Antibiotic sorption onto microplastics in water: A critical review of the factors, mechanisms and implications.

Microplastics as vectors for contaminants in the environment is becoming a topic of public interest. Microplastics have been found to actively adsorb heavy metals, per-fluorinated alkyl substances (PFAS), polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), pharmaceuticals and personal care products (PPCPs) and polybrominated diethers (PBDs) onto their surface. Particular interest in microplastics capacity to adsorb antibiotics needs further attention due to the potential role this interaction plays on antibiotic resistance. Antibiotic sorption experiments have been documented in the literature, but the data has not yet been critically reviewed. This review aims to comprehensively assess the factors that affect antibiotic sorption onto microplastics. It is recognised that the physico- chemical properties of the polymers, the antibiotic chemical properties, and the properties of the solution all play a crucial role in the antibiotic sorption capacity of microplastics. Weathering of microplastics was found to increase the antibiotic sorption capacity by up to 171%. An increase in solution salinity was found to decrease the sorption of antibiotics onto microplastics, in some instances by 100%. pH also has a substantial effect on sorption capacity, illustrating the significance of electrostatic interactions on the sorption of antibiotics onto microplastics. The need for a uniform experimental design when testing antibiotic sorption is highlighted to remove inconsistencies in the data currently presented. Current literature examines the link between antibiotic sorption and antibiotic resistance, however, further studies are still required to fully understand this emerging global crisis

Evaluating the generation of microplastics from an unlikely source: The unintentional consequence of the current plastic recycling process.

This study casts light on the potential of microplastic generation during plastic recycling - an unintended consequence of the process. To date, microplastics have been detected in the wastewater and sludge from plastic recycling facilities; however, generation pathways, factors and minimisation strategies are understudied. The purpose of this study is to identify the factors affecting microplastic generation, namely, plastic type and weathering conditions. The size reduction phase, which involved the mechanical shredding of the plastic waste material, was identified to be the predominate source of microplastic generation. Material type was found to significantly affect microplastic generation rates. Focussing on the microplastic particles in the size range of 0.212-1.18 mm, polycarbonate (PC), polyethylene terephthalate (PET), polypropylene (PP), and high-density polyethylene (HDPE) generated 28,600 ± 3961, 21,093 ± 2211, 18,987 ± 752 and 6807 ± 393 particles/kg of plastic material shredded, respectively. The significant variations between different plastic types were correlated (R2 = 0.88) to the hardness of the plastic. Environmental weathering was observed to significantly affect microplastic generation rates. Generation rates increased for PC, PET, PP, and HDPE by 185.05 %, 159.80 %, 123.70 % and 121.74 %, respectively, over a six-month environmental exposure period. The results in this study confirm production of large amounts of microplastics from the plastic recycling industry through its operational processes, which may be a significant source for microplastic pollution if measures to reduce their production and removal from wastewater and sludge are not considered

Change in the chemical, mechanical and physical properties of plastics due to UVA degradation in different water matrices: A study on the recyclability of littered plastics.

To move towards a circular society, the recyclability potential of littered plastics should be explored to provide potential value for a product that is typically destined for landfill or incineration. This study aims to understand the changes in physical, mechanical, and chemical properties of four types of plastics (polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC) and polylactic acid (PLA) after simulated environmental degradation. Plastic samples were subjected to different water matrices (in an attempt to simulate terrestrial, ocean, and river environments) to understand the role the environment plays on plastic degradation. Significant physical, mechanical, and chemical changes were observed for the PET, PP and PLA samples. Flakes and cracks were noted during the scanning electron microscopy (SEM) analysis of PET, PP and PLA illustrating the surface degradation that had occurred. Colour scanning of the samples provided complementary information about their suitability for upcycling or downcycling. Both PET and PP had visual colour changes, making them unsuitable for upcycling purposes. PLA had a significant decrease in its tensile strength in all environmental conditions, alongside significant chemical and surface change as revealed by Fourier-transform infrared (FTIR) and SEM analysis, respectively. PC had little to no changes in its chemical, mechanical, and physical properties due to high resistance to solar (UVA) degradation in presence of salt and natural organic matter in the form of humic acid. Therefore, out of the four types of plastics tested, PC was the only plastic determined to have good upcycling potential if collected from the environment. However, PET and PP could still be recycled into lower value products (i.e., construction materials)

Characterisation of the Material and Mechanical Properties of Atomic Force Microscope Cantilevers with a Plan-View Trapezoidal Geometry

