Membrane Defects Research Articles

SARS-CoV-2 FP1 Destabilizes Lipid Membranes and Facilitates Pore Formation.

SARS-CoV-2 viral entry requires membrane fusion, which is facilitated by the fusion peptides within its spike protein. These predominantly hydrophobic peptides insert into target membranes; however, their precise mechanistic role in membrane fusion remains incompletely understood. Here, we investigate how FP1 (SFIEDLLFNKVTLADAGFIK), the N-terminal fusion peptide, modulates membrane stability and barrier function across various model membrane systems. Through a complementary suite of biophysical techniques-including electrophysiology, fluorescence spectroscopy, and atomic force microscopy-we demonstrate that FP1 significantly promotes pore formation and alters the membrane's mechanical properties. Our findings reveal that FP1 reduces the energy barrier for membrane defect formation and stimulates the appearance of stable conducting pores, with effects modulated by membrane composition and mechanical stress. The observed membrane-destabilizing activity suggests that, beyond its anchoring function, FP1 may facilitate viral fusion by locally disrupting membrane integrity. These results provide mechanistic insights into SARS-CoV-2 membrane fusion mechanisms and highlight the complex interplay between fusion peptides and target membranes during viral entry.

Lipid Packing Defects are Necessary and Sufficient for Membrane Binding of α-Synuclein.

α-Synuclein (αSyn), an intrinsically disordered protein implicated in Parkinson's disease, is potentially thought to initiate aggregation through binding to cellular membranes. Previous studies have suggested that anionic membrane charge is necessary for this binding. However, these studies largely focus on unmodified αSyn, while nearly all αSyn in the body is N-terminally acetylated (NTA). NTA dramatically shifts the narrative by diminishing αSyn's reliance on anionic charge for membrane binding. Instead, we demonstrate that membrane packing defects are the dominant forces driving NTA-αSyn interactions, challenging the long-standing paradigm that anionic membranes are essential for αSyn binding. Using fluorescence microscopy and circular dichroism spectroscopy, we monitored the binding of NTA-αSyn to reconstituted membrane surfaces with different lipid compositions. Phosphatidylcholine and phosphatidylserine concentrations were varied to control surface charge, while phospholipid tail unsaturation and methylation were varied to control lipid packing. All-atom molecular dynamics simulations of lipid bilayers supported the observation that membrane packing defects are necessary for NTA-αSyn binding and that defect-rich membranes are sufficient for NTA-αSyn binding regardless of membrane charge. We further demonstrated that this affinity for membrane defects persisted in reconstituted, cholesterol-containing membranes that mimicked the physiological lipid composition of synaptic vesicles. Increasing phospholipid unsaturation in these mimics led to more membrane packing defects and a corresponding increase in NTA-αSyn binding. Altogether, our results point to a mechanism for the regulation of NTA-αSyn binding in biological membranes that extends beyond phospholipid charge to the structural properties of the lipids themselves.

Investigating How Lysophosphatidylcholine and Lysophosphatidylethanolamine Enhance the Membrane Permeabilization Efficacy of Host Defense Peptide Piscidin 1.

Lysophospholipids (LPLs) and host defense peptides (HDPs) are naturally occurring membrane-active agents that disrupt key membrane properties, including the hydrocarbon thickness, intrinsic curvature, and molecular packing. Although the membrane activity of these agents has been widely examined separately, their combined effects are largely unexplored. Here, we use experimental and computational tools to investigate how lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE), an LPL of lower positive spontaneous curvature, influence the membrane activity of piscidin 1 (P1), an α-helical HDP from fish. Four membrane systems are probed: 75:25 C16:0-C18:1 PC (POPC)/C16:0-C18:1 phosphoglycerol (POPG), 50:25:25 POPC/POPG/16:0 LPC, 75:25 C16:0-C18:1 PE (POPE)/POPG, and 50:25:25 POPE/POPG/14:0 LPE. Dye leakage, circular dichroism, and NMR experiments demonstrate that while the presence of LPLs alone does not induce leakage-proficient defects, it boosts the permeabilization capability of P1, resulting in an efficacy order of POPC/POPG/16:0 LPC > POPE/POPG/14:0 LPE > POPC/POPG > POPE/POPG. This enhancement occurs without altering the membrane affinity and conformation of P1. Molecular dynamics simulations feature two types of asymmetric membranes to represent the imbalanced ("area stressed") and balanced ("area relaxed") distribution of lipids and peptides in the two leaflets. The simulations capture the membrane thinning effects of P1, LPC, and LPE, and the positive curvature strain imposed by both LPLs is reflected in the lateral pressure profiles. They also reveal a higher number of membrane defects for the P1/LPC than P1/LPE combination, congruent with the permeabilization experiments. Altogether, these results show that P1 and LPLs disrupt membranes in a concerted fashion, with LPC, the more disruptive LPL, boosting the permeabilization of P1 more than LPE. This mechanistic knowledge is relevant to understanding biological processes where multiple membrane-active agents such as HDPs and LPLs are involved.

