Dhvar5 antimicrobial peptide (AMP) chemoselective covalent immobilization results on higher antiadherence effect than simple physical adsorption

Bacterial colonization and subsequent biofilm formation is still one of the major problems associated with medical devices. Antimicrobial peptides (AMP) immobilization onto biomaterials surface is a promising strategy to avoid bacterial colonization. However, a correct peptide orientation and exposure from the surface is essential to maintain AMP antimicrobial activity. This work aims to evaluate the effect of the immobilization on antibacterial activity of Dhvar5 (LLLFLLKKRKKRKY), an AMP with a head-to-tail amphipathicity. Dhvar5 was linked to thin chitosan coatings in i) a controlled orientation and exposure, testing covalent immobilization of its N- or C-terminus and using spacers with different lengths and flexibilities or in ii) a random orientation by physical adsorption. Chitosan coating was chosen due to its antimicrobial properties and readiness to be functionalized. Surface characterization demonstrated the chemoselective immobilization of the peptide with different spacers in a similar concentration (∼2 ng/cm2). Efficacy assays demonstrated that covalent immobilization of Dhvar5 exposing its cationic end, improves the chitosan coating antimicrobial effect by decreasing Methicillin-resistant Staphylococcus aureus (MRSA) colonization. This effect was enhanced when longer spacers were used independently of their flexibility. In opposite, immobilized Dhvar5 exposing its hydrophobic end has no effect on bacterial adhesion to chitosan, and when adsorbed in a random orientation even induces bacterial adhesion to chitosan coating.This work was financed by FEDER funds through the Programa Operacional Factores de Competitividade (COMPETE) and by Portuguese funds through FCT (Fundacao para a Ciencia e a Tecnologia) in the framework of the projects: PTDC/CTM/101484/2008; PEst-C/SAU/LA0002/2013; Pest-C/QUI/UI0081/2013. Fabiola Costa acknowledges FCT for the PhD grant SFRH/BD/72471/2010

Prevention of urinary catheter-associated infections by coating antimicrobial peptides from crowberry endophytes

Urinary catheters are extensively used in hospitals, being responsible for about 75% of hospital-acquired infections. In this work, a de novo designed antimicrobial peptide (AMP) Chain201D was studied in the context of urinary catheter-associated infections. Chain201D showed excellent antimicrobial activity against relevant ATCC strains and clinical isolates of bacteria and yeast and demonstrated high stability in a wide range of temperatures, pH and salt concentrations. Moreover, the bactericidal activity of Chain201D immobilized on a model surface was studied against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), some of the most prevalent strains found in urinary catheter-associated infections. Chain201D was successfully tethered to ((1-mercapto-11-undecyl)-(tetra(ethylene glycol) (EG4)) terminated self-assembled monolayers (SAMs), (EG4-SAMs), activated by 1,1'-Carbonyldiimidazole (CDI) at different concentrations. Chain201D surfaces can bind and kill by contact a high percentage of adherent bacteria. These achievements are obtained without any peptide modification (for chemoselective conjugation) and without the use of a spacer. Moreover, increased amounts of immobilized AMP lead to higher numbers of adhered/dead bacteria, revealing a concentration-dependent behaviour and demonstrating that Chain201D has excellent potential for developing antimicrobial urinary catheters.AntINFECT: Bioengineered Advanced Therapies for Problematic Infected Wounds POCI-01-0145-FEDER-031781) and Institute for Research and Innovation in Health Sciences (UID/BIM/04293/2019). C. Monteiro would like to acknowledge national funding through FCT – Fundação para a Ciência e a Tecnologia, I.P., provided by the contract-program and according to numbers 4, 5 and 6 of art. 23 of Law no. 57/2016 of 29th August, as amended by Law no. 57/2017 of 19th July. Professor Paula Gomes from Faculdade de Ciências da Universidade do Porto (FC-UP), Porto Peptide Synthesis Facility (POP-UP) for CEM 7 peptide. The funding received from Tekes, Finland (3331/31/2014) is thankfully acknowledged

Influence of Immobilization Strategies on the Antibacterial Properties of Antimicrobial Peptide-Chitosan Coatings

