Characterization and Some Physicochemical Aspects of Pathological Microcalcifications

Several major diseases, such as cancer and cardiovascular abnormalities, may be linked to pathological deposition of minerals or organic compounds in various tissues. Thus, the detection of such minerals or compounds and understanding the physicochemical processes associated with their formation are essential. As underlined by Schmidt et al., in Europe and the U.S., breast cancer will occur in 1 in 10 women. If clustered calcifications are one of the mammographic signs of early breast cancer, their chemical nature must be determined. More precisely, calcium phosphates (CaPs) are frequently associated with malignancy, but calcium oxalates are present in benign lesions. From a medical viewpoint, pathological calcifications refer to at least three very different families of biominerals: concretions, metastatic calcifications and dystrophic calcifications. Concretions are found in hollow organs or ducts of the body. For example, kidney stones are solid concretions of dissolved minerals in urine found in the kidney. In contrast, metastatic and dystrophic calcifications, which can be considered ectopic calcifications, are defined as unexpected biomineralization occurring in soft tissues. In the absence of a systemic mineral imbalance, dystrophic calcification is often associated with tissue alteration or necrosis. In contrast, metastatic calcifications resulting from mineral imbalance are more systemic and affect various tissues (e.g., vessels, lungs, kidneys). A fourth family can be considered physiological calcification (bone), which becomes pathological with diseases such as arthrosis or osteoporosis

Intérêt public, intérêt privé et discrimination

Nous considérons un service à qualité variable dont chaque usager consomme au plus une unité. Les coûts de production, fixe et variable, ne dépendent pas de la qualité : améliorer, dans certaines limites, la qualité, n’augmente pas les coûts de production. Chaque usager cependant apprécie d’autant plus le service que celui-ci est de meilleure qualité : la propension à payer de l’usager est une fonction linéaire croissante de la qualité du service.Chaque usager est seul à connaître sa propre propension à payer, alors que la distribution des propensions est connue de tous, producteurs et consommateurs. Nous étudions comment et pourquoi, dans ces conditions, une discrimination par les prix et les qualités peut être pratiquée par les producteurs. Nous montrons qu’un monopole recherchant la maximisation de son profit ne pratiquera pas de discrimination; en revanche, dans un large champ de situation, il n’est possible d’atteindre un optimum de Pareto sous contraintes — informationnelle et financière — qu’en discriminant : le gain qu’apporte la discrimination en tant que mécanisme d’autosélection l’emporte sur le gaspillage qu’il y a à produire au même coût une qualité moindre.Nous reformulons enfin notre modèle pour élargir son domaine d’application à des questions telles que la tarification de l’accès à un réseau téléphonique, le marchandage dans un contexte d’achats répétés, etc.We consider a service whose quality is variable and from which every consumer consumes either one unit or nothing. Production costs, both fixed and variable, do not depend on quality: a higher quality service is no more costly to produce than a lower quality one. On the consumption side however, higher quality is preferred: a consumer's willingness-to-pay for one unit of the service is an increasing and linear function of the service quality.A consumer's willingness-to-pay is private information to him, whereas the corresponding distribution over all consumers is public information, hence known to the producers. In this setting we investigate why and how producers might use price and quality discrimination. We show that a profit-maximising monopolist will not discriminate, whereas it is often the case that reaching a constrained Pareto optimum will not be possible without some recourse—which we precisely define—to discrimination: the improvement in welfare thus brought by self-selection is worth some waste of quality.In the last section we reformulate our model in order to include in the analysis such topics as network access pricing, selling strategies when buying is repeated, etc

Intérêt public, intérêt privé et discrimination

We consider a service whose quality is variable and from which every consumer consumes either one unit or nothing. Production costs, both fixed and variable, do not depend on quality: a higher quality service is no more costly to produce than a lower quality one. On the consumption side however, higher quality is preferred: a consumer's willingness-to-pay for one unit of the service is an increasing and linear function of the service quality. Nous considérons un service à qualité variable dont chaque usager consomme au plus une unité. Les coûts de production, fixe et variable, ne dépendent pas de la qualité : améliorer, dans certaines limites, la qualité, n’augmente pas les coûts de production. Chaque usager cependant apprécie d’autant plus le service que celui-ci est de meilleure qualité : la propension à payer de l’usager est une fonction linéaire croissante de la qualité du service.

Mechanical properties of self-setting composites: influence of the carboxymethylcellulose content and hydration state

The impact of the carboxymethylcellulose (CMC) content on the mechanical properties of calcium phosphate–calcium carbonate–CMC composite cements for bone substitution was investigated. The relevance of the compressive test conditions (wet or dried composite cements) is discussed and models are proposed to better understand the mechanisms involved in the mechanical properties of the composite materials. Based on a modellisation using the Voigt model for dried composite cements, we show that a minimum of CMC content of around 10–20 % is needed to enhance the mechanical properties of the dried composite materials (up to 86 MPa for the composite including 50 wt% CMC) through the formation of a mineral–organic entangled network. The compressive strength of the wet samples is low (\3 MPa) but the gain observed in the dried composites is encouraging and might be extrapolated to wet conditions if we were to use a less hydrophilic polysaccharid

Le temps partiel moins attractif ?

