bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of early resource-limiting conditions on patterns of growth, growth efficiency, and immune function at emergence in a damselfly (Odonata: Coenagrionidae)
Authors: Dmitriew C. , Cooray M. , Rowe L.
Published: May 2007

Periods of restricted growth during early development are expected to have detrimental effects on subsequent metrics of fitness, most prominently increases in age and decreases in size at maturity. However, in some cases, animals may compensate by altering foraging effort, growth efficiency, or patterns of resource allocation between critical traits prior to maturation. Yet, even when compensation for age and size is complete, brief periods of restricted growth may carry costs persisting in the long term, and compensatory tactics may themselves be costly. We investigated the long-term costs of early growth restriction and mechanisms of compensatory growth in the damselfly Ischnura verticalis (Say, 1839). Larvae were temporarily exposed to one of three feeding regimes in the early stages of development, after which food levels were restored. In the period of unrestricted growth prior to emergence, partial compensation for structural size in the lowest food treatment was observed, while both resource-limited groups accelerated mass gain relative to controls. Changes in food consumption and food conversion efficiency were ruled out as mechanisms for accelerating growth following diet restriction. We tested for changes in resource allocation patterns that could explain the observed compensatory growth and found that adult body shape may depend on early growth conditions in females. There was no evidence of detrimental effects on immune function at emergence, although males tended to have higher phenoloxidase activity (a measure of immunocompetence) than females.
Influence of land use and climate on wetland breeding birds in the Prairie Pothole region of Canada
Authors: Forcey G.M. , Linz G.M. , Thogmartin W.E. , Bleier W.J.
Published: May 2007

Bird populations are influenced by a variety of factors at both small and large scales that range from the presence of suitable nesting habitat, predators, and food supplies to climate conditions and land-use patterns. We evaluated the influences of regional climate and land-use variables on wetland breeding birds in the Canada section of Bird Conservation Region 11 (CA-BCR11), the Prairie Potholes. We used bird abundance data from the North American Breeding Bird Survey, land-use data from the Prairie Farm Rehabilitation Administration, and weather data from the National Climatic Data and Information Archive to model effects of regional environmental variables on bird abundance. Models were constructed a priori using information from published habitat associations in the literature, and fitting was performed with WinBUGS using Markov chain Monte Carlo techniques. Both land-use and climate variables contributed to predicting bird abundance in CA-BCR11, although climate predictors contributed the most to improving model fit. Examination of regional effects of climate and land use on wetland birds in CA-BCR11 revealed relationships with environmental covariates that are often overlooked by small-scale habitat studies. Results from these studies can be used to improve conservation and management planning for regional populations of avifauna.
Landscape features and sea ice influence nesting common eider abundance and dispersion
Authors: Chaulk Keith G. , Robertson Gregory J. , Montevecchi William A.
Published: May 2007

Factors that influence individual and colony spacing are still not well understood in many organisms. Common eiders ( Somateria mollissima (L. 1758)) nest on coastal islands and forage in intertidal and shallow subtidal waters. We considered several biotic and abiotic factors, their interactions, and how these might influence the distribution of eider colonies at several spatial scales in Labrador, Canada. At the island level, nest abundance was not related to intertidal prey density. At the 104 km2grid scale, eider nest abundance and the coefficient of dispersion (CD; the variance to mean ratio of colony size or grid cell, where CD indicates population dispersion) were negatively related to the number of islands. Spring ice cover was positively related to the number of islands but was negatively related to eider nest abundance and to CD. Ice cover – abundance and ice cover – CD were significant at two spatial scales (104 and 455 km2, respectively), but other relationships were weaker at the larger spatial scale. We hypothesize that during the spring, archipelagos with many islands trap ice, providing terrestrial predators access to nesting islands by acting as bridges and that increased predation reduces habitat quality causing nesting eiders to disperse. Our findings suggest that eiders respond to landscape features, including ice cover, a feature that is being influenced by climate change.
Variation in bat and bird fatalities at wind energy facilities: assessing the effects of rotor size and tower height
Authors: Barclay Robert M.R. , Baerwald E.F. , Gruver J.C.
Published: May 2007

Wind energy is a rapidly growing sector of the alternative energy industry in North America, and larger, more productive turbines are being installed. However, there are concerns regarding bird and bat fatalities at wind turbines. To assess the influence of turbine size on bird and bat fatalities, we analyzed data from North American wind energy facilities. Diameter of the turbine rotor did not influence the rate of bird or bat fatality. The height of the turbine tower had no effect on bird fatalities per turbine, but bat fatalities increased exponentially with tower height. This suggests that migrating bats fly at lower altitudes than nocturnally migrating birds and that newer, larger turbines are reaching that airspace. Minimizing tower height may help minimize bat fatalities. In addition, while replacing older, smaller turbines with fewer larger ones may reduce bird fatalities per megawatt, it may result in increased numbers of bat fatalities.
The influence of buoyancy and drag on the dive behaviour of an Arctic seabird, the Thick-billed Murre
Authors: Elliott Kyle H. , Davoren Gail K. , Gaston Anthony J.
Published: May 2007

