A role for pectin in the control of cell expansion

Uptake of nutrients and water depends on the growth of roots through elongation of individual cells near the. root tip. Many of the numerous components of Type I primary cell walls, those of dicotyledons and monocotyledons other than grasses (Poaceae), have been determined, and many hypotheses have been proposed for the control of cell expansion. This important aspect of plant growth still needs elucidation, however. A model is proposed in which pectin, which occurs as a calcium (Ca) pectate gel between the load-bearing cellulose microfibrils and xyloglucan (XG) chains, controls the rate at which cells expand. It is considered that the increasing tension generated by the expanding cell is transmitted to interlocked XG chains and cellulose microfibrils. The resulting deformation of the embedded Ca pectate gel elicits the excretion of protons from the cytoplasm, possibly via compounds such as cell wall-associated kinases, that weakens the Ca pectate gel, permitting slippage of XG molecules through the action of expansin. Further slippage is prevented by deformation of the pectic gel, proton diffusion, and the transfer of residual tension to adjacent XG chains. Evidence for this model is based on the effects of pH, Ca, and aluminum (Al) on root elongation and on the reactions of these cations with Ca pectate. This model allows for genetic selection of plants and adaptation of individual plants to root environmental conditions.

Alterations of neocortical pyramidal cell phenotype in the Ts65Dn mouse model of Down syndrome: Effects of environmental enrichment

Mental retardation in individuals with Down syndrome (DS) is thought to result from anomalous development and function of the brain; however, the underlying neuropathological processes have yet to be determined. Early implementation of special care programs result in limited, and temporary, cognitive improvements in DS individuals. In the present study, we investigated the possible neural correlates of these limited improvements. More specifically, we studied cortical pyramidal cells in the frontal cortex of Ts65Dn mice, a partial trisomy of murine chromosome 16 (MMU16) model characterized by cognitive deficits, hyperactivity, behavioral disruption and reduced attention levels similar to those observed in DS, and their control littermates. Animals were raised either in a standard or in an enriched environment. Environmental enrichment had a marked effect on pyramidal cell structure in control animals. Pyramidal cells in environmentally enriched control animals were significantly more branched and more spinous than non-enriched controls. However, environmental enrichment had little effect on pyramidal cell structure in Ts65Dn mice. As each dendritic spine receives at least one excitatory input, differences in the number of spines found in the dendritic arbors of pyramidal cells in the two groups reflect differences in the number of excitatory inputs they receive and, consequently, complexity in cortical circuitry. The present results suggest that behavioral deficits demonstrated in the Ts65Dn model could be attributed to abnormal circuit development.

Cortex, cognition and the cell: New insights into the pyramidal neuron and prefrontal function

Arguably the most complex conical functions are seated in human cognition, the how and why of which have been debated for centuries by theologians, philosophers and scientists alike. In his best-selling book, An Astonishing Hypothesis: A Scientific Search for the Soul, Francis Crick refined the view that these qualities are determined solely by cortical cells and circuitry. Put simply, cognition is nothing more, or less, than a biological function. Accepting this to be the case, it should be possible to identify the mechanisms that subserve cognitive processing. Since the pioneering studies of Lorent de No and Hebb, and the more recent studies of Fuster, Miller and Goldman-Rakic, to mention but a few, much attention has been focused on the role of persistent neural activity in cognitive processes. Application of modern technologies and modelling techniques has led to new hypotheses about the mechanisms of persistent activity. Here I focus on how regional variations in the pyramidal cell phenotype may determine the complexity of cortical circuitry and, in turn, influence neural activity. Data obtained from thousands of individually injected pyramidal cells in sensory, motor, association and executive cortex reveal marked differences in the numbers of putative excitatory inputs received by these cells. Pyramidal cells in prefrontal cortex have, on average, up to 23 times more dendritic spines than those in the primary visual area. I propose that without these specializations in the structure of pyramidal cells, and the circuits they form, human cognitive processing would not have evolved to its present state. I also present data from both New World and Old World monkeys that show varying degrees of complexity in the pyramidal cell phenotype in their prefrontal cortices, suggesting that cortical circuitry and, thus, cognitive styles are evolving independently in different species.

