The Role of Hydrogen for Sulfurimonas denitrificans’ Metabolism

Sulfurimonas denitrificans was originally isolated from coastal marine sediments. It can grow with thiosulfate and nitrate or sulfide and oxygen. Recently sequencing of its genome revealed that it encodes periplasmic and cytoplasmic [NiFe]-hydrogenases but the role of hydrogen for its metabolism has remained unknown. We show the first experimental evidence that S. denitrificans can indeed express a functional hydrogen uptake active hydrogenase and can grow on hydrogen. In fact, under the provided conditions it grew faster and denser on hydrogen than on thiosulfate alone and even grew with hydrogen in the absence of reduced sulfur compounds. In our experiments, at the time points tested, the hydrogen uptake activity appeared to be related to the periplasmic hydrogenase and not to the cytoplasmic hydrogenase. Our data suggest that under the provided conditions S. denitrificans can grow more efficiently with hydrogen than with thiosulfate.     

BNP but Not s-cTnln Is Associated with Cardioembolic Aetiology and Predicts Short and Long Term Prognosis after Cerebrovascular Events

Background

We analyzed the prognostic value of b-type natriuretic peptide (BNP) and sensitive cardiac Troponin (s-cTnI) in patients with ischemic stroke or transient ischemic attack (TIA) and their significance in predicting stroke aetiology.

Methods

In a prospectively enrolled cohort we measured BNP and s-cTnI levels upon admission. Primary endpoints were mortality, unfavorable functional outcome and stroke recurrence after 90 days and after 12 months. Secondary endpoint was cardioembolic aetiology.

Results

In 441 patients BNP but not s-cTnI remained an independent predictor for death with an adjusted HR of 1.2 (95% CI 1.1–1.4) after 90 days and 1.2 (95% CI 1.0–1.3) after one year. The comparison of the Area under Receiver Operating Characteristic (AUROC) of model A (age, NIHSS) and model B (age, NIHSS, BNP) showed an improvement in the prediction of mortality (0.85 (95% CI 0.79–0.90) vs. 0.86 (95% CI 0.81–0.92), Log Rank p = 0.004). Furthermore the category free net reclassification improvement (cfNRI) when adding BNP to the multivariate model was 57.5%, p<0.0001. For the prediction of functional outcome or stroke recurrence both markers provided no incremental value. Adding BNP to a model including age, atrial fibrillation and heart failure lead to a higher discriminatory accuracy for identification of cardioembolic stroke than the model without BNP (AUC 0.75 (95% CI 0.70–0.80) vs. AUC 0.79, (95% CI 0.75–0.84), p = 0.008).

Conclusion

BNP is an independent prognostic maker for overall mortality in patients with ischemic stroke or TIA and may improve the diagnostic accuracy to identify cardioembolic aetiology.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00390962","term_id":"NCT00390962"}}NCT00390962     

Optimizing Membrane Protein Overexpression in the Escherichia coli strain Lemo21(DE3)

Escherichia coli BL21(DE3) is widely used to overexpress proteins. In this overexpression host, the gene encoding the target protein is located on a plasmid and is under control of the T7 promoter, which is recognized exclusively by the T7 RNA polymerase (RNAP). The T7 RNAP gene is localized on the chromosome, and its expression is governed by the non-titratable, IPTG-inducible lacUV5 promoter. Recently, we constructed the Lemo21(DE3) strain, which allows improved control over the expression of genes from the T7 promoter. Lemo21(DE3) is a BL21(DE3) strain equipped with a plasmid harboring the gene encoding T7 lysozyme, an inhibitor of the T7 RNAP, under control of the exceptionally well-titratable rhamnose promoter. The overexpression yields of a large collection of membrane proteins in Lemo21(DE3) at different concentrations of rhamnose indicated that this strain may be very suitable for optimizing the production of membrane proteins. However, insight in the mechanism by which optimized expression yields are achieved in Lemo21(DE3) is lacking. Furthermore, whether the overexpressed proteins are suitable for functional and structural studies remains to be tested. Here, we show that in Lemo21(DE3), (i) the modulation of the activity of the T7 RNAP by the T7 lysozyme is key to optimizing the ratio of membrane proteins properly inserted in the cytoplasmic membrane to non-inserted proteins; (ii) maximizing the yields of membrane proteins is accompanied by reduction of the adverse effects of membrane protein overexpression, resulting in stable overexpression; and (iii) produced membrane proteins can be used for functional and structural studies.     

