bluuebunny/crossref_metadata_2025 huggingface dataset:
Extracellular Protease, Extracellular Haemolysin, and Virulence in Aeromonas salmonicida
Authors: Hackett Jeremy L. , Lynch William H. , Paterson William D. , Coombs David H.
Published: November 2009

We have examined the possibile relationships between extracellular protease and haemolysin and virulence in Aeromonas salmonicida, and the possible plasmid-encoded origin of these extracellular enzyme activities. Variants, isolated from different strains, showed simultaneous loss of both protease and haemolysin. The frequency of spontaneous loss from one strain (0.1–0.4%) as well as the frequency of induced loss from four strains (0.3–18%) treated with ethidium bromide suggested a plasmid-encoded origin for these enzymes. However, plasmid analyses showed no detectable loss of plasmids correlated with the loss of the extracellular activities. There was no change in the LD100 when fish were exposed to one virulent strain or its protease, haemolysin-negative variants indicating that these extracellular activities are not necessary for virulence or pathogenicity in the acute form of furunculosis. Furthermore, both protease, haemolysin-negative and protease, haemolysin-positive clones isolated from a second virulent strain treated with ethidium bromide were avirulent (LD50 increased >4 logs). Thus, attenuation of A. salmonicida can occur without detected loss of the extracellular enzymes, plasmids, or the A-layer.
Evaluation of Acid-Insoluble Ash as an Indicator of Feed Digestibility in Rainbow Trout (Salmo gairdneri)
Authors: Atkinson J. L. , Hilton J. W. , Slinger S. J.
Published: November 2009

Relative performances of dietary acid-insoluble ash, celite (a source of acid-insoluble ash), and chromic oxide as digestibility references were compared. Apparent digestibilities of dry matter, crude protein, and gross energy in a practical diet fed to rainbow trout (Salmo gairdneri) were similar regardless of indicator used. Acid-insoluble ash can bean effective indicator for digestibility trials with fish. Its natural occurrence in fish foods and feedstuffs and ease of analysis make it preferable to added indicators, such as chromic oxide, in many circumstances. When the acid-insoluble ash content of a diet is low, the addition of celite can improve the precision of the analysis without affecting absolute values of digestibility coefficients.
Early weaning stress impairs development of mucosal barrier function in the porcine intestine
Authors: Smith Feli , Clark Jessica E. , Overman Beth L. , Tozel Christena C. , Huang Jennifer H. , Rivier Jean E. F. , Blisklager Anthony T. , Moeser Adam J.
Published: November 2009

Early life stress is a predisposing factor for the development of chronic intestinal disorders in adult life. Here, we show that stress associated with early weaning in pigs leads to impaired mucosal barrier function. Early weaning (15- to 21-day weaning age) resulted in sustained impairment in intestinal barrier function, as indicated by reductions in jejunal transepithelial electrical resistance and elevations in mucosal-to-serosal flux of paracellular probes [3H]mannitol and [14C]inulin measured at 5 and 9 wk of age, compared with that shown in late-weaned pigs (23- to 28-day weaning age). Elevated baseline short-circuit current was observed in jejunum from early-weaned pigs and was shown to be mediated via enhanced Cl−secretion. Jejunal barrier dysfunction in early-weaned pigs coincided with increased lamina propria immune cell density particularly mucosal mast cells. The mast cell stabilizer drug sodium cromoglycolate ameliorated barrier dysfunction and hypersecretion in early-weaned pigs, demonstrating an important role of mast cells. Furthermore, activation of mast cells ex vivo with c48/80 and corticotrophin-releasing factor (CRF) in pig jejunum mounted in Ussing chambers induced barrier dysfunction and elevations in short-circuit current that were inhibited with mast cell protease inhibitors. Experiments in which selective CRF receptor antagonists were administered to early-weaned pigs revealed that CRF receptor 1 (CRFr1) activation mediates barrier dysfunction and hypersecretion, whereas CRFr2 activation may be responsible for novel protective properties in the porcine intestine in response to early life stress.
Modulation of urea transport across sheep rumen epithelium in vitro by SCFA and CO2
Authors: Abdoun Khalid , Stumpff Friederike , Rabbani Imtiaz , Martens Holger
Published: November 2009

Urea transport across the gastrointestinal tract involves transporters of the urea transporter-B group, the regulation of which is poorly understood. The classical stimulatory effect of CO2and the effect of short-chain fatty acids (SCFA) on the ruminal recycling of urea were investigated by using Ussing chamber and microelectrode techniques with isolated ruminal epithelium of sheep. The flux of urea was found to be phloretin sensitive and passive. At a luminal pH of 6.4, but not at 7.4, the addition of SCFA (40 mmol/l) or CO2/HCO3− (10% and 25 mmol/l) led to a fourfold increase in urea flux. The stepwise reduction of luminal pH in the presence of SCFA from 7.4 to 5.4 led to a bell-shaped modification of urea transport, with a maximum at pH 6.2. Lowering the pH in the absence of SCFA or CO2had no effect. Inhibition of Na+/H+exchange increased urea flux at pH 7.4, with a decrease being seen at pH 6.4. In experiments with double-barreled, pH-sensitive microelectrodes, we confirmed the presence of an apical pH microclimate and demonstrated the acidifying effects of SCFA on the underlying epithelium. We confirm that the permeability of the ruminal epithelium to urea involves a phloretin-sensitive pathway. We present clear evidence for the regulation of urea transport by strategies that alter intracellular pH, with permeability being highest after a moderate decrease. The well-known postprandial stimulation of urea transport to the rumen in vivo may involve acute pH-dependent effects of intraruminal SCFA and CO2on the function of existing urea transporters.
Liver apoptosis is age dependent and is reduced by activation of peroxisome proliferator-activated receptor-γ in hemorrhagic shock
Authors: Zingarelli Basilia , Chima Ranjit , O'Connor Michael , Piraino Giovanna , Denenberg Alvin , Hake Paul W.
Published: November 2009

