Pathophysiology of intra-abdominal adhesion and abscess formation, and the effect of hyaluronan

Advanced postoperative tissue antiadhesive membranes enabled with electrospun nanofibers

Tissue adhesion is one of the most common postoperative complications, which is frequently accompanied by inflammation, pain, and even dyskinesia, significantly reducing the quality of life of patients. Thus, to prevent the formation of tissue adhesions, various strategies have been explored. Among these methods, placing anti-adhesion membranes over the injured site to separate the wound from surrounding tissues is a simple and prominently favored method. Recently, electrospun nanofibers have been the most frequently investigated antiadhesive membranes due to their tunable porous structure and high porosities. They not only can act as an essential barrier and functional carrier system but also allow for high permeability and nutrient transport, showing great potential for preventing tissue adhesion. Herein, we provide a short review of the most recent applications of electrospun nanofibrous antiadhesive membranes in tendons, the abdominal cavity, dural sac, pericardium, and meninges. Firstly, each section highlights the most representative examples and they are sorted based on the latest progress of related research. Moreover, the design principles, preparation strategies, overall performances, and existing problems are highlighted and evaluated. Finally, the current challenges and several future ways to develop electrospun nanofibrous antiadhesive membranes are proposed. The systematic discussion and proposed directions can shed light on ideas and guide the reasonable design of electrospun nanofibrous membranes, contributing to the development of exceptional tissue anti-adhesive materials in the foreseeable future.

Challenges and opportunities of medicines for treating tendon inflammation and fibrosis: A comprehensive and mechanistic review

BACKGROUND

Tendinopathy refers to conditions characterized by collagen degeneration within tendon tissue, accompanied by the proliferation of capillaries and arteries, resulting in reduced mechanical function, pain, and swelling. While inflammation in tendinopathy can play a role in preventing infection, uncontrolled inflammation can hinder tissue regeneration and lead to fibrosis and impaired movement.

OBJECTIVES

The inability to regulate inflammation poses a significant limitation in tendinopathy treatment. Therefore, an ideal treatment strategy should involve modulation of the inflammatory process while promoting tissue regeneration.

METHODS

The current review article was prepared by searching PubMed, Scopus, Web of Science, and Google Scholar databases. Several treatment approaches based on biomaterials have been developed.

RESULTS

This review examines various treatment methods utilizing small molecules, biological compounds, herbal medicine-inspired approaches, immunotherapy, gene therapy, cell-based therapy, tissue engineering, nanotechnology, and phototherapy.

CONCLUSION

These treatments work through mechanisms of action involving signaling pathways such as transforming growth factor-beta (TGF-β), mitogen-activated protein kinases (MAPKs), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), all of which contribute to the repair of injured tendons.

Effects of composition and pH on the degradation of hyaluronate and carboxymethyl cellulose gels and release of nanocrystalline silver

Adhesions are fibrous tissue connections which are a common complication of surgical procedures and may be prevented by protecting tissue surfaces and reducing inflammation. The combination of biodegradable polymers and nanocrystalline silver can be used to create an anti-inflammatory gel to be applied during surgery. In this study, sodium hyaluronate and sodium carboxymethyl cellulose were added in concentrations from 0.25% to 1% w/v to aqueous nanocrystalline silver solutions to create viscous gels. Gels were loaded into dialysis cassettes and placed in PBS for 3 days. pH was adjusted using potassium phosphate monobasic and sodium hydroxide. Release of silver into the PBS was measured at several time points. Polymer degradation was compared by measuring the viscosity of the gels before and after the experiment. Gels lost up to 84% of initial viscosity over 3 days and released between 24% and 41% of the added silver. Gels with higher initial viscosity did not have a greater degree of degradation, as measured by percent viscosity reduction, but still resulted in a higher final viscosity. Silver release was not significantly impacted by pH or composition, but still varied between experimental groups.

The effect of natural surfactants on the development of postoperative intraabdominal adhesion

Background/aim

The development of postoperative adhesion after abdominal surgery is sometimes a severe problem. Our study investigates the effectiveness of exogenous surfactant application in preventing adhesion development in the experimental adhesion model.

Materials and methods

This randomized-controlled interventional study was carried out in the animal laboratory of Kahramanmaraş Sütçü İmam University between March 1 and March 31, 2020. An experimental intra-abdominal adhesion model was established in 24 adult female rats by cecal abrasion. Rats were randomly divided into four groups. Groups I, II, and III were taken intraperitoneally as beractant, poractant, and calfactant applied groups, respectively. Group IV was the control group. Relaparotomy was performed in all groups on the 15th postoperative day, and intra-abdominal adhesions were scored macroscopically according to the Canbaz scoring system. In addition, the cecal regions were evaluated microscopically and scored according to the Zühlke microscopic classification system. The scores of the groups were compared statistically.

Results

The Zühlke adhesion development score was significantly lower in the exogenous surfactant applied groups. In addition, when the surfactant-applied groups were compared among themselves, it was seen that the adhesion score in the beractant group was significantly better than the other surfactant types (p < 0.01).

Conclusion

Our study results showed that prophylactic intraperitoneal surfactant application significantly reduced postoperative adhesion development, particularly beractant.

Adhesive Small Bowel Obstruction: A Review

Adhesion is a leading cause of small bowel obstruction. Adhesive small bowel obstruction has significant challenges in diagnosis, treatment and prevention with considerable impact on morbidity and socioeconomic burden. Small bowel obstruction caused by adhesion or any other aetiology is clinically indistinguishable due to similar clinical presentation. Computed Tomography scans and water-soluble contrast studies are more specific in diagnosis and possess value in predicting the need for surgery. Surgical management is indicated only in complicated cases or failed conservative treatments with the majority resolving with non-operative management. However, there is no clear-cut consensus about the timing of operative intervention. Meticulous surgical practice is the keystone in preventing adhesion formation despite the availability of numerous pharmacological and surgical strategies. This review aims to update the current knowledge of the pathophysiology of adhesion formation, treatment options and various prevention modalities of adhesive small bowel obstruction.

KEYWORDS

diagnosis; laparotomy; prevention; surgery.

Novel silk protein/hyaluronic acid hydrogel loaded with azithromycin as an immunomodulatory barrier to prevent postoperative adhesions

Peritoneal adhesions, a common postoperative complication of laparotomy, are still treated with physical barriers, but their efficacy and ease of use are controversial. In this paper, we developed a wound microenvironment-responsive hydrogel composed of Antheraea pernyi silk protein (ASF) from wild cocoons and tyramine-modified hyaluronic acid (HA-Ph) loaded with azithromycin (AZI), glucose oxidase (GOX), and horseradish peroxidase (HRP). In addition, GOX-catalyzed oxygen production enhanced the antibacterial ability of the hydrogel. Moreover, the drug-loaded hydrogel increased macrophage CD206 expression while decreasing IL-6 and TNF-α expression. More importantly, the retarding effect of this novel hydrogel system on AZI almost eliminated the appearance of postoperative adhesions in rats. It was also found that the novel hydrogel enhanced the modulation of the TLR-4/Myd88/NF-κB pathway and TGF-β/Smad2/3 pathway by azithromycin in the locally damaged peritoneum of rats, which accelerated the remodeling of damaged tissues and dramatically reduced the deposition of collagen. Therefore, spraying the novel drug-loaded hydrogel on postoperative abdominal wounds can effectively inhibit the formation of postoperative adhesions.

