Densification and depression in glass transition temperature in polystyrene thin films.

Ellipsometry and X-ray reflectivity were used to characterize the mass density and the glass transition temperature of supported polystyrene (PS) thin films as a function of their thickness. By measuring the critical wave vector (qc) on the plateau of total external reflection, we evidence that PS films get denser in a confined state when the film thickness is below 50 nm. Refractive indices (n) and electron density profiles measurements confirm this statement. The density of a 6 nm (0.4 gyration radius, Rg) thick film is 30% greater than that of a 150 nm (10Rg) film. A depression of 25 °C in glass transition temperature (Tg) was revealed as the film thickness is reduced. In the context of the free volume theory, this result seems to be in apparent contradiction with the fact that thinner films are denser. However, as the thermal expansion of thinner films is found to be greater than the one of thicker films, the increase in free volume is larger for thin films when temperature is raised. Therefore, the free volume reaches a critical value at a lower Tg for thinner films. This critical value corresponds to the onset of large cooperative movements of polymer chains. The link between the densification of ultrathin films and the drop in their Tg is thus reconciled. We finally show that at their respective Tg(h) all films exhibit a critical mass density of about 1.05 g/cm(3) whatever their thickness. The thickness dependent thermal expansion related to the free volume is consequently a key factor to understand the drop in the Tg of ultrathin films.

Statistical analysis of mounded surfaces: application to the evolution of ultrathin gold film morphology with deposition temperature.

Extracting characteristic dimensions from mounded surfaces such as grain size or intergrain lengths is usually made by statistical analysis. Different statistical functions are used in the literature to extract characteristic lengths. The main issue is that depending on the choice of the statistical function the results can be very different. In this paper, we demonstrate using a series of model mounded surfaces for which characteristic dimensions are known, that a method (namely, interfacial differential function, IDF) is the most effective method to determine the different characteristic lengths. The influence on the statistical treatment of the variation of the different characteristic lengths is then studied and confirms the ability of the IDF analysis. The IDF method was used to analyze the evolution of ultrathin gold film morphology as function of deposition temperature. This approach allows us to demonstrate that the roughness increase with deposition temperature is mainly due to a grain height increase and not to a grain coarsening phenomena as it was claimed before.

Tuning the architecture of cellulose nanocrystal-poly(allylamine hydrochloride) multilayered thin films: influence of dipping parameters.

Multilayered thin films consisting of alternating cationic polyelectrolyte, poly(allylamine hydrochloride) (PAH), and anionic cellulose nanocrystals (CNs) were constructed using the dipping procedure by screening different experimental parameters: the drying step between each layer adsorption, the dipping time, the ionic strength of the PAH solution, and the concentration of CNs dispersion. We showed that the drying process and the ionic strength of PAH solution were crucial parameters for the successful construction of 8-bilayer films. Film thickness is mainly influenced by dipping time and CN concentration when using the dipping procedure without drying. Two architectures of adsorbed CN layers-a single or a double layer of CNs-were revealed on the basis of the thickness increment per bilayer, depending on experimental conditions. The layer adsorption process was investigated in real-time using quartz crystal microbalance with dissipation (QCM-D) experiments in an aqueous environment or by incorporating a drying step. On the basis of in situ construction of PAH-CN films in wet media, QCM-D data were indicative of highly hydrated films for which the progressive layer stacking is disturbed or prevented. QCM-D monitoring of CNs and PAH layer adsorption was monitored by incorporating a drying process. The impact of experimental parameters on PAH-CN multilayered construction and on CN layer configuration is discussed. This study offers new opportunities for tailoring the architecture of CN-based multilayer films.

Relative age is associated with sport dropout: evidence from youth categories of French basketball.

