What Drives Visitors' Use of Bins in Urban Parks? An Application of the Stimulus-Organism-Response Model.

Littering by visitors has led to severe challenges for rubbish collection in urban parks. One way to solve this problem is to encourage visitors to put rubbish in the bin. The purpose of this study is to explore the mechanism that drives people's use of bins in urban parks. The theoretical model of stimulus-organism-response is used to test the influence of stimuli (personal and social norms) on people's psychology (facilitators and inhibitors), thereby producing responses (the use of bins). In this study, we used a purposeful sampling method. Overall, 400 questionnaires were distributed, and 356 valid questionnaires were collected from visitors to the Shanghai City Park in China. The data were analysed using structural equations. The results show that personal and social norms have a significant impact on visitors' internal psychological state (facilitators and inhibitors). More specifically, personal and social norms are positively correlated with facilitators and negatively correlated with inhibitors. They have a significant positive impact on people's use of bins. We also found that facilitators and inhibitors partially mediate the relationship between norms and behaviours. The study suggests park managers should introduce various measures to influence people's personal norms and cultivate people's awareness of their obligation, responsibility, and commitment to the environment, and managers should also show visitors the consequences of not properly disposing of their rubbish as well as place more rubbish bins in key areas.

Swinhoeic acid from Potentilla fragarioides ameliorates high glucose-induced oxidative stress and accumulation of ECM in mesangial cells via Keap1-dependent activation of Nrf2.

OBJECTIVES: Diabetic nephropathy (DN) is one of the most common microvascular complications of diabetes mellitus. Oxidative stress resulting from high glucose promotes accumulation of ECM and development of DN. Activation of Nrf2 could attenuate oxidative stress and following accumulation of ECM. To find novel therapy for DN, we explored the effects of swinhoeic acid from Potentilla fragarioides on mesangial cells under high glucose and underlying mechanisms. METHODS: CCK-8 and BrdU incorporation assays for survival of mesangial cells gave the concentration of swinhoeic acid in following investigations. ROS, MDA, SOD and CAT were determined. And ECM proteins and their upstream regulators TGF-ß1 and CTGF were detected using ELISA assays. Activation of Nrf2 was explored by immunofluorescence staining together with luciferase reporter assay. To demonstrate the role of Nrf2 activation, siRNA interference was performed. And co-immunoprecipitation assay was used to elucidate swinhoeic acid affects the interaction between Keap1 and Nrf2. RESULTS: Swinhoeic acid at 10 and 20 µM attenuated oxidative stress and accumulation of ECM in mesangial cells under high glucose. Itactivated Nrf2 in a Keap1-dependent manner, which was involved in its effects. CONCLUSION: Swinhoeic acid ameliorates oxidative stress and accumulation of ECM resulting from high glucose in mesangial cells via activating Nrf2 in Keap1-dependent manner.

Discovery of caffeoylisocitric acid as a Keap1-dependent Nrf2 activator and its effects in mesangial cells under high glucose.

Diabetic nephropathy (DN) is one of the severe microvascular complications of diabetes mellitus. Oxidative stress resulting from aberrant metabolism of glucose mediates renal inflammation and fibrosis in the progression of DN. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor regulating the expression of antioxidant enzymes. Activating Nrf2 will give a promising therapy for DN. To discover novel Nrf2 activators, we have investigated caffeoylisocitric acid using mesangial cells under high glucose. The results showed at 10 µM, caffeoylisocitric acid significantly inhibited the self-limited proliferation of mesangial cells induced by high glucose. Further assessments have disclosed caffeoylisocitric acid mitigated oxidative stress, inflammation and accumulation of extracellular matrix resulting from high glucose via inactivating MAPK signalling. Meanwhile activation of Nrf2 was observed and involved in these effects through the interaction between Keap1 and caffeoylisocitric acid to disrupt Keap1-Nrf2 complex. Therefore, caffeoylisocitric acid is a promising Nrf2 activator targeting DN.

Carboxymethyl chitosan/phospholipid bilayer-capped mesoporous carbon nanoparticles with pH-responsive and prolonged release properties for oral delivery of the antitumor drug, Docetaxel.

