ABSTRACT
Slow freezing is the most commonly used technique for the cryopreservation of spermatozoa in clinical practice. However, it has been shown to have a negative impact on sperm function and structure. Vitrification as a successful alternative method has been proved to have better protective effects on human embryos, but vitrification of spermatozoa is still subject to low recovery rates. In this study, a modified vitrification method for native spermatozoa was developed. A total of 28 semen samples were included; each sample was divided into three equal parts and assigned to fresh, slow freezing, and vitrification groups. Sperm vitality, motility, morphology, DNA integrity, and acrosome reaction were assessed for each of the groups. The results showed that vitrification achieves better results for several sperm protection parameters than slow freezing; vitrification achieves a higher recovery rate (P < 0.05), motility (P <0.05), morphology (P <0.05), and curve line velocity (P <0.05) than slow freezing. Furthermore, DNA fragmentation was decreased (P <0.05) and better acrosome protection (P <0.05) was exhibited in the spermatozoa after vitrification. Principal component analysis of all sperm parameters revealed that the vitrification cluster was closer to the fresh cluster, indicating that spermatozoa are better preserved through vitrification. In conclusion, while both slow freezing and vitrification have negative effects on sperm function and structure, the vitrification protocol described here had a relatively better recovery rate (65.8%) and showed improved preservation of several sperm quality parameters compared with slow freezing.
ABSTRACT
Increasing evidence has shown that astrocytes are implicated in regulating oligodendrocyte myelination, but the underlying mechanisms remain largely unknown. To understand whether microRNAs in astrocytes function in regulating oligodendroglial differentiation and myelination in the developing and adult CNS, we generated inducible astrocyte-specific Dicer conditional knockout mice (hGFAP-CreERT; Dicer fl/fl). By using a reporter mouse line (mT/mG), we confirmed that hGFAP-CreERT drives an efficient and astrocyte-specific recombination in the developing CNS, upon tamoxifen treatment from postnatal day 3 (P3) to P7. The Dicer deletion in astrocytes resulted in inhibited oligodendroglial differentiation and myelination in the developing CNS of Dicer cKO mice at P10 and P14, and did not alter the densities of neurons or axons, indicating that Dicer in astrocytes is required for oligodendrocyte myelination. Consequently, the Dicer deletion in astrocytes at P3 resulted in impaired spatial memory and motor coordination at the age of 9 weeks. To understand whether Dicer in astrocytes is also required for remyelination, we induced Dicer deletion in 3-month-old mice and then injected lysolecithin into the corpus callosum to induce demyelination. The Dicer deletion in astrocytes blocked remyelination in the corpus callosum 14 days after induced demyelination. Together, our results indicate that Dicer in astrocytes is required for oligodendroglia myelination in both the developing and adult CNS.
ABSTRACT
Exposure to chronic hypoxia is considered to be a risk factor for deficits in brain function in adults, but the underlying mechanisms remain largely unknown. Since active myelinogenesis persists in the adult central nervous system, here we aimed to investigate the impact of chronic hypoxia on myelination and the related functional consequences in adult mice. Using a transgenic approach to label newly-generated myelin sheaths (NG2-CreER
ABSTRACT
Exposure to chronic hypoxia is considered to be a risk factor for deficits in brain function in adults, but the underlying mechanisms remain largely unknown. Since active myelinogenesis persists in the adult central nervous system, here we aimed to investigate the impact of chronic hypoxia on myelination and the related functional consequences in adult mice. Using a transgenic approach to label newly-generated myelin sheaths (NG2-CreER
Subject(s)
Animals , Mice , Clemastine , Hypoxia/complications , Mice, Inbred C57BL , Mice, Transgenic , Myelin Sheath , OligodendrogliaABSTRACT
Objective To describe the current situation of diarrhea in children under five years old in Nepal and to explore its influencing factors. Methods Data were collected from the open-access database, Nepal Demographic and Health Surveys in 2006, 2011 and 2016. Chi-square ( 2) and Wilcoxon rank sum test were used to compare difference of potential risk factors between groups with and without diarrhea. Multiple Logistic regression model was adopted to identify significant influencing factors on diarrhea in children under five years old in Nepal. Results In 2006, 2011 and 2016, the incidence of diarrhea children under five in Nepal was 12.3%, 13.3% and 6.8%, respectively. Univariate analysis of the potential influencing factors showed that there were significant differences in the gender, water source, toilet facilities and fuel type, age of children, age of mother when she gave birth to the child and education years of mother and children with and without diarrhea (all P＜0.05). Multiple analysis revealed that improved toilet facilities (OR=0.874, 95% CI: 0.769-0.994, P=0.041) and the age of children(OR=0.613, 95% CI: 0.580-0.645, P＜0.001) were protective factors of childhood diarrhea, and the risk of boys was higher than that of girls(OR=1.277, 95% CI: 1.147-1.423, P＜0.001). Conclusions From 2006 to 2016, the incidence of diarrhea in children under five years old in Nepal was decreasing. Toilet facilities, age of children and gender of children were identified as the influencing factors of childhood diarrhea.