Engineering a Bi-Conical Microchip as Vascular Stenosis Model.

Vascular stenosis is always associated with hemodynamic changes, especially shear stress alterations. Herein, bi-conical shaped microvessels were developed through flexibly and precisely controlled templated methods for hydrogel blood-vessel-like microchip. The blood-vessel-like microvessels demonstrated tunable dimensions, perfusable ability, and good cytocompatibility. The microchips showed blood-vessel-like lumens through fine embeddedness of human umbilical vein endothelial cells (HUVECs) on the interior surface of hydrogel microchannels, which closely reproduced the morphology and functions of human blood vessels. In the gradual narrowing region of bi-conical shape, fluid flow generated wall shear stress, which caused cell morphology variations. Wall shear rates at the gradual narrowing region were simulated by FLUENT software. The results showed that our microchannels qualified for performance as a vascular stenosis-like model in evaluating blood hydrodynamics. In general, our blood-vessel-on-a-chip could offer potential applications in the prevention, diagnosis, and therapy of arterial thrombosis.

On-Chip Facile Preparation of Monodisperse Resorcinol Formaldehyde (RF) Resin Microspheres.

Monodisperse resorcinol formaldehyde resin (RF) microspheres are an important polymeric material because of their rich surface functional group and uniform structural characteristics and have been increasingly applied as an electrode material, catalyst support, absorbent, and carbon microsphere precursor. The polymerization conditions, such as the gelation/solidification temperature and the residence time, can largely influence the physical properties and the formation of the 3D polymeric network of the RF microspheres as well as the carbon microspheres. However, few studies have reported on the complexity of the gelation and solidification processes of resol. In this work, we developed a new RF microsphere preparation device that contains three units: a droplet generation unit, a curing unit, and a collection unit. In this system, we controlled the gelation and solidification processes of the resol and observed its curing behavior, which helped us to uncover the curing mechanism of resol. Finally, we obtained the optimized polymerization parameters, obtaining uniform RF microspheres with a variation coefficient of 4.94%. The prepared porous RF microspheres presented a high absorption ability, reaching ~90% at 10 min. Thus, our method demonstrated the practicality of on-chip monodisperse microspheres synthesis. The product was useful in drug delivery and adsorbing large poisonous molecules.

[Comparison of respiratory diseases and symptoms among school-age children in areas with different levels of air pollution].

OBJECTIVE: To compare the differences of children's health in different area, and to confirm if the prevalence of respiratory diseases and symptoms among children are closely associated with the air pollution. METHODS: A cross-sectional study was conducted in an urban area A and a suburban area B with different levels of air pollution in Beijing. Using a cluster sampling method, we recruited 4 564 children from 3 primary schools in urban A and 4 primary schools in suburban B. Respiratory symptoms were investigated using an international standardized questionnaire including characteristics of children, living conditions, respiratory diseases and symptoms and situation of parents. The concentrations of air pollutants for recent five years were obtained from Reports on the Quality of the Beijing Environment. SPSS 16.0 was used to analyze data. RESULTS: The prevalence of cough, persistent cough, phlegm, persistent phlegm, wheeze and asthma in A area were higher than those in B area [(62.2% vs. 59.9%), (6.3% vs. 3.1%), (42.4% vs. 37.4%),(3.6% vs. 2.4%),(13.3% vs. 9.9%)and(9.5% vs. 5.4%)]. Except for cough, cough with cold, cough without cold, the prevalence of respiratory diseases and symptoms in A area were significantly higher than those in B area (P<0.05). Logistic regression analysis showed the prevalence of persistent cough, phlegm without cold, asthma in A area were significantly higher than those in B area (P<0.05). CONCLUSION: Respiratory diseases and symptoms among school-age children were closely associated with the level of air pollution.

Investigation of parabens in commercial cosmetics for children in Beijing, China.

Parabens are one of the most common preservatives in cosmetics. Because allergenicity and cytotoxicity potential values are major aspects of preservative safety and parabens are xenoestrogens, safety levels of parabens have been restricted in "Hygienic Standard for Cosmetics" (2007 edition) by the Ministry of Public Health of China, and a high-performance liquid chromatography (HPLC) for the simultaneous determination of parabens is recommended. To investigate whether the commonly used parabens in children's cosmetics were at a safety level, 105 cosmetics for children were randomly purchased from the local market in Beijing and analyzed by the proposed HPLC method. The detection rate of methylparaben was the highest and the next was propylparaben. Among the 105 samples, two or more kinds of parabens were detected in 72 samples with concentrations ranging from 0.02% to 0.75%; 18 samples contained one kind of paraben with concentrations ranging from 0.002% to 0.06%. In this study, the contents of parabens in the 105 samples were all below the restricted levels.

[Tissue distribution of 1,3-diphenyl-1,3-propanedione in mice].

OBJECTIVE: To investigate tissue distribution characteristics of 1,3-diphenyl-1,3-propanedione (DPPD) in mice. METHODS: Male ICR mice were dosed with DPPD 500 mg/kg via oral gavage, and the tissue samples of the heart, liver, spleen, lungs, kidneys and muscle of each mouse were collected as scheduled. At each time point, the concentrations of DPPD in the mouse tissues were measured by high performance liquid chromatography (HPLC) method. The main pharmacokinetic parameters were calculated by Thermo Kinetica 4.4.1 software. RESULTS: DPPD was absorbed rapidly after oral administration. The concentrations of DPPD in the liver and in the kidney were higher, respectively (liver: AUC(tot)=41.92 µg×h/g, kidney: AUC(tot)=40.40 µg×h/g). The drug concentrations showed a rapid distribution in the liver and lungs (T(max)=0.32 h and 0.33 h respectively) after oral administration, but in the muscle the maximum was 3.85 h. The maximum concentration of DPPD was in the liver (C(max)=31.20 µg/g), which was also the highest tissue concentration of all the subjects. DPPD could be detected at the low concentration within 24 h in all the tissues involved. CONCLUSION: DPPD distributed unevenly in various tissues. In the liver, kidney and muscle, the amount of the drug concentration was larger, and was lower in the lungs and spleen.