We used time–depth recorders to investigate the behaviour of free-ranging Thick-billed Murres ( Uria lomvia L., 1758) after attaching positively (n = 9), negatively (n = 10), or neutrally (n = 9) buoyant handicaps and increasing cross-sectional area by 3% (2.8 cm2; n = 8) or 6% (5.6 cm2; n = 6). When buoyancy was altered or drag increased, murres reduced dive depth and duration, suggesting that murres do not manipulate dive depth to obtain neutral buoyancy during the bottom phase. Ascent rate increased as the bird surfaced and mean ascent rate increased for deeper dives, presumably reflecting steeper dive angles and greater buoyancy during deep dives. For short dives (<150 s), preceding surface pauses were better correlated with dive depth and duration than succeeding surface pauses (surface pauses were “anticipatory”), suggesting that murres control inhalation rates based on anticipated dive depth and duration. Murres reduced ascent rate near the surface, possibly to reduce the risk of decompression sickness. Neutrally buoyant recorders attached to the legs had no effect on chick feeding frequencies or adult mass loss, suggesting that this attachment method may have the least effect on the foraging behaviour of alcids.
Moose browsing and forage availability: a scale-dependent relationship?
Authors: Månsson Johan , Andrén Henrik , Pehrson Åke , Bergström Roger
Published: May 2007

Scale dependence is a fundamentally important topic in ecology because it determines whether results can be generalized over different spatial scales. We studied the relationship between forage consumption by moose ( Alces alces (L., 1758)) and forage availability across six nested spatial scales in south-central Sweden. By using multiple regression, we concluded that the amount of available forage was the best single variable explaining absolute consumption, irrespectively of scale. Forage species diversity, site productivity, and moose density were also important for predicting forage consumption, but their effects differed across the different spatial scales. A multiple regression including forage availability, moose density, site productivity, and forage diversity explained between 31% and 49% of the variation in forage consumption. The importance of a moose index as an explanatory variable decreased with increasing spatial scale, whereas the importance of site productivity increased. According to model selection based on Akaike's information criterion, the same model was ranked highest at the four smallest spatial scales, whereas the top-ranked models at the two largest spatial scales differed. Furthermore, the relationship between consumption and forage availability changed from underutilization at small scales to proportional use at the home range level. Thus, for a comprehensive understanding of moose browsing in relation to food resources, we conclude that a multi-scale approach is necessary.
Survival rate of experimental food caches: implications for arctic foxes
Authors: Samelius Gustaf , Alisauskas Ray T. , Larivière Serge
Published: May 2007

Avoiding cache loss is critical to food-hoarding animals. Arctic foxes ( Alopex lagopus (L., 1758)) scatter-hoard thousands of eggs annually at large goose colonies, and we examined how survival rate of experimental caches were influenced by (i) nesting density by geese, (ii) relative proportion of two sympatric goose species, (iii) departure by ca. 1 million geese and their young after hatch, and (iv) age of cache sites. Survival rate of experimental caches was related to age of cache sites in the 1st year of the study (0.80 and 0.56 per 18-day period for caches from new and 1-month-old cache sites, respectively) and departure by geese in the 2nd year of the study (0.98 and 0.74 per 18-day period during and after goose nesting, respectively). These results suggest that food abundance and deterioration of cache sites (e.g., loss of soil cover and partial exposure of caches) were important factors affecting cache loss at our study site. Furthermore, annual variation in the importance of these factors suggests that strategies to prevent cache loss are not fixed in time but vary with existing conditions. Evolution of caching behaviours by arctic foxes may, thus, have been shaped by multiple selective pressures.
ON NONLEPTONIC DECAYS OF THE Λ0-HYPERON IN THE EFFECTIVE QUARK MODEL WITH CHIRAL U(3)×U(3) SYMMETRY
Authors: YA. BERDNIKOV A. , BERDNIKOV YA. A. , FABER M. , IVANOV A. N. , IVANOVA V. A. , NIKITCHENKO A. V. , TROITSKAYA N. I.
Published: May 2007

Within the effective quark model with chiral U (3) × U (3) symmetry we calculate the S-wave and P-wave amplitudes and the partial widths of the nonleptonic decays of the Λ0-hyperon, Λ0 → pπ- and Λ0 → nπ0. The theoretical results agree well with the experimental data. The angular distributions of the decay rates in dependence on the polarizations of baryons are analyzed both in the laboratory frame and in the rest frame of the Λ0-hyperon.
UNCERTAINTY ON DETERMINING THE DARK ENERGY EQUATION OF STATE DUE TO THE SPATIAL CURVATURE
Authors: HUANG ZHUO-YI , WANG BIN , SU RU-KENG
Published: May 2007

We have studied the uncertainty on the determination of the dark energy equation of state due to a nonvanishing spatial curvature by considering some fundamental observables. We discussed the sensitivity of these observables to the value and redshift history of the equation of state and the spatial curvature and investigated whether these different observables are complementary and can help to reduce the cosmic confusion.
STATUS OF STANDARD MODEL CALCULATIONS OF b →s TRANSITIONS
Authors: HURTH TOBIAS
Published: May 2007

