Sound waves alter the viability of tobacco cells via changes in cytosolic calcium, membrane integrity, and cell wall composition.

The effect of sound waves (SWs) on plant cells can be considered as important as other mechanical stimuli like touch, wind, rain, and gravity, causing certain responses associated with the downstream signaling pathways on the whole plant. The objective of the present study was to elucidate the response of suspension-cultured tobacco cells (Nicotiana tabacum L. cv Burley 21) to SW at different intensities. The sinusoidal SW (1,000 Hz) was produced through a signal generator, amplified, and beamed to the one layer floating tobacco cells inside a soundproof chamber at intensities of 60, 75, and 90 dB at the plate level for 15, 30, 45, and 60 min. Calibration of the applied SW intensities, accuracy, and uniformity of SW was performed by a sound level meter, and the cells were treated. The effect of SW on tobacco cells was monitored by quantitation of cytosolic calcium, redox status, membrane integrity, wall components, and the activity of wall modifying enzymes. Cytosolic calcium ions increased as a function of sound intensity with a maximum level of 90 dB. Exposure to 90 dB was also accompanied by a significant increase of H2O2 and membrane lipid peroxidation rate but the reduction of total antioxidant and radical scavenging capacities. The increase of wall rigidity in these cells was attributed to an increase in wall-bound phenolic acids and lignin and the activities of phenylalanine ammonia-lyase and covalently bound peroxidase. In comparison, in 60- and 75 dB, radical scavenging capacity increased, and the activity of wall stiffening enzymes reduced, but cell viability showed no changes. The outcome of the current study reveals that the impact of SW on plant cells is started by an increase in cytosolic calcium. However, upon calcium signaling, downstream events, including alteration of H2O2 and cell redox status and the activities of wall modifying enzymes, determined the extent of SW effects on tobacco cells.

Nonlinear dielectric spectroscopy biosensor for SARS-CoV-2 detection.

The coronavirus disease caused by the SARS-CoV-2 virus has affected people worldwide for more than two years. Here we present a new diagnostic method based on nonlinear dielectric spectroscopy to detect the presence of the SARS-CoV-2 virus in swab samples. A known current is injected into the virus sample suspension, and the biomarker is the third harmonic detected in the power spectrum of the recorded signal. Computational modeling of harmonic production supports the hypothesis of ion channels (the E-protein) with nonlinear current-voltage characteristics being present on the virus envelope as a possible origin of harmonics. The developed system is able to distinguish between positive and negative samples with 5-10 dBc (decibels relative to the carrier) higher third harmonic ratios in positive samples, in agreement with the computational estimation. Our early results demonstrate that this method can detect the virus in solution. This is the first time harmonic signatures are used to detect SARS-CoV-2 in swab samples.

Static magnetic field modulates olfactory ensheathing cell's morphology, division, and migration activities, a biophysical approach to regeneration.

The moderate static magnetic fields (SMFs) have been used here as a non-invasive tool to study their manipulative effects on the olfactory ensheathing cells (OECs) activity, growth, morphology, and migration in culture. The OECs are involved in the regeneration of primary olfactory sensory neurons and migration into the central nervous system to repair axons damaged by infection, injury, etc., that play a pivotal role in complementary regenerative medicine. Here, OECs were isolated from the olfactory bulb and cultured to confluence. An in vitro wound healing model was formed and exposed to either parallel (PaSMF) or perpendicular (PeSMF) SMF at intensities of 30, 50, and 70 mT, and cells' morphology, podia formation, proliferation, and migration were studied by time-lapse recording. The SMFs were not cytotoxic at the intensity and exposure time applied here. The exposure of cells to 70 mT PaSMF and PeSMF increased the formation of lamellipodia and filopodia, cell migration speed, and direction of the scratch forefront cells, significantly. Treatment of cells with 70 mT PaSMF and PeSMF increased cell divisions, while 30 mT PaSMF decreased it. SMF effects on OECs division, motility, migratory direction, and velocity indicate its effect on various aspects of cell physiology and signaling at atomic and molecular levels, and have a role in tissue regeneration that involves microtubules and actin filaments formation and rearrangements. Thus, the exposure of OECs with moderate SMF might be considered a promising noninvasive approach to remotely manipulate normal and stem cell activities for therapeutic regenerative purposes in various tissues including the central nervous system.

