Ecotin protects Salmonella Typhimurium against the microbicidal activity of host proteases.

Salmonella enterica serovar Typhimurium causes acute diarrhea upon oral infection in humans. The harsh and proteolytic environment found in the gastrointestinal tract is the first obstacle that these bacteria face after infection. However, the mechanisms that allow Salmonella to survive the hostile conditions of the gut are poorly understood. The ecotin gene is found in an extensive range of known phyla of bacteria and it encodes a protein that has been shown to inhibit serine proteases. Thus, in the present work we studied the role of ecotin of Salmonella Typhimurium in host-pathogen interactions. We found that Salmonella Typhimurium Δ ecotin strain exhibited lower inflammation in a murine model of Salmonella induced colitis. The Δ ecotin mutant was more susceptible to the action of pancreatin and purified pancreatic elastase. In addition, the lack of ecotin led to impaired adhesion to Caco-2 and HT-29 cell lines, related to the proteolytic activity of brush border enzymes. Besides, Δ ecotin showed higher susceptibility to lysosomal proteolytic content and intracellular replication defects in macrophages. In addition, we found Ecotin to have a crucial role in Salmonella against the microbicide action of granules released and neutrophil extracellular traps from human polymorphonuclear leukocytes. Thus, the work presented here highlights the importance of ecotin in Salmonella as countermeasures against the host proteolytic defense system. IMPORTANCE: The gastrointestinal tract is a very complex and harsh environment. Salmonella is a successful food borne pathogen, but little is known about its capacity to survive against the proteolysis of the gut lumen and intracellular proteases. Here, we show that Ecotin, a serine protease inhibitor, plays an important role in protecting Salmonella against proteases present at different sites encountered during oral infection. Our results indicate that Ecotin is an important virulence factor in Salmonella , adding another tool to the wide range of features this pathogen uses during oral infection.

New thermal decomposition pathway for TATB.

Understanding the thermal decomposition behavior of TATB (1,3,5-triamino-2,4,6-trinitrobenzene) is a major focus in energetic materials research because of safety issues. Previous research and modelling efforts have suggested benzo-monofurazan condensation producing H2O is the initiating decomposition step. However, early evolving CO2 (m/z 44) along with H2O (m/z 18) evolution have been observed by mass spectrometric monitoring of head-space gases in both constant heating rate and isothermal decomposition studies. The source of the CO2 has not been explained, until now. With the recent successful synthesis of 13C6-TATB (13C incorporated into the benzene ring), the same experiments have been used to show the source of the CO2 is the early breakdown of the TATB ring, not adventitious C from impurities and/or adsorbed CO2. A shift in mass m/z 44 (CO2) to m/z 45 is observed throughout the decomposition process indicating the isotopically labeled 13C ring breakdown occurs at the onset of thermal decomposition along with furazan formation. Partially labeled (N18O2)3-TATB confirms at least some of the oxygen comes from the nitro-groups. This finding has a significant bearing on decomposition computational models for prediction of energy release and deflagration to detonation transitions, with respect to conditions which currently do not recognize this oxidation step.

YeiE Regulates Motility and Gut Colonization in Salmonella enterica Serotype Typhimurium.

