Ability of physicians to diagnose influenza and usefulness of a rapid influenza antigen test in febrile returning travelers: A randomized controlled trial.

BACKGROUND: Fever is a frequent cause of medical consultation among returning travelers. The objectives of this study were to assess whether physicians were able to identify patients with influenza and whether the use of an influenza rapid diagnostic test (iRDT) modified the clinical management of such patients. METHODS: Randomized controlled trial conducted at 2 different Swiss hospitals between December 2008 and November 2012. Inclusion criteria were 1) age ≥18 years, 2) documented fever of ≥38 °C or anamnestic fever + cough or sore throat within the last 4 days, 3) illness occurring within 14 days after returning from a trip abroad, 4) no definitive alternative diagnosis. Physicians were asked to estimate the likelihood of influenza on clinical grounds, and a single nasopharyngeal swab was taken. Thereafter patients were randomized into 2 groups: i) patients with iRDT (BD Directigen A + B) performed on the nasopharyngeal swab, ii) patients receiving usual care. A quantitative PCR to detect influenza was done on all nasopharyngeal swabs after the recruitment period. Clinical management was evaluated on the basis of cost of medical care, number of X-rays requested and prescription of anti-infective drugs. RESULTS: 100 eligible patients were referred to the investigators. 93 patients had a naso-pharyngeal swab for a PCR and 28 (30%) swabs were positive for influenza. The median probability of influenza estimated by the physician was 70% for the PCR positive cases and 30% for the PCR negative cases (p < 0.001). The sensitivity of the iRDT was only 20%, and specificity 100%. Mean medical cost for the patients managed with iRDT and without iRDT were USD 581 (95%CI 454-707) and USD 661 (95%CI 522-800) respectively. 14/60 (23%) of the patients managed with iRDT were prescribed antibiotics versus 13/33 (39%) in the control group (p = 0.15). No patient received antiviral treatment. CONCLUSION: Influenza was a frequent cause of fever among these febrile returning travelers. Based on their clinical assessment, physicians had a higher level of suspicion for influenza in PCR positive cases. The iRDT used in this study showed a disappointingly low sensitivity and can therefore not be recommended for the management of these patients. TRIAL REGISTRATION: ClinicalTrials.gov NCT00821626.

The Intestinal Microbiota Contributes to the Ability of Helminths to Modulate Allergic Inflammation.

Intestinal helminths are potent regulators of their host's immune system and can ameliorate inflammatory diseases such as allergic asthma. In the present study we have assessed whether this anti-inflammatory activity was purely intrinsic to helminths, or whether it also involved crosstalk with the local microbiota. We report that chronic infection with the murine helminth Heligmosomoides polygyrus bakeri (Hpb) altered the intestinal habitat, allowing increased short chain fatty acid (SCFA) production. Transfer of the Hpb-modified microbiota alone was sufficient to mediate protection against allergic asthma. The helminth-induced anti-inflammatory cytokine secretion and regulatory T cell suppressor activity that mediated the protection required the G protein-coupled receptor (GPR)-41. A similar alteration in the metabolic potential of intestinal bacterial communities was observed with diverse parasitic and host species, suggesting that this represents an evolutionary conserved mechanism of host-microbe-helminth interactions.

Cumulative cultural dynamics and the coevolution of cultural innovation and transmission: an ESS model for panmictic and structured populations.

When individuals in a population can acquire traits through learning, each individual may express a certain number of distinct cultural traits. These traits may have been either invented by the individual himself or acquired from others in the population. Here, we develop a game theoretic model for the accumulation of cultural traits through individual and social learning. We explore how the rates of innovation, decay, and transmission of cultural traits affect the evolutionary stable (ES) levels of individual and social learning and the number of cultural traits expressed by an individual when cultural dynamics are at a steady-state. We explore the evolution of these phenotypes in both panmictic and structured population settings. Our results suggest that in panmictic populations, the ES level of learning and number of traits tend to be independent of the social transmission rate of cultural traits and is mainly affected by the innovation and decay rates. By contrast, in structured populations, where interactions occur between relatives, the ES level of learning and the number of traits per individual can be increased (relative to the panmictic case) and may then markedly depend on the transmission rate of cultural traits. This suggests that kin selection may be one additional solution to Rogers's paradox of nonadaptive culture.

