异氟醚下调MYC表达抑制高级别脑胶质瘤细胞增殖转移

目的 探究异氟醚对高级别脑胶质瘤细胞MYC基因表达及细胞增殖转移能力的影响。方法 分别采用含2%异氟醚的气体环境及常规气体环境（5% CO₂）培养对数生长期的人脑胶质瘤细胞系SHG-44 6 h,作为异氟醚组及对照组;CCK-8实验检测两组细胞气体暴露完成后0、24、48、72 h相对增殖能力;Transwell侵袭及迁移实验检测两组细胞侵袭及迁移能力;Western Blotting检测两组细胞C-Myc及N-Myc的蛋白表达。结果 异氟醚组细胞于暴露完成后48、72 h时增殖能力较对照组细胞显著下调,差异具有统计学意义（P<0.01）;异氟醚组穿透基质胶的侵袭细胞数、穿过微孔的迁移细胞数均较对照组显著减少,差异均具有统计学意义（P<0.01、0.001）;异氟醚组C-Myc及N-Myc的表达较对照组均显著下调,差异具有统计学意义（P<0.01）。结论 异氟醚可通过下调C-Myc及N-Myc基因的表达,抑制人高级别脑胶质瘤细胞的增殖转移。     

Observations on use of wrong agent in an anesthesia agent vaporizer

The creation of agent mixtures from the addition of the wrong agent to a vaporizer might pose a risk to the patient. Patient injury would be more likely if the anesthesia gas monitor displayed erroneous concentration values. Conventional inhalation agent monitors do not necessarily distinguish anesthetic agents. Some modern monitors have that ability but its clinical significance has not been determined. We wanted to simulate such an erroneous mixture in a laboratory setup. Six comparisons were made. Isoflurane, Enflurane, and Halothane vaporizers were first filled with the correct agent. They were run at 5 liters/minute fresh oxygen flow at a vaporizer dial setting of 5% until it reached the refill line. Then, one of two incorrect agents was added to the full line. Thereafter, the vaporizer continued at the same flow and the same dial setting until it was exhausted. Vaporizer output was recorded or calculated by using three methods of measurement: mass spectrometry, conventional infrared analysis (at 3.3 micrometer wave length), and piezoelectric crystal analysis. Additional calculations were used to estimate measurements that could not be made because of lack of available equipment. In a Halothane vaporizer: Enflurane added – not a significant problem; Isoflurane added – not a significant problem. In an Isoflurane vaporizer: Halothane added – not a significant problem; Enflurane added – not a significant problem. In an Enflurane vaporizer: Isoflurane added – not a significant problem; Halothane added – The sum of the delivered Halothane MAC and the delivered Enflurane MAC was twice the expected Enflurane MAC output from vaporizer, with conventional agent monitor reading which showed decreasing agent concentration. Patient injury could be more likely in this last case. In this last case and in all cases, piezoelectric crystal monitoring correctly displayed the sum of the two agent concentrations in volumes percent. Automatic agent identification can identify erroneous agents.     

Technical Performance and Reflection Capacity of the Anaesthetic Conserving Device—A Bench Study with Isoflurane and Sevoflurane

Objective

The anaesthetic conserving device (AnaConDa^®, Sedana Medical, Sundbyberg, Sweden) facilitates administration of isoflurane or sevoflurane by liquid infusion. An anaesthetic reflector inside the device conserves exhaled anaesthetic and re-supplies it during inspiration. In this bench study, we examined the influence of infusion rates and ventilatory settings on the resulting anaesthetic concentrations on patient (C_pat) and ventilator side of the reflector (C_loss) to describe its technical performance.

Methods

A Puritan Bennett 840 ICU ventilator (Pleasanton, US), AnaConDa^®, and a test lung (3 l-chloroprene-bag) were assembled. Infusion rates (IR, 0.2-50 ml h^-), respiratory rates (RR, 5-40 breaths min^-1), and tidal volumes (V_T, 0.3, 0.5, and 1.0 l) were varied. C_pat was measured via a thin catheter in the middle of the 3 l-bag in steady state (online data storage and averaging over >10 min). C_loss was calculated from IR (to yield the volume of vapour per unit of time), and expired minute volume (in which the vapour is diluted) on the assumption that, in the steady state, input by liquid infusion equals output through the reflector.

