Модификация мембран на основе полисульфона с использованием триблоксополимера полиэтиленгликоля и полипропиленгликоля

The phase state, viscosity and optical properties of polysulfone (PSF) solutions in N,N-dimethylacetamide (DMAc) with the addition of block copolymer Pluronic F127 and polyethylene glycol (PEG-4000, Mn = 4000 g-mol-1) were studied. Additives are both pore-forming and hydrophilizing agents. It was found that 18-22 % PSF solutions in DMAc with the Pluronic F127 content t ≥5 wt. % feature a lower critical solution temperature (LCST). Mixed matrix PSF/Pluronic F127 and PSF/PEG membranes were obtained by the phase inversion technique and the comparative studies of their structure and performance were carried out. It was found that the average surface roughness parameters of PSF/Pluronic F127 membranes significantly exceed those of PSF/PEG membranes. The presence of the both additives in the casting solution leads to the effective hydrophilization of the membrane selective layer. It was shown that the increase in the membrane flux and the decrease in the polyvinylpyrrolidone (K-30, Mn = 40000 g-mol-1) rejection coefficient are a result of adding both Pluronic F127 and PEG-4000 to the casting solution. It was shown that PSF/Pluronic F127 membranes are characterized by higher shrinkage resistance and a lower total flux decrease during ultrafiltration of bovine serum albumin solutions. It was found that the antifouling performance of PSF/Pluronic F127 membranes significantly exceeds that of PSF/PEG membranes.Изучено фазовое состояние, вязкостные и оптические свойства растворов полисульфона (ПСФ) в N,N-диметилацетамиде (ДМАА) с добавками блоксополимера Pluronic F127 и полиэтиленгликоля (ПЭГ-4000, Мn = 4000 г-моль-1) в качестве порообразователей и гидрофилизующих агентов. Установлено, что 18-22 %-ные растворы ПСФ в ДМАА с добавкойt ≥5 % Pluronic F127 характеризуются наличием нижней критической температуры смешения (НКТС). Методом инверсии фаз получена серия мембран со смешанной матрицей ПСФ/Pluronic F127 и ПСФ/ПЭГ и проведены сравнительные исследования их структуры и транспортных характеристик. Установлено, что значения параметров средней шероховатости поверхности для мембран ПСФ/Pluronic F127 существенно превышают таковые для мембран ПСФ/ПЭГ. Введение обеих добавок в формовочную композицию приводит к эффективной гидрофилизации селективного слоя мембран. Установлено, что введение в растворы как PluronicF127, так и ПЭГ-4000 приводит к увеличению удельной производительности мембран и снижению коэффициента задерживания по поливинилпирролидону (ПВП К-30, Mn = 40000 г-моль-1). Показано, что мембраны со смешанной матрицей ПСФ/ Pluronic F127 характеризуются более высокой устойчивостью к уплотнению, меньшей степенью уменьшения общего потока при фильтрации растворов бычьего сывороточного альбумина и существенно превосходят по устойчивости к загрязнению мембраны со смешанной матрицей ПСФ/ПЭГ

Hygienic quality of dehydrated aromatic herbs marketed in Southern Portugal

Dehydrated aromatic herbs are highly valued ingredients, widely used at home level and by food processing industry, frequently added to a great number of recipes in the Mediterranean countries. Despite being considered low-moisture products and classified as GRAS, during pre and post-harvesting stages of production they are susceptible of microbial contamination. In Europe an increasing number of food recalls and disease outbreaks associated with dehydrated herbs have been reported in recent years. In this study the microbial quality of 99 samples of aromatic herbs (bay leaves, basil, coriander, oregano, parsley, Provence herbs, rosemary and thyme) collected from retails shops in the region of Algarve (Southern Portugal) was assessed. All the samples were tested by conventional methods and were assayed for the total count of aerobic mesophilic microorganisms, Salmonella spp., Escherichia coli, coagulase-positive staphylococci and filamentous fungi. Almost 50 % of the herbs did not exceed the aerobic mesophilic level of 104 CFU/g. The fungi count regarded as unacceptable (106 CFU/g) was not found in any of the tested herbs, while 84 % of the samples ranged from ≤102 to 104 CFU/g. No sample was positive for the presence of Salmonella spp., Escherichia coli and staphylococci. The results are in compliance with the European Commission criteria although they point out to the permanent need of surveillance on the good standards of handling/cooking practices as well as the importance of avoiding contamination at production, retailing and distribution. The microbiological hazards associated with the pathogenic and toxigenic microbiota of dried herbs remain as a relevant public health issue, due to the fact that they are added to foods not submitted to any following lethal procedure. Control measures should be adopted in order to ensure that all phases of their supply chain respect the food safety standards.FCT: UID/BIA/04325/2019.info:eu-repo/semantics/publishedVersio

Decolonisation of MRSA, S. aureus and E. coli by Cold-Atmospheric Plasma Using a Porcine Skin Model In Vitro

