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Distinct Processes (distinct + process)
Selected AbstractsDissimilar aggregation processes govern precipitation and gelation of human IgM cryoglobulinsJOURNAL OF MOLECULAR RECOGNITION, Issue 2 2007Vicky Vallas Abstract Cryoglobulinemia is associated with a range of diseases including rheumatoid arthritis, B-cell malignancies, and chronic viral infections. This "cold-sensitivity" condition is caused by cryoglobulins that precipitate, gel, or occasionally crystallize in the cold. Clinical manifestations vary widely in severity, depending on many factors, including the type of cryoglobulin (monoclonal or mixed immunoglobulins) and the physical nature of the aggregates (precipitate, gel, or crystal). Dynamic light scattering (DLS) was used to examine the cold-induced precipitation or gelation of two human cryoglobulins, namely, Pot IgM and Yvo IgM. The DLS assay was highly reproducible, sensitive, and had low intra-assay variations for both IgM cryoglobulins. Distinct processes were revealed to contribute to precipitation and gelation of cryoglobulins. The precipitation of Pot IgM displayed a rapid transition from solution to solid phases, with a wide distribution of aggregate sizes. In contrast, the gelation of Yvo IgM progressed gradually across a broad temperature range to produce a relatively uniform gel matrix. Initial cryoglobulin concentrations determined the kinetics and critical temperatures for both precipitation and gelation. Moreover, the Yvo IgM was observed to have a distinct relationship between concentrations and mean hydrodynamic diameters or particle sizes. Concentration-dependent effects on particle sizes were present, but not as pronounced for the Pot IgM. Precipitation and gelation of cryoglobulins were also found to be differentially responsive to changes in the aqueous environment. Our results indicate that DLS is a rapid, reliable, and sensitive method for characterizing the nature of disease-associated cryoglobulins. Copyright © 2007 John Wiley & Sons, Ltd. [source] Involuntary interpretation of social cues is compromised in autism spectrum disordersAUTISM RESEARCH, Issue 4 2009Tjeerd Jellema Abstract A new social distance judgment task was used to measure quantitatively the extent to which social cues are immediately and involuntary interpreted by typically developing (TD) individuals and by individuals with autism spectrum disorders (ASD). The task thus tapped into the ability to involuntary "pick up" the meaning of social cues. The cues tested were social attention and implied biological motion. Task performance of the ASD and TD groups was similarly affected by a perceptual low-level illusion induced by physical characteristics of the stimuli. In contrast, a high-level illusion induced by the implications of the social cues affected only the TD individuals; the ASD individuals remained unaffected (causing them to perform superior to TD controls). The results indicate that despite intact perceptual processing, the immediate involuntary interpretation of social cues can be compromised. We propose that this type of social cue understanding is a distinct process that should be differentiated from reflective social cue understanding and is specifically compromised in ASD. We discuss evidence for an underpinning neural substrate. [source] Spontaneous mutation in mice provides new insight into the genetic mechanisms that pattern the seminal vesicles and prostate glandDEVELOPMENTAL DYNAMICS, Issue 4 2003Paul C. Marker Abstract The seminal vesicles and prostate gland are anatomically adjacent male sex-accessory glands. Although they arise from different embryonic precursor structures and express distinct sets of secretory proteins, these organs share common features in their developmental biology. A key shared developmental feature is the elaboration of complex secretory epithelia with tremendous surface area from simple precursor structures with juxtaposed epithelial and mesenchymal cells. In this study, new insight into the nature of the biological processes that underlie glandular morphogenesis is achieved by analyzing the phenotypes present in mice that harbor a spontaneous mutation, seminal vesicle shape (svs), previously identified for causing altered seminal vesicle morphology in adults. An examination of seminal vesicle development in svs mice provides the first evidence that the concurrent processes of epithelial branching and epithelial infolding are distinct processes under separate genetic control. It also provides the first direct evidence that the thickness and topology of the smooth muscle layer in the seminal vesicles are determined by interaction with the glandular epithelium during the branching process. In addition, the seminal vesicle phenotype in svs mice is shown to phenocopy the morphologic form present in certain other mammals such as the guinea pig, raising the possibility that the svs mutation is the sort of variant that arises during evolution. By also including an investigation of the prostate gland, this study also identifies previously unrecognized phenotypes in svs prostates, including increased gland size and dramatically reduced levels of branching morphogenesis. Finally, this study