Limb Ischemic Conditioning Induces Oxidative Stress Followed by a Correlated Increase of HIF-1α in Healthy Volunteers.

BACKGROUND: Local and remote ischemic preconditioning has been used as a protective intervention against ischemia/reperfusion (I/R) damage in several preclinical and clinical studies. However, its physiological mechanisms are not completely known. I/R increases the production of reactive oxygen species, which also serve as messengers for a variety of functions. Hypoxia-inducible factor 1 alpha (HIF-1α) is probably the most important transcription factor mediator of hypoxic signaling. OBJECTIVE: We hypothesized that limb ischemic conditioning (LIC) induces a local oxidative/nitrosative stress and a correlated increase of HIF-1α plasma levels. METHODS: An observational, prospective, and single-center study has been conducted in 27 healthy volunteers. LIC was applied: three cycles (5 min of ischemia followed by 5 min of reperfusion) using an ischemia cuff placed on the upper left arm. Time course of 8-isoprostane, nitrite, and HIF-1α levels was measured in blood plasma. Venous blood was sampled from the left arm before tourniquet inflation (basal) and after LIC: 1 min and 2 hr for 8-isoprostane and nitrite; and 1 min, 2 hr, 8 hr, 24 hr, and 48 hr for HIF-1α. RESULTS: After LIC, we have found an early increase of 8-isoprostane and nitrite. HIF-1α increased at 2 and 8 hr after LIC. We found a direct correlation between HIF-1α and 8-isoprostane and nitrite plasma levels. CONCLUSIONS: We concluded that LIC induces an early oxidative/nitrosative stress in the arm followed by an increase of HIF-1α plasma levels correlated with 8-isoprostane and nitrite levels, possibly as a local response.

Remote Ischemic Preconditioning Decreases Oxidative Lung Damage After Pulmonary Lobectomy: A Single-Center Randomized, Double-Blind, Controlled Trial.

BACKGROUND: During lobectomy in patients with lung cancer, the operated lung is often collapsed and hypoperfused. Ischemia/reperfusion injury may then occur when the lung is re-expanded. We hypothesized that remote ischemic preconditioning (RIPC) would decrease oxidative lung damage and improve gas exchange in the postoperative period. METHODS: We conducted a single-center, randomized, double-blind trial in patients with nonsmall cell lung cancer undergoing elective lung lobectomy. Fifty-three patients were randomized to receive limb RIPC immediately after anesthesia induction (3 cycles: 5 minutes ischemia/5 minutes reperfusion induced by an ischemia cuff applied on the thigh) and/or control therapy without RIPC. Oxidative stress markers were measured in exhaled breath condensate (EBC) and arterial blood immediately after anesthesia induction and before RIPC and surgery (T0, baseline); during operated lung collapse, immediately before resuming two-lung ventilation (TLV) (T1); immediately after resuming TLV (T2); and 120 minutes after resuming TLV (T3). The primary outcome was 8-isoprostane levels in EBC at T1, T2, and T3. Secondary outcomes included the following: NO2+NO3, H2O2 levels, and pH in EBC and in blood (8-isoprostane, NO2+NO3) and pulmonary gas exchange variables (PaO2/FiO2, A-aDO2, a/A ratio, and respiratory index). RESULTS: Patients subjected to RIPC had lower EBC 8-isoprostane levels when compared with controls at T1, T2, and T3 (differences between means and 95% confidence intervals): -15.3 (5.8-24.8), P = .002; -20.0 (5.5-34.5), P = .008; and -10.4 (2.5-18.3), P = .011, respectively. In the RIPC group, EBC NO2+NO3 and H2O2 levels were also lower than in controls at T2 and T1-T3, respectively (all P < .05). Blood levels of 8-isoprostane and NO2+NO3 were lower in the RIPC group at T2 (P < .05). The RIPC group had better PaO2/FiO2 compared with controls at 2 hours, 8 hours, and 24 hours after lobectomy in 95% confidence intervals for differences between means: 78 (10-146), 66 (14-118), and 58 (12-104), respectively. CONCLUSIONS: Limb RIPC decreased EBC 8-isoprostane levels and other oxidative lung injury markers during lung lobectomy. RIPC also improved postoperative gas exchange as measured by PaO2/FiO2 ratio.

A quantitative enzyme-linked immunosorbent assay for quantification of secretory immunoglobulin A in serum.

