The term 'brain relaxation' is routinely used to describe the size and firmness of the brain tissue during craniotomy. The status of brain relaxation is an important aspect of neuroanaesthesia practice and is relevant to the operating conditions, retraction injury, and likely patient outcomes. Brain relaxation is determined by the relationship between the volume of the intracranial contents and the capacity of the intracranial space (i.e. a content-space relationship). It is a concept related to, but distinct from, intracranial pressure. The evaluation of brain relaxation should be standardized to facilitate clinical communication and research collaboration. Both advantageous and disadvantageous effects of the various interventions for brain relaxation should be taken into account in patient care. The outcomes that matter the most to patients should be emphasized in defining, evaluating, and managing brain relaxation. To date, brain relaxation has not been reviewed specifically, and the aim of this manuscript is to discuss the current approaches to the definition, evaluation, and management of brain relaxation, knowledge gaps, and targets for future research.

Objective The umbilical cord provides nutrition and oxygen to the fetus. The aim of this study was to determine the effects of acetylcholine (ACh) on umbilical cords from humans and other mammals, and the mechanisms of ACh-mediated vasoconstriction in the human umbilical cord.Design Human and animal umbilical cords used in vascular and cellular experiments.Setting Institute for Fetology, First Hospital of Soochow University, Suzhou, China.Population A total of 85 pregnant women, 16 Sprague Dawley rats and seven pregnant sheep.Methods Umbilical cord veins and arteries from humans, rats and sheep, aortas and mesenteric arteries from rats, and mesenteric, carotid and femoral arteries from ovine fetuses were used to compare vascular functions in response to ACh and to determine the mechanisms of ACh-mediated umbilical vasoconstriction. Vascular tension and ion channel currents were measured on isolated vessels and smooth muscle cells from human umbilical cords.Main outcome measures Provision of new evidence to conclude that ACh-stimulated vasoconstriction is common to all umbilical cords, and cellular mechanisms are linked to potassium channels.Results ACh caused reliable vasoconstriction in umbilical veins/ arteries in humans, rats and sheep, but not in any other vessels, including fetal vessels. Atropine inhibited the effects of ACh. The mRNA of ACh-muscarinic receptor subtypes M 1 -M 5 was expressed in human umbilical vessels. The protein kinase C antagonist GF109203X and the calcium inhibitor nifedipine decreased ACh-induced vasoconstriction in human umbilical vessels. ACh also caused a reduction in whole-cell potassium channel currents and the single-channel current of largeconductance calcium-activated potassium (BKca) channels.Conclusion Umbilical vessels are significantly different from other vessels in their response to ACh. BKca channels in smooth muscle cells may play important roles in ACh-mediated vasoconstriction in human umbilical cords. This information may be important for fetal medicine and practice with regard to the effect on fetal development of umbilical vascular functions.Keywords Acetylcholine, BKca current, muscarinic receptor, umbilical cord vessels, vascular constriction.

This study investigated the effects of the ionic dissolution products of NovaBone® on osteoblastic proliferation and cell cycle regulation. MG63 osteoblast-like cells were cultured in NovaBone®-conditioned Dulbecco's Modified Eagle's Medium (DMEM) or control DMEM for 10 days. The concentration of silicon ions was significantly higher in NovaBone®-conditioned DMEM than control DMEM. MG63 cells cultured in NovaBone®-conditioned DMEM exhibited greater proliferation on days 1 and 4 than control cells. There were increased proportions of Novabone®-conditioned DMEM-cultured cells in the S and G2/M phases, and decreased proportions in the G0/G1 phase on days 1 and 4 versus control cells, while no differences were observed on days 7 and 10 between the two groups. Bone morphogenic protein 2 production increased in both groups, but was significantly higher for the NovaBone®-conditioned DMEM-cultured cells on day 10 compared with the controls. In conclusion, the NovaBone® ionic dissolution products, particularly the silicon ions, promoted proliferation of MG63 osteoblast-like cells in vitro via influences on the cell cycle.

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