Membrane Level Research Articles

Role of Water Molecules in Enabling Site Hopping and Vehicular Transport Mechanisms in Polynorbornene-Based Anion Exchange Membrane

Role of Water Molecules in Enabling Site Hopping and Vehicular Transport Mechanisms in Polynorbornene-based Anion Exchange Membrane Zhongyang Wang, ⸹ Ge Sun ， ⸹ Mrinmay Mandal, ‡, Paul A. Kohl, ‡, Juan de Pablo, ⸹ Shrayesh N. Patel, ⸹ and Paul F. Nealey ⸹ ‡ School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, 30332-0100, United States ⸹ Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA Ion exchange membranes are at the heart of electrochemical conversion and storage devices such as fuel cells 1, water electrolyzers 2, CO2 electrolyzers 3. redox flow batteries 4, and reverse electrodialysis 5. Anion exchange membrane fuel cells (AEMFCs) have attracted enormous attention as alternatives to replace perfluorinated, sulfonic acid-based proton exchange membrane fuel cells (PEMFCs) 6 because alkaline membrane electrode assemblies (MEAs) composed of anion exchange ionomers (AEIs) and AEMs that allow the use of Ni 7, 8, Fe 9, and Ag 10 based precious-group-metal (PGM) free catalysts in alkaline environments for hydrogen oxidation reactions (HORs) and oxygen reduction reactions (ORRs). However, the lack of understanding of ion transport mechanisms at different hydration levels of an anion exchange membrane hinders the rational design of the MEAs in an AEMFC. Here we investigate site hopping and vehicular transport mechanisms using anion exchange thin films, interdigitated electrodes, and atomistic molecular dynamics simulations. Halide ion (Br-, Cl- and I-) conductivities in polynorbornene-based thin films are measured as a function of temperature and relative humidity using electrochemical impedance spectroscopy. Halide ions show Arrhenius behaviors, and activation energy (Ea) is for the first time used as an indicator for detecting the transition of site hopping and vehicular transport mechanisms. Using atomistic molecular dynamics simulation, we quantitatively demonstrate that the transition of site hopping and vehicular mechanisms is aided by better solvation environments of anions and more percolated water pathways. References Z. Wang, J. Parrondo, C. He, S. Sankarasubramanian and V. Ramani, Nature Energy, 2019, 4, 281-289.S. Z. Oener, M. J. Foster and S. W. Boettcher, Science, 2020, 369, 1099-1103.D. A. Salvatore, C. M. Gabardo, A. Reyes, C. P. O’Brien, S. Holdcroft, P. Pintauro, B. Bahar, M. Hickner, C. Bae, D. Sinton, E. H. Sargent and C. P. Berlinguette, Nature Energy, 2021, 6, 339-348.K. Lin, Q. Chen, M. R. Gerhardt, L. Tong, S. B. Kim, L. Eisenach, A. W. Valle, D. Hardee, R. G. Gordon, M. J. Aziz and M. P. Marshak, Science, 2015, 349, 1529-1532.R. D. Cusick, Y. Kim and B. E. Logan, Science, 2012, 335, 1474-1477.J. Wang, Y. Zhao, B. P. Setzler, S. Rojas-Carbonell, C. Ben Yehuda, A. Amel, M. Page, L. Wang, K. Hu, L. Shi, S. Gottesfeld, B. Xu and Y. Yan, Nature Energy, 2019, 4, 392-398.G. Braesch, Z. Wang, S. Sankarasubramanian, A. G. Oshchepkov, A. Bonnefont, E. R. Savinova, V. Ramani and M. Chatenet, Journal of Materials Chemistry A, 2020, 8, 20543-20552.S. Kabir, K. Lemire, K. Artyushkova, A. Roy, M. Odgaard, D. Schlueter, A. Oshchepkov, A. Bonnefont, E. Savinova, D. C. Sabarirajan, P. Mandal, E. J. Crumlin, Iryna V. Zenyuk, P. Atanassov and A. Serov, Journal of Materials Chemistry A, 2017, 5, 24433-24443.H. Adabi, A. Shakouri, N. Ul Hassan, J. R. Varcoe, B. Zulevi, A. Serov, J. R. Regalbuto and W. E. Mustain, Nature Energy, 2021, 6, 834-843.H. Erikson, A. Sarapuu and K. Tammeveski, ChemElectroChem, 2019, 6, 73-86.

