Reversed size-dependent stabilization of ordered nanophases.

The size increase of a nanoscale material is commonly associated with the increased stability of its ordered phases. Here we give a counterexample to this trend by considering the formation of the defect-free L11 ordered phase in AgPt nanoparticles, and showing that it is better stabilized in small nanoparticles (up to 2.5 nm) than in larger ones, in which the ordered phase breaks in multiple domains or is interrupted by faults. The driving force for the L11 phase formation in small nanoparticles is the segregation of a monolayer silver shell (an Ag-skin) which prevents the element with higher surface energy (Pt) from occupying surface sites. With increasing particle size, the Ag-skin causes internal stress in the L11 domains which cannot thus exceed the critical size of ~2.5 nm. A multiscale modelling approach using full-DFT global optimization calculations and atomistic modelling is used to interpret the findings.

Pd surface and Pt subsurface segregation in Pt1-c Pd c nanoalloys.

The structure and chemical arrangement of Pt1-c Pd c nanoalloys with the icosahedral and face centered cubic symmetry are studied using Monte Carlo simulations with a tight binding interatomic potential fitted to density-functional theory calculations. Pd surface segregation from the lowest to the highest coordinated sites is predicted by the theory together with a Pt enrichment at the subsurface, whatever the structure and the size of the nanoparticles, and which subsists when increasing the temperature. The onion-shell chemical configuration is found for both symmetries and is initiated from the Pd surface segregation. It is amplified in the icosahedral symmetry and small sizes but when considering larger sizes, the oscillating segregation profile occurs near the surface on about three to four shells whatever the structure. Pd segregation results from the significant lower cohesive energy of Pd as compared to Pt and the weak ordering tendency leads to the Pt subsurface segregation. The very weak size mismatch does not prevent the bigger atoms (Pt) from occupying subsurface sites which are in compression whereas the smaller ones (Pd) occupy the central site of the icosahedra where the compression is an order of magnitude higher.

Systematic analysis of factors associated with progression and regression of ulcerative colitis in 918 patients.

BACKGROUND: Studies that systematically assess change in ulcerative colitis (UC) extent over time in adult patients are scarce. AIM: To assess changes in disease extent over time and to evaluate clinical parameters associated with this change. METHODS: Data from the Swiss IBD cohort study were analysed. We used logistic regression modelling to identify factors associated with a change in disease extent. RESULTS: A total of 918 UC patients (45.3% females) were included. At diagnosis, UC patients presented with the following disease extent: proctitis [199 patients (21.7%)], left-sided colitis [338 patients (36.8%)] and extensive colitis/pancolitis [381 (41.5%)]. During a median disease duration of 9 [4-16] years, progression and regression was documented in 145 patients (15.8%) and 149 patients (16.2%) respectively. In addition, 624 patients (68.0%) had a stable disease extent. The following factors were identified to be associated with disease progression: treatment with systemic glucocorticoids [odds ratio (OR) 1.704, P = 0.025] and calcineurin inhibitors (OR: 2.716, P = 0.005). No specific factors were found to be associated with disease regression. CONCLUSIONS: Over a median disease duration of 9 [4-16] years, about two-thirds of UC patients maintained the initial disease extent; the remaining one-third had experienced either progression or regression of the disease extent.

The gap between scientific evidence and clinical practice: 5-aminosalicylates are frequently used for the treatment of Crohn's disease.

