Cloning of bacteriophage lysins and evaluation of their antibacterial activity against Enterococcus faecalis

Enterococci are the causative agents of several serious infections. In addition, antibiotic- resistant enterococci are becoming increasingly prevalent due to the extensive use of antibiotics in the community and in hospitals. In this context, new antimicrobials acting by different mechanisms are highly desired. Lysins are bacteriophage-derived molecules that are produced when the bacteriophage (or phage) progeny needs to escape the bacterial host. Lysins very rapidly lyse the bacterial peptidoglycan. They can reach their target when added exogenously to Gram-positive bacteria, thanks to the lack of an impermeable outer membrane. In contrast, they are inactive when added externally to Gram-negative bacteria, which are surrounded by bilayer outer membrane. The action of lysins is normally restricted to bacterial hosts of the phages from which they were isolated, but some lysins have a broader spectrum of activity. In the present work, new lysins with a potentially lytic action against enterococci were identified by consulting a database of prophage sequences within bacterial genomes. Their amino acid sequences were analyzed in order to highlight both functional domains and possible differences with the previously described lysins. Three new lysins (plyEF, plyHH22 and plyE613) and the previously described enterococcal lysin plyV12 were studied. Cloning and purification were performed using several bacterial expression vectors with and without a C-terminal six-histidine tag. The expression and activity of lysins were screened by different methods. Recombinant host bacteria (E. coli BL21) were grown in various media and lysin expression was induced with IPTG. Induction of plyEF, plyHH22 and plyE613 readily blocked the growth of E. coli recipients, suggesting that they were toxic for this particular host. Thus, these enzymes could not be further purified. In contrast, induction of plyV12 did not block E. coli growth and the enzyme could be further studied. The latter results confirm the validity of our protocol. Moreover, we could also confirm the rapid lytic activity of plyV12 against E. faecalis ATCC 29212. The reason of the toxicity of plyEF, plyHH22 and plyE613 toward E. coli is as yet unclear and needs to be further explored

Individual monitoring of internal exposure for nuclear medicine workers in Switzerland

Monitoring of internal exposure for nuclear medicine workers requires frequent measurements due to the short physical half-lives of most radionuclides used in this field. The aim of this study was to develop screening measurements performed at the workplace by local staff using standard laboratory instrumentation, to detect whether potential intake has occurred. Such measurements do not enable to determine the committed effective dose, but are adequate to verify that a given threshold is not exceeded. For radioiodine, i.e. 123I, 124I, 125I and 131I, a calibrated surface contamination monitor is placed in front of the thyroid to detect whether the activity threshold has been exceeded. For radionuclides with very short physical half-lives (≤6 h), such as 99mTc and those used in positron emission tomography imaging, i.e. 11C, 15O, 18F and 68Ga, screening procedures consist in performing daily measurements of the ambient dose rate in front of the abdomen. Other gamma emitters used for imaging, i.e. 67Ga, 111In and 201Tl, are measured with a scintillation detector located in front of the thorax. For pure beta emitters, i.e. 90Y and 169Er, as well as beta emitters with low-intensity gamma rays, i.e. 153Sm, 177Lu, 186Re and 188Re, the procedure consists in measuring hand contamination immediately after use. In Switzerland, screening procedures have been adopted by most nuclear medicine services since such measurements enable an acceptable monitoring while taking into account practical and economic consideration

O−O Bond Formation and Liberation of Dioxygen Mediated by N5‐Coordinate Non‐Heme Iron(IV) Complexes

