Round Membrane Research Articles

In Vitro Evaluation of the Permeability of Different Resorbable Xenogeneic Membranes after Collagenolytic Degradation.

In this in vitro study, we compare the penetration of cells through different resorbable collagen membranes, which were collagenolytically degraded over different time periods. Three different resorbable collagen membranes were evaluated, including two non-cross-linked (NCL) membranes—namely, a porcine (NCL-P) and an equine (NCL-E) membrane—and an enzymatically cross-linked porcine (ECL-B) membrane. A special two-chamber model was fabricated, allowing for the placement of separating membranes, and a non-porous polyester membrane was used as a negative control (C), in order to verify the impermeability of the experimental chamber device. Round membrane samples with a diameter of 16 mm were fabricated. Eighteen membranes of each type were punched and placed on polyethylene nets as carriers. The membranes were then biodegraded—each on its carrier—in 12-well polystyrene plates: three samples of each membrane type were degraded for 1.5, 3, 6, or 12 h in 2 mL of a buffered collagenase solution, at 37 °C. For control purposes, three samples of each membrane type were not degraded, but only immersed in buffer solution for 1.5, 3, 6, or 12 h, at 37 °C. Another three samples of each type of membrane were degraded until complete dissolution, in order to determine the full hydroxyproline content for comparison. Liquid-preserved boar semen (containing at least 120 million sperm cells per milliliter) was used to test the cell occlusivity of the degraded membranes. At baseline and initial degradation, all tested membranes were tight, and no penetration was observed with up to 30 min of incubation time (results not shown). After 1.5 h, cells were partially capable of penetrating the NCL-E membrane only. One sample showed leakage, with a sperm volume of 1.7 million cells/mL over all samples. No penetration occurred in the test, NCL-P, and ECL-B groups. After a degradation time of 3 h, the NCL-P and ECL-B membranes remained occlusive to cells. All the membranes and measurements indicated leakage in the NCL-E group. After 6 h, four NCL-P measurements showed the first signs of cell penetration, as boar spermatozoa were detectable in the lower chamber (64 million cells/mL). The ECL-B membranes remained completely cell occlusive. After 12 h, four NCL-P measurements were cell penetration positive (14.6 million cells/mL), while the ECL-B group remained tight and showed no cell penetration. As the findings of our study are well in accordance with the results of several previous animal studies, it can be concluded that the surrogate model is capable of performing rapid and cheap screening of cell occlusivity for different collagen membranes in a very standardized manner. In particular, claims of long degradation resistance can be easily proven and compared. As the boar spermatozoa used in the present report had a size of 9 × 5 μm, smaller bacteria are probably also able to penetrate the leaking membranes; in this regard, our proposed study set-up may provide valuable information, although it must be acknowledged that sperm cells show active mobility and do not only translocate by growth.

Actin Turnover Required for Adhesion-Independent Bleb Migration

Cell migration is critical for many vital processes, such as wound healing, as well as harmful processes, such as cancer metastasis. Experiments have highlighted the diversity in migration strategies employed by cells in physiologically relevant environments. In 3D fibrous matrices and confinement between two surfaces, some cells migrate using round membrane protrusions, called blebs. In bleb-based migration, the role of substrate adhesion is thought to be minimal, and it remains unclear if a cell can migrate without any adhesion complexes. We present a 2D computational fluid-structure model of a cell using cycles of bleb expansion and retraction in a channel with several geometries. The cell model consists of a plasma membrane, an underlying actin cortex, and viscous cytoplasm. Cellular structures are immersed in viscous fluid which permeates them, and the fluid equations are solved using the method of regularized Stokeslets. Simulations show that the cell cannot effectively migrate when the actin cortex is modeled as a purely elastic material. We find that cells do migrate in rigid channels if actin turnover is included with a viscoelastic description for the cortex. Our study highlights the non-trivial relationship between cell rheology and its external environment during migration with cytoplasmic streaming.

