Low Tg, strongly segregated, ABA triblock copolymers: a rheological and structural study

ABA triblock copolymers can form microphase separated structures where the B blocks form bridges between A domains, leading to reversible networks interesting for a variety of applications such as pressure sensitive adhesives or thermoplastic elastomers. However, a major drawback of these systems is their rapid loss of mechanical properties upon temperature increase. A potential way to circumvent this limitation would be to design ABA triblock copolymers that keep their microphase separation at high temperatures. In this paper, we report on all-soft ABA triblock copolymers having a poly(n-butyl acrylate) (PnBA) central block and poly(heptafluorobutyl acrylate) (PHFBA) outer blocks. By introducing fluorinated units, the incompatibility between the blocks is largely increased, allowing strong segregation between the block domains, which preserve the microphase separation up to high temperatures despite the low glass transition temperature of the blocks, as shown by temperature dependent SAXS measurements. We study the properties of different copolymers, with similar PHFBA volume fractions but different block lengths. Linear shear rheology measurements revealed the presence of a second, low frequency, plateau whose onset and length depend on the PnBA and PHFBA length, respectively. This plateau also persists up to higher temperatures for longer PHFBA blocks.

Association of food insecurity with health, access to care, affordability of care, financial burden of care, and financial hardships among US adults during the COVID-19 pandemic

OBJECTIVES

To examine the associations between food insecurity and health, access to care, affordability of care, financial burden of care, and financial hardships among US adults during the COVID-19 pandemic and examine whether the associations were less pronounced among adults with safety nets.

STUDY DESIGN

We conducted a retrospective longitudinal cohort study using the 2020-2021 Medical Expenditure Panel Survey.

METHODS

Linear probability models were used to assess the associations between food insecurity in one year and the outcomes of interest in the following year while adjusting for baseline characteristics. We performed the analyses for the entire population and then conducted stratified analyses for adults with and without Supplemental Nutrition Assistance Program (SNAP) benefits or Medicaid coverage.

RESULTS

Compared with food-secure adults, food-insecure adults were 9.1 percentage points less likely to report life satisfaction and 9.9, 10.2, and 13.2 percentage points more likely to experience delays in getting medical care, postpone or forgo medical care because of cost, and struggle with paying medical bills. Food-insecure adults were 30.4, 27.2, and 23.5 percentage points more likely to face challenges in affording necessities, paying utility bills, and meeting rent or mortgage payments on time than food-secure adults. Notably, the strengths of these associations were attenuated among adults with SNAP benefits or Medicaid coverage.

CONCLUSIONS

Food insecurity was associated with poor health, limited access to and affordability of care, and a greater financial burden of care among US adults during the pandemic. Nevertheless, safety net programs can play a critical role in alleviating adverse consequences.

Double aortic arch: implications of antenatal diagnosis, differential growth of arches during pregnancy, associated abnormalities and postnatal outcome

OBJECTIVES

To evaluate the prenatal characteristics of double aortic arch (DAA), assess the relative size of the arches and their growth during pregnancy, describe associated cardiac, extracardiac and chromosomal/genetic abnormalities and review postnatal presentation and clinical outcome.

METHODS

This was a retrospective cohort study of all fetuses with a confirmed diagnosis of DAA seen in five specialized referral centers in London, UK, between October 2012 and November 2019. Cases were identified from the hospitals' fetal databases. Fetal echocardiographic findings, intracardiac and extracardiac abnormalities, genetic defects, computed tomography (CT) findings and postnatal clinical presentation and outcome were evaluated.

RESULTS

A total of 79 fetuses with DAA were included. Of those assessed postnatally, 48.6% had an atretic left aortic arch (LAA), while 5.1% had an atretic LAA at the first fetal scan and were misdiagnosed antenatally with right aortic arch (RAA). The LAA was atretic in 55.8% of those who underwent CT. DAA was an isolated abnormality in 91.1% of cases; 8.9% of patients had an additional intracardiac abnormality and 2.5% had both intra- and extracardiac abnormalities. Among the 52 cases that underwent genetic testing, 11.5% had genetic abnormalities and, specifically, the 22q11 microdeletion was identified in 3.8% of patients. At a median follow-up of 993.5 days, 42.5% of patients had developed symptoms of tracheoesophageal compression (5.5% during the first month after birth) and 56.2% had undergone intervention. Statistical analysis using the χ-square test showed no significant relationship between morphology of DAA (patency of both aortic arches vs atretic LAA) and the need for intervention (P = 0.134), development of vascular ring symptoms (P = 0.350) or evidence of airway compression on CT (P = 0.193).

