Perioperative ischaemia-induced liver injury and protection strategies: An expanding horizon for anaesthesiologists

BAPST. A Combo of Common use drugs as metabolic therapy of cancer-a theoretical proposal

Advances in cancer therapy have yet to impact worldwide cancer mortality. Poor cancer drug affordability is one of the factors limiting mortality burden strikes. Up to now, cancer drug repurposing had no meet expectations concerning drug affordability. The three FDA-approved cancer drugs developed under repurposing -all-trans-retinoic acid, arsenic trioxide, and thalidomide- do not differ in price from other drugs developed under the classical model. Though additional factors affect the whole process from inception to commercialization, the repurposing of widely used, commercially available, and cheap drugs may help. This work reviews the concept of the malignant metabolic phenotype and its exploitation by simultaneously blocking key metabolic processes altered in cancer. We elaborate on a combination called BAPST, which stands for the following drugs and pathways they inhibit: Benserazide (glycolysis), Apomorphine (glutaminolysis), Pantoprazole (Fatty-acid synthesis), Simvastatin (mevalonate pathway), and Trimetazidine (Fatty-acid oxidation). Their respective primary indications are: • Parkinson's disease (benserazide and apomorphine). • Peptic ulcer disease (pantoprazole). • Hypercholesterolemia (simvastatin). • Ischemic heart disease (trimetazidine). When used for their primary indication, the literature review on each of these drugs shows they have a good safety profile and lack predicted pharmacokinetic interaction among them. Most importantly, the inhibitory enzymatic concentrations required for inhibiting their cancer targets enzymes are below the plasma concentrations observed when these drugs are used for their primary indication. Based on that, we propose that the regimen BAPTS merits preclinical testing.

Remifentanil preconditioning promotes liver regeneration via upregulation of β-arrestin 2/ERK/cyclin D1 pathway

Remifentanil is a potent, short-acting opioid analgesic drug that can protect tissues from ischemia and reperfusion injury though anti-inflammatory effects. However, the utility of remifentanil in liver regeneration after hepatectomy is not known. Using a 70% hepatectomy mouse model (PHx), we found that preconditioning animals with 4 μg/kg remifentanil enhanced liver regeneration through supporting hepatocyte proliferation but not through anti-inflammatory effects. These effects were also phenocopied in vitro where 40 mM remifentanil promoted the proliferation of primary mouse hepatocyte cultures. We further identified that remifentanil treatment increased the expression of β-arrestin 2 in vivo and in vitro. Demonstrating specificity, remifentanil preconditioning failed to promote liver regeneration in liver-specific β-arrestin 2 knockout (CKO) mice subjected to PHx. While remifentanil increased the expression of activated (phosphorylated)-ERK and cyclin D1 in PHx livers, their levels were not significantly changed in remifentanil-treated CKO mice nor in WT mice pretreated with the ERK inhibitor U0126. Our findings suggest that remifentanil promotes liver regeneration via upregulation of a β-arrestin 2/ERK/cyclin D1 axis, with implications for improving regeneration process after hepatectomy.

Pharmacological postconditioning: a molecular aspect in ischemic injury

OBJECTIVE

Ischaemia/reperfusion (I/R) injury is defined as the damage to the tissue which is caused when blood supply returns to tissue after ischaemia. To protect the ischaemic tissue from irreversible injury, various protective agents have been studied but the benefits have not been clinically applicable due to monotargeting, low potency, late delivery or poor tolerability.

KEY FINDINGS

Strategies involving preconditioning or postconditioning can address the issues related to the failure of protective therapies. In principle, postconditioning (PoCo) is clinically more applicable in the conditions in which there is unannounced ischaemic event. Moreover, PoCo is an attractive beneficial strategy as it can be induced rapidly at the onset of reperfusion via series of brief I/R cycles following a major ischaemic event or it can be induced in a delayed manner. Various pharmacological postconditioning (pPoCo) mechanisms have been investigated systematically. Using different animal models, most of the studies on pPoCo have been carried out preclinically.

SUMMARY

However, there is a need for the optimization of the clinical protocols to quicken pPoCo clinical translation for future studies. This review summarizes the involvement of various receptors and signalling pathways in the protective mechanisms of pPoCo.

Preconditioning Effect of Remifentanil Versus Fentanyl in Prevalence of Early Graft Dysfunction in Patients After Liver Transplant: A Randomized Clinical Trial

OBJECTIVES

One of the most prevalent complications of orthotopic liver transplant is primary graft dysfunction. Recent studies have shown the preconditioning effect of remifentanil on animal livers but not human livers. Here, we compared the preconditioning effects of remifentanil and fentanyl in orthotopic liver transplant in human patients.

MATERIALS AND METHODS

In this double-blind clinical trial, 100 patients who underwent liver transplant from deceased donors were randomly allocated into 2 groups. Patients in the remifentanil group received remifentanil infusion, and those in the fentanyl group received fentanyl infusion during maintenance of anesthesia. Serum aminotransferase levels, prothrombin time (international normalized ratio), partial thrombin time, arterial blood gas levels, and renal function tests were evaluated over 7 days posttransplant. Intensive care unit stay and hospitalization were also recorded.