Directly Gel-Thermal Processing of Linker-Mixed Crystal-Glass Composite Membranes for Sorption-Preferential Gas Separation.

Membrane processes are promising for energy-saving industrial applications. However, efficient separation for some valuable gas mixtures with similar characteristics, such as CH4/N2 and O2/N2, remains extremely challenging. Metal-organic framework (MOF) membranes have been attracting intensive attention for gas sieving, but it is difficult to manufacture MOF membranes in scalability and precisely tune their transport property. In this study, Gel-thermal processing of linker-mixed MOF crystal-glass composite membranes is reported directly, with the mechanism of adjusting metal-linker bond strengths and angles to disrupt long-range periodicity of MOFs and promote glass phase formation, for sharply sorption-preferential gas separation. This strategy can be realized by using a simple, solvent/precursor-less, and cost-effective gel-thermal approach with two steps of gel coating and thermal conversion, thereby constructing crystal-glass composite membranes in a controllable, processable, versatile, and environmentally friendly route. Moreover, the mixed linkers enable preferential gas affinities and the ultramicroporous glasses can eliminate any membrane defects. The membranes exhibit outstanding gas separation performance for the challenging systems of CH4/N2 and O2/N2, with mixture selectivities up to 9.3 and 9.6, respectively, far exceeding those of polymer, MOF, and mixed-matrix membranes. The study provides an available route for architecting high-performance membranes for gas separations.

Role of Myofibroblasts in the Repair of Iatrogenic Preterm Membranes Subjected to Mechanical Stimulation.

We examined the role of myofibroblasts in regulating Cx43 and collagen structure in iatrogenic preterm amniotic membrane (AM) defects subjected to mechanical stimulation. Preterm AM specimens were collected from women undergoing planned preterm caesarean section after in utero intervention for correction of spina bifida by open fetal surgery (n=4 patients; preterm delivery at 34+0weeks to 35+0weeks). Control specimens taken 5cm away from the open fetal surgery defect site were compared with wound edge AM. In separate experiments, the effects of mechanical stimulation and co-treatment with Cx43 antisense on matrix and repair proteins were examined. Specimens were immunostained to detect αSMA and Cx43 in myofibroblasts and counterstained with DAPI to quantify nuclei shape. The direction of collagen fibrils in the wound edge region was examined by SHG imaging. Markers for matrix (collagen, elastin, GAG), inflammation (PGE2) and repair (TGFβ1) were examined by RT-qPCR and biochemical assays. In iatrogenic preterm AM specimens, the diameter of the open fetal surgery defect ranged between 3.5 and 7.5cm. At the wound edge of the open fetal surgery defect, αSMA positive myofibroblasts had deformed nuclei and showed abundant Cx43 localized in the cell bodies or formed plaques. In the fibroblast layer, collagen had degenerated in some regions or had polarity near the wound edge. In preterm AM defects, mechanical stimulation and Cx43 antisense increased the levels of collagen and elastin but not GAG or PGE2 release. Mechanical stimulation increased Cx43 and TGFβ1 gene expression. In open fetal surgery defects, myofibroblasts were elongated with collagen fibrils that either degenerated or had polarity. Whilst cells produced substantially higher Cx43 in the fibroblast than in the epithelial layer, they formed plaques, which may prevent migration and delay healing. Mechanical stimulation of preterm AM enhanced matrix repair proteins and the mechanotransduction should be explored to understand how Cx43 contributes to membrane integrity.

