Amphotericin B Polymer Nanoparticles Show Efficacy against Candida Species Biofilms

Purpose: Chronic infections of Candida albicans are characterised by the embedding of budding and entwined filamentous fungal cells into biofilms. The biofilms are refractory to many drugs and Candida biofilms are associated with ocular fungal infections. The objective was to test the activity of nanoparticulate amphotericin B (AmB) against Candida biofilms. Methods: AmB was encapsulated in the Molecular Envelope Technology (MET, N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan) nanoparticles and tested against Candida biofilms in vitro. Confocal laser scanning microscopy (CLSM) imaging of MET nanoparticles’ penetration into experimental biofilms was carried out and a MET-AmB eye drop formulation was tested for its stability. Results: MET-AmB formulations demonstrated superior activity towards C. albicans biofilms in vitro with the EC50 being ~30 times lower than AmB alone (EC50 MET-AmB = 1.176 μg mL−1, EC50 AmB alone = 29.09 μg mL−1). A similar superior activity was found for Candida glabrata biofilms, where the EC50 was ~10× lower than AmB alone (EC50 MET-AmB = 0.0253 μg mL−1, EC50 AmB alone = 0.289 μg mL−1). CLSM imaging revealed that MET nanoparticles penetrated through the C. albicans biofilm matrix and bound to fungal cells. The activity of MET-AmB was no different from the activity of AmB alone against C. albicans cells in suspension (MET-AmB MIC90 = 0.125 μg mL−1, AmB alone MIC90 = 0.250 μg mL−1). MET-AmB eye drops were stable at room temperature for at least 28 days. Conclusions: These biofilm activity findings raise the possibility that MET-loaded nanoparticles may be used to tackle Candida biofilm infections, such as refractory ocular fungal infections.

Finite-time stability results for fractional damped dynamical systems with time delays

This paper is explored with the stability procedure for linear nonautonomous multiterm fractional damped systems involving time delay. Finite-time stability (FTS) criteria have been developed based on the extended form of Gronwall inequality. Also, the result is deduced to a linear autonomous case. Two examples of applications of stability analysis in numerical formulation are described showing the expertise of theoretical prediction.

A Study of ψ-Hilfer Fractional Boundary Value Problem via Nonlinear Integral Conditions Describing Navier Model

This paper investigates existence, uniqueness, and Ulam’s stability results for a nonlinear implicit ψ-Hilfer FBVP describing Navier model with NIBCs. By Banach’s fixed point theorem, the unique property is established. Meanwhile, existence results are proved by using the fixed point theory of Leray-Schauder’s and Krasnoselskii’s types. In addition, Ulam’s stability results are analyzed. Furthermore, several instances are provided to demonstrate the efficacy of the main results.

Stability Analysis of Multistage One-Step Multiderivative Methods for Nonlinear Impulsive Differential Equations in Banach Spaces

In this paper, we first introduce the problem class K p μ , λ , ζ with respect to the initial value problems of nonlinear impulsive differential equations in Banach spaces. The stability and asymptotic stability results of the analytic solution of the problem class K p μ , λ , ζ are obtained. Then, the numerical stability and asymptotic stability conditions of multistage one-step multiderivative methods are also given. Two numerical experiments are given to confirm the theoretical results in the end.

Stabilization of Microbial Communities by Responsive Phenotypic Switching

Clonal microbes can switch between different phenotypes and recent theoretical work has shown that stochastic switching between these subpopulations can stabilize microbial communities. This phenotypic switching need not be stochastic, however, but can also be in response to environmental factors, both biotic and abiotic. Here, motivated by the bacterial persistence phenotype, we explore the ecological effects of such responsive switching by analyzing phenotypic switching in response to competing species. We show how the stability of microbial communities with responsive switching differs generically from that of communities with stochastic switching only. To understand this effect, we go on to analyse simple two-species models. Combining exact results and numerical simulations, we extend the classical stability results for models of two competing species without phenotypic variation to the case where one of the two species switches, stochastically and responsively, between two phenotypes. In particular, we show that responsive switching can stabilize coexistence even when stochastic switching on its own does not affect the stability of the community.

An asymptotic preserving scheme for a tumor growth model of porous medium type

Mechanical models of tumor growth based on a porous medium approach have been attracting a lot of interest both analytically and numerically. In this paper, we study the stability properties of a finite difference scheme for a model where the density evolves down pressure gradients and the growth rate depends on the pressure and possibly nutrients. Based on the stability results, we prove the scheme to be asymptotic preserving (AP) in the incompressible limit. Numerical simulations are performed in order to investigate the regularity of the pressure. We study the sharpness of the $L^4$-uniform bound of the gradient, the limiting case being a solution whose support contains a bubble which closes-up in finite time generating a singularity, the so-called focusing solution.

Qualitative Analysis of Langevin Integro-Fractional Differential Equation under Mittag–Leffler Functions Power Law

This research paper intends to investigate some qualitative analysis for a nonlinear Langevin integro-fractional differential equation. We investigate the sufficient conditions for the existence and uniqueness of solutions for the proposed problem using Banach’s and Krasnoselskii’s fixed point theorems. Furthermore, we discuss different types of stability results in the frame of Ulam–Hyers by using a mathematical analysis approach. The obtained results are illustrated by presenting a numerical example.