Fibrinolytic activity in the abdominal cavity of rats with faecal peritonitis

Aspirin Protected the Nitric Oxide/Cyclic Gmp Generating System in Human Peritoneum

♦ Objective

Changes in the expression of endothelial nitric oxide synthase (eNOS) in the peritoneum could be involved in the peritoneal dysfunction associated with peritoneal inflammation. The aim of the present study was to analyze the effect of Escherichia coli lipopolysaccharide (LPS) on eNOS expression in samples of human peritoneum. The effect of aspirin, a drug with anti-inflammatory properties, was also determined.

♦ Results

The eNOS protein expressed in human peritoneal tissue was reduced by LPS (10 μg/mL) in a time-dependent manner. The eNOS was expressed mainly in capillary endothelial cells and mesothelial cells. Anti-inflammatory doses of aspirin (1 – 10 mmol/L) restored eNOS expression in LPS-stimulated human peritoneal tissue samples. The main intracellular receptor of NO, soluble guanylate cyclase (sGC), was also downregulated by LPS. This effect was prevented by aspirin (5 mmol/L).

♦ Conclusion

Protein expression of the eNOS–sGC system in the peritoneal tissue was downregulated by LPS. High doses of aspirin protected both eNOS protein expression and sGC in human peritoneum. These findings suggest a new mechanism of action of aspirin that could be involved in the prevention of peritoneal dysfunction during inflammation.

Effect of the Bioadhesive, BioGlue, on Impaired Colonic Anastomose Healing in Rats

Colonic anastomotic leakage is still a problem in general surgery practice. We sought to investigate the effect of a new tissue adhesive, BioGlue, on the healing of normal and impaired colonic anastomoses. Sixty-four rats were randomized into 4 groups. In all animals, a 1-cm segment of the left colon was resected, and an end-to-end sutured anastomosis was created. Animals were then divided into 2 groups: normal and impaired anastomosis. These 2 groups were further subdivided into 2 additional groups: animals that received BioGlue and those that did not. All rats received intraperitoneal injections of either 0.9% NaCl or 5-fluorouracil (5-FU). Anastomotic evaluation was done 7 days after surgery. Macroscopic healing, mechanical strength, and histopathologic healing parameters were evaluated. Leakage of the anastomosis was significantly higher in rats in the impaired group compared with those in the BioGlue groups (P = 0.043). The adhesion formation score was significantly higher in rats in the impaired anastomosis group compared with the other groups. Bursting pressures were significantly lower in the impaired anastomosis group than in the other ones (P = 0.001). Neoangiogenesis and fibroblast activity were different among the groups (P = 0.001). Inflammatory cell infiltration and collagen deposition did not differ among the groups (P = 0.07). Immediate postoperative intraperitoneal administration of 5-FU after colonic anastomosis inhibits intestinal wound healing. Covering colon anastomoses with BioGlue after suturing conferred beneficial effect on healing.

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.

Response to pathological processes in the peritoneal cavity--sepsis, tumours, adhesions, and ascites

The peritoneum is one of the commonest sites for pathological processes in pediatric surgery. Its response to pathological processes is characterized by an inflammatory reaction with specific pathways depending on the type of injury or peritoneal process involved. This review discusses the current understanding of peritoneal inflammation, adhesion formation, intra-abdominal sepsis, peritoneal metastasis, and ascites and briefly reviews new therapeutic strategies to treat or prevent these pathological entities. Recent studies have improved the understanding of peritoneal responses, resulting in possible new targets for prevention and therapy.

Effect of intraabdominal administration of Allium sativum (garlic) oil on postoperative peritoneal adhesion

OBJECTIVE(S)

Peritoneal adhesion is a serious problem that develops after most abdominopelvic surgeries. Allium sativum (garlic) has been used for centuries as both a nutrient and a traditional medicine. The anti-inflammatory, antibacterial, fibrinolytic, and wound-healing properties of garlic are well-recognized. We evaluated the effect of garlic on formation of postoperative adhesions in rats.

STUDY DESIGN

Thirty Wistar-Albino female rats weighing 200-250 g were randomly divided into three groups (10 rats/group). Group 1 rats received 5 ml/kg garlic oil intraperitoneally and no surgery was performed. The ceca of Group 2 rats (controls) were scraped, to trigger adhesion formation, and no treatment was given. In Group 3 rats, 5 ml/kg garlic oil was added to the peritoneal cavity immediately after the cecum was scraped. All animals were sacrificed 10 d after surgery and adhesions graded in terms of severity and histopathologic characteristics.

