Dexmedetomidine use during orthotopic liver transplantation surgery on early allograft dysfunction: A randomized controlled trial.

BACKGROUND: Previous studies have shown a protective effect of dexmedetomidine use in kidney transplantation. In contrast, it is not known whether intraoperative administration of dexmedetomidine can reduce early allograft dysfunction incidence following liver transplantation. OBJECTIVE: To investigate the effect of dexmedetomidine use during surgery on early allograft dysfunction following orthotopic liver transplantation (OLT). STUDY DESIGN: This is a single-center, double-blinded, placebo-controlled randomized clinical trial. 330 adult patients undergoing orthotopic liver transplantation were enrolled from Jan 14th, 2019 to May 22nd, 2022. Patients received dexmedetomidine or normal saline during surgery. 1 year follow-ups were recorded. METHODS: Patients were randomized to two groups receiving either dexmedetomidine or normal saline intraoperatively. For patients in the dexmedetomidine group, a loading dose (1 µg/kg over 10 min) of dexmedetomidine was given after induction of anesthesia followed by a continuous infusion (0.5 µg/kg /h) until the end of surgery. For patients in the normal saline group, an equal volume loading dose of 0.9% saline was given after the induction of anesthesia followed by an equal volume continuous infusion until the end of surgery. The primary outcome was early allograft dysfunction. Secondary outcomes included primary graft non-function, acute kidney injury and acute lung injury/ acute respiratory distress syndrome. RESULTS: Of 330 patients included in the intention-to-treat analysis, 165 were in the dexmedetomidine group (mean [SD] age, 49 [10] years; 117 [70.9%] men), and 165 were in the normal saline group (mean SD age, 49 [9] years; 118 [74%] men). 39 (24.4%) patients in the dexmedetomidine group and 31 (19.4%) in normal saline group developed early allograft dysfunction and the difference was statistically insignificant (P=0.28). Secondary outcomes including primary graft non-function and acute kidney injury was similar between the two groups. CONCLUSION: Intraoperative administration of dexmedetomidine did not reduce early allograft dysfunction rate after orthotopic liver transplantation.

Multiscale QM/MM modelling of catalytic systems with ChemShell.

Hybrid quantum mechanical/molecular mechanical (QM/MM) methods are a powerful computational tool for the investigation of all forms of catalysis, as they allow for an accurate description of reactions occurring at catalytic sites in the context of a complicated electrostatic environment. The scriptable computational chemistry environment ChemShell is a leading software package for QM/MM calculations, providing a flexible, high performance framework for modelling both biomolecular and materials catalysis. We present an overview of recent applications of ChemShell to problems in catalysis and review new functionality introduced into the redeveloped Python-based version of ChemShell to support catalytic modelling. These include a fully guided workflow for biomolecular QM/MM modelling, starting from an experimental structure, a periodic QM/MM embedding scheme to support modelling of metallic materials, and a comprehensive set of tutorials for biomolecular and materials modelling.

Study design of the DAS-OLT trial: a randomized controlled trial to evaluate the impact of dexmedetomidine on early allograft dysfunction following liver transplantation.

BACKGROUND: Perioperative ischemia/reperfusion (I/R) injury during liver transplantation is strongly associated with early allograft dysfunction (EAD), graft loss, and mortality. Hepatic I/R injury also causes remote damage to other organs including the renal and pulmonary systems. Dexmedetomidine (DEX), a selective α2-adrenoceptor agonist which is used as an adjuvant to general anesthesia, has been shown in preclinical studies to provide organ protection by ameliorating the effects of I/R injury in a range of tissues (including the liver). However, prospective clinical evidence of any potential benefits in improving outcomes in liver transplantation is lacking. This study aimed to verify the hypothesis that the application of dexmedetomidine during the perioperative period of liver transplantation can reduce the incidence of EAD and primary graft non-function (PNF). At the same time, the effects of dexmedetomidine application on perioperative renal function and lung function were studied. METHODS: This is a prospective, single-center, randomized, parallel-group study. Two hundred participants (18-65 years) scheduled to undergo liver transplantation under general anesthesia will be included in this study. For participants in the treatment group, a loading dose of DEX will be given after induction of anesthesia (1 µg/kg over 10 min) followed by a continuous infusion (0.5 µg/kg /h) until the end of surgery. For participants in the placebo group, an equal volume loading dose of 0.9% saline will be given after the induction of anesthesia followed by an equal volume continuous infusion until the end of surgery. All other supplements, e.g., opioids, sedatives, and muscle relaxant, will be identical in both arms and administered according to routine clinical practice. DISCUSSION: The present trial will examine whether DEX confers organoprotective effects in the liver, in terms of reducing the incidence of EAD and PNF in orthotopic liver transplantation recipients. TRIAL REGISTRATION: ClinicalTrials.gov NCT03770130. Registered on 10 December 2018. https://clinicaltrials.gov/ct2/show/NCT03770130.