Influence of operation modes on gravity-driven membrane process in treating the secondary effluent: Flux improvement and biocake layer property

A low flux level of the gravity-driven membrane (GDM) process constrained its extensive application in treating the secondary effluent. In this study, different operation modes were introduced to the GDM process without aeration, backwashing, and chemical cleanings, hoping to develop simple and economic flux regulating strategies, and their influences on the filtration performances and biocake layer characteristics were systematically investigated. The results indicated that the stable fluxs in the intermittent GDM systems elevated by 40%–100% relative to the continuous GDM case, attributing to the synergetic effects of forming more permeable, mushroom-like structures and reducing the concentrations of EPS and SMP within biocake layers. The quantitative analysis of biocake layer properties suggested that the structural parameters of porosity and absolute roughness were closely related to the flux variation compared to the thickness and relative roughness. Besides, the intermittent GDM system generated an apparent detachment of the biocake layer from the membrane surface along with a persistent flux increase than in the continuous GDM case during long-term filtration, achieving its self-sustained operation in a higher flux level without any interferences. The periodical flux recovery and decline occurred daily in each intermittent GDM system since the biocake layer attached to the membrane surface was mainly reversible. Although there were no significant differences in removing dissolved organic pollutants under different operation modes, the manganese removals decreased by 0%–25% in the intermittent GDM filtrations compared to the continuous GDM scenario. The optimized daily operation mode was 16 h on / 8 h off (operation of 16 h, interruption of 8 h), considering the trade-off effects between membrane flux level and water production. These findings provide a new simply-feasible optimized GDM process operation strategy and benefit promoting the application of the GDM system in the reclamation of wastewater.

Uncovering the Potential of Lipid Drugs: A Focus on Transient Membrane Microdomain-targeted Lipid Therapeutics

Membrane lipids are generally viewed as inert physical barriers, but many vital cellular processes greatly rely on the interaction with these structures, as expressed by the membrane hypothesis that explain the genesis of schizophrenia, Alzheimer's and autoimmune diseases, chronic fatigue or cancer. The concept that the cell membrane displays transient membrane microdomains with distinct lipid composition providing the basis for the development of selective lipid-targeted therapies, the membrane-lipid therapies (MLTs). In this concern, medicinal chemists may design therapeutically valuable compounds 1) with a higher affinity for the lipids in these microdomains to restore the normal physiological conditions, 2) that can directly or 3) indirectly (via enzyme inhibition/activation) replace damaged lipids or restore the regular lipid levels in the whole membrane or microdomain, 4) that alter the expression of genes related to lipid genesis/metabolism or 5) that modulate the pathways related to the membrane binding affinity of lipid-anchored proteins. In this context, this mini-review aims to explore the structural diversity and clinical applications of some of the main membrane and microdomain-targeted lipid drugs.

Antifungal potential of isoespintanol extracted from Oxandra xylopioides diels (Annonaceae) against intrahospital isolations of Candida SPP