CONCLUSIONS

Most cases of DAA can be diagnosed easily at midgestation, as typically both arches are patent with a dominant RAA at this stage. However, we found that the LAA had become atretic in approximately half of the cases postnatally, supporting the theory of differential growth of the arches during pregnancy. DAA is usually an isolated abnormality; however, thorough assessment is required to exclude associated intra- and extracardiac anomalies and to determine the need for invasive prenatal genetic testing. Postnatally, early clinical assessment is needed and CT scan should be considered, irrespective of the presence of symptoms. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Small-Angle Neutron Scattering Study of the Structural Relaxation of Elongationally Oriented, Moderately Stretched Three-Arm Star Polymers

We present structural relaxation studies of a polystyrene star polymer after cessation of high-rate extensional flow. During the steady-state flow, the scattering pattern shows two sets of independent correlations peaks, reflecting the structure of a polymer confined in a fully oriented three-armed tube. Upon cessation of flow, the relaxation constitutes three distinct regimes. In a first regime, the perpendicular correlation peaks disappear, signifying disruption of the virtual tube. In a second regime, broad scattering arcs emerge, reflecting relaxation from highly aligned chains to more relaxed, still anisotropic form. New entanglements dominate the last relaxation regime where the scattering pattern evolves to a successively elliptical and circular pattern, reflecting relaxation via reptation.

Small-Angle X-Ray and Neutron Scattering on Photosynthetic Membranes

Ultrastructural membrane arrangements in living cells and their dynamic remodeling in response to environmental changes remain an area of active research but are also subject to large uncertainty. The use of noninvasive methods such as X-ray and neutron scattering provides an attractive complimentary source of information to direct imaging because in vivo systems can be probed in near-natural conditions. However, without solid underlying structural modeling to properly interpret the indirect information extracted, scattering provides at best qualitative information and at worst direct misinterpretations. Here we review the current state of small-angle scattering applied to photosynthetic membrane systems with particular focus on data interpretation and modeling.

Threading-Unthreading Transition of Linear-Ring Polymer Blends in Extensional Flow

Adding small amounts of ring polymers to a matrix of their linear counterparts is known to increase the zero-shear-rate viscosity because of linear-ring threading. Uniaxial extensional rheology measurements show that, unlike its pure linear and ring constituents, the blend exhibits an overshoot in the stress growth coefficient. By combining these measurements with ex-situ small-angle neutron scattering and nonequilibrium molecular dynamics simulations, this overshoot is shown to be driven by a transient threading-unthreading transition of rings embedded within the linear entanglement network. Prior to unthreading, embedded rings deform affinely with the linear entanglement network and produce a measurably stronger elongation of the linear chains in the blend compared to the pure linear melt. Thus, rings uniquely alter the mechanisms of transient elongation in linear polymers.

Evolution of local motifs and topological proximity in self-assembled quasi-crystalline phases

Using methods from the field of topological data analysis, we investigate the self-assembly and emergence of three-dimensional quasi-crystalline structures in a single-component colloidal system. Combining molecular dynamics and persistent homology, we analyse the time evolution of persistence diagrams and particular local structural motifs. Our analysis reveals the formation and dissipation of specific particle constellations in these trajectories, and shows that the persistence diagrams are sensitive to nucleation and convergence to a final structure. Identification of local motifs allows quantification of the similarities between the final structures in a topological sense. This analysis reveals a continuous variation with density between crystalline clathrate, quasi-crystalline, and disordered phases quantified by 'topological proximity', a visualization of the Wasserstein distances between persistence diagrams. From a topological perspective, there is a subtle, but direct connection between quasi-crystalline, crystalline and disordered states. Our results demonstrate that topological data analysis provides detailed insights into molecular self-assembly.

SAT0130 TREAT-TO-TARGET STRATEGY OF >8.000 PATIENTS WITH EARLY RHEUMATOID ARTHRITIS: DOES SMOKING AFFECT ACHIEVEMENT OF REMISSION ON METHOTREXATE AND TIME TO START OF FIRST BIOLOGIC? RESULTS FROM THE NATIONWIDE DANISH DANBIO REGISTRY

Background:

Smoking is a known risk factor for rheumatoid arthritis (RA). It is largely unknown whether smoking has any impact on disease activity and treatment outcomes (e.g. achieving remission on methotrexate and time to first biological disease modifying anti-rheumatic treatments (bDMARD)) in early RA with a modern treat-to-target strategy.

Objectives:

To explore if smoking was associated with treatment outcomes in newly diagnosed patients with RA starting first conventional synthetic (cs)DMARDs in routine care.

Methods:

Observational cohort study. Adult patients with RA starting first csDMARD during year 2010-2018 were identified in the Danish nationwide quality registry, DANBIO. Smoking status (current/never/previous) upon start of csDMARD (=baseline), disease activity, 1-year treatment outcomes and bDMARD treatment were retrieved from DANBIO. Data were censored Oct 2019.

