The counterbalance of endothelial glycocalyx and high wall shear stress to low-density lipoprotein concentration polarization in mouse ear skin arterioles.

BACKGROUND AND AIMS: Atherosclerosis preferentially occurs at regions in arterial branching, curvature, and stenosis, which may be explained by the geometric predilection of low-density lipoprotein (LDL) concentration polarization that has been investigated in major arteries in previous studies. Whether this also happens in arterioles remains unknown. METHODS: Herein, a radially non-uniform distribution of LDL particles and a heterogeneous endothelial glycocalyx layer in the mouse ear arterioles, as shown by fluorescein isothiocyanate labeled wheat germ agglutinin (WGA-FITC), were successfully observed by a non-invasive two-photon laser-scanning microscopy (TPLSM) technique. The stagnant film theory was applied as the fitting function to evaluate LDL concentration polarization in arterioles. RESULTS: The concentration polarization rate (CPR, the ratio of the number of polarized cases to that of total cases) in the inner walls of curved and branched arterioles was 22% and 31% higher than the outer counterparts, respectively. Results from the binary logistic regression and multiple linear regression analysis showed that endothelial glycocalyx thickness increases CPR and the thickness of the concentration polarization layer (CPL). Flow field computation indicates no obvious disturbances or vortex in modeled arterioles with different geometries and the mean wall shear stress is about 7.7-9.0 Pa. CONCLUSIONS: These findings suggest a geometric predilection of LDL concentration polarization in arterioles for the first time, and the existence of an endothelial glycocalyx, acting together with a relatively high wall shear stress in arterioles, may explain to some extent why atherosclerosis rarely occurs in these regions.

A low-cost and hand-hold PCR microdevice based on water-cooling technology.

Polymerase chain reaction (PCR) has become a powerful tool for detecting various diseases due to its high sensitivity and specificity. However, the long thermocycling time and the bulky system have limited the application of PCR devices in Point-of-care testing. Herein, we have proposed an efficient, low-cost, and hand-hold PCR microdevice, mainly including a control module based on water-cooling technology and an amplification module fabricated by 3D printing. The whole device is tiny and can be easily hand-held with a size of about 110 mm × 100 mm × 40 mm and a weight of about 300 g at a low cost of about $170.83. Based on the water-cooling technology, the device can efficiently perform 30 thermal cycles within 46 min at a heating/cooling rate of 4.0/8.1 ℃/s. To test our instrument, plasmid DNA dilutions were amplified with this device; the results demonstrate successful nucleic acid amplification of the plasmid DNA and exhibit the promise of this device for Point-of-care testing.

N-heterocyclic carbene-palladium(II)-1-methylimidazole complex-catalyzed Suzuki-Miyaura coupling of benzyl sulfonates with arylboronic acids.

The first example of palladium-catalyzed Suzuki-Miyaura coupling between benzyl sulfonates and arylboronic acids was reported in this paper. In the presence of a well-defined, air-stable and easily available NHC-Pd(II)-Im complex, all reactions worked well to give the desired products in good to almost quantitative yields under the optimal conditions. Electron-rich, -neutral, -poor and sterically-hindered substituents on both substrates are tolerated in such transformation, providing a convenient, efficient and alternative method for the synthesis of diarylmethanes.