The native architecture of a photosynthetic membrane

In photosynthesis, the harvesting of solar energy and its subsequent conversion into a stable charge separation are dependent upon an interconnected macromolecular network of membrane-associated chlorophyll–protein complexes. Although the detailed structure of each complex has been determined, the size and organization of this network are unknown. Here we show the use of atomic force microscopy to directly reveal a native bacterial photosynthetic membrane. This first view of any multi-component membrane shows the relative positions and associations of the photosynthetic complexes and reveals crucial new features of the organization of the network: we found that the membrane is divided into specialized domains each with a different network organization and in which one type of complex predominates. Two types of organization were found for the peripheral light-harvesting LH2 complex. In the first, groups of 10–20 molecules of LH2 form light-capture domains that interconnect linear arrays of dimers of core reaction centre (RC)–light-harvesting 1 (RC–LH1–PufX) complexes; in the second they were found outside these arrays in larger clusters. The LH1 complex is ideally positioned to function as an energy collection hub, temporarily storing it before transfer to the RC where photochemistry occurs: the elegant economy of the photosynthetic membrane is demonstrated by the close packing of these linear arrays, which are often only separated by narrow 'energy conduits' of LH2 just two or three complexes wide

Lignin biomarkers as tracers of mercury sources in lakes water column

This study presents the role of specific terrigenous organic compounds as important vectors of mercury (Hg) transported from watersheds to lakes of the Canadian boreal forest. In order to differentiate the autochthonous from the allochthonous organic matter (OM), lignin derived biomarker signatures [Lambda, S/V, C/V, P/(V ? S), 3,5-Bd/V and (Ad/Al)v] were used. Since lignin is exclusively produced by terrigenous plants, this approach can give a non equivocal picture of the watershed inputs to the lakes. Moreover, it allows a characterization of the source of OM and its state of degradation. The water column of six lakes from the Canadian Shield was sampled monthly between June and September 2005. Lake total dissolved Hg concentrations and Lambda were positively correlated, meaning that Hg and ligneous inputs are linked (dissolved OM r2 = 0.62, p\0.0001; particulate OM r2 = 0.76, p\0.0001). Ratios of P/(V ? S) and 3,5-Bd/V from both dissolved OM and particulate OM of the water column suggest an inverse relationship between the progressive state of pedogenesis and maturation of the OM in soil before entering the lake, and the Hg concentrations in the water column. No relation was found between Hg levels in the lakes and the watershed flora composition—angiosperm versus gymnosperm or woody versus non-woody compounds. This study has significant implications for watershed management of ecosystems since limiting fresh terrestrial OM inputs should reduce Hg inputs to the aquatic systems. This is particularly the case for largescale land-use impacts, such as deforestation, agriculture and urbanization, associated to large quantities of soil OM being transferred to aquatic systems

A large-scale study on the effects of sex on gray matter asymmetry

Research on sex-related brain asymmetries has not yielded consistent results. Despite its importance to further understanding of normal brain development and mental disorders, the field remains relatively unexplored. Here we employ a recently developed asymmetry measure, based on the Dice coefficient, to detect sex-related gray matter asymmetries in a sample of 457 healthy participants (266 men and 191 women) obtained from 5 independent databases. Results show that women’s brains are more globally symmetric than men’s (p < 0.001). Although the new measure accounts for asymmetries distributed all over the brain, several specific structures were identified as systematically more symmetric in women, such as the thalamus and the cerebellum, among other structures, some of which are typically involved in language production. These sex-related asymmetry differences may be defined at the neurodevelopmental stage and could be associated with functional and cognitive sex differences, as well as with proneness to develop a mental disorder

Direct intra-abdominal pressure monitoring via piezoresistive pressure measurement: a technical note

