The role of astrocytic γ-aminobutyric acid in the action of inhalational anesthetics

BACKGROUND

Inhalational anesthetics target the inhibitory extrasynaptic γ-aminobutyric acid type A (GABAA) receptors. Both neuronal and glial GABA mediate tonic inhibition of the extrasynaptic GABAA receptors. However, the role of glial GABA during inhalational anesthesia remains unclear. This study aimed to evaluate whether astrocytic GABA contributes to the action of different inhalational anesthetics.

METHODS

Gene knockout of monoamine oxidase B (MAOB) was used to reduce astrocytic GABA levels in mice. The hypnotic and immobilizing effects of isoflurane, sevoflurane, and desflurane were assessed by evaluating the loss of righting reflex (LORR) and tail-pinch withdrawal response (LTWR) in MAOB knockout and wild-type mice. Minimum alveolar concentration (MAC) for LORR, time to LORR, MAC for LTWR and time to LTWR of isoflurane, sevoflurane, and desflurane were assessed.

RESULTS

Time to LORR and time to LTWR with isoflurane were significantly longer in MAOB knockout mice than in wild-type mice (P < 0.001 and P = 0.032, respectively). Time to LORR with 0.8 MAC of sevoflurane was significantly longer in MAOB knockout mice than in wild-type mice (P < 0.001), but not with 1.0 MAC of sevoflurane (P=0.217). MAC for LTWR was significantly higher in MAOB knockout mice exposed to sevoflurane (P < 0.001). With desflurane, MAOB knockout mice had a significantly higher MAC for LORR (P = 0.003) and higher MAC for LTWR (P < 0.001) than wild-type mice.

CONCLUSIONS

MAOB knockout mice showed reduced sensitivity to the hypnotic and immobilizing effects of isoflurane, sevoflurane, and desflurane. Behavioral tests revealed that the hypnotic and immobilizing effects of inhalational anesthetics would be mediated by astrocytic GABA.

Electroencephalographic density spectral array monitoring during propofol/sevoflurane coadministration in children, an exploratory observational study

INTRODUCTION

Propofol and sevoflurane have a long history in pediatric anesthesia. Combining both drugs at low dose levels offers new opportunities. However, monitoring the hypnotic effects of this drug combination in children is challenging, because the currently available processed EEG-based systems are insufficiently validated in young children and the co-administration of anesthetics. This study investigated electroencephalographic density spectral array monitoring during propofol/sevoflurane coadministration with fixed sevoflurane- and variable propofol dosages.

PATIENTS AND METHODS

We analyzed the density spectral array pattern recorded during propofol/sevoflurane anesthesia in pediatric patients from birth to 11 years of age. Data from 78 patients were suitable for analysis. The primary outcome parameter of this study was the correlation between variable propofol dosages and the expression of the four electroencephalogram frequency bands β, α, θ, and δ. The main secondary outcome parameters were the intra-operative total EEG power and the prevalence of burst suppression.

RESULTS

In patients above the age of 1 year, a dose-dependent correlation between the propofol dosage and the relative percentage of β (-12.2%, p < 0.001) and δ (5.1%, p < 0.001) was found. There was an age-dependent trend toward increasing mean EEG power, with the most significant increase in the first year of life. In 14.1% of our patients, at least one episode of burst suppression occurred.

CONCLUSION

DSA-guided augmentation of propofol anesthesia with sevoflurane provides sufficient depth of anesthesia at doses usually considered sub-anesthetic in children, leading to less anesthetic drug exposure for the individual child.

Similarity and dissimilarity in alterations of the gene expression profile associated with inhalational anesthesia between sevoflurane and desflurane

Although sevoflurane is one of the most commonly used inhalational anesthetic agents, the popularity of desflurane is increasing to a level similar to that of sevoflurane. Inhalational anesthesia generally activates and represses the expression of genes related to xenobiotic metabolism and immune response, respectively. However, there has been no comprehensive comparison of the effects of sevoflurane and desflurane on the expression of these genes. Thus, we used a next-generation sequencing method to compare alterations in the global gene expression profiles in the livers of rats subjected to inhalational anesthesia by sevoflurane or desflurane. Our bioinformatics analyses revealed that sevoflurane and, to a greater extent, desflurane significantly activated genes related to xenobiotic metabolism. Our analyses also revealed that both anesthetic agents, especially sevoflurane, downregulated many genes related to immune response.

Involvement of Fgf2-mediated tau protein phosphorylation in cognitive deficits induced by sevoflurane in aged rats

OBJECTIVE

Anesthetics have been linked to cognitive alterations, particularly in the elderly. The current research delineates how Fibroblast Growth Factor 2 (Fgf2) modulates tau protein phosphorylation, contributing to cognitive impairments in aged rats upon sevoflurane administration.

METHODS

Rats aged 3, 12, and 18 months were subjected to a 2.5% sevoflurane exposure to form a neurotoxicity model. Cognitive performance was gauged, and the GEO database was employed to identify differentially expressed genes (DEGs) in the 18-month-old cohort post sevoflurane exposure. Bioinformatics tools, inclusive of STRING and GeneCards, facilitated detailed analysis. Experimental validations, both in vivo and in vitro, examined Fgf2's effect on tau phosphorylation.

RESULTS

Sevoflurane notably altered cognitive behavior in older rats. Out of 128 DEGs discerned, Fgf2 stood out as instrumental in regulating tau protein phosphorylation. Sevoflurane exposure spiked Fgf2 expression in cortical neurons, intensifying tau phosphorylation via the PI3K/AKT/Gsk3b trajectory. Diminishing Fgf2 expression correspondingly curtailed tau phosphorylation, neurofibrillary tangles, and enhanced cognitive capacities in aged rats.

CONCLUSION

Sevoflurane elicits a surge in Fgf2 expression in aging rats, directing tau protein phosphorylation through the PI3K/AKT/Gsk3b route, instigating cognitive aberrations.

Echinatin mitigates sevoflurane-induced neurotoxicity through regulation of ferroptosis and iron homeostasis

Surgery and anesthesia are vital medical interventions, but concerns over their potential cognitive side effects, particularly with the use of inhalational anesthetics like sevoflurane, have surfaced. This study delves into the neuroprotective potential of Echinatin against sevoflurane-induced neurotoxicity and the underlying mechanisms. Echinatin, a natural compound, has exhibited anti-inflammatory, antioxidant, and anticancer properties. Sevoflurane, while a popular anesthetic, is associated with perioperative neurocognitive disorders (PND) and neurotoxicity. Our investigation began with cellular models, where Echinatin demonstrated a significant reduction in sevoflurane-induced apoptosis. Mechanistically, we identified ferroptosis, a novel form of programmed cell death characterized by iron accumulation and lipid peroxidation, as a key player in sevoflurane-induced neuronal injury. Echinatin notably suppressed ferroptosis in sevoflurane-exposed cells, suggesting a pivotal role in neuroprotection. Expanding our research to a murine model, we observed perturbations in iron homeostasis, inflammatory cytokines, and antioxidants due to sevoflurane exposure. Echinatin treatment effectively restored iron balance, mitigated inflammation, and preserved antioxidant levels in vivo. Behavioral assessments using the Morris water maze further confirmed Echinatin's neuroprotective potential, as it ameliorated sevoflurane-induced spatial learning and memory impairments. In conclusion, our study unveils Echinatin as a promising candidate for mitigating sevoflurane-induced neurotoxicity. Through the regulation of ferroptosis, iron homeostasis, and inflammation, Echinatin demonstrates significant neuroprotection both in vitro and in vivo. These findings illuminate the potential for Echinatin to enhance the safety of surgical procedures involving sevoflurane anesthesia, minimizing the risk of cognitive deficits and neurotoxicity.

Stress Pathways Induced by Volatile Anesthetics and Failure of Preconditioning in a Mitochondrial Complex I Mutant

BACKGROUND

Carriers of mutations in the mitochondrial electron transport chain are at increased risk of anesthetic-induced neurotoxicity. To investigate the neurotoxicity mechanism and to test preconditioning as a protective strategy, this study used a Drosophila melanogaster model of Leigh syndrome. Model flies carried a mutation in ND23 (ND2360114) that encodes a mitochondrial electron transport chain complex I subunit. This study investigated why ND2360114 mutants become susceptible to lethal, oxygen-modulated neurotoxicity within 24 h of exposure to isoflurane but not sevoflurane.

METHODS

This study used transcriptomics and quantitative real-time reverse transcription polymerase chain reaction to identify genes that are differentially expressed in ND2360114 but not wild-type fly heads at 30 min after exposure to high- versus low-toxicity conditions. This study also subjected ND2360114 flies to diverse stressors before isoflurane exposure to test whether isoflurane toxicity could be diminished by preconditioning.

RESULTS

The ND2360114 mutation had a greater effect on isoflurane- than sevoflurane-mediated changes in gene expression. Isoflurane and sevoflurane did not affect expression of heat shock protein (Hsp) genes (Hsp22, Hsp27, and Hsp68) in wild-type flies, but isoflurane substantially increased expression of these genes in ND2360114 mutant flies. Furthermore, isoflurane and sevoflurane induced expression of oxidative (GstD1 and GstD2) and xenobiotic (Cyp6a8 and Cyp6a14) stress genes to a similar extent in wild-type flies, but the effect of isoflurane was largely reduced in ND2360114 flies. In addition, activating stress response pathways by pre-exposure to anesthetics, heat shock, hyperoxia, hypoxia, or oxidative stress did not suppress isoflurane-induced toxicity in ND2360114 mutant flies.

CONCLUSIONS

Mutation of a mitochondrial electron transport chain complex I subunit generates differential effects of isoflurane and sevoflurane on gene expression that may underlie their differential effects on neurotoxicity. Additionally, the mutation produces resistance to preconditioning by stresses that protect the brain in other contexts. Therefore, complex I activity modifies molecular and physiologic effects of anesthetics in an anesthetic-specific manner.

EDITOR’S PERSPECTIVE

Consistency analysis of consciousness index and bispectral index in monitoring the depth of sevoflurane anesthesia in laparoscopic surgery

Background

The Index of Consciousness (IoC) is a new monitoring index of anesthesia depth reflecting the state of consciousness of the brain independently developed by China. The research on monitoring the depth of anesthesia mainly focuses on propofol, and bispectral index (BIS) is a sensitive and accurate objective index to evaluate the state of consciousness at home and abroad. This study mainly analyzed the effect of IoC on monitoring the depth of sevoflurane anesthesia and the consistency and accuracy with BIS when monitoring sevoflurane maintenance anesthesia.

Objective

To investigate the monitoring value of the Index of Consciousness (IoC) for the depth of sevoflurane anesthesia in laparoscopic surgery.