We report the recent progress in Standard Model calculations of b→s transitions. We discuss the first NNLL prediction of the [Formula: see text] branching ratio, including important additional subtleties due to nonperturbative corrections and logarithmically-enhanced cut effects, and also the recent results on the inclusive mode [Formula: see text]. Moreover, new results on the corresponding exclusive modes are reviewed. Finally, we comment on the present status of the so-called B→Kπ puzzle in hadronic b→s transitions.
HUMAN-LIKE APPROACH TO FOOTSTEP PLANNING AMONG OBSTACLES FOR HUMANOID ROBOTS
Authors: AYAZ YASAR , MUNAWAR KHALID , MALIK MOHAMMAD BILAL , KONNO ATSUSHI , UCHIYAMA MASARU
Published: May 2007

Unlike wheeled robots, humanoid robots are able to cross obstacles by stepping over or upon them. Conventional 2D methods for robot navigation fail to exploit this unique ability of humanoids and thus design trajectories only by circumventing obstacles. Recently, global algorithms have been presented that take into account this feature of humanoids. However, due to high computational complexity, most of them are very time consuming. In this paper, we present a new approach to footstep planning in obstacle cluttered environments that employs a human-like strategy to terrain traversal. Simulation results of its implementation on a model of the Saika-3 humanoid robot are also presented. The algorithm, being one of reactive nature, refutes previous claims that reactive algorithms fail to find successful paths in complex obstacle cluttered environments.
Neural Organization of the Pathways From the Superior Colliculus to Trochlear Motoneurons
Authors: Izawa Yoshiko , Sugiuchi Yuriko , Shinoda Yoshikazu
Published: May 2007

The neural organization of the pathways from the superior colliculus (SC) to trochlear motoneurons was analyzed in anesthetized cats using intracellular recording and transneuronal labeling techniques. Stimulation of the ipsilateral or contralateral SC evoked excitation and inhibition in trochlear motoneurons with latencies of 1.1–2.3 and 1.1–3.8 ms, respectively, suggesting that the earliest components of excitation and inhibition were disynaptic. A midline section between the two SCs revealed that ipsi- and contralateral SC stimulation evoked disynaptic excitation and inhibition in trochlear motoneurons, respectively. Premotor neurons labeled transneuronally after application of wheat germ agglutinin-conjugated horseradish peroxidase into the trochlear nerve were mainly distributed ipsilaterally in the Forel's field H (FFH) and bilaterally in the interstitial nucleus of Cajal (INC). Consequently, we investigated these two likely intermediaries between the SC and trochlear nucleus electrophysiologically. Stimulation of the FFH evoked ipsilateral mono- and disynaptic excitation and contralateral disynaptic inhibition in trochlear motoneurons. Preconditioning stimulation of the ipsilateral SC facilitated FFH-evoked monosynaptic excitation. Stimulation of the INC evoked ipsilateral monosynaptic excitation and inhibition, and contralateral monosynaptic inhibition in trochlear motoneurons. Preconditioning stimulation of the contralateral SC facilitated contralateral INC-evoked monosynaptic inhibition. These results revealed a reciprocal input pattern from the SCs to vertical ocular motoneurons in the saccadic system; trochlear motoneurons received disynaptic excitation from the ipsilateral SC via ipsilateral FFH neurons and disynaptic inhibition from the contralateral SC via contralateral INC neurons. These inhibitory INC neurons were considered to be a counterpart of inhibitory burst neurons in the horizontal saccadic system.
Integrative pathway knowledge bases as a tool for systems molecular medicine
Authors: Liang Mingyu
Published: May 2007

There exists a sense of urgency to begin to generate a cohesive assembly of biomedical knowledge as the pace of knowledge accumulation accelerates. The urgency is in part driven by the emergence of systems molecular medicine that emphasizes the combination of systems analysis and molecular dissection in the future of medical practice and research. A potentially powerful approach is to build integrative pathway knowledge bases that link organ systems function with molecules.
Smoking Is Associated With Epicardial Coronary Endothelial Dysfunction and Elevated White Blood Cell Count in Patients With Chest Pain and Early Coronary Artery Disease
Authors: Lavi Shahar , Prasad Abhiram , Yang Eric H. , Mathew Verghese , Simari Robert D. , Rihal Charanjit S. , Lerman Lilach O. , Lerman Amir
Published: May 2007

Background—

Smoking is a major risk factor for cardiovascular events. One of the potential mechanisms may be related to both coronary endothelial dysfunction and increased inflammatory response. The present study was designed to test the hypothesis that smoking is associated with epicardial coronary endothelial dysfunction and inflammation.

Methods and Results—

Coronary endothelial function in response to acetylcholine was assessed in 881 patients (115 current smokers and 766 nonsmokers, including 314 previous smokers). Smokers were significantly younger than nonsmokers (43±1 versus 51±1 years,
P
<0.0001), had more epicardial vasoconstriction in response to intracoronary acetylcholine (−19±2% versus −14±1% change in coronary artery diameter,
P
=0.03), and were more likely than nonsmokers to have epicardial endothelial dysfunction (46% versus 35%,
P
=0.005), but their microvascular endothelial function was intact. Smokers had higher white blood cell counts than nonsmokers (7.7±0.2 versus 6.6±0.1×10
9
/L,
P
<0.0001), higher myeloperoxidase (156±19 versus 89±8 ng/mL), higher lipoprotein-associated phospholipase A
2
(242±12 versus 215±5 ng/mL), and higher levels of intracellular adhesion molecule (283±14 versus 252±5 ng/mL). There were no differences in the levels of C-reactive protein, fibrinogen, or vascular cell adhesion molecule between the groups.