Lacticaseibacillus rhamnosus dfa1 Attenuate Cecal Ligation-Induced Systemic Inflammation through the Interference in Gut Dysbiosis, Leaky Gut, and Enterocytic Cell Energy

Despite an uncommon condition, the clinical management of phlegmon appendicitis (retention of the intra-abdominal appendiceal abscess) is still controversial, and probiotics might be partly helpful. Then, the retained ligated cecal appendage (without gut obstruction) with or without oral Lacticaseibacillus rhamnosus dfa1 (started at 4 days prior to the surgery) was used as a representative model. At 5 days post-surgery, the cecal-ligated mice demonstrated weight loss, soft stool, gut barrier defect (leaky gut using FITC-dextran assay), fecal dysbiosis (increased Proteobacteria with reduced bacterial diversity), bacteremia, elevated serum cytokines, and spleen apoptosis without kidney and liver damage. Interestingly, the probiotics attenuated disease severity as indicated by stool consistency index, FITC-dextran assay, serum cytokines, spleen apoptosis, fecal microbiota analysis (reduced Proteobacteria), and mortality. Additionally, impacts of anti-inflammatory substances from culture media of the probiotics were demonstrated by attenuation of starvation injury in the Caco-2 enterocyte cell line as indicated by transepithelial electrical resistance (TEER), inflammatory markers (supernatant IL-8 with gene expression of TLR4 and NF-κB), cell energy status (extracellular flux analysis), and the reactive oxygen species (malondialdehyde). In conclusion, gut dysbiosis and leaky-gut-induced systemic inflammation might be helpful clinical parameters for patients with phlegmon appendicitis. Additionally, the leaky gut might be attenuated by some beneficial molecules from probiotics.

Synthesis and Characterization of Hydrogel-Based Hyaluronic Acid-Chitosan-Allium sativum Extract for Intraperitoneal Antiadhesion Application

Peritoneal Adhesion is a severe case that frequently occurs in patients after laparotomy surgery. Adhesions are pathological attachment that usually appears between the omentum, intestine, and abdominal wall. Several barriers are made to prevent adhesions, including liquid barriers such as sodium hyaluronate and carboxymethyl cellulose (CMC) but are fast absorbed-time hydrogel. The solid barrier has weakness of difficulty in covering all parts of the wound surface. The study aims to synthesize degradable hydrogel from N,O-Carboxymethyl Chitosan (NOCC), Aldehyde-Hyaluronic Acid, and the addition of Allium sativum (garlic oil). The best sample with the concentration of A-HA/NOCC 30 : 10 g/ml was obtained. The composite hydrogel of NOCC/AHA/Allium sativum has susceptible antimicrobial properties. In vitro cytotoxicity assay showed that hydrogel is nontoxic. The degradation time is for two weeks. The in vivo evaluation in a mouse model with an abrasion defect side was done to identify the effectiveness of the NOCC/AHA/A. sativum as antiperitoneal adhesion. Seven days after surgery, the observation of adhesion was performed. Based on all assay results, it can be resumed that the NOCC/AHA/A. sativum hydrogel possibly acts as an innovation to prevent postoperative intraperitoneal adhesion.

A nano chitosan membrane barrier prepared via Nanospider technology with non-toxic solvent for peritoneal adhesions' prevention

Peritoneal adhesion is one of the most common postsurgical complications and can cause bowel obstruction, pelvic pain, and infertility. Setting up a physical barrier directly between the injured site and surrounding tissues is an effective solution for preventing this adverse situation. This study investigated a chitosan electrospun membrane (CSEM) as a potent anti-adhesion barrier, which was prepared by a needleless technology called Nanospider. Scanning electron microscopy revealed that CSEM is a laminated nanofiber with good mechanical properties. The fiber is uniform with the diameter distributing in the range of 100-120 nm. The tensile strength can reach 27.45 ± 6.30 MPa with a maximum elongation at break of 18.50 ± 1.44%, which makes it stick easily to damaged parts but not to be easily damaged by tissue friction. The growth of S. aureus on CSEM was 59.18% lower than the control at 10 h, which indicates its better antibacterial property. In addition, CSEM has good coagulant and biocompatibility characteristics. It can perform hemostatic function within 10 min and the L929 mouse fibroblast viability on it was 92.18% ± 1.08% on the seventh day. In vivo experiments indicated that CSEM significantly prevented peritoneal adhesions within four weeks after surgery with wound surface coverage. These results indicate that CSEM is a promising anti-adhesion barrier material.

Therapeutic Effects of Hyaluronic Acid in Peritonitis-Induced Sepsis in Mice

Intra-abdominal infection is the second most common cause of sepsis, and the mortality rate from abdominal sepsis remains high. High molecular weight (HMW) hyaluronic acid (HA) has been studied in sterile injury models as an anti-inflammatory and anti-permeability agent. This study evaluated the therapeutic effects of intraperitoneal HMW HA administration in mice with peritonitis-induced sepsis. Sepsis was induced in C57BL/6 mice by cecal ligation and puncture (CLP), followed 4 h later by an intraperitoneal injection of HMW HA (20 mg/kg) solution or phosphate buffered saline (PBS). Survival, physiological data, organ injury, bacterial burden, and inflammatory cytokine levels were assessed in the CLP mice. To assess the effect of HA on macrophage phagocytosis activity, RAW264.7 cells, primed with lipopolysaccharide, were exposed with either PBS or HMW HA (500 μg/mL) prior to exposure to 10 CFU of E coli bacteria. HMW HA instillation significantly improved blood oxygenation, lung histology, and survival in CLP mice. Inflammatory cytokine levels in the plasma and bacterial burdens in the lung and spleen were significantly decreased by HA administration at 24 h after CLP. At 6 h after CLP, HA significantly decreased bacterial burden in the peritoneal lavage fluid. HMW HA administration significantly increased E coli bacterial phagocytosis by RAW264.7 cells in part through increased phosphorylation of ezrin/radixin/moesin, a known downstream target of CD44 (a HA receptor); ezrin inhibition abolished the enhanced phagocytosis by RAW264.7 cells induced by HA. Intraperitoneal administration of HMW HA had therapeutic effects against CLP-induced sepsis in terms of suppressing inflammation and increasing antimicrobial activity.

Postoperative peritoneal adhesion: an update on physiopathology and novel traditional herbal and modern medical therapeutics

Postoperative peritoneal adhesion (PPA) is a serious clinical condition that affects the high percentage of patients after abdominal surgery. In this review, we have tried to focus on pathophysiology and different underlying signal pathways of adhesion formation based on recent progress in the molecular and cellular mechanisms. Also, the strategies, developed based on traditional herbal and modern medicines, to prevent and treat the PPA via regulation of the molecular mechanisms were investigated. The search engines such as Google Scholar, PubMed, Scopus, and Science Direct have been used to evaluate the current literature related to the pathogenesis of adhesion formation and novel products. Recently, different mechanisms have been defined for adhesion formation, mainly categorized in fibrin formation and adhesion fibroblast function, inflammation, and angiogenesis. Therefore, the suppression of these mechanisms via traditional and modern medicine has been suggested in several studies. While different strategies with encouraging findings have been developed, most of the studies showed contradictory results and were performed on animals. The herbal products have been introduced as safe and effective agent which can be considered in future preclinical and clinical studies. Although a wide range of therapeutics based on traditional and modern medicines have been suggested, there is no agreement in the efficacy of these methods to prevent or treat adhesion formation after surgeries. Further basic and clinical researches are still needed to propose the efficiency of recommended strategies for prevention and treatment of PPA.