Methods

The study population consisted of 108 patients who experienced elective whole-body anesthesia procedures within the timeframe of April 2020 to June 2023 at our hospital. Throughout the anesthesia process, which encompassed induction and maintenance using inhaled sevoflurane, all patients were diligently monitored for both the Bispectral Index (BIS) and the Index of Consciousness (IoC). We conducted an analysis to assess the correlation between IoC and BIS throughout the anesthesia induction process and from the maintenance phase to the regaining of consciousness. To evaluate the predictive accuracy of IoC and BIS for the onset of unconsciousness during induction and the return of consciousness during emergence, we employed receiver operating characteristic (ROC) curve analysis.

Results

The mean difference between BIS and IoC, spanning from the pre-anesthesia induction phase to the completion of propofol induction, was 1.3 (95% Limits of Agreement [-53.4 to 56.0]). Similarly, during the interval from the initiation of sevoflurane inhalation to the point of consciousness restoration, the average difference between BIS and IoC was 0.3 (95% LOA [-10.8 to 11.4]). No statistically significant disparities were observed in the data acquired from the two measurement methodologies during both the anesthesia induction process and the journey from maintenance to the regaining of consciousness (P > 0.05). The outcomes of the ROC curve analysis disclosed that the areas under the curve (AUC) for prognosticating the occurrence of loss of consciousness were 0.967 (95% CI [0.935-0.999]) for BIS and 0.959 (95% CI [0.924-0.993]) for IoC, with optimal threshold values set at 81 (sensitivity: 88.10%, specificity: 92.16%) and 77 (sensitivity: 79.55%, specificity: 95.45%) correspondingly. For the prediction of recovery of consciousness, the AUCs were 0.995 (95% CI [0.987-1.000]) for BIS and 0.963 (95% CI [0.916-1.000]) for IoC, each associated with optimal cutoff values of 76 (sensitivity: 92.86%, specificity: 100.00%) and 72 (sensitivity: 86.36%, specificity: 100.00%) respectively.

Conclusion

The monitoring of sevoflurane anesthesia maintenance using IoC demonstrates a level of comparability to BIS, and its alignment with BIS during the maintenance phase of sevoflurane anesthesia is robust. IoC displays promising potential for effectively monitoring the depth of anesthesia.

Effects of propofol versus sevoflurane on surgical field visibility during arthroscopic rotator cuff repair: a randomized trial

BACKGROUND

During arthroscopic rotator cuff repair (ARCR), clear surgical field visibility (SFV) is the basis of successful surgery, but the choice of anesthesia maintenance drugs may have different effects on SFV. In this study, we aimed to compare the effects of propofol- and sevoflurane-based general anesthesia on SFV in patients undergoing ARCR.

METHODS

Patients (n = 130) undergoing elective ARCR in the lateral decubitus position were randomized into either the propofol group or sevoflurane group (65 per group). The duration of surgery and increased pressure irrigation (IPI), Boezaart score, rocuronium consumption and usage of remifentanil were recorded. The time of both spontaneous respiration recovery and extubation and the incidences of postoperative nausea and vomiting and agitation were also recorded.

RESULTS

The Boezaart score, duration of IPI and ratio of the duration of IPI to the duration of surgery (IPI/S ratio) were similar between the groups (P > 0.05). Rocuronium consumption, number of patients requiring remifentanil infusion and total remifentanil consumption were significantly lower in the sevoflurane group (P < 0.05). The spontaneous respiration recovery time was significantly longer in the propofol group (P < 0.05), but there were no differences in the extubation time between the groups(P > 0.05).

CONCLUSIONS

Compared with propofol, sevoflurane provides equally clear SFV while improving the convenience of anesthesia maintenance in ARCR patients with interscalene plexus (ISB) combined with general anesthesia.

TRIAL REGISTRATION

This single-center, prospective, RCT was retrospective registered at Chinese Clinical Trial Registry with the registration number ChiCTR2300072110 (02/06/2023).

Necroptosis involved in sevoflurane-induced cognitive dysfunction in aged mice by activating NMDA receptors increasing intracellular calcium

Perioperative neurocognitive disorders are a common surgical and postanesthesia complication. Necroptosis contributes to the emergence of various neurological disorders. We conjecture that cognitive impairment is associated with necroptosis of hippocampal neurons, which is mediated by NMDA receptors leading to cytoplasmic calcium imbalance. C57BL/6 J male mice ( 18 months) were randomly divided into the C ( control group), S ( sevoflurane group), S+M ( sevoflurane plus the NMDA receptor antagonist memantine group) and S+N ( sevoflurane plus necrostatin-1) group. We exposed the mice to 3% sevoflurane for 2 h a day for three consecutive days in the S, S+M and S+N groups. Memantine ( 20 mg/kg) or Nec-1 ( 10 mg/kg) was injected intraperitoneally 1 h before sevoflurane anesthesia in the S+M or S+N group. We used the animal behavior tests to evaluate the cognitive function. Pathological damage, the rate of necroptosis, [Ca2+]i, and the expression of necroptosis-related proteins were evaluated. The cognitive function tests, pathological damage, the rate of necroptosis, the expression of necroptosis-related proteins, NMDAR2A and NMDAR2B were significantly different in the S group ( P < 0.05). Alleviated pathological damage, decreased the rate of necroptosis and down-regulated the expression of necroptosis-related proteins occurred in the S+M and S+N group ( P < 0.05). The lower elevated [Ca2+]i, expression of NMDAR2A and NMDAR2B were found in the S+M group. Our findings highlighted sevoflurane-induced cognitive dysfunction is associated with an imbalance in cytoplasmic calcium homeostasis by activating NMDA receptors, which causes hippocampus neurons to undergo necroptosis and ultimately affects cognitive performance in aged mice.

Effects of anesthetics on nociceptive sensory evoked potentials by intraepidermal noxious electrical stimulation of A-δ fibers

PURPOSE

Generation of nociceptive sensory evoked potentials (NEPs) by selective stimulation of nociceptive intraepidermal nerve fibers is a simple technique which could be used as intraoperative nociception monitor. We evaluated the effects of remifentanil, propofol and sevoflurane on NEPs by this technique.

METHODS

Patients undergoing general anesthesia were assigned to groups in two studies. A-δ fiber selective NEPs were recorded. Study 1: NEPs were recorded at control, under anesthetics administration: remifentanil at an effect-site concentration (Ce) of 1.0 ng/mL (n = 10), propofol at Ce of 0.5 µg/mL (n = 10), or sevoflurane at 0.2 minimum alveolar concentration (MAC) (n = 10), and recovery from the anesthetics. Study 2: NEPs were recorded at control and under administration of higher dose anesthetics: propofol at Ce of 0.5 and 1.0 µg/mL (n = 10) or sevoflurane at 0.2 and 0.5 MAC (n = 10). A P-value < 0.016 was considered statistically significant in multiple analyses.

RESULTS

Study 1: Remifentanil at Ce of 1.0 ng/mL significantly suppressed the amplitude of NEPs (mean amplitude (standard deviation) of control vs. remifentanil administration: 16.8 µV (3.8) vs. 10.1 µV (2.5), P < 0.001). Propofol and sevoflurane did not suppress the amplitude significantly. Study 2: Propofol at Ce of 0.5 and 1.0 µg/mL and sevoflurane at 0.2 and 0.5 MAC did not suppress the amplitude significantly.

CONCLUSION

The amplitude of A-δ fiber selective NEPs was suppressed by remifentanil but not propofol or sevoflurane. NEPs with intraepidermal electrical stimulation can assess the analgesic effect of anesthetics.

CLINICAL TRIAL NUMBER

UMIN000038214 REGISTRY URL: https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000043328.

Prediction of blood pressure changes during surgical incision using the minimum evoked current of vascular stiffness value under sevoflurane anesthesia

Necessary and sufficient opioids should be administered for safe and stable anesthesia. However, opioid sensitivity varies among individuals. We previously reported that sympathetic responses to nociceptive stimuli under propofol anesthesia could be predicted by measuring the minimum evoked current of the vascular stiffness value (MECK). However, this result has only been proven under propofol anesthesia. We propose that MECK could be used under anesthesia with a volatile anesthetic. Thirty patients undergoing laparotomy with sevoflurane anesthesia received 0.7 minimum alveolar concentration (MAC) sevoflurane and intravenous remifentanil at a constant concentration of 2 ng/mL, followed by tetanic stimulation, to measure MECK. After tetanic stimulation, the same anesthetic conditions were maintained, and the rate of change in systolic blood pressure (ROCBP) during the skin incision was measured. The correlation coefficient between the MECK and ROCBP during skin incision under sevoflurane anesthesia was R =  - 0.735 (P < 0.01), similar to that in a previous study with propofol (R =  - 0.723). Thus, a high correlation was observed. The slope of the linear regression equation was - 0.27, similar to that obtained in the study on propofol (- 0.28). These results suggest that, as with propofol anesthesia, MECK can be used as a predictive index for ROCBP under 0.7 MAC sevoflurane anesthesia.Clinical trial registration: Registry, University hospital Medical Information Network; registration number, UMIN000047425; principal investigator's name, Noboru Saeki; date of registration, April 8, 2022.

Melatonin attenuates sevoflurane-induced hippocampal damage and cognitive deficits in neonatal mice by suppressing CypD in parvalbumin neurons

BACKGROUND

Sevoflurane, a commonly administered inhaled anesthetic, is found to induce synaptic and mitochondrial damage in neonatal mice. Mitochondrial membrane potential (MMP) changes, mediated by Cyclophilin D (CypD), are implicated in mitochondrial function. Melatonin, known for its significant neuroprotective properties, was investigated in this study to elucidate its mechanisms in mitigating the cognitive impairment caused by sevoflurane.

METHODS

The mice were categorized into several groups, including the control, vehicle, sevoflurane, vehicle plus sevoflurane, and melatonin plus sevoflurane groups. From postnatal day 6 to day 8, the mice were administered inhaled sevoflurane or intraperitoneal melatonin. MMP and reactive oxygen species (ROS) were measured using appropriate detection kits. The protein expression levels of PSD95, Synapsin Ⅰ, and CypD in the hippocampus were analyzed through western blotting in acute and prolonged terms. Immunofluorescence staining was used to assess the co-localizations of PSD95 or CypD in parvalbumin (PV) neurons. Cognitive ability was evaluated through novel object recognition, social interaction experiment, and the Morris water maze.

RESULTS

The findings revealed that repeated exposure to sevoflurane in neonatal mice resulted in cognitive and synaptic impairment. Furthermore, melatonin administration suppressed the ROS and CypD protein expression, enhanced the MMP in mitochondria and synaptic protein expression in PV neurons, and ameliorated cognitive deficits.

CONCLUSION

Melatonin alleviated sevoflurane-induced cognitive deficits by suppressing CypD and promoting synaptic development in hippocampal PV neurons. These results provide valuable insights into a promising therapeutic approach for preventing neurotoxic injuries caused by general anesthetics.

