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Various Forms (various + form)
Selected AbstractsChemInform Abstract: A Density Functional Study of the Various Forms of UN4O12 Containing Uranyl NitrateCHEMINFORM, Issue 2 2008Joel J. Berard Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Improved four-node Hellinger,Reissner elements based on skew coordinatesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 6 2008K. Wisniewski Abstract Mixed four-node elements based on the Hellinger,Reissner (HR) functional are developed for stress representations in various coordinates, including the skew, natural and Cartesian ones. The two-field HR functional is used in the classical form and in the incremental form suitable for non-linear materials. We argue that the skew coordinates, not the natural ones, should be associated with the natural basis at the element's center. If 5- and 7-parameter stress representations are assumed in these coordinates, then, for a linear elastic case, the homogenous equilibrium equations and the stress form of compatibility equation are satisfied point-wise. Two mixed four-node elements are developed and tested: 1.An assumed stress element (HR5-S) is developed from the non-enhanced HR functional, for a 5-parameter representation of stresses, formally identical as the one used, for example, in Pian and Sumihara [Int. J. Numer. Meth. Engng 1984; 20:1685,1695], but in terms of skew coordinates. This element is very simple and uses a smaller number of parameters, but is equally accurate as the elements by Yuan et al. [Int. J. Numer. Meth. Engng 1993; 36:1747,1763] and by Piltner and Taylor [Int. J. Numer. Meth. Engng 1995; 38:1783,1808]. 2.An assumed stress/enhanced strain element (HR9) is developed from the enhanced HR functional, for a 7-parameter representation of stress and a 2-parameter enhanced assumed displacement gradient or enhanced assumed strain enhancement. Various forms of 7-parameter representations appearing in the literature are reviewed, and we prove that they are linked by a linear onto transformation. The choice of coordinates for the stress and the enhancement turns out to be the crucial factor, and four combinations of coordinates for which the element performs the best are identified. Both elements are based on the Green strain, and several numerical tests show their good accuracy, in particular, their robustness to shape distortions for coarse meshes. Two update schemes for the multipliers of modes and the incremental constitutive procedure accounting for the plane stress condition for non-linear materials are tested for large deformation problems. Copyright © 2008 John Wiley & Sons, Ltd. [source] Organized International Asylum-Seeker Networks: Formation and Utilization by Chinese Students1INTERNATIONAL MIGRATION REVIEW, Issue 2 2006Jia Gao This article examines the formation and role of international networks formed by Chinese students living in the West in the late 1980s and early 1990s as part of their efforts to obtain the right to remain in Western countries in the immediate aftermath of the Tiananmen Square violence of June 4, 1989. Various forms of migrant social networks have been a research focus in international refugee and migration studies, but international networks formed by asylum seekers themselves, and their role in asylum-seeking processes, have been largely ignored. This article is based on a multi-method comparative study of Chinese students living in Australia and the United States at the time. Their experience provides data for examining and conceptualizing the role of organized international asylum-seeker networks in the asylum-seeking process. The analysis focuses on Chinese student lobbying in 1989, led by an independent Chinese student union, which helped "the Pelosi Bill" to be passed by the U.S. Congress. The main strategies adopted by Chinese students in the United States and Australia, as well as their internationally coordinated actions, are compared. Also examined is the role of two politicized international Chinese student organizations, the Chinese Alliance for Democracy and the Federation for Democratic China, in assisting students with obtaining residence. [source] Mechanical Properties of Magnetic Attachments for Removable Prostheses on Teeth and ImplantsJOURNAL OF PROSTHODONTICS, Issue 8 2008Arne F. Boeckler DMD Abstract Purpose: Magnetic attachments on teeth and implants may be used to improve stability, support, and retention of removable prostheses. Various forms of magnetic attachments are available, divided according to the design, the mechanical properties of the attachments, and the clinical indication. Recently developed attachment systems are small and promise improved retentive capacity, while existing magnetic attachments continue to be technologically modified and improved. This investigation reviewed and compared maximum retentive forces and characteristic curves for magnetic attachments indicated for use as root anchors and on implants. Materials and Methods: Twenty-four samarium-cobalt (SmCo) and neodym-iron-boron (NeFeB) magnetic attachments (12 tooth- and 12 implant-borne) were evaluated. Specimens were delivered by the manufacturers or fabricated according to their instructions. Five magnet pairs of each product and each combination were tested 10 times in a calibrated universal testing machine using a nonmagnetic test device (s = 40 mm, v = 20 mm/min). Results were recorded electronically and compared to manufacturers' details. Results: Maximum retentive forces for root keepers ranged from 1.4 to 6.6 N. Maximum retentive forces for magnetic attachments on implants ranged from 0.7 to 5.8 N. After a distance of 0.1 mm, a complete reversed distribution of the different