Sigma-phase in Fe-Cr and Fe-V alloy systems and its physical properties

A review is presented on physical properties of the sigma-phase in Fe-Cr and Fe-V alloy systems as revealed both with experimental -- mostly with the Mossbauer spectroscopy -- and theoretical methods. In particular, the following questions relevant to the issue have been addressed: identification of sigma and determination of its structural properties, kinetics of alpha-to-sigma and sigma-to-alpha phase transformations, Debye temperature and Fe-partial phonon density of states, Curie temperature and magnetization, hyperfine fields, isomer shifts and electric field gradients.Comment: 26 pages, 23 figures and 83 reference

A trematode parasite derived growth factor binds and exerts influences on host immune functions via host cytokine receptor complexes

The trematode Fasciola hepatica is responsible for chronic zoonotic infection globally. Despite causing a potent T-helper 2 response, it is believed that potent immunomodulation is responsible for rendering this host reactive non-protective host response thereby allow- ing the parasite to remain long-lived. We have previously identified a growth factor, FhTLM, belonging to the TGF superfamily can have developmental effects on the parasite. Herein we demonstrate that FhTLM can exert influence over host immune functions in a host receptor specific fashion. FhTLM can bind to receptor members of the Transforming Growth Factor (TGF) superfamily, with a greater affinity for TGF-β RII. Upon ligation FhTLM initiates the Smad2/3 pathway resulting in phenotypic changes in both fibroblasts and macrophages. The formation of fibroblast CFUs is reduced when cells are cultured with FhTLM, as a result of TGF-β RI kinase activity. In parallel the wound closure response of fibroblasts is also delayed in the presence of FhTLM. When stimulated with FhTLM blood monocyte derived macrophages adopt an alternative or regulatory phenotype. They express high levels interleukin (IL)-10 and arginase-1 while displaying low levels of IL-12 and nitric oxide. Moreover they also undergo significant upregulation of the inhibitory recep- tor PD-L1 and the mannose receptor. Use of RNAi demonstrates that this effect is depen- dent on TGF-β RII and mRNA knock-down leads to a loss of IL-10 and PD-L1. Finally, we demonstrate that FhTLM aids newly excysted juveniles (NEJs) in their evasion of antibody- dependent cell cytotoxicity (ADCC) by reducing the NO response of macrophages—again dependent on TGF-β RI kinase. FhTLM displays restricted expression to the F. hepatica gut resident NEJ stages. The altered fibroblast responses would suggest a role for damp- ened tissue repair responses in facilitating parasite migration. Furthermore, the adoption of a regulatory macrophage phenotype would allow for a reduced effector response targetingjuvenile parasites which we demonstrate extends to an abrogation of the ADCC response. Thus suggesting that FhTLM is a stage specific evasion molecule that utilises host cytokine receptors. These findings are the first to clearly demonstrate the interaction of a helminth cytokine with a host receptor complex resulting in immune modifications that facilitate the non-protective chronic immune response which is characteristic of F. hepatica infection

Spin and lattice dynamics of La2/3Ca1/3MnO3 doped with 1% 119Sn

1 at.% 119Sn doped La0.67Ca0.33MnO3 compound was studied by Mössbauer spectroscopy, magnetization, AC susceptibility and resistivity measurements. Huge separation (66 K) of the transition temperatures from the ferromagnetic (FM) to paramagnetic (PM) state (TC) and from metallic to insulating state (TM-I) clearly shows that transition from FM metallic to PM insulator phase goes via FM insulator phase. The Mn lattice dynamics was studied by the relative changes of Lamb-Mössbauer factor f as a function of temperature. In the Debye approximation from the calculated ln(f/f0) values of the characteristic Debye temperatures (čD) were estimated for the FM (368(10) K) and PM (391(6) K) phases. No anomaly of -ln(f/f0) at TM-I and its rather spurious increase around TC was found. The 119Sn isotope as a local diamagnetic probe samples the transferred hyperfine field (Bhf) from its neighbour Mn magnetic moments and witnesses the dynamics of the Mn moments. Theoretical curve based on the molecular field theory was fitted to the experimental values of Bm hf ax and the value of the ordering temperature (TC * H 280 K) of Mn moments inside the large FM domains was estimated. It is much higher than the TC (172 K) obtained from magnetization measurement. The coexistence of FM and PM phases, which is evident from the shape of our 119Sn Mössbauer spectra, was confirmed for temperatures T e 150 K and indicates the inhomogeneous character of the magnetic transition

FhTLM induces a part alternative part regulatory macrophage phenotype.