advances the goal of identifying the svs gene by mapping the svs mutation relative to known molecular markers and testing Fgfr2 as a candidate gene. The finding that the svs mutation maps to a genomic region syntenic to a region frequently deleted in human prostate tumors, together with the prostatic phenotype present in svs mice, further raises the interesting possibility that the svs mutation will identify a candidate prostate tumor suppressor gene. Developmental Dynamics 226:643,653, 2003. © 2003 Wiley-Liss, Inc. [source] AN EXACT FORM OF THE BREEDER'S EQUATION FOR THE EVOLUTION OF A QUANTITATIVE TRAIT UNDER NATURAL SELECTIONEVOLUTION, Issue 11 2005John S. Heywood Abstract Starting with the Price equation, I show that the total evolutionary change in mean phenotype that occurs in the presence of fitness variation can be partitioned exactly into five components representing logically distinct processes. One component is the linear response to selection, as represented by the breeder's equation of quantitative genetics, but with heritability defined as the linear regression coefficient of mean offspring phenotype on parent phenotype. The other components are identified as constitutive transmission bias, two types of induced transmission bias, and a spurious response to selection caused by a covariance between parental fitness and offspring phenotype that cannot be predicted from parental phenotypes. The partitioning can be accomplished in two ways, one with heritability measured before (in the absence of) selection, and the other with heritability measured after (in the presence of) selection. Measuring heritability after selection, though unconventional, yields a representation for the linear response to selection that is most consistent with Darwinian evolution by natural selection because the response to selection is determined by the reproductive features of the selected group, not of the parent population as a whole. The analysis of an explicitly Mendelian model shows that the relative contributions of the five terms to the total evolutionary change depends on the level of organization (gene, individual, or mated pair) at which the parent population is divided into phenotypes, with each frame of reference providing unique insight. It is shown that all five components of phenotypic evolution will generally have nonzero values as a result of various combinations of the normal features of Mendelian populations, including biparental sex, allelic dominance, inbreeding, epistasis, linkage disequilibrium, and environmental covariances between traits. Additive genetic variance can be a poor predictor of the adaptive response to selection in these models. The narrow-sense heritability s,2A/s,2P should be viewed as an approximation to the offspring-parent linear regression rather than the other way around. [source] Glucose-induced and nitrogen-starvation-induced peroxisome degradation are distinct processes in Hansenula polymorpha that involve both common and unique genesFEMS YEAST RESEARCH, Issue 1 2001Anna Rita Bellu Abstract In the methylotrophic yeast Hansenula polymorpha non-selective autophagy, induced by nitrogen starvation, results in the turnover of cytoplasmic components, including peroxisomes. We show that the uptake of these components occurs by invagination of the vacuolar membrane without their prior sequestration and thus differs from the mechanism described for bakers yeast. A selective mode of autophagy in H. polymorpha, namely glucose-induced peroxisome degradation, involves sequestration of individual peroxisomes tagged for degradation by membrane layers that subsequently fuse with the vacuole where the organelle is digested. H. polymorpha pdd mutants are blocked in selective peroxisome degradation. We observed that pdd1-201 is also impaired in non-selective autophagy, whereas this process still normally functions in pdd2-4. These findings suggest that mechanistically distinct processes as selective and non-selective autophagy involve common but also unique genes. [source] The dynamic network subserving the three phases of cognitive procedural learningHUMAN BRAIN MAPPING, Issue 12 2007Valérie Hubert Abstract Cognitive procedural learning is characterized by three phases (cognitive, associative, and autonomous), each involving distinct processes. We performed a behavioral study and a positron emission tomography (PET) activation study using the Tower of Toronto task. The aim of the behavioral study was to determine cognitive predictors for the length of each of the three learning phases, in order to preselect subjects for the PET study. The objective of the second study was to describe the cerebral substrates subtending these three phases. Contrasted with a reference (motor) task, the cognitive phase activated the prefrontal cortex, cerebellum, and parietal regions, all of which became less active as learning progressed. The associative phase was characterized by the activation of the occipital regions, right thalamus, and caudate nucleus. During the autonomous phase, new regions were involved, including the left thalamus and an anterior part of the cerebellum. These results, by employing a direct comparison between phases, provide the first evidence of the involvement and