categories of lexical verbs in use in Yorùbá-English code-mixing. The first type, clean verbs, originate from each of the languages in contact and are interchangeable; the second type, hybrid verbs, is a creation that results from language contact. The study concludes that these features of the verb are part of the grammatical basis of the Yorùbá-English code-mixing.
Communication verbs in Chinese and English
Authors: Shi Dongqin
Published: December 2008

This paper, using translation materials as data for analysis and based on Fillmore’s (1982) Frame Semantics Theory, presents a contrastive study of communication verbs in Chinese and English with respect to their representation of semantic components related to a communication event. In Talmy’s (1991) classification, Chinese and English fall into the same typological category as satellite-framed languages, where large numbers of verbs characteristically incorporate Manner with Motion, and the Path of motion is typically mapped onto a post-verb satellite. Previous contrastive studies of Chinese and English, however, have concluded that Chinese deviates from a typical satellite-framed language as represented by English with respect to both the conflation of Manner with Motion and the representation of the Path of motion. The present study, which examines, specifically, how communication verbs express speaking events in written narrative in Chinese and English, has found more intra-typological differences between the two languages in their representation of meanings in surface structures as well as in the narrative style in which words of a particular category are chosen for representing events. The major original findings from this study are that Chinese is by far more constrained than English in its encoding of semantic components in communication verbs, and that a translator may face a great challenge when doing Chinese-to-English translation with respect to the choice of appropriate communication verbs.
Alienation techniques in screen translation
Authors: Valdeón Roberto A.
Published: December 2008

This paper presents a critical approach to the translation of cultural items in the Spanish dubbed version of the American sitcom Will & Grace. The paper starts with a presentation of domestication and foreignization (Venuti 1995). The former is discussed in connection with the choices made in the target texts. I, then, introduce the term “alienation” as another strategy used to render culture specificities. In the second section I examine the key comical elements present in the scripts, in which cultural allusions also play a significant role. Section three explores how these culturally anchored lexical items are rendered in the Spanish version, establishing a taxonomy that includes preservation of international items, preservation of culture-specific items, substitution with a different source-culture item, substitution with an international item, substitution with a target-culture item, substitution with corrupted forms of target-culture items and substitution with a superordinate. The use and translation of expletives as elements unique to a language and culture are also covered. The final section discusses the transition from domestication to alienation.