The Role of Preconditioning and N-Acetylcysteine on Oxidative Stress Resulting From Tourniquet-Induced Ischemia-Reperfusion in Arthroscopic Knee Surgery

Efficacy of remote ischaemic preconditioning on outcomes following non-cardiac non-vascular surgery: a systematic review and meta-analysis

BACKGROUND

Remote ischaemic preconditioning (RIPC) has been investigated as a simple intervention to potentially mitigate the ischaemic effect of the surgical insult and reduce postoperative morbidity. This review systematically evaluates the effect of RIPC on morbidity, including duration of hospital stay and parameters reflective of cardiac, renal, respiratory, and hepatic dysfunction following non-cardiac non-vascular (NCNV) surgery.

METHODS

The electronic databases PubMed, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched from their inception date to November 2021. Studies investigating the effect of local preconditioning or postconditioning were excluded. Methodological quality and risk of bias were determined according to the Revised Cochrane risk-of-bias tool for randomised trials (RoB 2). Calculation of the odds ratios and a random effects model was used for dichotomous outcomes and mean differences or standardised mean differences as appropriate were used for continuous outcomes. The primary outcomes of interest were cardiac and renal morbidity, and the secondary outcomes included other organ function parameters and hospital length of stay.

RESULTS

A systematic review of the published literature identified 36 randomised controlled trials. There was no significant difference in postoperative troponin or acute kidney injury. RIPC was associated with lower postoperative serum creatinine (9 studies, 914 patients, mean difference (MD) - 3.81 µmol/L, 95% confidence interval (CI) - 6.79 to - 0.83, p = 0.01, I² = 5%) and lower renal stress biomarker (neutrophil gelatinase-associated lipocalin (NGAL), 5 studies, 379 patients, standardized mean difference (SMD) - 0.66, 95% CI - 1.27 to - 0.06, p = 0.03, I² = 86%). RIPC was also associated with improved oxygenation (higher P_aO₂/F_iO₂, 5 studies, 420 patients, MD 51.51 mmHg, 95% CI 27.32 to 75.69, p < 0.01, I² = 89%), lower biomarker of oxidative stress (malondialdehyde (MDA), 3 studies, 100 patients, MD - 1.24 µmol/L, 95% CI - 2.4 to - 0.07, p = 0.04, I² = 91%)) and shorter length of hospital stay (15 studies, 2110 patients, MD - 0.99 days, 95% CI - 1.75 to - 0.23, p = 0.01, I² = 88%).

CONCLUSIONS

This meta-analysis did not show an improvement in the primary outcomes of interest with the use of RIPC. RIPC was associated with a small improvement in certain surrogate parameters of organ function and small reduction in hospital length of stay. Our results should be interpreted with caution due to the limited number of studies addressing individual outcomes and the considerable heterogeneity identified.

TRIAL REGISTRATION

PROSPERO CRD42019129503.

Effect of Remote Ischaemic Preconditioning on Perioperative Endothelial Dysfunction in Non-Cardiac Surgery: A Randomised Clinical Trial

Endothelial dysfunction result from inflammation and excessive production of reactive oxygen species as part of the surgical stress response. Remote ischemic preconditioning (RIPC) potentially exerts anti-oxidative and anti-inflammatory properties, which might stabilise the endothelial function after non-cardiac surgery. This was a single centre randomised clinical trial including 60 patients undergoing sub-acute laparoscopic cholecystectomy due to acute cholecystitis. Patients were randomised to RIPC or control. The RIPC procedure consisted of four cycles of five minutes of ischaemia and reperfusion of one upper extremity. Endothelial function was assessed as the reactive hyperaemia index (RHI) and circulating biomarkers of nitric oxide (NO) bioavailability (L-arginine, asymmetric dimethylarginine (ADMA), L-arginine/ADMA ratio, tetra- and dihydrobiopterin (BH4 and BH2), and total plasma biopterin) preoperative, 2–4 h after surgery and 24 h after surgery. RHI did not differ between the groups (p = 0.07). Neither did levels of circulating biomarkers of NO bioavailability change in response to RIPC. L-arginine and L-arginine/ADMA ratio was suppressed preoperatively and increased 24 h after surgery (p < 0.001). The BH4/BH2-ratio had a high preoperative level, decreased 2–4 h after surgery and remained low 24 h after surgery (p = 0.01). RIPC did not influence endothelial function or markers of NO bioavailability until 24 h after sub-acute laparoscopic cholecystectomy. In response to surgery, markers of NO bioavailability increased, and oxidative stress decreased. These findings support that a minimally invasive removal of the inflamed gallbladder countereffects reduced markers of NO bioavailability and increased oxidative stress caused by acute cholecystitis.

