Oxidative stress in lung tissue induced by CO(2) pneumoperitoneum in the rat

Translating genetic findings to epigenetics: identifying the mechanisms associated with aging after high-radiation exposure on earth and in space

Purpose

Exposure to radiation is a health concern within and beyond the Earth's atmosphere for aircrew and astronauts in their respective austere environments. The biological effects of radiation exposure from a multiomics standpoint are relatively unexplored and stand to shed light on tailored monitoring and treatment for those in these career fields. To establish a reference variable for genetic damage, biological age seems to be closely associated with the effect of radiation. Following a genetic-based study, this study explores the epigenetic landscape of radiation exposure along with its associative effects on aging processes.

Methods

We imported the results of the genetics-based study that was a secondary analysis of five publicly available datasets (noted as Data1). The overlap of these genes with new data involving methylation data from two datasets (noted as Data2) following similar secondary analysis procedures is the basis of this study. We performed the standard statistical analysis on these datasets along with supervised and unsupervised learning to create preranked gene lists used for functional analysis in Ingenuity Pathway Analysis (IPA).

Results

There were 664 genes of interest from Data1 and 577 genes from Data2. There were 40 statistically significant methylation probes within 500 base pairs of the gene's transcription start site and 10 probes within 100 base pairs, which are discussed in depth. IPA yielded 21 significant pathways involving metabolism, cellular development, cell death, and diseases. Compared to gold standards for gestational age, we observed relatively low error and standard deviation using newly identified biomarkers.

Conclusion

We have identified 17 methylated genes that exhibited particular interest and potential in future studies. This study suggests that there are common trends in oxidative stress, cell development, and metabolism that indicate an association between aging processes and the effects of ionizing radiation exposure.

Hydromorphone Protects against CO2 Pneumoperitoneum-Induced Lung Injury via Heme Oxygenase-1-Regulated Mitochondrial Dynamics

Various pharmacological agents and protective methods have been shown to reverse pneumoperitoneum-related lung injury, but identifying the best strategy is challenging. Herein, we employed lung tissues and blood samples from C57BL/6 mice with pneumoperitoneum-induced lung injury and blood samples from patients who received laparoscopic gynecological surgery to investigate the therapeutic role of hydromorphone in pneumoperitoneum-induced lung injury along with the underlying mechanism. We found that pretreatment with hydromorphone alleviated lung injury in mice that underwent CO₂ insufflation, decreased the levels of myeloperoxidase (MPO), total oxidant status (TOS), and oxidative stress index (OSI), and increased total antioxidant status (TAS). In addition, after pretreatment with hydromorphone, upregulated HO-1 protein expression, reduced mitochondrial DNA content, and improved mitochondrial morphology and dynamics were observed in mice subjected to pneumoperitoneum. Immunohistochemical staining also verified that hydromorphone could increase the expression of HO-1 in lung tissues in mice subjected to CO₂ pneumoperitoneum. Notably, in mice treated with HO-1-siRNA, the protective effects of hydromorphone against pneumoperitoneum-induced lung injury were abolished, and hydromorphone did not have additional protective effects on mitochondria. Additionally, in clinical patients who received laparoscopic gynecological surgery, pretreatment with hydromorphone resulted in lower serum levels of club cell secretory protein-16 (CC-16) and intercellular adhesion molecule-1 (ICAM-1), a lower prooxidant-antioxidant balance (PAB), and higher heme oxygenase-1 (HO-1) activity than morphine pretreatment. Collectively, our results suggest that hydromorphone protects against CO₂ pneumoperitoneum-induced lung injury via HO-1-regulated mitochondrial dynamics and may be a promising strategy to treat CO₂ pneumoperitoneum-induced lung injury.

Effect of Pneumoperitoneum on Oxidative Stress and Inflammation via the Arginase Pathway in Rats

PURPOSE

Oxidative stress during CO₂ pneumoperitoneum is reported to be associated with decreased bioactivity of nitric oxide (NO). However, the changes in endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), and arginase during CO₂ pneumoperitoneum have not been elucidated.

MATERIALS AND METHODS

Thirty male Sprague-Dawley rats were randomized into three groups. After anesthesia induction, the abdominal cavities of the rats of groups intra-abdominal pressure (IAP)-10 and IAP-20 were insufflated with CO₂ at pressures of 10 mm Hg and 20 mm Hg, respectively, for 2 hours. The rats of group IAP-0 were not insufflated. After deflation, plasma NO was measured, while protein expression levels and activity of eNOS, iNOS, arginase (Arg) I, and Arg II were analyzed with aorta and lung tissue samples.

RESULTS

Plasma nitrite concentration and eNOS expression were significantly suppressed in groups IAP-10 and IAP-20 compared to IAP-0. While expression of iNOS and Arg I were comparable between the three groups, Arg II expression was significantly greater in group IAP-20 than in group IAP-0. Activity of eNOS was significantly lower in groups IAP-10 and IAP-20 than in group IAP-0, while iNOS activity was significantly greater in group IAP-20 than in groups IAP-0 and IAP-10. Arginase activity was significantly greater in group IAP-20 than in groups IAP-0 and IAP-10.

CONCLUSION

The activity of eNOS decreases during CO₂ pneumoperitoneum, while iNOS activity is significantly increased, a change that contributes to increased oxidative stress and inflammation. Moreover, arginase expression and activity is increased during CO₂ pneumoperitoneum, which seems to act inversely to the NO system.