<p>Abstract</p> <p>Background</p> <p>Piezoresistive pressure measurement technique (PRM) has previously been applied for direct IAP measurement in a porcine model using two different devices. Aim of this clinical study was to assess both devices regarding complications, reliability and agreement with IVP in patients undergoing elective abdominal surgery.</p> <p>Methods</p> <p>A prospective cohort study was performed in 20 patients randomly scheduled to receive PRM either by a Coach^®-probe or an Accurate++^®-probe (both MIPM, Mammendorf, Germany). Probes were placed on the greater omentum and passed through the abdominal wall paralleling routine drainages. PRM was compared with IVP measurement by t-testing and by calculating mean difference as well as limits of agreement (LA).</p> <p>Results</p> <p>There were no probe related complications. Due to technical limitations, data could be collected in 3/10 patients with Coach^®and in 7/10 patients with Accurate++^®. Analysis was carried out only for Accurate++^®. Mean values did not differ to mean IVP values. Mean difference to IVP was 0.1 ± 2.8 mmHg (LA: -5.5 to 5.6 mmHg).</p> <p>Conclusion</p> <p>Direct IAP measurement was clinically uneventful. Although results of Accurate++^®were comparable to IVP, the device might be too fragile for IAP measurements in the clinical setting. Local ethical committee trial registration: EK2024</p

Ultrasound enhanced prehospital thrombolysis using microbubbles infusion in patients with acute ST elevation myocardial infarction: Rationale and design of the Sonolysis study

Contains fulltext : 70525.pdf (publisher's version ) (Open Access)ABSTRACT: BACKGROUND -: Experimental studies have shown that ultrasound contrast agents enhance the effectiveness of thrombolytic agents in the presence of ultrasound in vitro and in vivo. Recently, we have launched a clinical pilot study, called "Sonolysis", to study this effect in patients with ST-elevation myocardial infarction based on proximal lesions of the infarct-related artery. METHODS/DESIGN -: In our multicenter, randomized, placebo controlled clinical trial we will include patients between 18 and 80 years of age with their first ST-elevation myocardial infarction based on a proximal lesion of the infarct-related artery. After receiving a single bolus alteplase 50 mg IV (Actilyse(R) Boehringer Ingelheim GmbH), a loading dose of aspirin 500 mg, and heparin 5000 IU in the ambulance according to the prehospital thrombolysis protocol, patients, following oral informed consent, are randomized to undergo 15 minutes of pulsatile ultrasound with intravenous administration of ultrasound contrast agent or placebo without ultrasound. Afterwards coronary angiography and, if indicated, percutaneous coronary intervention will take place. A total of 60 patients will be enrolled in approximately 1 year.The primary endpoints are based on the coronary angiogram and consist of TIMI flow, corrected TIMI frame count, and myocardial blush grade. Follow-up includes 12-lead ECG, 2D-echocardiography, cardiac MRI, and enzyme markers to obtain our secondary endpoints, including the infarct size, wall motion abnormalities, and the global left ventricular function. DISCUSSION -: The Sonolysis study is the first multicenter, randomized, placebo controlled clinical trial investigating the therapeutic application of ultrasound and microbubbles in acute ST-elevation myocardial infarction patients. A positive finding may stimulate further research and technical innovations to implement the treatment in the ambulance and maybe obtain even more patency at an earlier stage. TRIAL REGISTRATION -: Trialregister NTR161

Direct Heme Transfer Reactions in the Group A Streptococcus Heme Acquisition Pathway

The heme acquisition machinery in Group A Streptococcus (GAS) consists of the surface proteins Shr and Shp and ATP-binding cassette transporter HtsABC. Shp cannot directly acquire heme from methemoglobin (metHb) but directly transfers its heme to HtsA. It has not been previously determined whether Shr directly relays heme from metHb to Shp. Thus, the complete pathway for heme acquisition from metHb by the GAS heme acquisition machinery has remained unclear. In this study, the metHb-to-Shr and Shr-to-Shp heme transfer reactions were characterized by spectroscopy, kinetics and protein-protein interaction analyses. Heme is efficiently transferred from the β and α subunits of metHb to Shr with rates that are 7 and 60 times greater than those of the passive heme release from metHb, indicating that Shr directly acquires heme from metHb. The rapid heme transfer from Shr to Shp involves an initial heme donor/acceptor complex and a spectrally and kinetically detectable transfer intermediate, implying that heme is directly channeled from Shr to Shp. The present results show that Shr speeds up heme transfer from metHb to Shp, whereas Shp speeds up heme transfer from Shr to HtsA. Furthermore, the findings demonstrate that Shr can interact with metHb and Shp but not HtsA. Taken together with our published results on the Shp/HtsA reaction, these findings establish a model of the heme acquisition pathway in GAS in which Shr directly extracts heme from metHb and Shp relays it from Shr to HtsA

