Investigating lipid headgroup composition within epithelial membranes: a systematic review.

Membrane lipid composition is often quoted within the literature, but with very little insight into how or why these compositions vary when compared to other biological membranes. One prominent area that lacks understanding in terms of rationale for lipid variability is the human gastro-intestinal tract (GIT). We have carried out a comprehensive systematic literature search to ascertain the key lipid components of epithelial membranes, with a particular focus on addressing the human GIT and to use compositional data to understand structural aspects of biological membranes. Both bacterial outer membranes and the human erythrocyte membrane were used as a comparison for the mammalian [epithelial] membranes and to understand variations in lipid presence. We show that phosphatidylcholine (PC) lipid types tend to dominate (33%) with phosphatidylethanolamines (PE) and cholesterol having very similar abundances (25 and 23% respectively). This systematic review presents a detailed insight into lipid headgroup composition and roles in various membrane types, with a summary of the distinction between the major lipid bilayer forming lipids and how peripheral lipids regulate charge and fluidity. The variety of lipids present in biological membranes is discussed and rationalised in terms function as well as cellular position.

Controlled lateral anisotropy in correlated manganite heterostructures by interface-engineered oxygen octahedral coupling.

Controlled in-plane rotation of the magnetic easy axis in manganite heterostructures by tailoring the interface oxygen network could allow the development of correlated oxide-based magnetic tunnelling junctions with non-collinear magnetization, with possible practical applications as miniaturized high-switching-speed magnetic random access memory (MRAM) devices. Here, we demonstrate how to manipulate magnetic and electronic anisotropic properties in manganite heterostructures by engineering the oxygen network on the unit-cell level. The strong oxygen octahedral coupling is found to transfer the octahedral rotation, present in the NdGaO3 (NGO) substrate, to the La2/3Sr1/3MnO3 (LSMO) film in the interface region. This causes an unexpected realignment of the magnetic easy axis along the short axis of the LSMO unit cell as well as the presence of a giant anisotropic transport in these ultrathin LSMO films. As a result we possess control of the lateral magnetic and electronic anisotropies by atomic-scale design of the oxygen octahedral rotation.

Transition from Reconstruction toward Thin Film on the (110) Surface of Strontium Titanate.

The surfaces of metal oxides often are reconstructed with a geometry and composition that is considerably different from a simple termination of the bulk. Such structures can also be viewed as ultrathin films, epitaxed on a substrate. Here, the reconstructions of the SrTiO3 (110) surface are studied combining scanning tunneling microscopy (STM), transmission electron diffraction, and X-ray absorption spectroscopy (XAS), and analyzed with density functional theory calculations. Whereas SrTiO3 (110) invariably terminates with an overlayer of titania, with increasing density its structure switches from n × 1 to 2 × n. At the same time the coordination of the Ti atoms changes from a network of corner-sharing tetrahedra to a double layer of edge-shared octahedra with bridging units of octahedrally coordinated strontium. This transition from the n × 1 to 2 × n reconstructions is a transition from a pseudomorphically stabilized tetrahedral network toward an octahedral titania thin film with stress-relief from octahedral strontia units at the surface.

Extreme mobility enhancement of two-dimensional electron gases at oxide interfaces by charge-transfer-induced modulation doping.

Two-dimensional electron gases (2DEGs) formed at the interface of insulating complex oxides promise the development of all-oxide electronic devices. These 2DEGs involve many-body interactions that give rise to a variety of physical phenomena such as superconductivity, magnetism, tunable metal-insulator transitions and phase separation. Increasing the mobility of the 2DEG, however, remains a major challenge. Here, we show that the electron mobility is enhanced by more than two orders of magnitude by inserting a single-unit-cell insulating layer of polar La(1-x)Sr(x)MnO3 (x = 0, 1/8, and 1/3) at the interface between disordered LaAlO3 and crystalline SrTiO3 produced at room temperature. Resonant X-ray spectroscopy and transmission electron microscopy show that the manganite layer undergoes unambiguous electronic reconstruction, leading to modulation doping of such atomically engineered complex oxide heterointerfaces. At low temperatures, the modulation-doped 2DEG exhibits Shubnikov-de Haas oscillations and fingerprints of the quantum Hall effect, demonstrating unprecedented high mobility and low electron density.