The aim of the current research was to investigate the relative age effect (RAE) as a factor of basketball dropout. In order to do so, we examined the distribution of birth dates of young male (n=44,498) and female (n=30,147) French basketball players who have dropped out this sport during or at the end of the 2005-2006 season. χ(2) analyses showed an underrepresentation of dropouts among male players born early in the competition year and an overrepresentation among those born late in the "9-10 years old,""11-12 years old," and "13-14 years old" categories and in the first year of the "15-17 years old" category. Concerning girls, this asymmetry was observed across the same age categories. For both boys and girls, there was no biased distribution in the "7-8 years old" category. Findings of the present study confirm that the RAE should be taken into consideration in studies about sport dropout as a variable that may influence this phenomenon significantly.

Relative age effect in female sport: a diachronic examination of soccer players.

The relative age effect (RAE) is a biased distribution of elite athletes' birthdates, with an overrepresentation of those born at the beginning of the competitive year and an underrepresentation of those born at the end. Despite an abundant literature, the impact of sex on this phenomenon remains neglected by most researchers. This study investigated the whole sample of female soccer players affiliated to the French Soccer Federation for the 2006-2007 season (n=57 892). It first aimed at testing the presence of RAE depending on age. Next, we looked at the birthdates of dropout players during the next season (n=15 285), to test whether relative age accounts for dropout from the activity. The analyses revealed significant differences between the expected and the observed distributions for all age categories. Furthermore, a significantly biased distribution of dropout players' birthdates was found for the <10, <14, and <17 categories. On the whole, dropout players are underrepresented in Q1 and Q2, but overrepresented in Q3 and Q4. This study completes the literature on RAE among females, but the inconsistency of the results calls for more research on this population.

Self-assembled monolayers of bisphosphonates: influence of side chain steric hindrance.

Bisphosphonates form self-assembled monolayers (SAMs) spontaneously on stainless steel, silicon, and titanium oxidized surfaces. We used contact angle measurements, atomic force microscopy, and X-ray reflectivity analysis to study the formation of SAMs on a model surface of ultraflat titanium (rms = 0.2 nm). The results were extended to standard materials (mechanically polished titanium, stainless steel, and silicon) and showed that water-soluble bisphosphonic perfluoropolyether can easily form SAMs, with 100% surface coverage and a layer thickness of less than 3 nm. Hydrophobic (water contact angle >110 degrees on stainless steel or titanium) and lipophobic (methylene iodide contact angle >105 degrees on titanium) properties are discussed in terms of industrial applications.

The relative age effect in young French basketball players: a study on the whole population.

The aim of this study is to test the presence of the relative age effect (RAE) and to examine height in an overall population of the young French basketball players from 7 to 18 years old, male (n=151 259) and female (n=107 101). For the boys as for the girls, the results show a statistically significant RAE in all age categories. The effect seems more pronounced during puberty. As far as the height is concerned, players born during quarters 1 and 2 are always significantly taller than those born during quarter 4, apart from the 17-year-old female players. These results require a new look at the methodology in the statistical calculation and the interpretation of RAE. A study wanting to give a precise measurement of this effect will have to take as the expected theoretical distribution the whole population of licensed players in the corresponding years, rather than one on the global population of the country. This will avoid the hasty conclusion that an asymmetric distribution of dates of birth of professional players would be due to RAE, whereas in reality it would be representative of one existing in the population of licensed players.

Experimental evidence of the electrostatic contribution to the bending rigidity of charged membranes.

We address the issue of the origin of the bending rigidity of a charged membrane formed from amphiphilic molecules. Electrostatic effects are investigated by direct measurement of the force necessary to deform a catanionic membrane as function of the ionic strength of the medium by means of an atomic force microscope (AFM). Using continuum mechanical modeling of membrane deformation, we derive the bending rigidity of the catanionic membranes and monitor for the first time its decrease in response to increasing salt concentration.

Prosaposin is a novel androgen-regulated gene in prostate cancer cell line LNCaP.