Factors influencing the adoption of an innovation: an examination of the uptake of the Canadian Heart Health Kit (HHK)

BACKGROUND: There is an emerging knowledge base on the effectiveness of strategies to close the knowledge-practice gap. However, less is known about how attributes of an innovation and other contextual and situational factors facilitate and impede an innovation's adoption. The Healthy Heart Kit (HHK) is a risk management and patient education resource for the prevention of cardiovascular disease (CVD) and promotion of cardiovascular health. Although previous studies have demonstrated the HHK's content validity and practical utility, no published study has examined physicians' uptake of the HHK and factors that shape its adoption. OBJECTIVES: Conceptually informed by Rogers' Diffusion of Innovation theory, and Theory of Planned Behaviour, this study had two objectives: (1) to determine if specific attributes of the HHK as well as contextual and situational factors are associated with physicians' intention and actual usage of the HHK kit; and (2), to determine if any contextual and situational factors are associated with individual or environmental barriers that prevent the uptake of the HHK among those physicians who do not plan to use the kit. METHODS: A sample of 153 physicians who responded to an invitation letter sent to all family physicians in the province of Alberta, Canada were recruited for the study. Participating physicians were sent a HHK, and two months later a study questionnaire assessed primary factors on the physicians' clinical practice, attributes of the HHK (relative advantage, compatibility, complexity, trialability, observability), confidence and control using the HHK, barriers to use, and individual attributes. All measures were used in path analysis, employing a causal model based on Rogers' Diffusion of Innovations Theory and Theory of Planned Behaviour. RESULTS: 115 physicians (follow up rate of 75%) completed the questionnaire. Use of the HHK was associated with intention to use the HHK, relative advantage, and years of experience. Relative advantage and the observability of the HHK benefits were also significantly associated with physicians' intention to use the HHK. Physicians working in solo medical practices reported experiencing more individual and environmental barriers to using the HHK. CONCLUSION: The results of this study suggest that future information innovations must demonstrate an advantage over current resources and the research evidence supporting the innovation must be clearly visible. Findings also suggest that the innovation adoption process has a social element, and collegial interactions and discussions may facilitate that process. These results could be valuable for knowledge translation researchers and health promotion developers in future innovation adoption planning.

Innovation through withdrawal. Contribution to a sociology of detachment

To develop the understanding of innovation processes conceptualized in terms of asso- ciation through the "sociology of translation" (cf. actor-network theory) studies, this article analyses innovation processes in terms of dissociation and detachment mechanisms, exami- ning innovation through "withdrawal;" that is, innovation based on reducing or withdrawing use of a practice-"subtracting," "detaching"-a given artefact. Specifically, it focuses on the shift to farming techniques that have eliminated ploughing, bringing to light four major mechanisms constitutive of dissociation: centrifugal association; making entities and asso- ciations visible; making other entities and associations invisible; bringing together or "asso- ciating" new entities. The study helps refine our understanding of the detachment processes at work in innovation, shedding light in this particular case on transfers between public research institutes, industrial companies, farmers and citizens seeking to develop new farm production models.

