Laparoscopic Mouse Model Research Articles

Pneumoperitoneum induced mesothelial cell changes in a laparoscopic mouse model

BackgroundCO2 pneumoperitoneum (PP) during laparoscopic surgery, can cause hypoxia and desiccation in the peritoneal mesothelial cell, resulting in a time-dependent retraction and bulging of these cells, an acute inflammatory reaction and enhanced adhesion formation. Since hypoxia is prevented by adding 4% of oxygen (O2) to the CO2 PP, the aim of this study was to evaluate the effect of adding 4% O2 to the CO2 PP on mesothelial cell morphology. MethodsIn a standardized laparoscopic mouse model (n=8 mice per group), a control group with a 30- or 60-min PP with humidified CO2 + 4% of O2 (groups I and II) was compared to a hypoxic group with 30- or 60-min humidified pure CO2 (groups III and IV) and a desiccation group with 60-min of dry CO2 PP (group V). The effect upon the peritoneum morphology was evaluated by scanning electron microscopy (SEM) of abdominal wall peritoneal biopsies. Biopsies, taken immediately (n=4) and 24 hrs (n=4) after surgery, were compared to a group without PP (group VI, n=4). SEM pictures were blindly scored for cell retraction, deletion of microvilli, fibrin deposition, holes in the epithelial layer and visibility of cell borders using a semi-quantitative scoring system. ResultsPP Hypoxia (CO2 PP) has a deleterious effect upon mesothelial morphology, immediately (holes: p= 0.04) and 24 hrs later (cell retraction: p=0.005; total score: p=0.03) . Desiccation has also a deleterious effect immediately (microvilli p=0.0090; fibrin deposition p=0.05) and 24 hrs after surgery (cell retraction: p=0.0036; holes: p=0.0004; microvilli: p< 0.0001, fibrin deposition: p=0.0225; borders: p=0.0007). This deleterious effect increases with duration of CO2 PP, affecting cell retraction (p=0.016), holes (p=0.0441), and the total score (p=0.0488). The addition of 4% of O2 to the CO2 PP failed to reach statistical significance. ConclusionsThese data confirm that CO2 PP and dry gas have a deleterious effect on mesothelial cell morphology. Humidification of the insufflation gas reduces this deleterious effect. The hypothesis of a protective effect of adding O2 failed to reach significance.

Conditioning of the abdominal cavity reduces tumor implantation in a laparoscopic mouse model

PurposeThe addition of 4 % O2 and 10 % N2O to the CO2 pneumoperitoneum (PP), together with slight cooling and humidification (conditioning), contributes to reducing adhesions by preventing mesothelial damage. We investigated the effect of peritoneal damage during laparoscopy on tumor implantation.MethodsIn Experiment 1, different tumor cell concentrations were injected into control mice without PP and into mice with 60-min dry CO2PP (mesothelial damage). In Experiment 2, tumor cells were injected into control mice (group I) and in mice with mesothelial damage (group II). In groups III to VI, mesothelial damage was decreased by adding humidification, humidification + 10 % N2O, humidification + 10 % N2O + 4 % O2, and conditioning, respectively.ResultsIn Experiment 1, the tumors increased with the number of cells injected and with mesothelial damage in the abdominal cavity (p = 0.018) and abdominal wall (p < 0.0001). Experiment 2 confirmed that 60 min of dry CO2PP increased the number of tumors in the abdominal cavity and wall (p = 0.026 and p = 0.003, respectively). The number of tumors was decreased in the abdominal cavity by conditioning (p = 0.030) and in the abdominal wall using humidified CO2 (p = 0.032) or conditioning (p = 0.026).ConclusionsTumor implantation was enhanced by peritoneal damage (60 min of dry CO2PP and desiccation), but this was prevented by conditioning. If confirmed in humans, conditioning would become important for oncologic surgery.

