Genetic and biochemical characterization of hyicin 3682, the first bacteriocin reported for Staphylococcus hyicus

Publication date: Available online 12 February 2017
Source:Microbiological Research
Author(s): Patrícia Carlin Fagundes, Ilana Nascimento de Sousa Santos, Márcia Silva Francisco, Rodolpho Mattos Albano, Maria do Carmo de Freire Bastos
Hyicin 3682, the first bacteriocin reported for Staphylococcus hyicus, is a BsaCOL variant produced by S. hyicus 3682, a strain isolated from bovine milk. Hyicin 3682 is found in the culture supernatant, is bactericidal and its producing strain exhibits a much broader spectrum of antimicrobial activity than the producing strain of BsaCOL against several Gram-positive bacteria, which include food-borne pathogens, food-spoilage microorganisms and bacterial species of medical and veterinary importance. Sequencing of the genome of S. hyicus 3682 provided the nucleotide sequence of the entire gene cluster involved in hyicin 3682 production, which seems to be located on pRJ109, the single plasmid carried by this strain. This gene cluster is expressed and consists of 8,525bp and of eight genes (hyiA, hyiB, hyiC, hyiD, hyiP, hyiF, hyiE and hyiG) encoded on the same DNA strand. The mature lantibiotic Exhibits 91% identity to BsaCOL and its molecular mass was found to be ∼26Da higher due to two amino acid substitutions. S. hyicus 3682 proved to be only partially immune to its cognate bacteriocin up to 1,024 AU/ml. Therefore, hyicin 3682, the first Bsa variant reported in coagulase-negative staphylococci, does exhibit antimicrobial and siblicidal activities.



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Candida albicans infection and intestinal immunity

Publication date: Available online 13 February 2017
Source:Microbiological Research
Author(s): Yiqing Tong, Jianguo Tang
Fungal infections cause high rates of morbidity and mortality in intensive care and immunocompromised patients, and can represent a life-threatening disease. As a microorganism commonly found in the intestine, Candida albicans (C. albicans) can invade the gut epithelium barrier via microfold cells and enter the bloodstream. The defensive potential of the intestinal barrier against invasive C. albicans is dependent on innate and adaptive immune responses which enable the host to eliminate pathogenic fungi. The lamina propria layer of the intestine contains numerous immune cells capable of inducing an innate cellular immune response against invasive fungi. This review focuses on the immune response triggered by a C. albicans infection in the intestine.



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Computing and Comparing Effective Properties for Flow and Transport in Computer-Generated Porous Media

We compute effective properties (i.e., permeability, hydraulic tortuosity, and diffusive tortuosity) of three different digital porous media samples, including in-line array of uniform shapes, staggered-array of squares, and randomly distributed squares. The permeability and hydraulic tortuosity are computed by solving a set of rescaled Stokes equations obtained by homogenization, and the diffusive tortuosity is computed by solving a homogenization problem given for the effective diffusion coefficient that is inversely related to diffusive tortuosity. We find that hydraulic and diffusive tortuosity can be quantitatively different by up to a factor of ten in the same pore geometry, which indicates that these tortuosity terms cannot be used interchangeably. We also find that when a pore geometry is characterized by an anisotropic permeability, the diffusive tortuosity (and correspondingly the effective diffusion coefficient) can also be anisotropic. This finding has important implications for reservoir-scale modeling of flow and transport, as it is more realistic to account for the anisotropy of both the permeability and the effective diffusion coefficient.

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Piezoelectric Energy Generation from Vehicle Traffic with Technoeconomic Analysis

This paper presents a technical simulation based system to support the concept of generating energy from road traffic using piezoelectric materials. The simulation based system design replicates a real life system implementation. It investigates practicality and feasibility using a real-time simulation platform known as MATLAB-Simulink. The system design structure was proposed considering factors involved with the field of material sciences for piezoelectric generator modeling and field of power electronics for additional components in producing a realist outcome. It also ensures ease of vehicle performance, as this system utilizes energy source derived as kinetic energy released from vehicles into electrical power output, that is, obtained by harnessing kinetic energy due to strain of vehicles over asphalt road surface. Due to the real-time simulation platform, the system simulation predicts the effective global carbon footprint. In addition to evaluating technical viability, a technoeconomical business analysis provides a strategic perspective. By using the simulation based power generation results, an estimation of implementation cost and payback time in real life (for United Arab Emirates) was derived, hence validating and predicting real-time economic outcome. This is followed by a comparative study with other sources of renewable energy based on levelized energy cost factor that justifies the performance of the proposed system over other renewable energy sources, in support of providing an economical solution on reducing global carbon footprint.