Results

At lower concentrations (C _pat< 1 vol%) the ratio C_loss/C_pat was constant (R _C = 0.096?±±0.012) for all combinations of IR, RR and V_T, both for isoflurane and sevoflurane. The device could efficiently reflect up to 10 ml vapour per breath (e.g. 2 vol% in 0.5 l). When exceeding this capacity, surplus vapour “spilled over” and R_C markedly increased indicating decreased performance.

Conclusions

The triple product minute volume times R_C times C_pat describes anaesthetic losses through the reflector. It can easily be calculated as long as the 10 ml reflection capacity is not exceeded and thus R_C is constant. Increased minute ventilation necessitates increasing the IR to keep C_pat constant. When using large V_T and high C_pat “spill over” occurs. This effect offers some protection against an inadvertent overdose.     

Early stimulation treatment provides complete sensory‐induced protection from ischemic stroke under isoflurane anesthesia

Using a rodent model of ischemia [permanent middle cerebral artery occlusion (pMCAO)], previous studies demonstrated that whisker stimulation treatment completely protects the cortex from impending stroke when initiated within 2 h following pMCAO. When initiated 3 h post‐pMCAO, the identical treatment exacerbates stroke damage. Rats in these studies, however, were anesthetised with sodium pentobarbital, whereas human stroke patients are typically awake. To overcome this drawback, our laboratory has begun to use the anesthetic isoflurane, which allows rats to rapidly recover from pMCAO within minutes, to test stimulation treatment in awake rats and to determine whether isoflurane has an effect upon the pMCAO stroke model. We found no difference in infarct volume between pMCAO in untreated controls under either sodium pentobarbital or isoflurane, and the primary finding was that rats that received treatment immediately post‐pMCAO maintain cortical function and no stroke damage, whereas rats that received treatment 3 h post‐pMCAO exhibited eliminated cortical activity and extensive stroke damage. The only difference between anesthetics was the broad extent of evoked cortical activity observed during both functional imaging and electrophysiological recording, suggesting that the extent of evoked activity evident under isoflurane anesthesia is supported by underlying neuronal activity. Given the high degree of similarity with previous data, we conclude that the pMCAO stroke model is upheld with the use of isoflurane. This study demonstrated that the isoflurane‐anesthetised rat pMCAO model can be used for cerebrovascular studies, and allows for highly detailed investigation of potential novel treatments for ischemic stroke using awake, behaving animals.     

Influence of different isoflurane anesthesia protocols on murine cerebral hemodynamics measured with pseudo‐continuous arterial spin labeling

Arterial spin labeling (ASL)‐MRI can noninvasively map cerebral blood flow (CBF) and cerebrovascular reactivity (CVR), potential biomarkers of cognitive impairment and dementia. Mouse models of disease are frequently used in translational MRI studies, which are commonly performed under anesthesia. Understanding the influence of the specific anesthesia protocol used on the measured parameters is important for accurate interpretation of hemodynamic studies with mice. Isoflurane is a frequently used anesthetic with vasodilative properties. Here, the influence of three distinct isoflurane protocols was studied with pseudo‐continuous ASL in two different mouse strains. The first protocol was a free‐breathing set‐up with medium concentrations, the second a free‐breathing set‐up with low induction and maintenance concentrations, and the third a set‐up with medium concentrations and mechanical ventilation. A protocol with the vasoconstrictive anesthetic medetomidine was used as a comparison. As expected, medium isoflurane anesthesia resulted in significantly higher CBF and lower CVR values than medetomidine (median whole‐brain CBF of 157.7 vs 84.4 mL/100 g/min and CVR of 0.54 vs 51.7% in C57BL/6 J mice). The other two isoflurane protocols lowered the CBF and increased the CVR values compared with medium isoflurane anesthesia, without obvious differences between them (median whole‐brain CBF of 138.9 vs 131.7 mL/100 g/min and CVR of 10.0 vs 9.6%, in C57BL/6 J mice). Furthermore, CVR was shown to be dependent on baseline CBF, regardless of the anesthesia protocol used.     