Regulation of flagellum biosynthesis is a hierarchical process that is tightly controlled to allow for efficient tuning of flagellar expression. Flagellum-mediated motility directs Salmonella enterica serovar Typhimurium toward the epithelial surface to enhance gut colonization, but flagella are potent activators of innate immune signaling, so fine-tuning flagellar expression is necessary for immune avoidance. In this work, we evaluate the role of the LysR transcriptional regulator YeiE in regulating flagellum-mediated motility. We show that yeiE is necessary and sufficient for swimming motility. A ΔyeiE mutant is defective for gut colonization in both the calf ligated ileal loop model and the murine colitis model due to its lack of motility. Expression of flagellar class 2 and 3 but not class 1 genes is reduced in the ΔyeiE mutant. We linked the motility dysregulation of the ΔyeiE mutant to repression of the anti-FlhD4C2 factor STM1697. Together, our results indicate that YeiE promotes virulence by enhancing cell motility, thereby providing a new regulatory control point for flagellar expression in Salmonella Typhimurium. IMPORTANCE The ability to finely tune virulence factor gene expression is required for bacterial pathogens to successfully colonize a host. Flagellum-mediated motility is critical for many gut pathogens to establish productive infections. However, flagella activate the immune system, leading to bacterial clearance; therefore, tight control of flagellar gene expression enhances bacterial fitness in the host. Here, we demonstrate that the transcriptional regulator YeiE acts as a control point for flagellar gene expression and is required for Salmonella Typhimurium to establish a productive infection in mammals. The expression of an inhibitor of flagellar biogenesis is repressed in the absence of yeiE. Our work adds a new layer to the tightly controlled cascade regulating control of flagellar gene expression to facilitate the fitness of an enteric pathogen.

Canadian Stroke Best Practice Recommendations for Acute Stroke Management: Prehospital, Emergency Department, and Acute Inpatient Stroke Care, 6th Edition, Update 2018.

The 2018 update of the Canadian Stroke Best Practice Recommendations for Acute Stroke Management, 6th edition, is a comprehensive summary of current evidence-based recommendations, appropriate for use by healthcare providers and system planners caring for persons with very recent symptoms of acute stroke or transient ischemic attack. The recommendations are intended for use by a interdisciplinary team of clinicians across a wide range of settings and highlight key elements involved in prehospital and Emergency Department care, acute treatments for ischemic stroke, and acute inpatient care. The most notable changes included in this 6th edition are the renaming of the module and its integration of the formerly separate modules on prehospital and emergency care and acute inpatient stroke care. The new module, Acute Stroke Management: Prehospital, Emergency Department, and Acute Inpatient Stroke Care is now a single, comprehensive module addressing the most important aspects of acute stroke care delivery. Other notable changes include the removal of two sections related to the emergency management of intracerebral hemorrhage and subarachnoid hemorrhage. These topics are covered in a new, dedicated module, to be released later this year. The most significant recommendation updates are for neuroimaging; the extension of the time window for endovascular thrombectomy treatment out to 24 h; considerations for treating a highly selected group of people with stroke of unknown time of onset; and recommendations for dual antiplatelet therapy for a limited duration after acute minor ischemic stroke and transient ischemic attack. This module also emphasizes the need for increased public and healthcare provider's recognition of the signs of stroke and immediate actions to take; the important expanding role of paramedics and all emergency medical services personnel; arriving at a stroke-enabled Emergency Department without delay; and launching local healthcare institution code stroke protocols. Revisions have also been made to the recommendations for the triage and assessment of risk of recurrent stroke after transient ischemic attack/minor stroke and suggested urgency levels for investigations and initiation of management strategies. The goal of this updated guideline is to optimize stroke care across Canada, by reducing practice variations and reducing the gap between current knowledge and clinical practice.

An investigation of reasoning by analogy in schizophrenia and autism spectrum disorder.

Relational reasoning ability relies upon by both cognitive and social factors. We compared analogical reasoning performance in healthy controls (HC) to performance in individuals with Autism Spectrum Disorder (ASD), and individuals with schizophrenia (SZ). The experimental task required participants to find correspondences between drawings of scenes. Participants were asked to infer which item within one scene best matched a relational item within the second scene. We varied relational complexity, presence of distraction, and type of objects in the analogies (living or non-living items). We hypothesized that the cognitive differences present in SZ would reduce relational inferences relative to ASD and HC. We also hypothesized that both SZ and ASD would show lower performance on living item problems relative to HC due to lower social function scores. Overall accuracy was higher for HC relative to SZ, consistent with prior research. Across groups, higher relational complexity reduced analogical responding, as did the presence of non-living items. Separate group analyses revealed that the ASD group was less accurate at making relational inferences in problems that involved mainly non-living items and when distractors were present. The SZ group showed differences in problem type similar to the ASD group. Additionally, we found significant correlations between social cognitive ability and analogical reasoning, particularly for the SZ group. These results indicate that differences in cognitive and social abilities impact the ability to infer analogical correspondences along with numbers of relational elements and types of objects present in the problems.

