The oncogenic roles of Notch1 in astrocytic gliomas in vitro and in vivo

Notch receptors play an essential role in cellular processes during embryonic and postnatal development, including maintenance of stem cell self-renewal, proliferation, and determination of cell fate and apoptosis. Deregulation of Notch signaling has been implicated in some genetic diseases and tumorigenesis. The function of Notch signaling in a variety of tumors can be either oncogenic or tumor-suppressive, depending on the cellular context. In this study, Notch1 overexpression was observed in the majority of 45 astrocytic gliomas with different grades and in U251MG glioma cells. Transfection of siRNA targeting Notch1 into U251 cells in vitro downregulated Notch1 expression, associated with inhibition of cell growth, arrest of cell cycle, reduction of cell invasiveness, and induction of cell apoptosis. Meanwhile, tumor growth was delayed in established subcutaneous gliomas in nude mice treated with Notch1 siRNA in vivo. These results suggest that Notch1 plays an important oncogenic role in the development and progression of astrocytic gliomas. Furthermore, knockdown of Notch1 expression by siRNA simultaneously downregulated the expression of EGFR and the important components of its downstream pathways, including PI3K, p-AKT, K-Ras, cyclin D1 and MMP9, indicating the crosstalk and interaction of Notch and EGFR signaling pathways.     

Ad-PTEN增强LY294002对人胶质瘤细胞系U251的生长抑制作用

目的在体外实验中,利用携带野生型PTEN基因的重组腺病毒（Ad—PTEN）和P13K的小分子抑制剂LY294002联合抑制P13K／AKT信号通路,观察两者联合对人胶质瘤细胞系U251生长有无正向协同作用及探讨产生这种作用的机制。方法15251细胞按处理方式不同分为4组：DMSO对照组、空载病毒对照组、LY294002组和联合组（LY294002＋Ad—PTEN组）。在U251细胞系中导入LY294002并转染Ad—PTEN病毒后,提取总蛋白,用Westernblotting检测PTEN表达状态及P13K、AKT表达情况;用MTT法检测Ad—PTEN和LY294002对U251生长抑制率、流式细胞仪检测细胞周期、AnnexinV法检测细胞凋亡,观察导人LY294002和转染Ad—PTEN后U251增殖能力的改变;用划痕实验、Transwell实验观察LY294002及Ad—PTEN对U251迁移和侵袭能力的影响;Westernblotting检测P13K／AKT信号通路下游相关蛋白表达水平变化。结果Westernblotting显示：与DMSO组和空载病毒组相比,LY294002组P13K、AKT蛋白表达水平明显降低,联合组（LY294002＋Ad—PTEN）的WEN蛋白明显上调,而P13K、AKT蛋白下降水平比LY294002组更为显著。联合组与LY294002组、空载病毒组、DMSO组相比细胞周期阻滞在G0／G1期;联合组凋亡率比其他三组明显增加;自培养第2天起,联合组细胞增殖速率呈下降趋势。联合组侵袭和迁移细胞的相对数少于LY294002组、空载病毒组和DMSO组。Westernblotting结果证明位于P13K／AKT下游的MMP-2、MMP-9、PCNA、Bcl-2、CyclinD1、NF—KB、FAK蛋白表达水平显著下调。结论小分子抑制剂LY294002能够有效抑制U251中P13K、AKT蛋白的表达,联合转染Ad—PTEN后不仅能提高PTEN蛋白的表达水平,对P13K、AKT的抑制更为显著。在体外实验中,联合Ad—PTEN和LY294002能够有效地通过阻滞细胞周期、减少细胞凋亡来抑制U251的增殖能力,并能够抑制细胞的侵袭和迁移能力,两者联合使用具有正向协同作用。联合Ad—PTEN和LY294002对U251的生长与侵袭的抑制作用与P13K／AKT下游的MMP-2、MMP-9、PCNA、Bcl-2、CyclinD1、NF—KB、FAK蛋白表达水平下调有关。联合腺病毒转染技术和小分子抑制剂调控P13K／AKT信号通路是治疗胶质瘤的新途径。     

