Gentamycin inhibits the growth of Malassezia pachydermatis in culture

BackgroundMalassezia pachydermatis is a yeast of importance in both veterinary and human medicine.AimsTo know if M. pachydermatis grow on micological media with high concentrations of gentamycin.MethodsTwenty M. pachydermatis strains were streaked on Sabouraud Dextrose Agar plates with different concentrations of gentamycin.ResultsAll isolates were inhibited when high concentrations of gentamycin were added.ConclusionsThe use of plates with high concentrations of gentamycin can lead to some important misdiagnoses: firstly, false-negative cultures, and secondly, an erroneous classification of M. pachydermatis as a lipid-dependent species. Morever, all of this could be useful in two therapeutic fields: i) in animals, topical gentamycin could be an efficacious treatment for a disease such as external otitis in dogs; ii) in humans, we hypothesize that gentamycin could be regarded as a possible therapy (“antibiotic-lock”) for catheter-associated Malassezia spp. infections.     

Gliadins induce TNFα production through cAMP-dependent protein kinase A activation in intestinal cells (Caco-2)

Celiac disease is an autoimmune enteropathy caused by a permanent intolerance to gliadins. In this study the effects of two gliadin-derived peptides (PA2, PQPQLPYPQPQLP and PA9, QLQPFPQPQLPY) on TNFα production by intestinal epithelial cells (Caco-2) and whether these effects were related to protein kinase A (PKA) and/or -C (PKC) activities have been evaluated. Caco-2 cell cultures were challenged with several sets of gliadin peptides solutions (0.25 mg/mL), with/without different activators of PKA or PKC, bradykinin (Brdkn) and pyrrolidine dithiocarbamate (PDTC). The gliadin-derived peptides assayed represent the two major immunodominant epitopes of the peptide 33-mer of α-gliadin (56–88) (LQLQPFPQPQLPYPQPQLPYPQPQLPYPQPQPF). Both peptides induced the TNFα production triggering the inflammatory cell responses, the PA2 being more effective. The addition of the peptides in the presence of dibutyril cyclic AMP (cAMP), Brdkn or PDTC, inhibited the TNFα production. The PKC-activator phorbol 12-myristate 13-diacetate additionally increased the PA2- and PA9-induced TNFα production. These results link the gliadin-derived peptides induced TNFα production through cAMP-dependent PKA activation, where ion channels controlling calcium influx into cells could play a protective role, and requires NF-κB activation.     

The oncogenic phosphatase WIP1 negatively regulates nucleotide excision repair

Nucleotide excision repair (NER) is the only mechanism in humans to repair UV-induced DNA lesions such as pyrimidine (6-4) pyrimidone photoproducts and cyclobutane pyrimidine dimers (CPDs). In response to UV damage, the ataxia telangiectasia mutated and Rad3-related (ATR) kinase phosphorylates and activates several downstream effector proteins, such as p53 and XPA, to arrest cell cycle progression, stimulate DNA repair, or initiate apoptosis. However, following the completion of DNA repair, there must be active mechanisms that restore the cell to a prestressed homeostatic state. An important part of this recovery must include a process to reduce p53 and NER activity as well as to remove repair protein complexes from the DNA damage sites. Since activation of the damage response occurs in part through phosphorylation, phosphatases are obvious candidates as homeostatic regulators of the DNA damage and repair responses. Therefore, we investigated whether the serine/threonine wild-type p53-induced phosphatase 1 (WIP1/PPM1D) might regulate NER. WIP1 overexpression inhibits the kinetics of NER and CPD repair, whereas WIP1 depletion enhances NER kinetics and CPD repair. This NER suppression is dependent on WIP1 phosphatase activity, as phosphatase-dead WIP1 mutants failed to inhibit NER. Moreover, WIP1 suppresses the kinetics of UV-induced damage repair largely through effects on NER, as XPD-deficient cells are not further suppressed in repairing UV damage by overexpressed WIP1. Wip1 null mice quickly repair their CPD and undergo less UV-induced apoptosis than their wild-type counterparts. In vitro phosphatase assays identify XPA and XPC as two potential WIP1 targets in the NER pathway. Thus WIP1 may suppress NER kinetics by dephosphorylating and inactivating XPA and XPC and other NER proteins and regulators after UV-induced DNA damage is repaired.     

