Suppression of mitochondrial oxygen metabolism mediated by the transcription factor HIF-1 alleviates propofol-induced cell toxicity.

A line of studies strongly suggest that the intravenous anesthetic, propofol, suppresses mitochondrial oxygen metabolism. It is also indicated that propofol induces the cell death in a reactive oxygen species (ROS)-dependent manner. Because hypoxia-inducible factor 1 (HIF-1) is a transcription factor which is involved in cellular metabolic reprogramming by modulating gene expressions of enzymes including glycolysis pathway and oxygen utilization of mitochondria, we examined the functional role of HIF-1 activity in propofol-induced cell death. The role of HIF-1 activity on oxygen and energy metabolisms and propofol-induced cell death and caspase activity was examined in renal cell-derived RCC4 cells: RCC4-EV cells which lack von Hippel-Lindau protein (VHL) protein expression and RCC4-VHL cells, which express exogenous VHL, and in neuronal SH-SY5Y cells. It was demonstrated that HIF-1 is involved in suppressing oxygen consumption and facilitating glycolysis in cells and that the resistance to propofol-induced cell death was established in a HIF-1 activation-dependent manner. It was also demonstrated that HIF-1 activation by treatment with HIFα-hydroxylase inhibitors such as n-propyl gallate and dimethyloxaloylglycine, alleviated the toxic effects of propofol. Thus, the resistance to propofol toxicity was conferred by HIF-1 activation by not only genetic deletion of VHL but also exposure to HIFα-hydroxylase inhibitors.

Propofol induces a metabolic switch to glycolysis and cell death in a mitochondrial electron transport chain-dependent manner.

The intravenous anesthetic propofol (2,6-diisopropylphenol) has been used for the induction and maintenance of anesthesia and sedation in critical patient care. However, the rare but severe complication propofol infusion syndrome (PRIS) can occur, especially in patients receiving high doses of propofol for prolonged periods. In vivo and in vitro evidence suggests that the propofol toxicity is related to the impaired mitochondrial function. However, underlying molecular mechanisms remain unknown. Therefore, we investigated effects of propofol on cell metabolism and death using a series of established cell lines of various origins, including neurons, myocytes, and trans-mitochondrial cybrids, with defined mitochondrial DNA deficits. We demonstrated that supraclinical concentrations of propofol in not less than 50 µM disturbed the mitochondrial function and induced a metabolic switch, from oxidative phosphorylation to glycolysis, by targeting mitochondrial complexes I, II and III. This disturbance in mitochondrial electron transport caused the generation of reactive oxygen species, resulting in apoptosis. We also found that a predisposition to mitochondrial dysfunction, caused by a genetic mutation or pharmacological suppression of the electron transport chain by biguanides such as metformin and phenformin, promoted propofol-induced caspase activation and cell death induced by clinical relevant concentrations of propofol in not more than 25 µM. With further experiments with appropriate in vivo model, it is possible that the processes to constitute the molecular basis of PRIS are identified.

HIF-1-mediated suppression of mitochondria electron transport chain function confers resistance to lidocaine-induced cell death.

The local anesthetic lidocaine induces cell death by altering reactive oxygen species (ROS) generation and mitochondrial electron transport chain function. Because hypoxia-inducible factor 1 (HIF-1) is involved in determining oxygen metabolism and mitochondria function, we investigated the involvement of HIF-1 activity in lidocaine-induced cell death. We investigated the role of HIF activation on lidocaine-induced caspase activation and cell death in renal cell-derived RCC4 cells lacking functional von Hippel-Lindau (VHL) protein. We demonstrate that HIF-1 suppressed oxygen consumption and facilitated glycolysis in a pyruvate dehydrogenase kinase-1-dependent manner and that activation of HIF-1 conferred resistance to lidocaine-induced cell death. We also demonstrated that exogenous HIF-1 activation, through HIFα-hydroxylase inhibition or exposure to hypoxic conditions, alleviates lidocaine toxicity by suppressing mitochondria function and generating ROS, not only in RCC4 cells, but also in the neuronal SH-SY5Y cells. In conclusion, we demonstrate that HIF-1 activation due to VHL deletion, treatment with small molecule HIFα-hydroxylase inhibitors, and exposure to hypoxic conditions suppresses mitochondrial respiratory chain function and confers resistance to lidocaine toxicity.

Mitigation of inflammation using the intravenous anesthetic dexmedetomidine in the mouse air pouch model.

