bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency Control of Motor Patterning by Negative Sensory Feedback
Authors: Ausborn Jessica , Stein Wolfgang , Wolf Harald
Published: August 2007

The sensory system plays a key role in the generation of behavior by providing the nervous system with information about the environment and feedback about body movements such that motor output can continuously be adapted to changing circumstances. Although the effects of sensory organs on nervous system function have been demonstrated in many systems, the impact of sensory activity has rarely been studied in conditions in which motor output and sensory activity can interact as they do in behaving animals. In such situations, emergent properties may surface and govern the characteristics of the motor system.

We studied the dynamics of sensorimotor interaction with a combination of electrophysiological experiments and computational modeling in the locust flight pattern generator, including its sensory components. The locust flight motor output is produced by a central pattern generator that interacts with phasic sensory feedback from the tegula, a proprioceptor that signals downstroke movement of the wing. We modeled the flight control system, and we tested the model predictions by replacing tegula feedback in the animal with artificial feedback through computer-controlled electric stimulation of the appropriate sensory nerves.

With reference to the cycle frequency in the locust flight rhythm, our results show that motor patterns can be regulated via the variation of sensory feedback loops. In closed-loop conditions, tegula feedback strength determines cycle frequency in the model and the biological preparation such that stronger feedback results in lower frequencies. This regulatory mechanism appears to be a general emergent property of negative feedback systems.
A Microcircuit Model of the Frontal Eye Fields
Authors: Heinzle Jakob , Hepp Klaus , Martin Kevan A. C.
Published: August 2007

The cortical control of eye movements is highly sophisticated. Not only can eye movements be made to the most salient target in a visual scene, but they can also be controlled by top-down rules as is required for visual search or reading. The cortical area called frontal eye fields (FEF) has been shown to play a key role in the visual to oculomotor transformations in tasks requiring an eye movement pattern that is not completely reactive, but follows a previously learned rule. The layered, local cortical circuit, which provides the anatomical substrate for all cortical computation, has been studied extensively in primary sensory cortex. These studies led to the concept of a “canonical circuit” for neocortex (Douglas et al., 1989; Douglas and Martin, 1991), which proposes that all areas of neocortex share a common basic circuit. However, it has not ever been explored whether in principle the detailed canonical circuit derived from cat area 17 (Binzegger et al., 2004) could implement the quite different functions of prefrontal cortex. Here, we show that the canonical circuit can, with a few modifications, model the primate FEF. The spike-based network of integrate-and-fire neurons was tested in tasks that were used in electrophysiological experiments in behaving macaque monkeys. The dynamics of the model matched those of neurons observed in the FEF, and the behavioral results matched those observed in psychophysical experiments. The close relationship between the model and the cortical architecture allows a detailed comparison of the simulation results with physiological data and predicts details of the anatomical circuit of the FEF.
Neuronal Morphogenesis Is Regulated by the Interplay between Cyclin-Dependent Kinase 5 and the Ubiquitin Ligase Mind Bomb 1
Authors: Choe Eun-Ah , Liao Lujian , Zhou Jian-Ying , Cheng Dongmei , Duong Duc M. , Jin Peng , Tsai Li-Huei , Peng Junmin
Published: August 2007

Neuronal communication requires the coordinated assembly of polarized structures including axons, dendrites, and synapses. Here, we report the identification of a ubiquitin ligase mind bomb 1 (Mib1) in the postsynaptic density and the characterization of its role in neuronal morphogenesis. Expression of Mib1 inhibits neurite outgrowth in cell culture and its gene deletion enhances synaptic growth at the neuromuscular junction inDrosophila. The analysis of Mib1 interactome by mass spectrometry revealed that Mib1 primarily interacts with membrane trafficking proteins [e.g., EEA1 (early endosomal antigen 1), Rab11-interacting proteins, and SNAP25 (synaptosomal-associated protein of 25 kDa)-like protein] and cell adhesion components (e.g., catenin, coronin, dystrobrevin, and syndecan), consistent with its previously reported function in protein sorting. More interestingly, Mib1 is associated with deubiquitinating enzymes, BRCC36 and the mammalian ortholog of fat facets, and a number of kinases, such as casein kinase II, MARK (microtubule affinity regulating kinase)/PAR1, and cyclin-dependent kinase 5 (CDK5). Further characterization of the Mib1-CDK5 interaction indicated that the N-terminal domain of Mib1 directly binds to the regulatory subunit p35 of the CDK5 complex. In cell culture, Mib1 induces the relocalization of p35/CDK5 without affecting its degradation. Surprisingly, p35/CDK5 downregulates the protein level of Mib1 by its kinase activity, and completely rescues the Mib1-induced inhibitory effect on neurite morphology. p35/CDK5 also genetically interacts with Mib1 in the fly according to the rough-eye phenotype. The data strongly support that the negative interplay between Mib1 and p35/CDK5 may integrate the activities of multiple pathways during neuronal development.
Isoform-Selective Susceptibility of DISC1/Phosphodiesterase-4 Complexes to Dissociation by Elevated Intracellular cAMP Levels
Authors: Murdoch Hannah , Mackie Shaun , Collins Daniel M. , Hill Elaine V. , Bolger Graeme B. , Klussmann Enno , Porteous David J. , Millar J. Kirsty , Houslay Miles D.
Published: August 2007