Simulating the Architecture of the Actin Cortex during Bleb Nucleation

Blebs are round membrane protrusions involved in important cellular processes such as cell motility, cytokinesis, and apoptosis. Recent studies have focused on the importance of cells that use blebs for cell migration in 3D fibrous environments. Blebs are initiated either by a local delamination of the actin cortex from the membrane due to loss of membrane-cortex adhesion proteins or by a local disruption of the actin cortex. In either case, the cortex degrades in the region of bleb initiation and then reassembles in the bleb. Myosin contractility has been shown to be necessary for bleb formation. It has further been hypothesized that a localized increase in myosin contractility on the cortex results in a rupture of the actin network that can lead to bleb nucleation. A minimal model consisting of actin filaments, myosin molecular motors, and actin cross-linker proteins is used to quantify conditions where holes, or defects, can develop in an initially isotropic cytoskeletal network. The model is simulated using the Cytosim computational platform. Results show that increased myosin fosters actin alignment, while increasing the concentration of actin cross-linkers decreases the pore size of the cytoskeletal network. Holes in the actin network develop at relatively high concentration of both cross-linkers and myosin. Simulation results suggest that a spatially localized defect, representing cortical actin network architecture during bleb nucleation, requires localized actin depolymerization rather than localized distributions of cross-linkers and myosin.

Effects of Astragaloside Ⅳ on exosome secretion and its microRNA-126 expression in human endothelial progenitor cells

Objective: To investigate the effects of Astragaloside Ⅳ on the secretion of exosomes in human endothelial progenitor cells (EPCs) and the expression of microRNA (miRNA)-126 in exosomes. Methods: The umbilical cord blood from one healthy full-term newborn from the Department of Obstetrics and Gynecology of the First Affiliated Hospital of Hunan University of Traditional Chinese Medicine in 2019 was harvested for isolating mononuclear cells by density gradient centrifugation and cultured for 7 days. Morphological observation was performed during this period. Cells of the third passage were collected for identification by CD31 immunomagnetic bead sorting and double fluorescence staining. According to the random number table, the identified EPCs were divided into Astragaloside Ⅳ group and phosphate buffer solution (PBS) group. The cells in Astragaloside Ⅳ group were cultured with Astragaloside Ⅳ in final mass concentration of 100 mg/L for 24 hours, and the cells in PBS group were cultured with the same volume of PBS for 24 hours. After culture, the exosomes from the cell culture supernatant of the two groups were collected, and the expressions of characteristic markers of exosomes CD9, CD63, and CD81 were detected by Western blotting, the morphology of EPC exosomes (EPC-Exos) was observed under transmission electron microscope, and the particle size of EPC-Exos was detected by nanoparticle tracking analysis technique. The concentration of EPC-Exos was determined by dioctyl butyric acid method (the sample number was 3), and the expressions of miRNA-126-3p and miRNA-126-5p related to angiogenesis in EPC-Exos were determined by reverse transcription polymerase chain reaction (the sample number was 3). Data were statistically analyzed with independent sample t test. Results: (1) On the 4th day of culture, the cells began to adhere to the wall, and the multi-forms such as circle, fusiform, and strip appeared at the same time. On the 7th day of culture, the edge of the cells was clear and arranged like a paving stone, the central cells were round, and the surrounding cells were fusiform. (2) CD31 immunomagnetic beads sorting method identification showed that the membrane was stained with green fluorescence and the nucleus was stained with blue fluorescence. Double fluorescence staining method showed that the cells were orange-yellow. The cells were identified as EPCs. (3) After 24 hours of culture, the expressions of CD9, CD63, and CD81 in EPC-Exos were all positive, confirming that EPC-Exos were extracted successfully in this experiment. (4) After 24 hours of culture, the EPC-Exos of the two groups showed round membrane vesicles, and there was no significant difference in morphology. (5) After 24 hours of culture, the particle size of 98.7% EPC-Exos in Astragaloside Ⅳ group was 84.7 to 143.1 nm, and that of 98.0% EPC-Exos in PBS group was 88.7 to 123.5 nm. (6) After 24 hours of culture, the mass concentration of EPC-Exos in Astragaloside Ⅳ group was (310±5) μg/mL, which was significantly higher than (257±5) μg/mL in PBS group, t=13.369, P<0.01. (7) After 24 hours of culture, there were more miRNA-126-3p (t=16.062, P<0.01) and miRNA-126-5p (t=3.252, P<0.05) in EPC-Exos of Astragaloside Ⅳ group than in PBS group. Conclusions: Astragaloside Ⅳ can improve the function of human EPC secretory exosomes, and the secreted exosomes are loaded with miRNA-126.