Addition of nitrous oxide to the carbon dioxide pneumoperitoneum strongly decreases adhesion formation and the dose-dependent adhesiogenic effect of blood in a laparoscopic mouse model

To evaluate the effect of addition of nitrous oxide (N2O) to the carbon dioxide (CO2) pneumoperitoneum (PP) and the effect of blood, plasma, or red blood cells (RBCs) on postoperative adhesions in a laparoscopic mouse model. Prospective randomized controlled trial. University laboratory research center. BALB/c female mice. The effect of adding to the 60-minute CO2 PP 5%, 10%, 25%, 50%, or 100% N2O on adhesion formation was evaluated. Subsequently the effect of adding 1 mL blood, or RBCs, or plasma and the effect of adding different concentrations of blood were studied. Finally, the effect of adding 10% N2O, 4% O2, or both to the CO2 was evaluated in a control group and after addition of blood. Postoperative adhesions after 7 days. N2O strongly reduces adhesion formation with a full effect at a concentration of 5% or 10%. Adhesions increase linearly with 0.125 mL to 1 mL blood. In both the control group and after adding blood, 10% N2O is the most effective factor in prevention of adhesions. N2O, from concentrations of 5% upward, strongly prevents adhesion formation. Blood, mainly the plasma, increases adhesion formation. These data extend the concept of the role of acute inflammation and support the importance of good surgical practice with little bleeding and peritoneal cavity conditioning in adhesion prevention.

The impact of the learning curve on adhesion formation in a laparoscopic mouse model

To evaluate the impact of surgeon training on adhesion formation in a laparoscopic mouse model. Laparoscopic surgery and bowel manipulation was demonstrated to enhance postoperative adhesion formation. Prospective randomized, controlled trial. University laboratory research center. 200 BALB/c and 200 Swiss female mice. Adhesions were induced by opposing bipolar lesions and 60 minutes of pneumoperitoneum. Each surgeon operated on 80 mice (40 Swiss and 40 BALB/c), the only variable thus being his/her increasing experience. Some surgeons were already experienced gynecologists, others were starting their training. End points were the duration of surgery while performing the lesions. The adhesion formation was scored quantitatively (proportion and total) and qualitatively (extent, type, and tenacity) after 7 days. With training, duration of surgery and adhesion formation decreased exponentially for all surgeons, whether experienced or not. Experienced surgeons had initially a shorter duration of surgery, less adhesion formation, and less de novo adhesions than inexperienced surgeons. These data suggest that laparoscopic skills improve with training, leading to a decrease in the duration of surgery and formation of adhesions. Therefore completion of a standardized learning curve should be mandatory when initiating adhesion formation studies both in laboratory or clinical setting.

Postoperative inflammation in the abdominal cavity increases adhesion formation in a laparoscopic mouse model

To investigate acute inflammation in the peritoneal cavity in adhesion formation. Prospective randomized, controlled trial. University laboratory research center. 9- to 10-week-old BALB/c female mice. In a laparoscopic mouse model, acute inflammation in the peritoneal cavity evaluated in CO(2) pneumoperitoneum enhanced adhesions, by CO(2) pneumoperitoneum plus manipulation, and in the latter group plus dexamethasone. Qualitative and quantitative adhesion scores and an acute inflammation score (neoangiogenesis, diapedesis, and leukocyte accumulation). Adhesions at the lesion site were enhanced by the CO(2) pneumoperitoneum, further enhanced by manipulation, and decreased by the administration of dexamethasone. The acute inflammation scores (total, neoangiogenesis, diapedesis, and leukocyte accumulation) strongly correlated with the total adhesion score. Inflammation scores were similar at both the surgical lesion and the parietal peritoneum. Acute inflammation of the entire peritoneum cavity is an important mechanism involved in adhesion formation and enhances adhesion formation at the lesion site.

