Hypoxic White Matter Injury and Recovery After Reoxygenation in Adult Mice: Magnetic Resonance Imaging Findings and Histological Studies.

Cognitive dysfunction and brain white matter (WM) injury have been found in adults exposed to hypoxia. However, the mechanisms underlying these impairments remain unclear, and moreover, it is also unclear whether these impairments are reversible after reoxygenation. In this study, adult male mice were exposed to hypoxia for 15 days at a simulated altitude of 4300 m and then reoxygenated for 2 months. Control mice were raised under normoxic conditions. Mice showed a significant decrease in arterial oxygen saturation (SaO2) and an increase in heart rate and breath rate after hypoxic exposure, and they displayed anxiety-like emotion and impaired cognitions. Hypoxic mice showed decreased brain WM fractional anisotropy (FA) and increased mean diffusion (MD) mainly in the corpus callosum and internal capsule. The reason for the adult brain WM injury was myelin rather than axon. Further, the myelin injury was due to the obstruction of oligodendrocyte precursor cells (OPCs) differentiation and eventually led to behavioral deficits. More importantly, the changes in physiological indicators, behavioral disorders, and WM injury caused by hypoxia can be recovered after reoxygenation. Taken together, our data indicate that adult brain WM injury caused by hypoxia is reversible after reoxygenation and enhancing OPCs differentiation may be a promising therapy for clinical hypoxic diseases associated with brain injury. Schematic diagram of brain WM and behavioral changes induced by hypoxia/reoxygenation in adult mice.

Consistent differences in brain structure and functional connectivity in high-altitude native Tibetans and immigrants.

It has been well-established that high-altitude (HA) environments affect the human brain; however, the differences in brain structural and functional networks between HA natives and acclimatized immigrants have not been well clarified. In this study, native HA Tibetans were recruited for comparison with Han immigrants (average of 2.3 ± 0.3 years at HA), with lowland residents recruited as controls. Cortical gray matter volume, thickness, and functional connectivity were investigated using magnetic resonance imaging data. In addition, reaction time and correct score in the visual movement task, hematology, and SpO2 were measured. In both Tibetans and HA immigrants vs. lowlanders, decreased SpO2, increased hematocrit and hemoglobin, and increased reaction time and correct score in the visual movement task were detected. In both Tibetans and HA immigrants vs. lowlanders, gray matter volumes and cortical thickness were increased in the left somatosensory and motor cortex, and functional connectivity was decreased in the visual, default mode, subcortical, somatosensory-motor, ventral attention, and subcortical networks. Furthermore, SpO2 increased, hematocrit and hemoglobin decreased, and gray matter volumes and cortical thickness increased in the visual cortex, left motor cortex, and right auditory cortex in native Tibetans compared to immigrants. Movement time and correct score in task were positively correlated with the thickness of the visual cortex. In conclusion, brain structural and functional network difference in both Tibetan natives and HA immigrants were largely consistent, with native Tibetans only showing more intense brain modulation. Different populations acclimatized to HA develop similar brain mechanisms to cope with hostile HA environmental factors.

Novel chiral metal organic frameworks functionalized composites for facile preparation of optically pure propranolol hydrochlorides.

Two novel sorbents based on polydopamine (PDA)-coated magnetic graphite oxide-metal organic frameworks nanoparticles [Cu(L-mal)(bpy)]·H2O (MGO-CuLBH) and [Cu(D-mal)(bpy)]·H2O (MGO-CuDBH) possessing of both magnetic property and excellent enantioselective ability were prepared and characterized. Solutions of racemic propranolol hydrochloride (Rac-PRO) were chosen to investigate the enantioselective performance of MGO-CuLBH and MGO-CuDBH by dispersive magnetic nanoparticle solid phase extraction (d-MNSPE). The results showed that the nanocomposites have excellent enantioselectivity to PROs with enantiomeric excess (ee) values reaching up to 98%. The entire process with PROs by the d-MNSPE method was fast, convenient and the collected composites could be easily recycled. Multi-stage operations using MGO-CuLBH and MGO-CuDBH were scaled up to obtain milligram quantities of R-propranolol hydrochloride (R-PRO) and S-propranolol hydrochloride (S-PRO). Furthermore, on the basis of the successful preparations, the differences in the cytotoxicity of Rac-PRO, R-PRO and S-PRO on A549 cells in vitro were all evaluated.

Synthesis and performance of chiral ferrocene modified silica gel for mixed-mode chromatography.

A brush-type chiral stationary phase, N-ferrocenyl benzoyl-(1S, 2R)-1, 2-diphenyl ethanol-bonded on the silica gel (NFcBEs) for high performance liquid chromatography (HPLC), was prepared using γ-glycidoxypropyltrimethoxysilane as coupling reagent. The structure of this novel material was characterized by infrared spectroscopy, elemental analysis and thermogravimetric analysis. Mechanism involved in the chromatographic separation is the multi-interaction including hydrophobic, π-π, hydrogen-bonding, π-charge transfer, dipole-dipole and acid-base equilibrium interactions. Based on these interactions, successful separation could be achieved among polycyclic aromatic hydrocarbons, mono-substituted benzenes, aromatic amines, quinolines, nucleosides, phenols and 5-nitroimidazoles drugs in reversed phase liquid chromatography (RPLC). Good resolutions for substituted amine isomers were also obtained with NFcBEs. Racemates of amino acids and drug carvedilol mixtures were well separated on NFcBEs in the normal phase liquid chromatography (NPLC) mode. Such stationary phase with characteristics of multi-interaction mechanism and mixed-mode separation is potential for the analysis of complex samples. The retention behaviors of R- and S-carvedilol on NFcBEs column were investigated with the assistance of quantum chemistry calculation using the density functional theory (DFT) B3LYP method.