Highly responsive gas sensors based on grain boundary–rich polycrystalline few-layer MoS2 films for NO2 detection

Abstract This study addresses the issues of insufficient sensitivity and poor reversibility for NO2 detection by successfully fabricating a sensor based on uniform and high-quality few-layer MoS2 polycrystalline material using chemical vapor deposition. This approach aims to improve the response of the sensor by exploiting the abundance of grain boundary (GB) defects in polycrystalline MoS2 membranes. Comprehensive surface morphology analysis of the few-layer MoS2 polycrystalline films was conducted using microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy to characterize their chemical composition and properties. Subsequently, evaluation of 1–100-ppm NO2 was conducted at room temperature (25 °C). The results show excellent performance of the sensor, with a response range of 11–82.24. Notably, under ultraviolet excitation at room temperature, this sensor exhibits a response time of only 41 s to 50 ppm of NO2 with complete recovery and improved sensitivity, maintaining reliable stability over eight weeks. Furthermore, the findings reveal that the sensor demonstrates high selectivity toward NO2 gas with limit of detection and limit of qualification values of 10 and 34 ppb, respectively. Owing to the abundant adsorption sites provided by GB defects in polycrystalline thin films, the response performance of the sensor is effectively enhanced. This study provides valuable insights into the future design and development of high-performance NO2 gas sensors.

Mechanical Stability of Membranes in PEMWE

This study investigates the structural mechanics of membranes in proton exchange membrane water electrolysis (PEMWE) cells, with a particular focus on mechanical stressors and the resultant membrane deformation. Membrane defects such as cracks, pinholes, and thinning can occur due to mechanical stressors. Structural mechanical simulations can predict the membrane behaviour under stress if the boundary conditions are set accurately and the material models are chosen to fit experimental data. This presentation describes such model-based investigations and is divided into three parts. It begins with a general investigation of mechanical membrane behaviour in a PEMWE cell, followed by investigations regarding two different membrane reinforcing methods. Firstly, the study examines the mechanical stress exposure of Nafion® 117 membranes within PEMWE cells, with a focus on the gap geometry between the cell frame and porous transport layers (PTL). Using a finite-element analysis, mechanical stresses and strains on the membrane during assembly and PEMWE cell operation are quantified. For this purpose, a suitable material model was implemented and parameterized based on experimental data. The results of the cell simulation demonstrate that no critical states arise with a gap size of 0.15 mm, even under differential pressure up to 10 bar. However, increasing the gap sizes to over 0.3 mm can lead to membrane buckling, resulting in membrane thinning, possibly followed by membrane failure. [1]Secondly, the potential of reinforcing the membrane with a subgasket layer outside the active area is explored. Subgaskets can be used as a reinforcing layer for the membrane and are usually glued to the membrane. This study shows that subgasket layers can stabilize the membrane at the gap interface, even under differential pressure. However, this study highlights the need for careful positioning and thickness considerations of the subgasket for optimal mechanical stabilization. Furthermore, it was found that a subgasket can prevent membrane buckling, which can occur at increased gap sizes between cell frame and PTL. [2]Lastly, the use of woven web layers within the membrane structure is assessed as a reinforcement strategy to avoid membrane defects. Our findings suggest that no failure is expected during normal operation with applied woven web reinforcement, including varied temperatures and differential pressure, unless the gap size at the edge of the electrochemically active cell area exceeds 0.1 mm. [3] In conclusion, the research indicates that the choice of gap size in cell designs is crucial for preventing mechanical failures in PEMWE membranes. Additionally, the application of a reinforcement, such as a subgasket layer or woven web, can significantly enhance membrane stability, particularly at the gap interface. However, the thickness and the positioning of the subgasket must be carefully considered for optimal results. J. Kink, M. Ise, B. Bensmann and R. Hanke-Rauschenbach, J. Electrochem. Soc.(170), 54507 (2023). J. Kink, M. Suermann, M. Ise, Boris Bensmann, P. Junker and R. Hanke-Rauschenbach, Int. J. Hydrogen Energy (2024 (submitted)). J. Kink, M. Ise, B. Bensmann, P. Junker and R. Hanke-Rauschenbach, J. Electrochem. Soc.(170), 114513 (2023). Figure 1