Impact of smoking status was explored for the following outcomes: 1) median baseline disease activity baseline, 2) remission at 1-year (logistic regression analyses), 3) time to first bDMARD (Cox-regression analyses). Regression analyses were adjusted for gender and age.

Results:

Among 9515 patients, 8647 (91%) had available smoking status (Current 23%/never 50%/previous 27%) and were included. Baseline disease activity was independent of smoking status (Table 1). First line csDMARD was methotrexate in 91% of patients. Compared to never smokers, the current smokers were more often men, younger and sero-positive for IgM-RF and anti-CCP.

Table 1.

Patient characteristics and disease activity at baseline and 1 year stratified by smoking status. Numbers are medians (IQR) unless otherwise stated.

Smoking statusCurrentNeverPreviousBaselinePatient numbers, N200743082332Age, yrs58 (49-66)61 (48-71)62 (52-70)Female, %627163IgM-RF positive, %715465Anti-CCP positive, %715365DAS284.4 (3.4-5.3)4.4 (3.4-5.3)4.3 (3.3-5.3)CDAI18.7 (11.7-27.3)18.4 (10.9-27.4)18.5 (10.4-27.6)VAS patient global, mm60 (35-81)55 (30-77)55 (31-78)1 yearPatient number, N179338372053DAS282.6 (1.9-3.7)2.3 (1.7-3.4)2.5 (1.8-3.4)CDAI6.4 (2.8-12.5)4.9 (1.8-10.3)5.4 (2-10.8)DAS28-remission, %495753CDAI-remission, %273533VAS patient global, mm37 (14-67)29 (10-57)30 (11-58)

DAS28-response: DAS28(CRP)≤2.6; CDAI-remission: CDAI≤2.8

Never and previous smokers had higher odds of remission at 1 year’s follow-up compared to current smokers. In adjusted Cox regression analyses, baseline smoking was associated with shorter time to start of first bDMARD (Table 2).

Table 2.

Impact of baseline smoking status on treatment outcomes

ComparisonOdds Ratio (95% CI)pDAS28-remission 1 yr, yes vs. no*Never vs. current smoker1.43 (1.27;1.62)<0.001Previous vs. current1.14 (0.99;1.30)0.07CDAI remission 1 yr, yes vs. no*Never vs. current1.53 (1.34;1.75)<0.001Previous vs. current1.29 (1.11;1.50)<0.001ComparisonHazard Ratio (95% CI)pStart of bDMARD duringfollow-up**Never vs current smoker0.85 (0.76;0.96)0.006Previous vs. current1.05 (0.93;1.19)0.4

*Logistic regression analyses (adjusted for gender and age)

** Cox regression analyses (adjusted for gender and age)

Conclusion:

In this observational study of >8000 patients with RA starting a first csDMARD, current smoking was associated with lower odds of achieving remission on methotrexate and higher chance of having started bMDARD compared to never smokers. Seropositivity may be an intermediate variable. Further analyses are planned to study impact of comorbidities and other confounding factors.

Acknowledgments :

Thank you to all patients and departments who contribute to the DANBIO registry

Disclosure of Interests: :

Bente Glintborg Grant/research support from: Grants from Pfizer, Biogen and Abbvie, Oliver Hendricks Grant/research support from: Pfizer, MSD, Ada Colic Consultant of: Advisory board Sanofi, Hanne Merete Lindegaard: None declared, Rabiah Ahmed: None declared, Anne Gitte Loft Grant/research support from: Novartis, Consultant of: AbbVie, MSD, Novartis, Pfizer and UCB, Speakers bureau: AbbVie, MSD, Novartis, Pfizer and UCB, Gina Kollerup Speakers bureau: Eli Lilly, Marlene Andersen: None declared, Jolanta Grydehøj: None declared, Johnny Raun: None declared, Toke Thorgrimsen: None declared, Kasper Mortensen: None declared, Line Uhrenholt Speakers bureau: Abbvie, Eli Lilly and Novartis (not related to the submitted work), Dorte Jensen: None declared, Iben Ruge Grant/research support from: Novo Nordisk Foundation, Maren Kalisz: None declared, Kamilla Danebod: None declared, Niels Lomborg: None declared, Niels Steen Krogh: None declared, Merete L. Hetland Grant/research support from: BMS, MSD, AbbVie, Roche, Novartis, Biogen and Pfizer, Consultant of: Eli Lilly, Speakers bureau: Orion Pharma, Biogen, Pfizer, CellTrion, Merck and Samsung Bioepis

Mechanisms of crystallisation in polysorbates and sorbitan esters

Solid-state behaviour of the commonly used pharmaceutical excipient polysorbates, and their non-ethoxylated equivalents.