RESULTS

All animals tolerated the operations well. No adhesions were evident upon laparotomy of Group 1 animals. In Group 2 three rats had an adhesion grade 2 and seven rats had an adhesion of grade 3, whereas in Group 3 no adhesions were found in four rats, five rats had an adhesion grade of 1. Only one rat had a grade 2 adhesion. Macroscopic adhesions and mean adhesion scores of Group 3 were significantly lower than Group 2 (p<0.001). Histopathologic evaluation of the specimens also revealed a statistically significant differences in inflammation, fibrosis, and neovascularization scores between Group 2 and 3 (p=0.001, p=0.001, and p=0.011, respectively). Inflammation, fibrosis and vascularization scores in Group 3 were found significantly lower than Group 2.

CONCLUSION

The anti-inflammatory, antibacterial, fibrinolytic, antithrombotic, and wound-healing effects of garlic likely prevent formation of peritoneal adhesions in a rat model, and garlic may be effective and cheap when used to prevent such adhesions in humans.

New hepatectomy-induced postoperative adhesion model in rats, and evaluation of the efficacy of anti-adhesion materials

PURPOSE

Repeated hepatic resections are not uncommon during the surgical management of liver tumors. Postoperative adhesions induced by hepatectomies can have a significant negative impact on subsequent surgeries. We recently developed a new hepatectomy-induced postoperative adhesion animal model to evaluate the anti-adhesion efficacy of commercially available sheet materials (Seprafilm(®) and Interceed(®)) and the recently reported hyaluronan-based in situ cross-linkable hydrogels.

METHODS

The median lobe (ML) and the left lateral lobe (LLL) of the liver (approximately 70 % of the total liver) of 43 male Sprague-Dawley rats were resected based on the classical procedure; anti-adhesion materials were then applied. A relaparotomy was performed 1 week later to evaluate the adhesions and histopathological findings.

RESULTS

The rats without the application of anti-adhesion materials (n = 14) showed the most severe adhesions (grade 3) between the cut surface of the liver and the small bowel or omentum. All the barrier materials produced slight anti-adhesion effects. Adhesions between the liver surface and the diaphragm and adhesions around the hepatic hilum were less severe, but were not remarkably reduced, by the anti-adhesion materials.

CONCLUSION

We successfully established a new hepatectomy-induced animal adhesion model, which may be useful for the development of new anti-adhesion materials.

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.

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.

Pathogenesis of postoperative adhesion formation

Background

Current views on the pathogenesis of adhesion formation are based on the ‘classical concept of adhesion formation’, namely that a reduction in peritoneal fibrinolytic activity following peritoneal trauma is of key importance in adhesion development.

Methods

A non-systematic literature search (1960–2010) was performed in PubMed to identify all original articles on the pathogenesis of adhesion formation. Information was sought on the role of the fibrinolytic, coagulatory and inflammatory systems in the disease process.

Results

One unifying concept emerged when assessing 50 years of studies in animals and humans on the pathogenesis of adhesion formation. Peritoneal damage inflicted by surgical trauma or other insults evokes an inflammatory response, thereby promoting procoagulatory and antifibrinolytic reactions, and a subsequent significant increase in fibrin formation. Importantly, peritoneal inflammatory status seems a crucial factor in determining the duration and extent of the imbalance between fibrin formation and fibrin dissolution, and therefore in the persistence of fibrin deposits, determining whether or not adhesions develop.

Conclusion

Suppression of inflammation, manipulation of coagulation as well as direct augmentation of fibrinolytic activity may be promising antiadhesion treatment strategies.

Fibrinogen regulates the cytotoxicity of mycobacterial trehalose dimycolate but is not required for cell recruitment, cytokine response, or control of mycobacterial infection

