New insight from using spatiotemporal image correlation in prenatal screening of fetal conotruncal defects.

BACKGROUND: : To establish the reference range of the angle between ascending aorta and main pulmonary artery of fetus in the second and third trimester using spatiotemporal image correlation (STIC), and to investigate the value of this angle in prenatal screening of conotruncal defects (CTDs). MATERIALS AND METHODS: Volume images of 311 normal fetuses along with 20 fetuses with congenital heart diseases were recruited in this cross-sectional study. An offline analysis of acquired volume datasets was carried out with multiplanar mode. The angle between aorta and pulmonary artery was measured by navigating the pivot point and rotating axes and the reference range was established. The images of ascending aorta and main pulmonary artery in fetuses with congenital heart diseases were observed by rotating the axes within the normal angle reference range. RESULTS: THE ANGLE BETWEEN ASCENDING AORTA AND MAIN PULMONARY ARTERY OF THE NORMAL FETUS (RANGE: 59.1˚~97.0˚, mean ± SD: 78.0˚ ± 9.7˚) was negatively correlated with gestational age (r = -0.52; p<0.01). By rotating the normal angle range corresponding to gestational age, the fetuses with CTD could not display views of their left ventricular long axis and main pulmonary trunk correctly. CONCLUSION: The left ventricular long axis and main pulmonary trunk views can be displayed using STIC so that the echocardiographic protocol of the cardiovascular joint could be standardized. The reference range of the angle between ascending aorta and main pulmonary artery is clinically useful in prenatal screening of CTD and provides a reliable quantitative standard to estimate the spatial relationship of the large arteries of fetus.

Sequestration of copper from beta-amyloid promotes selective lysis by cyclen-hybrid cleavage agents.

Decelerated degradation of beta-amyloid (Abeta) and its interaction with synaptic copper may be pathogenic in Alzheimer disease. Recently, Co(III)-cyclen tagged to an aromatic recognition motif was shown to degrade Abeta in vitro. Here, we report that apocyclen attached to selective Abeta recognition motifs (KLVFF or curcumin) can capture copper bound to Abeta and use the Cu(II) in place of Co(III) to become proteolytically active. The resultant complexes interfere with Abeta aggregation, degrade Abeta into fragments, preventing H2O2 formation and toxicity in neuronal cell culture. Because Abeta binds Cu in amyloid plaques, apocyclen-tagged targeting molecules may be a promising approach to the selective degradation of Abeta in Alzheimer disease. The principle of copper capture could generalize to other amyloidoses where copper is implicated.

Frequency modulation of synchronized Ca(2+) spikes in cultured hippocampal networks through mTOR.

The atypical serine/threonine protein kinase, a mammalian target of rapamycin (mTOR), is believed to be essential to the regulation of cell growth and the functions of the central nervous system. By using calcium imaging and patch-clamping techniques to study the role of this signaling pathway in the activity of cultured hippocampal neurons, we found that rapamycin significantly reduces the spontaneous activities of network neurons as well as the efficacy of synaptic transmission through insulin-mTOR signaling pathway. Our study sheds light on understanding the role of mTOR signaling pathway in controlling the information processing of network neurons.

Deoxyschisandrin modulates synchronized Ca2+ oscillations and spontaneous synaptic transmission of cultured hippocampal neurons.

AIM: Deoxyschisandrin is one of the most effective composites of Schisandra chinensis, a famous Chinese medicine widely used as an antistress, anti-aging, and neurological performance-improving herb. In this study, we examined its specific mechanisms of action on cultured hippocampal neurons. METHODS: Hippocampal neurons, primarily cultured for 9-11 d in vitro, were used for this study. DS were dissolved in DMSO and applied to calcium imaging and whole-cell patch clamp. RESULTS: The application of 3 mg/L DS decreased the frequency of spontaneous and synchronous oscillations of intracellular Ca2+ to 72%+/-2% (mean+/-SEM), and the spontaneous inhibitory postsynaptic currents to 60%+/-3% (mean+/-SEM). The inhibitory concentration 50% (IC50) for the effect of DS on calcium oscillations was 3.8 mg/L. DS also depressed the high voltage-gated Ca2+ channel and the voltage-gated Na+ channel currents at the same time point. It had no effect, however, on voltage-gated K+ and spontaneous excitatory postsynaptic currents. CONCLUSION: DS inhibited the spontaneous and synchronous oscillations of intracellular Ca2+ through the depression of influx of extracellular calcium and the initiation of action potential. By repressing the spontaneous neurotransmitter release, DS modulated the neuronal network activities.

Astragaloside IV inhibits spontaneous synaptic transmission and synchronized Ca2+ oscillations on hippocampal neurons.

AIM: To investigate the changes in the spontaneous neuronal excitability induced by astragaloside IV (AGS-IV) in the cultured hippocampal network. METHODS: Hippocampal neurons in culture for 9-11 d were used for this study. The spontaneous synaptic activities of these hippocampal neurons were examined by Ca2+ imaging and whole-cell patch-clamp techniques. In total, 40 mg/L AGS-IV dissolved in DMSO and 2 mL/L DMSO were applied to the neurons under a microscope while the experiments were taking place. RESULTS: AGS-IV inhibited the frequencies of synchronized spontaneous Ca2+ oscillations to 59.39%+/- 3.25%(mean+/-SEM), the spontaneous postsynaptic currents to 43.78%+/- 7.72%(mean+/-SEM), and the spontaneous excitatory postsynaptic currents to 49.25%+/- 7.06%(mean+/-SEM) of those of the control periods, respectively, at 16 min after the AGSIV applications. AGS-IV also decreased the peak values of the voltage-gated K+ and Na+ channel currents at that time point. CONCLUSION: These results indicate that AGS-IV suppresses the spontaneous neuronal excitabilities effectively. Such a modulation of neuronal activity could represent new evidence for AGS-IV as a neuroprotector.

