Neurokinin-1 receptor and substance P messenger RNA levels increase during intraabdominal adhesion formation

Comparison of the effect of Everolimus, Prednisolone, and a combination of both on experimentally induced peritoneal adhesions in rats

Postoperative intra-abdominal adhesions represent a significant post-surgical problem. Its complications can cause a considerable clinical and cost burden. Herein, our study aimed to investigate the effect of Everolimus on peritoneal adhesion formation after inducing adhesions in rats. In this experimental study, adhesion bands were induced by intraperitoneal injection of 3 ml of 10% sterile talc solution in 64 male albino rats. The first group served as the control group. The second one received oral Prednisolone (1 mg/kg/day), the third received Everolimus (0.1 mg/kg/day), and group four received both drugs with similar dosages for four consecutive weeks. The formation of adhesion bands was qualitatively graded according to the Nair classification. The rats in the control group had extensive adhesions between the abdominal wall and the organs. Regarding substantial adhesion formation, 50% (8/16) of animals in the control group had substantial adhesions, while this rate in the groups receiving Prednisolone, Everolimus, and combination treatment was 31%, 31%, and 31%, respectively. Also, 68.75% (5/11) of the Prednisolone recipients had insubstantial adhesions, the same as Everolimus recipients, while in the combination group, 66.66% (10/15) rats had insubstantial adhesions. Everolimus demonstrated satisfactory results in reducing the rates of induced peritoneal adhesion in an experimental model, similar to Prednisolone and superior to a combination regime.

Analgesia in patients with adhesion-related chronic abdominal and pelvic pain after surgery: a systematic review

BACKGROUND AND OBJECTIVE

Adhesions are the most common cause of chronic abdominal pain after surgery. Surgical adhesiolysis can relieve symptoms in selected patients, but many require other treatments. The aim of this study is to evaluate analgesic treatments other than abdominal surgery in chronic pain related to adhesions.

DATABASE AND DATA TREATMENT

A search was conducted in PubMed, Embase, and Central. Studies with patients suffering from chronic postoperative pain related to adhesions and undergoing all types' analgesic treatment were included. The primary outcome was the number of patients who improved in pain at long-term follow-up (at least 1 year). Secondary outcomes included improvement in pain at 3 months follow-up, quality of life, and physical functioning.

RESULTS

Searches identified 3022 citations. Four studies were included, one trial, one cohort study, and two case reports. The primary outcome was not reported. In a small trial (n = 18) pregabalin tended to have a benefit over placebo improving pain at 3 months. In the cohort study, 17 patients with chronic pelvic pain underwent a trial of sacral nerve stimulation. Eight patients who responded positively received an implanted device for continuous modulation, reporting sustainable improvement during follow-up (range: 6-36 months). One case report described improved pain at 6 months with trans-abdominis plane stimulation. The second report described improvement of physical function with manual therapy at long-term follow-up.

CONCLUSIONS

Low level of evidence is available regarding analgesic treatments of chronic abdominal and pelvic pain related to adhesions. The benefit of pregabalin is doubtful; nerve modulation is promising in a selected group.HighlightsAdhesions are a frequent cause of chronic abdominal and pelvic pain after surgery.Many patients are not good candidates for surgery (Adhesiolysis) or have relapses of pain.There is an important knowledge gap regarding non-surgical analgesic treatment.Analgesia in adhesion-related chronic abdominal pain after surgery.

Post-Operative Adhesions: A Comprehensive Review of Mechanisms

Post-surgical adhesions are common in almost all surgical areas and are associated with significant rates of morbidity, mortality, and increased healthcare costs, especially when a patient requires repeat operative interventions. Many groups have studied the mechanisms driving post-surgical adhesion formation. Despite continued advancements, we are yet to identify a prevailing mechanism. It is highly likely that post-operative adhesions have a multifactorial etiology. This complex pathophysiology, coupled with our incomplete understanding of the underlying pathways, has resulted in therapeutic options that have failed to demonstrate safety and efficacy on a consistent basis. The translation of findings from basic and preclinical research into robust clinical trials has also remained elusive. Herein, we present and contextualize the latest findings surrounding mechanisms that have been implicated in post-surgical adhesion formation.

Effectiveness of barrier agents for preventing postoperative bowel obstruction after laparoscopic surgery: a retrospective cohort study

PURPOSE

The effectiveness of using anti-adhesion agents in laparoscopic surgery is controversial. We compared the outcomes of patients exposed to anti-adhesion agents (barrier group) with those of patients not exposed (no barrier group) in laparoscopic surgery.

METHODS

Using a nationwide claim-based database in Japan, we analyzed data from patients who underwent laparoscopic surgery between 2005 and 2019 and compared the patient characteristics and the proportion of those with bowel obstruction between the barrier and no barrier groups. We also performed several sensitivity and subgroup analyses.

RESULTS

Of the 57,499 patients who met the inclusion criteria, 14,360 and 43,139 were assigned to the barrier and no barrier groups, respectively. The proportion of patients with a bowel obstruction in the two groups did not differ among all patients hospitalized for obstruction (1.1 vs. 1.1%, p = 0.63) and those requiring surgery (0.2 vs. 0.2%, p = 0.39). In the sensitivity analysis with propensity score matching, the incidences of bowel obstruction between the barrier and non-barrier groups were equivocal (1.3 vs. 1.6%), but statistically marginal (chi-square test, p = 0.035; log-rank test, p = 0.09).

CONCLUSION

The use of barrier agents for adhesive prevention did not show clear effectiveness for the prevention of bowel obstruction after laparoscopic surgery for unselected cases. Further studies focusing on more specific procedures are needed.

Value of artificial ascites to assist thermal ablation of liver cancer adjacent to the gastrointestinal tract in patients with previous abdominal surgery

Background

To evaluate the feasibility and effectiveness of artificial ascites to assist thermal ablation of liver cancer adjacent to the gastrointestinal tract in patients with previous abdominal surgery.