The aim of this study was to evaluate the antifungal activity of isoespintanol (ISO) extracted from Oxandra xylopioides Diels (Annonaceae) against clinical isolates of Candida spp. Isoespintanol was obtained from the petroleum benzine extract of the leaves and was identified by nuclear magnetic resonance (NMR) and mass spectrometry (MS). For antifungal activity experiments, the broth microdilution method was used. The results show an inhibitory effect against Candida spp., with minimum inhibitory concentration (MIC) values between 450.4–503.3 μg/mL. Furthermore, the inhibitory effect of ISO against fungal biofilms is highlighted, even in some cases, greater than the effect shown by amphotericin B (AFB) and in others, where AFB showed no effect. Assays with fluorescent staining with acridine orange (AO) and ethidium bromide (EB), transmission electron microscopy (TEM), Evans blue, measurement of extracellular pH and leakage of intracellular material, evidenced damage at the level of fungal membranes and general cell damage, when cells were exposed to ISO, compared to untreated cells. The results of this research, serve as the basis for future studies in the establishment of the mechanisms of antifungal action of ISO, which could serve as an adjunct in the treatment of infections by these yeasts.

Fatty Acids of Erythrocyte Membranes and Blood Serum in Differential Diagnosis of Inflammatory Bowel Diseases

Aim: to study fatty acid levels in erythrocyte membranes (RBC) and blood serum (BS) in patients with inflammatory bowel diseases (IBDs) to develop differential diagnostic models including fatty acids as biomarkers to distinguish between nosological entities of IBDs (ulcerative colitis — UC, Crohn's disease — CD, unclassified colitis — UCC).Materials and methods. We examined 110 patients (mean age 37,7 ± 12,1 years) with IBDs and 53 healthy patients in control group (43,3 ± 11,7 years). The IBDs group included 50 patients with UC, 41 patients with CD, 19 patients with UCC. An exacerbation of the disease was revealed in 42 patients (84 %) with UC, 34 patients with CD (82.9 %) and 11 people with UCC (57.9 %). The study of fatty acids (FA) composition of RBC membranes and BS was carried out using GC/MS system based on three Agilent 7000B quadrupoles (USA).Results. The most significant for distinguishing active UC from CD exacerbation were serum levels of elaidin (p = 0.0006); docosatetraenoic (n-6) (p = 0.004); docodienic (n-6) (p = 0.009); omega-3/omega-6 ratio (p = 0.02); docosapentaenoic (n-3) (p = 0.03); the sum of eicosapentaenoic and docosahexaenoic (p = 0.03), as well as the content of RBC lauric FA (p = 0.04) (AUC — 0.89, sensitivity — 0.91, specificity — 0.89, diagnostic accuracy — 0.91). To distinguish active UC from the same of UCC, the following serum FA were found to be significant: alpha-linolenic; saturated (pentadecanoic, palmitic, stearic, arachidic); monounsaturated (palmitoleic, oleic); omega-6 (hexadecadienic, arachidonic) (p = 0.00000011—0.03300000) (AUC — 0.995, sensitivity — 0.98, specificity — 0.96, diagnostic accuracy — 0.97). The most significant in distinguishing patients with active CD from UCC exacerbation were levels of the following FA: alpha-linolenic; palmitoleic; oleic; the amount of saturated fatty acids (SFA); total unsaturated fatty acids (UFA); stearic; monounsaturated fatty acids (MUFA) amount; SFA/UFA; SFA/PUFA (polyunsaturated fatty acids); linoleic; total PUFA n6; lauric; arachidic acid (p = 0.0000000017–0.030000000) (AUC — 0.914, sensitivity — 0.90, specificity — 0.87, diagnostic accuracy — 0.91).Conclusion. The study of FA levels in groups with different nosological forms of IBDs using complex statistical analysis, including machine learning methods, made it possible to create diagnostic models that differentiate CD, UC and UCC in the acute stage with high accuracy. The proposed approach is promising for the purposes of differential diagnosis of nosological forms of IBDs.

Structural Insights into the Binding Propensity of Human SHIP2 SH2 to Oncogenic CagA Isoforms from Helicobacter pylori.

