ABSTRACT
BACKGROUND: The event of paroxysmal deplorizing shift (PDS) is the cellular hallmark of brain neurons of epileptiform activities. Its development used to be considered to be related to abnormal synaptic interactions. Recertly, the intrinsic nature of PDS has received more attention.OBJECTIVE: To observe the characteristics of epileptiform activities of rat hippocampal CA1 pyramidal neurons induced by low-dosage veratridine and investigate its possible ion mechanism.DESIGN: An exploratory and observational trial.SETTING: Institute of Neuroscience, Fourth Military Medical University of Chinese PLA.MATERIALS: This study was conducted at the Institute of Neuroscience,Fourth Military Medical University of Chinese PLA, from October 2002 to October 2004. Forty healthy SD rats of 14 days old were selected. Drugs were provided from Tianjin Drug Company and Sigma Company.METHODS: Rats were anesthetized by intraperitoneal injection, and their brain was removed and cut into slices. Epileptiform activities were induced by 0.5 μ mol/L veratridine. Then 80 nmol/L tetrodotoxin was added into the perfused solution on 6 cerebral slices, and 5 μmol/L phenytoin was used on another 5 cerebral slices. The electrophysiological characteristics of the cells under the effect of different kinds of drugs were observed.MAIN OUTCOME MEASURE: Discharge pattern of cells and tetrodotoxin-sensitive sodium currents under voltage-clamp configuration through Ⅰ-Ⅴ reaction.RESULTS: After perfusion of 0.5 μmol/L veratridine, the rat pyramidal neurons in CA1 area displayed relatively fixed-mode of runs of PDS bursting,followed by the hyperpolarization of cell membrane. Such epileptiform activities were blocked either by 80 nmol/L tetrodotoxin or 5 μnol/L phenytoin. The tetrodotoxin-sensitive sodium currents in epileptic neurons and normal controls under voltage-clamp configuration on holding potential of -55 rmV, -60 rmV, -65 mV. This shows that persistent sodium currents could be improved by low-dosage veratridine in a voltage-dependent manner.CONCLUSION: Low-dosage veratridine may induce runs of PDS like epileptiform activities on rat CA1 pyramidal neurons. Such changes can be blocked by low-dosage tetrodotoxin or phenytoin. Its ion mechanism may be related to persistent sodium currents.
ABSTRACT
Aim To observe the production of anti-idiotypic antibodies directed against AK auto Ab in the rabbit sera after long-term, high dose allogenic AK auto Ab injection. Methods Allogenic AK auto Ab (5mg/kg)was injected intramuscularly to rabbit once every other day for 90 days. Anti-idiotypic antibodies in rabbit sera were detected by ELISA. Results Rabbits injected with AK auto Ab generated anti-idiotypic antibodies that could react to F(ab′ )2 of AK auto Ab. The titers of anti-idiotypic antibodies reached the highest levels at 4 weeks after the administration of AK auto Ab and then gradually decreased. Conclusion Rabbits could be induced to form immune tolerance when high-does allogenic AK auto Ab is administrated for long-term.
ABSTRACT
Objective To construct and express human ScFv against keratin in E.coli,and identify its binding activity with antigens and antigenic specificity.Methods By genetic engineering technology,human anti-keratin ScFv was constructed from Fab fragment selected from established semi-synthetic phage antibody library.The binding activity with antigens and antigenic specificity of expressed products were i-dentified by ELISA.Results Results of DNA sequence analysis showed that nucleotide sequence of V?and VH of ScFv gene was similar to that of V?and VH of Fab gene,suggesting that there was no mutation in the construction of ScFv.The soluble anti-keratin ScFv was found to have a good antigenic specificity as well as excellent binding activity with target antigens by ELISA.However,the binding activity of ScFv with keratin was lower than that of Fab.Conclusions The successful expression and identification of human an-ti-keratin ScFv might lay a solid foundation for further observation of biological activities of anti-keratin au-toantibody,manufacture of genetic-engineering anti-keratin products,and promotion of clinical application of genetic-engineering anti-keratin antibodies.