Changes in aggregation states of light-harvesting complexes as a mechanism for modulating energy transfer in desert crust cyanobacteria.

In this paper we propose an energy dissipation mechanism that is completely reliant on changes in the aggregation state of the phycobilisome light-harvesting antenna components. All photosynthetic organisms regulate the efficiency of excitation energy transfer (EET) to fit light energy supply to biochemical demands. Not many do this to the extent required of desert crust cyanobacteria. Following predawn dew deposition, they harvest light energy with maximum efficiency until desiccating in the early morning hours. In the desiccated state, absorbed energy is completely quenched. Time and spectrally resolved fluorescence emission measurements of the desiccated desert crust Leptolyngbya ohadii strain identified (i) reduced EET between phycobilisome components, (ii) shorter fluorescence lifetimes, and (iii) red shift in the emission spectra, compared with the hydrated state. These changes coincide with a loss of the ordered phycobilisome structure, evident from small-angle neutron and X-ray scattering and cryo-transmission electron microscopy data. Based on these observations we propose a model where in the hydrated state the organized rod structure of the phycobilisome supports directional EET to reaction centers with minimal losses due to thermal dissipation. In the desiccated state this structure is lost, giving way to more random aggregates. The resulting EET path will exhibit increased coupling to the environment and enhanced quenching

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

Simple down conversion nano-crystal coatings for enhancing Silicon-solar cells efficiency

Utilizing self-assembled nano-structured coatings on top of existing solar cells has thepotential to increase the total quantum efficiency of the cell using a simple and cheap process. In ourwork we have exploited the controlled absorption of nano-crystal with different band gaps to realizedown conversion artificial antennas that self-assembled on the device surface. The UV sun light isconverted to the visible light enhancing the solar cell performance in two complementary routes; a.protecting the solar cell and coatings from the UV illumination and therefore reducing the UVradiation damage. b. enhancing the total external quantum efficiency of the cell by one percent. Thisis achieved using a simple cheap process that can be adjusted to many different solar cells

Impact of lower uterine segment involvement in type II endometrial cancer and the unique mutational profile of serous tumors

Objective: Evaluation of the impact of lower uterine segment involvement (LUSI) in type II endometrial cancer, and mutational profile of uterine papillary serous carcinomas (UPSC). Methods: Retrospective cohort study comparing patients with type II endometrial cancer with LUSI to patients without LUSI. Genes commonly implicated in carcinogenesis were analyzed in a subgroup of 42 patients with UPSC using next generation sequencing. Results: 83 patients with type II endometrial cancer were included in the study, of these, LUSI was diagnosed in 31.3%. During a median follow-up of 45.5 months, patients with LUSI developed more local and distant recurrences (local: 19.2% vs. 3.5%, P = .03; distant: 50% vs. 17.5%, P = .004) and progression events (73.1% vs. 26.3%, P < .001), with shorter mean progression-free survival (16 months compared to 26.5 months, P < .01). In a multivariate analysis, LUSI was the only significant pathological factor, associated with a 2.9-fold increase in the risk of progression (P = .007), and a 2.6-fold increase in the risk of death (P = .02). In the subgroup of patients with UPSC, mutations were identified in 54 genes, including TP53 (80%), PPP2R1A (40%), and PTEN (22.5%). Frequent mutations in the PTEN-PI3K-AKT signaling pathway were found in patients with tumor in the upper uterine segment only (P = .04), with PTEN being mutated in 29% of the samples (P = .07). Conclusion: Type II endometrial cancers presenting in the LUS have a significantly worse prognosis and this might be associated with a unique mutational profile. Keywords: Lower uterine segment, Uterine papillary serous carcinoma, Type II endometrial cancer, Sequencing, Gene analysis, PTEN mutatio

An easily reversible structural change underlies mechanisms enabling desert crust cyanobacteria to survive desiccation.

International audienceBiological desert sand crusts are the foundation of desert ecosystems, stabilizing the sands and allowing colonization by higher order organisms. The first colonizers of the desert sands are cyanobacteria. Facing the harsh conditions of the desert, these organisms must withstand frequent desiccation-hydration cycles, combined with high light intensities. Here, we characterize structural and functional modifications to the photosynthetic apparatus that enable a cyanobacterium, Leptolyngbya sp., to thrive under these conditions. Using multiple in vivo spectroscopic and imaging techniques, we identified two complementary mechanisms for dissipating absorbed energy in the desiccated state. The first mechanism involves the reorganization of the phycobilisome antenna system, increasing excitonic coupling between antenna components. This provides better energy dissipation in the antenna rather than directed exciton transfer to the reaction center. The second mechanism is driven by constriction of the thylakoid lumen which limits diffusion of plastocyanin to P700. The accumulation of P700(+) not only prevents light-induced charge separation but also efficiently quenches excitation energy. These protection mechanisms employ existing components of the photosynthetic apparatus, forming two distinct functional modes. Small changes in the structure of the thylakoid membranes are sufficient for quenching of all absorbed energy in the desiccated state, protecting the photosynthetic apparatus from photoinhibitory damage. These changes can be easily reversed upon rehydration, returning the system to its high photosynthetic quantum efficiency

Mechanically rigid supramolecular assemblies formed from an Fmoc-guanine conjugated peptide nucleic acid.

The variety and complexity of DNA-based structures make them attractive candidates for nanotechnology, yet insufficient stability and mechanical rigidity, compared to polyamide-based molecules, limit their application. Here, we combine the advantages of polyamide materials and the structural patterns inspired by nucleic-acids to generate a mechanically rigid fluorenylmethyloxycarbonyl (Fmoc)-guanine peptide nucleic acid (PNA) conjugate with diverse morphology and photoluminescent properties. The assembly possesses a unique atomic structure, with each guanine head of one molecule hydrogen bonded to the Fmoc carbonyl tail of another molecule, generating a non-planar cyclic quartet arrangement. This structure exhibits an average stiffness of 69.6 ± 6.8 N m-1 and Young's modulus of 17.8 ± 2.5 GPa, higher than any previously reported nucleic acid derived structure. This data suggests that the unique cation-free "basket" formed by the Fmoc-G-PNA conjugate can serve as an attractive component for the design of new materials based on PNA self-assembly for nanotechnology applications

Changes in aggregation states of light-harvesting complexes as a mechanism for modulating energy transfer in desert crust cyanobacteria

In this paper we propose an energy dissipation mechanism that iscompletely reliant on changes in the aggregation state of thephycobilisome light-harvesting antenna components. All photosyntheticorganisms regulate the efficiency of excitation energy transfer(EET) to fit light energy supply to biochemical demands. Not many dothis to the extent required of desert crust cyanobacteria. Followingpredawn dew deposition, they harvest light energy with maximumefficiency until desiccating in the early morning hours. In thedesiccated state, absorbed energy is completely quenched. Timeand spectrally resolved fluorescence emission measurements of thedesiccated desert crust Leptolyngbya ohadii strain identified (i) reducedEET between phycobilisome components, (ii) shorter fluorescencelifetimes, and (iii) red shift in the emission spectra, comparedwith the hydrated state. These changes coincide with a loss of theordered phycobilisome structure, evident from small-angle neutronand X-ray scattering and cryo-transmission electron microscopy data.Based on these observations we propose a model where in the hydratedstate the organized rod structure of the phycobilisome supportsdirectional EET to reaction centers with minimal losses due tothermal dissipation. In the desiccated state this structure is lost, givingway to more random aggregates. The resulting EET path will exhibitincreased coupling to the environment and enhanced quenching