Sunscreens - Which and what for?

It is well established that sun exposure is the main cause for the development of skin cancer. Chronic continuous UV radiation is believed to induce malignant melanoma, whereas intermittent high-dose UV exposure contributes to the occurrence of actinic keratosis as precursor lesions of squamous cell carcinoma as well as basal cell carcinoma. Not only photocarcinogenesis but also the mechanisms of photoaging have recently become apparent. In this respect the use of sunscreens seemed to prove to be more and more important and popular within the last decades. However, there is still inconsistency about the usefulness of sunscreens. Several studies show that inadequate use and incomplete UV spectrum efficacy may compromise protection more than previously expected. The sunscreen market is crowded by numerous products. Inorganic sunscreens such as zinc oxide and titanium oxide have a wide spectral range of activity compared to most of the organic sunscreen products. It is not uncommon for organic sunscreens to cause photocontact allergy, but their cosmetic acceptability is still superior to the one given by inorganic sunscreens. Recently, modern galenic approaches such as micronization and encapsulation allow the development of high-quality inorganic sunscreens. The potential systemic toxicity of organic sunscreens has lately primarily been discussed controversially in public, and several studies show contradictory results. Although a matter of debate, at present the sun protection factor (SPF) is the most reliable information for the consumer as a measure of sunscreen filter efficacy. In this context additional tests have been introduced for the evaluation of not only the protective effect against erythema but also protection against UV-induced immunological and mutational effects. Recently, combinations of UV filters with agents active in DNA repair have been introduced in order to improve photoprotection. This article reviews the efficacy of sunscreens in the prevention of epithelial and nonepithelial skin cancer, the effect on immunosuppression and the value of the SPF as well as new developments on the sunscreen market. Copyright (C) 2005 S. Karger AG, Basel

Research on eco-hydro-morphological river processes by combining field investigations, physical modeling and numerical simulations

Hydrodynamical, morphodynamical and ecological river processes and their multiple linkages occur in an infinity of different configurations and over a wide range of spatial and temporal scales. This paper illustrates a research methodology that consists in combining field investigations, physical modeling in the laboratory, and numerical simulations in order to develop generic insight and tools for engineering and management of the river environment. This combined methodology is illustrated in research on (i) the macroscale characteristics of the velocity distribution and their relation to long-term and large-scale planimetric river processes, (ii) the flow field in the vicinity of the river bank and its importance with respect to bank erosion and, (iii) linkages between the characteristics of the mean flow and the turbulence on the one hand, and the behavior of invertebrates on the other. The reported research strongly relies on the use of state-of-the-art measuring instruments as well as numerical techniques

Influence of quorum sensing signal molecules on biofilm formation in Proteus mirabilis O18

The influence of basis of quorum sensing molecules on Proteus strains is much less known as compared to Pseudomonas or Escherichia. We have previously shown that a series of acylated homoserine lactones (acyl-HSL) does not influence the ureolytic, proteolytic, or hemolytic abilities, and that the swarming motility of Proteus mirabilis rods is strain specific. The aim of the presented study was to find out if the presence of a series of acyl-HSL influences biofilm formation of P. mirabilis laboratory strain belonging to O18 serogroup. This serogroup is characterized by the presence of a unique non-carbohydrate component, namely phosphocholine. Escherichia coli and P. mirabilis O18 strains used in this work contains cloned plasmids encoding fluorescent protein genes with constitutive gene expression. In mixed biofilms in stationary and continuous flow conditions, P. mirabilis O18 overgrow whole culture. P. mirabilis O18 strain has genetically proved a presence of AI–2 quorum sensing system. Differences in biofilm structure were observed depending on the biofilm type and culture methods. From tested acylated homoserine lactones (BHL, HHL, OHL, DHL, dDHL, tDHL), a significant influence had BHL on thickness, structure, and the amount of exopolysaccharides produced by biofilms formed by P. mirabilis O18 pDsRed2

Determination of Molecular Structures of HIV Envelope Glycoproteins using Cryo-Electron Tomography and Automated Sub-tomogram Averaging

Since its discovery nearly 30 years ago, more than 60 million people have been infected with the human immunodeficiency virus (HIV) (www.usaid.gov). The virus infects and destroys CD4+ T-cells thereby crippling the immune system, and causing an acquired immunodeficiency syndrome (AIDS) 2. Infection begins when the HIV Envelope glycoprotein "spike" makes contact with the CD4 receptor on the surface of the CD4+ T-cell. This interaction induces a conformational change in the spike, which promotes interaction with a second cell surface co-receptor 5,9. The significance of these protein interactions in the HIV infection pathway makes them of profound importance in fundamental HIV research, and in the pursuit of an HIV vaccine

Identification of a Key Amino Acid of LuxS Involved in AI-2 Production in Campylobacter jejuni

