Increase In Water Permeability Research Articles

Polilaktida plastifikatua elikagaien ontziratzerako: plastifikatzailearen pisu molekularraren eragina bolumen aske eta hesi-ezaugarrietan

Gaur egun plastikoen hondakinek sorrarazten duten arazoari aurre egiteko aukera bat polimero biodegradagarriak erabiltzea da. Horien artean polilaktidak interes handia piztu du, baina elikagaien ontziratzean erabilgarria izan dadin bere deformakortasuna hobetu behar da. Helburu horrekin lan honetan polilaktidari polietilenglikol (PEG) plastifikatzailea gehitu zaio. Zehazki pisu molekular desberdina daukaten hiru polietilenglikol erabili dira, eta pisu molekularrak propietate fisikoetan daukan eragina aztertu da. Plastifikatzailea gehitutakoan beira-trantsizio tenperatura jaitsi egiten da, bereziki pisu molekular altuena duen polietilenglikola gehitutakoan, eta kristalinitate-maila handiagoa egiten da. Bolumen askean aldaketak txikiak badira ere, plastifikatzaile kantitatea handitu ahala, bolumen askea nabarmen handiagoa egiten da. Hesi ezaugarriei dagokienez, oxigenoaren kasuan iragazkortasuna murriztu edo bere horretan mantentzen da; karbono dioxidoaren eta uraren kasuan, ordea, iragazkortasuna handitu egiten da plastifikatzaile kantitatearekin batera. Aipatzekoa da plastifikatzaile nahaste desberdinen artean pisu molekular baxueneko plastifikatzailea duen sistemak azaltzen dituela iragazkortasun balio altuenak. PEG 1500 eta PEG 4600 sistemen kasuan aldaketak ez dira hain nabariak, eta, pisu molekularraz gainera, beste faktore batzuek, hala nola beira-trantsizio tenperaturak, kristalinitate-mailak eta bolumen askeak, ere eragina daukate.

Liposomes-assisted fabrication of high performance thin film composite nanofiltration membrane

Conventional biomimetic membranes for desalination are mostly fabricated by incorporating water channels using self-assembled lipid or polymer vesicles as key platforms for protein or water channel reconstitution. Herein, we propose a thin film composite nanofiltration membrane via an unconventional liposomes-assisted fabrication without the incorporation of protein or water channels. The polyamide skin layer containing liposomes was thinner and filled with wrinkles and nanovoids. As a result, compared with the liposome-free control membrane, our optimized liposome-assisted membrane was able to achieve an increased water permeability from 11.17 to 18.21 LMH/bar, alongside an excellent MgCl2 rejection of 95.87% and a monovalent/divalent (NaCl/MgCl2) ion selectivity (α) of 18.2. Extensive membrane characterization showed that the liposome-assisted skin layer indeed exhibited a smaller thickness with an increased effective membrane area and a reduced surface hydrophobicity, which contribute towards a reduction in the hydrodynamic resistance of the polyamide layer. Furthermore, our approach of liposome-assisted thin film composite membrane is simpler and more scalable to fabricate without protein or water channels incorporation, rendering our design more attractive for future nanofiltration using vesicle-embedded biomimetic membranes.

The 3-ketoacyl-CoA synthase WFL is involved in lateral organ development and cuticular wax synthesis in Medicago truncatula.

A 3-ketoacyl-CoA synthase involved in biosynthesis of very long chain fatty acids and cuticular wax plays a vital role in aerial organ development in M. truncatula. Cuticular wax is composed of very long chain fatty acids and their derivatives. Defects in cuticular wax often result in organ fusion, but little is known about the role of cuticular wax in compound leaf and flower development in Medicago truncatula. In this study, through an extensive screen of a Tnt1 retrotransposon insertion population in M. truncatula, we identified four mutant lines, named wrinkled flower and leaf (wfl) for their phenotype. The phenotype of the wfl mutants is caused by a Tnt1 insertion in Medtr3g105550, encoding 3-ketoacyl-CoA synthase (KCS), which functions as a rate-limiting enzyme in very long chain fatty acid elongation. Reverse transcription-quantitative PCR showed that WFL was broadly expressed in aerial organs of the wild type, such as leaves, floral organs, and the shoot apical meristem, but was expressed at lower levels in roots. In situ hybridization showed a similar expression pattern, mainly detecting the WFL transcript in epidermal cells of the shoot apical meristem, leaf primordia, and floral organs. The wfl mutant leaves showed sparser epicuticular wax crystals on the surface and increased water permeability compared with wild type. Further analysis showed that in wfl leaves, the percentage of C20:0, C22:0, and C24:0 fatty acids was significantly increased, the amount of cuticular wax was markedly reduced, and wax constituents were altered compared to the wild type. The reduced formation of cuticular wax and wax composition changes on the leaf surface might lead to the developmental defects observed in the wfl mutants. These findings suggest that WFL plays a key role in cuticular wax formation and in the late stage of leaf and flower development in M. truncatula.

