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Candida albicans belongs to our commensal mucosal flora and in immune-competent individuals in the absence of epithelial damage, this fungus is well tolerated and controlled by our immune defense. However, C. albicans is an opportunistic microorganism that can cause different forms of infections, ranging from superficial to life-threatening systemic infections. C. albicans is polymorphic and switches between different phenotypes (e.g. from yeast form to hyphal form). C. albicans hyphae are invasive and can grow into tissues to eventually reach circulation. During fungal infections, neutrophils in particular play a critical role for the defense, but how neutrophils are directed toward the invasive forms of fungi is less well understood. We set out to investigate possible neutrophil chemoattractants released by C. albicans into culture supernatants. We found that cell-free culture supernatants from the hyphal form of C. albicans induced both neutrophil chemotaxis and concomitant intracellular calcium transients. Size separation and hydrophobic sorting of supernatants indicated small hydrophilic factors as responsible for the activity. Further analysis showed that the culture supernatants contained high levels of short-chain fatty acids with higher levels from hyphae as compared to yeast. Short-chain fatty acids are known neutrophil chemoattractants acting via the neutrophil free fatty acid receptor 2. In line with this, the calcium signaling in neutrophils induced by hyphae culture supernatants was blocked by a free fatty acid receptor 2 antagonist and potently increased in the presence of a positive allosteric modulator. Our data imply that short-chain fatty acids may act as a recruitment signal whereby neutrophils can detect C. albicans hyphae. [ABSTRACT FROM AUTHOR]

Invasive mycoses remain underdiagnosed and difficult to treat. Hospitalized individuals with compromised immunity increase in number and constitute the main risk group for severe fungal infections. Current antifungal therapy is hampered by slow and insensitive diagnostics and frequent toxic side effects of standard antifungal drugs. Identification of new antifungal compounds with high efficacy and low toxicity is therefore urgently required. We investigated the antifungal activity of tempol, a cell-permeable nitroxide. To narrow down possible mode of action we used RNA-seq technology and metabolomics to probe for pathways specifically disrupted in the human fungal pathogen Candida albicans due to tempol administration. We found genes upregulated which are involved in iron homeostasis, mitochondrial stress, steroid synthesis, and amino acid metabolism. In an ex vivo whole blood infection, tempol treatment reduced C. albicans colony forming units and at the same time increased the release of pro-inflammatory cytokines, such as interleukin 8 (IL-8, monocyte chemoattractant protein-1, and macrophage migration inhibitory factor). In a systemic mouse model, tempol was partially protective with a significant reduction of fungal burden in the kidneys of infected animals during infection onset. The results obtained propose tempol as a promising new antifungal compound and open new opportunities for the future development of novel therapies. [ABSTRACT FROM AUTHOR]

Cryptococcosis, caused by the basidiomycete Cryptococcus neoformans , is a life-threatening disease affecting approximately one million people per year worldwide. Infection can occur when C. neoformans cells are inhaled by immunocompromised people. In order to establish infection, the yeast must bypass recognition and clearance by immune cells guarding the tissue. Using in vitro infections, we characterized the role of mast cells (MCs) in cryptococcosis. We found that MCs recognize C. neoformans and release inflammatory mediators such as tryptase and cytokines. From the latter group MCs released mainly CCL-2/MCP-1, a strong chemoattractant for monocytic cells. We demonstrated that supernatants of infected MCs recruit monocytes but not neutrophils. During infection with C. neoformans , MCs have a limited ability to kill the yeast depending on the serotype. C. neoformans , in turn, modulates the lifespan of MCs both, by presence of its polysaccharide capsule and by secreting soluble modulators. Taken together, MCs might have important contributions to fungal clearance during early stages of cryptocococis where these cells regulate recruitment of monocytes to mucosal tissues. [ABSTRACT FROM AUTHOR]

Neutrophils are crucial for the human innate immunity and constitute the majority of leukocytes in circulation. Thus, blood neutrophil counts serve as a measure for the immune system's functionality. Hematological patients often have low neutrophil counts due to disease or chemotherapy. To increase neutrophil counts and thereby preventing infections in high-risk patients, recombinant G-CSF is widely used as adjunct therapy to stimulate the maturation of neutrophils. In addition, G-CSF is utilized to recruit stem cells (SCs) into the peripheral blood of SC donors. Still, the actual functionality of neutrophils resulting from G-CSF treatment remains insufficiently understood. We tested the ex vivo functionality of neutrophils isolated from blood of G-CSF-treated healthy SC donors. We quantified chemotaxis, oxidative burst, and phagocytosis before and after treatment and detected significantly reduced chemotactic activity upon G-CSF treatment. Similarly, in vitro treatment of previously untreated neutrophils with G-CSF led to reduced chemotactic activity. In addition, we revealed that this effect persists in the allogeneic SC recipients up to 4 weeks after neutrophil engraftment. Our data indicates that neutrophil quantity, as a sole measure of immunocompetence in high-risk patients should be considered cautiously as neutrophil functionality might be affected by the primary treatment. [ABSTRACT FROM AUTHOR]