Osteoconductive and electroactive carbon nanofibers/hydroxyapatite nanocomposite tailored for bone tissue engineering: in vitro and in vivo studies.

In this study, we aimed to fabricate osteoconductive electrospun carbon nanofibers (CNFs) decorated with hydroxyapatite (HA) crystal to be used as the bone tissue engineering scaffold in the animal model. CNFs were derived from electrospun polyacrylonitrile (PAN) nanofibers via heat treatment and the carbonized nanofibers were mineralized by a biomimetic approach. The growth of HA crystals was confirmed using XRD, FTIR, and EDAX analysis techniques. The mineralization process turned the hydrophobic CNFs (WCA: 133.5° ± 0.6°) to hydrophilic CNFs/HA nanocomposite (WCA 15.3° ± 1°). The in vitro assessments revealed that the fabricated 24M-CNFs nanocomposite was biocompatible. The osteoconductive characteristics of CNFs/HA nanocomposite promoted in vivo bone formation in the rat's femur defect site, significantly, observed by computed tomography (CT) scan images and histological evaluation. Moreover, the histomorphometric analysis showed the highest new bone formation (61.3 ± 4.2%) in the M-CNFs treated group, which was significantly higher than the negative control group (the defect without treatment) (< 0.05). To sum up, the results implied that the fabricated CNFs/HA nanocomposite could be considered as the promising bone healing material.

Application of a static magnetic field as a complementary aid to healing in an in vitro wound model.

OBJECTIVE: Static magnetic field (SMF) has long been used as a therapeutic means, though its effects on the activity of cells and the mechanism(s) involved remain unknown. The purpose of this study is to determine the effect of a moderate-intensity SMF on the activity, growth and migration of mouse embryonic fibroblast (NIH 3T3), aiming to mimic wound healing and to study it in real time. METHOD: A cell-free area (a scratch with a 200-500µm width) was formed in NIH 3T3 cultured cells and used as a wound model. The effects of a SMF (10, 50, 80 and 100mT) on the survival rate (MTT assay), integrity of cell membranes (lactate dehydrogenase (LDH) assay), the morphology of the cell (circularity, number and length of filopodia), cell orientation, and migration (speed, direction, rate) were studied as a function of the incubation time in a time-lapse manner. RESULTS: The exposure of cells to SMF at all intensities had no cytotoxic effect, as revealed by the MTT assay. The integrity of the membranes of the SMF-treated cells studied by the LDH assay test showed no effects. The structure of the membrane at the leading edge of the cells changed and showed several filopodia extended parallel to the field direction. The exposure to the SMF elongated the cells and decreased their circularity at SMF 10mT. The migration of the cells from one edge of the gap towards the other was affected by the applied SMF. The maximum and minimum effects were monitored at 80mT and 10mT, respectively. Analysis of cell migration revealed an average directness of 0.73, 0.66, 0.78, 0.78 and 0.69 under SMF 10, 50, 80, 100mT and control, respectively. CONCLUSION: The morphological and functional changes of the cells in the presence of SMF revealed particular effects on the membrane and cytoskeleton. Cells were affected by physicochemical changes caused by the applied SMF, though the extent of the incurred effects was not a linear function of the field intensity. This low cost, non-invasive approach can be used as a magneto-manipulative means to tailor a practical, independent or complementary means of manipulating the activities of cells and tissues for clinical purposes.

Clinical Cell Therapy Guidelines for Neurorestoration (IANR/CANR 2017).