Stretching PEO-PPO Type of Star Block Copolymer Gels: Rheology and Small-Angle Scattering

Cross-linked Tetronic star block copolymer gels, based on poly(ethylene oxide) and poly(propylene oxide), behave quite regular with respect to mechanical properties, but exhibits unusual absence of structural response to strain. The elastic response is linear up to more than 100% strain, with a steady-state modulus of the order of 0.01 MPa after an initial stress relaxation. Neutron and X-ray scattering experiments show a consistent but unexpected response to uniaxial strain, with no changes in characteristic molecular dimensions. Upon strain beyond about 100%, that is, when the stress-strain curve is no longer linear, structural texture appears and becomes even more pronounced upon further strain, thus, indicating alignment of the self-assembled hexagonally ordered cylindrical micelles with the cylinder-axis perpendicular to the strain. It is proposed that the main structural response to large-amplitude strain is related to a layer-dominated structure of cross-linked star molecules.

Towards biomimics of cell membranes: Structural effect of phosphatidylinositol triphosphate (PIP3) on a lipid bilayer

Phosphoinositide (PIP) lipids are anionic phospholipids playing a fundamental role for the activity of several transmembrane and soluble proteins. Among all, phosphoinositol-3',4',5'-trisphosphate (PIP₃) is a secondary signaling messenger that regulates the function of proteins involved in cell growth and gene transcription. The present study aims to reveal the structure of PIP-containing lipid membranes, which so far has been little explored. For this purpose, supported lipid bilayers (SLBs) containing 1,2-dioleoyl-sn-glycero-3-phospho-(1'-myo-inositol-3',4',5'-trisphosphate (DOPIP₃) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) were used as mimics of biomembranes. Surface sensitive techniques, i.e. Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), Atomic Force Microscopy (AFM) and Neutron Reflectometry (NR), provided detailed information on the formation of the SLB and the location of DOPIP₃ in the lipid membrane. Specifically, QCM-D and AFM were used to identify the best condition for lipid deposition and to estimate the total bilayer thickness. On the other hand, NR was used to collect experimental structural data on the DOPIP₃ location and orientation within the lipid membrane. The two bilayer leaflets showed the same DOPIP₃ concentration, thus suggesting the formation of a symmetric bilayer. The headgroup layer thicknesses of the pure POPC and the mixed POPC/DOPIP₃ bilayer suggest that the DOPIP₃-headgroups have a preferred orientation, which is not perpendicular to the membrane surface, but instead it is close to the surrounding lipid headgroups. These results support the proposed PIP₃ tendency to interact with the other lipid headgroups as PC, so far exclusively suggested by MD simulations.

Highly Anisotropic Glassy Polystyrenes Are Flexible

We show that stretching polystyrene melts at a rate faster than the inverse Rouse time, followed by rapid quenching below the glass transition temperature, results in a material that is flexible and remains so for at least six months. Oriented micro/nanofibers are observed in the flexible samples after the mechanical tests. The fibers are probably related to the highly aligned molecules in melt stretching. At room temperature, a tensile strength over 300 MPa has been achieved for the flexible polystyrenes.

Structural Studies of Three-Arm Star Block Copolymers Exposed to Extreme Stretch Suggests a Persistent Polymer Tube

We present structural small-angle neutron scattering studies of a three-armed polystyrene star polymer with short deuterated segments at the end of each arm. We show that the form factor of the three-armed star molecules in the relaxed state agrees with that of the random phase approximation of Gaussian chains. Upon exposure to large extensional flow conditions, the star polymers change conformation resulting in a highly stretched structure that mimics a fully extended three-armed tube model. All three arms are parallel to the flow, one arm being either in positive or negative stretching direction, while the two other arms are oriented parallel, right next to each other in the direction opposite to the first arm.

Cutting edges and weaving threads in the gene editing (Я)evolution: reconciling scientific progress with legal, ethical, and social concerns

Gene-editing technology, such as CRISPR/Cas9, holds great promise for the advancement of science and many useful applications technology. This foundational technology enables modification of the genetic structure of any living organisms with unprecedented precision. Yet, in order to enhance its potential for societal benefit, it is necessary to adapt rules and produce adequate regulations. This requires an interdisciplinary effort in legal thinking. Any legislative initiative needs to consider both the benefits and the problematic aspects of gene editing, from a broader societal and value-based perspective. This paper stems from an interdisciplinary research project seeking to identify and discuss some of the most pressing legal implications of gene-editing technology and how to address these. While the questions raised by gene editing are global, laws and regulations are to a great extent bound by national borders. This paper presents a European perspective, written for a global audience, and intends to contribute to the global debate. The analysis will include brief references to corresponding USA rules in order to place these European debates in the broader international context. Our legal analysis incorporates interdisciplinary contributes concerning the scientific state of the art, philosophical thinking regarding the precautionary principle and dual-use issues as well as the importance of communication, social perception, and public debate. Focusing mainly in the main regulatory and patent law issues, we will argue that (a) general moratoriums and blank prohibitions do a disservice to science and innovation; (b) it is crucial to carefully consider a complex body of international and European fundamental rights norms applicable to gene editing;