Methods

Thirty-nine patients with a total of 40 liver malignant tumors were enrolled between January 2016 and June 2019. All had histories of hepatectomy, splenectomy, cholecystectomy, and intestinal surgery. The distance between the tumor and the gastrointestinal tract was < 5 mm. Normal saline was used as artificial ascites to protect the gastrointestinal tract during thermal ablation. The success rate of the procedure, incidence of major complications, and the technical efficacy of ablation were recorded. Patients were followed for local tumor progression (LTP), and overall survival (OS).

Results

The use of artificial ascites was successful in 38 of the 40 procedures (95%). Major complications occurred in two of the 39 patients (5.1%) following the procedure. One was an intestinal fistula that occurred in a failed case and was associated with an infection. The other was a liver abscess that occurred in a successful case. The technical efficacy of ablation was 100% (40/40 procedures). The median follow-up was 16 months. The 1-, 2-, and 3-year LTP rates were 2.9, 5.7 and 5.7%. The 1-, 2-, and 3-year OS rates were 97.1, 86.8 and 69.5%.

Conclusion

In patients with previous abdominal surgery, artificial ascites is feasible and effective for assisting thermal ablation of liver cancer adjacent to the gastrointestinal tract.

[Influence of unmodified and modified sutures on experimental abdominal adhesive process]

OBJECTIVE

Experimental assessment of the effect of modified and unmodified surgical suture material on abdominal adhesive process.

MATERIAL AND METHODS

The study was performed on male rats of the Wistar subpopulation. There were 5 animals in each group. In all animals, midline abdominal incision was followed by suturing the parietal peritoneum with modified and unmodified suture material. All animals were euthanized with carbon dioxide vapors in 14 days after surgery. Macro- and microscopic assessment of severity of abdominal adhesive process was carried out. Two types of preparation of excised complexes 'peritoneum-suture material-adhesion' were applied for histological examination: paraffin sections and embedding in epoxy resin. Specimens were stained by Van Gieson and with methylene blue solution. Histological specimens were examined using Axio Imager A1 light microscope (Zeiss, Germany).

RESULTS

Polypropylene filaments result extensive adhesions occupying about 75% of the area. Adhesions have a dense structure with signs of vascularization. Modification of suture material with solution of polyhydroxybutyrate/hydroxyvalerate and heparin reduce severity of adhesions. The use of modified suture material was followed by adhesions with more loose structure, no signs of vascularization. Adhesions occupied less than 25% of the area. Histological examination of excised complexes 'peritoneum-suture material-adhesion' revealed accumulation of inflammatory cells around the unmodified suture material, while there were no signs of tissue inflammatory process around the modified sutures.

CONCLUSION

Application of polyhydroxybutyrate/hydroxyvalerate and heparin on the surface of surgical sutures is an effective method for prevention of abdominal adhesions.

The Effect of Daikenchuto, Japanese Herbal Medicine, on Adhesion Formation Induced by Cecum Cauterization and Cecum Abrasion in Mice

Daikenchuto (DKT) has been widely used for the treatment of postsurgical ileus in Japan. However, its effect on postsurgical adhesion formation has been obscure. In this study, the effect of DKT on postsurgical adhesion formation induced by cecum cauterization or cecum abrasion in mice was investigated. First, the expression of adhesion-related molecules in damaged ceca was investigated by quantitative (q)RT-PCR. During 24 h after surgery, mRNA expressions of interferon-γ (IFN-γ), plasminogen activator inhibitor-1 (PAI-1), interleukin-17 (IL-17), and Substance P (SP) in cauterized ceca and those of PAI-1 and IL-17 in abraded ceca were significantly up-regulated. Next, the effect of DKT on adhesion formation macroscopically evaluated with adhesion scoring standards. DKT (22.5-67.5 mg/d) was administered orally for 7 d during the perioperative period, and DKT did not reduce adhesion scores in either the cauterization model (control : DKT 67.5 mg/d, 4.8 ± 0.2 : 4.8 ± 0.2) or in the abrasion model (control : DKT 67.5 mg/d, 4.9 ± 0.1 : 4.5 ± 0.3). Histologically, collagen deposition and leukocyte accumulation were found at the adhesion areas of control mice in both models, and DKT supplementation did not alleviate them. Last, effect of DKT on expression of proadhesion moleculs was evaluated. DKT also failed to down-regulate mRNA expression levels of them in damaged ceca of both models. In conclusion, PAI-1 and IL-17 may be key molecules of postsurgical adhesion formation. Collagen deposition and leukocytes accumulation are histological characteristic feature of post-surgical adhesion formation. DKT may not have any preventive effect on postsurgical adhesion formation in mice.

Tetramethylpyrazine Improves Postoperative Tissue Adhesion: A Drug Repurposing

Plants are known to possess plenty of pharmacological activities as a result of various phytoconstituents. Tetramethylpyrazine (TMP), one of the most widely used medicinal compound isolated from traditional Chinese herb, is usually employed for anti-oxidation, anti-inflammation, anti-platelet aggregation, anti-lipid, anti-fibrosis, as well as activating blood, removing stasis, dilating small arteries, improving microcirculation and antagonizing calcium. In the present paper, the anti-adhesion effect of TMP were reviewed. TMP was found to play a multi-target and muti-link role in anti-adhesion by inhibiting hyperplasia of collagen and overexpression of adhesion-related factors and reducing the concentration of white blood cells and fibrin in plasma. Because previous studies mostly focused on in vitro experiments and animal experiments, there is an urgent need for clinical research with abundant indicators to further prove its anti-adhesion potency. Future basic research should concentrate on the development of TMP as a biological material.

Surgical adhesions in mice are derived from mesothelial cells and can be targeted by antibodies against mesothelial markers

Peritoneal adhesions are fibrous tissues that tether organs to one another or to the peritoneal wall and are a major cause of postsurgical and infectious morbidity. The primary molecular chain of events leading to the initiation of adhesions has been elusive, chiefly due to the lack of an identifiable cell of origin. Using clonal analysis and lineage tracing, we have identified injured surface mesothelium expressing podoplanin (PDPN) and mesothelin (MSLN) as a primary instigator of peritoneal adhesions after surgery in mice. We demonstrate that an anti-MSLN antibody diminished adhesion formation in a mouse model where adhesions were induced by surgical ligation to form ischemic buttons and subsequent surgical abrasion of the peritoneum. RNA sequencing and bioinformatics analyses of mouse mesothelial cells from injured mesothelium revealed aspects of the pathological mechanism of adhesion development and yielded several potential regulators of this process. Specifically, we show that PDPN+MSLN+ mesothelium responded to hypoxia by early up-regulation of hypoxia-inducible factor 1 alpha (HIF1α) that preceded adhesion development. Inhibition of HIF1α with small molecules ameliorated the injury program in damaged mesothelium and was sufficient to diminish adhesion severity in a mouse model. Analyses of human adhesion tissue suggested that similar surface markers and signaling pathways may contribute to surgical adhesions in human patients.