脐带间充质干细胞移植治疗大鼠脑缺血损伤

背景：对于缺血性脑卒中至今尚无确实有效的药物治疗,干细胞因其具有高度自我更新能力和多向分化潜能,使其重建中枢神经系统结构与功能成为可能。 目的：观察脐带间充质干细胞移植治疗缺血性脑卒中模型鼠的效果及安全性,并探讨其可能机制。 方法：体外分离人脐带间充质干细胞,移植前以BrdU标记。将SD雄性大鼠制作大脑中动脉闭塞模型后随机分为3组：移植组于造模后第7天,移植脐带间充质干细胞到损伤侧纹状体,PBS组给予等量PBS,模型组大鼠不做处理。 结果与结论：①人脐带间充质干细胞移植组大鼠mNSS评分恢复优于模型组(P < 0.05);模型组mNSS评分在损伤后35 d内恢复速度慢于模型组(P < 0.05),至第56天与模型组比较差异无显著性意义(P > 0.05)。②移植组大鼠损伤中心及周围均可见Brdu染色阳性细胞及与 Nestin、微管缔合蛋白2、胶原纤维酸性蛋白、Ⅷ因子、血管内皮生长因子免疫组织化学双染阳性细胞。表明脐带间充质干细胞可以在体外分离培养,移植后能在鼠宿主脑内存活、分化,促进大脑中动脉闭塞模型鼠神经功能的恢复。推测其机制可能与移植后细胞分化为神经元样和神经胶质细胞样细胞,并分泌或促进宿主分泌神经营养因子、促进新生血管形成有关。关键词：大脑中动脉闭塞;人脐带间充质干细胞;大鼠;胶原纤维酸性蛋白;血管内皮生长因子;神经功能 doi:10.3969/j.issn.1673-8225.2012.19.011     

脊髓损伤大鼠内皮祖细胞与脊髓血管新生

背景：诸多脑损伤实验表明,改善损伤组织缺血缺氧有助于促进损伤组织的修复,并有保护神经功能的目的。 目的：探讨挫伤型脊髓损伤后大鼠外周血中内皮祖细胞的变化及其与创伤灶周围早期血管新生情况的关系。 方法：成年雄性SD大鼠60只,随机数字表法均分为实验组与对照组。实验组采用Allen’s原理制作脊髓损伤模型,对照组只行椎板切除暴露脊髓,不予打击致伤。分别于术前及术后3,6,24,48,72,168 h取大鼠外周血,流式细胞仪检测外周血中内皮祖细胞数量。并于术前及术后1,4,7,14 d处死大鼠取脊髓,采用血管内皮标志物CD31免疫组化染色方法观察创伤区血管的新生情况。 结果与结论：两组大鼠外周血内皮祖细胞水平于伤后3 h均有所下降,6 h开始上升,24 h达高峰,随后逐渐达稳定水平。实验组高峰值明显高于对照组。同时微血管数量呈逐渐增多的趋势。说明大鼠脊髓损伤后,外周血内皮祖细胞数量明显增加,内皮祖细胞参与血管新生和损伤组织的修复,最终促进神经功能恢复。     

Mesenchymal stem cells maintain the microenvironment of central nervous system by regulating the polarization of macrophages/microglia after traumatic brain injury