Pyramidal cell heterogeneity in the visual cortex of the nocturnal new world owl monkey (aotus trivirgatus)

Recent studies have revealed marked variation in pyramidal cell structure in the visual cortex of macaque and marmoset monkeys. In particular, there is a systematic increase in the size of, and number of spines in, the arbours of pyramidal cells with progression through occipitotemporal (OT) visual areas. In the present study we extend the basis for comparison by investigating pyramidal cell structure in visual areas of the nocturnal owl monkey. As in the diurnal macaque and marmoset monkeys, pyramidal cells became progressively larger and more spinous with anterior progression through OT visual areas. These data suggest that: 1. the trend for more complex pyramidal cells with anterior progression through OT visual areas is a fundamental organizational principle in primate cortex; 2. areal specialization of the pyramidal cell phenotype provides an anatomical substrate for the reconstruction of the visual scene in OT areas; 3. evolutionary specialization of different aspects of visual processing may determine the extent of interareal variation in the pyramidal cell phenotype in different species; and 4. pyramidal cell structure is not necessarily related to brain size. Crown Copyright (C) 2003 Published by Elsevier Science Ltd on behalf of IBRO. All rights reserved.

The pyramidal neuron in occipital, temporal and prefrontal cortex of the owl monkey (Aotus trivirgatus): regional specialization in cell structure

Recent studies have revealed marked regional variation in pyramidal cell morphology in primate cortex. In particular, pyramidal cells in human and macaque prefrontal cortex (PFC) are considerably more spinous than those in other cortical regions. PFC pyramidal cells in the New World marmoset monkey, however, are less spinous than those in man and macaques. Taken together, these data suggest that the pyramidal cell has become more branched and more spinous during the evolution of PFC in only some primate lineages. This specialization may be of fundamental importance in determining the cognitive styles of the different species. However, these data are preliminary, with only one New World and two Old World species having been studied. Moreover, the marmoset data were obtained from different cases. In the present study we investigated PFC pyramidal cells in another New World monkey, the owl monkey, to extend the basis for comparison. As in the New World marmoset monkey, prefrontal pyramidal cells in owl monkeys have relatively few spines. These species differences appear to reflect variation in the extent to which PFC circuitry has become specialized during evolution. Highly complex pyramidal cells in PFC appear not to have been a feature of a common prosimian ancestor, but have evolved with the dramatic expansion of PFC in some anthropoid lineages.

Enhanced effector and memory CTL responses generated by incorporation of receptor activator of NF-kappa B(RANK)/RANK ligand costimulatory molecules into dendritic cell immunogens expressing a human tumor-specific antigen

The outcome of dendritic cell (DC) presentation of Ag to T cells via the TCR/MHC synapse is determined by second signaling through CD80/86 and, importantly, by ligation of costimulatory ligands and receptors located at the DC and T cell surfaces. Downstream signaling triggered by costimulatory molecule ligation results in reciprocal DC and T cell activation and survival, which predisposes to enhanced T cell-mediated immune responses. In this study, we used adenoviral vectors to express a model tumor Ag (the E7 oncoprotein of human papillomavirus 16) with or without coexpression of receptor activator of NF-kappaB (RANK)/RANK ligand (RANKL) or CD40/CD40L costimulatory molecules, and used these transgenic DCs to immunize mice for the generation of E7-directed CD8(+) T cell responses. We show that coexpression of RANK/RANKL, but not CD40/CD40L, in E7-expressing DCs augmented E7-specific IFN-gamma-secreting effector and memory T cells and E7-specific CTLs. These responses were also augmented by coexpression of T cell costimulatory molecules (RANKL and CD40L) or DC costimulatory molecules (RANK and CD40) in the E7-expressing DC immunogens. Augmentation of CTL responses correlated with up-regulation of CD80 and CD86 expression in DCs transduced with costimulatory molecules, suggesting a mechanism for enhanced T cell activation/survival. These results have generic implications for improved tumor Ag-expressing DC vaccines, and specific implications for a DC-based vaccine approach for human papillomavirus 16-associated cervical carcinoma.

Effect of time of harvest of budded virus on the selection of baculovirus FP mutants in cell culture