Cell therapy has been shown to be a key clinical therapeutic option for central nervous system diseases or damage. Standardization of clinical cell therapy procedures is an important task for professional associations devoted to cell therapy. The Chinese Branch of the International Association of Neurorestoratology (IANR) completed the first set of guidelines governing the clinical application of neurorestoration in 2011. The IANR and the Chinese Association of Neurorestoratology (CANR) collaborated to propose the current version "Clinical Cell Therapy Guidelines for Neurorestoration (IANR/CANR 2017)". The IANR council board members and CANR committee members approved this proposal on September 1, 2016, and recommend it to clinical practitioners of cellular therapy. These guidelines include items of cell type nomenclature, cell quality control, minimal suggested cell doses, patient-informed consent, indications for undergoing cell therapy, contraindications for undergoing cell therapy, documentation of procedure and therapy, safety evaluation, efficacy evaluation, policy of repeated treatments, do not charge patients for unproven therapies, basic principles of cell therapy, and publishing responsibility.

Green synthesis of degradable conductive thermosensitive oligopyrrole/chitosan hydrogel intended for cartilage tissue engineering.

Electroactive scaffolds containing conductive polymers can promote tissue repair and regeneration. However, these polymers are non-degradable and cannot be removed from body. To overcome this limitation of conductive polymers, we developed a novel injectable electroactive hydrogel containing pyrrole oligomers which possessed the unique properties of being both electrically conductive and biodegradable. First, pyrrole oligomers were synthesized via chemical polymerization and were found to be amorphous with a non-globular morphology. Then, three different compositions of injectable chitosan/beta glycerophosphate hydrogels containing different concentrations of pyrrole oligomers were synthesized and characterized for chemical structure, morphology, conductivity, swelling ratio, In vitro biodegradation and gelation time. An increase in oligopyrrole content resulted in decreased pore size, and increased gelation time, swelling ratio, conductivity and degradation time. Among all the hydrogel compositions, the sample with pyrrole oligomer:chitosan ratio of 0.1 (w/w) showed the most prominent biodegradability, biocompatibility, electro-activity, swelling ratio and pore size values and was chosen as the optimal electroactive hydrogel composition in this work.

Effects of static magnetic fields on the structure, polymerization, and bioelectric of tubulin assemblies.

Due to widespread exposure of human being to various sources of static magnetic fields (SMF), their effect on the spatial and temporal status of structure, arrangement, and polymerization of tubulin was studied at the molecular level. The intrinsic fluorescence intensity of tubulin was increased by SMF, indicating the repositioning of tryptophan and tyrosine residues. Circular Dichroism spectroscopy revealed variations in the ratios of alpha helix, beta, and random coil structures of tubulin as a result of exposure to SMF at 100, 200, and 300 mT. Transmission Electron microscopy of microtubules showed breaches and curvatures whose risk of occurrence increased as a function of field strength. Dynamic light scattering revealed an increase in the surface potential of tubulin aggregates exposed to SMF. The rate and extent of polymerization increased by 9.8 and 33.8%, at 100 and 300 mT, respectively, but decreased by 36.16% at 200 mT. The conductivity of polymerized tubulin increased in the presence of 100 and 300 mT SMF but remained the same as the control at 200 mT. The analysis of flexible amino acids along the sequence of tubulin revealed higher SMF susceptibility in the helical electron conduction pathway set through histidines rather than the vertical electron conduction pathway formed by tryptophan residues. The results reveal structural and functional effects of SMF on tubulin assemblies and microtubules that can be considered as a potential means to address the safety issues and for manipulation of bioelectrical characteristics of cytosol, intracellular trafficking and thus, the living status of cells, remotely.

Impact of heat shock step on bacterial transformation efficiency.

CaCl2 treatment followed by heat shock is the most common method for artificial transformation. Here, the cells were transformed using CaCl2 treatment either with heat shock (standard protocol) or without heat shock (lab protocol) to comprehend the difference in transformation efficiency. The BL21 strain of Escherichia coli (E. coli) was being susceptible using CaCl2 treatment. Some Cells were kept at -80 oC while the others were kept at 4 ˚C. Afterwards the susceptible cells were transformed using either standard or lab protocol. The transformation efficiency between cells experienced heat shock and those were not influenced by heat shock was almost the same. Moreover, regardless of transformation protocol, the cells kept at 4 ˚C were transformed more efficiently in compared to those were kept at -80 oC.

Interaction of polyethylene glycol (PEG) with the membrane-binding domains following spinal cord injury (SCI): introduction of a mechanism for SCI repair.

