X-Ray Absorption Spectroscopy and Computer Modelling Study of Nanocrystalline Binary Alkaline Earth Fluorides

Nanocrystalline samples of Ba1-xCaxF2 prepared by high-energy milling show an unusually high F-ion conductivity, which exhibit a maximum in the magnitude and a minimum in the activation energy at x = 0.5. Here, we report an X-ray absorption spectroscopy (XAS) at the Ca and Sr K edges and the Ba L-3 edge and a molecular dynamics (MD) simulation study of the pure and mixed fluorides. The XAS measurements on the pure binary fluorides, CaF2, SrF2 and BaF2 show that high-energy ball-milling produces very little amorphous material, in contrast to the results for ball milled oxides. XAS measurements of Ba1-xCaxF2 reveal that for 0 < x < 1 there is considerable disorder in the local environments of the cations which is highest for x = 0.5. Hence the maximum in the conductivity corresponds to the composition with the maximum level of local disorder. The MD calculations also show a highly disordered structure consistent with the XAS results and similarly showing maximum disorder at x = 0.5.

High alkaline phosphatase activity in phosphate replete waters: The case of two macrotidal estuaries

The occurrence of alkaline phosphatase activity (APA) that hydrolyses organic phosphorus into phosphate (PO4) is commonly related to PO4 deficiency of oceanic, coastal and fresh waters. APA is almost never investigated in PO4-rich estuaries, since very low activities are expected to occur. As a consequence, microbial mineralization of organic phosphorus into PO4 has often been ignored in estuaries. In this study, we examined the importance of potential APA and the associated microbial dynamics in two estuaries, the Aulne and the Elorn (Northwestern France), presenting two different levels of PO4 concentrations. Unexpected high potential APA was observed in both estuaries. Values ranged from 50 to 506 nmol L−1 h−1, which range is usually found in very phosphorus-limited environments. High potential APA values were observed in the oligohaline zone (salinity 5–15) in spring and summer, corresponding to a PO4 peak and a maximum bacterial production of particle-attached bacteria. In all cases, high potential APA was associated with high suspended particulate matter and total particulate phosphorus. The low contribution of the 0.2–1 μm fraction to total APA, the strong correlation between particulate APA and bacterial biomass, and the close relationship between the production of particle-attached bacteria and APA, suggested that high potential APA is mainly due to particle-attached bacteria. These results suggest that the microbial mineralization of organic phosphorus may contribute to an estuarine PO4 production in spring and summer besides physicochemical processes.

Leishmania (Viannia) shawi purified antigens confer protection against murine cutaneous leishmaniasis

Leishmania (Viannia) shawi was characterized only recently, and few studies concerning the immunogenic and protective properties of its antigens have been performed. The present study aimed to evaluate the protective potential of the five antigenic fractions isolated from L. (V.) shawi promastigotes in experimental cutaneous leishmaniasis.Soluble antigen from L. (V.) shawi promastigotes was submitted to reverse phase HPLC to purify F1, F2, F3, F4 and F5 antigens. BALB/c mice were immunized once a week for two consecutive weeks by subcutaneous routes in the rump, using 25 mu g protein. After 1 week, groups were challenged in the footpad with L. (V.) shawi promastigotes. After 8 weeks, those same mice were sacrificed and parasite burden as well as the cellular and humoral immune responses were evaluated.F1 and F5-immunized mice restrained lesion progression and parasite load in the skin. However, only the F1 group was able to control the parasitism in lymph nodes, which was associated with low IL-4 and high IFN-gamma production; IgG2a isotype was increased in this group. Immunizations with F2, F3 and F4 antigens did not protect mice.The capability of antigens to restrain IL-4 levels and increase IFN-gamma was associated with protection, such as in immunization using F1 antigen.

Cord Blood Alkaline Phosphatase as an Indicator of Neonatal Jaundice

Background: Management of hyperbilirubinemia remains a challenge for neonatal medicine because of the risk of neurological complications related to the toxicity of severe hyperbilirubinemia. Objectives: The purpose of this study was to examine the validity of cord blood alkaline phosphatase level for predicting neonatal hyperbilirubinemia. Patients and Methods: Between October and December 2013 a total of 102 healthy term infants born to healthy mothers were studied. Cord blood samples were collected for measurement of alkaline Phosphatase levels immediately after birth. Neonates were followed-up for the emergence of jaundice. Newborns with clinical jaundice were recalled and serum bilirubin levels measured. Appropriate treatment based on serum bilirubin level was performed. Alkaline phosphatase levels between the non-jaundiced and jaundiced treated neonates were compared. Results: The incidence of severe jaundice that required treatment among followed-up neonates was 9.8%. The mean alkaline phosphatase level was 309.09 ± 82.51 IU/L in the non-jaundiced group and 367.80 ± 73.82 IU/L in the severely jaundiced group (P = 0.040). The cutoff value of 314 IU/L was associated with sensitivity 80% and specificity 63% for predicting neonatal hyperbilirubinemia requiring treatment. Conclusions: The cord blood alkaline phosphatase level can be used as a predictor of severe neonatal jaundice.

Development of an antigen-driven colitis model to study presentation of antigens by antigen presenting cells to T cells

Inflammatory bowel disease (IBD) is a chronic inflammation which affects the gastrointestinal tract (GIT). One of the best ways to study the immunological mechanisms involved during the disease is the T cell transfer model of colitis. In this model, immunodeficient mice (RAG-/-recipients) are reconstituted with naive CD4+ T cells from healthy wild type hosts. This model allows examination of the earliest immunological events leading to disease and chronic inflammation, when the gut inflammation perpetuates but does not depend on a defined antigen. To study the potential role of antigen presenting cells (APCs) in the disease process, it is helpful to have an antigen-driven disease model, in which a defined commensal-derived antigen leads to colitis. An antigen driven-colitis model has hence been developed. In this model OT-II CD4+ T cells, that can recognize only specific epitopes in the OVA protein, are transferred into RAG-/- hosts challenged with CFP-OVA-expressing E. coli. This model allows the examination of interactions between APCs and T cells in the lamina propria.