Ovarian size as a risk factor for recurrent adnexal torsion: Smaller is not better

AIM

To investigate characteristics and risk factors for recurrent adnexal torsion (AT).

METHODS

Retrospective cohort study in a university-affiliated medical center included 320 Women with AT verified by laparoscopy, from January 2005 through January 2017. Demographic data, clinical symptoms, surgical findings and treatment were retrospectively reviewed from patient records. Data from primary and secondary AT of patients in the recurrent torsion group was compared to those with single torsion, to evaluate risk factors for recurrent AT.

RESULTS

Two hundred and sixty seven (83.4%) patients had a single event of AT and 53 (16.5%) had recurrent AT. Patients with recurrent torsion had significantly fewer previous non-gynecologic surgeries (4.3% and 9.8% of the study groups vs 32.2% of the control group, P = 0.001 for both). Ovarian size was significantly smaller in the recurrent torsion groups (47.5 mm and 48.3 mm vs 63.9 mm, P = 0.045 and P = 0.012, respectively). Polycystic ovary was significantly more common in the recurrent AT group (P = 0.028 and P = 0.005), with risk ratio 4.4 (95% confidence interval, 1.66 to 11.63). Ovaries without any specific findings were also more common among recurrent AT cases (P = 0.001 for both groups). Logistic regression analysis demonstrated that smaller ovarian size is an independent risk factor for recurrent AT.

CONCLUSION

Recurrent torsion correlated with fewer previous surgeries, small ovarian mass, polycystic ovaries and ovaries without specific findings, which might indicate that additional pathophysiological factors contribute to the recurrent event. Ovarian fixation might be recommended in patients with primary torsion of normal or polycystic ovaries.

Association of Intraoperative Findings With Outcomes and Resource Use in Children With Complicated Appendicitis

Importance

The influence of disease severity on outcomes and use of health care resources in children with complicated appendicitis is poorly characterized. Adjustment for variation in disease severity may have implications for ensuring fair reimbursement and comparative performance reporting among hospitals.

Objective

To examine the association of intraoperative findings as a measure of disease severity with complication rates and resource use in children with complicated appendicitis.

Design

This retrospective cohort study used clinical data from the American College of Surgeons National Surgical Quality Improvement Program pediatric appendectomy pilot database (NSQIP-P database) and cost data from the Pediatric Health Information System database. Twenty-two children's hospitals participated in the NSQIP Pediatric Appendectomy Collaborative Pilot Project. Patients aged 3 to 18 years with complicated appendicitis who underwent an appendectomy from January 1, 2013, through December 31, 2014, were included in the study. Appendicitis was categorized in the NSQIP-P database as complicated if any of the following 4 intraoperative findings occurred in the operative report: visible hole, fibropurulent exudate in more than 2 quadrants, abscess, or extraluminal fecalith. Data were analyzed from January 1, 2013, through December 31, 2014.

Main Outcomes and Measures

Thirty-day postoperative adverse event rate, revisit rate, hospital cost, and length of stay. Multivariable regression was used to estimate event rates and outcomes for all observed combinations of intraoperative findings, with adjusting for patient characteristics and clustering within hospitals.

Results

A total of 1333 patients (58.7% boys; median age, 10 years; interquartile range, 7-12 years) were included; multiple intraoperative findings of complicated appendicitis were reported in 589 (44.2%). Compared with single findings, the presence of multiple findings was associated with higher rates of surgical site infection (odds ratio, 1.40; 95% CI, 0.95-2.06; P = .09), higher revisit rates (odds ratio, 1.60; 95% CI, 1.15-2.21; P = .005), longer length of stay (rate ratio, 1.45; 95% CI, 1.36-1.55; P < .001), and higher hospital cost (rate ratio, 1.35; 95% CI, 1.19-1.53; P < .001). Significant differences were found among different combinations of intraoperative findings for all outcomes, including a 3.6-fold difference in rates of surgical site infection (range, 7.5% for fecalith alone to 27.2% for all 4 findings; P = .002), a 2.6-fold difference in revisit rates (range, 8.9% for exudate alone to 22.9% for all 4 findings; P = .001), a 2.2-fold difference in length of stay (range, 4.0 days for exudate alone to 8.9 days for all 4 findings; P < .001), and a 2.4-fold difference in mean cumulative cost (range, $13 296 for exudate alone to $32 282 for all 4 findings; P < .001).

Conclusions and Relevance

More severe presentations of complicated appendicitis are associated with worse outcomes and greater resource use. Severity adjustment may be needed to ensure fair reimbursement and comparative performance reporting, particularly at hospitals treating underserved populations where more severe presentations are common.

The Prevention of Hepatectomy-Induced Adhesions by Bilayer Sponge Composed of Ultrapure Alginate

BACKGROUND

Adhesion formation is a critical issue in surgery, particularly in hepatectomy. The present study aimed to develop a bilayer adhesion barrier comprising alginate (Alg) of different molecular weight (Mw). It was expected that a slowly dissolving layer remains on the cut surface, functioning as a physical barrier, whereas a rapidly dissolving layer widely distributes in the peritoneal cavity to prevent de novo adhesions.

METHODS

Bilayer Alg sponges were fabricated using low Mw Alg for the upper layer and high Mw Alg for the bottom layer. The dissolution behavior of each layer was evaluated in vitro in peritoneum-like environments. We constructed a Pean crush hepatectomy-induced adhesion model in rats. The effects of the bilayer sponge on cut surface and de novo adhesions were separately evaluated in terms of their extent and grade.

RESULTS

The Alg sponge layer with low Mw dissolved faster than that with high Mw in vitro. One week after the hepatectomy, although no significant decrease in adhesion extent on the cut surface was observed in rats that received Seprafilm and Interceed, treatment with Alg bilayer sponge significantly decreased the adhesion extent to 38% of that without treatment. Moreover, a significant decrease in de novo adhesion extent was observed in the Alg bilayer sponge compared with the Interceed group.

CONCLUSIONS

The Alg bilayer sponge was effective for preventing both cut surface and de novo adhesions in the rat Pean crush hepatectomy model. The simple yet functional design of the Alg bilayer sponge can facilitate its use in future clinical practice.

Drug-loaded hyaluronic acid hydrogel as a sustained-release regimen with dual effects in early intervention of tendinopathy

Resulting from accumulative microtrauma, impaired healing and oxidative stress, tendinopathy is a debilitating and relentlessly deteriorating disease that greatly affects daily function and quality of life. Current therapy usually provides symptomatic relief only. Sufferers undergo repetitive and protracted treatment courses that rarely alter the disease process. We aim to develop a sustained-release regimen with an intrinsic therapeutic effect in tendinopathy treatment, using oxidised hyaluronic acid/adipic acid dihydrazide hydrogel (HA hydrogel) as both the drug carrier and a mitigating agent of symptoms. We show that HA hydrogel can mitigate tendinopathy changes both in vitro (mechanically induced tendinopathy model) and in vivo (collagenase-induced tendinopathy model). A potent anti-oxidative (pigallocatechin gallate) incorporated into HA hydrogel conferred an additional protective effect in both models. The results indicate that when administered early, combined medications targeting different pathogenesis pathways can resolve tendinopathy. Although facilitating the healing process and mitigating oxidative stress are promising therapeutic strategies, the most effective regimen for tendinopathy treatment has to be determined yet. The established experimental model and drug carrier system provide a platform for exploring new therapeutics against this debilitating disease.