Dexmedetomidine, an α2-adrenergic/imidazoline receptor agonist, is a widely used intravenous anesthetic. Its primary current usage is for sedation of patients in the intensive care unit. The mouse air pouch model is versatile in studying the anti-inflammatory effect of a drug on a local inflammation, which is induced by a variety of substances. In the present study, using the carrageenan-induced air pouch inflammation model, we tested whether dexmedetomidine mitigates inflammation occurring locally in the mouse air pouch. We found that dexmedetomidine dose-dependently inhibited the production of tumor necrosis factor (TNF)-α and interleukin (IL)-6 in the pouch and decreased the number of white blood cells (WBC) recruited into the pouch. Dexmedetomidine also dose-dependently inhibited the production of neutrophil chemokines, cxcl1 and cxcl2. Furthermore, the dexmedetomidine-induced decreased recruitment of WBC into the pouch was successfully reversed with intra-pouch administration of cxcl1/cxcl2, but not TNF-α or IL-6. Lastly, the inhibition of the production of the cytokines and chemokines with dexmedetomidine was reversed by the treatment of yohimbine, suggesting that dexmedetomidine's anti-inflammatory effect is primarily via the stimulation of the α2-adrenergic receptor. We conclude that dexmedetomidine has an anti-inflammatory property in the carrageenan-induced mouse air pouch inflammation model, and that the dexmedetomidine-induced inhibition of production of the neutrophil chemokines, cxcl1 and cxcl2, may be related, at least in part, to the inhibition of WBC intra-pouch recruitment.

The antioxidant N-acetyl cysteine suppresses lidocaine-induced intracellular reactive oxygen species production and cell death in neuronal SH-SY5Y cells.

BACKGROUND: The local anesthetic lidocaine can affect intra- and extra-cellular signaling pathways in both neuronal and non-neuronal cells, resulting in long-term modulation of biological functions, including cell growth and death. Indeed, lidocaine was shown to induce necrosis and apoptosis in vitro. While several studies have suggested that lidocaine-induced apoptosis is mitochondrial pathway-dependent, it remains unclear whether reactive oxygen species (ROS) are involved in this process and whether the observed cell death can be prevented by antioxidant treatment. METHODS: The effects of lidocaine and antioxidants on cell viability and death were evaluated using SH-SY5Y cells, HeLa cells, and HeLa cell derivatives. Cell viability was examined via MTS/PES ([3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt]/phenazine ethosulfate) assay. Meanwhile, cell apoptosis and necrosis were evaluated using a cell death detection assay with Annexin V-FITC and PI staining, as well as by assaying for caspase-3/7 and caspase-9 activity, and by measuring the release of lactate dehydrogenase, respectively. Mitochondrial transmembrane potential (ΔΨm) was assessed using the fluorescent probe tetramethylrhodamine ethyl ester. RESULTS: Lidocaine treatment resulted in suppression of the mitochondrial electron transport chain and subsequent attenuation of mitochondrial membrane potential, as well as enhanced ROS production, activation of caspase-3/7 and caspase-9, and induction of apoptosis and necrosis in SH-SY5Y cells in a dose- and time-dependent manner. Likewise, the anesthetics mepivacaine and bupivacaine also induced apoptosis in SH-SY5Y cells. Notably, the antioxidants N-acetyl cysteine (NAC) and Trolox successfully scavenged the mitochondria-derived ROS and suppressed local lidocaine-induced cell death. CONCLUSIONS: Our findings demonstrate that the local anesthetics lidocaine, mepivacaine, and bupivacaine inhibited the activity of mitochondria and induced apoptosis and necrosis in a dose-dependent manner. Furthermore, they demonstrate that treatment with the antioxidants NAC, Trolox, and GGA resulted in preservation of mitochondrial voltage and inhibition of apoptosis via suppression of caspase activation.

Rapid development of a spinal epidural hematoma following thoracic epidural catheter removal in an esophageal carcinoma surgical patient: a case report.

BACKGROUND: The occurrence of spinal epidural hematomas associated with the use of epidural catheters is relatively rare. Furthermore, it is unusual for hematoma-associated neurological symptoms to occur within 15 min of removing a catheter. Here, we report our experience with an esophageal carcinoma surgical patient who developed an epidural hematoma almost immediately after catheter removal, resulting in paralysis of his lower extremities. The patient achieved full neurological recovery following prompt diagnosis and surgical intervention. CASE PRESENTATION: A 68-year-old man was admitted with esophageal carcinoma and underwent video-assisted thoracoscopic esophagectomy followed by posterior mediastinal gastric tube reconstruction. During surgery, the patient was administered both general and epidural anesthesia. The epidural catheter was inserted approximately 5 cm into the epidural space at the Th6-7 level. The patient was extubated the following day in the general intensive care unit. Two days after surgery, the d-dimer level was high at 36.9 µg/mL (reference range 0-0.9 µg/mL), and we decided to administer an anticoagulant (enoxaparin sodium) to prevent thrombosis. The epidural catheter was removed 2 h prior to the scheduled administration of enoxaparin sodium. However, the patient reported a complete lack of strength in his lower extremities 15 min after catheter removal. Upon examination, the manual muscle testing score was 1 out of 5, and the patient experienced impaired touch sensation and cold sensation below Th4. An emergency magnetic resonance imaging scan was performed 2 h after catheter removal, which revealed a possible spinal epidural hematoma spreading from Th3 to Th6. Three hours after catheter removal, we began emergency surgery to evacuate the hematoma, which had spread to Th7. After surgery, the patient showed improvements in touch sensation, cold sensation, and motor function. The patient was able to walk 2 days after hematoma removal. CONCLUSIONS: It is highly unusual for a spinal epidural hematoma to develop so rapidly after the removal of an epidural catheter. This case emphasizes the need for vigilant patient monitoring, rapid diagnosis, and prompt surgery to ensure adequate neurological recovery in these patients.