Effects of propofol and sevoflurane on social and anxiety-related behaviours in sleep-deprived rats

BACKGROUND

Sleep disorders can profoundly affect neurological function. We investigated changes in social and anxiety-related brain functional connectivity induced by sleep deprivation, and the potential therapeutic effects of the general anaesthetics propofol and sevoflurane in rats.

METHODS

Twelve-week-old male Sprague-Dawley rats were subjected to sleep deprivation for 20 h per day (from 14:00 to 10:00 the next day) for 4 consecutive weeks. They were free from sleep deprivation for the remaining 4 h during which they received propofol (40 mg kg-1 i.p.) or sevoflurane (2% for 2 h) per day or no treatment. These cohorts were instrumented for EEG/EMG recordings on days 2, 14, and 28. Different cohorts were used for open field and three-chambered social behavioural tests, functional MRI, nuclear magnetic resonance spectroscopy, and positron emission tomography imaging 48 h after 4 weeks of sleep deprivation.

RESULTS

Propofol protected against sleep deprivation-induced anxiety behaviours with more time (44.7 [8.9] s vs 24.2 [4.1] s for the sleep-deprivation controls; P<0.001) spent in the central area of the open field test and improved social preference index by 30% (all P<0.01). Compared with the sleep-deprived rats, propofol treatment enhanced overall functional connectivity by 74% (P<0.05) and overall glucose metabolism by 30% (P<0.01), and improved glutamate kinetics by 20% (P<0.05). In contrast, these effects were not found after sevoflurane treatment.

CONCLUSIONS

Unlike sevoflurane, propofol reduced sleep deprivation-induced social and anxiety-related behaviours. Propofol might be superior to sevoflurane for patients with sleep disorders who receive anaesthesia, which should be studied in clinical studies.

The differential cancer growth associated with anaesthetics in a cancer xenograft model of mice: mechanisms and implications of postoperative cancer recurrence

Anaesthetics may modify colorectal cancer cell biology which potentially affects long-term survival. This study aims to compare propofol and sevoflurane regarding with the direct anaesthetic effects on cancer malignancy and the indirect effects on host immunity in a cancer xenograft mode of mice. Cultured colon cancer cell (Caco-2) was injected subcutaneously to nude mice (day 1). Mice were exposed to either 1.5% sevoflurane for 1.5 h or propofol (20 μg g-1; ip injection) with or without 4 μg g-1 lipopolysaccharide (LPS; ip) from days 15 to 17, compared with those without anaesthetic exposure as controls. The clinical endpoints including tumour volumes over 70 mm3 were closely monitored up to day 28. Tumour samples from the other cohorts were collected on day 18 for PCR array, qRT-PCR, western blotting and immunofluorescent assessment. Propofol treatment reduced tumour size (mean ± SD; 23.0 ± 6.2mm3) when compared to sevoflurane (36.0 ± 0.3mm3) (p = 0.008) or control (23.6 ± 4.7mm3). Propofol decreased hypoxia inducible factor 1α (HIF1α), interleukin 1β (IL1β), and hepatocyte growth factor (HGF) gene expressions and increased tissue inhibitor of metalloproteinases 2 (TIMP-2) gene and protein expression in comparison to sevoflurane in the tumour tissue. LPS suppressed tumour growth in any conditions whilst increased TIMP-2 and anti-cancer neutrophil marker expressions and decreased macrophage marker expressions compared to those in the LPS-untreated groups. Our data indicated that sevoflurane increased cancer development when compared with propofol in vivo under non-surgical condition. Anaesthetics tested in this study did not alter the effects of LPS as an immune modulator in changing immunocyte phenotype and suppressing cancer development.

Anesthetic Preferences for Cardiac Anesthesia: A Survey of the Society of Cardiovascular Anesthesiologists

BACKGROUND

Volatile anesthetics have been historically preferred for cardiac anesthesia, but the evidence for their superiority to intravenous agents is mixed. We conducted a survey to better understand the current state of practice and the rationale behind provider preferences for anesthesia for cardiac surgery with cardiopulmonary bypass. We hypothesized that anesthetic preference would vary considerably among surveyed providers without a clear majority, as would the rationale behind those preferences.

METHODS

Email invitations were sent to members of the Society of Cardiovascular Anesthesiologists, who were asked to identify the anesthetics or sedatives they typically prefer to administer during induction, prebypass, bypass, postbypass, and postoperative periods and why they prefer those agents. Members' beliefs regarding the importance of anesthetics on postoperative outcomes were also assessed.

RESULTS

Invitations were sent on 2 separate dates to 3328 and 3274 members, of whom 689 (21%) responded. The median (interquartile range [IQR]) respondent age was 45 (37-56) years, 79% were men, and 75% were fellowship trained. The most frequently chosen drug for induction was propofol (80%). Isoflurane was the most frequently selected primary agent for the prebypass (57%), bypass (62%), and postbypass periods (50%). Sevoflurane was the second most frequently selected (30%; 17%, and 24%, respectively). Propofol was the third most frequently selected agent for the bypass (14%) and postbypass periods (17%). Ease of use was the most frequently selected reason for administering isoflurane and sevoflurane for each period. During bypass, the second most frequently selected rationale for using isoflurane and sevoflurane was institutional practice. A total of 76% responded that the perfusionist typically delivers the bypass anesthetic. Ischemic preconditioning, organ protection, and postoperative cognitive function were infrequently selected as rationales for preferring the volatile anesthetics. Most respondents (73%) think that anesthetics have organ-protective properties, especially isoflurane (74%) and sevoflurane (59%), and 72% believed that anesthetic choice contributes to patient outcome. The median (IQR) agreement (0 = strongly disagree to 100 = strongly agree) was 72 (63-85) for the statement that "inhaled anesthetics are an optimal maintenance anesthetic for cardiac surgery."

CONCLUSIONS

In a survey of cardiac anesthesiologists, a majority of respondents indicated that they prefer volatile anesthetics for maintenance of anesthesia, that anesthetic selection impacts patient outcomes, and that volatile anesthetics have organ-protective properties. The members' rationales for preferring these agents possibly reflect that practical considerations, such as ease of use, effectiveness, and institutional practice, also influence anesthetic selection during cardiac surgery in addition to considerations such as organ protection.

The deleterious impact of exposure to different inhaled anesthetics is time dependent

In this study, the effects of exposure to isoflurane, sevoflurane and desflurane on the oxidative response and inflammation at different times was analyzed in the lungs of adult C57BL/6 mice. 120 animals were divided into 3 groups (n = 40): Isoflurane (ISO), Sevoflurane (SEV) and Desflurane (DES) and exposed to these anesthetics for 1 h (n = 10), 2 h (n = 10) and 3 h (n = 10), at a minimum alveolar concentration (MAC) equal to 1. The control group (CG) (n = 10) was exposed to ambient air. 24 h after the experimental protocol, the animals were euthanized and the bronchoalveolar lavage fluid (BALF), blood and lung tissue samples were collected. In the BALF, animals exposed to isoflurane for 2 h and 3 h showed a greater influx of leukocytes, especially macrophages compared to the CG. The ISO3h had lower leukocyte counts in the peripheral blood compared to CG, ISO1h and ISO2h. There was an increase in CCL-2 levels in the ISO3h compared to the CG. Superoxide dismutase activity was higher in ISO1h compared to CG. The activity of catalase was higher in the ISO1h and ISO2h compared to the CG. The lipid peroxidation, as well as carbonylated protein were higher in the ISO3h compared to the CG (p < 0.05). Similar results were observed in the exposure of SEV and DES compared to inflammation and redox imbalance in different periods. This study demonstrated that time is a determinant to promote a local and systemic inflammatory response to different inhalational anesthetics in a healthy murine model.

Flavonoids from Rhododendron nivale Hook. f delay aging via modulation of gut microbiota and glutathione metabolism

BACKGROUND

Rhododendron nivale Hook. f (R.n), one of the four Manna Stash used in Tibetan medicine to delay aging, possesses anti-aging pharmacological activity. However, which R.n ingredients contain anti-aging properties and the underlying mechanisms involved are unclear.

HYPOTHESIS/PURPOSE

Based on interactions between gut microbiota and natural medicines and the important role of gut microbiota in anti-aging, the study investigated the hypothesis that R.n possesses anti-aging properties and the interaction of gut microbiota with R.n is responsible for its anti-aging effects.

STUDY DESIGN

The primary active ingredients of R.n and their target function and pathway enrichment were explored. An aging mouse model was used to clarify the underlying anti-aging mechanisms of R.n.

METHODS

Chromatography, spectroscopy, nuclear magnetic technology, and pharmacology were used to reveal the major active ingredients of ethanol extract residues of R.n (RNEA). The target function and pathway enrichment of these active ingredients were explored. Plasma metabolomics coupled with intestinal flora evaluation and bioinformatics analysis was used to clarify the underlying anti-aging mechanisms of RNEA.

RESULTS

Myricetin-3-β-D-xylopyranoside, hyperin, goospetin-8-methyl ether 3-β-D-galactoside, and diplomorphanin B were separated and identified from RNEA. The network pharmacology study revealed that the active ingredients' target function and pathway enrichment focused mainly on the glutathione antioxidant system. In a D-galactose-induced mouse model of aging, RNEA was shown to possess suitable anti-aging pharmacological activity, as indicated by the amelioration of memory loss and weakened superoxide dismutase and glutathione peroxidase activities. Plasma metabolomics coupled with intestinal flora examination and bioinformatics analysis revealed that RNEA could regulate the expression of glutathione-related enzymes and ameliorate D-galactose-induced imbalances in methionine, glycine, and serine, and betaine and galactose metabolism. The results showed that RNEA reshaped the disordered intestinal flora and mitigated the D-galactose-mediated decline in glutathione oxidase expression, further confirming that the anti-aging effect of RNEA was closely related to regulation of the glutathione antioxidant system.

CONCLUSION

RNEA, consisting of myricetin-3-β-D-xylopyranoside, hyperin, goospetin-8-methyl ether 3-β-D-galactoside, and diplomorphanin B, possesses anti-aging activity. The anti-aging effect of RNEA might be due to reshaping intestinal flora homeostasis, increasing the expression of glutathione peroxidase 4 in the intestines and liver, enhancing glutathione peroxidase activity, and reinforcing the glutathione antioxidant system.

Ethnopharmacological impact of Melaleuca rugulosa (Link) Craven leaves extract on liver inflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Melaleuca species have been used by many ethnic communities for the management and treatment of several ailments as hemorrhoids, cough, skin infections, rheumatism, sore throat, pain, inflammation, and digestive system malfunctions. However, the detailed mechanistic pharmacological effect of Melaleuca rugulosa (Link) Craven leaves in the management of liver inflammation has not been yet addressed.

AIM OF THE STUDY

The present study aimed to evaluate the anti-inflammatory, antioxidant, and antiapoptotic capacities of the aqueous methanol extract of M. rugulosa leaves in relevance to their flavonoid content using an appropriate in vivo model.