The effects of arginase inhibitor on lung oxidative stress and inflammation caused by pneumoperitoneum in rats

Background

Pneumoperitoneum-induced oxidative stress and organ injury are known to be associated with nitric oxide (NO) inactivation. Because arginase competes with NO synthase (NOS) for a common substrate, L-arginine, arginase inhibition may increase NO bioavailability. Therefore, we evaluated the ability of the arginase inhibitor, 2 (S)-amino-6-boronohexanoic acid (ABH), to attenuate pneumoperitoneum-induced decrease of NO bioavailability and lung injury.

Methods

Thirty rats were randomly divided into the following groups: 1) the PP-ABH group received a subcutaneous injection of ABH (5 mg/kg) 1 h before induction of pneumoperitoneum (insufflation to intraperitoneal pressure of 15 mmHg for 60 min); 2) the PP group received saline by subcutaneous injection 1 h before induction of pneumoperitoneum; and 3) the control group received saline by subcutaneous injection before a sham procedure with no gas insufflation. After desufflation, blood was collected to determine levels of plasma nitrite, NOS, inflammatory cytokines, and malondialdehyde, a marker of oxidative stress. Lung tissue was obtained for histological evaluation.

Results

We found that plasma nitrite levels were lower in the PP group and higher in the PP-ABH group, compared with controls (P <0.01 and P <0.05, respectively). In the PP group, endothelial NOS activity was decreased and inducible NOS activity was increased compared with the PP-ABH and control groups. Malondialdehyde levels increased 3-fold in the PP group and 2-fold in the PP-ABH group compared with controls. Tumor necrosis factor-α, interleukin-6, and interleukin-1ß levels were elevated in the PP group compared to the control group, but the increase in cytokine production was attenuated or blocked in the PP-ABH group. Lung injury scores were 4.8-fold higher in the PP group and 2-fold higher in the PP-ABH group compared with controls (P <0.001 and P <0.01, respectively).

Discussion

Pneumoperitoneum decreases NO bioavailability and increases the inflammation cytokines, resulting in organ injuries. Inhibition of arginase activity could maintain NO bioavailability by attenuating pneumoperitoneum-induced changes in NOS activity. In addition, arginase inhibition attenuated the oxidative stress and inflammation and decreased the severity of lung injury caused by pneumoperitoneum.

Conclusions

By increasing NO bioavailability and suppressing oxidative stress and inflammation, pretreatment with an arginase inhibitor may protect against lung injury caused by pneumoperitoneum.

The Effect of Carbon Dioxide Insufflation Applied at Different Pressures and Periods on Thrombotic Factors

The aim of this experimantal study which is applied on rats, is to determine the differences on the clotting factors over the application of low and high intraabdominal pressure (IAP) values in different periods of time in carbon dioxide (CO2) pneumoperitoneum. Thirty rats were randomized into five groups (n = 6): a control group (Group K) and 1 h and 6 mm Hg IAP (Group A), 2 h and 6 mm Hg IAP (Group B), 1 h and 12 mm Hg IAP (Group C) and 2 h and 12 mm Hg IAP were created with CO2 pneumoperitoneum (Group D). At the end of the experiment, plasma samples taken from subjects and fibrinogen, FII (prothrombin), FV, FVII, FVIII, FIX, FX, FXI, FXII, von willebrand's factor (vWF), ristocetin cofactor, protein C, protein S, antithrombin III (AT III) levels are studied. There were statistically significant differences in the mean levels of FII, FV, FVII, FVIII, FIX, FX, FXI, FXII, and protein S between the groups. A hypercoagulable state occurred with the following: increase in the coagulation parameters compared to the control group; increase in FVII in the group only Group C; decrease in AT III in all groups compared to the control group; decrease in protein C in the group only XII Group D compared to control group; decrease in protein S in all groups except group D compared to control group. CO2 insufflation predisposes to thromboembolic events both by inducing coagulation factors and by suppressing the fibrinolytic system contrary to the controversies in the literature.

Evidence for negative effects of elevated intra-abdominal pressure on pulmonary mechanics and oxidative stress

OBJECTIVE

To compare the effects of pneumoperitoneum on lung mechanics, end-tidal CO2 (ETCO2), arterial blood gases (ABG), and oxidative stress markers in blood and bronchoalveolar lavage fluid (BALF) during laparoscopic cholecystectomy (LC) by using lung-protective ventilation strategy.

MATERIALS AND METHODS

Forty-six patients undergoing LC and abdominal wall hernia (AWH) surgery were assigned into 2 groups. Measurements and blood samples were obtained before, during pneumoperitoneum, and at the end of surgery. BALF samples were obtained after anesthesia induction and at the end of surgery.

RESULTS

Peak inspiratory pressure, ETCO2, and pCO2 values at the 30th minute were significantly increased, while there was a significant decrease in dynamic lung compliance, pH, and pO2 values in LC group. In BALF samples, total oxidant status (TOS), arylesterase, paraoxonase, and malondialdehyde levels were significantly increased; the glutathione peroxidase levels were significantly decreased in LC group. The serum levels of TOS and paraoxonase were significantly higher at the end of surgery in LC group. In addition, arylesterase level in the 30th minute was increased compared to baseline. Serum paraoxonase level at the end of surgery was significantly increased when compared to AWH group.