Disrupted-in-schizophrenia 1 (DISC1) is a genetic susceptibility factor for schizophrenia and related severe psychiatric conditions. DISC1 is a multifunctional scaffold protein that is able to interact with several proteins, including the independently identified schizophrenia risk factor phosphodiesterase-4B (PDE4B). Here we report that the 100 kDa full-length DISC1 isoform (fl-DISC1) can bind members of each of the four gene, cAMP-specific PDE4 family. Elevation of intracellular cAMP levels, so as to activate protein kinase A, caused the release of PDE4D3 and PDE4C2 isoforms from fl-DISC1 while not affecting binding of PDE4B1 and PDE4A5 isoforms. Using a peptide array strategy, we show that PDE4D3 binds fl-DISC1 through two regions found in common with PDE4B isoforms, the interaction of which is supplemented because of the presence of additional PDE4B-specific binding sites. We propose that the additional binding sites found in PDE4B1 underpin its resistance to release during cAMP elevation. We identify, for the first time, a functional distinction between the 100 kDa long DISC1 isoform and the short 71 kDa isoform. Thus, changes in the expression pattern of DISC1 and PDE4 isoforms offers a means to reprogram their interaction and to determine whether the PDE4 sequestered by DISC1 is released after cAMP elevation. The PDE4B-specific binding sites encompass point mutations in mouse Disc1 that confer phenotypes related to schizophrenia and depression and that affect binding to PDE4B. Thus, genetic variation inDISC1andPDE4that influence either isoform expression or docking site functioning may directly affect psychopathology.
Amyloid β Protein Modulates Glutamate-Mediated Neurotransmission in the Rat Basal Forebrain: Involvement of Presynaptic Neuronal Nicotinic Acetylcholine and Metabotropic Glutamate Receptors
Authors: Chin James H. , Ma Li , MacTavish David , Jhamandas Jack H.
Published: August 2007

Amyloid β (Aβ) protein, a 39–43 amino acid peptide deposited in brains of individuals with Alzheimer's disease (AD), has been shown to interact directly with a number of receptor targets including neuronal nicotinic acetylcholine receptors (nAChRs) and glutamate receptors. In this study, we investigated the synaptic effects of Aβ1–42on glutamate-mediated neurotransmission in the diagonal band of Broca (DBB), a cholinergic basal forebrain nucleus. Glutamatergic miniature EPSCs (mEPSCs) were recorded using whole-cell patch-clamp recordings from identified cholinergic DBB neurons in rat forebrain slices. In 54% of DBB neurons, bath application of Aβ1–42(100 nm), but not Aβ42–1(inverse fragment), significantly increased the frequency of mEPSCs without affecting amplitude or kinetic parameters (rise or decay time). In 32% of DBB neurons, bath application of Aβ1–42significantly decreased only the frequency but not amplitude of mEPSCs. Application of dihydro-β-erythroidine (DHβE) (an antagonist for the α4β2 subtype of nAChRs) but not α-bungarotoxin (an antagonist for the α7 subtype of nAChRs) blocked Aβ1–42-mediated increases in mEPSC frequency. The Aβ1–42-mediated increase in glutamatergic transmission is thus presynaptic and mediated via non-α7 AChRs. In contrast, Aβ1–42-mediated decreases in mEPSC frequency could not be antagonized by either DHβE or α-bungarotoxin. However, the Aβ1–42-evoked depression in mEPSC frequency was antagonized by (RS)-α-methyl-4-carboxyphenyglycine, a nonselective group I/II metabotropic glutamate receptor antagonist. These observations provide further insight into the mechanisms whereby Aβ affects synaptic function in the brain and may be relevant in the context of synaptic failure observed in AD.
Conductive Hearing Loss Disrupts Synaptic and Spike Adaptation in Developing Auditory Cortex
Authors: Xu Han , Kotak Vibhakar C. , Sanes Dan H.
Published: August 2007

Although sensorineural hearing loss (SNHL) is known to compromise central auditory structure and function, the impact of milder forms of hearing loss on cellular neurophysiology remains mostly undefined. We induced conductive hearing loss (CHL) in developing gerbils, reared the animals for 8–13 d, and subsequently assessed the temporal features of auditory cortex layer 2/3 pyramidal neurons in a thalamocortical brain slice preparation with whole-cell recordings. Repetitive stimulation of the ventral medial geniculate nucleus (MGv) evoked robust short-term depression of the postsynaptic potentials in control neurons, and this depression increased monotonically at higher stimulation frequencies. In contrast, CHL neurons displayed a faster rate of synaptic depression and a smaller asymptotic amplitude. Moreover, the latency of MGv evoked potentials was consistently longer in CHL neurons for all stimulus rates. A separate assessment of spike frequency adaptation in response to trains of injected current pulses revealed that CHL neurons displayed less adaptation compared with controls, although there was an increase in temporal jitter. For each of these properties, nearly identical findings were observed for SNHL neurons. Together, these data show that CHL significantly alters the temporal properties of auditory cortex synapses and spikes, and this may contribute to processing deficits that attend mild to moderate hearing loss.
Attention to Painful Stimulation Enhances γ-Band Activity and Synchronization in Human Sensorimotor Cortex
Authors: Hauck Michael , Lorenz Jürgen , Engel Andreas K.
Published: August 2007