MATERIALS AND METHODS

The aqueous methanol extract of M. rugulosa leaves was administered to the rats at three non-toxic doses (250, 500, and 1000 mg/kg) for seven days prior to the initiation of liver-injury induced by paracetamol (3 g/kg). Liver enzymes including alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) were evaluated in serum samples. The oxidative stress markers including reduced glutathione (GSH), malondialdehyde (MDA), and nitric oxide (NO) levels as well as the inflammatory markers such as tumour necrosis factor-alpha (TNF-α) and nuclear factor-kappa B (NF-κB), were assessed in liver homogenate. The results were supported by histopathological and immuno-histochemical studies. The phytochemical investigation of the flavonoid-rich fraction of the aqueous methanol extract was accomplished using different chromatographic and spectroscopic techniques.

RESULTS

The aqueous methanol extract of M. rugulosa leaves showed a powerful hepatoprotective activity evidenced by the significant reduction of MDA and NO levels, as well as increasing GSH and catalase activity. Moreover, the extract exhibited anti-inflammatory and antiapoptotic activities witnessed by decreasing TNF-α, NF-κB, iNOS, p-JNK, caspase-3, BAX, and increasing Bcl-2 levels. Moreover, the pretreatment of rats with all doses of M. rugulosa leaves extract showed a significant decrease in liver weight/body weight (LW/BW) ratio, and total bilirubin induced by paracetamol. On the other hand, the chromatographic separation of the flavonoid-rich fraction afforded twenty known flavonoids namely; iso-orientin (1), orientin (2), isovitexin (3), vitexin (4), quercetin-3-O-β-D-glucuronid methyl ether (5), quercetin-3-O-β-D-mannuronpyranoside (6), isoquercetin (7), quercitrin (8), kaempferol-3-O-β-D-mannuronopyranoside (9), kaempferol-7-O-methyl ether-3-O-β-D-glucopyranoside (10), guaijaverin (11), avicularin (12), kaempferide-3-O-β-D-glucopyranoside (13), astragalin (14), afzelin (15), luteolin (16), apigenin (17), quercetin (18), kaempferol (19), and catechin (20).

CONCLUSION

The aqueous methanol extract of M. rugulosa leaves showed potential hepatoprotective, antioxidant, and anti-inflammatory activities against paracetamol-induced liver inflammation which is correlated at least in part to its considerable phenolic content.

The effects of total intravenous and inhalation anesthesia maintenance on tissue oxygenation in coronary artery bypass graft surgery

OBJECTIVE

The aim of this study is to evaluate the effect of total intravenous anesthesia (TIVA) and inhalational anesthesia techniques on tissue oxygenation in cardiac surgery. We compared the effects of midazolam-based TIVA and sevoflurane-based (SEVO) inhalation anesthesia maintenance on intraoperative central and regional tissue oxygenation parameters.

PATIENTS AND METHODS

A total of 104 adult patients who were scheduled for elective isolated coronary bypass surgery were included in the study. All patients were divided into two groups: the TIVA group consisted of total intravenous anesthesia maintenance patients (n=52) and the SEVO group consisted of patients with inhalation anesthesia with sevoflurane maintenance (n=52). Tissue oxygenation values were observed with left-right cerebral and somatic left forearm Near-Infrared Spectroscopy (NIRS) sensors. The hemodynamic parameters, NIRS StO2, central (ScvO2) and peripheral venous oxygen saturations of the patients were recorded at six intraoperative time points.

RESULTS

The effects of midazolam-based TIVA and sevoflurane-based inhalation anesthesia maintenance on intraoperative central and peripheral tissue oxygenation parameters were compared and it was found that in the left forearm NIRS StO2 and ScvO2 values were higher in the SEVO group than the TIVA group. Although not significantly different, forearm regional venous oxygen saturation was also higher in the SEVO group.

CONCLUSIONS

The effects of anesthetic drugs on regional tissue oxygenation can become important in critical patients and challenging surgeries. Sevoflurane-based anesthesia provides better tissue oxygenation than TIVA in patients undergoing coronary bypass surgery.

Therapeutic potential of pregnenolone and pregnenolone methyl ether on depressive and CDKL5 deficiency disorders: Focus on microtubule targeting

Pregnenolone methyl-ether (PME) is a synthetic derivative of the endogenous neuroactive steroid pregnenolone (PREG), which is an important modulator of several brain functions. In addition to being the precursor of steroids, PREG acts directly on various targets including microtubules (MTs), the functioning of which is fundamental for the development and homeostasis of nervous system. The coordination of MT dynamics is supported by a plethora of MT-associated proteins (MAPs) and by a specific MT code that is defined by the post-translational modifications of tubulin. Defects associated with MAPs or tubulin post-translational modifications are linked to different neurological pathologies including mood and neurodevelopmental disorders. In this review, we describe the beneficial effect of PME in major depressive disorders (MDDs) and in CDKL5 deficiency disorder (CDD), two pathologies that are joint by defective MT dynamics. Growing evidence indeed suggests that PME, as well as PREG, is able to positively affect the MT-binding of MAP2 and the plus-end tracking protein CLIP170 that are both found to be deregulated in the above mentioned pathologies. Furthermore, PME influences the state of MT acetylation, the deregulation of which is often associated with neurological abnormalities including MDDs. By contrast to PREG, PME is not metabolised into other downstream molecules with specific biological properties, an aspect that makes this compound more suitable for therapeutic strategies. Thus, through the analysis of MDDs and CDD, this work focuses attention on the possible use of PME for neuronal pathologies associated with MT defects.

Genotoxic and mutagenic effects of methyl ether dillapiole on the development of Aedes aegypti (Diptera: Culicidae)

Dillapiole, extracted from Piper aduncum essential oil and its derivatives, has been shown to be a potential alternative to the control of Aedes aegypti, which has become resistant to synthetic insecticides. Methyl ether dillapiole (MED) and temephos (TM) were compared to complement the data on the genotoxicity and developmental changes of Ae. aegypti. Over four generations (G₁ -G₄ ), third stage larvae were treated with MED at 60, 80 and 100 μg/mL and TM at 0.002, 0.005 and 0.007 μg/mL for 4 h. Adult females were separated to estimate oviposition and hatching rates, and total egg length. Over the four generations, a significant reduction was recorded in oviposition and hatching rates, and in mean egg length (Tukey, P < 0.05), compared with the negative control (NC). Cytological slide preparations were done from adult oocytes and larval neuroblasts. The cumulative effects of genotoxic (bridges, budding and nuclear fragmentation) and mutagenic (micronucleus and chromosomal breakage) damage was observed in the neuroblasts and oocytes of exposed mosquitoes. Developmental changes and damage to the genome of MED-treated Ae. aegypti were greater than those caused by TM. Further studies should focus on understanding the effects of the MED molecule on Ae. aegypti.

Comparison of blood pressure and pain rating index used for depth regulation of sevoflurane anaesthesia

OBJECTIVES

The Pain Rating index (PRi) is a new parameter for regulating analgesic depth of anaesthesia based on wavelet analysis. The aim of this study was to investigate the feasibility of PRi for depth regulation of sevoflurane anaesthesia.

METHODS

We conducted a monocentric randomized controlled study from September 2017 to June 2018 in patients undergoing anterior cervical discectomy and fusion (ACDF) (n=44). Patients were randomly allocated into two groups and assigned 22 cases to each group: systolic blood pressure group (SBP group) and pain rating index group (PRi group). In SBP group, sevoflurane inhalation concentration (Cs) was adjusted to maintain SBP values at baseline values -20%～+20%; in PRi group, Cs was adjusted to maintain PRi values between 50 and 70. The primary endpoint was anaesthesia recovery time. Secondary endpoints included extubation time, sevoflurane consumption, number of intraoperative haemodynamic instability events /interventions, number of adverse events and postoperative visual analogue scale for pain.

RESULTS

Patient demographic characteristics, surgical time and anaesthesia time did not differ between groups. Anaesthesia recovery time was shorter in PRi group than in SBP group (17.5±3.8min vs 21.5±2.8 min; P=0.001). Extubation time was also shorter in PRi group than in SBP group (21.9±1.7min vs 24.1±2.5min; P=0.001). Sevoflurane consumption was lower in PRi group than in SBP group (15.5±4.1ml vs 20.0±2.5ml; P=0.001).

CONCLUSIONS

PRi was feasible to regulate depth of sevoflurane anaesthesia, which could shorten anaesthesia recovery time and extubation time, reduce sevoflurane consumption during general anaesthesia in patients undergoing cervical vertebra surgery.

Sevoflurane Exposure Results in Sex-Specific Transgenerational Upregulation of Target IEGs in the Subiculum

Large body of animal work and emerging clinical findings have suggested that early exposure to anesthetics may result in increased risk of learning disabilities and behavioral impairments. Recent studies have begun to investigate anesthesia-induced epigenetic modifications to elucidate their role in behavioral and neurodevelopmental abnormalities. Here we examine sevoflurane-induced transgenerational modifications of subicular neuronal DNA methylation and expression of immediate early genes (IEGs), arc and junB, crucial to synaptic plasticity and normal neuronal development. We show that 6 h sevoflurane exposure in postnatal day 7 rat pups resulted in decreased neuronal 5-methycytosine, indicating reduced DNA methylation. This effect is transgenerationally expressed in offspring born to exposed mothers which is of importance considering that decreased DNA methylation in the brain has been linked with functional decline in learning and memory. We further show that sevoflurane exposure induces upregulation of Arc and JunB mRNA expression, 42.7% and 35.2%, respectively. Transgenerational changes in Arc and JunB mRNA were sexually dimorphic only occurring in males born to exposed females, expressed as upregulation of Arc and JunB mRNA, 71.6% and 74.0%, respectively. We further investigated correlation between altered arc promoter methylation and observed upregulation of Arc mRNA and observed that sevoflurane reduced methylation in the 5-upstream promoter region of females exposed to sevoflurane. Transgenerational hypomethylation and modifications to IEGs crucial to synaptic plasticity, observed following neonatal sevoflurane exposure could contribute to morphological and cognitive deficits known to occur with neonatal sevoflurane exposure.

