Trapping of a Terminal Intermediate in the Boron-Mediated Dinitrogen Reduction: Mono-, Tri-, and Tetrafunctionalized Hydrazines in Two Steps from N2.

The addition of chlorotrimethylsilane to a boron-mediated, transition-metal-free N2 activation reaction leads to the isolation of multiple potassium boryl(silyl)hydrazido species, likely trapping products of a terminal dinitrogen complex of boron. One of these silylated N2 species can be protonated or methylated, providing access to mono- to tetrafunctionalized hydrazines in two steps from N2 and in the absence of transition metals.

Bypassing Ammonia: From N2 to Nitrogen Heterocycles without N1 Intermediates or Transition Metals.

Diboradiazene compounds, derived in one step from the boron-mediated reduction of dinitrogen (N2), were treated separately with sulfur and acetic anhydride, providing heterocyclic compounds that are BN isosteres of thiophene and 1,3-oxazole, respectively. These simple reactions represent the final steps in two-step routes to complex heterocycles from N2 that both circumvent the need for transition metal reagents and completely bypass the traditional intermediate ammonia.

Stochastic chain termination in bacterial pilus assembly.

Adhesive type 1 pili from uropathogenic Escherichia coli strains are filamentous, supramolecular protein complexes consisting of a short tip fibrillum and a long, helical rod formed by up to several thousand copies of the major pilus subunit FimA. Here, we reconstituted the entire type 1 pilus rod assembly reaction in vitro, using all constituent protein subunits in the presence of the assembly platform FimD, and identified the so-far uncharacterized subunit FimI as an irreversible assembly terminator. We provide a complete, quantitative model of pilus rod assembly kinetics based on the measured rate constants of FimD-catalyzed subunit incorporation. The model reliably predicts the length distribution of assembled pilus rods as a function of the ratio between FimI and the main pilus subunit FimA and is fully consistent with the length distribution of membrane-anchored pili assembled in vivo. The results show that the natural length distribution of adhesive pili formed via the chaperone-usher pathway results from a stochastic chain termination reaction. In addition, we demonstrate that FimI contributes to anchoring the pilus to the outer membrane and report the crystal structures of (i) FimI in complex with the assembly chaperone FimC, (ii) the FimI-FimC complex bound to the N-terminal domain of FimD, and (iii) a ternary complex between FimI, FimA and FimC that provides structural insights on pilus assembly termination and pilus anchoring by FimI.

Relations between character strengths, school satisfaction, enjoyment of learning, academic self-efficacy, and school achievement: An examination of various aspects of positive schooling.

This study is embedded in the theoretical framework of the engine model of positive schooling. Accordingly, relations were investigated between students' endogenous input variables (i.e., character strengths), process variables (i.e., school satisfaction, enjoyment of learning, and academic self-efficacy), and school achievement as an outcome variable. A sample of 300 students (between 10 and 17 years of age) completed web-based self-report measures for all key variables. Specific character strengths (e.g., love of learning, zest, hope, perseverance, and perspective) were substantially positively related to school satisfaction, enjoyment of learning, academic self-efficacy, and/or school achievement. Exploratory mediation analyses supported the basic assumption that processes (i.e., school satisfaction, enjoyment of learning, and academic self-efficacy) mediate the relations between character strengths as input variables and school achievement as an outcome variable. The findings underline the benefit of studying inputs, processes, and outcomes simultaneously to better understand the interplay among relevant variables in the context of positive schooling.

Spectroscopic glimpses of the transition state of ATP hydrolysis trapped in a bacterial DnaB helicase.

The ATP hydrolysis transition state of motor proteins is a weakly populated protein state that can be stabilized and investigated by replacing ATP with chemical mimics. We present atomic-level structural and dynamic insights on a state created by ADP aluminum fluoride binding to the bacterial DnaB helicase from Helicobacter pylori. We determined the positioning of the metal ion cofactor within the active site using electron paramagnetic resonance, and identified the protein protons coordinating to the phosphate groups of ADP and DNA using proton-detected 31P,1H solid-state nuclear magnetic resonance spectroscopy at fast magic-angle spinning > 100 kHz, as well as temperature-dependent proton chemical-shift values to prove their engagements in hydrogen bonds. 19F and 27Al MAS NMR spectra reveal a highly mobile, fast-rotating aluminum fluoride unit pointing to the capture of a late ATP hydrolysis transition state in which the phosphoryl unit is already detached from the arginine and lysine fingers.