Changing Perspectives from Oxidative Stress to Redox Signaling-Extracellular Redox Control in Translational Medicine

Extensive research has changed the understanding of oxidative stress that has been linked to every major disease. Today we distinguish oxidative eu- and distress, acknowledging that redox modifications are crucial for signal transduction in the form of specific thiol switches. Long underestimated, reactive species and redox proteins of the Thioredoxin (Trx) family are indeed essential for physiological processes. Moreover, extracellular redox proteins, low molecular weight thiols and thiol switches affect signal transduction and cell–cell communication. Here, we highlight the impact of extracellular redox regulation for health, intermediate pathophenotypes and disease. Of note, recent advances allow the analysis of redox changes in body fluids without using invasive and expensive techniques. With this new knowledge in redox biochemistry, translational strategies can lead to innovative new preventive and diagnostic tools and treatments in life sciences and medicine.

Effect of Preoperative Administration of Oral Melatonin on Pneumatic Tourniquet-Induced Ischemia-Reperfusion Injury in Orthopedic Surgery of Lower Extremities: A Randomized Clinical Trial

Background

Ischemic reperfusion injury (IRI) causes cellular damage and dysfunction. The present study aimed to evaluate the effect of melatonin on pneumatic tourniquet-induced IRI in orthopedic surgery of the lower extremities.

Methods

A randomized clinical trial was conducted at Chamran Hospital, Shiraz University of Medical Sciences (Shiraz, Iran), from September to November 2019. The target population was patients scheduled for elective orthopedic surgery of the lower extremities. A total of 67 patients were randomly divided into two groups, placebo (n=34) and melatonin (n=33). The groups received 10 mg melatonin or placebo the night before surgery and two hours before surgery. Primary outcome variables were the serum levels of superoxide dismutase (SOD) and malondialdehyde (MDA). Hemodynamic parameters, sedation score, and drug side effects were also evaluated. Data were analyzed using SPSS version 21.0 software. P<0.05 was considered statistically significant.

Results

In the analysis phase, due to loss to follow-up (n=26), 41 patients divided into two groups of melatonin (n=20) and placebo (n=21) were evaluated. There was no significant difference in demographic data, duration of surgery (P=0.929), and tourniquet time (P=0.496) between the groups. The serum levels of SOD and MDA were not significantly different between the groups (P=0.866 and P=0.422, respectively), nor were the incidence of postoperative nausea (P=0.588) and patients' satisfaction (P=0.088). However, the postoperative sedation score and vomiting between the groups were significantly different (P<0.001).

Conclusion

Administration of 10 mg melatonin provided effective sedation, but had no significant effect on the serum levels of SOD and MDA, nor on pneumatic tourniquet-induced IRI in orthopedic surgery of the lower limbs.

Trial registration number

IRCT20141009019470N87.

CoenzymeQ10 and Ischemic Preconditioning Potentially Prevent Tourniquet-Induced Ischemia/Reperfusion in Knee Arthroplasty, but Combined Pretreatment Possibly Neutralizes Their Beneficial Effects

Tourniquet (TQ) use during total knee arthroplasty (TKA) induces ischemia/reperfusion (I/R) injury, resulting in mitochondrial dysfunction. This study aims to determine the effects of coenzyme Q10 (CoQ10) and ischemic preconditioning (IPC), either alone or in combination, on I/R-induced mitochondrial respiration alteration in peripheral blood mononuclear cells (PBMCs) and pain following TKA. Forty-four patients were allocated into four groups: control, CoQ10, IPC, and CoQ10 + IPC. CoQ10 dose was 300 mg/day for 28 days. IPC protocol was three cycles of 5/5-min I/R time. Mitochondrial oxygen consumption rates (OCRs) of PBMCs were measured seven times, at baseline and during ischemic/reperfusion phases, with XFe 96 extracellular flux analyzer. Postoperative pain was assessed for 48 h. CoQ10 improved baseline mitochondrial uncoupling state; however, changes in OCRs during the early phase of I/R were not significantly different from the placebo. Compared to ischemic data, IPC transiently increased basal OCR and ATP production at 2 h after reperfusion. Clinically, CoQ10 significantly decreased pain scores and morphine requirements at 24 h. CoQ10 + IPC abolished analgesic effect of CoQ10 and mitochondrial protection of IPC. In TKA with TQ, IPC enhanced mitochondrial function by a transient increase in basal and ATP-linked respiration, and CoQ10 provides postoperative analgesic effect. Surprisingly, CoQ10 + IPC interferes with beneficial effects of each intervention.

Effect of remote ischaemic preconditioning on mortality and morbidity after non-cardiac surgery: meta-analysis

Background

Remote ischaemic preconditioning (RIPC) has been shown to have a protective role on vital organs exposed to reperfusion injury. The aim of this systematic review was to evaluate the effects of non-invasive RIPC on clinical and biochemical outcomes in patients undergoing non-cardiac surgery

Methods

A systematic literature search of PubMed, EMBASE, Scopus, and Cochrane databases was carried out in February 2020. RCTs investigating the effect of non-invasive RIPC in adults undergoing non-cardiac surgery were included. Meta-analyses and trial sequential analyses (TSAs) were performed on cardiovascular events, acute kidney injury, and short- and long-term mortality.