Cantilever devices have found applications in numerous scientific fields and instruments, including the atomic force microscope (AFM), and as sensors to detect a wide range of chemical and biological species. The mechanical properties, in particular, the spring constant of these devices is crucial when quantifying adhesive forces, material properties of surfaces, and in determining deposited mass for sensing applications. A key component in the spring constant of a cantilever is the plan-view shape. In recent years, the trapezoidal plan-view shape has become available since it offers certain advantages to fast-scanning AFM and can improve sensor performance in fluid environments. Euler beam equations relating cantilever stiffness to the cantilever dimensions and Young’s modulus have been proven useful and are used extensively to model cantilever mechanical behaviour and calibrate the spring constant. In this work, we derive a simple correction factor to the Euler beam equation for a beam-shaped cantilever that is applicable to any cantilever with a trapezoidal plan-view shape. This correction factor is based upon previous analytical work and simplifies the application of the previous researchers formula. A correction factor to the spring constant of an AFM cantilever is also required to calculate the torque produced by the tip when it contacts the sample surface, which is also dependent on the plan-view shape. In this work, we also derive a simple expression for the torque for triangular plan-view shaped cantilevers and show that for the current generation of trapezoidal plan-view shaped AFM cantilevers, this will be a good approximation. We shall apply both these correction factors to determine Young’s modulus for a range of trapezoidal-shaped AFM cantilevers, which are specially designed for fast-scanning. These types of AFM probes are much smaller in size when compared to standard AFM probes. In the process of analysing the mechanical properties of these cantilevers, important insights are also gained into their spring constant calibration and dimensional factors that contribute to the variability in their spring constant

Identification of the Photoreceptor Transcriptional Co-Repressor SAMD11 as Novel Cause of Autosomal Recessive Retinitis Pigmentosa

Retinitis pigmentosa (RP), the most frequent form of inherited retinal dystrophy is characterized by progressive photoreceptor degeneration. Many genes have been implicated in RP development, but several others remain to be identified. Using a combination of homozygosity mapping, whole-exome and targeted next-generation sequencing, we found a novel homozygous nonsense mutation in SAMD11 in five individuals diagnosed with adult-onset RP from two unrelated consanguineous Spanish families. SAMD11 is ortholog to the mouse major retinal SAM domain (mr-s) protein that is implicated in CRX-mediated transcriptional regulation in the retina. Accordingly, protein-protein network analysis revealed a significant interaction of SAMD11 with CRX. Immunoblotting analysis confirmed strong expression of SAMD11 in human retina. Immunolocalization studies revealed SAMD11 was detected in the three nuclear layers of the human retina and interestingly differential expression between cone and rod photoreceptors was observed. Our study strongly implicates SAMD11 as novel cause of RP playing an important role in the pathogenesis of human degeneration of photoreceptors.This work was supported by several grants from the Spanish Centre for Biomedical Network Research on Rare Diseases (CIBERER)(06/07/0036), Instituto de Salud Carlos III (ISCIII, Spanish Ministry of Health)/FEDER, including FIS (PI013/00226) and RETICS (RD09/0076/00101 and RD12/0034/0010), Ministry of Economy and Competitiveness (MINECO), including FEDER (BFU2012-36845), and BIO2011-27069, Conselleria de Educació of the Valencia Community (PROMETEOII/2014/025), Spanish National Organization of the Blind (ONCE) and the Spanish Fighting Blindness Foundation (FUNDALUCE). M.C. was sponsored by the Miguel Servet Program for Researchers in the Spanish National Health Service (CP12/03256) and RSA by Sara Borrel Postdoctoral Program (CD12/00676), both from the ISCIII/FEDER. A.A-F. was sponsored by CIBERER, RPC is supported by Fundación Conchita Rábago (FCR), L.C is sponsored by RETICS (RD12/0034/0010) from ISCIII and L.d.S. was supported by CAPES Foundation, Ministry of Education of Brazil