A number of cortical regions are involved in processing pain-related information. The SI and SII somatosensory cortices process mainly sensory discriminative attributes but also play an important role in recognition and memory of painful events. Regions such as SII and the posterior insula appear to be the first stations that house processes by which attention profoundly shapes both behavioral responses and subjective pain experience. We investigated the influence of directed attention on pain-induced oscillations and synchronization processes using magnetoencephalogram in combination with an oddball paradigm in 20 healthy subjects. The subject's task was to count rare painful electrical stimuli applied to one finger, while ignoring frequent stimuli at a different finger. A high detection ratio was observed for all blocks and subjects. Early evoked oscillations in the δ-band increased with higher stimulus intensity and directed attention, most prominently at contralateral sensorimotor sites. Furthermore, suppression and rebound of β activity were observed after painful stimulation. Moreover, induced oscillatory activity in the high γ-band increased with directed attention, an effect being significantly stronger for high compared with low stimulus intensity. Coupling analysis performed for this high γ response revealed stronger functional interactions between ipsilateral and contralateral sites during attention. We conclude that pain-induced high-frequency activity in sensorimotor areas may reflect an attentional augmentation of processing, leading to enhanced saliency of pain-related signals and thus to more efficient processing of this information by downstream cortical centers.
Increasing Sulfatide Synthesis in Myelin-Forming Cells of Arylsulfatase A-Deficient Mice Causes Demyelination and Neurological Symptoms Reminiscent of Human Metachromatic Leukodystrophy
Authors: Ramakrishnan Hariharasubramanian , Hedayati Kerstin Khalaj , Lüllmann-Rauch Renate , Wessig Carsten , Fewou Simon Ngamli , Maier Helena , Goebel Hans-Hilmar , Gieselmann Volkmar , Eckhardt Matthias
Published: August 2007

Metachromatic leukodystrophy (MLD) is a lysosomal storage disorder caused by the deficiency of arylsulfatase A (ASA). This results in accumulation of sulfated glycosphingolipids, mainly 3-O-sulfogalactosylceramide (sulfatide), in the nervous system and various other organs. In patients, lipid storage causes a progressive loss of myelin leading to various neurological symptoms. The sulfatide storage pattern in ASA-deficient [ASA(−/−)] mice is comparable to humans, but regrettably, the mice do not mimic the myelin pathology. We reasoned that increasing sulfatide storage in this animal model might provoke demyelination. Therefore, we generated transgenic ASA(−/−) [tg/ASA(−/−)] mice overexpressing the sulfatide-synthesizing enzyme galactose-3-O-sulfotransferase-1 in myelinating cells. Indeed, these tg/ASA(−/−) mice displayed a significant increase in sulfatide storage in brain and peripheral nerves. Mice older than 1 year developed severe neurological symptoms. Nerve conduction velocity was significantly reduced in tg/ASA(−/−) mice because of a peripheral neuropathy characterized by hypomyelinated and demyelinated axons. Inhomogeneous myelin thickness in the corpus callosum, increased frequency of hypomyelinated and demyelinated axons in corpus callosum and optic nerve, and substantially reduced myelin basic protein levels are in accordance with loss of myelin in the CNS. Thus, increasing sulfatide storage in ASA(−/−) mice leads to neurological symptoms and morphological alterations that are reminiscent of human MLD. The approach described here may also be applicable to improve other mouse models of lysosomal as well as nonlysosomal disorders.
Following the Nyinkka: Relations of Respect and Obligations to Act in the Collaborative Work of Aboriginal Cultural Centers
Authors: Christen Kimberly
Published: August 2007

In July 2003 the Warumungu Aboriginal community opened the Nyinkka Nyunyu Art and Culture Centre in Tennant Creek, Northern Territory, Australia. Nyinkka Nyunyu is a Warumungu community center, museum, and tourist destination. As such it embodies the eclectic and practical modalities of Aboriginal business. This article examines the practices of Aboriginal representation and self‐determination through the behind‐the‐scenes work of community consultation, collaboration, and culturemaking. Looking to existing social relations and systems of obligation, the Warumungu community's production of the visual displays for the Centre demonstrates the interdependent networks forged out of a colonial history of displacement and a present trajectory of alliance‐building.
Changes in the Style, Production and Distribution of Pottery in Santa María Atzompa, Oaxaca, Mexico during the 1990s
Authors: Thieme Mary S.
Published: August 2007

The potters of Santa María Atzompa, a town located in the Valley of Oaxaca in Southern Mexico, have been making pottery for at least 500 years. The town has been widely known for its production of green glazed cookware and ornamental pottery, which is sold throughout the State of Oaxaca and beyond. Beginning in the mid‐1990s, to a large extent as a result of public concern, publicity, and legislation about the lead glaze, which they have been using since the Colonial Period, the potters changed the style, distribution and social context of their ceramics production. This paper examines the town's pottery industry through time, focusing on the household as a key social unit.
Exploring a Literacy Website That Works: ReadWriteThink.org
Authors: Anderson Rebecca S. , Balajthy Ernest
Published: August 2007

While it is easy to find lesson plans on the Internet, the quality of plans and the formats in which they are written vary considerably, and the process of sifting through the chaff in order to find the wheat can be time‐consuming and discouraging. To address these concerns the authors of this Technology in Literacy column introduce www.ReadWriteThink.org. The International Reading Association (IRA), the National Council of Teachers of English (NCTE), and a consortium of other organizations developed the site, which provides lessons in reading and writing, as well as many other interactive features that provide unique supports for teachers:

Lessons are written and reviewed by literacy educators.