Conclusion—

Young smokers are characterized by epicardial coronary endothelial dysfunction, preserved microvascular endothelial function, and increased levels of inflammatory biomarkers and oxidative stress. The present study provides further information regarding the potential mechanisms by which smoking contributes to cardiovascular events.
Cross-Sectional Correlates of Increased Aortic Stiffness in the Community
Authors: Mitchell Gary F. , Guo Chao-Yu , Benjamin Emelia J. , Larson Martin G. , Keyes Michelle J. , Vita Joseph A. , Vasan Ramachandran S. , Levy Daniel
Published: May 2007

Background—

Increased aortic stiffness is associated with numerous common diseases of aging, including heart disease, stroke, and renal disease. However, the prevalence and correlates of abnormally high aortic stiffness are incompletely understood.

Methods and Results—

We evaluated 2 aortic stiffness measures, carotid-femoral pulse wave velocity and forward pressure wave amplitude, in a pooled sample of the Framingham Original, Offspring, and minority Omni cohorts (mean age, 62 years; 56% women). Abnormal stiffness of each measure was defined as a value exceeding the sex-specific 90th percentile of a reference group with a low burden of conventional cardiovascular disease risk factors. Applying this criterion to the entire sample identified a 24% to 33% prevalence of abnormal stiffness measures. The prevalence of abnormal stiffness increased markedly with age, eg, for pulse wave velocity, from a few percent in both sexes aged <50 years to 64% (men) to 74% (women) in those aged ≥70 years. With adjustment for age, important correlates of abnormal aortic stiffness included higher mean arterial pressure, greater body mass index, impaired glucose metabolism, and abnormal lipids. Correlates of aortic stiffness were similar if we used age-specific rather than fixed criteria for defining abnormal stiffness.

Conclusions—

The prevalence of abnormal aortic stiffness increases steeply with advancing age in the community, especially in the presence of obesity or diabetes. Our data suggest that the burden of disease attributable to aortic stiffness is likely to increase considerably over the next few years as the population ages.
Novel Mechanisms of Valsartan on the Treatment of Acute Myocardial Infarction Through Inhibition of the Antiadhesion Molecule Periostin
Authors: Iekushi Kazuma , Taniyama Yoshiaki , Azuma Junya , Katsuragi Naruto , Dosaka Norio , Sanada Fumihiro , Koibuchi Nobutaka , Nagao Kaori , Ogihara Toshio , Morishita Ryuichi
Published: May 2007

Our previous study demonstrated that periostin, an extracellular matrix protein, plays an important role in left ventricular remodeling through the inhibition of cell–cell interactions. Because the gene regulation of periostin has not yet been examined, we focused on the effects of angiotensin (Ang) II and mechanical stretch, because Ang II and mechanical stretch are related to cardiac remodeling after myocardial infarction. First, we examined the effects of Ang II on periostin in myocytes and fibroblasts in vitro. Ang II significantly increased periostin through phosphatidylinositol 3-kinase, c-Jun N-terminal kinase, p38, and extracellular signal-regulated kinase 1/2 pathways in myocytes and fibroblasts (
P
<0.05). On the other hand, mechanical stretch also significantly increased periostin expression (
P
<0.05). This increase was inhibited partially, but significantly, by an Ang II receptor blocker, valsartan, and inhibited almost completely by valsartan with the neutralization antibodies for transforming growth factor-β and platelet-derived growth factor–BB (
P
<0.05). Therefore, we further examined periostin expression in vivo. Periostin expression was significantly increased in infarcted myocardium (
P
<0.05), and treatment with valsartan significantly attenuated it at 4 weeks after myocardial infarction (
P
<0.05), accompanied by a significant improvement in cardiac dysfunction (
P
<0.05). Overall, the present study demonstrated that Ang II, as well as mechanical stretch, stimulated periostin expression in both cardiac myocytes and fibroblasts, whereas valsartan significantly attenuated the increase in periostin expression. The inhibition of periostin by valsartan might especially contribute to its beneficial effects on cardiac remodeling after myocardial infarction.
Treatment of Young Subjects at High Familial Risk of Future Hypertension With an Angiotensin-Receptor Blocker
Authors: Skov Karin , Eiskjær Hans , Hansen Hans Erik , Madsen Jens Kristian , Kvist Stinne , Mulvany Michael John
Published: May 2007