Intraperitoneal injection of cultured mesothelial cells decrease CO2 pneumoperitoneum-enhanced adhesions in a laparoscopic mouse model

Mesothelial cells are involved in peritoneal repair, and they modulate adhesion formation. Intraperitoneal injection of cultured mesothelial cells can decrease adhesion formation. The importance of the amount of cells, of the culture methods or of the origin of the cells is still unknown. Female Balb/c mice were used in a CO2 pneumoperitoneum-enhanced adhesion formation model. Mesothelial cells were obtained from Balb/c mice and cultured over a 3-week period. Following a pilot experiment (n = 10) with injection of 400,000 mesothelial cells a dose–response study was performed with 400,000; 133,000; and 44,000 cells (n = 40). Adhesion formation decreased after the injection of cultured mesothelial cells as evidenced in the first (proportion p < 0.046, total adhesions: NS) and second experiment (p < 0.001 for proportion and total adhesions). The reduction was moreover dose dependent with a half maximal effect with some 100,000 cells. Intraperitoneal injection of cultured mesothelial cells can decrease CO2 pneumoperitoneum-enhanced adhesion formation in mice and the effect is dose dependent, the half maximum effect being obtained with some 100,000 cells, a number which is surprisingly similar to the number of cells harvested from one mouse.

Hypothermia does Reduce Postoperative Adhesions: Reply

Sir, We thank Binda et al. for their interest in our study ‘‘Peritoneal infusion with cold saline decreased postoperative intra-abdominal adhesion formation’’ [1]. Our results do confirm the Binda et al. study that temperature change may affect adhesion formation in a laparoscopic mouse model [2]. Both studies showed that hypothermia reduces postoperative intra-abdominal adhesion formation. Concerning the impact of cold saline infusion upon body temperature, we used continuous dripping of 4 C normal saline into the abdominal cavity until the cold saline ran out. The effect will be limited in the abdominal cavity; its effects on superficial layer or entire body are undetermined. We did not examine the changes of mesothelium; it would be valuable for another study to demonstrate the reaction of mesothelium. Our cytokine level is calculated as mean and standard deviation. Due to limited space, we did not provide those data. Blood sampling for cytokines in this study is at days 1, 3, 7, and 14. It is unclear whether days 7 or 6 have the highest level of cytokines. However, it is generally agreed that peritoneal repair is complete after 7 days. The levels of cytokines in group III is nearly the one to four times those of group IV; we are not sure it is only slightly changed of cytokines. Finally, we do appreciate the excellent comments to clarify some intriguing issues and make the study of postoperative adhesion perfect.

Peritoneal Infusion with Cold Saline Decreased Postoperative Intra‐abdominal Adhesion Formation: Letter to the Editor

We read with interest the article by Fang et al. [1] demonstrating that peritoneal infusion with cold saline for 30 min after surgery decreased adhesion formation in a mouse model. These results indeed confirm our data demonstrating that, in a laparoscopic mouse model, adhesion formation decreases with hypothermia [2]. The data are, moreover, consistent with our observation in mice that intraperitoneal temperatures higher than 37 C increase adhesion formation [3], as had already been observed after irrigation with saline warmer than 37 C [4]. We would be most interested to have some additional information. From the article by Fang et al., it is unclear what the impact of cold saline infusion was upon body temperature of the mice; i.e., to what extent the infusion with cold saline affects the superficial layers, the abdominal cavity, or the entire body. We also were intrigued by the results of cytokines which are nice, but difficult to judge without standard deviations. Moreover we were surprised that some effects lasted for more than 7 days, although it is generally believed that peritoneal repair is completed by postoperative day 7. Also group III is intriguing. Because we know that desiccation occurs when the abdomen is left open, this can be assumed to be the driving mechanism of the increase of adhesions and of the changes in cytokines observed. Therefore, we wonder whether the authors observed any changes in the mesothelium indicating desiccation. Their data do, however, confirm that the peritoneal cavity is a cofactor in adhesion formation at the level of the surgical trauma [5]. Surprisingly, also in open surgery, Fang et al. did not see de novo adhesions, thus confirming our observations in a laparoscopic mouse model. The time courses of the cytokine concentrations in group IV (desiccation only; no surgical trauma) and group III (desiccation ? surgical trauma) are intriguing in that opening the abdomen (and desiccation) induced such an increase in adhesions, yet affected cytokines only slightly. In conclusion, we appreciate the promising results that expand to open surgery our observations that in laparoscopy temperature affects adhesion formation.

