Differentiation renders susceptibility to excitotoxicity in HT22 neurons

HT22 is an immortalized mouse hippocampal neuronal cell line that does not express cholinergic and glutamate receptors like mature hippocampal neurons in vivo.This in part prevents its use as a model for mature hippocampal neurons in memory-related studies.We now report that HT22 cells were appropriately induced to differentiate and possess properties similar to those of mature hippocampal neurons in vivo,such as becoming more glutamate-receptive and excitatory.Results showed that sensitivity of HT22 cells to glutamate-induced toxicity changed dramatically when comparing undifferentiated with differentiated cells,with the half-effective concentration for differentiated cells reducing approximately two orders of magnitude.Moreover,glutamate-induced toxicity in differentiated cells,but not undifferentiated cells,was inhibited by the N-methyl-Daspartate receptor antagonists MK-801 and memantine.Evidently,differentiated HT22 cells expressed N-methyl-D-aspartate receptors,while undifferentiated cells did not.Our experimental findings indicated that differentiation is important for immortalized cell lines to render post-mitotic neuronal properties,and that differentiated HT22 neurons represent a better model of hippocampal neurons than undifferentiated cells.     

Is therapeutic hypothermia beneficial for pediatric patients with traumatic brain injury? A meta-analysis

Purpose

Hypothermia therapy shows its unique potential for reducing mortality in animal study and improving neurologic outcome in patients with traumatic brain injury. However, therapeutic hypothermia for pediatric traumatic brain injury remains a controversial issue. To determine the effectiveness and safety of hypothermia treatment for pediatric traumatic brain injury patients, we conducted this meta-analysis.

Patients and methods

We analyzed the data from MEDLINE, Pubmed, EMBASE, and Cochrane Library by electronic searching. No limitation of language was selected for analysis. We extracted the mortality and adverse events from the published trials.

Results

Six clinical trials and 366 pediatric patients met our inclusion criteria. Pediatric patients with traumatic brain injury treated with hypothermia had more unfavorable outcome than those in the normothermia group (RR 1.73, 95 % CI 1.06 to 2.84), and this increased risk is statistically significant. Patients with therapeutic hypothermia are slightly likely to be induced by cardiac arrhythmia, and the likelihood is also significant (RR 2.57, 95 % CI 1.01 to 6.54). Risk of pneumonia has no statistical difference between normothermia and hypothermia arms (RR 0.90, 95 % CI 0.73 to 1.12). Two of the included trials have reported their detail randomization assignment.

Conclusions

Hypothermia may slightly increase the risk of mortality in children with traumatic brain injury and the ratio of cardiac arrhythmia after this hypothermia therapy is slightly higher than that in normothermia groups. In the future, more randomized controlled trials and multicenter studies on the mechanism of therapeutic hypothermia are required.     

Results of phase II levetiracetam trial following acute head injury in children at risk for posttraumatic epilepsy

Posttraumatic seizures develop in up to 20% of children following severe traumatic brain injury (TBI). Children ages 6–17 years with one or more risk factors for the development of posttraumatic epilepsy, including presence of intracranial hemorrhage, depressed skull fracture, penetrating injury, or occurrence of posttraumatic seizure were recruited into this phase II study. Treatment subjects received levetiracetam 55 mg/kg/day, b.i.d., for 30 days, starting within 8 h postinjury. The recruitment goal was 20 treated patients. Twenty patients who presented within 8–24 h post‐TBI and otherwise met eligibility criteria were recruited for observation. Follow‐up was for 2 years. Forty‐five patients screened within 8 h of head injury met eligibility criteria and 20 were recruited into the treatment arm. The most common risk factor present for pediatric inclusion following TBI was an immediate seizure. Medication compliance was 95%. No patients died; 19 of 20 treatment patients were retained and one observation patient was lost to follow‐up. The most common severe adverse events in treatment subjects were headache, fatigue, drowsiness, and irritability. There was no higher incidence of infection, mood changes, or behavior problems among treatment subjects compared to observation subjects. Only 1 (2.5%) of 40 subjects developed posttraumatic epilepsy (defined as seizures >7 days after trauma). This study demonstrates the feasibility of a pediatric posttraumatic epilepsy prevention study in an at‐risk traumatic brain injury population. Levetiracetam was safe and well tolerated in this population. This study sets the stage for implementation of a prospective study to prevent posttraumatic epilepsy in an at‐risk population.     

