Mean-field quantum phase transition in graphene and in general gapless systems

We study the quantum critical properties of antiferromagnetism in graphene at T=0 within mean-field (MF) theory. The resulting exponents differ from the conventional MF exponents, describing finite temperature transitions. Motivated by this, we have developed the MF theory of general gapless phases with density of states rho(E) |E|^r, r>-1, with the interaction as control parameter. For r>2, the conventional MF exponents \'a la Landau are recovered, while for -1<r<2, the exponents vary significantly with r. The critical interaction is finite for r>0, therefore no weak-coupling solution exists in this range. This generalizes the results on quantum criticality of the gapless Kondo systems to bulk correlated phases.Comment: 5 pages, 1 figure, 2 table

A pollenek által indukált oxidatív stressz hatása a humán dendritikus sejtek működésére = Effects of pollen-induced oxidative stress on human dendritic cell function

Eredményeink szerint a hidratálódott pollenszemek által termelt reaktív oxigéngyököknek fontos szerepe van az allergiás reakciók kialakulásának legelső szakaszában (azaz a szenzibilizálódásban). Ezek a rendkívül reakcióképes gyökök gyulladást elősegítő citokinek termelődését váltják ki a myeloid dendritikus sejtekből, ezzel hozzájárulnak a lokális veleszületett immunválaszok kialakulásához, valamint adjuváns faktorként segítik a pollen antigének elleni szerzett immunitás kialakulását is. Ezzel szemben az oxidative stressznek kitett plazmacitoid dendritikus sejteknek inkább gyulladást gátló, vagy tolerogén hatása van az adaptív immunválaszok szabályozásában. Eredményeink arra is utalnak, hogy a pollenek által kiváltott oxidative stress megelőzésének, vagy csökkentésének a légutakban jótékony hatása lehet az allergiás tünetek kezelésében. | Based on our results reactive oxygen species generated by hydrated pollen grains have an important role in the initial phase of the development of allergic reactions (it is called sensitization). These highly reactive radicals trigger pro-inflammatory cytokine production from myeloid DCs contributing to local innate immunity and also act as an adjuvant factor in the initiation of adaptive immune responses against pollen antigens. In contrast, plasmacytoid dendritic cells exposed to oxidative stress have an anti-inflammatory or tolerogenic role in regulating adaptive immune responses. Our data also imply that prevention or reduction of pollen-induced oxidative damage in the airways may have a beneficial role in therapy of allergic symptoms

Cianobakteriális tömegprodukciók toxintartalmának vizsgálata magyarországi vízterekben és a környezeti faktorok cianotoxintermelés-szabályozó hatásának fiziológiai és bioanalitikai vizsgálata izolált cianobaktérium törzseken. = The investigation of the toxin content of cyanobacterial mass production in Hungarian water bodies. Physiological and bioanalytical measurement of the effect of environmental factors on toxin production in isolated cyanobacterial strains.

A magyarországi vízvirágzások, algák és cianobaktériumok okozta tömegprodukciók toxicitásának feltérképezése során megvizsgáltuk milyen planktonikus fajok okoznak tömegprodukciót és milyen toxinok megjelenése jellemző a magyarországi vízterekre. A magyarországi vízterekben elsősorban a cianobaktériumok idéznek elő vízvirágzást és a toxikus tömegprodukciók során a mikrocisztin variánsok megjelenésére lehet a legnagyobb valószínűséggel számítani. Célunk volt továbbá olyan módszerek kidolgozása, amelyek a leggyakoribb cianobakteriális toxinok nyomonkövetését, termelésének tanulmányozását lehetővé teszik valós biológiai mátrixokból. A téma kapcsán a legnagyobb kihívást jelentette, hogy a leggyakoribb cianotoxinok analízisére egy adott módszer nem létezett, amivel egyidőben (szimultán) lehet különböző kémiai karakterű cianotoxinokat detektálni. Az általunk elsőként kidolgozott kapilláris elektroforézises módszer a fent említett problémát oldotta meg. A cianobakteriális toxintermelés laboratóriumi vizsgálata során, a cilindrospermopszin-termelést vizsgáltuk kén-, foszfor-, illetve nitrogénéhezés körülményei között, az intracelluláris toxinkoncentrációk tanulmányozásával a vegetatívsejtekben és a heterocisztában. A tápelem-éhezéses kísérleteink során a növekedési rátától független toxintartalmat mértünk a cilindrospermopszin-termelő Aphanizomenon ovalisporum szervezetben. | Mass developments of algae and cyanobacteria mainly caused by eutrophication of aquatic ecosystems both in fresh water and in marine environments are a worldwide problem. Besides the ecologically important suppression of other cyanobacterial blooms hold a high risk for human and animal health due to the ability of several species to produce potent toxins. The cyanobacterial and algal toxins are a diverse group of natural toxins, both from the chemical and the toxicological points of view. The present research project focuses on occurrences and importance of mass production of toxic algae and cyanobacteria and their toxins in domestic waters using our developed analytical methods. In addition, we focus mainly on the alteration of cyanotoxin-production under different environmental conditions