systems became obvious. The retentive force provided by the manufacturer was achieved in one implant abutment, with retentive force (as compared to those provided by the manufacturers) for root keepers ranging between 42.5% and 92.9% and for implant abutments between 43.0% and 99.4%. Conclusion: There were differences between magnetic attachments for both the initial retentive capabilities and the characteristic curves. Recently introduced products provided relatively high initial retentive forces despite their small size. The measured retentive forces and the manufacturer's information differed in the majority of magnetic systems evaluated. [source] Why Have Child Maltreatment and Child Victimization Declined?JOURNAL OF SOCIAL ISSUES, Issue 4 2006David Finkelhor Various forms of child maltreatment and child victimization declined as much as 40,70% from 1993 until 2004, including sexual abuse, physical abuse, sexual assault, homicide, aggravated assault, robbery, and larceny. Other child welfare indicators also improved during the same period, including teen pregnancy, teen suicide, and children living in poverty. This article reviews a wide variety of possible explanations for these changes: demography, fertility and abortion legalization, economic prosperity, increased incarceration of offenders, increased agents of social intervention, changing social norms and practices, the dissipation of the social changes from the 1960s, and psychiatric pharmacology. Multiple factors probably contributed. In particular, economic prosperity, increasing agents of social intervention, and psychiatric pharmacology have advantages over some of the other explanations in accounting for the breadth and timing of the improvements. [source] Right movies on the right seat: Laterality and seat choiceAPPLIED COGNITIVE PSYCHOLOGY, Issue 1 2010Matia Okubo Various forms of lateral preferences are found in human behaviour. Conducting two experiments, we investigated the lateral preference for seat choice exhibited by people at the movie theatre. The right-handed participants (N,=,269) tended to choose seats to the right of the screen when they were positively motivated to see the movie. This rightward bias disappeared when they were negatively motivated. In addition, the non-right-handed participants (N,=,105) did not show any substantial bias in their seat choice. It is well known that visual and emotional information is better processed in the right hemisphere. Considering the visual and emotional nature of movie experiences, the rightward seating bias among right-handers appears to be determined by their motivation to effectively utilize their right-hemisphere functions. Copyright © 2009 John Wiley & Sons, Ltd. [source] John Browne (1642,1702): Anatomist and plagiaristCLINICAL ANATOMY, Issue 1 2010Marios Loukas Abstract In contrast to many other physicians of his age, John Browne (1642,1702), an English anatomist and surgeon, managed to strike a balance in his career that spanned relative obscurity, prestige, and notoriety. Among his more prestigious credits, Browne was Surgeon in Ordinary to King Charles II and William III. He also had numerous publications to his name, some of which are credited as great innovations. His career, however, was tempered by his most important book, which has been critiqued by his contemporaries as well as modern historians as plagiarism. Although Browne undeniably copied the works of others and published them under his name, he was not alone in this practice. Various forms of intellectual thievery were common in Browne's day, and there were many perpetrators. The life of this overlooked figure in the history of anatomy and the stigma attached to him will be examined. Clin. Anat. 23:1,7, 2010. © 2009 Wiley-Liss, Inc. [source] Antimicrobial peptides and proteins, exercise and innate mucosal immunityFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2006Nicholas P. West Abstract This review examines the question of whether exercise can be used as an experimental model to further our understanding of innate antimicrobial peptides and proteins (AMPs) and their role in susceptibility to infection at mucosal surfaces. There is strong evidence to suggest that AMPs, in combination with cellular and physical factors, play an important role in preventing infection. Although AMPs act directly on microorganisms, there is increasing recognition that they also exert their protective effect via immunomodulatory mechanisms, especially in noninflammatory conditions. Further studies that manipulate physiologically relevant concentrations of AMPs are required to shed light on the role they play in reducing susceptibility to infection. Evidence shows that in various form prolonged and/or exhaustive exercise is a potent modulator of the immune system, which can either sharpen or blunt the immune response to pathogens. The intensity and duration of exercise can be readily controlled in experimental settings to manipulate the degree of physical stress. This would allow for an investigation into a potential dose,response effect between exercise and AMPs. In addition, the use of controlled exercise could provide an experimental model by which to examine whether changes in the concentration of AMPs alters susceptibility to illness. [source] Improving realism of a surgery simulator: linear anisotropic elasticity, complex interactions and force extrapolationCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 3 2002Guillaume Picinbono Abstract In this article, we describe the latest developments of the minimally invasive hepatic surgery simulator prototype developed at INRIA. The goal of this simulator is to provide a realistic training test bed to perform laparoscopic procedures. Therefore, its