Signs and symptoms of disordered eating in pregnancy: A Delphi consensus study

Background: This study aimed to establish consensus on the expression and distinction of disordered eating inpregnancy to improve awareness across various health professions and inform the development of a pregnancyspecific assessment instrument.Methods: A three-round modified Delphi method was used with two independent panels. International cliniciansand researchers with extensive knowledge on and/or clinical experience with eating disorders formed the firstpanel and were recruited using structured selection criteria. Women who identified with a lived experience ofdisordered eating in pregnancy formed the second panel and were recruited via expressions of interest from studyadvertising on pregnancy forums and social media platforms. A systematic search of academic and grey literatureproduced 200 sources which were used to pre-populate the Round I questionnaire. Additional items were includedin Round II based on panel feedback in Round I. Consensus was defined as 75% agreement on an item.Results: Of the 102 items presented to the 26 professional panel members and 15 consumer panel members, 75reached consensus across both panels. Both panels clearly identified signs and symptoms of disordered eating inpregnancy and endorsed a number of clinical features practitioners should consider when delineating disorderedeating symptomatically from normative pregnancy experiences.Conclusion: A list of signs and symptoms in consensus was identified. The areas of collective agreement may beused to guide clinicians in clinical practice, aid the development of psychometric tools to detect/assess pregnancyspecific disordered eating, in addition to serving as starting point for the development of a core outcome set tomeasure disordered eating in pregnancy

Outer membrane protein folding from an energy landscape perspective

The cell envelope is essential for the survival of Gram-negative bacteria. This specialised membrane is densely packed with outer membrane proteins (OMPs), which perform a variety of functions. How OMPs fold into this crowded environment remains an open question. Here, we review current knowledge about OFMP folding mechanisms in vitro and discuss how the need to fold to a stable native state has shaped their folding energy landscapes. We also highlight the role of chaperones and the β-barrel assembly machinery (BAM) in assisting OMP folding in vivo and discuss proposed mechanisms by which this fascinating machinery may catalyse OMP folding

Effect of early Vasopressin vs Norepinephrine on kidney failure in patients with septic shock : the VANISH randomized clinical trial

Importance Norepinephrine is currently recommended as the first-line vasopressor in septic shock; however, early vasopressin use has been proposed as an alternative. Objective To compare the effect of early vasopressin vs norepinephrine on kidney failure in patients with septic shock. Design, Setting, and Participants A factorial (2×2), double-blind, randomized clinical trial conducted in 18 general adult intensive care units in the United Kingdom between February 2013 and May 2015, enrolling adult patients who had septic shock requiring vasopressors despite fluid resuscitation within a maximum of 6 hours after the onset of shock. Interventions Patients were randomly allocated to vasopressin (titrated up to 0.06 U/min) and hydrocortisone (n = 101), vasopressin and placebo (n = 104), norepinephrine and hydrocortisone (n = 101), or norepinephrine and placebo (n = 103). Main Outcomes and Measures The primary outcome was kidney failure–free days during the 28-day period after randomization, measured as (1) the proportion of patients who never developed kidney failure and (2) median number of days alive and free of kidney failure for patients who did not survive, who experienced kidney failure, or both. Rates of renal replacement therapy, mortality, and serious adverse events were secondary outcomes. Results A total of 409 patients (median age, 66 years; men, 58.2%) were included in the study, with a median time to study drug administration of 3.5 hours after diagnosis of shock. The number of survivors who never developed kidney failure was 94 of 165 patients (57.0%) in the vasopressin group and 93 of 157 patients (59.2%) in the norepinephrine group (difference, −2.3% [95% CI, −13.0% to 8.5%]). The median number of kidney failure–free days for patients who did not survive, who experienced kidney failure, or both was 9 days (interquartile range [IQR], 1 to –24) in the vasopressin group and 13 days (IQR, 1 to –25) in the norepinephrine group (difference, −4 days [95% CI, −11 to 5]). There was less use of renal replacement therapy in the vasopressin group than in the norepinephrine group (25.4% for vasopressin vs 35.3% for norepinephrine; difference, −9.9% [95% CI, −19.3% to −0.6%]). There was no significant difference in mortality rates between groups. In total, 22 of 205 patients (10.7%) had a serious adverse event in the vasopressin group vs 17 of 204 patients (8.3%) in the norepinephrine group (difference, 2.5% [95% CI, −3.3% to 8.2%]). Conclusions and Relevance Among adults with septic shock, the early use of vasopressin compared with norepinephrine did not improve the number of kidney failure–free days. Although these findings do not support the use of vasopressin to replace norepinephrine as initial treatment in this situation, the confidence interval included a potential clinically important benefit for vasopressin, and larger trials may be warranted to assess this further

Die Surfactantkonversion als enzymatischer Prozeß : Ist das Surfactantprotein SP-B ein Substrat der Konvertase?

