Ultrasonography monitoring with Superb Microvascular Imaging during cerebrovascular surgery.

INTRODUCTION: Ultrasonography (US) is used as a real-time dynamic imaging modality during neurosurgery. A novel Doppler US technique, Superb Microvascular Imaging (SMI), can be used to visualize low-velocity flow of small vessels at high resolution with high frame rates. We visualized vessel flow using this US SMI technique and contrast agent during cerebrovascular surgery. METHODS: Forty-three patients with an unruptured cerebral aneurysm (control), ischemic and hemorrhagic moyamoya disease, carotid artery stenosis, hemangioblastoma, severe stenosis of the middle cerebral artery, venous angioma, and intracerebral hemorrhage (ICH) underwent neurosurgery with US SMI monitoring using a contrast agent. The diameter, length, and number of penetrating vessels were analyzed in patients with an unruptured cerebral aneurysm (control), moyamoya disease, and ICH. RESULTS: Diameter and length of cerebral penetrating vessels were significantly increased in patients with moyamoya disease and ICH compared to control patients. The number of penetrating vessels was increased in moyamoya disease patients compared to control and ICH patients. In hemorrhagic moyamoya disease, flow in the penetrating vessels originated from a deep periventricular point and extended to the cerebral surface. Pulsatile cerebral aneurysms during clipping surgery and carotid artery stenosis during carotid endarterectomy were easily identified by SMI. Drastically increased vessel flow in patients with a hemangioblastoma or a venous angioma was observed. CONCLUSION: Using the US SMI technique and contrast agent, we obtained useful flow information of the vascular disease structure and intracerebral deep small vessels during cerebrovascular surgery. Further quantitative analysis will be informative and helpful for cerebrovascular surgery.

Molecular Dynamics Study of the Changes in Conformation of Calmodulin with Calcium Binding and/or Target Recognition.

Calmodulin is a calcium binding protein with two lobes, N-lobe and C-lobe, which evolved from duplication and fusion of a single precursor lobe of a pair of EF-hand. These two lobes of calmodulin show subtle differences in calcium binding and target recognition; these are important for the functions of calmodulin. Since the structures, especially main chain conformations, of two EF-lobes in holo-form are quite similar; this is a good example to evaluate the effect of side chains for structural dynamics. We analyzed the structure of calmodulin using molecular dynamics and found differences in conformational ensembles between N- and C-lobes. We also showed the mutant structures created by homology modeling could reproduce the difference of dynamic motion between N- and C-lobes.

Implantable patch sensor for L-glutamate in hippocampal slices.

We describe an implantable patch sensor for monitoring L-glutamate in hippocampal slices in submerged and interface preparations. This patch sensor is prepared by excising the cell membrane in the CA3 region of a hippocampal slice in a submerged preparation, and then implanted in the target neuronal region (CA1) of mouse hippocampal slices. The lifetime of the sensor was 3-8 min for the interface slice and 40-50 min for the submerged slice. The calibration of an implanted sensor can be achieved by adding an L-glutamate solution to a bath (ACSF) solution. The monitoring of L-glutamate release in the CA1 region of mouse hippocampal slices under chemical stimulation with γ-aminobutyric acid (GABA) and potassium chloride (KCl) was demonstrated.