the time course of activation of different regions in each learning phase, in accordance with current models of cognitive procedural learning. The involvement of a frontoparietal network suggests the use of strategies in problem solving during the cognitive phase. The involvement of the occipital regions during the associative and autonomous phase suggests the intervention of mental imagery. Lastly, the activation of the cerebellum during the autonomous phase is consistent with the fact that performance in this phase is determined by psychomotor abilities. Hum Brain Mapp, 2007. © 2007 Wiley-Liss, Inc. [source] Developing and maintaining protective CD8+ memory T cellsIMMUNOLOGICAL REVIEWS, Issue 1 2006Matthew A. Williams Summary:, A critical aim of vaccine-related research is to identify the mechanisms by which memory T cells are formed and maintained over long periods of time. In recent years, we have designed experiments aimed at addressing two key questions: (i) what are the factors that maintain functionally responsive CD8+ memory cells over long periods of time, and (ii) what are the signals during the early stages of infection that drive the differentiation of long-lived CD8+ memory T cells? We have identified a role for CD4+ T cells in the generation of CD8+ T-cell-mediated protection from secondary challenge. While CD4+ T cells appear to play a role in the programme of CD8 memory, we find that they are also required for the long-term maintenance of CD8+ memory T-cell numbers and function. This property is independent of CD40,CD40L interactions, and we propose a role for CD4+ T cells in maintaining the ability of CD8+ memory T cells to respond to interleukin-7 (IL-7) and IL-15. By manipulating both the time course of infection and the timing of antigen presentation to newly recruited CD8+ T cells, we also demonstrate that the programming of effector and memory potential are at least partially distinct processes. [source] A taxonomy of political processes in systems developmentINFORMATION SYSTEMS JOURNAL, Issue 5 2010Rajiv Sabherwal Abstract Significant resources invested in information system development (ISD) are wasted due to political manoeuvres. Prior research on ISD politics has contributed mainly through theoretical development and case studies. This has enhanced understanding of relevant concepts, political tactics and conditions facilitating politics. However, there is limited understanding of the different processes through which politics unfold. This paper uses 89 ISD projects to develop a taxonomy of political processes in ISD. The taxonomy includes three distinct processes: Tug of War, wherein multiple parties strive to gain project control; Obstacle Race, which involves efforts to resist and pursue the project; and Empire Building, wherein the project is used as an instrument to enhance political or resource bases. The taxonomy is explained using the non-proponents' view of the project and the balance of power between system's proponents and non-proponents. We also discuss the emergent taxonomy's implications for how politics can be managed and studied. [source] The integrin family of cell adhesion molecules has multiple functions within the CNSJOURNAL OF NEUROSCIENCE RESEARCH, Issue 3 2002Richard Milner Abstract Integrins comprise a large family of cell adhesion molecules that mediate interactions between the extracellular environment and the cytoplasm. During the last decade, analysis of the expression and function of these molecules has revealed that integrins regulate many aspects of cell behavior including cell death, proliferation, migration, and differentiation. Within the central nervous system (CNS), most of the early studies focused on the role of integrins in mediating adhesive and migratory events in two distinct processes: neural development and CNS inflammation. Interestingly, recent analysis of transgenic mice has provided some surprising results regarding the role of integrins in neural development. Furthermore, a large body of evidence now supports the idea that in addition to these well-described functions, integrins play multiple roles in the CNS, both during development and in the adult in areas as diverse as synaptogenesis, activation of microglia, and stabilization of the endothelium and blood-brain barrier. Many excellent reviews have addressed the contribution of integrins in mediating leukocyte extravasation during CNS inflammation. This review will focus on recently emerging evidence of novel and diverse roles of integrins and their ligands in the CNS during development and in the adult, in health and disease. © 2002 Wiley-Liss, Inc. [source] RT-GROG: parallelized self-calibrating GROG for real-time MRIMAGNETIC RESONANCE IN MEDICINE, Issue 1 2010Haris Saybasili Abstract A real-time implementation of self-calibrating Generalized Autocalibrating Partially Parallel Acquisitions (GRAPPA) operator gridding for radial acquisitions is presented. Self-calibrating GRAPPA operator gridding is a parallel-imaging-based, parameter-free gridding algorithm, where coil sensitivity profiles are used to calculate gridding weights. Self-calibrating GRAPPA operator gridding's weight-set calculation and image reconstruction steps are decoupled into two distinct