Effect of Hydrogen-Rich Saline on Postoperative Intra-Abdominal Adhesion Bands Formation in Mice

Background

Postsurgical peritoneal adhesions (PPAs) are pathologic fibrous bands within the peritoneal cavity. The aim of this study was to investigate the protective effect of hydrogen-rich saline (HRS) on PPAs formation in mice.

Material/Methods

Adhesions were induced in mice using the cecum rubbing model. The mice were allocated into 4 groups: control sham group without cecum rubbing; PPA group with saline applied intraperitoneally (i.p.) daily after cecum rubbing; PPA+HRS (5) group with 5 ml/kg of HRS applied i.p. daily after cecum rubbing; and PPA+HRS (10) group with 10 ml/kg of HRS applied i.p. daily after cecum rubbing. On the 1^st, 3^rd, and 7^th days after the operation, mice were killed and pathological adhesion bands were quantified to detect the effect of HRS on PPAs formation.

Results

HRS did not affect PPAs formation on the 1^st day, but did make a significant reduction on the 3^rd and 7^th days. A significant increase of t-PA and decrease of TGF-β1 and PAI-1 in the peritoneal fluids were observed in the HRS-treated groups. The levels of MDA and MPO in the HRS-treated groups were significantly lower than those in the PPA group. TNF-α and IL-6 levels in HRS-treated groups significantly decreased compared with those in the PPA group on postoperative day 3 and 7. Moreover, HRS decreased the mRNA levels of pro-inflammatory cytokines and TGF-β1 expression in the postsurgical adhesion bands.

Conclusions

These results showed that HRS had therapeutic potential for preventing PPAs formation, possibly through balancing the expression of TGF-β1, t-PA, and PAI-1, and inhibiting oxidative stress and inflammation.

Paeoniflorin prevents postoperative peritoneal adhesion formation in an experimental rat model

Although materials and modern surgical techniques have been developed to suppress postoperative adhesions, adhesion formation can still occur, and thus, a novel effective anti-adhesion drug is greatly needed. In the present study, we explored the efficacy of paeoniflorin treatment against postoperative peritoneal adhesions and examined the anti-oxidative stress and anti-inflammatory properties of PE. Forty-eight male Sprague-Dawley rats were randomly divided into 6 groups for the study: the sham, control, hyaluronan and three concentrations (10, 20 and 40 mg/kg/d) paeoniflorin groups. Abdominal adhesions were created by abrasion of the caecum and its opposite abdominal wall. In the paeoniflorin groups, the rats were administered daily oral doses of paeoniflorin for 7 days. The abdominal cavities of the rats were reopened with a U-shaped incision to macroscopically grade the adhesions. Histologic analysis was performed, and oxidative stress, inflammatory cytokine, collagen fiber degradation and cytokeratin levels were measured. Macroscopic and histopathological measurements revealed that paeoniflorin reduced peritoneal adhesion and inflammation. Notably, treatment with paeoniflorin reduced the protein levels of TGF-β1, IL-6 and COX-2. The collagen fiber fractions were distinctly lower in the PE groups than in the control group. Western blotting analyses showed that paeoniflorin increased MMP-9 and superoxide dismutase-2 protein expression and sharply reduced α-SMA and COX-2 protein expression. Peritoneal mesothelium cells were more continuous and complete in animals treated with paeoniflorin. Our study suggests that paeoniflorin can be used to ameliorate peritoneal adhesions via anti-oxidative stress and anti-inflammatory actions during the postoperative period.

A Novel Method for Evaluating Postoperative Adhesions in Rats

Purpose/Aim: Postoperative adhesions remain an undesirable and commonly symptomatic side effect of abdominopelvic surgeries. Animal models of postoperative adhesions typically yield heterogeneous adhesions throughout the abdominal cavity and are not easily quantified. Here we present a novel method of postoperative adhesion assessment and report its reliability and measurement error.

MATERIALS AND METHODS

A model of cecal abrasion with partial sidewall attachment was performed on female rats. After 1, 2, 4, or 7 days of recovery, the rats were euthanized and their abdominopelvic cavities were systematically evaluated for postoperative adhesions. The necropsy was recorded through the surgical microscope. Four raters were trained to use a ballot to capture key factors of the adhesions as they viewed the recordings. Their ratings were compared for measurement error and reliability (using Bland-Altman plots and intraclass correlation coefficients, respectively) and for the ability to discriminate differences in experimental groups. A subset of the data was analyzed to determine practical utility.

RESULTS

The rating system was shown to have low measurement error and high inter-rater reliability for all parameters measured. Applied practically, the system was able to discriminate groups in a manner that was expected.

CONCLUSIONS

We have developed and validated a rating system for postoperative adhesions and shown that it can detect group differences. This method can be used to quantify postoperative adhesions in rodent models.

The comparison of the effects of ellagic acid and diclofenac sodium on intra-abdominal adhesion: an in vivo study in the rat model

Peritoneal adhesions are seen frequently after abdominal surgery and can cause serious complications. We aimed to evaluate the effects of the oral use of diclofenac sodium and ellagic acid on formation of postoperative adhesions in rats Studies have shown that agents with anti-inflammatory properties and antioxidant substances can prevent adhesion by decreasing oxidative stress. We compared and evaluated the effects of ellagic acid that has strong antioxidant and anti-inflammatory properties and the nonsteroidal anti-inflammatory diclofenac sodium on peritoneal adhesion development in our experimental study. Laparotomy was performed with a midline incision under general anesthesia and an adhesion model was created on the antimesenteric side of the cecum in Groups I, II, and III. Group I received 85 mg/kg ellagic acid and Group II, 50 mg/kg diclofenac sodium through the nasogastric catheter while Group III received no medication. Only laparotomy was performed in Group IV. The rats were sacrificed at the end of the 14th day. Following macroscopic scoring, tissue samples were removed and subjected to biochemical and histopathologic evaluation. The degree of adhesion and the malondialdehyde level were decreased (P < 0.05), and glutathione level increased (P < 0.05) in Group I compared to Group II and Group III. The effects of ellagic acid on the prevention of peritoneal adhesion were found to be stronger than diclofenac sodium. This can be explained by the fact that ellagic acid is a strong antioxidant and decreases oxidative stress with anti-inflammatory and anti-angiogenic effects.