BACKGROUND: There is uncertain evidence of effectiveness of 5-aminosalicylates (5-ASA) to induce and maintain response and remission of active Crohn's disease (CD), and weak evidence to support their use in post-operative CD. AIM: To assess the frequency and determinants of 5-ASA use in CD patients and to evaluate the physicians' perception of clinical response and side effects to 5-ASA. METHODS: Data from the Swiss Inflammatory Bowel Disease Cohort, which collects data since 2006 on a large sample of IBD patients, were analysed. Information from questionnaires regarding utilisation of treatments and perception of response to 5-ASA were evaluated. Logistic regression modelling was performed to identify factors associated with 5-ASA use. RESULTS: Of 1420 CD patients, 835 (59%) were ever treated with 5-ASA from diagnosis to latest follow-up. Disease duration >10 years and colonic location were both significantly associated with 5-ASA use. 5-ASA treatment was judged to be successful in 46% (378/825) of treatment episodes (physician global assessment). Side effects prompting stop of therapy were found in 12% (98/825) episodes in which 5-ASA had been stopped. CONCLUSIONS: 5-Aminosalicylates were frequently prescribed in patients with Crohn's disease in the Swiss IBD cohort. This observation stands in contrast to the scientific evidence demonstrating a very limited role of 5-ASA compounds in the treatment of Crohn's disease.

Topical therapy is underused in patients with ulcerative colitis.

The availability of new topical preparations for the treatment of left sided ulcerative colitis offers a therapy optimization for many patients. Rectal application of steroids and 5-aminosalicylic acid (5-ASA) is associated with fewer side effects and has a higher therapeutic efficacy in left-sided colitis as compared to a systemic therapy. Therefore, we were interested in the use of topical therapy in patients with ulcerative colitis. The key question was whether topical treatment is more frequently used than oral therapy in patients with proctitis and left sided colitis. Data of 800 patients of the Swiss IBD cohort study were analyzed. Sixteen percent of patients of the cohort had proctitis, 21% proctosigmoiditis and 41% pancolitis. Topical therapy with 5-ASA or corticosteroids was given in 26% of patients with proctitis, a combined systemic and topical treatment was given in 13%, whereas systemic treatment with 5-ASA without topical treatment was given in 29%. Proportion of topical drug use decreased with respect to disease extension from 39% for proctitis to 13.1% for pancolitis (P=0.001). Patients with severe colitis received a significantly higher dose of topical 5-ASA than patients in remission. Side effects of topical or systemic 5-ASA or budesonide treatment were less frequently seen compared to other medications. Topical treatment was frequently stopped over time. The quality of life was the same in patients with limited disease compared to patients with pancolitis. Topical treatment in proctitis patients was underused in Switzerland. Since topical treatment is safe and effective it should be used to a larger extend.

[Topical therapy of ulcerative colitis]. / Topische Therapie bei Colitis ulcerosa.

The availability of new topical preparations for the treatment of left sided ulcerative colitis ulcerosa offers a therapy optimization for many patients. Rectal application of steroids and 5-aminosalicylic acid (5-ASA) is associated with fewer side effects and has a higher therapeutic efficacy in mild to moderate-active left-sided colitis as compared to a systemic therapy. Often it is argued that the patients' compliance is insufficient with a rectal therapy. However, with sufficient information on the proven advantages this is usually not the case. The rectal application of drugs in distal ulcerative colitis is suitable also for the maintenance of remission. Therefore the new therapy guidelines recommend topical therapy more than in former times. Subsequently, these manuscripts focussed specifically on the topical therapy of distal colitis, to elucidate that clear treatment advantages are present in daily practice.

Evaluating resistance to Bt toxin Cry1Ab by F2 screen in European populations of Ostrinia nubilalis (Lepidoptera: Crambidae).