Tapping the innovation potential of corporate engagement with stakeholders

Summary This dissertation explores how stakeholder dialogue influences corporate processes, and speculates about the potential of this phenomenon - particularly with actors, like non-governmental organizations (NGOs) and other representatives of civil society, which have received growing attention against a backdrop of increasing globalisation and which have often been cast in an adversarial light by firms - as a source of teaming and a spark for innovation in the firm. The study is set within the context of the introduction of genetically-modified organisms (GMOs) in Europe. Its significance lies in the fact that scientific developments and new technologies are being generated at an unprecedented rate in an era where civil society is becoming more informed, more reflexive, and more active in facilitating or blocking such new developments, which could have the potential to trigger widespread changes in economies, attitudes, and lifestyles, and address global problems like poverty, hunger, climate change, and environmental degradation. In the 1990s, companies using biotechnology to develop and offer novel products began to experience increasing pressure from civil society to disclose information about the risks associated with the use of biotechnology and GMOs, in particular. Although no harmful effects for humans or the environment have been factually demonstrated even to date (2008), this technology remains highly-contested and its introduction in Europe catalysed major companies to invest significant financial and human resources in stakeholder dialogue. A relatively new phenomenon at the time, with little theoretical backing, dialogue was seen to reflect a move towards greater engagement with stakeholders, commonly defined as those "individuals or groups with which. business interacts who have a 'stake', or vested interest in the firm" (Carroll, 1993:22) with whom firms are seen to be inextricably embedded (Andriof & Waddock, 2002). Regarding the organisation of this dissertation, Chapter 1 (Introduction) describes the context of the study, elaborates its significance for academics and business practitioners as an empirical work embedded in a sector at the heart of the debate on corporate social responsibility (CSR). Chapter 2 (Literature Review) traces the roots and evolution of CSR, drawing on Stakeholder Theory, Institutional Theory, Resource Dependence Theory, and Organisational Learning to establish what has already been developed in the literature regarding the stakeholder concept, motivations for engagement with stakeholders, the corporate response to external constituencies, and outcomes for the firm in terms of organisational learning and change. I used this review of the literature to guide my inquiry and to develop the key constructs through which I viewed the empirical data that was gathered. In this respect, concepts related to how the firm views itself (as a victim, follower, leader), how stakeholders are viewed (as a source of pressure and/or threat; as an asset: current and future), corporate responses (in the form of buffering, bridging, boundary redefinition), and types of organisational teaming (single-loop, double-loop, triple-loop) and change (first order, second order, third order) were particularly important in building the key constructs of the conceptual model that emerged from the analysis of the data. Chapter 3 (Methodology) describes the methodology that was used to conduct the study, affirms the appropriateness of the case study method in addressing the research question, and describes the procedures for collecting and analysing the data. Data collection took place in two phases -extending from August 1999 to October 2000, and from May to December 2001, which functioned as `snapshots' in time of the three companies under study. The data was systematically analysed and coded using ATLAS/ti, a qualitative data analysis tool, which enabled me to sort, organise, and reduce the data into a manageable form. Chapter 4 (Data Analysis) contains the three cases that were developed (anonymised as Pioneer, Helvetica, and Viking). Each case is presented in its entirety (constituting a `within case' analysis), followed by a 'cross-case' analysis, backed up by extensive verbatim evidence. Chapter 5 presents the research findings, outlines the study's limitations, describes managerial implications, and offers suggestions for where more research could elaborate the conceptual model developed through this study, as well as suggestions for additional research in areas where managerial implications were outlined. References and Appendices are included at the end. This dissertation results in the construction and description of a conceptual model, grounded in the empirical data and tied to existing literature, which portrays a set of elements and relationships deemed important for understanding the impact of stakeholder engagement for firms in terms of organisational learning and change. This model suggests that corporate perceptions about the nature of stakeholder influence the perceived value of stakeholder contributions. When stakeholders are primarily viewed as a source of pressure or threat, firms tend to adopt a reactive/defensive posture in an effort to manage stakeholders and protect the firm from sources of outside pressure -behaviour consistent with Resource Dependence Theory, which suggests that firms try to get control over extemal threats by focussing on the relevant stakeholders on whom they depend for critical resources, and try to reverse the control potentially exerted by extemal constituencies by trying to influence and manipulate these valuable stakeholders. In situations where stakeholders are viewed as a current strategic asset, firms tend to adopt a