Das in der Alveole der Säugerlungen vorkommende Surfactantmaterial kann in sogenannte small und large surfactant aggregates aufgetrennt werden. Zu den large surfactant aggregates zählen Lamellarkörperchen und tubuläres Myelin, also die biophysikalisch hochaktiven Präkursoren des interfacialen Surfactantfilms. Unter den Prämissen einer akuten respiratorischen Insuffizienz ist wiederholt festgestellt worden, dass die Verteilung zwischen den large surfactant aggregates und small surfactant aggregates sehr zugunsten der small surfactant aggregates verschoben ist. Hieraus resultierend findet sich ein Übergewicht dieser, biophysikalisch weitgehend inaktiven, Abbauprodukte des Grenzflächenfilms. Vor diesem Hintergrund wurde in der vorliegenden Doktorarbeit der Fragestellung nachgegangen, wodurch die alveoläre Umwandlung der large in die small surfactant aggregates, ein als Surfactantkonversion bezeichneter Vorgang, vermittelt wird, und ob diese Surfactantkonversion ein enzymatisch getriggerter Prozess ist. Zur Beantwortung dieser Frage wurde als Ausgangsmaterial eine gepoolte bronchoalveoläre Lavage von gesunden Kaninchen, sowie ein rekonstituiertes Surfactantmaterial verwendet. Methodisch kamen weiterhin chromatographische, elektrophoretische, biophysikalische Verfahren, sowie Enzymaktivitäts-Assays zur Anwendung. Zunächst einmal konnte festgestellt werden, dass für die weitreichende Konversion von Surfactant in vitro in der Tat die Gegenwart einer Esterase notwendig ist. Weiterhin ergab sich im Rahmen der Rekonstitutionsversuche mit variablen Surfactant-Apoproteinen ebenfalls der Hinweis, dass vor allen Dingen der relative Gehalt an SP-B einen weitreichenden Einfluss auf den Konversionsgrad ausübt. Bei der Untersuchung der Herkunft der Esteraseaktivität in der BAL zeigte sich, dass im Überstand der resuspendierten Zellen der bronchoalveolären Lavage, wie auch im Zelllysat erhebliche Mengen an Esteraseaktivität nachweisbar waren. Weiterhin wurde festgestellt, dass unter den Bedingungen einer in vitro Konversion die Esteraseaktivität in den Subfraktionen alveolären Surfactans zeitabhängig abfiel. So war in den large surfactant aggregates 42 min nach Beginn der in vitro Konversion überhaupt keine Esteraseaktivität und nur noch etwa ein Viertel der Amidaseaktivität nachweisbar. Auf der Suche nach dem möglichen Substrat dieser Esterase wurde sowohl für die natürliche, wie auch für isoliert mit - an Sepharose gekoppelter - Esterase inkubiertem Surfactantprotein B der Nachweis erbracht, dass im Rahmen des Konversionsprozesses das dimere SP-B abgebaut und ein Spaltprodukt in einem Molekulargewichtsbereich von 11-14 kDa neu auftritt. Eine aminoterminale Sequenzierung dieses Spaltproduktes ergab zweifelsfrei den Nachweis eines Surfactantprotein B entstammenden Proteins und zwar des aminoterminalen Anteils des SP-B. Dieses Spaltprodukt konnte durch ein neu entwickeltes HPLC-Verfahren zur Auftrennung der hydrophoben Surfactantproteine aus der BAL weiter aufgereinigt werden. Zusammenfassend ergibt sich auf der Basis der hier vorliegenden Daten der Befund, dass die Umwandlung von large in small surfactant aggregates und der hiermit verbundene Verlust der Oberflächenaktivität nicht nur von der Größe der Oberflächenveränderung, sondern zudem von der Gegenwart einer enzymatischen Aktivität abhängig sind. Im Rahmen der hier durchgeführten Untersuchung konnte der Nachweis einer Esteraseaktivität sowohl in den Zellen der BAL, wie auch im zellfreien Überstand erbracht werden. Als mögliches Substrat dieser Aktivität konnte das Surfactantprotein B identifiziert werden, für welches das Auftreten eines 11-14 kDa großen Spaltproduktes einwandfrei belegt werden konnte. Aus der Kenntnis dieser Ergebnisse leiten sich mögliche neue Therapieoptionen für das Acute Respiratory Distress Syndrome, wie auch für den Ventilator Induced Lung Injury ab, bei denen Verschiebungen des alveolären Surfactantpools zugunsten der small surfactant aggregates wiederholt beschrieben worden sind.The alveolar surfactant pool can be separated into the \u27large surfactant aggregates\u27 (LSA) and the \u27small surfactant aggregates\u27 (SSA). The LSA, including lamellar bodies and tubular myelin, represent the biophysically highly active precursors of the interfacial surfactant film. Under cyclic area changes LSA are converted into the SSA (surfactant conversion). In contrast to LSA the SSA are clearly less surface active. Under clinical conditions of the acute respiratory distress syndrome, the balance of LSA to SSA is found to be switched in favour of SSA. Under these conditions, the alveolar surfactant pool predominantly consists of the largely inactive small surfactant aggregates, thus favouring impairment of gas exchange and lung function. Drawn against this background we aimed to elucidate the mechanisms of the conversion process. To answer this question pooled bronchoalveolar lavages of healthy rabbits and reconstituted surfactant preparations were subjected to repetitive surface area changes in vitro and extend of conversion was analysed. Besides chromatographic, electrophoretic and biophysical techniques, enzyme activity assays were applied for experimental investigations. It was found that an esterase activity is necessary for the induction of surfactant conversion under cyclic surface area changes. Experiments with various concentrations of the different surfactant proteins SP-A, SP-B or SP-C in reconstituted lipid mixtures revealed that only SP-B has a profound impact on the extent of in vitro conversion. Enzyme activity assays showed high esterase activity in complete cell suspensions of bronchoalveolar lavage and cell lysates. Under conditions of in vitro conversion, the esterase activity was found to decline in dependency of the incubation time, resulting in complete loss of esterase activity after 42 min of in vitro conversion. With emphasis on the potential role of surfactant proteins as substrates of esterase activity, we could show that in vitro conversion of BAL as well as incubation of isolated SP-B with sepharose linked esterase would result in a cleavage of dimeric SP-B and detection of a new protein band with a molecular range of 11-14 kilodalton. Amino terminal sequencing revealed that this protein truly represents a cleavage product of the amino terminal part of SP-B. Further purification of the cleavage product was performed by a new developed HPLC method for separation from other hydrophobic surfactant proteins and phospholipids. In summary the presented data support the conclusion that conversion of large surfactant aggregates to small surfactant aggregates not only depends on cyclic changes of the air-liquid interface, but also on the presence of an esterase activity. This esterase activity was detected in the cytosolic fraction of BAL cells, mostly alveolar macrophages. A SP-B cleavage product with a molecular range of 11-14 kilodalton was identified upon in vitro incubation of esterase with SP-B and after in vitro conversion of a rabbit BAL pool, suggesting that SP-B is a substrate of the alveolar esterase. These data may help to identify new molecular targets to treat acute respiratory distress syndrome and ventilator induced lung injury