A Comparison of the Effects of Prolonged (>10 Hour) Low-flow Sevoflurane, High-flow Sevoflurane, and Low-flow Isoflurane Anaesthesia on Hepatorenal Function in Orthopaedic Patients

This study compared the effects of low-flow sevoflurane, high-flow sevoflurane and low-flow isoflurane on hepatorenal function during and after more than 10 hours of anaesthesia. Twenty-five patients scheduled for elective orthopaedic surgery were categorized into three groups; low-flow sevoflurane (fresh gas flow at 1 litre/min, n=9), high-flow sevoflurane (5 l/min, n=7), or low-flow isoflurane (1 l/min, n=9). Inspiratory compound A concentrations were measured. The groups had similar duration of anaesthesia and exposure to anaesthetic agents. The area under the curve of concentration (mean, SD) of compound A in the low-flow sevoflurane group (359.8, 106.1 ppm.h) was greater than that in the high-flow sevoflurane group (61.1, 29.3 ppm.h; P<0.01). All groups showed normal plasma creatinine and creatinine clearance, and transient postoperative increases in plasma alanine aminotrans-ferase and alpha glutathione-S-transferase, as well as urinary glucose and alpha glutathione-S-transferase, with no significant differences between groups. There were no significant relationships between the area under the curve of concentration of compound A and the biomarkers. These findings suggest that prolonged anaesthesia with low-flow sevoflurane has similar effects on hepatorenal function to prolonged anaesthesia with high-flow sevoflurane and low-flow isoflurane.

Effect of Newer Anaesthetics on Duration of Stay in Postanaesthesia Care Unit in Patients Undergoing Major Abdominal Surgery

Newer anaesthetic agents, such as remifentanil and sevoflurane, are more expensive than conventional anaesthetics, such as isoflurane and fentanyl. However, newer anaesthetics might outweigh their higher acquisition costs by reducing length of stay in the postanaesthesia care unit and thereby reducing personnel costs. We retrospectively investigated the influence of newer anaesthetics on time to eligibility for discharge from the postanaesthesia care unit in consecutive patients undergoing major abdominal surgery.

Using a chart review, patients undergoing major abdominal surgery with three different anaesthetic regimens (isoflurane/fentanyl (n=80), sevoflurane/fentanyl (n=40), and sevoflurane/remifentanil (n=42)) were compared regarding duration of anaesthesia, surgery, time till extubation, and time to eligibility for discharge from the post-anaesthesia care unit.

Extubation times were shorter in patients in the sevoflurane/fentanyl and the sevoflurane/remifentanil groups compared to patients in the isoflurane/fentanyl group. Time to eligibility to discharge from the postanaesthesia care unit was similar in isoflurane/fentanyl and sevoflurane/fentanyl group. In the sevoflurane/fentanyl group, time to eligibility for discharge from the unit showed a tendency to be increased (P=0.08), however these patients were significantly older compared to the other groups.

Sevoflurane and remifentanil did not appear to reduce time to eligibility to discharge from the postanaesthesia care unit in our patients undergoing major abdominal surgery compared to isoflurane and fentanyl. This study highlighted the necessity for carefully planned transition from remifentanil to other longer-acting analgesia in our patients.

Anaesthesia for Electroconvulsive Therapy: A Comparison of Sevoflurane with Propofol

This study was a prospective audit of patients receiving either intravenous induction of anaesthesia with propofol 2 mg/kg or inhalational induction using 8% sevoflurane for patients undergoing electroconvulsive therapy (ECT). All patients received inhaled 50% nitrous oxide. The anaesthetic agent was determined by psychiatrist preference. Each psychiatrist nominated only one induction technique for all his or her patients. Seventy treatments were studied in each group. Induction time was longer in the sevoflurane group. The time from commencing induction to loss of verbal contact was [mean (SD)] 64 (29.9) seconds for sevoflurane and 36 (33.6) seconds for propofol (P=0.001). Time to loss of eyelash reflex was 82 (32.6)s for sevoflurane and 44 (17.9)s for propofol (P<0.001). The duration of seizure activity was longer in sevoflurane patients, 35 (17.8)s, compared with 20 (9.8)s in the propofol group (P< 0.001). Discharge times were similar. Minor adverse effects occurred in three patients, all in the sevoflurane group (one bradycardia and two episodes of post-procedural nausea). There were no major adverse events in either group. Propofol and sevoflurane both appear to be suitable agents for induction of anaesthesia for ECT.

Sevoflurane versus Propofol for Induction of Anaesthesia for Electroconvulsive Therapy: A Randomized Crossover Trial

Propofol is often used to induce anaesthesia for electroconvulsive therapy. Some patients who receive propofol have fits of poor quality or inadequate duration despite increasing electroconvulsive therapy doses. Sevoflurane has been reported to exhibit pro-convulsant properties in some “at-risk” patients during anaesthesia for other procedures. The purpose of this study was to perform a randomized crossover trial in patients undergoing electroconvulsive therapy, comparing the effects on seizure parameters of propofol versus sevoflurane induction. Patients were randomly allocated to receive either sevoflurane or propofol for their first treatment. In the subsequent treatment the alternative agent was used.

Patients in both treatment groups exhibited equally good fits, with those in the sevoflurane group having slightly better morphology, which is the most subjective of the parameters measured. The sevoflurane administrations were associated with slightly higher pulse rates and blood pressures.

Sevoflurane provides a suitable alternative to propofol for anaesthesia in patients undergoing electroconvulsive therapy, although the slightly greater pulse rate rise and blood pressure rise should be considered in patients with ischaemic heart disease.

The Relationship between Calculated Effect-site Sevoflurane Levels and Awakening from Anaesthesia

We have previously described a system that displays real-time estimates of effect-site sevoflurane concentrations. Estimates of effect-site levels should be similar to minimum alveolar concentration (MAC) values, which are determined after allowing time for equilibrium. This study aimed to determine estimated effect-site sevoflurane concentrations at awakening from routine anaesthesia and to compare this with published estimates of MAC-awake. If these values were similar, this would validate our approach to the calculation of effect-site concentration. Sixty-five patients undergoing a variety of surgical procedures were observed. Prior to disconnection from the breathing circuit, forward estimates of effect-site sevoflurane were recorded. Patients were observed in the postanaesthesiacare unit and the time at which they responded to comm and wasrecorded. Age-adjusted effect-site sevoflurane at the time of awakeningwas determined. Correlation with patient, surgical and anaestheticfactors includingage, gender, ASA status and intraoperative opioid usage were explored. Mean age-adjusted calculated effect-site concentration at awakening was 0.59 (SD 0.27) vol%. This value is within the range of values determined for MAC-awake of sevoflurane. There was no correlation with any of the demographic or anaesthetic factors, but patients undergoing major surgery woke at a significantly lower mean sevoflurane level. These results support the use of effect-site sevoflurane concentration to guide administration of anaesthesia.

Suppression of Long Non-Coding RNA LINC00652 Restores Sevoflurane-Induced Cardioprotection Against Myocardial Ischemia-Reperfusion Injury by Targeting GLP-1R Through the cAMP/PKA Pathway in Mice

BACKGROUND/AIMS

Long non-coding RNA (lncRNA) and glucagon-like peptide 1 receptor (GLP-1R) are crucial for heart development and for adult heart structural maintenance and function. Herein, we performed a study to explore the effect of lncRNA LINC00652 (LINC00652) on myocardial ischemia-reperfusion (I/R) injury by targeting GLP-1R through the cyclic adenosine monophosphate-protein kinase A (cAMP/PKA) pathway.

METHODS

Bioinformatics software was used to screen the long-chain non-coding RNAs associated with myocardial ischemia-reperfusion and to predict target genes. The mRNA and protein levels of LINC00652, GLP-1R and CREB were detected by RT-qPCR and western blotting. In order to identify the interaction between LINC00652 and myocardial I/R injury, the cardiac function, the hemodynamic changes, the pathological changes of the myocardial tissues, the myocardial infarct size, and the apoptosis of myocardial cells of mice were measured. Meanwhile, the levels of serum IL-1β and TNF-α were detected.

RESULTS

LINC00652 was overexpressed in the myocardial cells of mice with myocardial I/R injury. GLP-1R is the target gene of LINC00652. We also determined higher levels of LINC00652 and GLP-1R in the I/R modeled mice. Additionally, si-LINC00652 decreased cardiac pathology, infarct size, apoptosis rates of myocardial cells, and levels of IL-1β and TNF-α, and increased GLP-1R expression cardiac function, normal hemodynamic index, and the expression and phosphorylation of GLP-1R and CREB proteins.

CONCLUSION

Taken together, our key findings of the present highlight LINC00652 inhibits the activation of the cAMP/PKA pathway by targeting GLP-1R to reduce the protective effect of sevoflurane on myocardial I/R injury in mice.

MicroRNA-374 Exerts Protective Effects by Inhibiting SP1 Through Activating the PI3K/Akt Pathway in Rat Models of Myocardial Ischemia-Reperfusion After Sevoflurane Preconditioning

BACKGROUND/AIMS

Ischemic heart disease is a leading cause of death in cardiovascular diseases, and microRNAs (miRs) have been reported to be potential therapeutic targets in heart disease. Herein, this study aims to investigate the effects of microRNA (miR)-374 on myocardial ischemia-reperfusion (I/R) injury in rat models pretreated with sevoflurane by targeting SP1 through the PI3K/Akt pathway.

METHODS

SD rats were grouped into sham, I/R and sevoflurane + I/R (sevoflurane preconditioning and I/R) groups. The biochemical indicators, pathological changes, positive expression of SP1 protein, and apoptosis rates were measured using biochemical detection, Evans blue-TTC staining, immunohistochemistry and TUNEL staining. RT-qPCR and Western blotting were used to investigate the expression of miR-374 mRNA and the protein expression of SP1, PI3K, HO-1, p53, iNOS, c-fos, Akt/p-Akt, and GSK-3β/p-GSK-3β. Cardiomyocytes were treated with miR-374 mimics, miR-374 inhibitors, or siRNA-SP1. Cardiomyocyte proliferation and cycle distribution and apoptosis were studied by MTT and flow cytometry.

RESULTS

Compared with the I/R group, in the sevoflurane + I/R group, serum SOD and IL-10 increased, while MDA, LDH, CK, TNF-α, IL-6 and IL-10 decreased, as did the percentage of infarct area, the positive rate of SP1 and the apoptosis index. The expression of SP1, p53, iNOS and c-fos decreased, and the miR-374 expression of PI3K, HO-1, Akt/p-Akt, GSK-3β/p-GSK-3β increased. With the upregulation of miR-374 and the downregulation of SP1, the expression of SP1, p53, iNOS and c-fos decreased, as did the proportion of cells in G1 phase and the apoptosis rate; the expression of PI3K, HO-1, Akt/p-Akt, GSK-3β/p-GSK-3β increased. The results in the miR-374 inhibitor group contrasted with the above results.

CONCLUSION

The results indicated that miR-374 could alleviate myocardial I/R damage in rat models pretreated with sevoflurane by targeting SP1 by activating the PI3K/Akt pathway.

Effects of sevoflurane on apoptosis, BDNF and cognitive functions in neonatal rats

OBJECTIVE

To evaluate the early and late effects of sevoflurane on the neonatal brain.

BACKGROUND

Sevoflurane is the most used anaesthetics in neonatal subjects.

