Stationary distribution and extinction of a stochastic HIV/AIDS model with nonlinear incidence rate.

This paper studies a stochastic HIV/AIDS model with nonlinear incidence rate. In the model, the infection rate coefficient and the natural death rates are affected by white noise, and infected people are affected by an intervention strategy. We derive the conditions of extinction and permanence for the stochastic HIV/AIDS model, that is, if $ R_0/ < 1, $ HIV/AIDS will die out with probability one and the distribution of the susceptible converges weakly to a boundary distribution; if $ R_0/ > 1 $, HIV/AIDS will be persistent almost surely and there exists a unique stationary distribution. The conclusions are verified by numerical simulation.

Improved Bioavailability and Antitumor Effect of Docetaxel by TPGS Modified Proniosomes: In Vitro and In Vivo Evaluations.

A novel oral drug delivery system, TPGS modified docetaxel proniosomes (DTX-TPGS-PNs), was designed to enhance the oral bioavailability and antitumor efficiency of the poorly water-soluble drug docetaxel. DTX-TPGS-PN niosomes were 93 ± 6.5 nm in size, -18.53 ± 1.65 mV in zeta potential and exhibited spherical morphology, with an encapsulation efficiency of 97.31 ± 0.60%. The system showed sustained release in both simulated gastric and intestinal fluid. The results of caco-2 monolayer, everted gut sac model and improved single-pass intestinal perfusion model transport studies showed that DTX-TPGS-PN niosomes could significantly improve the absorption of DTX. The pharmacokinetics study suggested the absolute bioavailability of DTX-TPGS-PN niosomes were 7.3 times that of DTX solution. In addition, a higher antitumor efficacy than DTX solution was demonstrated in MCF-7 and MDA-MB-231 cells in vitro and in MCF-7 tumor-bearing mice model in vivo. Our results demonstrated DTX-TPGS-PN is promising in enhancing the bioavailability and efficiency of poorly water-soluble drug DTX, and the potential of proniosomes as stable precursors for oral drug delivery.

[Development and characterization of TPGS modified proniosomes of docetaxel].

A novel oral delivery system that TPGS modified docetaxel proniosomes, DTX-TPGS-PN, was developed and the characterization after hydration was observed. Firstly, Doce-TPGS-PN was optimized by investing the factors, including the type of surfactant, methods of adding TPGS, content of TPGS and the molar ratio of span40/cholesterol, which may affecting the particle size, encapsulation efficiency and instantaneous release of drug in the formulation. Then, the morphology, particle size, Zeta potential, encapsulation efficiency and in vitro release of the formulation were evaluated. The result showed that hydrated nanoparticles of DTX-TPGS-PNs were (93 ± 6.5) nm in size,(-83.95 ± 3.69) mV in zeta potential, (97.31 ± 0.60)% in encapsulation efficiency, exhibiting spherical morphology and biphasic release process that a low burst effect within the first 0.5 hour and a relative-sustained release for the next several hours in PBS. These results indicate the oral delivery system of DTX-TPGS-PN was successfully built with good properties.

Global behaviour of an age-infection-structured HIV model with impulsive drug-treatment strategy.

In this paper, we develop an HIV model that considers the dependence of HIV/AIDS progress on infection age (duration since infection), chronological age and impulsive antiretroviral treatment. The analytical results show that there exists a globally asymptotically stable infection-free state when the impulsive period T and drug-treatment proportion p satisfy R(0)(p,T)<1. The numerical simulation results indicate that there exist T and p such that R(0)(p,T)<1. Due to pulses, it would be difficult to obtain the optimal pulse interval in the age distribution of population. However, our results demonstrate the effect of the impulsive drug-treatment strategy on the dynamics of HIV/AIDS.