Cross talk between MyD88 and focal adhesion kinase pathways

Focal adhesion kinase (FAK) is a nonreceptor protein tyrosine kinase involved in signaling downstream of integrins, linking bacterial detection, cell entry, and initiation of proinflammatory response through MAPKs and NF-kappaB activation. In this study, using protein I/II from Streptococcus mutans as a model activator of FAK, we investigated the potential link between FAK and TLR pathways. Using macrophages from TLR- or MyD88-deficient mice, we report that MyD88 plays a major role in FAK-dependent protein I/II-induced cytokine release. However, response to protein I/II stimulation was independent of TLR4, TLR2, and TLR6. The data suggest that there is a cross talk between FAK and MyD88 signaling pathways. Moreover, MyD88-dependent, LPS-induced IL-6 secretion by human and murine fibroblasts required the presence of FAK, confirming that MyD88 and FAK pathways are interlinked.     

Prognostic factors in canine appendicular osteosarcoma - a meta-analysis

ABSTRACT: BACKGROUND: Appendicular osteosarcoma is the most common malignant primary canine bone tumor. When treated by amputation or tumor removal alone, median survival times (MST) do not exceed 5 months, with the majority of dogs suffering from metastatic disease. This period can be extended with adequate local intervention and adjuvant chemotherapy, which has become common practice. Several prognostic factors have been reported in many different studies, e.g. age, breed, weight, sex, neuter status, location of tumor, serum alkaline phosphatase (SALP), bone alkaline phosphatase (BALP), infection, percentage of bone length affected, histological grade or histological subtype of tumor. Most of these factors are, however, only reported as confounding factors in larger studies. Insight in truly significant prognostic factors at time of diagnosis may contribute to tailoring adjuvant therapy for individual dogs suffering from osteosarcoma.The objective of this study was to systematically review the prognostic factors that are described for canine appendicular osteosarcoma and validate their scientific importance. RESULTS: A literature review was performed on selected studies and eligible data were extracted. Meta-analyses were done for two of the three selected possible prognostic factors (SALP and location), looking at both survival time (ST) and disease free interval (DFI). The third factor (age) was studied in a qualitative manner. Both elevated SALP level and the (proximal) humerus as location of the primary tumor are significant negative prognostic factors for both ST and DFI in dogs with appendicular osteosarcoma. Increasing age was associated with shorter ST and DFI, however, was not statistically significant because information of this factor was available in only a limited number of papers. CONCLUSIONS: Elevated SALP and proximal humeral location are significant negative prognosticators for canine osteosarcoma.     

Weakened Resilience in Parenting Self-Efficacy in Pregnant Women Who Were Abused in Childhood: An Experimental Test

This study tested experimentally whether the combination of a history of childhood abuse and confrontation with difficult infant temperament is associated with negative changes in parenting self-efficacy. First-time pregnant women (N = 243) participated in the Adult Attachment Interview, which was used to assess the occurrence of abuse by parents in childhood and unresolved representations, and completed a task asking them to respond to infant cries. Sixty of the 243 participants (25%) experienced childhood abuse, mostly physical or sexual. The task simulated infant temperamental difficulty by manipulating soothing success in order to reflect an easy-to-soothe (80% soothing success) and a difficult-to-soothe infant (20% soothing success). Both after baseline and after each of the two stimulus series women assessed their parenting self-efficacy. Women who reported childhood abuse did not differ from women who reported no childhood abuse in parenting self-efficacy at baseline or in response to the easy-to-soothe infant (relative to baseline), but decreased more in parenting self-efficacy following the difficult-to-soothe infant. Effects did not vary according to resolution of trauma. These findings suggest that in response to infant temperamental difficulty, women who experienced childhood abuse may more easily lose confidence in their parenting abilities, which underlines the importance of preparing at-risk women for the possible challenges that come along with parenthood.     