The large-scale cultivation of transgenic crops producing Bacillus thuringiensis (Bt) toxins have already lead to the evolution of Bt resistance in some pest populations targeted by these crops. We used the F2 screening method for further estimating the frequency of resistance alleles of the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), to Bt maize, Zea mays L., producing the Cry1Ab toxin. In France, Germany, and Italy, 784, 455, and 80 lines of European corn borer were screened for resistance to Mon810 maize, respectively. In Slovakia, 26 lines were screened for resistance to the Cry1Ab toxin. The cost of F2 screen performed in the four countries varied from U.S. dollars 300 to dollars 1300 per line screened. The major difference in cost was mostly due to a severe loss of univoltine lines during the screen in Germany and Slovakia. In none of the screened lines did we detect alleles conferring resistance to Mon810 maize or to the Cry1Ab toxin. The frequency of resistance alleles were < 1.0 x 10(-3), < 1.6 x 10(-3), < 9.2 x 10(-3), and < 2.6 x 10(-2) in France, Germany, Italy, and Slovakia, with 95% probability, respectively. The average detection probability over all lines was approximately 90%. Making the assumption that European corn borer populations in these countries belong to the same genetic entity, the frequency of alleles conferring resistance to the Cry1Ab produced by the Mon810 maize in western and central Europe was 1.0 x 10(-4), with a 95% confidence interval of 0-3.0 x 10(-4).

Appropriateness of therapy for fistulizing Crohn's disease: findings from a national inflammatory bowel disease cohort.

BACKGROUND: About 30-50% of patients with Crohn's disease (CD) develop fistulae, implying significant disease burden and complicated clinical management. AIM: To assess appropriate use of therapy for fistulizing CD patients enrolled in the Swiss Inflammatory Bowel Disease Cohort using criteria developed by the European Panel on the Appropriateness of Crohn's disease Therapy. METHODS: Specific questionnaires were used to gather information on disease and its management. We assessed appropriateness of therapy at enrolment for adult CD patients with one or several fistulae. RESULTS: Two hundred and eighty-eight CD patients had fistulizing disease, of which 80% had complex fistulae and 32% currently had active draining fistulae. Mean age (s.d.) at diagnosis was 27 years (11), 51% males. Of the patients, 78% were judged as having globally an appropriate therapy, which was more often given for complex fistulae (87%) than for simple fistulae (67%). Antibiotics, azathioprine/MP, methotrexate and conservative surgery were almost always appropriate. Anti-tumor necrosis factor α was considered globally appropriate (91%), although most often with an uncertain indication. The 5ASA compounds, steroids and aggressive surgery were most often inappropriate (84%, 58% and 86% respectively). CONCLUSIONS: Formal appropriateness criteria for CD therapy were applied to a national cohort of IBD patients. For more than three-quarters of the patients with fistulizing CD, therapy was globally appropriate.

[Inflammatory bowel disease: a "survival kit" for general practitioners]. / Les maladies inflarnmatoires chroniques de l'intestin: "survival kit" pour internistes et généralistes.

There are approximately 12000 patients suffering from inflammatory bowel disease (IBD) in Switzerland. IBD can be debilitating not only because of the direct consequences in the gut but also because of extraintestinal manifestations. An early diagnosis is the key in defining optimal therapeutic interventions. The management is multidisciplinary and the general practitioner should work in direct collaboration with a gastroenterologist. Optimal management should aim at inducing and maintaining remission as well as reducing the risk of complications such as abcesses, fistulas or colorectal cancer.

Size and shape effects on the order-disorder phase transition in CoPt nanoparticles.

Chemically ordered bimetallic nanoparticles are promising candidates for magnetic-storage applications. However, the use of sub-10 nm nanomagnets requires further study of possible size effects on their physical properties. Here, the effects of size and morphology on the order-disorder phase transition temperature of CoPt nanoparticles (T(C)(NP)) have been investigated experimentally, using transmission electron microscopy, and theoretically, with canonical Monte Carlo simulations. For 2.4-3-nm particles, T(C)(NP) is found to be 325-175 degrees C lower than the bulk material transition temperature, consistent with our Monte Carlo simulations. Furthermore, we establish that T(C)(NP) is also sensitive to the shape of the nanoparticles, because only one dimension of the particle (that is, in-plane size or thickness) smaller than 3 nm is sufficient to induce a considerable depression of T(C)(NP). This work emphasizes the necessity of taking into account the three-dimensional morphology of nano-objects to understand and control their structural properties.

[Main therapeutic advances in IBD in 2008]. / Maladies inflammatoires de l'intestin.