During inflammatory responses and wound healing, the conversion of soluble fibrinogen to fibrin, an insoluble extracellular matrix, long has been assumed to create a scaffold for the migration of leukocytes and fibroblasts. Previous studies concluded that fibrinogen is a necessary cofactor for mycobacterial trehalose 6,6'-dimycolate-induced responses, because trehalose dimycolate-coated beads, to which fibrinogen was adsorbed, were more inflammatory than those to which other plasma proteins were adsorbed. Herein, we investigate roles for fibrin(ogen) in an in vivo model of mycobacterial granuloma formation and in infection with Mycobacterium tuberculosis, the causative agent of tuberculosis. In wild-type mice, the subcutaneous injection of trehalose dimycolate-coated polystyrene microspheres, suspended within Matrigel, elicited a pyogranulomatous response during the course of 12 days. In fibrinogen-deficient mice, neutrophils were recruited but a more suppurative lesion developed, with the marked degradation and disintegration of the matrix. Compared to that in wild-type mice, the early formation of granulation tissue in fibrinogen-deficient mice was edematous, hypocellular, and disorganized. These deficiencies were complemented by the addition of exogenous fibrinogen. The absence of fibrinogen had no effect on cell recruitment or cytokine production in response to trehalose dimycolate, nor was there a difference in lung histopathology or overall bacterial burden in mice infected with Mycobacterium tuberculosis. In this model, fibrin(ogen) was not required for cell recruitment, cytokine response, or response to infection, but it promoted granulation tissue formation and suppressed leukocyte necrosis.

An assessment of the effects of a hyaluronan-based solution on reduction of postsurgical adhesion formation in rats: a comparative study of hyaluronan-based solution and two film barriers

BACKGROUND

Intra-abdominal application of anti-adhesive barriers may reduce the extent and severity of postoperative adhesions. This study was designed to compare the effectiveness of a sprayable liquid barrier (a mixed solution of sodium hyaluronate and carboxymethylcellulose) with two conventional sheets.

METHODS

Eighty male Sprague Dawley rats underwent laparotomy with subsequent multiple intestinal wall abrasions and abdominal wall injury. Afterwards, sodium hyaluronate and carboxymethylcellulose (HA-CMC) solutions were intraperitoneally sprayed or a film barrier of either oxidized regenerated cellulose (ORC) or polylactic acid (PA) was placed under the incision. At postoperative d 21, the rats underwent relaparotomy and complete adhesiolysis. Three investigators, who were blind to the group assignment, scored the extent of adhesion formation and resected specimens for histologic examination of fibrosis and inflammation. Expression profiles of parameters as mediators (macrophages [CD68]) in cellular inflammation response were analyzed.

RESULTS

Mean adhesion scores in rats that received HA-CMC solution (7.6±2.3) and ORC membrane (8.1±2.2) were lower than in rats that received PA film (10.7±2.5) and the control group (11.2±2.6) (P<0.05 for each comparison). In addition, there were significantly fewer adhesions located between large and small intestine in the HA-CMC solution group than in the control and each of the film barrier groups (P<0.05 for each comparison).

CONCLUSIONS

This study suggests that both HA-CMC solution and ORC membrane decrease the overall incidence of postoperative adhesions. However, the mixed solution of HA-CMC appeared to be superior to ORC membrane because this sprayable solution is easy to use and suitable for site-specific adhesion prevention after multifocal bowel trauma.

Spatiotemporal progression of localized bacterial peritonitis before and after open abdomen lavage monitored by in vivo bioluminescent imaging

BACKGROUND

Bacterial peritonitis is a life-threatening abdominal infection associated with high morbidity and mortality. The rat is a popular animal model for studying peritonitis and its treatment, but longitudinal monitoring of the progression of peritonitis in live animals has been impossible until now and thus required a large number of animals. Our objective was to develop a noninvasive in vivo imaging technique to monitor the spatiotemporal spread of bacterial peritonitis.

METHODS

Peritonitis was induced in 8 immunocompetent male Wistar rats by placing fibrin clots containing 5x10(8) cells of both Bacteroides fragilis (American Type Tissue Culture [ATCC)] 25,285 and bioluminescent Escherichia coli Xen14. After 1 or 2 days, infected clots were removed and open abdomen lavage was performed. In vivo bioluminescent imaging was used to monitor the spread of peritonitis.

RESULTS

Bioluminescent in vivo imaging showed an increase in the area of spread, and the number of E. coli tripled into the rat's abdominal cavity on day 1 after clot insertion; however, on day 2, encapsulation of the clot confined bacterial spread. Bioluminescent E. coli respread over the peritoneal cavity after lavage; within 10 days, however, in vivo imaging showed a decrease of 3-4 orders of magnitude in bacterial load.

CONCLUSION

Bioluminescent in vivo imaging can be effectively used to monitor the spatiotemporal behavior of the peritonitis during 3 different stages of the disease process: initiation, treatment, and follow-up. Imaging allows researchers to repeatedly image the same animal, thereby reducing variability and providing greater confidence in determining treatment efficacies for therapeutic interventions using a small number of animals.

