Long-term potentiation (LTP) and depression (LTD) in the hippocam

Long-term potentiation (LTP) and depression (LTD) in the hippocampal region of the brain are two forms of synaptic plasticity that increase or decrease, respectively, the strength of synaptic transmission by postsynaptic AMPA-type glutamate receptors. Both LTP and LTD are induced by activation of NMDA-type glutamate receptors but differ in the level and duration of Ca(2+) influx through the

NMDA receptor 5-Fluoracil cost and the subsequent engagement of downstream signaling by protein kinases, including PKA, PKC, and CaMKII, and phosphatases, including PPI and calcineurin-PP2B (CaN). This review addresses the important emerging roles of the A-kinase anchoring protein family of scaffold proteins in regulating

localization of PKA and other kinases and phosphatases to postsynaptic multiprotein complexes that control NMDA and AMPA receptor function during LTP and LTD.”
“Objective: In risk stratification of aortic diseases such as aneurysm and aortic dissection, diameter is one parameter whose influence on the average aortic wall stress is directly described by the Laplace law. More advanced mechanical models can be used and may yield additional information, such as transmural stress distributions. The question then arises of how refined models need to be to provide clinicians with practical help.

Methods: Two sets of finite element models were used. The relative roles of diameter, material stiffness, longitudinal stretch, blood pressure, CA3 chemical structure wall thickness, and vessel curvature were explored using simplified aortic models

for comparison with the Laplace law. The influences of the material properties nonlinearity and residual stress unless on the transmural stress distribution were investigated using an advanced aortic model including recent experimental findings in older humans.

Results: The Laplace law was confirmed as one effective, basic tool to assess the average wall stress in the aortic wall, both in the circumferential and longitudinal directions. However, the simplified models were sufficient to show that, as already reported in the literature, longitudinal stretch and vessel curvature have potentially equally strong or even stronger contributions to wall stress than the parameters included in the Laplace law. When the advanced model was used, and residual stress induced by large opening angles such as found in older subjects was introduced, the transmural stress gradient was found inverted compared with expectations, with the largest stresses now toward the adventitia. The results suggested that the intima may be increasingly shielded from higher stresses as one gets older, which might be protective against the initiation of dissection tears in the thoracic aorta.

Conclusion: Biomechanical analysis of the aorta may be refined by using increasingly detailed computational models.

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