A coimmunosuppression with azathioprine or methotrexate in addition to infliximab does not improve the therapeutic efficacy in Crohn's disease but increase the risks of infectious complications and neoplasia.

Case report: human herpesvirus 6 reactivation associated with colitis in a lung transplant recipient.

Whereas human herpesvirus 6 (HHV-6) reactivation is frequent in solid organ transplant recipients, symptomatic disease is rare. A case of colitis associated with HHV-6B reactivation was observed in a lung transplant recipient. This case report suggests that symptomatic HHV-6 infection may occur in the absence of detectable viremia.

Controlling structure and morphology of CoPt nanoparticles through dynamical or static coalescence effects.

The structure and morphology of 1 to 3 nm size CoPt nanoparticles have been investigated in situ and in real time under different conditions: growth at 500 degrees C or at room temperature (RT) followed by annealing at 500 degrees C. The small-angle x-ray scattering measurements show size and temperature dependent growth mode with particle motions on the surface, while wide-angle scattering results, supported by Monte Carlo simulations, allow structure identification. If icosahedra are systematically detected at the first growth stages at RT, annealing at 500 degrees C yields the decahedral structure from the quasistatic coalescence of icosahedral morphology. Meanwhile, growth at 500 degrees C proceeds by a dynamical coalescence mechanism at the early stage, yielding truncated octahedral cubic structures.

Structure and chemical ordering in CoPt nanoalloys.

The structure and chemical ordering of CoPt nanoclusters in the size range of 1 to 3 nm are investigated by global optimization methods and Monte Carlo simulations using a many body potential derived from the tight binding model. For the smaller systems (number of atoms N < 100), the optimized clusters display a polyicosahedral-like atomic structure with a little core-shell chemical ordering characterized by a particular surface chemical configuration: some pentagonal or hexagonal Pt rings centered, respectively on a Co atom or a Co dimer. A transition to the decahedral symmetry occurs at about N = 100 atoms, with a pseudo L1(0) ordered phase in each tetrahedral unit. For larger cluster sizes, 201 < N < 1289, the L1(0)-ordered/disordered transition on the face centered cubic truncated octahedron is studied by canonical Monte Carlo simulations showing that the critical disordering temperature decreases with the cluster size. We also notice a Co surface segregation especially at edges and, possibly, (100) facets, depending on the cluster size, on both cubic and fivefold symmetry structures.

Appropriate treatment for Crohn's disease: methodology and summary results of a multidisciplinary international expert panel approach--EPACT.

BACKGROUND/AIMS: For many therapeutic decisions in Crohn's disease (CD), high-grade evidence is lacking. To assist clinical decision-making, explicit panel-based appropriateness criteria were developed by an international, multidisciplinary expert panel. METHODS: 10 gastroenterologists, 3 surgeons and 2 general practitioners from 12 European countries assessed the appropriateness of therapy for CD using the RAND Appropriateness Method. Their assessment was based on the study of a recent literature review of the subject, combined with their own expert clinical judgment. Panelists rated clinical indications and treatment options using a 9-point scale (1 = extremely inappropriate; 9 = extremely appropriate). These scenarios were then discussed in detail at the panel meeting and re-rated. Median ratings and disagreement were used to aggregate ratings into three assessment categories: appropriate (A), uncertain (U) and inappropriate (I). RESULTS: 569 specific indications were rated, dealing with 9 clinical presentations: mild/moderate luminal CD (n = 104), severe CD (n = 126), steroid-dependent CD (n = 25), steroid-refractory CD (n = 37), fistulizing CD (n = 49), fibrostenotic CD (n = 35), maintenance of medical remission of CD (n = 84), maintenance of surgical remission (n = 78), drug safety in pregnancy (n = 24) and use of infliximab (n = 7). Overall, 146 indications (26%) were judged appropriate, 129 (23%) uncertain and 294 (52%) inappropriate. Frank disagreement was low (14% overall) with the greatest disagreement (54% of scenarios) being observed for treatment of steroid-refractory disease. CONCLUSIONS: Detailed explicit appropriateness criteria for the appropriate use of therapy for CD were developed for the first time by a European expert panel. Disease location, severity and previous treatments were the main factors taken into account. User-friendly access to EPACT criteria is available via an Internet site, www.epact.ch, allowing prospective evaluation and improvement of appropriateness of current CD therapy.