Non‐selective Defect Minimization towards Highly Efficient Metal‐Organic Framework Membranes for Gas Separation

AbstractThe persistence of defects in polycrystalline membranes poses a substantial obstacle to reaching the theoretical molecular sieving separation and scaling up production. The low membrane selectivity in most reported literature is largely due to the unavoidable non‐selective defects during synthesis, leading to a mismatch between the well‐defined pore structure of polycrystalline molecular sieve materials. This paper presents a novel approach for minimizing non‐selective defects in metal–organic framework (MOF) membranes by a constricted crystal growth strategy in a confined environment. The in situ ZIF formation using the densely packed seeding array between the substrate and the pre‐grown top ZIF layer yields a confined membrane interlayer, which is highly uniform with a tightly packed crystalline structure. Unlike uncontrolled crystal growth, we purposely regulate the interlayer membrane growth in the direction parallel to the substrate. A notable 99 % decrease in defects in the confined interlayer was achieved compared to the random‐grown top layer, leading to a ~353 % increment in H2/N2 selectivity over the non‐confined reference MOF membrane. The performance of this new membrane sits in the optimal range above the Robeson upper bound. The membrane boasts a balanced high H2 permeability (>5000 Barrer) and selectivity (>50), significantly surpassing peer ZIF membranes.

Non-selective Defect Minimization towards Highly Efficient Metal-Organic Framework Membranes for Gas Separation.

The persistence of defects in polycrystalline membranes poses a substantial obstacle to reaching the theoretical molecular sieving separation and scaling up production. The low membrane selectivity in most reported literature is largely due to the unavoidable non-selective defects during synthesis, leading to a mismatch between the well-defined pore structure of polycrystalline molecular sieve materials. This paper presents a novel approach for minimizing non-selective defects in metal-organic framework (MOF) membranes by a constricted crystal growth strategy in a confined environment. The in situ ZIF formation using the densely packed seeding array between the substrate and the pre-grown top ZIF layer yields a confined membrane interlayer, which is highly uniform with a tightly packed crystalline structure. Unlike uncontrolled crystal growth, we purposely regulate the interlayer membrane growth in the direction parallel to the substrate. A notable 99 % decrease in defects in the confined interlayer was achieved compared to the random-grown top layer, leading to a ~353 % increment in H2/N2 selectivity over the non-confined reference MOF membrane. The performance of this new membrane sits in the optimal range above the Robeson upper bound. The membrane boasts a balanced high H2 permeability (>5000 Barrer) and selectivity (>50), significantly surpassing peer ZIF membranes.

BN SO46 - PANDORA's BOX- When anatomy trumps the pathology

Abstract Background Obturator hernias are usually attributed to elderly females presenting with small bowel obstruction. We present a case of an elderly gentleman with severe Kyphoscoliosis presenting with small bowel obstruction. His past medical history included Ischaemic Heart Disease with stents in the coronary arteries and on dual antiplatelets. His Kyphoscoliosis precluded him from being able to lie flat on his back. The spinal deformity as revealed in the CT scans proved challenging to position him dsafely for surgery. The lack of access between costal margins and the pelvis meant that surgical access with Laparoscopy was going to be impossible. Method After initial resuscitation, he underwent CT scan of his Chest, abdomen and pelvis which revealed an obstructed Obturator Hernia on the left side with small bowel obstruction. The CT was also concerning for the Anaesthetists due to the challenge posed by the severe Kyphoscoliosis. After fibreoptic intubation, abdomen was accessed through a transverse muscle cutting incision, at the level of the umbilicus. The Obturator membrane was approached from above and the hernia was reduced. The obstructed small bowel was viable and the defect in the obturator membrane was closed with No1 Ethibond sutures. The abdomen was closed with mass closure. Results Patient had a smooth post operative period and was discharged home after 2 weeks. Obturator hernias are notorious for their occult presentation. Unless the patient is scanned with CT imaging, it is impossible to make the diagnosis although clinical signs like Howship- Romberg sign may be present with pain on internal rotation of the hip, as a result of irritation of the Obturator nerve. Obturator Neuralgia may be elicited with positive Hannington- Kiff sign, which is an absence of absent adductor reflux in the thigh. Conclusion Obturator hernias are typically seen in skinny old females. When presenting with small bowel obstruction, Obturator herniae are challenging both in terms of diagnosis as well as in management. In our case, the challenging anatomy posed greater risk to safe airway control. From surgical view, laparoscopy as a less invasive option was ruled out because of the restricted access. When anatomy is challenging, the Surgeon will be forced to think outside the box and consider access to the abdomen through incisions which are not routinely used. The preoperative imaging shows the challenge posed by the extreme spinal deformity.