METHODS

The study included 7-day-old male Wistar-Albino rats (n = 30), which were divided into the two groups according to the anaesthetic received: sevoflurane (S) and control group (C). Half of each group was sacrificed six hours after anaesthesia (early, E) while the remaining subjects were sacrificed six weeks later (late, L). The serum brain-derived-neurotrophic factor (BDNF), brain BDNF and caspase-3 were evaluated. In addition, elevated plus arm test and Morris water test were performed in the late group.

RESULTS

BDNF levels were higher in the late groups than in the early ones (p < 0.05). BDNF levels in cerebral cortex were higher in the Group CE than in the Group CL and SL (p < 0.05). There was a significant negative correlation between serum BDNF and cortex BDNF levels (p = 0.003, r = -0.425). Cortex caspase 3 levels were significantly higher in the Groups SE and SL than in the Group CE and CL (p < 0.05). There was no significant difference between the groups in the terms of open arm index, locomotor activity and Morris water test.

CONCLUSIONS

Although sevoflurane induced apoptosis, it didn't affect BDNF levels and showed no long-term negative effects on learning and anxiety in neonatal rats (Tab. 1, Fig. 3, Ref. 26).

Sevoflurane causes greater QTc interval prolongation in chronically hyperglycemic patients than in normoglycemic patients

QTc interval prolongation is a serious diabetic complication and increases mortality rate. Hyperglycemia inhibits the rapid component of delayed rectifier potassium channel currents (Ikr) and prolongs the QTc interval on electrocardiograms. Sevoflurane also inhibits the Ikr and causes QTc interval prolongation. In fact, torsade de pointes occurred in a patient with poorly controlled diabetes mellitus during sevoflurane anesthesia. We enrolled 74 patients, including 37 normoglycemic patients (glycated hemoglobin [HbA1c]: <6.5%) (NG group) and 37 chronically hyperglycemic patients (HbA1c: ≥6.5%) (HG group). Anesthesia was induced with 2 mg/kg propofol and 0.3 μg/kg/min remifentanil, and maintained with 2% sevoflurane in 40% O2 and 0.2-0.3 μg/kg/min remifentanil. The QT interval and Tp-e interval (from the peak to the end of the T wave) were measured before and at 5, 10, 30, 60, 90, and 120 min after the administration of sevoflurane and adjusted for the patient's heart rate (QTc and Tp-ec, respectively). P-values of <0.05 were considered statistically significant. The QTc and the Tp-ec intervals of the two groups did not differ significantly before the administration of sevoflurane. The QTc interval gradually increased with time in both groups and was significantly longer than the baseline value at 10 min after the administration of sevoflurane in both groups. The QTc interval of the HG group was significantly longer than that of the NG group at 90 min and 120 min after the administration of sevoflurane. The Tp-ec interval was not affected by sevoflurane in either group.We have demonstrated that sevoflurane significantly prolongs the QTc interval, and that the extent of the prolongation is significantly greater in chronically hyperglycemic patients than in normoglycemic patients. Although Tp-ec is not affected by sevoflurane, it should be noted that the simultaneous blockade of potassium channels would increase the risk of arrhythmias.

Sevoflurane protects rat brain endothelial barrier structure and function after hypoxia-reoxygenation injury

Background

After cerebral injury blood-brain barrier disruption significantly impairs brain homeostasis. Volatile anesthetics have been shown to be protective in ischemia-reperfusion injury scenarios. Their impact on brain endothelial cells after hypoxia-reoxygenation (H/R) has not yet been studied in detail.

Methods

Rat brain endothelial cells (RBE4) were exposed to severe hypoxia and reoxygenated in air in the presence or absence of sevoflurane. Changes in dextran permeability and architecture of the cellular junctional proteins ZO-1 and β-catenin were measured. To determine necrosis and apoptosis rate DNA content, LDH release and caspase activity were quantified. The role of vascular endothelial growth factor (VEGF) as an inflammatory mediator increasing vascular permeability was assessed. At the same time, it was evaluated if sevoflurane effects are mediated through VEGF. Results were analyzed by unpaired t-tests or one way-analysis of variance followed by Bonferroni’s correction.

Results

H/R led to a 172% increase in permeability (p<0.001), cell swelling and qualitatively but not quantitatively modified expression of ZO-1, β-catenin and F-actin. In the presence of sevoflurane during reoxygenation, barrier function improved by 96% (p = 0.042) in parallel to a decrease of the cell size and less re-arranged junction proteins and F-actin. Sevoflurane-induced improvement of the barrier function could not be explained on the level of necrosis or apoptosis as they remained unchanged independent of the presence or absence of the volatile anesthetic. Increased expression of VEGF after H/R was attenuated by sevoflurane by 34% (p = 0.004). Barrier protection provided by sevoflurane was similar to the application of a blocking VEGF-antibody. Furthermore, the protective effect of sevoflurane was abolished in the presence of recombinant VEGF.

Conclusions

In H/R-induced rat brain endothelial cell injury sevoflurane maintains endothelial barrier function through downregulation of VEGF, which is a key player not only in mediating injury, but also with regard to the protective effect of sevoflurane.

A critical test of Drosophila anaesthetics: Isoflurane and sevoflurane are benign alternatives to cold and CO2

Anaesthesia is often a necessary step when studying insects like the model organism Drosophila melanogaster. Most studies of Drosophila and other insects that require anaesthesia use either cold exposure or carbon dioxide exposure to induce a narcotic state. These anaesthetic methods are known to disrupt physiology and behavior with increasing exposure, and thus ample recovery time is required prior to experimentation. Here, we examine whether two halogenated ethers commonly used in vertebrate anaesthesia, isoflurane and sevoflurane, may serve as alternative means of insect anaesthesia. Using D. melanogaster, we generated dose-response curves to identify exposure times for each anaesthetic (cold, CO₂, isoflurane and sevoflurane) that allow for five-minutes of experimental manipulation of the animals after the anaesthetic was removed (i.e. 5min recovery doses). We then compared the effects of this practical dose on high temperature, low temperature, starvation, and desiccation tolerance, as well as locomotor activity and fecundity of female flies following recovery from anaesthesia. Cold, CO₂ and isoflurane each had significant or near significant effects on the traits measured, but the specific effects of each anaesthetic differed, and effects on stress tolerance generally did not persist if the flies were given 48h to recover from anaesthesia. Sevoflurane had no measureable effect on any of the traits examined. Care must be taken when choosing an anaesthetic in Drosophila research, as the impacts of specific anaesthetics on stress tolerance, behavior and reproduction can widely differ. Sevoflurane may be a practical alternative to cold and CO₂ anaesthesia in insects - particularly if flies are to be used for experiments shortly after anesthesia.

Premedication with fentanyl-midazolam improves sevoflurane anesthesia for surgical intervention in laboratory mice

Balanced anesthesia allows for a reduced dosage of each component, while inducing general anesthesia of sufficient depth with potentially fewer side effects. Here, we compare two anesthetic protocols combining sevoflurane anesthesia with pre-medication (ketamine [K] or fentanyl-midazolam [FM]) to a sevoflurane monoanesthesia (S) concerning their ability to provide reliable anesthesia suitable for moderate surgery in laboratory mice. Twenty-one female C57BL/6J mice assigned randomly to one of three protocols underwent a 50-min anesthesia and a sham embryo transfer. Heart rate and core body temperature were continuously recorded by telemetry intra-operatively and for three days pre- and three days post-surgery. Intra-operative respiratory rate was determined by counting thorax movements. Body weight, food, and water intake were measured daily for three days pre- and three days post-surgery. The heart rate in the KS group remained at baseline level throughout the 50-min of anesthesia and surgery. FMS caused a lower heart rate and S alone caused a higher heart rate compared to baseline values. Intra-operative body temperature was at baseline levels in all groups. A decreased respiratory rate was observed in all groups compared to baseline values obtained from resting mice of the same strain, sex and age-distribution. Surgical stimuli induced no significant changes in heart rate and respiratory rate in the KS or FMS group but significant respiratory alteration in the S group compared to baseline values obtained 10 s before applying the stimulus. Post-operative heart rate was above baseline values in all groups; with a significant deviation in the S group. There were no changes in body weight, food, and water intake. In summary, FMS was superior to KS and S for moderate surgery in laboratory mice resulting in less inter-individual variability in response to painful stimuli. Fentanyl and midazolam reduced the depressant effect of sevoflurane on the respiratory rate and the negative post-anesthetic effects on the heart rate. Impact statement With approximately 65 million animals used per year mice are still the most prevalent laboratory mammal species worldwide. In course of biomedical research projects approximately 40% of mice will undergo one or more short or long-term anesthesia. Sufficient anesthetic depth, cardiovascular stability, adequate analgesia, and short recovery times are essential requirements of anesthetic protocols to meet animal welfare. Anesthesia in mice and rats are only to be performed by personnel with appropriate basic training and experience. However, more and more adapted and advanced anesthetic protocols, required to answer very specific scientific questions, often exceed the skills acquired through basic training and present a major challenge to researchers. It is therefore of great importance to further develop and evaluate safe and reliable anesthetic protocols as presented in this study to provide new perspectives on this challenging problem.

Cyclophilin D Modulates the Cardiac Mitochondrial Target of Isoflurane, Sevoflurane, and Desflurane

BACKGROUND

Volatile anesthetics are known to limit myocardial ischemia-reperfusion injuries. Mitochondria were shown to be major contributors to cardioprotection. Cyclophilin D (CypD) is one of the main regulators of mitochondria-induced cell death. We compared the effect of isoflurane, sevoflurane, and desflurane in the presence or absence of CypD, to clarify its role in the mechanism of cardioprotection induced by these anesthetics.

METHODS

Oxidative phosphorylation, mitochondrial membrane potential, and H2O2 production were measured in isolated mitochondria from wild-type (WT) or CypD knockout mice in basal conditions and after hypoxia-reoxygenation in the presence or absence of volatile anesthetics.

RESULTS

All volatile anesthetics inhibited mitochondrial state 3 of complex I, decreased membrane potential, and increased adenosine diphosphate consumption duration in both WT and CypD knockout mice. However, they differently modified H2O2 production after stimulation by succinate: CypD ablation reduced H2O2 production, isoflurane decreased H2O2 level in WT but not in CypD knockout mice, sevoflurane affected both lines whereas desflurane increased H2O2 production in CypD knockout and had no effect on WT mice.

CONCLUSIONS

This study showed different effects of isoflurane, sevoflurane, and desflurane on mitochondrial functions and highlighted the implication of CypD in the regulation of adenosine diphosphate consumption and complex I-induced radical oxygen species production.

Antibacterial effect of sevoflurane and isoflurane

OBJECTIVE

Multidrug resistant bacteria are increasing worldwide and therapeutic options are limited. Some anaesthetics have shown antibacterial activity before. In this study, we have investigated the antibacterial effect of the halogenated anaesthetic agents sevoflurane and isoflurane against a range of resistant pathogens.