Effects of macrophage-dependent peroxisome proliferator-activated receptor γ signalling on adhesion formation after abdominal surgery in an experimental model

BACKGROUND

The pathophysiology of adhesion formation after abdominal and pelvic surgery is still largely unknown. The aim of the study was to investigate the role of macrophage polarization and the effect of peroxisome proliferator-activated receptor (PPAR) γ stimulation on adhesion formation in an animal model.

METHODS

Peritoneal adhesion formation was induced by the creation of ischaemic buttons within the peritoneal wall and the formation of a colonic anastomosis in wild-type, interleukin (IL) 10-deficient (IL-10(-/-) ), IL-4-deficient (IL-4(-/-) ) and CD11b-Cre/PPARγ(fl) (/fl) mice. Adhesions were assessed at regular intervals, and cell preparations were isolated from ischaemic buttons and normal peritoneum. These samples were analysed for macrophage differentiation and its markers, and expression of cytokines by quantitative PCR, fluorescence microscopy, arginase activity and pathological examination. Some animals underwent pioglitazone (PPAR-γ agonist) or vehicle treatment to inhibit adhesion formation. Anastomotic healing was evaluated by bursting pressure measurement and collagen gene expression.

RESULTS

Macrophage M2 marker expression and arginase activity were raised in buttons without adhesions compared with buttons with adhesions. IL-4(-/-) and IL-10(-/-) mice were not affected, whereas CD11b-Cre/PPARγ(fl) (/fl) mice showed decreased arginase activity and increased adhesion formation. Perioperative pioglitazone treatment increased arginase activity and decreased adhesion formation in wild-type but not CD11b-Cre/PPARγ(fl) (/fl) mice. Pioglitazone had no effect on anastomotic healing.

CONCLUSION

Endogenous macrophage-specific PPAR-γ signalling affected arginase activity and macrophage polarization, and counter-regulated peritoneal adhesion manifestation. Pharmacological PPAR-γ agonism induced a shift towards macrophage M2 polarization and ameliorated adhesion formation in a macrophage-dependent manner. Surgical relevance Postoperative adhesion formation is frequently seen after abdominal surgery and occurs in response to peritoneal trauma. The pathogenesis is still unknown but includes an imbalance in fibrinolysis, collagen production and inflammatory mechanisms. Little is known about the role of macrophages during adhesion formation. In an experimental model, macrophage M2 marker expression was associated with reduced peritoneal adhesion formation and involved PPAR-γ-mediated arginase activity. Macrophage-specific PPAR-γ deficiency resulted in reduced arginase activity and aggravated adhesion formation. Pioglitazone, a PPAR-γ agonist, induced M2 polarization and reduced postoperative adhesion formation without compromising anastomotic healing in mice. Pioglitazone ameliorated postoperative adhesion formation without compromising intestinal wound healing. Therefore, perioperative PPAR-γ agonism might be a promising strategy for prevention of adhesion formation after abdominal surgery.

[Intestinal obstruction secondary to postoperative adhesion formation in abdominal surgery. Review]

The development of intestinal obstruction after upper and lower abdominal surgery is part of the daily life of each every surgeon. Despite this, there are very few good quality studies that allow enable assessment of the frequency of intestinal obstruction to be assessed, even although postoperative adhesions are the cause of considerable direct and indirect morbidity and its prevention can be considered a public health problem. And yet, in Mexico, at this time, there is no validated recommendation validated on the prevention of adhesions, or more particularly, in connection with the use of a variety of anti-adhesion commercial products which have been marketed for at least a decade. Intraperitoneal adhesions develop between surfaces without peritoneum of the abdominal organs, mesentery, and abdominal wall. The most common site of adhesions is between the greater omentum and anterior abdominal wall previous. Despite the frequency of adhesions and their direct and indirect consequences, just there is only one published a recommendation (from gynaecological literature), regarding peritoneal adhesion prevention. As regards of colorectal surgery, performed more than 250,000 colorectal resections are performed annually in the United States, and from 24% to 35% of them will develop a complication. The clinical and economic financial burden of these complications is enormous, and surgeries colorectal surgery been specifically highlighted as a potential point prevention point of surgical morbidity.

Percutaneous radiofrequency ablation of hepatic tumours: factors affecting technical failure of artificial ascites formation using an angiosheath

AIM

To evaluate the technical feasibility of artificial ascites formation using an angiosheath before percutaneous radiofrequency ablation (RFA) for hepatic tumours and to determine predictive factors affecting the technical failure of artificial ascites formation.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board. One hundred and thirteen patients underwent percutaneous RFA of hepatic tumours after trying to make artificial ascites using an angiosheath to avoid collateral thermal damage. The technical success rate of making artificial ascites using an angiosheath and conversion rate to other techniques after initial failure of making artificial ascites were evaluated. The technical success rate for RFA was assessed. In addition, potential factors associated with technical failure including previous history of transcatheter arterial chemoembolization (TACE) or RFA, type of abdominal surgery, and adjacent perihepatic structures were reviewed. Predictive factors for the technical failure of artificial ascites formation were analysed using multivariate analysis.

RESULTS

The technical success rates of artificial ascites formation by angiosheath and that of RFA were 84.1% (95/113) and 97.3% (110/113), respectively. The conversion rate to other techniques after the failure of artificial ascites formation using an angiosheath was 15.9% (18/113). Previous hepatic resection was the sole independent predictive factor affecting the technical failure of artificial ascites formation (p<0.001, odds ratio = 29.03, 95% confidence interval: 4.56-184.69).