Occupational exposure to anaesthetic gases: a role for TIVA

Modern anaesthesia is still mostly administered by the inhalational route and there is increasing concern over its potential for pollution. One of the first gaseous anaesthetic agents was nitrous oxide and this is still widely used today despite being associated with adverse effects caused by depression of vitamin B₁₂ function and diminished reproductive health. The use of halothane is associated with hepatitis but the adverse effects of newer halogenated hydrocarbons are less well recognised. Chronic exposure may cause reduction in antioxidant activity in plasma and erythrocytes, inhibition of neutrophil apoptosis, depression of central neuro-respiratory activity, increased DNA breaks, effects on cerebral blood circulation and altered renal function. Inhalational anaesthetics also have adverse environmental effects, including ozone damage and greenhouse gas effects. Levels of inhalational anaesthetics in the ambient air of operating theatres and recovery rooms often exceed those stated in national guidelines. Anaesthetic procedures can be modified and air-conditioning and air scavenging systems should be used to minimise the risks from occupational exposure and threats to the environment. Such contamination could be avoided with the use of total intravenous anaesthesia.     

Reliability and spatial specificity of rat brain sensorimotor functional connectivity networks are superior under sedation compared with general anesthesia

Functional connectivity networks derived from resting‐state functional MRI (rsfMRI) have received increasing interest to further our understanding of brain function. The anesthesia in rodent models may influence the interpretation and comparison of results from functional connectivity MRI (fcMRI). More research is required on this aspect. In this study, we investigated rat brain connectivity networks under 1.5% isoflurane anesthesia in comparison with medetomidine sedation. rsfMRI data were acquired under both anesthesia conditions within one imaging session. Male Wistar rats (n = 17) were scanned at 11.7 T with focus on the sensorimotor system. The data underwent a per‐subject independent component analysis (ICA), after which individual components were grouped using hierarchical clustering. Consistent and reliable networks were identified under medetomidine in sensorimotor cortex (three networks) and striatum (two networks). The incidence of these networks was drastically reduced under isoflurane. Seed correlation analysis confirmed these results and revealed globally elevated correlations with low topical specificity under isoflurane, stemming from low‐frequency global signal fluctuations. Global signal removal thus enhanced slightly regional specificity under isoflurane and showed anti‐correlations of cortico‐striatal connections in both anesthesia regimes. Functional connectivity networks are thus reliably detected in medetomidine‐sedated animals on an individual basis using ICA. Their occurrence, however, is heavily compromised under isoflurane as a result of global signal fluctuations potentially stemming from burst‐suppression‐like neural activity. Anesthesia and pharmacologically induced modulations may provide insight into network mechanisms in the future. As an agent for fcMRI in brain disease studies, light sedation using medetomidine preserves connectivity networks in a greater level of detail, and may therefore be considered superior to standard isoflurane anesthesia. Copyright © 2013 John Wiley & Sons, Ltd.     

Time‐dependent effects of isoflurane and dexmedetomidine on functional connectivity,spectral characteristics,and spatial distribution of spontaneous BOLD fluctuations