Lessons are carefully screened and edited to save teachers from wasting time with poorly prepared materials.

Lessons are linked to other lessons in the collection with related objectives, activities, or themes, to help teachers develop focused units of study.

Lessons are offered in a level of detail that far surpasses the lesson plans provided at most other educational sites.

Lessons include many online activities and resources that can be accessed easily to save teachers from spending time in looking for necessary materials.

Resource links are provided in the body of the lesson, as well as in a sidebar accompanying the lesson.

Links to sites offering further information and resources are kept up‐to‐date.

Lessons are aligned to the IRA/NCTE Standards for the English Language Arts.
Tapping Students' Cultural Funds of Knowledge to Address the Achievement Gap
Authors: Risko Victoria J. , Walker‐Dalhouse Doris
Published: August 2007

Students whose language, ethnicity, and race are not represented in a school's dominant culture experience varying degrees of success in reading achievement, resulting in persistent gaps in reading achievement. Culturally responsive instruction can help to close that gap. This teaching strategy capitalizes on the knowledge and literacy strategies students learn in their homes and communities, the ways that students reason about and make sense of their world, and the language and communicative patterns of students.

In this article, the authors provide a discussion of cultural modeling as one example of how to design culturally responsive instruction. Cultural modeling is a way of designing instruction to make explicit connections between content and literacy goals and the knowledge and experiences students share with family, community, and peers.
Learning From Abdallah: A Case Study of an Arabic‐Speaking Child in a U.S. School
Authors: Palmer Barbara C. , El‐Ashry Fathi , Leclere Judith T. , Chang Sara
Published: August 2007

Abdallah, an Arabic‐speaking, Palestinian 9‐year‐old student, was observed as he worked to understand his new English language and culture. Some issues and questions addressed in the article include effective methodologies for the assessment of literacy development in the Arabic and English languages, effective instructional strategies to scaffold Arabic‐speaking children's English language learning, and linguistic factors that might affect the Arabic‐speaking students' transition to English. The article sets forth theoretical underpinnings for the chosen assessment and instructional strategies and a summary of supporting research in the area of Arabic‐speaking English‐language learners. If teachers are to be prepared to design and implement instruction for Arabic‐speaking English‐language learners, they must have an understanding of the linguistic and cultural characteristics of this population, the differences between the Arabic and English languages, and effective strategies for assessing and scaffolding language and literacy development.
Implementing a Schoolwide Literacy Framework: Improving Achievement in an Urban Elementary School
Authors: Fisher Douglas , Frey Nancy
Published: August 2007

Teachers at an urban elementary school developed and implemented a literacy instructional framework based on a gradual release of responsibility model. The framework included

focus lessons

guided instruction

collaborative learning

independent learning

Over six years, literacy and math achievement at this school increased dramatically. The teachers at the school attribute the changes to the focused professional development they received that was based on a literacy framework they created.
Teaching Economics Through Children's Literature in the Primary Grades
Authors: Rodgers Yana V. , Hawthorne Shelby , Wheeler Ronald C.
Published: August 2007

Primary‐grade students can gain exposure to a wide range of economic concepts in state standards if teachers use reading strategies that embrace children's literature with economic content. This approach allows teachers to teach their students reading strategies and economics simultaneously. Almost all states have content standards in economics, beginning with kindergarten. Our review has identified well over 300 picture books and easy readers that focus on economic concepts found in the state standards. We selected a number of these books and arranged them into groups of five by economic concept. The selection of a book into the “top five” is based on objective criteria and on direct experience in teaching with the books. The longer list, which is found at a complementary website, and the top‐five selections should prove useful given the current trend in numerous states to link English standards to required readings with topics in the social sciences.
Pen Pal Letter Exchanges: Taking First Steps Toward Developing Cultural Understandings
Authors: Barksdale Mary Alice , Watson Carol , Park Eun Soo
Published: August 2007

This article describes a qualitative research project that examined pen pal letters exchanged between children in Virginia, USA, and Malawi in Sub‐Saharan Africa. The goal was to study the nature of communication between students living in these two very different cultural contexts. The results of this study indicated that there were three primary themes within the pen pal letters between the primary and elementary students: daily life and culture, language, and connections. The students enjoyed sharing information about all aspects of their daily life and culture with their pen pals, and they were able to communicate meaningfully with one another on these topics. The students followed the language patterns established by one another in their letters, and they made attempts to use terminology that would be readily understandable to one another. Each theme found in the study is explored, and the value of using pen pal exchanges to support the development of literacy and cultural understandings is discussed. Recommendations are made for establishing pen pal exchanges in international contexts.
Utilité clinique de trois outils d'évaluation pour les personnes atteintes de démence
Authors: Hébert Michèle , Thibeault Rachel , Sacolax Nickolas , Tandon Kajal , Germain Mélanie , Bruneau Philippe , Gravel Jean
Published: August 2007

