A new alkali-thermostable azoreductase from Bacillus sp. strain SF

A screening for dye-decolorizing alkali-thermophilic microorganisms resulted in a Bacillus sp. strain isolated out of the wastewater drain of a textile finishing company. An NADH-dependent azoreductase of this strain, Bacillus sp. strain SF, was found to be responsible for the decolorization of azo dyes. This enzyme was purified by a combination of ammonium sulfate precipitation and anion-exchange and affinity chromatography and had a molecular mass of 61.6 kDa and an isoelectric point at pH 5.3. The pH optimum of the azoreductase depended on the substrate and was within the range of pHs 8 to 9, while the temperature maximum was reached at 80 degrees C. Decolorization only took place in the absence of oxygen and was enhanced by FAD, which was not consumed during the reaction. A 26% similarity of this azoreductase to chaperonin Cpn60 from a Bacillus sp. was found by peptide mass mapping experiments. Substrate specificities of the azoreductase were studied by using synthesized model substrates based on di-sodium-(R)-benzyl-azo-2,7-dihydroxy-3,6-disulfonyl-naphthaline. Those dyes with NO2 substituents, especially in the ortho position, were degraded fastest, while analogues with a methyl substitution showed the lowest degradation rates.     

Characterization of central nervous system structures by magnetic resonance diffusion anisotropy

Diffusion-weighted magnetic resonance imaging (MRI) provides information about tissue water diffusion. Diffusion anisotropy, which can be measured with diffusion tensor MRI, is a quantitative measure of the directional dependence of the diffusion restriction that is introduced by biological structures such as nerve fibers. Diffusion tensor MRI data was obtained in the brain, brain stem, and cervical spinal cord. For each region, scans were performed in four normal volunteers. Fractional anisotropy (FA), an index of diffusion anisotropy, was measured within regions of interest located in the corpus callosum, capsula interna, thalamus, caudate nucleus, putamen, brain cortex, pyramidal tract of the medulla, accessory olivary nucleus, dorsal olivary nucleus, inferior olivary nucleus, spinal white and gray matter. The highest FA value was measured in the corpus callosum (81 +/- 3%). The values of the other areas decreased in the following order: pyramidal tract in the medulla (72 +/- 1%), spinal white matter (65 +/- 4%), capsula interna (62 +/- 3%), accessory olivary nucleus (36 +/- 2%), spinal gray matter (35 +/- 5%), dorsal olivary nucleus in the medulla (29 +/- 2%), thalamus (28 +/- 2%), inferior olivary nucleus (15 +/- 2%), putamen (13 +/- 2%), caudate nucleus (13 +/- 2%), and brain cortex (9 +/- 1%). Our results indicate that the underlying fiber architecture, fiber density, and uniformity of nerve fiber direction affect anisotropy values of the various structures. Characterization of various central nervous system structures with diffusion anisotropy is possible and may be useful to monitor degenerative diseases in the central nervous system.     

Glial activation and pathological pain

Pain is a sensation we have all experienced. For most of us, the pain has been temporary. However, for patients with pathological pain, the pain experience is unending, with little hope for therapeutic relief. Pathological pain is characterized by an amplified response to normally innocuous stimuli, and an amplified response to acute pain. Pathological pain has long been described as the result of dysfunctional neuronal activity. While neuronal functioning is indeed altered, there is significant evidence showing that exaggerated pain is regulated by the activation of astrocytes and microglia. In exaggerated pain, astrocytes, and microglia are activated by neuronal signals including substance P, glutamate, and fractalkine. Activation of glia by these substances leads to the release of mediators that then act on other glia and neurons. These include a family of proteins called "proinflammatory cytokines" released from microglia and astrocytes. These cytokines have been shown to be critical mediators of exaggerated pain. Some patients with pathological pain also report "extra-territorial" and/or "mirror" image pain. That is, exaggerated pain is experienced not only in the area of trauma. In extra-territorial pain, pain is also perceived as arising from neighboring healthy tissues outside of the site of trauma. In the rare cases of mirror-image pain, such pain is perceived as arising from the healthy, corresponding body part on the opposite side of the body. New data suggest that activation of astrocyte communication via gap junctions may mediate such spread of pain. While traditional therapies for pathological pain have focused on neuronal targets, the following review describes glia as newly recognized mediators of exaggerated pain, and as new therapeutic targets. Moreover, the glial-neuronal interactions discussed here are likely not exclusive to pain, but rather are likely to play significant roles in other behavioral phenomena.     

A cradle for new proteins: trigger factor at the ribosome

Newly synthesized proteins leave the ribosome through a narrow tunnel in the large subunit. During ongoing synthesis, nascent protein chains are particularly sensitive to aggregation and degradation because they emerge from the ribosome in an unfolded state. In bacteria, the first protein to interact with nascent chains and facilitate their folding is the ribosome-associated chaperone trigger factor. Recently, crystal structures of trigger factor and of its ribosome-binding domain in complex with the large ribosomal subunit revealed that the chaperone adopts an extended 'dragon-shaped' fold with a large hydrophobic cradle, which arches over the exit of the ribosomal tunnel and shields newly synthesized proteins. These structural results, together with recent biochemical data on trigger factor and its interplay with other chaperones and factors that interact with the nascent chain, provide a comprehensive view of the role of trigger factor during co-translational protein folding.     