Impact of steroid medication before hospital admission on barotrauma in mechanically ventilated patients with acute respiratory distress syndrome in intensive care units.

PURPOSE: To investigate the association between steroid medication before hospital admission and barotrauma in mechanically ventilated patients with acute respiratory distress syndrome (ARDS). METHODS: An observational single-center retrospective study was conducted using patients admitted to the general intensive care unit (ICU) of a university hospital in Japan. We analyzed 149 mechanically ventilated patients with ARDS hospitalized between March 2008 and March 2011. ARDS was identified according to criteria from the Berlin Definition. Barotrauma was defined as pneumothorax, subcutaneous emphysema, or mediastinal emphysema occurring during mechanical ventilation in the ICU. The influence of steroid medication before hospital admission on barotrauma was studied using multiple logistic regression analysis. RESULTS: There were no differences in baseline patient characteristics except for congestive heart failure, peak pressure during mechanical ventilation, and steroid pulse therapy between the barotrauma and non-barotrauma groups. Logistic regression analysis showed that peak pressure ≥35 cmH2O was associated with barotrauma in patients with ARDS [odds ratio (OR), 17.34; P < 0.01], whereas steroid medication before hospital admission was not a significant factor for barotrauma (OR, 1.63; P = 0.51). CONCLUSIONS: Barotrauma in ARDS patients was associated with higher pressure during mechanical ventilation but not with steroid medication before hospital admission.

[A case of the transversus abdominis plane block in a super obese patient using a convex probe].

We report that the transversus abdominis plane block (TAP block) can be performed under ultrasound guidance using not a linear probe but a convex probe in a markedly obese patient undergoing laparoscopy-assisted distal gastrectomy. The TAP block is effective for providing perioperative analgesia. The common probe for the TAP block is a high-frequency linear probe, which can not depict the deeper tissues. We used a low-frequency convex probe for TAP block, which clearly showed the spread of local anesthetics in TAP block in a markedly obese patient. A convex probe is preferable for TAP block in markedly obese patients.

Efficacy of single-dose intravenous immunoglobulin administration for severe sepsis and septic shock.

BACKGROUND: Although some studies conducted outside of Japan have addressed the effectiveness of intravenous immunoglobulins (IVIG) in treating infections, the dosing regimens and amounts used in Japan are very different from those reported. Here, we investigate the effectiveness of single-dose administration of IVIG in sepsis patients in Japan. METHODS: We analyzed 79 patients admitted to the intensive care unit (ICU) of a tertiary care institution due to severe sepsis or septic shock. Patients were randomly divided into a group that was administered standard divided doses of IVIG (5 g/day for 3 days, designated the S group) or a group that was administered a standard single dose of IVIG (15 g/day for 1 day, H group); freeze-dried sulfonated human IVIG was used. The longitudinal assessment of procalcitonin (PCT) levels, C-reactive protein (CRP) levels, white blood cell count, blood lactate levels, IL-6 levels, Sequential Organ Failure Assessment (SOFA) score, and Systemic Inflammatory Response Syndrome (SIRS) was conducted. We also assessed mechanical ventilation duration (days), ICU stay (days), 28-day survival rate, and 90-day survival rate. RESULTS: The study showed no significant differences in PCT levels, CRP levels, 28-day survival rate, and 90-day survival rate between the two groups. However, patients in the H group showed improvements in the various SIRS diagnostic criteria, IL-6 levels, and blood lactate levels in the early stages after IVIG administration. In light of the non-recommendation of IVIG therapy in the Surviving Sepsis Campaign Guidelines 2012, our findings of significant early post-administration improvements are noteworthy. IVIG's anti-inflammatory effects may account for the early reduction in IL-6 levels after treatment, and the accompanying improvements in microcirculation may improve blood lactate levels and reduce SOFA scores. However, the low dosages of IVIG in Japan may limit the anti-cytokine effects of this treatment. Further studies are needed to determine appropriate treatment regimens of single-dose IVIG. CONCLUSIONS: In this study, we investigated the effectiveness of single-dose IVIG treatment in patients with severe sepsis or septic shock. Although there were no significant effects on patient prognoses, patients who were administered single-dose IVIG showed significantly improved IL-6 levels, blood lactate levels, and disease severity scores.