The role of acute inflammation at the peritoneal cavity-enhanced adhesion formation

Abstract Objective: To investigate the role of acute inflammation of the peritoneal cavity in adhesion formation. Design: Prospective randomized, controlled trial Setting: University laboratory research centerAnimals: 9-10 weeks old BALB/c female mice Interventions: In our laparoscopic mouse model acute inflammation of the peritoneal cavity and adhesion formation were evaluated in a control group with CO2 pneumoperitoneum (PP)-enhanced adhesions, in CO2 PP plus manipulation-enhanced adhesions and in the latter group + dexamethasone-reduced adhesions. Adhesions and acute inflammation were assessed by neoangiogenesis, diapedesis and leukocytes accumulation on the 2nd day after surgery. Main outcome measure(s): Qualitative and quantitative adhesion scores and an acute inflammation score.Results: Adhesions were enhanced by the CO2 PP (p=0.007), further enhanced by manipulation (p&amp;lt;0.0001 versus CO2 PP) and decreased by the administration of dexamethasone (p&amp;lt;0.0001 versus CO2 PP+manipulation ). Acute inflammation scores strongly correlated with total adhesion score whether assessed as total inflammation score (p&amp;lt;0.0001) or as neoangiogenesis (p&amp;lt;0.0002), diapedesis (p&amp;lt;0.03) or leukocyte accumulation (p&amp;lt;0.0002). Inflammation scores, moreover, were strikingly similar at the surgical lesion and at the parietal peritoneum. Conclusions: These data strongly suggest that acute inflammation in the entire peritoneum cavity is the driving mechanism of adhesion formation at the lesion site.

Hyperoxia and prevention of adhesion formation: a laparoscopic mouse model for open surgery

CO(2) pneumoperitoneum with more than 10% oxygen enhances adhesions. As during open surgery the peritoneum is exposed to air (20% oxygen), in this hyperoxia-enhanced adhesion model we evaluated the effect of hypothermia and products with known effectiveness in hypoxia (pure CO(2) pneumoperitoneum) and normoxia (CO(2) pneumoperitoneum plus 3-4% oxygen) models. Results were expected to be important for adhesion prevention in open surgery, and, moreover, similarities and differences between the three models would be important to identify differences in pathways of adhesion formation between laparoscopy and laparotomy. Two experiments were performed in which the effect of hypothermia (32 degrees C), a surfactant (phospholipids), a barrier (Hyalobarrier gel), reactive oxygen species scavengers (superoxide dismutase, SOD, and ascorbic acid, AA), anti-inflammatory agents (dexamethasone and nimesulide), a calcium channel blocker (diltiazem) and recombinant plasminogen activator (r-PA) were evaluated upon adhesions. University Hospital. BALB/c mice. Hyperoxia-enhanced adhesions were induced by performing laparoscopically bipolar lesions during 60 minutes of CO(2) pneumoperitoneum plus 12% oxygen at 37 degrees C body temperature. Adhesions were scored after 7 days. In this model, adhesions were reduced by hypothermia (P < 0.02; Wilcoxon), phospholipids (P = 0.03), Hyalobarrier gel (P < 0.004), dexamethasone (P < 0.005) and diltiazem (P < 0.01). A significant but quantitatively borderline effect was seen for AA (P < 0.002) and r-PA (P = 0.0005), whereas SOD and nimesulide did not have any effect. Hyperoxia-enhanced adhesions were prevented by hypothermia, dexamethasone, phospholipids, Hyalobarrier gel, diltiazem, r-PA and AA. All effects were similar to those in the hypoxia-enhanced adhesion model, suggesting that the underlying mechanisms are similar.