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Ischemia/Reperfusion Injury following Acute Myocardial Infarction: A Critical Issue for Clinicians and Forensic Pathologists

Acute myocardial infarction (AMI) is a leading cause of morbidity and mortality. Reperfusion strategies are the current standard therapy for AMI. However, they may result in paradoxical cardiomyocyte dysfunction, known as ischemic reperfusion injury (IRI). Different forms of IRI are recognized, of which only the first two are reversible: reperfusion-induced arrhythmias, myocardial stunning, microvascular obstruction, and lethal myocardial reperfusion injury. Sudden death is the most common pattern for ischemia-induced lethal ventricular arrhythmias during AMI. The exact mechanisms of IRI are not fully known. Molecular, cellular, and tissue alterations such as cell death, inflammation, neurohumoral activation, and oxidative stress are considered to be of paramount importance in IRI. However, comprehension of the exact pathophysiological mechanisms remains a challenge for clinicians. Furthermore, myocardial IRI is a critical issue also for forensic pathologists since sudden death may occur despite timely reperfusion following AMI, that is one of the most frequently litigated areas of cardiology practice. In this paper we explore the literature regarding the pathophysiology of myocardial IRI, focusing on the possible role of the calpain system, oxidative-nitrosative stress, and matrix metalloproteinases and aiming to foster knowledge of IRI pathophysiology also in terms of medicolegal understanding of sudden deaths following AMI.

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Flexible conceptual combination: Electrophysiological correlates and consequences for associative memory

Abstract

When meaningful stimuli such as words are encountered in groups or pairs (e.g., “elephant-ferry”), they can be processed either separately or as an integrated concept (“an elephant ferry”). Prior research suggests that memory for integrated associations is supported by different mechanisms than is memory for nonintegrated associations. However, little is known about the neurocognitive mechanisms that support the integration of novel stimulus pairs. We recorded ERPs while participants memorized sequentially presented, unrelated noun pairs using a strategy that either did or did not involve attempting to construct coherent definitions. We varied the concreteness of the first noun in each pair to examine whether conceptual combination instructions would induce compositional concreteness effects, or differences in ERPs evoked by the second noun as a function of the concreteness of the first noun. We found that the conceptual combination task, but not the noncombinatory encoding task, produced compositional concreteness effects on a late frontal negativity previously linked to visual imagery. Moreover, word pairs studied under conceptual combination instructions showed evidence of more unitized or holistic memory representations on associative recognition and free recall tests. Finally, item analyses indicated that (a) items with higher normed imageability ratings were rated by participants as easier to conceptually combine, and (b) in the conceptual combination task, ease-of-combination ratings mediated an indirect relationship between imageability and subsequent associative memory. These data are suggestive of a role of compositional imagery in the online formation of novel concepts via conceptual combination.

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Evaluating the efficacy of fully automated approaches for the selection of eyeblink ICA components

Abstract

Independent component analysis (ICA) offers a powerful approach for the isolation and removal of eyeblink artifacts from EEG signals. Manual identification of the eyeblink ICA component by inspection of scalp map projections, however, is prone to error, particularly when nonartifactual components exhibit topographic distributions similar to the blink. The aim of the present investigation was to determine the extent to which automated approaches for selecting eyeblink-related ICA components could be utilized to replace manual selection. We evaluated popular blink selection methods relying on spatial features (EyeCatch), combined stereotypical spatial and temporal features (ADJUST), and a novel method relying on time series features alone (icablinkmetrics) using both simulated and real EEG data. The results of this investigation suggest that all three methods of automatic component selection are able to accurately identify eyeblink-related ICA components at or above the level of trained human observers. However, icablinkmetrics, in particular, appears to provide an effective means of automating ICA artifact rejection while at the same time eliminating human errors inevitable during manual component selection and false positive component identifications common in other automated approaches. Based upon these findings, best practices for (a) identifying artifactual components via automated means, and (b) reducing the accidental removal of signal-related ICA components are discussed.

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