Secretory immunoglobulin A (SIgA) in serum is possibly the best index of SIgA presence in mucosal secretions in digestive tract and the mirror of its immunologic barrier against many pathogenic aggressions. The measurement of salivary SigA alone may be affected by total salivary secretion and its final concentration in the gland lumen is probably not useful as an appropriate index of mucosal secretions in the digestive tract. The usefulness of the determination of SigA against various epitopes in serum from patients with various autoimmune disease has been demonstrated. The aetiology of many digestive related disorders could be triggered by an alteration of mucose SIgA barrier. The determination of Igs is important for different liver diseases and specifically the SIgA in autoimmune diseases such as rheumatoid arthritis. We developed an easy and efficient immunologic assay to quantify SIgA in serum samples.

Expression of aquaporins 1 and 5 in a model of ventilator-induced lung injury and its relation to tidal volume.

NEW FINDINGS: What is the central question of this study? Although different studies have attempted to find factors that influence the expression of aquaporins (AQPs) in the lung in different situations, to date no research group has explored the expression of AQP1 and AQP5 jointly in rats mechanically ventilated with different tidal volumes in a model of ventilator-induced lung injury. What is the main finding? Mechanical ventilation with a high tidal volume causes lung injury and oedema, increasing lung permeability. In rats ventilated with a high tidal volume, the pulmonary expression of AQP1 decreases. We analysed the expression of aquaporins 1 and 5 and its relation with tidal volume in a model of ventilator-induced lung injury. Forty-two rats were used. Six non-ventilated animals were killed (control group). The remaining rats were ventilated for 2 h with different tidal volumes (group 7ML with 7 ml kg-1 and group 20ML with 20 ml kg-1 ) and a respiratory rate of 90 breaths min-1 . Lung oedema was measured, and the expression of AQP1 and AQP5 was determined by Western immunoblotting and measurement of mRNA. Lung oedema and alveolar-capillary membrane permeability were significantly increased in the animals of group 20ML compared with the control group. Expression of AQP1 was decreased in groups 7ML and 20ML compared with the control group. In conclusion, mechanical ventilation with a high tidal volume causes lung injury and oedema, increasing lung permeability. In rats ventilated with a high tidal volume, the pulmonary expression of AQP1 decreases.

Effects of remote ischemic postconditioning on HIF-1α and other markers in on-pump cardiac surgery.

BACKGROUND: There is a lack of data about the effects of remote ischemic postconditioning (RIPostC) on hypoxia-inducible factor-1α (HIF-1α) plasma levels after on-pump cardiac surgery (OPCS). This study aimed to measure the effects of RIPostC on postoperative HIF-1α plasma levels, cardiac markers and arterial oxygenation in patients undergoing OPCS. METHODS: This single-centre randomized, double blind, controlled trial, enrolled 70 patients (35 control and 35 RIPostC). RIPostC was performed by 3 cycles (5 min of ischemia followed by 5 min of reperfusion) administered in upper arm immediately after the pump period. The primary outcome was to measure HIF-1α plasma levels: before surgery (T0), and 2 h (T1), 8 h (T2), 24 h (T3), 36 h (T4) and 48 h (T5) after RIPostC. As secondary endpoint, Troponin T, CK-MB, CPK plasma levels and PaO2/FiO2 ratio were measured. RESULTS: HIF-1α plasma levels were increased at T1-T3 compared to T0 in both groups (P < 0.001). In the RIPostC group HIF-1α increased compared to the control group: differences between means (95% CI) were 0.034 (0.006-0.06) P = 0.019 at T1; 0.041 (0.013-0.069) P = 0.005 at T2; and 0.021 (0.001-0.042) P = 0.045 at T3. PaO2/FiO2 was higher in the RIPostC group than in the control group: at T3, T4 and T5. Moreover, Troponin T, CK-MB and CPK values decreased in the RIPostC group compared to the control group. CONCLUSIONS: HIF-1α plasma levels increased in control patients during for at least 36 h after OPCS. RIPostC resulted in even higher HIF-1α levels during at least the first 24 h and improved arterial oxygenation and cardiac markers.

Myocardial oxidative stress protection by sevoflurane vs. propofol: a randomised controlled study in patients undergoing off-pump coronary artery bypass graft surgery.