Toward tailoring of a new draw solute for forward osmosis process: Branched poly (deep eutectic solvent)-decorated magnetic nanoparticles

The introduction of suitable draw solutes is a critical factor in increasing water permeability of a forward osmosis (FO) process. In this study, a branched poly (deep eutectic solvent) was synthesized by surface initiated ring opening polymerization of glycidol on the magnetic core followed by introducing choline chloride as hydrogen bond acceptor to glycerol moieties. Due to the polyionic nature of as-synthesized material, it was expected to represent high osmotic pressure and high water flux. Moreover, the existence of Fe3O4 magnetic nanoparticles as core leads to easy separation of draw solute by an external magnetic field with low energy consumption. The FO performance of the branched poly (deep eutectic solvent)@Fe3O4 as a draw solute was investigated where the water flux of 17.9 L m−2 h−1 (LMH) and the reverse solute flux of 0.12 g m−2 h−1 (gMH) were obtained for 3.5 g L−1 solution. The recyclability of magnetic draw solute was also studied to ensure the FO applicability. Moreover, the brackish water containing 0.2 M and 0.3 M NaCl was also employed as a feed solution to evaluate the capability of branched poly (deep eutectic solvent)@Fe3O4 for the water desalination process.

Abstract MP01: Vasopressin Contributes To Differences In The Physiology Of Hypertension Between Non-Hispanic Blacks And Whites

Objective: Vasopressin increases water permeability and activity of the epithelial sodium channel ENaC in the distal nephron of the kidney, favoring increased water and sodium retention. We hypothesized that genetically mediated differences in circulating vasopressin concentrations could contribute to features of hypertension that vary between non-Hispanic blacks and whites. To test this hypothesis we measured copeptin, a fragment of pre-pro arginine vasopressin with a prolonged half-life that is more easily quantified. Methods: The Genetic Epidemiology of Responses to Antihypertensives (GERA) I study was designed to identify predictors of response to diuretic therapy in non-Hispanic black and non-Hispanic white adults with essential hypertension. Blood samples were obtained after a 4 week washout of anti-hypertensive medication while on a sodium intake of 2 mmol/kg. Copeptin was measured from thawed EDTA plasma samples using the copeptin proAVP homogeneous automated immunofluorescent assay on the BRAHMS Kryptor Compact PLUS (Thermo Fisher). Results: Copeptin was significantly higher in blacks (median: 7.4 pmol/L, IQR: 4.4-10.2 pmol/L) than in whites (median: 5.4 pmol/L, IQR: 3.6-8.0 pmol/L) (p <0.001), while renin was lower (Table 1). Racial differences remained significant (p = 0.001) in multivariate models that included 24 hour urine sodium excretion and calculated plasma osmolality. Conclusions: Higher copeptin (vasopressin) concentrations in non-Hispanic blacks compared to whites may contribute to the distinct differences in the hypertensive phenotypes between these racial groups. The underlying mechanism(s) require further study.

How do nitrated lipids affect the properties of phospholipid membranes?

Biological membranes are under constant attack of free radicals, which may lead to lipid nitro-oxidation, producing a complex mixture of nitro-oxidized lipids that are responsible for structural and dynamic changes on the membrane. Despite the latter, nitro-oxidized lipids are also associated with several inflammatory and neurodegenerative diseases, the underlying mechanisms of which remain elusive. We perform atomistic molecular dynamics simulations using several isomers of nitro-oxidized lipids to study their effect on the structure and permeability of the membrane, as well as the interaction between the mixture of these products in the phospholipid membrane environment. Our results show that the stereo- and positional isomers have a stronger effect on the properties of the membrane composed of oxidized lipids compared to that containing nitrated lipids. Nevertheless, nitrated lipids lead to three-fold increase in water permeability compared to oxidized lipids. In addition, we show that in a membrane consisting of combined nitro-oxidized lipid products, the presence of oxidized lipids protects the membrane from transient pores. Is well stablished that plasma application and photodynamic therapy produces a number of oxidative species used to kill cancer cells, through membrane damage induced by nitro-oxidative stress. This study is important to elucidate the mechanisms and the molecular level properties involving the reactive species produced during that cancer therapies.