Results

Some 43 RCTs including 3660 patients were included. The surgical areas comprised orthopaedic, vascular, abdominal, pulmonary, neurological, and urological surgery. Meta-analysis showed RIPC to be associated with fewer cardiovascular events in non-cardiac surgery (13 trials, 1968 patients, 421 events; odds ratio (OR) 0.68, 95 per cent c.i. 0.47 to 0.96; P = 0.03). Meta-analyses of the effect of RIPC on acute kidney injury (12 trials, 1208 patients, 211 events; OR 1.14, 0.78 to 1.69; P = 0.50; I² = 9 per cent), short-term mortality (7 trials, 1239 patients, 65 events; OR 0.65, 0.37 to 1.12; P = 0.12; I² = 0 per cent), and long-term mortality (4 trials, 1167 patients, 9 events; OR 0.67, 0.18 to 2.55; P = 0.56; I² = 0 per cent) showed no significant differences for RIPC compared with standard perioperative care in non-cardiac surgery. However, TSAs showed that the required information sizes have not yet been reached.

Conclusion

Application of RIPC to non-cardiac surgery might reduce cardiovascular events, but not acute kidney injury or all-cause mortality, but currently available data are inadequate to confirm or reject an assumed intervention effect.

Impact of Dexmedetomidine on Tourniquet-Induced Systemic Effects in Total Knee Arthroplasty under Spinal Anesthesia: a Prospective Randomized, Double-Blinded Study

Background

Clinical studies on the impact of dexmedetomidine on tourniquet-induced systemic effects have been inconsistent. We investigated the impact of dexmedetomidine on tourniquet-induced systemic effects in total knee arthroplasty.

Methods

Eighty patients were randomly assigned to either control (CON) or dexmedetomidine (DEX) group. The DEX group received an intravenous loading dose of 0.5 μg/kg DEX over 10 minutes, followed by a continuous infusion of 0.5 μg/kg/h from 10 minutes before the start of surgery until completion. The CON group received the same calculated volume of normal saline. Pain outcomes and metabolic and coagulative changes after tourniquet application and after tourniquet release were investigated.

Results

The frequency of fentanyl administration postoperatively, patient-controlled analgesia (PCA) volume at 24 hours postoperatively, total PCA volume consumed in 48 hours postoperatively, and VAS score for pain at 24 and 48 hours postoperatively were significantly lower in the DEX group than in the CON group. Ten minutes after the tourniquet release, the DEX group showed significantly higher pH and lower lactate level than those in the CON group. Antithrombin III activity and body temperature 10 minutes after tourniquet release were significantly lower in the DEX group than in the CON group. Ca²⁺, K⁺, HCO₃ ^-, base excess, and PCO₂ levels 10 minutes after tourniquet release were not significantly different between the two groups.

Conclusion

We showed that DEX attenuated pain and hemodynamic, metabolic, and coagulative effects induced by the tourniquet. However, these metabolic and coagulative changes were within normal limits. Therefore, DEX could be used as an analgesic adjuvant, but should not be considered for routine use to prevent the systemic effects induced by tourniquet use.

Understanding and Optimizing Tourniquet Use During Extremity Surgery

Tourniquet use during extremity surgery is commonplace and a relatively safe practice. The surgical team's knowledge of the patient history, proper assessment, and indications and contraindications for and risks of tourniquet use can prevent unwanted outcomes. Exploration of these critical areas reinforces perioperative nurses' awareness and understanding of safe tourniquet use. Additionally, a review of the physiological effect of tourniquets on the skin, the body's response to local compression, the risk of vascular compromise, and the effect of the tourniquet on postoperative pain and swelling provides insight into AORN recommended practice guidelines. This article summarizes the indications and assessments for and risks of tourniquet use for patients during extremity surgery. An understanding of these topics can improve surgical outcomes and promote safe perioperative care.