Androgen-regulated genes (ARG) are implicated in normal and neoplastic growth of the prostate. Recently, we reported genomic amplification and/or overexpression of a previously known neurotrophic factor, prosaposin, in androgen-independent (AI) or metastatic prostate cancer (PCa) cells and tissues. Prosaposin and/or its known active molecular derivatives (e.g., saposin C) function as a pluripotent growth factor with diverse biological activities that favor malignant phenotypes in PCa cells. In addition, prosaposin or saposin C upregulates androgen receptor (AR) and AR-target genes (i.e., prostate-specific antigen, Probasin) expression and activity in LNCaP cells. Here, we examined prosaposin as an ARG. We report that DHT treatment of LNCaP cells increases prosaposin expression. In addition, we demonstrate androgen-responsiveness of prosaposin promoter and AR occupancy to a hormone-responsive element located in the proximal region of the prosaposin promoter. Our data for the first time identify prosaposin as an ARG. This observation, together with the pleiotropic growth factor activity of prosaposin, might suggest a role for this molecule in AR-dependent progression of prostate cancer at its early or late AI-state.

Direct method to study membrane rigidity of small vesicles based on atomic force microscope force spectroscopy.

Mechanical properties of lipidic membranes such as their bending rigidity are governing liposome morphology and play an important role in processes like membrane fusion and adhesion. Force versus deformation measurements are the most direct means to determine this, but so far experimental data is scarce and mainly stems from techniques that are limited to giant vesicles. We present atomic force microscope force spectroscopy as a method allowing force-deformation measurements of submicron vesicles. Bending rigidities of small unilamellar dipalmitoylphosphatidylcholine (DPPC) liposomes (R<200 nm) can be derived from the force-deformation data using analytical models based on shell theory and are in good agreement with independent measurements.

Azobenzene-containing monolayer with photoswitchable wettability.

A compact monolayer containing azobenzene has been prepared on silicon substrates. The elaboration route consisted of covalent grafting of freshly synthesized azobenzene moieties onto an isocyanate-functionalized self-assembled monolayer (SAM). The highly packed and ordered isocyanate-functionalized SAM and the azobenzene-functionalized SAM were monitored and characterized by contact angle measurements and X-ray reflectivity (XR). Photoswitching of the wettability of the film induced by the reversible cis-trans isomerization of the azobenzene chromophores is experimentally shown from water and olive oil contact angle measurements.

Interleukin-1beta (IL-1beta) induces a crosstalk between cAMP and ceramide signaling pathways in thyroid epithelial cells.

Interleukin-1 beta (IL-1beta) is an important regulator of the thyroid cell function. This cytokine has been largely described to trigger an important biological signaling cascade: the sphingomyelin/ceramide pathway. In this report, we show that IL-1beta induces the transient activation of a neutral sphingomyelinase in porcine thyroid cells. Moreover, IL-1beta and ceramides are demonstrated to inhibit the TSH-induced cAMP production via the implication of alphaGi subunit of the adenylyl cyclase system. This crosstalk between cAMP and ceramide pathways constitutes a preponderant process in the TSH-controlled differentiation state of thyrocytes. All these results argue for the involvement of ceramides and IL-1beta in the thyroid function regulation, leading to a cell dedifferentiated state.

[Unusual presentation of infantile myofibromatosis with an ulcered plaque]. / Présentation inhabituelle d'une myofibromatose cutanée infantile en plaque unique ulcérée.

INTRODUCTION: Infantile myofibromatosis is a rare fibrovascular-like, isolated or multicentric tumor, occasionally of the bone or an organ and appearing before the age of 2. We report a case of infantile myofibromatosis in a child in an atypical form with a single, ulcerated plaque and having developed after the onset of clusters of papular nodules. OBSERVATION: An infant was seen in consultation because of asymptomatic papules that had developed on the back. The histological examination of a partial biopsy revealed a histiocytofibromatus aspect and led to the diagnosis of clusters of multiple histiocytofibromatous. One year later, the papular nodules had converged, forming a large plaque with ulcerated center. The progressive extension and the absence of healing prompted surgical exeresis and the final diagnosis of myofibromatosis. DISCUSSION: Diagnosis of infantile myofibromatosis is difficult histologically and clinically and relies on a clear anatomoclinical confrontation. The clinical aspects are varied. To our knowledge, myofibromatosis with a single ulcerated plaque has never been reported in the literature before.