CONCLUSIONS

Our study showed negative effects of pneumoperitoneum in both lung and systemic levels despite lung-protective ventilation strategy.

Selected oxidative stress markers in gynecological laparoscopy

INTRODUCTION

The surgical stress response after laparoscopy is smaller when compared with open surgery, and it is expected that after minimally invasive surgery the possible development of oxidative stress will be less severe.

AIM

To evaluate markers of pro-oxidant activity - levels of lipid peroxides and malondialdehyde - and activity of the antioxidant enzymes superoxide dismutase and glutathione peroxidase in the perioperative period in patients undergoing gynecological laparoscopy and to determine whether the duration of laparoscopy can affect these changes.

MATERIAL AND METHODS

The study included 64 patients, divided into two groups: group 1 with duration of laparoscopy up to 20 min, and group 2 with duration of the operation over 40 min. Blood samples were collected before anesthesia, 5 min after release of pneumoperitoneum, and 10 h after surgery.

RESULTS

A statistically significant increase in the levels of lipid peroxides and malondialdehyde in samples collected after surgery was found in comparison with values obtained before surgery. Also statistically significant differences existed between groups of patients with different duration of surgery. Superoxide dismutase and glutathione peroxidase activity values were significantly decreased. They were also significantly different between the two groups with different duration of surgery.

CONCLUSIONS

In our study, levels of the markers of pro-oxidant activity increased and levels of the markers of antioxidant enzymes decreased, suggesting development of oxidative stress. The duration of laparoscopic procedures affects the severity of the presented changes.

Aprotinin reduces oxidative stress induced by pneumoperitoneum in rats

BACKGROUND

Ischemia-reperfusion injury induced by pneumoperitoneum is a well-studied entity, which increases oxidative stress during laparoscopic operations. The reported anti-inflammatory action of aprotinin was measured in a pneumoperitoneum model in rats for the first time in this study.

MATERIALS AND METHODS

A total of 60 male Albino Wistar rats were used in our protocol. Prolonged pneumoperitoneum (4 h) was applied, causing splanchnic ischemia and a period of reperfusion with a duration of 60 or 180 min followed. Several cytokines and markers of oxidative stress were measured in liver, small intestine, and lungs to compare the aprotinin group with the control group. Tissue inflammation was also evaluated and compared between groups using a five-scaled histopathologic score.

RESULTS

In aprotinin group values of biochemical markers (tumor necrosis factor α, interleukin 6, endothelin 1, C reactive protein, pro-oxidant-antioxidant balance, and carbonyl proteins) were lower in all tissues studied. Statistical significance was greater in liver and lungs (P < 0.05). Histopathologic examination revealed significant difference between control and aprotinin groups in all tissues examined. Aprotinin groups showed mild to moderate lesions, while in control groups severe to very severe inflammation was present. Aprotinin subgroup with prolonged reperfusion period (180 min) showed milder lesions in all tissues than the rest of the groups.

CONCLUSIONS

Aprotinin reduced inflammatory response and oxidative stress induced by pneumoperitoneum in liver, small intestine, and lungs.

Effects of different pressure levels of CO2 pneumoperitoneum on liver regeneration after liver resection in a rat model

BACKGROUND

A recent study demonstrated that high pressure of carbon dioxide (CO2) pneumoperitoneum before liver resection impairs postoperative liver regeneration. This study was aimed to investigate effects of varying insufflation pressures of CO2 pneumoperitoneum on liver regeneration using a rat model.

METHODS

180 male Wistar rats were randomly divided into three groups: control group (without preoperative pneumoperitoneum), low-pressure group (with preoperative pneumoperitoneum at 5 mmHg), and high-pressure group (with preoperative pneumoperitoneum at 10 mmHg). After pneumoperitoneum, all rats were subjected to 70% partial hepatic resection and then euthanized at 0 min, 12 h, and on postoperative days (PODs) 1, 2, 4, and 7. Following outcome parameters were used: liver regeneration (liver regeneration rate, mitotic count, Ki-67 labeling index), hepatocellular damage (serum aminotransferases), oxidative stress [serum malondialdehyde (MDA)], interleukin-6 (IL-6), and hepatocyte growth factor (HGF) expression in the liver tissue.

RESULTS

No significant differences were observed for all parameters between control and low-pressure groups. The liver regeneration rate and mitotic count were significantly decreased in the high-pressure group than in control and low-pressure groups on PODs 2 and 4. Postoperative hepatocellular damage was significantly greater in the high-pressure group on PODs 1, 2, 4, and 7 compared with control and/or low-pressure groups. Serum MDA levels were significantly higher in the high-pressure group on PODs 1 and 2, and serum IL-6 levels were significantly higher in the high-pressure group at 12 h and on POD 1, compared with control and/or low-pressure groups. The HGF tissue expression was significantly lower in the high-pressure group at 12 h and on PODs 1 and 4, compared with that in control and/or low-pressure groups.

CONCLUSIONS

High-pressure pneumoperitoneum before 70% liver resection impairs postoperative liver regeneration, but low-pressure pneumoperitoneum has no adverse effects. This study suggests that following laparoscopic liver resection using appropriate pneumoperitoneum pressure, no impairment of liver regeneration occurs.

Use of dexmedetomidine to prevent pulmonary injury after pneumoperitoneum in ventilated rats

PURPOSE

This study examined the effectiveness of dexmedetomidine in preventing lung injury resulting from pneumoperitoneum in a ventilated rat model.