proactive/offensive posture in an effort to tap stakeholder contributions and connect the organisation to its environment - behaviour consistent with Institutional Theory, which suggests that firms try to ensure the continuing license to operate by internalising external expectations. In instances where stakeholders are viewed as a source of future value, firms tend to adopt an interactive/innovative posture in an effort to reduce or widen the embedded system and bring stakeholders into systems of innovation and feedback -behaviour consistent with the literature on Organisational Learning, which suggests that firms can learn how to optimize their performance as they develop systems and structures that are more adaptable and responsive to change The conceptual model moreover suggests that the perceived value of stakeholder contribution drives corporate aims for engagement, which can be usefully categorised as dialogue intentions spanning a continuum running from low-level to high-level to very-high level. This study suggests that activities aimed at disarming critical stakeholders (`manipulation') providing guidance and correcting misinformation (`education'), being transparent about corporate activities and policies (`information'), alleviating stakeholder concerns (`placation'), and accessing stakeholder opinion ('consultation') represent low-level dialogue intentions and are experienced by stakeholders as asymmetrical, persuasive, compliance-gaining activities that are not in line with `true' dialogue. This study also finds evidence that activities aimed at redistributing power ('partnership'), involving stakeholders in internal corporate processes (`participation'), and demonstrating corporate responsibility (`stewardship') reflect high-level dialogue intentions. This study additionally finds evidence that building and sustaining high-quality, trusted relationships which can meaningfully influence organisational policies incline a firm towards the type of interactive, proactive processes that underpin the development of sustainable corporate strategies. Dialogue intentions are related to type of corporate response: low-level intentions can lead to buffering strategies; high-level intentions can underpin bridging strategies; very high-level intentions can incline a firm towards boundary redefinition. The nature of corporate response (which encapsulates a firm's posture towards stakeholders, demonstrated by the level of dialogue intention and the firm's strategy for dealing with stakeholders) favours the type of learning and change experienced by the organisation. This study indicates that buffering strategies, where the firm attempts to protect itself against external influences and cant' out its existing strategy, typically lead to single-loop learning, whereby the firm teams how to perform better within its existing paradigm and at most, improves the performance of the established system - an outcome associated with first-order change. Bridging responses, where the firm adapts organisational activities to meet external expectations, typically leads a firm to acquire new behavioural capacities characteristic of double-loop learning, whereby insights and understanding are uncovered that are fundamentally different from existing knowledge and where stakeholders are brought into problem-solving conversations that enable them to influence corporate decision-making to address shortcomings in the system - an outcome associated with second-order change. Boundary redefinition suggests that the firm engages in triple-loop learning, where the firm changes relations with stakeholders in profound ways, considers problems from a whole-system perspective, examining the deep structures that sustain the system, producing innovation to address chronic problems and develop new opportunities - an outcome associated with third-order change. This study supports earlier theoretical and empirical studies {e.g. Weick's (1979, 1985) work on self-enactment; Maitlis & Lawrence's (2007) and Maitlis' (2005) work and Weick et al's (2005) work on sensegiving and sensemaking in organisations; Brickson's (2005, 2007) and Scott & Lane's (2000) work on organisational identity orientation}, which indicate that corporate self-perception is a key underlying factor driving the dynamics of organisational teaming and change. Such theorizing has important implications for managerial practice; namely, that a company which perceives itself as a 'victim' may be highly inclined to view stakeholders as a source of negative influence, and would therefore be potentially unable to benefit from the positive influence of engagement. Such a selfperception can blind the firm from seeing stakeholders in a more positive, contributing light, which suggests that such firms may not be inclined to embrace external sources of innovation and teaming, as they are focussed on protecting the firm against disturbing environmental influences (through buffering), and remain more likely to perform better within an existing paradigm (single-loop teaming). By contrast, a company that perceives itself as a 'leader' may be highly inclined to view stakeholders as a source of positive influence. On the downside, such a firm might have difficulty distinguishing when stakeholder contributions are less pertinent as it is deliberately more open to elements in operating environment (including stakeholders) as potential sources of learning and change, as the firm is oriented towards creating space for fundamental change (through boundary redefinition), opening issues to entirely new ways of thinking and addressing issues from whole-system perspective. A significant implication of this study is that potentially only those companies who see themselves as a leader are ultimately able to tap the innovation potential of stakeholder dialogue.

