Joseph SchianodiCola

Propofol induces MAPK/ERK cascade dependant expression of cFos and Egr-1 in rat hippocampal slices

BackgroundPropofol is a commonly used intravenous anesthetic agent, which produce rapid induction of and recovery from general anesthesia. Numerous clinical studies reported that propofol can potentially cause amnesia and memory loss in human subjects. The underlying mechanism for this memory loss is unclear but may potentially be related to the induction of memory-associated genes such as c-Fos and Egr-1 by propofol. This study explored the effects of propofol on c-Fos and Egr-1 expression in rat hippocampal slices.FindingsHippocampal brain slices were exposed to varying concentrations of propofol at multiple time intervals. The transcription of the immediate early genes, c-Fos and Egr-1, was quantified using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). MAPK/ERK inhibitors were used to investigate the mechanism of action. We demonstrate that propofol induced the expression of c-Fos and Egr-1 within 30 and 60 min of exposure time. At 16.8 μM concentration, propofol induced a 110% increase in c-Fos transcription and 90% decrease in the transcription of Egr-1. However, at concentrations above 100 μM, propofol failed to induce expression of c-Fos but did completely inhibit the transcription of Egr-1. Propofol-induced c-Fos and Egr-1 transcription was abolished by inhibitors of RAS, RAF, MEK, ERK and p38-MAPK in the MAPK/ERK cascade.ConclusionsOur study shows that clinically relevant concentrations of propofol induce c-Fos and down regulated Egr-1 expression via an MAPK/ERK mediated pathway. We demonstrated that propofol induces a time and dose dependant transcription of IEGs c-Fos and Egr-1 in rat hippocampal slices. We further demonstrate for the first time that propofol induced IEG expression was mediated via a MAPK/ERK dependant pathway. These novel findings provide a new avenue to investigate transcription-dependant mechanisms and suggest a parallel pathway of action with an unclear role in the activity of general anesthetics.

Efficacy of ginger on intraoperative and postoperative nausea and vomiting in elective cesarean section patients

OBJECTIVE To evaluate the efficacy of dry powdered ginger, given orally, on nausea and vomiting during and after an elective cesarean section performed under combined spinal epidural anesthesia. STUDY DESIGN 239 women, ginger (n=116) and placebo (n=123), who underwent elective cesarean section at term under combined spinal-epidural anesthesia were provided with standard preoperative antiemetic treatment in addition to a randomized study drug. They were given two capsules (1g each) of either dry powdered ginger or placebo, one capsule a half-hour before induction of anesthesia and the second 2h after surgery. The study was double-blinded and the incidences of nausea and vomiting were assessed both intraoperatively and postoperatively. Levels of pain and pruritus were also assessed postoperatively. RESULTS The intraoperative incidence of nausea was 52% and 61%, ginger versus placebo (p=0.149). The number of episodes of intraoperative nausea was less in the ginger group compared to placebo (mean difference was -0.396, 95% CI -0.738, -0.054) and the result was statistically significant (p=0.023). The incidence of intraoperative vomiting was 27.35% in the ginger group and 36.59% in the placebo group, and the difference was not statistically significant (p=0.126). The number of episodes of vomiting during surgery was less in the ginger group compared to placebo: (mean difference -0.158, 95% CI -0.626, 0.311) although statistically insignificant (p=0.505). Furthermore, postoperatively, there was no statistical difference in the incidence of nausea and vomiting assessed at 0, 2, 2 ½ and 24h after surgery. There were also no differences in postoperative pain or pruritus. CONCLUSION Ginger given in dry powdered form reduced the number of episodes of intraoperative nausea compared to a placebo, but it had no effect on incidence of nausea, vomiting, or pain during and after an elective cesarean section performed under combined spinal epidural anesthesia.

Propofol induces ERK-dependant expression of c-Fos and Egr-1 in neuronal cells.

This study explored the effects of propofol on c-Fos and Egr-1 in neuroblastoma (N2A) cells. We demonstrate that propofol induced the expression of c-Fos and Egr-1 within 30 and 60 min of exposure time. At 16.8 μM concentration, propofol induced a 6 and 2.5-fold expression of c-Fos and Egr-1, respectively. However, at concentrations above 100 μM, propofol failed to induce expression of c-Fos or Egr-1. Propofol-induced c-Fos and Egr-1 transcription was unaffected by bicuculline, a &ggr;-aminobutyric acid-A receptor antagonist, but was abolished by PD98059, a mitogen-activated protein kinase/extracellular signal-regulated kinase inhibitor. Our study shows that clinically relevant concentrations of propofol induce c-Fos and Egr-1 expression through an extracellular signal-regulated kinase mediated and &ggr;-aminobutyric acid-A independent pathway.