METHODS

Animals (n=18) were allocated randomly into 3 groups: control group, no pneumoperitoneum; sham group, pneumoperitoneum with intra-abdominal pressure of 12 mm Hg for 60 minutes; and dexmedetomidine group, dexmedetomidine administration 30 minutes before pneumoperitoneum. The rats were rested for 30 minutes after abdominal deflation. Then, blood samples were obtained for plasma malondialdehyde and ischemia-modified albumin (IMA) analyses. Tissue samples were taken for histopathologic examination and malondialdehyde analysis.

RESULTS

Compared with the control group, the sham group had a significantly higher level of plasma IMA. Pretreatment with dexmedetomidine significantly reduced the IMA level. Histopathologically, tissues from sham rats exhibited moderate or severe tissue damage, compared with control tissues. Dexmedetomidine-treated rats showed significantly less tissue damage than sham rats.

CONCLUSIONS

Dexmedetomidine prophylaxis resulted in significantly less IMA production and significantly less neutrophil infiltration, thereby helping to protect the lungs from injury after pneumoperitoneum.

Minimally invasive surgery and oxidative stress response: what have we learned from animal studies?

Oxidative stress (OS) is an integral part of the surgical stress response. Minimally invasive surgery causes less trauma, and thus attenuated stress response is anticipated. However, the pneumoperitoneum or pneumoretroperitoneum is implicated in free radical production. This study reviewed available data on the impact of minimally invasive surgery on OS response of animal models in a systematic way. Databases were searched up to and including January 2010. Most of the studies investigated the effect of pneumoperitoneum on OS, 3 studies investigated the effect of pneumoretroperitoneum on OS. There was a great heterogeneity on experimental conditions including animal models, measured OS markers, methods, and time periods of measurement. Published animal data do not allow a reliable conclusion on the effect of minimally invasive surgery on OS because of the great heterogeneity of experimental conditions. Besides, most studies focus on the effect of pneumoperitoneum, without taking into consideration the effect of less surgical trauma.

The oxidative effect of prolonged CO(2) pneumoperitoneum a comparative study in rats

BACKGROUND

The current study evaluated the effect of time in the severity of the oxidative stress due to pneumoperitoneum.

METHODS

Forty Wistar rats were allocated randomly into 2 groups. The 1 h pneumoperitoneum (Pp) group, which was subjected to 60 min of pneumoperitoneum, and the 3 h Pp, to pneumoperitoneum for 180 min. The animals were divided in half. One half of the rats were left resting for 30 min after abdominal desufflation and the other for 8 h. After these two time periods, blood, liver, kidney, lung and small intestine were obtained for biochemical analysis and histopathological examination.

RESULTS

In the 3 h Pp, the associated oxidative stress was increased. There was an overt increase in blood and tissue MDA and blood PAB values. The MPO values were significantly higher in the 3 h Pp group in serum, kidneys, and intestine during the early phase of reperfusion and in liver after 8 h of reperfusion. These changes occurred in the presence of light microscopic evidence of greater tissue damage for the 3 h Pp, which were consistent with the fluctuation of the MPO values.

CONCLUSION

In our experimental model, we proved biochemically and histologically that time of maintenance of pneumoperitoneum is an additive factor that could cause increased oxidative stress in laparoscopic procedures.

Effects of carbon dioxide pneumoperitoneum on hepatic and renal morphology of rats after segmental colectomy and colonic anastomosis

PURPOSE

To evaluate the effects of increased intraperitoneal pressure caused by carbon dioxide pneumoperitoneum on the hepatic and renal morphology of rats.

METHODS

Fifty-four adult male rats were randomly divided into three groups (P, PP and C) after anesthesia: P - in 18 animals, pneumoperitoneum was established for 30 minutes immediately before laparotomy; PP - in 18 animals, pneumoperitoneum was established for 60 minutes divided into 30 immediately before laparotomy and 30 after abdominal closure; control group (C) - 18 animals underwent laparotomy without pneumoperitoneum induction. The pneumoperitoneum was maintained at a pressure of 5 mm Hg. Nine animals in each group were killed on the 3(rd) and 7(th) postoperative days, when kidney and liver samples were collected for morphological analysis. The liver specimens were stained with hematoxylin and eosin (HE), and the kidney specimens, with HE and von Kossa. Blinded examiners analyzed the slides.

RESULTS

No changes in renal morphology were found. Liver samples showed histological signs of degeneration in animals in the pneumoperitoneum groups killed on the 7(th) postoperative day (p=0.029).

CONCLUSION

The CO(2) pneumoperitoneum did not affect renal morphology but caused hydropic degeneration in the liver of animals killed on the 7(th) postoperative day.

Increased oxidative stress and gut ischemia caused by prolonged pneumoperitoneum in patients undergoing robot-assisted laparoscopic radical prostatectomy

OBJECTIVE

To investigate changes in plasma oxidative stress markers associated with prolonged pneumoperitoneum during robot-assisted laparoscopic radical prostatectomy (RALP).

METHODS

In all, patients of ASA Physical Status II-III who intended to undergo RALP were enrolled in the study. Arterial plasma levels of malondialdehyde (MDA) and intramucosal pH were measured 1 minute before and at 1 hour, 2 hours, 3 hours, and 4 hours after the introduction of pneumoperitoneum at an insufflation pressure of 15 mmHg; likewise, they were again measured every 10 minutes after deflation for 60 minutes, at 2 hours and 12 hours after deflation.