A clinical observation in pediatric and adult intensive care units is that the incidence of multiple organ failure in pediatric trauma victims is lower than in adult patients. However, the molecular mechanisms are not yet defined. Recent experimental studies have shown that the nuclear peroxisome proliferator-activated receptor-γ (PPARγ) modulates the inflammatory process. In this study, we hypothesized that severity of liver injury may be age dependent and PPARγ activation may provide beneficial effects. Hemorrhagic shock was induced in anesthetized young (3–5 mo old) and mature male Wistar rats (11–13 mo old) by withdrawing blood to a mean arterial blood pressure of 50 mmHg. After 3 h, rats were rapidly resuscitated with shed blood. Animals were euthanized 3 h after resuscitation. In mature rats, liver injury appeared more pronounced compared with young rats and was characterized by marked hepatocyte apoptosis, extravasation of erythrocytes, and accumulation of neutrophils. The ratio between the antiapoptotic protein Bcl-2 and the proapoptotic protein BAX was lower, whereas activity of caspase-3, the executioner of apoptosis, was higher in liver of mature rats compared with young rats. Plasma alanine aminotransferase levels were not different between the two age groups. This heightened liver apoptosis was associated with a significant downregulation of PPARγ DNA binding in mature rats compared with young rats. Treatment with the PPARγ ligand ciglitazone significantly reduced liver apoptosis in mature rats. Our data suggest that liver injury after severe hemorrhage is age dependent and PPARγ activation is a novel hepatoprotective mechanism.
A microfluidic wound-healing assay for quantifying endothelial cell migration
Authors: van der Meer Andries D. , Vermeul Kim , Poot André A. , Feijen Jan , Vermes István
Published: November 2009

Endothelial migration is an important process in the formation of blood vessels and the repair of damaged tissue. To study this process in the laboratory, versatile and reliable migration assays are essential. The purpose of this study was to investigate whether the microfluidic version of the conventional wound-healing assay is a useful research tool for vascular science. Endothelial cells were seeded in a 500-μm-wide microfluidic channel. After overnight incubation, cells had formed a viable and confluent monolayer. Then, a wound was generated in this monolayer by flushing the channel with three parallel fluid streams, of which the middle one contained the protease trypsin. By analyzing the closing of the wound over time, endothelial cell migration could be measured. Although the migration rate was two times lower in the microfluidic assay than in the conventional assay, an identical 1.5-times increase in migration rate was found in both assays when vascular endothelial growth factor (VEGF165) was added. In the microfluidic wound-healing assay, a stable gradient of VEGF165 could be generated at the wound edge. This led to a two-times increase in migration rate compared with the untreated control. Finally, when a shear stress of 1.3 Pa was applied to the wound, the migration rate increased 1.8 times. In conclusion, the microfluidic assay is a solid alternative for the conventional wound-healing assay when endothelial cell migration is measured. Moreover, it offers unique advantages, such as gradient generation and application of shear stress.
GPS/Galileo Multipath Detection and Mitigation Using Closed‐Form Solutions
Authors: Rouabah Khaled , Chikouche Djamel
Published: November 2009

We propose an efficient method for the detection of Line of Sight (LOS) and Multipath (MP) signals in global navigation satellite systems (GNSSs) which is based on the use of virtual MP mitigation (VMM) technique. By using the proposed method, the MP signals′ delay and coefficient amplitudes can be efficiently estimated. According to the computer simulation results, it is obvious that our proposed method is a solution for obtaining high performance in the estimation and mitigation of MP signals and thus it results in a high accuracy in GNSS positioning.
Bifurcation Analysis of a Van der Pol‐Duffing Circuit with Parallel Resistor
Authors: Braga Denis de Carvalho , Mello Luis Fernando , Messias Marcelo
Published: November 2009

We study the local codimension one, two, and three bifurcations which
occur in a recently proposed Van der Pol‐Duffing circuit (ADVP) with parallel
resistor, which is an extension of the classical Chua′s circuit with cubic nonlinearity.
The ADVP system presents a very rich dynamical behavior, ranging from
stable equilibrium points to periodic and even chaotic oscillations. Aiming to contribute
to the understand of the complex dynamics of this new system we present
an analytical study of its local bifurcations and give the corresponding bifurcation
diagrams. A complete description of the regions in the parameter space for
which multiple small periodic solutions arise through the Hopf bifurcations at the
equilibria is given. Then, by studying the continuation of such periodic orbits,
we numerically find a sequence of period doubling and symmetric homoclinic bifurcations
which leads to the creation of strange attractors, for a given set of the
parameter values.
Automatic Clustering of Flow Cytometry Data with Density-Based Merging
Authors: Walther Guenther , Zimmerman Noah , Moore Wayne , Parks David , Meehan Stephen , Belitskaya Ilana , Pan Jinhui , Herzenberg Leonore
Published: November 2009