main functionality is to simulate the action of virtual laparoscopic surgical instruments for deforming and cutting tridimensional anatomical models. Throughout this paper, we present the general features of this simulator including the implementation of several biomechanical models and the integration of two force-feedback devices in the simulation platform. More precisely, we describe three new important developments that improve the overall realism of our simulator. First, we have developed biomechanical models, based on linear elasticity and finite element theory, that include the notion of anisotropic deformation. Indeed, we have generalized the linear elastic behaviour of anatomical models to ,transversally isotropic' materials, i.e. materials having a different behaviour in a given direction. We have also added to the volumetric model an external elastic membrane representing the ,liver capsule', a rather stiff skin surrounding the liver, which creates a kind of ,surface anisotropy'. Second, we have developed new contact models between surgical instruments and soft tissue models. For instance, after detecting a contact with an instrument, we define specific boundary constraints on deformable models to represent various forms of interactions with a surgical tool, such as sliding, gripping, cutting or burning. In addition, we compute the reaction forces that should be felt by the user manipulating the force-feedback devices. The last improvement is related to the problem of haptic rendering. Currently, we are able to achieve a simulation frequency of 25,Hz (visual real time) with anatomical models of complex geometry and behaviour. But to achieve a good haptic feedback requires a frequency update of applied forces typically above 300,Hz (haptic real time). Thus, we propose a force extrapolation algorithm in order to reach haptic real time. Copyright © 2002 John Wiley & Sons, Ltd. [source] How Do We Know?: Students Examine Issues of Credibility With a Complicated Multimodal Web-Based TextCURRICULUM INQUIRY, Issue 2 2009Mark Baildon ABSTRACT As reading continues to become governed by a spatial "logic of the image" rather than strictly a temporal or linear logic of written language (Kress, 2003), and readers increasingly engage with a range of Internet-based texts, a host of challenges ensue for educators and students alike. One of the most vexing of these challenges deals with discernments of credibility. Determining the credibility of multimodal texts, especially on/within the Internet with its "vast network of relations of credibility" (Burbules & Callister, 2000), is particularly challenging because these texts mix images, music, graphic arts, video, and print to make sophisticated claims supported by various forms or types of evidence. This article examines how a group of ninth-grade students grappled with issues of credibility after viewing the controversial Internet video, Loose Change, a well-documented and comprehensive multimedia account that argues the "real story" of September 11 was covered up by the U.S. government. Findings from the study highlight the range of knowledge and literacy practices students mobilized to "read" the video and the challenges they experienced reading and evaluating the video as a multimodal text. Implications of this work point to the need to consider epistemological issues and further develop tools that can support teachers and students in critically assessing multimodal texts. [source] Women's Careers Beyond the Classroom: Changing Roles in a Changing WorldCURRICULUM INQUIRY, Issue 3 2001Nina Bascia Drawing from our own and others' research over the past decade and a half, we present four "readings," each illuminating a different dimension of women educators' career development, particularly their movement into work beyond the classroom. The majority of the participants in our studies are women who work for change in their classrooms, schools, and district organizations, using the opportunities, vehicles, and channels available,or apparent,to them. They do this work in professional and personal contexts that are continually changing, sometimes as a result of their own choices and actions and sometimes not. While there is a growing body of literature on women's movement into, and their lives in, educational administration, we are concerned here with the broader and more varied manifestations of leadership beyond the classroom. In the four readings, we bring together several strands in the literature on women educators' lives and careers. We first lay out the taken-for-granted oppositional contrasts in the educational discourses that have tended to obscure more complex understandings of work lives and careers. Next, we explore how the particular kinds of work available to women actually encourage some to move beyond narrow conceptions of the distinctions between classroom and nonclassroom work. Third, we discuss the developmental nature of individual career paths. Fourth, we note the spatial and temporal nature of leadership work by showing how it is influenced and changed by greater economic, social, and political forces. We believe that these multiple interpretations are required to understand the range and combination of influences that propel and compel women educators to take up various forms of leadership work beyond the classroom. [source] Myosin light chain kinase colocalizes with nonmuscle myosin IIB in myofibril precursors and sarcomeric Z-lines of cardiomyocytesCYTOSKELETON, Issue 7 2006T. V. Dudnakova Abstract Myosin light chain kinase (MLCK) is a key regulator of various forms of cell motility involving actin and myosin II. MLCK is widely present in vertebrate tissues including the myocardium. However, the role