Lung Membranes Research Articles

Ag nanoparticle interaction with complex lipidbilayer: an atomistic and coarse-grained study

Understanding nanoparticle (NP) translocation through complex cellular membranes is required for pre-evaluating their toxicity. Silver (Ag) is a common material, extensively applied in NP form for its apparent anti-bacterial properties. While so widely available, data about their interaction with lipid membranes, particularly the role of size and surface functionalization in membrane binding, is relatively scarce. As a first step, we performed all-atom biased and unbiased molecular dynamic simulations for bare Ag NPs for three sizes (1/3/5 nm diameter) with a complex membrane of DPPC:DOPC:POPC:Chol in 5:2:2:1 representing model lung membrane.

Anticoagulant Biomimetic Consecutive Gas Exchange Network for Advanced Artificial Lung Membrane

Anticoagulant Biomimetic Consecutive Gas Exchange Network for Advanced Artificial Lung Membrane

Investigating the Efficacy of Zingerone on Mesothelioma and the Role of TRPV1 in This Effect

Mesothelioma is a highly lethal cancer developing in the lung, heart, and abdominal membranes. Zingerone, a capsaicin-like bioactive compound, has been shown to have anticancer properties. Transient Receptor Potential Vanilloid 1 (TRPV1) is an ion channel involving in the cytotoxicity of capsaicin. In the present study, we aimed at determining the cytotoxicity of zingerone on a mesothelioma cell line and to evaluate the role of TRPV1 in this effect. For this purpose, H2452 was used as the mesothelioma cell line and MTS was performed to calculate zingerone cytotoxicity. Moreover, TRPV1 was inhibited by capsazepeine while TRPV1 production was reduced through shRNA treatment. Besides, wound healing and clonogenic assays were performed to measure the migration and colony forming abilities, respectively. As a result, IC50 value of zingerone was calculated as 11.49 mM. Capsazepine treatment or lowered TRPV1 gene expression did not appear to affect zingerone cytotoxicity (p > 0.05) even though the migration rate and colony forming abilities of the zingerone treated cells decreased significantly compared to the control (p < 0.05). Therefore, we concluded that zingerone was less cytotoxic to H2452 cells than the most cancer types and TRPV1 did not seem to have a role in its cytotoxicity.

Clinical Analysis of 15 Cases of Non-Hodgkin Lymphoma Complicated with Pneumocystis carinii Pneumonia Treated with R-CHOP Regimen

Objective: To investigate the clinical features of R-CHOP regimen in the treatment of non-Hodgkin’s lymphoma with Pneumocystis carinii pneumonia (PCP) in order to improve the understanding of PCP and the side effects of Rituxan. Methods: A retrospective analysis of 90 patients with non-Hodgkin’s lymphoma treated with R-CHOP chemotherapy in our hospital from November 2015 to November 2020, of which 15 (16.7%) patients, combined with PCP clinical data, including clinical symptoms, physical signs, chest imaging examination and treatment data were used for to analysis and summarization. Results: The clinical features of R-CHOP chemotherapy combined with PCP were fever, cough, and sputum. Some patients had fewer clinical symptoms. Common imaging manifestations were double lung membrane glass shadow, patchy shadow, and flocculent shadow. It can occur in all clinical stages, and the incidence of late stage is high, and there is no clear correlation with bone marrow suppression. Pneumocystis was found in 2 cases of sputum, and the rest of the patients were clinically diagnosed. The main therapeutic drugs are sulfamethoxazole (8/15), compound sulfamethoxazole (6/15), clindamycin (1/15, sulfa drug allergy), and adrenal cortex hormones (4/15). Fourteen cases were cured and 1 case died. Conclusion: The incidence of R-CHOP in advanced non-Hodgkin’s lymphoma of PCP is high. Patients with clinical use of R-CHOP chemotherapy will encounter fever, cough, chest computed tomography (CT) film glass shadow, and diffuse patch shadow. Patients should be alert to the possibility of PCP and take sulfonamides as soon as possible for medical treatment.

