Ischemic postconditioning exerts neuroprotective effect through negatively regulating PI3K/Akt2 signaling pathway by microRNA-124.

Ischemic stroke is a serious threat to human life and health, which is often accompanied by cerebral ischemia-reperfusion (I/R) injury in clinic. Ischemic postconditioning (IPostC) is a short period of mild non-fatal ischemia in the early stage of cerebral I/R injury. However, there are few reports about the protective effect of IPostC. In the present study, we investigated the neuroprotective effect of IPostC in a mice model of ischemia induced by the middle cerebral artery occlusion (MCAO). MicroRNA-124(miR-124) is a small RNA highly expressed in the brain. Several studies have shown that miR-124 is significantly decreased in IPostC. Therefore, we hypothesize that IPostC may play an important role by downregulating the expression of miR-124. Mice were treated with cerebral I/R and IPostC treatment on the basis of MCAO. The results showed that IPostC significantly reduced neurobehavioral deficits and decreased brain infarct volume. Moreover, we also found that inhibiting miR-124 effectively reduced neurons/cells apoptosis in vivo and vitro. In addition, western blot analysis of apoptosis-related proteins and PI3K/Akt2 signaling pathway proteins showed that downregulation of miR-124 significantly decreased the expression of Caspase-3 and BAX, and increased the expression of anti-apoptotic protein Bcl-2. Inhibition of miR-124 also increase PI3K/Akt/mTOR signaling pathway, thus inhibiting cell apoptosis and autophagy. However, overexpression of miR-124 weakens the protective effect of IPostC. These observations suggest that IPostC exerts its neuroprotective effect through negatively regulating PI3K/Akt2 signaling pathway by miR-124.

Theoretical Study on the Aggregation of Copper Clusters on a Liquid Surface.

The ground state structures of copper clusters with different sizes along with their aggregation have been systematic investigated using Amsterdam Density Functional (ADF) and Atomistix ToolKit (ATK) programs. On the basis of geometry optimization, some Cu clusters with more stable structures which were not reported previously have been revealed. In most cases, these Cu clusters prefer to adopt icosahedral structures which originate from the 13-atom icosahedron. It has also been demonstrated that the interaction between two Cu clusters is anisotropic, which is attributed to their charge distribution, especially the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of Cu clusters. Moreover, we have carried out the simulation of Cu clusters aggregation on the silicone oil substrate by means of Monte Carlo (MC) method, which shows good consistence with our previous experimental studies.

Health correlates, addictive behaviors, and peer victimization among adolescents in China.

BACKGROUND: Peer victimization has been recognized as a common social problem affecting children and adolescents in all parts of the world. This study aims to examine the prevalence of different types of peer victimization and to evaluate the associations between peer victimization and health correlates. METHODS: Using a large population sample of 18,341 adolescents aged 15-17 years from 6 cities in China, this study estimated the prevalence of different types of peer victimization, addictive behaviors, and health-related variables with self-administrated questionnaires. A three-phase logistical regression analysis was conducted to investigate the associations between peer victimization and addictive behaviors as well as health-related factors among adolescents. RESULTS: A total of 42.9% of the surveyed Chinese adolescents have been bullied by peers, with boys reporting higher rate on overt victimization (36.9%) and girls on relational forms (33.9%). School environment (34.7%) was the most frequent scene of peer violence, followed by neighborhood, family, and internet. Addictive behaviors except substance abuse were found related to higher possibility of peer victimization (aOR 1.21-1.73, P < 0.001). Peer victimization was significantly associated with more depressive symptoms, post-traumatic stress disorder symptoms, and suicide ideation and deliberate self-harm (aOR 1.05-2.27, P < 0.001), and poorer self-esteem and health-related quality of life (aOR 0.95-0.97, P < 0.001). CONCLUSION: Possible explanations of the associations found in this study are discussed and implications for future services are raised.

Neuroprotection induced by post-conditioning following ischemia/reperfusion in mice is associated with altered microRNA expression.