Discrete Nanoscale Distribution of Hair Lipids Fails to Provide Humidity Resistance.

The subcellular distribution of lipids in human hair was investigated to better understand their role in water permeability. Unlike stratum corneum where lipids are organized under a precisely ordered continuous structure, the removal of free lipids in hair does not lead to an increase of water permeability. Esterified and CH2-enriched molecules were tracked at a 10 nm resolution by infrared nanospectroscopy (atomic force microscopy coupled to infrared spectroscopy, AFMIR). Free and bound lipids in the 25 nm thick intercellular spaces were directly detected for the first time, further substantiating the potential of AFMIR to study complex biomaterials. We observed that they were mostly found accumulated in some regions of the external cuticle layers, as "hotspots" in nonkeratinous portions of the internal cortex, and that they do not seem to modulate much the water exchanges due to their discrete distribution throughout the hair fiber.

Engineering Heterostructured Thin-Film Nanocomposite Membrane with Functionalized Graphene Oxide Quantum Dots (GOQD) for Highly Efficient Reverse Osmosis.

In this study, custom-tailored graphene oxide quantum dots (GOQD) were synthesized as functional nanofillers to be embedded into the polyamide (PA) membrane for reverse osmosis (RO) via interfacial polymerization (IP). The heterostructured interface-functionalization of amine/sulfonic decoration on GOQD (N/S-d-GOQD) takes place via the tuning of the molecular design. The embedded N/S-d-GOQD inside the PA matrix contributes to facilitating water molecules quick transport due to the more accessible capturing sites with higher internal polarity, achieving a nearly 3-fold increase in water permeance when compared to the pristine thin-film composite (TFC) membrane. Covalent bonding between the terminal amine groups and the acyl chloride of trimesoyl chloride (TMC) enables the formation of an amplified selective layer, while the sulfonic part assists in maintaining a robust membrane surface negative charge, thus remarkably improving the membrane selectivity toward NaCl. As a result, the newly developed TFN membrane performed remarkably high water permeance up to 5.89 L m-2 h-1 bar-1 without the compromising of its favorable salt (NaCl) rejection ratio of 97.1%, revealing a comparably high separation property when comparing to the state-of-the-art RO membranes, and surpassing the permeability-selectivity trade-off limits. Furthermore, we systematically investigated the GOQDs with different surface decorations but similar configurations (including 3 different nanofillers of pristine GOQD, amine decorated GOQD (N-d-GOQD), and N/S-d-GOQD) to unveil the underlying mechanisms of the swing effects of internal geometry and polarity of the embedded nanofillers on contributing to the uptake, and/or release of aqueous molecules within TFN membranes, providing a fundamental perspective to investigate the impact of embedded nanofillers on the formation of an IP layer and the overall transporting behavior of the RO process.

Fabrication of High-Performance Thin-Film Composite Nanofiltration Membrane by Dynamic Calcium-Carboxyl Intra-Bridging during Post-Treatment.

Widespread applications of nanofiltration (NF) and reverse osmosis (RO)-based processes for water purification and desalination call for high-performance thin-film composite (TFC) membranes. In this work, a novel and facile modification method was proposed to fabricate high-performance thin-film composite nanofiltration membrane by introducing Ca2+ in the heat post-treatment. The introduction of Ca2+ induced in situ Ca2+-carboxyl intra-bridging, leading to the embedment of Ca2+ in the polyamide (PA) layer. This post modification enhanced the hydrophilicity and surface charge of NF membranes compared to the pristine membrane. More interestingly, the modified membrane had more nodules and exhibited rougher morphology. Such changes brought by the addition of Ca2+ enabled the significant increase of water permeability (increasing from 17.9 L·m−2·h−1·bar−1 to 29.8 L·m−2·h−1·bar−1) while maintaining a high selectivity (Na2SO4 rejection rate of 98.0%). Furthermore, the intra-bridging between calcium and carboxyl imparted the NF membranes with evident antifouling properties, exhibiting milder permeability decline of 4.2% (compared to 16.7% of NF-control) during filtration of sodium alginate solution. The results highlight the potential of using Ca2+-carboxyl intra-bridging post-treatment to fabricate high-performance TFC membranes for water purification and desalination.