SHIP2 is a multi-domain inositol 5-phosphatase binding to a variety of phosphotyrosine (pY)-containing proteins through its SH2 domain, so as to regulate various cell signaling pathways by modulating the phosphatidylinositol level in the plasma membrane. Unfavorably, Helicobacter pylori can hijack SHIP2 through the CagA protein to induce gastric cell carcinogenesis. To date, the interaction between SHIP2 and CagA was not analyzed from a structural point of view. Here, the binding of SHIP2-SH2 with Tyr-phosphorylated peptides from four EPIYA motifs (A/B/C/D) in CagA was studied using NMR spectroscopy. The results showed that EPIYA-C and -D bind to a similar interface of SHIP2-SH2, including a pY-binding pocket and a hydrophobic pocket, to achieve high affinity, while EPIYA-A and -B bind to a smaller interface of SHIP2-SH2 with weak affinity. By summarizing the interface and affinity of SHIP2-SH2 for CagA EPIYA-A/B/C/D, c-MET and FcgR2B ITIM, it was proposed that, potentially, SHIP2-SH2 has a selective preference for L > I > V for the aliphatic residues at the pY+3 position in its ligand. This study reveals the rule of the ligand sequence bound by SHIP2-SH2 and the mechanism by which CagA protein hijacks SHIP2, which will help design a peptide inhibitor against SHIP2-SH2.

Relationship between age of pregnant women with gestational diabetes mellitus and mode of delivery and neonatal Apgar score.

BACKGROUNDGestational diabetes mellitus (GDM) refers to abnormal glucose tolerance during pregnancy, and it is often accompanied by obvious changes in glucose and lipid metabolism, and associated with adverse pregnancy outcomes. The incidence of fetal distress, polyhydramnios, puerperal infection, premature delivery, and macrosomia in pregnant women with GDM are higher than in those without GDM.AIMTo analyze the relationship between age of pregnant women with GDM and mode of delivery and neonatal Apgar score.METHODSA total of 583 pregnant women with GDM who delivered in the Department of Obstetrics at our hospital between March 2019 and March 2022 were selected. Among them, 377 aged < 35 years were selected as the right age group and 206 aged > 35 years were selected as the older group. The clinical data of the two groups were collected, and the relationship between age of the pregnant women with GDM and mode of delivery, maternal and neonatal outcomes, and neonatal Apgar score were compared. In the older group, 159 women were classed as the adverse outcome group and 47 as the good outcome group according to whether they had adverse maternal and infant outcomes. The related factors of adverse maternal and infant outcomes were analyzed through logistic regression.RESULTSThe number of women with assisted pregnancy, ≤ 37 wk gestation, ≥ 2 pregnancies, one or more deliveries, and no pre-pregnancy blood glucose screening in the older group were all higher than those in the right age group (P < 0.05). The natural delivery rate in the right age group was 40.85%, which was higher than 22.33% in the older group (P < 0.05). The cesarean section rate in the older group was 77.67%, which was higher than 59.15% in the right age group (P < 0.05). The older group had a higher incidence of polyhydramnios and postpartum hemorrhage, and lower incidence of fetal distress than the right age group had (P < 0.05). There was no significant difference in neonatal weight between the two groups (P > 0.05). The right age group had higher Apgar scores at 1 and 5 min than the older group had (P < 0.05). Significant differences existed between the poor and good outcome groups in age, education level, pregnancy mode, ≤ 37 wk gestation, number of pregnancies, and premature rupture of membranes (P < 0.05). Logistic regression showed that age, education level and premature rupture of membranes were all risk factors affecting the adverse outcomes of mothers and infants (P < 0.05).CONCLUSIONDelivery mode and Apgar score of pregnant women with GDM are related to age. Older age increases the adverse outcome of mothers and infants.

The role of cell adhesion molecules in the progression of bladder urothelial carcinomas.