MEK inhibitor PD98059 acutely inhibits synchronized spontaneous Ca2+ oscillations in cultured hippocampal networks.

AIM: To investigate the changes in synchronized spontaneous Ca2+ oscillations induced by mitogen-activated protein kinase kinase (MEK) inhibitor PD98059 at different concentrations in cultured hippocampal network. METHODS: Hippocampal neurons in culture for 1-2 weeks were used for this study. Spontaneous synaptic activities of these hippocampal neurons were examined by Ca2+ imaging using calcium-sensitive dye. MEK inhibitor PD98059 (10, 30, and 60 micromol/L) and SB202474 (10 and 60 micromol/L), a negative control for mitogen-activated protein kinase (MAPK) cascade study, were applied to the cells under the microscope while imaging was taking place. RESULTS: PD98059 at a lower concentration of 10 micromol/L had little effect on the Ca2+ oscillation. At the higher concentration of 30 micromol/L, 5 min after application of PD98059, the spike frequency was decreased to 25.38% +/-7.40% (mean+/-SEM, n=16, P<0.01 vs medium control) of that of the control period. At an even higher concentration of 60 micromol/L, 5 min after application of PD98059, the spike frequency was decreased to 14.53%+/-5.34% (mean+/-SEM, n=16, P< 0.01 vs medium control) of that of the control period. The spike amplitude underwent a corresponding decrease. However, the negative control SB202474 at concentrations of 10 and 60 micromol/L had little inhibition effect on the Ca2+ oscillation. CONCLUSION: These results indicate that PD98059 inhibits synchronized spontaneous Ca2+ oscillation through inhibition of MEK, which hints that the MAPK cascade is required to maintain synchronized spontaneous Ca2+ oscillation.

GDNF augments survival and differentiation of TH-positive neurons in neural progenitor cells.

GDNF plays an important role in the survival and differentiation of primary dopaminergic neurons, but it requires multiple factors for its entire range of activities. This study investigated the effects of GDNF and its cofactors on the development of bFGF-responsive neural progenitor cells (NPCs), mesencephalic and cortical progenitor cells (MP and CP). Various factors were found to have significant inductive effects on the survival and maintenance of these cells in late developmental stages. MP had greater potential than CP to differentiate into dopaminergic neurons. Treatment of NPCs with GDNF and its cofactors enhanced MAP-2 and TH expression, particularly the latter. These findings suggest that NPCs, particularly MP, could develop into more specific neurons if the appropriate factors were applied during the final cell fate specification. They might thus become beneficial sources of donor cells in the treatment of neurological disorders.

Muscarinic acetylcholine receptors involved in the regulation of neural stem cell proliferation and differentiation in vitro.

Neural stem cells (NSCs) are currently considered powerful candidates for cell therapy in neurodegenerative disorders such as Parkinson's disease. However, it is not known when and how NSCs begin to differentiate functionally. Recent reports suggest that classical neurotransmitters such as acetylcholine (Ach) are involved in the proliferation and differentiation of neural progenitor cells, suggesting that neurotransmitters play an important regulatory role in development of the central nervous system (CNS). We have shown by calcium imaging and immunochemistry that proliferation and differentiation are enhanced by M2 muscarinic Ach receptors (mAchR) expressed on the NSC surface and on their neural progeny. Moreover, atropine, an mAchR antagonist, blocks the enhancement and inhibits the subsequent differentiation of NSCs. Further understanding of this neural-nutrition role of Ach might elucidate fetal brain development, the brain's response to injury, and learning and memory.

Green fluorescent protein-labeled mapping of neural stem cells migrating towards damaged areas in the adult central nervous system.

Neural stem cells, which are clonogenic cells with multilineage differentiation properties from regions of the fetal brain, cortex and hippocampus, are currently considered as powerful candidates for cell replacement therapy in neurodegenerative disorders, such as Parkinson's disease. A key issue is whether stem cells can survive, migrate and differentiate following transplantation into the adult CNS. Here, enhanced green fluorescent protein plasmid electroporation-transfected neural stem cells from the fetal cortex were grafted into the striatum of a rat model of Parkinson's disease. We found most of the grafted cells could survive in the adult parkinsonian rat brain and migrated towards damaged areas, while they moved randomly in the normal brain. Several grafted cells differentiated into neurons.

Effect of new O-superfamily conotoxin SO3 on sodium and potassium currents of cultured hippocampal neurons.

The effects of a new O-superfamily conotoxin SO3 on sodium and potassium currents were examined in cultured rat hippocampal neurons using the whole-cell patch clamp technique. SO3 caused a concentration-dependent, rapidly developing and reversible inhibition of sodium currents (I(Na)). The IC(50) value for the blockage of I(Na) was calculated to be 0.49 and the Hill coefficient was 1.7. Using electrophysiological and pharmacological protocols, transient A-type potassium currents (I(A)) and delayed rectifiers potassium currents (I(K)) were isolated. SO3 caused a concentration-dependent, and reversible inhibition of I(K). The IC(50) value for the blockage of I(K) was calculated to be 1.6 and the Hill coefficient was 0.6, with no significant effect on I(A). These results indicate that SO3 can selectively inhibit neuronal sodium and potassium currents.