Ischemic preconditioning and ischemic postconditioning (IPostC) represent promising strategies to reduce ischemia-reperfusion (I/R) injury and attenuate the lethal ischemic damage following stroke. However, the mechanism underlying this attenuation remains to be elucidated. It was hypothesized that alterations in microRNA (miRNA) expression in the cerebral cortex and hippocampus of mice following I/R is associated with the functional improvement induced by IPostC. Behavioral changes were assessed in a mouse model of I/R in the absence or presence of IPostC, followed by microarray analyses to investigate the expressional alterations of miRNAs in the cerebral cortex and hippocampus of mice. The results of the present study revealed that IPostC abrogated the neurological impairment and hippocampus­associated cognitive deficits induced by I/R, and upregulated or downregulated the expression levels of numerous miRNAs. Furthermore, the upregulation of miR­19a, and the downregulation of miR­1, let­7f and miR­124 expression levels following IPostC was confirmed utilizing reverse transcription­quantitative polymerase chain reaction. The results of the present study demonstrated that alterations in miRNA expression in the cerebral cortex and hippocampus of mice following I/R was associated with the neuroprotection induced by IPostC.

Mature brain-derived neurotrophic factor and its receptor TrkB are upregulated in human glioma tissues.

There are two forms of brain-derived neurotrophic factor (BDNF), precursor of BDNF (proBDNF) and mature BDNF, which each exert opposing effects through two different transmembrane receptor signaling systems, consisting of p75 neurotrophin receptor (p75NTR) and tyrosine receptor kinase B (TrkB). Previous studies have demonstrated that proBDNF promotes cell death and inhibits the growth and migration of C6 glioma cells through p75NTR in vitro, while mature BDNF has opposite effects on C6 glioma cells. It is hypothesized that mature BDNF is essential in the development of malignancy in gliomas. However, histological data obtained in previous studies were unable distinguish mature BDNF from proBDNF due to the lack of specific antibodies. The present study investigated the expression of mature BDNF using a specific sheep monoclonal anti-mature BDNF antibody in 42 human glioma tissues of different grades and 10 control tissues. The correlation between mature BDNF and TrkB was analyzed. Mature BDNF expression was significantly increased in high-grade gliomas, and was positively correlated with the malignancy of the tumor and TrkB receptor expression. The present data have demonstrated that increased levels of mature BDNF contribute markedly to the development of malignancy of human gliomas through the primary BDNF receptor TrkB.

Spontaneous running wheel improves cognitive functions of mouse associated with miRNA expressional alteration in hippocampus following traumatic brain injury.

Traumatic brain injury (TBI) is an insult to the brain that results in impairments of cognitive and physical functioning. Both of human research and animal studies demonstrate that spontaneous exercise can facilitate neuronal plasticity and improve cognitive function in normal or TBI rodent models. However, the possible mechanisms underlying are still not well known. We postulated that spontaneous running wheel (RW) altered microRNA (miRNA) expressions in hippocampus of mice following TBI, which might be associated with the improvement in cognitive functions. In the present study, acquisition of spatial learning and memory retention was assessed by using the Morris water maze (MWM) test on days 15 post RW exercise. Then, microarray analyses in miRNA files were employed, and the expressional changes of miRNAs in the hippocampus of mice were detected. The results showed that spontaneous RW exercise (i) recovered the hippocampus-related cognitive deficits induced by TBI, (ii) altered hippocampal expressions of miRNAs in both of sham and TBI mice, and (iii) miR-21 or miR-34a was associated with the recovery process. The present results indicated that an epigenetic mechanism might be involved in voluntary exercise-induced cognitive improvement of mice that suffered from TBI.

Mature BDNF promotes the growth of glioma cells in vitro.

High-grade glioma is incurable and is associated with a short survival time and a poor prognosis. There are two forms of brain-derived neurotrophic factor (BDNF), proBDNF and mature BDNF, which exert opposite effects. Their diverse actions are mediated through two different transmembrane receptor signalling systems: p75NTR and TrkB. The important roles of the BDNF/TrkB signalling system in tumour cell proliferation and survival have been demonstrated. However, few studies have been able to distinguish mature BDNF from proBDNF due to the limitation of specific antibodies. Using specific proBDNF antibodies, we demonstrated that the proBDNF/p75NTR pathway appears to inhibit malignant glioma cell growth and migration. In the present study using specific mature BDNF antibodies, we found that mature BDNF inhibited C6 glioma cell apoptosis and increased cell growth and migration in vitro. Our data suggest that the counterbalance between mature BDNF and proBDNF may regulate tumour growth.