Abstract 1840: Isolation and evaluation of human nanobodies against hypoxanthine guanine phosphoribosyltransferase (HPRT) and their potential use for the detection and targeting of lung, breast and colon cancer cells

Abstract Since the clinical relevance of hypoxanthine guanine phosphoribosyltransferase (HPRT) as both a cancer biomarker and a potential tumor target is increasing, we isolated human nanobodies (Nbs) against HPRT and tested their potential to detect and target cytosolic and membrane associated HPRT in lung, breast and colon cancer cells. HPRT is a purine salvage pathway enzyme that catalyzes the conversion of hypoxanthine to inosine monophosphate and guanine to guanosine monophosphate. Until recently, HPRT was considered as a housekeeping gene and its clinical relevance was mainly limited to congenital central nervous disorders such as Lesch-Nyhan disease. However, recent gene expression analysis across all cancers in The Cancer Genome Atlas (TCGA) database and analysis of HPRT expression within cancer patients' tissues has revealed that the expression of HPRT is elevated in the majority of malignant tissues in comparison to normal tissues. Moreover, multiple studies have recently shown that HPRT may be associated with the cell membrane in lung, colon cancer and lymphoma cells, and not in normal cells. Thus, HPRT is a potential immunotherapeutic target for cancer. Using phage display technology we isolated 384 nanobody clones from the Christ human single domain antibody (dAb) library against human HPRT. Ten of the most sensitive Nbs were sequenced and evaluated to determine their sensitivity using dose response curves. Four parameter logistic regression analysis of the top 10 HPRT nanobodies showed R squared values ranging from 0.9388-0.9989 and a sigmoidal shape denoting a concentration-dependent antigen-ligand relationship. The anti-HPRT Nbs were able to detect minimum HPRT amounts ranging from 10-20 ng/ml. Validation of the anti-HPRT Nbs was conducted with a siRNA HPRT knockdown in A549 cells. A549 siRNA HPRT knockdown cell lysate showed at least a 5-fold reduction in the overall signal in phage ELISA compared to A549 wild type cell lysate (p&amp;lt;0.001) indicating the specificity of the Nbs to HPRT. In addition, flow cytometry analysis showed that the anti-HPRT Nbs were able to detect membrane associated HPRT on A549 (20%), NCI-H460 (23%), HT-29 (41%) , SW620 (46%) and MDA-MB-231 (32%) cancer cell lines. Anti-HPRT Nbs did not show significant binding to normal mononuclear cells compared to cancer cells (p&amp;lt;0.002). Anti-HPRT Nbs were successfully expressed and purified using the pET-scFv expression system. Human anti-HPRT Nbs may be used for the detection of both cytosolic and membrane associate HPRT. Future directions of this research will explore the uses of anti-HPRT-Nb-based therapies and their use in other applications such as chimeric antigen receptors (CARs) for cell adoptive therapies. Citation Format: Edwin J. Velazquez, Tyler B. Humpherys, Toni O. Mortimer, David M. Bellini, Kathryn R. Smith, Rachel M. Morris, Abigail Goodman, Kim L. O'Neill. Isolation and evaluation of human nanobodies against hypoxanthine guanine phosphoribosyltransferase (HPRT) and their potential use for the detection and targeting of lung, breast and colon cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1840.

Extracorporeal Membrane Oxygenation in Pregnancy and the Postpartum Period: A Systematic Review of Case Reports

(Int J Obstet Anesthesia. 2020;43:106–113) Extracorporeal membrane oxygenation (ECMO) is a modified form of cardiopulmonary bypass used in intensive care units (ICU) in which venous blood is removed, pumped through an artificial oxygenating lung membrane and returned to the patient. Data on the use of ECMO in pregnant or postpartum patients is quite limited. This study explored the use of ECMO in pregnant and postpartum patients by reviewing published case studies and analyzing maternal and neonatal outcomes.

The Roles of Membrane Technology in Artificial Organs: Current Challenges and Perspectives.