Diversity of the Cronobacter genus as revealed by multilocus sequence typing.

Cronobacter (previously known as Enterobacter sakazakii) is a diverse bacterial genus consisting of seven species: C. sakazakii, C. malonaticus, C. turicensis, C. universalis, C. muytjensii, C. dublinensis, and C. condimenti. In this study, we have used a multilocus sequence typing (MLST) approach employing the alleles of 7 genes (atpD, fusA, glnS, gltB, gyrB, infB, and ppsA; total length, 3,036 bp) to investigate the phylogenetic relationship of 325 Cronobacter species isolates. Strains were chosen on the basis of their species, geographic and temporal distribution, source, and clinical outcome. The earliest strain was isolated from milk powder in 1950, and the earliest clinical strain was isolated in 1953. The existence of seven species was supported by MLST. Intraspecific variation ranged from low diversity in C. sakazakii to extensive diversity within some species, such as C. muytjensii and C. dublinensis, including evidence of gene conversion between species. The predominant species from clinical sources was found to be C. sakazakii. C. sakazakii sequence type 4 (ST4) was the predominant sequence type of cerebral spinal fluid isolates from cases of meningitis.

Identification and characterization of Cronobacter iron acquisition systems.

Cronobacter spp. are emerging pathogens that cause severe infantile meningitis, septicemia, or necrotizing enterocolitis. Contaminated powdered infant formula has been implicated as the source of Cronobacter spp. in most cases, but questions still remain regarding the natural habitat and virulence potential for each strain. The iron acquisition systems in 231 Cronobacter strains isolated from different sources were identified and characterized. All Cronobacter spp. have both the Feo and Efe systems for acquisition of ferrous iron, and all plasmid-harboring strains (98%) have the aerobactin-like siderophore, cronobactin, for transport of ferric iron. All Cronobacter spp. have the genes encoding an enterobactin-like siderophore, although it was not functional under the conditions tested. Furthermore, all Cronobacter spp. have genes encoding five receptors for heterologous siderophores. A ferric dicitrate transport system (fec system) is encoded specifically by a subset of Cronobacter sakazakii and C. malonaticus strains, of which a high percentage were isolated from clinical samples. Phylogenetic analysis confirmed that the fec system is most closely related to orthologous genes present in human-pathogenic bacterial strains. Moreover, all strains of C. dublinensis and C. muytjensii encode two receptors, FcuA and Fct, for heterologous siderophores produced by plant pathogens. Identification of putative Fur boxes and expression of the genes under iron-depleted conditions revealed which genes and operons are components of the Fur regulon. Taken together, these results support the proposition that C. sakazakii and C. malonaticus may be more associated with the human host and C. dublinensis and C. muytjensii with plants.

Tracking cognitive phases in analogical reasoning with event-related potentials.

Analogical reasoning consists of multiple phases. Four-term analogies (A:B::C:D) have an encoding period in which the A:B pair is evaluated prior to a mapping phase. The electrophysiological timing associated with analogical reasoning has remained unclear. We used event-related potentials to identify neural timing related to analogical reasoning relative to perceptual and semantic control conditions. Spatiotemporal principal-components analyses revealed differences primarily in left frontal electrodes during encoding and mapping phases of analogies relative to the other conditions. The timing of the activity differed depending upon the phase of the problem. During the encoding of A:B terms, analogies elicited a positive deflection compared to the control conditions between 400 and 1,200 ms, but for the mapping phase analogical processing elicited a negative deflection that occurred earlier and for a shorter time period, between 350 and 625 ms. These results provide neural and behavioral evidence that 4-term analogy problems involve a highly active evaluation phase of the A:B pair.

