Quercetin increases the antidepressant-like effects of sclareol and antagonizes diazepam in thiopental sodium-induced sleeping mice: A possible GABAergic transmission intervention

Quercetin is the most common polyphenolic flavonoid present in fruits and vegetables demonstrating versatile health-promoting effects. This study aimed to examine the effects of quercetin (QR) and sclareol (SCL) on the thiopental sodium (TS)-induced sleeping and forced swimming test (FST) mouse models. SCL (1, 5, and 10 mg/kg, p.o.) or QR (50 mg/kg, p.o.) and/or diazepam (DZP) (3 mg/kg, i.p.) were employed. After 30 min of TS induction, individual or combined effects on the animals were checked. In the FST test, the animals were subjected to forced swimming after 30 min of administration of the test and/or controls for 5 min. In this case, immobility time was measured. In silico studies were conducted to evaluate the involvement of GABA receptors. SCL (5 and 10 mg/kg) significantly increased the latency and decreased sleeping time compared to the control in the TS-induced sleeping time study. DZP (3 mg/kg) showed a sedative-like effect in animals in both sleeping and FST studies. QR (50 mg/kg) exhibited a similar pattern of activity as SCL. However, its effects were more prominent than those of SCL groups. SCL (10 mg/kg) altered the DZP-3-mediated effects. SCL-10 co-treated with QR-50 significantly (p < 0.05) increased the latency and decreased sleep time and immobility time, suggesting possible synergistic antidepressant-like effects. In silico studies revealed that SCL and QR demonstrated better binding affinities with GABAA receptor, especially α2, α3, and α5 subunits. Both compounds also exhibited good ADMET and drug-like properties. In animal studies, the both compounds worked synergistically to provide antidepressant-like effects in a slightly different fashion. As a conclusion, the combined administration of SCL and QR may be used in upcoming neurological clinical trials, according to in vivo and in silico findings. However, additional investigation is necessary to verify this behavior and clarify the potential mechanism of action.

The dosage of thiopental as pharmacological cerebral protection during non-shunt carotid endarterectomy: A retrospective study

Background

Thiopental has been used as a pharmacological cerebral protection strategy during carotid endarterectomy surgeries. However, the optimal dosage required to induce burst suppression on the electroencephalogram (EEG) remains unknown. This retrospective study aimed to determine the optimal dosage of thiopental required to induce burst suppression during non-shunt carotid endarterectomy.

Methods

The Neurological Institute of Thailand Review Board approved the study. Data were collected from 2009 to 2019 for all non-shunt carotid endarterectomy patients who received thiopental for pharmacological cerebral protection and had intraoperative EEG monitoring. Demographic information, carotid stenosis severity, intraoperative EEG parameters, thiopental dosage, carotid clamp time, intraoperative events, and patient outcomes were abstracted.

Results

The study included 57 patients. Among them, 24 patients (42%) achieved EEG burst suppression pattern with a thiopental dosage of 26.3±10.1 mg/kg/hr. There were no significant differences in perioperative events between patients who achieved burst suppression and those who did not. After surgery, 33.3% of patients who achieved burst suppression were extubated and awakened. One patient in the non-burst suppression group experienced mild neurological deficits. No deaths occurred within one month postoperative.

Conclusions

The optimal dosage of thiopental required to achieve burst suppression on intraoperative EEG during non-shunt carotid endarterectomy was 26.3±10.1 mg/kg/hr.

Thiopental sodium attenuates hypoxia/reoxygenation-induced injury in osteoblasts by modulating AKT signaling

Thiopental sodium (TPTS) is a barbiturate general anesthetic, while its effects on hypoxia/reoxygenation (H/R)-induced injury are still unclear. This study aimed to investigate whether TPTS exerts protective effects against the H/R-induced osteoblast cell injury and explore the underlying mechanisms. Osteoblast cell injury model was induced by the H/R condition, which was treated with or without TPTS. Cell viability and lactate dehydrogenase (LDH) release were determined by the corresponding commercial kits. The levels of oxidative stress were determined in the experimental groups. Cell apoptosis and Caspase-3 activities were determined by propidium iodide staining and substrate-based assay, respectively. Western blotting and qRT-PCR were performed to measure the mRNA and protein levels, respectively. Treatment with TPTS was able to increase cell viability and reduce LDH release in H/R-induced osteoblasts. Additionally, TPTS regulated oxidative stress in H/R-induced osteoblasts by suppressing malondialdehyde (MDA) and reactive oxygen species (ROS) as well as boosting superoxide dismutase (SOD). TPTS was able to suppress cell apoptosis by suppressing Caspase-3 activity and cleavage. TPTS exerted protective effects against cell injury and apoptosis induced by the H/R conditions, which were associated with its regulation of Akt signaling. Moreover, TPTS induced osteoblast differentiation under the H/R condition. In summary, TPTS attenuates H/R-induced injury in osteoblasts by regulating AKT signaling.

Propofol and thiopental for intravenous induction in neonates: Study protocol for a dose-finding trial

BACKGROUND

Propofol and thiopental are commonly used induction agents in neonatal anesthesia. Even though both hypnotics have been used off-label for many years, pharmacological knowledge regarding these agents is scarce in neonates. The significant variability in neonates' body composition, organ function, and maturation makes pharmacological studies highly relevant albeit challenging. As a result, there is currently limited data about the anesthetic induction dose of thiopental and propofol in neonates. In addition, a knowledge gap exists concerning the pharmacodynamics of induction doses.

OBJECTIVE

To determine the median effective anesthetic induction dose of propofol and thiopental in neonatal patients of different gestational and postnatal ages and evaluate the pharmacodynamics of the anesthesia induction doses on the neonatal systemic and cerebral hemodynamics.

METHODS

This is a single-center, prospective, open-label, interventional, dose-finding study, including neonatal patients from birth up to 28 postnatal days undergoing general anesthesia for surgical or diagnostic procedures. The patients will be stratified according to their gestational and postnatal age and allocated to one of the two trial arms: anesthesia induction with propofol or anesthesia induction with thiopental. We will use Dixon's up-and-down method to estimate the median effective anesthesia induction dose of both agents in neonates of different gestational and postnatal ages. In addition, we will study the relationship between anesthesia induction doses and changes in systemic and cerebral hemodynamics.

DISCUSSION

Alterations in the systemic and cerebral regional hemodynamics secondary to anesthesia induction may be harmful in neonates, especially premature and critically ill newborns, due to their immature organ systems, reduced physiological reserves, and impaired cerebral autoregulation. Perfusion homeostasis is considered one of the significant and modifiable determinants of anesthesia-related neurocognitive outcomes. Therefore, dose-finding and safety pharmacological studies of the anesthetic induction agents in neonates are urgently needed and acknowledged as a high priority by the European Medicine Agency. Estimating adequate induction doses to ensure optimal depth of anesthesia while avoiding systemic and cerebral hemodynamic disturbances will help ensure safe anesthesia and potentially improve anesthesia-related outcomes in this group of patients.

TRIAL REGISTRATION

EudraCT (EudraCT Identifier: 2019-001534-34), 05.07.2022.

Effects of ketamine, thiopental and their combination on the rat liver: A biochemical evaluation

BACKGROUND

In the literature, it has been suggested that ketamine-related oxidative organ damage results from increased blood adrenaline level, and thiopental-related oxidative damage is caused by decreased adrenaline level, suggesting that ketamine-thiopental combination (KT) may be beneficial in reducing the hepatotoxic effect of ketamine.

OBJECTIVES

To biochemically investigate the effects of ketamine, thiopental and KT on the liver in rats.

MATERIAL AND METHODS

Male albino Wistar type rats received intraperitoneally (ip.) 30 mg/kg ketamine in the ketamine alone (KG) group (n = 6), 15 mg/kg thiopental in the thiopental alone (TG) group (n = 6), and 30 mg/kg ketamine + 15 mg/kg thiopental in the ketamine+thiopental (KTG) group (n = 6). The same volume of distilled water as solvent was given to the healthy (HG) animal group. This procedure was repeated once daily for 30 days. At the end of this period, the animals were killed by decapitation and their livers were removed. In liver tissue, malondialdehyde (MDA), total glutathione (tGSH), total oxidant status (TOS), total antioxidant status (TAS), tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), and interleukin-6 (IL-6) levels were measured. The IL-1β, IL-6, TNF-α, adrenalin (ADR), noradrenalin (NDR), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) levels were determined in blood samples taken from the tail veins.