Effect of Upper Abdomen Tissue Manipulation on Adhesion Formation between Injured Areas in a Laparoscopic Mouse Model

Study Objective These experiments were designed to examine the effect of manipulation during surgery as a cofactor in adhesion formation at trauma sites. Design Randomized, controlled trial. Canadian Task Force Classification–class 1. Setting University laboratory research center. Subjects A standardized laparoscopic mouse model (Balb\\c mice 9–10 weeks old) for adhesion formation after opposing bipolar lesions and 60 minutes of carbon-dioxide pneumoperitoneum. In this model adhesions are known to decrease after the addition of 3% of oxygen, dexamethasone, or both. In addition, adhesions decrease with experience (i.e., with a decreasing amount of manipulation during the learning curve). Interventions A factorial design was used to evaluate the effects of dexamethasone and of adding 3% of oxygen on manipulation-enhanced adhesion formation during a learning curve. Blocks of 4 animals were thus randomized as controls (carbon-dioxide pneumoperitoneum only) or received an additional 3% of oxygen, dexamethasone, or both. In a second experiment, the effects of manipulation on adhesion formation were quantified. In a third experiment we evaluated whether dexamethasone had a specific effect on manipulation-enhanced adhesion formation. Measurements and Main Results Qualitative and quantitative adhesion scoring 7 days after the intervention. The first experiment confirmed that adhesion formation decreased during the learning curve (p <.0001) and after the addition of dexamethasone whether assessed as the total adhesion score (p <.0001 and p =.0009, respectively) or a quantitative score (p <.0001 and p <.0001, respectively). The second experiment showed that adhesion formation increased by standardized touching and grasping of omentum and bowels (proportion score p =.0059 and p =.0003, respectively) and this effect increased with duration of touching (p =.0301). In the third experiment, dexamethasone was confirmed to decreased adhesion formation (p =.0001) but this effect was not specific for manipulation-enhanced adhesion formation. Conclusion Manipulation of intraperitoneal organs in the upper abdomen enhances adhesion formation at trauma sites, confirming that the peritoneal cavity is a cofactor in adhesion formation. Dexamethasone decreases adhesion formation but the effect is not specific for manipulation-enhanced adhesion formation.

Prevention of adhesion formation in a laparoscopic mouse model should combine local treatment with peritoneal cavity conditioning

Adhesion formation results from a series of local events at the trauma site. This process can be enhanced by factors derived from the peritoneal cavity such as mesothelial cell hypoxia (pneumoperitoneum with pure CO(2)), reactive oxygen species (pneumoperitoneum with more than 4% oxygen), desiccation and mesothelial trauma produced through manipulation. Adhesion prevention, therefore, should combine local treatment while minimizing adverse peritoneal factors through conditioning of the pneumoperitoneum. In a laparoscopic mouse model, adhesion induction comprised a mechanical lesion together with a humidified pneumoperitoneum for 60 min with pure CO(2) at 37 degrees C. Adhesion prevention consisted of a combination of treatments known to reduce adhesions, i.e. pneumoperitoneum with CO(2) with the addition of 3-4% O(2), reduction of body temperature (BT) to 32 degrees C and application of antiadhesion products such as anti-inflammatory drugs (dexamethasone, nimesulide), calcium-channel blockers (diltiem), surfactants (phospholipids), barriers (Hyalobarrier gel), reactive oxygen species scavengers (superoxide dismutase and ascorbic acid) and recombinant plasminogen activator. The addition of 3% O(2) to the pneumoperitoneum or a lower BT decreased adhesions by 32% or 48%, respectively (P < 0.05, Wilcoxon), but were without additional effects when combined. In addition, if dexamethasone or Hyalobarrier((R)) gel were administrated, the total reduction was 76% (P = 0.04) or 85% (P < 0.02), respectively. Combining pneumoperitoneum conditioning together with dexamethasone or a barrier resulted in significant adhesion reduction in a laparoscopic mouse model.