An optimized low-pressure tourniquet murine hind limb ischemia reperfusion model: Inducing acute ischemia reperfusion injury in C57BL/6 wild type mice

Acute ischemia reperfusion injury in skeletal muscle remains an important issue in several fields of regenerative medicine. Thus, a valid model is essential to gain deeper insights into pathophysiological relations and evaluate possible treatment options. While the vascular anatomy of mice regularly prevents sufficient vessel occlusion by invasive methods, there is a multitude of existing models to induce ischemia reperfusion injury without surgical procedures. Since there is no consensus on which model to prefer, this study aims to develop and evaluate a novel, optimized low-pressure tourniquet model. C57BL/6 mice underwent an ischemic procedure by either tourniquet or invasive artery clamping. A sham group served as control. With exception of the sham group, mice underwent 2 hours of ischemia followed by 4 hours of reperfusion. Groups were compared using microcirculatory and spectroscopic measurements, distinctions in tissue edema, histological and immunohistochemical analyses. Both procedures led to a significant decrease in tissue blood flow (- 97% vs. - 86%) and oxygenation (- 87% vs. - 75%) with a superiority of the low-pressure tourniquet. Tissue edema in the tourniquet cohort was significantly increased (+ 59%), while the increase in the clamping cohort was non-significant (+ 7%). Haematoxylin Eosin staining showed significantly more impaired muscle fibers in the tourniquet group (+ 77 p.p. vs. + 11 p.p.) and increased neutrophil infiltration/ROI (+ 51 vs. + 8). Immunofluorescence demonstrated an equal increase of p38 in both groups (7-fold vs. 8-fold), while the increase in apoptotic markers (Caspase-3, 3-Nitrotyrosine, 4-Hydroxynonenal) was significantly higher in the tourniquet group. The low-pressure tourniquet has been proven to produce reproducible and thus reliable ischemia reperfusion injury. In addition, significantly less force was needed than previously stated. It is therefore an important instrument for studying the pathophysiology of ischemia reperfusion injury and for the development of prophylactic as well as therapeutic interventions.

Propofol post-conditioning after temporary clipping reverses oxidative stress in aneurysm surgery

PURPOSE

Animal studies have demonstrated that propofol post-conditioning produces long-term neuroprotection in focal cerebral ischemia-reperfusion injury. However, whether propofol post-conditioning provides neuroprotection in human beings has never been explored. The aim of this study was to evaluate the role of propofol post-conditioning on oxidative stress and post-operative cognitive function following aneurysm clipping.

MATERIALS AND METHODS

Sixty patients undergoing intracranial aneurysm clipping were randomized into a propofol post-conditioning group or a sevoflurane group. Sevoflurane (0.5-2%) was used for maintenance anesthesia in both groups. In the propofol post-conditioning group, the inhaled concentration of sevoflurane was reduced after temporary clip removal to keep the bispectral index (BIS) value between 40 and 60, and propofol (Cp 1.2 µg/mL) was subsequently started. Blood samples were drawn at six time points: before induction, immediately after clip removal, at the end of the operation, 24-h post-surgery, 3 days post-surgery, and 7 days post-surgery. Oxidative stress and cognitive function were measured.

RESULTS

Between the conclusion of the operation to 7 days after surgery, propofol post-conditioning decreased the serum concentration of •OH and 8-isoprostane and increased γ-tocopherol and SOD. Reduced micronuclei and nucleoplasmic bridges were observed in the propofol post-conditioning group. Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores were improved by propofol post-conditioning compared to the group that received no propofol.

CONCLUSIONS

Together, our data suggest that propofol post-conditioning (Cp 1.2 µg/mL) may protect the brain from oxidative stress injury up to 7 days post-surgery after temporary parent artery clipping. Furthermore, the neuroprotection induced by propofol post-conditioning may contribute to improvement in cognitive function.

Effects of Pharmacologic Dose of Resveratrol Supplementation on Oxidative/Antioxidative Status Biomarkers in Nonalcoholic Fatty Liver Disease Patients: A Randomized, Double-Blind, Placebo-Controlled Trial

Purpose: Despite a proposed role for oxidative stress in the pathogenesis of nonalcoholic fatty liver disease (NAFLD), antioxidant approaches have not been sufficiently investigated in human NAFLD management. Resveratrol has been reported to possess a wide range of biological functions, including antioxidant activities. This study aimed to evaluate the effects of resveratrol supplementation on oxidative/anti-oxidative status in patients with NAFLD.

Methods: This randomized, double-blind, placebo-controlled clinical trial was conducted on 60 patients with NAFLD (males and females) aged 20 to 60 years, and body mass index (BMI) of 25-35 kg/m2. Subjects were randomly assigned to receive a daily dose of 600 mg resveratrol (2×300 mg pure trans-resveratrol capsules; n=30) or placebo capsules (n=30) for 12 wk. Fasting blood samples, anthropometric measurements, and dietary intakes were collected for all patients at baseline and at the end of the trial. Oxidative stress was evaluated by measurement of serum malondialdehyde (MDA), oxidized low-density lipoprotein (ox-LDL), total antioxidant capacity (TAC), and erythrocyte superoxide dismutase (SOD) as well as glutathione peroxidase (GSH-Px) activities. Changes in the outcomes were analyzed using analysis of covariance (ANCOVA).

Results: Resveratrol supplementation did not significantly affect neither serum MDA, ox-LDL, and TAC levels, nor erythrocyte SOD and GSH-Px activities, compared to placebo group (All P>0.05). Moreover, changes in serum levels of liver enzymes (ALT, AST, GGT, and ALP) were not significant in neither of the study groups (All P>0.05).