of MLCK in cardiomyocyte function is not known. Previous attempts to gain insight into possible roles and identify potential molecular partners were disappointing and equivocal due to cross reactivity of early antibodies with striated muscle MLCK, which has a different genetic locus and a divergent amino acid sequence from the abovementioned enzyme. Using an immunofluorescence approach and a panel of antibodies directed against MLCK, cytoskeletal, and sarcomeric proteins, we localized MLCK to myofibril precursors and Z-lines of sarcomeres in embryonic and adult cardiomyocytes. The same structures contained nonmuscle myosin IIB implicating this protein as a possible target of MLCK. Our results suggest a role for MLCK in cardiomyocyte differentiation and contraction through regulation of nonmuscle myosin IIB. Cell Motil. Cytoskeleton 2006. © 2006 Wiley-Liss, Inc. [source] Childhood acne: evaluation and managementDERMATOLOGIC THERAPY, Issue 4 2006Julie L. Cantatore-Francis ABSTRACT:, Acne is a disease that can be seen in the first year of life, early childhood, prepubertal age, and puberty. The purpose of this article is to review the clinical presentation and pathogenesis of the various forms of prepubertal acne and to propose guidelines regarding its evaluation and treatment. The early clinical recognition of the disease and prompt initiation of therapy in these age groups will help prevent the sequelae of emotional distress and severe scarring in both the child and parents. [source] Privatisation Results: Private Sector Participation in Water Services After 15 YearsDEVELOPMENT POLICY REVIEW, Issue 6 2006Naren Prasad Privatisation of public infrastructure has been the mantra of many development agencies since the late 1980s. Water supply is no exception, and various forms of private sector participation (PSP) have been tried in the water and sanitation sector. This article examines the results of these experiments. It suggests that PSP has had mixed results and that in several important respects the private sector seems to be no more efficient in delivering services than the public sector. Despite growing evidence of failures and increasing public pressure against it, privatisation in water and sanitation is still alive, however. Increasingly, it is being repackaged in new forms such as that of public-private partnership. [source] Shb null allele is inherited with a transmission ratio distortion and causes reduced viability in uteroDEVELOPMENTAL DYNAMICS, Issue 9 2007Vitezslav Kriz Abstract SHB is an Src homology 2 domain-containing adapter protein that has been found to be involved in numerous cellular responses. We have generated an Shb knockout mouse. No Shb,/, pups or embryos were obtained on the C57Bl6 background, indicating an early defect as a consequence of Shb - gene inactivation on this genetic background. Breeding heterozygotes for Shb gene inactivation (Shb+/,) on a mixed genetic background (FVB/C57Bl6/129Sv) reveals a distorted transmission ratio of the null allele with reduced numbers of Shb+/+ and Shb,/, animals, but increased number of Shb+/, animals. The Shb, allele is associated with various forms of malformations, explaining the relative reduction in the number of Shb,/, offspring. Shb,/, animals that were born were viable, fertile, and showed no obvious defects. However, Shb+/, female mice ovulated preferentially Shb, oocytes explaining the reduced frequency of Shb+/+ mice. Our study suggests a role of SHB during reproduction and development. Developmental Dynamics 236:2485,2492, 2007. © 2007 Wiley-Liss, Inc. [source] Are antidepressants safe in the treatment of bipolar depression?ACTA PSYCHIATRICA SCANDINAVICA, Issue 5 2008A critical evaluation of their potential risk to induce switch into mania or cycle acceleration Objective:, To address whether switch of depression into hypomania or mania or cycle acceleration in patients with bipolar disorder is caused by antidepressants or whether this phenomenon is attributable to the natural history of bipolar disorder itself. Method:, A critical review of the literature, pointing at sources of bias that have been previously overlooked. For examining the causation in question, the Bradford,Hill criteria were applied, i.e. specificity of the potential causative agent, strength of effect, consistency in findings, dose,response relation, temporal relation with exposure to agent preceding effect and biological plausibility. Results:, There is a scarcity of randomized studies addressing the question, and the available studies all suffer from various forms of bias. However, there is some evidence suggesting that antidepressants given in addition to a mood stabilizer are not associated with an increased rate of switch when compared with the rate associated with the mood stabilizer alone. Conclusion:, When combined with a mood stabilizer, antidepressants given for acute bipolar depression seemingly do not induce a switch into hypomania or mania. Whether antidepressants may accelerate episode frequency and/or may cause other forms of destabilization in patients with bipolar disorder remain to be properly studied. [source] Intranuclear cytoplasmic inclusions in fine-needle aspiration smears of papillary thyroid carcinoma: A study of its morphological forms, association with nuclear grooves, and mode of formationDIAGNOSTIC CYTOPATHOLOGY, Issue 5 2005D.SC., Dilip K. Das M.B.B.S., Ph.D. Abstract Intranuclear cytoplasmic inclusion (INCI) and nuclear grooves in fine-needle aspiration (FNA) smears of papillary thyroid carcinoma (PTC) represent cytoplasmic invaginations into the nucleus. Although formation of INCIs is linked to nuclear grooves, they seldom exist together. This study was undertaken to find out the various morphological