The recent outbreak of the COVID-19 pandemic in 2020 reasserted the necessity of artificial lung membrane technology to treat patients with acute lung failure. In addition, the aging world population inevitably leads to higher demand for better artificial organ (AO) devices. Membrane technology is the central component in many of the AO devices including lung, kidney, liver and pancreas. Although AO technology has improved significantly in the past few decades, the quality of life of organ failure patients is still poor and the technology must be improved further. Most of the current AO literature focuses on the treatment and the clinical use of AO, while the research on the membrane development aspect of AO is relatively scarce. One of the speculated reasons is the wide interdisciplinary spectrum of AO technology, ranging from biotechnology to polymer chemistry and process engineering. In this review, in order to facilitate the membrane aspects of the AO research, the roles of membrane technology in the AO devices, along with the current challenges, are summarized. This review shows that there is a clear need for better membranes in terms of biocompatibility, permselectivity, module design, and process configuration.

The role of size and nature in nanoparticle binding to a model lung membrane: an atomistic study.

Understanding the uptake of nanoparticles (NPs) by different types of cellular membranes plays a pivotal role in the design of NPs for medical applications and in avoiding adverse effects that result in nanotoxicity. Yet, the role of key design parameters, such as the bare NP material, NP size and surface reactivity, and the nature of NP coatings, in membrane remodelling and uptake mechanisms is still very poorly understood, particularly towards the lower range of NP dimensions that are beyond the experimental imaging resolution. The same can be said about the role of a particular membrane composition. Here, we systematically employ biased and unbiased molecular dynamics simulations to calculate the binding energy for three bare materials (Ag/SiO2/TiO2) and three NP sizes (1/3/5 nm diameter) with a representative lung surfactant membrane, and to study their binding kinetics. The calculated binding energies show that irrespective of size, Ag nanoparticles bind very strongly to the bilayer, while the NPs made of SiO2 or TiO2 experience very low to no binding. The unbiased simulations provide insight into how the NPs and membrane affect each other in terms of the solvent-accessible surface area (SASA) of the NPs and the defect types and fluidity of the membrane. Using these systematic fine-grained results in coarsening procedures will pave the way for simulations considering NP sizes that are well beyond the membrane thickness, i.e. closer to experimental dimensions, for which different binding characteristics and more significant membrane remodelling are expected.

Development of Porous and Flexible PTMC Membranes for In Vitro Organ Models Fabricated by Evaporation-Induced Phase Separation.

Polymeric membranes are widely applied in biomedical applications, including in vitro organ models. In such models, they are mostly used as supports on which cells are cultured to create functional tissue units of the desired organ. To this end, the membrane properties, e.g., morphology and porosity, should match the tissue properties. Organ models of dynamic (barrier) tissues, e.g., lung, require flexible, elastic and porous membranes. Thus, membranes based on poly (dimethyl siloxane) (PDMS) are often applied, which are flexible and elastic. However, PDMS has low cell adhesive properties and displays small molecule ad- and absorption. Furthermore, the introduction of porosity in these membranes requires elaborate methods. In this work, we aim to develop porous membranes for organ models based on poly(trimethylene carbonate) (PTMC): a flexible polymer with good cell adhesive properties which has been used for tissue engineering scaffolds, but not in in vitro organ models. For developing these membranes, we applied evaporation-induced phase separation (EIPS), a new method in this field based on solvent evaporation initiating phase separation, followed by membrane photo-crosslinking. We optimised various processing variables for obtaining form-stable PTMC membranes with average pore sizes between 5 to 8 µm and water permeance in the microfiltration range (17,000–41,000 L/m2/h/bar). Importantly, the membranes are flexible and are suitable for implementation in in vitro organ models.

Blood Oxygenation Using Fluoropolymer-Based Artificial Lung Membranes.