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.

TGF-β and inflammatory blood markers in prediction of intraperitoneal adhesions

PURPOSE

Intraperitoneal adhesions (IA) develop as a consequence of the healing process in peritoneum injured during surgeries. IA might be formed after all types of surgical interventions regardless the surgical approach with a higher incidence in obese individuals. Here we determine the diagnostic power of TGF-β and blood inflammatory parameters in the prediction of IA in obese patients undergoing second surgical intervention.

MATERIALS AND METHODS

Eighty patients were divided into groups according to body mass index (BMI) values and presence of intraperitoneal adhesions (IA). Evaluation of peritoneal adhesion index (PAI), serum TGF-β and blood inflammatory parameters was performed.

RESULTS

Level of TGF-β, C-reactive protein (CRP), leukocytes, neutrophil to lymphocyte ratio and platelet to lymphocyte ratio were significantly higher in obese patients while TGF-β, CRP, and leukocytes were higher in patients with IA. There was a significant correlation between PAI values and TGF-β concentration (p<0.001; r=0.869) in IA group.

CONCLUSIONS

The preoperative TGF-β concentration, BMI, CRP and NLR could be strong predictors of intraperitoneal adhesions in patients with the history of surgeries.

The Small Molecule Inhibitor QLT-0267 Decreases the Production of Fibrin-Induced Inflammatory Cytokines and Prevents Post-Surgical Peritoneal Adhesions

Peritoneal adhesions develop after abdominal surgery, trauma or intraperitoneal infections, and have important consequences. The deposition of peritoneal fibrin is a common pathophysiological pathway for the formation of adhesions. Here, we aimed to examine the effects of fibrin-induced cytokine production on peritoneal mesothelial cells (PMCs), and to block the effects of fibrin using an integrin-linked kinase (ILK) inhibitor, QLT-0267. PMCs were cultured from the enzymatic disaggregation of rat omentum. After the PMCs were covered with fibrin, the expression of IL-1β, IL-6, TNFα and VEGF-A increased. This increase in cytokine production was attenuated by QLT-0267, which acted via the inhibition of both the ILK and focal adhesion kinase (FAK) pathways, and subsequently via the GSK-3β pathway. We found that QLT-0267 decreased both the severity of peritoneal adhesion and the serum levels of IL-6 in our post-surgical adhesion mouse model. In conclusion, our study provides novel evidence that fibrin-induced cytokine production may involve in the mechanism of peritoneal adhesion formation. Furthermore, the use of the small molecule inhibitor QLT-0267 is a new strategy in preventing peritoneal adhesion in patients undergoing abdominal surgery.

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.

The effectiveness of heparin, platelet-rich plasma (PRP), and silver nanoparticles on prevention of postoperative peritoneal adhesion formation in rats

Purpose:

To assess the effectiveness of heparin, platelet-rich plasma (PRP), and silver nanoparticles on prevention of postoperative adhesion in animal models.

Methods:

Sixty males Albino Wistar rats aged 5 to 6 weeks were classified into five groups receiving none, heparin, PRP, silver nanoparticles, PRP plus silver nanoparticles intraperitoneally. After 2 weeks, the animals underwent laparotomy and the damaged site was assessed for peritoneal adhesions severity.

Results:

The mean severity scores were 2.5 ± 0.9, 2.16 ± 0.7, 1.5 ± 0.5, 2.66 ± 0.88, and 2.25 ± 0.62 in the control, heparin, PRP, silver and PRP plus silver groups, respectively with significant intergroup difference (p = 0.004). The highest effective material for preventing adhesion formation was PRP followed by heparin and PRP plus silver. Moreover, compared to the controls, only use of PRP was significantly effective, in terms of adhesion severity (p = 0.01) .

Conclusion:

Platelet-rich plasma alone may have the highest efficacy for preventing postoperative peritoneal adhesions in comparison with heparin, silver nanoparticles and PRP plus silver nanoparticles.

Comparing Lavage of the Peritoneal Cavity with Lidocaine, Bupivacaine and Normal Saline to Reduce the Formation of Abdominal Adhesion Bands in Rats

BACKGROUND

Intra-abdominal adhesions are fibrous bands that develop after abdominal surgery or inflammation and cause mortality and morbidity following surgeries. This study aimed to assess the effects of bupivacaine, saline and two doses of lidocaine, after peritoneal lavage and to compare their effects in reducing abdominal adhesions in rat.

METHODS

In a blinded, randomised, placebo-controlled clinical trial, 50 female rats were anaesthetised and the parietal peritoneum was scratched to induce punctate bleeding. The rats were randomly assigned to five groups: saline, lidocaine 2% (3 and 6 mg/kg), bupivacaine 0.25% (2 mg/kg) and control (no irrigation). The peritoneal cavity was irrigated with the appropriate solution during laparotomy. Two weeks later, re-laparotomy was performed. The quantity, quality, severity and scores of adhesions were recorded and compared.

RESULTS

The quantity and quality of adhesions were significantly higher in the control group than in the lidocaine (6 mg/kg) and bupivacaine groups. The quality of the adhesions was higher in the normal saline group than in the lidocaine (6 mg/kg) and bupivacaine groups. The severity of adhesions between the lidocaine 3 and 6 mg/kg groups and between the lidocaine 3 mg/kg and saline groups was lower than that in the control group.

CONCLUSION

Using lidocaine (6 mg/kg) and bupivacaine lavage in first laparotomy reduces abdominal peritoneal obstruction because of the formation of adhesion bands.

Injectable thermosensitive hydrogel containing hyaluronic acid and chitosan as a barrier for prevention of postoperative peritoneal adhesion

Peritoneal adhesion is one of the common complications after abdominal surgery. Injectable thermosensitive hydrogel could serve as an ideal barrier to prevent this postoperative tissue adhesion. In this study, poly(N-isopropylacrylamide) (PNIPAm) was grafted to chitosan (CS) and the polymer was further conjugated with hyaluronic acid (HA) to form thermosensitive HA-CS-PNIPAm hydrogel. Aqueous solutions of PNIPAm and HA-CS-PNIPAm at 10%(w/v) are both free-flowing and injectable at room temperature and exhibit sol-gel phase transition around 31°C; however, HA-CS-PNIPAm shows less volume shrinkage after gelation and higher complex modulus than PNIPAm. Cell culture studies indicate both injectable hydrogel show barrier effects to reduce fibroblasts penetration while induce little cytotoxicity in vitro. From a sidewall defect-bowel abrasion model in rats, significant reduction of postoperative peritoneal adhesion was found for peritoneal defects treated with HA-CS-PNIPAm compared with those treated with PNIPAm and untreated controls from gross and histological evaluation. Furthermore, HA-CS-PNIPAm did not interfere with normal peritoneal tissue healing and did not elicit acute toxicity from blood analysis and tissue biopsy examination. By taking advantage of the easy handling and placement properties of HA-CS-PNIPAm during application, this copolymer hydrogel would be a potentially ideal injectable anti-adhesion barrier after abdominal surgeries.

