The Electron-Screening Correction for the Proton-Proton Reaction

We test the Salpeter formalism for the electron screening of the solar proton-proton fusion reaction by solving numerically the relevant Schrodinger equation. We evaluate exactly the square of the overlap integral of the two-proton wave function and the deuteron wave function and compare with the usual analytic approximation. The usual WKB solution agrees with the numerical result to $O(10^{-4})$. The WKB approximation should be even more precise for the other nuclear fusion reactions in the $pp$ chain and CNO cycles.Comment: 8 pages, RevTeX, some modifications and extensions, to appear in Phys. Rev.

Hormones and immunity to parasitic apicomplexans

Several studies revealed a close functional relations between the immune, nervous and endocrine systems which communicate between each other using the common mediators and their receptors. The immune cells not only receive signals from the endocrine system but also produce numerous hormones, usually after stimulation with antigens including parasites antigens. On the other hand, parasites are able to exploit hormonal microenvironment within the host to establish an infection and avoid the eradication by evolving receptors for host hormones. Some parasites produce also steroid hormones and alter host hormones levels. Increasing numbers of prophylaxis and therapy procedures involve hormones as main or supplementary components (e.g., estrogens, dexamethasone or insulin). The aim of this paper is to present new literature data concerning the immunomodulatory effect of selected hormones in infections caused by two parasitic apicomplexans: Toxoplasma gondii and Plasmodium spp. In addition to sex- and pregnancy- associated hormones which determine dimorphic immune responses in females versus males, the action of other hormones of great physiological importance will also be discussed

Prolactin as a modulator of antiparasitic immunity

Prolactin (PRL) is a polypeptide hormone of the pituitary origin, that expresses over 300 separate biological activities, including its involvement in the regulation of immune functions. The hormone's immune capacities are related, among others, to comitogenic activity, prevention of immune cell apoptosis, stimulation of interleukins and antibodies production. Prolactin acts as a potent positive modulator of immunity to some protozoan parasites. It is well established that the hormone stimulates IFN−g and many other TH1−type cytokines production during Toxoplasma gondii, Leishmania sp. and Acanthamoeba castellanii infections. Recent studies suggest that human prolactin may be a regulator of antiparasitic activity against Plasmodium falciparum. On the other hand pregnancy−associated hyperprolactinemia may have a relevant contribution to reactivation of latent infections caused by many helminthic parasites, like Ancylostoma sp. or Necator sp. It is possibly connected with the process of transmammary transmission of hookworm infection to breast−fed newborns. Moreover, an increase in endogenous circulating prolactin during late pregnancy and lactation in ewes infected with Haemonchus contortus, promotes the phenomenon of periparturient egg rise. High prolactin levels have also been seen in dairy cattle suffering from other trichostrongylids infections. In this article we have discussed the role of prolactin as an important regulator of immunity to parasites

The utility of MTT and XTT colorimetric test in the studies conducted in vitro with Toxoplasma gondii tachyzoites

Tetrazolium salts are widely used as indicators of metabolic activity for both eukaryotic and prokaryotic cells. Live cells reduce the tetrazole ring in MTT or XTT salts and then a colored formazane formed can be assessed spectrophotometrically. Despite widespread use of MTT/XTT reduction tests biochemical mechanisms of the reaction are still unknown, and each test application case requires standardization of experimental conditions. In the present study we tested in vitro the utility of both MTT and XTT salts to determine the influence of selected extracellular agents for T. gondii tachyzoites and their host cells (i.e. mouse L929 fibroblasts). The results showed that MTT is reduced more intensively than XTT by host and parasite cells. The attenuation of T. gondii tachyzoites resulted in a decrease of reduction level of both tetrazolium salts, particularly of XTT. Using MTT we found also that T. gondii is not susceptible to extremely toxic substance, sodium azide. Our results confirmed a high usefulness of MTT reduction tests in numerous studies on eukaryotic cells