processes, implemented in C++ and parallelized. This decoupling allows the weights to be updated adaptively in the background while image reconstruction threads use the most recent gridding weights to grid and reconstruct images. All possible combinations of two-dimensional gridding weights GG are evaluated for m,n = {,0.5, ,0.4, ,, 0, 0.1, ,, 0.5} and stored in a look-up table. Consequently, the per-sample two-dimensional weights calculation during gridding is eliminated from the reconstruction process and replaced by a simple look-up table access. In practice, up to 34× faster reconstruction than conventional (parallelized) self-calibrating GRAPPA operator gridding is achieved. On a 32-coil dataset of size 128 × 64, reconstruction performance is 14.5 frames per second (fps), while the data acquisition is 6.6 fps. Magn Reson Med 64:306,312, 2010. © 2010 Wiley-Liss, Inc. [source] A double three-step theory of brain metastasis in mice: the role of the pia mater and matrix metalloproteinasesNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 3 2007N. Saito The brain is frequently affected by the spread of lung cancer, and haematogenous metastasis is a common route to brain metastasis. We therefore developed an isogenic brain metastasis model of lung cancer to use the Lewis lung carcinoma cell line and analysed dynamics of neoplastic cells after extravasation. Histological analysis revealed two characteristic patterns: metastatic foci exhibiting an angiocentric pattern were designated ,perivascular proliferations'; neoplastic cells infiltrating the brain parenchyma were designated ,invasive proliferations'. Electron microscopic observation of perivascular proliferations showed that neoplastic cells were confined to the perivascular space. In invasive proliferations, however, fragments of collagen fibre were observed in the gaps between neoplastic cells, indicating that the neoplastic cells had disintegrated the pia-glial membrane. We analysed the expressions of matrix metalloproteinase-2 (MMP-2) and MMP-9 by using both immunohistochemical analysis and real-time polymerase chain reaction analysis. MMP-2 expression was significantly higher in invasive proliferations. MMP-9 expression was significantly higher in day 7, but there was no significant difference in day 11. The pia-glial membrane and perivascular space are the barriers that neoplastic cells must overcome to infiltrate the brain. In conclusion, our findings suggest that brain metastasis requires two distinct processes. [source] Effects of temperature, sorbitol, alanine and diapause hormone on the embryonic development in Bombyx mori: in vitro tests of old hypothesesPHYSIOLOGICAL ENTOMOLOGY, Issue 4 2005Ken-Ichi Iwata Abstract., An in vitro culture method is described in which embryonic development in Bombyx mori is traced at various temperatures and treatments. The results show that the induction, intensification and termination of diapause are distinct processes. Prediapause embryos, explanted from 40-h-old diapause-destined eggs and cultured in Grace's medium, continue to develop to the appendage-formation stage without arrest, which indicates that the isolated embryos have not entered diapause, whereas the development of embryos from diapausing eggs (15 days after being laid) is significantly slower. The rate of development of embryos dissected from diapause eggs increases during chilling (5 °C) and incubation (at 25 °C) gradually during chilling and dramatically at 25 °C. The in vitro experiments also reveal that sorbitol directly inhibits the development of embryos explanted from diapausing eggs but has no affect on the development of embryos from prediapause eggs. Neither alanine nor diapause hormone prevent isolated embryos from developing. [source] Cyclopentenone Eicosanoids as Mediators of Neurodegeneration: A Pathogenic Mechanism of Oxidative Stress-Mediated and Cyclooxygenase-Mediated NeurotoxicityBRAIN PATHOLOGY, Issue 2 2005Erik S. Musiek The activation of cyclooxygenase enzymes in the brain has been implicated in the pathogenesis of numerous neurodegenerative conditions. Similarly, oxidative stress is believed to be a major contributor to many forms of neurodegeneration. These 2 distinct processes are united by a common characteristic: the generation of electrophilic cyclopentenone eicosanoids. These cyclopentenone compounds are defined structurally by the presence of an unsaturated carbonyl moiety in their prostane ring, and readily form Michael adducts with cellular thiols, including those found in glutathione and proteins. The cyclopentenone prostaglandins (PGs) PGA2, PGJ2, and 15-deoxy-,12,14 PGJ2, enzymatic products of cyclooxygenase-mediated arachidonic acid metabolism, exert a complex array of potent neurodegenerative, neuroprotective, and anti-inflammatory effects. Cyclopentenone isoprostanes (A2/J2 -IsoPs), products of non-enzymatic, free radical-mediated arachidonate oxidation, are also highly bioactive, and can exert direct neurodegenerative effects. In addition, cyclopentenone products of docosahexaenoic acid oxidation (cyclopentenone neuroprostanes) are also formed abundantly in the brain. For the first time, the formation and biological actions of these various classes of reactive cyclopentenone