Description : Les ergothérapeutes sont de plus en plus sollicités dans la démarche diagnostique des atteintes cognitives chez la personne âgée. But : Trois outils pouvant aider au processus d'évaluation ont été étudiés pour documenter leurs qualités diagnostiques et la nature de l'association de leurs résultats : le Mini-Mental State Examination (MMSE), le Protocole d'examen cognitif de la personne âgée (PECPA-2r) et le Système de mesure de l'autonomie fonctionnelle (SMAF). Méthodologie : Une étude corrélationnelle transversale a permis de documenter l'association entre les résultats obtenus avec les trois outils alors qu'ils étaient utilisés auprès de personnes âgées référées au projet par leur médecin traitant. Résultats : Les résultats de L'étude, réalisée auprès de 52 personnes âgées chez qui une atteinte cognitive était soupçonnée, ont montré qu'une corrélation très forte existe entre les scores obtenus aux trois outils d'évaluation. Les scores au MMSE seraient d'excellents prédicteurs des scores au PECPA-2r et au SMAF. La sévérité de l'atteinte cognitive serait un bon prédicteur du niveau d'atteinte de l'autonomie. Conséquences pour la pratique : Certaines observations faites par les évaluateurs lors de l'administration des PECPA-2r et SMAF se sont révélées particulièrement utiles à la démarche diagnostique ultérieure faite par le médecin traitant. Le court temps d'administration du MMSE ne permettait pas de telles observations alors que les PECPA-2r et SMAF offraient ce temps propice à l'observation. Les ergothérapeutes sont invités à examiner avec attention leurs intentions cliniques alors qu'ils choisissent leurs outils d'évaluation.
Utilisation de la télésurveillance auprès des personnes âgées à domicile: pratiques actuelles et potentielles
Authors: Caouette Amélie , Vincent Claude , Montreuil Benoit
Published: August 2007

Description. L'utilisation des services de télésurveillance connaît un essor chez les aînés. À cet égard, les ergothérapeutes recommandent depuis longtemps des systèmes d'appel d'urgence qui sont liés à des centrales de télésurveillance. But. Cette étude vise à documenter les utilisations actuelles et potentielles des services de télésurveillance dans un contexte de soutien à domicile auprès des aînés ainsi que les impacts de ces services sur la pratique des ergothérapeutes. Méthodologie. Pour ce faire, une recension des écrits scientifiques portant sur les utilisations de la télésurveillance a été réalisée et le Modèle canadien de rendement occupationnel a été employé pour les répertorier. Résultats. La recension des écrits révèle que le monitorage à distance des composantes physiques et cognitives chez l'aîné à l'aide des nouvelles technologies d'information et de télécommunications s'avère efficace sur le plan clinique et qu'il existe des impacts positifs sur la composante affective de la personne ainsi que sur l'environnement social, physique et institutionnel. Au niveau du monitorage des occupations dans le domicile, la recherche et développement est prometteuse pour les soins personnels comme le suivi des déplacements, du sommeil, de la prise de médicaments et de la routine de vie. Conséquences pour la pratique. L'arrivée sur le marché de nouveaux services de télésurveillance permettra de suivre en mode continu les progrès des aînés à domicile, de façon non invasive, et d'intervenir précocement lors d'une perturbation dans les occupations quotidiennes.
Description de la pratique des ergothérapeutes du Québec en salle d'urgence
Authors: Veillette Nathalie , Demers Louise , Dutil Élisabeth
Published: August 2007

Introduction. Les ergothérapeutes interviennent à l'urgence, mais on ne connaît pas l'ampleur et la nature de cette pratique. Objectif. Décrire la pratique professionnelle des ergothérapeutes du Québec à l'urgence. Méthodologie. Questionnaire postal aux membres de l'Ordre des ergothérapeutes du Québec portant sur le contexte général de pratique, la nature des interventions, les outils d'évaluation, les modèles de pratique et la satisfaction au travail à l'urgence. Résultats. Les ergothérapeutes oeuvrant à l'urgence pratiquent dans plusieurs régions socio-administratives du Québec depuis un maximum de 11 ans. Ils consacrent plus de 90% du temps à la clientèle âgée et sont intégrés à des équipes interdisciplinaires. Ils évaluent diverses sphères du fonctionnement et 75% utilisent des outils maison. Les difficultés rencontrées affectent le deux tiers des répondants qui se disent neutres ou insatisfaits par rapport à cette pratique. Conséquences pour la pratique. Les répondants ont confirmé l'émergence de l'ergothérapie à l'urgence et la nécessité d'être mieux outillé pour faire face aux difficultés rencontrées dans leur pratique.
Multi-Scaffolding Environment: An Analysis of Scaffolding and its Impact on Cognitive Load and Problem-Solving Ability
Authors: Doering Aaron , Veletsianos George
Published: August 2007

A Multi-Scaffolding Environment (MSE) is a multimedia environment reliant on authentic scaffolding. We examine the impact of the availability of multiple scaffolds on learning and cognitive load within an MSE where learners are assigned a real-world task and given access to four support tools to help them complete the task. By examining an MSE in the area of geographic literacy, we explore the effectiveness of problem-based learning and whether multiple scaffolding is applicable to any content area. Quantitative and qualitative data indicate that a learner-controlled multi-scaffolding approach may be a valuable approach in problem-based learning contexts.
Differential course of HIV-1 infection and apolipoprotein E polymorphism
Authors: Corder Elizabeth , Galeazzi Luciano , Franceschi Claudio , Cossarizza Andrea , Paganelli Roberto , Pinti Marcello , Mussini Cristina , Borghi Vanni , Pinter Elena , Cristofaro Rita , Galeazzi Roberta , Perini Marino , Aiuti Fernando , Giunta Sergio
Published: August 2007

