Prefronto-cerebellar transcranial direct current stimulation increases amplituded and decreases latency of P3b component in patients with euthymic bipolar disorder

INTRODUCTION: Neurocognitive impairments have been observed in patients with bipolar disorder (BD) even during the euthymic phase of the disease, potentially representing trait-associated rather than state-associated characteristics of the disorder. In the present study, we used transcranial direct current stimulation (tDCS) applied to cerebellar and prefrontal cortices to improve the neurophysiological performances of patients with euthymic BD. METHODS: Twenty-five outpatients with BD underwent open-label prefrontocerebellar tDCS for 3 consecutive weeks. Neurophysiological performances were assessed through the examination of the P3b and P3a subcomponents of P300 event-related potential at baseline and after stimulation. RESULTS: Compared to baseline, P3b component after tDCS showed significantly higher amplitude and shorter latency (latency: Fz P=0.02, Cz P=0.03, and Pz P=0.04; amplitude: Fz P=0.24, Cz P=0.02, and Pz P=0.35). CONCLUSION: In our sample of patients with euthymic BD, concomitant prefrontoexcitatory and cerebellar-inhibitory modulations led to improved brain information processing stream. This improvement may at least partially result from neuroplastic modulation of prefrontocerebellar circuitry activity

Prefronto–cerebellar transcranial direct current stimulation improves visuospatial memory, executive functions, and neurological soft signs in patients with euthymic bipolar disorder

Objective: The aim of the study was to improve neuropsychological functioning of euthymic patients with bipolar disorder (BD) using transcranial direct current stimulation (tDCS) applied to cerebellar and prefrontal cortices. Methods: Twenty-five BD outpatients underwent prefrontal (anodal) and cerebellar (cathodal) tDCS for 3 consecutive weeks. All participants were assessed through the Rey Complex Figure Test delay and copy and the Neurological Examination Scale at baseline and after therapy with tDCS. Results: After tDCS treatment, patients showed significant improvements in visuospatial memory tasks. Patients with worse baseline cognitive performances also showed a significant improvement in executive functioning tasks. Neurological Examination Scale total score and motor coordination subscale significantly improved. Conclusion: Prefrontal-excitatory and cerebellar-inhibitory stimulations in euthymic BD patients may lead to better neurocognitive performances. This improvement could result from the modulation of prefronto-thalamic-cerebellar circuit activity pattern, which can be disrupted in BD

Hosting the Unwanted: Stethoscope Contamination Threat

Aims: Stethoscopes represent a vehicle of bacteria and other microorganisms and may play a role in the spread of health-care associated infections (HAIs). We aimed to evaluate the contamination levels of stethoscopes before and after use of a disinfecting technique (DT). Study Design: Matched cross-over study. Place and Duration of Study: The study was conducted in July 2012 and involved three hospitals in Siena Province (Italy). Two were public hospitals with about 750 and 140 beds, and the other was private with 40 beds. Methodology: We evaluated: i) contamination on 74 shared and non shared stethoscopes; ii) bacterial load before and after use of a DT. Total bacterial count (TBC) at 36ºC and 22ºC, Staphylococcus spp., molds, Enterococcus spp., Pseudomonas spp., Escherichia coli and total coliforms bacteria were evaluated. Mann Whitney and Wilcoxon tests were used for comparisons (p<0.05). Results: Before DT, 49 stethoscopes were positive for TBC at 36ºC, 48 for TBC at 22ºC, 40 for Staphylococcus spp., 18 for methicillin-resistant Staphylococcus aureus, 33 for coliforms (9 for Escherichia coli), 5 for Enterococcus spp. and 2 for molds. After cleaning, the percentage reduction in CFUs was close at 100% in most comparisons. Shared stethoscopes proved to be less contaminated than non shared ones (p<0.05). Conclusion: Our results suggest that stethoscopes may be potential vehicles of HAIs. The DT was effective in reducing bacterial contamination

Multisignal control of expression of the LHCX protein family in the marine diatom Phaeodactylum tricornutum