The Discrimination of Colored Acrylic, Cotton, and Wool Textile Fibers Using Micro-Raman Spectroscopy. Part 1 : In Situ Detection and Characterization of Dyes

Raman spectroscopy has been applied to characterize fiber dyes and determine the discriminating ability of the method. Black, blue, and red acrylic, cotton, and wool samples were analyzed. Four excitation sources were used to obtain complementary responses in the case of fluorescent samples. Fibers that did not provide informative spectra using a given laser were usually detected using another wavelength. For any colored acrylic, the 633-nm laser did not provide Raman information. The 514-nm laser provided the highest discrimination for blue and black cotton, but half of the blue cottons produced noninformative spectra. The 830-nm laser exhibited the highest discrimination for red cotton. Both visible lasers provided the highest discrimination for black and blue wool, and NIR lasers produced remarkable separation for red and black wool. This study shows that the discriminating ability of Raman spectroscopy depends on the fiber type, color, and the laser wavelength.

Coevolution of restriction factors and retroviruses

Les virus exploitent la machinerie cellulaire de l'hôte pour se répliquer. Ils doivent s'adapter pour infecter la cellule hôte de manière optimale tout en échappant à la vigilance du système de défense de l'hôte. Ainsi l'hôte et les virus se livrent à de constantes batailles évolutives. Mon travail de thèse a porté sur l'étude des signatures évolutives de facteurs de l'hôte agissant comme des 'facteurs de restriction' en bloquant la réplication rétrovirale chez les primates. Plus spécifiquement, mon travail a visé à utiliser des données évolutives pour renseigner les analyses fonctionnelles et la biologie. Nous avons étudié le facteur anti-VIH-1 nommé TRIM5a (i) chez les prosimiens pour mieux comprendre son rôle dans le contrôle d'un lentivirus endogène, (ii) dans son activité contre d'autres anciennes infections représentées par des rétrovirus endogènes humains et (iii) en tant que protéine capable de générer des mutants de la capside. Premièrement nous nous sommes intéressés à TRIM5a chez deux espèces de lémuriens dont Microcebus murinus qui porte le lentivirus endogène PSIV dans son génome depuis plusieurs millions d'années,. Nous avons observé que TRIM5a chez M. murinus a un spectre d'activité antivirale réduit à l'opposé de TRIM5a chez le Lemur catta - non porteur du PSIV endogène - qui bloque une large variété de rétrovirus dont le PSIV. De ce fait TRIM5a aurait pu contribuer à protéger certaines espèces de lémuriens vis-à-vis d'anciennes infections par le PSIV. A l'inverse du PSIV, des virus dérivés des rétrovirus endogènes humains HERV-K and HERV-H se sont révélés largement résistants à l'inhibition par TRIM5a. Ces données illustrent une absence de protection par TRIM5a face à d'autres anciennes infections rétrovirales. Puis, pour évaluer l'impact de la protéine TRIM5a humaine sur le VIH-1, nous avons testé l'effet de mutations des résidues sous sélection positive dans la capside du VIH-1 sur l'inhibition par TRIM5a. Nos résultats montrent que TRIM5a ne jouerait pas un rôle significatif dans l'évolution de la capside du VIH-1. Enfin notre travail a porté sur le facteur anti-VIH-1 SAMHD1 récemment découvert, que nous avons séquencé chez 25 espèces de primates. L'analyse évolutive des sites sous sélection positive et des expériences fonctionnelles ont permis d'identifier le domaine de SAMHD1 interagissant avec la protéine lentivirale Vpx. De même que d'autres protéines virales contrecarrent les facteurs de restriction en les menant à la dégradation, nous avons observé que Vpx induit la dégradation de SAMHD1 de manière spécifique à l'espèce. Ces découvertes contribuent à comprendre comment les facteurs de restriction et les virus co-évoluent pour se neutraliser l'un l'autre. - Viruses hijack the host cellular machinery to replicate. They adapt to infect optimally host cells while escaping host defense systems. Viruses and the host coevolve in an evolutionary struggle. My thesis work has been devoted to study the evolutionary signatures of host factors acting as restriction factors that block retroviral replication in primates. Specifically, my work aimed at using evolutionary data to inform functional analyses and biology. We studied the anti-HIV-1 factor TRIM5a (i) in prosimians to better understand its possible role in the control of an endogenous lentivirus, (ii) in its activity against other ancient infections - as represented by HERVs, and (iii) as a protein capable of generating escape mutants in the viral capsid. First, my work focused on two lemur species, one of which was the gray mouse lemur that carries the endogenous lentivirus PSIV integrated in its genome for several million years. TRIM5a from gray mouse lemur exhibited a limited antiviral spectrum as opposed to TRIM5a from ring-tailed lemur - not a host of PSIV - that is able to block diverse retroviruses notably PSIV. These results support the possible contribution of TRIM5a in protecting lemur species from ancient infection by PSIV. In contrast, chimeric viruses derived from two human endogenous retroviruses were broadly resistant to TRIM5a-mediated restriction, suggesting TRIM5a lack of activity against other types of ancient infections. To evaluate the recent impact of human TRIM5a on HIV-1 evolution, we tested whether variants at positively selected sites in the HIV-1 capsid affected the ability of human TRIM5a alleles to restrict HIV-1. Our results indicate that TRIM5a does not play a significant role in the evolution of HIV1 capsid. At last, our work concentrated on the newly discovered anti-HIV-1 restriction factor SAMHD1. We determined its coding sequence in a panel of 25 species of primates. Evolutionary analyses of positively selected sites in SAMHD1 domains and functional assays identified the domain of SAMHD1 interacting with the lentiviral protein Vpx. Similar to other viral countermeasures targeting cellular restriction factors, Vpx was responsible of the degradation of SAMHD1 orthologs in a species-specific manner. These findings contributed to understanding how restriction factors and viruses evolve to counteract each other.

Rare genomic structural variants in complex disease: lessons from the replication of associations with obesity.

The limited ability of common variants to account for the genetic contribution to complex disease has prompted searches for rare variants of large effect, to partly explain the 'missing heritability'. Analyses of genome-wide genotyping data have identified genomic structural variants (GSVs) as a source of such rare causal variants. Recent studies have reported multiple GSV loci associated with risk of obesity. We attempted to replicate these associations by similar analysis of two familial-obesity case-control cohorts and a population cohort, and detected GSVs at 11 out of 18 loci, at frequencies similar to those previously reported. Based on their reported frequencies and effect sizes (OR≥25), we had sufficient statistical power to detect the large majority (80%) of genuine associations at these loci. However, only one obesity association was replicated. Deletion of a 220 kb region on chromosome 16p11.2 has a carrier population frequency of 2×10(-4) (95% confidence interval [9.6×10(-5)-3.1×10(-4)]); accounts overall for 0.5% [0.19%-0.82%] of severe childhood obesity cases (P = 3.8×10(-10); odds ratio = 25.0 [9.9-60.6]); and results in a mean body mass index (BMI) increase of 5.8 kg.m(-2) [1.8-10.3] in adults from the general population. We also attempted replication using BMI as a quantitative trait in our population cohort; associations with BMI at or near nominal significance were detected at two further loci near KIF2B and within FOXP2, but these did not survive correction for multiple testing. These findings emphasise several issues of importance when conducting rare GSV association, including the need for careful cohort selection and replication strategy, accurate GSV identification, and appropriate correction for multiple testing and/or control of false discovery rate. Moreover, they highlight the potential difficulty in replicating rare CNV associations across different populations. Nevertheless, we show that such studies are potentially valuable for the identification of variants making an appreciable contribution to complex disease.