Rheological Link Between Polymer Melts with a High Molecular Weight Tail and Enhanced Formation of Shish-Kebabs

Presence of an ultra high molecular weight (UHMw) fraction in flowing polymer melts is known to facilitate formation of oriented crystalline structures significantly. The UHMw fraction manifests itself as a minor tail in the molar mass distribution and is hardly detectable in the canonical characterization methods. In this study, alternatively, we demonstrate how the nonlinear extensional rheology reveals to be a very sensitive characterization tool for investigating the effect of the UHMw-tail on the structural ordering mechanism. Samples containing a UHMw-tail relative to samples without, exhibit a clear increase in extensional stress that is directly correlated with the crystalline orientation of the quenched samples. Extensional rheology, particularly, in combination with linear creep measurements, thus, enables the conformational evolution of the UHMw-tail to be studied and linked to the enhanced formation of oriented structures.

Cross-Linked Amylose Bio-Plastic: A Transgenic-Based Compostable Plastic Alternative

Bio-plastics and bio-materials are composed of natural or biomass derived polymers, offering solutions to solve immediate environmental issues. Polysaccharide-based bio-plastics represent important alternatives to conventional plastic because of their intrinsic biodegradable nature. Amylose-only (AO), an engineered barley starch with 99% amylose, was tested to produce cross-linked all-natural bioplastic using normal barley starch as a control. Glycerol was used as plasticizer and citrate cross-linking was used to improve the mechanical properties of cross-linked AO starch extrudates. Extrusion converted the control starch from A-type to Vh- and B-type crystals, showing a complete melting of the starch crystals in the raw starch granules. The cross-linked AO and control starch specimens displayed an additional wide-angle diffraction reflection. Phospholipids complexed with Vh-type single helices constituted an integrated part of the AO starch specimens. Gas permeability tests of selected starch-based prototypes demonstrated properties comparable to that of commercial Mater-Bi^© plastic. The cross-linked AO prototypes had composting characteristics not different from the control, indicating that the modified starch behaves the same as normal starch. The data shows the feasibility of producing all-natural bioplastic using designer starch as raw material.

Direct monitoring of lipid transfer on exposure of citrem nanoparticles to an ethanol solution containing soybean phospholipids by combining synchrotron SAXS with microfluidics

Lipid exchange among citrem nanoparticles and an ethanol micellar solution containing soy phosphatidylcholine was investigated in situ by coupling small angle X-ray scattering with a microfluidic device. The produced soy phosphatidylcholine/citrem nanoparticles have great potential in the development of hemocompatible nanocarriers for drug delivery.

All-natural bio-plastics using starch-betaglucan composites

Grain polysaccharides represent potential valuable raw materials for next-generation advanced and environmentally friendly plastics. Thermoplastic starch (TPS) is processed using conventional plastic technology, such as casting, extrusion, and molding. However, to adapt the starch to specific functionalities chemical modifications or blending with synthetic polymers, such as polycaprolactone are required (e.g. Mater-Bi). As an alternative, all-natural and compostable bio-plastics can be produced by blending starch with other polysaccharides. In this study, we used a maize starch (ST) and an oat β-glucan (BG) composite system to produce bio-plastic prototype films. To optimize performing conditions, we investigated the full range of ST:BG ratios for the casting (100:0, 75:25, 50:50, 25:75 and 0:100 BG). The plasticizer used was glycerol. Electron Paramagnetic Resonance (EPR), using TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) as a spin probe, showed that the composite films with high BG content had a flexible chemical environment. They showed decreased brittleness and improved cohesiveness with high stress and strain values at the break. Wide-angle X-ray diffraction displayed a decrease in crystallinity at high BG content. Our data show that the blending of starch with other natural polysaccharides is a noteworthy path to improve the functionality of all-natural polysaccharide bio-plastics systems.