Alteration of the intercellular adhesion system plays an essential role in the initiation and progression of bladder carcinomas. We followed the immunoexpression of adhesion molecules, E-cadherin, β-catenin and Claudin-1, in relation to the histopathological grade and the pT category in a number of 50 urothelial carcinomas of the bladder, based on a final staining score (FSS), calculated on the basis of reaction intensity and labeled cells number. E-cadherin immunoexpression was identified in the membrane of tumor cells, low FSS being associated with invasive high-grade carcinomas. β-catenin reactions were membranous in the case of low-grade noninvasive carcinomas and predominantly cytoplasmic and nuclear in the case of high-grade invasive ones, for which high FSS were associated. Claudin-1 was identified at the membrane level, the high FSS values being more frequent in the case of high-grade invasive carcinomas, although there were no significant statistical associations. Loss of E-cadherin expression and the associated positive linear relation of β-catenin and Claudin-1 indicate the usefulness of the analyzed markers in identifying the invasive aggressive phenotype of urothelial bladder carcinomas.

Membrane interaction to intercellular spread of pathology in Alzheimer's disease.

Progressive development of pathology is one of the major characteristic features of neurodegenerative diseases. Alzheimer’s disease (AD) is the most prevalent among them. Extracellular amyloid-β (Aβ) plaques and intracellular tau neurofibrillary tangles are the pathological phenotypes of AD. However, cellular and animal studies implicate tau as a secondary pathology in developing AD while Aβ aggregates is considered as a trigger point. Interaction of Aβ peptides with plasma membrane (PM) seems to be a promising site of involvement in the events that lead to AD. Aβ binding to the lipid membranes initiates formation of oligomers of Aβ species, and these oligomers are known as primary toxic agents for neuronal toxicities. Once initiated, neuropathological toxicities spread in a “prion-like” fashion probably through the mechanism of intercellular transfer of pathogenic aggregates. In the last two decades, several studies have demonstrated neuron-to-neuron transfer of neurodegenerative proteins including Aβ and tau via exosomes and tunneling nanotubes (TNTs), the two modes of long-range intercellular transfer. Emerging pieces of evidence indicate that molecular pathways related to the biogenesis of exosomes and TNTs interface with endo-lysosomal pathways and cellular signaling in connection to vesicle recycling-imposed PM and actin remodulation. In this review, we discuss interactions of Aβ aggregates at the membrane level and its implications in intercellular spread of pathogenic aggregates. Furthermore, we hypothesize how spread of pathogenic aggregates contributes to complex molecular events that could regulate pathological and synaptic changes related to AD.

The E3 ubiquitin-protein ligase Nedd4-2 regulates the sodium chloride cotransporter NCC but is not required for a potassium-induced reduction of NCC expression.

Na+ and K+ balance is influenced by the activity of the sodium chloride cotransporter NCC in the distal convoluted tubule. NCC activity and abundance are reduced by high extracellular K+. The E3 ubiquitin ligase neural precursor cell expressed developmentally downregulated 4–2 (Nedd4-2) has been proposed as a modulator of NCC abundance. Here, we examined the functional role of Nedd4-2 on NCC regulation and whether Nedd4-2 is important for the effects of high extracellular K+ on NCC. Total and plasma membrane levels of ubiquitylated NCC were lower in NCC-expressing MDCKI cells after Nedd4-2 deletion. NCC and phosphorylated NCC (pT58-NCC) levels were higher after Nedd4-2 deletion, and NCC levels on the plasma membrane were elevated. No significant changes were seen after Nedd4-2 knockdown in the levels of SPAK and phosphorylated SPAK (pS373-SPAK), the major NCC regulatory kinase. Nedd4-2 deficiency had no effect on the internalization rate of NCC from the plasma membrane, but NCC protein half-life was increased. In ex vivo experiments with kidney tubule suspensions from Nedd4-2 knockout (KO) mice, high K+ reduced total and pT58-NCC regardless of genotype. We conclude that Nedd4-2 is involved in ubiquitylation of NCC and modulating its plasma membrane levels and degradation. However, Nedd4-2 does not appear to be important for K+ induced reductions in NCC abundance.