Typology of environmental conditions at the onset of winter phytoplankton blooms in a shallow macrotidal coastal ecosystem, Arcachon Bay (France)

Phytoplankton dynamics were assessed in the macrotidal ecosystemof Arcachon Bay through high-frequency surveys over a 5-yearperiod in order to characterize typology of environmental conditionsat the onset of the productive period. Temporal variations ofhydrological and biological parameters were examined in externaland internal waters of the lagoon, during the winter–springperiods from 1999 to 2003. An additional survey was performedduring winter–spring 2005 in order to study the verticalstructure of the water column. The occurrence of winter phytoplanktonblooms between January and March emerged as a recurrent event.The early onset of the productive period is influenced by thebiological functioning of adjacent Bay of Biscay oceanic waters.It is hypothesized that under a propitious hydrodynamic regime,phytoplankton inocula from the Bay of Biscay enter in the ArcachonBay where cells presumably find favourable conditions for theirfast development. The timing of the onset of those winter bloomsin Arcachon Bay seems to be mainly influenced by the presenceof anticyclonic weather conditions (associated with an increasein incident irradiance) during late winter (i.e. by February),while the water column does not show any particular stabilizationnor stratification liable to facilitate the onset of these blooms.Moreover, these winter blooms dominated by diatoms led to anearly nutrient depletion which could have inevitable consequenceson the structuration of the food web during spring and summer.     

Vasodilator effects of peptides derived from egg white proteins

The aim of this work was to investigate the effect of several peptides, identified before and after simulated gastrointestinal digestion of an egg white hydrolysate, on the vascular function, in rat aorta. The sequences IVF, RADHPFL and YAEERYPIL (0.1 mM) induced vasodilatation in intact aortic rings, with the maximum percentage of dilation corresponding to RADHPFL (40.5 ± 7.0%). Two of the end products of the gastrointestinal digestion, RADHP and YPI, also showed vasodilator activity with degrees of relaxation higher than 50%. However, all these peptides failed to induce relaxation in endothelium-denuded aortic rings. The relaxation induced by RADHP was concentration-dependent and it was partially blocked by the nitric oxide synthase inhibitor l-NAME (100 μM) and by the B₁ bradykinin receptor antagonist Des-HOE 140 (30 nM), thus showing that it was mediated by NO production through the activation of B₁ bradykinin receptors. These findings suggest that these peptides could reduce the vascular resistance and could be used as functional food ingredients in the prevention and treatment of hypertension.     

Three-dimensional model for the isolated recombinant influenza virus polymerase heterotrimer

The genome of influenza A virus is organized into eight ribonucleoprotein complexes (RNPs), each containing one RNA polymerase complex. This RNA polymerase has also been found non-associated to RNPs and is possibly involved in distinct functions in the infection cycle. We have expressed the virus RNA polymerase complex by co-tranfection of the PB1, PB2 and PA genes in mammalian cells and the heterotrimer was purified by the TAP tag procedure. Its 3D structure was determined by electron microscopy and single-particle image processing. The model obtained resembles the structure previously reported for the polymerase complex associated to viral RNPs but appears to be in a more open conformation. Detailed model comparison indicated that specific areas of the complex show important conformational changes as compared to the structure for the RNP-associated polymerase, particularly in regions known to interact with the adjacent NP monomers in the RNP. Also, the PB2 subunit seems to undergo a substantial displacement as a result of the association of the polymerase to RNPs. The structural model presented suggests that a core conformation of the polymerase in solution exists but the interaction with other partners, such as proteins or RNA, will trigger distinct conformational changes to activate new functional properties.     