eicosanoids are reviewed, with emphasis on their potential roles in neurodegeneration. The accumulating evidence suggests that the formation of cyclopentenone eicosanoids in the brain may represent a novel pathogenic mechanism, which contributes to many neurodegenerative conditions. [source] L'ajustement mutuel dans le fonctionnement organique du système multiorganisationnel d'aide et de services aux sans-abri de MontréalCANADIAN PUBLIC ADMINISTRATION/ADMINISTRATION PUBLIQUE DU CANADA, Issue 1 2009Alain Dupuis Sommaire : Notre étude de l'organisation du secteur de l'aide et des services aux sans-abri à Montréal Centre met en lumière un système multiorganisationnel de services de santé et de services sociaux qui n'est pas intégré hiérarchiquement dans son ensemble et qui n'est pas soumis à une « entente de gestion et d'imputabilité» globale propre à une gestion fondée sur la normalisation des résultats. L'étude présente un système d'ensemble de type « organique » plutôt que bureaucratique, largement fondé sur des ajustements mutuels entre les nombreux acteurs publics et « communautaires » de ce secteur. La coordination des services se réalise alors essentiellement dans les interactions entre les intervenants alors qu'ils accomplissent leur travail, et ce avec le soutien des gestionnaires. À l'aide de nombreux extraits d'entrevues, nous étudions le fonctionnement de ce système « organique » sous la forme de trois catégories de processus d'ajustement mutuel qui se superposent et se complètent pour assurer la valeur des services : disjoint unilatéral, conjoint bilatéral et conjoint multilatéral. Selon les sciences de l'organisation, un tel système est potentiellement mieux adaptéà composer avec la complexité des connaissances et des valeurs caractéristiques des services humains, qu'un à système formellement intégré et contrôlé par des règles, des indicateurs et des cibles quantifiables. Abstract: This study of the organization of the sector dedicated to providing aid and services to the homeless in Central Montreal reveals a multiorganizational health and social services system that is neither hierarchically integrated as a whole nor subject to a comprehensive "management and accountability agreement" specific to standardized results-based management. The study details a comprehensive system that is "organic," rather than bureaucratic, and broadly organized based on mutual adjustments among the numerous public and "community" practitioners in this sector. The coordination of services is therefore essentially achieved through the interaction of the workers as they perform their jobs, with the support of management. This study draws on a number of extracts from interviews to examine how this "organic" system operates, in the form of three distinct processes of mutual adjustment that are superimposed and complementary to ensure the value of the services: "unilateral disjoined,""bilateral joined" and "multilateral joined." According to organizational science, this type of system is potentially more likely to address the complexities inherent in the knowledge and values that are characteristic of human services than a formally integrated system that is controlled by rules, indicators and quantifiable targets. [source] Photoinduced Energy- and Electron-Transfer Processes in Dinuclear RuII,OsII, RuII,OsIII, and RuIII,OsII Trisbipyridine Complexes Containing a Shape-Persistent Macrocyclic SpacerCHEMPHYSCHEM, Issue 1 2006Margherita Venturi Prof. Abstract The PF6,salt of the dinuclear [(bpy)2Ru(1)Os(bpy)2]4+complex, where 1 is a phenylacetylene macrocycle which incorporates two 2,2,-bipyridine (bpy) chelating units in opposite sites of its shape-persistent structure, was prepared. In acetonitrile solution, the Ru- and Os-based units display their characteristic absorption spectra and electrochemical properties as in the parent homodinuclear compounds. The luminescence spectrum, however, shows that the emission band of the RuIIunit is almost completely quenched with concomitant sensitization of the emission of the OsIIunit. Electronic energy transfer from the RuIIto the OsIIunit takes place by two distinct processes (ken=2.0×108and 2.2×107s,1at 298 K). Oxidation of the OsIIunit of [(bpy)2Ru(1)Os (bpy)2]4+by CeIVor nitric acid leads quantitatively to the [(bpy)2RuII(1)OsIII(bpy)2]5+complex which exhibits a bpy-to-OsIIIcharge-transfer band at 720 nm (,max=250,M,1cm,1). Light excitation of the RuIIunit of [(bpy)2RuII(1)OsIII(bpy)2]5+is followed by electron transfer from the RuIIto the OsIIIunit (kel,f=1.6×108and 2.7×107s,1), resulting in the transient formation of the [(bpy)2RuIII(1)OsII(bpy)2]5+complex. The latter species relaxes to the [(bpy)2RuII(1)OsIII(bpy)2]5+one by back electron transfer (kel,b=9.1×107and 1.2×107s,1). The biexponential decays of the [(bpy)2*RuII(1)OsII(bpy)2]4+, [(bpy)2*RuII(1)OsIII(bpy)2]5+, and [(bpy)2RuIII(1)OsII(bpy)2]5+species are related to the presence of two conformers, as expected because of the steric hindrance between hydrogen atoms of the pyridine and phenyl rings. Comparison of the results obtained with those previously reported for other Ru,Os polypyridine complexes shows that the macrocyclic ligand 1 is a relatively poor conducting bridge. [source] | ||||||||||||||||