Neutrophils have the ability to capture and kill microbes extracellularly through the formation of neutrophil extracellular traps (NETs). These are DNA and protein structures that neutrophils release extracellularly and are believed to function as a defense mechanism against microbes. The classic NET formation process, triggered by, e.g., bacteria, fungi, or by direct stimulation of protein kinase C through phorbol myristate acetate, is an active process that takes several hours and relies on the production of reactive oxygen species (ROS) that are further modified by myeloperoxidase (MPO). We show here that NET-like structures can also be formed by neutrophils after interaction with phenol-soluble modulin α (PSMα) that are cytotoxic membrane-disturbing peptides, secreted from community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). The PSMα-induced NETs contained the typical protein markers and were able to capture microbes. The PSMα-induced NET structures were disintegrated upon prolonged exposure to DNase-positive S. aureus but not on exposure to DNase-negative Candida albicans. Opposed to classic NETosis, PSMα-triggered NET formation occurred very rapidly, independently of ROS or MPO, and was also manifest at 4°C. These data indicate that rapid NETs release may result from cytotoxic membrane disturbance by PSMα peptides, a process that may be of importance for CA-MRSA virulence. [ABSTRACT FROM AUTHOR]

This article, integrating different lines of sociocultural and critical research, sets out to analyze argumentative writing in a 6th grade Cypriot Greek elementary classroom. Attention is directed to specific strategies used, such as repetition and paraphrase of each other's words and of text meanings. These strategies are revisited as voicing tools, arising out of students' engagement with a nexus of reading and writing events and with the ideological positions constituted through them. The analysis traces the bi-directional processes at work in this polyvocal community. Classroom activities, rather than seen as neutral, are redefined as constituents of a deeply dialogic universe, which privileges specific texts and voices and projects various identity positions onto speakers and writers. At the same time, this universe gives rise to specific scaffolds which help students in the appropriation of advanced generic resources. Students' argumentative texts are shown to arise out of the integration of various dialogically-emergent strategies. Analysis illustrates how students, while drawing from prior texts, and acknowledging genre-related scaffolds, rework and contest social meanings and generic resources as part of their attempt to assert their voice vis-à-vis those populating their classroom community. [ABSTRACT FROM AUTHOR]

Invasive mycoses have been increasing worldwide, with Candida spp. being the most prevalent fungal pathogen causing high morbidity and mortality in immunocompromised individuals. Only few antimycotics exist, often with severe side effects. Therefore, new antifungal drugs are urgently needed. Because the identification of antifungal compounds depends on fast and reliable assays, we present a new approach based on high-throughput image analysis to define cell morphology. Candida albicans and other fungi of the Candida clade switch between different growth morphologies, from budding yeast to filamentous hyphae. Yeasts are considered proliferative, whereas hyphae are required for invasion and dissemination. Thus, morphotype switching in many Candida spp. is connected to virulence and pathogenesis. It is, consequently, reasonable to presume that morphotype blockers interfere with the virulence, thereby preventing hazardous colonization. Our method efficiently differentiates yeast from hyphal cells using a combination of automated microscopy and image analysis. We selected the parameters length/width ratio and mean object shape to quantitatively discriminate yeasts and hyphae. Notably, Z′ factor calculations for these parameters confirmed the suitability of our method for high-throughput screening. As a second stage, we determined cell viability to discriminate morphotype-switching inhibitors from those that are fungicidal. Thus, our method serves as a basis for the identification of candidates for next-generation antimycotics. [ABSTRACT FROM PUBLISHER]

Reaction of KVO3 with 2-[N,N'-(carboxymethyl)aminomethyl]-5-methylhydro quinone (H4 mecah) in aqueous solution at pH 8.2 results in the isolation of mononuclear K2 [VV (O)2 {Hmecah(-3)}]2H2O complex. On the other hand, reaction with the 2-[N,N'-(carboxymethyl)aminomethyl]-5-tert-butylhydroquinone (H4tbutcah) under the same conditions gives the tetranuclear mixed-valent complex K6 [{VV O(µ-O)VIV O}{µ-tbutbicah(-6)}]210.5H2 O(H6 tbutbicah, 2,2'-({2-[bis(carboxymethyl)amino]-3,6-dihydroxy-4-methylbenzyl}azanediyl)diacetic acid). The structures of both complexes were determined by single-crystal X-ray crystallography. The coordination environment of vanadium ions in both complexes is octahedral, with four out of the six positions to be occupied by the two cis carboxylate oxygens, one hydroquinonate oxygen, and one amine nitrogen atoms of the ligands' tripod binding sites. The importance of the chelate ring strains in the stabilization of the p-semiquinone radical is also discussed. A protonation of the ligated to vanadium(IV) ion hydroquinonate oxygen at low pH was revealed by continuous wave (cw) X-band electron paramagnetic resonance (EPR) and UV-vis spectroscopies. [ABSTRACT FROM AUTHOR]

