Separation of Oil Emulsion with Dynamic Membrane with Surface Layer of Polystyrene

In this paper, we studied the parameters of the process of separation of oil emulsion using a dynamic membrane of ultrafiltration PTFEg-PSd. A polymer membrane with a dynamic layer of polystyrene particles with sizes from 55 to 72 nm was obtained on a substrate of hydrophilic polytetrafluoroethylene (PTFE). The results of scanning electron microscopy showed the formation of a layer of spherical polystyrene particles on the membrane surface. The properties of a dynamic membrane were studied: porosity, moisture capacity, and wettability. After applying the polystyrene layer, an increase in the hydrophobicity of the surface layer of the membrane was established. For membrane separation, a 1% oil emulsion was prepared by dispersing the carbonaceous oil. The retention capacity of membranes for oil products from 1% oil emulsion was 96.4%, with a specific productivity of 113 dm3/m2·h which is not inferior to the performance of a commercial UPM-100 ultrafiltration membrane. Particle sizes of the dispersed phase in a 1% oil emulsion are distributed in the range from 229 to 1476 nm, after separation of the emulsion by a dynamic membrane, oil particles with sizes from 134 to 236 nm were detected in the filtrate, which indicates the removal of the bulk of the dispersed phase from the emulsion by ultrafiltration membranes.

Variation of membrane particle–bound CD133 in cerebrospinal fluid of patients with subarachnoid and intracerebral hemorrhage

OBJECTIVEPrevious studies have demonstrated that human CSF contains membrane particles carrying the stem cell antigenic marker CD133 (prominin-1). Here, the authors analyzed the variation of the amount of these CD133-positive particles in the CSF of patients with subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH).METHODSConsecutive CSF samples from 47 patients with SAH or ICH were compared to 14 healthy control patients. After differential ultracentrifugation of CSF, the membrane particle fraction was separated on gel electrophoresis and its CD133 content was probed by immunoblotting using the mouse monoclonal antibody 80B258 directed against human CD133. The antigen-antibody complexes were detected by chemiluminescence reagents and quantified using human Caco-2 cell extract as positive control with a standardized curve.RESULTSAs compared to healthy controls (6.3 ± 0.5 ng of bound CD133 antibody; n = 14), the amount of membrane particle–associated CD133 immunoreactivities was significantly elevated in patients with SAH and ICH (38.2 ± 6.6 ng and 61.3 ± 11.0 ng [p < 0.001] for SAH [n = 18] and ICH [n = 29], respectively). In both groups the CD133 level dropped during the first 7 days (i.e., day 5–7: SAH group, 24.6 ± 10.1 ng [p = 0.06]; ICH group, 25.0 ± 4.8 ng [p = 0.002]). Whereas changes in the amount of CD133-positive membrane particles between admission and day 5–7 were not associated with clinical outcomes in patients with ICH (modified Rankin Scale [mRS] scores 0–3, −30.9 ± 12.8 ng vs mRS scores 4–6, −21.8 ± 10.7 ng; p = 0.239), persistent elevation of CD133 in patients with SAH was related to impaired functional outcome 3 months after ictus (mRS scores 0–2, −29.9 ± 8.1 ng vs mRS scores 3–6, 7.6 ± 20.3 ng; p = 0.027). These data are expressed as the mean ± standard error of the mean (SEM).CONCLUSIONSLevels of membrane particle–associated CD133 in the CSF of patients with SAH and ICH are significantly increased in comparison to healthy patients, and they decline during the hospital stay. Specifically, the persistent elevation of CD133-positive membrane particles within the first week may represent a possible surrogate measure for impaired functional outcome in patients with SAH.