Morphogenesis of the branching reef coral Madracis mirabilis

Understanding external deciding factors in growth and morphology of reef corals is essential to elucidate the role of corals in marine ecosystems, and to explain their susceptibility to pollution and global climate change. Here, we extend on a previously presented model for simulating the growth and form of a branching coral and we compare the simulated morphologies to three-dimensional (3D) images of the coral species Madracis mirabilis. Simulation experiments and isotope analyses of M. mirabilis skeletons indicate that external gradients of dissolved inorganic carbon (DIC) determine the morphogenesis of branching, phototrophic corals. In the simulations we use a first principle model of accretive growth based on local interactions between the polyps. The only species-specific information in the model is the average size of a polyp. From flow tank and simulation studies it is known that a relatively large stagnant and diffusion dominated region develops within a branching colony. We have used this information by assuming in our model that growth is entirely driven by a diffusion-limited process, where DIC supply represents the limiting factor. With such model constraints it is possible to generate morphologies that are virtually indistinguishable from the 3D images of the actual colonies.     

Le développement de l’inventaire de dépistage ERIraos: un outil global d’appréciation du risque d’évolution psychotique

Adequate identification of patients for early intervention programmes requires reliable and valid assessment tools. Within the German Schizophrenia Network (Kompetenznetz Schizophrenie) a set of schedules for early detection of schizophrenia has been proposed: the Early Recognition Inventory ERIraos. ERIraos is a two-step procedure with a 17-item checklist used at step 1 by GPs, psychologists, teachers, while a comprehensive 110-item symptom list is applied at early intervention centres at the expert level. In addition, ERIraos allows the assessment of several risk factors for psychosis such as familial load, childhood deficiencies, alcohol and drug use by special modules. Some preliminary results are presented here. The frequency of the 17 checklist symptoms increases from the early to the late prodrome, and more specific symptoms occur over time. The 17 checklist symptoms are grouped by factor analysis to 5 factors (psychotic, depressive, disorganised, withdrawn, dysphoric). In addition to prodromal symptoms, most patients (86.2%) report at least one additional risk factor (mean: 1.7 risks). 68% demonstrate some schizotypal features, 53% report alcohol and/or drug consumption, 24% demonstrate some deficiency or delay in childhood development, 21% report definite obstetric or birth complications, and 10% have a family history of schizophrenia or some schizophrenia-like diagnosis in first degree relatives. So far, the results are of a preliminary nature, and when sufficient information on psychotic transitions is available, the predictive value of ERIraos will be determined.     

Choice of fluids in critically ill patients

Background

Fluids are by far the most commonly administered intravenous treatment in patient care. During critical illness, fluids are widely administered to maintain or increase cardiac output, thereby relieving overt tissue hypoperfusion and hypoxia.

Main text

Until recently, because of their excellent safety profile, fluids were not considered “medications”. However, it is now understood that intravenous fluid should be viewed as drugs. They affect the cardiovascular, renal, gastrointestinal and immune systems. Fluid administration should therefore always be accompanied by careful consideration of the risk/benefit ratio, not only of the additional volume being administered but also of the effect of its composition on the physiology of the patient. Apart from the need to constantly assess fluid responsiveness, it is also important to periodically reconsider the type of fluid being administered and the evidence regarding the relationship between specific disease states and different fluid solutions.

Conclusions

The current review presents the state of the art regarding fluid solutions and presents the existing evidence on routine fluid management of critically ill patients in specific clinical settings (sepsis, Adult Respiratory Distress Syndrome, major abdominal surgery, acute kidney injury and trauma).

     

Live Faecalibacterium prausnitzii induces greater TLR2 and TLR2/6 activation than the dead bacterium in an apical anaerobic co‐culture system

Inappropriate activation of intestinal innate immune receptors, such as toll‐like receptors (TLRs), by pathogenic bacteria is linked to chronic inflammation. In contrast, a “tonic” level of TLR activation by commensal bacteria is required for intestinal homeostasis. A technical challenge when studying this activation in vitro is the co‐culturing of oxygen‐requiring mammalian cells with obligate anaerobic commensal bacteria. To overcome this, we used a novel apical anaerobic co‐culture system to successfully adapt a TLR activation assay to be conducted in conditions optimised for both cell types. Live Faecalibacterium prausnitzii, an abundant obligate anaerobe of the colonic microbiota, induced higher TLR2 and TLR2/6 activation than the dead bacterium. This enhanced TLR induction by live F. prausnitzii, which until now has not previously been described, may contribute to maintenance of gastrointestinal homeostasis. This highlights the importance of using physiologically relevant co‐culture systems to decipher the mechanisms of action of live obligate anaerobes.