Conclusion: Resveratrol supplementation did not modify oxidative/anti-oxidative status in patients with NAFLD.

Lateral parapatellar and subvastus approaches are superior to the medial parapatellar approach in terms of soft tissue perfusion

PURPOSE

The arthrotomy techniques of knee surgery may cause varying degrees of disruption to the tissue blood supply. The aim of this study was to investigate the effects of the medial parapatellar (MPPa), midvastus (MVa), subvastus (SVa) and lateral parapatellar (LPPa) approaches on regional tissue perfusion of the knee.

METHODS

In this experimental study, a total of 28 female rabbits were applied with four different arthrotomy techniques as Group MPPa, Group MVa, Group SVa and Group LPPa. The blood supply of the tissue around the knee was examined by scintigraphic imaging including the perfusion reserve and T _max, and biochemical alteration of the oxidative stress parameters including malondialdehyde (MDA), fluorescent oxidation products (FlOPs), and histopathological findings were evaluated on tissue samples after 3 weeks.

RESULTS

The perfusion reserve was increased in all four groups compared to the healthy, contralateral knees. In the Group LPPa, the vascularity was significantly increased compared to the Group MPPa (p = 0.006). In the examination of biochemical parameters, the increase in MDA levels was statistically significant in the Group MPPa compared with the Group LPPa (p = 0.004), and in the Group MVa compared with the Group LPPa (p = 0.006). The increase in the value of MDA levels was striking in the Group MPPa and Group MVa compared with the control group (p = 0.004, p = 0.004, respectively). The increase in another oxidative stress parameter, the tissue FlOPs levels, was statistically significant in the Group MPPa compared with the control group (p = 0.035).

CONCLUSION

The LPPa and SVa caused less oxidative stress and less disruption of the muscle blood supply, in biochemical and scintigraphic parameters, compared to the MPPa and MVa. Therefore, in clinical practice, the SVa is preferable to the MPPa and MVa in total knee arthroplasty and the LPPa should be preferred more frequently in selected cases with critical soft tissue viability.

A comparison of the effects of lindane and FeCl3/ADP on spontaneous contractions in isolated rat or human term myometrium

Oxidative stress affects the contractile behavior of smooth muscle resulting in complications during labor. Toxicants such as lindane and ferric chloride (FeCl₃)/adenosine diphosphate (ADP) cause oxidative stress and have previously been shown to inhibit smooth muscle contraction. In this study we examined the effects of the oxygen species scavengers, ascorbic acid and N-acetylcysteine on lindane and FeCl₃/ADP's inhibition of spontaneous myometrial contractions in rat and human myometrium. Lindane and FeCl₃/ADP gave rise to concentration-dependent reductions in rat (EC₅₀ 11.8×10^-6M and 0.9×10^-3M) and human myometrial contractions (EC₅₀ 16.3×10^-6M and 1.1×10^-3M, respectively). Pre-treatment with N-acetylcysteine significantly increased the EC₅₀ for the effects of lindane on motility index of human tissue and reduced the maximum inhibitory effect of FeCl₃/ADP on contractions in both rat and human myometrium. Ascorbic acid reduced the effects of FeCl₃/ADP in rat tissue only. In conclusion pre-treatment with specific antioxidants may protect both rat and human myometrium from the inhibitory effects of lindane and FeCl₃/ADP.

Hypoxic Air Inhalation and Ischemia Interventions Both Elicit Preconditioning Which Attenuate Subsequent Cellular Stress In vivo Following Blood Flow Occlusion and Reperfusion