Dynamical Effects in Resonant X-Ray Diffraction.

Using resonant magnetic diffraction at the Ni L_{2,3} edge in a LaNiO_{3} superlattice, we show that dynamical effects beyond the standard kinematic approximation can drastically modify the resonant scattering cross section. In particular, the combination of extinction and refraction convert maxima to minima in the azimuthal-angle dependence of the diffracted intensity, which is commonly used to determine orbital and magnetic structures by resonant x-ray diffraction. We provide a comprehensive theoretical description of these effects by numerically solving Maxwell's equations in three dimensions. The understanding and description of dynamical diffraction enhances the capabilities of resonant x-ray scattering as a probe of electronic ordering phenomena in solids.

Adjacent Fe-Vacancy Interactions as the Origin of Room Temperature Ferromagnetism in (In(1-x)Fe(x))2O3.

Dilute magnetic semiconductors (DMSs) show great promise for applications in spin-based electronics, but in most cases continue to elude explanations of their magnetic behavior. Here, we combine quantitative x-ray spectroscopy and Anderson impurity model calculations to study ferromagnetic Fe-substituted In2O3 films, and we identify a subset of Fe atoms adjacent to oxygen vacancies in the crystal lattice which are responsible for the observed room temperature ferromagnetism. Using resonant inelastic x-ray scattering, we map out the near gap electronic structure and provide further support for this conclusion. Serving as a concrete verification of recent theoretical results and indirect experimental evidence, these results solidify the role of impurity-vacancy coupling in oxide-based DMSs.

Measuring partial fluorescence yield using filtered detectors.

Typically, X-ray absorption near-edge structure measurements aim to probe the linear attenuation coefficient. These measurements are often carried out using partial fluorescence yield techniques that rely on detectors having photon energy discrimination improving the sensitivity and the signal-to-background ratio of the measured spectra. However, measuring the partial fluorescence yield in the soft X-ray regime with reasonable efficiency requires solid-state detectors, which have limitations due to the inherent dead-time while measuring. Alternatively, many of the available detectors that are not energy dispersive do not suffer from photon count rate limitations. A filter placed in front of one of these detectors will make the energy-dependent efficiency non-linear, thereby changing the responsivity of the detector. It is shown that using an array of filtered X-ray detectors is a viable method for measuring soft X-ray partial fluorescence yield spectra without dead-time. The feasibility of this technique is further demonstrated using α-Fe2O3 as an example and it is shown that this detector technology could vastly improve the photon collection efficiency at synchrotrons and that these detectors will allow experiments to be completed with a much lower photon flux reducing X-ray-induced damage.

The role of macrolides in childhood non-cystic fibrosis-related bronchiectasis.

Non-cystic fibrosis-related bronchiectasis is a chronic inflammatory lung disease, which is regarded as an "orphan" lung disease, with little research devoted to the study of this condition. Bronchiectasis results in impaired quality of life and mortality if left untreated. The tools available in the armamentarium for the management of bronchiectasis entail antibiotic therapy traditionally used to treat exacerbations, stratagems to improve mucociliary clearance, and avoidance of toxins. Macrolides have been known for the last two decades to have not only anti-bacterial effects but immunomodulatory properties as well. In cystic fibrosis, the use of macrolides is well documented in subjects colonized with Pseudomonas aeruginosa, to improve quality of life and lung function. There is currently emerging evidence to suggest the benefit of macrolides in subjects not colonized with Pseudomonas aeruginosa. This beneficial effect has been less explored in the context of bronchiectasis from other causes. The purpose of this paper is to review the current literature on the use of macrolides in non-cystic fibrosis related bronchiectasis in paediatrics.

Common variable immunodeficiency disorders: What generalists should know.