Effects of amniotic membrane on the healing of primary colonic anastomoses in the cecal ligation and puncture model of secondary peritonitis in rats

PURPOSE

We aimed to investigate the effects of amniotic membrane on primary colonic anastomoses in a rat peritonitis model.

MATERIALS AND METHODS

Fifty female Sprague Dawley rats were used in the study. Bacterial peritonitis was induced in all rats by performing a cecal ligation and puncture. Ten rats served as controls for the bursting pressure measurement, while the other 40 animals were divided into two groups (the anastomosis group (P) or the amniotic membrane group (PA)), and all of them underwent colonic anastomosis. The latter group had amniotic membrane covering their anastomoses. Half of the PA and P groups were sacrificed on the third postoperative day (PA3, P3), and the other half on the seventh postoperative day (PA7, P7).

RESULTS

The bursting pressures were significantly higher in groups PA3 and PA7 compared with P3 (p < 0.01) and P7 (p < 0.05), respectively. Inflammatory cell infiltration and adhesion scores were significantly lower in groups PA3 and PA7 compared with groups P3 (p < 0.001, p < 0.01, respectively) and P7 (p < 0.001, p < 0.05, respectively). Neoangiogenesis, fibroblast activity, collagen deposition, and hydroxyproline concentrations were significantly higher in groups with amniotic membrane than in groups without amniotic membrane (p < 0.05, for all comparisons).

CONCLUSION

This study showed that the covering of colonic anastomoses with amniotic membrane significantly prevented the delaying effect of intraperitoneal sepsis and provided a safer and stronger anastomosis than suture and that this was the case for both the early and late phases of anastomotic healing in the colon.

The innate immune response to secondary peritonitis

Secondary peritonitis continues to cause high morbidity and mortality despite improvements in medical and surgical therapy. This review combines data from published literature, focusing on molecular patterns of inflammation in pathophysiology and prognosis during peritonitis. Orchestration of the innate immune response is essential. To clear the microbial infection, activation and attraction of leukocytes are essential and beneficial, just like the expression of inflammatory cytokines. Exaggeration of these inflammatory systems leads to tissue damage and organ failure. Nonsurvivors have increased proinflammation, complement activation, coagulation, and chemotaxis. In these patients, anti-inflammatory systems are decreased in blood and lungs, whereas the abdominal compartment shows decreased neutrophil activation and decreased or stationary chemokine and cytokine levels. A later down-regulation of proinflammatory mediators with concomitant overexpression of anti-inflammatory mediators leads to immunoparalysis and failure to clear residual bacterial load, resulting in the occurrence of superimposed infections. Thus, in patients with adverse outcome, the inflammatory reaction is no longer contained within the abdomen, and the inflammatory response has shifted to other compartments. For the understanding of the host response to secondary peritonitis, it is essential to realize that the defense systems presumably are expressed differently and, in part, autonomously in different compartments.

Microbubble-enriched lavage fluid for treatment of experimental peritonitis

Background

Relaparotomies and closed postoperative peritoneal lavage (CPPL) are performed to treat persistent peritonitis. This experimental animal study compared open abdominal lavage with CPPL, and evaluated the potential of microbubble-enriched lavage fluids to improve the efficiency of CPPL and reduce clinical morbidity, mortality and cost.

Methods

Fluorescent polystyrene spheres were injected intraperitoneally into 22 male Wistar rats to simulate localized peritonitis. After 18 h the rats received open abdominal lavage and CPPL, with and without microbubbles. Microbubbles were obtained by adding ultrasound contrast agents to continuous ambulatory peritoneal dialysis fluid.

Results

Open abdominal lavage was 3·5 times more effective in particle removal than CPPL, owing to better fluid dynamics. The introduction of air–liquid interfaces in the form of microbubbles made CPPL up to 2·4 times more effective than lavage without bubbles. Best detachment results were obtained when microbubbles with a flexible surfactant shell and longer blood elimination half-life were used.

Conclusion

Open abdominal and CPPL lavage techniques are not efficient beyond a certain duration and volume as they do not cause bacterial detachment from the peritoneal membrane. Using surface tension forces from microbubbles significantly enhanced polystyrene particle detachment. These findings may have great consequences for the treatment of patients with peritonitis.