Intercoat Gel (Oxiplex): Efficacy, Safety, and Tissue Response in a Laparoscopic Mouse Model

Study Objective To study the efficacy and safety of Intercoat gel in a laparoscopic mouse model with pneumoperitoneum-enhanced adhesion formation. Design Randomized controlled trial. Evidence obtained from a properly designed, randomized, controlled trial (Canadian Task Force classification I). Setting University laboratory research center. Subjects Balb\\c female mice 9 to 10 weeks old. Interventions Two laparoscopic mouse models for adhesion formation were used. In the first model, adhesions following bipolar opposing lesions in the pelvis were enhanced by 60 minutes of carbon-dioxide pneumoperitoneum. In the second model, adhesions were further enhanced by bowel manipulation. The first experiment evaluated the efficacy of Intercoat in both models. The second experiment evaluated the efficacy of Intercoat in the first model, when applied immediately on the lesion, when applied at the end of the pneumoperitoneum, and when applied in the upper abdomen. Biopsy specimens were taken after 7 days and were evaluated after hematoxylin-eosin and CD45 staining. Measurements and Main Results Qualitative and quantitative adhesion scoring. Morphology was evaluated by standard light microscopy. In both models, Intercoat decreased adhesion formation whether applied immediately on the lesion or at the end of the pneumoperitoneum (qualitative and quantitative scoring p <.0001 and p <.0001, respectively). Intercoat application is associated with tissue redness, vascular congestion, and cellular edema but without an inflammatory reaction. Applied in the upper abdomen, Intercoat does not increase adhesions, but decreases adhesions at higher doses (p =.0024). Intercoat in high doses had a toxic effect (p =.0058). Conclusion Intercoat is an effective antiadhesion product. It is associated with tissue edema and vasodilatation as observed after 7 days both macroscopically and by histology.

The Addition of 4% Oxygen to the CO 2 Pneumoperitoneum Does Not Decrease Dramatically Port Site Metastases

Study Objective Port site metastases (PSM) after laparoscopic surgery for advanced-stage ovarian carcinoma are a cause of concern, but the pathophysiology is unknown. Because CO 2 pneumoperitoneum was recently demonstrated to be a cofactor in adhesion formation and tumor implantation in a laparoscopic mouse model, and because both could be prevented by the addition of 4% oxygen to the CO 2 pneumoperitoneum, we wanted to test the hypothesis that PSM could be related to tumor cell hypoxia during CO 2 pneumoperitoneum. Design A randomized controlled pilot trial to compare the incidence of PSM in women undergoing laparoscopy with a pure CO 2 pneumoperitoneum in comparison with women with CO 2 pneumoperitoneum with the addition of 4% oxygen (Canadian Task Force classification C). Setting University Hospital Gasthuisberg, Leuven, Belgium. Patients Since January 1, 2007, 22 consecutive women undergoing laparoscopy for suspected ovarian cancer with subsequent debulking laparotomy were included. Interventions Diagnostic laparoscopy with 100% CO 2 versus laparoscopy with addition of 4% oxygen. Measurements and Main Results In the control group, 9 (47%) PSM found in 19 port sites were excised. In the CO 2+oxygen group, a similar incidence was found, that is, 8 (50%) PSM in 16 port sites. The incidence of PSM was higher in small women (p <.018) and in high-grade malignancies. The pathophysiology of PSM is unknown, but besides direct wound contamination, aerosolization of tumor cells and gas leaks have been suggested together with a causal relationship with the CO 2 pneumoperitoneum. Tumor cell hypoxia probably is not an important mechanism because PSM were not prevented by adding small amounts of oxygen to the CO 2 pneumoperitoneum. Conclusion The hypothesis of tumor cell hypoxia by the CO 2 pneumoperitoneum as a mechanism for PSM could not be confirmed.