In this article, a new type of carboxymethyl chitosan/phospholipid bilayer-capped mesoporous carbon nanomatrix (CCS/PL/MC) was fabricated as a potential nano-drug delivery system. In this drug delivery system, a mesoporous carbon nanomatrix (MC) acts as the support for loading drug molecules, a positively charged phospholipid (PL) layer works as the inner shell for prolonged drug release and a negatively charged carboxymethyl chitosan (CCS) layer serves as the outer shell for pH-responsive drug release. Docetaxel (DTX) was selected as a model drug. The drug-loaded CCS/PL/MC was synthesized via a combination approach of double emulsion/solvent evaporation followed by lyophilization. The drug-loaded nanoparticles were characterized for their particle size, structure, morphology, zeta (ζ)-potential, specific surface area, porosity, drug loading and solid state. In vitro drug release tests showed that the drug-loaded CCS/PL/MC nanoparticles possess a good pH-sensitivity and prolonged releasing ability with negligible release in gastric media and controlled release in intestinal media. Compared with MC and PL-capped MC, CCS/PL/MC had a greater mucoadhesiveness. Moreover, cellular uptake study indicated that CCS/PL/MC might improve intracellular drug delivery. These results suggest that this hybrid nanocarrier, combining the beneficial features of CCS, PL and MC, is a promising drug delivery system able to improve the oral absorption of antitumor drugs.

Synthesis and evaluation of mesoporous carbon/lipid bilayer nanocomposites for improved oral delivery of the poorly water-soluble drug, nimodipine.

PURPOSE: A novel mesoporous carbon/lipid bilayer nanocomposite (MCLN) with a core-shell structure was synthesized and characterized as an oral drug delivery system for poorly water-soluble drugs. The objective of this study was to investigate the potential of MCLN-based formulation to modulate the in vitro release and in vivo absorption of a model drug, nimodipine (NIM). METHODS: NIM-loaded MCLN was prepared by a procedure involving a combination of thin-film hydration and lyophilization. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area analysis, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were employed to characterize the NIM-loaded MCLN formulation. The effect of MCLN on cell viability was assessed using the MTT assay. In addition, the oral bioavailability of NIM-loaded MCLN in beagle dogs was compared with that of the immediate-release formulation, Nimotop®. RESULTS: Our results demonstrate that the NIM-loaded MCLN formulation exhibited a typical sustained release pattern. The NIM-loaded MCLN formulation achieved a greater degree of absorption and longer lasting plasma drug levels compared with the commercial formulation. The relative bioavailability of NIM for NIM-loaded MCLN was 214%. MCLN exhibited negligible toxicity. CONCLUSION: The data reported herein suggest that the MCLN matrix is a promising carrier for controlling the drug release rate and improving the oral absorption of poorly water-soluble drugs.

Preparation, Physicochemical Characterization and I n - vitro Dissolution Studies of Diosmin-cyclodextrin Inclusion Complexes.

Diosmin, a vascular-protecting agent, is practically insoluble in water, and its oral absorption is limited by its extremely low dissolution rate. In this study, ß-cyclodextrin (ßCD) and 2-hydroxypropyl-ß-cyclodextrin (HPßCD) were obtained to improve the solubility and dissolution rate of diosmin. Phase solubility studies of diosmin with ßCD and HPßCD in distilled water were conducted to characterize the complexes in liquid state. The solid-state characterization of the complexes prepared with different methods was performed by fourier transform-infra red spectroscopy (FTIR), optical microscopy analyses, and differential scanning calorimetry (DSC). Dissolution studies were carried out in distilled water using US pharmacopeia dissolution rate testing equipment. The complexation of diosmin with ßCD and HPßCD both indicated an AL type of phase-solubility diagrams, and the apparent stability constants (Kc) was found to be 222.13 and 200.08 M(-1), respectively. The Kc values indicated the ßCD and HPßCD showed the similar equal complexation ability with diosmin, HPßCD provided higher solubility for diosmin due to its higher water solubility. The dissolution studies suggest that the inclusion complexes provide higher dissolution rate compared with the physical mixtures and the drug alone. Furthermore, the inclusion complex prepared by freeze drying method presented higher dissolution rate than kneading method.