Atrial septal defect (ASD), trans-catheter closure – case report

Atrial septal defect (ASD) is one of the most common types of congenital heart defects, occurring in about 25% of children. An atrial septal defect occurs when there is a failure to close the communication between the right and left atria. It encompasses defects involving both the true septal membrane and other defects that allow for communication between both atria. There are five types of atrial septal defects ranging from most frequent to least: patent foramen ovale, ostium secundum defect, ostium primum defect, sinus venosus defect, and coronary sinus defect. Small atrial septal defects usually spontaneously close in childhood. Large defects that do not close spontaneously may require percutaneous or surgical intervention to prevent further complications such as stroke, dysrhythmias, and pulmonary hypertension. This activity describes the evaluation, diagnosis, and management of atrial septal defect and highlights the role of team-based interprofessional care for affected patients. Atrial septal defects are frequently asymptomatic. The characteristic murmur is a soft, systolic ejection murmur over the pulmonic area (second intercostal space) combined with a wide, fixed splitting of S2. Many ASDs go undiagnosed until adulthood; therefore, treatment, especially of large defects, is often delayed. Untreated large defects can cause exercise intolerance, cardiac dysrhythmias, palpitations, increased incidence of pneumonia, pulmonary hypertension and increased mortality.

Whole Blood Transcriptome Analysis in Congenital Anemia Patients.

Congenital anemias include a broad range of disorders marked by inherent abnormalities in red blood cells. These abnormalities include enzymatic, membrane, and congenital defects in erythropoiesis, as well as hemoglobinopathies such as sickle cell disease and thalassemia. These conditions range in presentation from asymptomatic cases to those requiring frequent blood transfusions, exhibiting phenotypic heterogeneity and different degrees of severity. Despite understanding their different etiologies, all of them have a common pathophysiological origin with congenital defects of erythropoiesis. We can find different types, from congenital sideroblastic anemia (CSA), which is a bone marrow failure anemia, to hemoglobinopathies as sickle cell disease and thalassemia, with a higher prevalence and clinical impact. Recent efforts have focused on understanding erythropoiesis dysfunction in these anemias but, so far, deep gene sequencing analysis comparing all of them has not been performed. Our study used Quant 3' mRNA-Sequencing to compare transcriptomic profiles of four sickle cell disease patients, ten thalassemia patients, and one rare case of SLC25A38 CSA. Our results showed clear differentiated gene map expressions in all of them with respect to healthy controls. Our study reveals that genes related to metabolic processes, membrane genes, and erythropoiesis are upregulated with respect to healthy controls in all pathologies studied except in the SLC25A38 CSA patient, who shows a unique gene expression pattern compared to the rest of the congenital anemias studied. Our analysis is the first that compares gene expression patterns across different congenital anemias to provide a broad spectrum of genes that could have clinical relevance in these pathologies.

Impact of membrane surface and module damage on virus removal and integrity in RO membranes