Dans les secteurs de l’hôtellerie-restauration et du commerce, le temps partiel a longtemps été un outil privilégié de flexibilité pour les entreprises qui cherchaient à adapter leur volume de main-d’œuvre en fonction de leurs besoins, souvent difficiles à anticiper. Cependant, à partir de la fin des années 1990, les contrats à temps partiel sont devenus de moins en moins flexibles à mesure que le législateur en encadrait et en réglementait les usages. Les pouvoirs publics ont ainsi cherché à limiter les excès des périodes antérieures et la précarité associée à ces contrats, touchant essentiellement des femmes peu diplômées. L’article s’interroge sur les effets de ces changements législatifs dans les branches et dans les entreprises : comment les acteurs nationaux les ont-ils traduits dans les conventions collectives ? Comment les entreprises ont-elles réagi et abordent-elles cette nouvelle donne législative et conventionnelle ? À partir d’une étude qualitative réalisée de 2009 à 2011, nous revenons sur les enjeux du temps partiel dans les secteurs de services et sur les conséquences de la loi et de son appropriation par les acteurs à tous les niveaux de la régulation collective (articulations entre la loi, les conventions nationales, les accords d’entreprises et les pratiques sur le terrain). Nous avançons que de nouvelles configurations organisationnelles flexibles émergent dans les entreprises, associant au temps partiel un recours accru à la polyactivité, à la polyvalence et à la polycompétence.Part time work has long been a privileged management tool for companies in the “hotel and catering” and “retail trade” service sectors seeking to adjust employment volume to companies’ needs that are not easy to anticipate. However, since the end of the nineties, these part time contracts have become less and less flexible as the legislator has increased their legal framework and regulated their use. The aim of public authorities was to minimise the lack of job security which characterised part time positions, mainly occupied by unskilled women. This article deals with the implementation of these legislative changes within the service sector: how did national industrial partners translate them into collective bargaining agreements? How did companies react to these new labour laws? Based on a qualitative study conducted from 2009 to 2011, this article analyses the issues of part time work in the service sector and the effects of new legislation at every level of collective regulation: legal structures, collective bargaining agreements, company agreements, and practical experiments in companies. The authors also give an account of new flexible organizational patterns in companies, linking part time work to more polyvalence, polyactivity and polycompetence

Freeze-casting for PLGA/carbonated apatite composite scaffolds: structure and properties

This paper focuses on the fabrication of three-dimensional porous PLGA-biomimetic carbonated apatite composite scaffolds by freeze-casting and using dimethyl carbonate as a solvent. Several charge/polymer ratios were tested in order to finely understand the influence of the filler rate on the scaffold porosity and mechanical and degradation properties using complementary characterization techniques (SEM, mercury porosimetry and X-ray microtomography). It was demonstrated that the apatite ratio within the composite scaffold has a strong influence in terms of architecture, material cohesion, mechanical properties and in vitro degradation properties. An optimum biomimetic apatite ratio was reached to combine good mechanical properties (higher rigidity) and material cohesion. In vitro degradation studies showed that higher apatite filler rates limited PLGA degradation and enhanced the hydrophilicity of the scaffolds which is expected to improve the biological properties of the scaffolds in addition to the bioactivity related to the presence of the apatite analogous to bone mineral

Up-regulation of avian uncoupling protein in cold-acclimated and hyperthyroid ducklings prevents reactive oxygen species production by skeletal muscle mitochondria

<p>Abstract</p> <p>Background</p> <p>Although identified in several bird species, the biological role of the avian homolog of mammalian uncoupling proteins (avUCP) remains extensively debated. In the present study, the functional properties of isolated mitochondria were examined in physiological or pharmacological situations that induce large changes in avUCP expression in duckling skeletal muscle.</p> <p>Results</p> <p>The abundance of avUCP mRNA, as detected by RT-PCR in gastrocnemius muscle but not in the liver, was markedly increased by cold acclimation (CA) or pharmacological hyperthyroidism but was down-regulated by hypothyroidism. Activators of UCPs, such as superoxide with low doses of fatty acids, stimulated a GDP-sensitive proton conductance across the inner membrane of muscle mitochondria from CA or hyperthyroid ducklings. The stimulation was much weaker in controls and not observed in hypothyroid ducklings or in any liver mitochondrial preparations. The production of endogenous mitochondrial reactive oxygen species (ROS) was much lower in muscle mitochondria from CA and hyperthyroid ducklings than in the control or hypothyroid groups. The addition of GDP markedly increased the mitochondrial ROS production of CA or hyperthyroid birds up to, or above, the level of control or hypothyroid ducklings. Differences in ROS production among groups could not be attributed to changes in antioxidant enzyme activities (superoxide dismutase or glutathione peroxidase).</p> <p>Conclusion</p> <p>This work provides the first functional <it>in vitro </it>evidence that avian UCP regulates mitochondrial ROS production in situations of enhanced metabolic activity.</p

Is the formula of Traub still up to date in antemortem blood glucose level estimation?

According to the hypothesis of Traub, also known as the ‘formula of Traub', postmortem values of glucose and lactate found in the cerebrospinal fluid or vitreous humor are considered indicators of antemortem blood glucose levels. However, because the lactate concentration increases in the vitreous and cerebrospinal fluid after death, some authors postulated that using the sum value to estimate antemortem blood glucose levels could lead to an overestimation of the cases of glucose metabolic disorders with fatal outcomes, such as diabetic ketoacidosis. The aim of our study, performed on 470 consecutive forensic cases, was to ascertain the advantages of the sum value to estimate antemortem blood glucose concentrations and, consequently, to rule out fatal diabetic ketoacidosis as the cause of death. Other biochemical parameters, such as blood 3-beta-hydroxybutyrate, acetoacetate, acetone, glycated haemoglobin and urine glucose levels, were also determined. In addition, postmortem native CT scan, autopsy, histology, neuropathology and toxicology were performed to confirm diabetic ketoacidosis as the cause of death. According to our results, the sum value does not add any further information for the estimation of antemortem blood glucose concentration. The vitreous glucose concentration appears to be the most reliable marker to estimate antemortem hyperglycaemia and, along with the determination of other biochemical markers (such as blood acetone and 3-beta-hydroxybutyrate, urine glucose and glycated haemoglobin), to confirm diabetic ketoacidosis as the cause of deat