forms of INCIs, their relation to nuclear grooves, and mode of formation. FNA smears of 54 PTC cases were studied for various forms of INCI, nuclear chromatin pattern, nuclear grooves, and nuclear notches. A differential count of INCIs was made in 19 cases having ,10 INCIs per 200 neoplastic cells. INCIs were present in 48 (88.9%) of 54 PTC cases. Round INCIs were present in 46 (85.2%) cases, followed by oval (48.1%), tear drop/flask-shaped (18.5%), irregular (14.8%), planoconvex/semicircular (13%), rectangular (9.3%), spindle-shaped (3.7%), and bilobed (3.7%). A differential count of INCIs also showed that the round form was the commonest (76.3%). The oval and other forms constituted 19.5 and 4.2%, respectively. INCIs and nuclear grooves were present together in a cell in 15 (27.8%) cases. The formation of INCIs as a cytoplasmic invagination into the nucleus was shown cytomorphologically in rare cells. For the first time in this study, the various morphological forms of INCIs, and the extent of their coexistence with nuclear grooves, (have been highlighted) and showed their mode of formation shown at a light microscopic level. Diagn. Cytopathol. 2005;32:264,268. © 2005 Wiley-Liss, Inc. [source] Clinical supervision in the alcohol and other drugs field: an imperative or an option?DRUG AND ALCOHOL REVIEW, Issue 3 2007ANN M. ROCHE Abstract There is a growing interest in Clinical Supervision (CS) as a central workforce development (WFD) strategy. This paper provides a definition of and rationale for CS, characterises its various forms, identifies selection and training issues, and advises on policy and implementation issues central to redressing shortcomings in supervision practice within the alcohol and other drugs (AOD) field. Relevant selective literature is reviewed. Key conceptual issues were identified, and strategies developed to address implementation barriers and facilitate relevant policy. There is a common conceptual confusion between administrative supervision and CS. Clarification of the role, function and implementation of CS is required. Priority issues for the AOD field include: enhancing belief in CS; ensuring adequate resource allocation; developing evaluation protocols; and addressing specific arrangements under which supervision should occur. CS has been underutilised to date but holds considerable potential as a WFD strategy. It is fundamental to workers' professional development, can contribute to worker satisfaction and retention, and may improve client outcomes. Critical next steps are to establish the generalisability to the AOD field of the benefits observed from CS in other disciplines, and evaluate longer-term gains of CS programs. [source] The nature of calcareous deposits along pan margins in eastern central NamibiaEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2002Florias MeesArticle first published online: 13 JUN 200 Abstract In a region along the western margin of the Kalahari in eastern Namibia and western Botswana, many pan basins have mainly calcareous deposits along part of their margins. These are typically lined by low vertical scarps. In Namibia, these pans are mainly located in dry river beds. The petrographical study of these deposits demonstrates that they consist of lacustrine sediments that have to a varying extent been affected by early-diagenetic processes and by the formation of late-diagenetic features. The original composition of the deposits ranges from highly calcareous sediments, typically with ostracod, diatom and charophyte remains, to entirely non-calcareous diatomites. The deposits generally show an upward increase in total carbonate content, which is mainly a synsedimentary feature. The early-diagenetic processes that affected the deposits include the formation of orthic siliceous nodules. At a later stage, secondary calcite enrichment occurred, leaving only the silica-impregnated sections unaffected. This enrichment partly accounts for the upward increase in total carbonate content in some profiles and often resulted in the development of a highly calcareous surface horizon. Sepiolite and amorphous silica that are part of the groundmass of the deposits may also partly have formed at this stage. Late-diagenetic features include various forms of secondary calcite and silica. This study of pan basins in eastern central Namibia indicates that a lacustrine rather than purely pedogenic origin should also be considered for calcareous deposits that commonly occur along pan margins in other parts of southern Africa. Copyright © 2002 John Wiley & Sons, Ltd. [source] Consistent Tests for Stochastic DominanceECONOMETRICA, Issue 1 2003Garry F. Barrett Methods are proposed for testing stochastic dominance of any pre,specified order, with primary interest in the distributions of income. We consider consistent tests, that are similar to Kolmogorov,Smirnov tests, of the complete set of restrictions that relate to the various forms of stochastic dominance. For such tests, in the case of tests for stochastic dominance beyond first order, we propose and justify a variety of approaches to inference based on simulation and the bootstrap. We compare these approaches to one another and to alternative approaches based on multiple comparisons in the context of a Monte Carlo experiment and an empirical example. [source] Exporting the German Model: The Establishment of a New Automobile Industry Cluster in ShanghaiECONOMIC GEOGRAPHY, Issue 1 2005Heiner Depner Abstract: Recent work has provided evidence that the establishment of new industry clusters cannot be jump-started through policy initiatives alone. This evidence does not imply, however, that the genesis of a new cluster cannot be planned at all. Especially in the context of a