Biomolecular solid-state NMR spectroscopy at 1200 MHz: the gain in resolution.

Progress in NMR in general and in biomolecular applications in particular is driven by increasing magnetic-field strengths leading to improved resolution and sensitivity of the NMR spectra. Recently, persistent superconducting magnets at a magnetic field strength (magnetic induction) of 28.2 T corresponding to 1200 MHz proton resonance frequency became commercially available. We present here a collection of high-field NMR spectra of a variety of proteins, including molecular machines, membrane proteins, viral capsids, fibrils and large molecular assemblies. We show this large panel in order to provide an overview over a range of representative systems under study, rather than a single best performing model system. We discuss both carbon-13 and proton-detected experiments, and show that in 13C spectra substantially higher numbers of peaks can be resolved compared to 850 MHz while for 1H spectra the most impressive increase in resolution is observed for aliphatic side-chain resonances.

Colorectal cancer incidence, mortality, and stage distribution in European countries in the colorectal cancer screening era: an international population-based study.

BACKGROUND: Colorectal cancer screening programmes and uptake vary substantially across Europe. We aimed to compare changes over time in colorectal cancer incidence, mortality, and stage distribution in relation to colorectal cancer screening implementation in European countries. METHODS: Data from nearly 3·1 million patients with colorectal cancer diagnosed from 2000 onwards (up to 2016 for most countries) were obtained from 21 European countries, and were used to analyse changes over time in age-standardised colorectal cancer incidence and stage distribution. The WHO mortality database was used to analyse changes over time in age-standardised colorectal cancer mortality over the same period for the 16 countries with nationwide data. Incidence rates were calculated for all sites of the colon and rectum combined, as well as the subsites proximal colon, distal colon, and rectum. Average annual percentage changes (AAPCs) in incidence and mortality were estimated and relevant patterns were descriptively analysed. FINDINGS: In countries with long-standing programmes of screening colonoscopy and faecal tests (ie, Austria, the Czech Republic, and Germany), colorectal cancer incidence decreased substantially over time, with AAPCs ranging from -2·5% (95% CI -2·8 to -2·2) to -1·6% (-2·0 to -1·2) in men and from -2·4% (-2·7 to -2·1) to -1·3% (-1·7 to -0·9) in women. In countries where screening programmes were implemented during the study period, age-standardised colorectal cancer incidence either remained stable or increased up to the year screening was implemented. AAPCs for these countries ranged from -0·2% (95% CI -1·4 to 1·0) to 1·5% (1·1 to 1·8) in men and from -0·5% (-1·7 to 0·6) to 1·2% (0·8 to 1·5) in women. Where high screening coverage and uptake were rapidly achieved (ie, Denmark, the Netherlands, and Slovenia), age-standardised incidence rates initially increased but then subsequently decreased. Conversely, colorectal cancer incidence increased in most countries where no large-scale screening programmes were available (eg, Bulgaria, Estonia, Norway, and Ukraine), with AAPCs ranging from 0·3% (95% CI 0·1 to 0·5) to 1·9% (1·2 to 2·6) in men and from 0·6% (0·4 to 0·8) to 1·1% (0·8 to 1·4) in women. The largest decreases in colorectal cancer mortality were seen in countries with long-standing screening programmes. INTERPRETATION: We observed divergent trends in colorectal cancer incidence, mortality, and stage distribution across European countries, which appear to be largely explained by different levels of colorectal cancer screening implementation. FUNDING: German Cancer Aid (Deutsche Krebshilfe) and the German Federal Ministry of Education and Research.

Incremental Validity of Character Strengths as Predictors of Job Performance Beyond General Mental Ability and the Big Five.