Effects of intra-abdominal administration of recombinant tissue plasminogen activator on coagulation, fibrinolysis and inflammatory responses in experimental polymicrobial peritonitis

Peritonitis represents a procoagulant state because of activated coagulation and inhibited fibrinolysis. Intra-abdominal fibrin deposition-entrapping bacteria-prevents bacterial spread but impairs bacterial clearance. Activating intra-abdominal fibrinolysis by recombinant tissue-type plasminogen activator (r-tPA) early during peritonitis may enhance bacterial clearance and reduce inflammation. This study examines effects of abdominal r-tPA lavage on local and distant coagulation, fibrinolysis, and inflammatory responses in experimental polymicrobial peritonitis. Twenty-four hours after cecal ligation and puncture, mice were exposed to therapeutic abdominal lavage with varying doses of r-tPA or saline (controls). Coagulation, fibrinolysis, and inflammation were assessed in abdominal, systemic, and pulmonary compartments (n = 6 per group per time point). Survival was assessed during 96 h (n = 16 per group). Highest-dose (2 mg/mL) r-tPA lavage caused immediate death. High-dose (0.5 mg/mL) r-tPA lavage increased fibrinolysis, demonstrated by low abdominal plasminogen activator inhibitor 1 levels and elevated pulmonary tPA levels, resulting in reduced abdominal bacterial load, chemokine levels, leukocyte influx, and thrombin generation, along with less pulmonary fibrin depositions and organ damage on histological examination (P < 0.05 vs. saline lavage). Low-dose (0.05 mg/mL) r-tPA lavage showed hardly any effect compared with saline lavage. Adversely, abdominal and plasma interleukin (IL) 12 were elevated, whereas IL-10 levels were decreased after high-dose r-tPA lavage (P < 0.05 vs. saline). Survival rate was not affected by any dose of r-tPA lavage compared with saline lavage. Delayed local stimulation of fibrinolysis by peritoneal r-tPA lavage enhanced intra-abdominal bacterial clearance and reduced intra- and extra-abdominal coagulation responses in a dose-dependent manner. Survival rate was unaffected likely due to adverse changes in IL-12 and IL-10 levels.

Fibrinolytic responses of human peritoneal fluid in laparoscopic cholecystectomy: a prospective clinical study

BACKGROUND

The reduction in peritoneal fibrinolysis is believed to be the pathogenetic mechanism of adhesion formation. The general conclusion based on previous clinical and experimental studies is that laparoscopic procedures produce less adhesion formation. The association between this beneficial effect of laparoscopic cholecystectomy and peritoneal fibrinolytic changes is not clear. Therefore, the authors aimed to compare the effects of open and laparoscopic cholecystectomy on peritoneal fibrinolysis. For this purpose, fibrinolytic parameters in peritoneal fluid were investigated 24 h after laparoscopic and open cholecystectomies.

METHODS

In a prospective clinical study, peritoneal fluid was sampled via a drain 24 h after laparoscopic (n = 10) and open (n = 9) cholecystectomies. Activities and concentrations of tissue plasminogen activator (tPA), plasminogen activator inhibitor type 1 (PAI-1), and tPA/PAI-1 complex were determined by enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

In peritoneal fluids, tPA and tPA/PAI-1 complex concentrations were higher in the open cholecystectomy group (p = 0.009 and p < 0.001, respectively), but tPA activity and PAI-1 concentrations did not differ between the groups (p = 0.514 and p = 0.716, respectively).

CONCLUSIONS

Fibrinolytic changes in peritoneal fluid have several similarities in open and laparoscopic cholecystectomies with regard to tPA activity and PAI-1 levels. However, higher tPA levels after the open procedure probably are secondary to more intense tissue handling leading to mesothelial release of tPA.

The effect of immunosuppression on peritoneal adhesions formation after small bowel transplantation in rats

BACKGROUND

The reported incidence of adhesion related small bowel obstruction after abdominal organ transplantation is considerably lower than other abdominal procedures. The purpose of the study was to investigate the influence of immunosuppression on peritoneal adhesion formation after intestinal transplantation in rats.

METHODS

Four groups of rats (n = 6) underwent small bowel intestinal transplantation in syngeneic (Groups A, B) and allogeneic (Groups C, D) combinations. Groups B and D received tacrolimus immunosuppression 1 mg/kg/d. Animals were euthanized on postoperative day 7, and the total adhesion score (TAS), tissue hydroxyproline content (HPC), TGF-beta mRNA expression levels and histology were examined.