Diatoms are phytoplanktonic organisms that grow successfully in the ocean where light conditions are highly variable. Studies of the molecular mechanisms of light acclimation in the marine diatom Phaeodactylum tricornutum show that carotenoid de-epoxidation enzymes and LHCX1, a member of the light-harvesting protein family, both contribute to dissipate excess light energy through non-photochemical quenching (NPQ). In this study, we investigate the role of the other members of the LHCX family in diatom stress responses. Our analysis of available genomic data shows that the presence of multiple LHCX genes is a conserved feature of diatom species living in different ecological niches. Moreover, an analysis of the levels of four P. tricornutum LHCX transcripts in relation to protein expression and photosynthetic activity indicates that LHCXs are differentially regulated under different light intensities and nutrient starvation, mostly modulating NPQ capacity. We conclude that multiple abiotic stress signals converge to regulate the LHCX content of cells, providing a way to fine-tune light harvesting and photoprotection. Moreover, our data indicate that the expansion of the LHCX gene family reflects functional diversification of its members which could benefit cells responding to highly variable ocean environments

The DivJ, CbrA and PleC system controls DivK phosphorylation and symbiosis in Sinorhizobium meliloti

Sinorhizobium meliloti is a soil bacterium that invades the root nodules it induces on Medicago sativa, whereupon it undergoes an alteration of its cell cycle and differentiates into nitrogen-fixing, elongated and polyploid bacteroid with higher membrane permeability. In Caulobacter crescentus, a related alphaproteobacterium, the principal cell cycle regulator, CtrA, is inhibited by the phosphorylated response regulator DivK. The phosphorylation of DivK depends on the histidine kinase DivJ, while PleC is the principal phosphatase for DivK. Despite the importance of the DivJ in C. crescentus, the mechanistic role of this kinase has never been elucidated in other Alphaproteobacteria. We show here that the histidine kinases DivJ together with CbrA and PleC participate in a complex phosphorylation system of the essential response regulator DivK in S. meliloti. In particular, DivJ and CbrA are involved in DivK phosphorylation and in turn CtrA inactivation, thereby controlling correct cell cycle progression and the integrity of the cell envelope. In contrast, the essential PleC presumably acts as a phosphatase of DivK. Interestingly, we found that a DivJ mutant is able to elicit nodules and enter plant cells, but fails to establish an effective symbiosis suggesting that proper envelope and/or low CtrA levels are required for symbiosis.National Institutes of Health (U.S.) (Grant GM31010

A systems-wide understanding of photosynthetic acclimation in algae and higher plants

The ability of phototrophs to colonise different environments relied on the robust protection against oxidative stress in phototrophs, a critical requirement for the successful evolutionary transition from water to land. Photosynthetic organisms have developed numerous strategies to adapt their photosynthetic apparatus to changing light conditions in order to optimise their photosynthetic yield, crucial for life to exist on Earth. Photosynthetic acclimation is an excellent example of the complexity of biological systems, in which highly diverse processes, ranging from electron excitation over protein protonation to enzymatic processes coupling ion gradients with biosynthetic activity interact on drastically different timescales, ranging from picoseconds to hours. An efficient functioning of the photosynthetic apparatus and its protection is paramount for efficient downstream processes including metabolism and growth. Modern experimental techniques can be successfully integrated with theoretical and mathematical models to promote our understanding of underlying mechanisms and principles. This Review aims to provide a retrospective analysis of multidisciplinary photosynthetic acclimation research carried out by members of the Marie Curie Initial Training Project “AccliPhot”, placing the results in a wider context. The Review also highlights the applicability of photosynthetic organisms for industry, particularly with regards to the cultivation of microalgae. It aims to demonstrate how theoretical concepts can successfully complement experimental studies broadening our knowledge of common principles in acclimation processes in photosynthetic organisms, as well as in the field of applied microalgal biotechnology

Rôle des protéines de la famille des antennes collectrices de lumière, LHCX, dans la photoprotection chez les diatomées