Recent advances in X-ray compatible microfluidics for applications in soft materials and life sciences

The increasingly narrow and brilliant beams at X-ray facilities reduce the requirements for both sample volume and data acquisition time. This creates new possibilities for the types and number of sample conditions that can be examined but simultaneously increases the demands in terms of sample preparation. Microfluidic-based sample preparation techniques have emerged as elegant alternatives that can be integrated directly into the experimental X-ray setup remedying several shortcomings of more traditional methods. We review the use of microfluidic devices in conjunction with X-ray measurements at synchrotron facilities in the context of 1) mapping large parameter spaces, 2) performing time resolved studies of mixing-induced kinetics, and 3) manipulating/processing samples in ways which are more demanding or not accessible on the macroscale. The review covers the past 15 years and focuses on applications where synchrotron data collection is performed in situ, i.e. directly on the microfluidic platform or on a sample jet from the microfluidic device. Considerations such as the choice of materials and microfluidic designs are addressed. The combination of microfluidic devices and measurements at large scale X-ray facilities is still emerging and far from mature, but it definitely offers an exciting array of new possibilities.

Direct monitoring of calcium-triggered phase transitions in cubosomes using small-angle X-ray scattering combined with microfluidics

This article introduces a simple microfluidic device that can be combined with synchrotron small-angle X-ray scattering (SAXS) for monitoring dynamic structural transitions. The microfluidic device is a thiol–ene-based system equipped with 125 µm-thick polystyrene windows, which are suitable for X-ray experiments. The device was prepared by soft lithography using elastomeric molds followed by a simple UV-initiated curing step to polymerize the chip material and simultaneously seal the device with the polystyrene windows. The microfluidic device was successfully used to explore the dynamics of the structural transitions of phytantriol/dioleoylphosphatidylglycerol-based cubosomes on exposure to a buffer containing calcium ions. The resulting SAXS data were resolved in the time frame between 0.5 and 5.5 s, and a calcium-triggered structural transition from an internal inverted-type cubic phase of symmetryIm3mto an internal inverted-type cubic phase of symmetryPn3mwas detected. The combination of microfluidics with X-ray techniques opens the door to the investigation of early dynamic structural transitions, which is not possible with conventional techniques such as glass flow cells. The combination of microfluidics with X-ray techniques can be used for investigating protein unfolding, for monitoring the formation of nanoparticles in real time, and for other biomedical and pharmaceutical investigations.

Nematic effects and strain coupling in entangled polymer melts under strong flow

We use small-angle neutron scattering (SANS) to study labeled short chains with and without the influence of an entangled and highly stretched surrounding environment of longer chains. We find unequivocal evidence of nematic effects as the blend chains in steady state flow are stretched a factor ∼1.5 more from the presence of the long chain nematic field. In the pure melt we confirm that the nonaffine mean-field result ν=0.5 for the strain coupling is still valid for very fast flows, while in the nematic system our analysis predicts an increased coupling constant. We provide a structural explanation for the two first regimes of the nonlinear relaxation, particularly a transition regime where the long chains are relaxing in a sea of reptating short chains.

Microemulsions as Potential Carriers of Nisin: Effect of Composition on Structure and Efficacy

Water-in-oil (W/O) microemulsions based on either refined olive oil (ROO) or sunflower oil (SO), distilled monoglycerides (DMG), and ethanol were used as nisin carriers in order to ensure its effectiveness as a biopreservative. This work presents experimental evidence on the effects of ethanol concentration, hydration, the nature of oil, and the addition of nisin on the nanostructure of the proposed inverse microemulsions as revealed by electrical conductivity measurements, dynamic light scattering (DLS), small angle X-ray scattering (SAXS), and electron paramagnetic resonance (EPR) spectroscopy. Modeling of representative SAXS profiles was applied to gain further insight into the effects of ethanol and solubilized water content on the inverse swollen micelles' size and morphology. With increasing ethanol content, the overall size of the inverse micelles decreased, whereas hydration resulted in an increase in the micellar size due to the penetration of water into the hydrophilic core of the inverse swollen micelles (hydration-induced swelling behavior). The dynamic properties of the surfactant monolayer were also affected by the nature of the used vegetable oil, the ethanol content, and the presence of the bioactive molecule, as evidenced by EPR spin probing experiments. According to simulation on the experimental spectra, two populations of spin probes at different polarities were revealed. The antimicrobial effect of the encapsulated nisin was evaluated using the well diffusion assay (WDA) technique against Lactococccus lactis. It was found that this encapsulated bacteriocin induced an inhibition of the microorganism growth. The effect was more pronounced at higher ethanol concentrations, but no significant difference was observed between the two used vegetable oils (ROO and SO).