The biomechanical characteristics of human vestibular aqueduct: a numerical-based model construction and simulation

Vestibular aqueduct is a precise structure embedded in the temporal bone and plays a key role in the physiological function of inner ear by maintaining the endolymphatic circulation and buffering the impact from intracranial pressure. Although the alterations on the morphology or volume of vestibular aqueduct result in variety of diseases, the approaches of evaluating the condition of vestibular aqueduct are still unsatisfing because the pathological sections utilized for the 3D construction model most likely undergoes morphological changes. In this study, the vestibular aqueduct images obtained by CT scanning were processed by finite element method to construct the 3D model. To assess if this numerical model reflects the actual biomechanical properties of vestibular aqueduct, the fluid-solid coupling calculation was applied to simulate the endolymphatic flow in the vestibular aqueduct. By measuring the dynamics of endolymphatic flow, and the pressure and displacement on round membrane under external pressure, we found the numerical 3D model recapitulated the biomechanical characteristics of the real vestibular aqueduct. In summary, our approach of 3D model construction for vestibular aqueduct will provide a powerful method for the research of vestibular aqueduct-related diseases.

Сдвиговый спекл-интерферометр с квадролинзой

The paper proposes a new optical element – Quad lens, which is used as part of a shearing speckle interferometer (sherograph) to provide measurements of stress-strain states of objects simultaneously in two mutually perpendicular directions. Quad lens consists of four identical sections cut from the original round lenses and spaced from each other to form a gap. Quad lens creates four images of an object that are offset relative to the optical axis by a distance that depends on the size of the gaps between the sectors. Phase recovery from a single speckle interferogram is performed using the spatial phase shift method based on the Fourier transform. To increase the contrast of interference bands, an aperture diaphragm with four holes is installed in front of quad lens sectors, and polarizing channel isolation can be used to separate channels and reduce the influence of cross interference. Experimental results of using a speckle interferometer with quad lens for the study of microdeformation of a round membrane are presented.

Modelling of the boundary layer disturbances by localized effect of the round membrane

The spatial development of the flat plate boundary layer disturbances by the hot-wire anemometry is experimentally investigated. Controlled disturbances were introduced into the laminar flow by means of a round membrane located on the surface of the model. The impulse motion of a round membrane leads to the formation of longitudinal localized structures and wave packets in the boundary layer. Wave packets consist of a set of straight and oblique waves, differing in their propagation characteristics. The development of wave packets downstream is consistent with the linear theory of hydrodynamic stability.

Exosomal miR-423-5p mediates the proangiogenic activity of human adipose-derived stem cells by targeting Sufu

BackgroundHuman adipose-derived stem cells (hADSCs) are an important source of cells for regenerative medicine. Evidence of extensive interactions with the surrounding microenvironment has led researchers to focus more on hADSCs as activating agents of regenerative pathways, rather than simply replacing damaged cells. Several studies have found that functional miRNAs can be packaged into exosomes and transferred from donor cells into recipient cells, indicating that transported miRNAs may be a new class of cell-to-cell regulatory species. The aim of the present study was to evaluate whether the exosome-derived miRNAs secreted by hADSCs are capable of influencing angiogenesis, a key step in tissue regeneration.MethodsExosomes were purified from hADSCs followed by the characterization of their phenotype and angiogenic potential in vitro. RNA sequencing was performed to detect the miRNAs that were enriched in the hADSC-derived exosomes. A miRNA-mimic experiment was used to detect the key miRNAs in the proangiogenic activity of hADSC-derived exosomes.ResultsExosomes isolated from hADSCs were characterized as round membrane vesicles with a size of approximately 100 nm and were positive for CD9 and flotillin. The exosomes were internalized by primary human umbilical vein endothelial cells (HUVECs) and stimulated HUVEC proliferation and migration. Remarkably, the exosomes promoted vessel-like formation by HUVECs in a dose-dependent manner, and their maximum activity (10 μg/mL) was comparable with that of 5% FBS. The RNA-seq bioinformatics analysis predicted 1119 gene targets of the top 30 exosomal miRNAs in Gene Ontology (GO) analysis and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis, and the pathway involved in the angiogenesis was among the top KEGG pathways. Moreover, intact miR-423-5p was further demonstrated to be transferred into HUVECs via exosomes and to exert its angiogenic function by targeting Sufu.ConclusionsExosomal miR-423-5p mediated the proangiogenic activity of hADSCs by targeting Sufu, which may contribute to the exploitation of exosomes from hADSCs as a therapeutic tool for regenerative medicine.