The ability of flow cytometry to allow fast single cell interrogation of a large number of cells has made this technology ubiquitous and indispensable in the clinical and laboratory setting. A current limit to the potential of this technology is the lack of automated tools for analyzing the resulting data. We describe methodology and software to automatically identify cell populations in flow cytometry data. Our approach advances the paradigm of manually gating sequential two-dimensional projections of the data to a procedure that automatically produces gates based on statistical theory. Our approach is nonparametric and can reproduce nonconvex subpopulations that are known to occur in flow cytometry samples, but which cannot be produced with current parametric model-based approaches. We illustrate the methodology with a sample of mouse spleen and peritoneal cavity cells.
A Fixed Point Approach to the Fuzzy Stability of an Additive-Quadratic-Cubic Functional Equation
Authors: Park Choonkil
Published: November 2009

Using the fixed point method, we prove the generalized Hyers-Ulam stability of the following additive-quadratic-cubic functional equation "Equation missing" = "Equation missing" in fuzzy Banach spaces.
A New Tool for Automatic Assessment of Segmental Wall Motion Based on Longitudinal 2D Strain
Authors: Liel-Cohen Noah , Tsadok Yossi , Beeri Ronen , Lysyansky Peter , Agmon Yoram , Feinberg Micha S. , Fehske Wolfgang , Gilon Dan , Hay Ilan , Kuperstein Rafael , Leitman Marina , Deutsch Lisa , Rosenmann David , Sagie Alik , Shimoni Sarah , Vaturi Mordehay , Friedman Zvi , Blondheim David S.
Published: November 2009

Background—

Identification and quantification of segmental left ventricular wall motion abnormalities on echocardiograms is of paramount clinical importance but is still performed by a subjective visual method. We constructed an automatic tool for assessment of wall motion based on longitudinal strain.

Methods and Results—

Echocardiograms of 105 patients (3 apical views) were blindly analyzed by 12 experienced readers. Visual segmental scores (VSS) and peak systolic longitudinal strain were assigned to each of 18 segments per patient. Ranges of peak systolic longitudinal strain that best fit VSS (by receiver operating characteristic analysis) were used to generate automatic segmental scores (ASS). Comparisons of ASS and VSS were performed on 1952 analyzable segments. There was agreement of wall motion scores between both methods in 89.6% of normal, 39.5% of hypokinetic, and 69.4% of akinetic segments. Correlation between methods was
r
=0.63 (
P
<0.0001). Interobserver and intraobserver reliability using interclass correlation for scoring segmental wall motion into 3 scores by ASS was 0.82 and 0.83 and by VSS 0.70 and 0.69, respectively. Compared with VSS (majority rule), ASS had a sensitivity, specificity, and accuracy of 87%, 85%, and 86%, respectively. ASS and VSS had similar success rates for correct identification of wall motion abnormalities in territories supplied by culprit arteries. VSS had greater specificity and positive predictive values, whereas ASS had higher sensitivity and negative predictive values for identifying the culprit artery.

Conclusions—

Automatic quantification of wall motion on echocardiograms by this tool performs as well as visual analysis by experienced echocardiographers, with a greater reliability and similar agreement to angiographic findings.
Short Communication: The Neuropeptide Substance P Mediates Adventitial Mast Cell Activation and Induces Intraplaque Hemorrhage in Advanced Atherosclerosis
Authors: Bot Ilze , de Jager Saskia C.A. , Bot Martine , van Heiningen Sandra H. , de Groot Paul , Veldhuizen Roel W. , van Berkel Theo J.C. , von der Thüsen Jan H. , Biessen Erik A.L.
Published: November 2009

Rationale
:

Although we and others have recently shown that mast cells play an important role in plaque progression and destabilization, the nature of the actual trigger for (peri)vascular mast cell activation during atherosclerosis is still unresolved.

Objective
:

In this study, we confirm that perivascular mast cell content correlates with the number of nerve fibers in the adventitia of human coronary atherosclerotic plaque specimen. Because peripheral C-type nerve fibers secrete, among others, substance P, a potent mast cell activator, we set out to study effects of adventitial administration of this neuropeptide on mast cell dependent destabilization of carotid artery plaques in apolipoprotein E–deficient (apoE
−/−
) mice.

Methods and Results
:

Substance P treatment significantly enhanced the number and activation status of adventitial mast cells compared to controls and promoted intraplaque hemorrhages. These phenomena could be prevented by coadministration of the neurokinin-1 receptor antagonist spantide I and did not occur in mast cell deficient apoE
−/−
mice, establishing the critical involvement of mast cells in substance P–elicited plaque destabilization.

Conclusions
:

Our data suggest that neurotransmitters such as substance P are capable of promoting mast cell dependent plaque destabilization and provide a new, direct link between neural factors and vascular inflammation.
GTP Cyclohydrolase I Phosphorylation and Interaction With GTP Cyclohydrolase Feedback Regulatory Protein Provide Novel Regulation of Endothelial Tetrahydrobiopterin and Nitric Oxide
Authors: Li Li , Rezvan Amir , Salerno John C. , Husain Ahsan , Kwon Kihwan , Jo Hanjoong , Harrison David G. , Chen Wei
Published: November 2009

Rationale
:

GTP cyclohydrolase I (GTPCH-1) is the rate-limiting enzyme involved in de novo biosynthesis of tetrahydrobiopterin (BH
4
), an essential cofactor for NO synthases and aromatic amino acid hydroxylases. GTPCH-1 undergoes negative feedback regulation by its end-product BH
4
via interaction with the GTP cyclohydrolase feedback regulatory protein (GFRP). Such a negative feedback mechanism should maintain cellular BH
4
levels within a very narrow range; however, we recently identified a phosphorylation site (S81) on human GTPCH-1 that markedly increases BH
4
production in response to laminar shear.

