Décentralisation : l'exigence du débat.

Cette publication n'a pas de résumé

Surface proteins of Shiga toxin-producing Escherichia coli mediate association with milk fat globules in raw milk

IntroductionBy adhering to host cells and colonizing tissues, bacterial pathogens can successfully establish infection. Adhesion is considered the first step of the infection process and bacterial adhesion to anti-adhesive compounds is now seen as a promising strategy to prevent infectious diseases. Among the natural sources of anti-adhesive molecules, the membrane of milk fat globules (MFGs) is of interest because of its compositional diversity of proteins and glycoconjugates. However, few studies have focused on the bacterial molecules involved in MFG- mediated inhibition of bacterial adhesion to enterocytes.MethodsWe used three pathogenic Shiga toxin-producing Escherichia coli (STEC) strains (O26:H11 str. 21765, O157:H7 str. EDL933, and O103:H3 str. PMK5) as models to evaluate whether STEC surface proteins are involved in the affinity of STEC for MFG membrane proteins (MFGMPs). The affinity of STEC for MFGMPs was assessed both indirectly by a natural raw milk creaming test and directly by an adhesion test. Mass spectrometry was used to identify enriched STEC proteins within the protein fraction of MFGMs. Bacterial mutants were constructed and their affinity to MFGs were measured to confirm the role of the identified proteins.ResultsWe found that free STEC surface proteins inhibit the concentration of the pathogen in the MFG-enriched cream in a strain-dependent manner. Moreover, the OmpA and FliC proteins were identified within the protein fraction of MFGMs. Our results suggest that FliC protein participates in STEC adhesion to MFGMPs but other STEC molecules may also participate.DiscussionFor the first time, this study highlighted, the involvement of STEC surface proteins in the affinity for MFGs. The mechanism of STEC-MFG association is still not fully understood but our results confirm the existence of receptor/ligand type interactions between the bacteria and MFGs. Further studies are needed to identify and specify the molecules involved in this interaction. These studies should consider the likely involvement of several factors, including adhesion molecules, and the diversity of each STEC strain

Synthesis of phenolics and flavonoids in ginger (Zingiber officinale Roscoe) and their effects on photosynthesis rate

The relationship between phenolics and flavonoids synthesis/accumulation and photosynthesis rate was investigated for two Malaysian ginger (Zingiber officinale) varieties grown under four levels of glasshouse light intensity, namely 310, 460, 630 and 790 μmol m 2s 1. High performance liquid chromatography (HPLC) was employed to identify and quantify the polyphenolic components. The results of HPLC analysis indicated that synthesis and partitioning of quercetin, rutin, catechin, epicatechin and naringenin were high in plants grown under 310 μmol m 2s 1. The average value of flavonoids synthesis in leaves for both varieties increased (Halia Bentong 26.1%; Halia Bara 19.5%) when light intensity decreased. Photosynthetic rate and plant biomass increased in both varieties with increasing light intensity. More specifically, a high photosynthesis rate (12.25 μmol CO 2 m 2s 1 in Halia Bara) and plant biomass (79.47 g in Halia Bentong) were observed at 790 μmol m 2s 1. Furthermore, plants with the lowest rate of photosynthesis had highest flavonoids content. Previous studies have shown that quercetin inhibits and salicylic acid induces the electron transport rate in photosynthesis photosystems. In the current study, quercetin was an abundant flavonoid in both ginger varieties. Moreover, higher concentration of quercetin (1.12 mg/g dry weight) was found in Halia Bara leaves grown under 310 μmol m 2s 1 with a low photosynthesis rate. Furthermore, a high content of salicylic acid (0.673 mg/g dry weight) was detected in Halia Bara leaves exposed under 790 μmol m 2s 1 with a high photosynthesis rate. No salicylic acid was detected in gingers grown under 310 μmol m 2s 1. Ginger is a semi-shade loving plant that does not require high light intensity for photosynthesis. Different photosynthesis rates at different light intensities may be related to the absence or presence of some flavonoid and phenolic compounds

Evaluation Research and Institutional Pressures: Challenges in Public-Nonprofit Contracting