Changes of Lipid Peroxidation after Administration of Nanomodified Resuspending Solution into Donor Red Blood Cells

The problem of increasing the functional activity preservation of red blood cells is priority for the Blood Service and clinical transfusiology. Taking into account the previously discovered unique properties of magnetite nanoparticles, namely: nonspecific modulation of metabolic processes, strengthening of adaptive mechanisms of cellular organelles, acceleration of reparative processes at the level of membranes and macromolecules, for the first time an attempt was made to use the upgraded saline solution of sodium chloride (nanotechnologically upgraded solution - NUS) as a resuspending of erythrocyte-containing components (ECC). Objective: to improve the preservation of red blood cells containing donor blood components using NUS for resuspending. To achieve this goal, the first stage of the study examined the effect of a new resuspending solution (NUS) on lipoperoxidation, catalase activity, and red blood cell peroxidation resistance in donor blood components containing red blood cells. Object of Research: red blood cells from preservation blood of donors, which are intended for component transfusion therapy. As a result of the study, the advantages of using NUS were established, namely: a significant decrease in the levels of primary and secondary lipid peroxidation products in the first 15 days of observation, an increase in catalase activity and resistance of red blood cells to peroxidation in the first stages of the study, inhibition of the shear reaction with neutral lipid peroxidation in the late stages of observation.

New dual dye for vitreoretinal surgery with increased transparency

ObjectivesTo develop a new dye formulation for vitreoretinal surgery, which shows increased transparency for better intraoperative handling with better parameters important for use.Methods and analysisA new blue dye, DDG, was...

Snail Track Lesion with Flat Keratometry in Anterior Segment Dysgenesis Caused by a Novel FOXC1 Variant.

We report the phenotype of a 15-year-old female patient with anterior segment dysgenesis (ASD) caused by a novel heterozygous loss-of-function FOXC1 variant. The proband underwent an ophthalmic examination as well as a molecular genetic investigation comprising exome sequencing, a single nucleotide polymorphism array to access copy number and Sanger sequencing to exclude non-coding causal variants. There was bilateral mild iris hypoplasia with pupil deformation and iridocorneal adhesions. In addition to these features of ASD, the corneas were flat, with mean keratometry readings of 38.8 diopters in the right eye and 39.5 diopters in the left eye. There was a snail track lesion of the left cornea at the level of the Descemet membrane. The central corneal endothelial cell density was reduced bilaterally at 1964 and 1373 cells/mm2 in the right and left eyes, respectively. Molecular genetic analysis revealed that the proband was a carrier of a novel heterozygous frameshifting variant in FOXC1, c.605del p.(Pro202Argfs*113). Neither parent had this change, suggesting a de novo origin which was supported by paternity testing. We found no possibly pathogenic variants in the other genes associated with posterior corneal dystrophies or ASD. Further studies are warranted to verify whether there is a true association between snail track lesions, corneal flattening, and pathogenic variants in FOXC1.

KRAS Promoter Methylation Status and miR-18a-3p and miR-143 Expression in Patients With Wild-type KRAS Gene in Colorectal Cancer.

Although some mutations of KRAS proto-oncogene, GTPase (KRAS) have been associated with the prognosis and therapeutic management of colorectal cancer (CRC), the epigenetic mechanisms (DNA methylation and microRNA expression) that regulate wild-type KRAS expression in patients with CRC are poorly known. The aim of this study was to establish whether there is a relationship between the expression of the wild-type KRAS gene, the methylation status of its distal promoter, and miR-143 and miR-18a-3p levels in samples of sporadic CRC. A total of 51 cases of sporadic CRC with wild-type KRAS were analyzed. The expression levels of KRAS mRNA, miR-18a-3p, miR-143, and KRAS protein, as well as methylation in the distal promoter of the KRAS gene were evaluated. In the analyzed cases, KRAS mRNA expression was detected in 51.1%; wild-type KRAS protein was found in the membrane in 31.4% and in the cytoplasm in 98% of cases. An inverse relationship of marginal significance was observed between miR-18a-3p and KRAS protein expression in the cytoplasm (odds ratio=0.14, 95% confidence interval=0.012-1.092; p=0.08). The methylation status of the distal promoter of KRAS at four CpG islands was analyzed in 30 cases (58.8%): partial methylation of the four CpG islands evaluated was observed in two cases (6.7%). In these cases, KRAS protein expression was not evidenced at the membrane level; miR-18a-3p expression was not detected either but high expression of miR-143 was observed. No association was found between the expression levels of KRAS mRNA, miR-18a-3p, miR-143 and methylation status. Methylation status was detected with low frequency, thus being the first report of methylation in wild-type KRAS.