Rapid formation and selection of FP (few polyhedra) mutants occurs during serial passaging of Helicoverpa armigera nucleopolyhedrovirus (HaSNPV) in insect cell culture. The production of HaSNPV for use as biopesticides requires the passaging of the virus over a number of passages to produce enough virus inoculum for large-scale fermentation. During serial passaging in cell culture, FP mutants were rapidly selected, resulting in declined productivity and reduced potency of virus. Budded virus (BV) is usually harvested between 72 and 96 h postinfection (hpi) in order to obtain a high titer virus stock. In this study, the effect of tine of harvest (TOH) for BV on the selection rate of HaSNPV FP mutants during serial passaging was investigated. BV were harvested at different times postinfection, and each series was serially passaged for six passages. The productivity and percentage of FP mutants at each passage were determined. It was found that the selection of FP mutants can he reduced by employing an earlier TOH for BV. Serial passaging with BV harvested at 48 hpi showed a slower accumulation of FP mutants compared to that of BV harvested after 48 hpi. Higher cell specific yields were also maintained when BV were harvested at 48 hpi. When BV that were formed between 48 and 96 hpi were harvested and serially passaged, FP mutants quickly dominated the virus population. This suggests that the V formed and released between 48 and 96 hpi are most likely from FP mutant infected cells.

Almoxarifado virtual: uma proposta de sustentabilidade por contrata????o de gerenciamento de meios

A iniciativa opera a partir da presta????o de um servi??o continuado de gerenciamento de meios. Em s??ntese, o ??rg??o parou de adquirir materiais de escrit??rio e de combate a inc??ndio e passou a operar com um almoxarifado terceirizado que fornece insumos de expediente, processamento de dados e combate a inc??ndios de seu pr??prio almoxarifado, num sistema similar a um stop shop, al??m de controlar os estoques de pronto uso de cada unidade e fazer o seu ressuprimento. Cada unidade da autarquia possui uma cota aut??noma de pedidos, num baixo valor em periodicidade mensal. Com tal iniciativa, as unidades se mant??m supridas o ano todo, sem desperd??cios e sem estoques, fazendo os seus pedidos no almoxarifado virtual e customizando suas cestas de necessidades de produtos para a produ????o processual e o atendimento sazonal das emerg??ncias ambientais

Projeto visita virtual e videoconfer??ncia judicial

Este projeto nasceu de uma parceria entre o Departamento Penitenci??rio Nacional e a Defensoria P??blica da Uni??o (DPU). Apresenta duas importantes vertentes no ??mbito da execu????o penal. A primeira relaciona-se ao direito de manuten????o dos v??nculos afetivos dos presidi??rios, possibilitando o contato deles com seus familiares e amigos; e a segunda refere-se ?? realiza????o de audi??ncias judiciais por videoconfer??ncia. Desde a implanta????o do Projeto Visita Virtual e Videoconfer??ncia Judicial, em maio de 2010, 509 presos participaram da visita virtual e puderam conversar e visualizar seus familiares e amigos por meio desse recurso, conferindo, assim, um resultado extremamente satisfat??rio, visto que h?? pelo menos um ano n??o recebiam visitas. De mar??o de 2011 at?? julho deste ano, foram realizadas 160 videoconfer??ncias

Escrit??rio virtual

Este projeto refere-se ?? implementa????o de um modelo de gest??o que reduz os custos com as ??reas-meio, e volta o seu potencial para o provimento de solu????es das necessidades do cliente. ?? uma nova forma de conceber o tempo, o espa??o e os relacionamentos, mediante a cria????o de um escrit??rio virtual que visa aproximar os t??cnicos aos seus clientes. O funcion??rio carrega consigo o notebook e o aparelho celular podendo trabalhar em qualquer lugar e a qualquer hora, com o objetivo de atender as demandas dos clientes com prontid??o e agilidade no momento da solicita????o. Os resultados deste modelo podem ser percebidos tanto na satisfa????o dos clientes como dos funcion??rios envolvidos

Los modelos CAMEL y Promethee como instrumentos de análisis de la banca virtual en España

Consideramos de interés realizar un análisis financiero de la banca virtual en España para ser capaces de posicionar aquellas entidades bancarias que vieron en el canal de Internet una vía de expansión hacia nuevos clientes o como consolidación de los existentes, ya que todos los bancos creados en España de carácter virtual son filiales de grandes grupos bancarios. Utilizamos como modelos de análisis la aplicación de los métodos multicriterio CAMEL y Promethee. Como conclusiones del trabajo se observa que, independientemente del método utilizado, la entidad que mejor se posiciona para el periodo de análisis estudiado (2004-2010) es Bancopopular-e. No obstante, son entidades que todavía alcanzan valores muy bajas de rentabilidad y liquidez y donde datos como la eficiencia o la calidad de activos son muy mejorables.