RESULTS

All of the animals in Group C showed severe histological (Grade III) acute cellular rejection. There were no histological signs of rejection in Group D. A significant reduction in TAS was observed in tacrolimus treated animals in both syngeneic and allogeneic combinations (Groups B and D), compared with controls (Groups A and C) (P < 0.001 and P < 0.01, respectively). TAS results correlated with the differences in TGF-beta levels that showed significant reduction when each immunosuppressed group was compared with its nontreated counterpart, i.e., (Groups B versus A, P < 0.05, and Groups D versus C, P < 0.01). TGF-beta levels were significantly high in the rejection group (C) and correlated with the intense adhesion formation that was demonstrated in that group. Group C was also the only group in which a significant elevation in HPC was demonstrated (P < 0.001).

CONCLUSION

Intense adhesion formation occurs during early posttransplant acute rejection. Postsurgical adhesion formation is significantly reduced in immunosuppressed rats after intestinal transplantation.

In vivo performance of antibiotic embedded electrospun PCL membranes for prevention of abdominal adhesions

The aim of this study was to prepare nonwoven materials from poly(epsilon-caprolactone) (PCL) and their antibiotic containing forms by electrospinning, so as to prevent postsurgery induced abdominal adhesions in rats. epsilon-Caprolactone was first polymerized by ring-opening polymerization, and then it was processed into matrices composed of nanofibers by electrospinning. A model antibiotic (Biteral) was embedded within a group of PCL membranes. In the rat model, defects on the abdominal walls in the peritoneum were made to induce adhesion. The plain or antibiotic embedded PCL membranes were implanted on the right side of the abdominal wall. No membrane implantation was made on the left side of the abdominal wall that served as control. Macroscopical and histological evaluations showed that using these barriers reduces the extent, type, and tenacity of adhesion. The antibiotic embedded membranes significantly eliminated postsurgery abdominal adhesions, and also improved healing.

Peritoneal lavage with activated protein C alters compartmentalized coagulation and fibrinolysis and improves survival in polymicrobial peritonitis

OBJECTIVE

During peritonitis, intra-abdominal fibrin entraps bacteria and hampers their elimination. Systemic administration of anticoagulant activated protein C improves survival in patients with severe sepsis, but its precise mode of action is unclear. This study in polymicrobial peritonitis assessed the effects of local activated protein C administration in peritoneal lavage fluid on coagulation, fibrinolysis, and survival.

DESIGN

Prospective, randomized study.

SETTING

University-based research laboratory.

SUBJECTS

C57BL/6 mice.

INTERVENTIONS

Twenty-four hours after induction of peritonitis by cecal ligation and puncture, mice underwent peritoneal lavage with activated protein C (1.0 microg/mL) or saline. Peritoneal lavage fluid, blood, and lungs were sampled after 24, 48, or 72 hrs (n = 8/group/time point). For survival analysis, maximum observation was 96 hrs (n = 22/group). Clotting time, tissue factor expression, thrombin-antithrombin complexes, fibrin degradation products (D-dimers), plasminogen activator, and plasminogen activator inhibitor were used to assess coagulation and fibrinolysis responses.

MEASUREMENTS AND MAIN RESULTS

Activated protein C lavage reduced abdominal bacterial load, abdominal and pulmonary clotting times, D-dimers (p < .05 vs. saline), pulmonary tissue factor expression, and fibrin depositions, without clear effects on systemic thrombin generation. Activated protein C lavage decreased plasma and abdominal tissue plasminogen activator levels with increased inhibitor plasminogen activator inhibitor-1 levels (p < .05) but had reverse effects on pulmonary fibrinolysis. Survival improved from 55% (saline) to 80% after intra-abdominal activated protein C administration (p = .03).

CONCLUSIONS

Peritoneal lavage with activated protein C may rebalance coagulation and fibrinolysis within compartments and improve survival in polymicrobial peritonitis.

Endogenous tissue-type plasminogen activator is protective during Escherichia coli-induced abdominal sepsis in mice

Sepsis is associated with enhanced production of tissue-type plasminogen activator (tPA). We investigated the function of endogenous tPA in the immune responses to Escherichia coli-induced abdominal sepsis using tPA gene-deficient (tPA(-/-)) and normal wild-type (WT) mice. tPA(-/-) mice demonstrated an impaired defense against E. coli peritonitis as indicated by higher bacterial loads at the primary site of the infection, enhanced dissemination, and reduced survival. The protective function of tPA was independent of plasmin since plasminogen gene-deficient (Plg(-/-)) mice were indistinguishable from WT mice. Relative to WT mice, tPA(-/-) mice demonstrated similar neutrophil counts in the peritoneal cavity despite much higher bacterial loads and higher local concentrations of neutrophil attracting chemokines, suggesting a reduced migratory response. In line, tPA(-/-) mice demonstrated a reduced thioglycolate-induced neutrophil influx into the peritoneal cavity and i.p. injection of WT mice with a replication-defective adenoviral vector expressing tPA caused an enhanced cell migration to the peritoneal cavity during E. coli peritonitis. These findings identify a novel protective function of tPA in abdominal sepsis caused by E. coli that seems independent of its role in the generation of plasmin.