RESULTS

In the group treated with ketamine and thiopental alone, MDA, TOS, IL-1β, IL-6, TNF-α, ADR, NDR, ALT, and AST levels were found to be high, and those of tGSH and TAS to be low. However, there was no significant change in the levels of these parameters in the KTG.

CONCLUSIONS

These results indicate that oxidative stress and inflammation developed in the liver tissue of the group that used ketamine and thiopental alone, suggesting that the KT form may be safer in terms of toxicity in the clinical usage.

Impact of anesthesia, sex, and circadian cycle on renal afferent nerve sensitivity

Elevated renal afferent nerve (ARNA) activity or dysfunctional reno-renal reflexes via altered ARNA sensitivity contribute to hypertension and chronic kidney disease. These nerves contain mechano- and chemosensitive fibers that respond to ischemia, changes in intrarenal pressures, and chemokines. Most studies have utilized various anesthetized preparations and exclusively male animals to characterize ARNA responses. Therefore, this study assessed the impact of anesthesia, sex, and circadian period on ARNA responses and sensitivity. Multifiber ARNA recordings were performed in male and female Sprague-Dawley rats (250-400 g) and compared across decerebrate versus Inactin, isoflurane, and urethane anesthesia groups. Intrarenal artery infusion of capsaicin (0.1-50.0 μM, 0.05 mL) produced concentration-dependent increases in ARNA; however, the ARNA sensitivity was significantly greater in decerebrate versus Inactin, isoflurane, and urethane groups. Increases in renal pelvic pressure (0-30 mmHg, 30 s) produced pressure-dependent increases in ARNA; however, ARNA sensitivity was again greater in decerebrate and Inactin groups versus isoflurane and urethane. Acute renal artery occlusion (30 s) increased ARNA, but responses did not differ across groups. Analysis of ARNA responses to increased pelvic pressure between male and female rats revealed significant sex differences only in isoflurane and urethane groups. ARNA responses to intrarenal capsaicin infusion were significantly blunted at nighttime versus daytime; however, ARNA responses to increased pelvic pressure or renal artery occlusion were not different between daytime and nighttime. These results demonstrate that ARNA sensitivity is greatest in decerebrate and Inactin-anesthetized groups but was not consistently influenced by sex.NEW & NOTEWORTHY We determined the impact of anesthesia, sex, and circadian cycle on renal afferent nerve (ARNA) sensitivity to chemical and mechanical stimuli. ARNA sensitivity to renal capsaicin infusion was greatest in decerebrate > Inactin > urethane or isoflurane groups. Elevated renal pelvic pressure significantly increased ARNA; decerebrate and Inactin groups exhibited the greatest ARNA sensitivity. Sex differences in renal afferent responses were not consistently observed. Circadian cycle altered chemosensory but not mechanosensory responses.

Ketamine/xylazine and barbiturates modulate microglial morphology and motility differently in a mouse model

Microglia, the resident immune cells of the brain, are highly ramified and motile and their morphology is strongly linked to their function. Microglia constantly monitor the brain parenchyma and are crucial for maintaining brain homeostasis and fine-tuning neuronal networks. Besides affecting neurons, anesthetics may have wide-ranging effects mediated by non-neuronal cells and in particular microglia. We thus examined the effect of two commonly used anesthetic agents, ketamine/xylazine and barbiturates, on microglial motility and morphology. A combination of two-photon in vivo imaging and electroencephalography (EEG) recordings in unanesthetized and anesthetized mice as well as automated analysis of ex vivo sections were used to assess morphology and dynamics of microglia. We found that administration of ketamine/xylazine and pentobarbital anesthesia resulted in quite distinct EEG profiles. Both anesthetics reduced microglial motility, but only ketamine/xylazine administration led to reduction of microglial complexity in vivo. The change of cellular dynamics in vivo was associated with a region-dependent reduction of several features of microglial cells ex vivo, such as the complexity index and the ramification length, whereas thiopental altered the size of the cytoplasm. Our results show that anesthetics have considerable effects on neuronal activity and microglial morphodynamics and that barbiturates may be a preferred anesthetic agent for the study of microglial morphology. These findings will undoubtedly raise compelling questions about the functional relevance of anesthetics on microglial cells in neuronal physiology and anesthesia-induced neurotoxicity.

Anesthesia may alter mRNA expression of certain wound healing-associated genes in dermal wound environment of the rats

Some anesthetics including ketamine/xylazine and thiopental have been shown to alter the expression of genes related with inflammatory cytokines and chemokines in previous studies unassociated with wound healing, arising the question of whether commonly used anesthetics in wound healing models could interfere with the transcriptional responses of the genes associated with skin wound healing. The gene expression profile in wound biopsies of rats who received widely used anesthetics doses of intraperitoneal ketamine/xylazine (50 mg/kg and 10 mg/kg) or thiopental (50 mg/kg) in comparison with control rats was analyzed by monitoring the expression of genes effective on various phases of wound healing. The expression levels of 84 genes were determined on 3rd, 7th and 14th days of post-wounding using a qPCR array system. Of the genes either up or downregulated fivefolds or more, three (Egf, Col5a1 and Cxcl3) and two (Tgfa and Il2) genes were found to be the most responsive ones to ketamine/xylazine or thiopental anesthesia respectively in a period of 14 days after correction for multiple testing. However, up to 22 and 24 genes for ketamine/xylazine and thiopental were found to be differentially expressed in the same period without correction for multiple-comparisons testing (p < 0.05). In conclusion, our data suggest that ketamine/xylazine and thiopental may alter the transcriptional responses of some genes associated with wound healing in rats. We strongly suggest to consider the possible alteration effect of these anesthetics on gene expression in animal models of dermal wound healing.

Intubation Conditions following Rocuronium: Influence of Induction Agent and Priming

A small priming dose of rocuronium can shorten the onset time of neuromuscular blockade. Induction agents with less cardiovascular depression also reduce the onset time. We hypothesized that ketamine, compared to thiopentone, would reduce onset time and improve intubating conditions following priming. Sixty patients ASA I to II, randomized by computer-generated sequence to four groups were investigated in a double-blind controlled trial. In the two groups with priming, 0.04 mg/kg of rocuronium was followed by three minutes of priming interval. Induction was followed by an intubation dose of 0.4 mg/kg of rocuronium. After 30 seconds, intubation was attempted within a further 20 seconds. In the two control groups, the same sequence was repeated except sham priming (saline) was given. For induction, S-ketamine (1 mg/kg) or thiopentone (4 mg/kg) were administered. Intubating conditions were graded as excellent, good, poor, or not possible. Neuromuscular transmission was monitored by acceleromyography of the thumb. There were no measured differences in onset time of neuromuscular block or in haemodynamics between the groups. The proportion of good to excellent intubating conditions was higher when ketamine was preceded by priming compared to ketamine without priming (87% vs 20%; P<0.05). In both priming and control groups intubating conditions were improved when using ketamine compared to thiopentone (P<0.05). The mechanism of this effect was not clear from this study.

Bispectral Index during Modified Rapid Sequence Induction Using Thiopentone or Propofol and Rocuronium

This randomized controlled trial compared Bispectral Index (BIS) values in 40 patients after a modified rapid sequence induction using thiopentone 4 mg/kg or propofol 2 mg/kg with rocuronium 0.6 mg/kg as muscle relaxant. Endotracheal intubation was performed at 60 seconds from induction of anaesthesia and BIS values were recorded for three minutes after induction. At the 120, 150 and 180 second measurements there was a significantly greater proportion of subjects with BIS values ≤ 60 (“anaesthetized”) in the propofol group compared with the thiopentone group (P values <0.02, <0.01 and <0.01 respectively).