Immediate,lag and time window effects of meteorological factors on ST-elevation myocardial infarction incidence

The influence of several meteorological parameters on acute myocardial infarction (AMI) incidences with immediately and/or delayed effects has been widely reported. It remains unknown whether the individual AMI subtypes reveal similar patterns. To date, generally seasonal variation in ST elevation MI (STEMI) has been investigated. However, these approaches couldn’t detect the effects of changes in multiple meteorological variables on STEMI incidence within a specific season. Therefore, the aim of our study is to explore immediate, delayed and cumulative effects of average daily temperature, atmospheric pressure and humidity on nation-wide STEMI hospital admissions. We linked daily hospitals’ STEMI admission data with meteorological stations’ data according to the patient’s permanent residence. Subsequently, a multivariate analysis based on a main effect generalised linear model, assuming a log-link function with a Poisson distribution, was conducted. With the help of lags, we were able to analyse delayed effects, while the cumulative effects of specific meteorological variables were analysed utilising time windows. As a result, we confirmed immediate and delayed negative effect of low temperature and low relative humidity for all observed lags as well as cumulative average effects of low temperature and low relative humidity for all observed time windows. However, no delayed, single-day effect for atmospheric pressure was detected. Nevertheless, the cumulative average effect was confirmed in all time windows suggesting that prolonged low pressure influences the incidence of STEMI. A novelty of our approach is the comparative examination of immediate, delayed and cumulative effect of specific meteorological variables on the incidence of STEMI. This approach enables us to gain a new insight into the phenomenon studied.     

Comparison of photosynthetic performances of marine picocyanobacteria with different configurations of the oxygen-evolving complex

The extrinsic PsbU and PsbV proteins are known to play a critical role in stabilizing the Mn₄CaO₅ cluster of the PSII oxygen-evolving complex (OEC). However, most isolates of the marine cyanobacterium Prochlorococcus naturally miss these proteins, even though they have kept the main OEC protein, PsbO. A structural homology model of the PSII of such a natural deletion mutant strain (P. marinus MED4) did not reveal any obvious compensation mechanism for this lack. To assess the physiological consequences of this unusual OEC, we compared oxygen evolution between Prochlorococcus strains missing psbU and psbV (PCC 9511 and SS120) and two marine strains possessing these genes (Prochlorococcus sp. MIT9313 and Synechococcus sp. WH7803). While the low light-adapted strain SS120 exhibited the lowest maximal O₂ evolution rates (P_max per divinyl-chlorophyll a, per cell or per photosystem II) of all four strains, the high light-adapted strain PCC 9511 displayed even higher P^Chl_max and P^PSII_max at high irradiance than Synechococcus sp. WH7803. Furthermore, thermoluminescence glow curves did not show any alteration in the B-band shape or peak position that could be related to the lack of these extrinsic proteins. This suggests an efficient functional adaptation of the OEC in these natural deletion mutants, in which PsbO alone is seemingly sufficient to ensure proper oxygen evolution. Our study also showed that Prochlorococcus strains exhibit negative net O₂ evolution rates at the low irradiances encountered in minimum oxygen zones, possibly explaining the very low O₂ concentrations measured in these environments, where Prochlorococcus is the dominant oxyphototroph.     

Quantification of the catalytic performance of C1-cellulose-specific lytic polysaccharide monooxygenases

Applied Microbiology and Biotechnology - Lytic polysaccharide monooxygenases (LPMOs) have recently been shown to significantly enhance the degradation of recalcitrant polysaccharides and are of...