Risk indexes for studying interconnected earthing systems inside MV networks

The paper presents a risk-evaluation-based approach to the issue of interconnection between the earth electrodes of the MV/LV substations within MV networks. After a short introduction on the interconnection between earthing systems, the paper proposes four risk indexes defined starting from the safety requirements given by CENELEC HD 63 7 S1. The indexes allow one to put in evidence, in a clear way, the benefits of the interconnection in terms of reduction of risk of critical electric shock for persons and of stress on the insulation of the LV devices in the presence of single line to earth faults and double earth faults inside MV/LV substations and single line to earth faults inside HV/MV stations. Moreover they can be used to identify in a simple way a Global Earthing System

Serratiopeptidase reduces the invasion of osteoblasts by Staphylococcus aureus

Finding new strategies to counteract periprosthetic infection and implant failure is a main target in orthopedics. Staphylococcus aureus, the leading etiologic agent of orthopedic implant infections, is able to enter and kill osteoblasts, to stimulate pro-inflammatory chemokine secretion, to recruit osteoclasts, and to cause inflammatory osteolysis. Moreover, by entering eukaryotic cells, staphylococci hide from the host immune defenses and shelter from the extracellular antibiotics. Thus, infection persists, inflammation thrives, and a highly destructive osteomyelitis occurs around the implant. The ability of serratiopeptidase (SPEP), a metalloprotease by Serratia marcescens, to control S. aureus invasion of osteoblastic MG-63 cells and pro-inflammatory chemokine MCP-1 secretion was evaluated. Human osteoblast cells were infected with staphylococcal strains in the presence and in the absence of SPEP. Cell proliferation and cell viability were also evaluated. The release of pro-inflammatory chemokine MCP-1 was evaluated after the exposure of the osteoblast cells to staphylococcal strains. The significance of the differences in the results of each test and the relative control values was determined with Student’s t-test. SPEP impairs their invasiveness into osteoblasts, without affecting the viability and proliferation of bone cells, and tones down their production of MCP-1. We recognize SPEP as a potential tool against S. aureus bone infection and destruction

SU NIETZSCHE E BLOCH: NICHILISMO E AUTOCONTRADDITTORIET\uc0 DELLA SECOLARIZZAZIONE

This study starts from the hypothesis that self-contraddiction constitutes the bond of conjunction between nihilism and secularization. The circle of self-contraddiction constitutes here the central thread for the interpretation of the question of nihilism in Nietzsche and the question of the secularization of the religion as an important part of the thinking of Nietzsche and Bloch. From this point of view Bloch's considerations about\ua0the secularization allow an analysis of the topic\ua0of the nihilism in his work: the secularization of the west-religion shows her link with the main thesis of nihilism and can be interpreted\ua0as her development. Therefore an important part of the thinking of Bloch can be read from the perspective of the renewal of the Nietzschean thesis of the self-contraddiction (self-disintegration) of Christianity in\ua0Atheismus im Christentum,\ua0that is as a philosophical development of the principle of the secularization of west-religion in conjuction with the self-contraddictory logic of the accomplished nihilism