[Pseudolymphomatous folliculitis]. / Folliculites pseudo-lymphomateuses.

INTRODUCTION: A case of a rare variety of cutaneous pseudo-lymphoma is reported. CASE REPORT: A 13 Year-old boy presented with a nodule on the nose groove which corresponded histologically to a dense, peri follicular lymphocyte infiltration penetrating the hair. Following partial biopsy, the lesion disappeared within a fortnight. COMMENTS: Our case report corresponds to the entity described in 1999 in the Japanese. Our case occurred in a Caucasian French adolescent. The papulonodule, usually unique, is composed histologically of a dense, peripilary infiltrate that penetrates and disrupt the hair. The majority of cases have been removed surgically. Those that have not usually disappear following partial biopsy. The individualization of this entity is debatable: the involvement of the hair follicles by the infiltration of pseudolymphomas on the face is frequent and non-specific.

Thrombospondin 1: a multifunctional protein implicated in the regulation of tumor growth.

Thrombospondins belong to a family of extracellular matrix (ECM) proteins widely found from embryonic to adult tissues. The modular structure of thrombospondins contains a series of peptide sequences implicated in a multiplicity of biological functions. Extracellular matrix undergoes important alterations under proteolysis that occurs in pathological processes like tumorigenesis. An elevated secretion of thrombospondin 1 (TSP1) is often observed in tumors and is sometimes considered as a predictive factor. However, the role of TSP1 in cancer progression remains controversial and must be carefully apprehended. The regulation of cell adhesion, proliferation, apoptosis by TSP1 is examined in the present review and it is clear from the literature and from our investigations that TSP1 presents both stimulatory and inhibitory effects. The exposition of cryptic sites upon conformational changes can partially explain this contradiction. More interestingly, the analysis of TSP1-directed intracellular signaling pathways activated through specific receptors or supramolecular receptors docking systems may be useful to discriminate the precise function of TSP1 in tumor progression. The central role played by TSP1 in the control of matrix-degrading enzyme activation and catabolism reveals attractive tracks of research and highlights the involvement of the lipoprotein receptor-related protein (LRP) receptor in these events. Therefore, TSP1-derived peptides constitute a source of potentially active matrikins which could provide essential tools in cancer therapy.

[Cold-induced urticaria]. / Urticaire au froid.

Cold urticaria is characterized by the development of urticaria, usually superficial and/or angioedematous reaction after cold contact. It was found predominantly in young women. The diagnosis is based on the history and ice cube test. Patients with a negative ice cube test may have represented systemic cold urticaria (atypical acquired cold urticaria) induced by general body cooling. The pathogenesis is poorly understood. Cold urticaria can be classified into acquired and familial disorders, with an autosomal dominant inheritance. Idiopathic cold urticaria is most common type but the research of a cryopathy is necessary. Therapy is often difficult. It is essential that the patient be warned of the dangers of swimming in cold water because systemic hypotension can occur. H1 antihistamines can be used for treatment of cold urticaria but the clinical responses are highly variable. The combination with an H2 antagonists is more effective. Doxepin may be useful in the treatment. Leukotriene receptor antagonists may be a novel, promising drug entity. In patients who do not respond to previous treatments, induction of cold tolerance may be tried.

TGFbeta1 effects on functional activity of porcine thyroid cells cultured in suspension.