Artificial lung (AL) membranes are used for blood oxygenation for patients undergoing open-heart surgery or acute lung failures. Current AL technology employs polypropylene and polymethylpentene membranes. Although effective, these membranes suffer from low biocompatibility, leading to undesired blood coagulation and hemolysis over a long term. In this work, we propose a new generation of AL membranes based on amphiphobic fluoropolymers. We employed poly(vinylidene-co-hexafluoropropylene), or PVDF-co-HFP, to fabricate macrovoid-free membranes with an optimal pore size range of 30-50 nm. The phase inversion behavior of PVDF-co-HFP was investigated in detail for structural optimization. To improve the wetting stability of the membranes, the fabricated membranes were coated using Hyflon AD60X, a type of fluoropolymer with an extremely low surface energy. Hyflon-coated materials displayed very low protein adsorption and a high contact angle for both water and blood. In the hydrophobic spectrum, the data showed an inverse relationship between the surface free energy and protein adsorption, suggesting an appropriate direction with respect to biocompatibility for AL research. The blood oxygenation performance was assessed using animal sheep blood, and the fabricated fluoropolymer membranes showed competitive performance to that of commercial polyolefin membranes without any detectable hemolysis. The data also confirmed that the bottleneck in the blood oxygenation performance was not the membrane permeance but rather the rate of mass transfer in the blood phase, highlighting the importance of efficient module design.

Sialic acids expression in newborn rat lungs: implications for pulmonary developmental biology

Mammalian lung development proceeds during the postnatal period and continues throughout life. Intricate tubular systems of airways and vessels lined by epithelial cells are developed during this process. All cells, and particularly epithelial cells, carry an array of glycans on their surfaces. N-acetylneuraminic (Neu5Ac) and N-glycolylneuraminic (Neu5Gc) acids, two most frequently-occurring sialic acid residues, are essential determinants during development and in the homeostasis of cells and organisms. However, systematic data about the presence of cell surface sialic acids in the postnatal lung and their content is still scarce. In the present study, we addressed the histochemical localization of Neu5Ac > Neu5Gc in 0-day-old rat lungs. Furthermore, both residues were separated, identified and quantified in lung membranes isolated from 0-day-old rat lungs using high-performance liquid chromatography (HPLC) methodologies. Finally, we compared these results with those previously reported by us for adult rat lungs. The Neu5Ac > Neu5Gc residues were located on the surface of ciliated and non-ciliated cells and the median values for both residues in the purified lung membranes of newborn rats were 5.365 and 1.935 μg/mg prot., respectively. Comparing these results with those reported for the adults, it was possible to observe a significant difference between the levels of Neu5Ac and Neu5Gc (p < 0.001). A more substantial change was found for the case of Neu5Ac. The preponderance of Neu5Ac and its expressive increase during the postnatal development points towards a more prominent role of this residue. Bearing in mind that sialic acids are negatively charged molecules, the high content of Neu5Ac could contribute to the formation of an anion “shield” and have a role in pulmonary development and physiology.

Abstract 519: Exploring the potential of human nanobodies against thymidine kinase 1 for the targeting of lung cancer cells

Abstract Single domain antibodies or nanobodies (Nbs) have positively proved effective for the targeting of multiple tumor targets. This study describes the isolation of human Nbs against the tumor proliferation biomarker thymidine kinase 1 (TK1). The anti-TK1 Nbs were used to target membrane associated TK1 in the non-small cell lung carcinoma cell lines NCI-H460 and A549 cells. TK1 is a pyrimidine salvage enzyme that is upregulated in malignant tissues. Recently, we have reported the presence of a TK1 form that is associated to the cell membrane in breast, lung and colon tumors as well as leukemia. Our findings suggest that targeting of TK1 in proliferating cancer cells may be an alternative approach for the treatment of cancer. Using phage display technology, we isolated a total of 237 nanobodies from the Daniel Christ DAb library. After 2-4 rounds of selection the affinity of the nanobodies to TK1 was tested with monoclonal phage ELISA using human recombinant TK1. Ten of the most sensitive anti-TK1 Nbs were then selected and evaluated with dose response curves as possible candidates for preclinical testing. The dose response curves showed R squares values ranging from 0.9738-0.9980 fitting a sigmoidal curve. Thus, indicating a strong antibody dose response relationship specific for TK1. In addition, the specificity of the TK1 antibodies was tested by screening against unrelated proteins and cell lysate from an siRNA TK1 knockdown using monoclonal phage ELISA. Nanobodies showed negligible binding when screened against TK1 non related proteins. Validation of the anti-TK1 Nbs with TK1 siRNA knockdown showed a significant reduction on the Nbs binding compared to wild type. The sensitivity of the anti-TK1 Nbs to detect TK1 was within the nanomolar range (between 100-20 ng/ml) and had thermostable standing temperatures between 50-75 °C. The anti-TK1 Nbs were used to detect membrane associated TK1 in the non-small cell lung carcinoma cell lines NCI-H460 and A549. The phage nanobodies showed binding capacity to TK1 on cancer cells with 30- 60% of positive cells for NCI-H460 and 25 to 40% for A549 cells. Human Nbs represent a valuable resource for the detection and the targeting of TK1 in proliferating tumor cells. Further work is required to enable the exploration of the therapeutic uses of anti-TK1 Nb-based therapies and their incorporation to cell adoptive therapies such as chimeric antigen receptor (CAR) therapies. Citation Format: Edwin J. Velazquez, Jordan D. Cress, Kathryn R. Smith, David M. Bellini, Jonathan R. Skidmore, Zachary D. Ewell, Richard A. Robison, Kim L. O'Neill. Exploring the potential of human nanobodies against thymidine kinase 1 for the targeting of lung cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 519.