This article examines the connection between program evaluation research and decision-making by public managers. Drawing on neo-institutional theory, a framework is presented for diagnosing the pressures and conditions that lead alternatively toward or away the rational use of evaluation research. Three cases of public-nonprofit contracting for the delivery of major programs are presented to clarify the way coercive, mimetic, and normative pressures interfere with a sound connection being made between research and implementation. The article concludes by considering how public managers can respond to the isomorphic pressures in their environment that make it hard to act on data relating to program performance.This publication is Hauser Center Working Paper No. 23. The Hauser Center Working Paper Series was launched during the summer of 2000. The Series enables the Hauser Center to share with a broad audience important works-in-progress written by Hauser Center scholars and researchers

Varieties of Capitalism and the Learning Firm: Contemporary Developments in EU and German Company Law - A Comment on the Strine-Bainbridge Debate About Shared Values of Corporate Management and Labor

Research in corporate governance and in labour law has been characterized by a disjuncture in the way that scholars in each field are addressing organizational questions related to the business enterprise. While labour has eventually begun to shift perspectives from aspirations to direct employee involvement in firm management, as has been the case in Germany, to a combination of \u27exit\u27 and \u27voice\u27 strategies involving pension fund management and securities litigation, it remains to be seen whether this new stream will unfold as a viable challenge to an otherwise exclusionary shareholder value paradigm. At the same time, recent suggestions made by Delaware Chancery Court Vice Chancellor Strine, to dare think about potentially shared commitments between management and labor - and UCLA\u27s Stephen Bainbridge\u27s response - underline the viability - and, the contestedness - of attempts at moving the corporate governance debate beyond the confines of corporate law proper. While such a wider view had already famously been encouraged by Dean Clarke in his 1986 treatise on Corporate Law (p. 32), mainstream corporate law does not seem to have endorsed this perspective. This paper takes the questionable divide between management and labor within the framework of a limiting corporate governance concept as starting point to explore the institutional dynamics of the corporation, hereby building on the theory of the innovative enterprise, as developed by management theorists Mary O\u27Sullivan and William Lazonick. Largely due to the sustained distance between corporate and labour law scholars, neither group has effectively addressed their common blind spot: a better understanding of the business enterprise itself. In midst of an unceasing flow of affirmations of the finance paradigm of the corporation on the one hand and \u27voice\u27 strategies by labour on the other, it seems to fall to management theorists to draw lessons from the continuing co-existence of different forms of market organization, in which companies appear to thrive. Exploring the conundrum of \u27risky\u27 business decisions within the firm, management theorists have been arguing for the need to adopt a more sophisticated organizational perspective on companies operating on locally, regionally and transnationally shaped, often highly volatile market segments. Research by comparative political economists has revealed a high degree of connectivity between corporate governance and economic performance without, however, arriving at such favourable results only for shareholder value regimes. Such findings support the view that corporate governance regimes are embedded in differently shaped regulatory frameworks, characterized by distinct institutions, both formal and informal, and enforcement processes. As a result of these findings, arguments to disassociate issues of corporate governance from those of the firm\u27s (social) responsibility [CSR] have been losing ground. Instead, CSR can be taken to be an essential part of understanding a particular business enterprise. It is the merging of a comparative political economy perspective on the corporation with one on the organizational features, structures and processes of the corporation, which can help us better understand the distribution of power and knowledge within the \u27learning firm\u27

Bureaucracy as a Lens for Analyzing and Designing Algorithmic Systems

Scholarship on algorithms has drawn on the analogy between algorithmic systems and bureaucracies to diagnose shortcomings in algorithmic decision-making. We extend the analogy further by drawing on Michel Crozier’s theory of bureaucratic organizations to analyze the relationship between algorithmic and human decision-making power. We present algorithms as analogous to impartial bureaucratic rules for controlling action, and argue that discretionary decision-making power in algorithmic systems accumulates at locations where uncertainty about the operation of algorithms persists. This key point of our essay connects with Alkhatib and Bernstein’s theory of ’street-level algorithms’, and highlights that the role of human discretion in algorithmic systems is to accommodate uncertain situations which inflexible algorithms cannot handle. We conclude by discussing how the analysis and design of algorithmic systems could seek to identify and cultivate important sources of uncertainty, to enable the human discretionary work that enhances systemic resilience in the face of algorithmic errors.Peer reviewe

The interfacial bioscience grand challenge.

This report is broken down into the following 3 sections: (1) Chemical Cross-linking and Mass Spectrometry Applied to Determination of Protein Structure and Dynamics; (2) Computational Modeling of Membrane Protein Structure and Dynamics; and (3) Studies of Toxin-Membrane Interactions using Single Molecule Biophysical Methods