RO membrane modules are very effective in removing viruses and salts, but concerns remain regarding their long-term integrity in full-scale RO spiral wound systems. Membrane defects can arise from delamination, chlorine, or abrasive particle exposure, and module defects can arise from permeate tube, O-ring, and glue line damage. These issues compromise the membrane and module's performance, allowing viruses to pass that are not detected by conductivity monitoring. This paper assesses the impact of damage on virus removal using biological indicators (natural virus markers (NV)) and non-biological surrogates (salt, sulfate, rhodamine WT, pyranine). Three categories of module damage were studied and characterized using different autopsy techniques: membrane module component damage (permeate tube damage, O-ring damage, and membrane delamination), oxidative membrane damage (by hypochlorite exposure dose), and membrane surface damage (by abrasive particle exposure). Module component damage resulted in increased water permeability and decreased natural virus rejection. The conductivity remained similar to that of an intact module except in the case of permeate tube damage. Chlorine exposure (9000 ppm.h) didn't result in detectable NV markers in the permeate, indicating an intact support layer despite active layer damage. Abrasive particle exposure by suspended silicon carbide in the feed resulted in scratches, observed by SEM images, and a decline in the rejection of fluorescent marker, which indicates membrane surface damage. Results demonstrate that NV markers most consistently determine virus removal capacity in modules compromised by component damage. However, for assessing active layer damage, solutes like rhodamine-WT and pyranine prove more effective. This underscores the necessity of employing multiple indicators for a comprehensive evaluation of membrane integrity.

The Onerous task of managing paroxysmal nocturnal hemoglobinuria in a Low resource setting: a case report. A hematologist’s experience

Introduction: Paroxysmal nocturnal hemoglobinuria (PNH) is a form of red cell membrane defect characterized by increased sensitivity to complement-mediated cell lysis, resulting in intravascular hemolytic anemia, passage of hemoglobin-containing urine, a high risk of venous thrombosis and progression to pancytopenia.The diagnosis of PNH is based on the flow cytometric (FCM) detection of peripheral blood cell clones. Such clones lack expression of the surface molecules linked to the glycosylphosphatidylinositol (GPI) anchors. The underlying defect is a somatic mutation of the short arm of the phosphatidylinositol glycan class A gene (PIG-A). Case report: We report a case of a 34-year-old male, with recurrent hemolytic anemia and dural venous sinus thrombosis found to have PNH by flow cytometry. He is currently on anticoagulation, iron and folate supplements, intermittent steroids for hemolytic episodes as we await complement inhibitors. Conclusion: As part of the diagnostic workup for patients presenting with recurrent hemolytic anemia and thrombosis in unusual sites, clinicians should include PNH on the list of differential diagnoses. Effort should be taken to characterize the red urine reported on the urine dipstick as blood/hemoglobin by microscopy to differentiate hematuria and hemoglobinuria and order for flow cytometry as this has implications on patient management. Keywords: Thrombosis; hemolysis; complement; paroxysmal nocturia; hemoglobinuria.

Neo Angio-Osteo-Chonrogenesis Using Autologous Matrix induced Chondrogenesis (AMIC) Membrane in the Treatment of Freiberg`s Disease of Lesser Metatarsals –A Five Year Folow Up of 10 Cases

Category: Lesser Toes; Other Introduction/Purpose: Freiberg’s infraction is osteonecrosis of lesser metatarsal heads most commonly affecting adolescent females. They usually present with pain and swelling of the forefoot. MRI is useful investigation in the early diagnosis. It is a self-limiting disease and the main stay of treatment is non operative. Surgery is indicated in failed conservative management which include open debridement, cheilectomy, micro fracture, and osteotomy and excision arthroplasty. The aim of the study is to describe a new technique for treatment of Freiberg`s disease of lesser metatarsals and document the one and five-year functional outcomes. Methods: A retrospective analysis of ten patients who had Freiberg`s infraction of the lesser toe metatarsals treated with open debridement, microfracture, bone grafting and application of AMIC membrane was carried out. The patients were followed up to five years and the outcome measures were scored using The Manchester-Oxford Foot Questionnaire (MOxFQ) and Visual Analogue Pain Score (VAS), Figure 1. Results: The mean age was 42.7 years and follow-up time was 36.4 months. The most common site was second metatarsal, eight (80%) followed by third metatarsal, two (20%). The mean base line MOxFQ was 72.5 (95% CI- 45±100) which improved to 42.5 (95%CI- 2.5±82.5) at one year. The mean baseline VAS improved from 47.3(95%CI- 14.3±80.3) to 30.3 (95%CI- 2.1±58.5) at one year. The mean MOxFQ and VAS at five years was 7 (95%CI-0.8±13.2) and 3.6(95%CI-1.3±6.2) respectively. Conclusion: Open debridement of the Freiberg`s disease combined with microfracture of the defect, bone grafting and application of AMIC membrane gives good functional outcomes.