Acute and chronic effects on central hemodynamics and arterial stiffness in professional rowers

Controversial data exist on acute and chronic effects of competitive sports on central hemodynamics and arterial stiffness. We investigated chronic as well as acute training effects in professional rowers. The trial was planned as a non-randomized, controlled pilot-study comparing athletes and controls. 13 German national team rowers (24.1 ± 1.5 years) and 12 controls (23.8 ± 0.8 years) participated. Aortic, brachial hemodynamics and arterial stiffness were measured (Arteriograph, TensioMed(®), Hungary) before and after a standardized exercise test. Chronic heart rate (49 [Formula: see text] 2 bpm versus 70 [Formula: see text] 2 bpm, p  <  0.05) as well as brachial diastolic pressure (65 [Formula: see text] 2 mmHg versus 74 [Formula: see text] 2 mmHg, p  <  0.05) was significantly lower in rowers. Physical power (305 [Formula: see text] 63 versus 158 [Formula: see text] 60 W, p  <  0.001) was better. Chronic aortic pulse pressure (41.6 [Formula: see text] 6.0 versus 35.2 [Formula: see text] 3.8 mmHg; p  <  0.01) and AIx (9.1 [Formula: see text] 5.4 versus 7.0 [Formula: see text] 10.2; p  <  0.01) were significantly higher in athletes. After the all-out test (acute effects) pulse wave velocity (rowers: 6.6 [Formula: see text] 1.2 m s(-1) versus 7.8 [Formula: see text] 1.6 m s(-1), p  <  0.001; control group 6.0 [Formula: see text] 0.4 m s(-1) versus 8.0 [Formula: see text] 1.4 m s(-1), p  =  0.005) and heart rate (rowers: 49 [Formula: see text] 2 bpm versus 91 [Formula: see text] 3 bpm, p  <  0.001; control group 70 [Formula: see text] 2 bpm versus 92 [Formula: see text] 4 bpm, p  <  0.001) increased significantly in both groups. The controls' aortic AIx (7.0 [Formula: see text] 10.2 versus 2.0 [Formula: see text] 6.0; p  <  0.01) decreased significantly after exercise. Professional rowers showed higher chronic aortic pulse pressure and arterial stiffness. Given the risk associated with elevated aortic pulse pressure and AIx for development of cardiovascular diseases, longterm observations of professional rowers are needed with respect to arterial stiffness and prognosis. Furthermore the acute effects need additional research.

Structural Study of Four-Armed Amphiphilic Star-Block Copolymers: Pristine and End-Linked Tetronic T1307

We present a comparative structural study of 30 wt % aqueous suspensions of two related systems based on 4-arm PEO-PPO type of macromolecules (Tetronic T1307, BASF) with the PPO block near the star center. One system concerns the pristine 4-arm PEO-PPO star block copolymer T1307. The second system is a 1:1 blend consisting of, respectively, tetra-amine (TAT) and tetra-N-hydroxysuccinimide (TNT) terminated T1307. The two systems show common characteristics which are also known from linear PEO-PPO type of copolymers (Pluronic, BASF): at low temperatures the measured structure is dominated by the characteristics of individual molecules, while at higher temperatures hydrophobic effects of the PPO domains cause self-assembly into spherical or rodlike micelles. These micelles form in both systems ordered mesophases. The pristine T1307 copolymer suspension behaves generally very similarly to linear PEO-PPO type of di- and triblock copolymers: unimers at low temperatures associating into micelles at higher temperatures, forming subsequently cubic and hexagonal phases upon further increase in temperatures. The cubic phase of the 30 wt % Tetronic T1307 has FCC symmetry. The structure of the cross-linked 30 wt % 1:1 TAT-TNT system is basically organized into two-dimensional network sheets. At low temperatures the system is rather disordered but still with a sharp correlation peak which is associated with the distance between neighboring network sheets. Upon raising temperatures, PPO self-assembly causes organization across neighboring sheets, resulting in cylinder-like assemblies perpendicular to the sheets. These cylinders form hexagonal structure.

Quantification of the information in small-angle scattering data

Small-angle X-ray and neutron scattering have become increasingly popular owing to improvements in instrumentation and developments in data analysis, sample handling and sample preparation. For some time, it has been suggested that a more systematic approach to the quantification of the information content in small-angle scattering data would allow for a more optimal experiment planning and a more reliable data analysis. In the present article, it is shown how ray-tracing techniques in combination with a statistically rigorous data analysis provide an appropriate platform for such a systematic quantification of the information content in scattering data. As examples of applications, it is shown how the exposure time at different instrumental settings or contrast situations can be optimally prioritized in an experiment. Also, the gain in information by combining small-angle X-ray and neutron scattering is assessed. While solution small-angle scattering data of proteins and protein–lipid complexes are used as examples in the present case study, the approach is generalizable to a wide range of other samples and experimental techniques. The source code for the algorithms and ray-tracing components developed for this study has been made available on-line.

Consensus guidelines for enhanced recovery after gastrectomy: Enhanced Recovery After Surgery (ERAS®) Society recommendations

BACKGROUND

Application of evidence-based perioperative care protocols reduces complication rates, accelerates recovery and shortens hospital stay. Presently, there are no comprehensive guidelines for perioperative care for gastrectomy.