Effect of Reteplase™ and PAI-1 antibodies on postoperative adhesion formation in a laparoscopic mouse model

Postoperative adhesions remain an important clinical problem, accounting for infertility, chronic pain and bowel obstruction. Its prevention is still inadequate and overall poorly understood. The aim of this study was to investigate the effect of Reteplase (a recombinant plasminogen activator, r-PA) and of PAI-1 antibodies upon adhesion formation in a laparoscopic model. Pneumoperitoneum-enhanced adhesions were induced by performing a bipolar lesion in female BALB/c mice and by using pure and humidified CO(2) as insufflation gas for 60 min. In experiment 1, four doses of 0.125, 0.25, 0.5 and 1 mg/0.5 ml r-PA and one and two doses of 1 mg r-PA were administrated i.p. Two control groups were included, one without any treatment and the second one receiving four times 0.5 ml of saline. In experiment 2, four doses of 0, 1, 10 and 100 microg/0.5 ml r-PA were administrated i.p. In experiment 3, PAI-1 neutralising and non-neutralising antibodies were injected i.p. after performing the lesion on day 0 and days 2 and 4. Adhesions were scored after 7 days. Adhesion formation was less with the administration of four doses of 1 microg r-PA (proportion, p < 0.04, Wilcoxon). An increase in adhesion formation was observed when higher number of doses and amounts of r-PA were used (Proc GLM, eight groups, two variables, p = 0.05 for the amount of r-PA and p < 0.02 for the number of doses administrated). No effect was observed with the PAI-1 antibodies. Low-dose i.p. administration of rPA is effective in the prevention of adhesions in a laparoscopic mouse model.

Efficacy of barriers and hypoxia-inducible factor inhibitors to prevent CO 2 pneumoperitoneum-enhanced adhesions in a laparoscopic mouse model

Study objective To investigate the effects of hypoxia-inducible factor (HIF) inhibitors, flotation agents, barriers, and a surfactant on pneumoperitoneum-enhanced adhesions in a laparoscopic mouse model. Design Prospective randomized trial (Canadian Task Force classification I). Setting Department of Obstetrics and Gynecology, University Hospital Gasthuisberg, Catholic University of Leuven. Subjects One hundred fourteen female BALB/c mice. Interventions Adhesions were induced during laparoscopy in BALB/c female mice. Pneumoperitoneum was maintained for 60 minutes with humidified CO 2. In 3 experiments the effects of HIF inhibitors such as 17-allylamino 17-demethoxygeldanamycin, radicicol, rapamycin, and wortmanin, flotation agents such as Hyskon and carboxymethylcellulose, barriers such as Hyalobarrier gel and SprayGel, and surfactant such as phospholipids were evaluated. Measurements and main results Adhesions were scored after 7 days during laparotomy. Adhesion formation decreased with the administration of wortmannin (p <.01), phospholipids (p <.01), Hyalobarrier Gel (p <.01), and SprayGel (p <.01). Conclusions These experiments confirm the efficacy of barriers and phospholipids to separate or lubricate damaged surfaces. They also confirm the role of mesothelial hypoxia in this model by the efficacy of the HIF inhibitor wortmannin.

Effect of reactive oxygen species scavengers, antiinflammatory drugs, and calcium-channel blockers on carbon dioxide pneumoperitoneum-enhanced adhesions in a laparoscopic mouse model

Postoperative adhesions are a clinical problem. They can cause female infertility, intestinal obstruction, chronic pelvic pain, and difficulties at the time of reoperation. A variety of approaches described to prevent adhesions have shown variable and inconsistent results. Therefore, this study aimed to evaluate most known substances in a laparoscopic mouse model to obtain quantitative and comprehensive information on adhesion prevention. Specifically, this first study aimed to investigate the effects of reactive oxygen species (ROS) scavengers, antiinflammatory agents, and a calcium-channel blocker on pneumoperitoneum-enhanced adhesions. Adhesions were induced during laparoscopy in BALB/c female mice by creation of a bipolar lesion. Carbon dioxide (CO2) pneumoperitoneum was maintained for 60 min using humidified CO2. Six experiments were conducted to evaluate the effects of ROS scavengers (superoxide dismutase [SOD], catalase, melatonin, and ascorbic acid), antiinflammatory agents (dexamethasone, tenoxicam, ibuprofen, parecoxib, nimesulide, anti-tumor necrosis factor [TNF]-alpha), and a calcium-channel blocker (diltiazem). Adhesions were scored after 7 days during laparotomy. Adhesions were reduced by SOD (p < 0.01, proc general linear methods (GLM) of experiments 1 and 2), diltiazem (p = 0.05, Wilcoxon), and dexamethasone (p < 0.03), but not by nonsteroidal antiinflammatory drugs (NSAIDs) nor by anti-TNF-alpha. When all the experiments were grouped for analysis, adhesions also decreased with one and three doses of SOD (p < 0.01 and p < 0.01, respectively) and with one and three doses of ascorbic acid (p < 0.02 and p = 0.05, respectively). These experiments confirm that SOD, diltiazem, and dexamethasone can decrease adhesion formation. The absence of effect from the other antiinflammatory drugs and anti-TNF-alpha is surprising.