developing economy, it seems useful to reinvestigate the relation among economic development, the strategies of multinational firms, and state intervention in this respect. Drawing from the case of the automobile industry and its supplier system in Shanghai in which German firms play an important role, we provide empirical evidence of the evolution of a new cluster that is supported by the state in various forms and characterized by a focal, hierarchically structured production system. We use a multidimensional approach to clusters, which leads to a more nuanced understanding of the evolution and growth of a cluster than that provided by earlier accounts. This approach allows us to distinguish the development of the Shanghai automobile industry cluster along its vertical, horizontal, external, institutional, and power dimensions. We provide evidence that another dimension,"culture",plays an important role, especially in its relation to issues of power and institutions. The role of this dimension is demonstrated in the case of German firms, which tap into the Chinese innovation system. This system is characterized by particular business relations, institutions, norms, and various social practices that are new to German firms. We demonstrate how this difference creates problems in establishing local production and supplier relations and how these problems can be overcome. [source] Failure of immunocompetitive capillary electrophoresis assay to detect disease-specific prion protein in buffy coat from humans and chimpanzees with Creutzfeldt-Jakob diseaseELECTROPHORESIS, Issue 5 2003Larisa Cervenakova Abstract The emergence of a new environmentally caused variant of Creutzfeldt-Jakob disease (vCJD), the result of food-born infection by the causative agent of bovine spongiform encephalopathy (BSE), has stimulated research on a practical diagnostic screening test. The immunocompetitive capillary electrophoresis (ICCE) assay has been reported to detect disease-specific, proteinase-resistant prion protein (PrPres) in the blood of scrapie-infected sheep. We have applied this method to blood from CJD-infected chimpanzees and humans. The threshold of detection achieved with our ICCE was 0.6 nM of synthetic peptide corresponding to the prion protein (PrP) C -terminus, and 2 nM of recombinant human PrP at the optimized conditions. However, the test was unable to distinguish between extracts of leucocytes from healthy and CJD-infected chimpanzees, and from healthy human donors and patients affected with various forms of CJD. Thus, the ICCE assay as presently performed is not suitable for use as a screening test in human transmissible spongiform encephalopathies (TSEs). [source] Biological significance of metals partitioned to subcellular fractions within earthworms (Aporrectodea caliginosa),ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2006Martina G. Vijver Abstract Metal ions in excess of metabolic requirements are potentially toxic and must be removed from the vicinity of important biological molecules to protect organisms from adverse effects. Correspondingly, metals are sequestrated in various forms, defining the accumulation pattern and the magnitude of steady-state levels reached. To investigate the subcellular fractions over which Ca, Mg, Fe, Cu, Zn, Cd, Pb, Ni, and As are distributed, earthworms (Aporrectodea caliginosa) collected from the field were analyzed by isolating metal-rich granules and tissue fragments from intracellular microsomal and cytosolic fractions (i.e., heat-stable proteins and heat-denatured proteins). The fractions showed metal-specific binding capacity. Cadmium was mainly retrieved from the protein fractions. Copper was equally distributed over the protein fraction and the fraction comprising tissue fragments, cell membranes, and intact cells. Zinc, Ca, Mg, and As were mainly found in this fraction as well. Lead, Fe, and Ni were mainly isolated from the granular fraction. To study accumulation kinetics in the different fractions, three experiments were conducted in which earthworms were exposed to metal-spiked soil and a soil contaminated by anthropogenic inputs and, indigenous earthworms were exposed to field soils. Although kinetics showed variation, linear uptake and steady-state types of accumulation patterns could be understood according to subcellular compartmentalization. For risk assessment purposes, subcellular distribution of metals might allow for a more precise estimate of effects than total body burden. Identification of subcellular partitioning appears useful in determining the biological significance of steady-state levels reached in animals. [source] Alcohol and mortality: methodological and analytical issues in aggregate analysesADDICTION, Issue 1s1 2001Thor Norström This supplement includes a collection of papers that aim at estimating the relationship between per capita alcohol consumption and various forms of mortality, including mortality from liver cirrhosis, accidents, suicide, homicide, ischaemic heart disease, and total mortality. The papers apply a uniform methodological protocol, and they are all based on time series data covering the post-war period in the present EU countries and Norway. In this paper we discuss various methodological and analytical issues that are common to these papers. We argue that analysis of time series data is the most feasible approach for assessing the aggregate health consequences of changes in population drinking. We further discuss how aggregate data may also be useful for judging the plausibility of individual-level relationships, particularly those prone to be confounded by selection effects. The aggregation of linear and curvilinear risk curves is treated as well as various methods for dealing