The neural organization of perception in chess experts.

The human visual system responds to expertise, and it has been suggested that regions that process faces also process other objects of expertise including chess boards by experts. We tested whether chess and face processing overlap in brain activity using fMRI. Chess experts and novices exhibited face selective areas, but these regions showed no selectivity to chess configurations relative to other stimuli. We next compared neural responses to chess and to scrambled chess displays to isolate areas relevant to expertise. Areas within the posterior cingulate, orbitofrontal cortex, and right temporal cortex were active in this comparison in experts over novices. We also compared chess and face responses within the posterior cingulate and found this area responsive to chess only in experts. These findings indicate that the configurations in chess are not strongly processed by face-selective regions that are selective for faces in individuals who have expertise in both domains. Further, the area most consistently involved in chess did not show overlap with faces. Overall, these results suggest that expert visual processing may be similar at the level of recognition, but need not show the same neural correlates.

A hierarchy for relational reasoning in the prefrontal cortex.

The human brain possesses a unique capacity to reason about abstract relationships among items in our environment. The neural organization of reasoning abilities has remained elusive. Two approaches toward investigating human reasoning have involved studying visuo-spatial reasoning abilities and studying analogical reasoning. These approaches have both revealed anterior prefrontal cortex (PFC) involvement, but no prior studies have jointly investigated these two forms of reasoning to understand any potential convergence of activation within the PFC. Using fMRI, we tested the extent to which these two forms of reasoning (visuo-spatial and analogical) overlap in PFC activation. We conducted a visuo-spatial reasoning task that required processing multiple changes across three abstract pictures. This task activated a progressively anterior series of PFC regions when multiple relations had to be integrated. We also conducted a four-term analogy task in a stage-wise manner and compared results from this task to semantic and perceptual control conditions that did not require integrating relations across the problems. We found greater activation for analogical reasoning in the series of PFC regions that were sequentially involved in the visuo-spatial reasoning task. These findings indicate that stages of neural processing overlap for different domains within human reasoning. The pattern of differences across the analogy task suggests a hierarchical organization for relational reasoning across domains in which posterior frontal cortex is active across concrete reasoning tasks, while progressively more anterior regions are recruited to process increasingly abstract representations in reasoning.

Superimposed myasthenia gravis in chronic spinal cord injury: a case report.

STUDY DESIGN: Case report. BACKGROUND/OBJECTIVE: Myasthenia gravis (MG) complicating spinal cord injury (SCI) is extremely rare. We report a patient with SCI developing MG leading to death. There are no similar articles at present on literature search. CASE REPORT: A 54-year-old man, paralysed at the T12 level (ASIA A) for 40 years, was admitted for surgical repair of his grade IV sacral pressure sore. During the admission he developed diplopia, fluctuating dysphagia and slurred speech. Elevated anti-acetylcholine receptor antibodies and single fibre electromyography confirmed the diagnosis of MG and pyridostigmine was commenced. His admission was complicated by intermittent episodes of unexplained tachycardia and tachypnoea. He succumbed following cardio respiratory within 6 weeks of admission. Post mortem examination was inconclusive of a definite cause of death. In the presence of SCI, it can be challenging to diagnose MG or its complications like myasthenic and cholinergic crisis. CONCLUSION: The case highlights the difficulty in diagnosis and management of MG in persons with SCI.

An fMRI investigation of cognitive stages in reasoning by analogy.