METHODS

Two experiments were conducted. In the first, bacterial suspensions of both ATCC and resistant strains of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were exposed to liquid sevoflurane and isoflurane during 15, 30 and 60 minutes. In the second experiment clinical resistant strains of E. coli, Klebsiella pneumoniae, Enterobacter cloacae, P. aeruginosa, Acinetobacter baumannii, S. aureus, and Enterococcus faecium were studied. Previously inoculated agar plates were irrigated with the halogenated anaesthetic agents and these were left to evaporate before the plates were incubated. In both experiments colony forming units were counted in resultant plates.

RESULTS

In the first experiment, isoflurane showed faster and higher antimicrobial effect than sevoflurane against all the strains studied. Gram-negative organisms were more susceptible. In the second experiment, E. faecium was found to be resistant to both halogenated agents; only isoflurane showed statistically significant activity against the rest of the strains studied.

CONCLUSIONS

Both halogenated agents, but particularly isoflurane, showed in vitro antibacterial activity against pathogens resistant to conventional antibiotics. Further investigation is required to determine whether or not they also exhibit this property in vivo. This might then allow these agents to be considered as rescue treatment against multidrug resistant pathogens, including a topical use in infected wounds.

Isoflurane and sevoflurane affects Wnt/β-catenin signaling pathways in hippocampal formation of neonatal rats

OBJECTIVE

General anesthesia impairs spatial learning and memory in neonatal rats. The aim of this study was to investigate whether the Wnt pathway was involved in neonatal isoflurane and sevoflurane exposure-induced neurocognitive impairment.

MATERIALS AND METHODS

Sprague-Dawley rats were randomly assigned to administration isoflurane or sevoflurane for 6 hours at postnatal 7 days. Wnt inhibitor XAV 939 was administrated 30 min before anesthesia. Morris water maze was used to test the learning and memory at 5-week and 10-week. Hematoxylin and Eosin (H&E) stain was performed to evaluation the neuronal death in the hippocampus. Quantitative Real-time PCR (q-PCR) and Western blot assays were used to measure mRNA and proteins expression levels of the Wnt3a, GSK 3β and β-catenin, respectively.

RESULTS

The results showed that isoflurane or sevoflurane could significantly increase neonatal death and cell lost in the developing brain and the Wnt inhibitor could improve the cell degeneration. It demonstrated that isoflurane or sevoflurane could impair the P7 rats learning and memory capability, while these effects were reduced over time. When rats treated Wnt inhibitor at 30 min before anesthesia, the impairment of brain could relieve. q-PCR and Western blot demonstrated that isoflurane or sevoflurane affects expression levels of Wnt3a, GSK 3β and β-catenin. These results suggested that impairment of learning and memory in P7 rats may be related to the Wnt signaling pathway.

CONCLUSIONS

The results suggested general anesthesia treatment led to increased brain cell degeneration and impaired learning and memory in P7 rats via Wnt signaling pathway.

Effects of sevoflurane and clonidine on acid base status and long-term emotional and cognitive outcomes in spontaneously breathing rat pups

Background

Numerous experiments in rodents suggest a causative link between exposure to general anaesthetics during brain growth spurt and poor long-lasting neurological outcomes. Many of these studies have been questioned with regard of their translational value, mainly because of extremely long anaesthesia exposure. Therefore, the aim of the present study was to assess the impact of a short sevoflurane anaesthesia, alone or combined with clonidine treatment, on respiratory function in spontaneously breathing rat pups and overall effects on long-lasting emotional and cognitive functions.

Methods

At postnatal day (PND) 7, male Sprague Dawley rat pups were randomized into four groups and exposed to sevoflurane for one hour, to a single dose of intraperitoneal clonidine or to a combination of both and compared to a control group. Blood gas analysis was performed at the end of sevoflurane anaesthesia and after 60 minutes from clonidine or saline injection. Emotional and cognitive outcomes were evaluated in different group of animals at infancy (PND12), adolescence (PND 30–40) and adulthood (PND 70–90).

Results

Rat pups exposed to either sevoflurane or to a combination of sevoflurane and clonidine developed severe hypercapnic acidosis, but maintained normal arterial oxygenation. Emotional and cognitive outcomes were not found altered in any of the behavioural task used either at infancy, adolescence or adulthood.

Conclusions

Sixty minutes of sevoflurane anaesthesia in newborn rats, either alone or combined with clonidine, caused severe hypercapnic acidosis in spontaneously breathing rat pups, but was devoid of long-term behavioural dysfunctions in the present setting.

The Differential Effects of Anesthetics on Bacterial Behaviors

Volatile anesthetics have been in clinical use for a long period of time and are considered to be promiscuous by presumably interacting with several ion channels in the central nervous system to produce anesthesia. Because ion channels and their existing evolutionary analogues, ion transporters, are very important in various organisms, it is possible that volatile anesthetics may affect some bacteria. In this study, we hypothesized that volatile anesthetics could affect bacterial behaviors. We evaluated the impact of anesthetics on bacterial growth, motility (swimming and gliding) and biofilm formation of four common bacterial pathogens in vitro. We found that commonly used volatile anesthetics isoflurane and sevoflurane affected bacterial motility and biofilm formation without any effect on growth of the common bacterial pathogens studied here. Using available Escherichia coli gene deletion mutants of ion transporters and in silico molecular docking, we suggested that these altered behaviors might be at least partly via the interaction of volatile anesthetics with ion transporters.

Cardiopulmonary and acid–Base effects of desflurane and sevoflurane in spontaneously breathing cats

The cardiopulmonary effects of desflurane and sevoflurane anesthesia were compared in cats breathing spontaneously. Heart (HR) and respiratory (RR) rates; systolic (SAP), diastolic (DAP) and mean arterial (MAP) pressures; partial pressure of end tidal carbon dioxide (PETCO2), arterial blood pH (pH), arterial partial pressure of oxygen (PaO2) and carbon dioxide (PaCO2); base deficit (BD), arterial oxygen saturation (SaO2) and bicarbonate ion concentration (HCO3) were measured. Anesthesia was induced with propofol (8±2.3 mg/kg IV) and maintained with desflurane (GD) or sevoflurane (GS), both at 1.3 MAC. Data were analyzed by analysis of variance (ANOVA), followed by the Tukey test ( P<0.05). Both anesthetics showed similar effects. HR and RR decreased when compared to the basal values, but remained constant during inhalant anesthesia and PETCO2 increased with time. Both anesthetics caused acidemia and hypercapnia, but BD stayed within normal limits. Therefore, despite reducing HR and SAP (GD) when compared to the basal values, desflurane and sevoflurane provide good stability of the cardiovascular parameters during a short period of inhalant anesthesia (T20–T60). However, both volatile anesthetics cause acute respiratory acidosis in cats breathing spontaneously.

Reducing Caloric Intake Prevents Ischemic Injury and Myocardial Dysfunction and Affects Anesthetic Cardioprotection in Type 2 Diabetic Rats

Background. Type 2 diabetes mellitus (T2DM) increases the risk of myocardial ischemia, followed by increased perioperative risk of cardiovascular morbidity. We investigated whether reducing caloric intake reduces ischemic injury and myocardial dysfunction and affects the protective effects of the volatile anesthetic sevoflurane in diet-induced T2DM rats. Methods. Rats received a western (WD) or control diet (CD). Caloric intake was reduced by reversing WD-fed rats to CD. Myocardial function was determined with echocardiography. After 8 weeks of diet feeding, myocardial infarction was induced and the effect of sevoflurane was studied on myocardial function and ischemia/reperfusion injury. Results. WD-feeding resulted in a mild T2DM phenotype and myocardial dysfunction. Sevoflurane further impaired systolic function in WD-fed rats. Unexpectedly, WD-feeding reduced infarct size compared to CD-feeding. Sevoflurane reduced infarct size in CD-fed rats; however it enlarged infarct size in WD-fed rats. Caloric reduction restored myocardial dysfunction and the protective effect of sevoflurane against ischemia compared to WD-fed rats, whereas the protective effects of WD-feeding persisted. Conclusion. Caloric reduction restored the T2DM phenotype and myocardial function, while the cardioprotective properties of WD-feeding or sevoflurane persisted. Our data suggest that reducing caloric intake in T2DM might be a possible intervention to reduce perioperative risk of cardiovascular morbidity.

Phosphoproteome Profiling of SH-SY5y Neuroblastoma Cells Treated with Anesthetics: Sevoflurane and Isoflurane Affect the Phosphorylation of Proteins Involved in Cytoskeletal Regulation

Inhalation anesthetics are used to decrease the spinal cord transmission of painful stimuli. However, the molecular or biochemical processes within cells that regulate anesthetic-induced responses at the cellular level are largely unknown. Here, we report the phosphoproteome profile of SH-SY5y human neuroblastoma cells treated with sevoflurane, a clinically used anesthetic. Phosphoproteins were isolated from cell lysates and analyzed using two-dimensional gel electrophoresis. The phosphorylation of putative anesthetic-responsive marker proteins was validated using western blot analysis in cells treated with both sevoflurane and isoflurane. A total of 25 phosphoproteins were identified as differentially phosphorylated proteins. These included key regulators that signal cytoskeletal remodeling steps in pathways related to vesicle trafficking, axonal growth, and cell migration. These proteins included the Rho GTPase, Ras-GAP SH3 binding protein, Rho GTPase activating protein, actin-related protein, and actin. Sevoflurane and isoflurane also resulted in the dissolution of F-actin fibers in SH-SY5y cells. Our results show that anesthetics affect the phosphorylation of proteins involved in cytoskeletal remodeling pathways.

[Emulsified Sevoflurane Selectively Blocking Spinal Cord and Brain in Rabbit Model]

OBJECTIVES

To establish the rabbits model of selectively anesthetized brain and spinal cord and to explore the skeletal muscle relaxation sites of sevoflurane.

METHODS

Sixteen adult male New Zealand white rabbits were randomly assigned to the experiment. The upper torso systemic circulation and the lower torso bypass circulation were independently established by the ligation of thoracic aorta at T12-L1 level. Sevoflurane was administered to the upper or lower torso through lungs or oxygenator to selectively anesthetized brain or spinal cord (mainly lumbar and sacro-coccygeal region). Sevoflurane concentration from end-tidal (represented the brain) and oxygenator outlet (represented the spinal cord) was measured by an anesthetic gas analyzer. The concentration and partial pressure of sevoflurane in carotid artery (represented the brain) and abdominal aorta (represented the spinal cord) were determined using a gas chromatograph with the two-stage headspace equilibration method.