We studied the course of infection with human immunodeficiency virus type 1 (HIV-1) in relation to apolipoprotein E (APOE) polymorphism found for 209 Italians treated at Infectious Disease Clinics in Rome and Modena. Clinically, patients were classified into four groups according to the yearly rate of decline in CD4+ cell count (LTNP: long-term non-progression; SLOW, ’NORMAL’ or RAPID). Patients at both extremes of the clinical spectrum, i.e. those who rapidly progressed to AIDS and those with stable high CD4 cell counts, had few APOE ɛ4 and ɛ2 alleles (P = 0.04). Detailed clinical information was then used to construct four model-based clinical profiles using grade-of-membership analysis (GoM), predictive of APOE genotypic frequencies: 1. The clinical profile associated with good long-term prognosis lacked ɛ2 (P=0.01); 2. Disease progression to AIDS was associated with ɛ4 and ɛ2, most evident for zidovudine-lamivudine regimens without a protease inhibitor (P = 0.03); and, 3. AIDS patients had low ɛ4 and ɛ2 frequencies, consistent with a high mortality rate among ɛ4+ and ɛ2+ AIDS patients. These findings suggest allele-specific immunomodulatory effects involving inherited APOE isoform important enough to alter the clinical course of HIV infection and, possibly, drug efficacy. They imply a connection between lipid metabolism and immunity potentially relevant to common disorders.
Cytosolic phospholipase A2 regulation in the hibernating thirteen-lined ground squirrel
Authors: Woods Ashley , Storey Kenneth
Published: August 2007

Cytosolic calcium-dependent phospholipase A2 (cPLA2) has multiple roles including production of arachidonic acid (a key player in cellular signaling pathways) and membrane remodeling. Additionally, since catabolism of arachidonic acid generates free radicals, the enzyme is also implicated in ischemic injury to mammalian organs. Regulation of cPLA2 could be important in the suppression and prioritization of cellular pathways in animals that undergo reversible transitions into hypometabolic states. The present study examines the responses and regulation of cPLA2 in skeletal muscle and liver of hibernating thirteen-lined ground squirrels, Spermophilus tridecemlineatus. cPLA2 activity decreased significantly by 43% in liver during hibernation, compared with euthermic controls, and Km values for arachidonoyl thio-PC substrate fell in both organs during hibernation to 61% in liver and 28% in muscle of the corresponding euthermic value. To determine whether these responses were due to a change in the phosphorylation state of the enzyme, Western blotting was employed using antibodies recognizing phospho-Ser505 on α-cPLA2. The amount of phosphorylated α-cPLA2 in hibernator liver was just 38% of the value in euthermic liver. Furthermore, incubation of liver extracts under conditions that enhanced protein phosphatase action caused a greater reduction in the detectable amount of phospho-Ser505 enzyme content in euthermic, versus hibernator, extracts. The data are consistent with a suppression of cPLA2 function during torpor via enzyme dephosphorylation, an action that may contribute to the well-developed ischemia tolerance and lack of oxidative damage found in hibernating species over cycles of torpor and arousal.
Mechanical properties of photoaged in situ polymerized PS/EPDM blends
Authors: Lourenço Emerson , Felisberti Maria Isabel
Published: August 2007

In this study, the mechanical properties of in situ polymerized PS/EPDM blends with different composition were evaluated before and after accelerated photoaging and compared with the properties of commercial HIPS submitted to similar aging conditions (ASTM G53). The mechanical properties of the PS/EPDM blends as well as their photochemical stability are influenced by the polymerization temperature and blend composition. Although the initial mechanical properties of HIPS are superior in comparison with the in situ polymerized PS/EPDM blends, a pronounced drop of them was observed already for short time exposure. For example, after the aging period, all PS/EPDM blends showed higher strain at break than HIPS. Because PS/EPDM blends present higher resistance to photoaging stability than HIPS, the mechanical properties of the HIPS become worse than the other blends as the aging time increases. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Analyzing the dynamic chemorheology of curing resins: Extraction of model parameters associated with cure advancement
Authors: Love B. J. , Piguet‐Ruinet F.
Published: August 2007

The assessment of transient changes in reactive fluids has been described as chemorheology. While several individual chemorheological studies are published, few have investigated unifying principles that may help in identifying protocols for predictive modeling. We have extracted datasets from other published manuscripts on reactive resin curing, and have observed a range of exponential growth in viscosity with these reactive systems. We have found that regardless of the initial viscosity, the dynamic viscosity rise in many of these resins advances with a similar exponential rise, with the exponent varying between 0.02 and 1.5 min−1 Isothermal photopolymerization yielded more accurate viscosity models than corresponding crosslinked resins with a widely varying heating schedule. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Synthesis and comparative properties of poly(dimethylsiloxane) grafted alkyl acrylate
Authors: Yang Xue‐feng , Yao Cheng
Published: August 2007