Over the last decades, various predictors have proven relevant for job performance [e.g., general mental ability (GMA), broad personality traits, such as the Big Five]. However, prediction of job performance is far from perfect, and further potentially relevant predictors need to be investigated. Narrower personality traits, such as individuals' character strengths, have emerged as meaningfully related to different aspects of job performance. However, it is still unclear whether character strengths can explain additional variance in job performance over and above already known powerful predictors. Consequently, the present study aimed at (1) examining the incremental validity of character strengths as predictors of job performance beyond GMA and/or the Big Five traits and (2) identifying the most important predictors of job performance out of the 24 character strengths, GMA, and the Big Five. Job performance was operationalized with multidimensional measures of both productive and counterproductive work behavior. A sample of 169 employees from different occupations completed web-based self-assessments on character strengths, GMA, and the Big Five. Additionally, the employees' supervisors provided web-based ratings of their job performance. Results showed that character strengths incrementally predicted job performance beyond GMA, the Big Five, or GMA plus the Big Five; explained variance increased up to 54.8, 43.1, and 38.4%, respectively, depending on the dimension of job performance. Exploratory relative weight analyses revealed that for each of the dimensions of job performance, at least one character strength explained a numerically higher amount of variance than GMA and the Big Five, except for individual task proactivity, where GMA exhibited the numerically highest amount of explained variance. The present study shows that character strengths are relevant predictors of job performance in addition to GMA and other conceptualizations of personality (i.e., the Big Five). This also highlights the role of socio-emotional skills, such as character strengths, for the understanding of performance outcomes above and beyond cognitive ability.

Dimer Organization of Membrane-Associated NS5A of Hepatitis†C Virus as Determined by Highly Sensitive 1 H-Detected Solid-State NMR.

The Hepatitis C virus nonstructural protein 5A (NS5A) is a membrane-associated protein involved in multiple steps of the viral life cycle. Direct-acting antivirals (DAAs) targeting NS5A are a cornerstone of antiviral therapy, but the mode-of-action of these drugs is poorly understood. This is due to the lack of information on the membrane-bound NS5A structure. Herein, we present the structural model of an NS5A AH-linker-D1 protein reconstituted as proteoliposomes. We use highly sensitive proton-detected solid-state NMR methods suitable to study samples generated through synthetic biology approaches. Spectra analyses disclose that both the AH membrane anchor and the linker are highly flexible. Paramagnetic relaxation enhancements (PRE) reveal that the dimer organization in lipids requires a new type of NS5A self-interaction not reflected in previous crystal structures. In conclusion, we provide the first characterization of NS5A AH-linker-D1 in a lipidic environment shedding light onto the mode-of-action of clinically used NS5A inhibitors.

Structural basis for DEAH-helicase activation by G-patch proteins.

RNA helicases of the DEAH/RHA family are involved in many essential cellular processes, such as splicing or ribosome biogenesis, where they remodel large RNA-protein complexes to facilitate transitions to the next intermediate. DEAH helicases couple adenosine triphosphate (ATP) hydrolysis to conformational changes of their catalytic core. This movement results in translocation along RNA, which is held in place by auxiliary C-terminal domains. The activity of DEAH proteins is strongly enhanced by the large and diverse class of G-patch activators. Despite their central roles in RNA metabolism, insight into the molecular basis of G-patch-mediated helicase activation is missing. Here, we have solved the structure of human helicase DHX15/Prp43, which has a dual role in splicing and ribosome assembly, in complex with the G-patch motif of the ribosome biogenesis factor NKRF. The G-patch motif binds in an extended conformation across the helicase surface. It tethers the catalytic core to the flexibly attached C-terminal domains, thereby fixing a conformation that is compatible with RNA binding. Structures in the presence or absence of adenosine diphosphate (ADP) suggest that motions of the catalytic core, which are required for ATP binding, are still permitted. Concomitantly, RNA affinity, helicase, and ATPase activity of DHX15 are increased when G-patch is bound. Mutations that detach one end of the tether but maintain overall binding severely impair this enhancement. Collectively, our data suggest that the G-patch motif acts like a flexible brace between dynamic portions of DHX15 that restricts excessive domain motions but maintains sufficient flexibility for catalysis.