In the last twenty years new antibacterial agents approved by the U.S. FDA decreased whereas in parallel the resistance situation of multi-resistant bacteria increased. Thus, community and nosocomial acquired infections of resistant bacteria led to a decrease in the efficacy of standard therapy, prolonging treatment time and increasing healthcare costs. Therefore, the aim of this work was to demonstrate the applicability of cold atmospheric plasma for decolonisation of Gram-positive (Methicillin-resistant Staphylococcus aureus (MRSA), Methicillin-sensitive Staphylococcus aureus) and Gram-negative bacteria (E. coli) using an ex vivo pig skin model. Freshly excised skin samples were taken from six month old female pigs (breed: Pietrain). After application of pure bacteria on the surface of the explants these were treated with cold atmospheric plasma for up to 15 min. Two different plasma devices were evaluated. A decolonisation efficacy of 3 log10 steps was achieved already after 6 min of plasma treatment. Longer plasma treatment times achieved a killing rate of 5 log10 steps independently from the applied bacteria strains. Histological evaluations of untreated and treated skin areas upon cold atmospheric plasma treatment within 24 h showed no morphological changes as well as no significant degree of necrosis or apoptosis determined by the TUNEL-assay indicating that the porcine skin is still vital. This study demonstrates for the first time that cold atmospheric plasma is able to very efficiently kill bacteria applied to an intact skin surface using an ex vivo porcine skin model. The results emphasize the potential of cold atmospheric plasma as a new possible treatment option for decolonisation of human skin from bacteria in patients in the future without harming the surrounding tissue

Влияние давления при формировании селективного слоя на структуру и свойства динамических композиционных мембран для первапорации

Composite membranes for pervaporation were prepared by forming a selective layer based on cross-linked polyvinyl alcohol (PVA) on the porous membrane-substrate surface in the dynamic mode (via PVA solution ultrafiltration). It was found that the pressure growth results in increasing the thickness of the composite membrane selective layer. Composite membrane contact angle, flux, water content in permeate in ethanol/water (mass ratio 90/10) pervaporation were revealed to have maximum values at 3–4 atm depending on the PVA concentration in the feed solution. It was shown that the revealed dependence of the contact angle, selectivity, and permeability on the pressure of the selective layer formation is due to the compaction of the polymer matrix-substrate under the action of the transmembrane pressure and its relaxation after pressure release. When using elevated pressures (more than 3–4 atm), the relaxation of the polymer matrix causes the microdefect to form as a result of deformation of the selective layer.Композиционные мембраны для первапорации были получены методом формирования селективного слоя на основе сшитого поливинилового спирта (ПВС) на поверхности пористой мембраны-подложки в динамическом режиме (ультрафильтрации растворов ПВС). Установлено, что повышение давления приводит к увеличению толщины селективного слоя композиционных мембран; при этом их контактный угол смачивания, удельная производительность, содержание воды в пермеате в процессе первапорации смеси этанол/вода 90/10 изменяются экстремально с максимумом при 3–4 атм в зависимости от концентрации раствора ПВС. Экстремальная зависимость краевого угла смачивания, коэффициента разделения и проницаемости композиционных мембран объясняется процессами уплотнения полимерной матрицы-подложки под действием трансмембранного давления и ее релаксации после снятия давления. При использовании повышенных давлений (более 3–4 атм) релаксация полимерной матрицы приводит к появлению микродефектов в результате деформации сформированного селективного слоя

Genome Sequence of a Lancefield Group C Streptococcus zooepidemicus Strain Causing Epidemic Nephritis: New Information about an Old Disease

Outbreaks of disease attributable to human error or natural causes can provide unique opportunities to gain new information about host-pathogen interactions and new leads for pathogenesis research. Poststreptococcal glomerulonephritis (PSGN), a sequela of infection with pathogenic streptococci, is a common cause of preventable kidney disease worldwide. Although PSGN usually occurs after infection with group A streptococci, organisms of Lancefield group C and G also can be responsible. Despite decades of study, the molecular pathogenesis of PSGN is poorly understood. As a first step toward gaining new information about PSGN pathogenesis, we sequenced the genome of Streptococcus equi subsp. zooepidemicus strain MGCS10565, a group C organism that caused a very large and unusually severe epidemic of nephritis in Brazil. The genome is a circular chromosome of 2,024,171 bp. The genome shares extensive gene content, including many virulence factors, with genetically related group A streptococci, but unexpectedly lacks prophages. The genome contains many apparently foreign genes interspersed around the chromosome, consistent with the presence of a full array of genes required for natural competence. An inordinately large family of genes encodes secreted extracellular collagen-like proteins with multiple integrin-binding motifs. The absence of a gene related to speB rules out the long-held belief that streptococcal pyrogenic exotoxin B or antibodies reacting with it singularly cause PSGN. Many proteins previously implicated in GAS PSGN, such as streptokinase, are either highly divergent in strain MGCS10565 or are not more closely related between these species than to orthologs present in other streptococci that do not commonly cause PSGN. Our analysis provides a comparative genomics framework for renewed appraisal of molecular events underlying APSGN pathogenesis