with the time-lag problem. With regard to estimation techniques we find country specific analyses preferable to pooled cross-sectional/time series models since the latter incorporate the dubious element of geographical co-variation, and conceal potentially interesting variations in alcohol effects. The approach taken in the papers at hand is instead to pool the country specific results into three groups of countries that represent different drinking cultures; traditional wine countries of southern Europe, beer countries of central Europe and the British Isles and spirits countries of northern Europe. The findings of the papers reinforce the central tenet of the public health perspective that overall consumption is an important determinant of alcohol-related harm rates. However, there is a variation across country groups in alcohol effects, particularly those on violent deaths, that indicates the potential importance of drinking patterns. There is no support for the notion that increases in per capita consumption have any cardioprotective effects at the population level. [source] Immune modulation of HLA-G dimer in maternal-fetal interfaceEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 7 2007Kimiko Kuroki Abstract HLA-G is a non-classical human MHC class I molecule, which has several characteristics distinct from classical MHC, such as low polymorphism and restricted tissue distribution. HLA-G is expressed on placenta, thymus and some tumors. At the maternal-fetal interface, trophoblasts do not express major classical MHC class I molecules (MHCI), HLA-A and -B, to prevent normal T cell responses. Instead, HLA-G is expressed and can suppress a wide range of immune responses by binding to inhibitory immune cell surface receptors, such as leukocyte Ig-like receptor (LILR) B1 and LILRB2. HLA-G exists in various forms, including ,2m-associated or -free disulfide-linked dimers that can be expressed either at the cell surface or in soluble form. However, until recently the physiological role of these different molecular forms has been unclear. In this issue of the European Journal of Immunology, one article demonstrates that the disulfide-linked homodimer of ,2m-associated HLA-G is the major fraction expressed by trophoblast cells. The HLA-G dimer modulates the function of LILRB1-expressing antigen-presenting cells by principally binding to LILRB1. On the other hand, another recent report showed that ,2m-free disulfide-linked HLA-G dimers are produced by villous cytotrophoblast cells. Taken together, these results provide strong evidence in support of the hypothesis that HLA-G dimers play a role in immune suppression at the maternal-fetal interface. Further in-depth investigation will help to clarify the precise mechanism of HLA-G receptor recognition and signaling in vivo and the role of these interactions in successful reproduction. See accompanying article: http://dx.doi.org/10.1002/eji.200737089 [source] REVIEW: Stress, alcohol and drug interaction: an update of human researchADDICTION BIOLOGY, Issue 1 2009Magdalena Uhart ABSTRACT A challenging question that continues unanswered in the field of addiction is why some individuals are more vulnerable to substance use disorders than others. Numerous risk factors for alcohol and other drugs of abuse, including exposure to various forms of stress, have been identified in clinical studies. However, the neurobiological mechanisms that underlie this relationship remain unclear. Critical neurotransmitters, hormones and neurobiological sites have been recognized, which may provide the substrates that convey individual differences in vulnerability to addiction. With the advent of more sophisticated measures of brain function in humans, such as functional imaging technology, the mechanisms and neural pathways involved in the interactions between drugs of abuse, the mesocorticolimbic dopamine system and stress systems are beginning to be characterized. This review provides a neuroadaptive perspective regarding the role of the hormonal and brain stress systems in drug addiction with a focus on the changes that occur during the transition from occasional drug use to drug dependence. We also review factors that contribute to different levels of hormonal/brain stress activation, which has implications for understanding individual vulnerability to drug dependence. Ultimately, these efforts may improve our chances of designing treatment strategies that target addiction at the core of the disorder. [source] Disruption of the palatal rugae pattern in Tabby (eda) mutant miceEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2007Cyril Charles The eda mouse gene is linked with anomalies of ectodermal derivatives, such as hair, glands, and teeth. The palatal rugae (oral mucosa foldings on the hard palate) are also ectodermal derivatives. Therefore, we searched for and compared palatal rugae anomalies of Tabby mice bearing a mutation in the eda gene with their wild-type counterparts. We compared the number and shape of palatal rugae in 179 mutant and 102 wild-type mice from four different stocks of Tabby mice. Palatal rugae anomalies were documented at a low frequency in wild-type mice of different backgrounds, which may reflect a lack of robustness of palatal rugae development. However, the proportion of anomalies observed in the C57BL/6J background makes us recommend avoiding its use in further palate studies. We showed statistically that the phenotypic variability seen in wild-type animals is further increased in Tabby mutants. The anomalies mainly included various forms of reduction, with rugae IV,VI being more frequently affected. Those rugae were shortened, dotted or absent (mainly ruga V). By analogy to the role played by eda in other