Effect of desiccation and temperature during laparoscopy on adhesion formation in mice

To investigate the effects of desiccation (without cooling) and of oversaturation of the pneumoperitoneum on adhesion formation. Prospective randomized trial. Academic research center. BALB/c and NMRI female mice. The effect of desiccation using nonhumidified CO(2) on adhesion formation was evaluated in a laparoscopic mouse model. Body temperature (BT) was maintained at 37 degrees C using a homeothermic blanket. In addition to controls without desiccation, the effect of both hypothermia and desiccation on adhesion formation was evaluated. Subsequently the effect of oversaturating the pneumoperitoneum using a high energy gas to avoid any desiccation was studied. During surgery BT, pneumoperitoneum temperature, and relative humidity were monitored. Adhesions were scored after 7 days. Adhesions increased with increasing levels of desiccation when BT was kept at 37 degrees C. This was prevented with humidified gas. If BT decreased, adhesions were fewer. Oversaturating the pneumoperitoneum increased adhesions due to high energy gas causing an increase in both BT and pneumoperitoneum temperature. Adhesions increase with desiccation and decrease when BT is reduced. Adhesions are minimized when humidified gas is used. Since desiccation is associated with cooling, its effect is generally underestimated because of the counterbalance with cooling. The concept of combining controlled intraperitoneal cooling with a rigorous prevention of desiccation might be important for clinical adhesion prevention.

Adhesion formation and interanimal variability in a laparoscopic mouse model varies with strains

Adhesion formation after laparoscopic surgery was evaluated in mice of different strains. More adhesions were observed in Swiss, NMRI, and BALB/c mice, with less interanimal variability in BALB/c mice. These data point to genetics effects on adhesion formation, which open new insights in its pathogenesis and indicate the importance of a careful strain selection for animal studies.

Effect of adding more than 3% oxygen to carbon dioxide pneumoperitoneum on adhesion formation in a laparoscopic mouse model

To investigate the effect of the addition of 3% or higher oxygen concentrations to the carbon dioxide (CO2) pneumoperitoneum. Prospective, randomized trial. Academic research center. Female Naval Medical Research Institute mice (n = 100). Sixty minutes of CO2 pneumoperitoneum with 0%, 3%, 6%, 9%, or 12% oxygen; induction of adhesions by the creation of standardized peritoneal lesions during laparoscopy. Adhesions were quantitatively and qualitatively scored after 7 days during laparotomy to determine [1] the effect of 60 minutes of CO2 pneumoperitoneum with 0%, 3%, 6%, 9%, or 12% oxygen on adhesion formation, and [2] the effect of duration of CO2 pneumoperitoneum and insufflation pressure on adhesion formation with the addition of 0%, 3%, and 12% oxygen. Compared with a CO2 pneumoperitoneum with 3% oxygen, adhesion formation is greater when either no oxygen or more than 3% oxygen is added to the CO2 pneumoperitoneum. These effects persisted at higher insufflation pressures and longer duration of pneumoperitoneum, both known to increase adhesion formation with pure CO2. This study confirms that adhesion formation is decreased with the addition of 3% oxygen to the CO2 pneumoperitoneum. The addition of higher oxygen concentrations, however, is deleterious. Adhesions always increase with time and duration of the pneumoperitoneum.