Low hydrogen‐containing siloxane (l‐PDMS) material was prepared by H2SO4‐catalyzed equilibration of octa‐methyl cyclo tetra siloxane (D4), hexamethyl disiloxane (MM) and high hydrogen‐containing siloxane (h‐PDMS). Poly(dimethylsiloxane) (PDMS) grafted methyl acrylate (MA), ethyl acrylate (EA), and butyl acrylate (BA) were prepared by Pt‐catalyzed hydrosilylation reaction of l‐PDMS and three acrylates, respectively. PDMS grafted alkyl acrylate not only preserves the properties of PDMS, but also adds new ones. Viscosity, viscosity–temperature coefficient (VTC), viscosity‐index (VI), and TGA experiments indicate that the grafted copolymers have outstanding thermal stability as PDMS. The measurement of surface tension (ST) shows the grafted copolymers have low surface energy as PDMS. However, emulsifiability, lubricity, and solubility in organic solvent, such as acetone, isopropanol, of PDMS grafted alkyl acrylate were better than the properties of PDMS, which can be very useful for fine chemical industry. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Enhanced integrative repair of the porcine meniscus in vitro by inhibition of interleukin‐1 or tumor necrosis factor α
Authors: McNulty Amy L. , Moutos Franklin T. , Weinberg J. Brice , Guilak Farshid
Published: August 2007

Objective

To examine the hypotheses that increasing concentrations of interleukin‐1 (IL‐1) or tumor necrosis factor α (TNFα) inhibit the integrative repair of the knee meniscus in an in vitro model system, and that inhibitors of these cytokines will enhance repair.

Methods

Explants (8 mm in diameter) were harvested from porcine medial menisci. To simulate a full‐thickness defect, a 4‐mm–diameter core was removed and reinserted. Explants were cultured for 14, 28, or 42 days in the presence of 0–1,000 pg/ml of IL‐1 or TNFα. Explants were also cultured in the presence of IL‐1 or TNFα with IL‐1 receptor antagonist (IL‐1Ra) or TNF monoclonal antibody (mAb). At the end of the culture period, biomechanical testing, cell viability, and histologic analyses were performed to quantify the extent of repair.

Results

Mechanical testing revealed increased repair strength, cell accumulation, and tissue formation at the interface over time under control conditions. Pathophysiologic concentrations of both IL‐1 and TNFα significantly decreased repair strength, cell migration, and tissue formation at the interface. The addition of IL‐1Ra or TNF mAb to explants prevented the effects of IL‐1 or TNFα, respectively.

Conclusion

Our findings document that physiologically relevant concentrations of IL‐1 and TNFα inhibit meniscal repair in vitro and therefore may also inhibit meniscal repair during arthritis or following joint injury. The finding that IL‐1Ra and TNF mAb promoted integrative meniscal repair in an inflammatory microenvironment suggests that intraarticular delivery of IL‐1Ra and/or TNF mAb may be useful clinically to promote meniscal healing following injury.
Prevalence of hypospadias in the same geographic region as ascertained by three different registries
Authors: Nelson Paul , Nieuwenhuijsen Mark , Jensen Tina Kold , Mouriquand Pierre , Hughes Ieuan , Wilcox Duncan , Elliott Paul
Published: August 2007

Hypospadias birth prevalence may be increasing with maternal exposure to endocrine disrupters. Yet hypospadias registers are hindered by data quality concerns. We compare the birth prevalence per thousand male births (BP) and ascertainment of hypospadias in the South East of England between 1st January 1997 to 31st September 1998 in a population‐based hypospadias case register (surgeons' register) 731 cases, BP 3.8, (95% confidence interval 3.7–3.9), the National Congenital Anomaly System (NCAS) 645 cases (88% of surgeons' register), BP 3.4, (95% confidence interval 3.29–3.5) and Hospital Episode Statistics (HES) 221 cases (30% of the surgeons register), BP 1.15 (95% confidence interval 1.1–1.2). There were 191,438 male births (National Statistics). We found considerable differences in birth prevalence estimates and ascertainment according to data source. Compared with the Surgeons' register, the HES under‐ascertainment of 10% was possibly explained by procedural weaknesses. NCAS's 70% under‐ascertainment is explained by exclusion of so‐called mild hypospadias (since 1990). This exclusion does not appear warranted since mild and severe hypospadias probably share aetiology and all require surgery. NCAR's utility could be improved if it returned to including “minor” hypospadias. Meanwhile routine data such as HES are potentially suitable for surveillance of this condition. Birth Defects Research (Part A), 2007. © 2007 Wiley‐Liss, Inc.
High prevalence of NTDs in Shanxi Province: A combined epidemiological approach
Authors: Gu Xue , Lin Liangming , Zheng Xiaoying , Zhang Ting , Song Xinming , Wang Jinfeng , Li Xinhu , Li Peizhen , Chen Gong , Wu Jilei , Wu Lihua , Liu Jufen
Published: August 2007