A randomized, prospective, double-blind trial comparing 3% chloroprocaine followed by 0.5% bupivacaine to 2% lidocaine followed by 0.5% bupivacaine for interscalene brachial plexus block.

BACKGROUND: The combination of 2-chloroprocaine and bupivacaine (C/B) for regional anesthesia has been described, but its use was largely abandoned due to equivocal results in efficacy. In this prospective, double-blind, randomized study, we compared the onset of an interscalene block using C/B versus a combination of lidocaine and bupivacaine (L/B). METHODS: Thirty patients scheduled for shoulder arthroscopy under interscalene block were divided into two groups of 15 each. One group (C/B) received 3% 2-chloroprocaine combined with bicarbonate and epinephrine, immediately followed by 0.5% bupivacaine and epinephrine, whereas the other group (L/B) received 2% lidocaine instead of 3% 2-chloroprocaine. Motor and sensory block were assessed every 15 s. The primary end-point was the time of onset to complete motor block. Time-to-event (survival) statistical analysis tests were applied. RESULTS: One L/B patient had a failed block, and was excluded. The median time to motor block for C/B and L/B was 90 (15–575) and 180 (15–3720) s, respectively (P = 0.0325), and to sensory block for C/B and L/B was 90 (30–600) and 210 (30–3900) s, respectively (P = 0.0185). Survival analysis showed that in 5 min, 13 of 15 patients from the C/B group but only 7 of 14 from the L/B group had a successful motor block. In 10 min, 15 of 15 patients from the C/B group but only 10 of 14 from the L/B group had a successful motor block. It took as long as 60 min to assess block success/failure for blocks in the L/B group. CONCLUSIONS: This study demonstrates that a successful block was more rapid using C/B than L/B for interscalene blocks.

Bicarbonate plus epinephrine shortens the onset and prolongs the duration of sciatic block using chloroprocaine followed by bupivacaine in sprague-dawley rats.

Background: Chloroprocaine is a fast-acting local anesthetic, whereas bupivacaine is a long-acting one. They have been coadministered with limited success. The objective of this study was to determine the effect of additives on the efficacy of regional blockade using chloroprocaine followed by bupivacaine. Methods: Four groups of Sprague-Dawley rats, 20 each, were administered chloroprocaine followed by bupivacaine to induce sciatic nerve blockade. Group 1 received chloroprocaine with isotonic sodium chloride solution followed by bupivacaine and was used as a control. Group 2 received chloroprocaine with isotonic sodium chloride solution and epinephrine followed by bupivacaine with epinephrine. Group 3 received chloroprocaine with sodium bicarbonate followed by bupivacaine, and group 4 received chloroprocaine with sodium bicarbonate and epinephrine followed by bupivacaine with epinephrine. The time to onset and duration of anesthesia were measured for all 4 groups. Results: The block using chloroprocaine followed by bupivacaine in group 1 had an onset of 2.5 mins (SD, 0.4 mins) and duration of 104 mins (SD, 16 mins). Adding epinephrine to both chloroprocaine and bupivacaine (group 2) did not significantly change the onset (2.8 mins [SD, 1.3 mins]; P = 0.35) or duration (110 mins [SD, 25 mins]; P = 0.23). With group 3, adding bicarbonate to chloroprocaine hastened the onset (1.2 mins [SD, 0.4 mins]; P < 0.0001) and shortened the duration (87 mins [SD, 13 mins]; P = 0.008). In group 4, adding bicarbonate and epinephrine to chloroprocaine and epinephrine to bupivacaine hastened the onset (1.4 mins [SD, 0.4 mins]; P < 0.0001) and increased the duration (130 mins [SD, 23 mins]; P < 0.0001). Conclusions: Sodium bicarbonate plus epinephrine shortens the onset and prolongs the duration of a chloroprocaine-bupivacaine sciatic block in Sprague-Dawley rats.

The effect of local anesthetic on pro-inflammatory macrophage modulation by mesenchymal stromal cells.