Virtual simulation of the postsurgical cosmetic outcome in patientswith pectus excavatum

Pectus excavatum is the most common congenital deformity of the anterior chest wall, in which several ribs and the sternum grow abnormally. Nowadays, the surgical correction is carried out in children and adults through Nuss technic. This technic has been shown to be safe with major drivers as cosmesis and the prevention of psychological problems and social stress. Nowadays, no application is known to predict the cosmetic outcome of the pectus excavatum surgical correction. Such tool could be used to help the surgeon and the patient in the moment of deciding the need for surgery correction. This work is a first step to predict postsurgical outcome in pectus excavatum surgery correction. Facing this goal, it was firstly determined a point cloud of the skin surface along the thoracic wall using Computed Tomography (before surgical correction) and the Polhemus FastSCAN (after the surgical correction). Then, a surface mesh was reconstructed from the two point clouds using a Radial Basis Function algorithm for further affine registration between the meshes. After registration, one studied the surgical correction influence area (SCIA) of the thoracic wall. This SCIA was used to train, test and validate artificial neural networks in order to predict the surgical outcome of pectus excavatum correction and to determine the degree of convergence of SCIA in different patients. Often, ANN did not converge to a satisfactory solution (each patient had its own deformity characteristics), thus invalidating the creation of a mathematical model capable of estimating, with satisfactory results, the postsurgical outcome

A contribution to a virtual enterprise taxonomy

This paper presents a taxonomy able to contribute to building a framework within the domain of Virtual Enterprises (VE). A VE taxonomy currently does not exist, and this lack is felt in the ambiguous way that some concepts are addressed, leading to a fragment understanding that hinders the development of the science of VE integration and management. The structure of the taxonomy developed is based on the view of the system as a 5-tuple consisting of Input, Control, Output, Mechanism, and Process, which is the underlying system-view in the well-know IDEF0 diagramming technique. In particular, this taxonomy addresses the VE extended lifecycle that implies the use of a meta-organization called Market of Resources, as an original contribution to the VE theory and practice. The taxonomy presented is constructed in a way to be easily complemented with other VE partial taxonomies that may be found in literature.

A importância da personagem virtual no contexto da animação 3D em tempo real

O desenvolvimento de personagens digitais tridimensionais1 na área da animação, a constante procura por soluções tecnológicas convincentes, aliado a uma estética própria, tem contribuído para o sucesso e afirmação da animação tridimensional, na indústria do entretenimento. Contudo, toda a obra que procura ou explora a vertente digital/3D, torna-se ‘vitima’ das limitações do render2 aplicado a uma sequência de imagens, devido ao aumento dos custos financeiros e humanos, assim como da influência e dificuldade implicadas no cumprimento dos objectivos e prazos. O tempo real tem assumido, cada vez mais, um papel predominante na indústria da animação interactiva. Com a evolução da tecnologia surgiu a necessidade de procurar a metodologia apropriada que sirva de alavanca para o desenvolvimento de animações 3D em tempo real, através de softwares open-source ou de baixo orçamento, para a redução de custos, que possibilite simultaneamente descartar qualquer dependência do render na animação 3D. O desenvolvimento de personagens em tempo real, possibilita o surgimento de uma nova abordagem: a interactividade na arte de animar. Esta possibilita a introdução de um vasto leque de novas aplicações e consequentemente, contribui para o aumento do interesse e curiosidade por parte do espectador. No entanto, a inserção, implementação e (ab)uso da tecnologia na área da animação, levanta questões atuais sobre qual o papel do animador. Esta dissertação procura analisar estes aspectos, dando apoio ao projecto de animação 3D em tempo real, denominado ‘PALCO’.

A taxonomy for virtual enterprises

The purpose of this paper is to present a taxonomy able to contribute to building a framework within the domain of Virtual Enterprises (VE), to facilitate the sharing of knowledge and contributions to knowledge, as well as for trust building among VE stakeholders. A VE taxonomy currently does not exist, and this lack is felt in the ambiguous way that some concepts are addressed, leading to a fragment understanding that hinders the development of the science of VE integration and management. The structure of the taxonomy developed is based on the view of the system as a 5-tuple consisting of Input, Control, Output, Mechanism, and Process, which is the underlying system-view in the well-know IDEF0 diagramming technique. In particular, this taxonomy addresses the VE extended lifecycle that implies the use of a meta-organization called Market of Resources, as an original contribution to the VE theory and practice. The taxonomy presented does not repeat what the literature already includes, or the commonplaces, and it is constructed in a way to be easily complemented with other VE partial taxonomies that may be found in literature. Some suggestions for extensions to other interrelated domains (as evolution leaves taxonomies in an open or incompleteness state) are given in the text.