Intraperitoneal Tenoxicam to Prevent Abdominal Adhesion Formation in a Rat Peritonitis Model

PURPOSE

We investigated the effects of intraperitoneal tenoxicam on the development of postoperative intra-abdominal adhesions and oxidative stress in a model of bacterial peritonitis.

METHODS

Bacterial peritonitis was induced in 24 rats by cecal ligation and puncture. The rats were randomly assigned to one of three groups. Group 1 (n = 8) received 2 ml saline intraperitoneally, group 2 (n = 8) received 2 ml (0.5 mg/kg) tenoxicam (Oksamen) intraperitoneally, and group 3 (n = 8) was a control, which did not receive any injection. All animals were killed 14 days later so we could assess the adhesion score and measure anastomotic bursting pressures. Tissue antioxidant levels were measured in 1-g tissue samples taken from the abdominal wall.

RESULTS

The adhesion score was significantly lower in the tenoxicam group than in the saline and control groups. The anastomotic bursting pressures were higher in the saline and tenoxicam groups than in the control group. The catalase (CAT) levels were higher in the saline and tenoxicam groups than in the control group. The malondialdehyde (MDH) levels were higher in the saline group than in the tenoxicam and control groups.

CONCLUSIONS

Intraperitoneal tenoxicam inhibited the formation of postoperative intra-abdominal adhesions without compromising wound healing in this bacterial peritonitis rat model. Tenoxicam also decreased the oxidative stress during peritonitis.

Effects of the intraperitoneal lornoxicam on the formation of intraperitoneal adhesions in rat peritonitis model

BACKGROUND

To investigate the effects of intraperitoneally administered lornoxicam on adhesion formation, bursting pressure, tissue antioxidant levels, morbidity and mortality after ileocolic anastomosis in a rat bacterial peritonitis model.

METHODS

Thirty-six rats were divided into three random groups. Bacterial peritonitis was induced by performing a cecal ligation and puncture, then the cecal was resected and ileocolic anastomosis was performed. Rats of groups 1, 2 and 3 were given 2 mL normal saline, 2 mL lornoxicam, and nothing, respectively. All groups were killed at day 14. Adhesions were scored, and the presence of intra-abdominal abscesses and fistulas were noted. Anastomotic healing was assessed by bursting pressure. Tissue antioxidant levels were tested from left abdominal walls.

RESULTS

One day after cecal ligation and puncture, microbiological examination showed polymicrobial bacterial peritonitis. The rats treated with lornoxicam had significantly lower adhesion scores than did the saline and nothing treated rats (P = 0.007). Bursting pressures of groups were unaffected by the treatment. Tissue antioxidant levels of groups were affected by the treatment. Morbidity and mortality were similar in all groups.

CONCLUSIONS

The present study demonstrated that a single intraperitoneal instillation of lornoxicam in buffer solution at the end of the surgery reduces adhesion formation in rats bacterial peritonitis model. It was also determined that lornoxicam had no negative effect on the healing of intestinal anastomosis, abscess and anastomotic leakage. Use of lornoxicam in peritonitis was effective in decreasing the oxidative stress of tissue during peritonitis.

An Assessment of the Effects of Two Types of Bioresorbable Barriers to Prevent Postoperative Intra-Abdominal Adhesions in Rats

PURPOSE

This study assessed and compared the efficacy of two types of bioresorbable membranes in the prevention of postoperative adhesion under clean contaminated and bacterial peritonitis conditions using a cecal ligation and puncture model in rats.