Ischemic preconditioning (IPC) is valid technique which elicits reductions in femoral blood flow occlusion mediated reperfusion stress (oxidative stress, Hsp gene transcripts) within the systemic blood circulation and/or skeletal muscle. It is unknown whether systemic hypoxia, evoked by hypoxic preconditioning (HPC) has efficacy in priming the heat shock protein (Hsp) system thus reducing reperfusion stress following blood flow occlusion, in the same manner as IPC. The comparison between IPC and HPC being relevant as a preconditioning strategy prior to orthopedic surgery. In an independent group design, 18 healthy men were exposed to 40 min of (1) passive whole-body HPC (FiO₂ = 0.143; no ischemia. N = 6), (2) IPC (FiO₂ = 0.209; four bouts of 5 min ischemia and 5 min reperfusion. n = 6), or (3) rest (FiO₂ = 0.209; no ischemia. n = 6). The interventions were administered 1 h prior to 30 min of tourniquet derived femoral blood flow occlusion and were followed by 2 h subsequent reperfusion. Systemic blood samples were taken pre- and post-intervention. Systemic blood and gastrocnemius skeletal muscle samples were obtained pre-, 15 min post- (15PoT) and 120 min (120PoT) post-tourniquet deflation. To determine the cellular stress response gastrocnemius and leukocyte Hsp72 mRNA and Hsp32 mRNA gene transcripts were determined by RT-qPCR. The plasma oxidative stress response (protein carbonyl, reduced glutathione/oxidized glutathione ratio) was measured utilizing commercially available kits. In comparison to control, at 15PoT a significant difference in gastrocnemius Hsp72 mRNA was seen in HPC (−1.93-fold; p = 0.007) and IPC (−1.97-fold; p = 0.006). No significant differences were observed in gastrocnemius Hsp32 and Hsp72 mRNA, leukocyte Hsp72 and Hsp32 mRNA, or oxidative stress markers (p > 0.05) between HPC and IPC. HPC provided near identical amelioration of blood flow occlusion mediated gastrocnemius stress response (Hsp72 mRNA), compared to an established IPC protocol. This was seen independent of changes in systemic oxidative stress, which likely explains the absence of change in Hsp32 mRNA transcripts within leukocytes and the gastrocnemius. Both the established IPC and novel HPC interventions facilitate a priming of the skeletal muscle, but not leukocyte, Hsp system prior to femoral blood flow occlusion. This response demonstrates a localized tissue specific adaptation which may ameliorate reperfusion stress.

Skeletal muscle ischemia-reperfusion injury and cyclosporine A in the aging rat

Old patients exhibit muscle impairments and increased perioperative risk during vascular surgery procedures. Although aging generally impairs protective mechanisms, data are lacking concerning skeletal muscle in elderly. We tested whether cyclosporine A (CsA), which protects skeletal muscle from ischemia-reperfusion (IR) in young rats, might reduce skeletal muscle mitochondrial dysfunction and oxidative stress in aging rats submitted to hindlimb IR. Wistar rats aged 71-73 weeks were randomized to IR (3 h unilateral tourniquet application and 2 h reperfusion) or IR + CsA (10 mg/kg cyclosporine IV before reperfusion). Maximal oxidative capacity (VM ax ), acceptor control ratio (ACR), and relative contribution of the mitochondrial respiratory chain complexes II, III, IV (VS ucc ), and IV (VTMPD /Asc ), together with calcium retention capacity (CRC) a marker of apoptosis, and tissue reactive oxygen species (ROS) production were determined in gastrocnemius muscles from both hindlimbs. Compared to the nonischemic hindlimb, IR significantly reduced mitochondrial coupling, VMax (from 7.34 ± 1.50 to 2.87 ± 1.22 μMO2 /min/g; P < 0.05; -70%), and VS ucc (from 6.14 ± 1.07 to 3.82 ± 0.83 μMO2 /min/g; P < 0.05; -42%) but not VTMPD /Asc . IR also decreased the CRC from 15.58 ± 3.85 to 6.19 ± 0.86 μMCa(2+) /min/g; P < 0.05; -42%). These alterations were not corrected by CsA (-77%, -49%, and -32% after IR for VM ax, VS ucc , and CRC, respectively). Further, CsA significantly increased ROS production in both hindlimbs (P < 0.05; +73%). In old rats, hindlimb IR impairs skeletal muscle mitochondrial function and increases oxidative stress. Cyclosporine A did not show protective effects.

The effect of iloprost and N-acetylcysteine on skeletal muscle injury in an acute aortic ischemia-reperfusion model: an experimental study

Objective. The objective of this study was to examine the effects of iloprost and N-acetylcysteine (NAC) on ischemia-reperfusion (IR) injuries to the gastrocnemius muscle, following the occlusion-reperfusion period in the abdominal aorta of rats. Materials and Methods. Forty male Sprague-Dawley rats were randomly divided into four equal groups. Group 1: control group. Group 2 (IR): aorta was occluded. The clamp was removed after 1 hour of ischemia. Blood samples and muscle tissue specimens were collected following a 2-hour reperfusion period. Group 3 (IR + iloprost): during a 1-hour ischemia period, iloprost infusion was initiated from the jugular catheter. During a 2-hour reperfusion period, the iloprost infusion continued. Group 4 (IR + NAC): similar to the iloprost group. Findings. The mean total oxidant status, CK, and LDH levels were highest in Group 2 and lowest in Group 1. The levels of these parameters in Group 3 and Group 4 were lower compared to Group 2 and higher compared to Group 1 (P < 0.05). The histopathological examination showed that Group 3 and Group 4, compared to Group 2, had preserved appearance with respect to hemorrhage, necrosis, loss of nuclei, infiltration, and similar parameters. Conclusion. Iloprost and NAC are effective against ischemia-reperfusion injury and decrease ischemia-related tissue injury.