The large D membrane paradigm for Einstein-Gauss-Bonnet gravity

We find the equations of motion of membranes dual to the black holes in Einstein-Gauss-Bonnet (EGB) gravity to leading order in 1/D in the large D regime. We also find the metric solutions to the EGB equations to first subleading order in 1/D in terms of membrane variables. We propose a world volume stress tensor for the membrane whose conservation equations are equivalent to the leading order membrane equations. We work out the light quasi-normal mode spectrum of static black holes in EGB gravity from the linearised fluctuations of static, round membranes. Also, the effective equations for stationary black holes and the spectrum of linearised spectrum about black string configurations has been obtained using the membrane equation for EGB gravity. All our results are worked out to linear order in the Gauss-Bonnet parameter.

Computational methods of the superplastic forming duration of a round membrane

The methods for calculating the duration of the superplastic forming of a circular membrane are considered. The results of calculations by analytical formulas are compared with the solution of boundary-value problems of the theory of creep and viscoplasticity found in the medium of the ANSYS software complex. The values of material constants were determined by the data of uniaxial tests and testing formings of the VT6 titanium alloy (Ti–6Al–4V).

Study of heat induced changes in elastic properties of multilayer Mo/ZrSi2 membranes

The paper describes a technique for manufacturing of sub-micron metal membranes based on magnetron deposition of multilayer structures. Tensile stress, biaxial elastic modulus and mechanical strength of 25–50nm thick multilayer Mo/ZrSi2 membranes were measured, and the behavior of these parameters before and after vacuum heating of samples at the level of heat loads up to 1W/cm2 was studied. The elastic properties were obtained from measurements of deformation dependence of the round membranes on the applied pressure differential. A rapid increase in tensile stress of a 25nm thick Mo/ZrSi2 film was observed at a uniform heat load of 0.25W/cm2 which was probably caused by desorption of water molecules from the membrane surface.

Simulation of Surface Oscillation of Ultrasound Sensor Based on Piezoelectric Semiconductor Transducer

In the article theoretical and experimental studies of the surface deformation of piezoelectric sensors are carried out. Round membrane was used as a model of piezoelectric sensors. Experimental studies were conducted on mass-produced sensors and self-made sensor. Good match fluctuations in membrane model with fixed edges real sensors is shown.

Deformation characteristics of aluminum alloys

The paper presents the results of tests to failure of aluminum alloys samples AMg6, AMg6M of various forms. Among the samples there were uniaxial samples, tubular samples in torsion, round membranes designed to hidrolipoclasia, thin cut plates, flat samples with holes and round solid samples with an annular undercut with different radius cuts. The impact of volume stress state, calculated by the method of mathematical simulation of each type samples loading processes, on maximum deformation is discussed.

Retro reproduction: an old imaging technology rewrites the rules of modern embryology.

On a video screen, against a black backdrop, 15 spherical blue-green cells vibrate with a quiet energy. Slowly at first, then faster, they begin to roil and roll. Within the confines of their round membrane cases, they divide, becoming two, three, four cells, then those, in turn, divide to become eight. One splits into two, then pauses, struggling to catch up and spinning off pieces of cellular detritus as it does. Near the top, another, by now many cells rich, hollows out and expands, contracts, expands, contracts. It falls in upon itself and then hatches, pouring out from its shell and ballooning to the side.

Rubberlike membranes at inner pressure

The methods of building experiments of stretching of round membranes by normal pressure has been developed. The experimental data are compared with results of the theoretical research. The nonlinear theory of shells is offered for calculation of elastic membranes.

Novel thin-film composite tri-bore hollow fiber membrane fabrication for forward osmosis

We have developed novel tri-bore thin-film composite (TFC) hollow fiber (HF) membranes for forward osmosis (FO) processes by employing a specially designed tri-bore blossom spinneret. The resultant hollow fibers exhibit evenly-distributed three inner bores with an either round or triangle outer geometry. The newly developed triangle tri-bore hollow fibers have impressive mechanical strength with enhanced permeation properties better than the round ones. Further efforts were given to investigate the effects of glycerol treatment and surfactant concentration during the interfacial polymerization. The new developed TFC tri-bore HF membranes exhibit high water fluxes of 50.5LMH and 11.8LMH with salt leakages as low as 3.5gMH and 2.5gMH, in pressure retarded osmosis (PRO) and FO modes, respectively, when using 2M NaCl as the draw solution and pure water as the feed. The potential of using the triangle TFC membrane for desalination is also investigated. It could reach a water flux of 5.8LMH using a 2M NaCl draw solution and a model seawater solution as the feed. In addition, much more fibers can be packed in a FO module if TFC tri-bore HF membranes have a triangle shape instead of a round one. Theoretical calculations suggest that water output of the module consisting of triangle membranes would double the one comprising round membranes at a 40% packing density. This may enlighten the advantages of triangle tri-bore configuration for FO applications.