Mesenchymal stem cells (MSCs), which are regarded as promising candidates for cell replacement therapies, are able to regulate immune responses after traumatic brain injury (TBI). Secondary immune response following the mechanical injury is the essential factor leading to the necrosis and apoptosis of neural cells during and after the cerebral edema has subsided and there is lack of efficient agent that can mitigate such neuroinflammation in the clinical application. By means of three molecular pathways (prostaglandin E2 (PGE2), tumor-necrosis-factor-inducible gene 6 protein (TSG-6), and progesterone receptor (PR) and glucocorticoid receptors (GR)), MSCs induce the activation of macrophages/microglia and drive them polarize into the M2 phenotypes, which inhibits the release of pro-inflammatory cytokines and promotes tissue repair and nerve regeneration. The regulation of MSCs and the polarization of macrophages/microglia are dynamically changing based on the inflammatory environment. Under the stimulation of platelet lysate (PL), MSCs also promote the release of pro-inflammatory cytokines. Meanwhile, the statue of macrophages/microglia exerts significant effects on the survival, proliferation, differentiation and activation of MSCs by changing the niche of cells. They form positive feedback loops in maintaining the homeostasis after TBI to relieving the secondary injury and promoting tissue repair. MSC therapies have obtained great achievements in several central nervous system disease clinical trials, which will accelerate the application of MSCs in TBI treatment.     

Cold water swimming pretreatment reduces cognitive deficits in a rat model of traumatic brain injury

A moderate stress such as cold water swimming can raise the tolerance of the body to potentially injurious events. However, little is known about the mechanism of beneficial effects induced by moderate stress. In this study, we used a classic rat model of traumatic brain injury to test the hypothesis that cold water swimming preconditioning improved the recovery of cognitive functions and explored the mechanisms. Results showed that after traumatic brain injury, pre-conditioned rats(cold water swimming for 3 minutes at 4℃) spent a significantly higher percent of times in the goal quadrant of cold water swim, and escape latencies were shorter than for non-pretreated rats. The number of circulating endothelial progenitor cells was significantly higher in pre-conditioned rats than those without pretreatment at 0, 3, 6 and 24 hours after traumatic brain injury. Immunohistochemical staining and Von Willebrand factor staining demonstrated that the number of CD34~+ stem cells and new blood vessels in the injured hippocampus tissue increased significantly in pre-conditioned rats. These data suggest that pretreatment with cold water swimming could promote the proliferation of endothelial progenitor cells and angiogenesis in the peripheral blood and hippocampus. It also ameliorated cognitive deficits caused by experimental traumatic brain injury.     

Epidemiology of maternal morbidity and mortality

Maternal morbidity and mortality remains a significant health care concern in the United States, as the rates continue to rise despite efforts to improve maternal health. In 2013, the United States ranked 60th in maternal mortality worldwide. We review the definitions, rates, trends, and top causes of severe maternal morbidity and mortality, as well as risk factors for adverse maternal outcomes. We describe current local and national initiatives in place to reduce maternal morbidity and mortality and offer suggestions for future research.     

Cortical Thinning Correlates with Cognitive Change in Multiple Sclerosis but not in Neuromyelitis Optica

Objectives

To compare spatial patterns of cortical thickness alterations in neuromyelitis optica (NMO) and multiple sclerosis (MS); and to investigate the correlations between cortical thinning and clinical variables in NMO and MS.

Methods

We studied 23 patients with NMO, 27 patients with MS and 26 healthy controls (HCs). The global, brain region and vertex-based cortical thickness (CTh) were analysed and compared among the three groups. A general linear model was used to investigate the correlations between cortical thinning and clinical measures.

Results

A limited number of cortical regions in visual cortex were found to be significantly thinner in NMO patients than in HCs. The MS patients exhibited more widespread cortical thinning compared with HCs, and significantly greater cortical thinning in the insula and the parahippocampus compared with NMO. The extent of cortical thinning in several brain regions correlated with cognitive measures in MS, but not in NMO.

Conclusions

Neocortical thinning in NMO mainly affects visual cortex, while MS patients show much more extensive cortical thinning. Cognitive changes are correlated with cortical atrophy in MS not in NMO. The substrates of cognitive changes in MS and NMO could therefore be different.

Key Points

? MS patients show much more extensive cortical thinning than NMO. ? Cortical thinning of insula and parahippocampus particularly distinguishes MS from NMO. ? Cognitive changes are correlated with cortical atrophy in MS but not in NMO.