Periostin antisense oligonucleotide prevents adhesion formation after surgery in mice

To study the role of periostin in adhesion formation, the effect of periostin antisense oligonucleotide (PAO) on adhesion formation was evaluated in mice. Under anesthesia, the serous membrane of the cecum was abraded, and the adhesion score and mRNA levels of periostin and its related factors were determined after surgery. Saline, 40 mg/kg of negative sense oligonucleotide (NSO), or 40 mg/kg of PAO were injected into the abdomen after surgery, and the adhesion score and mRNA levels were evaluated 14 days later. Filmy adhesion formation was observed 1 day after surgery, and the adhesion score increased gradually to 14 days. The mRNA levels of periostin, transforming growth factor (TGF)-β, and collagen I increased gradually from 3 days to 14 days. The adhesion score of PAO was significantly lower than of saline or NSO 14 days after surgery. The mRNA levels of periostin, TGF-β, and collagen I were also significantly attenuated by treatment with PAO compared with saline or NSO. Thus, these results demonstrated that the periostin mRNA level increased in the abraded cecum, and PAO prevented adhesion formation along with attenuation of the periostin mRNA level.

The Preventive Effect of Dexmedetomidine Against Postoperative Intra-abdominal Adhesions in Rats

This study aimed to determine the possible preventive effects of dexmedetomidine on postoperative intra-abdominal adhesions. Dexmedetomidine is a highly selective and potent α2 adrenergic agonist with sedative, analgesic, anxiolytic, sympatholytic, hemodynamic, and diuretic properties. In recent years, investigations have shown that dexmedetomidine possesses secondary antioxidant and also anti-inflammatory effects. Thirty Wistar albino male rats were randomized and divided into 3 groups of 10 animals each: group 1, sham-operated; group 2, cecal abrasion + peritoneal dissection; group 3, cecal abrasion + peritoneal dissection followed by daily intravenous injection of 10 μg/kg dexmedetomidine for 10 days. The animals were killed on postoperative day 21. Blood and cecal samples were taken for biochemical and histopathologic evaluation. In this study, biochemical and pathologic parameters were significantly better in the cecal abrasion + peritoneal dissection + dexmedetomidine group when compared with the cecal abrasion + peritoneal dissection group. Tissue malondialdehyde, myeloperoxidase, total sulfhydryl, and catalase were found to be significantly different between the cecal abrasion/peritoneal dissection + dexmedetomidine and the cecal abrasion/peritoneal dissection groups. Plasma malondialdehyde and total sulfhydryl values were also statistically different between these groups (P < 0.05). Statistical analyses of mean pathologic scores showed that the histopathologic damage in the cecal abrasion/peritoneal dissection + dexmedetomidine group was significantly less than the damage in the control group (P < 0.05 for all pathologic parameters). The results of this study show that dexmedetomidine had a significant preventive effect on postoperative intra-abdominal adhesions. We concluded that these effects might be due to antioxidant and anti-inflammatory activities.

Fabrication of a photo-crosslinked gelatin hydrogel for preventing abdominal adhesion

A photocrosslinkable gelatin-based hydrogel membrane of easy-handling and non-toxic degradation was developed for preventing intra-abdominal adhesion formation.

Effect of "phase change" complex on postoperative adhesion prevention

BACKGROUND

Postsurgical peritoneal adhesion is a major clinical problem. Numerous anti-adhesion products have been studied, but none could be easily used to provide a physical barrier. In this study, we developed a "phase change" anti-adhesion barrier for reducing peritoneal adhesion by cross-linked copolymerization of O-carboxymethyl chitosan (CMC) and CaCl2 and addition of cyclosporin A (CsA).

MATERIALS AND METHODS

The CMC-CaCl2-CsA compound was characterized by equilibrium swelling rate, weight loss, releasing effect, and coagulation test, and its biosafety was characterized by acute oral toxicity, hemolysis, and cytotoxicity. Intestinal adhesion model was applied on 64 Sprague-Dawley rats, which received CMC, CMC-CaCl2, or CMC-CaCl2-CsA treatment. At postoperative days 7 and 14, the rats were euthanized, and adhesions were graded by an investigator blinded to the treatment groups, using a predetermined adhesion scoring system. The cecum and adhesion tissue were stained with hematoxylin and eosin and antibodies for matrix metalloproteinase-9 and TIMP-1 for further histopathologic examination.

RESULTS

The phase change anti-adhesive material exhibited effective blood clotting and were nontoxic in clotting experiments and acute toxicity test. The degradation rate could be adjusted using phosphate-buffered solution with varying pH. Adhesions were significantly reduced in the CMC-CaCl2-CsA treatment group compared with the control group (P < 0.001). Expression of matrix metalloproteinase-9 was stronger in CMC-CaCl2-CsA treatment group at 7 days after surgery.

CONCLUSIONS

"Phase-change" adhesive can undergo changes after application, and it inhibits the formation of abdominal adhesions after surgery. The material is convenient for using by surgeons and provides an effective tool for intestinal adhesion prevention.

[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.

Efficacy and Safety of Ultrapure Alginate-Based Anti-Adhesion Gel in Experimental Peritonitis

BACKGROUND

Intra-abdominal infection may lead to adhesion and abscess formation. An adhesion barrier can reduce these complications but also aggravate intra-peritoneal infection, causing the opposite effects. The fear of infection propagation has limited clinical adhesion barrier use in a contaminated or infected abdomen. This study evaluated both adhesion and abscess reduction and infection propagation of a new ultrapure alginate-based anti-adhesive barrier gel in a rat peritonitis model.

METHODS

In 64 male Wistar rats, bacterial peritonitis was induced via intra-abdominal injection of a mixture of sterile feces, 10(5) colony-forming units (CFU) of Escherichia coli, and 10(4) CFU of Bacteroides fragilis. Surgical debridement and peritoneal lavage were performed 1 h after inoculation. Animals were randomly allocated in equal numbers to a control group or an alginate gel group. Animals were sacrificed on day five post-operatively. Death and the presence and size of intra-abdominal abscesses were noted, and adhesions were scored. All outcomes were compared in the two groups.

RESULTS

Seventeen rats (27%) died prematurely without any difference between the groups. Of the surviving rats in the alginate gel group, 88% developed abscesses vs. 100% of the control group. There was no significant difference in the abscess scores or incidence rates of adhesion formation between the groups. The adhesion scores were lower for the alginate gel group compared with control animals (p=0.04).

CONCLUSION

Ultrapure alginate gel reduces adhesion severity but not abscesses. The gel seemed to be safe, not aggravating intra-peritoneal infection in this abdominal infection model.

Inhibition of cyclooxygenase-2 prevents intra-abdominal adhesions by decreasing activity of peritoneal fibroblasts

BACKGROUND

Postoperative intra-abdominal adhesions are common complications after abdominal surgery. The exact molecular mechanisms that are responsible for these complications remain unclear, and there are no effective methods for preventing adhesion formation or reformation. The aim of the study reported here was to investigate the preventive effects and underlying potential molecular mechanisms of selective cyclooxygenase-2 (COX-2) inhibitors in a rodent model of postoperative intra-abdominal adhesions.