Precisely Determined Water Permeabilities of Sub‐100 nm Nanochannels

AbstractMembrane ultrafiltration is an extensively used technique for water purification and hence understanding the water flow confined in nanochannels is of vital importance. As a key parameter, water permeability has been the focus of fundamental researches and technical applications. However, water permeability in sub‐100 nm regime is not yet well understood as evidenced by the previously published data which are divergent from theory. Here, the precise determination of water permeabilities of sub‐100 nm nanochannels is reported. This is achieved by the proposed innovative pore diameter‐calibration method with excellent accuracy through replicating the pore geometry, and using the nanoporous ion track‐etched membrane as a model system which features well‐defined, cylindrical, straight, and equally sized nanochannels. Thanks to this accurate calibration method, the measured permeabilities show a remarkably improved precision as compared to the previously reported data. In addition, the measured permeabilities of the ultrafiltration channels are lower than the theoretical predictions. The discrepancy is explained under the framework of the wettability effect. It is expected that the work will shed light on a controversy over a decrease or increase in water permeability of ultrafiltration membranes and also guide the design of ultrafiltration membranes for water purification and separation applications.

Effect of colloidal nanosilica as an admixture on chloride ion diffusion of Portland cement–fly ash mortars

The properties of the ordinary Portland cement (OPC) mortar having a water–cement (w/c) proportion of 0.450 and cement/sand ratio of 1:2 are altered by replacing cement with 25% fly ash and adding 2% colloidal nanosilica separately and in a combined form. The changes were studied experimentally. Cured specimens at different ages were subjected to compressive strength test, split tensile test, and durability tests such as sorptivity, water absorption, and chloride penetration. The impact of the addition of colloidal nanosilica on the permeability of the mortar matrix, estimated by the coefficient of absorptivity, was computed by performing a water absorption test for 60 min. It was observed that in the initial curing regime, fly ash expansion causes a decrease in strength and an increase in water permeability. The addition of 2% colloidal nanosilica proves to be advantageous in the hardened OPC and fly ash mortar as it increases the materials characteristic strength by conferring it a dense microstructure. Nanosilica in the cement matrix with and without fly ash assists the rapid growth of hydrated products by creating additional nucleation sites and improving the durability properties of the material as anodic polarization decreases under impressed voltage. The microstructure was analyzed by SEM and found to have the refinement of a pore structure and densification of binding gels in the colloidal nanosilica -incorporated samples.

Rapid effects of aldosterone and phosphatase inhibition on water and urea permeabilities

Aldosterone promotes renal sodium uptake, thereby increasing water reabsorption. But our previous data showed that aldosterone decreases UT‐A1 urea transporter expression, suggesting aldosterone could inhibit water reabsorption. In this study, we investigated the rapid effect of aldosterone on vasopressin‐stimulated osmotic water permeability in rat inner medullary collecting ducts (IMCDs). In IMCDs from male Sprague Dawley rats weighing 50–75g, we saw that aldosterone significantly decreased osmotic water permeability from 152 ± 21 to 122 ± 17 μm/s (45 min, n=4, p<0.01). Given the rapid nature of the response, we further investigated whether the effect of aldosterone might be through phosphatase‐mediated modulation of transporter phosphorylation. Inhibition of PP1/PP2a phosphatases by calyculin increased basal osmotic water permeability from 58 ± 8 to 92 ± 14 μm/s (n=4, p<0.01). In the presence of vasopressin, stimulation by calyculin remained significant in both male and female rats 77 ± 10 to 119 ± 15 μm/s (30 min, n=6, p<0.01). Addition of aldosterone to the bath in the presence of calyculin reversed the increase in osmotic water permeability from 119 ± 15 to 89 ± 10 μm/s (45 min, p<0.01). Inhibition of pp2B with tacrolimus also stimulated water permeability (88 ± 13 to 108 ± 19 μm/s), which was reversed by addition of aldosterone (81 ± 10 μm/s). Urea permeability was also increased by both calyculin (25 ± 7 × 10−5 to 32 ± 7 × 10−5 cm/s; n=3, p<0.05) and tacrolimus (15 ± 1 × 10−5 to 18 ± 1 × 10− 5 cm/s; n=4, p<0.05). Aldosterone decreased pser256‐ and increased pser261‐AQP2. Inhibition of PP2B by tacrolimus increased pser256‐ and decreased pser261‐AQP2. Calyculin increases pser256‐AQP2 and this was reversed by aldosterone. Treatment of inner medullary tissue with 50 nM calyculin or 62 nM tacrolimus resulted in significantly increased UT‐A1 phosphorylation. We conclude that aldosterone is able to rapidly inhibit water and urea reabsorption, possibly by altering phosphatase activity and changing the phosphorylation states of AQP2 and UT‐A1.Support or Funding InformationAHA 18CDA34060053NIH/NIDDKRO1‐DK41707