Molecular mechanisms underlying the effects of acupuncture on neuropathic pain

Acupuncture has been used to treat neuropathic pain for a long time, but its mechanisms of action remain unknown. In this study, we observed the effects of electroacupuncture and manual acu-puncture on neuropathic pain and on ephrin-B/EphB signaling in rats models of chronic constriction injury-induced neuropathic pain. The results showed that manual acupuncture and elec-puncture significantly reduced mechanical hypersensitivity following chronic constriction injury, es-pecially electroacupuncture treatment. Real-time PCR results revealed that ephrin-B1/B3 and EphB1/B2 mRNA expression levels were significantly increased in the spinal dorsal horns of chronic constriction injury rats. Electroacupuncture and manual acupuncture suppressed the high sion of ephrin-B1 mRNA, and elevated EphB3/B4 mRNA expression. Electroacupuncture signifi-cantly enhanced the mRNA expression of ephrin-B3 and EphB3/B6 in the dorsal horns of neuro-pathic pain rats. Western blot results revealed that electroacupuncture in particular, and manual acupuncture, significantly up-regulated ephrin-B3 protein levels in rat spinal dorsal horns. The re-sults of this study suggest that acupuncture could activate ephrin-B/EphB signaling in neuropathic pain rats and improve neurological function.     

傅里叶域OCT对不同屈光状态非青光眼青年人群神经节细胞复合体的观察

目的：应用傅里叶域光学相干断层扫描（OCT）观察不同屈光状态非青光眼青年人群神经节细胞复合 体（GCC）形态特征,探讨眼轴长度（AL）与GCC的变化规律。方法：病例对照研究。基于AL纳入非 高度近视94眼和高度近视62眼,使用OCT测量其黄斑区GCC厚度、上/下半区GCC（GCC-S/GCC-I） 厚度、局部丢失体积（FLV）和整体丢失体积（GLV）并计算FLV与GLV比值（FGR）。使用线性回归 分析各指标与AL的相关性;采用受试者工作特征曲线下面积（AUC）评价2组间各指标差异及界值。 结果：线性回归结果示受试者GCC厚度（β=-0.698,P<0.001）、GCC-S厚度（β=-0.693,P<0.001）、 GCC-I厚度（β=-0.672,P<0.001）随AL延长而下降;FLV不随AL变化而变化（β=0.115,P=0.155）; GLV随AL延长而增高（β=0.346,P<0.001）,FGR随AL延长而降低（β=-0.473,P<0.001）。独立样 本t检验结果示高度近视组和非高度近视组间GCC厚度（t=7.398,P<0.001）、GCC-S厚度（t=7.313, P<0.001）、GCC-I厚度（t=7.022,P<0.001）、GLV（t=-3.482,P=0.001）及FGR（t=5.361,P<0.001） 差异有统计学意义,FLV差异无统计学意义（t=1.057,P=0.292）。AUCGCC为0.809（P<0.001）,最佳 界值99 μm;AUCGLV为0.689（P<0.001）,最佳界值3.42;AUCFGR为0.711（P<0.001）,最佳界值0.44; AUCFLV为0.546（P=0.330）。结论：OCT可观察不同屈光状态非青光眼青年人群GCC,平均GCC厚度、 GCC-S厚度、GCC-I厚度、GLV和FGR随AL变化而发生改变。     

Levels of beta-secretase (BACE1) in cerebrospinal fluid as a predictor of risk in mild cognitive impairment