Effects of Silybum marianum (L.) Gaertn. (silymarin) extract supplementation on antioxidant status and hs-CRP in patients with type 2 diabetes mellitus: a randomized, triple-blind, placebo-controlled clinical trial

AIM

Diabetes is a serious metabolic disorder and oxidative stress and inflammation contribute to its pathogenesis and complications. Since Silybum marianum (L.) Gaertn. (silymarin) extract is an antioxidant with anti-inflammatory properties, this randomized clinical trial was conducted to evaluate the effects of silymarin supplementation on oxidative stress indices and hs-CRP in type 2 diabetes mellitus patients.

METHODS

For the present paralleled, randomized, triple-blinded, placebo-controlled clinical trial, 40 type 2 diabetes patients aged 25-50 yr old and on stable medication were recruited from the Iranian Diabetes Society and endocrinology clinics in East Azarbayjan (Tabriz, Iran) and randomly assigned into two groups. Patients in the silymarin treatment group received 140 mg, thrice daily of dried extracts of Silybum marianum (n = 20) and those in the placebo group (n = 20) received identical placebos for 45 days. Data pertaining to height, weight, waist circumference and BMI, as well as food consumption, were collected at base line and at the conclusion of the study. Fasting blood samples were obtained and antioxidant indices and hs-CRP were assessed at baseline, as well as at the end of the trial.

RESULTS

All 40 patients completed the study and did not report any adverse effects or symptoms with the silymarin supplementation. Silymarin supplementation significantly increased superoxide dismutase (SOD), glutathione peroxidase (GPX) activity and total antioxidant capacity (TAC) compared to patients taking the placebo, by 12.85%, 30.32% and 8.43%, respectively (p < 0.05). There was a significant reduction in hs-CRP levels by 26.83% (p < 0.05) in the silymarin group compared to the placebo group. Malondialdehyde (MDA) concentration significantly decreased by 12.01% (p < 0.05) in the silymarin group compared to the baseline.

CONCLUSIONS

Silymarin supplementation improves some antioxidant indices (SOD, GPX and TAC) and decrease hs-CRP levels in T2DM patients.

Ischaemic conditioning strategies for the nephrologist: a promise lost in translation?

Over the last quarter of a century, a huge effort has been made to develop interventions that can minimise ischaemia reperfusion injury. The most potent of these are the ischaemic conditioning strategies, which comprise ischaemic preconditioning, remote ischaemic preconditioning and ischaemic postconditioning. While much of the focus for these interventions has been on protecting the myocardium, other organs including the kidney can be similarly protected. However, translation of these beneficial effects from animal models into routine clinical practice has been less straightforward than expected. In this review, we examine the role of ischaemic conditioning strategies in reducing tissue injury from the 'bench to the bedside' and discuss the barriers to their greater translation.

Propofol sedation in total knee replacement : effects on oxidative stress and ischemia-reperfusion damage

PURPOSE

This study aimed to show the effect of propofol sedation on oxidative stress and inflammation resulting from ischemia-reperfusion.

METHODS

After having obtained written informed consent from the patients and ethics committee approval, 36 patients were randomly allocated to 2 groups: group C, control and group P, propofol. Spinal anesthesia was administered to both groups with 15 mg bupivacaine. Patients in group P received a propofol infusion of 2 mg/kgBW/h and the patients in group C received a placebo infusion in an equal dose. Malondialdehyde (MDA), superoxide dismutase (SOD) and the total antioxidative capacity (TAC) levels were measured in venous blood samples prior to propofol or placebo administration (preischemia T0), 30 min after placing the tourniquet (ischemia T1) and 2 h after deflation of the tourniquet (reperfusion T2). High sensitivity C-reactive protein (hsCRP) and neutrophil levels were measured before propofol was administered (T0) and 12 h after reperfusion (T3).

RESULTS

While serum MDA and SOD levels were significantly higher during the reperfusion period than the preischemic period, TAC levels were found to be low in the control group (p < 0.05). In the propofol group there were no differences between the preischemia-reperfusion periods with respect to MDA, SOD and TAC levels (p > 0.05). The neutrophil and hsCRP levels were observed to be increased to a lesser extent in the propofol group compared to the control group (p < 0.05).

CONCLUSIONS

Propofol infusion in addition to spinal anesthesia may reduce oxidative damage and the inflammatory response developing due to the tourniquet in total knee replacement surgery.