Objective
:

We sought to define how S81 phosphorylation alters GTPCH-1 enzyme activity and how this is modulated by GFRP.

Methods and Results
:

Using prokaryotically expressed proteins, we found that the GTPCH-1 phospho-mimetic mutant (S81D) has increased enzyme activity, reduced binding to GFRP and resistance to inhibition by GFRP compared to wild-type GTPCH-1. Using small interfering RNA or overexpressing plasmids, GFRP was shown to modulate phosphorylation of GTPCH-1, BH
4
levels, and NO production in human endothelial cells. Laminar, but not oscillatory shear stress, caused dissociation of GTPCH-1 and GFRP, promoting GTPCH-1 phosphorylation. We also found that both GTPCH-1 phosphorylation and GFRP downregulation prevents endothelial NO synthase uncoupling in response to oscillatory shear. Finally oscillatory shear was associated with impaired GTPCH-1 phosphorylation and reduced BH
4
levels in vivo.

Conclusions
:

These studies provide a new mechanism for regulation of endothelial GTPCH-1 by its phosphorylation and interplay with GFRP. This mechanism allows for escape from GFRP negative feedback and permits large amounts of BH
4
to be produced in response to laminar shear stress.
Excessive Incidence of Stroke in Iran
Authors: Azarpazhooh Mahmoud Reza , Etemadi Mohammad Mehdi , Donnan Geoffrey A. , Mokhber Naghmeh , Majdi Mohammad Reza , Ghayour-Mobarhan Majid , Ghandehary Kavian , Farzadfard Mohammad Taghi , Kiani Reza , Panahandeh Majid , Thrift Amanda G.
Published: November 2009

Background and Purpose—

The epidemiology of stroke and its subtypes in the Middle East is unclear. Most previous studies have been performed in Western countries, and incidence rates are unlikely to apply in the Middle East. We aimed to determine the incidence of stroke in Mashhad, northeastern Iran.

Methods—

During a 12-month period (2006–2007), we prospectively ascertained all strokes occurring in a population of 450 229. Multiple overlapping sources were used to identify people with stroke. A large number of volunteers assisted in finding stroke patients not admitted to hospital. Potential cases were reviewed by a group of stroke experts before inclusion.

Results—

A total of 624 first-ever strokes occurred during the study period, 98.4% undergoing imaging. Despite a relatively low crude annual incidence rate of first-ever stroke FES (139; 95% CI, 128 to 149) per 100 000 residents, rates adjusted to the European population aged 45 to 84 years were higher than in most other countries: 616 (95% CI, 567 to 664) for ischemic stroke, 94 (95% CI, 75 to 113) for intracerebral hemorrhage, and 12 (95% CI, 5 to 19) for subarachnoid hemorrhage. Age-specific stroke incidence was higher in younger patients than is typically seen in Western countries. Comparison of age-specific incidence rates between regions revealed that stroke in Mashhad occurs approximately 1 decade earlier than in Western countries.

Conclusions—

The results of this study provide evidence that the incidence of stroke in Iran is considerably greater than in most Western countries, with stroke occurring at younger ages. Ischemic stroke incidence was also considerably greater than reported in other regions.
Association of Thyroid Autoantibodies With Moyamoya-Type Cerebrovascular Disease
Authors: Kim Suk Jae , Heo Kwang Gi , Shin Hee Young , Bang Oh Young , Kim Gyeong-Moon , Chung Chin-Sang , Kim Keon Ha , Jeon Pyoung , Kim Jong Soo , Hong Seung-Chyul , Lee Kwang Ho
Published: November 2009

Background and Purpose—

To investigate the association between thyroid autoantibodies and moyamoya disease (MMD) in patients with an apparent euthyroid state.

Methods—

We prospectively studied angiographically diagnosed patients with MMD. We compared demographic profiles, thyroid function test, and thyroid autoantibody status between MMD and control groups.

Results—

A total of 63 patients with MMD, 71 patients with non-MMD stroke, and 200 healthy control subjects were included. The prevalence of elevated thyroid autoantibodies was higher in the MMD group than in other groups (
P
<0.01 for MMD versus non-MMD;
P
<0.001 for MMD versus control subjects). After adjusting for covariates, the elevated thyroid autoantibodies (OR, 4.871; 95% CI, 1.588 to 15.277) and smoking habits (OR, 0.206 for current smoker; 95% CI, 0.054 to 0.786) were independently associated with MMD versus non-MMD stroke.