All intubations were completed within two minutes. No explicit recall of intubation was detected clinically with either induction agent. The BIS scores we have measured suggest that thiopentone 4 mg/kg is more likely to be associated with lighter planes of anaesthesia and consequent risk of awareness than propofol 2 mg/kg, if intubation is delayed or prolonged.

Differential Anaesthetic Effects following Microinjection of Thiopentone and Propofol into the Pons of Adult Rats: A Pilot Study

Identifying the central nervous system sites of action of anaesthetics is important for understanding the link between their molecular actions and clinical effects. The aim of the present pilot study was to compare the anaesthetic effect of bilateral microinjections of propofol and thiopentone (both 200 μg/μl, in Intralipid and 0.9% saline respectively) into a recently discovered anaesthetic-sensitive region in the rat brainstem, the “mesopontine tegmental anaesthetic area” (MPTA). Microinjections (1 μl per side) were made into the MPTA of fifteen male Sprague-Dawley rats. The effect of each agent on spontaneous behaviour, postural control and nociceptive responsiveness was subjectively assessed according to established criteria. The main finding was that thiopentone induced an “anaesthesia-like” state, including complete atonia and loss of righting ability, in 20% of the subjects. Overall, thiopentone significantly reduced postural control and had a moderate antinociceptive effect compared to saline microinjections (P<0.01 and 0.05, respectively, Wilcoxon test). In contrast, propofol did not induce “anaesthesia” in any animal tested, although a similar antinociceptive effect to that of thiopentone was observed (P<0.05, Wilcoxon test). In summary, propofol and thiopentone have different effects when microinjected into the MPTA. While both agents reduced reflex withdrawal to a nociceptive stimulus, only thiopentone induced an “anaesthesia-like” state.

The effect of inactin on kidney mitochondrial function and production of reactive oxygen species

Inactin is a long lasting anesthetic agent commonly used in rat studies, but is also shown to exert physiological effects such as reducing renal blood flow, glomerular filtration rate and depressing tubular transport capacity. The effect of inactin on isolated kidney mitochondria is unknown and may be important when studying related topics in anaesthetized animals. The aim of this study was to determine whether inactin exerts effects on mitochondrial function and production of reactive oxygen species. Kidney mitochondrial function and production of reactive oxygen after acutely (5 min) or longer (1.5 hour) anesthetizing rats with inactin was evaluated using high-resolution respirometry. The results demonstrate that inactin significantly improves respiratory control ratio, inhibits complex I in the mitochondrial respiratory chain, reduce both unregulated proton leak and time dependently reduce the regulated proton leak via uncoupling protein-2 and adenine nucleotide translocase. Inactin also contributes to increased mitochondrial hydrogen peroxide production. In conclusion, inactin exerts persistent effects on mitochondrial function and these profound effects on mitochondrial function should to be considered when studying mitochondria isolated from animals anesthesized with inactin.

Dose requirements of alfentanil to eliminate autonomic responses during rapid-sequence induction with thiopental 4 mg/kg and rocuronium 0.6 mg/kg

STUDY OBJECTIVE

Opioids are integral part of anesthesia induction, but information on optimal dosing is limited. We aimed to determine doses of alfentanil needed to eliminate increases in 5 autonomic response variables (plasma concentrations of epinephrine, norepinephrine and vasopressin, arterial blood pressure [ABP], and heart rate) during rapid-sequence induction of anesthesia with thiopental 4 mg/kg and rocuronium 0.6 mg/kg.

DESIGN

Prospective, randomized, observer-blinded, interventional clinical study.

SETTING

Large academic institution.

PATIENTS

Eighty-four healthy patients, aged 18 to 55 years, received 1 of 7 assessor-blinded doses of alfentanil (0, 10, 20, 30, 40, 50, and 60 μg/kg) together with thiopental 4 mg/kg and rocuronium 0.6 mg/kg, administered in rapid succession (15 seconds). Laryngoscopy was initiated 40 seconds after rocuronium, and tracheal intubation was concluded within 15 seconds thereafter.

MEASUREMENTS

An indwelling radial artery catheter was used for hemodynamic monitoring and blood sampling. Relationships between alfentanil dose and response variables were tested with linear regression, and the influence of covariates (sex, body weight, and age) was determined. Alfentanil dose needed to prevent increases in ABP >10% above baseline with 95% probability was estimated with logistic regression.

MAIN RESULTS

Significant relationships were determined between alfentanil dose and response variables. Clinically interesting influence of covariates was not found. Alfentanil 55 μg/kg was needed to prevent increases in ABP postintubation >10% above baseline with 95% probability. One individual needed a bolus of vasopressor postintubation.

CONCLUSIONS

Optimal control of autonomic responses during rapid-sequence induction was achieved with clinically relevant doses of alfentanil in healthy patients anesthetized with thiopental 4 mg/kg and rocuronium 0.6 mg/kg.

Memory Interventions in the Criminal Justice System: Some Practical Ethical Considerations

In recent years, discussion around memory modification interventions has gained attention. However, discussion around the use of memory interventions in the criminal justice system has been mostly absent. In this paper we start by highlighting the importance memory has for human well-being and personal identity, as well as its role within the criminal forensic setting; in particular, for claiming and accepting legal responsibility, for moral learning, and for retribution. We provide examples of memory interventions that are currently available for medical purposes, but that in the future could be used in the forensic setting to modify criminal offenders' memories. In this section we contrast the cases of (1) dampening and (2) enhancing memories of criminal offenders. We then present from a pragmatic approach some pressing ethical issues associated with these types of memory interventions. The paper ends up highlighting how these pragmatic considerations can help establish ethically justified criteria regarding the possibility of interventions aimed at modifying criminal offenders' memories.

The role of mitochondrial ATP-sensitive potassium channels on cardiovascular effects of thiopental and ketamine in rats

OBJECTIVE

We aimed to investigate whether mitochondrial ATP-sensitive potassium (mitoKATP) channels play any role on cardiovascular effects of thiopental (TP) or ketamine (K) anesthesia in rats.

BACKGROUND

mitoKATP channels are the end-effectors of cardioprotection induced by some anesthetics. TP and K are the most frequently used anesthetics with their own cardiovascular effects in experimental studies. To the best of our knowledge, there is no study investigating the cardiovascular effects of TP and K associated with mitoKATP channels.

MATERIALS AND METHODS

The experimental groups: TP control, K/Xylazine (X) control, TP+5-hydroxydecanoate (5-HD; mitoKATP channel blocker) and K/X+5-HD. Mean arterial blood pressure (MABP), heart rate (HR) and standard limb lead II ECG were recorded and arrhythmia parameters were evaluated.

RESULTS

Blockage of mitoKATP channels by 5-HD increased MABP and decreased HR in the TP+5-HD and K/X+5-HD groups, respectively. 5-HD caused an increase in ventricular ectopic beat (VEB) incidence. Moreover, VEB incidence was significantly different in TP+5-HD (100%) than K/X+5-HDgroup (66.6%) and ventricular tachycardia was only seen in TP+5-HD (incidence was 88.3%).

CONCLUSION

mitoKATP channels play different roles in influencing cardiovascular effects of K/X and TP anesthesia in rats. The differences in hemodynamic parameters and arrhythmia scores of these anesthetics should be considered when they are used in an experimental study associated with mitoKATP channels (Fig. 3, Ref. 35).

Refractory intracranial hypertension in posterior reversible encephalopathy syndrome

INTRODUCTION

Posterior reversible encephalopathy syndrome (PRES) is a largely reversible disease with long-term favorable outcome. A minority of patients, however, may develop progressive cerebral edema and ischemia resulting in severe disability or death. We report a case of severe intracranial hypertension associated with PRES that was successfully treated according to intracranial pressure (ICP)- and cerebral perfusion pressure (CPP)-driven therapy.

METHODS

Case report.