Thyrotropin (TSH) and transforming growth factor beta 1 (TGFbeta1) have major roles in the regulation of folliculogenesis and differentiation in thyroid cells. Isolated porcine thyroid cells cultured in the presence of TSH on a plastic surface recover a follicular architecture and exhibit normal functional properties. The addition of TGFbeta1 to the culture medium induces important morphological changes and extracellular matrix remodelling. Similarly, thyroid cells lose their ability to organify iodine and their responsiveness to adenylate cyclase. The aim of this study was to analyse the influence of TGFbeta1 on the functional activity of thyrocytes in suspension culture, independent of follicle disruption. In this system, we demonstrate that TGFbeta1 inhibits expression of thyroperoxidase, NADPH oxidase activity, iodine uptake and, consequently, iodine organification. Moreover, TGFbeta1 decreases basal and TSH-stimulated cAMP production and TSH receptor expression. Taken together, these data converge to demonstrate an essential role of TGFbeta1 in the regulation of the thyroid cell function.

Interleukin 1 beta (IL-1 beta) action in porcine thyroid cells involves the ceramide signalling pathway.

Interleukin 1 beta (IL-1beta) is often associated with thyroidal autoimmune diseases. This cytokine has been largely described to trigger an important biological signalling pathway: the sphingomyelin/ceramide pathway. In this report we show that IL-1beta induces ceramide formation and sphingomyelin degradation in porcine thyroid cells via the activation of a neutral sphingomyelinase. Among the potential targets of IL-1beta and ceramides action, we have investigated the role of an atypical protein kinase C (PKC), the PKC zeta. We show that both IL-1beta and ceramides lead to an increase of PKCzeta activity. All these results suggest an important role for ceramides and IL-1beta in regulation of thyroid function, leading to cell survival or to apoptosis.

Involvement of the ceramide signaling pathway in modulating the differentiated state of porcine thyroid cells.

Neutral sphingomyelinase (Smase) is a cell membrane-associated phospholipase that hydrolyzes sphingomyelin to phosphocholine and ceramide, a lipid second messenger involved in cell differentiation and/or apoptosis. We first evidenced that porcine cultured thyroid cells could express neutral Smase activity even if thyrotropin (TStH), an essential hormone in thyroid cell differentiation, was found to induce a 1.7-fold decrease in Smase activity. Triggering the ceramide pathway by exogenous addition of neutral bacterial Smase (0.1 U/mL for 48 h), which transiently increased ceramide level by fourfold, drastically modified thyroid cell morphology. The follicle-like structures generated by TSH were disrupted, and the Smase-induced cell spreading was accompanied by a parallel loss of cell ability to iodinate proteins as well as a decrease of the adenylate cyclase system response. These inhibitory effects have been reproduced using short-chain exogenous ceramide analogs (C2-ceramides). Overall these data showed that ceramides emerged as potential mediators of dedifferentiation in thyroid cells.

[Prevention of venous thromboembolism. Survey of in-hospital medical practice]. / Prévention de la maladie thromboembolique veineuse. Enquête sur les pratiques en milieu médical hospitalier.

OBJECTIVES: In an effort to improve the prevention of venous thromboembolism, the Nancy University Hospitals conducted a survey of medical practice concerning indications for preventive therapy and surveillance of platelet counts and anti Xa activity. METHODS: The survey involved 163 medical files. Questionnaires were filled out in 6 units (3 medical wards and 3 intensive care units). RESULTS: Indications for preventive therapy were found to be quite variable with the exception of very low risk of thromboembolism where the treat/do not treat ratio was 0.1/1, indicating a clear tendency for abstention. This ratio was 0.77/1 and 0.38/1 respectively for low and moderate risk and 2/1 for high risk. There was undoubtedly a ward effect. The attitudes in practice tended toward non-prevention in patients without limited mobility. For platelet counts, an initial count was performed in 95% of the cases and during treatment in 38% although the specific rates were not the same for different types of units. Anti-Xa activity, which according to prevention recommendations need not to be determined, was not monitored in 88% of the cases. In accordance with prevention recommendations, anti-Xa activity was not determined in 88% of the cases. CONCLUSION: Further progress is needed in the prevention of venous thromboembolism and should be based on wider use of existing methods.