Offspring of hypertensive parents are at high risk of future hypertension and subsequent cardiovascular diseases. We investigated whether early treatment with an angiotensin-receptor blocker in young normotensive offspring of hypertensive parents persistently lowered blood pressure after treatment withdrawal, a possibility supported by animal studies. The study is an investigator-initiated, double-blind study of 110 healthy normotensive subjects aged 18 to 36 years where both parents have essential hypertension randomly assigned to 1 of 2 treatment groups: candesartan (Atacand, Astra Zeneca), 16 mg o.d. or placebo. The intervention period was 12 months, with 24 months of follow-up. Primary outcome was mean 24-hour ambulatory blood pressure recordings (mean AMBP) after 12 and 24 months follow-up and was based on intention to treat (n=110). Secondary outcomes were changes during treatment in mean AMBP, left ventricular mass, renal hemodynamics, and adverse events during intervention and were based on those completing the intervention period (n=105). Primary outcome: At 12 and 24 months follow-up, mean AMBP was not different to placebo. Secondary outcomes: After 12 months of intervention, mean AMBP was reduced: −3.9/−3.4 mm Hg for candesartan versus 0.3/0.6 mm Hg for placebo,
P
<0.0001. Renal vascular resistance and left ventricular mass were also reduced (
P
=0.0007,
P
=0.019, respectively). There were no significant differences in adverse advents between the 2 groups. In conclusion, temporary treatment of subjects at high familial risk of future hypertension with an angiotensin receptor blocker is feasible, but the treatment had no persistent effect on blood pressure when treatment was withdrawn.
Neurophysiological Evidence for the Time Course of Activation of Global Shape, Part, and Local Contour Representations during Visual Object Categorization and Memory
Authors: Schendan Haline E. , Kutas Marta
Published: May 2007

Categorization of visual objects entails matching a percept to long-term representations of structural knowledge. This object model selection is central to theories of human visual cognition, but the representational format(s) is largely unknown. To characterize these neural representations, event-related brain potentials (ERPs) to fragmented objects during an indirect memory test were compared when only local contour features, but not global shapes of the object and its parts, differed between encoding and retrieval experiences. The ERP effects revealed that the format of object representations varies across time according to the particular neural processing and memory system currently engaged. An occipito-temporal P2(00) showed implicit memory modulation to items that repeatedly engaged similar perceptual grouping processes but not items that merely reinstantiated visual features. After 500 msec, memory modulation of a late positive complex, indexing secondary categorization and/or explicit recollection processes, was sensitive to local contour changes. In between, a frontocentral N350, indexing the model selection and an implicit perceptual memory system, showed reactivation of object representations whenever the same global shapes were reactivated, despite local feature differences. These and prior N350 findings provide direct neurophysiological evidence that the neural representations supporting object categorization include knowledge beyond local contours and about higher-order perceptual structures, such as the global shapes of the object and its parts, that can differ between object views. The N350 is proposed to index a second state of interactive, recurrent, and feedback processing in occipital and ventral temporal neocortex supporting higher-order cognitive abilities and phenomenological awareness with objects.
Prefrontal Cortical Response to Conflict during Semantic and Phonological Tasks
Authors: Snyder Hannah R. , Feigenson Keith , Thompson-Schill Sharon L.
Published: May 2007

Debates about the function of the prefrontal cortex are as old as the field of neuropsychology—often dated to Paul Broca's seminal work. Theories of the functional organization of the prefrontal cortex can be roughly divided into those that describe organization by process and those that describe organization by material. Recent studies of the function of the posterior, left inferior frontal gyrus (pLIFG) have yielded two quite different interpretations: One hypothesis holds that the pLIFG plays a domain-specific role in phonological processing, whereas another hypothesis describes a more general function of the pLIFG in cognitive control. In the current study, we distinguish effects of increasing cognitive control demands from effects of phonological processing. The results support the hypothesized role for the pLIFG in cognitive control, and more task-specific roles for posterior areas in phonology and semantics. Thus, these results suggest an alternative explanation of previously reported phonology-specific effects in the pLIFG.
What is Involved and What is Necessary for Complex Linguistic and Nonlinguistic Auditory Processing: Evidence from Functional Magnetic Resonance Imaging and Lesion Data
Authors: Dick Frederic , Saygin Ayse Pinar , Galati Gaspare , Pitzalis Sabrina , Bentrovato Simone , D'Amico Simona , Wilson Stephen , Bates Elizabeth , Pizzamiglio Luigi
Published: May 2007

We used functional magnetic resonance imaging (fMRI) in conjunction with a voxel-based approach to lesion symptom mapping to quantitatively evaluate the similarities and differences between brain areas involved in language and environmental sound comprehension. In general, we found that language and environmental sounds recruit highly overlapping cortical regions, with cross-domain differences being graded rather than absolute. Within language-based regions of interest, we found that in the left hemisphere, language and environmental sound stimuli evoked very similar volumes of activation, whereas in the right hemisphere, there was greater activation for environmental sound stimuli. Finally, lesion symptom maps of aphasic patients based on environmental sounds or linguistic deficits [Saygin, A. P., Dick, F., Wilson, S. W., Dronkers, N. F., & Bates, E. Shared neural resources for processing language and environmental sounds: Evidence from aphasia. Brain, 126, 928–945, 2003] were generally predictive of the extent of blood oxygenation level dependent fMRI activation across these regions for sounds and linguistic stimuli in young healthy subjects.
Predictive Learning, Prediction Errors, and Attention: Evidence from Event-related Potentials and Eye Tracking
Authors: Wills A. J. , Lavric A. , Croft G. S. , Hodgson T. L.
Published: May 2007