RESULTS

The mean duration of pneumoperitoneum was around 4 hours. After induction of pneumoperitoneum, the MDA concentrations were significantly elevated at various time points as compared with the preinsufflation value. Significant increase of MDA value was noted also 30 minutes after deflation as compared with the pre-deflation levels. The intramucosal pH value decreased significantly after CO(2) insufflation compared with the preinsufflation values. It also increased significantly 2 hours after CO(2) deflation as compared with the pre-deflation values.

CONCLUSION

A prolonged pneumoperitoneum in RALP results in decreased splanchnic blood flow. Pneumoperitoneum itself produces oxidative stress, and ischemia-reperfusion model after deflation of pneumoperitoneum produces more oxidative stress.

Carbon dioxide pneumoperitoneum induces anti-inflammatory response and hepatic oxidative stress in young rats with bacterial peritonitis

PURPOSE

The aim of this study was to investigate the effects of carbon dioxide (CO(2)) pneumoperitoneum on the intra-abdominal spread of bacteria, the local and systemic cytokine expression, and oxidant/antioxidant status in young rats with bacterial peritonitis.

METHODS

Young Sprague-Dawley rats, aging 20-27 days and weighing around 50 g, were allocated to six groups of six to nine animals in each. Intra-abdominal infection model was developed by intraperitoneal injection with 1 cc of Escherichia coli (E. coli) (10(8) CFU/mL, ATCC25922 strain) via right lower abdominal wall. Carbon dioxide (CO(2)) pneumoperitoneum was applied to the rats via umbilical pit insufflation with 20 cc CO(2) for 30 min. All survived rats underwent laparotomy and were killed 24 h or 3 days later. Serum levels of CO(2) and CRP were measured. Left lower abdomen peritoneum, peritoneal fluid, mesenteric lymph node of terminal ileum, and liver were taken for bacterial culture. Liver and plasma levels of TNF-α, IL-1β, and IL-6 were examined for the level of local and systemic immunologic response. Oxidant/antioxidant status in liver and plasma were assessed by measuring malondialdehyde (MDA), and reduced to oxidized glutathione ratio (GSH/GSSG).

RESULTS

Carbon dioxide (CO(2)) pneumoperitoneum does not facilitate E. coli dissemination to other intra-abdominal organs in rats with localized E. coli peritonitis. Peritonitis rats that underwent abdominal CO(2) insufflation have insignificantly higher CRP or lower CO(2) levels. Plasma and liver TNF-α, IL-1β concentrations were not significantly different among the four groups, but plasma IL-6 was significantly increased in rats with E. coli peritonitis and CO(2) pneumoperitoneum that were killed 3 days later as compared with that of rats that were killed 24 h later. In rats with E. coli peritonitis, CO(2) pneumoperitoneum was significantly associated with decreased hepatic GSH/GSSG ratio. However, plasma and liver MDA levels were not altered after CO(2) pneumoperitoneum.

CONCLUSIONS

Carbon dioxide (CO(2)) pneumoperitoneum is not associated with E. coli dissemination in the presence of local intra-abdominal infection. CO(2) pneumoperitoneum elicited systemic anti-inflammatory response at a specific time period and decreased hepatic antioxidant status in young rats with E. coli peritonitis.

Prevention of pulmonary complications of pneumoperitoneum in rats

Background

Carbon dioxide (CO₂) pneumoperitoneum facilitates the visualization of abdominal organs during laparoscopic surgery. However, the associated increase in intra-abdominal pressure causes oxidative stress, which contributes to tissue injury.

Objective

We investigated the ability of the antioxidant and anti-inflammatory drug Erdosteine to prevent CO₂ pneumoperitoneum-induced oxidative stress and inflammatory reactions in a rat model.

Methods

Fourteen female adult Wistar albino rats were divided into a control group (Group A, n = 7) and an Erdosteine group (Group B, n = 7). Group A received 0.5 cc/day 0.9% NaCl, and Group B received 10 mg/kg/day Erdosteine was administered by gavage, and maintained for 7 days prior to the operation. During the surgical procedure, the rats were exposed to CO₂ pneumoperitoneum with an intra-abdominal pressure of 15 mmHg for 30 min. The peritoneal gas was then desufflated. The rats were sacrificed following 3 h of insufflation. Their lungs were removed, histologically evaluated, and scored for intra-alveolar hemorrhage, alveolar edema, congestion, and leukocyte infiltration. The results were statistically analyzed. A value of P < 0.05 was considered statistically significant.

Results

Significant differences were detected in intra-alveolar hemorrhage (P < 0.05), congestion (P < 0.001), and leukocyte infiltration (P < 0.001) in Group A compared with Group B. However, the differences in alveolar edema were not statistically significant (P = 0.698).

Conclusions

CO₂ pneumoperitoneum results in oxidative injury to lung tissue, and administration of Erdosteine reduces the severity of pathological changes. Therefore, Erdosteine may be a useful preventive and therapeutic agent for CO₂ pneumoperitoneum-induced oxidative stress in laparoscopic surgery.