RESULTS

A 42-year-old woman underwent bilateral lung transplantation for severe bronchiectasis. Her immunosuppressive regimen consisted of azathioprine, prednisone, and tacrolimus. She acutely developed an aggressive form of PRES that rapidly resulted in severe refractory intracranial hypertension despite discontinuation of potentially causative medications and adequate supportive therapy. Accordingly, second-tier therapies, including barbiturate infusion, were instituted and immunosuppression was switched to anti-thymocyte globulin followed by mycophenolate mofetil. Within 10 h of barbiturate administration, ICP dropped to 20 mmHg. Thiopental was administered for two days and then rapidly tapered because of severe urosepsis. Six months after discharge from the intensive care unit the patient returned to near-normal life, her only complaint being short-term amnesia.

CONCLUSIONS

The decision to undertake ICP monitoring in medical conditions in which no clear recommendations exist greatly relies on physicians' judgment. This case suggests that ICP monitoring may be considered in the setting of acute PRES among selected patients, when severe intracranial hypertension is suspected, provided that a multidisciplinary team of neurocritical care specialists is readily available.

Orexin A reverses propofol and thiopental induced cytoskeletal rearrangement in rat neurons

Orexin A (OA) is an endogenous peptide regulating awakefulness, known to reduce anaesthesia in animals, but on cellular level its mechanisms to reverse anaesthetics are unknown. Primary cortical cell cultures from newborn rat brains are used and live cell light microscopy is performed to measure 1) neurite retraction after propofol, thiopental, barbituric acid and ketamine exposure and 2) the effect of OA application either before or after anaesthetics. Cytoskeletal reorganization is evaluated with fluorescence microscopy, protein changes are detected with Western blots and mass spectrometry is used to identify proteins after treatment with anaesthetics and/or OA. Adult rats are anaesthesized with propofol, and the cytoskeletal morphology is studied. Orexin A reverses and inhibits neurite retraction and actin ring formation induced by propofol and thiopental. No effect on retraction or actin rings was seen for ketamine (not active on gamma-aminobutiric acid A (GABA(A)) receptors), the non-anaesthetic barbituric acid, OA or solvents used. OA increases the tyrosine phosphorylation of a 50 kDa protein, identified as vimentin. Propofol induces an immediate granular appearance of vimentin, which OAreverses to a smooth distribution. Cytoskeletal morphology changes are also induced by propofol in vivo. All OA effects are blocked with an orexin receptor1 (OX1) antagonist. We conclude that OA reverses the GABAA receptor mediated cellular effects of both propofol and thiopental in rat brain cells. The morphologic changes of actin and vimentin caused by propofol and thiopental, and the subsequent reversal by OA, deepens our understanding of the mechanisms of anaesthesia.

Comparison of propofol-dexmedetomidine, tiopental-dexmedetomidine and etomidate-dexmedetomidine combinations' effects on the tracheal intubation conditions without using muscle relaxants

BACKGROUND

In our study, we aimed to compare the endotracheal intubation conditions without muscle relaxants during induction with the combinations of dexmedotimidine-propofol, dexmedotimidine-thiopenthal and dexmedetomidine-etomidate.

METHOD

Seventy-six patients, in ASA risk group I-II, between ages 20-60 years, with Mallampati Class 1 were included in the study. All patients were premedicated with midazolam. The patients were randomly divided into three groups as Group P (n=30, dexmedetomidine-propofol), Group T (n=30, dexmedetomidine-thiopenthal), Group E (n=16, dexmedetomidine-etomidate). All patients received dexmedetomidine 1 μg.kg-1 in 10 min. Then, the patients were administered 2.5 mg.kg-1 propofol for Group P, 5 mg.kg-1 thiopental for Group T and 0.3 mg.kg-1 etomidate for Group E during induction. Hemodynamic data of the patients were recorded before induction, after dexmedetomidine administration, immediately after intubation and 3, 5 and 10 minutes after intubation.

RESULTS

There was no difference between the groups according to hemodynamic data. Sixteen patients in Group P and 10 patients in Group T had acceptable intubation conditions. Muscle relaxant was needed in 14, 20 and 16 patients in Groups P, T and E, respectively (p<0.05).

CONCLUSION

In conclusion, we determined that best intubation conditions without muscle relaxants were achieved with propofol-dexmedetomidine combination. None of the patients receiving etomidate -dexmedetomidine combination could be intubated without muscle relaxants (Tab. 6, Ref. 29).

Thiopental inhibits global protein synthesis by repression of eukaryotic elongation factor 2 and protects from hypoxic neuronal cell death

Ischemic and traumatic brain injury is associated with increased risk for death and disability. The inhibition of penumbral tissue damage has been recognized as a target for therapeutic intervention, because cellular injury evolves progressively upon ATP-depletion and loss of ion homeostasis. In patients, thiopental is used to treat refractory intracranial hypertension by reducing intracranial pressure and cerebral metabolic demands; however, therapeutic benefits of thiopental-treatment are controversially discussed. In the present study we identified fundamental neuroprotective molecular mechanisms mediated by thiopental. Here we show that thiopental inhibits global protein synthesis, which preserves the intracellular energy metabolite content in oxygen-deprived human neuronal SK-N-SH cells or primary mouse cortical neurons and thus ameliorates hypoxic cell damage. Sensitivity to hypoxic damage was restored by pharmacologic repression of eukaryotic elongation factor 2 kinase. Translational inhibition was mediated by calcium influx, activation of the AMP-activated protein kinase, and inhibitory phosphorylation of eukaryotic elongation factor 2. Our results explain the reduction of cerebral metabolic demands during thiopental treatment. Cycloheximide also protected neurons from hypoxic cell death, indicating that translational inhibitors may generally reduce secondary brain injury. In conclusion our study demonstrates that therapeutic inhibition of global protein synthesis protects neurons from hypoxic damage by preserving energy balance in oxygen-deprived cells. Molecular evidence for thiopental-mediated neuroprotection favours a positive clinical evaluation of barbiturate treatment. The chemical structure of thiopental could represent a pharmacologically relevant scaffold for the development of new organ-protective compounds to ameliorate tissue damage when oxygen availability is limited.

Pharmacology of intravenous sedative/anesthetic medications used in oral surgery

This article provides an overview of historical and current sedative agents available to the dentist anesthetist. The surgeon is given rational choices for sedation and the individualization of drug selection for each patient. Total intravenous anesthesia is becoming increasingly popular for dental sedation because of the availability of ultra-short-acting drugs and computerized infusion technology. Levels of sedation are more easily achieved and maintained, and recovery is enhanced, which gives the operator extreme, moment-to-moment control of the anesthetic experience and improves patient outcomes.

Propofol and thiopental as anesthetic agents in electroconvulsive therapy: a retrospective study in major depression

OBJECTIVE

To determine the influence of propofol and thiopental as anesthetics in electroconvulsive therapy (ECT), as regards, seizure duration, electrical charge, clinical efficacy, cardiovascular profile, and presence of adverse cognitive effects.

METHODS

A retrospective design including 127 patients who received bilateral ECT for the treatment of a major depressive episode.

RESULTS

The mean seizure duration in the propofol group was significantly shorter than in the thiopental group (21.23±6.09 versus 28.24±6.6 7s, P<.001). The mean stimulus charge was 348.22 mC in the propofol group, and 238 mC in the thiopental group (P<.001). Propofol was associated with a lower increase in blood pressure. There were no differences between groups in treatment response or presence of adverse effects.

CONCLUSIONS

The anesthetic agent used in ECT might determine differences in parameters such as seizure duration or electrical charge. However, this does not seem to be translated into differences in clinical efficacy or the pattern of adverse effects observed.