Expression of Staphylococcus aureus clumping factor A in Lactococcus lactis subsp. cremoris using a new shuttle vector.

Staphylococcus aureus harbors redundant adhesins mediating tissue colonization and infection. To evaluate their intrinsic role outside of the staphylococcal background, a system was designed to express them in Lactococcus lactis subsp. cremoris 1363. This bacterium is devoid of virulence factors and has a known genetic background. A new Escherichia coli-L. lactis shuttle and expression vector was constructed for this purpose. First, the high-copy-number lactococcal plasmid pIL253 was equipped with the oriColE1 origin, generating pOri253 that could replicate in E. coli. Second, the lactococcal promoters P23 or P59 were inserted at one end of the pOri253 multicloning site. Gene expression was assessed by a luciferase reporter system. The plasmid carrying P23 (named pOri23) expressed luciferase constitutively at a level 10,000 times greater than did the P59-containing plasmid. Transcription was absent in E. coli. The staphylococcal clumping factor A (clfA) gene was cloned into pOri23 and used as a model system. Lactococci carrying pOri23-clfA produced an unaltered and functional 130-kDa ClfA protein attached to their cell walls. This was indicated both by the presence of the protein in Western blots of solubilized cell walls and by the ability of ClfA-positive lactococci to clump in the presence of plasma. ClfA-positive lactococci had clumping titers (titer of 4,112) similar to those of S. aureus Newman in soluble fibrinogen and bound equally well to solid-phase fibrinogen. These experiments provide a new way to study individual staphylococcal pathogenic factors and might complement both classical knockout mutagenesis and modern in vivo expression technology and signature tag mutagenesis.

Role of intracellular signaling pathways activated in fibroblasts in response to lipoproteins

Summary The best described physiological function of low-density lipoproteins (LDL) is to transport cholesterol to target tissues. LDL deliver their cholesterol cargo to cells following their interaction with the LDL receptor. LDL, when their vascular concentrations increase, have also been implicated in pathologies such as atherosclerosis. Among the cell types that are found in blood vessels, endothelial and smooth muscle cells have dominated cellular research on atherosclerotic mechanisms and LDL activation of signaling pathways, while very little is known about adventitial fibroblast activation caused by elevated lipoprotein levels. Since fibroblasts participate in wound repair and since it has recently been recognized that fibroblasts may play pivotal roles in vascular remodeling and repair of injury, we assessed whether lipoproteins affect fibroblast function. We have found that LDL specifically mediate the activation of a class of mitogen-activated protein kinases (MAPKs): the p38 MAPKs. The activation of this pathway in turn modulates cell shape by promoting lamellipodia formation and extensive cell spreading. This is of particular interest because it provides a mechanism by which LDL can promote wound healing or vessel wall remodeling as observed during the development of atherosclerosis. In order to understand the molecular mechanisms by which LDL induce p38 activation we searched for the component in the LDL particle responsible for the induction of this pathway. We found that cholesterol is the major component of lipoprotein particles that mediates their ability to stimulate the p38 MAPK pathway. Furthermore, we investigated the cellular mechanisms underlying the ability of LDL to induce cell shape changes and whether this could participate in wound repair. Our recent data demonstrates that the capacity of LDL to induce fibroblast spreading relies on their ability to stimulate IL-8 secretion, which in turn leads to accelerated wound healing. LDL-induced IL-8 production and subsequent wound closure are impaired upon inhibition of the p38 MAPK pathway indicating that the LDL-induced spreading and accelerated wound sealing rely on the ability of LDL to stimulate IL-8 secretion in a p38 MAPK-dependent manner. Therefore, regulation of fibroblast shape and migration by lipoproteins may be relevant to atherosclerosis that is characterized by increased LDL-cholesterol levels, IL-8 production and extensive remodeling of the vessel wall. Résumé: La fonction physiologique des lipoprotéines à faible densité (LDL) la mieux décrite est celle du transport du cholestérol aux tissus cibles. Les LDL livrent leur cargaison de cholestérol aux cellules après leur interaction avec le récepteur au LDL. Une concentration vasculaire des LDL augmenté est également impliquée dans le développement de l'athérosclérose. Parmi les types de cellule présents dans les vaisseaux sanguins, les cellules endothéliales et les cellules du muscle lisse ont dominé la recherche cellulaire sur les mécanismes athérosclérotiques et sur l'activation par les LDL des voies de signalisation intracellulaire. A l'inverse peu de choses sont connues sur l'activation des fibroblastes de l'adventice par les lipoprotéines. Puisqu'il a été récemment reconnu que les fibroblastes peuvent jouer un rôle central dans la remodélisation vasculaire et la réparation tissulaire, nous avons étudié si les lipoprotéines affectent la fonction des fibroblastes. Nous avons constaté que les LDL activent spécifiquement une classe de protéines kinases: les p38 MAPK (mitogen-activated protein kinases). L'activation de cette voie module à son tour la forme de la cellule en favorisant la formation de lamellipodes et l'agrandissement des cellules. Cela a un intérêt particulier car il fournit un mécanisme par lequel les LDL peuvent promouvoir la cicatrisation ou la remodélisation des parois vasculaires comme observés lors du développement de l'athérosclérose. Pour comprendre les mécanismes moléculaires par lesquels les LDL provoquent l'activation des p38 MAPK, nous avons cherché à identifier les composants dans la particule de LDL responsables de l'induction de cette voie. Nous avons constaté que le cholestérol est l'élément principal des particules de lipoprotéine qui contrôle leur capacité à stimuler la voie des p38 MAPK. En outre, nous avons examiné les mécanismes cellulaires responsables de la capacité des LDL à induire des changements dans la forme des cellules. Nos données récentes démontrent que la capacité des LDL à induire l'agrandissement des cellules, ainsi que leur aptitude à favoriser la cicatrisation, reposant sur leur capacité à stimuler la sécrétiond'IL-8. La production d'IL-8 induite par les LDL est bloquée par l'inhibition de la voie p38 MAPK, ce qui indique que l'étalement des cellules induit par les LDL ainsi que l'accélération de la cicatrisation sont liés à la capacité des LDL à stimuler la sécrétion d'IL8 via l'activation des p38 MAPK. La régulation de la forme et de la migration des fibroblastes par les lipoprotéines peuvent donc participer au développement de l'athérosclérose qui est caractérisée par l'augmentation des niveaux de production de LDL-cholestérol et d'IL-8 ainsi que par une remodélisation augmentée de la paroi du vaisseau.