CONTEXT: Myocardial oxidative stress plays an essential role in the pathogenesis of ischaemia-reperfusion injury associated with coronary artery bypass grafting (CABG). Both propofol and volatile anaesthetics have been shown to reduce reactive oxygen species in experimental and clinical studies. MAIN OBJECTIVE: To compare the influence of sevoflurane and propofol on myocardial oxidative stress markers (F2-isoprostanes and nitrates/nitrites) in coronary sinus blood samples from patients undergoing off-pump CABG. DESIGN AND SETTING: Randomised controlled clinical study of patients scheduled for off-pump CABG in a tertiary academic university hospital from June 2007 to August 2009. Forty patients consented to enrolment and were assigned to receive either propofol or sevoflurane. INTERVENTIONS: Upon completion of the proximal anastomosis, a retroplegia cannula was inserted in the coronary sinus to obtain blood samples, according to the study protocol. MAIN OUTCOME MEASURES: Markers of lipoperoxidation (F2-isoprostanes) and nitrosative stress (nitrates/nitrites) were measured in coronary sinus blood samples at three time points: after the end of the proximal anastomosis (T1), after completion of all grafts (T2) and 15 min after revascularisation (T3). RESULTS: Of the 40 recruited patients, 38 fully completed the study. In the sevoflurane group (n = 20), concentrations of oxidative stress markers in the coronary sinus remained almost constant and were significantly lower than those in the propofol group (n = 18) at all time points. F2-isoprostanes concentrations were as follows at T1: sevoflurane group 37.2 ±â€Š27.5 pg ml vs. propofol group 170.7 ±â€Š30.9 pg ml [95% confidence interval (CI) 112.16-155.08, P < 0.0001); at T2: sevoflurane group 31.94 ±â€Š24.6 pg ml vs. propofol group 171.6 ±â€Š29.7 pg ml (95% CI 119.78-159.63, P < 0.0001); and at T3: sevoflurane group 23.8 ±â€Š13.0 pg ml vs. propofol group 43.6 ±â€Š31 pg ml (95% CI 2.87-36.63, P = 0.023). CONCLUSION: In patients undergoing off-pump CABG, sevoflurane showed better antioxidative properties than propofol.

Glutathione oxidation correlates with one-lung ventilation time and PO2/FiO2 ratio during pulmonary lobectomy.

OBJECTIVES: During lung lobectomy, the operated lung completely collapses with simultaneous hypoxic pulmonary vasoconstriction, followed by expansion and reperfusion. Here, we investigated glutathione oxidation and lipoperoxidation in patients undergoing lung lobectomy, during one-lung ventilation (OLV) and after resuming two-lung ventilation (TLV), and examined the relationship with OLV duration. METHODS: We performed a single-centre, observational, prospective study in 32 patients undergoing lung lobectomy. Blood samples were collected at five time-points: T0, pre-operatively; T1, during OLV, 5 minutes before resuming TLV; and T2, T3, and T4, respectively, 5, 60, and 180 minutes after resuming TLV. Samples were tested for reduced glutathione (GSH), oxidized glutathione (GSSG), glutathione redox potential, and malondialdehyde (MDA). RESULTS: GSSG and MDA blood levels increased at T1, and increased further at T2. OLV duration directly correlated with marker levels at T1 and T2. Blood levels of GSH and glutathione redox potential decreased at T1-T3. GSSG, oxidized glutathione/total glutathione ratio, and MDA levels were inversely correlated with arterial blood PO2/FiO2 at T1 and T2. DISCUSSION: During lung lobectomy and OLV, glutathione oxidation, and lipoperoxidation marker blood levels increase, with further increases after resuming TLV. Oxidative stress degree was directly correlated with OLV duration, and inversely correlated with arterial blood PO2/FiO2.

Supplemental perioperative oxygen and the risk of surgical wound infection: a randomized controlled trial.