Nanosponges intercept coronavirus infection

Nanoparticles cloaked in human lung and immune cell membranes act as decoys to neutralize SARS-CoV-2 in cell culture, preventing host cell infection.

Relationship Between Lung Diffusion And Exercise Capacity In Heart Failure With Preserved Ejection Fraction

PURPOSE: Patients with heart failure with preserved ejection fraction (HFpEF) have impaired lung diffusion (DL) at rest and during exercise which may contribute to a reduced exercise capacity. However, it is unclear whether these impairments are solely due to alterations in pulmonary hemodynamics or related to other cardiopulmonary factors which may impair oxygen uptake such as the inability to recruit lung surface area. Therefore this study examined simultaneous measurements of DL for carbon monoxide (DLCO) and nitric oxide (DLNO), which allows for partitioning of DL into its alveolar-capillary membrane (Dm) and pulmonary capillary blood volume (Vc) components, to better understand the relationship between exertional changes in lung diffusion and exercise capacity. METHODS: HFpEF patients (N=17, age=62±9y, BMI=36±8kg/m2) undergoing exercise right heart catheterization performed simultaneous rebreathe DLCO/NO tests at rest and during each stage of incremental supine cycling exercise, and membrane conductance (Dm) and pulmonary capillary blood volume (Vc) were calculated. Breath-by-breath pulmonary gas exchange was recorded throughout rest and exercise. RESULTS: All patients were hemodynamically diagnosed with HFpEF (pulmonary capillary wedge pressure >15 at rest and/or >25 mmHg during exercise). Overall lung and alveolar-capillary membrane diffusion increased from rest to peak exercise (DLCO: 11.8±4.0 to 16.2±7.4 ml/min/mmHg, DLNO: 33.1±11.5 to 48.4±21.9 ml/min/mmHg, Dm: 18.9±7.2 to 28.3±13.1 ml/min/mmHg; p’s<0.01). The change in DL was related to exercise capacity (change in DLCO vs. peak VO2: R=0.69, p<0.01, change in DLNO vs. peak VO2: R=0.65, p<0.01) and this was primarily driven by changes in Dm (change in Dm vs. peak VO2: R=0.63, p<0.01) but not Vc (change in Vc vs. peak VO2: R=0.15, p=0.582). CONCLUSIONS: These data highlight that a limited increase in lung diffusion and alveolar-capillary membrane conductance during exercise are associated with a lower VO2 peak in HFpEF patients. In addition to hemodynamic constraints previously reported in HFpEF, an inability to recruit lung surface area during exercise may also contribute to the reduced exercise capacity in these patients.