CONCLUSION

Making artificial ascites for RFA of hepatic tumours using an angiosheath was technically feasible in most cases. However, history of hepatic resection was a significant predictive factor affecting the technical failure of artificial ascites formation.

The neurokinin 1 receptor regulates peritoneal fibrinolytic activity and postoperative adhesion formation

BACKGROUND

Intra-abdominal adhesions are a common source of postoperative morbidity. Previous studies in our laboratory have shown that a neurokinin 1 receptor antagonist (NK-1RA) reduces abdominal adhesion formation and increases peritoneal fibrinolytic activity. However, the cellular pathway by which the antagonist exerts its effects is unclear, as cultured peritoneal mesothelial cells exposed to the NK-1RA show increases in fibrinolytic activity despite having very low expression of neurokinin 1 receptor (NK-1R) messenger RNA and protein. Our aim was to determine whether the NK-1R plays an essential role in the adhesion-reducing effects of the NK-1RA, or if the NK-1RA is acting independently of the receptor.

METHODS

Homozygous NK-1R knockout mice and age matched wild-type mice underwent laparotomy with cecal cautery to induce adhesions. At the time of surgery, mice received a single intraperitoneal dose of either NK-1RA (25 mg/kg) or saline alone. Adhesion severity at the site of cecal cautery was assessed on postoperative day 7. In a separate experiment, peritoneal fluid was collected from wild type and NK-1R knockout mice 24 h after laparotomy with cecal cautery and administration of either NK-1RA or saline. Tissue plasminogen activator levels, representative of total fibrinolytic activity, were then measured in peritoneal fluid.

RESULTS

In wild-type mice, NK-1RA administration significantly decreased adhesion formation compared with saline controls. Among the NK-1R knockout mice, there was no significant reduction in adhesion formation by the NK-1RA. Fibrinolytic activity increased 244% in wild-type mice administered NK-1RA compared with saline controls; however, the NK-1RA did not raise fibrinolytic activity above saline controls in NK-1R knockout mice.

CONCLUSIONS

These data indicate that the NK-1R mediates the adhesion-reducing effects of the NK-1RA, in part, by the upregulation of peritoneal fibrinolysis, and suggest that the NK-1R is a promising therapeutic target for adhesion prevention.

Standardised models for inducing experimental peritoneal adhesions in female rats

Animal models for adhesion induction are heterogeneous and often poorly described. We compare and discuss different models to induce peritoneal adhesions in a randomized, experimental in vivo animal study with 72 female Wistar rats. Six different standardized techniques for peritoneal trauma were used: brushing of peritoneal sidewall and uterine horns (group 1), brushing of parietal peritoneum only (group 2), sharp excision of parietal peritoneum closed with interrupted sutures (group 3), ischemic buttons by grasping the parietal peritoneum and ligating the base with Vicryl suture (group 4), bipolar electrocoagulation of the peritoneum (group 5), and traumatisation by electrocoagulation followed by closure of the resulting peritoneal defect using Vicryl sutures (group 6). Upon second look, there were significant differences in the adhesion incidence between the groups (P < 0.01). Analysis of the fraction of adhesions showed that groups 2 (0%) and 5 (4%) were significantly less than the other groups (P < 0.01). Furthermore, group 6 (69%) was significantly higher than group 1 (48%) (P < 0.05) and group 4 (47%) (P < 0.05). There was no difference between group 3 (60%) and group 6 (P = 0.2). From a clinical viewpoint, comparison of different electrocoagulation modes and pharmaceutical adhesion barriers is possible with standardised models.

Biodegradable and thermosensitive micelles inhibit ischemia-induced postoperative peritoneal adhesion

Ischemia-induced adhesion is very common after surgery, and leads to severe abdominal adhesions. Unfortunately, many existing barrier agents used for adhesion prevention have only limited success. The objective of this study is to evaluate the efficacy of biodegradable and thermosensitive poly(ε-caprolactone)–poly(ethylene glycol)–poly(ε-caprolactone) (PCL–PEG–PCL) micelles for the prevention of postoperative ischemia-induced adhesion. We found that the synthesized PCL–PEG–PCL copolymer could self-assemble in an aqueous solution to form micelles with a mean size of 40.1±2.7 nm at 10°C, and the self-assembled micelles could instantly turn into a nonflowing gel at body temperature. In vitro cytotoxicity tests suggested that the copolymer showed little toxicity on NIH-3T3 cells even at amounts up to 1,000 μg/mL. In the in vivo test, the postsurgical ischemic-induced peritoneal adhesion model was established and then treated with the biodegradable and thermosensitive micelles. In the control group (n=12), all animals developed adhesions (mean score, 3.58±0.51), whereas three rats in the micelles-treated group (n=12) did not develop any adhesions (mean score, 0.67±0.78; P<0.001, Mann–Whitney U-test). Both hematoxylin and eosin and Masson trichrome staining of the ischemic tissues indicated that the micelles demonstrated excellent therapeutic effects on ischemia-induced adhesion. On Day 7 after micelle treatment, a layer of neo-mesothelial cells emerged on the injured tissues, which confirmed the antiadhesion effect of the micelles. The thermosensitive micelles had no significant side effects in the in vivo experiments. These results suggested that biodegradable and thermosensitive PCL–PEG–PCL micelles could serve as a potential barrier agent to reduce the severity of and even prevent the formation of ischemia-induced adhesions.

Hypothermia decreases postoperative intra-abdominal adhesion formation

BACKGROUND

Hypothermia may decrease postoperative intra-abdominal adhesion. We sought to determine the most suitable temperature for hypothermia for decreasing postoperative adhesion formation.

METHODS

One hundred and twenty male BALB/c mice weighing 25 to 30 g were randomized into 5 groups: adhesion model with infusion of cold saline at (I) 15°C; (II) 10°C; or (III) 4°C; (IV) adhesion model without infusion of saline; and (V) sham operation without infusion of saline. Adhesion scores, incidence of adhesion, and serum cytokine levels were measured at postoperative days 1, 3, 7, and 14.

