Bacillus cereus: Epidemiology, Virulence Factors, and Host-Pathogen Interactions

Bacillus cereus is an important human pathogen, and new findings have expanded our understanding of how this bacterium causes disease. B. cereus Hemolysin BL (HBL) and nonhemolytic enterotoxin (NHE) induce membrane pore formation, leading to activation of the NLRP3 inflammasome, systemic inflammation, and death. Lipopolysaccharide-induced tumor necrosis factor (TNF)-α factor (LITAF) and cell death-inducing P53 target 1 (CDIP1) are bona fide mammalian surface receptors of HBL. These newly identified toxin receptors and the NLRP3 inflammasome represent unique targets for potential future therapies against severe B. cereus infections. The toxin-producing bacterium Bacillus cereus is an important and neglected human pathogen and a common cause of food poisoning. Several toxins have been implicated in disease, including the pore-forming toxins hemolysin BL (HBL) and nonhemolytic enterotoxin (NHE). Recent work revealed that HBL binds to the mammalian surface receptors LITAF and CDIP1 and that both HBL and NHE induce potassium efflux and activate the NLRP3 inflammasome, leading to pyroptosis. These mammalian receptors, in part, contribute to inflammation and pathology. Other putative virulence factors of B. cereus include cytotoxin K, cereulide, metalloproteases, sphingomyelinase, and phospholipases. In this review, we highlight the latest progress in our understanding of B. cereus biology, epidemiology, and pathogenesis, and discuss potential new directions for research in this field.S.M.M. is supported by the Australian National University and the National Health and Medical Research Council of Australia under Project Grants (APP1141504, APP1146864, APP1162103 and APP1163358) and the R.D. Wright Career Development Fellowship (APP1162025). D.E.T. and S.M.M. are supported by Therapeutic Innovation Australia. D.E.T and A.M. are supported by The Gretel and Gordon Bootes Medical Research Foundation. A.M. is supported by a John Curtin School of Medical Research International PhD scholarshi

Assessment of microbial products in the biosorption process of Cu(II) onto aerobic granular sludge: Extracellular polymeric substances contribution and soluble microbial products release

© 2018 In the present study, the responses of microbial products in the biosorption process of Cu(II) onto aerobic granular sludge were evaluated by using batch and spectroscopic approaches. Batch experimental data showed that extracellular polymeric substances (EPSs) contributed to Cu(II) removal from an aqueous solution, especially when treating low metal concentrations, whereas soluble microbial products (SMPs) were released under the metal stress during biosorption process. A three-dimensional excitation-emission matrix (3D-EEM) identified four main fluorescence peaks in the EPS, i.e., tryptophan protein-like, aromatic protein-like, humic-like and fulvic acid-like substances, and their fluorescence intensities decreased gradually in the presence of Cu(II) during the sorption process. Particularly, tryptophan protein-like substances quenched the Cu(II) binding to a much higher extent through a static quenching process with less than one class of binding sites. According to the synchronous fluorescence spectra, the whole fluorescence intensity of released SMP samples expressed an increased trend with different degrees along with contact time. Two-dimensional correlation spectroscopy (2D-COS) suggested that the fulvic-like fluorescence fraction might be more susceptible to metal exposure than other fractions. The result of molecular weight distribution demonstrated that the SMPs released from the biosorption process differed significantly according to contact time. The result obtained could provide new insights into the responses of microbial products from aerobic granular sludge with heavy metal treatment

Determining the optimal range of vitamin C for early red drum (Sciaenops ocellatus) juveniles