Diatoms dominate phytoplanktonic communities in contemporary oceans, contributing to 20% of global primary productivity. In their extremely variable environment, diatoms are especially efficient in adjusting their photosynthetic activity by dissipating as heat the light energy absorbed in excess, through a process called “Non-Photochemical Quenching of chlorophyll fluorescence”, (NPQ). In the model diatom Phaeodactylum tricornutum, it has been shown that LHCX1, a photosynthetic antenna-related gene, is involved in the NPQ process. Through integrated approaches of genetics, molecular biology, biochemistry, study of the kinetics of chlorophyll fluorescence yields and ultrafast spectroscopy, I studied the role of the LHCX family in the photoprotection activity of P. tricornutum. I first correlated a differential regulation of the 4 P. tricornutum LHCX genes with different dynamics of NPQ and photosynthetic activity, in different light and nutrient conditions. By localizing the LHCXs in fractioned photosynthetic complexes and the different sites of energy dissipation, I was able to propose a model of dynamic regulation of NPQ capacity involving mainly the LHCX1 in the reaction centers, during short-term high light responses. During prolonged high light stress, the quenching occurs mainly in the antennas, potentially mediated by the LHCX3 isoform. Finally, using photosynthetic parameters, I screened a series of transgenic lines putatively deregulated in their LHCX amount, and I identified lines with altered NPQ, which could represent novel investigation tools. Altogether, this work highlighted the functional diversification and the importance of the LHCX protein family in the fine-tuning of light harvesting and photoprotection capacity, possibly contributing to explain diatoms success in their highly fluctuating environment.Les diatomées constituent le principal groupe du phytoplancton dans les océans, contribuant à près de 20% de la production primaire globale. Dans leur environnement très variable, les diatomées sont particulièrement efficaces dans leur capacité à ajuster leur activité photosynthétique en dissipant sous forme de chaleur l’énergie lumineuse absorbée en excès, par un processus appelé le « Non-Photochemical Quenching of chlorophyll fluorescence », (NPQ). Chez la diatomée modèle, Phaeodactylum tricornutum, il a été montré que LHCX1, une protéine proche des antennes photosynthétiques, est impliquée dans le NPQ. Par des approches intrégrées de génétique, biologie moléculaire, biochimie, imagerie des cinétiques de fluorescence et spectroscopie ultrarapide, j’ai étudié le rôle de la famille des LHCX chez P. tricornutum. J’ai tout d’abord pu corréler une expression différentielle des 4 gènes LHCX de P. tricornutum avec différentes dynamiques de NPQ et activités photosynthétiques, dans différentes conditions de lumiére et nutriments. En localisant les LHCX dans les differents complexes photosynthétiques et les différents sites de dissipation d’énergie, j’ai pu proposer un modèle de régulation dynamique du NPQ impliquant à court terme principalement LHCX1 au niveau des centres réactionnels, et une autre isoforme, possiblement LHCX3, au niveau des antennes lors d’un stress lumineux prolongé. Enfin, par le criblage d’une série de mutants potentiellement dérégulés dans leur contenu en LHCXs, j’ai pu identifier des lignées avec un NPQ altéré qui pourront constituer des nouveaux outils de recherche. Dans l’ensemble ce travail de thèse a permis de mettre en évidence la diversification fonctionnelle et l’importance de la famille des LHCX dans la fine modulation des capacités de collecte de lumière et de photoprotection, expliquant sans doute en partie le succès des diatomées dans leur environnement très fluctuant

Impact of a disinfecting technique on microbial contamination of computer keyboards and telephone handsets

Background: Computers and telephones are ubiquitous in the hospital and have been shown to be contaminated with potentially pathogenic microorganism. The aim of the study was to determine microbial contamination on computer keyboards and telephone handsets and the effectiveness of a disinfecting technique (DT). Methods: A matched cross-over study, involving an overall of 50 computer keyboards and 50 telephone handsets, was conducted in three hospitals, located in the Local Health Area of Siena (Italy) before and after the use of an innovative DT consisting of a malleable-elastic compound, containing ethanol, which adheres to surfaces, removes dirt and disinfects. Total bacterial count was evaluated and several types of bacteria and fungi were researched pre- and post- use of the DT. Non parametric tests: Wilcoxon signed rank and Mann Whitney, were used, when appropriate. Results: The DT was effective in disinfecting the objects. In fact, Colony-Forming Units (CFUs) decreased to zero in most comparisons. All the comparisons showed significant differences (p<0.001) after the DT, both for computer keyboards and telephone handsets. The only exception was found for molds in telephones (p=0.062). Keyboards emerged to be dirtier than telephones handsets (p<0.05) for several types of bacteria. Conclusions: The data suggest that microbial contamination of keyboards and telephones is considerable. These objects can be a vehicle for Health Care-Associated Infections HAIs and their disinfection should not be neglected. The DT showed to be appropriate for the disinfecting purpose