Conclusions—

Elevated thyroid autoantibodies were frequently observed in patients with MMD. The results of the present study suggest that immune aberrancies associated with or underlying thyroid autoimmunity are also playing a role in developing MMD.
Ten-Year Detection Rate of Brain Arteriovenous Malformations in a Large, Multiethnic, Defined Population
Authors: Gabriel Rodney A. , Kim Helen , Sidney Stephen , McCulloch Charles E. , Singh Vineeta , Johnston S. Claiborne , Ko Nerissa U. , Achrol Achal S. , Zaroff Jonathan G. , Young William L.
Published: November 2009

Background and Purpose—

To evaluate whether increased neuroimaging use is associated with increased brain arteriovenous malformation (BAVM) detection, we examined detection rates in the Kaiser Permanente Medical Care Program of northern California between 1995 and 2004.

Methods—

We reviewed medical records, radiology reports, and administrative databases to identify BAVMs, intracranial aneurysms (IAs: subarachnoid hemorrhage [SAH] and unruptured aneurysms), and other vascular malformations (OVMs: dural fistulas, cavernous malformations, Vein of Galen malformations, and venous malformations). Poisson regression (with robust standard errors) was used to test for trend. Random-effects meta-analysis generated a pooled measure of BAVM detection rate from 6 studies.

Results—

We identified 401 BAVMs (197 ruptured, 204 unruptured), 570 OVMs, and 2892 IAs (2079 SAHs and 813 unruptured IAs). Detection rates per 100 000 person-years were 1.4 (95% CI, 1.3 to 1.6) for BAVMs, 2.0 (95% CI, 1.8 to 2.3) for OVMs, and 10.3 (95% CI, 9.9 to 10.7) for IAs. Neuroimaging utilization increased 12% per year during the time period (
P
<0.001). Overall, rates increased for IAs (
P
<0.001), remained stable for OVMs (
P
=0.858), and decreased for BAVMs (
P
=0.001). Detection rates increased 15% per year for unruptured IAs (
P
<0.001), with no change in SAHs (
P
=0.903). However, rates decreased 7% per year for unruptured BAVMs (
P
=0.016) and 3% per year for ruptured BAVMs (
P
=0.005). Meta-analysis yielded a pooled BAVM detection rate of 1.3 (95% CI, 1.2 to 1.4) per 100 000 person-years, without heterogeneity between studies (
P
=0.25).

Conclusions—

Rates for BAVMs, OVMs, and IAs in this large, multiethnic population were similar to those in other series. During 1995 to 2004, a period of increasing neuroimaging utilization, we did not observe an increased rate of detection of unruptured BAVMs, despite increased detection of unruptured IAs.
Endovascular Treatment of Very Small (3 mm or Smaller) Intracranial Aneurysms
Authors: Brinjikji Waleed , Lanzino Giuseppe , Cloft Harry J. , Rabinstein Alejandro , Kallmes David F.
Published: November 2009

Background and Purpose—

We performed a meta-analysis of published studies on the endovascular treatment of very small intracranial aneurysms, including 71 patients treated at our institution.

Methods—

We conducted a computerized MEDLINE search of the literature for reports on the treatment of intracranial aneurysms with a maximum dimension of ≤3 mm by using the search terms “small,” “tiny,” “intracranial aneurysm,” “endovascular,” and “coil.” A total of 7 studies, including our institution’s consecutive case series of 71 intracranial aneurysms, were included in this study. We extracted information regarding intraoperative complications, procedural mortality and morbidity, immediate- and long-term angiographic outcomes, and retreatment rate. The meta-analysis was performed with the statistical package Comprehensive Meta-Analysis.

Results—

Approximately 61% of the aneurysms in this meta-analysis presented as ruptured, whereas 39% of the aneurysms were unruptured. Procedural rupture rates for very small aneurysms was 8.3% (95% CI, 6.0% to 11.4%). The mortality rate due to procedural rupture was 2.4% (95% CI, 1.2% to 4.7%). The morbidity rate due to thromboembolic complications was 1.9% (95% CI, 0.9% to 3.9%). Subarachnoid hemorrhage within 1 month of treatment occurred in 1.6% (95% CI, 0.6% to 3.7%) of cases. There was no statistically significant difference between unruptured and ruptured aneurysms for any of these outcomes.

Conclusion—

Our meta-analysis suggests that treatment of very small aneurysms is feasible and effective in >90% of treated aneurysms. However, the risk of periprocedural rupture is higher than that reported for larger aneurysms. Similarly, the combined rate of periprocedural mortality and morbidity is not negligible (7.3%) and should be considered when considering the best therapeutic option for these aneurysms.
Roles of Medial Prefrontal Cortex and Orbitofrontal Cortex in Self-evaluation
Authors: Beer Jennifer S. , Lombardo Michael V. , Bhanji Jamil Palacios
Published: November 2009

Empirical investigations of the relation of frontal lobe function to self-evaluation have mostly examined the evaluation of abstract qualities in relation to self versus other people. The present research furthers our understanding of frontal lobe involvement in self-evaluation by examining two processes that have not been widely studied by neuroscientists: on-line self-evaluations and correction of systematic judgment errors that influence self-evaluation. Although people evaluate their abstract qualities, it is equally important that perform on-line evaluations to assess the success of their behavior in a particular situation. In addition, self-evaluations of task performance are sometimes overconfident because of systematic judgment errors. What role do the neural regions associated with abstract self-evaluations and decision bias play in on-line evaluation and self-evaluation bias? In this fMRI study, self-evaluation in two reasoning tasks was examined; one elicited overconfident self-evaluations of performance because of salient but misleading aspects of the task and the other was free from misleading aspects. Medial PFC (mPFC), a region associated with self-referential processing, was generally involved in on-line self-evaluations but not specific to accurate or overconfident evaluation. Orbitofrontal cortex (OFC) activity, a region associated with accurate nonsocial judgment, negatively predicted individual differences in overconfidence and was negatively associated with confidence level for incorrect trials.
Reasoning with Exceptions: An Event-related Brain Potentials Study
Authors: Pijnacker Judith , Geurts Bart , van Lambalgen Michiel , Buitelaar Jan , Hagoort Peter
Published: November 2009