Anesthesia and brain tumor surgery: technical considerations based on current research evidence.

PURPOSE OF REVIEW: Anesthetics may influence cancer recurrence and metastasis following surgery by modulating the neuroendocrine stress response or by directly affecting cancer cell biology. This review summarizes the current evidence on whether commonly used anesthetics potentially affect postoperative outcomes following solid organ cancer surgery with particular focus on neurological malignancies. RECENT FINDINGS: Despite significant improvement in diagnostic and therapeutic technology over the past decades, mortality rates after cancer surgery (including brain tumor resection) remains high. With regards to brain tumors, interaction between microglia/macrophages and tumor cells by multiple biological factors play an important role in tumor progression and metastasis. Preclinical studies have demonstrated an association between anesthetics and brain tumor cell biology, and a potential effect on tumor progression and metastasis has been revealed. However, in the clinical setting, the current evidence is inadequate to draw firm conclusions on the optimal anesthetic technique for brain tumor surgery. SUMMARY: Further work at both the basic science and clinical level is urgently needed to evaluate the association between perioperative factors, including anesthetics/technique, and postoperative brain tumor outcomes.

Iatrogenic subglottic tracheal stenosis after tracheostomy and endotracheal intubation: A cohort observational study of more severity in keloid phenotype.

BACKGROUND: Tracheostomy and endotracheal intubation can result in subglottic tracheal stenosis, and predisposition to keloid scar formation can increase stenosis risk after tracheal injury. This study aims to compare the incidence and severity of subglottic tracheal stenosis in keloid and non-keloid patients following iatrogenic tracheal injury, in particular tracheostomy. METHODS: From 2012 to 2017, 218 573 patients were intubated for surgery; 2276 patients received tracheostomy in People's Hospital of Zhengzhou University, China. Among these patients, 133 patients, who developed tracheal stenosis after intubation and/or tracheostomy, were divided into keloid or non-keloid groups; their Myer and Cotton grading of tracheal stenosis, time-to-onset of airway stenosis, and treatment outcome were assessed and compared. RESULTS: The percentages of high grade (Myer and Cotton grading III/IV) tracheal stenosis were higher among keloid patients than non-keloid patients (intubation: 83.3% vs 25.7%; tracheostomy: 77.7% vs 33.3%). Time-to-onset of airway stenosis following intubation (tracheostomy) was 27 ± 5 (38 ± 13) and 41 ± 7 (82 ± 14) days for keloid and non-keloid patients, respectively (P < 0.01). The incidence of tracheal stenosis is higher in keloid than non-keloid subjects (19.4% vs 1.82%, P < 0.001). Keloid patients also required more frequent treatment (P < 0.01) of longer duration, yet cure rate was significantly lower (P < 0.01). CONCLUSIONS: Our study suggests that tracheostomized patients with keloid phenotype are more susceptibility to develop iatrogenic tracheal stenosis of greater severity and with poorer treatment outcome. Greater cautions may be required when performing tracheostomy in keloid subjects. More substantive analysis is warranted to establish keloid phenotype as a risk factor for tracheal stenosis.

Both Bupivacaine and Levobupivacaine inhibit colon cancer cell growth but not melanoma cells in vitro.