RESULTS

Adhesion scores among groups I, II, and III did not differ significantly. Interleukin-6 was significantly decreased in groups I, II, and III, compared to the levels in groups IV and V (P < .05). Tumor necrosis factor-α levels in groups I and II were significantly decreased compared to those in groups III, IV, and V (P < .05).

CONCLUSION

We suggest that 15°C is the appropriate temperature for induction of hypothermia to decrease postoperative intra-abdominal adhesion formation.

A Prospective Experimental Study to Investigate the Peritoneal Adhesion Formation of Argon Plasma Coagulation (APC) Versus a Novel Aerosol Plasma in a Rat Model

Background. This is a prospective, randomized, controlled, single-blinded study to investigate peritoneal adhesion formation of standard argon plasma coagulation (APC) versus aerosol plasma coagulation in a rat model. Methods. Bilateral lesions were created on the abdominal wall of 16 female Wistar rats with standard and aerosol plasma coagulation APC energy in a standard fashion. After 10 days, the rats were killed humanely to evaluate the peritoneal trauma sites. Adhesion incidence, quantity, and quality were scored 10 days postoperatively and studied histopathologically. Results. Average energy intake was 97.7 ± 3.1 J for APC and 93.8 ± 4.2 J for aerosol plasma coagulation. Incidence of adhesion formation was 74.2% for standard APC and 16.1% for aerosol plasma coagulation ( P < .0001). Standard APC mainly results in dense adhesions. Histological evaluation revealed no significant difference with regard to the average depth of lesions created by APC and aerosol plasma coagulation ( P = 0.21) at day 10; both groups showed an identical morphology of necrosis and granulation tissue formation. Conclusions. This study compares adhesion formation of standard APC versus aerosol plasma coagulation in a rat model. Standard APC produced significantly more adhesions. Aerosol plasma coagulation creates fewer adhesions, which are of lower grade, which seems to be achieved mainly by improved peritoneal conditioning in this animal model.

Practical implications of postoperative adhesions for preoperative consent and operative technique

Adhesions complicate most intra-peritoneal operations. Once adhesions have formed, patients are at life-long risk for complications that include small bowel obstruction, increased risks during subsequent operations and female infertility. This has two implications for the daily work of surgeons. On the one hand, surgeons need to include the risks from adhesions during pre-operative consent. On the other hand, surgeons need to use operative techniques that minimize adhesions. Therefore this review focuses on the practical implications of adhesions for preoperative consent and operative technique.

Local tissue ischemia is not necessary for suture-induced adhesion formation

BACKGROUND

We investigated the hypothesis that local tissue ischemia is responsible for suture-induced adhesion formation.

METHODS

A total of 160 interrupted sutures were placed in the parietal peritoneum of 20 Wistar rats. The animals were randomized into an ischemia group, where the sutures were pulled tight and a non-ischemia group, where the sutures were tied as loose loops with air knots to avoid any local ischemia. The midline laparotomy was closed with a running suture. On postoperative day 10, adhesions to the sutures were counted.

RESULTS

There was no statistically significant difference in the number of adhesions forming to sutures with local ischemia (n = 66/80) versus sutures without local ischemia (n = 69/80).

CONCLUSION

We conclude that local tissue ischemia is not necessary for suture-induced adhesion formation and propose an additional mechanical mechanism to explain how suture knots can predispose to adhesiogenesis.

An involvement of neurokinin-1 receptor in FcεRΙ-mediated RBL-2H3 mast cell activation

OBJECTIVE AND DESIGN

To determine whether the neurokinin-1 receptor (NK1R) plays a role in the activation of RBL-2H3 mast cells after FcεRΙ aggregation.

MATERIALS AND METHODS

NK1R expression in RBL-2H3 cells was inhibited by small hairpin RNA (shRNA) against NK1R, and determined by western blotting. For activation, both NK1R knockdown and control RBL-2H3 cells were sensitized by dinitrophenol (DNP)-specific IgE and stimulated with the antigen DNP-bovine serum albumin (BSA). Following the activation of RBL-2H3 cells, monocyte chemoattractant protein (MCP-1) production and intracellular calcium flux were monitored by ELISA and confocal microscopy assay, respectively. For investigation of the signaling mechanism, phosphorylation of mitogen-activated protein kinases (MAPKs) after RBL-2H3 cell activation was assessed by western blotting.

RESULTS

shRNA-NK1R mediated an effective inhibition of NK1R expression in RBL-2H3 cells. Protein production of MCP-1 was reduced by more than 55 % in NK1R knockdown RBL-2H3 cells compared with control RBL-2H3 cells. In addition, both calcium mobilization and phosphorylation levels of MAPKs (Erk1/2, JNK, and p38) after DNP-BSA stimulation (via FcεRΙ) were decreased due to the inhibition of NK1R expression.

CONCLUSION

NK1R is required for the activation of RBL-2H3 cells following FcεRΙ engagement and involved in the regulation of MAPK signaling pathways.

Current strategies and future perspectives for intraperitoneal adhesion prevention

INTRODUCTION

The formation of peritoneal adhesions still is a relevant clinical problem after abdominal surgery. Until today, the most important clinical strategies for adhesion prevention are accurate surgical technique and the physical separation of traumatized serosal areas. Despite a variety of barriers which are available in clinical use, the optimal material has not yet been found.

DISCUSSION

Mesothelial cells play a crucial physiological role in friction less gliding of the serosa and the maintenance of anantiadhesive surface. The formation of postoperative adhesions results from a cascade of events and is regulated by various cellular and humoral factors. Therefore, optimization or functionalization of barrier materials by developments interacting with this cascade on a structural or pharmacological level could give an innovative input for future strategies in peritoneal adhesion prevention. For this purpose, the proper understanding of the formal pathogenesis of adhesion formation is essential. Based on the physiology of the serosa and the pathophysiology of adhesion formation, the available barriers in current clinical practice as well as new innovations are discussed in the present review.

A sprayable hyaluronate/carboxymethylcellulose adhesion barrier exhibits regional adhesion reduction efficacy and does not impair intestinal healing

BACKGROUND

While bioresorbable solid barriers such as Seprafilm® prevent adhesions, their efficacy is limited to sites of application. The aim of this study was to assess the effectiveness of the sprayable adhesion barrier Sepraspray® in preventing adhesions to sites of direct application and to remote sites.