Formation of the O−O bond is considered the critical step in oxidative water cleavage to produce dioxygen. High‐valent metal complexes with terminal oxo (oxido) ligands are commonly regarded as instrumental for oxygen evolution, but direct experimental evidence is lacking. Herein, we describe the formation of the O−O bond in solution, from non‐heme, N5‐coordinate oxoiron(IV) species. Oxygen evolution from oxoiron(IV) is instantaneous once meta‐chloroperbenzoic acid is administered in excess. Oxygen‐isotope labeling reveals two sources of dioxygen, pointing to mechanistic branching between HAT (hydrogen atom transfer)‐initiated free‐radical pathways of the peroxides, which are typical of catalase‐like reactivity, and iron‐borne O−O coupling, which is unprecedented for non‐heme/peroxide systems. Interpretation in terms of [FeIV(O)] and [FeV(O)] being the resting and active principles of the O−O coupling, respectively, concurs with fundamental mechanistic ideas of (electro‐) chemical O−O coupling in water oxidation catalysis (WOC), indicating that central mechanistic motifs of WOC can be mimicked in a catalase/peroxidase setting.DFG, 12489635, SFB 658: Elementarprozesse in molekularen Schaltern auf OberflächenTU Berlin, Open-Access-Mittel - 201

Calibration and testing of a TLD dosemeter for area monitoring

The response of a TLD-600/TLD-700 area dosemeter has been characterized in neutron fields around the 590 MeV cyclotron ring at the Paul Scherrer Institute (PSI). The dosemeter is based on a cylindrical paraffin moderator with three of each type of TLD chip at the centre, and is intended to use for area monitoring around accelerator facilities. The dosemeter is calibrated in terms of ambient dose equivalent using a non-moderated 252Cf neutron source. The ambient dose equivalent response has been tested in five locations where the neutron fields and dose rates have been well characterized by Bonner sphere spectrometer and active neutron monitor measurements. The different spectrum shapes and dose rates in the five locations permit the comparison of the behavior of the active and passive dosemeters in these neutron field

Observer Reaction to Physical and Verbal Abuse in Relation to Gender and Sexual Orientation of Abuser and Victim

Advocating for victims of domestic violence has drastically evolved within the last few years through an increase of education and advocacy for victims, but there is still room for improvement. This study examines the relationship among gender of abuser, gender of victim, and type of abuse (physical or verbal) and participants reaction to witnessing domestic violence. In this experimental study, participants were randomly assigned to one of ten different vignettes describing a domestic violence scenario that varied the gender of the victim and the abuser, along with the type of abuse. Two of these vignettes did not mention the gender of the victim or abuser, only the type of abuse. Participants were then asked to infer the gender of the people described in the given scenario. Lastly, they were asked to rate their likelihood, on a five point rating scale, to do the following: leave the couple alone, call the police, verbally intervene, physically intervene, video the altercation, monitor the couple so the abuser knows there is a witness, or just watch the fight because it is interesting. Participants were also asked to fill out a general Victim Concern Scale to gauge their overall concern for victims and if there was any relation with the different types of vignettes. Higher levels of intervention for calling the police were found for scenarios where the gender was not specified. Physical violence was found to have a higher participant response rate than verbal abuse and the most likely response was to call the police. Consistent with previous research, this study found no significant difference in participants’ responses to vignettes when comparing heterosexual relationships to LGBTQ+ relationships. Interestingly, participants in this study equally assumed the gender of the victim and abuser. This research adds to previous studies by establishing the relationship among the variables listed and by being able to contribute knowledge to the understanding of domestic violence

The First Faith-Based Movement: The Religious Roots of Social Progressivism in America (1880-1912) in Historical Perspective

This re-evaluation of the published writings of Richard T. Ely, Josiah Strong, and Jane Addams during the Progressive era (1880- 1912) explores the themes of religious idealism and nationalism that figured prominently in the early formulation of modern liberal reform ideology in the United States. A specific focus will be placed on tracing themes of the America’s millennial destiny and how they gradually evolved into prophesies of social transformation through the applied use of social science knowledge. Beyond merely satisfying historical curiosity, this inquiry provides a new perspective from which to consider the fierce clashes over social welfare policy which occurred in the twentieth century

A practical approach to execute and test a lean startup: building phase

This paper practically applies the “Lean Startup Approach” by identifying, analyzing and executing a newly developed web-based business idea. Hypotheses were designed and tested with the construction of a minimum viable product – i.e. a landing page. In-depth interviews allowed deciding either to pivot or persevere the initial launch strategy. Overall, the aim was to collect as much valuable response as possible from customers and ultimately decide for a superior strategy while devoting the smallest amount of time and money