211 research outputs found

    Characterization of Shewanella oneidensis MtrC: a cell-surface decaheme cytochrome involved in respiratory electron transport to extracellular electron acceptors

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    MtrC is a decaheme c-type cytochrome associated with the outer cell membrane of Fe(III)-respiring species of the Shewanella genus. It is proposed to play a role in anaerobic respiration by mediating electron transfer to extracellular mineral oxides that can serve as terminal electron acceptors. The present work presents the first spectropotentiometric and voltammetric characterization of MtrC, using protein purified from Shewanella oneidensis MR-1. Potentiometric titrations, monitored by UV–vis absorption and electron paramagnetic resonance (EPR) spectroscopy, reveal that the hemes within MtrC titrate over a broad potential range spanning between approximately +100 and approximately -500 mV (vs. the standard hydrogen electrode). Across this potential window the UV–vis absorption spectra are characteristic of low-spin c-type hemes and the EPR spectra reveal broad, complex features that suggest the presence of magnetically spin-coupled low-spin c-hemes. Non-catalytic protein film voltammetry of MtrC demonstrates reversible electrochemistry over a potential window similar to that disclosed spectroscopically. The voltammetry also allows definition of kinetic properties of MtrC in direct electron exchange with a solid electrode surface and during reduction of a model Fe(III) substrate. Taken together, the data provide quantitative information on the potential domain in which MtrC can operate

    Resuscitation Endpoints in Trauma

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    Fluid and blood resuscitation is the mainstay of therapy for the treatment of hemorrhagic shock, whether due to trauma or other etiology. Cessation of hemorrhage with rapid hemostatic techniques is the first priority in the treatment of traumatic hemorrhagic shock, with concomitant fluid resuscitation with blood and crystalloids to maintain perfusion and organ function. “Hypotensive” or “low-volume” resuscitation has become increasingly accepted in the prehospital resuscitation phase of trauma, prior to definitive hemorrhage control, since aggressive fluid resuscitation may increase bleeding. Resuscitation after hemorrhage control is focused on restoration of tissue oxygenation. Efforts to optimize resuscitation have used “resuscitation endpoints” as markers of adequacy of resuscitation. The resuscitation endpoints that have been evaluated include both global (restoration of blood pressure, heart rate and urine output, lactate, base deficit, mixed venous oxygen saturation, ventricular end-diastolic volume) and regional (gastric tonometry, near-infrared spectroscopy for measurement of muscle tissue oxygen saturation) measures. This review critically evaluates the evidence regarding the use of resuscitation endpoints in trauma.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75386/1/j.1778-428X.2005.tb00127.x.pd

    Zebrafish arl6ip1 Is Required for Neural Crest Development during Embryogenesis

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    BACKGROUND:Although the embryonic expression pattern of ADP ribosylation factor-like 6 interacting protein 1 (Arl6ip1) has been reported, its function in neural crest development is unclear. METHODS/PRINCIPAL FINDINGS:We found that knockdown of Arl6ip1 caused defective embryonic neural crest derivatives that were particularly severe in craniofacial cartilages. Expressions of the ectodermal patterning factors msxb, dlx3b, and pax3 were normal, but the expressions of the neural crest specifier genes foxd3, snai1b, and sox10 were greatly reduced. These findings suggest that arl6ip1 is essential for specification of neural crest derivatives, but not neural crest induction. Furthermore, we revealed that the streams of crestin- and sox10-expressing neural crest cells, which migrate ventrally from neural tube into trunk, were disrupted in arl6ip1 morphants. This migration defect was not only in the trunk neural crest, but also in the enteric tract where the vagal-derived neural crest cells failed to populate the enteric nervous system. We found that this migration defect was induced by dampened Shh signaling, which may have resulted from defective cilia. These data further suggested that arl6ip1 is required for neural crest migration. Finally, by double-staining of TUNEL and crestin, we confirmed that the loss of neural crest cells could not be attributed to apoptosis. CONCLUSIONS/SIGNIFICANCE:Therefore, we concluded that arl6ip1 is required for neural crest migration and sublineage specification

    Digital Traces of Distinction? Popular Orientation and User-Engagement with Status Hierarchies in TripAdvisor Reviews of Cultural Organizations

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    Cultural organizations are categorized by cultural products (high or popular culture) and by organizational form (nonprofit or commercial). In sociology, these classifications are understood predominantly through a Bourdieusian lens, which links cultural consumption to habitus and a class-based struggle for distinction. However, people’s engagement with institutionalized cultural classifications may be expressed differently on the Internet, where a culture of hierarchy-free equality is (sometimes) idealized. Using digital trace data from a representative sample of 280 user-generated reviews of four London cultural organizations, we find that reviewers are concerned with practical issues over cultural content, displaying a popular orientation to cultural consumption (an “audience-focus” or an “embodied” approach). A very small minority of reviewers claim status honor on a variety of bases, including symbolic mastery of traditional cultural capital. Overall, we find an online space in the cultural sphere in which cultural hierarchies are not relevant

    A phase II clinical trial of 6-mercaptopurine (6MP) and methotrexate in patients with BRCA defective tumours:a study protocol

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    BACKGROUND: BRCA1 and BRCA2 genes are critical in homologous recombination DNA repair and have been implicated in familial breast and ovarian cancer tumorigenesis. Tumour cells with these mutations demonstrate increased sensitivity to cisplatin and poly (ADP-ribose) polymerase (PARP) inhibitors. 6MP was identified in a screen for novel drugs and found to selectively kill BRCA-defective cells in a xenograft model as effectively as the PARP inhibitor AGO14699, even after these cells had acquired resistance to a PARP inhibitor or cisplatin. Exploiting the genetic basis of these tumours enables us to develop a more tailored approach to therapy for patients with BRCA mutated cancers. METHODS: This multi-centre phase II single arm trial was designed to investigate the activity and safety of 6-mercaptopurine (6MP) 55 mg/m² per day, and methotrexate 15 mg/m² per week in patients with advanced breast or ovarian cancer, ECOG PS 0-2, progressing after ≥ one prior regimen and known to bear a BRCA1/2 germ line mutation. Accrual was planned in two stages, with treatment continuing until progression or unacceptable toxicity; in the first, if less than 3/30 evaluable patients respond at 8 weeks after commencing treatment, the trial will be stopped for futility; if not, then accrual would proceed to a second stage, in which if more than 9/65 evaluable patients are found to respond at 8 weeks, the treatment will be regarded as potentially effective and a phase III trial considered subject to satisfactory safety and tolerability. The primary outcome is objective response at 8 weeks, defined by RECISTS v1.1 as complete response, partial response or stable disease. Secondary outcomes include safety, progression- free and overall survival, and quality of life. DISCUSSION: This study aims to investigate whether 6MP might be an effective treatment for BRCA deficient tumours even after the development of resistance to PARP inhibitors or platinum drugs. The study has surpassed the first stage analysis criteria of more than 3 out of 30 evaluable patients responding at 8 weeks, and is currently in the second stage of recruitment. TRIAL REGISTRATION: NCT01432145 http://www.ClinicalTrials.gov

    Tripping on Acid: Trans-Kingdom Perspectives on Biological Acids in Immunity and Pathogenesis

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