SUPEROXIDE DISMUTASE LOADED NIOSOMES DELIVERY TO HAIR FOLLICLES: PERMEATION THROUGH SYNTHETIC MEMBRANE AND GUINEA PIG SKIN

Objective: Alopecia aretea is associated with an increase in free radicals causing damage to hair follicles. Superoxide dismutase (SOD) with sufficient penetration through hair follicles, can prevent their death by its strong antioxidant effects. SOD with high molecular weight underwent limitation in follicular delivery. The aim of this study was the improvement of SOD localization into hair follicles. Methods: SOD-loaded niosomes were prepared by thin layer hydration method and were used as a vehicle for delivery to hair follicles through guinea pig skin and the synthetic membrane. Particle size, entrapment efficiency, drug release, and permeability parameters through hairly and non-hairly pig skin compared with a synthetic membrane were evaluated. Results: Niosomes demonstrated 152-325 nm particle size and the SOD burst and sustained release from niosomes were mainly controlled by diffusion and dissolution phenomena. SOD was protected against degradation by niosomes and after six months, enzyme content and activity decreased less than 5%. In comparison with free SOD, niosomes increased SOD affinity to penetration through follicles by interaction with sebum. Likewise, niosome's characters such as type of surfactant, solid lipid/liquid lipid ratio played critical roles on SOD deposition on hair follicles. Conclusion: Synthetic membrane and hairy guinea pig skin demonstrated similar barrier property against free-SOD thereby implying that free SOD does not interact with guinea pig sebum. Niosomes can introduce a suitable carrier for SOD localization into the hair follicles.

Mobility of an axisymmetric particle near an elastic interface

Using a fully analytical theory, we compute the leading-order corrections to the translational, rotational and translation–rotation coupling mobilities of an arbitrary axisymmetric particle immersed in a Newtonian fluid moving near an elastic cell membrane that exhibits resistance towards stretching and bending. The frequency-dependent mobility corrections are expressed as general relations involving separately the particle’s shape-dependent bulk mobility and the shape-independent parameters such as the membrane–particle distance, the particle orientation and the characteristic frequencies associated with shearing and bending of the membrane. This makes the equations applicable to an arbitrary-shaped axisymmetric particle provided that its bulk mobilities are known, either analytically or numerically. For a spheroidal particle, these general relations reduce to simple expressions in terms of the particle’s eccentricity. We find that the corrections to the translation–rotation coupling mobility are primarily determined by bending, whereas shearing manifests itself in a more pronounced way in the rotational mobility. We demonstrate the validity of the analytical approximations by a detailed comparison with boundary integral simulations of a truly extended spheroidal particle. They are found to be in a good agreement over the whole range of applied frequencies.

Abstract 16593: Endocytosis Pathway of Kv1.5 Channels in Atrial Cardiomyocytes

Trafficking of ion channels in cardiomyocytes is a highly dynamic process which is determinant for shaping action potential (AP). In this study, we focused on the dynamic of Kv1.5 channel which carry the atria-specific potassium outward current involved in the repolarisation of the AP. We first investigated the endocytosis pathway for Kv1.5 channels in the atria. High resolution 3-D microscopy revealed that Kv1.5 channels are associated with clathrin vesicles in atrial myocytes but not with caveolin. Electron microscopy showed that vesicles are found both at the lateral sarcolemma and at the intercalated disc. Blockade of the clathrin pathway using sucrose or SiRNA induced an increase in IKur recorded by whole-cell patch-clamp and an accumulation of Kv1.5 channels at the sarcolemma as shown by biotinylation assay. Clathrin blockade also increased fluorescence recovery after photo bleaching of Kv1.5 channels. Altogether, these data show that Kv1.5 channels are internalized through the clathrin pathway. TIRF microscopy approach was used to follow eGFPKv1.5-Kv1.5 channels in living cells and to establish their dynamic in control and clathrin-blocked myocytes. Blockade of the clathrin pathway leads to a global increase of Kv1.5 channels at the membrane. Particle analysis revealed an accumulation of the channels into clusters and their stabilisation at the membrane. Our objective now is to investigate the involvement of the cytoskeleton in Kv1.5 channels endocytosis by using dyes staining tubulin or actin in live cells; and the fate of internalized channels at different time points by co-immunostainings with antibodies directed against the different endosomes. In conclusion, we have identified the clathrin pathway as the internalization route for Kv1.5 channel, in atrial myocytes. The blockade of this pathway modifies Kv1.5 channels dynamic at the membrane. Future work will be conducted to further investigate dynamic and fate of this atria-specific channel. This study should help understanding the constitution of the sub-membrane reservoir of repolarization that we previously described (Balse E., et al. 2009, PNAS).