Autoinducer-2 (AI-2) mediated quorum sensing has been associated with the expression of virulence factors in a number of pathogenic organisms and has been demonstrated to play a role in motility and cytolethal distending toxin (cdt) production in Campylobacter jejuni. We have initiated the work to determine the molecular basis of AI-2 synthesis and the biological functions of quorum sensing in C. jejuni. In this work, two naturally occurring variants of C. jejuni 81116 were identified, one producing high-levels of AI-2 while the other is defective in AI-2 synthesis. Sequence analysis revealed a G92D mutation in the luxS gene of the defective variant. Complementation of the AI-2− variant with a plasmid encoded copy of the wild-type luxS gene or reversion of the G92D mutation by site-directed mutagenesis fully restored AI-2 production by the variant. These results indicate that the G92D mutation alone is responsible for the loss of AI-2 activity in C. jejuni. Kinetic analyses showed that the G92D LuxS has a ∼100-fold reduced catalytic activity relative to the wild-type enzyme. Findings from this study identify a previously undescribed amino acid that is essential for AI-2 production by LuxS and provide a unique isogenic pair of naturally occurring variants for us to dissect the functions of AI-2 mediated quorum sensing in Campylobacter

Embodiment and body awareness in meditators

[EN] Mindfulness practice consists of focusing attention in an intentional way on the experience of the present moment, including bodily sensations, thoughts or feelings, and the environment, with an attitude of acceptance and without judging. The body and, especially, body awareness are key elements in mindfulness. Embodiment or the feeling of being located within one's physical body is a related concept, and it is composed of the sense of ownership, location, and agency of the body. The rubber hand illusion (RHI) is an experimental paradigm that has been used to understand the mechanisms of embodiment, and evidence shows that body awareness modulates this illusion. To our knowledge, no studies have analyzed embodiment processes in meditators. The aim of this study is to use the RHI to analyze the mechanisms of embodiment and its relationship with body awareness and mindfulness in meditators and non-meditators. The sample was composed of long-term meditators (n = 15) and non-meditators (n = 15). Objective and self-report measures for embodiment with the RHI and self-report questionnaires of body awareness and mindfulness were administered. One-way ANOVA revealed significant differences between groups in sense of agency in the rubber hand. Meditators experienced less sense of agency in the rubber hand than non-meditators. Pearson's correlations showed that this lower sense of agency in the rubber hand was associated with higher body awareness and mindfulness. Results highlight the role of body awareness and mindfulness in embodiment mechanisms. This study has clinical implications, especially in psychopathological disorders that can be influenced by disturbances in these processes.The authors would like to acknowledge the "BODYTA" project (Spanish Ministry of Economy and Competitiveness, PSI2014-51928-R), "PROMOSAM" (Spanish Ministry of Economy and Competitiveness, PSI2014-56303-REDT), and "Excellence Research Program PROMETEO II" (Generalitat Valenciana, Conselleria de Educacion, Cultura y Deporte, PROMETEOII/2013/003). CIBERobn is an initiate of the ISCIII. PROMOSAM Excellence in Research Program (PSI2014-56303-REDT), MINECO, Spain.Cebolla, A.; Miragall, M.; Palomo, P.; Llorens Rodríguez, R.; Soler, J.; Demarzo, M.; García Campayo, J.... (2016). Embodiment and body awareness in meditators. Mindfulness. 7(6):1297-1305. https://doi.org/10.1007/s12671-016-0569-xS1297130576Aguado, J., Luciano, J. V., Cebolla, A., Serrano-Blanco, A., Soler, J., & García-Campayo, J. (2015). 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A Novel Enzymatic System against Oxidative Stress in the Thermophilic Hydrogen-Oxidizing Bacterium Hydrogenobacter thermophilus

Rubrerythrin (Rbr) is a non-heme iron protein composed of two distinctive domains and functions as a peroxidase in anaerobic organisms. A novel Rbr-like protein, ferriperoxin (Fpx), was identified in Hydrogenobacter thermophilus and was found not to possess the rubredoxin-like domain that is present in typical Rbrs. Although this protein is widely distributed among aerobic organisms, its function remains unknown. In this study, Fpx exhibited ferredoxin:NADPH oxidoreductase (FNR)-dependent peroxidase activity and reduced both hydrogen peroxide (H2O2) and organic hydroperoxide in the presence of NADPH and FNR as electron donors. The calculated Km and Vmax values of Fpx for organic hydroperoxides were comparable to that for H2O2, demonstrating a multiple reactivity of Fpx towards hydroperoxides. An fpx gene disruptant was unable to grow under aerobic conditions, whereas its growth profiles were comparable to those of the wild-type strain under anaerobic and microaerobic conditions, clearly indicating the indispensability of Fpx as an antioxidant of H. thermophilus in aerobic environments. Structural analysis suggested that domain-swapping occurs in Fpx, and this domain-swapped structure is well conserved among thermophiles, implying the importance of structural stability of domain-swapped conformation for thermal environments. In addition, Fpx was located on a deep branch of the phylogenetic tree of Rbr and Rbr-like proteins. This finding, taken together with the wide distribution of Fpx among Bacteria and Archaea, suggests that Fpx is an ancestral type of Rbr homolog that functions as an essential antioxidant and may be part of an ancestral peroxide-detoxification system