ProBDNF and its receptors are upregulated in glioma and inhibit the growth of glioma cells in vitro.

BACKGROUND: High-grade glioma is incurable, with a short survival time and poor prognosis. The increased expression of p75 neurotrophin receptor (NTR) is a characteristic of high-grade glioma, but the potential significance of increased p75NTR in this tumor is not fully understood. Since p75NTR is the receptor for the precursor of brain-derived neurotrophic factor (proBDNF), it is suggested that proBDNF may have an impact on glioma. METHODS: In this study we investigated the expression of proBDNF and its receptors p75NTR and sortilin in 52 cases of human glioma and 13 cases of controls by immunochemistry, quantitative real-time PCR, and Western blot methods. Using C6 glioma cells as a model, we investigated the roles of proBDNF on C6 glioma cell differentiation, growth, apoptosis, and migration in vitro. RESULTS: We found that the expression levels of proBDNF, p75NTR, and sortilin were significantly increased in high-grade glioma and were positively correlated with the malignancy of the tumor. We also observed that tumors expressed proBDNF, p75NTR, and sortilin in the same cells with different subcellular distributions, suggesting an autocrine or paracrine loop. The ratio of proBDNF to mature BDNF was decreased in high-grade glioma tissues and was negatively correlated with tumor grade. Using C6 glioma cells as a model, we found that proBDNF increased apoptosis and differentiation and decreased cell growth and migration in vitro via p75NTR. CONCLUSIONS: Our data indicate that proBDNF and its receptors are upregulated in high-grade glioma and might play an inhibitory effect on glioma.

[Expression of programmed cell death 5 and apoptosis during atrophy of the parotid gland cells].

OBJECTIVE: To investigate the expression and relationship of programmed cell death 5 (PDCD5) and cell apoptosis in the parotid gland after leading duct ligation in rat and elucidate the role of PDCD5 on the atophy of parotid gland. METHODS: The Wistar rat model of leading duct ligation was established, and the samples of parotid gland were obtained from different time point (0, 1, 3, 5, 7, 14, 21, 30, 60, 90 and 120 d). The expression of PDCD5 protein was examined by immunohistochemistry. Cell apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). RESULTS: The distribution of PDCD5 protein in normal parotid was in cytoplasm with uniformity. The expression of PDCD5 protein was significantly increased and reached the peak at 3 d (1.261 ± 0.048) following main duct ligation. PDCD5 was located both in cytoplasm and nuclear of parotid gland cells. The PDCD5 density in acinar cells was higher than that in duct cells at day 1 and 3 after duct ligation (P < 0.01). The apoptotic cells were obviously upregulated at 3 d after duct ligation. The apoptosis index observed in acinar cells [(21.750 ± 0.119)%] was more than that in duct cells [(5.720 ± 0.205)%]. The difference of apoptosis index between acinar cells and duct cells was statistically significant (P < 0.01). The increased PDCD5 levels were positively correlated with cell apoptosis induced by duct ligation. CONCLUSIONS: The expression of PDCD5 is associated with the atophy of the parotid gland after rat parotid duct ligation, indicating that PDCD5 might play an important role in apoptotic pathways after parotid duct ligation.

[Studies on the chemical constituents from the flowers of Ophiopogon japonicus].

OBJECTIVE: To study the chemical constituents from the flowers of Ophiopogon japonicus. METHODS: Column chromatography and spectral analysis were used to isolate and identify the constituents. RESULTS: Eleven compounds were obtained and identified as beta-sitosterol (I), diosgenin (II), daucosterol (III), ophiopogonin C' (IV), dioscin (V), 7-dihy-droxy-6-methyl-3-(4'-hydroxybenzyl) chroman-4-one(VI), luteolin (VII), kaempferol-3-O-beta-D-glucopyranosides (VIII), kaempferol-3-O-(6"-tigloyl) -beta-D-glucopyranosides (IX), kaempferol-3-O-(6"-acetyl) -beta-D-glucopyranosides (X), glucose (XI). CONCLUSION: Eleven compounds are obtained from the flowers of O. japonicus for the first time. Compond VI is isolated as a simple substance compound of O. japonicus for the first time. Componds VII, VIII, IX and X are isolated from this genus for the first time.