Creation of an Age-Adjusted, Dual-Energy X-ray Absorptiometry-Derived Trabecular Bone Score Curve for the Lumbar Spine in Non-Hispanic US White Women.

The trabecular bone score (TBS, Med-Imaps, Pessac, France) is an index of bone microarchitecture texture extracted from anteroposterior dual-energy X-ray absorptiometry images of the spine. Previous studies have documented the ability of TBS of the spine to differentiate between women with and without fractures among age- and areal bone mineral density (aBMD)-matched controls, as well as to predict future fractures. In this cross-sectional analysis of data collected from 3 geographically dispersed facilities in the United States, we investigated age-related changes in the microarchitecture of lumbar vertebrae as assessed by TBS in a cohort of non-Hispanic US white American women. All subjects were 30 yr of age and older and had an L1-L4aBMDZ-score within ±2 SD of the population mean. Individuals were excluded if they had fractures, were on any osteoporosis treatment, or had any illness that would be expected to impact bone metabolism. All data were extracted from Prodigy dual-energy X-ray absorptiometry devices (GE-Lunar, Madison, WI). Cross-calibrations between the 3 participating centers were performed for TBS and aBMD. aBMD and TBS were evaluated for spine L1-L4 but also for all other possible vertebral combinations. To validate the cohort, a comparison between the aBMD normative data of our cohort and US non-Hispanic white Lunar data provided by the manufacturer was performed. A database of 619 non-Hispanic US white women, ages 30-90 yr, was created. aBMD normative data obtained from this cohort were not statistically different from the non-Hispanic US white Lunar normative data provided by the manufacturer (p = 0.30). This outcome thereby indirectly validates our cohort. TBS values at L1-L4 were weakly inversely correlated with body mass index (r = -0.17) and weight (r = -0.16) and not correlated with height. TBS values for all lumbar vertebral combinations decreased significantly with age. There was a linear decrease of 16.0% (-2.47 T-score) in TBS at L1-L4 between 45 and 90 yr of age (vs. -2.34 for aBMD). Microarchitectural loss rate increased after age 65 by 50% (-0.004 to -0.006). Similar results were obtained for other combinations of lumbar vertebra. TBS, an index of bone microarchitectural texture, decreases with advancing age in non-Hispanic US white women. Little change in TBS is observed between ages 30 and 45. Thereafter, a progressive decrease is observed with advancing age. The changes we observed in these American women are similar to that previously reported for a French population of white women (r(2) > 0.99). This reference database will facilitate the use of TBS to assess bone microarchitectural deterioration in clinical practice.

