γ-Aminobutyric Acid Type A Receptor Potentiation Inhibits Learning in a Computational Network Model.

Background: Propofol produces memory impairment at concentrations well below those abolishing consciousness. Episodic memory, mediated by the hippocampus, is most sensitive. Two potentially overlapping scenarios may explain how γ-aminobutyric acid receptor type A (GABAA) potentiation by propofol disrupts episodic memory-the first mediated by shifting the balance from excitation to inhibition while the second involves disruption of rhythmic oscillations.

γ-Aminobutyric acid receptor type A receptor potentiation reduces firing of neuronal assemblies in a computational cortical model.

Background: The understanding of how general anesthetics act on individual cells and on global brain function has increased significantly during the last decade. What remains poorly understood is how anesthetics act at intermediate scales. Several major theories emphasize the importance of neuronal groups, sets of strongly connected neurons that fire in a time-locked fashion, in all aspects of brain function, particularly as a necessary substrate of consciousness.

Expression of endothelial adhesion molecules after radiosurgery in an animal model of arteriovenous malformation.

Background: Endothelial adhesion molecules may be important in the response of brain arteriovenous malformations (AVMs) to radiosurgery. In addition to a putative role in the occlusive process after radiosurgery, they may serve as potential targets for biological strategies to accelerate intravascular thrombosis.

Objective: To determine the temporal expression of E-selectin and vascular cell adhesion molecule-1 in an animal model of AVMs.

Endothelial molecular changes in a rodent model of arteriovenous malformation.

Object: The cellular and molecular processes underlying arteriovenous malformation (AVM) development and response to radiosurgery are largely unknown. An animal model mimicking the molecular properties of AVMs is required to examine these processses. This study was performed to determine whether the endothelial molecular changes in an animal model of arteriovenous fistula (AVF) are similar to those in human AVMs.

Inflammatory molecule expression in cerebral arteriovenous malformations.

Inflammatory proteins may play a role in the pathophysiology of cerebral arteriovenous malformations and their response to radiosurgery. The aim of this study was to compare the expression of inflammatory molecules in arteriovenous malformations (AVMs) with that in normal cerebral vessels. Fresh-frozen surgical specimens from 15 AVMs and three control specimens were studied.

Thrombotic molecule expression in cerebral vascular malformations.

Thrombosis is an important end-point in the obliteration of vascular malformations after radiosurgery. The aim of this study was to investigate the expression of thrombotic molecules in arteriovenous malformations (AVMs) and cavernous malformations (CMs), and in AVMs after radiosurgery. Fresh-frozen surgical specimens from 18 AVMs (including three that had previously been treated with radiosurgery), seven CMs, and three control specimens were studied.

Ultrastructure of perinidal capillaries in cerebral arteriovenous malformations.

Objective: The ultrastructure of perinidal capillaries in cerebral arteriovenous malformations (AVMs) was examined to clarify their pathomorphological features.

Methods: Fifteen AVM specimens were dissected and divided into perinidal and intranidal groups and processed for ultrastructural study immediately after surgical removal. Eleven of the patients had presented with hemorrhage.

Responses of arteriovenous malformations to radiosurgery: ultrastructural changes.

Objective: To examine the ultrastructural changes in arteriovenous malformations (AVMs) after radiosurgery and to explore the possible mechanisms of posttreatment obliteration and hemorrhage.

Methods: Twenty-two specimens, among them three irradiated AVMs (size, 3-6 cm), 15 nonirradiated AVMs, and four normal controls were processed for ultrastructural study immediately after removal. Transmission electron microscopy was used to compare the vasculature of irradiated AVMs with nonirradiated AVMs and normal controls.

Ultrastructural characteristics of hemorrhagic, nonhemorrhagic, and recurrent cavernous malformations.

Object: Ultrastructural characteristics of hemorrhagic, nonhemorrhagic, primary, and recurrent central nervous system cavernous malformations (CMs) were examined in an attempt to clarify their pathological mechanisms.

Methods: Thirteen specimens (nine from samples of CMs and four from healthy control tissue) were processed for ultrastructural study immediately after surgical or postmortem removal, by fixation in glutaraldehyde/formalin and postfixation in OsO4. Transmission electron microscopy was used to examine the vascular walls, endothelium, subendothelium, and cytoplasmic organelles.