Antimicrobial Activities and Mechanisms of Magnesium Oxide Nanoparticles (nMgO) against Pathogenic Bacteria, Yeasts, and Biofilms.

Magnesium oxide nanoparticle (nMgO) is a light metal based antimicrobial nanoparticle that can be metabolized and fully resorbed in the body. To take advantage of the antimicrobial properties of nMgO for medical use, it is necessary to determine the minimal inhibitory, bactericidal and fungicidal concentrations (MIC, MBC and MFC) of nMgO against prevalent infectious bacteria and yeasts. The objective of this study was to use consistent methods and conditions to reveal and directly compare the efficacy of nMgO against nine prevalent pathogenic microorganisms, including two gram-negative bacteria, three gram-positive bacteria with drug-resistant strains, and four yeasts with drug-resistant strains. The MIC of nMgO varied from 0.5 mg/mL to 1.2 mg/mL and the minimal lethal concentration (MLC) of nMgO at 90% killing varied from 0.7 mg/mL to 1.4 mg/mL against different pathogenic bacteria and yeasts. The most potent concentrations (MPC) of nMgO were 1.4 and/or 1.6 mg/mL, depending on the type of bacteria and yeasts tested. As the concentration of nMgO increased, the adhesion of bacteria and yeasts decreased. Moreover, S. epidermidis biofilm was disrupted at 1.6 mg/mL of nMgO. E. coli and some yeasts showed membrane damage after cultured with ≥0.5 mg/mL nMgO. Overall, nMgO killed both planktonic bacteria and disrupted nascent biofilms, suggesting new antimicrobial mechanisms of nMgO. Production of reactive oxygen species (ROS), Ca2+ ion concentrations, and quorum sensing likely contribute to the action mechanisms of nMgO against planktonic bacteria, but transient alkaline pH of 7 to 10 or increased Mg2+ ion concentrations from 1 to 50 mM showed no inhibitory or killing effects on bacteria such as S. epidermidis. Further studies are needed to determine if specific concentrations of nMgO at MIC, MLC or MPC level can be integrated into medical devices to evoke desired antimicrobial responses without harming host cells

Transcriptional signatures of somatic neoblasts and germline cells in <i>Macrostomum lignano</i>

The regeneration-capable flatworm <i>Macrostomum lignano</i> is a powerful model organism to study the biology of stem cells in vivo. As a flatworm amenable to transgenesis, it complements the historically used planarian flatworm models, such as <i>Schmidtea mediterranea</i>. However, information on the transcriptome and markers of stem cells in <i>M. lignano</i> is limited. We generated a de novo transcriptome assembly and performed the first comprehensive characterization of gene expression in the proliferating cells of <i>M. lignano</i>, represented by somatic stem cells, called neoblasts, and germline cells. Knockdown of a selected set of neoblast genes, including <i>Mlig-ddx39</i>, <i>Mlig-rrm1</i>, <i>Mlig-rpa3</i>, <i>Mlig-cdk1</i>, and <i>Mlig-h2a</i>, confirmed their crucial role for the functionality of somatic neoblasts during homeostasis and regeneration. The generated <i>M. lignano</i> transcriptome assembly and gene expression signatures of somatic neoblasts and germline cells will be a valuable resource for future molecular studies in <i>M. lignano</i>

Language, Truth, and Logic and the Anglophone reception of the Vienna Circle

A. J. Ayer’s Language, Truth, and Logic had been responsible for introducing the Vienna Circle’s ideas, developed within a Germanophone framework, to an Anglophone readership. Inevitably, this migration from one context to another resulted in the alteration of some of the concepts being transmitted. Such alterations have served to facilitate a number of false impressions of Logical Empiricism from which recent scholarship still tries to recover. In this paper, I will attempt to point to the ways in which LTL has helped to foster the various mistaken stereotypes about Logical Empiricism which were combined into the received view. I will begin by examining Ayer’s all too brief presentation of an Anglocentric lineage for his ideas. This lineage, as we shall see, simply omits the major 19th century Germanophone influences on the rise of analytic philosophy. The Germanophone ideas he presents are selectively introduced into an Anglophone context, and directed towards various concerns that arose within that context. I will focus on the differences between Carnap’s version of the overcoming of metaphysics, and Ayer’s reconfiguration into what he calls the elimination of metaphysics. Having discussed the above, I will very briefly outline the consequences that Ayer’s radicalisation of the Vienna Circle’s doctrines had on the subsequent Anglophone reception of Logical Empiricism

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