Preconditioning is a method that may reduce the negative side-effect of pneumoperitoneum

Increased intra-abdominal pressure during laparoscopy leads to hypoxia due to reduced blood flow. Aim of our study was to investigate whether preconditioning can reduce this negative effect of the pneumoperitoneum. Fifty female Wistar rats were used, divided into 5 groups. I: Sham operation (Sham), II: conventional pneumoperitoneum (PP), III: transvaginal pneumoperitoneum (TV), IV: preconditioning for 2.5 minutes in two cycles (Pre 2.5), V: preconditioning for 5 minutes (Pre 5). Malondialdehyde (MDA), reduced glutathione (GSH), sulfhydrylgroup (SH-) concentrations, superoxide-dismutase (SOD) and mieloperoxidase (MPO) activity, and anti-apoptotic pathway marker p-AKT level and inflammatory cytokine TNF-α were measured. SOD activity and GSH concentration were decreased in PP and TV groups comparing to Sham and preconditioning groups. MPO activity was decreased also in PP and TV groups comparing to the Sham group but in the preconditioning groups it has remained high. MDA concentration in plasma was increased in PP and TV groups comparing to Sham and preconditioning groups. There was no difference in the case of blood MDA and SH-concentrations between groups. Anti-apoptotic pathway marker p-AKT level was decreased in the TV group comparing to the sham and preconditioning groups. TNF-α level was increased in TV and preconditioning groups compared to the sham group. According to the results preconditioning can reduce negative effects of pneumoperitoneum.

Systematic review of oxidative stress associated with pneumoperitoneum

Background

There have been several reports of ischaemic complications after routine laparoscopy. The aim of this review was to investigate the relationship between this oxidative stress and pneumoperitoneum.

Methods

Medline, Medline in-process, The Cochrane Library, PubMed and EMBASE were searched for papers on oxidative stress and pneumoperitoneum, from 1947 to March 2008 with no language restriction or restriction on trial design. Papers that did not investigate pneumoperitoneum as a causative factor, or did not report outcome measures related to oxidative stress, were excluded.

Results

A total of 73 relevant papers were identified: 36 animal studies, 21 human clinical trials, nine case reports, five review articles and two comments. Pneumoperitoneum causes a reduction in splanchnic blood flow, resulting in biochemical evidence of oxidative stress in a pressure- and time-dependent manner. There is evidence that the use of carbon dioxide for insufflation is contributory. Several measures proposed to minimize the oxidative stress have shown promise in animal studies, but few have been evaluated in the clinical setting.

Conclusion

There is an increasing body of evidence, mainly from animal studies, that pneumoperitoneum decreases splanchnic perfusion with resulting oxidative stress. It is now appropriate to investigate the clinical significance of pneumoperitoneum-associated oxidative stress.

The impact of carbon dioxide pneumoperitoneum on liver regeneration after liver resection in a rat model

BACKGROUND

In recent years, laparoscopic hepatic resection is performed by an increasing number of surgeons. Despite many advantages of the laparoscopic procedure, it is unclear whether the pneumoperitoneum affects the postoperative liver regeneration after liver resection. The current study aimed to investigate the influence of a carbon dioxide (CO(2)) pneumoperitoneum on liver regeneration in a rat model.

METHODS

In this study, 60 male Wistar rats were subjected to 70% partial hepatic resection. Of these 60 animals, 30 underwent preoperative pneumoperitoneum at 9 mmHg for 60 min. After hepatic resection, the rats were killed at 12, 24, and 48 h, and on days 4 and 7. The outcome parameters were hepatocellular injury (plasma aminotransferases), oxidative stress (plasma malondialdehyde), interleukin-6 (IL-6), and liver regeneration (mitotic index, KI-67; regenerating liver mass).

RESULTS

The mitotic index was significantly lower in the pneumoperitoneum group than in the group without pneumoperitoneum at all time points (p < 0.05). In the pneumoperitoneum group, KI-67 was significantly lower on day 4 (p < 0.05). The liver regeneration rate was significantly lower for the animals with pneumoperitoneum on days 2 and 4 (p < 0.05). The postoperative hepatocellular injury was significantly greater after pneumoperitoneum at 12, 24, and 48 h (p < 0.05). Plasma malondialdehyde and IL-6 were significantly higher in the pneumoperitoneum group at 24 h and on day 4 (p < 0.05).

CONCLUSION

This study showed that pneumoperitoneum before extended liver resection impaired postoperative liver regeneration. Oxidative stress reaction and hepatocellular damage was markedly higher after pneumoperitoneum. Further investigations, especially with patients that have impaired liver function, are necessary for clinical consequences to be drawn from these results.

Mesna protects splanchnic organs from oxidative stress induced by pneumoperitoneum

BACKGROUND

We investigated the potential beneficial effect of the antioxidant 2-mercaptoethane-sulfonate (mesna) against oxidative stress induced by pneumoperitoneum in splanchnic organs.

METHODS

Wistar rats were subjected to either (a) CO(2) pneumoperitoneum (15 mmHg for 60 min) (group P), (b) pretreatment with mesna (400 mg/kg, p.o.) followed by pneumoperitoneum with a 180 min interval (group MP), (c) sham operation (group S), or (d) administration of mesna only (group M). Forty-five minutes after desufflation (groups P and MP), 60 + 45 min after the induction of anesthesia (group S), or 180 min after mesna administration (group M), tissue specimens were excised from liver, kidneys, jejunum and stomach. Tissue oxidative state was assessed on the basis of glutathione-to-glutathione disulfide ratio, malondialdehyde concentration , and superoxide dismutase activity.