Vitamin C plays an important role for fish survival, growth and disease resistance. However, the optimal vitamin C for rearing red drum Sciaenops ocellatus juveniles in Vietnam is not known. To address this issue, a 70-day feeding trial was conducted to evaluate the optimal dietary vitamin C requirements for red drum juveniles. Seven isonitrogenous (55.35% protein) and isolipidic (9.07% lipid) diets were formulated to include graded vitamin C concentrations of 23.2, 124.5, 235.2, 423.8, 626.7, 824.6, and 1,027.3 mg/kg, respectively. The results showed that fish fed on 423.8 mg/kg vitamin C diet had the highest growth rate, which can be linked to the increased feed utilization. Broken-line analysis indicated that the optimal dietary vitamin C requirements of red drum juveniles were 342.92 and 405.80 mg/kg for growth parameters, feed utilization, body composition and biochemical parameters of serum. Based on these parameters the optimal vitamin C supplementation level for red drum juveniles was estimated in the range of 342.92–405.80 mg/kg vitamin C in the diets with direct applications in producing artificial feed for rearing juveniles of this species in Vietnam

Hydrothermal Synthesis, Characterization, and Sintering Behavior of Core-Shell Particles: A Principle Study on Lanthanum Strontium Cobaltite Coated with Nanosized Gadolinium Doped Ceria

In this work, nanostructured (La0.6Sr0.4)0.99CoO3 (LSC)-Ce0.8Gd0.2O1.9 (CGO) core-shell particles were prepared by precipitating CGO nanoparticles on the surface of LSC particles under hydrothermal conditions. The as-prepared core-shell particles were sintered by spark plasma sintering (SPS) and conventional sintering, and the microstructure evolution and densification behavior were studied. Dense microstructures were reached using both sintering methods at relatively low temperatures. In the case of SPS, the core-shell architecture was partially maintained and nano-structured CGO grains were formed, while conventional sintering led to the formation of larger CGO grains. This work covers a detailed characterization of (a) the individual LSC-CGO core-shell particles and (b) the composites after densification

Bacillus cereus non-haemolytic enterotoxin activates the NLRP3 inflammasome

Inflammasomes are important for host defence against pathogens and homeostasis with commensal microbes. Here, we show non-haemolytic enterotoxin (NHE) from the neglected human foodborne pathogen Bacillus cereus is an activator of the NLRP3 inflammasome and pyroptosis. NHE is a non-redundant toxin to haemolysin BL (HBL) despite having a similar mechanism of action. Via a putative transmembrane region, subunit C of NHE initiates binding to the plasma membrane, leading to the recruitment of subunit B and subunit A, thus forming a tripartite lytic pore that is permissive to efflux of potassium. NHE mediates killing of cells from multiple lineages and hosts, highlighting a versatile functional repertoire in different host species. These data indicate that NHE and HBL operate synergistically to induce inflammation and show that multiple virulence factors from the same pathogen with conserved function and mechanism of action can be exploited for sensing by a single inflammasome

SECURE PERFORMANCE ANALYSIS OF ADAPTIVE ENERGY HARVESTING ENABLED RELAYING NETWORKS

In this paper, the impact of the jamming signal on the secrecy performance of Energy Harvesting (EH) enabled dual-hop amplify-and-forward relaying network is investigated. First, the security outage probability analysis is studied for conventional networks under a single passive eavesdropper attack. Then, the outage performance analysis in two cases regarding energy harvesting is investigated. Moreover, the proposed work enhances Physical Layer (PHY) security performance of two-hop relaying model using Cooperative Jamming Dual-Hop Techniques (CJDH). For this purpose, new closed-form expressions are derived for the outage probability of CJDH model in the presence of interference over Rayleigh fading channels. A power allocation optimization problem for energy harvesting protocol is formulated and solved for enhancing the system security. The derived analytical formulas herein are supported by numerical and simulation results to clarify the main contributions of the paper

Targeted next-generation sequencing on hirschsprung disease: A pilot study exploits DNA pooling