The utility of MTT and XTT colorimetric test in the studies conducted in vitro with Toxoplasma gondii tachyzoites

Tetrazolium salts are widely used as indicators of metabolic activity for both eukaryotic and prokaryotic cells. Live cells reduce the tetrazole ring in MTT or XTT salts and then a colored formazane formed can be assessed spectrophotometrically. Despite widespread use of MTT/XTT reduction tests biochemical mechanisms of the reaction are still unknown, and each test application case requires standardization of experimental conditions. In the present study we tested in vitro the utility of both MTT and XTT salts to determine the influence of selected extracellular agents for T. gondii tachyzoites and their host cells (i.e. mouse L929 fibroblasts). The results showed that MTT is reduced more intensively than XTT by host and parasite cells. The attenuation of T. gondii tachyzoites resulted in a decrease of reduction level of both tetrazolium salts, particularly of XTT. Using MTT we found also that T. gondii is not susceptible to extremely toxic substance, sodium azide. Our results confirmed a high usefulness of MTT reduction tests in numerous studies on eukaryotic cells

Dysfunction of CD4+CD25high T regulatory cells in patients with recurrent aphthous stomatitis

Background: Recurrent aphthous stomatitis (RAS) is a chronic inflammatory disease of unknown etiology characterized by recurring formation of painful oral ulcers. RAS may result from oral epithelium damage caused by T-cell-mediated immune response. CD4+CD25+ T regulatory (Treg) cells suppress proliferation and effector functions of other immune cells, and therefore are crucial in regulating the immune response. Methods: We tested the function of peripheral CD4+CD25high Treg cells in active RAS through their ability to inhibit proliferation and cytokine production of conventional CD4+ T cells. We also attempted to detect the presence of FOXP3 and indoleamine 2,3-dioxygenase (IDO) mRNA in the lesional and non-lesional oral mucosa of RAS patients and healthy individuals using real-time PCR assay. Results: Treg cells derived from RAS patients were less efficient in the suppression of cytokine production of CD4+ T effector cells than Treg cells from healthy individuals. Moreover, in RAS, Treg cells were nearly twice less potent in the inhibition of CD4+CD25- T cell proliferation than in healthy donors. Furthermore, we have demonstrated the decreased proportion of CD4+CD25+FOXP3+ Treg cells in peripheral blood of RAS patients compared with controls. We failed to detect FOXP3 mRNA, while IDO mRNA expression was decreased in non-lesional mucosa biopsies from RAS patients compared with ulcer biopsies or normal mucosa from healthy donors. Conclusions: These findings suggest that CD4 +CD25high Treg cells are both functionally and quantitatively compromised in RAS and that decreased constitutive expression of IDO in oral mucosa in RAS may lead to the loss of local immune tolerance

Status and future developments of the Linear IFMIF Prototype Accelerator (LIPAc)

International audienceLIPAc is the Linear IFMIF Prototype Accelerator developed within the framework of the IFMIF project under the Broader Approach (BA) agreement signed between EURATOM and the Japanese Government in 2007. The IFMIF accelerator aims to provide an accelerator-based D-Li neutron source to produce high intensity neutron fluxes with appropriate energy spectrum in order to characterize materials envisioned for future fusion reactors. Because the IFMIF accelerator has to reach unprecedented performances, the feasibility is being tested through the design, manufacturing, installation, commissioning and testing activities of a 1:1-scale prototype accelerator, namely LIPAc, from the injector to the first cryomodule together with the High Energy Beam Transport line and the High Power Beam Dump. After outstanding results obtained in 2019, the LIPAc project has entered 2020 in the preparation of the third commissioning stage, i.e., validation in continuous-wave mode of the complete accelerator up to 5 MeV with its final beam dump. The validation until the nominal energy of 9 MeV will be made after the completion of cryomodule assembly. After a brief overview of the goals already achieved in the framework of the IFMIF/EVEDA program, this paper will present a synthesis of the results that have been obtained so far with the LIPAc accelerator as well as the future developments planned beyond 2020