Phosphinoborylenes as stable sources of fleeting borylenes.

Base-stabilised borylenes that mimic the ability of transition metals to bind and activate inert substrates have attracted significant attention in recent years. However, such species are typically highly reactive and fleeting, and often cannot be isolated at ambient temperature. Herein, we describe a readily accessible trimethylphosphine-stabilised borylborylene which was found to possess a labile P-B bond that reversibly cleaves upon gentle heating. Exchange of the labile phosphine with other nucleophiles (CO, isocyanide, 4-dimethylaminopyridine) was investigated, and the binding strength of a range of potential borylene "ligands" has been evaluated computationally. The room-temperature-stable PMe3-bound borylenes were subsequently applied to novel bond activations including [2 + 2] cycloaddition with carbodiimides and the reduction of dichalcogenides, revealing that PMe3-stabilised borylenes can effectively behave as stable sources of the analogous fleeting dicoordinate species under mild conditions.

Medico-legal assessment of methamphetamine and amphetamine serum concentrations-what can we learn from survived intoxications?

Medico-legal experts are increasingly enlisted to assess the methamphetamine and amphetamine serum concentrations after a criminal offense. However, since criminal users rarely provide useful information to medico-legal experts regarding the substances abused, when the substance(s) was/were used, dose of ingestion tools are needed to interpret the analytical data, which can be used as objective evidence in such cases. A comparative series of methamphetamine and amphetamine serum concentrations were used to analyze the frequency of concentrations, to determine methamphetamine/amphetamine concentration ratios, and prove them as a tool to distinguish pure methamphetamine from mixed amphetamine/methamphetamine ingestion. Additionally, two cases of survived accidental methamphetamine intoxication, resulting from ingestion smuggling which was longitudinally monitored, and pharmacokinetic parameters were assessed. In a series of 628 samples where the most frequent concentration of methamphetamine exceeded the therapeutic level, there was a strong correlation suggesting pure methamphetamine consumption, when the ratios of methamphetamine/amphetamine concentrations were within the range between 3 and 10. In the two cases of methamphetamine bodypacking, the relevant serum concentrations of methamphetamine and amphetamine, which could be measured up to 9 days after ingestion, indicated a decrease of the methamphetamine/amphetamine ratios in an exponential manner. However, the ratios were not always within the range between 3 and 10. Lastly, the course of the serum concentrations suggested an increase of the apparent elimination half-life of methamphetamine. In terms of the objective evidence required in criminal law, calculating methamphetamine/amphetamine concentration ratio is not a suitable to means to distinguish pure methamphetamine intake and that of mixed amphetamine/methamphetamine abuse in an individual case. Instead, methamphetamine high serum concentrations and the possible increase in apparent elimination half-life suggest that an extended detection period may be used to distinguish between "illicit use" as compared to "therapeutic use" of methamphetamine.

Multiscale dispersion-state characterization of nanocomposites using optical coherence tomography.

Nanocomposite materials represent a success story of nanotechnology. However, development of nanomaterial fabrication still suffers from the lack of adequate analysis tools. In particular, achieving and maintaining well-dispersed particle distributions is a key challenge, both in material development and industrial production. Conventional methods like optical or electron microscopy need laborious, costly sample preparation and do not permit fast extraction of nanoscale structural information from statistically relevant sample volumes. Here we show that optical coherence tomography (OCT) represents a versatile tool for nanomaterial characterization, both in a laboratory and in a production environment. The technique does not require sample preparation and is applicable to a wide range of solid and liquid material systems. Large particle agglomerates can be directly found by OCT imaging, whereas dispersed nanoparticles are detected by model-based analysis of depth-dependent backscattering. Using a model system of polystyrene nanoparticles, we demonstrate nanoparticle sizing with high accuracy. We further prove the viability of the approach by characterizing highly relevant material systems based on nanoclays or carbon nanotubes. The technique is perfectly suited for in-line metrology in a production environment, which is demonstrated using a state-of-the-art compounding extruder. These experiments represent the first demonstration of multiscale nanomaterial characterization using OCT.

