BACKGROUND： 3, 4-methylenedioxymethamphetamine （MDMA, also known as ＂ecstasy＂） has been shown to exhibit neurotoxic effects on the hippocampus. However, exposure to sub-lethal insults of MDMA has been reported to...BACKGROUND： 3, 4-methylenedioxymethamphetamine （MDMA, also known as ＂ecstasy＂） has been shown to exhibit neurotoxic effects on the hippocampus. However, exposure to sub-lethal insults of MDMA has been reported to result in neuroprotection. OBJECTIVE： To investigate the effects of MDMA on hippocampal neuronal viability, caspase-3 activity, and mRNA expression of the N-methyI-D-aspartate （NMDA） receptor 2B （NR2B） subunit. DESIGN, TIME AND SETTING： A cytological, in vitro experiment was performed at the Department of Anatomy, School of Medicine, and Department of Toxicology-Pharmacology, Faculty of Pharmacy Tehran University of Medical Sciences in 2008. MATERIALS： MDMA was extracted from ecstasy tablets, which were kindly supplied by the Pharmacology-Toxicology Department, Faculty of Pharmacy, Tehran University of Medical Sciences, Iran. METHODS： Hippocampal neurons were isolated from Wistar rats at gestational day 18. Following primary culture, hippocampal neuronal viability was detected by MTT assay. Varying concentrations of MDMA （100-5 000 μmol/L） were used to determine lethal concentration 50 （LC50）, which was around 1 500 μmol/L. Five concentrations of MDMA below 1 500 μmol/L （100, 200, 400, 800, and 1 050 μmol/L） were used for the remaining experiments. After 24 hours of MDMA treatment, NR2B mRNA expression was detected by RT-PCR, and caspase-3 relative activity was determined by colorimetric assay. MAIN OUTCOME MEASURES： Hippocampal neuronal viability, caspase-3 activity, and NR2B mRNA expression. RESULTS： MDMA-induced neurotoxicity in hippocampal neuronal cultures was dose-dependent. In high concentrations （1 000-5 000μmol/L） of MDMA, neuronal viability was decreased. However, with a 500 μmol/L dose of MDMA, neuronal viability was significantly increased （P 〈 0.01）. Low concentrations of MDMA （200 and 400μmol/L） significantly decreased caspase-3 activity （P 〈 0.01）, whereas high concentrations of MDMA significantly increased caspase-3 activity （P 〈 0.01）. NR2B subunit mRNA expression was not significantly altered after 100 -1 050 μmol/L MDMA exposure. CONCLUSION： MDMA exhibits dual effects on hippocampal neuronal viability and caspase-3 activity. These effects are independent from NR2B subunit expression levels.展开更多
A serious threat to cognitive radio networks that sense the spectrum in a cooperative manner is the transmission of false spectrum sensing data by malicious sensor nodes. SNR fluctuations due to wireless channel effec...A serious threat to cognitive radio networks that sense the spectrum in a cooperative manner is the transmission of false spectrum sensing data by malicious sensor nodes. SNR fluctuations due to wireless channel effects complicate handling such attackers even further. This enforces the system to acquire authentication. Actually, the decision maker needs to determine the reliability or trustworthiness of the shared data. In this paper, the evaluation process is considered as an estimation dilemma on a set of evidences obtained through sensor nodes that are coordinated in an underlying wireless sensor network. Then, a likelihood-based computational trust evaluation algorithm is proposed to determine the trustworthiness of each sensor node's data. The proposed procedure just uses the information which is obtained from the sensor nodes without any presumptions about node’s reliability. Numerical results confirm the effectiveness of the algorithm in eliminating malicious nodes or faulty nodes which are not necessarily conscious attackers.展开更多
基金Supported by: the Deputy of Research in Tehran University of Medical Sciences
文摘BACKGROUND： 3, 4-methylenedioxymethamphetamine （MDMA, also known as ＂ecstasy＂） has been shown to exhibit neurotoxic effects on the hippocampus. However, exposure to sub-lethal insults of MDMA has been reported to result in neuroprotection. OBJECTIVE： To investigate the effects of MDMA on hippocampal neuronal viability, caspase-3 activity, and mRNA expression of the N-methyI-D-aspartate （NMDA） receptor 2B （NR2B） subunit. DESIGN, TIME AND SETTING： A cytological, in vitro experiment was performed at the Department of Anatomy, School of Medicine, and Department of Toxicology-Pharmacology, Faculty of Pharmacy Tehran University of Medical Sciences in 2008. MATERIALS： MDMA was extracted from ecstasy tablets, which were kindly supplied by the Pharmacology-Toxicology Department, Faculty of Pharmacy, Tehran University of Medical Sciences, Iran. METHODS： Hippocampal neurons were isolated from Wistar rats at gestational day 18. Following primary culture, hippocampal neuronal viability was detected by MTT assay. Varying concentrations of MDMA （100-5 000 μmol/L） were used to determine lethal concentration 50 （LC50）, which was around 1 500 μmol/L. Five concentrations of MDMA below 1 500 μmol/L （100, 200, 400, 800, and 1 050 μmol/L） were used for the remaining experiments. After 24 hours of MDMA treatment, NR2B mRNA expression was detected by RT-PCR, and caspase-3 relative activity was determined by colorimetric assay. MAIN OUTCOME MEASURES： Hippocampal neuronal viability, caspase-3 activity, and NR2B mRNA expression. RESULTS： MDMA-induced neurotoxicity in hippocampal neuronal cultures was dose-dependent. In high concentrations （1 000-5 000μmol/L） of MDMA, neuronal viability was decreased. However, with a 500 μmol/L dose of MDMA, neuronal viability was significantly increased （P 〈 0.01）. Low concentrations of MDMA （200 and 400μmol/L） significantly decreased caspase-3 activity （P 〈 0.01）, whereas high concentrations of MDMA significantly increased caspase-3 activity （P 〈 0.01）. NR2B subunit mRNA expression was not significantly altered after 100 -1 050 μmol/L MDMA exposure. CONCLUSION： MDMA exhibits dual effects on hippocampal neuronal viability and caspase-3 activity. These effects are independent from NR2B subunit expression levels.
文摘A serious threat to cognitive radio networks that sense the spectrum in a cooperative manner is the transmission of false spectrum sensing data by malicious sensor nodes. SNR fluctuations due to wireless channel effects complicate handling such attackers even further. This enforces the system to acquire authentication. Actually, the decision maker needs to determine the reliability or trustworthiness of the shared data. In this paper, the evaluation process is considered as an estimation dilemma on a set of evidences obtained through sensor nodes that are coordinated in an underlying wireless sensor network. Then, a likelihood-based computational trust evaluation algorithm is proposed to determine the trustworthiness of each sensor node's data. The proposed procedure just uses the information which is obtained from the sensor nodes without any presumptions about node’s reliability. Numerical results confirm the effectiveness of the algorithm in eliminating malicious nodes or faulty nodes which are not necessarily conscious attackers.