Bisphosphonates are biologically relevant therapeutics for bone disorders and cancer. Reaction of γ-chlorobutyric acid, phosphorus acid, and phosphorus trichloride without the use of solvent gave the tetrahydrofuranyl-2,2-bisphosphonate sodium salt (Na2H2L). The Na2H2L was isolated, characterized in solution by ¹H, 13C, and 31P NMR spectroscopy and in solid state by single X-Ray crystallography. The crystal structure showed that the Na2H2L forms in the crystal infinite two-dimensional sheets stacked one parallel to the other. A comparison of the chelating properties of H2L2- with similar hydroxyl bisphosphonate ligands shows that the strength of the Na-O(furanyl/hydroxyl) bond is directly related to the total charge of the ligand anion. [ABSTRACT FROM AUTHOR]

Copper ions in the active sites of several proteins/enzymes interact with phenols and quinones, and this interaction is associated to the reactivity of the enzymes. In this study the speciation of the Cu2+ with iminodiacetic phenolate/hydroquinonate ligands has been examined by pH-potentiometry. The results reveal that the iminodiacetic phenol ligand forms mononuclear complexes with Cu2+ at acidic and alkaline pHs, and a binuclear Ophenolate-bridged complex at pH range from 7 to 8.5. The binucleating hydroquinone ligand forms only 2 : 1 metal to ligand complexes in solution. The pK values of the protonation of the phenolate oxygen of the two ligands are reduced about 2 units after complexation with the metal ion and are close to the pK values for the copper-interacting tyrosine phenol oxygen in copper enzymes. [ABSTRACT FROM AUTHOR]

Reaction of NH4VO3 with (phenolate/hydroquinonate) iminodiacetate tripod ligands in aqueous solution in the pH range 7-8 results in the isolation of three new dioxido vanadium(V) complexes, one dinuclear (NH4)4{(VVO)2[μ-bicah(6-)-N,O,O,O]}·8H2O, (H6bicah, 2,5-bis[N,N′-bis(carboxymethyl)aminomethyl]-hydroquinone), and two mono - nuclear (NH4)2{(VVO)2[Hcah(3-)-N,O,O,O]·2H2O, (H4cah, 2-[N,N′-bis(carboxy - methyl)aminomethyl]-hydroquinone) and (NH4)2{(VVO)[Hcacp(3-)-N,O,O,O]} 4H2O, (H4cacp, 2-[N,N′-bis(carboxymethyl)aminomethyl]-4-carboxyphenol). The 51V, 1H, and 13C NMR spectra in D2O show the coordination environment of vanadium in the above complexes to be octahedral, with four out of six positions to be occupied by the two carboxylate oxygen, one hydroquinonate oxygen, and one amine nitrogen atoms of the tripod ligand. The two acetate arms are in cis position to each other. Variable-temperature ¹H and 13C NMR measure ments show that the complexes are kinetically labile. An intramolecular exchange that proceeds through the opening of the phenolate/hydroquinonate chelate ring has been revealed by 2D{¹H} NMR EXSY (exchange spectroscopy). [ABSTRACT FROM AUTHOR]

Immunosuppressed patients are frequently afflicted with severe mycoses caused by opportunistic fungal pathogens. Besides being a commensal, colonizing predominantly skin and mucosal surfaces, Candida albicans is the most common human fungal pathogen. Mast cells are present in tissues prone to fungal colonization being expectedly among the first immune cells to get into contact with C. albicans. However, mast cell-fungus interaction remains a neglected area of study. Here we show that human mast cells mounted specific responses towards C. albicans. Collectively, mast cell responses included the launch of initial, intermediate and late phase components determined by the secretion of granular proteins and cytokines. Initially mast cells reduced fungal viability and occasionally internalized yeasts. C. albicans could evade ingestion by intracellular growth leading to cellular death. Furthermore, secreted factors in the supernatants of infected cells recruited neutrophils, but not monocytes. Late stages were marked by the release of cytokines that are known to be anti-inflammatory suggesting a modulation of initial responses. C. albicans-infected mast cells formed extracellular DNA traps, which ensnared but did not kill the fungus. Our results suggest that mast cells serve as tissue sentinels modulating antifungal immune responses during C. albicans infection. Consequently, these findings open new doors for understanding fungal pathogenicity. [ABSTRACT FROM AUTHOR]