Contribution of Tricellulin to Paracellular Water Permeability in Two Epithelial Cell Lines of Different Tightness

Large amounts of water molecules pass through epithelia driven by osmotic gradients along two pathways, paracellular, transcellular, or both. The transcellular pathway comprises aquaporin (AQP) water channels and some carriers like SGLT1. The existence of a paracellular pathway for water through the tight junctions (TJ) was discussed controversially for many years until molecular components of the paracellular water transport, claudin‐2 and claudin‐15, were identified. Recently, an effect of angulin‐2 (ILDR1) on water transport was shown, suggesting that the tricellular tight junction (tTJ) is also involved, but the role of its barrier‐forming protein, tricellulin, was not elucidated so far.For analyzing this, two epithelial cell lines featuring properties of tight epithelium and intermediate‐tight epithelium, Madin‐Darby canine kidney cells clone 7 (MDCK C7) and human colon cells (HT‐29/B6), respectively, were stably transfected with shRNA targeting tricellulin. Standard molecular biological techniques were applied to analyze expression, localization and function of transfected/regulated TJ proteins. Transepithelial water transport was measured in clones with unchanged expression of other transport‐relevant proteins before and after TJ modification using mannitol or 4‐kDa dextran as an osmotic gradient.After shRNA transfection into MDCK C7 cells, two knockdown (KD) clones with lowest expression of tricellulin were chosen. Tricellulin KD downregulated the expression of occludin and claudin‐4 and ‐8 but upregulated that of claudin‐1, thus roughly balancing expression of the tightening proteins. TER was reduced in both tricellulin KD clones; however, the permeability to 4‐kDa FITC‐dextran was increased only in the clone exhibiting the highest reduction of tricellulin. Nonetheless, water fluxes induced by a gradient of mannitol or 4‐kDa dextran were greatly increased in both tricellulin KD clones compared with their respective controls. In the intermediate‐tight epithelial cell line, HT‐29/B6, again two tricellulin KD clones were chosen. Tricellulin KD upregulated the expression of tightening claudins (‐1, ‐3 and ‐8) and angulin‐1, but also upregulated the expression of the claudin‐2 and AQP‐4, both forming water channels. On the other hand, AQP‐3 was downregulated. Comparable to what was found in MDCK C7 cells, tricellulin KD caused TER to decrease and permeability to 4‐kDa FITC‐dextran to increase compared to controls. Remarkably, water fluxes were not significantly different between the tricellulin KD clones and their controls.We conclude that in MDCK C7 cells, a cell line devoid of claudin‐2‐based water channels, tricellulin increases water permeability at reduced expression. In contrast, in HT‐29/B6 cells, tricellulin KD does not significantly alter transepithelial water transport, most probably concealed by the presence of larger transport rates mediated by other proteins. All in all, the contribution of tricellulin to overall water transport becomes significant if no other major transport pathways for water are present.Support or Funding InformationSupported by DFG GRK 2318 A3

PKA-independent vasopressin signaling in renal collecting duct.

Vasopressin regulates renal water excretion by binding to a Gα s-coupled receptor (V2R) in collecting duct cells, resulting in increased water permeability through regulation of the aquaporin-2 (AQP2) water channel.This action is widely accepted to be associated with cAMP-mediated activation of protein kinase A (PKA). Here, we use phosphoproteomics in collecting duct cells in which PKA has been deleted (CRISPR-Cas9) to identify PKA-independent responses to vasopressin. The results show that V2R-mediated vasopressin signaling is predominantly, but not entirely, PKA-dependent.Upregulated sites in PKA-null cells include Ser256 of AQP2, which is critical to regulation of AQP2 trafficking. In addition, phosphorylation changes in the protein kinases Stk39 (SPAK) and Prkci (an atypical PKC) are consistent with PKA-independent regulation of these protein kinases. Target motif analysis of the phosphopeptides increased in PKA-null cells indicates that vasopressin activates one or more members of the AMPK/SNF1-subfamily of basophilic protein kinases. In vitro phosphorylation assays using recombinant, purified SNF1-subfamily kinases confirmed postulated target specificities.Of interest, measured IBMX-dependent cAMP levels were an order of magnitude higher in PKA-null than in PKA-intact cells, indicative of a PKA-dependent feedback mechanism. Overall, the findings support the conclusion that V2-receptor mediated signaling in collecting duct cells is in part PKA-independent.