We compared reasoning about four-term analogy problems in the format (A:B::C: D) to semantic and perceptual control conditions that required matching without analogical mapping. We investigated distinct phases of the problem solving process divided into encoding, mapping/inference, and response. Using fMRI, we assessed the brain activation relevant to each of these phases with an emphasis on achieving a better understanding of analogical reasoning relative to these other matching conditions. We predicted that the analogical condition would involve the most cognitive effort in the encoding and mapping/inference phases, while the control conditions were expected to engage greater prefrontal cortex (PFC) activation at the response period. Results showed greater activation for the analogical condition relative to the control conditions at the encoding phase in several predominantly left lateralized and medial areas of the PFC. Similar results were observed for the mapping/inference phase, though this difference was limited to the left PFC and rostral PFC. The response phase resulted in the fastest and most accurate responses in the analogy condition relative to the control conditions. This was accompanied by greater processing within the left lateral and the medial PFC for the control conditions relative to the analogy condition, consistent with most of the cognitive processing of the analogy condition having occurred in the prior task phases. Overall we demonstrate that the left ventral and dorsal lateral, medial, and rostral PFC are important in both the encoding of relational information, mapping and inference processes, and verification of semantic and perceptual responses in four term analogical reasoning.

A multi-centre study of the community needs of people with spinal cord injuries: the first 18 months.

STUDY DESIGN: Multi-centre, single cohort. OBJECTIVES: To assess the needs, perceived environmental barriers, level of participation and psychological function of spinal cord injured patients living in the community 3-18 months after discharge. SETTING: The National Spinal Injuries Centre, Stoke Mandeville, UK.; Princess Royal Spinal Injuries Centre, Sheffield UK.; Midlands Centre for Spinal Injuries, Oswestry, UK. METHOD: Participants sustaining injury aged 18 or above were recruited from one of three spinal cord injuries units 3-18 months after discharge. Postal packs containing questionnaires, consent forms and information were distributed and a 2-week reminder was sent. RESULTS: Main findings showed community needs to be generally well addressed however psychosocial needs were rated significantly lower than physical. Responses suggested no environmental impact on participation levels, however, qualitative data highlighted delays in accommodation, adaptations and availability of equipment to interfere with transition to community living. A substantial amount of respondents reported significant impact on independence and activity from secondary conditions and pain. Nearly all the sample reported dissatisfaction with their sexual life and these needs were not well addressed. CONCLUSIONS: Societal participation continues to be affected by secondary conditions and pain, whereas delays in equipment and structural adaptations impact on the transition to community living. Sexual needs and problems remain an issue for the spinal cord injured population and a need which is left unaddressed in the community.

Life satisfaction, appraisals and functional outcomes in spinal cord-injured people living in the community.

STUDY DESIGN: Multi-centre, single cohort. OBJECTIVES: To assess the relationship between cognitive appraisals in a spinal cord-injured population living in the community, and examine how these factors affect social participation, life satisfaction and functional outcomes. SETTING: The National Spinal Injuries Centre, Stoke Mandeville, UK; Princess Royal Spinal Injuries Centre, Sheffield UK; Midlands Centre for Spinal Injuries, Oswestry, UK. METHOD: Participants (n=81) sustaining injury aged 18 or above were recruited from one of three spinal cord injuries units 3-18 months after discharge. Postal packs containing questionnaires, consent forms and information were distributed and a 2-week reminder sent. RESULTS: Participation was found to be strongly related to life satisfaction, negative appraisals of disability were found to explain 12.9% of the variance in total participation scores. The variance in scores on Life Satisfaction Questionnaires was explained by appraisals, participation and secondary complications to a total of 69.6%. Functional Independence Scores were explained by negative perceptions of disability, growth and resilience and total secondary complication scores, explaining 49.4% of the variance in this measure. CONCLUSION: Participation, functional independence and life satisfaction were significantly related to appraisal styles in this population. Negative perceptions of disability, fearful despondency and overwhelming disbelief were themes that impacted on the likelihood of participation and independence and involved in expressed levels of life satisfaction. Our results suggest the need to tackle cognitive styles of SCI patients before discharge to improve the rehabilitation process.

Space flight alters bacterial gene expression and virulence and reveals a role for global regulator Hfq.