MATERIALS AND METHODS

The expression of COX-2 in postoperative intra-abdominal adhesions and normal peritoneal tissue was examined by immunohistochemistry and Western blot analysis. Assays were performed to elucidate the effect of COX-2 inhibition on hypoxia-induced fibroblast activity in vitro and on intra-abdominal adhesion formation in vivo.

RESULTS

Hypoxia-induced COX-2 expression in peritoneal fibroblasts was increased in postoperative intra-abdominal adhesions. Inhibition of COX-2 attenuated the activating effect of hypoxia on normal peritoneal fibroblasts in vitro. Data indicate that selective COX-2 inhibitor prevents in vivo intra-abdominal adhesion by inhibition of basic fibroblast growth factor and transforming growth factor-beta expression, but not through an antiangiogenic mechanism. Furthermore, using selective COX-2 inhibitors to prevent intra-abdominal adhesions did not adversely affect the weight, bowel motility, or healing of intestinal anastomoses in a rat model.

CONCLUSION

These results show that hypoxia-induced COX-2 expression in peritoneal fibroblasts is involved in the formation of intra-abdominal adhesions. Inhibition of COX-2 prevents postoperative intra-abdominal adhesions through suppression of inflammatory cytokines.

Inflammation

Inflammation was described as early as 3000 BC in an Egyptian papyrus [1] and is still a common problem despite continuous advancements in prevention and treatment methods. The delineation of the site and extent of inflammation are crucial to the clinical management of infection and for monitoring the response to therapy [2].

Preoperative nomogram to predict risk of bowel injury during adhesiolysis

BACKGROUND

Inadvertent bowel injury during adhesiolysis is a major cause of increased morbidity and mortality following abdominal surgery. Identification of risk factors predicting this complication would guide preoperative counselling and surgical decision-making. The aim of this study was to identify predictive preoperative factors for inadvertent bowel injury occurring during adhesiolysis.

METHODS

All patients undergoing elective abdominal surgery between June 2008 and June 2010 were evaluated prospectively as part of the LAPAD study. Data on adhesiolysis and inadvertent organ injury were gathered by direct observation during operation. Univariable logistic regression was used to investigate factors that increased the risk of inadvertent bowel injury. Independent predictors of bowel injury were identified using multivariable logistic regression and used to create a clinical nomogram.

RESULTS

Of 715 patients eligible for analysis, 48 (6.7 per cent) had inadvertent bowel injuries. In 42 patients the defect was detected during operation and in nine at a later time (3 patients had both). Bowel resection was required for almost two-thirds of the enterotomies. The number of previous laparotomies, anatomical site of the operation, presence of bowel fistula and laparotomy via a pre-existing median scar were independent predictors of bowel injury. A clinical scoring system was constructed using a nomogram incorporating these risk factors; this had a predictive discrimination, measured as the area under the receiver operating characteristic curve, of 0.85.

CONCLUSION

A nomogram based on four independent factors predicted the risk of inadvertent bowel injury.

REGISTRATION NUMBER

NCT01236625 (http://www.clinicaltrials.gov).

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.

[The mechanism of adhesion formation and the possibilities of modeling -- a preliminary study]

A huge number of factors play a significant role in the process of adhesion formation, like bleeding, the presence of foreign bodies, tissue injury, tissue destruction, ischemia and hypoxia. Adhesions are present in 95% of the cases following abdominal surgery. As a result of adhesions a large number of postoperative complications can occur, such as abdominal pain, bowel motility disturbances and infertility. Hence, it is important to know the precise mechanism of adhesion formation process and establish a suitable animal model to investigate the underlying mechanisms. Molecules which play a part in the process of adhesion formation were collected from the international literature. Male Wistar rats were used to create the adhesion model. Bleeding, implantation of foreign bodies, creation of ischemic areas and tissue destructions were carried out. Within this experiment the tiny bleeding and ischemic areas did not result in adhesion formation. The adhesion formation due to foreign body implantation depends on the type of the materials. Due to the inhibitory mechanism of adhesion formation there was no adhesion detectable due to tiny peritoneal destruction. The most reliable model was the one when gross tissue destruction of the abdominal wall was applied and the resulting bleeding initiated the adhesion formation process. It is also extremely important to know the key participants in the complex process of adhesion formation. This reliable model can help to work out the proper method of prevention.

Novel thermosensitive hydrogel for preventing formation of abdominal adhesions

Adhesions can form after almost any type of abdominal surgery. Postoperative adhesions can be prevented by improved surgical techniques, such as reducing surgical trauma, preventing ischemia, and avoiding exposure of the peritoneal cavity to foreign materials. Although improved surgical techniques can potentially reduce formation of adhesions, they cannot be eliminated completely. Therefore, finding more effective methods to prevent postoperative adhesions is imperative. Recently, we found that a novel thermosensitive hydrogel, ie, poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCEC) had the potential to prevent postoperative adhesions. Using the ring-opening polymerization method we prepared a PCEC copolymer which could be dissolved and assembled at 55°C into PCEC micelles with mean size of 25 nm. At body temperature, a solution containing PCEC micelles could convert into a hydrogel. The PCEC copolymer was biodegradable and had low toxicity in vitro and in vivo. We found that most animals in a hydrogel-treated group (n = 10) did not develop adhesions. In contrast, 10 untreated animals developed adhesions that could only be separated by sharp dissection (P < 0.001). The hydrogel could adhere to peritoneal wounds and degraded gradually over 7-9 days, transforming into a viscous fuid that was completely absorbed within 12 days. The injured parietal and visceral peritoneum remesothelialized over about seven and nine days, respectively. This study confirms that PCEC hydrogel has potential application in the prevention of postoperative adhesions.

Electrospun adherent-antiadherent bilayered membranes based on cross-linked hyaluronic acid for advanced tissue engineering applications

A procedure to obtain electrospun mats of hyaluronic acid (HA) stable in aqueous media in one single step has been developed. It consists in combining an HA solution with a divinyl sulfone one as cross-linker in a three-way valve to immediately electroblow their mixture. Membranes obtained with this method, after sterilization and conditioning, are ready to use in cell culture without need of any additional post-treatment. HA nanofibers are deposited onto previously electrospun poly(l-lactic acid) (PLLA) mats in order to obtain stably joined bilayered membranes with an adherent face and the opposite face non-adherent, despite their different hydrophilicity and mechanical properties. These bilayered HA/PLLA membranes may be of use, for example, in applications seeking to transplant cells on a tissue surface and keep them protected from the environment: the PLLA nanofiber face is cell friendly and promotes cell attachment and spreading and can thus be used as a cell supply vehicle, while the HA face hinders cell adhesion and thus may prevent post-surgical adherences, a major issue in many surgeries.