BACKGROUND: Retrospective studies indicate that the use of regional anaesthesia causes a reduction in cancer recurrence after oncological surgery, which could be due to anaesthetic's negating effect on immunosuppression related to the surgical stress response. Local anaesthetics may also exert direct suppressive effects on malignant cells, an area where further investigation is urgently needed. METHODS: Human colon cancer cells and human melanoma cells were cultured and then treated with 1 mM bupivacaine or levobupivacaine for up to 24 or 48 h. Their migratory ability was measured by scratch assay, proliferation determined with Ki67 immunofluorescence staining, and apoptosis accessed with annexin V and PI staining on flow cytometry. The effects of bupivacaine and levobupivacaine on cellular signaling and molecular response, specifically, on endoplasmic reticulum stress (ERS), were studied with immunostaining and western blot. RESULTS: In colon cancer cells, treatment with bupivacaine and levobupivacaine significantly inhibited cell migration (**p < 0.01, ***p < 0.001; n = 4) and proliferation (**p < 0.01; n = 4), while increasing the expression of CHOP (***p < 0.001; n = 4) and decreased the expression of Grp78 (*p < 0.05; n = 4). These effects were not mirrored by melanoma cells, such that no significant increase in apoptosis was seen in either melanoma cell lines following treatment. CONCLUSION: These in vitro data suggested that both bupivacaine and levobupivacaine suppress colorectal adenocarcinoma cell proliferation and migration, which are concurrent with increased endoplasmic reticulum stress. Conversely, melanoma cells are more resilient to these two commonly used local anaesthetics. Further in vivo studies or clinical trials are needed.

Dexmedetomidine attenuates spinal cord ischemia-reperfusion injury through both anti-inflammation and anti-apoptosis mechanisms in rabbits.

BACKGROUND: Dexmedetomidine (Dex) can improve neuronal viability and protect the spinal cord from ischemia-reperfusion (I/R) injury, but the underlying mechanisms are not fully understood. This study investigated the effects of dexmedetomidine on the toll-like receptor 4 (TLR4)-mediated nuclear factor κB (NF-κB) inflammatory system and caspase-3 dependent apoptosis induced by spinal cord ischemia-reperfusion injury. METHODS: Twenty-four rabbits were divided into three groups: I/R, Dex (10 µg/kg/h prior to ischemia until reperfusion), and Sham. Abdominal aortic occlusion was carried out for 30 min in the I/R and Dex groups. Hindlimb motor function was assessed using the Tarlov scoring system for gait evaluation. Motor neuron survival and apoptosis in the ventral grey matter were assessed by haematoxylin-eosin staining and terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end labelling staining. The expression and localisation of ionised calcium-binding adaptor molecule 1, TLR4, NF-κB and caspase-3 were assessed by immunoreactivity analysis. The levels of interleukin 1ß and tumour necrosis factor α were assessed using enzyme-linked immunosorbent assays. RESULTS: Perioperative treatment with dexmedetomidine was associated with a significant preservation of locomotor function following spinal cord ischemia-reperfusion injury with increased neuronal survival in the spinal cord compared to control. In addition, dexmedetomidine suppressed microglial activation, inhibited the TLR4-mediated NF-κB signalling pathway, and inhibited the caspase-3 dependent apoptosis. CONCLUSIONS: Dexmedetomidine confers neuroprotection against spinal cord ischemia-reperfusion injury through suppression of spinal cord inflammation and neuronal apoptosis. A reduction in microglial activation and inhibition of both the TLR4-mediated NF-κB signalling pathway and caspase-3 dependent apoptosis are implicated.

Characterisation of recombinant HERG K+ channel blockade by the Class Ia antiarrhythmic drug procainamide.

Class Ia antiarrhythmic drugs, including procainamide (PROC), are associated with cardiac sodium channel blockade, delayed ventricular repolarisation and with a risk of ventricular pro-arrhythmia. The HERG K(+) channel is frequently linked to drug-induced pro-arrhythmia. Therefore, in this study, interactions between PROC and HERG K(+) channels were investigated, with particular reference to potency and mechanism of drug action. Whole-cell patch-clamp recordings of HERG current (I(HERG)) were made at 37 degrees C from human embryonic kidney (HEK 293) cells stably expressing the HERG channel. Following activating pulses to +20 mV, I(HERG) tails were inhibited by PROC with an IC(50) value of approximately 139 microM. I(HERG) blockade was found to be both time- and voltage-dependent, demonstrating contingency upon HERG channel gating. However, I(HERG) inhibition by PROC was relieved by depolarisation to a highly positive membrane potential (+80 mV) that favoured HERG channel inactivation. These data suggest that PROC inhibits the HERG K(+) channel by a primarily 'open' or 'activated' channel state blocking mechanism and that avidity of drug-binding is decreased by extensive I(HERG) inactivation. The potency of I(HERG) blockade by PROC is much lower than for other Class Ia agents that have been studied previously under analogous conditions (quinidine and disopyramide), although the blocking mechanism appears similar. Thus, differences between the chemical structure of PROC and other Class Ia antiarrhythmic drugs may help provide insight into chemical determinants of blocking potency for agents that bind to open/activated HERG channels.