Global optimization study of small (10 < or = N < or = 120) Pd clusters supported on MgO(100).

Experimental evidence suggests that Pd clusters on MgO, known to be good reaction catalysts, have face centered cubic (fcc) epitaxial structures. The structure of such clusters is the result of the interplay of Pd-Pd and Pd-substrate bonds, the former inclined to favor icosahedral (Ih) and decahedral (Dh)-like structures, the latter leading to place Pd atoms on top of oxygen sites, according to an epitaxial stacking. This paper shows the results of a basin-hopping global optimization procedure applied to free and MgO-supported Pd clusters in the size range 10 < or = N < or = 120. Pd-MgO interactions are modeled by an analytical function fitted to ab initio results, while Pd-Pd interactions are modeled by a semiempirical potential. Besides the tight-binding Rosato-Guillopé-Legrand (RGL) potential, we have adopted a modified version of RGL that better reproduces the experimental surface energy of palladium, modifying the attractive part of Pd atoms potential energy. We have compared the two potential models, and as a result, the RGL potential favors clusters with epitaxial arrangements, so that cluster structures are epitaxial fcc in almost all the size ranges considered. On the contrary, the alternative potential model preserves some Ih-like characteristics typical of the free Pd clusters, and it suggests that a transition size from Ih-like to epitaxial structures can take place at about 100 atoms.

[Inflammatory diseases of the intestines]. / Maladies inflammatoires de l'intestin.

5-aminosalicylates preparations are not superior to placebo for the maintenance of medically-induced remission in patients with Crohn's disease. We have to reconsider the potential risks associated with inhibition of lymphocyte trafficking since it can induce serious and potentially lethal infections. Infliximab has shown efficacy in active ulcerative colitis.

Self-organized growth of nanoparticles on a surface patterned by a buried dislocation network.

The self-organized growth of Co nanoparticles is achieved at room temperature on an inhomogenously strained Ag(001) surface arising from an underlying square misfit dislocation network of 10 nm periodicity buried at the interface between a 5 nm-thick Ag film and a MgO(001) substrate. This is revealed by in situ grazing-incidence small-angle x-ray scattering. Simulations of the data performed in the distorted wave Born approximation framework demonstrate that the Co clusters grow above the dislocation crossing lines. This is confirmed by molecular dynamic simulations indicating preferential Co adsorption on tensile sites.

Single impurity effect on the melting of nanoclusters.

We show by molecular dynamics simulations that the melting temperature of clusters can be tuned by selective doping. In fact, a single Ni or Cu impurity in Ag icosahedral clusters considerably increases the melting temperature even for sizes of more than a hundred atoms. The upward shift is correlated to the strain relaxation induced by a small central impurity in icosahedral clusters.

[Infectious diarrhea]. / Diarrhées infectieuses.

Traveler's diarrhea is generally a benign condition which resolves spontaneously in 48 h. Information on dietary hygiene, severity of symptoms and dehydration, as well as their management, is essential. Chemoprophylaxis and antibiotic treatment are not recommended, except in very specific situations. The incidence of chronic diarrhea in HIV-positive patients has dramatically decreased since the introduction of HAART. In the absence of any correlation with the initiation of HAART, a stepwise diagnostic workup is indicated (bacteriological cultures and microscopic examination of fecal samples followed by ileocolonoscopy and gastroduodenoscopy). Specific treatment of any pathogens identified, and HAART in the case of microsporidiasis or cryptosporidiosis, constitute the mainstay of therapeutic management of chronic diarrhea in these patients.