Defeasible inferences are inferences that can be revised in the light of new information. Although defeasible inferences are pervasive in everyday communication, little is known about how and when they are processed by the brain. This study examined the electrophysiological signature of defeasible reasoning using a modified version of the suppression task. Participants were presented with conditional inferences (of the type “if p, then q; p, therefore q”) that were preceded by a congruent or a disabling context. The disabling context contained a possible exception or precondition that prevented people from drawing the conclusion. Acceptability of the conclusion was indeed lower in the disabling condition compared to the congruent condition. Further, we found a large sustained negativity at the conclusion of the disabling condition relative to the congruent condition, which started around 250 msec and was persistent throughout the entire epoch. Possible accounts for the observed effect are discussed.
Cross-domain Effects of Music and Language Experience on the Representation of Pitch in the Human Auditory Brainstem
Authors: Bidelman Gavin M. , Gandour Jackson T. , Krishnan Ananthanarayan
Published: November 2009

Neural encoding of pitch in the auditory brainstem is known to be shaped by long-term experience with language or music, implying that early sensory processing is subject to experience-dependent neural plasticity. In language, pitch patterns consist of sequences of continuous, curvilinear contours; in music, pitch patterns consist of relatively discrete, stair-stepped sequences of notes. The primary aim was to determine the influence of domain-specific experience (language vs. music) on the encoding of pitch in the brainstem. Frequency-following responses were recorded from the brainstem in native Chinese, English amateur musicians, and English nonmusicians in response to iterated rippled noise homologues of a musical pitch interval (major third; M3) and a lexical tone (Mandarin tone 2; T2) from the music and language domains, respectively. Pitch-tracking accuracy (whole contour) and pitch strength (50 msec sections) were computed from the brainstem responses using autocorrelation algorithms. Pitch-tracking accuracy was higher in the Chinese and musicians than in the nonmusicians across domains. Pitch strength was more robust across sections in musicians than in nonmusicians regardless of domain. In contrast, the Chinese showed larger pitch strength, relative to nonmusicians, only in those sections of T2 with rapid changes in pitch. Interestingly, musicians exhibited greater pitch strength than the Chinese in one section of M3, corresponding to the onset of the second musical note, and two sections within T2, corresponding to a note along the diatonic musical scale. We infer that experience-dependent plasticity of brainstem responses is shaped by the relative saliency of acoustic dimensions underlying the pitch patterns associated with a particular domain.
The Neural Correlates of Persuasion: A Common Network across Cultures and Media
Authors: Falk Emily B. , Rameson Lian , Berkman Elliot T. , Liao Betty , Kang Yoona , Inagaki Tristen K. , Lieberman Matthew D.
Published: November 2009

Persuasion is at the root of countless social exchanges in which one person or group is motivated to have another share its beliefs, desires, or behavioral intentions. Here, we report the first three functional magnetic resonance imaging studies to investigate the neurocognitive networks associated with feeling persuaded by an argument. In the first two studies, American and Korean participants, respectively, were exposed to a number of text-based persuasive messages. In both Study 1 and Study 2, feeling persuaded was associated with increased activity in posterior superior temporal sulcus bilaterally, temporal pole bilaterally, and dorsomedial prefrontal cortex. The findings suggest a discrete set of underlying mechanisms in the moment that the persuasion process occurs, and are strengthened by the fact that the results replicated across two diverse linguistic and cultural groups. Additionally, a third study using region-of-interest analyses demonstrated that neural activity in this network was also associated with persuasion when a sample of American participants viewed video-based messages. In sum, across three studies, including two different cultural groups and two types of media, persuasion was associated with a consistent network of regions in the brain. Activity in this network has been associated with social cognition and mentalizing and is consistent with models of persuasion that emphasize the importance of social cognitive processing in determining the efficacy of persuasive communication.
Behavioral and Neural Evidence for Item-specific Performance Monitoring
Authors: Blais Chris , Bunge Silvia
Published: November 2009

How cognitive control is recruited and implemented has become a major focus of researchers in cognitive psychology and neuroscience. Current theories posit that cognitive control operates at the level of general rules—for example, in a Stroop task, “attend to the color of the stimulus.” Here we report behavioral evidence suggesting that cognitive control is implemented much more locally, operating at the level of specific stimuli appearing in a task block. In addition, we report neural evidence that many of the regions implicated in cognitive control on the Stroop task, including anterior cingulate cortex and dorsolateral prefrontal cortex, operate at a local level.
A Psychophysiological Investigation of Moral Judgment after Ventromedial Prefrontal Damage
Authors: Moretto Giovanna , Làdavas Elisabetta , Mattioli Flavia , di Pellegrino Giuseppe
Published: November 2009