ectodermal derivatives, we propose that it might play a role in defining the pattern of the palatal rugae. [source] PURGING THE GENOME WITH SEXUAL SELECTION: REDUCING MUTATION LOAD THROUGH SELECTION ON MALESEVOLUTION, Issue 3 2009Michael C. Whitlock Healthy males are likely to have higher mating success than unhealthy males because of differential expression of condition-dependent traits such as mate searching intensity, fighting ability, display vigor, and some types of exaggerated morphological characters. We therefore expect that most new mutations that are deleterious for overall fitness may also be deleterious for male mating success. From this perspective, sexual selection is not limited to influencing those genes directly involved in exaggerated morphological traits but rather affects most, if not all, genes in the genome. If true, sexual selection can be an important force acting to reduce the frequency of deleterious mutations and, as a result, mutation load. We review the literature and find various forms of indirect evidence that sexual selection helps to eliminate deleterious mutations. However, direct evidence is scant, and there are almost no data available to address a key issue: is selection in males stronger than selection in females? In addition, the total effect of sexual selection on mutation load is complicated by possible increases in mutation rate that may be attributable to sexual selection. Finally, sexual selection affects population fitness not only through mutation load but also through sexual conflict, making it difficult to empirically measure how sexual selection affects load. Several lines of enquiry are suggested to better fill large gaps in our understanding of sexual selection and its effect on genetic load. [source] Intermittent hypoxia and respiratory plasticity in humans and other animals: does exposure to intermittent hypoxia promote or mitigate sleep apnoea?EXPERIMENTAL PHYSIOLOGY, Issue 3 2009Jason H. Mateika This review focuses on two phenomena that are initiated during and after exposure to intermittent hypoxia. The two phenomena are referred to as long-term facilitation and progressive augmentation of respiratory motor output. Both phenomena are forms of respiratory plasticity. Long-term facilitation is characterized by a sustained elevation in respiratory activity after exposure to intermittent hypoxia. Progressive augmentation is characterized by a gradual increase in respiratory activity from the initial to the final hypoxic exposure. There is much speculation that long-term facilitation may have a significant role in individuals with sleep apnoea because this disorder is characterized by periods of upper airway collapse accompanied by intermittent hypoxia, one stimulus known to induce long-term facilitation. It has been suggested that activation of long-term facilitation may serve to mitigate apnoea by facilitating ventilation and, more importantly, upper airway muscle activity. We examine the less discussed but equally plausible situation that exposure to intermittent hypoxia might ultimately lead to the promotion of apnoea. There are at least two scenarios in which apnoea might be promoted following exposure to intermittent hypoxia. In both scenarios, long-term facilitation of upper airway muscle activity is initiated but ultimately rendered ineffective because of other physiological conditions. Thus, one of the primary goals of this review is to discuss, with support from basic and clinical studies, whether various forms of respiratory motor neuronal plasticity have a beneficial and/or a detrimental impact on breathing stability in individuals with sleep apnoea. [source] A sympathetic view of the sympathetic nervous system and human blood pressure regulationEXPERIMENTAL PHYSIOLOGY, Issue 6 2008Michael J. Joyner New ideas about the relative importance of the autonomic nervous system (and especially its sympathetic arm) in long-term blood pressure regulation are emerging. It is well known that mean arterial blood pressure is normally regulated in a fairly narrow range at rest and that blood pressure is also able to rise and fall ,appropriately' to meet the demands of various forms of mental, emotional and physical stress. By contrast, blood pressure varies widely when the autonomic nervous system is absent or when key mechanisms that govern it are destroyed. However, 24 h mean arterial pressure is still surprisingly normal under these conditions. Thus, the dominant idea has been that the kidney is the main long-term regulator of blood pressure and the autonomic nervous system is important in short-term regulation. However, this ,renocentric' scheme can be challenged by observations in humans showing that there is a high degree of individual variability in elements of the autonomic nervous system. Along these lines, the level of sympathetic outflow, the adrenergic responsiveness of blood vessels and individual haemodynamic patterns appear to exist in a complex, but appropriate, balance in normotension. Furthermore, evidence from animals and humans has now clearly shown that the sympathetic nervous system can play an important role in longer term blood pressure regulation in both normotension and hypertension. Finally, humans with high baseline sympathetic traffic might be at increased risk for hypertension if the ,balance' among factors deteriorates or is lost. In this context, the goal of this review is to encourage a comprehensive rethinking of the complexities related to long-term blood pressure regulation in humans and promote finer appreciation of physiological relationships among the autonomic nervous system, vascular function, ageing, metabolism and blood pressure. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||