scholarly journals Steady-state flux of diffusing particles to a rough boundary formed by absorbing spikes periodically protruding from a reflecting base

2019 ◽  
Vol 150 (19) ◽  
pp. 194109 ◽  
Author(s):  
Alexei T. Skvortsov ◽  
Alexander M. Berezhkovskii ◽  
Leonardo Dagdug
Pharmaceutics ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1560
Author(s):  
Amr Gamal ◽  
Haitham Saeed ◽  
Fatma I. Abo El-Ela ◽  
Heba F. Salem

Throughout the United States and the world, skin cancer is the most frequent form of cancer. Sonidegib (SNG) is a hedgehog inhibitor that has been used for skin cancer treatment. However, SNG has low bioavailability and is associated with resistance. The focus of this work is to enhance bioavailability, anti-tumor efficacy and targeting of SNG via developing ethosome gel as a potential treatment for skin cancer. SNG-loaded ethosomes formulation was prepared and characterized in vitro by %entrapment efficiency (%EE), vesicle size, morphology, %release and steady-state flux. The results showed that the prepared formulation was spherical nanovesicles with a %EE of 85.4 ± 0.57%, a particle size of 199.53 ± 4.51 nm and a steady-state flux of 5.58 ± 0.08 µg/cm2/h. In addition, SNG-loaded ethosomes formulation was incorporated into carbopol gel to study the anti-tumor efficacy, localization and bioavailability in vivo. Compared with oral SNG, the formulation showed 3.18 times higher relative bioavailability and consequently significant anti-tumor activity. In addition, this formulation showed a higher rate of SNG penetration in the skin’s deep layers and passive targeting in tumor cells. Briefly, SNG-loaded ethosome gel can produce desirable therapeutic benefits for treatment of skin cancer.


2018 ◽  
Vol 12 (1) ◽  
Author(s):  
Abel Folch-Fortuny ◽  
Bas Teusink ◽  
Huub C.J. Hoefsloot ◽  
Age K. Smilde ◽  
Alberto Ferrer

2019 ◽  
Author(s):  
Gosse B. Overal ◽  
Josephus Hulshof ◽  
Robert Planqué

AbstractMicrobial cells need to adapt to changing environmental conditions to survive. There is an evolutionary advantage to grow fast; this requires high metabolic rates, and an efficient allocation of enzymatic resources. Here we study a general control theory called qORAC, developed previously, which allows cells to adaptively control their enzyme allocations to achieve maximal steady state flux. The control is robust to perturbations in the environment, but those perturbations themselves do not feature in the control. In this paper we focus on the archetypical pathway, the linear chain with reversible Michaelis-Menten kinetics, together with qORAC control. First we assume that the metabolic pathway is in quasi-steady state with respect to enzyme synthesis. Then we show that the map between steady state metabolite and enzyme concentrations is a smooth bijection. Using this information, we finally show that the unique (and hence flux-maximising) steady state of this system is locally stable. We provide further evidence that it may in fact be globally stable.


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