Administering local anesthetics (LAs) peri- and post-operatively aims to prevent or mitigate pain in surgical procedures and after tissue injury in cases of osteoarthritis (OA) and other degenerative diseases. Innovative tissue protective and reparative therapeutic interventions such as mesenchymal stromal cells (MSCs) are likely to be exposed to co-administered drugs such as LAs. Therefore, it is important to determine how this exposure affects the therapeutic functions of MSCs and other cells in their target microenvironment. In these studies, we measured the effect of LAs, lidocaine and bupivacaine, on macrophage viability and pro-inflammatory secretion. We also examined their effect on modulation of the macrophage pro-inflammatory phenotype in an in vitro co-culture system with MSCs, by quantifying macrophage tumor necrosis factor (TNF)-α secretion and MSC prostaglandin E2 (PGE2) production. Our studies indicate that both LAs directly attenuated macrophage TNF-α secretion, without significantly affecting viability, in a concentration- and potency-dependent manner. LA-mediated attenuation of macrophage TNF-α was sustained in co-culture with MSCs, but MSCs did not further enhance this anti-inflammatory effect. Concentration- and potency-dependent reductions in macrophage TNF-α were concurrent with decreased PGE2 levels in the co-cultures further indicating MSC-independent macrophage attenuation. MSC functional recovery from LA exposure was assessed by pre-treating MSCs with LAs prior to co-culture with macrophages. Both MSC attenuation of TNF-α and PGE2 secretion were impaired by pre-exposure to the more potent bupivacaine and high dose of lidocaine in a concentration-dependent manner. Therefore, LAs can affect anti-inflammatory function by both directly attenuating macrophage inflammation and MSC secretion and possibly by altering the local microenvironment which can secondarily reduce MSC function. Furthermore, the LA effect on MSC function may persist even after LA removal.

Effect of Local Anesthetics on Human Mesenchymal Stromal Cell Secretion.

Anti-fibrotic and tissue regenerative mesenchymal stromal cell (MSC) properties are largely mediated by secreted cytokines and growth factors. MSCs are implanted to augment joint cartilage replacement and to treat diabetic ulcers and burn injuries simultaneously with local anesthetics, which reduce pain. However, the effect of anesthetics on therapeutic human MSC secretory function has not been evaluated. In order to assess the effect of local anesthetics on the MSC secretome, a panel of four anesthetics with different potencies - lidocaine, procaine, ropivacaine and bupivacaine - was evaluated. Since injured tissues secrete inflammatory cytokines, the effects of anesthetics on MSCs stimulated with tumor necrosis factor (TNF)-α and interferon (IFN)-γ were also measured. Dose dependent and anesthesia specific effects on cell viability, post exposure proliferation and secretory function were quantified using alamar blue reduction and immunoassays, respectively. Computational pathway analysis was performed to identify upstream regulators and molecular pathways likely associated with the effects of these chemicals on the MSC secretome. Our results indicated while neither lidocaine nor procaine greatly reduced unstimulated cell viability, ropivacaine and bupivacaine induced dose dependent viability decreases. This pattern was exaggerated in the simulated inflammatory environment. The reversibility of these effects after withdrawal of the anesthetics was attenuated for TNF-α/IFN-γ-stimulated MSCs exposed to ropivacaine and bupivacaine. In addition, secretome analysis indicated that constitutive secretion changes were clearly affected by both anesthetic alone and anesthetic plus TNFα/IFNγ cell stimulation, but the secretory pattern was drug specific and did not necessarily coincide with viability changes. Pathway analysis identified different intracellular regulators for stimulated and unstimulated MSCs. Within these groups, ropivacaine and bupivacaine appeared to act on MSCs similarly via the same regulatory mechanisms. Given the variable effect of local anesthetics on MSC viability and function, these studies underscore the need to evaluate MSC in the presence of medications, such as anesthetics, that are likely to accompany cell implantation.

Intraoperatively Diagnosed Tracheal Tear after Using an NIM EMG ETT with Previously Undiagnosed Tracheomalacia

Tracheal rupture is a rare complication of endotracheal intubation. We present a case of tracheal rupture that was diagnosed intraoperatively after the use of an NIM EMG endotracheal tube. A 66-year-old female with a recurrent multinodular goiter was scheduled for total thyroidectomy. Induction of anesthesia was uncomplicated. Intubation was atraumatic using a 6 mm NIM EMG endotracheal tube (ETT). Approximately 90 minutes into the surgery, a tracheal tear was suspected. After confirming the diagnosis, conservative treatment with antibiotic coverage was favored. The patient made a full recovery with no complications. Diagnosis of the tracheal tear was made intraoperatively, prompting early management.

Aspiration during electroconvulsive therapy under general anesthesia.