Primary immune deficiency disorders (PIDDs) are common and underdiagnosed. Predominant antibody deficiencies (PADs) are the most common type of immune deficiency and comprise 55% of the immune deficiencies diagnosed.[1] Although immunoglobulin A (IgA) deficiency remains the most common type of PID, common variable immunodeficiency disorders remain the most common symptomatic PID for which medical therapy is sought.

Parental access to hospitalised children during infectious disease pandemics such as COVID-19.

The COVID-19 pandemic has resulted in many hospitals severely limiting or denying parents access to their hospitalised children. This article provides guidance for hospital managers, healthcare staff, district-level managers and provincial managers on parental access to hospitalised children during a pandemic such as COVID-19. It: (i) summarises legal and ethical issues around parental visitation rights; (ii) highlights four guiding principles; (iii) provides 10 practical recommendations to facilitate safe parental access to hospitalised children; (iv) highlights additional considerations if the mother is COVID-19-positive; and (v) provides considerations for fathers. In summary, it is a child's right to have access to his or her parents during hospitalisation, and parents should have access to their hospitalised children; during an infectious disease pandemic such as COVID-19, there is a responsibility to ensure that parental visitation is implemented in a reasonable and safe manner. Separation should only occur in exceptional circumstances, e.g. if adequate in-hospital facilities do not exist to jointly accommodate the parent/caregiver and the newborn/infant/child. Both parents should be allowed access to hospitalised children, under strict infection prevention and control (IPC) measures and with implementation of non-pharmaceutical interventions (NPIs), including handwashing/sanitisation, face masks and physical distancing. Newborns/infants and their parents/caregivers have a reasonably high likelihood of having similar COVID-19 status, and should be managed as a dyad rather than as individuals. Every hospital should provide lodger/boarder facilities for mothers who are COVID-19-positive, COVID-19-negative or persons under investigation (PUI), separately, with stringent IPC measures and NPIs. If facilities are limited, breastfeeding mothers should be prioritised, in the following order: (i) COVID-19-negative; (ii) COVID-19 PUI; and (iii) COVID-19-positive. Breastfeeding, or breastmilk feeding, should be promoted, supported and protected, and skin-to-skin care of newborns with the mother/caregiver (with IPC measures) should be discussed and practised as far as possible. Surgical masks should be provided to all parents/caregivers and replaced daily throughout the hospital stay. Parents should be referred to social services and local community resources to ensure that multidisciplinary support is provided. Hospitals should develop individual-level policies and share these with staff and parents. Additionally, hospitals should ideally track the effect of parental visitation rights on hospital-based COVID-19 outbreaks, the mental health of hospitalised children, and their rate of recovery.

COVID-19 in children: Should we be worried?

Reports indicate that children infected with SARS-CoV-2 have thus far presented with less severe disease than adults. Anxiety regarding a greater ability to transmit the virus is largely unfounded and has played a significant role in the decision to allow children to return to school. In some patients, however, especially in infants and in those with underlying comorbidities, severe disease must be anticipated and planned for accordingly. The most relevant severe clinical presentation in addition to the established respiratory complications, is that of a multisystem inflammatory disorder, with features resembling Kawasaki disease. The impact of the pandemic on the economic and social wellbeing of children, including food insecurity and care when parents are ill, cannot be ignored. During this pandemic, it is imperative to ensure access to routine and emergency medical services to sick children. In so doing, potentially devastating medical and socioeconomic consequences can be mitigated.

A case series and literature review on patients with rhinological complications secondary to the use of cocaine and levamisole.

BACKGROUND: Levamisole is an increasingly common cutting agent used with cocaine. Both cocaine and levamisole can have local and systemic effects on patients. METHODS: A retrospective case series was conducted of patients with a cocaine-induced midline destructive lesion or levamisole-induced vasculitis, who presented to a Dundee hospital or the practice of a single surgeon in Paisley, from April 2016 to April 2019. A literature review on the topic was also carried out. RESULTS: Nine patients from the two centres were identified. One patient appeared to have levamisole-induced vasculitis, with raised proteinase 3, perinuclear antineutrophil cytoplasmic antibodies positivity and arthralgia which improved on systemic steroids. The other eight patients had features of a cocaine-induced midline destructive lesion. CONCLUSION: As the use of cocaine increases, ENT surgeons will see more of the complications associated with it. This paper highlights some of the diagnostic issues and proposes a management strategy as a guide to this complex patient group. Often, multidisciplinary management is needed.