Dynamic Changes between Two LHCX-Related Energy Quenching Sites Control Diatom Photoacclimation

International audienceMarine diatoms are prominent phytoplankton organisms that perform photosynthesis in extremely variable environments. Diatoms possess a strong ability to dissipate excess absorbed energy as heat via nonphotochemical quenching (NPQ). This process relies on changes in carotenoid pigment composition (xanthophyll cycle) and on specific members of the light-harvesting complex family specialized in photoprotection (LHCXs), which potentially act as NPQ effectors. However, the link between light stress, NPQ, and the existence of different LHCX isoforms is not understood in these organisms. Using picosecond fluorescence analysis, we observed two types of NPQ in the pennate diatom Phaeodactylum tricornutum that were dependent on light conditions. Short exposure of low-light-acclimated cells to high light triggers the onset of energy quenching close to the core of photosystem II, while prolonged light stress activates NPQ in the antenna. Biochemical analysis indicated a link between the changes in the NPQ site/mechanism and the induction of different LHCX isoforms, which accumulate either in the antenna complexes or in the core complex. By comparing the responses of wild-type cells and transgenic lines with a reduced expression of the major LHCX isoform, LHCX1, we conclude that core complex-associated NPQ is more effective in photoprotection than is the antenna complex. Overall, our data clarify the complex molecular scenario of light responses in diatoms and provide a rationale for the existence of a degenerate family of LHCX proteins in these algae

Evolution of internal stresses and substructure during creep at intermediate temperatures

[EN] Secondary creep has most generally been associated with a rather steady structure. Many models have been suggested to explain the constant strain rate in terms of the effective stress which is determined by the structurally-dependent internal stresses. The internal stresses deduced macroscopically have been of the order of half the applied stress. In this article, by pinning the dislocations under load in an Al-Zn alloy, the evolution of the structure and local effective stresses with strain has been identified by electron microscopy. Values of local effective stresses at the subgrain boundaries ranging between 10-20 times the applied stress have been measured. The emission of dislocations from these boundaries and the evolution of substructure within the subgrain interior indicate that the controlling mechanism during the creep process is the relaxation of internal stresses by this emission. At the same time, the subboundary stress-fields existing in different subgrains determine their different behaviour as a function of time. Hard and soft subgrains alternate in the deformation process to produce overall uniform strain.[FR] Le fluage secondaire a été le plus souvent associé à une structure plutôt constante. De nombreux modèles ont été proposés pour expliquer la vitesse de déformation constante à partir de la contrainte effective déterminée par les contraintes internes dépendant de la structure. Les contraintes internes déduites macroscopiquement étaient de l'ordre de la moitié de la contrainte appliquée. Dans cet article, nous avons précisé par microscopie électronique l'évolution de la structure et des contraintes effectives locales en fonction de la déformation, en ancrant les dislocations sous charge dans un alliage Al-Zn. Nous avons mesuré des valeurs des contraintes effectives locales aux sous-joints de grains comprises entre 10 et 20 fois la contrainte appliquée. L'émission de dislocations hors de ces sous-joints et l'évolution de la sous-structure à l'intérieur des sous-grains montrent que le mécanisme qui contrôle le phénomène de fluage est la relaxation des contraintes internes par cette émission. En même temps, les champs de contrainte des sous-joints qui existent dans différents sous-grains déterminent leur comportement différent en fonction du temps. Au cours de la déformation, on a des sous-grains alternativement durs et mous qui donnent une déformation globale uniforme