高效液相色谱法测定人血清和尿中盐酸青藤碱浓度及药代动力学研究

用RP-HPLC法,以三唑仑为内标,反相C₁₈为分析柱,乙腈—0.01mol·L^-1磷酸二氢钠—四甲基乙二胺(46∶54∶0.22v/v)为流动相,磷酸调至pH6.9,检测波长263nm,测定血清和尿中盐酸青藤碱浓度,线性范围分别为6～480ng·mL^-1和0.06～3μg·mL^-1,平均回收率75.88%和91.35%,日内日间误差小于5%,最低检测浓度血清4ng·mL^-1,尿40ng·mL^-1。8名健康男性志愿者单次口服盐酸青藤碱片80mg,测定血清及尿浓度,该药符合二室开放模型,体内消除符合一级动力学消除过程,主要药代动力学参数:T_1/2α0.791±0.491h,T_1/2β9.397±2.425h,T_{max 1.040±0.274h,Cmax246.604±71.165ng·mL^-1,AUC 2651.158±1039.050ng·h·mL^-1,CL 0.033±0.01ng·mL^-1。}     

Critical-state dynamics of avalanches and oscillations jointly emerge from balanced excitation/inhibition in neuronal networks

Criticality has gained widespread interest in neuroscience as an attractive framework for understanding the character and functional implications of variability in brain activity. The metastability of critical systems maximizes their dynamic range, storage capacity, and computational power. Power-law scaling-a hallmark of criticality-has been observed on different levels, e.g., in the distribution of neuronal avalanches in vitro and in vivo, but also in the decay of temporal correlations in behavioral performance and ongoing oscillations in humans. An unresolved issue is whether power-law scaling on different organizational levels in the brain-and possibly in other hierarchically organized systems-can be related. Here, we show that critical-state dynamics of avalanches and oscillations jointly emerge in a neuronal network model when excitation and inhibition is balanced. The oscillatory activity of the model was qualitatively similar to what is typically observed in recordings of human resting-state MEG. We propose that homeostatic plasticity mechanisms tune this balance in healthy brain networks, and that it is essential for critical behavior on multiple levels of neuronal organization with ensuing functional benefits. Based on our network model, we introduce a concept of multi-level criticality in which power-law scaling can emerge on multiple time scales in oscillating networks.     

Pathophysiological mechanisms of dominant and recessive KVLQT1 K+ channel mutations found in inherited cardiac arrhythmias

The inherited long QT syndrome (LQTS), characterized by a prolonged QT interval in the electrocardiogram and cardiac arrhythmia, is caused by mutations in at least four different genes, three of which have been identified and encode cardiac ion channels. The most common form of LQTS is due to mutations in the potassium channel gene KVLQT1, but their effects on associated currents are still unknown. Different mutations in KVLQT1 cause the dominant Romano-Ward (RW) syndrome and the recessive Jervell and Lange-Nielsen (JLN) syndrome, which, in addition to cardiac abnormalities, includes congenital deafness. Co- expression of KvLQT1 with the IsK protein elicits slowly activating potassium currents resembling the cardiac Iks current. We now show that IsK not only changes the kinetics of KvLQT1 currents, but also its ion selectivity. Several mutations found in RW, including a novel mutation (D222N) in the putative channel pore, abolish channel activity and reduce the activity of wild-type KvLQT1 by a dominant-negative mechanism. By contrast, a JLN mutation truncating the carboxyterminus of the KvLQT1 channel protein abolishes channel function without having a dominant-negative effect. This fully explains the different patterns of inheritance. Further, we identified a novel splice variant of the KVLQT1 gene, but could not achieve functional expression of this nor of a previously described heart-specific isoform.      

Lasting synaptic changes underlie attention deficits caused by nicotine exposure during adolescence

Tobacco smoking and nicotine exposure during adolescence interfere with prefrontal cortex (PFC) development and lead to cognitive impairments in later life. The molecular and cellular underpinnings of these consequences remain elusive. We found that adolescent nicotine exposure induced lasting attentional disturbances and reduced mGluR2 protein and function on presynaptic terminals of PFC glutamatergic synapses. Restoring mGluR2 activity in vivo by local infusion of a group II mGluR agonist in adult rats that received nicotine as adolescents rescued attentional disturbances.     

Astrocyte lipid metabolism is critical for synapse development and function in vivo

The brain is considered to be autonomous in lipid synthesis with astrocytes producing lipids far more efficiently than neurons. Accordingly, it is generally assumed that astrocyte‐derived lipids are taken up by neurons to support synapse formation and function. Initial confirmation of this assumption has been obtained in cell cultures, but whether astrocyte‐derived lipids support synapses in vivo is not known. Here, we address this issue and determined the role of astrocyte lipid metabolism in hippocampal synapse formation and function in vivo. Hippocampal protein expression for the sterol regulatory element‐binding protein (SREBP) and its target gene fatty acid synthase (Fasn) was found in astrocytes but not in neurons. Diminishing SREBP activity in astrocytes using mice in which the SREBP cleavage‐activating protein (SCAP) was deleted from GFAP‐expressing cells resulted in decreased cholesterol and phospholipid secretion by astrocytes. Interestingly, SCAP mutant mice showed more immature synapses, lower presynaptic protein SNAP‐25 levels as well as reduced numbers of synaptic vesicles, indicating impaired development of the presynaptic terminal. Accordingly, hippocampal short‐term and long‐term synaptic plasticity were defective in mutant mice. These findings establish a critical role for astrocyte lipid metabolism in presynaptic terminal development and function in vivo. GLIA 2017;65:670–682