Preparation and in vitro biocompatibility of PBAT and chitosan composites for novel biodegradable cardiac occluders

Abstract The biodegradable composites were prepared by melt blending of chitosan (CS) and poly(butyleneadipate-co-terephthalate) (PBAT). By utilizing Fourier transformed infrared spectroscopy, scanning electron microscopy-energy dispersive spectroscopy, mechanical properties analysis, water contact angle measuring, differential scanning calorimetry, and thermogravimetric analysis, it was demonstrated that the CS of the PBAT-CS10 composite was relatively evenly dispersed in the PBAT matrix, the mechanical properties were significantly improved, the hydrophilicity was increased, the cold crystallization temperature was increased, and a good range of melt working temperature was obtained. The PBAT-CS10 composite was used to fabricate a cardiac occluder by fused deposition modeling of three-dimensional printing, and finite element analysis, and in vitro implantation testing proved the occluder’s mechanical support and sealing function under extreme boundary conditions. In vitro degradation experiments, neutral red uptake cytotoxicity assay, CCK-8 cell proliferation detection, immunofluorescence staining of the cytoskeleton, cell apoptosis detection, and reactive oxygen species assay were all performed on the composite, confirming that it and the occluder made of it could be hydrolyzed under physiological conditions and had no adverse effects on the cell membrane, lysosome membrane, cell proliferation, cell morphology, cell apoptosis, or ROS level, and had good biocompatibility.

PROGNOSTIC VALUE OF DYNAMIC THIOL-DISULFIDE HOMEOSTASIS IN PREDICTING HOSPITAL MORTALITY IN HYPOXEMIC RESPIRATORY FAILURE

Hypoxemic respiratory failure (HRF) has a PaO2 &lt; 60 mmHg with normal or subnormal PaCO2. The gas exchange is impaired at the level of the alveolo-capillary membrane. HRF is associated with high mortality in hospital, and there is no diagnostic laboratory test to predict this mortality. This study evaluates the possibility of predicting mortality in HRF patients with dynamic thiol-disulfide homeostasis parameters, which are indicators of oxidation state. Sixty-two patients with HRF and 40 healthy controls were included in the study. Dynamic thiol-disulfide parameters were studied from the serum of all participants. Total and native thiol levels were significantly lower in the patients than in the controls (p &lt; 0.05). Disulfide levels were higher in patients who died than survivors (p

Supplementing clinical diagnostics of erosive joint diseases with bio-inspired ratiometric sensors

Inflammatory rheumatological disorders are often characterised by altered levels of matrix metalloproteinase levels in joint fluid and joint membranes. Therefore, monitoring of MMP activity in synovial fluid is essential to enable timely diagnosis, prognosis, and effective treatment. Here we report a novel fluorescence assay to measure protease activity in aspirated synovial fluid. Our fluorescent reporters contain cleavable linkers based on the peptide sequences of protease substrates, showing a ratiometric output upon cleavage. We have validated our reporters in patient-derived synovial fluid, and demonstrated their ability to characterise disease type.

Interaction of Oxicam Derivatives with the Artificial Models of Biological Membranes-Calorimetric and Fluorescence Spectroscopic Study.