BACKGROUND: Shanxi Province has historically reported a high prevalence of NTDs. In order to establish baseline rates for NTDs and discuss the risk factors associated with sociodemographic, maternal characteristics, and geographic factors, we performed the present study using an approach combining population and hospital‐based methodologies. METHODS: We used χ2 and Fisher's exact tests to evaluate variation in the prevalence by selected covariates and computed crude ORs and 95% CIs. Adjusted odds ratios (AORs) were performed using logistic regression with all the covariates included in the model. RESULTS: The overall NTD prevalence during the 3 year study period was 199.38 per 10,000 births, with a higher NTD prevalence clustered in 46 villages within this geographic area. However, no statistical significance was found between NTD prevalence and the elevation of the villages or their distance from coal plants. AORs revealed women aged 20 and above had a lower risk of NTDs compared to those younger than 20 (AOR range 0.4–0.5). A higher risk of NTDs was observed among female infants (AOR 1.50; 95% CI: 1.04–2.17), women with four or more previous births (AOR 2.80; 95% CI: 1.20–6.52), and a previous history of birth defects (AOR 3.23; 95% CI: 1.46–7.12). CONCLUSIONS: This study has documented a high prevalence of NTDs in Shanxi. Similar variations to other reports were found in the risk of NTDs by maternal demographic characteristics and a clustering of NTDs in certain villages that require further exploration. Birth Defects Research (Part A), 2007. © 2007 Wiley‐Liss, Inc.
Seeking causes: Classifying and evaluating congenital heart defects in etiologic studies
Authors: Botto Lorenzo D. , Lin Angela E. , Riehle‐Colarusso Tiffany , Malik Sadia , Correa Adolfo
Published: August 2007

BACKGROUND: Classification and analysis of congenital heart defects (CHD) in etiologic studies is particularly challenging because of diversity of cardiac phenotypes and underlying developmental mechanisms. We describe an approach to classification for risk assessment of CHD based on developmental and epidemiologic considerations, and apply it to data from the National Birth Defect Prevention Study (NBDPS). METHODS: The classification system incorporated the three dimensions of cardiac phenotype, cardiac complexity, and extracardiac anomalies. The system was designed to facilitate the assessment of simple isolated defects and common associations. A team with cardiologic expertise applied the system to a large sample from the NBDPS. RESULTS: Of the 4,703 cases of CHDs in the NBDPS with birth years 1997 through 2002, 63.6% were simple, isolated cases. Specific associations of CHDs represented the majority of the remainder. The mapping strategy generated relatively large samples for most cardiac phenotypes and provided enough detail to isolate important subgroups of CHDs that may differ by etiology or mechanism. CONCLUSIONS: Classification of CHDs that considers cardiac and extracardiac phenotypes is practically feasible, and yields manageable groups of well‐characterized phenotypes. Although best suited for large studies, this approach to classification and analysis can be a flexible and powerful tool in many types of etiologic studies of heart defects. Birth Defects Research (Part A), 2007. © 2007 Wiley‐Liss, Inc.
Discrete Stochastic Models for Compliance Analysis Based on an AIDS Clinical Trial Group (ACTG) Study
Authors: Sun Junfeng , Nagaraj H. N. , Reynolds Nancy R.
Published: August 2007

Compliance is the extent to which a patient follows the prescribed regimen. Here we investigate the statistical properties of two popular measures of compliance – percentage of compliant days and percentage of doses taken. We use a stationary Markov chain to model the dependence structure of successive data points for each subject. We illustrate our model using discrete compliance data collected from an AIDS Clinical Trial Group study (ACTG 398). We check the model assumptions and evaluate the small sample as well as large sample properties of our estimators. We show that ignoring the within‐subject dependence will usually underestimate the standard errors of the estimates of these compliance measures. Our model allows the application of meta‐analytic approaches to assess the variation across subjects in these compliance indices and changes in them due to intervention. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
From dummy regression to prior probabilities in PLS‐DA
Authors: Indahl Ulf G. , Martens Harald , Næs Tormod
Published: August 2007

Different published versions of partial least squares discriminant analysis (PLS‐DA) are shown as special cases of an approach exploiting prior probabilities in the estimated between groups covariance matrix used for calculation of loading weights. With prior probabilities included in the calculation of both PLS components and canonical variates, a complete strategy for extracting appropriate decision spaces with multicollinear data is obtained. This idea easily extends to weighted linear dummy regression so that the corresponding fitted values also span the canonical space. Two different choices of prior probabilities are applied with a real dataset to illustrate the effect for the obtained decision spaces. Copyright © 2007 John Wiley & Sons, Ltd.
Grey component analysis
Authors: Westerhuis Johan A. , Derks Eduard P. P. A. , Hoefsloot Huub C. J. , Smilde Age K.
Published: August 2007

The interpretation of principal component analysis (PCA) models of complex biological or chemical data can be cumbersome because in PCA the decomposition is performed without any knowledge of the system at hand. Prior information of the system is not used to improve the interpretation. In this paper we introduce Grey Component Analysis (GCA) as a new explorative data analysis method that uses the available prior information. GCA uses a soft penalty approach to gently push the decomposition into the direction of the prior information. The grey components are therefore partly data driven and partly driven by the prior information. GCA works in a confirmatory mode to analyze the validity of the prior information and in an exploratory mode in which new phenomena can be studied in detail. To show the wide applicability of GCA, applications within spectroscopy and gene expression are presented. Many diagnostic properties of GCA are introduced and examples of erroneous parts within the prior information are indicated. Copyright © 2007 John Wiley & Sons, Ltd.