Changes in intraocular pressures during laparoscopy: a comparison of propofol total intravenous anesthesia to desflurane-thiopental anesthesia

The aim of the study was to examine intraocular pressure (IOP) changes during laparoscopic cholecystectomy performed under either desflurane-thiopental anesthesia or propofol total intravenous anesthesia (TIVA). 36 patients who will undergo elective laparoscopic cholecystectomy were enrolled in the study. The patients were randomly divided into one of two groups: desflurane (Group D, n=18) or propofol (Group P, n=18). All patients received fentanyl 2 micro/kg IV, and then breathed 100% oxygen for 3 minutes prior to induction of anesthesia. Anesthesia was induced by using thiopental 5 mg/kg IV in Group D and 2 mg/kg IV propofol in group P. Neuromuscular block was achieved with rocuronium 0.6 mg/kg IV. Anesthesia was maintained with desflurane 3-6% in group D and propofol infusion 5-10 mg/kg/h in group P. Desflurane and propofol concentrations were adjusted to maintain mean arterial pressure witihin 20% of the preinduction value. During anaesthesia, fractionated doses of fentanyl 0.5-1 micro g /kg IV and maintenance doses of muscle relaxants were used. In both groups, the the mixture 60% nitrous oxide and 40% oxygen was administered used. Arterial pressure, heart rate, ETCO2, SpO2 and IOP were recorded at the predefined time points. Creation of pneumoperitoneum resulted in a significant increase in IOP which remained elevated throughout the operation in both groups. Also, we recorded a similar IOP changes with both techniques except at five minutes after pneumoperitoneum in 15 degrees reverse Trendelenburg position during desflurane-thiopental anesthesia. In c6nclusion, desflurane-thiopental anesthesia maintains the IOP at least at similar levels compared to propofol TIVA anesthesia.

Age-dependent changes in the susceptibility to thiopental anesthesia in mice: analysis of the relationship to the functional expression of GABA transporter

The potency of anesthetics changes during development, probably due not only to pharmacokinetic factors such as differential distribution and/or metabolism, but also to pharmacodynamic factors such as changes to the GABAergic system in the brain. To explore the latter mechanism, we focused on the GABA transporter (GAT), the uptake system for GABA, which participates in the synaptic clearance of GABA. Thiopental-induced anesthesia, as assessed by the onset and duration of loss of the righting reflex, was more pronounced in 3-week-old mice than in 7-week-old mice. Both NO-711 and SKF89976A, selective GAT-1 inhibitors, significantly enhanced the anesthesia in the 7-week-old but not in the 3-week-old mice. In synaptosomes prepared from the cerebral cortex, the kinetics of GABA transport was similar between the two age groups, as assessed by [(3)H]GABA uptake assay. In addition, expression of GAT mRNA was similar between the two age groups, as assessed by quantitative RT-PCR. Thiopental reduced [(3)H]GABA uptake only at high concentrations in a similar manner at both ages. Conversely, the ability of SKF89976A to inhibit [(3)H]GABA uptake was greater in the 7-week-old mice than in the 3-week-old mice. Based on these results, GAT seems unlikely to contribute to the greater susceptibility to thiopental anesthesia in 3-week-old mice, while the increased ability of GABA uptake inhibitors to enhance thiopental-induced anesthesia in 7-week-old mice is at least partly due to higher sensitivity of GAT to the inhibitors.

Comparative study of the haemodynamic effects of propofol and thiopentone in modified electroconvulsive therapy in Nigerians

BACKGROUND

Electroconvulsive therapy provokes abrupt changes in systemic haemodynamics. We compared the effects of propofol and thiopentone on haemodynamic responses of patients scheduled for ECT between September 2008 and March 2009 in two Nigerian tertiary hospitals.

METHODS

In a prospective, randomized study, 40 patients scheduled for ECT were allocated into 2 groups of 20 each. Anaesthesia was induced with either 1mg/kg propofol (PG) or 5 mg/kg thiopentone (TG) and 0.5mg/kg suxamethonium prior to ECT. Heart rate (HR), blood pressure- systolic (SBP), mean arterial (MAP) and diastolic (DBP) were taken before ECT and at 1 and 5 minutes postictal. The means of the increases in haemodynamic parameters were compared.

RESULTS

There were significant increases in mean HR in both groups at 1 and 5 min and the increases were comparable between the 2 groups (p = 0.784). The increases in SBP were not significant in both groups and were comparable (p = 0.988). The increases in mean DBP were not significant in both groups but it was significantly greater in TG (p = 0.012). Increase in MAP was significantly greater in the TG at 1 min (p = 0.028).

CONCLUSION

Propofol at 1 mg/kg and thiopentone at 5 mg/kg used for modified ECT in this study resulted in significant increases in heart rates. However, a significant increase in mean arterial pressure with thiopentone and a significantly greater increase in diastolic blood pressure when the two agents are compared confer some superiority on propofol over thiopentone in attenuating haemodynamic responses to ECT.

Manganese-enhanced magnetic resonance imaging detects mossy fiber sprouting in the pilocarpine model of epilepsy

PURPOSE

Mossy fiber sprouting (MFS) is a frequent finding following status epilepticus (SE). The present study aimed to test the feasibility of using manganese-enhanced magnetic resonance imaging (MEMRI) to detect MFS in the chronic phase of the well-established pilocarpine (Pilo) rat model of temporal lobe epilepsy (TLE).

METHODS

To modulate MFS, cycloheximide (CHX), a protein synthesis inhibitor, was coadministered with Pilo in a subgroup of animals. In vivo MEMRI was performed 3 months after induction of SE and compared to the neo-Timm histologic labeling of zinc mossy fiber terminals in the dentate gyrus (DG).

KEY FINDINGS

Chronically epileptic rats displaying MFS as detected by neo-Timm histology had a hyperintense MEMRI signal in the DG, whereas chronically epileptic animals that did not display MFS had minimal MEMRI signal enhancement compared to nonepileptic control animals. A strong correlation (r = 0.81, p < 0.001) was found between MEMRI signal enhancement and MFS.

SIGNIFICANCE

This study shows that MEMRI is an attractive noninvasive method for detection of mossy fiber sprouting in vivo and can be used as an evaluation tool in testing therapeutic approaches to manage chronic epilepsy.

The effects of intravenous anesthetics on mouse embryonic fibroblast viability and proliferation

PURPOSE

The aim of this study is to evaluate the cytotoxic and antiproliferating effects of intravenous anesthetics on an mouse fibroblast in vitro cell culture system.

METHODS

The cells were exposed to the usual clinical plasma concentration of intravenous anesthetics, i.e., midazolam (0.15 μg/ml), propofol (2 μg/ml), remifentanil (2 μg/ml), thiopental (10 μg/ml), for 4, 8, or 24 h. Cell proliferation (n = 6 for each) under intravenous anesthetics was analyzed using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Cytotoxicity (n = 6 for each) of intravenous anesthetics was investigated using a LIVE/DEAD viability assay kit.

RESULTS

Intravenous anesthetic exposure time did not affect the proliferation rate of mouse fibroblasts. The cytotoxicity of intravenous anesthetics did not differ in accordance with exposure time.

CONCLUSION

Our results showed that intravenous anesthetics may not affect mouse fibroblast proliferation and viability.

A prospective, randomized comparison of the effects of thiopental and propofol on bispectral index during caesarean section till delivery of newborn

BACKGROUND

Since in caesarean operations skin incision to delivery time is very short, induction agent could be still effective on BIS level till the time of delivery. Therefore this study was designed to analyze the effect on maintaining adequate bispectral index levels till delivery of neonate of propofol and thiopental as an induction agent for caesarean section.

METHODS

Eighty two patients undergoing caesarean section were allocated into two groups. In the group T anesthesia induction was performed with thiopental (5 mg/kg) and in the group P with propofol (2.5 mg/kg). Anesthesia was maintained with sevoflurane. Heart rates, blood pressures and BIS values during significant events of surgery and anesthesia till delivery, durations of surgery, induction to skin incision and to delivery and Apgar scores were recorded. For statistical analysis T-test was used for comparison of means of independent samples.

RESULTS

The groups were comparable with respect to age, weight and gestational age. The patients in the group P had significantly lower levels of bispectral index values during uterus incision; 40.6 vs. 59.5 (p = 0.019) and delivery; 41 vs. 62.9 (p = 0.018).

CONCLUSION

Anesthesia induction with propofol in a dose of 2.5 mg/kg maintains lower levels of heart rate, blood pressure and BIS till delivery when compared with thiopental in a dose of 5 mg/kg. There is no financial support taken from any kind of company or person. There are no financial relationships between authors and commercial interests with a vested interest in the outcome of study.

