1. Cell-type-specific imaging of neurotransmission reveals a disrupted excitatory-inhibitory cortical network in isoflurane anaesthesia
Wenzhi Sun, Hailong Dong, Xinxin Zhang, Huiming Li, Dan Wang, Mingzi Ran, Juan Guo, Zilong Gao, Shiyi Zhao, Ji Hu EBioMedicine . 2021 Mar;65:103272. doi: 10.1016/j.ebiom.2021.103272.
Background:Despite the fundamental clinical significance of general anaesthesia, the cortical mechanism underlying anaesthetic-induced loss of consciousness (aLOC) remains elusive.Methods:Here, we measured the dynamics of two major cortical neurotransmitters, gamma-aminobutyric acid (GABA) and glutamate, through in vivo two-photon imaging and genetically encoded neurotransmitter sensors in a cell type-specific manner in the primary visual (V1) cortex.Findings:We found a general decrease in cortical GABA transmission during aLOC. However, the glutamate transmission varies among different cortical cell types, where in it is almost preserved on pyramidal cells and is significantly reduced on inhibitory interneurons. Cortical interneurons expressing vasoactive intestinal peptide (VIP) and parvalbumin (PV) specialize in disinhibitory and inhibitory effects, respectively. During aLOC, VIP neuronal activity was delayed, and PV neuronal activity was dramatically inhibited and highly synchronized.Interpretation:These data reveal that aLOC resembles a cortical state with a disrupted excitatory-inhibitory network and suggest that a functional inhibitory network is indispensable in the maintenance of consciousness.Funding:This work was supported by the grants of the National Natural Science Foundation of China (grant nos. 81620108012 and 82030038 to H.D. and grant nos. 31922029, 61890951, and 61890950 to J.H.).
2. Aerospace Gravitational Effects
Eric Chumbley, Issaka Y. Akparibo, Jackie Anderson
When pilots fly high-performance aircraft, they conduct maneuvers in the air that expose them to high acceleration in the +GZ axis. These +GZ forces acting cephalad-to-foot direction induces cerebral hypotension that may impair cerebral blood flow. G-induced loss of consciousness (G-LOC ) occurs when acceleration forces produce a situation in which the cardiovascular system is unable to supply oxygenated blood to the regions of the nervous system that support consciousness. When aircrew of high-performance aircraft are exposed to +Gz acceleration, symptoms ranging from peripheral visual loss, blackout, and loss of consciousness may occur. A condition known as almost loss of consciousness (A-LOC) first described by the US Navy in the 1980s may occur when a pilot is exposed to +Gz stress at levels that are insufficient to cause G-LOC. It is a syndrome that encompasses a wide variety of cognitive, physical, emotional, and physiological symptoms. The most prevalent symptom is reported to be a disconnection between cognition and ability to act. In centrifuge studies of 500 healthy individuals, individuals who experience G-LOC were observed to have a blank stare and show signs of unconsciousness. The majority of persons who experience G-LOC have myoclonic jerks and which they do not remember after recovery from the episode. The convulsions last for about 4 seconds and occur after the return of cerebral blood flow. Memorable dreams follow the myoclonic jerks.A study conducted by Green and Steven showed that 20.1% of United Kingdom Royal Air Force (RAF) aircrew had suffered one episode of G-LOC and 82% had suffered two episodes. G-LOC is reported to occur most commonly in training aircrew. Prevalence of G-LOC in front-line aircraft is low at 11.3%, and 6% in fast jet aircraft. It is difficult to predict pilot characteristics that may predispose to G-LOC. The most recent survey done in United Kingdom RAF showed a decrease in the incidence of G-LOC from 20% IN 2005 to about 15% in 2012. Sevilla and Gardner found that time on aircraft type less than 600 hours, pilotage younger than 30 years, and poor anti-G straining maneuver is associated with 72% of G-LOC accidents.
3. Synthesis, Structures, and Fluorescence Properties of Dimeric Aluminum Oxo Clusters
Xue-Zhen Zhang, Jian Zhang, Xiao-Feng Wang, Wei-Hui Fang Inorg Chem . 2021 May 17;60(10):7089-7093. doi: 10.1021/acs.inorgchem.0c03816.
Aluminum is an important component for luminescence. However, the fluorescent aluminum complex with unambiguous structural information is still limited. Herein, we report a series of fluorescence aluminum oxo clusters (AlOCs). By introducing an additional coordination site to the aromatic conjugation ligand, cluster nuclearity increment and fluorescence variation are observed. Al8(OH)2(μ4-O)2(1-NA)2(OEt)16(AlOC-41, 1-NA = 1-naphthoic acid, OEt = ethanol) is made up of two tetrahedral subunits. By introducing an additional coordination site to the aromatic conjugation ligand, we isolate a high nuclearity compound Al10(μ3-O)2(3-HNA)2(OEt)22(AlOC-47, 3-HNA = 3-hydroxy-2-naphthoic acid). Correspondingly, their luminescence performance is different (blue fluorescence inAlOC-41and green inAlOC-47). Present herein is a platform to illustrate the relationship between synthesis, structure, and fluorescence properties.