Extravascular Lung Water And Lung Diffusing Capacity In Response To Ultra-endurance Exercise Performed At Moderate Altitude

PURPOSE: Strenuous exercise performed at altitude increases cardiac output and pulmonary arterial and capillary pressures to levels that may exceed a tolerable alveolar-capillary load, thereby evoking fluid leakage into the interstitial space. Accordingly, this study aimed to determine whether running an ultramarathon at moderate altitude increases extravascular lung water (EVLW) and whether this inhibits the transfer of gas across the alveolar-capillary membrane. METHODS: Cardiac biomarkers (cTnI & BNP), exhaled nitric oxide (ExNO), echocardiographic signs of EVLW, and lung (DLco) and alveolar-capillary membrane (Dm) diffusing capacity for carbon monoxide (determined via a single-breath DLco/DLno method) were assessed in 53 runners (10 Females; Age:41±10y BMI:23±2kg/m2) before, 1-4h and 24h after a 100km (CCC: 6,100m of ascent, altitude range of 1,035-2,584m) or 170km (UTMB: 10,000m of ascent, altitude range of 1,035-2,565m) mountain ultramarathon. RESULTS: Participants finished the ultramarathon in 27±12h with an average heart rate of 124±13bpm. Cardiac biomarkers were increased acutely after the race (cTnI: 0.01±0.00 vs. 0.04±0.01ng/ml, p<0.01; BNP: 21±2 vs. 123±12pg/ml, p<0.01), while ExNO decreased (25.6±2.0 vs. 14.5±1.3 ppb, p<0.01). Signs of EVLW increased after the race (average comet tails count: 2±1 vs. 7±1, p<0.01) while DLco decreased (31.6±1.0 vs. 28.6±0.9 ml/min/mmHg, p<0.01) but Dm remained unchanged (171.4±7.6 vs. 167.2±8.8 ml/min/mmHg, p>0.05). Cardiac biomarkers, ExNO, EVLW and Dm were similar to baseline values after 24h of recovery, while DLco remained mildly reduced (30.6±1.6 ml/min/mmHg, p<0.05). CONCLUSIONS: These data suggest a mild and transient increase in cardiac biomarkers and extravascular lung water occur after completing an ultramarathon at moderate altitude, but this has minimal impact on the transfer of gas across the alveolar-capillary membrane, despite an overall reduction in lung diffusion. In some subjects an exaggerated increase in extravascular lung water and decrease in alveolar-capillary membrane diffusion was observed, suggesting that some individuals may have an increased propensity for developing mild exercise-induced pulmonary edema at altitude.

Molecular dynamics exploring of atmosphere components interacting with lung surfactant phospholipid bilayers

Sulfur dioxide (SO2), nitrogen oxide (NO2) and ozone (O3) in the atmosphere are significantly correlated with various respiratory and cardiovascular diseases. High doses of each of these gases or a mixture can change the physical and chemical properties of the lung membrane, thus leading to an increased pulmonary vascular permeability and structural failure of the alveolar cell membrane. In the present study, detailed molecular dynamic (MD) modeling was applied to investigate the effects of SO2, NO2, O3 and mixtures of these gases on the dipalmitoyl phosphatidylcholine (DPPC) phospholipid bilayer. The results showed that several key physical properties, including the mass density, lipid ordering parameter, lipid diffusion, and electrostatic potential of the cell membrane, have been changed by the binding of different compounds. This resulted in significant variations and more disorder in the DPPC bilayer. The multiple analyses of membrane properties proved the toxicity of NO2, O3, and SO2 to the DPPC bilayer, providing a theoretical basis for the experimental phenomenon that SO2, NO2 and O3 can cause lung cell apoptosis. For the single systems, the damage to DPPC bilayer caused by O3 was more serious than NO2 and SO2. More importantly, the MD simulations using the mixtures of SO2, NO2, and O3 showed a much greater decline of membrane fluidity and the aggravation of membrane damage than the single systems, indicating a synergistic effect when NO2, SO2, and O3 coexisted in the atmosphere, which could lead to much more severe damage and greater toxicities to the lung.

