Melanin nanoparticles enhance the neuroprotection of mesenchymal stem cells against hypoxic-ischemic injury by inhibiting apoptosis and upregulating antioxidant defense.

Polydopamine nanoparticles are artificial melanin nanoparticles (MNPs) that show strong antioxidant activity. The effects of MNPs on the neuroprotection of mesenchymal stem cells (MSCs) against hypoxic-ischemic injury and the underlying mechanism have not yet been revealed. In this study, an oxygen-glucose deprivation (OGD)-injured neuron model was used to mimic neuronal hypoxic-ischemic injury in vitro. MSCs pretreated with MNPs and then cocultured with OGD-injured neurons were used to investigate the potential effects of MNPs on the neuroprotection of MSCs and to elucidate the underlying mechanism. After coculturing with MNPs-pretreated MSCs, MSCs, and MNPs in a transwell coculture system, the OGD-injured neurons were rescued by 91.24%, 79.32%, and 59.97%, respectively. Further data demonstrated that MNPs enhanced the neuroprotection against hypoxic-ischemic injury of MSCs by scavenging reactive oxygen species and superoxide and attenuating neuronal apoptosis by deactivating caspase-3, downregulating the expression of proapoptotic Bax proteins, and upregulating the expression of antiapoptotic Bcl-2 proteins. These findings suggest that MNPs enhance the neuroprotective effect of MSCs against hypoxic-ischemic injury by inhibiting apoptosis and upregulating antioxidant defense, which could provide some evidence for the potential application of combined MNPs and MSCs in the therapy for ischemic stroke.

First-principles study of spontaneous polarization in SrBi2Ta2O9.

We investigate the spontaneous polarization in SrBi2Ta2O9 by analyzing the maximally localized Wannier functions using a first-principles method. The calculated spontaneous polarization in ferroelectric SrBi(2)Ta(2)O(9) along the polarized a axis is 23.8 µC cm( - 2), with an electronic contribution of 8.4 µC cm( - 2). The electronic contribution of each atom to the spontaneous polarization in the unit cell is quantitatively evaluated. The Bi component plays the most important role in the complex chemical bonding and the total polarization. The chemical bonding in the Ta-O octahedra and bismuth oxide slabs of ferroelectric SrBi2Ta2O9 is also addressed.

[Negative association of FGA gene 128C/G polymorphism with cerebral infarction and its effect on plasma fibrinogen in Hunan Hans].

OBJECTIVE: To investigate the relationship of FGA gene 128C/G polymorphism and cerebral infarction (CI) and evaluate the effect of FGA-128C/G polymorphism on plasma fibrinogen in Hunan Hans. METHODS: FGA-128C/G polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing in 194 CI patients and 114 healthy controls. RESULTS: There were CG and CC genotypes in the FGA-128C/G locus. No GG genotype was observed in Hunan Hans. There was no significant difference in genotype and allele frequencies between the controls and CI group (P> 0.05), and statistically significant difference was not found in fibrinogen (Fg) level between the CG and CC genotypes (P>0.05). After analyzing blood plasma Fg using the influencing factor multiple regression analysis, it was shown that the Fg level had no relationship with the FGA-128C/G genotype, but it increased with age. And the Fg level in males was higher than that in females. CONCLUSION: There was FGA gene 128C/G polymorphism in the Hunan Han population. There was no association of this polymorphism with the increased Fg level of CI patient in the population. FGA-128C/G might not be the predisposing gene of CI in Hunan Han population. The age and sex were the major factors affecting the plasma Fg level in this population.