Separation of Acetic Acid and Water Using Reverse Osmosis Membranes

Reverse osmosis can potentially be used for separation of acetic acid from waste stream. However, the investigation on the separation of this binary mixture utilizing reverse osmosis is scarce. Thus, this study aims to evaluate the feasibility of lab-synthesized and commercially available reverse osmosis membranes to separate low acetic acid concentration from aqueous mixture. A commercially available AG membrane and three laboratory synthesized polysulfone (PSf) membranes were used in this work. Initial test for water permeation using dead end filtration found that 17.5 wt% PSf has the highest water permeability. As the polymer concentration decreases, the membrane porosity increases which decreases the resistance which enables the penetration of the permeant more easily through the membrane matrix resulting in higher water permeation when 17.5wt% PSf was used. Further modification by interfacial polymerization to form a thin polyamide layer on the porous support was seen to have had improved the membrane affinity towards water resulted in increased of permeation through the membrane matrix. However, the rejection was lower than that of the AG membrane. This indicates that, the increase in water permeation when 17.5wt%PSf was used is due to the high membrane porosity. This is evidence since 17.5wt%PSf has the highest water flux but lower acetic acid rejection compared to the commercial AG membrane. Low rejection of acetic acid when reverse osmosis membrane was applied indicates that other factor such as Donnan effect has to be further considered when synthesizing the membrane.

Nanoclays‐Incorporated Thin‐Film Nanocomposite Membranes for Reverse Osmosis Desalination

AbstractA series of thin‐film nanocomposite (TFN) membranes with incorporation of Laponite nanoclays (NC‐LAP) is prepared and demonstrated for brackish water and seawater desalination. It is the first attempt to use poly(ethylene glycol) 200 (PEG200) assisted Laponite as nanofillers to improve the performance of TFN membranes for reverse osmosis (RO) seawater desalination. The influence of NC‐LAP loading and PEG200 as the dispersant on membrane properties is investigated. An increase in NC‐LAP loading results in an increase in water permeability without sacrificing the salt rejection. At the loading of 0.3 wt%, the TFN membrane shows a water permeability of 2.7 L m−2 h−1 bar−1 (LMH bar−1) and a salt rejection of 98.18% for brackish water desalination at 20 bar and 25 ± 1 °C. This water permeability is 53% higher than the conventional thin‐film composite (TFC) membrane. A steady water flux above 35 LMH is obtained when using seawater as the feed at 50 bar and 25 ± 1 °C. The existence of PEG200 to effectively disperse NC‐LAP nanoparticles is essential to fabricate the NC‐LAP incorporated TFN membranes for brackish water and seawater desalination.

Rab7 involves Vps35 to mediate AQP2 sorting and apical trafficking in collecting duct cells.

Aquaporin-2 (AQP2) is a vasopressin-regulated water channel protein responsible for osmotic water reabsorption by kidney collecting ducts. In response to vasopressin, AQP2 traffics from intracellular vesicles to the apical plasma membrane of collecting duct principal cells, where it increases water permeability and, hence, water reabsorption. Despite continuing efforts, gaps remain in our knowledge of vasopressin-regulated AQP2 trafficking. Here, we studied the functions of two retromer complex proteins, small GTPase Rab7 and vacuolar protein sorting 35 (Vps35), in vasopressin-induced AQP2 trafficking in a collecting duct cell model (mpkCCD cells). We showed that upon vasopressin removal, apical AQP2 returned to Rab5-positive early endosomes before joining Rab11-positive recycling endosomes. In response to vasopressin, Rab11-associated AQP2 trafficked to the apical plasma membrane before Rab5-associated AQP2 did so. Rab7 knockdown resulted in AQP2 accumulation in early endosomes and impaired vasopressin-induced apical AQP2 trafficking. In response to vasopressin, Rab7 transiently colocalized with Rab5, indicative of a role of Rab7 in AQP2 sorting in early endosomes before trafficking to the apical membrane. Rab7-mediated apical AQP2 trafficking in response to vasopressin required GTPase activity. When Vps35 was knocked down, AQP2 accumulated in recycling endosomes under vehicle conditions and did not traffic to the apical plasma membrane in response to vasopressin. We conclude that Rab7 and Vps35 participate in AQP2 sorting in early endosomes under vehicle conditions and apical membrane trafficking in response to vasopressin.