P1111MULTI ORGAN SUPPORT WITH EXTRACORPOREAL CARBON DIOXIDE REMOVAL (ECCO2R) AND CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) WITH CITRATE ANTICOAGULATION IN THE CLINICAL SETTING OF DIFFICULT WEANING FROM MECHANICAL VENTILATION

Abstract Background and Aims Prolonged mechanical ventilation is associated with the risk of difficult weaning due to the onset of muscle weakness. A disproportion occurs between the respiratory workload and the muscular force, which leads to failure of the ventilatory pump and hypercapnia. Some early experiences suggest that ECCO2R facilitates weaning from the ventilator in patients with a high risk of failure. Method Clinical case: a 49 year-old man with a) recent orthotopic liver transplantation (cryptogenic cirrhosis), b) acute renal injury (AKI) on continuous veno-venous hemofiltration (CVVH) and c) acute respiratory distress syndrome (ARDS) requiring prolonged mechanical ventilation. After unsuccessful attempts at weaning from the ventilator, a lung membrane was inserted in series, before the hemofilter, on the CRRT circuit in order to remove CO2 and so reduce the workload of the respiratory muscles (Fig. 1). The patient was then extubated. We used citrate anticoagulation due to the presence of contraindications to systemic heparin (high bleeding risk, thrombocytopenia). Results ECCO2R + CRRT treatment requires a relatively high blood flow (300-350 ml / min) in order to extract a significant amount of CO2, but, the more the blood flow increases, the more citrate must be infused, and the more the metabolic load increases. The patient developed mild alkalosis as an initial sign of citrate accumulation (Table 1), but it was self-limiting. During ECCO2R we actually obtained the desired decrease in respiratory muscle effort (decrease in respiratory rate from 24 to 18 per minute and a maximum negative value of esophageal pressure from -8 to -4 cmH2O) and the treatment was interrupted after 36 hours. Mechanical ventilation was restored due to a complication independent of ECCO2R (massive pneumothorax). The patient tolerated the treatment for 36 hours. Conclusion ECCO2R proved an efficient and relatively simple technology helping respiratory function recovery. Due to the very frequent association of AKI and ARDS, leading to a high mortality rate, nephrological care in intensive care units should include this new treatment. Moreover, reduction of the inflammatory pathway secondary to mechanical ventilation could also benefit the evolution of AKI.

Presence of N-acetylneuraminic acid in the lung during postnatal development

Sialic acids, particularly N-acetylneuraminic acid (Neu5Ac), are present as terminal components of rich and complex oligosaccharide chains, which are termed glycans, and are exhibited on the cell surfaces, especially on epithelial cells. Crucial in the ‘social behavior’ of the cell, sialic acids play vital roles in many physiological and pathological phenomena. The aim of the present study was to separate, identify, and quantify Neu5Ac in purified lung membranes from 4-, 14-, and 21-day-old animals, followed by the statistical analysis of these results with our previously reported data (0-day-old and adult results). Complementary, ultrastructural methodologies were used. The differences in the Neu5Ac values obtained across the examined postnatal-lung development relevant ages studied were found to be statistically significant. A substantial increase in the mean level of this compound was found during the period of ‘bulk’ alveolarization, which takes place from postnatal day 4 to 14 (P4-P14). The comparison of the mean levels of Neu5Ac, during microvascular maturation (mainly between P12 and P21), reveals that the difference, although statistically significant, is the least significant difference among all the pair-wise differences between the developmental stages. The presence of sub-terminal N-acetylgalactosamine (GalNAc)/Galactose (Gal) residues with terminal sialic acids on the bronchioloalveolar cell surfaces was confirmed using lung ultra-thin sections of adult and 0-day-old animals. These results showed that, although Neu5Ac levels increase throughout postnatal lung development, this sialic acid was substantially added to epithelial cell surfaces during the “bulk” alveolarization period, while its presence was less important during the microvascular maturation period. Bearing in mind that sialic acids are negatively charged and create charge repulsions between adjacent cells, we hypothesized that they can substantially contribute to postnatal alveolar formation and maturation.