Activation of mitochondrial-driven apoptosis in skeletal muscle cells is not mediated by reactive oxygen species production

While the acquisition of apoptosis resistance is part of the differentiation program of skeletal muscle cells, differentiated muscle cells can undergo apoptosis in response to physiological or pathological stimuli. The generation of reactive oxygen species by mitochondria plays a major role in the control of apoptosis in many cell types. Indeed their involvement in controlling apoptosis in differentiated muscle cells, or in generating resistance to apoptosis remains unknown. Moreover, differentiated muscle cells specifically express the uncoupling protein-3, a mitochondrial protein potentially involved in controlling reactive oxygen species production. To study the role of mitochondrial reactive oxygen species in the control of apoptosis in skeletal muscle cells, L6E9 myoblasts and myotubes were exposed to staurosporine, an inducer of apoptosis via mitochondrial pathways. Staurosporine activated apoptotic pathways (i.e. caspase-3 and caspase-9) increasing reactive oxygen species in myoblasts and, to a minor extent, in myotubes. However, the increase in reactive oxygen species was not needed to induce apoptosis nor was it involved in the differential sensitization of myoblasts and myotubes to apoptosis. Moreover, expression of uncoupling protein-3 in myotubes did not affect reactive oxygen species production, although it produced a slight sensitization for staurosporine-induced apoptosis. Results indicate that apoptotic activation in skeletal muscle cells mainly involves reactive oxygen species-independent mechanisms and that mitochondrial uncoupling protein-3 is not protective either for reactive oxygen species production or for apoptotic activation in muscle cells.     

Utilization of (18‐Crown‐6)‐2,3,11,12‐tetracarboxylic Acid as a Chiral NMR Solvating Agent for Diamines and β‐Amino Acids

The compound (18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid was evaluated as a chiral nuclear magnetic resonance (NMR) solvating agent for a series of diamines and bicyclic β‐amino acids. The amine must be protonated for strong association with the crown ether. An advantage of (18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid over many other crown ethers is that it undergoes a neutralization reaction with neutral amines to form the protonated species needed for binding. Twelve primary diamines in neutral and protonated forms were evaluated. Diamines with aryl and aliphatic groups were examined. Some are atropisomers with equivalent amine groups. Others have two nonequivalent amine groups. Association equilibria for these systems are complex, given the potential formation of 2:1, 1:1, and 1:2 crown‐amine complexes and given the various charged species in solution for mixtures of the crown ether with the neutral amine. The crown ether produced enantiomeric differentiation in the ¹H NMR spectrum of one or more resonances for every diamine substrate. Also, a series of five bicyclic β‐amino acids were examined and (18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid caused enantiomeric differentiation in the ¹H NMR spectrum of three or more resonances of each compound. Chirality 27:708–715, 2015. © 2015 Wiley Periodicals, Inc.     

Fractal Characterization of Chromatin Decompaction in Live Cells

Chromatin organization has a fundamental impact on the whole spectrum of genomic functions. Quantitative characterization of the chromatin structure, particularly at submicron length scales where chromatin fractal globules are formed, is critical to understanding this structure-function relationship. Such analysis is currently challenging due to the diffraction-limited resolution of conventional light microscopy. We herein present an optical approach termed inverse spectroscopic optical coherence tomography to characterize the mass density fractality of chromatin, and we apply the technique to observe chromatin decompaction in live cells. The technique makes it possible for the first time, to our knowledge, to sense intracellular morphology with length-scale sensitivity from ∼30 to 450 nm, thus primarily probing the higher-order chromatin structure, without resolving the actual structures. We used chromatin decompaction due to inhibition of histone deacytelases and measured the subsequent changes in the fractal dimension of the intracellular structure. The results were confirmed by transmission electron microscopy and confocal fluorescence microscopy.