The impact of dose calculation algorithms on partial and whole breast radiation treatment plans

BioMed CentralBackground: This paper compares the calculated dose to target and normal tissues when using pencil beam (PBC), superposition/convolution (AAA) and Monte Carlo (MC) algorithms for whole breast (WBI) and accelerated partial breast irradiation (APBI) treatment plans. Methods: Plans for 10 patients who met all dosimetry constraints on a prospective APBI protocol when using PBC calculations were recomputed with AAA and MC, keeping the monitor units and beam angles fixed. Similar calculations were performed for WBI plans on the same patients. Doses to target and normal tissue volumes were tested for significance using the paired Student’s t-test. Results: For WBI plans the average dose to target volumes when using PBC calculations was not significantly different than AAA calculations, the average PBC dose to the ipsilateral breast was 10.5% higher than the AAA calculations and the average MC dose to the ipsilateral breast was 11.8% lower than the PBC calculations. For ABPI plans there were no differences in dose to the planning target volume, ipsilateral breast, heart, ipsilateral lung, or contra-lateral lung. Although not significant, the maximum PBC dose to the contra-lateral breast was 1.9% higher than AAA and the PBC dose to the clinical target volume was 2.1% higher than AAA. When WBI technique is switched to APBI, there was significant reduction in dose to the ipsilateral breast when using PBC, a significant reduction in dose to the ipsilateral lung when using AAA, and a significant reduction in dose to the ipsilateral breast and lung and contra-lateral lung when using MC. Conclusions: There is very good agreement between PBC, AAA and MC for all target and most normal tissues when treating with APBI and WBI and most of the differences in doses to target and normal tissues are not clinically significant. However, a commonly used dosimetry constraint, as recommended by the ASTRO consensus document for APBI, that no point in the contra-lateral breast volume should receive >3% of the prescribed dose needs to be relaxed to >5%.FacultyReviewe