Allergic sensitisation in South Africa: Exploring regional variation in sensitisation.

BACKGROUND: Allergy is a common health problem in South Africa (SA), and a rational approach to allergy testing is essential to ensure cost-effective as well as optimal patient diagnosis and management. OBJECTIVES: To review allergy testing data with respect to current national testing recommendations, and to explore the regional variations in sensitisation. METHODS: Retrospective data review on allergy testing from a private pathology provider in SA over a 2-year period. Data on skin-prick testing (SPT) and allergen-specific IgE testing originating from all the provinces of SA were collected and analysed with regards to allergen positivity rate and regional sensitisation patterns. RESULTS: Among the patients (N=45 0320) tested for a suspected inhalant allergy, 46% tested positive. Only 45% of these received additional testing for the nine recommended inhalant allergens included in the current national testing protocol. Among the patients (N=6 775) who received SPT for a suspected inhalant allergy, 59% yielded one or more positive results. The most frequent sensitising allergens were house dust mite (Dermatophagoides pteronyssinus) and grass pollen. The house dust mite, Blomia tropicalis, was a significant sensitiser in coastal regions. SPT identified two other important regional allergens which are not included in the current recommendations for inhalant allergen-specific IgE testing. CONCLUSIONS: The current diagnostic recommendations include allergens that demonstrate significant sensitisation in all regions of SA. Two additional allergens that show significant regional sensitisation in the South African population were identified. These findings may aid the recommendations for the most appropriate and cost-effective approach to allergy testing of symptomatic patients in SA.

Transition from a uni- to a bimodal interfacial charge distribution in [Formula: see text]/[Formula: see text] upon cooling.

We present a combined resonant soft X-ray reflectivity and electric transport study of [Formula: see text]/[Formula: see text] field effect devices. The depth profiles with atomic layer resolution that are obtained from the resonant reflectivity reveal a pronounced temperature dependence of the two-dimensional electron liquid at the [Formula: see text]/[Formula: see text] interface. At room temperature the corresponding electrons are located close to the interface, extending down to 4 unit cells into the [Formula: see text] substrate. Upon cooling, however, these interface electrons assume a bimodal depth distribution: They spread out deeper into the [Formula: see text] and split into two distinct parts, namely one close to the interface with a thickness of about 4 unit cells and another centered around 9 unit cells from the interface. The results are consistent with theoretical predictions based on oxygen vacancies at the surface of the [Formula: see text] film and support the notion of a complex interplay between structural and electronic degrees of freedom.

Diagnosis and management of community-acquired pneumonia in children: South African Thoracic Society guidelines.

BACKGROUND: Pneumonia remains a major cause of morbidity and mortality amongst South African children. More comprehensive immunisation regimens, strengthening of HIV programmes, improvement in socioeconomic conditions and new preventive strategies have impacted on the epidemiology of pneumonia. Furthermore, sensitive diagnostic tests and better sampling methods in young children improve aetiological diagnosis. OBJECTIVES: To produce revised guidelines for pneumonia in South African children under 5 years of age. METHODS: The Paediatric Assembly of the South African Thoracic Society and the National Institute for Communicable Diseases established seven expert subgroups to revise existing South African guidelines focusing on: (i) epidemiology; (ii) aetiology; (iii) diagnosis; (iv) antibiotic management and supportive therapy; (v) management in intensive care; (vi) prevention; and (vii) considerations in HIV-infected or HIVexposed, uninfected (HEU) children. Each subgroup reviewed the published evidence in their area; in the absence of evidence, expert opinion was accepted. Evidence was graded using the British Thoracic Society (BTS) grading system. Sections were synthesized into an overall guideline which underwent peer review and revision. RECOMMENDATIONS: Recommendations include a diagnostic approach, investigations, management and preventive strategies. Specific recommendations for HIV infected and HEU children are provided. VALIDATION: The guideline is based on available published evidence supplemented by the consensus opinion of SA paediatric experts. Recommendations are consistent with those in published international guidelines.