A comprehensive analysis of both the molecular genetic and phenotypic responses of any organism to the space flight environment has never been accomplished because of significant technological and logistical hurdles. Moreover, the effects of space flight on microbial pathogenicity and associated infectious disease risks have not been studied. The bacterial pathogen Salmonella typhimurium was grown aboard Space Shuttle mission STS-115 and compared with identical ground control cultures. Global microarray and proteomic analyses revealed that 167 transcripts and 73 proteins changed expression with the conserved RNA-binding protein Hfq identified as a likely global regulator involved in the response to this environment. Hfq involvement was confirmed with a ground-based microgravity culture model. Space flight samples exhibited enhanced virulence in a murine infection model and extracellular matrix accumulation consistent with a biofilm. Strategies to target Hfq and related regulators could potentially decrease infectious disease risks during space flight missions and provide novel therapeutic options on Earth.

Transient femoral nerve palsy associated with a synovial cyst of the hip in a patient with spinal cord injury.

We report a case of local compression-induced transient femoral nerve palsy in a 46-year-old man. He had previously undergone surgical release of the soft tissues anterior to both hip joints because of contractures following spinal injury. An MRI scan confirmed a synovial cyst originating from the left hip joint, lying adjacent to the femoral nerve. The cyst expanded on standing, causing a transient femoral nerve palsy. The symptoms resolved after excision of the cyst.

Modified Girdlestones-Taylor procedure for claw toes in spinal cord injury.

STUDY DESIGN: A combination of review of case notes and outpatient follow-up. OBJECTIVE: To evaluate the effectiveness of the modified Girdlestones-Taylor procedure in patients with spinal cord injury (SCI). SETTING: Princess Royal Spinal Injuries Centre (PRSIC), Northern General Hospital, Sheffield, UK. METHODS: Nine patients with claw toe deformities to 27 toes were treated at the PRSIC from 1996 to 2005. After examination of their medical records, their toes were assessed for pain, residual deformity and stiffness. They were also asked to grade their satisfaction with the surgical outcome. The results were tabulated. RESULTS: The average age of our series of patients was 43.3 years. The mean time from injury to surgery was 20.4 years and the mean time from surgery to last follow-up was 37.3 months. All our patients had good to excellent results, with over 70% of the toes having excellent results. CONCLUSION: The modified Girdlestones-Taylor procedure for claw toe correction appears to be a safe and effective treatment for patients with SCI.

Differences in gene content between Salmonella enterica serovar Enteritidis isolates and comparison to closely related serovars Gallinarum and Dublin.

Salmonella enterica serovar Enteritidis is often transmitted into the human food supply through eggs of hens that appear healthy. This pathogen became far more prevalent in poultry following eradication of the fowl pathogen S. enterica serovar Gallinarum in the mid-20th century. To investigate whether changes in serovar Enteritidis gene content contributed to this increased prevalence, and to evaluate genetic heterogeneity within the serovar, comparative genomic hybridization was performed on eight 60-year-old and nineteen 10- to 20-year-old serovar Enteritidis strains from various hosts, using a Salmonella-specific microarray. Overall, almost all the serovar Enteritidis genomes were very similar to each other. Excluding two rare strains classified as serovar Enteritidis in the Salmonella reference collection B, only eleven regions of the serovar Enteritidis phage type 4 (PT4) chromosome (sequenced at the Sanger Center) were absent or divergent in any of the other serovar Enteritidis strains tested. The more recent isolates did not have consistent differences from 60-year-old field isolates, suggesting that no large genomic additions on a whole-gene scale were needed for serovar Enteritidis to become more prevalent in domestic fowl. Cross-hybridization of phage genes on the array with related genes in the examined genomes grouped the serovar Enteritidis isolates into two major lineages. Microarray comparisons of the sequenced serovar Enteritidis PT4 to isolates of the closely related serovars Dublin and Gallinarum (biovars Gallinarum and Pullorum) revealed several genomic areas that distinguished them from serovar Enteritidis and from each other. These differences in gene content could be useful in DNA-based typing and in understanding the different phenotypes of these related serovars.