Lipid-binding domains regulate positioning of the membrane proteins via specific interactions with phospholipid's head groups. Spinal cord injury (SCI) diminishes the integrity of neural fiber membranes at nanoscopic level. In cases that the ruptured zone size is beyond the natural resealing ability, there is a need for reinforcing factors such as polymers (e.g. Polyethylene glycol) to patch the dismantled axoplasm. Certain conserved sequential and structural patterns of interacting residues specifically bind to PEGs. It is also found that PEG600, PEG400 and PEG200 share the strongest interaction with the lipid-binding domains even more successful than phospholipid head groups. The alpha helix structure composed of hydrophobic, neutral and acidic residues prepares an opportunity for PEG400 to play an amphipathic role in the interaction with injured membrane. This in-silico study introduces a mechanism for PEG restorative ability at the molecular level. It is believed that PEG400 interrelates the injured membrane to their underneath axoplasm while retaining the integrity of ruptured membrane via interaction with ENTH domains of membrane proteins. This privilege of PEG400 in treating injured membrane must be considered in designing of polymeric biomaterials that are introduced for SCI repair.

Novel aspects of spinal cord evoked potentials (SCEPs) in the evaluation of dorso-ventral and lateral mechanical impacts on the spinal cord.

OBJECTIVES: The aim of the current study was to mimic mechanical impacts on the spinal cord by manifesting the effects of dorsoventral (DVMP) and lateral (LMP) mechanical pressure on neural activity to address points to be considered during surgery for different purposes, including spinal cord decompression. APPROACHES: Spinal cords of anesthetized rats were compressed at T13. Different characteristics of axons, including vulnerability, excitability, and conduction velocity (CV), in response to promptness, severity, and duration of pressure were assessed by spinal cord evoked potentials (SCEPs). Real-time SCEPs recorded at L4-5 revealed N1, N2, and N3 peaks that were used to represent the activity of injured sensory afferents, interneurons, and MN fibers. The averaged SCEP recordings were fitted by trust-region algorithm to find the equivalent Gaussian and polynomial equations. MAIN RESULTS: The pyramidal and extrapyramidal pathways possessed CVs of 3-11 and 16-80 m s(-1), respectively. DVMP decreased the excitability of myelinated neural fibers in antidromic and orthodromic pathways. The excitability of fibers in extrapyramidal and pyramidal pathways of lateral corticospinal (LCS) and anterior corticospinal (ACS) tracts decreased following LMP. A significant drop in the amplitude of N3 and its conduction velocity (CV) revealed higher susceptibility of less-myelinated fibers to both DVMP and LMP. The best parametric fitting model for triplet healthy spinal cord CAP was a six-term Gaussian equation (G6) that fell into a five-term equation (G5) at the complete compression stage. SIGNIFICANCE: The spinal cord is more susceptible to dorsoventral than lateral mechanical pressures, and this should be considered in spinal cord operations. SCEPs have shown promising capabilities for evaluating the severity of SCI and thus can be applied for diagnostic or prognostic intraoperative monitoring (IOM).

Impact of inhomogeneous static magnetic field (31.7-232.0 mT) exposure on human neuroblastoma SH-SY5Y cells during cisplatin administration.

Beneficial or adverse effects of Static Magnetic Fields (SMFs) are a large concern for the scientific community. In particular, the effect of SMF exposure during anticancer therapies still needs to be fully elucidated. Here, we evaluate the effects of SMF at induction levels that cisPt-treated cancer patients experience during the imaging process conducted in Low field (200-500 mT), Open field (300-700 mT) and/or inhomogeneous High field (1.5-3 T) Magnetic Resonance Imaging (MRI) machines. Human adrenergic neuroblastoma SH-SY5Y cells treated with 0.1 µM cisPt (i.e. the lowest concentration capable of inducing apoptosis) were exposed to SMF and their response was studied in vitro. Exposure of 0.1 µM cisPt-treated cells to SMF for 2 h decreased cell viability (30%) and caused overexpression of the apoptosis-related cleaved caspase-3 protein (46%). Furthermore, increase in ROS (Reactive Oxygen Species) production (23%) and reduction in the number of mitochondria vs controls were seen. The sole exposure of SMF for up to 24 h had no effect on cell viability but increased ROS production and modified cellular shape. On the other hand, the toxicity of cisPt was significantly prevented during 24 h exposure to SMF as shown by the levels of cell viability, cleaved caspase-3 and ROS production. In conclusion, due to the cytoprotective effect of 31.7-232.0 mT SMF on low-cisPt-concentration-treated SH-SY5Y cells, our data suggest that exposure to various sources of SMF in cancer patients under a cisPt regimen should be strictly controlled.