Prediction error (“surprise”) affects the rate of learning: We learn more rapidly about cues for which we initially make incorrect predictions than cues for which our initial predictions are correct. The current studies employ electrophysiological measures to reveal early attentional differentiation of events that differ in their previous involvement in errors of predictive judgment. Error-related events attract more attention, as evidenced by features of event-related scalp potentials previously implicated in selective visual attention (selection negativity, augmented anterior N1). The earliest differences detected occurred around 120 msec after stimulus onset, and distributed source localization (LORETA) indicated that the inferior temporal regions were one source of the earliest differences. In addition, stimuli associated with the production of prediction errors show higher dwell times in an eye-tracking procedure. Our data support the view that early attentional processes play a role in human associative learning.
Rhythm and Beat Perception in Motor Areas of the Brain
Authors: Grahn Jessica A. , Brett Matthew
Published: May 2007

When we listen to rhythm, we often move spontaneously to the beat. This movement may result from processing of the beat by motor areas. Previous studies have shown that several motor areas respond when attending to rhythms. Here we investigate whether specific motor regions respond to beat in rhythm. We predicted that the basal ganglia and supplementary motor area (SMA) would respond in the presence of a regular beat. To establish what rhythm properties induce a beat, we asked subjects to reproduce different types of rhythmic sequences. Improved reproduction was observed for one rhythm type, which had integer ratio relationships between its intervals and regular perceptual accents. A subsequent functional magnetic resonance imaging study found that these rhythms also elicited higher activity in the basal ganglia and SMA. This finding was consistent across different levels of musical training, although musicians showed activation increases unrelated to rhythm type in the premotor cortex, cerebellum, and SMAs (pre-SMA and SMA). We conclude that, in addition to their role in movement production, the basal ganglia and SMAs may mediate beat perception.
State of the Art Reviews: Resistance Training for Children and Adolescents
Authors: Faigenbaum Avery D.
Published: May 2007

Although much of what we understand about the stimulus of resistance exercise has been gained by exploring the responses of adults to various training protocols, research into the effects of resistance exercise on children and adolescents has increased over the past decade. Despite outdated concerns that resistance training was ineffective or unsafe for youth, research increasingly suggests that resistance training can be a safe and effective method of exercise for children and adolescents provided that appropriate training guidelines are followed. In addition to enhancing motor skills and sports performance, regular participation in a youth resistance training program has the potential to positively influence several measurable indices of health. It helps strengthen bone, facilitate weight control, enhance psychosocial well-being, and improve one's cardiovascular risk profile. Furthermore, a stronger musculoskeletal system will enable boys and girls to perform life's daily activities with more energy and vigor and may increase a young athlete's resistance to sports-related injuries. Along with other types of physical activity, a properly designed youth resistance training program can offer observable health value to children and adolescents when appropriately prescribed and supervised.
State of the Art Reviews: Smoking Cessation
Authors: Sullivan Karyn M . , Seed Sheila M. , DeBellis Ronald J.
Published: May 2007

Smoking cessation continues to be an area of great concern for public health. Smoking status and willingness to quit should be assessed at every patient visit. A variety of nonprescription and prescription pharmacotherapy options exist for those willing to quit. Medications currently approved by the Food and Drug Administration for smoking cessation include nicotine replacement therapy (gum, lozenge, patch, inhaler, and nasal spray), bupropion sustained release, and the newly approved varenicline. Nortriptyline and clonidine are not indicated for smoking cessation but have been used as second-line agents. This review focuses on each treatment option, including precautions, proper dosing and duration, adverse effects, and medication delivery issues. Attention is also given to individual patient considerations such as combination therapy, pregnancy, postcessation weight gain, and effects of cessation on the current medication regimen.
State of the Art Reviews: Changing and Adhering to Lifestyle Changes
Authors: Harris Michael A. , Oelbaum Rhea , Flomo David
Published: May 2007

Given the relationship between lifestyle and health, researchers have examined those factors that predict healthy lifestyle changes. Several key variables have emerged from the literature, and these variables predict positive lifestyle changes across multiple health domains. More specifically, past health behavior, demographics, personality traits, social support, family functioning, ongoing contact with health care providers, and an individual's social ecology or network predict lifestyle change and adherence to lifestyle interventions. These variables are significant predictors of dietary and exercise regimen adherence, smoking cessation, decreased alcohol consumption, and adherence to medical treatment regimens. In addition, the use of behavioral, multicomponent, culturally specific interventions has proven to yield positive lifestyle changes across multiple health domains. For reasons of brevity, this review focuses on predictors of positive lifestyle change within the realms of diet and physical activity.
Patient Education: The Tapestry of Emotion and Exercise
Authors: Miner Martin
Published: May 2007

In everyday practice, it is important to realize that the tapestry of emotion and body, via the conduit of exercise, is closely linked. Anxiety is reduced following exercise. Depressed patients who exercise maintain their gains longer than those who do not. Exercise is an effective means and adjunct to medical therapy to treat both anxiety and depressive disorders, often present as comorbid disorders.
State of the Art Reviews: The Anti-Inflammatory Actions of Exercise Training
Authors: Flynn Michael G. , McFarlin Brian K. , Markofski Melissa M.
Published: May 2007

