Recognition of Error Symptoms in Large Systems

Coordinated Science Laboratory was formerly known as Control Systems LaboratoryJoint Services Electronics Program / N00014-84-C-0149IBM Corporatio

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

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

Oligoclonal bands increase the specificity of MRI criteria to predict multiple sclerosis in children with radiologically isolated syndrome

Background: Steps towards the development of diagnostic criteria are needed for children with the radiologically isolated syndrome to identify children at risk of clinical demyelination. Objectives: To evaluate the 2005 and 2016 MAGNIMS magnetic resonance imaging criteria for dissemination in space for multiple sclerosis, both alone and with oligoclonal bands in cerebrospinal fluid added, as predictors of a first clinical event consistent with central nervous system demyelination in children with radiologically isolated syndrome. Methods: We analysed an international historical cohort of 61 children with radiologically isolated syndrome (18 years), defined using the 2010 magnetic resonance imaging dissemination in space criteria (Ped-RIS) who were followed longitudinally (mean 4.2 4.7 years). All index scans also met the 2017 magnetic resonance imaging dissemination in space criteria. Results: Diagnostic indices (95% confidence intervals) for the 2005 dissemination in space criteria, with and without oligoclonal bands, were: sensitivity 66.7% (38.4\u201388.2%) versus 72.7% (49.8\u201389.3%); specificity 83.3% (58.6\u201396.4%) versus 53.9% (37.2\u201369.9%). For the 2016 MAGNIMS dissemination in space criteria diagnostic indices were: sensitivity 76.5% (50.1\u201393.2%) versus 100% (84.6\u2013100%); specificity 72.7% (49.8\u201389.3%) versus 25.6% (13.0\u201342.1%). Conclusions: Oligoclonal bands increased the specificity of magnetic resonance imaging criteria in children with Ped-RIS. Clinicians should consider testing cerebrospinal fluid to improve diagnostic certainty. There is rationale to include cerebrospinal fluid analysis for biomarkers including oligoclonal bands in planned prospective studies to develop optimal diagnostic criteria for radiologically isolated syndrome in children

Oxidation of arsenite by Agrobacterium albertimagni, AOL15, sp. nov., isolated from Hot Creek, California

An arsenite-oxidizing bacterium, Agrobacterium albertimagni strain AOL15 (ATCC BAA-24), was isolated from the surface of aquatic macrophytes collected in Hot Creek, California. Under laboratory conditions, whole cell suspensions of AOL15 oxidized arsenite with a Ks of 3.4 ± 2.2 μM and a Vmax of 1.81 ± 0.58 × 10-12 μmole · cell-1 · min-1 (or 0.043 ± 0.017 μmole · mg protein-1 · min-1). The Ks value for AOL15 is the lowest value to date reported for whole cell suspensions and is comparable to ambient concentrations of arsenic of 2.7 μM reported for Hot Creek, indicating that AOL15 can oxidize arsenite under ambient conditions. Previous studies at this site revealed a rapid in situ oxidation of geothermally-derived arsenite while field incubation studies demonstrated that this oxidation was bacterially mediated. The isolation of the arsenite oxidizer AOL15 from this environment supports these previous observations. Arsenite does not support chemolithoautotrophic growth of AOL15 and toxicity studies with AOL15 showed that arsenite (at 5 mM) is toxic to AOL15, yet arsenate concentrations as high as 50 mM do not show any toxic effects. These results suggest that the oxidation of arsenite by AOL15 is a detoxification mechanism