A single natural nucleotide mutation alters bacterial pathogen host tropism

The capacity of microbial pathogens to alter their host tropism leading to epidemics in distinct host species populations is a global public and veterinary health concern. To investigate the molecular basis of a bacterial host-switching event in a tractable host species, we traced the evolutionary trajectory of the common rabbit clone of Staphylococcus aureus. We report that it evolved through a likely human-to-rabbit host jump over 40 years ago and that only a single naturally occurring nucleotide mutation was required and sufficient to convert a human-specific S. aureus strain into one that could infect rabbits. Related mutations were identified at the same locus in other rabbit strains of distinct clonal origin, consistent with convergent evolution. This first report of a single mutation that was sufficient to alter the host tropism of a microorganism during its evolution highlights the capacity of some pathogens to readily expand into new host species populations

EFFECTS OF FATIGUE ON GROUND REACTION FORCES DURING RUNNING

Research on whether muscular lower limb fatigue causes higher impact forces is equivocal. If lower limb fatigue increases vertical ground reaction forces during running, the athlete may be predisposed to injury. This information may help personal trainers make recommendations on whether it is best to run before or after activities that fatigue the lower limbs. PURPOSE: To determine if muscular lower limb fatigue affects vertical ground reaction forces during running. METHODS: Ten healthy, habitually active subjects aged 18-46y volunteered for the study. Each subject was instructed to jog at a medium fast constant speed approximately 6 m over two force plates (AMTI, 1500 Hz). GRFs were recorded during left foot contact, both before and after an exhaustive treadmill run determined by reaching an RPE of 15 on a 20-point scale and maintaining that pace for at least 30 seconds. Peak vertical impact forces for two to three trials were averaged for each condition and a dependent t-test (SPSS v.22) was used to analyze the mean difference in pre-and-post fatigue GRFs. Repeated measures ANOVA was used to graph within-subject differences due to the intervention. RESULTS: Mean GRF values for pre & post fatigue were 1518.95 +/- 406.23 N and 1503.39 +/- 401.34 N, respectively, which were not significantly different (p\u3e0.05). CONCLUSION: No significant difference in peak vertical impact forces pre-and-post fatigue was observed. Future research should use a standardized fatigue protocol perhaps based on lactate levels or predicted max HR, and multiple trials across multiple days

Genomic evidence for the evolution of Streptococcus equi : host restriction, increased virulence, and genetic exchange with human pathogens

The continued evolution of bacterial pathogens has major implications for both human and animal disease, but the exchange of genetic material between host-restricted pathogens is rarely considered. Streptococcus equi subspecies equi (S. equi) is a host-restricted pathogen of horses that has evolved from the zoonotic pathogen Streptococcus equi subspecies zooepidemicus (S. zooepidemicus). These pathogens share approximately 80% genome sequence identity with the important human pathogen Streptococcus pyogenes. We sequenced and compared the genomes of S. equi 4047 and S. zooepidemicus H70 and screened S. equi and S. zooepidemicus strains from around the world to uncover evidence of the genetic events that have shaped the evolution of the S. equi genome and led to its emergence as a host-restricted pathogen. Our analysis provides evidence of functional loss due to mutation and deletion, coupled with pathogenic specialization through the acquisition of bacteriophage encoding a phospholipase A(2) toxin, and four superantigens, and an integrative conjugative element carrying a novel iron acquisition system with similarity to the high pathogenicity island of Yersinia pestis. We also highlight that S. equi, S. zooepidemicus, and S. pyogenes share a common phage pool that enhances cross-species pathogen evolution. We conclude that the complex interplay of functional loss, pathogenic specialization, and genetic exchange between S. equi, S. zooepidemicus, and S. pyogenes continues to influence the evolution of these important streptococci.Publisher PDFPeer reviewe

Synthesis of Acid-Labile PEG and PEG-Doxorubicin-Conjugate Nanoparticles via Brush-First ROMP

A panel of acid-labile bis-norbornene cross-linkers was synthesized and evaluated for the formation of acid-degradable brush-arm star polymers (BASPs) via the brush-first ring-opening metathesis polymerization (ROMP) method. An acetal-based cross-linker was identified that, when employed in conjunction with a poly(ethylene glycol) (PEG) macromonomer, provided highly controlled BASP formation reactions. A combination of this new cross-linker with a novel doxorubicin (DOX)-branch-PEG macromonomer provided BASPs that simultaneously degrade and release cytotoxic DOX in vitro.Massachusetts Institute of Technology. Department of ChemistryNational Institute for Biomedical Imaging and Bioengineering (U.S.) (NIBIB 1R21EB018529-01A1