Application of OmpF nanochannel forming protein in polynucleotide sequence recognition.

Recognition of the sequence of human genome sequence is vital to address malfunctions occurring at molecular, cellular and tissue levels and requires a great deal of time, cost and efforts. Thus, various synthetic and natural pores were considered to fabricate high-throughput systems capable to fulfill the task in an efficient manner. Here, voltage gating OmpF nanochannel, whose structure is known at an atomic level, was used to recognize and differentiate between polynucleotide primers through voltage clamp technique. Our results showed that poly(T) occasionally blocked the channel at both polarities, while poly(C) and poly(G) obstructed it only at positive polarity. The channel was blocked at potential differences of as low as 80 mV in the presence of poly(T). The conductance of channel decreased in the presence of poly(C) and poly(G) by 61 and 5% respectively. Analysis of the number of events showed that poly(T) caused more closing events at higher voltages, while poly(G) and poly(C) induced it at lower voltages. Application of the hazard function as a statistical parameter and analysis of event closing times in various voltages demonstrated the most efficient differentiation at 60 mV. The results of practical and theoretical approaches presented here show that OmpF porin channel possesses the structural and dynamic characteristics required to be considered as a biosensor capable for continuous polynucleotide sequencing.

Efficient repairing effect of PEG based tri-block copolymer on mechanically damaged PC12 cells and isolated spinal cord.

Membrane sealing effects of polymersomes made of tri-block copolymer, PEG-co-FA/SC-co-PEG, (PFSP) were studied on isolated spinal cord strips, PC12 cell lines and artificial bilayer following mechanical impact implemented by aneurism clip, sonication and electric shock, respectively. The homogeneity and size of PFSP, membrane permeability and cell viability were assessed by dynamic light scattering, LDH release and MTT assays. According to the results, the biocompatible, physico-chemical, size, surface charge and amphipathic nature of PFSP polymersome makes it an ideal macromolecule to rapidly reseal damaged membranes of cells in injured spinal cord as well as in culture medium. Compound action potentials recorded from intentionally damaged spinal cord strips incubated with PFSP showed restoration of neural excitability by 82.24 % and conduction velocity by 96.72 % after 5 min that monitored in real time. Thus, they triggered efficient instant and sustained sealing of membrane and reactivation of temporarily inactivated axons. Treatment of ultrasonically damaged PC12 cells by PFSP caused efficient cell membrane repair and led to their increased viability. The optimum effects of PFSP on stabilization and impermeabilizing of the lipid bilayer occurred at the same concentrations applied to the damaged cells and spinal cord fibers and was approved by restoration of membrane conductance and calcein release manifested by NanoDrop technique. The unique physico-chemical characteristics of novel polymersomes introduced here, make them capable to reorganize membrane lipid molecules, reseal the breaches and restore the hydrophobic insulation in spinal cord damaged cells. Thus, they might be considered in the clinical treatment of SCI at early stages.

Mechanical characteristics of electrospun aligned PCL/PLLA nanofibrous scaffolds conduct cell differentiation in human bladder tissue engineering.