The effects of succinylcholine or low-dose rocuronium to aid endotracheal intubation of adult sows

This randomized, prospective, blinded study compared the use of succinylcholine or rocuronium to aid endotracheal intubation of 27 adult sows [mean body weight 261 ± 28 (standard deviation) kg]. Preliminary trials allowed development of the intubation technique and skills. The sows were premedicated with azaperone, atropine, and morphine, and anesthesia was induced with thiopental [6 mg/kg body weight (BW)]. Nine sows each received succinylcholine (1.0 mg/kg BW), rocuronium (0.5 mg/kg BW), or saline (15 mL) after induction. Increments of thiopental (1 mg/kg BW) were used if swallowing impaired intubation. Intubation was performed 45 s after injection of the test drug and was timed and scored. The intubation scores were analyzed with Kruskal-Wallis analysis of variance (ANOVA). Time taken for intubation, body weight, and total dose of thiopental were analyzed with ANOVA and Bonferroni's multiple-comparisons test. No significant differences (at P < 0.05) were found between the groups with regard to intubation score, time taken for intubation, or total thiopental dose. Thus, neuromuscular blocking agents did not aid endotracheal intubation of adult sows anesthetized with thiopental.

3-Hydroxy-2'-methoxy-6-methylflavone: a potent anxiolytic with a unique selectivity profile at GABA(A) receptor subtypes

Genetic and pharmacological studies have demonstrated that α2- and α4-containing GABA(A) receptors mediate the anxiolytic effects of a number of agents. Flavonoids are a class of ligands that act at GABA(A) receptors and possess anxiolytic effects in vivo. Here we demonstrate that the synthetic flavonoid, 3-hydroxy-2'-methoxy-6-methylflavone (3-OH-2'MeO6MF) potentiates GABA-induced currents at recombinant α1/2β2, α1/2/4/6β1-3γ2L but not α3/5β1-3γ2L receptors expressed in Xenopus oocytes. The enhancement was evident at micromolar concentrations (EC(50) values between 38 and 106 μM) and occurred in a flumazenil-insensitive manner. 3-OH-2'MeO6MF displayed preference for β2/3- over β1-containing receptors with the highest efficacy observed at α2β2/3γ2L, displaying a 4-11-fold increase in efficacy over α2β1γ2L and α1/4/6-containing subtypes. In contrast, 3-OH-2'MeO6MF acted as a potent bicuculline-sensitive activator, devoid of potentiation effects at extrasynaptic α4β2/3δ receptors expressed in oocytes. The affinity of 3-OH-2'MeO6MF for α4β2/3δ receptors (EC(50) values between 1.4 and 2.5 μM) was 10-fold higher than at α4β1δ GABA(A) receptors. 3-OH-2'MeO6MF acted as a full agonist at α4β2/3δ (105% of the maximal GABA response) but as a partial agonist at α4β1δ (61% of the maximum GABA response) receptors. In mice, 3-OH-2'MeO6MF (1-100 mg/kg i.p.) induced anxiolytic-like effects in two unconditioned models of anxiety: the elevated plus maze and light/dark paradigms. No sedative or myorelaxant effects were detected using holeboard, actimeter and horizontal wire tests and only weak barbiturate potentiating effects on the loss of righting reflex test. Taken together, these data suggest that 3-OH-2'MeO6MF is an anxiolytic without sedative and myorelaxant effects acting through positive allosteric modulation of the α2β2/3γ2L and direct activation of α4β2/3δ GABA(A) receptor subtypes.

Anesthetic binding in a pentameric ligand-gated ion channel: GLIC

Cys-loop receptors are molecular targets of general anesthetics, but the knowledge of anesthetic binding to these proteins remains limited. Here we investigate anesthetic binding to the bacterial Gloeobacter violaceus pentameric ligand-gated ion channel (GLIC), a structural homolog of cys-loop receptors, using an experimental and computational hybrid approach. Tryptophan fluorescence quenching experiments showed halothane and thiopental binding at three tryptophan-associated sites in the extracellular (EC) domain, transmembrane (TM) domain, and EC-TM interface of GLIC. An additional binding site at the EC-TM interface was predicted by docking analysis and validated by quenching experiments on the N200W GLIC mutant. The binding affinities (K(D)) of 2.3 ± 0.1 mM and 0.10 ± 0.01 mM were derived from the fluorescence quenching data of halothane and thiopental, respectively. Docking these anesthetics to the original GLIC crystal structure and the structures relaxed by molecular dynamics simulations revealed intrasubunit sites for most halothane binding and intersubunit sites for thiopental binding. Tryptophans were within reach of both intra- and intersubunit binding sites. Multiple molecular dynamics simulations on GLIC in the presence of halothane at different sites suggested that anesthetic binding at the EC-TM interface disrupted the critical interactions for channel gating, altered motion of the TM23 linker, and destabilized the open-channel conformation that can lead to inhibition of GLIC channel current. The study has not only provided insights into anesthetic binding in GLIC, but also demonstrated a successful fusion of experiments and computations for understanding anesthetic actions in complex proteins.

Cardioprotection via modulation of calcium homeostasis by thiopental in hypoxia-reoxygenated neonatal rat cardiomyocytes

PURPOSE

Ca(2+) homeostasis plays an important role in myocardial cell injury induced by hypoxia-reoxygenation, and prevention of intracellular Ca(2+) overload is key to cardioprotection. Even though thiopental is a frequently used anesthetic agent, little is known about its cardioprotective effects, particularly in association with Ca(2+) homeostasis. We investigated whether thiopental protects cardiomyocytes against hypoxia-reoxygenation injury by regulating Ca(2+) homeostasis.

MATERIALS AND METHODS

Neonatal rat cardiomyocytes were isolated. Cardiomyocytes were exposed to different concentrations of thiopental and immediately replaced in the hypoxic chamber to maintain hypoxia. After 1 hour of exposure, a culture dish was transferred to the CO(2) incubator and cells were incubated at 37 for 5 hours. At the end of the experiments, the authors assessed cell protection using immunoblot analysis and caspase activity. The mRNA of genes involved in Ca(2+) homeostasis, mitochondrial membrane potential, and cellular Ca(2+) levels were examined.

RESULTS

In thiopental-treated cardiomyocytes, there was a decrease in expression of the proapoptotic protein Bax, caspase-3 activation, and intracellular Ca(2+) content. In addition, both enhancement of anti-apoptotic protein Bcl-2 and activation of Erk concerned with survival were shown. Furthermore, thiopental attenuated alterations of genes involving Ca(2+) regulation and significantly modulated abnormal changes of NCX and SERCA2a genes in hypoxia-reoxygenated neonatal cardiomyocytes. Thiopental suppressed disruption of mitochondrial membrane potential (DeltaPsi(m)) induced by hypoxia-reoxygenation.

CONCLUSION

Thiopental is likely to modulate expression of genes that regulate Ca(2+) homeostasis, which reduces apoptotic cell death and results in cardioprotection.

Gastric emptying of enterally administered liquid meal in conscious rats and during sustained anaesthesia

BACKGROUND

Gastric motility studies are frequently conducted with anaesthetized animal models. Some studies on the same animal species have reported differences in vagal control of the stomach that could not be explained solely by slightly different experimental conditions. A possible limitation in the comparison between similar studies relates to the use of different anaesthetic agents. Furthermore, anaesthetic effects may also limit generalizations between mechanistic studies of gastric function and the gastric function of conscious animals. In the present study, we used the [(13)C]-breath test following a liquid mixed-nutrient test meal (Ensure), 1 ml) with the aim to investigate the rate of gastric emptying in animals that were either conscious or anaesthetized with either Inactin or urethane.

METHODS

One week after determining the maximum (13)CO(2) concentration, time to peak [(13)C] recovery and gastric half emptying time in control, conscious rats, we repeated the experiment in the same rats anaesthetized with Inactin or urethane.

KEY RESULTS

Our data show that Inactin anaesthesia prolonged the time to peak [(13)C] recovery but did not significantly reduce the maximum (13)CO(2) concentration nor delay gastric half emptying time. Conversely, urethane anaesthesia resulted in a significant slowing of all parameters of gastric emptying as measured by the maximum (13)CO(2) concentration, time to peak [(13)C] recovery and half emptying time.