<p>FhTLM (200ng/mL) was used to stimulate the bovine macrophages derived from blood monocytes. Thereafter levels of (A) nitric oxide (NO) levels, (B) arginase-1 levels, (C) IL-10, and (D) IL-12 in matched samples. Data in A-D is collected from the same experiment. In separate experiments using the same donors mannose receptor expression was also determined using immunofluorescence (E) and (F) increases in PD-L1 mRNA expression levels were quantified. Data represents means +/- SEM of triplicate measurments and experiments were repeated three times with similar results. Results were analysed using a 1-way Anova and statistical significant differences are indicated on the graphs; *P<0.05, **P<0.01.</p

FhTLM binds to and initiates mammalian host signalling pathways.

<p>(A) FhTLM was used to stimulate the TGF-β responsive cell line at the indicated doses. Relative light units (RLU) were converted to equivalent TGF-B concentration by comparison with a TGF-β standard curve. (B) This activity was inhibited by polyclonal serum raised against TGF-β. Plate-bound FhTLM was detected using the recombinant fusion proteins (C) bovine TGF-B R1-Fc and (D) bovine TGF-B RII-Fc. Results are reported as optical densities (OD) at 450nm. (E) Avidity of receptor-FhTLM interactions were measured using KSCN and presented as OD as a function of increasing KSCN molarity. (F) and (G) FhTLM and TGF-β, respectively, were used to coat ELISA plates (400ng/mL) overnight. Thereafter TGF-β1 and FhTLM were used in increasing concentrations shown to block the interaction of TGF-βRI-Fc or TGF-βRII-Fc. Data presented are means +/- SD of triplicates, experiments were repeated three times with similar results.</p

FhTLM can initiate transcription factor activation in primary host leukocytes.

<p>Naïve bovine PBMCs were incubated with FhTLM (200ng/mL) and subsequently prepared for immunoflouresence (A) to detect (B) Smad2/3 and (C) GATA1. (A) The upper row are cells stained with DAPI, middle row with anti-Smad2/3-FITC, and bottom row iIn both panels, the columns represent (from left to right) unstimulated PBMCs, TGF-β1 stimulated PBMCs, and FhTLM stimulated PBMCs. Following staining cytospins were examined at 40X magnification and the number of positive cells (i.e. FITC overlaid on DAPI) were calculated. This analysis was conducted over time for Smad2/3 (B) and at 3hrs for GATA1 (C). Data presented are means +/- SEM of triplicates, experiments were repeated three times with similar results. Results were analysed using a 1-way Anova and statistical significant differences are indicated on the graphs, *P<0.05 or **P<0.01.</p

FhTLM reduces the capacity of macrophages to kill juvenile F. hepatica by ADCC.

<p>Macrophages were cultured from naïve donors as described in the presence of FhTLM or TGF-β for 24hrs. Following this macrophages were incubated with newly excysted juveniles (NEJs) in the presence of serum taken from naïve (non-immune) or experimentally infected, 13 weeks post-infection, animals (immune). After 6hr of incubation dead parasites were counted (A) and levels of NO in the supernatant determined (B). Experiments were repeated to test the effect of TGF-β RI ALK inhibitor, SB431542 (5μM),on macrophages before incubation with NEJs and serum and measurement of parasite killing (C) and NO levels (D). Data in (A) and (B) were tested for statistical significance using a 2-way anova to determine effect of non-immune vs immune sera and between PBS, FhTLM, and TGF-β macrophage treatment. Data in (C) and (D) were tested using 1-way Anova to determine the effect of inhibitor on TGF-β or FhTLM. **P<0.01 and ***P<0.001. Data displayed is mean +/- SEM and is representative of experiments conducted with 5 individual naïve macrophage donors, using 5 technical replicates per animal.</p

FhTLM changes fibroblast responses.

<p>FhTLM was included as an additive in fibroblast CFU cultures (A) or in wound repair assays (C). (A) 3T3 fibroblasts were seeded at 6 cells/well in 6 well plates with the indicated additives. Cultures were incubated for 10 days, stained with crystal violet and CFUs were counted. (B) Cultures as above were established but with the addition of the specific TGF-β RI activin receptor-like kinase (ALK) inhibitor SB431542 (5μM). (C) 3T3 fibroblasts were seeded in 6 wells plates and grown to 80% confluence. Horizontal wounds were introduced and wells imaged at T0 and again at T24. TGF-β or FhTLM were included post-wounding at the indicated concentrations. Images were blinded and % wound closure was calculated as area of well visible at T24 relative to T0. (D) Cell lysates were collected from (C) and arginase levels were determined by enzyme assay and reported as mU/10⁶ cells. For A, B and C data represents means +/- SEM of 4–6 measurements and experiments twice were repeated with similar results. Data in D represent combined data from (C) with N = 8–12 measurements +/- SEM per treatment. Results were analysed using a 1-way Anova and statistical significant differences are indicated on the graphs, P **P<0.01.</p