Converging evidence suggests that emotion processing mediated by ventromedial prefrontal cortex (vmPFC) is necessary to prevent personal moral violations. In moral dilemmas, for example, patients with lesions in vmPFC are more willing than normal controls to approve harmful actions that maximize good consequences (e.g., utilitarian moral judgments). Yet, none of the existing studies has measured subjects' emotional responses while they considered moral dilemmas. Therefore, a direct link between emotion processing and moral judgment is still lacking. Here, vmPFC patients and control participants considered moral dilemmas while skin conductance response (SCR) was measured as a somatic index of affective state. Replicating previous evidence, vmPFC patients approved more personal moral violations than did controls. Critically, we found that, unlike control participants, vmPFC patients failed to generate SCRs before endorsing personal moral violations. In addition, such anticipatory SCRs correlated negatively with the frequency of utilitarian judgments in normal participants. These findings provide direct support to the hypothesis that the vmPFC promotes moral behavior by mediating the anticipation of the emotional consequences of personal moral violations.
Human Anterior Intraparietal and Ventral Premotor Cortices Support Representations of Grasping with the Hand or a Novel Tool
Authors: Jacobs Stéphane , Danielmeier Claudia , Frey Scott H.
Published: November 2009

Humans display a remarkable capacity to use tools instead of their biological effectors. Yet, little is known about the mechanisms that support these behaviors. Here, participants learned to grasp objects, appearing in a variety of orientations, with a novel, handheld mechanical tool. Following training, psychophysical functions relating grip preferences (i.e., pronated vs. supinated) to stimulus orientations indicate a reliance on distinct, effector-specific internal representations when planning grasping actions on the basis of the tool versus the hands. Accompanying fMRI data show that grip planning in both hand and tool conditions was associated with similar increases in activity within the same regions of the anterior intraparietal and caudal ventral premotor cortices, a putative homologue of the macaque anterior intraparietal–ventral premotor (area F5) “grasp circuit.” These findings suggest that tool use is supported by effector-specific representations of grasping with the tool that are functionally independent of previously existing representations of the hand and yet occur within the same parieto-frontal regions involved in manual prehension. These levels of representation are critical for accurate planning and execution of actions in a manner that is sensitive to the respective properties of these effectors. These effector-specific representations likely coexist with effector-independent representations. The latter were recently reported in macaque F5 [Umiltà, M. A., Escola, L., Intskirveli, I., Grammont, F., Rochat, M., Caruana, F., et al. When pliers become fingers in the monkey motor system. Proceedings of the National Academy of Sciences, U.S.A., 105, 2209–2213, 2008] and appear to be established by tool use training through modification of existing representations of grasping with the hand. These more abstract levels of representation may facilitate the transfer of skills between hand and tool.
Music and Speech Listening Enhance the Recovery of Early Sensory Processing after Stroke
Authors: Särkämö Teppo , Pihko Elina , Laitinen Sari , Forsblom Anita , Soinila Seppo , Mikkonen Mikko , Autti Taina , Silvennoinen Heli M. , Erkkilä Jaakko , Laine Matti , Peretz Isabelle , Hietanen Marja , Tervaniemi Mari
Published: November 2009

Our surrounding auditory environment has a dramatic influence on the development of basic auditory and cognitive skills, but little is known about how it influences the recovery of these skills after neural damage. Here, we studied the long-term effects of daily music and speech listening on auditory sensory memory after middle cerebral artery (MCA) stroke. In the acute recovery phase, 60 patients who had middle cerebral artery stroke were randomly assigned to a music listening group, an audio book listening group, or a control group. Auditory sensory memory, as indexed by the magnetic MMN (MMNm) response to changes in sound frequency and duration, was measured 1 week (baseline), 3 months, and 6 months after the stroke with whole-head magnetoencephalography recordings. Fifty-four patients completed the study. Results showed that the amplitude of the frequency MMNm increased significantly more in both music and audio book groups than in the control group during the 6-month poststroke period. In contrast, the duration MMNm amplitude increased more in the audio book group than in the other groups. Moreover, changes in the frequency MMNm amplitude correlated significantly with the behavioral improvement of verbal memory and focused attention induced by music listening. These findings demonstrate that merely listening to music and speech after neural damage can induce long-term plastic changes in early sensory processing, which, in turn, may facilitate the recovery of higher cognitive functions. The neural mechanisms potentially underlying this effect are discussed.
Affective Priming Effects of Musical Sounds on the Processing of Word Meaning
Authors: Steinbeis Nikolaus , Koelsch Stefan
Published: November 2009

Recent studies have shown that music is capable of conveying semantically meaningful concepts. Several questions have subsequently arisen particularly with regard to the precise mechanisms underlying the communication of musical meaning as well as the role of specific musical features. The present article reports three studies investigating the role of affect expressed by various musical features in priming subsequent word processing at the semantic level. By means of an affective priming paradigm, it was shown that both musically trained and untrained participants evaluated emotional words congruous to the affect expressed by a preceding chord faster than words incongruous to the preceding chord. This behavioral effect was accompanied by an N400, an ERP typically linked with semantic processing, which was specifically modulated by the (mis)match between the prime and the target. This finding was shown for the musical parameter of consonance/dissonance (Experiment 1) and then extended to mode (major/minor) (Experiment 2) and timbre (Experiment 3). Seeing that the N400 is taken to reflect the processing of meaning, the present findings suggest that the emotional expression of single musical features is understood by listeners as such and is probably processed on a level akin to other affective communications (i.e., prosody or vocalizations) because it interferes with subsequent semantic processing. There were no group differences, suggesting that musical expertise does not have an influence on the processing of emotional expression in music and its semantic connotations.
Electrical Stimulation of Broca's Area Enhances Implicit Learning of an Artificial Grammar
Authors: de Vries Meinou H. , Barth Andre C. R. , Maiworm Sandra , Knecht Stefan , Zwitserlood Pienie , Flöel Agnes
Published: November 2009