RESULTS

Pneumoperitoneum deteriorated all the oxidative stress markers in the organs studied. Mesna prevented the occurrence of oxidative stress following pneumoperitoneum in all the organs studied. In the absence of pneumoperitoneum, the administration of mesna caused mild enhancement of the oxidative state of liver, stomach, and kidneys compared to sham controls.

CONCLUSIONS

Prophylaxis with mesna prevents oxidative stress induced by pneumoperitoneum in splanchnic organs.

Validation and reduction of the oxidative stress following laparoscopic operations: a prospective randomized controlled study

OBJECTIVE

To validate ischemia-reperfusion mechanism during laparoscopic cholecystectomy, and to assess the reduction of oxidative stress by an intermittent sequential pneumatic compression (ISPC) device.

SUMMARY BACKGROUND

Increased intraperitoneal pressure during laparoscopic operations may lead to decreased cardiac output and visceral perfusion, and possible ischemia-reperfusion effects. Using the ISPC device was shown to improve cardiac output and visceral perfusion during pneumoperitoneum (PP).

METHODS

Twenty patients undergoing elective laparoscopic cholecystectomy were enrolled in a randomized prospective controlled study and divided into 2 groups: 1) study group (10 patients), activation of ISPC together with creation of PP; and 2) control group, without ISPC. Lipid peroxidation and glutathione levels (as indicators of oxidative stress) as well as liver and renal function tests, were measured before and at the end of PP, and again at 30 minutes, 4 hours, and 24 hours afterward, together with hemodynamic and respiratory parameters.

RESULTS

There was no significant difference between both groups concerning liver enzymes and bilirubin, nor in hemodynamic parameters. In the control group, increased lipid peroxide levels were noted 4 hours after PP termination, in comparison to pre-PP levels (590.4-649.2 mmol/L, P = 0.002). In the study group (ISPC), such changes were not inspected. Decreased total glutathione levels were noted in the control group, 30 minutes following CO2 evacuation.

CONCLUSIONS

Our study validates the ischemia-reperfusion mechanism following laparoscopic surgery. The use of an ISPC device decreased the oxidative stress (secondary to relative ischemia-reperfusion insult) following PP, probably due to improved cardiac output and visceral perfusion.

Carbon dioxide suppresses macrophage superoxide anion production independent of extracellular pH and mitochondrial activity

BACKGROUND

Superoxide anions released by activated macrophages during surgery are considered to be responsible for local cellular damage. Application of CO2 pneumoperitoneum during laparoscopy affects superoxide anion release, but the underlying mechanism remains unclear and the data reported are conflicting. We investigated the direct and pH-mediated impact of CO2 and air on macrophage superoxide anion production.

METHODS

Cells of the NR 8383 rat macrophage cell line were incubated for 2 hours in 5% CO2, 100% CO2, and room air or pH 7.4, pH 6.5, and pH 5.5. The extracellular pH was monitored during incubation. At 0, 2, and 6 hours after incubation, the release of superoxide anions was determined fluorometrically. The mitochondrial activity was determined via the conversion of MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] during and after incubation.

RESULTS

Extracellular pH decreased to 6.4 during incubation in a CO2 atmosphere. The release of superoxide anions was significantly reduced immediately after CO2 incubation. It was restored at all other time-points. Decreasing the extracellular pH to 6.5 had no effect on superoxide anion release, whereas acidification of the extracellular milieu to pH 5.5 significantly suppressed subsequent superoxide release. Mitochondrial activity was significantly decreased by CO2 up to 2 hours and by acidic milieu up to 6 hours. Incubation in room air had no effect.

CONCLUSIONS

Incubation in CO2 can directly suppress macrophage superoxide anion production. This effect is of short duration, fully reversible, and not correlated to changes in extracellular pH or mitochondrial activity. Air contamination does not affect macrophage superoxide anion release. We speculate that CO2 pneumoperitoneum could attenuate the intraoperative free radical production by directly inhibiting superoxide anion release of macrophages without long-lasting suppression of macrophages and their capacity to release superoxide anions postoperatively.

gamma-Glutamyl transpeptidase is induced by 4-hydroxynonenal via EpRE/Nrf2 signaling in rat epithelial type II cells

gamma-Glutamyl transpeptidase (GGT) plays key roles in glutathione homeostasis and metabolism of glutathione S-conjugates. Rat GGT is transcribed via five tandemly arranged promoters into seven transcripts. The transcription of mRNA V is controlled by promoter 5. Previously we found that GGT mRNA V-2 was responsible for the induction of GGT in rat alveolar epithelial cells by 4-hydroxynonenal (HNE). In the current study, the underlying mechanism was investigated. Reporter deletion and mutation analysis demonstrated that an electrophile-response element (EpRE) in the proximal region of GGT promoter 5 (GP5) was responsible for the basal- and HNE-induced promoter activity. Gel-shift assays showed an increased binding activity of GP5 EpRE after HNE exposure. The nuclear content of NF-E2-related factor 2 (Nrf2) was significantly increased by HNE. The recruitment of Nrf2 to GP5 EpRE after HNE treatment was demonstrated by supershift and chromatin immunoprecipitation assays. The tissue expression pattern of GGT mRNA V was previously unknown. Using polymerase chain reaction, we found that GGT mRNA V-2 was expressed in many tissues in rat. Taken together, GGT mRNA V-2 is widely expressed in rat tissues and its basal and HNE-induced expression is mediated through EpRE/Nrf2 signaling.