Certain features of electrospun PCL/PLLA nanofibrous scaffolds such as thickness, cross section density, strength, and elastisity can be tailored to mimic the native microenvironment required for bladder tissue engineering. In this study the differentiation of human bladder smooth muscle cells (hBSMCs) cultured on electrospun scaffolds was studied. The scaffolds of aligned PCL/PLLA fibrous with a thickness of about 100 nm, used to implement different mechanical stimulation. Longitudinal (0.7 MPa) and traverse (0.02 MPa) Young's modulus of the constructed hybrid aligned PCL/PLLA scaffolds showed anisotropic orientation of the electrospun fibers. Based on the elastic limit strain, the aligned scaffolds were selected and SEM micrographs used to reveal the outcomes. The application of mechanical forces on seeded scaffolds at physiologic and 0.1 Hz frequencies played crucial role in the differentiation of hBSMCs. Scaffolds were stretched to 2% below the deformation point and the effects of the physiologic and 0.1 Hz stretching frequencies on hBSMCs seeded scaffolds were investigated at gene transcription level. The application of 0.1 Hz stretching forces increased transcriptions of collagen type I/III/IV, elastin, alpha-smooth muscle actin and caldesmon, while at physiologic rate, all of the mentioned genes were down-regulated. On the other hand, exposing human bladder urothelial cells (hBUCs) to 0.1 Hz stretching frequencies promoted transcription of certain functional markers including cytokeratin 8 and 18. We found that mechanical forces with different frequencies exert different regulatory effects on extracellular matrices and contractile genes in hBSMCs and hBUCs that should be considered in tissue engineering strategies.

The neuroprotective ability of polyethylene glycol is affected by temperature in ex vivo spinal cord injury model.

Immediate membrane sealing after spinal cord injury (SCI) can prevent further degradation and result in ultimate functional recovery. It has been reported that polyethylene glycol (PEG) can repair membrane damage caused by mechanical insults to the spinal cord. Furthermore, membrane fluidity and its sealing process vary at different temperatures. Here, we have assessed the possible synergistic effects of PEG and temperature on the repair of neural membranes in an SCI model. The effects of PEGs (400, 1,000 and 2,000 Da) were studied at different temperatures (25, 37 and 40 °C) by means of compound action potential (CAP) recovery and a lactate dehydrogenase (LDH) assay. Isolated spinal cords were mounted in a double sucrose gap chamber, where the amplitude and area of CAPs were recorded after implementing injury, in the presence and absence of PEG. Moreover, the LDH assay was used to assess the effects of PEG on membrane resealing. Data showed that the least CAP recovery occurred at 25 °C, followed by 37 and 40 °C, in all treated groups. Moreover, maximum CAP amplitude recovery, 65.46 ± 5.04 %, was monitored in the presence of PEG400 at 40 °C, followed by 41.49 ± 2.41 % in PEG1000 and 37.36 ± 1.62 % in PEG2000. Furthermore, raising the temperature from 37 to 40 °C significantly increased CAP recovery in the PEG2000 group. Similar recovery patterns were obtained by CAP area measurements and LDH assay. The results suggest that application of low-molecular weight PEG (PEG400) in mild hyperthermia conditions (40 °C) provides the optimum condition for membrane sealing in SCI model.

Protective effect of low molecular weight polyethylene glycol on the repair of experimentally damaged neural membranes in rat's spinal cord.

OBJECTIVES: Membrane disruption is one of the main factors that cause axonal damage and functional deficits manifested in spinal cord injury (SCI). In this study, we used polyethylene glycol (PEG) to induce immediate membrane sealing and to promote functional recovery after SCI. METHODS: The effects of PEG (200-2000 Da) on the damaged membrane were monitored by means of spinal cord evoked potentials (SCEPs) in an SCI model in rats. In a parallel study, membranes of neural cells were mechanically damaged in culture by ultrasound waves (20 kHz) and the repairing effects of PEGs were examined afterwards at the single cell level. RESULTS: Analysis of SCEPs showed that the smaller the PEG, the higher was the ultimate recovery of SCEP (i.e., 200 Da caused 49.5% and 2000 Da up to 16.3%). The rate of recovery was maximum with a polynomial trend, when the damaged spinal cord was treated with PEG200 for 25 minutes. The analysis of survival rate of mechanically damaged cells in culture, measured by MTT assay, showed that again smaller PEGs, caused higher membrane sealing rate; 77.8±3.5 for PEG400 (20% w/w) vs 32.1±6.9 for PEG2000 (20% w/w). The large ones (PEG1000 and 2000) that presented minor repair at low concentration, showed no significant sealing effects at high concentrations (>50%). CONCLUSION: Our studies showed that the application of low molecular weight PEGs, (<50% w/w) can be considered as one of the effective early treatments for SCI.