Artificial grammar learning constitutes a well-established model for the acquisition of grammatical knowledge in a natural setting. Previous neuroimaging studies demonstrated that Broca's area (left BA 44/45) is similarly activated by natural syntactic processing and artificial grammar learning. The current study was conducted to investigate the causal relationship between Broca's area and learning of an artificial grammar by means of transcranial direct current stimulation (tDCS). Thirty-eight healthy subjects participated in a between-subject design, with either anodal tDCS (20 min, 1 mA) or sham stimulation, over Broca's area during the acquisition of an artificial grammar. Performance during the acquisition phase, presented as a working memory task, was comparable between groups. In the subsequent classification task, detecting syntactic violations, and specifically, those where no cues to superficial similarity were available, improved significantly after anodal tDCS, resulting in an overall better performance. A control experiment where 10 subjects received anodal tDCS over an area unrelated to artificial grammar learning further supported the specificity of these effects to Broca's area. We conclude that Broca's area is specifically involved in rule-based knowledge, and here, in an improved ability to detect syntactic violations. The results cannot be explained by better tDCS-induced working memory performance during the acquisition phase. This is the first study that demonstrates that tDCS may facilitate acquisition of grammatical knowledge, a finding of potential interest for rehabilitation of aphasia.
“Virus and Epidemic”: Causal Knowledge Activates Prediction Error Circuitry
Authors: Fenker Daniela B. , Schoenfeld Mircea A. , Waldmann Michael R. , Schuetze Hartmut , Heinze Hans-Jochen , Duezel Emrah
Published: November 2009

Knowledge about cause and effect relationships (e.g., virus–epidemic) is essential for predicting changes in the environment and for anticipating the consequences of events and one's own actions. Although there is evidence that predictions and learning from prediction errors are instrumental in acquiring causal knowledge, it is unclear whether prediction error circuitry remains involved in the mental representation and evaluation of causal knowledge already stored in semantic memory. In an fMRI study, participants assessed whether pairs of words were causally related (e.g., virus–epidemic) or noncausally associated (e.g., emerald–ring). In a second fMRI study, a task cue prompted the participants to evaluate either the causal or the noncausal associative relationship between pairs of words. Causally related pairs elicited higher activity in OFC, amygdala, striatum, and substantia nigra/ventral tegmental area than noncausally associated pairs. These regions were also more activated by the causal than by the associative task cue. This network overlaps with the mesolimbic and mesocortical dopaminergic network known to code prediction errors, suggesting that prediction error processing might participate in assessments of causality even under conditions when it is not explicitly required to make predictions.
Coordinated Roles of Motivation and Perception in the Regulation of Intergroup Responses: Frontal Cortical Asymmetry Effects on the P2 Event-related Potential and Behavior
Authors: Amodio David M.
Published: November 2009

Self-regulation is believed to involve changes in motivation and perception that function to promote goal-driven behavior. However, little is known about the way these processes interact during the on-line engagement of self-regulation. The present study examined the coordination of motivation, perception, and action control in White American participants as they regulated responses on a racial stereotyping task. Electroencephalographic indices of approach motivation (left frontal cortical asymmetry) and perceptual attention to Black versus White faces (the P2 event-related potential) were assessed during task performance. Action control was modeled from task behavior using the process-dissociation procedure. A pattern of moderated mediation emerged, such that stronger left frontal activity predicted larger P2 responses to race, which in turn predicted better action control, especially for participants holding positive racial attitudes. Results supported the hypothesis that motivation tunes perception to facilitate goal-directed action. Implications for theoretical models of intergroup response regulation, the P2 component, and the relation between motivation and perception are discussed.
Feasibility and Safety of Transcatheter Intervention for Complex Patent Ductus Arteriosus
Authors: Yang Shi-Wei , Zhou Yu-Jie , Hu Da-Yi , Liu Yu-Yang , Shi Dong-Mei , Guo Yong-He , Cheng Wan-Jun , Nie Xiao-Min , Wang Jian-Long
Published: November 2009

We evaluated the transcatheter intervention of complex patent ductus arteriosus (PDA) in Chinese adults. Between January 2004 and April 2008, 112 adult patients (43 males, 69 females, mean age 31 ± 19 years) underwent intervention. Coils were used for patients with small PDA, and Amplatzer duct occluders or China-made mushroom-shaped occluders were used for patients with moderate-to-large PDA. The success rate of transcatheter intervention was 93.8%, and 9 patients (8.0%) had small residual shunts. At the end of 12 months follow-up, the rate of residual shunts was 1.8%. Peak systolic pulmonary pressure decreased from 94 ± 21 mm Hg preintervention to 58 ± 20 mm Hg postintervention (P < .001). No severe procedure-related complications (including death, dislocation of occluders, stenosis of aorta or pulmonary artery) occurred. Some patients developed hemolysis or vascular access complications, all resolved by conservative therapy. Transcatheter intervention is an effective and safe treatment for adult PDA patients with complex anatomic or hemodynamic conditions.