Tumor necrosis factor (TNF) signaling, but not TWEAK (TNF-like weak inducer of apoptosis)-triggered cIAP1 (cellular inhibitor of apoptosis protein 1) degradation, requires cIAP1 RING dimerization and E2 binding.

Cellular inhibitor of apoptosis (cIAP) proteins, cIAP1 and cIAP2, are important regulators of tumor necrosis factor (TNF) superfamily (SF) signaling and are amplified in a number of tumor types. They are targeted by IAP antagonist compounds that are undergoing clinical trials. IAP antagonist compounds trigger cIAP autoubiquitylation and degradation. The TNFSF member TWEAK induces lysosomal degradation of TRAF2 and cIAPs, leading to elevated NIK levels and activation of non-canonical NF-kappaB. To investigate the role of the ubiquitin ligase RING domain of cIAP1 in these pathways, we used cIAP-deleted cells reconstituted with cIAP1 point mutants designed to interfere with the ability of the RING to dimerize or to interact with E2 enzymes. We show that RING dimerization and E2 binding are required for IAP antagonists to induce cIAP1 degradation and protect cells from TNF-induced cell death. The RING functions of cIAP1 are required for full TNF-induced activation of NF-kappaB, however, delayed activation of NF-kappaB still occurs in cIAP1 and -2 double knock-out cells. The RING functions of cIAP1 are also required to prevent constitutive activation of non-canonical NF-kappaB by targeting NIK for proteasomal degradation. However, in cIAP double knock-out cells TWEAK was still able to increase NIK levels demonstrating that NIK can be regulated by cIAP-independent pathways. Finally we show that, unlike IAP antagonists, TWEAK was able to induce degradation of cIAP1 RING mutants. These results emphasize the critical importance of the RING of cIAP1 in many signaling scenarios, but also demonstrate that in some pathways RING functions are not required.

Effect of angiotensin converting enzyme inhibition in renovascular hypertension.

The unique ability of angiotensin converting enzyme (ACE) inhibitors to inhibit the generation of angiotensin II has made them very useful agents for treating patients with renovascular hypertension. Their efficacy in lowering blood pressure in this type of secondary hypertension is now well established. However, episodes of acute renal failure may occur during ACE inhibition, particularly when renal perfusion is compromised. This is often the case in patients with renal artery stenosis and a single kidney or with bilateral renal artery stenosis. In recent years, investigators have shown concern at the long-term fate of the stenotic kidney in patients with unilateral renal artery stenosis who are treated with ACE inhibitors. Although overall renal function remained stable, a decrease in glomerular filtration was demonstrated in the stenotic kidney under ACE inhibition. The long-term implications of this observation merit further investigations.

Oligomerization of the alpha 1a- and alpha 1b-adrenergic receptor subtypes. Potential implications in receptor internalization.

We combined biophysical, biochemical, and pharmacological approaches to investigate the ability of the alpha 1a- and alpha 1b-adrenergic receptor (AR) subtypes to form homo- and hetero-oligomers. Receptors tagged with different epitopes (hemagglutinin and Myc) or fluorescent proteins (cyan and green fluorescent proteins) were transiently expressed in HEK-293 cells either individually or in different combinations. Fluorescence resonance energy transfer measurements provided evidence that both the alpha 1a- and alpha 1b-AR can form homo-oligomers with similar transfer efficiency of approximately 0.10. Hetero-oligomers could also be observed between the alpha 1b- and the alpha 1a-AR subtypes but not between the alpha 1b-AR and the beta2-AR, the NK1 tachykinin, or the CCR5 chemokine receptors. Oligomerization of the alpha 1b-AR did not require the integrity of its C-tail, of two glycophorin motifs, or of the N-linked glycosylation sites at its N terminus. In contrast, helix I and, to a lesser extent, helix VII were found to play a role in the alpha 1b-AR homo-oligomerization. Receptor oligomerization was not influenced by the agonist epinephrine or by the inverse agonist prazosin. A constitutively active (A293E) as well as a signaling-deficient (R143E) mutant displayed oligomerization features similar to those of the wild type alpha 1b-AR. Confocal imaging revealed that oligomerization of the alpha1-AR subtypes correlated with their ability to co-internalize upon exposure to the agonist. The alpha 1a-selective agonist oxymetazoline induced the co-internalization of the alpha 1a- and alpha 1b-AR, whereas the alpha 1b-AR could not co-internalize with the NK1 tachykinin or CCR5 chemokine receptors. Oligomerization might therefore represent an additional mechanism regulating the physiological responses mediated by the alpha 1a- and alpha 1b-AR subtypes.