The modified 1,2-benzothiazine analogues designed as new drug candidates and discussed in this paper are oxicam derivatives. Oxicams are a class of non-steroidal anti-inflammatory drugs (NSAIDs). Their biological target is cyclooxygenase (COX), a membrane protein associated with the phospholipid bilayer. In recent decades, it has been proven that the biological effect of NSAIDs may be closely related to their interaction at the level of the biological membrane. These processes are often complicated and the biological membranes themselves are very complex. Therefore, to study these mechanisms, simplified models of biological membranes are used. To characterize the interaction of six oxicam derivatives with DPPC, DMPC and EYPC, artificial models of biological membranes (multi-bilayers or liposomes), differential scanning calorimetry (DSC) and fluorescence spectroscopy techniques were applied. In spectroscopic measurements, two fluorescent probes (Laurdan and Prodan) localized in different membrane segments were used. All tested oxicam derivatives interacted with the lipid bilayers and may penetrate the artificial models of biological membranes. They intercalated into the lipid bilayers and were located in the vicinity of the polar/apolar membrane interface. Moreover, a good drug candidate should not only have high efficiency against a molecular target but also exhibit strictly defined ADMET parameters, therefore these activities of the studied compounds were also estimated.

Finite Time Thermodynamic Modeling and Performance Analysis of High-Temperature Proton Exchange Membrane Fuel Cells.

In order to improve the output performance of high-temperature proton exchange membrane fuel cells (HT-PEMFC), a finite time thermodynamic (FTT) model for HT-PEMFC was established. Several finite time thermodynamic indexes including power density, thermodynamic efficiency, exergy efficiency, exergetic performance efficient (EPC), entropy production rate and ecological coefficient of performance (ECOP) were derived. The energetic performance, exergetic performance and ecological performance of the HT-PEMFC were analyzed under different parameters. Results showed that operating temperature, doping level and thickness of membrane had a significant effect on the performance of HT-PEMFC and the power density increased by 58%, 31.1% and 44.9%, respectively. When the doping level reached 8, the output performance of HT-PEMFC wa optimal. The operating pressure and relative humidity had little influence on the HT-PEMFC and the power density increased by 8.7%% and 17.6%, respectively.

Behavioral and Molecular Responses to Exogenous Cannabinoids During Pentylenetetrazol-Induced Convulsions in Male and Female Rats.

Epilepsy is a disabling, chronic brain disease,affecting ~1% of the World’s population, characterized by recurrent seizures (sudden, uncontrolled brain activity), which may manifest with motor symptoms (e.g., convulsions) or non-motor symptoms. Temporal lobe epilepsies (TLE) compromising the hippocampus are the most common form of focal epilepsies. Resistance in ~1/3 of epileptic patients to the first line of treatment, i.e., antiepileptic drugs (AEDs), has been an important motivation to seek alternative treatments. Among these, the plant Cannabis sativa (commonly known as marihuana) or compounds extracted from it (cannabinoids) have gained widespread popularity. Moreover, sex differences have been proposed in epilepsy syndromes and in cannabinoid action. In the hippocampus, cannabinoids interact with the CB1R receptor whose membrane levels are regulated by β-Arrestin2, a protein that promotes its endocytosis and causes its downregulation. In this article, we evaluate the modulatory role of WIN 55,212-2 (WIN), a synthetic exogenous cannabinoid on behavioral convulsions and on the levels of CB1R and β-Arrestin2 in female and male adolescent rats after a single injection of the proconvulsant pentylenetetrazol (PTZ). As epilepsies can have a considerable impact on synaptic proteins that regulate neuronal toxicity, plasticity, and cognition, we also measured the levels of key proteins markers of excitatory synapses, in order to examine whether exogenous cannabinoids may prevent such pathologic changes after acute seizures. We found that the exogenous administration of WIN prevented convulsions of medium severity in females and males and increased the levels of phosphorylated CaMKII in the hippocampus. Furthermore, we observed a higher degree of colocalization between CB1R and β-Arrestin2 in the granule cell layer.