Anesthesia is often necessary to perform fMRI experiments in the rodent model; however, commonly used anesthetic protocols may manifest changing brain conditions over the duration of the study. This possibility was explored in the current work. Eleven rats were anesthetized with 2% isoflurane anesthesia; four rats were anesthetized for a short period (30 min, simulating induction and fMRI setup) and seven rats were anesthetized for a long period (3 h, simulating surgical preparation). Following the initial anesthetic period, isoflurane was discontinued, and a dexmedetomidine bolus (0.025 mg/kg) and continuous subcutaneous infusion (0.05 mg/kg/h) were administered. Blood‐oxygen‐level dependent resting state imaging was performed every 30 min from 0.75 h post dexmedetomidine bolus until 5.75 h post‐bolus. Evaluation of power spectra obtained from time courses in the primary somatosensory cortex revealed, in general, a monotonic increase in low‐frequency power (0.05–0.3 Hz) in both groups over the duration of resting state imaging. Greater low‐band spectral power (0.05–0.15 Hz) is present in the short isoflurane group for the first 2.75 h, but the spectra become highly uniform at 3.25 h. The emergence of a ~0.18 Hz peak, beginning at the 3.75 h time point, exists in both groups and evolves similarly, increasing in strength as the duration of dexmedetomidine sedation (and time since isoflurane cessation) extends. In the long isoflurane group only, bilateral functional connectivity strengthens with anesthetic duration, and correlation is linearly linked to low‐band spectral power. Convergence of connectivity and spectral metrics between the short and long isoflurane groups occurs at ~3.25 h, suggesting the effects of isoflurane have subsided. Researchers using dexmedetomidine following isoflurane for functional studies should be aware of the duration specific effects of the pre‐scan isoflurane durations as well as the continuing influences of long‐term imaging under dexmedetomidine. Copyright © 2014 John Wiley & Sons, Ltd.     

Effects of isoflurane, sevoflurane, and desflurane on platelet function: A prospective, randomized, single-blind, in vivo study

Background:

The primary physiologic function of platelets is to facilitate hemostasisby aggregation. Volatile anesthetics have been reported to decrease platelet aggregation in vivo and in vitro.

Objective:

The aim of this study was to investigate the hematologic effectsof the anesthetics isoflurane, sevoflurane, and desflurane on hemoglobin (Hb), hematocrit (Hct), platelet count, activated partial thromboplastin time (aPTT), prothrombin time (PT), international normalized ratio (INR), and platelet aggregation after minor surgery.

Methods:

Patients aged 20 to 60 years who were scheduled to undergominor surgery and American Society of Anesthesiologists physical status P1 or P2 (healthy or mild systemic disease) were randomized to 1 of 3 groups: 1 minimum alveolar concentration (MAC) of isoflurane, sevoflurane, or desflurane. None of the patients received premedication. Anesthesia was induced using IV thiopental 5 to 6 mg/kg, fentanyl 1 to 2 μg/kg, and vecuronium 0.1 mg/kg, and maintained with 1 MAC of isoflurane, sevoflurane, or desflurane in 66% nitrous oxide and 33% oxygen. Vecuronium 0.03 mg/kg was given when necessary for muscle relaxation. All patients were monitored throughout surgery; isotonic saline was given at a rate of 5 mL/kg · h. Hematologic studies were performed preoperatively, 15 minutes after intubation, and 1 hour after the end of surgery. Platelet aggregation tests were performed in a laboratory using a platelet function analyzer (PFA), collagen/epinephrine PFA test cartridges, collagen/adenosine diphosphate PFA test cartridges, and PFA trigger solution.

Results:

This prospective, randomized, single-blind, in vivo study was conducted at Gevher Nesibe Teaching Hospital, Erciyes University, Kayseri, Turkey. Thirty patients (15 men, 15 women) were randomized to the 3 treatment groups (each, n = 10). Hb, Hct, platelet count, aPTT, PT, and INR were statistically similar between all 3 groups. The measured parameters were not significantly different between the isoflurane and desflurane groups at any time point. However, in the sevoflurane group, mean (5D) platelet aggregation was significantly delayed 15 minutes after intubation and 1 hour after surgery compared with the preoperative values (collagen/epinephrine, 81.70 [9.85] seconds vs 196.20 [27.84] seconds and 115.40 [25.80] seconds; both, P < 0.05).

Conclusions:

In this study of the effects of isoflurane, sevoflurane, and desflurane in patients undergoing minor surgery, clinically relevant antithrombotic effects were observed 15 minutes after intubation with all 3 drugs, although the effects in patients receiving sevoflurane were significantly greater compared with those in patients receiving isoflurane and desflurane. The antithrombotic effects of isoflurane and desflurane were not continued at 1 hour after surgery; however, the inhibitory effects of sevoflurane on platelet function were continued at 1 hour after surgery but were significantly decreased from levels found at 15 minutes after intubation.