Chronic rhinitis in South Africa - more than just allergy!

Chronic rhinitis is a troublesome condition for sufferers. It is tempting to label all patients with chronic nasal symptoms as having allergic rhinitis (AR), but many such patients have other causes of chronic rhinitis that need a specific diagnosis and management strategy. Even when the patient fully fits the definition of AR, their condition will be best served by combining medication with ongoing patient education.

Effect of growth time on the surface and adhesion properties of Lactobacillus rhamnosus GG.

AIMS: To investigate the changes in the surface properties of Lactobacillus rhamnosus GG during growth, and relate them with the ability of the Lactobacillus cells to adhere to Caco-2 cells. METHODS AND RESULTS: Lactobacillus rhamnosus GG was grown in complex medium, and cell samples taken at four time points and freeze dried. Untreated and trypsin treated freeze dried samples were analysed for their composition using SDS-PAGE analysis and Fourier transform infrared spectroscopy (FTIR), hydrophobicity and zeta potential, and for their ability to adhere to Caco-2 cells. The results suggested that in the case of early exponential phase samples (4 and 8 h), the net surface properties, i.e. hydrophobicity and charge, were determined to a large extent by anionic hydrophilic components, whereas in the case of stationary phase samples (13 and 26 h), hydrophobic proteins seemed to play the biggest role. Considerable differences were also observed between the ability of the different samples to adhere to Caco-2 cells; maximum adhesion was observed for the early stationary phase sample (13 h). The results suggested that the adhesion to Caco-2 cells was influenced by both proteins and non-proteinaceous compounds present on the surface of the Lactobacillus cells. CONCLUSION: The surface properties of Lact. rhamnosus GG changed during growth, which in return affected the ability of the Lactobacillus cells to adhere to Caco-2 cells. SIGNIFICANCE AND IMPACT OF THE STUDY: The levels of adhesion of Lactobacillus cells to Caco-2 cells were influenced by the growth time and reflected changes on the bacterial surface. This study provides critical information on the physicochemical factors that influence bacterial adhesion to intestinal cells.

The formulation and introduction of a 'can't intubate, can't ventilate' algorithm into clinical practice.

Both the American Society of Anesthesiologists and the Difficult Airway Society of the United Kingdom have published guidelines for the management of unanticipated difficult intubation. Both algorithms end with the 'can't intubate, can't ventilate' scenario. This eventuality is rare within elective anaesthetic practice with an estimated incidence of 0.01-2 in 10,000 cases, making the maintenance of skills and knowledge difficult. Over the last four years, the Department of Anaesthetics at the Royal Perth Hospital have developed a didactic airway training programme to ensure staff are appropriately trained to manage difficult and emergency airways. This article discusses our training programme, the evaluation of emergency airway techniques and subsequent development of a 'can't intubate, can't ventilate' algorithm.

The use of mandibular nerve block to predict safe anaesthetic induction in patients with acute trismus.

Acute trismus can be caused by pain, muscle spasm, swelling or mechanical obstruction. Unfortunately, the cause is not always obvious during pre-operative airway assessment. In this pilot study, we prospectively evaluated mandibular nerve block as a pre-operative tool to identify patients with reversible causes of trismus, namely pain or spasm, in order to allow safe anaesthetic induction. Six patients with unilateral fractured mandibles and trismus received a mandibular nerve block before induction of general anaesthesia. There was an increase in maximal inter-incisor gap after the blocks (median (range) distance: pre-block 16.5 (14-30) and post-block 34 (32-35) mm; p = 0.027), and no further improvement after induction of general anaesthesia (post-induction 37 (30-40) mm; p = 0.276 compared with post-block). There was an improvement in pain scores (p = 0.027), and no side-effects were detected. Pre-operative mandibular nerve blockade appears to reverse trismus caused by pain and muscle spasm, allowing the anaesthetist to decide whether awake intubation is genuinely indicated.