Effective combination of hydrostatic pressure and aligned nanofibrous scaffolds on human bladder smooth muscle cells: implication for bladder tissue engineering.

Bladder tissue engineering has been the focus of many studies due to its highly therapeutic potential. In this regard many aspects such as biochemical and biomechanical factors need to be studied extensively. Mechanical stimulations such as hydrostatic pressure and topology of the matrices are critical features which affect the normal functions of cells involved in bladder regeneration. In this study, hydrostatic pressure (10 cm H(2)O) and stretch forces were exerted on human bladder smooth muscle cells (hBSMCs) seeded on aligned nanofibrous polycaprolactone/PLLA scaffolds, and the alterations in gene and protein expressions were studied. The gene transcription patterns for collagen type I, III, IV, elastin, α-SMA, calponin and caldesmon were monitored on days 3 and 5 quantitatively. Changes in the expressions of α-SMA, desmin, collagen type I and III were quantified by Enzyme-linked immuno-sorbent assay. The scaffolds were characterized using scanning electron microscope, contact angle measurement and tensile testing. The positive effect of mechanical forces on the functional improvement of the engineered tissue was supported by translational down-regulation of α-SMA and VWF, up-regulation of desmin and improvement of collagen type III:I ratio. Altogether, our study reveals that proper hydrostatic pressure in combination with appropriate surface stimulation on hBSMCs causes a tissue-specific phenotype that needs to be considered in bladder tissue engineering.

Effects of trehalose and sorbitol on the activity and structure of Pseudomonas cepacia lipase: spectroscopic insight.

The stability of enzymes with no reduction in their catalytic activity still remains a critical issue in industrial applications. Naturally occurring osmolytes are commonly used as protein stabilizers. In this study we have investigated the effects of sorbitol and trehalose on the structural stability and activity of Pseudomonas cepacia lipase (PCL), using UV-visible, circular dichroism (CD) and fluorescence spectroscopy. Surface plasmon resonance (SPR) technique was used to trace changes in the refractive index and dielectric constant of the environment. The results revealed that catalytic activity and intrinsic fluorescence intensity of PCL increased in the presence of both osmolytes. Far-UV CD spectra indicated that the protein has undergone some conformational changes upon interacting with these osmolytes. Increasing the concentration of sorbitol led to changes in the refractive index and consequently the dielectric constant of environment; whereas in the case of trehalose, such changes were not significant. Unfavorable interactions of trehalose with protein surface induced higher preferential exclusion from the enzyme-water interface than that of sorbitol. Results of this report could give further insights about the stabilization mechanism of osmolytes.

The effect of 2.1 T static magnetic field on astrocyte viability and morphology.

The viability and a number of morphological properties of in situ astrocytes of rat spinal cord cultures including changes in surface area and migration of both cell body and nucleus were investigated at magnetic field intensities comparable to those currently used for magnetic resonance imaging. Viability of rat spinal astrocytes was studied after up to 72 hours of 2.1T static magnetic field exposure. Surface areas and two-dimensional centroids of both soma and nucleus after 2 hours of magnetic field exposure were determined and compared with those of the same cells before magnetic field exposure. Cell membrane ruffling was quantified using fractal analysis. Viability of astrocytes remained unchanged at 4, 16, 24, 48 and 72 hours. The mean soma area before and after 2 hours of field exposure was 6450 microm(2) and 6299 microm(2), respectively, whereas the values for nuclear area were 185.6 microm(2) and 185.7 microm(2). The mean displacement of the centroid of soma parallel and perpendicular to the magnetic field direction was 1.07 microm and 0.78 microm, respectively. The corresponding quantities for nuclei were 0.29 microm and -2.00 microm. None of these changes were statistically significant. No membrane protrusion was observed by fractal analysis. In conclusion, strong static magnetic field at 2.1 T does not significantly affect the viability and morphological properties of rat astrocytes.