Prevention of intra-abdominal adhesion by bi-layer electrospun membrane

The aim of this study was to compare the anti-adhesion efficacy of a bi-layer electrospun fibrous membrane consisting of hyaluronic acid-loaded poly(ε-caprolactone) (PCL) fibrous membrane as the inner layer and PCL fibrous membrane as the outer layer with a single-layer PCL electrospun fibrous membrane in a rat cecum abrasion model. The rat model utilized a cecal abrasion and abdominal wall insult surgical protocol. The bi-layer and PCL membranes were applied between the cecum and the abdominal wall, respectively. Control animals did not receive any treatment. After postoperative day 14, a visual semiquantitative grading scale was used to grade the extent of adhesion. Histological analysis was performed to reveal the features of adhesion tissues. Bi-layer membrane treated animals showed significantly lower adhesion scores than control animals (p < 0.05) and a lower adhesion score compared with the PCL membrane. Histological analysis of the bi-layer membrane treated rat rarely demonstrated tissue adhesion while that of the PCL membrane treated rat and control rat showed loose and dense adhesion tissues, respectively. Bi-layer membrane can efficiently prevent adhesion formation in abdominal cavity and showed a significantly decreased adhesion tissue formation compared with the control.

Comparison between the intraoperative use of polyvinyl chloride cover and surgical compresses for preventing postoperative adhesions

BACKGROUND/PURPOSE

Surgical compresses used for retraction during major abdominal and pelvic procedures lead to postoperative adhesion formation resulting from damage to the visceral peritoneum. This study investigates whether polyvinyl chloride (PVC) covers cause less postsurgical adhesion and inflammation than surgical compresses in an animal model.

METHODS

Female Wistar albino rats (n = 160) were divided into three groups (compress, PVC cover and control), which were then divided into 16 subgroups (n = 10/group). All animals underwent midline laparotomy and cecal abrasion. A metal retractor, which applies a constant force, was then placed on the small intestine for 2 h. In the control group, no material was placed under the retractor, whereas a surgical compress or PVC cover was placed in the experimental animals. Full-thickness small intestinal biopsies were obtained and examined by light and electron microscopy. The following parameters were evaluated: congestion, mesothelial proliferation, leukocyte migration and collagenization. Adhesions were scored according to the Nair, Knightly and Mazuji scoring systems.

RESULTS

All inflammation scores were significantly higher in the compress group than in the other two groups. However, no significant difference was observed between the PVC cover and control groups. Adhesions were more frequent in the compress group than in the other two groups, regardless of the scoring system used.

CONCLUSIONS

Surgical compresses used in abdominal and pelvic surgeries cause inflammation and adhesion. Contrary to surgical compresses, PVC covers do not cause inflammation and adhesion, which may considerably reduce adhesion-related complications in abdominopelvic surgeries.

Effects of new anti-adhesion polyvinyl alcohol gel on healing of colon anastomoses in rats

BACKGROUND

Adhesions follow abdominal surgery with an incidence as high as 95%, resulting in invalidating complications such as bowel obstruction, female infertility, and chronic pain. Searches have been performed for a safe and effective adhesion barrier; however, such barriers have impaired anastomotic site healing. The primary aim of this study was to investigate the effect of a new adhesion barrier, polyvinyl alcohol gel, on healing of colonic anastomoses using a rat model.

METHODS

Thirty-two Wistar rats were divided in two groups. In all animals, an anastomosis was constructed in the ascending colon. The first group received no adhesion barrier, whereas in the second group, 2 mL of polyvinyl alcohol gel (A-Part Gel(®); Aesculap AG, Tuttlingen, Germany) was applied circularly around the anastomosis. All animals were sacrificed on the seventh post-operative day, and the abdomen was inspected for signs of anastomotic leakage. The anastomotic bursting pressure, the adhesions around the anastomosis, and the collagen content of the excised anastomosis were measured.

RESULTS

No significant differences were observed between the two groups in the incidence of anastomotic leakage, the anastomotic bursting pressure (p=0.08), or the collagen concentration (p=0.91). No significant reduction in amount of adhesions was observed in the rats receiving polyvinyl alcohol gel.

CONCLUSIONS

This experimental study showed no significant differences in anastomotic leakage, anastomotic bursting pressure, or collagen content of the anastomosis when using the adhesion barrier polyvinyl alcohol around colonic anastomoses. The barrier did not prevent adhesion formation.

Fibrin-Induced epithelial-to-mesenchymal transition of peritoneal mesothelial cells as a mechanism of peritoneal fibrosis: effects of pentoxifylline

Excessive fibrin deposition in the peritoneum is thought to be involved in the development of encapsulating peritoneal sclerosis (EPS), an important cause of morbidity and mortality in peritoneal dialysis patients. We investigated fibrin-induced epithelial-to-mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) as a possible mechanism of fibrin involvement in EPS. In vitro, fibrin overlay of PMCs altered their morphology; increased α-smooth muscle actin, fibronectin, fibroblast specific protein-1, and α(v)β(3) integrin expression; and decreased cytokeratin 18 and E-cadherin expression. Fibrin overlay also increased focal adhesion kinase and Src kinase phosphorylation. Fibrin-induced changes were inhibited by treating the cells with α(v)β(3) integrin antibody or pentoxifylline (PTX). In a rat model, intraperitoneal injection of Staphylococcus aureus and fibrinogen induced severe EPS features, which were attenuated by PTX treatment. PTX-treated rats also showed preserved peritoneal ultrafiltration function and lower concentrations of cytokines than the untreated rats. S. aureus- and fibrinogen-injected rats had higher percentage of cytokeratin-positive cells in the omentum fibrotic tissue than controls; this was also reduced by PTX treatment. Our results suggest that fibrin induces EMT of PMCs by engaging α(v)β(3) integrin and activating associated kinases. Our EPS animal model showed that fibrin-induced EMT was involved in the pathogenesis of peritoneal fibrosis and was inhibited by PTX.

Effects of different pulmonary surfactants in the prevention of postoperative intraabdominal adhesion formation

BACKGROUND

After abdominal surgery, the formation of postoperative adhesion is a serious problem. The aim of the study is to evaluate the efficacy of 2 different pulmonary surfactants, poractant and beractant, on adhesion prevention in an experimental model.

MATERIALS AND METHODS

An experimental intraabdominal adhesion model was created in 18 adult female rats by cecal abrasion. The rats were randomly assigned to 3 groups. Group I received no further treatment, whereas groups II and III received intraperitoneal poractant and beractant, respectively, before closing the incision. On the 15th postoperative day, all rats underwent relaparotomy, intraabdominal adhesions were scored macroscopically according to Canbaz scoring system, and the cecum in each animal was evaluated microscopically.

RESULTS

The median adhesion scores of group II and III rats were significantly lower when compared with group I (P = .02). Group III had a lower median adhesion score than did group II, but this did not reach significance (P > .05).

CONCLUSION

These observations suggest that intraperitoneal instillation of both pulmonary surfactants is associated with lower adhesion scores, higher adhesion-free cases, and improved histologic findings.

Polyvinyl alcohol hydrogel decreases formation of adhesions in a rat model of peritonitis

BACKGROUND

Adhesion formation after surgery for peritonitis-related conditions, with such associated complications as intestinal obstruction, pain, and infertility, remains an important problem. Applying a liquid barrier intra-peritoneally might reduce initial adhesion formation.

METHODS

A combination of the cecal ligation and puncture model of peritonitis with the side-wall defect (SWD) model of adhesion formation was performed. Forty rats were assigned randomly to receive no barrier or 1 mL or 2 mL of the cross-linked polyvinyl alcohol and carboxymethylcellulose (PVA/CMC) hydrogel A-Part(®) Gel (B. Braun Aesculap AG, Tuttlingen, Germany). After 14 days, the animals were sacrificed, and adhesion formation and abscess formation were scored.