CONTEXT: Supplemental perioperative oxygen has been variously reported to halve or double the risk of surgical wound infection. OBJECTIVE: To test the hypothesis that supplemental oxygen reduces infection risk in patients following colorectal surgery. DESIGN, SETTING, AND PATIENTS: A double-blind, randomized controlled trial of 300 patients aged 18 to 80 years who underwent elective colorectal surgery in 14 Spanish hospitals from March 1, 2003, to October 31, 2004. Wound infections were diagnosed by blinded investigators using Centers for Disease Control and Prevention criteria. Baseline patient characteristics, anesthetic treatment, and potential confounding factors were recorded. INTERVENTIONS: Patients were randomly assigned to either 30% or 80% fraction of inspired oxygen (FIO2) intraoperatively and for 6 hours after surgery. Anesthetic treatment and antibiotic administration were standardized. MAIN OUTCOME MEASURES: Any surgical site infection (SSI); secondary outcomes included return of bowel function and ability to tolerate solid food, ambulation, suture removal, and duration of hospitalization. RESULTS: A total of 143 patients received 30% perioperative oxygen and 148 received 80% perioperative oxygen. Surgical site infection occurred in 35 patients (24.4%) administered 30% FIO2 and in 22 patients (14.9%) administered 80% FIO2 (P=.04). The risk of SSI was 39% lower in the 80% FIO2 group (relative risk [RR], 0.61; 95% confidence interval [CI], 0.38-0.98) vs the 30% FIO2 group. After adjustment for important covariates, the RR of infection in patients administered supplemental oxygen was 0.46 (95% CI, 0.22-0.95; P = .04). None of the secondary outcomes varied significantly between the 2 treatment groups. CONCLUSIONS: Patients receiving supplemental inspired oxygen had a significant reduction in the risk of wound infection. Supplemental oxygen appears to be an effective intervention to reduce SSI in patients undergoing colon or rectal surgery. Trial Registration ClinicalTrials.gov Identifier: NCT00235456.

Oxidative lung injury correlates with one-lung ventilation time during pulmonary lobectomy: a study of exhaled breath condensate and blood.

OBJECTIVES: During lung lobectomy, the operated lung is collapsed and hypoperfused; oxygen deprivation is accompanied by reactive hypoxic pulmonary vasoconstriction. After lung lobectomy, ischaemia present in the collapsed state is followed by expansion-reperfusion and lung injury attributed to the production of reactive oxygen species. The primary objective of this study was to investigate the time course of several markers of oxidative stress simultaneously in exhaled breath condensate and blood and to determine the relationship between oxidative stress and one-lung ventilation time in patients undergoing lung lobectomy. METHODS: This single-centre, observational, prospective study included 28 patients with non-small-cell lung cancer who underwent lung lobectomy. We measured the levels of hydrogen peroxide, 8-iso-PGF2α, nitrites plus nitrates and pH in exhaled breath condensate (n = 25). The levels of 8-iso-PGF2α and nitrites plus nitrates were also measured in blood (n = 28). Blood samples and exhaled breath condensate samples were collected from all patients at five time points: preoperatively; during one-lung ventilation, immediately before resuming two-lung ventilation; immediately after resuming two-lung ventilation; 60 min after resuming two-lung ventilation and 180 min after resuming two-lung ventilation. RESULTS: Both exhaled breath condensate and blood exhibited significant and simultaneous increases in oxidative-stress markers immediately before two-lung ventilation was resumed. However, all these values underwent larger increases immediately after resuming two-lung ventilation. In both exhaled breath condensate and blood, marker levels significantly and directly correlated with the duration of one-lung ventilation immediately before resuming two-lung ventilation and immediately after resuming two-lung ventilation. Although pH significantly decreased in exhaled breath condensate immediately after resuming two-lung ventilation, these pH values were inversely correlated with the duration of one-lung ventilation. CONCLUSIONS: During lung lobectomy, the operated lung is collapsed and oxidative injury occurs, with the levels of markers of oxidative stress increasing simultaneously in exhaled breath condensate and blood during one-lung ventilation. These increases were larger after resuming two-lung ventilation. Increases immediately before resuming two-lung ventilation and immediately after resuming two-lung ventilation were directly correlated with the duration of one-lung ventilation.

Increased expression of AQP 1 and AQP 5 in rat lungs ventilated with low tidal volume is time dependent.

BACKGROUND AND GOALS: Mechanical ventilation (MV) can induce or worsen pulmonary oedema. Aquaporins (AQPs) facilitate the selective and rapid bi-directional movement of water. Their role in the development and resolution of pulmonary oedema is controversial. Our objectives are to determine if prolonged MV causes lung oedema and changes in the expression of AQP 1 and AQP 5 in rats. METHODS: 25 male Wistar rats were subjected to MV with a tidal volume of 10 ml/kg, during 2 hours (n = 12) and 4 hours (n = 13). Degree of oedema was compared with a group of non-ventilated rats (n = 5). The expression of AQP 1 and AQP 5 were determined by western immunoblotting, measuring the amount of mRNA (previously amplified by RT-PCR) and immunohistochemical staining of AQPs 1 and 5 in lung samples from all groups. RESULTS: Lung oedema and alveolar-capillary membrane permeability did not change during MV. AQP-5 steady state levels in the western blot were increased (p<0.01) at 2 h and 4 h of MV. But in AQP-1 expression these differences were not found. However, the amount of mRNA for AQP-1 was increased at 2 h and 4 h of MV; and for AQP 5 at 4 h of MV. These findings were corroborated by representative immunohistochemical lung samples. CONCLUSION: In lungs from rats ventilated with a low tidal volume the expression of AQP 5 increases gradually with MV duration, but does not cause pulmonary oedema or changes in lung permeability. AQPs may have a protective effect against the oedema induced by MV.