Versatility of hydrophilic and antifouling PVDF ultrafiltration membranes tailored with polyhexanide coated copper oxide nanoparticles

Hydrophilic poly(vinylidene fluoride) (PVDF) nanocomposite ultrafiltration (UF) membranes with excellent antifouling and antibiofouling characteristics are fabricated by employing polyhexanide coated copper oxide nanoparticles (P–CuO NPs). The presence of P–CuO NPs is played a significant role in altering the PVDF membrane matrix and probed by XRD, FTIR, FESEM and contact angle analysis. The PVDF/P–CuO nanocomposite membranes exhibited an outstanding antifouling performance indicated by the superior pure water flux, effective foulant separation and maximum flux recovery ratio during UF experiments as a result of the formation of the hydrophilic and more porous membrane due to the uniform distribution of P–CuO NPs. Particularly, the PVDF/P–CuO-3 membrane showed higher PWF of 152.5 ± 2.4 lm−2h−1 and porosity of 64.5% whereas the lower contact angle of 52.5°. Further, it showed the higher rejection of 99.5 and 98.4% and the flux recovery ratio of 99.5 and 98.5% respectively for BSA and HA foulants, demonstrated its increased water permeation, foulant separation and antifouling behavior. Further, the decent antibacterial activity is showed by the PVDF/P–CuO nanocomposite membranes with the formation of halo-zone around the membrane when exposed to the bacterial medium demonstrated that, by this process an antibacterial water treatment membrane can be developed by simple phase inversion technique with good membrane stability.

Mechanical and Flexural Behavior of High Performance Concrete Containing Nano Silica

This research work presents the role of nano silica (NS) on properties of high performance concrete. This study evaluates the influence of nano silica in three percentages (1%, 2%, 3 %,) by weight of cement. Several tests including mechanical properties and flexural test were performed to understand the influence of nano silica on behavior of concrete. It was determined that Portland cement replaced with 3% by weight with nano silica could accelerate C-S-H gel structure at early stage of hydration. In return this increases water permeability resistance of concrete specimens and acts as filler material that enhances micro structure as well as activator to promote pozzolanic activity and this will pave the way for producing good quality concrete.

Lixivaptan, a New Generation Diuretic, Counteracts Vasopressin-Induced Aquaporin-2 Trafficking and Function in Renal Collecting Duct Cells.

Vasopressin V2 receptor (V2R) antagonists (vaptans) are a new generation of diuretics. Compared with classical diuretics, vaptans promote the excretion of retained body water in disorders in which plasma vasopressin concentrations are inappropriately high for any given plasma osmolality. Under these conditions, an aquaretic drug would be preferable over a conventional diuretic. The clinical efficacy of vaptans is in principle due to impaired vasopressin-regulated water reabsorption via the water channel aquaporin-2 (AQP2). Here, the effect of lixivaptan—a novel selective V2R antagonist—on the vasopressin-cAMP/PKA signaling cascade was investigated in mouse renal collecting duct cells expressing AQP2 (MCD4) and the human V2R. Compared to tolvaptan—a selective V2R antagonist indicated for the treatment of clinically significant hypervolemic and euvolemic hyponatremia—lixivaptan has been predicted to be less likely to cause liver injury. In MCD4 cells, clinically relevant concentrations of lixivaptan (100 nM for 1 h) prevented dDAVP-induced increase of cytosolic cAMP levels and AQP2 phosphorylation at ser-256. Consistent with this finding, real-time fluorescence kinetic measurements demonstrated that lixivaptan prevented dDAVP-induced increase in osmotic water permeability. These data represent the first detailed demonstration of the central role of AQP2 blockade in the aquaretic effect of lixivaptan and suggest that lixivaptan has the potential to become a safe and effective therapy for the treatment of disorders characterized by high plasma vasopressin concentrations and water retention.