[Dynamic observation of applying repairing laryngeal mucosal defect with heterogeneous acellular dermal matrix].

OBJECTIVE: To study the clinical effect of heterogeneity (cattle) acellular dunal matrix in repairing mucosa defect in laryngeal surgery. METHODS: Eighteen cancer patients with mucosa defect in central vocal area accepted treatment with heterogeneity acellular dunal matrix after surgery. There were two methods to repair mucosa defect. One was simple use of acellular dunal matrix, the second was combined use of acellular dunal matrix and muscle lamella or muscle and tendon film lamella. 18 cases had cancer in central vocal area: T2N0M0 (8), T3N1M0 (5), T3N2M0 (4), T4N2M0 (1). All were squamous cell carcinoma. Ten cancer patients accepted radiation after surgery. The radiotherapy volume was 60-80 Gy. After the operation, the patients were checked by fibrolaryngoscope four or five times after half a year, observing the dynamic development. RESULTS: All 18 patients were healed, rechecked by endoscope after 0.5-6 months, heterogeneity acellular dunal matrix mingled with mucosa within 30-60 d, no allergy and irritation were found. The laryngeal function, including breathing, pronouncing and swallowing, was recovered. The survival rate (1 year) was 100%, and 10 patients survived after 2 years. After radiotherapy, the process of recovery was not affected. CONCLUSIONS: Heterogeneity acellular dunal matrix can be easily obtained and it is a new method to repair mucosa defect. The operative procedure is easy to perform and worthwhile to use clinically.

Effects of NT-4 gene modified fibroblasts transplanted into AD rats.

It is well known that fibroblasts can act as a cell vector to express functional protein, like neurotrophin-4 (NT-4). The present study evaluated the effect of NT-4 gene modified fibroblasts grafted into the hippocampus of AD rat model. AD rats were reproduced by bilateral transection of the hippocampal fimbria-fornix. The transplanted fibroblasts steadily expressed NT-4 proteins at least 2 months after transplantation. This correlated with a significant rescue in the number of cholinergic neurons in the host hippocampus. Morris water maze tests demonstrated significant improvements in learning and memory, especially in rats receiving NT-4-modified fibroblasts. The present results showed that NT-4 gene modified fibroblasts could provide a long-term and steady expression of NT-4, and it significantly improved the behavior of AD rats. These findings should have important clinical applications in providing a long-term NT-4 Secretion for the treatment of AD.

[Distribution and change of NGF, BDNF and NT3 in the hippocampus of rat with AD].

OBJECTIVE: To investigate the distribution and change of NGF, BDNF and NT3 in hippocampus of rat with Alzheimer disease(AD) by immunohistochemistry. METHODS: AD model was established by injecting beta amyloid protein into the hippocampus of rat. The rats were killed ten days after injection. The hippocampus sections were made coronally on a freezing microtome. Brain sections were processed by immunohistochemical procedure with molocloned antibodies against NGF, BDNF and NT3. The number of positive neurons of NGF, BDNF and NT3 was counted and analyzed statistically. RESULTS: It was found that the number of NGF positive neurons increased and the immunostaining intensity became stronger as compared with the control (P<0.01). The number of BDNF positive neurons decreased and the immunostaining intensity weakened (P<0.01). There Our was no change in the number and immunostaining intensity of NT3 positive neurons (P>0.05). CONCLUSION: results show that NGF, BDNF, NT3 have experienced different changes in hippocampus of rat with AD, suggesting that they play different roles in the course of AD and bear relation to the physiological function of cholinergic neurons in hippocampus of rat with AD. In particular, BDNF exerts crucial effect on the degeneration of neuronal function in the hippocampus of rat with AD.