Regulatory NLRs Control the RLR-Mediated Type I Interferon and Inflammatory Responses in Human Dendritic Cells

L

Ragweed pollen extract intensifies lipopolysaccharide-induced priming of NLRP3 inflammasome in human macrophages

Ragweed pollen extract (RWE) possesses intrinsic NADPH oxidase activity that induces oxidative stress by initiating the production of intracellular reactive oxygen species (ROS). The ROS are important contributors to the manifestation of allergic inflammation; furthermore, concomitant exposure to an allergen and an endotoxin trigger a stronger inflammatory response. One of the main pro-inflammatory cytokines produced in inflammatory responses is interleukin-1β (IL-1β), and its production is associated with caspase-1-containing inflammasome complexes. Intracellular ROS have been implicated in NLRP3 inflammasome-mediated IL-1β production, therefore, we aimed to study whether RWE influences the function of NLRP3 inflammasome. Here we describe that, in the presence of NADPH, RWE significantly elevates lipopolysaccharide-induced IL-1β production of THP-1 cells as well as human primary macrophages and dendritic cells. We also demonstrate that increased IL-1β production is mediated through NLRP3 inflammasome in THP-1 macrophages. We provide evidence that RWE elevates cytosolic ROS level in these cells, and ROS inhibitors abolish IL-1β production. Furthermore, we show that RWE enhances lipopolysaccharide-induced gene transcription/expression of pro-IL-1β and key components of the inflammasome via a ROS-dependent mechanism

Regulation of type I interferon responses by mitochondria-derived reactive oxygen species in plasmacytoid dendritic cells

Mitochondrial reactive oxygen species (mtROS) generated continuously under physiological conditions have recently emerged as critical players in the regulation of immune signaling pathways. In this study we have investigated the regulation of antiviral signaling by increased mtROS production in plasmacytoid dendritic cells (pDCs), which, as major producers of type I interferons (IFN), are the key coordinators of antiviral immunity. The early phase of type I IFN production in pDCs is mediated by endosomal Toll-like receptors (TLRs), whereas the late phase of IFN response can also be triggered by cytosolic retinoic acid-inducible gene-I (RIG-I), expression of which is induced upon TLR stimulation. Therefore, pDCs provide an ideal model to study the impact of elevated mtROS on the antiviral signaling pathways initiated by receptors with distinct subcellular localization. We found that elevated level of mtROS alone did not change the phenotype and the baseline cytokine profile of resting pDCs. Nevertheless increased mtROS levels in pDCs lowered the TLR9-induced secretion of pro-inflammatory mediators slightly, whereas reduced type I IFN production markedly via blocking phosphorylation of interferon regulatory factor 7 (IRF7), the key transcription factor of the TLR9 signaling pathway. The TLR9-induced expression of RIG-I in pDCs was also negatively regulated by enhanced mtROS production. On the contrary, elevated mtROS significantly augmented the RIG-I-stimulated expression of type I IFNs, as well as the expression of mitochondrial antiviral-signaling (MAVS) protein and the phosphorylation of Akt and IRF3 that are essential components of RIG-I signaling. Collectively, our data suggest that increased mtROS exert diverse immunoregulatory functions in pDCs both in the early and late phase of type I IFN responses depending on which type of viral sensing pathway is stimulated