Effect of N-acetyl cysteine on enterocyte apoptosis and intracellular signalling pathways' response to oxidative stress in weaned piglets

N-acetyl cysteine (NAC) has been widely used for preventing reactive oxygen species-induced damage. However, little is known as to whether dietary NAC supplementation would alleviate intestinal injury in weaned piglets. The present study evaluated the effect of NAC on enterocyte apoptosis and intracellular signalling pathways' response to weaning stress. The control piglets were normally suckling, and piglets in the weaning and NAC groups were fed the basal diet and basal+NAC diet from 14 to 25 d of age, respectively. Compared with the control piglets, weaning increased cortisol concentrations (P< 0·05), decreased superoxide dismutase and glutathione peroxidase activities (P< 0·05), increased malondialdehyde content (P< 0·05) in serum and enhanced enterocyte apoptosis index (AI) and concentrations of caspase-3, caspase-8 and caspase-9 (P< 0·05). Gene expression analyses indicated that weaning induced apoptosis via Fas signalling and mitochondrial pathways in weaned piglets. Dietary NAC supplementation decreased (P< 0·05) cortisol concentrations and the AI, increased (P< 0·05) antioxidant status in serum and alleviated histopathological changes in the intestine. It also inhibited Fas, caspase-3, caspase-8 and integrin αvβ6 (αvβ6) gene expressions in the NAC-treated piglets. However, no significant decrease (P>0·10) in caspase-3, caspase-8 and caspase-9 concentrations was observed in the NAC group compared with the weaning group. In conclusion, weaning may induce enterocyte apoptosis via the activation of Fas-dependent and mitochondria-dependent apoptosis. Although NAC had no effect on caspase concentrations, it was clearly beneficial for preserving morphological integrity in weaned piglets via the regulation of cell apoptosis and the inhibition of Fas-dependent apoptosis and αvβ6 expression.

Tourniquet use does not affect rehabilitation, return to activities, and muscle damage after arthroscopic meniscectomy: a prospective randomized clinical study

PURPOSE

The purpose of this prospective randomized trial was to examine the effect of tourniquet use on rehabilitation rate, return to work and sport activities, and muscle damage after arthroscopic meniscectomy.

METHODS

Eighty patients who underwent arthroscopic partial meniscectomy were randomly allocated to the use of an inflated (group A, n = 40) or deflated (group B, n = 40) pneumatic tourniquet. Patients with concomitant ligamentous deficiency or grade III and IV chondral lesions were excluded. The primary outcome measures were pain, measured with a visual analog scale (VAS), and knee range of motion (ROM) on days 8 and 15 postoperatively; time required for patients to discontinue the use of crutches; time to return to light activities and moderate sporting activities such as jogging; and serum creatine phosphokinase (CPK) levels monitored preoperatively and on days 1, 8, and 15 postoperatively.

RESULTS

The 2 groups did not differ in terms of age; male-female ratio; body mass index; and preoperative International Knee Documentation Committee, Tegner, and Lysholm scores. Operative time was not significantly different between groups (mean, 27.5 for group A and 31.2 for group B; P = .83). VAS pain scores and knee ROM were not significant between groups (minimum P = .22). The patients progressed to weight-bearing without crutches within 13.4 and 12.9 days for groups A and B, respectively (P = .9). Return to work and jogging did not differ significantly between groups (minimum P = .34). Serum CPK values were also not significantly different between or within groups during consecutive measurements (P = .3). Tourniquet time did not significantly affect postoperative ROM, VAS pain scores, or serum CPK levels (minimum P = .14).

CONCLUSIONS

Tourniquet use for less than 30 minutes during arthroscopic meniscectomy does not affect postoperative pain or return to light work and jogging. In addition, tourniquet-induced muscle damage after arthroscopic meniscectomy, though potentially present locally, is not detectable in the systemic circulation.

LEVEL OF EVIDENCE

Level I, prospective randomized trial.

Different oxidative stress marker levels in blood from the operated knee or the antecubital vein in patients undergoing knee surgery: a tourniquet-induced ischemia-reperfusion model

BACKGROUND

In knee surgery a tourniquet is usually applied in order to provide a bloodless surgical field. This study aims to compare, in a tourniquet-induced ischemia-reperfusion model, the glutathione oxidation and lipid peroxidation in two different blood sources: an operated knee drainage tube or the antecubital vein.

METHODS

Thirty-two patients undergoing total knee replacement were studied. We measured reduced glutathione (GSH), oxidized glutathione (GSSG), malondialdehyde (MDA) and other metabolic parameters in the blood from the operated knee (17 patients), or from the antecubital vein (15 patients) before tourniquet inflation (T(0)) and after tourniquet release at different times: 3, 10, and 60 minutes (T(1), T(2), and T(3), respectively).

RESULTS

We have found an early increase of approximately 100% in GSSG and MDA blood levels coinciding with a decrease in GSH levels at T(1)-T(3) in blood from the operated knee. These changes were also observed in blood from the antecubital vein at T(1) and T(2), but at lower levels than in blood from the operated knee.

CONCLUSIONS

There is an intense glutathione oxidation and lipid peroxidation in the operated knee after tourniquet deflation. The surgical drainage is a good source of blood for the determination of biomarkers in a tourniquet-induced ischemia-reperfusion model, because changes are observed more early and it is more direct than another source of systemic blood.