To adopt an efficient approach of identifying rare variants possibly related to Hirschsprung disease (HSCR), a pilot study was set up to evaluate the performance of a newly designed protocol for next generation targeted resquencing. In total, 20 Chinese HSCR patients and 20 Chinese sex-matched individuals with no HSCR were included, for which coding sequences (CDS) of 62 genes known to be in signaling pathways relevant to enteric nervous system development were selected for capture and sequencing. Blood DNAs from eight pools of five cases or controls were enriched by PCR-based RainDance technology (RDT) and then sequenced on a 454 FLX platform. As technical validation, five patients from case Pool-3 were also independently enriched by RDT, indexed with barcode and sequenced with sufficient coverage. Assessment for CDS single nucleotide variants showed DNA pooling performed well (specificity/sensitivity at 98.4%/83.7%) at the common variant level; but relatively worse (specificity/sensitivity at 65.5%/61.3%) at the rare variant level. Further Sanger sequencing only validated five out of 12 rare damaging variants likely involved in HSCR. Hence more improvement at variant detection and sequencing technology is needed to realize the potential of DNA pooling for large-scale resequencing projects. © 2014 John Wiley & Sons Ltd/University College London.postprin

Bridging dentistry and traditional Chinese medicine : a study on the current mutual understanding among the future practitioners

Objectives: This project aimed to promote the mutual understanding between dental and TCM students. The objectives were to describe the current teaching of dentistry in the TCM schools and that of TCM in the dental school, to describe the TCM students’ knowledge on dentistry and the dental students’ knowledge on TCM, and to produce promotional materials for enhancing the mutual understanding between dental and TCM students. Methods: Information on the current teaching of dentistry in the TCM schools and that of TCM in the dental school was collected through a search on the undergraduate programme syllabus and conducting interviews with the leaders of the schools. Questionnaire surveys were conducted among the final year students of the TCM and the dental schools to collect information on their knowledge of the counter profession. Two leaflets and a short video were produced with the aid of computer software and used in the promotional activities. Results: It was found that very little information on dentistry was covered in the undergraduate programmes of the three TCM schools, and vice versa in the dental school. A total of 39 TCM students and 55 dental students completed the questionnaire survey. Most of the students did not know the basic theories and practice of the counter profession. Less than half of the student knew what types of patient cases may be suitable for cross-referral to the other profession. Conclusions: The TCM and dental schools in Hong Kong do not have scheduled teaching on the counter profession. The TCM students have little knowledge on dentistry and how to collaborate with dental practitioners on patients presented with oral problems. Conversely, it is the same for the dental students. Lastly, informative printed and audio-visual promotional materials can be produced with limited resources and used to facilitate the mutual understanding between TCM and dental practitioners.published_or_final_versio

True versus Apparent Malaria Infection Prevalence: The Contribution of a Bayesian Approach

AIMS: To present a new approach for estimating the "true prevalence" of malaria and apply it to datasets from Peru, Vietnam, and Cambodia. METHODS: Bayesian models were developed for estimating both the malaria prevalence using different diagnostic tests (microscopy, PCR & ELISA), without the need of a gold standard, and the tests' characteristics. Several sources of information, i.e. data, expert opinions and other sources of knowledge can be integrated into the model. This approach resulting in an optimal and harmonized estimate of malaria infection prevalence, with no conflict between the different sources of information, was tested on data from Peru, Vietnam and Cambodia. RESULTS: Malaria sero-prevalence was relatively low in all sites, with ELISA showing the highest estimates. The sensitivity of microscopy and ELISA were statistically lower in Vietnam than in the other sites. Similarly, the specificities of microscopy, ELISA and PCR were significantly lower in Vietnam than in the other sites. In Vietnam and Peru, microscopy was closer to the "true" estimate than the other 2 tests while as expected ELISA, with its lower specificity, usually overestimated the prevalence. CONCLUSIONS: Bayesian methods are useful for analyzing prevalence results when no gold standard diagnostic test is available. Though some results are expected, e.g. PCR more sensitive than microscopy, a standardized and context-independent quantification of the diagnostic tests' characteristics (sensitivity and specificity) and the underlying malaria prevalence may be useful for comparing different sites. Indeed, the use of a single diagnostic technique could strongly bias the prevalence estimation. This limitation can be circumvented by using a Bayesian framework taking into account the imperfect characteristics of the currently available diagnostic tests. As discussed in the paper, this approach may further support global malaria burden estimation initiatives