Oxidative stress injury after on-pump cardiac surgery: effects of aortic cross clamp time and type of surgery.

BACKGROUND: Cardiopulmonary bypass (CPB) in on-pump cardiac surgery can have harmful systemic effects, triggered in part by radical oxygen species (ROS) produced by ischemia-reperfusion in the heart and the lung. We determined the relationship between levels of oxidative stress markers (8-isoprostane and nitrites/nitrates) in plasma with aortic cross clamp duration in patients undergoing cardiac surgery with CPB. METHODS: Thirty patients with CPB were studied: 14 with coronary artery bypass graft surgery and 16 with valve surgery. Plasma levels of 8-isoprostane, and nitrites/nitrates were measured over a 24-hour time course: before (T0) and after CPB: 5 minutes (T1), 1 hour (T2), 12 hours (T3), and 24 hours (T4). RESULTS: Plasma levels of 8-isoprostane and nitrites/nitrates increased early after CPB, with a subsequent and progressive decline. Levels of oxidative stress markers in T1-T2 were positively correlated with the aortic cross clamp duration. Aortic cross clamp duration times greater than 50 minutes were correlated with higher oxidative stress levels. There were no significant differences in the levels of oxidative stress markers between surgery types. CONCLUSION: Cardiac surgery with CPB is associated with an early increase of oxidative stress markers in systemic blood. Aortic cross clamp duration is positively correlated with oxidative stress injury.

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.

Hyperoxia during colon surgery is associated with a reduction of xanthine oxidase activity and oxidative stress in colonic mucosa.

BACKGROUND: Gut manipulation during surgery may induce local oxidative stress. Supplemental inspired oxygen increases arterial and tissue oxygen partial pressures. This study examined whether a 0.80 fraction of inspired oxygen (FiO(2)) attenuates the oxidative stress, reducing xanthine oxidase (XO) activity in colonic mucosa as a possible mechanism during colon surgery. METHODS: Twenty-four cancer patients who underwent elective colon resection were randomly assigned to either 0.30 FiO(2) or 0.80 FiO(2) during surgery. Malondialdehyde (MDA) and oxidized glutathione (GSSG) levels were measured in blood plasma. We also determined the enzymatic activities of XO and xanthine dehydrogenase (XDH) in the colonic mucosa after resection of the piece of colon. RESULTS: Oxygen partial pressure in arterial blood was higher in the 0.80 FiO(2) group than in the 0.30 FiO(2) group (P<0.001). MDA and GSSG levels measured in blood plasma as well as MDA measured in colonic mucosa were lower in the 0.80 FiO(2) group than in the 0.30 FiO(2) group. Otherwise, XO enzymatic activity and XO/(XO+XDH) ratio in colonic mucosa were lower in the 0.80 FiO(2) group than in the 0.30 FiO(2) group. CONCLUSIONS: XO may be a major source of reactive oxygen species in patients during colon surgery. Inspiring 0.80 oxygen during colon surgery increases arterial partial pressure and this treatment was associated with reduced XO activity and levels of oxidative stress in colonic mucosa.

Bemiparin improves the total antioxidant status in plasma.

The aim of this work is to test the protective effect of bemiparin (3500 I.U., s.c.) against oxidative stress in plasma from healthy volunteers. We have evaluated the total antioxidant activity in plasma, superoxide dismutase and glutathione peroxidase activities, and oxidized glutathione and malondialdehyde levels, in two groups: treated (n=20) and control (n=15). Blood samples were collected at: basal, 2, 4, 6, 8 and 10 h. Total antioxidant activity and antioxidant enzymes activity were higher in the treated group at 2-6 h. However, oxidized glutathione and malondialdehyde levels were lower in the treated group at same times. The results suggest that bemiparin exerts an early beneficial effect against oxidative stress in plasma.