Neurally adjusted ventilatory assist : from animal studies to clinical practice

Patients in the Intensive Care Unit (ICU) undergoing ventilator treatment may experience asynchrony with the ventilator, which has been associated with increased need of sedation, sleep disruption, prolonged mechanical ventilation and unsuccessful weaning from the ventilator. The search for new strategies to improve patient-ventilator interaction is ongoing. Neurally Adjusted Ventilatory Assist (NAVA) is a recently developed ventilator support that uses the Electrical Activity of the diaphragm (EAdi) as an input signal to control the ventilator. Each breath is delivered in proportion to the EAdi amplitude and follows the timing of the EAdi start and ending. NAVA may potentially improve patient-ventilator synchrony, which could be beneficial, especially in paediatric ICU patients. Further, NAVA use could be of interest during surgery and general anaesthesia, potentially reducing risk for intraoperative atelectasis formation and postoperative complications. However, the feasibility of NAVA during general anaesthesia has not been investigated. There is some uncertainty among clinicians on how to set NAVA bedside. A pragmatic strategy, targeting NAVA to different levels of muscle unloading has not been studied, but could be a means of standardizing the approach to unload. Finally, it is not known if lower unloading could improve the distribution of ventilation in favour of the dorsal regions of the lungs. Patient-ventilator synchrony and diaphragm unloading with NAVA compared to Pressure Support (PS) were evaluated in Acute Lung Injured (ALI) rabbits with increasing level of assist and in rats breathing with an added dead space in the respiratory circuit. The feasibility and efficacy of NAVA was investigated in small species, close in weight to the smallest viable human being. The pattern of breathing in NAVA and PS was studied in small species, when dead space was added. The feasibility of NAVA in sedation and anaesthesia with sevoflurane and propofol and the impact of these drugs on the pattern of breathing and muscle contractility were investigated in a big animal model. The possibility to target NAVA to different levels of respiratory muscle unloading was evaluated in Neurosurgical Intensive Care (NICU) patients and the effect of moderate unloading on the distribution of ventilation was investigated with Electrical Impedance Tomography. Synchrony with NAVA was maintained and diaphragm unloading increased when raising the assist level, while for high PS the synchrony and unloading worsened, due to wasted inspiratory efforts causing a larger work of breathing. With NAVA, oxygenation and ventilation remained in the physiologic range in small species and when dead space was added, similar PaCO2 was achieved with a lower increase in respiratory rate and minute ventilation, compared to PS. Sedation and anaesthesia with sevoflurane and propofol, during NAVA in pigs, preserved the EAdi signal and spontaneous breathing, keeping the gas exchange in the physiologic range. The tidal volume variability in NAVA was preserved both with sevoflurane and propofol, being higher in propofol, due to more frequent sighs, followed by post-sigh apnoea. With sevoflurane Neuro-mechanical and Neuro-Ventilatory Efficiency (NVE) were higher, suggesting that sevoflurane could better preserve muscle contractility, compared to propofol. In NAVA it was feasible to set the assist at different levels of respiratory muscle unloading in NICU patients, by means of the NVE. Lower muscle unloading was shown to redistribute ventilation towards the dorsal regions of the lungs. In conclusion this thesis demonstrates that NAVA improves patient-ventilator synchrony for increased assist levels and unloads the respiratory muscles with lower pressures and volumes compared to PS. NAVA is feasible and efficacious in small species, close in weight to the lowest viable human being and appears to be more efficient than PS in eliminating the CO2. NAVA is feasible during sedation and anaesthesia with sevoflurane and propofol in pigs and preserves the natural variability in pattern of breathing. Propofol in combination with NAVA is associated with more sighs and post-sigh apnoea than sevoflurane. Sevoflurane appears to preserve muscle contractility in NAVA better than propofol. NAVA can be targeted to different levels of muscle unloading by means of the NVE and lower unloading redistributes ventilation towards the dorsal regions of the lungs, providing the premise for a better matching of ventilation and perfusion

Interactions of Neutrophils with the Polymeric Molecular Components of the Biofilm Matrix in the Context of Implant-Associated Bone and Joint Infections

In the presence of orthopedic implants, opportunistic pathogens can easily colonize the biomaterial surfaces, forming protective biofilms. Life in biofilm is a central pathogenetic mechanism enabling bacteria to elude the host immune response and survive conventional medical treatments. The formation of mature biofilms is universally recognized as the main cause of septic prosthetic failures. Neutrophils are the first leukocytes to be recruited at the site of infection. They are highly efficient in detecting and killing planktonic bacteria. However, the interactions of these fundamental effector cells of the immune system with the biofilm matrix, which is the true interface of a biofilm with the host cells, have only recently started to be unveiled and are still to be fully understood. Biofilm matrix macromolecules consist of exopolysaccharides, proteins, lipids, teichoic acids, and the most recently described extracellular DNA. The latter can also be stolen from neutrophil extracellular traps (NETs) by bacteria, who use it to strengthen their biofilms. This paper aims to review the specific interactions that neutrophils develop when they physically encounter the matrix of a biofilm and come to interact with its polymeric molecular components