Measurement of the branching fraction and CP content for the decay B(0) -> D(*+)D(*-)

This is the pre-print version of the Article. The official published version can be accessed from the links below. Copyright @ 2002 APS.We report a measurement of the branching fraction of the decay B0→D*+D*- and of the CP-odd component of its final state using the BABAR detector. With data corresponding to an integrated luminosity of 20.4  fb-1 collected at the Υ(4S) resonance during 1999–2000, we have reconstructed 38 candidate signal events in the mode B0→D*+D*- with an estimated background of 6.2±0.5 events. From these events, we determine the branching fraction to be B(B0→D*+D*-)=[8.3±1.6(stat)±1.2(syst)]×10-4. The measured CP-odd fraction of the final state is 0.22±0.18(stat)±0.03(syst).This work is supported by DOE and NSF (USA), NSERC (Canada), IHEP (China), CEA and CNRS-IN2P3 (France), BMBF (Germany), INFN (Italy), NFR (Norway), MIST (Russia), and PPARC (United Kingdom). Individuals have received support from the A.P. Sloan Foundation, Research Corporation, and Alexander von Humboldt Foundation

Trabalho de consenso de força-tarefa da WFSBP sobre marcadores biológicos das demências: contribuição da análise do LCR e do sangue para o diagnóstico precoce e diferencial das demências

Aging of population, and increasing life expectancy result in an increasing number of patients with dementia. This symptom can be a part of a completely curable disease of the central nervous system (e.g, neuroinflammation), or a disease currently considered irreversible (e.g, Alzheimer's disease, AD). In the latter case, several potentially successful treatment approaches are being tested now, demanding reasonable standards of pre-mortem diagnosis. Cerebrospinal fluid and serum analysis (CSF/serum analysis), whereas routinely performed in neuroinflammatory diseases, still requires standardization to be used as an aid to the clinically based diagnosis of AD. Several AD-related CSF parameters (total tau, phosphorylated forms of tau, Aß peptides, ApoE genotype, p97, etc.) tested separately or in a combination provide sensitivity and specificity in the range of 85%, the figure commonly expected from a good diagnostic tool. In this review, recently published reports regarding progress in neurochemical pre-mortem diagnosis of dementias are discussed with a focus on an early and differential diagnosis of AD. Novel perspectives offered by recently introduced technologies, e.g, fluorescence correlation spectroscopy (FCS) and surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) are briefly discussed.O envelhecimento da população e o aumento da expectativa de vida resultam em um número cada vez maior de pacientes com demência. Os déficits cognitivos podem ser manifestações de uma doença curável do sistema nervoso central (por exemplo, neuroinflamação), como também de uma doença atualmente considerada irreversível, como a doença de Alzheimer (DA). Tendo em vista as novas abordagens terapêuticas para a DA, em que se avalia o potencial modificador da patogenia, torna-se necessário o estabelecimento de um diagnóstico confiável em vida. Embora a análise do líquido cefalorraquidiano (LCR) e do soro seja realização de rotina em doenças neuroinflamatórias, ainda necessita de padronização para ser usada como instrumento auxiliar no diagnóstico clínico da DA. Vários parâmetros relacionados à DA (tau total, formas fosforiladas de tau, peptídeos A&#946;, genótipo ApoE, p97 etc.) podem ser determinados no LCR. A combinação de alguns desses parâmetros proporciona sensibilidade e especificidade na faixa de 85% para o diagnóstico da DA, um valor usualmente atribuído a um bom instrumento de diagnóstico. Nesta revisão, são discutidas as publicações mais recentes sobre os marcadores neuroquímicos para o diagnóstico clínico das demências, com ênfase no diagnóstico precoce e diferencial da DA. Discutem-se brevemente as novas perspectivas oferecidas por tecnologias recentes, tais como a FCS (fluorescence correlation spectroscopy) e a técnica de espectrometria de massa pelo método SELDI-TOF (surface enhanced laser desorption/ionization time-of-flight mass spectrometry)