CONCLUSIONS & INFERENCES

Our data indicate that Inactin(R) anaesthesia does not significantly affect gastric emptying while urethane anaesthesia profoundly impairs gastric emptying. We suggest that Inactin(R), not urethane, is the more suitable anaesthetic for gastrointestinal research.

[Effects of anesthetic agents on seizure duration and hemodynamics in electroconvulsive therapy]

BACKGROUND

Thiopental and suxamethonium have been recommended as anesthetic agents for electroconvulsive therapy (ECT). We hypothesize that propofol and vecuronium can also be used and superior to thiopental and suxamethonium in seizure duration and hemodynamics.

METHODS

We made couples of anesthetic and muscle relaxant with these anesthetic agents and obtained four different combinations. We evaluated 10 patients with cross-over design, undergoing first four sequential ECTs using these four combinations in random turn. Total 40 ECTs were divided to four groups and compared with each other in seizure duration, blood pressure, and pulse rate. Group TS: thiopental (2 mg x kg(-1)) and suxamethonium (1.2 mg x kg(-1)), group PS: propofol (0.75 mg x kg(-1) and suxamethonium (1.2 mg x kg(-1)), group TV thiopental (2 mg x kg(-1)) and vecuronium (0.07 mg x kg(-1)), group PV: propofol (0.75 mg x kg-1) and vecuronium (0.07 mg x kg(-1)). Seizure duration was measured by EEG engineer to whom anesthetic agents were unknown. We measured blood pressure and heart rate before anesthetic induction, pre-ictal, post-ictal, and every minute for ten minutes thereafter. Wilcoxon signed-rank test was used as statistic measures.

RESULTS

In between-group comparison of dynamics, there was no significant difference in these four groups. In seizure duration there was no significant difference between thiopental and propofol. Vecuronium (group TV: 27.0 +/- 24.6s, group PV: 17.5 +/-15.1s) shortened the seizure duration in comparison with suxamethonium (group TS: 43.0 +/-25.9s, group PS: 39.2 +/- 28.9s).

CONCLUSIONS

Rocuronium, which will be used for ECT in future, is needed to be studied in suxamethonium-controlled design.

Does anesthetic induction for Cesarean section with a combination of ketamine and thiopentone confer any benefits over thiopentone or ketamine alone? A prospective randomized study

BACKGROUND

The aim of this study was to evaluate the benefit of a combination of thiopentone and ketamine over either of these drugs alone as an induction agent for Cesarean section.

METHODS

Randomized prospective study of 3 groups of 20 patients (Group I: thiopentone alone; Group II: ketamine alone; Group III thiopentone and ketamine combination).

RESULTS

Systolic blood pressure (BP) (as measured at baseline, after induction, at intubation, and at 5 min, 10 min, 15 min, 20 min, 25 min, 30 min): baseline BP did not differ significantly across groups. However, postinduction values were significantly higher for Group II (ketamine alone) (P>0.001), but these values normalized by 30 min postinduction. Diastolic BP (as measured at baseline, after induction, at intubation, and at 5 min, 10 min, 15 min, 20 min, 25 min, 30 min): baseline BP did not differ significantly across groups. After induction, diastolic BP increased significantly in all groups. In Group I and Group III, these values returned to baseline after 10 min, and in Group II at the 30 min postinduction stage. Heart rate (measured at the same time as BP): at rest, presented no significant difference in heart rate across groups. At induction, all groups showed a significant rise in heart rate. At intubation, Group I showed an increase in heart rate, Group II a decrease in heart rate, and Group III no change. These intergroup variations were statistically significant. Apgar scores and umbilical venous gas measurements: although there were intergroup variations, these were not statistically significant. Postoperative pain assessment (subjective) VAS scores: the VAS pain scores 3 h after surgery were significantly higher in Group I, both at rest and coughing, at 24 h after surgery the difference persisted for scores at rest, but equalized during coughing. Postoperative pain assessment (objective) time to first analgesic demand: the duration of time to demand for first analgesic was significantly longer in Group II (ketamine only). Postoperative pain assessment (objective) total consumption of analgesic: patients of Group I consumed a significantly higher amount of analgesics than the other groups. Intraoperative event recall, awareness: no patient reported any adverse events of this nature.

CONCLUSIONS

We conclude that though there were no adverse events and a significantly lower analgesic requirement, the use of ketamine alone as an induction agent in Cesarean section should be avoided, as it causes significant maternal hemodynamic changes. The addition of a reduced dose of ketamine to thiopentone in the induction cocktail confers the benefit of reducing analgesic requirement without side effects. The treatment is safe and effective for the mother and child.

Thiamylal and thiopental attenuate beta-adrenergic signaling pathway by suppressing adenylyl cyclase in rat ventricular myocytes

The effects of intravenous anesthetics on myocytes have not been fully elucidated. To investigate the effects of various intravenous anesthetics such as fentanyl, morphine, ketamine, diazepam, midazolam, thiamylal, and thiopental on the beta-adrenergic signaling pathway, we measured isoproterenol-stimulated cyclic adenosine monophosphate (cAMP) production in freshly isolated rat ventricular myocytes. Fentanyl, morphine, ketamine, diazepam, and midazolam did not significantly affect isoproterenol-stimulated cAMP production. However, thiamylal and thiopental dose-dependently decreased cAMP production stimulated by isoproterenol or by forskolin, a direct adenylyl cyclase stimulator. In addition, we examined the role of protein kinase C (PKC) as a potential mediator of the thiamylal- or thiopental-induced effects on cAMP production using bisindolylmaleimide I, a non-specific PKC inhibitor. Bisindolylmaleimide I did not alter the inhibitory effects of thiamylal or thiopental. Thiamylal and thiopental significantly decreased isoproterenol-stimulated cAMP production by suppressing the adenylyl cyclase. We conclude that barbiturates such as thiamylal and thiopental decrease isoproterenol-stimulated cAMP production by suppressing the adenylyl cyclase through PKC-independent mechanisms.

Brevenal inhibits pacific ciguatoxin-1B-induced neurosecretion from bovine chromaffin cells

Ciguatoxins and brevetoxins are neurotoxic cyclic polyether compounds produced by dinoflagellates, which are responsible for ciguatera and neurotoxic shellfish poisoning (NSP) respectively. Recently, brevenal, a natural compound was found to specifically inhibit brevetoxin action and to have a beneficial effect in NSP. Considering that brevetoxin and ciguatoxin specifically activate voltage-sensitive Na⁺ channels through the same binding site, brevenal has therefore a good potential for the treatment of ciguatera. Pacific ciguatoxin-1B (P-CTX-1B) activates voltage-sensitive Na⁺ channels and promotes an increase in neurotransmitter release believed to underpin the symptoms associated with ciguatera. However, the mechanism through which slow Na⁺ influx promotes neurosecretion is not fully understood. In the present study, we used chromaffin cells as a model to reconstitute the sequence of events culminating in ciguatoxin-evoked neurosecretion. We show that P-CTX-1B induces a tetrodotoxin-sensitive rise in intracellular Na⁺, closely followed by an increase in cytosolic Ca²⁺ responsible for promoting SNARE-dependent catecholamine secretion. Our results reveal that brevenal and β-naphtoyl-brevetoxin prevent P-CTX-1B secretagogue activity without affecting nicotine or barium-induced catecholamine secretion. Brevenal is therefore a potent inhibitor of ciguatoxin-induced neurotoxic effect and a potential treatment for ciguatera.