The list of diseases with a known inflammatory etiology is growing. Cardiovascular disease, osteoporosis, diabetes, geriatric cachexia, and Alzheimer's disease have all been shown to be linked to or exacerbated by aberrantly regulated inflammatory processes. Nevertheless, there is mounting evidence that those who are physically active, or who become physically active, have a reduction in biomarkers associated with chronic inflammation. There was strong early consensus that exercise-induced reductions in inflammation were explained by body mass index or body fatness, but recent studies provide support for the contention that exercise has body fat—independent anti-inflammatory effects. With few exceptions, the anti-inflammatory effects of exercise appear to occur regardless of age or the presence of chronic diseases. What remains unclear are the mechanisms by which exercise training induces these anti-inflammatory effects, but there are several intriguing possibilities, including release of endogenous products, such as heat shock proteins; selective reduction of visceral adipose tissue mass or reducing infiltration of adipocytes by macrophages; shift in immune cell phenotype; cross-tolerizing effects; or exercise-induced shifts in accessory proteins of toll-like receptor signaling. However, future research endeavors are likely to uncover additional potential mechanisms, and it could be some time before functional mechanisms are made clear. In summary, the potential anti-inflammatory influences of exercise training may provide a low-cost, readily available, and effective treatment for low-grade systemic inflammation and could contribute signifiecantly to the positive effects of exercise training on chronic disease.
Gene-expression analysis identifies novel RBL2/p130 target genes in endemic Burkitt lymphoma cell lines and primary tumors
Authors: De Falco Giulia , Leucci Eleonora , Lenze Dido , Piccaluga Pier Paolo , Claudio Pier Paolo , Onnis Anna , Cerino Giovanna , Nyagol Joshua , Mwanda Walter , Bellan Cristiana , Hummel Michael , Pileri Stefano , Tosi Piero , Stein Harald , Giordano Antonio , Leoncini Lorenzo
Published: May 2007

Burkitt lymphoma (BL) is a B-cell tumor whose characteristic gene aberration is the translocation t(8;14), which determines c-myc overexpression. Several genetic and epigenetic alterations other than c-myc overexpression have also been described in BL. It has been demonstrated that the RBL2/p130 gene, a member of the retinoblastoma family (pRbs), is mutated in BL cell lines and primary tumors. The aim of this study was to investigate the biologic effect of RBL2/p130 in BL cells and its possible role in lymphomagenesis. Therefore, we reintroduced a functional RBL2/p130 in BL cell lines where this gene was mutated. Our results demonstrated that RBL2/p130-transfected cells regain growth control. This suggests that RBL2/p130 may control the expression of several genes, which may be important for cell growth and viability. Gene-expression analysis revealed a modulation of several genes, including CGRRF1, RGS1, BTG1, TIA1, and PCDHA2, upon RBL2/p130 reintroduction. We then monitored their expression in primary tumors of endemic BL as well, demonstrating that their expression resembled those of the BL cell lines. In conclusion, these data suggest that, as RBL2/p130 modulates the expression of target genes, which are important for cell growth and viability, its inactivation may be relevant for the occurrence of BL.
Using gene expression data and network topology to detect substantial pathways, clusters and switches during oxygen deprivation of Escherichia coli
Authors: Schramm Gunnar , Zapatka Marc , Eils Roland , König Rainer
Published: May 2007

Background

Biochemical investigations over the last decades have elucidated an increasingly complete image of the cellular metabolism. To derive a systems view for the regulation of the metabolism when cells adapt to environmental changes, whole genome gene expression profiles can be analysed. Moreover, utilising a network topology based on gene relationships may facilitate interpreting this vast amount of information, and extracting significant patterns within the networks.

Results

Interpreting expression levels as pixels with grey value intensities and network topology as relationships between pixels, allows for an image-like representation of cellular metabolism. While the topology of a regular image is a lattice grid, biological networks demonstrate scale-free architecture and thus advanced image processing methods such as wavelet transforms cannot directly be applied. In the study reported here, one-dimensional enzyme-enzyme pairs were tracked to reveal sub-graphs of a biological interaction network which showed significant adaptations to a changing environment. As a case study, the response of the hetero-fermentative bacterium E. coli to oxygen deprivation was investigated. With our novel method, we detected, as expected, an up-regulation in the pathways of hexose nutrients up-take and metabolism and formate fermentation. Furthermore, our approach revealed a down-regulation in iron processing as well as the up-regulation of the histidine biosynthesis pathway. The latter may reflect an adaptive response of E. coli against an increasingly acidic environment due to the excretion of acidic products during anaerobic growth in a batch culture.