Alterations of neuronal precursor cells in stages of human adult neurogenesis in heroin addicts.

BACKGROUND: Adult neurogenesis has been shown to occur throughout life and different brain pathologies were demonstrated to be associated with altered neurogenesis. Here, an impact of heroin addiction on neurogenesis in humans is hypothesised. METHODS: Post mortem hippocampal specimens of drug addicts with known heroin abuse and a group of non-addictive control subjects were analysed, using antibodies indicating different stages of neurogenesis. The subgranular zone of the dentate gyrus was examined qualitatively and quantitatively. RESULTS: The data indicate (i) a decreased number of neural precursor cells, (ii) accompanied by low rates of proliferation and (iii) a marked loss of dendritic trees in targeting cells in heroin fatalities. (iv) The age-dependent increase of differentiating cells in the healthy controls was not observed in the addicts. Additionally, double immunofluorescence labelling indicated the precursor nature of Musashi-1 positive cells in the human subgranular zone of the dentate gyrus. CONCLUSIONS: Present data firstly demonstrate the influence of drug addiction with known heroin abuse on different developmental stages of progenitors in the dentate gyrus. The patterns of antibody staining suggest a distinct inhibition of neurogenesis at the stage of neural precursor cells and revealed morphological changes in targeting cells in cases of heroin addicts as compared to healthy controls. These alterations could be considerable for memory and cognitive deficits as well as addictive behaviour in chronic drug abusers and may give rise to specific pro-neurogenic therapies.

Changes of the GPR17 receptor, a new target for neurorepair, in neurons and glial cells in patients with traumatic brain injury.

Unveiling the mechanisms participating in the damage and repair of traumatic brain injury (TBI) is fundamental to develop new therapies. The P2Y-like GPR17 receptor has recently emerged as a sensor of damage and a key actor in lesion remodeling/repair in the rodent brain, but its role in humans is totally unknown. Here, we characterized GPR17 expression in brain specimens from seven intensive care unit TBI patients undergoing neurosurgery for contusion removal and from 28 autoptic TBI cases (and 10 control subjects of matched age and gender) of two university hospitals. In both neurosurgery and autoptic samples, GPR17 expression was strong inside the contused core and progressively declined distally according to a spatio-temporal gradient. Inside and around the core, GPR17 labeled dying neurons, reactive astrocytes, and activated microglia/macrophages. In peri-contused parenchyma, GPR17 decorated oligodendrocyte precursor cells (OPCs) some of which had proliferated, indicating re-myelination attempts. In autoptic cases, GPR17 expression positively correlated with death for intracranial complications and negatively correlated with patients' post-traumatic survival. Data indicate lesion-specific sequential involvement of GPR17 in the (a) death of irreversibly damaged neurons, (b) activation of microglia/macrophages remodeling the lesion, and (c) activation/proliferation of multipotent parenchymal progenitors (both reactive astrocytes and OPCs) starting repair processes. Data validate GPR17 as a target for neurorepair and are particularly relevant to setting up new therapies for TBI patients.

Quantitative analysis of astrogliosis in drug-dependent humans.

Drug addiction is a chronic, relapsing disease caused by neurochemical and molecular changes in the brain. In this human autopsy study qualitative and quantitative changes of glial fibrillary acidic protein (GFAP)-positive astrocytes in the hippocampus of 26 lethally intoxicated drug addicts and 35 matched controls are described. The morphological characterization of these cells reflected alterations representative for astrogliosis. But, neither quantification of GFAP-positive cells nor the Western blot analysis indicated statistical significant differences between drug fatalities versus controls. However, by semi-quantitative scoring a significant shift towards higher numbers of activated astrocytes in the drug group was detected. To assess morphological changes quantitatively, graph-based representations of astrocyte morphology were obtained from single cell images captured by confocal laser scanning microscopy. Their underlying structures were used to quantify changes in astroglial fibers in an automated fashion. This morphometric analysis yielded significant differences between the investigated groups for four different measures of fiber characteristics (Euclidean distance, graph distance, number of graph elements, fiber skeleton distance), indicating that, e.g., astrocytes in drug addicts on average exhibit significant elongation of fiber structures as well as two-fold increase in GFAP-positive fibers as compared with those in controls. In conclusion, the present data show characteristic differences in morphology of hippocampal astrocytes in drug addicts versus controls and further supports the involvement of astrocytes in human pathophysiology of drug addiction. The automated quantification of astrocyte morphologies provides a novel, testable way to assess the fiber structures in a quantitative manner as opposed to standard, qualitative descriptions.