S100B levels in the cerebrospinal fluid of rats are sex and anaesthetic dependent

1. S100B is a calcium-binding protein that acts as a neurotrophic cytokine and is expressed in the central nervous system, predominantly by astrocytes. At nanomolar concentrations, S100B stimulates neurite outgrowth and glial glutamate uptake, as well as protecting neurons against glutamate excitoxicity. 2. Peripheral S100B concentrations, particularly in the serum and cerebrospinal fluid (CSF), have been used as a parameter of glial activation or death in several physiological and pathological conditions. 3. In the present study, we investigated the effect of anaesthetics (thiopental, ketamine and halothane) on CSF concentrations of S100B, as well as a possible sex dependence, because several studies have suggested astrocytes as putative targets for oestrogen. 4. Higher levels of CSF S100B were found when rats were anaesthetized with thiopental; these levels, independently of anaesthetic, were sex dependent. Conversely, no effect of anaesthetic or sex was observed on serum concentrations of S100B. 5. The increase in CSF concentrations of S100B induced by thiopental was confirmed in non-anaesthetized neonatal rats and cortical astrocyte cultures. 6. Assuming CSF S100B as a marker of development, glial activation or even brain damage, investigations regarding the sex dependence of its concentration may be useful in gaining an understanding of sex variations in the behaviour and the pathological course of, as well as susceptibility to, many brain disorders. The findings of the present study reinforce the sex effect on synaptic plasticity and suggest a sex dependence of neural communication mediated by extracellular S100B without restricting the influence of astrocytes on the developmental phase.

Quantification of burst suppression and bispectral index with 2 different bolus doses of thiopentone sodium

Metabolic suppression caused by barbiturates is a major mechanism responsible for their cerebral protective potential. Maximal cerebral metabolic suppression is believed to coincide with electroencephalographic burst suppression. However, many neurosurgical procedures associated with cerebral ischemic threat are still performed in the absence of electroencephalogram monitoring, especially in developing nations. The present study was designed to assess the degree of burst suppression with 2 different doses of thiopentone sodium administered on the background of isoflurane anesthesia intraoperatively. Forty-one patients without any intracranial pathology undergoing elective spinal surgery under a general anesthetic consisting of N2O (60%) in O2 (40%) and isoflurane to maintain a bispectral index (BIS) value of 45 were randomized to receive a thiopentone bolus of either 3 or 5 mg/kg. BIS, burst suppression ratio (BSR), systolic blood pressure, and heart rate were recorded before the bolus and every 15 seconds for first 2 minutes and every 30 seconds for another 8 minutes. During the 10-minute study period after the administration of thiopentone bolus, BIS values were significantly lower in the group that received thiopentone 5 mg/kg compared with the group that received thiopentone 3 mg/kg (P<0.02). BSR>25% was seen in 7 out of 21 patients in the 3 mg/kg group and 10 out of 20 patients in the 5 mg/kg group. There was a statistically insignificant prolongation of the duration of burst suppression with thiopentone 5 mg/kg [243 s (range 75 to 435 s)] compared with thiopentone 3 mg/kg [171 s (30 to 465 s)]. The number of patients who had a BSR >50% was higher among patients who received thiopentone 5 mg/kg as compared with those who received a dose of 3 mg/kg [9/20 vs. 3/21(P<0.02)]. We conclude that thiopentone in a bolus dose of 3 to 5 mg/kg produces only a short duration of incomplete burst suppression. Also, in this dose range, burst suppression does not occur consistently in all patients. The present data suggest that bolus doses of thiopentone in the range of 3 to 5 mg/kg may have very limited value in providing significant metabolic suppression required for intraoperative cerebral protection during temporary ischemic episodes.

A comparison of propofol and thiopentone use in electroconvulsive therapy: cognitive and efficacy effects

OBJECTIVE

The purpose of this study was to compare thiopentone and propofol administration for electroconvulsive therapy (ECT) in terms of associated efficacy and cognitive side effects in the immediate and medium term.

METHOD

Participants comprised 30 depressed patients who were administered either propofol or thiopentone as an anesthetic agent for ECT. Clinical rating scales and a battery of neuropsychological tests were administered at baseline, after 6 treatments, 1 to 3 days after treatment end point, and at 1-month follow-up.

RESULTS

Thiopentone administration was associated with advantages in efficacy and cognitive side effects compared with propofol administration.

CONCLUSIONS

This study reports some serendipitous findings regarding the comparative effects of the anesthetic agents, propofol and thiopentone. Although limited by small sample size, results suggest that thiopentone has advantages for use as an anesthetic agent with ECT compared with propofol. It also highlights the need for further investigation of the impact of anesthetic agents on the cognitive side effects and efficacy of ECT.

Unilateral nondominant electrode placement as a risk factor for recall of awareness under anesthesia during electroconvulsive therapy

BACKGROUND

Awareness under anesthesia can be a frightening experience for patients receiving electroconvulsive therapy (ECT).

CASE REPORT

We present a 19-year-old, 62-kg, bipolar woman who was prescribed right unilateral ECT for a treatment-refractory major depressive episode. Her premedication comprised thiopentone sodium (200 mg) and succinylcholine (30 mg). She received 3 treatments uneventfully. A day after the fourth treatment, she described her awareness of paralysis during the last procedure and refused further treatment despite the marked improvement that had resulted with ECT.

DISCUSSION

Electroconvulsive therapy is more usually administered with bilateral than with unilateral electrode placement. During ECT, awareness under anesthesia and recall of paralysis (resulting from inadequate doses of anesthesia and/or premature administration of the muscle relaxant) may be more common than is generally realized but may not be reported by patients because bilateral ECT tends to obliterate the memory of the ECT procedure. If this is true, unilateral nondominant ECT, which is relatively memory sparing, may increase the chance of recollection of paralysis when narcosis under anesthesia is incomplete. Careful clinical assessment and monitoring of the depth of anesthesia using the bispectral index can minimize this risk of awareness under anesthesia.

Sedative Effect of Centranthus longiflorus ssp. longiflorus in Rats and the Influence of Adrenalectomy on its Effect

Sedative effect of the aqueous extract of Centranthus longiflorus ssp. longiflorus (Cle-1) on intact and adrenalectomized rats was investigated using a thiopental sleeping test to clarify the relationship of this effect on adrenal gland hormones, particularly glucocorticoids. Adrenal gland hormones were found to play an important role in inhibiting the sedative effect of the investigated drugs. It is clear, however, that these hormones are not glucocorticoids. Glucocorticoids were not responsible for shortening the sleep period.

At clinically relevant concentrations the anaesthetic/amnesic thiopental but not the anticonvulsant phenobarbital interferes with hippocampal sharp wave-ripple complexes

Background

Many sedative agents, including anesthetics, produce explicit memory impairment by largely unknown mechanisms. Sharp-wave ripple (SPW-R) complexes are network activity thought to represent the neuronal substrate for information transfer from the hippocampal to neocortical circuits, contributing to the explicit memory consolidation. In this study we examined and compared the actions of two barbiturates with distinct amnesic actions, the general anesthetic thiopental and the anticonvulsant phenobarbital, on in vitro SPW-R activity.

Results

Using an in vitro model of SPW-R activity we found that thiopental (50–200 μM) significantly and concentration-dependently reduced the incidence of SPW-R events (it increased the inter-event period by 70–430 %). At the concentration of 25 μM, which clinically produces mild sedation and explicit memory impairment, thiopental significantly reduced the quantity of ripple oscillation (it reduced the number of ripples and the duration of ripple episodes by 20 ± 5%, n = 12, P < 0.01), and suppressed the rhythmicity of SPWs by 43 ± 15% (n = 6, P < 0.05). The drug disrupted the synchrony of SPWs within the CA1 region at 50 μM (by 19 ± 12%; n = 5, P < 0.05). Similar effects of thiopental were observed at higher concentrations. Thiopental did not affect the frequency of ripple oscillation at any of the concentrations tested (10–200 μM). Furthermore, the drug significantly prolonged single SPWs at concentrations ≥50 μM (it increased the half-width and the duration of SPWs by 35–90 %). Thiopental did not affect evoked excitatory synaptic potentials and its results on SPW-R complexes were also observed under blockade of NMDA receptors. Phenobarbital significantly accelerated SPWs at 50 and 100 μM whereas it reduced their rate at 200 and 400 μM. Furthermore, it significantly prolonged SPWs, reduced their synchrony and reduced the quantity of ripples only at the clinically very high concentration of 400 μM, reported to affect memory.

Conclusion

We hypothesize that thiopental, by interfering with SPW-R activity, through enhancement of the GABA_A receptor-mediated transmission, affects memory processes which involve hippocampal circuit activation. The quantity but not the frequency of ripple oscillation was affected by the drug.