Conclusion

Based on microarray expression profiling data of prokaryotic cells exposed to fundamental treatment changes, our novel technique proved to extract system changes for a rather broad spectrum of the biochemical network.
Induction of MMP-9 release from human dermal fibroblasts by thrombin: involvement of JAK/STAT3 signaling pathway in MMP-9 release
Authors: Wang Li , Luo Jianmin , He Shaoheng
Published: May 2007

Background

It has been recognized that dermal fibroblasts and matrix metalloproteases (MMP) play crucial roles in wound healing process in skin. Thrombin was found to stimulate IL-8 release from human dermal fibroblasts (HDFs). However, little is known of the effect of thrombin on secretion of MMPs from dermal fibroblasts. In the present study, the influence of thrombin on proMMP-2 and proMMP-9 activity release from primary cultured HDFs, and its potential signaling pathways were investigated.

Results

The results showed that thrombin induced proMMP-9, but not proMMP-2 release from HDFs in a dose dependent manner at 6 h following incubation. Thrombin also upregulated expression of proMMP-9 mRNA in HDFs. Hirudin completely abolished the action of thrombin on HDFs. An agonist peptide of protease-activated receptor-1, SFLLR-NH2 stimulated an enhanced release of proMMP-9 from HDFs. AG490, an inhibitor of STAT3 inhibited basal and thrombin-provoked proMMP-9 release and phosphorylation of STAT3. PD98059, an inhibitor of MAPK and LY294002, an inhibitor PI3K failed to significantly inhibit thrombin induced proMMP-9 release.

Conclusion

Thrombin is a potent stimulus of proMMP-9 release from HDFs. Thrombin induced proMMP-9 release is most likely through activation of PAR-1. JAK/STAT3 signaling pathway is involved in proMMP-9 release from HDFs.
Colon cancer risk and different HRT formulations: a case-control study
Authors: Dinger Jürgen C , Heinemann Lothar AJ , Möhner Sabine , Thai Do Minh , Assmann Anita
Published: May 2007

Background

Most studies have found no increased risk of colon cancer associated with hormone replacement therapy (HRT), or even a decreased risk. But information about the effects of different HRT preparations is lacking.

Methods

A case-control study was performed within Germany in collaboration with regional cancer registries and tumor centers. Up to 5 controls were matched to each case of colon cancer. Conditional logistic regression analysis was applied to estimate crude and adjusted odds ratios (OR) and 95% confidence intervals (95% CI). Stratified analyses were performed to get an impression of the risk associated with different estrogens and progestins.

Results

A total of 354 cases of colon cancer were compared with 1422 matched controls. The adjusted overall risk estimate for colon cancer (ColC) associated with ever-use of HRT was 0.97 (0.71 – 1.32). No clinically relevant trends for ColC risk were observed with increasing duration of HRT use, or increasing time since first or last HRT use in aggregate.

Whereas the overall risk estimates were stable, the numbers in many of the sub-analyses of HRT preparation groups (estrogens and progestins) were too small for conclusions. Nevertheless, if the ColC risk estimates are taken at face value, most seemed to be reduced compared with never-use of HRT, but did not vary much across HRT formulation subgroups. In particular, no substantial difference in ColC risk was observed between HRT-containing conjugated equine estrogens (CEE) or medroxyprogesterone acetate (MPA) and other formulations more common in Europe.

Conclusion

Ever-use of HRT was not associated with an increased risk of colon cancer. In contrary, most risk estimates pointed non-significantly toward a lower ColC risk in HRT ever user. They did not vary markedly among different HRT formulations (estrogens, progestins). However, the small numbers and the overlapping nature of the subgroups suggest cautious interpretation.
A model of blood flow in the mesenteric arterial system
Authors: Mabotuwana Thusitha DS , Cheng Leo K , Pullan Andrew J
Published: May 2007

Background

There are some early clinical indicators of cardiac ischemia, most notably a change in a person's electrocardiogram. Less well understood, but potentially just as dangerous, is ischemia that develops in the gastrointestinal system. Such ischemia is difficult to diagnose without angiography (an invasive and time-consuming procedure) mainly due to the highly unspecific nature of the disease.

Understanding how perfusion is affected during ischemic conditions can be a useful clinical tool which can help clinicians during the diagnosis process. As a first step towards this final goal, a computational model of the gastrointestinal system has been developed and used to simulate realistic blood flow during normal conditions.

Methods

An anatomically and biophysically based model of the major mesenteric arteries has been developed to be used to simulate normal blood flows. The computational mesh used for the simulations has been generated using data from the Visible Human project. The 3D Navier-Stokes equations that govern flow within this mesh have been simplified to an efficient 1D scheme. This scheme, together with a constitutive pressure-radius relationship, has been solved numerically for pressure, vessel radius and velocity for the entire mesenteric arterial network.

Results

The computational model developed shows close agreement with physiologically realistic geometries other researchers have recorded in vivo. Using this model as a framework, results were analyzed for the four distinct phases of the cardiac cycle – diastole, isovolumic contraction, ejection and isovolumic relaxation. Profiles showing the temporally varying pressure and velocity for a periodic input varying between 10.2 kPa (77 mmHg) and 14.6 kPa (110 mmHg) at the abdominal aorta are presented. An analytical solution has been developed to model blood flow in tapering vessels and when compared with the numerical solution, showed excellent agreement.

Conclusion

An anatomically and physiologically realistic computational model of the major mesenteric arteries has been developed for the gastrointestinal system. Using this model, blood flow has been simulated which show physiologically realistic flow profiles.