Electroconvulsive Therapy Under General Anesthesia To the Editor: We often assume that patients who have had nothing by mouth (NPO) for more than 8 hours have nothing in their stomach. Exceptions include the very anxious (eg, trauma), the big-bellied patient (eg, pregnancy, obese), the neurologically impaired patient (eg, diabetes, renal failure), ileus or bowel obstruction, hiatal hernia, and enteral tube feeding. We present a case of aspiration during electroconvulsive therapy (ECT) under general anesthesia. A 51-year-old man (weight 77 kg) was admitted to the hospital for major depression because he was not responding to antidepressants. After evaluation by the psychiatric team, the patient was scheduled for ECT in the morning. The patient had a history of hyperlipidemia. His medications included rosuvastatin, quetiapine, and venlafaxine. The patient did not have any surgical history. The preanesthetic evaluation revealed a severely depressed patient communicating in a low voice, with no anticipated airway difficulties. The patient had nothing by mouth for approximately 14 hours before the procedure. The patient complained of constipation and lower abdominal discomfort that had fully resolved 4 hours before the procedure, after a normal bowel movement. Anesthetic Management The patient was connected to standard American Society of Anesthesiologists monitors in the ECT room. The patient was scheduled to undergo a standard-dose titration protocol for the ECTVstarting with a low dose of right unilateral ultrabrief pulse of 0.3 millisecond, 1-second duration, 20 Hz, at 800 mA. Isolated limb technique (left lower limb isolation by using the tourniquet inflation before the muscle relaxant) was used during ECT to measure the motor activity along with electroencephalogram monitoring. He was preoxygenated with 100% oxygen as he was spontaneously breathing through a transparent facemask covering the nose and mouth with a tight seal using a Mapleson F (Jackson-Rees) anesthesia circuit for 3 minutes. General anesthesia was induced with methohexital 80 mg (È1 mg/kg) intravenously (IV). Succinylcholine 60 mg (È0.75 mg/kg) IV was given next after a bite block was placed, and ventilation was possible with the transparent facemask secured with head straps. The first stimulus of ECTwas administered following clinical cessation of eyelid fasciculation. No nerve stimulator was used to assess the depth of paralysis. The first dose of ECT was administered without a response. After 30 seconds, a second stimulus was administered, and the patient started convulsing, but without arching his back. The motor seizure duration was 65 seconds and the electroencephalogram seizure duration was 94 seconds. He immediately began producing copious amounts of semisolid food and secretions through the mouth and nose. His heart rate was 124 beats/min, blood pressure 156/86 mm Hg, and oxygen saturation (SpO2) 96%. At this juncture, the patient was given an additional dose of methohexital 60 mg IV and succinylcholine 40 mg IV. He was rapidly intubated orally with a 7-mm cuffed endotracheal tube (ETT). Aspiration from the ETT revealed particulate matter, whereas aspiration from an orogastric tube revealed minimal secretions. The patient was sedated with a propofol infusion 25 to 50 Hg/kg per minute and transferred to the intensive care unit maintaining an SpO2 of 88% to 90% on 100% oxygen. Bronchoscopy and lavage through the ETT tube showed partially digested rice and beans that were consumed more than 20 hours before the procedure. The consulting gastroenterologist diagnosed a ‘‘possible depression-associated gastroparesis.’’ The patient appeared to have had sustained an irreversible pulmonary injury and died 35 days after the event because of sepsis and multiorgan failure.

Comparison of the Potency of Lidocaine and Chloroprocaine in Sciatic Nerve Block in Sprague-Dawley Rats

Aim: This study investigates the relative potencies and ED50 of the local anesthetics lidocaine and chloroprocaine in a sciatic block in Sprague-Dawley rats. Methods: The study involved 80 rats (chloroprocaine n = 40, lidocaine n = 40). Each rat was injected close to the sciatic nerve with 0.1 ml of the concentration of local anesthetic being tested. Using the up-and-down allocation technique, the next concentration was determined by the response of the previous subject to a higher or lower concentration. A successful block was assessed by pinching the fifth metatarsal. Absent vocalization and a very weak withdrawal response were defined as the onset of block. Results: Using the up-and-down methodology, the estimates of ED50 for chloroprocaine was 0.1 ml of 1.2% (with 95% CI of 1.1–1.6), and that for lidocaine was 0.1 ml of 0.65% (with 95% CI of 0.65–0.88), giving a lidocaine/chloroprocaine potency ratio of 1.85 (with 95% CI of 1.66–2.61). Discussion: Using the results of this study, the effects of the two drugs can be compared using the commercially available concentrations of chloroprocaine and lidocaine in a peripheral nerve block.