Effect of carbon dioxide pneumoperitoneum on the severity of acute pancreatitis: An experimental study in rats

BACKGROUND

In the management of mild acute biliary pancreatitis, it is generally recommended to perform laparoscopic cholecystectomy after the subsidence of the attack during the same hospital admission. The effect of laparoscopy on abdominal organs has been widely investigated but not in acute pancreatitis. This study used an animal model of mild acute pancreatitis to examine the effects of CO(2) pneumoperitoneum on acute pancreatitis in rats.

METHODS

Mild acute pancreatitis was induced in 30 male Sprague-Dawley rats by surgical ligation of the biliopancreatic duct. After 2 days, animals were assigned to three groups: sham operation (animals were anesthetized for 30 min without undergoing laparotomy), CO(2) pneumoperitoneum (applied for 30 min at a pressure of 12 mmHg), and laparotomy (performed for 30 min, and then the abdomen was closed). Two hours after the surgical procedures, animals were killed and levels of lactate dehydrogenase, aspartate aminotransferase, glucose, urea, hematocrit, and leukocyte count among Ranson's criteria and levels of amylase, lipase, and total bilirubin were measured to determine the severity of acute pancreatitis. Histopathologic examination of the pancreas was done, and malondialdehyde and glutathione levels of the pancreas and lung were determined.

RESULTS

The only significant differences between the groups were in lactate dehydrogenase and aspartate aminotransferase levels, which were significantly higher in the pneumoperitoneum group compared to the sham operation group.

CONCLUSION

CO(2) pneumoperitoneum for 30 min at a pressure of 12 mmHg did not affect the severity of acute pancreatitis induced by ligation of the biliopancreatic duct in rats.

Effects of carbon dioxide pneumoretroperitoneum on free radical formation in remote organs and use of verapamil as an antioxidant

BACKGROUND AND PURPOSE

Pneumoretroperitoneum (Prp) acts as an ischemia/reperfusion (I/R) model. Ischemia/reperfusion (I/R) injury causes production of reactive oxygen species, which affect organs remote from the sites of I/R. The aim of this study was to assess the remote organ changes after Prp and to explore the effects of antioxidants.

MATERIALS AND METHODS

Eighteen adult rabbits were randomized to three groups, each consisting of six rabbits. Group I (control) underwent balloon dissection of the left retroperitoneal space without gas insufflation. In group II (Prp), carbon dioxide at 10 mm Hg was applied for 2 hours after the balloon dissection (ischemia period) and for 1 hour after desufflation (reperfusion period). In group III (Prp + antioxidant), 5 minutes before the experiment, verapamil at 0.2 mg/kg was given intravenously and the same procedure was employed as in group II. Hepatic, pulmonary, opposite kidney, and treated kidney malondialdehyde (MDA) and reduced glutathione (GSH) levels were evaluated to show response to Prp.

RESULTS

Pneumoretroperitoneum exerted oxidative stress on all tissues with an increase of MDA (P < 0.05) and a decrease of GSH (P < 0.05). The verapamil-treated group showed lower values of MDA (P < 0.05) and higher values of GSH (P < 0.05) than group II.

CONCLUSION

Pneumoretroperitoneum increased oxidative stress in all remote organs tested. Verapamil reduced the oxidative stress. We concluded that Prp should be employed carefully in patients with limited vital organ capacity. Verapamil administration may be considered for protection against tissue injury attributable to oxidative stress in these patients.

Role of mitogen-activated protein kinases in 4-hydroxy-2-nonenal-induced actin remodeling and barrier function in endothelial cells

In vivo and in vitro studies indicate that 4-hydroxy-2-nonenal (4-HNE), generated by cellular lipid peroxidation or after oxidative stress, affects endothelial permeability and vascular tone. However, the mechanism(s) of 4-HNE-induced endothelial barrier function is not well defined. Here we provide evidence for the first time on the involvement of mitogen-activated protein kinases (MAPKs) in 4-HNE-mediated actin stress fiber formation and barrier function in lung endothelial cells. Treatment of bovine lung microvascular endothelial cells with hydrogen peroxide (H(2)O(2)), as a model oxidant, resulted in accumulation of 4-HNE as evidenced by the formation of 4-HNE-Michael protein adducts. Exposure of cells to 4-HNE, in a dose- and time-dependent manner, decreased endothelial cell permeability measured as transendothelial electrical resistance. The 4-HNE-induced permeability changes were not because of cytotoxicity or endothelial cell apoptosis, which occurred after prolonged treatment and at higher concentrations of 4-HNE. 4-HNE-induced changes in transendothelial electrical resistance were calcium independent, as 4-HNE did not alter intracellular free calcium levels as compared with H(2)O(2) or diperoxovanadate. Stimulation of quiescent cells with 4-HNE (1-100 microm) resulted in phosphorylation of ERK1/2, JNK, and p38 MAPKs, and actin cytoskeleton remodeling. Furthermore, pretreatment of bovine lung microvascular endothelial cells with PD 98059 (25 microm), an inhibitor of MEK1/2, or SP 600125 (25 microm), an inhibitor of JNK, or SB 202190 (25 microm), an inhibitor of p38 MAPK, partially attenuated 4-HNE-mediated barrier function and cytoskeletal remodeling. These results suggest that the activation of ERK, JNK, and p38 MAP kinases is involved in 4-HNE-mediated actin remodeling and endothelial barrier function.