Round window membrane and delivery of biologically active agents into the cochlea

Establishing efficient methods for local administration of drugs to the inner ear has great clinical relevance for the management of inner ear disorders. However, the administration route remains a critical issue. The most feasible approach for a non invasive drug delivery to the inner ear is application of medication to the middle ear cavity on the promise that it will diffuse through the thin round window membrane (RWM) separating the inner ear from the middle ear cavity. Gene therapy represents a promising future in otology and offers an exciting therapeutic alternative as it could be used in prevention or management of cochlear disorders. Also for a gene therapy approach, RWM application seems most feasible administration route. Exploring and characterizing the RWM route of administration is thus a fundamentally important area of research for the development of future treatment of inner ear disorders. The objectives of the thesis were to evaluate the efficacy of two drug and gene delivering vehicles to the inner ear, sodium hyaluronate (HYA) and chitosans, which can be applied to the cochlea. Ultimate aim is to establish an efficient drug delivery system and gene transfection for the inner ear. HYA and chitosans loaded with the ototoxic drug neomycin as tracer for drug release have been instilled into the middle ear of the guinea pigs. Effects on RWM and cochlear hair cells were evaluated after a single instillation of HYA (day 7 and 28), chitosans and saline solution (day 7). The hearing organ was analysed for hair cell loss and the thickness and ultrastructural properties of the RWM were analysed by light and transmission electron microscopy. The in vitro transfection efficiency of chitosan was tested by exposing organotypic cultures of the organ of Corti, prepared from postnatal day 2 rats, to chitosan carrying plasmid DNA (pDNA). The in vivo transfection efficiency was tested at one day or seven days after infusing chitosan/pDNA polyplexes with the use of osmotic pumps into the cochlea of adult guinea pigs. Tissue analysis was made by immunohistochemsitry and RT-PCR. HYA and chitosans, especially glycosylated derivative, are safe vehicles that can be used for drug transport into the inner ear through the RWM. Both vehicles successfully released the loaded neomycin, which exerted toxic effects on cochlear hair cells in a degree depending on the concentrations used. The vehicles per se had no noxious effect on the cochlear hair cells but they provoked a comparable effect on the thickness and morphology of the RWM. The thickness of the RWM returned to normal 4 weeks after exposure to HYA. Chitosan as a carrier for inner ear transfection, was associated with inconsistent transfection in vitro and in vivo . The importance of the RWM as a portal for local therapy of inner ear disorders is highlighted in this thesis by focusing on efficiency and effects of the vehicles, applied to the RWM for delivering biologically active agents into the cochlea. The difficulties and variability associated with applying substances to the RWM were explored. The results of this thesis add new knowledge concerning mechanisms of passage of biologically active agents through the RWM and may help us to better understand the role of RWM in the local cochlear therapy and problems of local treatment of inner ear diseases

Optimization of Vehicle-to-Grid Scheduling in Constrained Parking Lots

An automatic Vehicle-to-Grid (V2G) technology can contribute to the utility grid. V2G technology has drawn great interest in the recent years. Success of the sophisticated automatic V2G research depends on efficient scheduling of gridable vehicles in constrained parking lots. Parking lots have constraints of space and current limits for V2G. However, V2G can reduce dependencies on small expensive units in the existing power systems as energy storage that can decrease running costs. It can efficiently manage load fluctuation, peak load; however, it increases spinning reserves and reliability. As number of gridable vehicles in V2G is much higher than small units of existing systems, unit commitment (UC) with V2G is more complex than basic UC for only thermal units. Particle swarm optimization (PSO) is proposed to solve the V2G, as PSO has been demonstrated to reliably and accurately solve complex constrained optimization problems easily and quickly without any dimension limitation and physical computer memory limit. In the proposed model, binary PSO optimizes the on/off states of power generating units easily. Vehicles are presented by signed integer number instead of 0/1 to reduce the dimension of the problem. Typical discrete version of PSO has less balance between local and global searching abilities to optimize the number of charging/discharging gridable vehicles in the constrained system. In the same model, balanced PSO is proposed to optimize the V2G part in the constrained parking lots. Finally, results show a considerable amount of profit for using proper scheduling of gridable vehicles in constrained parking lots

Economic Load Dispatch Using Bacterial Foraging Technique with Particle Swarm Optimization Biased Evolution

This paper presents a novel modified bacterial foraging technique (BFT) to solve economic load dispatch (ELD) problems. BFT is already used for optimization problems, and performance of basic BFT for small problems with moderate dimension and searching space is satisfactory. Search space and complexity grow exponentially in scalable ELD problems, and the basic BFT is not suitable to solve the high dimensional ELD problems, as cells move randomly in basic BFT, and swarming is not sufficiently achieved by cell-to-cell attraction and repelling effects for ELD. However, chemotaxis, swimming, reproduction and elimination-dispersal steps of BFT are very promising. On the other hand, particles move toward promising locations depending on best values from memory and knowledge in particle swarm optimization (PSO). Therefore, best cell (or particle) biased velocity (vector) is added to the random velocity of BFT to reduce randomness in movement (evolution) and to increase swarming in the proposed method to solve ELD. Finally, a data set from a benchmark system is used to show the effectiveness of the proposed method and the results are compared with other methods

An Electron‐Rich Calix[4]arene‐Based Receptor with Unprecedented Binding Affinity for Nitric Oxide