METHODS

An international working group within the Enhanced Recovery After Surgery (ERAS®) Society assembled an evidence-based comprehensive framework for optimal perioperative care for patients undergoing gastrectomy. Data were retrieved from standard databases and personal archives. Evidence and recommendations were classified according to the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system and were discussed until consensus was reached within the group. The quality of evidence was rated 'high', 'moderate', 'low' or 'very low'. Recommendations were graded as 'strong' or 'weak'.

RESULTS

The available evidence has been summarized and recommendations are given for 25 items, eight of which contain procedure-specific evidence. The quality of evidence varies substantially and further research is needed for many issues to improve the strength of evidence and grade of recommendations.

CONCLUSION

The present evidence-based framework provides comprehensive advice on optimal perioperative care for the patient undergoing gastrectomy and facilitates multi-institutional prospective cohort registries and adequately powered randomized trials for further research.

Self-assembling peptides form nanodiscs that stabilize membrane proteins

New methods to handle membrane bound proteins, e.g. G-protein coupled receptors (GPCRs), are highly desirable. Recently, apoliprotein A1 (ApoA1) based lipoprotein particles have emerged as a new platform for studying membrane proteins, and it has been shown that they can self-assemble in combination with phospholipids to form discoidal shaped particles that can stabilize membrane proteins. In the present study, we have investigated an ApoA1 mimetic peptide with respect to its solution structure when in complex with phospholipids. This was achieved using a powerful combination of small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) supported by coarse-grained molecular dynamics simulations. The detailed structure of the discs was determined in unprecedented detail and it was found that they adopt a discoidal structure very similar to the ApoA1 based nanodiscs. We furthermore show that, like the ApoA1 and derived nanodiscs, these peptide discs can accommodate and stabilize a membrane protein. Finally, we exploit their dynamic properties and show that the 18A discs may be used for transferring membrane proteins and associated phospholipids directly and gently into phospholipid nanodiscs.

The effect of butter grains on physical properties of butter-like emulsions

Milk fat exists as globules in its natural state in milk. The potential of using globular fat to modulate the rheological properties and crystallization behavior in butter-like emulsions was studied in the present work. We conducted a comparative study of butter-like emulsions, with a fat phase consisting of 0, 10, 25, 50, or 100% anhydrous milk fat (AMF), the remaining fat being butter grains, and all samples containing 20% water, to obtain systematic variation in the ratio of globular fat. All emulsions were studied over 4wk of storage at 5°C. By combining small and large deformation rheology, we conducted a detailed characterization of the rheological behavior of butter-like emulsions. We applied differential scanning calorimetry to monitor thermal behavior, confocal laser scanning microscopy for microstructural analysis, and low-field pulsed nuclear magnetic resonance spectrometry to measure solid fat content. By combining these techniques, we determined that increasing the fraction of globular fat (by mixing with butter grains) decreases the hardness of butter-like emulsions up to an order of magnitude at d 1. However, no difference was observed in thermal behavior as a function of butter grain content, as all emulsions containing butter grains revealed 2 endothermal peaks corresponding to the high (32.7°C ± 0.6) and medium (14.6°C ± 0.1) melting fractions of fatty acids. In terms of microstructure, decreasing the amount of butter grains in the emulsions resulted in formation of a denser fat crystal network, corresponding to increased hardness. Moreover, microstructural analysis revealed that the presence of butter grains resulted in faster formation of a continuous fat crystal network compared with the 100% AMF sample, which was dominated by crystal clusters surrounded by liquid oil. During storage, hardness remained stable and no changes in thermal behavior were observed, despite an increase in solid fat content of up to 5%. After 28d of storage, we observed no difference in either microstructural or rheological properties, indicating that formation of primary bonds occurs primarily within the first day of storage. The rheological behavior of butter-like emulsions is not determined solely by hardness, but also by stiffness related to secondary bonds within the fat crystal network. The complex rheological behavior of milk fat-based emulsions is better characterized using multiple parameters.

Small-angle scattering gives direct structural information about a membrane protein inside a lipid environment

Monomeric bacteriorhodopsin (bR) reconstituted into POPC/POPG-containing nanodiscs was investigated by combined small-angle neutron and X-ray scattering. A novel hybrid approach to small-angle scattering data analysis was developed. In combination, these provided direct structural insight into membrane-protein localization in the nanodisc and into the protein-lipid interactions. It was found that bR is laterally decentred in the plane of the disc and is slightly tilted in the phospholipid bilayer. The thickness of the bilayer is reduced in response to the incorporation of bR. The observed tilt of bR is in good accordance with previously performed theoretical predictions and computer simulations based on the bR crystal structure. The result is a significant and essential step on the way to developing a general small-angle scattering-based method for determining the low-resolution structures of membrane proteins in physiologically relevant environments.