RESULTS

Thirty animals survived, distributed equally among the groups. There were significantly fewer adhesions to the SWD in the PVA/CMC groups (median 0) than in the control group (median 26%-50%) (p<0.05). The median tenacity of the adhesions was significantly higher in the control group (Zühlke score 2) than in the PVA/CMC groups (Zühlke score 0) (p<0.05). The amount and size of intra-abdominal abscesses were not significantly different in the three groups.

CONCLUSION

In this experiment, PVA/CMC hydrogel reduced the amount of adhesions to the SWD and between viscera significantly with equal risk of abscess formation.

The role of tissue plasminogen activator in the management of complex intra-abdominal abscesses in children

OBJECTIVE

The objective of this study is to assess the safety of fibrinolytic therapy using tissue plasminogen activator (tPA) in children with complex intra-abdominal abscesses.

SUMMARY BACKGROUND DATA

Intra-abdominal abscesses are common in children. Antibiotics and percutaneous drainage are the mainstays of treatment, but drainage may be less effective when the fluid is thick or septated. Fibrinolytic therapy using tPA is effective in a rat model of intra-abdominal abscesses, has recently been reported for the treatment of intra-abdominal abscesses in adults, and is commonly used in the treatment of empyema in children.

METHODS

This is a retrospective review of all patients over a 10-year period who had intra-abdominal collections managed with tPA abscess drainage.

RESULTS

Sixty-four children had a total of 66 drains placed and 92 doses of tPA. Appendicitis was the cause of the abscesses in 52 of 64 children. Mean length of stay pre-tPA was 11.7 ± 7.63 days, mean time from drain insertion to tPA was 4.3 ± 3.78 days, and mean time from tPA to discharge was 8.6 ± 8.85 days. Thirty patients underwent an operation before tPA administration. No patients experienced bleeding complications, anastomotic or appendiceal stump leak, or wound dehiscence after the administration of tPA, and no patients had abnormalities in coagulation studies related to tPA administration. One child died of sepsis.

CONCLUSIONS

Tissue plasminogen activator is safe for the management of thick or septated intra-abdominal abscesses in children. A prospective controlled study will be needed to evaluate the efficacy of this technique.

Oral tadalafil reduces intra-abdominal adhesion reformation in rats

BACKGROUND

Currently, there is no ideal agent to prevent adhesion formation. We have shown that sildenafil, a phosphodiesterase-5 (PDE-5) inhibitor, reduces post-operative adhesion formation by vasodilatation and increases fibrinolytic activity. Here, we evaluated whether tadalafil, a long-acting PDE-5 inhibitor, decreases post-operative adhesion reformation in rats.

MATERIALS AND METHODS

Standardized lesions were created in Wistar albino rats by cauterization of uterine horns and abrasion of adjacent peritonium. The extent and severity of adhesions were scored on the 14th post-operative day and adhesiolysis was performed at the second laparotomy. Animals were then assigned randomly into two groups. The study group (n = 11) received 10 mg/kg oral tadalafil by gavage 60 min before the second laparotomy and daily for 14 days afterwards. Controls (n = 11) received the same volume of tap water for 14 days by gavage. Animals were killed 15 days after adhesiolysis and adhesions were scored blind during the third laparotomy. RESULTS Basal adhesion scores at the time of the second laparotomy were comparable in the study and control groups. Scores for the extent of adhesion reformation in the study and control groups did not differ [median 1 (range 0-3) versus median 2 (range 1-3); P: 0.81] but tadalafil reduced the respective severity scores [median 0.5 (range 0-1) versus median 1 (range 0.5-1); P: 0.02] and total scores [median 2 (range 0-4) versus median 2.5 (range 1.5-4); P: 0.042].

CONCLUSIONS

Oral administration of tadalafil during the perioperative period reduces intra-abdominal adhesion reformation in rats.

Evaluation of the effects of gonadotropin-releasing hormone antagonist (GnRH-ant) and agonist (GnRH-a) in the prevention of postoperative adhesion formation in a rat model with immunohistochemical analysis

OBJECTIVE

To investigate the effects of GnRH antagonist (GnRH-ant) and agonist (GnRH-a) in the prevention of postoperative pelvic adhesions by a visual scoring system and immunohistochemical methods in a rat uterine horn model.

DESIGN

Controlled experimental animal study.

SETTING

Animal laboratory at an academic research environment.

ANIMAL(S)

Twenty-one Wistar albino rats.

INTERVENTION(S)

Rats were randomized into three groups. One week before the operation the rats received either GnRH-ant or GnRH-a or saline solution; they then underwent surgical laparotomy, and both uterine horns were traumatized by a scalpel. Three weeks later, all rats were sacrificed and extension and severity of the adhesions in each group were scored by a visual scoring system. Adhesion tissues were evaluated immunohistochemically for vitronectin and u-PAR.

MAIN OUTCOME MEASURE(S)

Scores of extend and severity of adhesions and staining of vitronectin and u-PAR.

RESULT(S)

The extent of adhesion scores were 1.85 ± 0.86, 0.78 ± 1.05, and 0.42 ± 0.64, and the severity of adhesion scores were 1.71 ± 0.91, 0.57 ± 0.85, 0.50 ± 0.75 for control, GnRH-ant, and GnRH-a groups, respectively. The extent and severity of adhesions were significantly lower in both GnRH-ant and GnRH-a groups when compared with the control group. Adhesion extent scores in the GnRH-a group were lower than in the GnRH-ant group, but this difference was not significant. vitronectin and u-PAR staining were significantly greater in both the GnRH-ant and GnRH-a groups than in the control group.

CONCLUSION(S)

GnRH-ant as well as GnRH-a reduced postoperative adhesion formation in a rat model. This finding was supported immunohistochemically by vitronectin and u-PAR staining.

Efficacy of polyethylene glycol adhesion barrier after gynecological laparoscopic surgery: Results of a randomized controlled pilot study

Postoperative adhesions are the most frequent complication of peritoneal surgery, causing small bowel obstruction, female infertility and chronic pain. This pilot study assessed the efficacy of a sprayable polyethylene glycol (PEG) barrier in the prevention of de novo adhesions. 16 patients undergoing laparoscopic gynecological surgery were randomly assigned by shuffled sealed envelopes to receive either the adhesion barrier or no adhesion prevention. Incidence and severity of adhesions were scored at eight sites in the pelvis and reassessed by second look laparoscopy. Adhesion prevention was considered successful if no de novo adhesion were found at second look laparoscopy. One patient was excluded before randomization. Nine patients were randomized to treatment and six patients to control group. De novo adhesions were found in 0/9 patients who received the PEG barrier compared to 4/6 without adhesion prevention (0% vs. 67%, P = 0.01). Reduction in adhesion score was significantly greater in patients receiving PEG barrier (−2.6 vs. −0.06, P = 0.03). Meta-analysis of three randomized trials demonstrated that PEG barrier reduces the incidence of adhesions (odds ratio [OR] = 0.27; 95% CI 0.11–0.67). From this study, PEG barrier seems effective in reducing postoperative formation of de novo adhesions.