Preparation of Pebax based ternary mixed matrix membranes for enhancing CO2 transport and separation

As a type of material for membrane separation in carbon capture technology, mixed matrix membranes (MMMs) have the advantages of simple processing and excellent gas separation performance and have great research prospects. However, the affinity between organic matrix and inorganic fillers is usually poor, and microphase separation occurs at the interface. At the same time, as the filler content increases, the filler particles will aggregate, leading to non-selective defects in the homogeneous membrane and reducing the gas separation performance of MMMs. Herein, the strategy of adding a third component was adopted. Small molecule polyethylene glycol dimethyl ether (PEGDME) was introduced into the Pebax/NH2-MIL-101 membrane to prepare a ternary mixed matrix membrane Pebax/PEGDME/NH2-MIL-101. Adding small molecules as the third component optimized the membrane structure by utilizing the interaction between the third component, inorganic fillers, and polymer matrix, effectively improving the physical microenvironment of gas separation. At the same time, NH2-MIL-101 was modified to PEI-MIL-101, further improving the performance of the mixed matrix membrane. The CO2 permeability of the Pebax/PEGDME/NH2-MIL-101 ternary mixed matrix membrane reached 313 Barrer, and the CO2/N2 selectivity reached 47.7. The CO2 permeability coefficient of Pebax/PEGDME/PEI-MIL-101 membrane reached 286 Barrer, and the CO2/N2 selectivity coefficient reached 54.2. This work provides new ideas for optimizing the gas separation performance of mixed matrix membranes.

EN FACE OPTICAL COHERENCE TOMOGRAPHY MORPHOLOGY OF MACULAR PUCKER CORRELATES WITH METAMORPHOPSIA: Possible Role of the Henle Fiber Layer.

To describe macular pucker contraction patterns with en face optical coherence tomography (OCT), to provide a correlation with metamorphopsia scores, and to discuss the protective role of the Henle fiber layer (HFL) against tangential traction. Retrospective, institutional, observational, and consecutive case series. Clinical charts, M-charts scores, and structural and en face OCT imaging of patients diagnosed with macular pucker were reviewed. A 120 eyes of 114 consecutive patients diagnosed with macular pucker were included. En face OCT patterns of macular pucker contraction were foveal in 51 of 120 eyes (42.5%) and extrafoveal in 69 of 120 eyes (57.5%). Foveal macular puckers had regular, a concentric, circle morphology in the HFL (46/51 eyes, 90.2%), whereas extrafoveal membranes had irregular, distorted, circular HFL morphology (62/69 eyes, 89.8%; P < 0.001). Foveal contraction morphology and regular HFL pattern, as well as extrafoveal contraction morphology and an irregular HFL pattern, highly correlated one with another (P < 0.001 in both cases). Foveal macular puckers with regular HFL patterns had significantly less vertical and horizontal M-charts scores as compared with extrafoveal membranes with irregular HFL (P < 0.001 in both cases). Ellipsoid zone and external limiting membrane defects were rare in the parafoveal region (5/120 eyes, 4.2%). Visual acuity did not correlate with metamorphopsia scores (P = 0.903). En face OCT imaging identifies macular pucker contraction patterns that correlate with metamorphopsia scores and that can be used alongside the current structural OCT staging system to guide clinicians in the surgical decision-making process.

Clinical and genetic diagnosis of two Turkish patients with hereditary spherocytosis

Hereditary spherocytosis is a congenital disorder caused by defects in the erythrocyte membrane. It is characterized by hemolytic anemia, jaundice, splenomegaly, and cholelithiasis. The clinical presentation is variable. Especially in the neonatal period and cases without a family history, it isn't easy to diagnose with classical approaches. Here, we describe the genetic findings of a 1.5-month-old and a 2-month-old girl diagnosed with hereditary spherocytosis in Turkish families. Both cases presented with severe anemia and jaundice. Spherocytes were frequently seen in peripheral blood smears. Targeted next-generation sequencing (NGS) revealed that the 1.5-month-old girl was heterozygous for a novel frameshift mutation c.1617del (p.Leu540CysfsTer31) in exon 15 of the ANK1 gene, while the 2-month-old girl was heterozygous for a mutation c.1912C&amp;gt;T (p.Arg638Ter) in exon 13 of the SPTB gene, which leads to abnormal protein truncation. Parents did not carry these mutations. To our knowledge, the ANK1 mutation identified in a 7-month-old girl has not been reported previously. NGS may be helpful in diagnosing hereditary spherocytosis, especially in atypical cases.