RESULTS

The median peak alanine aminotransferase level during 7 days after transplant was 2100 U/L (interquartile range, 1230-3220) in the remifentanil group and 3815 U/L (interquartile range, 2385-5675) in the fentanyl group (P = .048). Metabolic acidosis, renal state, prothrombin time (international normalized ratio), and partial thrombin time were similar in both groups (P > .05). Durations of stay in the intensive care unit and hospital were not significantly different between the 2 groups (P = .75 and P = .23, respectively). Overall, the clinical outcomes were similar in the remifentanil and fentanyl groups (P > .05).

CONCLUSIONS

We found that remifentanil and fentanyl were not different with regard to their preconditioning effects and graft protection in orthotopic liver transplant recipients.

Remifentanil Preconditioning Attenuates Hepatic Ischemia-Reperfusion Injury in Rats via Neuronal Activation in Dorsal Vagal Complex

Remifentanil, an ultra-short acting opiate, has been reported to protect against hepatic ischemia-reperfusion injury, which is a major cause of postoperative liver dysfunction. The objective of this study was to determine whether a central vagal pathway is involved in this protective procedure. Rat models of hepatic ischemia-reperfusion were used in the experimental procedures. The results revealed that intravenous pretreatment with remifentanil decreased serum aminotransferases and hepatic histologic damage; however, an intraperitoneal injection of μ-opioid receptor antagonist did not abolish the protection of remifentanil preconditioning. c-Fos immunofluorescence of the brain stem showed that dorsal motor nucleus of the vagus was activated after remifentanil preconditioning. Moreover, serum alanine aminotransferase, histopathologic damage, and apoptosis decreased in remifentanil preconditioning group compared to vagotomized animals with remifentanil preconditioning, and there was no statistical difference of TNF-α and IL-6 between NS/Va and RPC/Va groups. In addition, remifentanil microinjection into dorsal vagal complex decreased serum aminotransferases, inflammatory cytokines, and hepatic histologic injury and apoptosis, and these effects were also abolished by a peripheral hepatic vagotomy. In conclusion, remifentanil preconditioning conferred liver protection against ischemia-reperfusion injury, which was mediated by the central vagal pathway.

Adenosine A1 and A2A Receptors in the Brain: Current Research and Their Role in Neurodegeneration

The inhibitory adenosine A1 receptor (A1R) and excitatory A2A receptor (A2AR) are predominantly expressed in the brain. Whereas the A2AR has been implicated in normal aging and enhancing neurotoxicity in multiple neurodegenerative diseases, the inhibitory A1R has traditionally been ascribed to have a neuroprotective function in various brain insults. This review provides a summary of the emerging role of prolonged A1R signaling and its potential cross-talk with A2AR in the cellular basis for increased neurotoxicity in neurodegenerative disorders. This A1R signaling enhances A2AR-mediated neurodegeneration, and provides a platform for future development of neuroprotective agents in stroke, Parkinson’s disease and epilepsy.

Anesthesia for the Patient with Concomitant Hepatic and Renal Impairment

Hepatic and renal disease are common comorbidities in patients presenting for intermediate- and high-risk surgery. With the evolution of perioperative medicine, anesthesiologists are encountering more patients who have significant hepatic and renal disease, both acute and chronic in nature. It is important that anesthesiologists have an in-depth understanding of the physiologic derangements seen with hepatic and renal disease to evaluate and manage these patients appropriately. Perioperative management requires an understanding of the physiologic perturbations associated with each disease process. This article elucidates the goals in the management and treatment of this complex patient population.

Impact of ischemic preconditioning on ischemia-reperfusion injury of the rat sciatic nerve

The aim of this study was to assess the preventive effects of ischemic preconditioning (IPC) on ischemia-reperfusion (IR) injury in the sciatic nerve of the rat hind limb. This study included two experiments. For Experiment 1, 40 Sprague-Dawley (SD) rats were randomly divided into 4 equal groups that received different IPC treatments prior to IR. Serum concentrations of aspartate aminotransferase (AST), lactate dehydrogenase (LDH), malondialdehyde (MDA), and superoxide dismutase (SOD) were assessed following reperfusion. Furthermore, we tested the electrophysiological response and ultrastructural changes in the ipsilateral sciatic nerve after IR. After determining the best IPC protocol for protection, we performed a second experiment with 30 SD rats randomly divided into 3 equal groups. Each group underwent 1, 2, or 3 IPC cycles before prolonged ischemia and reperfusion. The same analyses as in Experiment 1 were performed. In Experiment 1, the AST, LDH, and MDA concentrations were decreased in all IPC groups compared with the control group. Concentration of these enzymes showed decreases with increasing IPC cycle number in Experiment 2; however, the difference between 2 and 3 cycles of IPC did not reach significance. Conversely, SOD activity increased in the rapid and delayed groups, and with increasing cycles of IPC. The electrophysiological test showed a decrease in amplitude and increase in conduction velocity with increasing IPC cycles. Moreover, ultrastructural damage decreased with increasing IPC cycles. IPC protected against IR injury in the peripheral nerves. This effect was positively correlated with the number of IPC cycles.