The role of character strengths in adolescent romantic relationships: an initial study on partner selection and mates' life satisfaction.

The present study investigated the role of 24 character strengths in 87 adolescent romantic relationships focusing on their role in partner selection and their role in mates' life satisfaction. Measures included the Values in Action Inventory of Strengths for Youth, the Students' Life Satisfaction Scale, and an Ideal Partner Profiler for the composition of an ideal partner. Honesty, humor, and love were the most preferred character strengths in an ideal partner. Hope, religiousness, honesty, and fairness showed the most substantial assortment coefficients. Hierarchical regression analyses revealed targets' character strengths as explaining variance in targets' life satisfaction. Furthermore, to a lesser degree, specific character strengths of partners and couples' similarity in certain character strengths explained variance in targets' life satisfaction beyond targets' character strengths. This first research on this topic showed that character strengths play a significant role in adolescent romantic relationships.

Survived ileocecal blowout from compressed air.

Industrial accidents with compressed air entering the gastro-intestinal tract often run fatally. The pressures usually over-exceed those used by medical applications such as colonoscopy and lead to vast injuries of the intestines with high mortality. The case described in this report is of a 26-year-old man who was harmed by compressed air that entered through the anus. He survived because of fast emergency operation. This case underlines necessity of explicit instruction considering hazards handling compressed air devices to maintain safety at work. Further, our observations support the hypothesis that the mucosa is the most elastic layer of the intestine wall.

Modulation of NMDA receptor current in layer V pyramidal neurons of the rat prefrontal cortex by P2Y receptor activation.

Current responses to N-methyl-D-aspartate (NMDA) in layer V pyramidal neurons of the rat prefrontal cortex were potentiated by the P2 receptor agonists adenosine 5'-triphosphate (ATP) and uridine 5'-triphosphate (UTP). The failure of these nucleotides to induce inward current on fast local superfusion suggested the activation of P2Y rather than P2X receptors. The potentiation by ATP persisted in a Ca(2+)-free superfusion medium but was abolished by 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl) ester, cyclopiazonic acid, 7-nitroindazole, fluoroacetic acid, bafilomycin, and tetanus toxin, indicating that an astrocytic signaling molecule may participate. Because the metabotropic glutamate receptor (mGluR) agonists (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD) (group I/II) and (RS)-3,5-dihydroxyphenylglycine (group I) both imitated the effect of ATP and the group I mGluR antagonist 1-aminoindan-1,5-dicarboxylic acid or a combination of selective mGluR(1) (7-(hydroxyimino)-cyclopropa[b]chromen-1a-carboxylate) and mGluR(5) (2-methyl-6-(phenylethynyl)pyridine) antagonists abolished the facilitation by ATP, it was concluded that the signaling molecule may be glutamate. Pharmacological tools known to interfere with the transduction cascade of type I mGluRs (guanosine 5'-O-(3-thiodiphosphate), U-73122, xestospongin C, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, calmodulin kinase II [CAMKII] inhibitor peptide) depressed the actions of both ATP and ACPD. Characterization of the P2Y receptor by agonists (ATP and UTP), antagonists (suramin and pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid), and knockout mice (P2Y(2)(-/-)) suggested that the nucleotides act at the P2Y(4) subtype. In conclusion, we propose that exogenous and probably also endogenous ATP release vesicular glutamate from astrocytes by P2Y(4) receptor activation. This glutamate then stimulates type I mGluRs of layer V pyramidal neurons and via the G(q)/phospholipase C/inositol 1,4,5-trisphosphate/Ca(2+)/CAMKII transduction pathway facilitates NMDA receptor currents.