METHODS

Intraabdominal adhesions were induced in 30 rats by creating three ischemic buttons on each side of a midline incision. To assess efficacy, Sepraspray (5 mg/button) or Seprafilm (1 cm(2)/button) was applied over three buttons on one side of the peritoneum. Operated control animals received no treatment. On day 7, adhesions were scored as percent of buttons with adhesions. To assess safety, 81 rats underwent a colonic transection repaired with an end-to-end anastomosis. Both barriers were applied circumferentially to anastomoses. Controls received no product. The integrity of healing anastomosed colonic wounds was assessed by burst pressure and tensile strength at days 3, 5, and 7 postoperatively.

RESULTS

The direct application of both Sepraspray and Seprafilm significantly (p < 0.001) reduced adhesion formation compared to controls. While Seprafilm had no remote effect on adhesion formation, Sepraspray significantly (p < 0.001) reduced adhesion formation to contralateral ischemic buttons. Neither barrier affected anastomotic integrity at any time point.

CONCLUSIONS

Sepraspray has widespread efficacy throughout the peritoneum in reducing adhesions without compromising intestinal healing. Furthermore, this sprayable alternative offers the potential for easier intraabdominal application.

Prevention of postoperative peritoneal adhesions: a review of the literature

BACKGROUND

postoperative adhesions are a significant health problem with major implications on quality of life and health care expenses. The purpose of this review was to investigate the efficacy of preventative techniques and adhesion barriers and identify those patients who are most likely to benefit from these strategies.

METHODS

the National Library of Medicine, Medline, Embase, and Cochrane databases were used to identify articles related to postoperative adhesions.

RESULTS

ileal pouch-anal anastomosis, open colectomy, and open gynecologic procedures are associated with the highest risk of adhesive small-bowel obstruction (class I evidence). Based on expert opinion (class III evidence) intraoperative preventative principles, such as meticulous hemostasis, avoiding excessive tissue dissection and ischemia, and reducing remaining surgical material have been published. Laparoscopic techniques, with the exception of appendicitis, result in fewer adhesions than open techniques (class I evidence). Available bioabsorbable barriers, such as hyaluronic acid/carboxymethylcellulose and icodextrin 4% solution, have been shown to reduce adhesions (class I evidence).

CONCLUSIONS

postoperative adhesions are a significant health problem with major implications on quality of life and health care. General intraoperative preventative techniques, laparoscopic techniques, and the use of bioabsorbable mechanical barriers in the appropriate cases reduce the incidence and severity of peritoneal adhesions.

Intra-abdominal adhesions: definition, origin, significance in surgical practice, and treatment options

BACKGROUND

Intra-abdominal adhesions arise after more than 50% of all abdominal operations and are an important source of postoperative complications. They attach normally separated organs to each other and can cause major problems for the affected patients by giving rise to small bowel obstruction, chronic pelvic pain, dyspareunia, infertility, and higher complication rates in subsequent operations. They are also a frequent source of medicolegal conflict. Thus, every physician should be familiar with their mechanism of origin, their consequences, and the methods by which they can be prevented.

METHODS

A selective PubMed/Medline search from 1960 onward as well as articles to which these publications referred. The expert consensus position of the European Society for Gynaecological Surgery is also taken into consideration.

RESULTS

Adhesions arise through aberrant wound healing after peritoneal injury with further influence from a variety of other factors. Preventive measures include minimizing peritoneal injury intraoperatively through the meticulous observance of basic surgical principles, moistening the mesothelium to keep it from drying out, irrigating the peritoneal cavity to remove blood and clot, and keeping the use of intra-abdominal foreign material to a minimum.

CONCLUSION

Adhesions are an inevitable consequence of intra-abdominal surgery. They can be prevented to some extent with meticulous surgical technique and certain other measures. For operations carrying a high risk of postoperative adhesions, e.g., surgery on the adnexa or bowel, commercially available peritoneal instillates or barrier methods can be used to limit adhesion formation.

Open adhesiolysis is more effective in reducing adhesion reformation than laparoscopic adhesiolysis in an experimental model

BACKGROUND

This study compared adhesion reformation after open and laparoscopic adhesiolysis in a rat model.

METHODS

Adhesions were induced by surgically creating ischaemic buttons on the peritoneal side wall. After 7 days the animals underwent laparoscopy with carbon dioxide insufflation or laparotomy to score and lyse adhesions. Peritoneal tissue and fluid were collected after 24 h in a subset of animals, and adhesion reformation was scored 7 days after lysis in the remainder. Tissue plasminogen activator (tPA), plasminogen activator inhibitor (PAI) 1, transforming growth factor (TGF) beta1 and tumour necrosis factor (TNF) alpha mRNA, and total fibrinolytic activity were assessed. The abdomen of non-operated animals was insufflated for 7, 15 or 30 min with carbon dioxide, after which tPA and PAI-1 mRNA and total fibrinolytic activity were measured.

RESULTS

Animals that underwent open adhesiolysis had 60 per cent fewer reformed adhesions than the laparoscopic adhesiolysis group (P < 0.001). There were no differences in tPA activity or tPA, PAI-1 and TNF-alpha mRNA between groups, but TGF-beta1 mRNA levels were significantly increased in the open group. Carbon dioxide insufflation did not affect peritoneal tPA activity.

CONCLUSION

Open adhesiolysis may be more beneficial in minimizing adhesion reformation in the management of adhesion-related complications.

High rectal injury during trans-1 axial lumbar interbody fusion L5-S1 fixation: a case report

STUDY DESIGN

A case report.

OBJECTIVE

To report a case of high rectal injury during trans-1 axial Lumbar Interbody Fusion (axiaLIF) L5-S1 fixation.

SUMMARY OF BACKGROUND DATA

Trans-1 axiaLIF procedure is gaining in popularity for L5-S1 fusion due to the ease of access to the sacrum through the presacral space. Normally, the midline of the sacrum at S1-S2 is relatively free from neurovascular and intra-abdominal structures, making this level a safe entry point for the axiaLIF procedure. We report a case of high rectal injury during Trans-1 axiaLIF L5-S1 procedure due to altered intra-abdominal anatomy as a result of multifactorial adhesions formation.