It is key to fight bacterial adhesion to prevent biofilm establishment on biomaterials. Surface immobilization of antimicrobial peptides (AMP) is a promising strategy to avoid bacterial colonization. This work aimed to investigate whether the direct surface immobilization of Dhvar5, an AMP with head-to-tail amphipathicity, would improve the antimicrobial activity of chitosan ultrathin coatings. The peptide was grafted by copper-catalyzed azide-alkyne cycloaddition (CuAAC) chemistry by either its C- or N- terminus to assess the influence of peptide orientation on surface properties and antimicrobial activity. These features were compared with those of coatings fabricated using previously described Dhvar5-chitosan conjugates (immobilized in bulk). The peptide was chemoselectively immobilized onto the coating by both termini. Moreover, the covalent immobilization of Dhvar5 by either terminus enhanced the antimicrobial effect of the chitosan coating by decreasing colonization by both Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria. Relevantly, the antimicrobial performance of the surface on Gram-positive bacteria depended on how Dhvar5-chitosan coatings were produced. An antiadhesive effect was observed when the peptide was grafted onto prefabricated chitosan coatings (film), and a bactericidal effect was exhibited when coatings were prepared from Dhvar5-chitosan conjugates (bulk). This antiadhesive effect was not due to changes in surface wettability or protein adsorption but rather depended on variations in peptide concentration, exposure, and surface roughness. Results reported in this study show that the antibacterial potency and effect of immobilized AMP vary greatly with the immobilization procedure. Overall, independently of the fabrication protocol and mechanism of action, Dhvar5-chitosan coatings are a promising strategy for the development of antimicrobial medical devices, either as an antiadhesive or contact-killing surface.This work was financed by the FCT- Fundação para a Ciência e a Tecnologia through projects POCI-01-0145-FEDER-031781 (AntINFECT), UIB/50006/2020 (LAQV-REQUIMTE) and FEDER—Fundo Europeu de Desenvolvimento Regional through NORTE 2020—Programa Operacional Regional do Norte-Bio2Skin Advanced (NORTE-01-0247-FEDER-047225). M Barbosa (SFRH/BD/108966/2015) and Pedro Alves (SFRH/BD/145471/2019) Ph.D. grants were financially supported by national (FCT/Norte 2020 Framework) and European Union funds (ESF—European Social Fund). Paula Parreira (CEECIND/01210/2018) and Maria Cristina L. Martins (LA/P/0070/2020) also thank FCT for funding. Maria Cristina L. Martins also acknowledges the MOBILIsE Project, which has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement no. 951723

Gênese da atenção domiciliária no Brasil no início do século XX

Objetivo: problematizar as condições de possibilidade para o aparecimento da atenção domiciliária no início do século XX no Brasil.Método: estudo de inspiração genealógica sobre a atenção domiciliária. O material empírico foi constituído por dois documentos legais sobre o tema publicados no Diário Oficial. A análise documental utilizou as ferramentas analíticas poder, poder disciplinar e biopolítica, inspiradas em Foucault.Resultados: foram elaboradas duas categorias: “Vigilância no domicílio: as enfermeiras visitadoras e a tuberculose” e “Registros: o aparelho político e econômico”.Considerações finais: A tuberculose, a nova profissão das enfermeiras visitadoras, os registros produzidos pela vigilância e a análise minuciosa das cidades conferiram à atenção domiciliária um caráter de vigilância, inspeção e controle voltado a conduzir as condutas dos indivíduos.Palavras-chave: Vigilância da população. Serviços de assistência domiciliar. Assistência domiciliar. Enfermagem

Brain energy rescue:an emerging therapeutic concept for neurodegenerative disorders of ageing

The brain requires a continuous supply of energy in the form of ATP, most of which is produced from glucose by oxidative phosphorylation in mitochondria, complemented by aerobic glycolysis in the cytoplasm. When glucose levels are limited, ketone bodies generated in the liver and lactate derived from exercising skeletal muscle can also become important energy substrates for the brain. In neurodegenerative disorders of ageing, brain glucose metabolism deteriorates in a progressive, region-specific and disease-specific manner — a problem that is best characterized in Alzheimer disease, where it begins presymptomatically. This Review discusses the status and prospects of therapeutic strategies for countering neurodegenerative disorders of ageing by improving, preserving or rescuing brain energetics. The approaches described include restoring oxidative phosphorylation and glycolysis, increasing insulin sensitivity, correcting mitochondrial dysfunction, ketone-based interventions, acting via hormones that modulate cerebral energetics, RNA therapeutics and complementary multimodal lifestyle changes