Calixarenes have found widespread application as building blocks for the design and synthesis of functional materials in host–guest chemistry. The ongoing desire to develop a detailed understanding of the nature of NO bonding to multichromophoric π‐stacked assemblies led us to develop an electron‐rich methoxy derivative of calix[4]arene (3), which we show exists as a single conformer in solution at ambient temperature. Here, we examine the redox properties of this derivative, generate its cation radical (3+.) using robust chemical oxidants, and determine the relative efficacy of its NO binding in comparison with model calixarenes. We find that 3/3+. is a remarkable receptor for NO+/NO, with unprecedented binding efficacy. The availability of precise experimental structures of this calixarene derivative and its NO complex, obtained by X‐ray crystallography, is critically important both for developing novel functional NO biosensors, and understanding the role of stacked aromatic donors in efficient NO binding, which may have relevance to biological NO transport

Improving Performance of the SMD Solvation Model: Bondi Radii Improve Predicted Aqueous Solvation Free Energies of Ions and pK\u3csub\u3ea\u3c/sub\u3e Values of Thiols

Calculation of the solvation free energy of ionic molecules is the principal source of errors in the quantum chemical evaluation of pKa values using implicit polarizable continuum solvent models. One of the important parameters affecting the performance of these models is the choice of atomic radii. Here, we assess the performance of the solvation model based on density (SMD) implicit solvation model employing SMD default radii (SMD) and Bondi radii (SMD-B), a set of empirical atomic radii developed based on the crystallographic data. For a set of 112 ions (60 anions and 52 cations), the SMD-B model showed lower mean unsigned error (MUE) for predicted aqueous solvation free energies (4.0 kcal/mol for anions and 2.4 kcal/mol for cations) compared to the standard SMD model (MUE of 5.0 kcal/mol for anions and 2.9 kcal/mol for cations). In particular, usage of Bondi radii improves the aqueous solvation energies of sulfur-containing ions by \u3e5 kcal/mol compared to the SMD default radii. Indeed, for a set of 45 thiols, the SMD-B model was found to dramatically improve the predicted pKa values, with ∼1 pKa unit mean deviation from the experimental values, compared to ∼7 pKa units mean deviation for the SMD model with the default radii. These findings highlight the importance of the choice of atomic radii on the performance of the implicit solvation models

Slow Release of Ions from Internalized Silver Nanoparticles Modifies the Epidermal Growth Factor Signaling Response

Due to their distinctive physiochemical properties, including a robust antibacterial activity and plasmonic capability, hundreds of consumer and medical products contain colloidal silver nanoparticles (AgNPs). However, even at sub-toxic dosages, AgNPs are able to disrupt cell functionality, through a yet unknown mechanism. Moreover, internalized AgNPs have the potential to prolong this disruption, even after the removal of excess particles. In the present study, we evaluated the impact, mechanism of action, and continual effects of 50 nm AgNP exposure on epidermal growth factor (EGF) signal transduction within a human keratinocyte (HaCaT) cell line. After AgNP expose, EGF signaling was initially obstructed due to the dissolution of particles into silver ions. However, at longer durations, the internalized AgNPs increased EGF signaling activity. This latter behavior correlated to sustained HaCaT stress, believed to be maintained through the continual dissolution of internalized AgNPs. This study raises concerns that even after exposure ceases, the retained nanomaterials are capable of acting as a slow-release mechanism for metallic ions; continually stressing and modifying normal cellular functionality

Discrete Evolutionary Population Models: A New Approach

In this paper, we apply a new approach to a special class of discrete time evolution models and establish a solid mathematical foundation to analyse them. We propose new single and multi-species evolutionary competition models using the evolutionary game theory that require a more advanced mathematical theory to handle effectively. A key feature of this new approach is to consider the discrete models as non-autonomous difference equations. Using the powerful tools and results developed in our recent work [E. D\u27Aniello and S. Elaydi, The structure of ω-limit sets of asymptotically non-autonomous discrete dynamical systems, Discr. Contin. Dyn. Series B. 2019 (to appear).], we embed the non-autonomous difference equations in an autonomous discrete dynamical systems in a higher dimension space, which is the product space of the phase space and the space of the functions defining the non-autonomous system. Our current approach applies to two scenarios. In the first scenario, we assume that the trait equations are decoupled from the equations of the populations. This requires specialized biological and ecological assumptions which we clearly state. In the second scenario, we do not assume decoupling, but rather we assume that the dynamics of the trait is known, such as approaching a positive stable equilibrium point which may apply to a much broader evolutionary dynamics

Less Is More: Long-Term in Vitro Exposure to Low Levels of Silver Nanoparticles Provides New Insights for Nanomaterial Evaluation

In view of the vast number of new nanomaterials (NMs) that require testing and the constraints associated with animal models, the majority of studies to elucidate nanotoxicological effects have occurred in vitro, with limited correlation and applicability to in vivo systems and realistic, occupational exposure scenarios. In this study, we developed and implemented a chronic in vitromodel coupled with lower, regulatory dosages in order to provide a more realistic assessment of NM-dependent consequences and illuminate the implications of long-term NM exposure. When keratinocytes were exposed to 50 nm silver nanoparticles (Ag-NPs), we determined that chronically dosed cells operated under augmented stress and modified functionality in comparison to their acute counterparts. Specifically, Ag-NP exposure through a chronic mechanism increased p38 activation, actin disorganization, heightened ki67 expression, and extensive gene modification. Additionally, chronic Ag-NP exposure altered the way in which cells perceived and responded to epidermal growth factor stimulation, indicating a transformation of cell functionality. Most importantly, this study demonstrated that chronic exposure in the pg/mL range to Ag-NPs did not induce a cytotoxic response, but instead activated sustained stress and signaling responses, suggesting that cells are able to cope with prolonged, low levels of Ag-NP exposure. In summary, we demonstrated that through implementation of a chronic dosimetry paradigm, which more closely resembles realistic NM exposure scenarios, it is possible to illuminate long-term cellular consequences, which greatly differ from previously obtained acute assessments