RESULTS

When 1.5 mininum alveolar concentration (MAC) sevoflurane was administrated via lungs, the concentration and partial pressure of sevoflurane in the carotid artery were significantly higher than those in the abdominal aorta (P<0.05), with the end-tidal sevoflurane concentration higher than that of oxygenator outlet ( P<0.05), which indicated sevoflurane concentration and partial pressure in brain were higher than those in spinal cord. When 1.5 MAC sevoflurane was delivered via oxygenator,the indicators were conversed ( P<0.05), which indicated sevoflurane concentration and partial pressure in spinal cord were higher than those in brain.

CONCLUSIONS

Based on the unique blood supply to the spinal cord of New Zealand white rabbits, we successfully established selectively anesthetized brain and spinal cord rabbit models.

Are there any effects of Sevoflurane and Desflurane anaesthesia on blood glucose levels in acute hyperglycemic diabetic rats?

AIM

The aim of this study was to investigate blood glucose level of desflurane and sevoflurane on blood glucose in diabetic rats undergoing acute hyperglycemia.

MATERIALS AND METHODS

In this study, 30 male Wistar albino rats were included. Diabetes was induced by a single IP injection of streptozotocin. After the effects of chronic diabetes encountered, diabetic rats were randomly assigned into diabetic control (group DC), diabetic hyperglycemia group (group DH), diabetic hyperglycemia group with desflurane (group DH-D), and diabetic hyperglycemia group with sevoflurane (group DH-S) groups. The normoglycemic groups received an IP injection of the same amount of saline. Hyperglycemic diabetic rats were anaesthetized by desflurane 6 % or sevoflurane 2 % at a dose, by which minimal alveolar concentration (MAC) for rats would be one. The drugs were given for 4 hours within 100 % oxygen at a rate of 6 L.min-1. One hour after cessation of inhalation anesthesia, blood glucose levels were determined at 1st, 4th and 24th hours. 24 hours after the anaesthesia.

RESULTS

Serum glucose was detected to be significantly lower in Group C, when compared to Groups DC, DH, DH-D and DH-S (p = 0.002, p = 0.001, p = 0.002, p = 0.003, respectively). Blood glucose levels in the diabetic groups were similar at the end of 6 weeks period, after hyperglycemia and anaesthesia induction.

CONCLUSION

We found out that sevoflurane and desflurane administrations in hyperglycemic rats were both related with insignificant blood glucose level increase at early post anaesthesia period and at post anaesthesia 24th hours. We still think that patients undergoing anaesthesia protocols with acute hyperglycemia need relatively longer follow up periods (Tab. 1, Ref. 28).

Anesthetic Sevoflurane Causes Rho-Dependent Filopodial Shortening in Mouse Neurons

Early postnatal anesthesia causes long-lasting learning and memory impairment in rodents, however, evidence for a specific neurotoxic effect on early synaptogenesis has not been demonstrated. Drebrin A is an actin binding protein whose localization in dendritic protrusions serves an important role in dendritic spine morphogenesis, and is a marker for early synaptogenesis. We therefore set out to investigate whether clinically-relevant concentrations of anesthetic sevoflurane, widely- used in infants and children, alters dendritic morphology in cultured fetal day 16 mouse hippocampal neurons. After 7 days in vitro, mouse hippocampal neurons were exposed to four hours of 3% sevoflurane in 95% air/5% CO₂ or control condition (95% air/5% CO₂). Neurons were fixed in 4% paraformaldehyde and stained with Alexa Fluor555-Phalloidin, and/or rabbit anti-mouse drebrin A/E antibodies which permitted subcellular localization of filamentous (F)-actin and/or drebrin immunoreactivity, respectively. Sevoflurane caused acute significant length-shortening in filopodia and thin dendritic spines in days-in-vitro 7 neurons, an effect which was completely rescued by co-incubating neurons with ten micromolar concentrations of the selective Rho kinase inhibitor Y27632. Filopodia and thin spine recovered in length two days after sevoflurane exposure. Yet cluster-type filopodia (a precursor to synaptic filopodia) were persistently significantly decreased in number on day-in-vitro 9, in part owing to preferential localization of drebrin immunoreactivity to dendritic shafts versus filopodial stalks. These data suggest that sevoflurane induces F-actin depolymerization leading to acute, reversible length-shortening in dendritic protrusions through a mechanism involving (in part) activation of RhoA/Rho kinase signaling and impairs localization of drebrin A to filopodia required for early excitatory synapse formation.

[The Effect of Emulsified Sevofluran on Muscular Relaxation through Selective Blockage of Peripheral Nerves]

OBJECTIVES

To identify the site that emulsified sevoflurane influences in the nerve system.

METHODS

Thirty-six healthy New Zealand rabbits were randomly and equally divided into low concentration emulsified sevoflurane group [4 mL/(kg·h)], medium concentration [6 mL/(kg·h)]group, high concentration group[10 mL/(kg·h)]and intralipid control group. Emulsified sevoflurane was infused through arterial to selectively block peripheral nerves, neuro-muscular junctions and muscle fibers. The anterior tibial muscle resting tensions and muscle contraction forces were compared before and after the infusions.

RESULTS

Significant differences of blood sevoflurane pressure between femoral veins and internal jugular veins appeared in rabbits in all the groups ( P<0.05). No significant changes in the resting tension of anterior tibia muscles were found in terms of single contractions and tetanic forces with the low and medium levels of infusion of sevoflurane compared to the base values. High level of infusion of sevoflurane resulted in decreased single contraction forces and tetanic forces of anterior tibia muscles ( P<0.05).

CONCLUSIONS

A rabbit model with selective blockage of peripheral nerves was established. Peripheral nerves are not the primary site which low and medium levels of emulsified sevoflurane influence skeletal muscle relaxations.

Middle Cerebral Arterial Blood Flow Velocity and Hemodynamics in Heart Surgery

The aim of this study was to evaluate the effects of propofol, isoflurane, and sevoflurane on middle cerebral arterial blood flow velocity during open heart surgery, and the relationship between these effects and hemodynamic parameters. Fifty-two patients undergoing coronary artery bypass on cardiopulmonary bypass were divided randomly into 3 groups: the first group received 100 μg·kg−1·min−1 propofol, the other groups received one minimum alveolar concentration of sevoflurane or isoflurane for anesthesia maintenance. Middle cerebral arterial blood flow velocities were measured by transcranial Doppler, and hemodynamics were measured by the thermodilution technique. Middle cerebral arterial blood flow velocities decreased significantly after administration of isoflurane and propofol, but there was no significant difference between the groups. After weaning from cardiopulmonary bypass, cerebral blood flow increased and came close to the value after induction in all groups. The pulsatility index and resistivity index increased significantly only after the propofol infusion, but there was no significant difference between the groups.

Relationship of bispectral index values, haemodynamic changes and recovery times during sevoflurane or propofol anaesthesia in rabbits

The aim of this study was to determine and compare the degree of hypnosis achieved during propofol or sevoflurane anaesthesia in rabbits using bispectral index (BIS), and to evaluate its usefulness as a predictor of both haemodynamic changes during anaesthesia and recovery times. Twenty adult male New Zealand White rabbits, average weight 4.4 ± 0.4 kg, were used for this study. Animals were randomly allocated to one of two groups with 10 rabbits/group. An electroencephalographic recording was obtained from each conscious rabbit prior to drug administration. All animals received buprenorphine as a preanaesthetic medication (0.05 mg/kg, intravenous [i.v.]). Anaesthesia was induced with propofol (8 mg/kg, i.v.) in all animals; 10 rabbits were maintained with sevoflurane via inhalation (1 minimum alveolar concentration – end-tidal sevoflurane concentration of 3.7% – at a fresh gas flow rate of 3 L/min; group I), and 10 were maintained with i.v. propofol (0.6 mg/kg/min; group II). The rabbits were orotracheally intubated and spontaneous ventilation was maintained throughout the study (100% oxygen). After abdominal surgery through a ventral midline laparotomy, rabbits were allowed to recover from anaesthesia. Cardiovascular variables and BIS values were recorded at intervals throughout the procedure, as was the duration of recovery from anaesthesia.

In both groups, mean BIS values were significantly decreased immediately after induction, compared with baseline values obtained during consciousness. Anaesthetic depth (evaluated by clinical observation) was similar in both groups; however, group II rabbits had significantly higher ( P<0.001) BIS values from 30 s before incision until anaesthesia was discontinued. There was no significant difference in BIS recorded 1 and 5 min after incision as compared with values obtained 30 s before incision in either group.

During sevoflurane or propofol administration, correlations were found between BIS values and mean arterial blood pressure (MABP), and between BIS values and heart rate (HR).

Mean BIS values at discontinuation of administration of the anaesthetic agent were greater in group II (69.1 ± 6.0) than in group I (49.3 ± 2.2). However, recovery from anaesthesia was significantly longer in group II (38.4 ± 7.2 min) than in group I (11.5 ± 2.5 min).

In conclusion, BIS can be used to differentiate between conscious and unconscious states during anaesthesia in rabbits. BIS values derived from an electroencephalogram at the end of anaesthesia were not useful for predicting the speed of anaesthetic recovery in sevoflurane or propofol-anaesthetized rabbits undergoing abdominal surgery. Despite the correlation found between BIS and haemodynamic parameters, its usefulness as a predictor of clinically important changes in arterial blood pressure and HR in anaesthetized rabbits was limited.

Effects of magnesium sulfate and propofol on the minimum alveolar concentration preventing motor movement in sevoflurane-anesthetized dogs

OBJECTIVE To evaluate the effect of MgSO4, alone and in combination with propofol, on the minimum alveolar concentration preventing motor movement (MACNM) in sevoflurane-anesthetized dogs. ANIMALS 6 healthy purpose-bred adult male Beagles (least squares mean ± SEM body weight, 12.0 ± 1.1 kg). PROCEDURES Dogs were anesthetized 3 times at weekly intervals. The MACNM was measured 45 minutes after induction of anesthesia (baseline; MACNM-B) and was determined each time by use of a noxious electrical stimulus. Treatments were administered as a loading dose and constant rate infusion (CRI) as follows: treatment 1, MgSO4 loading dose of 45 mg/kg and CRI of 15 mg/kg/h; treatment 2, propofol loading dose of 4 mg/kg and CRI of 9 mg/kg/h; and treatment 3, MgSO4 and propofol combination (same doses used previously for each drug). A mixed-model ANOVA and Tukey-Kramer tests were used to determine effects of each treatment on the percentage decrease from MACNM-B. Data were reported as least squares mean ± SEM values. RESULTS Decrease from MACNM-B was 3.4 ± 3.1%, 48.3 ± 3.1%, and 50.3 ± 3.1%, for treatments 1, 2, and 3, respectively. The decrease for treatments 2 and 3 was significantly different from that for treatment 1; however, no significant difference existed between results for treatments 2 and 3. CONCLUSIONS AND CLINICAL RELEVANCE MgSO4 did not affect MACNM, nor did it potentiate the effects of propofol on MACNM. Administration of MgSO4 in this study appeared to provide no clinical advantage as an anesthetic adjuvant.