Potential of diagnostic electron microscopy of calcification, pathological neovascularization and elastolysis in combination with phenotyping of cell populations in large arteries

Aim. To determine the potential of diagnostic electron microscopy of intraplaque processes (severity of lipid damage, fibrous cap thickness and condition, severity of pathological neovascularization, presence, nature and severity of calcification, ratio and distribution of various cell populations).Material and methods. The study objects were plaques removed during endar­terectomy from the human carotid artery and segments of the human internal mammary artery removed during coronary bypass surgery. Whole specimens were subjected to chemical fixation, staining with heavy metal salts, embedding in epoxy resin followed by layer-by-layer grinding, polishing, contrasting, visualization using back-scattered electron scanning electron microscopy and three-dimensional reconstruction with color mapping (modified EM-BSEM).Results. The use of a modified EM-BSEM made it possible to: 1) visualize the fibrous cap thickness and assess the extracellular matrix; 2) analyze the neointimal lipid distribution; 3) perform three-dimensional reconstruction and analyze the microenvironment of calcifications of various sizes; 4) visualize endothelial cells, defects in interendothelial contacts and the basement membrane of neointimal capillaries with their subsequent three-dimensional reconstruction; 5) perform an analysis of age-dependent defects in the basement membrane and internal elastic membrane of the internal mammary artery. The resolution of the obtained images was significantly superior to intravascular imaging methods (intravascular ultrasound and optical coherence tomography), allowing additional assessment of capillary fluidity, the degree of calcification encapsulation and the condition of elastic fibers. Three-dimensional reconstruction of calcifications, neointimal capillaries and elastic fibers made it possible to assess their spatial density and heterogeneity. Simultaneously with the identification and assessment of these histological structures, objective phenotyping of cell populations was performed, which made it possible to isolate macrophages and foam cells, vascular smooth muscle cells, fibroblasts and endothelial cells in atherosclerotic plaques and automatically identify them through color mapping determined by their electronic contrast distribution signatures.Conclusion. The modified EM-BSEM method allows for universal electron microscopic diagnosis of atherosclerotic and elastolytic lesions of large arteries with high information content about vascular remodeling and high accuracy. Electronic contrast distribution signatures unique for each cell population indicate the possibility of their automated phenotyping using specialized neural network algorithms.

Homogeneously assembled covalent organic framework membrane co-stitched by β-cyclodextrin and chitosan for dye separation

Covalent organic frameworks (COFs) based membranes have demonstrated great potential in molecular separation. However, COFs are usually synthesized as powders, and difficult to form large-area and highly crystalline membranes. There normally exists unfavorable crystal flaws and stacking defects in membranes, impairing their rejection performance. The severe reaction conditions of solvothermal synthesis also inhibit their fabrication. Here, a comprehensive strategy was developed to fabricate a homogeneously assembled COF membrane co-stitched by β-cyclodextrin (β-CD) and chitosan (CS). Specifically, the COF crystallites (named TATP) were homogeneously formed and assembled to be films at room temperature under the control of n-propylamine; The aminated CS chemically bonded the TATP crystallites on the substrate and helped assemble them to form dense films. β-CD molecules were subsequently embedded into the TATP layer and crosslinked to further stitch membrane defects. The prepared CD-TATP-NH2CS/nylon membrane demonstrated enhanced excellent rejection performance. It could reject 100 % of R250 (BB), Congo red, Direct blue15, and 99.4 % of Alcian blue. It also could selectively separate Methyl orange (MO) and BB mixed solutions with only MO passing through, owing to the co-stitching of the membrane defects by β-CD and CS. This study provides a significant concept and strategy for fabricating high-performance COF membranes.