CONTEXT: Elevated beta-secretase (beta-site amyloid precursor protein-cleaving enzyme 1 [BACE1]) activity has been found in the brains of patients with sporadic Alzheimer disease (AD) compared with controls. Now we are particularly interested in whether BACE1 can be identified in the cerebrospinal fluid (CSF) of patients with mild cognitive impairment (MCI), a population at high risk for AD. The possible presence of BACE1 in the CSF of patients with AD and MCI has so far gone unreported. OBJECTIVE: To examine whether BACE1 can be identified in the CSF of patients with MCI. DESIGN: We evaluated CSF BACE1 levels using 2 sandwich enzyme-linked immunosorbent assays, BACE1 enzymatic activities by means of synthetic fluorescence substrate, and total amyloid-beta peptide levels using a sandwich enzyme-linked immunosorbent assay. SETTING: Two independent research centers. PARTICIPANTS: Eighty patients with sporadic AD, 59 patients with MCI, and 69 controls. MAIN OUTCOME MEASURES: BACE1 levels and enzymatic activities and amyloid-beta peptide levels. RESULTS: Increased CSF levels of BACE1 protein were associated with increased risk ratios (RRs) for patients with MCI compared with controls (RR, 2.08; 95% confidence interval [CI], 1.58-2.58) and patients with AD (RR, 1.65; 95% CI, 1.19-2.03). Similarly, patients with MCI showed increased levels of BACE1 activity compared with controls (RR, 2.17; 95% CI, 1.66-2.71) and patients with AD (RR, 3.71; 95% CI, 2.74-4.36). For total amyloid-beta peptide and tau, increased CSF levels were associated with a higher risk of MCI compared with controls. The BACE1 activity was significantly correlated with BACE1 protein level (rho = 0.23; P<.001) and amyloid-beta peptide level (rho = 0.39; P<.001), with amyloid-beta peptide correlated with BACE1 protein level (rho = 0.30; P<.001). CONCLUSION: Significant elevation of BACE1 levels and activity in CSF is an indicator of MCI, which could be an early stage of AD.     

DCPIB,A Specific Inhibitor of Volume-Regulated Anion Channels (VRACs), Inhibits Astrocyte Proliferation and Cell Cycle Progression Via G1/S Arrest

Volume-regulated anion channels (VRACs) are involved in regulating the proliferation and cell cycle progression of a number of cell types. However, little is known about its role on astrocyte proliferation, although numerous VRACs were reported to play important roles in astrocytic neurotransmitters release during swelling. In the present study, we demonstrated that VRAC inhibition by 4-(2-butyl-6,7-dichloro-2-cyclopentyl-indan-1-on-5-yl) oxobutyric acid (DCPIB) can attenuate astrocyte proliferation and DNA synthesis in vitro. Simultaneously, Western blots showed that VRAC inhibition led to a decrease in CDK 4 and cyclin D1 expression accompanied with an increase in p27 expression, which caused the proliferating astrocytes arrested at the G1/S checkpoint. Furthermore, we showed that DCPIB-induced astrocyte proliferation inhibition was modulated through the ERK signaling cascade. These observations demonstrated that VRACs play essential roles in the proliferation of astrocyte.     

Spinal P2X(7) receptor mediates microglia activation-induced neuropathic pain in the sciatic nerve injury rat model

P2X₇ receptor is an important member of ATP-sensitive ionotropic P2X receptors family, which includes seven receptor subtypes (P2X₁-P2X₇). Recent evidence indicates that P2X₇R participates in the onset and persistence of neuropathic pain. In tetanic stimulation of the sciatic nerve model, P2X₇R was involved in the activation of microglia, but whether this happens in other neuropathic pain models remains unclear. In this study we used immunohistochemistry and Western blot to explore the relationship of P2X₇R expression with microglia activation, and with mechanical allodynia and thermal hypersensitivity in the chronic constriction of the sciatic nerve (CCI) rat model. The results show that following nerve ligature, mechanical allodynia and thermal hypersensitivity were developed within 3 days (d), peaked at 14 d and persisted for 21 d on the injured side. P2X₇R levels in the ipsilateral L4-6 spinal cord were increased markedly after injury and the highest levels were observed on day 14, significant difference was observed at I-IV layers of the dorsal horn. The change in P2X₇R levels in the spinal cord was consistent with the development of mechanical allodynia and thermal hypersensitivity. Intrathecal administration of the P2X₇R antagonist Brilliant Blue G (BBG) reversed CCI-induced mechanical allodynia and thermal hypersensitivity. Double-labeled immunofluorescence showed that P2X₇R expression were restricted to microglia, spinal microglia were activated after nerve injury, which was inhibited by BBG. These results indicated that spinal P2X₇R mediate microglia activation, this process may play an important role in development of mechanical allodynia and thermal hypersensitivity in CCI model.