Multi dynamic extraction: An innovative method to obtain a standardized chemically and biologically reproducible polyphenol extract from poplar-type propolis to be used for its anti-infective properties

Antimicrobial activity is a well-known property of propolis, making it a candidate for antimicrobial surfaces in biomedical devices. Nevertheless, large-scale use of propolis as an anti-infective agent is limited by the heterogeneity of its chemical composition and consequent variation in antimicrobial activity. The aim of this study was to demonstrate that the multi dynamic extraction (M.E.D.) method produces standardized polyphenolic mixtures from poplar-type propolis, with reproducible chemical composition and anti-microbial activity, independently from the chemical composition of the starting raw propolis. Three raw propolis samples, from Europe, America, and Asia, were analyzed for their polyphenol chemical composition by means of HPLC-UV and then combined to obtain three mixtures of propolis, which werme submitted to the M.E.D. extraction method. The chemical composition and the antimicrobial activity of M.E.D. propolis against bacteria and fungi were determined. The three M.E.D. propolis showed similar chemical compositions and antimicrobial activities, exhibiting no relevant differences against antibiotic-susceptible and antibiotic-resistant strains. The batch-to-batch reproducibility of propolis extracts obtained with the M.E.D. method encourages the design of drugs alternative to traditional antibiotics and the development of anti-infective surface-modified biomaterials

Searching for Virulence Factors among Staphylococcus lugdunensis Isolates from Orthopedic Infections: Correlation of β-hemolysin, hemolysin III, and slush Genes with Hemolytic Activity and Synergistic Hemolytic Activity

Staphylococcus lugdunensis is an emerging high-virulent pathogen. Here, the presence and expression of virulence genes (icaA, fbl, vwbl, fbpA, slush A, B and C, and genes of the putative beta-hemolysin and hemolysin III) and the ability to induce synergistic hemolytic activity and hemolysis after 24, 48 and 72 h were investigated in a collection of twenty-two S. lugdunensis clinical isolates. The collection of isolates, mainly from implant orthopedic infections, had previously been grouped by ribotyping/dendrogram analysis and studied for biofilm matrices, biomasses and antibiotic resistances. Two isolates, constituting a unique small ribogroup sharing the same cluster, exhibited an amplicon size of the slush operon (S. lugdunensis synergistic hemolysin) which was shorter than the expected 977 bp. This outcome can predict the genetic lineage of the S. lugdunensis strains. One isolate (cra1342) presented two deletions: one of 90 bp in slush A and the other of 91 bp in slush B. Another isolate (N860314) showed a single 193 bp deletion, which encompassed part of the slush B terminal sequence and most of slush C. The isolate N860314 was devoid of hemolytic activity after 24 h, and the first consideration was that the deleted region deals with the coding of the active enzymatic site of the slush hemolysin. On the other hand, cra1342 and N860314 isolates with different slush deletions and with hemolytic activity after 24 and 48 h, respectively, could have replaced the hemolytic phenotype through other processes

Bio-inspired coating strategies for the immobilization of polymyxins to generate contact-killing surfaces