METHODS

A 44-year-old female patient with a history of previous anterior and posterior spinal surgeries, pelvic inflammatory disease, and non-disclosed previous diverticulitis, developed a high rectal injury during Trans-1 axiaLIF L5-S1 fixation.

RESULTS

After Trans-1 axiaLIF L5-S1, the patient presented with an episode of melena and hypogastric pain with nausea and vomiting. A computed tomography (CT) scan of the abdomen with intravenous and oral contrast showed presacral soft tissue fluid density with fat stranding and extraluminal rectal contrast and gas with some areas of soft tissue enhancement compatible with probable high rectal perforation. Patient's symptoms gradually subsided during a period of 6 months with aid from a temporary diverting ileostomy and a course of i.v. antibiotics. No spine implants were removed.

CONCLUSION

We report a case of high rectal injury during Trans-1 axiaLIF L5-S1 fixation and strongly advice that patients who are candidates for this surgery and have any risk factors for intra-abdominal adhesion formation, undergo a pelvic CT with rectal contrast before the surgery to evaluate for any signs of altered rectal-sacral anatomy.

Practical limitations of bioresorbable membranes in the prevention of intra-abdominal adhesions

INTRODUCTION

Intra-abdominal adhesions are a significant source of postoperative morbidity. Bioresorbable barriers composed of hyaluronic acid and carboxymethylcellulose (HA/CMC) reduce adhesion formation by physically separating injured or healing peritoneal surfaces. To assess whether the efficacy of a physical barrier can extend beyond the site of application, we evaluated the effectiveness of an HA/CMC barrier in preventing adhesions distal to the site of placement.

METHODS

Adhesions were induced in rats by creating peritoneal ischemic buttons on either side of a midline incision. An HA/CMC barrier (Seprafilm Genzyme) was intraoperatively placed either under the midline incision, unilaterally over half the ischemic buttons, or bilaterally over all ischemic buttons. Control buttons received no HA/CMC. On day 7 adhesions were scored. In similar experiments, peritoneal fluid was collected at 24 h to assess the effects of HA/CMC on tissue plasminogen activator activity.

RESULTS

Placement of HA/CMC under the midline incision did not reduce adhesion formation to distal ischemic buttons (72 +/- 7%) compared to controls (80 +/- 8%). Unilateral placement of HA/CMC significantly (p < 0.05) reduced adhesion formation to those ischemic buttons over which the barrier was applied (35 +/- 7%) compared to both contralateral (83 +/- 9%) and control (80 +/- 8%) ischemic buttons. The bilateral application of HA/CMC also significantly (p < 0.05) reduced adhesion formation to all ischemic buttons compared to controls (22 +/- 7% vs. 66 +/- 7%, respectively). HA/CMC did not affect peritoneal tPA activity.

CONCLUSIONS

Effective adhesion reduction by the physical barrier HA/CMC appears to be limited to the site of application in this rat model. Despite the presence of a bioresorbable membrane at predicted sites of adhesion formation in the peritoneal cavity, adhesions readily form to distal unprotected sites.

Estrogen replacement therapy prevents airway dysfunction in a murine model of allergen-induced asthma

We previously reported that 17beta-estradiol (E2) prevents hyperresponsiveness to carbachol of murine asthmatic tracheal rings in vitro. We now investigated whether E2 is similarly effective in reducing airway hyperreactivity in a murine model of allergic asthma in vivo. Female ovariectomized BALB/c mice were rendered asthmatic by a 25-day protocol of sensitization to ovalbumin. Under positive-pressure ventilation, anesthetized asthmatic mice exhibited a dramatic increase in airway responsiveness to increasing doses of inhaled methacholine compared to PBS-sensitized controls, as reflected in decreased dynamic compliance of the respiratory system and increased tissue damping, tissue elastance, and airway resistance. Furthermore, asthmatic mice exhibited hypercellularity and increased protein concentration in the bronchoalveolar lavage, strong signs of peribronchial cuffing with inflammatory cells and increased goblet cell activity. To test the effects of estrogen, three additional groups of mice were implanted subcutaneously with different amounts of slow-release E2 pellets at the time of ovariectomy and rendered asthmatic as before. E2 dose-dependently inhibited airway hyperresponsiveness to methacholine, reduced bronchoalveolar lavage hypercellularity, and virtually eliminated histologic signs of inflammation and goblet cell hyperactivity. The inflammation and airway hyperactivity in asthmatic mice was associated with an increase in bronchoalveolar lavage levels of TGFbeta1, which was completely abolished in E2-treated asthmatic mice. We conclude that estrogen replacement therapy effectively ameliorates the pathologic profile of murine allergic asthma.

An FDA approved neurokinin-1 receptor antagonist is effective in reducing intraabdominal adhesions when administered intraperitoneally, but not orally

INTRODUCTION

Postoperative adhesions pose a continued healthcare problem. We previously demonstrated that intraperitoneal (i.p.) administration of a neurokinin-1 receptor antagonist (NK-1RA) at surgery reduces intraabdominal adhesions in rats. The NK-1RA aprepitant (Emend, Merck) is clinically approved for preventing postoperative nausea and vomiting; however, its effects on adhesion formation are unknown. Thus, we determined the effects of i.p. and oral administration of aprepitant on adhesion formation in a rat model.

METHODS

Adhesions were surgically induced in rats that were randomized to receive either one or five oral preoperative doses or a single intraoperative i.p. dose of aprepitant (50 mg/kg). Adhesions were scored at 7 days. In similar experiments using i.p. dosing, animals were sacrificed at 24 h and peritoneal fluid, and tissue were collected to assess fibrinolytic activity and tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) mRNA levels, respectively.

RESULTS

I.p. aprepitant reduced adhesion formation by 33% (p < 0.05) compared with controls while oral aprepitant had no effect. Compared to controls i.p. aprepitant reduced tPA activity by 55% (p < 0.05), increased PAI-1 mRNA levels by 140% (p < 0.05), and had no affect on tPA mRNA levels.

CONCLUSION

These data suggest that aprepitant maybe a useful pharmacologic agent for reducing adhesion formation clinically.