Silver nanoparticle uptake in the human lung assessed through in-vitro and in-silico methods

Silver nanoparticles (AgNP) are commonly used in medical, cosmetics, clothing, and industrial applications for their antibacterial and catalytic properties. As AgNP become more prevalent, the doses to which humans are exposed may increase and pose health risks, particularly through incidental inhalation. This exposure was evaluated through in-vitro methods simulating lung fluids and lung epithelium, and through computational fluid dynamics (CFD) methods of AgNP transport. A high-dose scenario simulated a short-term inhalation of 10 μg AgNP/m3, based on an exposure limit recommended by the National Institute of Occupational Safety and Health for the case of a health-care worker who handles AgNP-infused wound dressings, and regularly wears AgNP-imbedded clothing. Bioaccessibility tests were followed by a Parallel Artificial Membrane Permeability Assay (PAMPA) and supported by CFD models of the lung alveoli, membrane, pores, and blood capillaries. Results indicate that such exposure produces an average and maximum AgNP flux of approximately 4.7 × 10−21 and 6.5 × 10−19 mol m−2·s−1 through lung tissue, respectively, yielding a blood-silver accumulation of 0.46–64 mg per year, which may exceed the lowest adverse effect level of 25 mg for an adult male. Results from in-silico simulations were consistent with values estimated in vitro (within an order of magnitude), which suggest that CFD models may be used effectively to predict silver exposure from inhaled AgNP. Although the average short-term exposure concentrations are 3 orders of magnitude smaller than the reported threshold for mammalian cytotoxicity effects (observed at 5000 ppb), cumulative effects resulting from constant exposure to AgNP may pose risks to human health in the long-term, with predicted bioaccumulation reaching potential toxic effects after only five months of exposure, based on maximum flux.

A 2-year multicenter, observational, prospective, cohort study on extracorporeal CO2 removal in a large metropolis area

BackgroundExtracorporeal carbon dioxide removal (ECCO2R) is a promising technique for the management of acute respiratory failure, but with a limited level of evidence to support its use outside clinical trials and/or data collection initiatives. We report a collaborative initiative in a large metropolis.MethodsTo assess on a structural basis the rate of utilization as well as efficacy and safety parameters of 2 ECCO2R devices in 10 intensive care units (ICU) during a 2-year period.ResultsSeventy patients were recruited in 10 voluntary and specifically trained centers. The median utilization rate was 0.19 patient/month/center (min 0.04; max 1.20). ECCO2R was started under invasive mechanical ventilation (IMV) in 59 patients and non-invasive ventilation in 11 patients. The Hemolung Respiratory Assist System (Alung) was used in 53 patients and the iLA Activve iLA kit (Xenios Novalung) in 17 patients. Main indications were ultraprotective ventilation for ARDS patients (n = 24), shortening the duration of IMV in COPD patients (n = 21), preventing intubation in COPD patients (n = 9), and controlling hypercapnia and dynamic hyperinflation in mechanically ventilated patients with severe acute asthma (n = 6). A reduction in median VT was observed in ARDS patients from 5.9 to 4.1 ml/kg (p <0.001). A reduction in PaCO2 values was observed in AE-COPD patients from 67.5 to 51 mmHg (p< 0.001). Median duration of ECCO2R was 5 days (IQR 3–8). Reasons for ECCO2R discontinuation were improvement (n = 33), ECCO2R-related complications (n = 18), limitation of life-sustaining therapies or measures decision (n = 10), and death (n = 9). Main adverse events were hemolysis (n = 21), bleeding (n = 17), and lung membrane clotting (n = 11), with different profiles between the devices. Thirty-five deaths occurred during the ICU stay, 3 of which being ECCO2R-related.ConclusionsBased on a registry, we report a low rate of ECCO2R device utilization, mainly in severe COPD and ARDS patients. Physiological efficacy was confirmed in these two populations. We confirmed safety concerns such as hemolysis, bleeding, and thrombosis, with different profiles between the devices. Such results could help to design future studies aiming to enhance safety, to demonstrate a still-lacking strong clinical benefit of ECCO2R, and to guide the choice between different devices.Trial registrationClinicalTrials.gov: Identifier: NCT02965079 retrospectively registered https://clinicaltrials.gov/ct2/show/NCT02965079