Microbial colonization of indwelling devices remains a major concern in modern healthcare. Developing approaches to prevent biomaterial-associated infections (BAI) is, therefore, in great demand. This study aimed to immobilize two antimicrobial peptides (polymyxins B and E) onto polydimethylsiloxane (PDMS) using two polydopamine (pDA)-based approaches: the conventional two-step method involving the deposition of a pDA layer to which biomolecules are immobilized, and a one-step method where peptides are dissolved together with dopamine before its polymerization. Surface characterization confirms the immobilization of polymyxins onto PDMS at a non-toxic concentration. Immobilization of polymyxins using a one-step pDA-based approach is able to prevent Pseudomonas aeruginosa adhesion and kill a significant fraction of the adherent ones. Living cells adhered to these modified surfaces exhibit the same susceptibility pattern as cells adhered to unmodified surfaces, highlighting no resistance development. Results suggest that polymyxins immobilization holds a great potential as an additional antimicrobial functionality in the design of biomaterials.The authors acknowledge the Portuguese Foundation for Science and Technology (FCT), the strategic funding of UID/BIO/04469/2013 unit. This study was also supported by FCT and the European Community fund FEDER, through Program COMPETE, under the scope of the Projects “PTDC/SAU-SAP/113196/2009 (FCOMP-01-0124-FEDER-016012),” “RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462),” and “BioHealth—Biotechnology and Bioengineering approaches to improve health quality,” Ref. NORTE-07-0124-FEDER-000027, co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, FEDER. The authors also acknowledge FCT for the PhD Grant of Diana Alves (SFRH/BD/78063/2011)

Bio-inspired coating strategies for the immobilization of polymyxins to generate contact-killing surfaces

Microbial colonization of indwelling devices remains a major concern in modern healthcare. Developing approaches to prevent biomaterial-associated infections (BAI) is, therefore, in great demand. This study aimed to immobilize two antimicrobial peptides (polymyxins B and E) onto polydimethylsiloxane (PDMS) using two polydopamine (pDA)-based approaches: the conventional two-step method involving the deposition of a pDA layer to which biomolecules are immobilized, and a one-step method where peptides are dissolved together with dopamine before its polymerization. Surface characterization confirms the immobilization of polymyxins onto PDMS at a non-toxic concentration. Immobilization of polymyxins using a one-step pDA-based approach is able to prevent Pseudomonas aeruginosa adhesion and kill a significant fraction of the adherent ones. Living cells adhered to these modified surfaces exhibit the same susceptibility pattern as cells adhered to unmodified surfaces, highlighting no resistance development. Results suggest that polymyxins immobilization holds a great potential as an additional antimicrobial functionality in the design of biomaterials.The authors acknowledge the Portuguese Foundation for Science and Technology (FCT), the strategic funding of UID/BIO/04469/2013 unit. This study was also supported by FCT and the European Community fund FEDER, through Program COMPETE, under the scope of the Projects “PTDC/SAU-SAP/113196/2009 (FCOMP-01-0124-FEDER-016012),” “RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462),” and “BioHealth—Biotechnology and Bioengineering approaches to improve health quality,” Ref. NORTE-07-0124-FEDER-000027, co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, FEDER. The authors also acknowledge FCT for the PhD Grant of Diana Alves (SFRH/BD/78063/2011)

Drug loaded homogeneous electrospun PCL/gelatin hybrid nanofiber structures for anti-infective tissue regeneration membranes

YesInfection is the major reason for guided tissue regeneration/guided bone regeneration (GTR/GBR) membrane failure in clinical application. In this work, we developed GTR/GBR membranes with localized drug delivery function to prevent infection by electrospinning of poly(ε-caprolactone) (PCL) and gelatin blended with metronidazole (MNA). Acetic acid (HAc) was introduced to improve the miscibility of PCL and gelatin to fabricate homogeneous hybrid nanofiber membranes. The effects of the addition of HAc and the MNA content (0, 1, 5, 10, 20, 30, and 40 wt.% of polymer) on the properties of the membranes were investigated. The membranes showed good mechanical properties, appropriate biodegradation rate and barrier function. The controlled and sustained release of MNA from the membranes significantly prevented the colonization of anaerobic bacteria. Cells could adhere to and proliferate on the membranes without cytotoxicity until the MNA content reached 30%. Subcutaneous implantation in rabbits for 8 months demonstrated that MNA-loaded membranes evoked a less severe inflammatory response depending on the dose of MNA than bare membranes. The biodegradation time of the membranes was appropriate for tissue regeneration. These results indicated the potential for using MNA-loaded PCL/gelatin electrospun membranes as anti-infective GTR/GBR membranes to optimize clinical application of GTR/GBR strategies