Membrane-Type Surface Stress Sensor with Piezoresistive Readout

We present the fabrication and characterization of a membrane-type surface stress sensor (MSS), arranged in arrays for molecular detection in gaseous phase. Made out of SOI substrate, a round membrane with a diameter of 500 μm and a thickness of 2.5 μm is suspended by four sensing beams with integrated p-type piezoresistors, composing a full Wheatstone bridge. The membrane is coated with a thin polymer layer, which reacts with volatile molecules and produces a deflection of the membrane. Accumulated mechanical stress due to the deflection is applied on the sensing beams. MSS were functionalized with cellulose acetate butyrate (CAB) by inkjet spotting. They were characterized in a humidity chamber and showed a fast response time of 1.3 s for a relative humidity transition from 0% to 62%. Moreover, the membrane response is linear with a sensitivity of 87 mV/%RH.

A New Method to Extract Piezoresistive Coefficients in Polysilicon Through Gauges Placed on a MEMS Membrane

This paper presents a new method to evaluate piezoresistive coefficients of polysilicon in the case of N-doping but valid for other types. We measured and simulated the mechanical stress profile distribution along a bossed membrane using several gauges placed along the radial axis of round membranes. Pressure was applied to the membrane. The electromechanical characterizations of the MEMS membrane are in accordance with the simulations and allowed to extract piezoresistive coefficients of the heavily doped polysilicon.

Round Window Membrane in Ménière's Disease

To disclose the histopathologic findings of the thickness of the round window membrane and the presence of false round window membrane in Ménière's disease. Twelve temporal bones from 6 patients with bilateral Ménière's disease, 44 temporal bones from 23 patients with unilateral Ménière's disease, and 102 age-matched normal temporal bones from 56 individuals were histopathologically examined. The thickness of the round window membrane was calculated from 3 different places. In addition, the presence of false round window membrane was investigated in temporal bones with Ménière's disease and compared to the normal temporal bones. A significant difference in the mean thickness of the round window membrane was observed in temporal bones with Ménière's disease compared with normal temporal bones. There was no significant difference in the thickness of the round window membrane between the diseased side and contralateral side in patients with unilateral Ménière's disease. A false round membrane was observed in 9 (25.7%) of 35 Ménière's disease cases and in 5 (4.9%) of 102 normal temporal bones. The thickened nature of the round window membrane and the frequent presence of false round window membrane in patients with Ménière's disease may impede the intratympanic injection treatments. The thickened middle layer of the round window membrane may be related to perilymphatic pressure changes observed in patients with Ménière's disease.

Thickness of the Human Round Membrane in Ménière's Disease

RESULTS: The population mean age was 51.48 15. 44.26% of the patients were males. 58.83% of the patients identify the tinnitus as a pure tone sound. Bilateral tinnitus was found in 79 (43.17%) patients. 54 (29.50%) patients had right tinnitus, and 50 (27.33%) left tinnitus. The associated pathologies were presbycusis (39.34%), sudden deafness (10.93%), acoustic trauma (7.65%), primary hydrops (4.37%), otosclerosis (4.37%), meningioma (1.04%), acoustic neuroma (1.04%), and temporal bone fracture (0.55%). In 4.92% of the patients we could not identify the cause. 25.68% of the patients had normal pure tone and speech audiometry. The equiparation volume media of tinnitus was 6.2db over pure tone threshold. The minimal masking level media was 11.9db pure tone threshold. CONCLUSION: The mean age of the affected population was 51.52 /- 15. The three most common etiologies of tinnitus in this population were presbycusis, deafness and acoustic trauma. Tinnitus was also found in a group of patients with normal hearing. Tinnitus was identified as a pure tone sound in almost a half of the population, and frequently compromised both ears.