METHODS

Wistar albino rats (n = 72) were divided into six groups. Bacterial peritonitis was induced using a cecal ligation and puncture model in groups 2, 4, and 6. Groups 1, 3, and 5 served as controls for clean contaminated procedures in the absence of bacterial peritonitis. Groups 1 and 2 were the untreated clean contaminated and bacterial peritonitis groups and served as controls for the effect of the bioresorbable membranes in each condition. In groups 3 and 4, a 1.5 x 3 cm USP glycerol/sodium hyaluronate/carboxymethylcellulose membrane was wrapped around the cecal resection area and a 2 x 4 cm membrane was left under the incision. The oxidized regenerated cellulose membrane was similarly applied in groups 5 and 6. Four weeks later, the adhesions were evaluated. In addition, fibrosis and inflammation were observed histopathologically.

RESULTS

Adhesion development (P = .008), fibrosis (P = .008), and inflammation (P = .0001) differed among the groups. Both materials increased adhesion formation in the bacterial peritonitis condition. Increased fibrotic activity was detected in all material-applied groups under both conditions. In addition, more inflammation was detected in the groups that received the application of a material, especially in the presence of bacterial peritonitis.

CONCLUSION

Neither material prevented adhesions in clean contaminated conditions. Moreover, they increased adhesion formation in bacterial peritonitis.

Role of peritoneal mesothelial cells in peritonitis

Background

Peritoneal mesothelial cells have a remarkable capacity to respond to peritoneal insults. They generate an intense biological response and play an important role in the formation of adhesions. This review describes these activities and comments on their relationship to surgical drainage, peritoneal lavage and laparostomy in the management of patients with peritonitis.

Methods and results

Material was identified from previous review articles, references cited in original papers and a Medline search of the literature. The peritoneal mesothelium adapts to peritonitis by facilitating the clearance of contaminated fluid from the peritoneal cavity and inducing the formation of fibrinous adhesions that support the localization of contaminants. In addition, the fluid within the peritoneal cavity is a battleground in which effector mechanisms generated with the involvement of peritoneal mesothelial cells meet the contaminants. The result is a complex mix of cascading processes that have evolved to protect life in the absence of surgery.

Conclusion

Future advances in the management of patients with severe peritonitis may depend upon molecular strategies that modify the activity of peritoneal mesothelial cells.

Influence of the sampling technique on the measurement of peritoneal fibrinolytic activity

OBJECTIVE

To establish the influence of the peritoneal sampling technique on the measurement of fibrinolytic capacity.

DESIGN

Clinical study.

SETTING

University hospital, Germany.

SUBJECTS

40 peritoneal biopsy specimens were taken from 10 patients who were having elective colorectal resections.

INTERVENTIONS

Peritoneal biopsy specimens were taken either with a biopsy punch (n = 20) or manually with forceps and scissors (n = 20).

MAIN OUTCOME MEASURES

Extent of agreement in fibrinolytic activities between specimens taken with biopsy punch and manually. Major endpoint-peritoneal tissue plasminogen activator (t-PA) activity. Minor endpoints-peritoneal tissue plasminogen activator concentration, and concentration and activity of plasminogen activator inhibitior type 1 (PAT-1).

RESULTS

Intra-assay agreement and the extent of agreement between the groups were evaluated by the method of Bland and Altman. Correlation of repeated measurements of t-PA and PAI-1 concentrations and activities from the same sample using the same ELISA kit was high (r = 0.93-0.99, p < 0.01). t-PA activities and concentrations between the groups correlated poorly (r= 0.60 and 0.66, p < 0.01) while no correlation at all was seen for PAI-1 concentration and activity between the groups (r = 0.6 and 0.1, p = 0.2 and 0.9). The mean differences between the groups ranged from -27% to -4.8%.

CONCLUSION

The sampling technique considerably affects the measurement of peritoneal fibrinolytic activity.

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

BACKGROUND

Intra-abdominal adhesions and abscesses cause significant morbidity and mortality. The formation of fibrin in the abdominal cavity is a common pathophysiological pathway for both. The aim of this review was to investigate the pathophysiology of intra-abdominal adhesions and abscesses, and to explore the possible sites of action of hyaluronan.

METHODS

Data were reviewed from the literature using the Medline database.

RESULTS

Both surgery and peritonitis disturb the equilibrium between coagulation and fibrinolysis in the abdominal cavity in favour of the coagulation system. Hyaluronan-based agents reduce adhesion formation after surgery. Moreover, hyaluronan solution reduces abscess formation in experimental peritonitis. Possible mechanisms of action include mechanical separation of wound surfaces, improvement of peritoneal healing, modulation of the inflammatory response and enhanced fibrinolysis.

CONCLUSION

Diminished fibrin degradation is a common pathway for the formation of adhesions and abscesses. The potential of hyaluronan-based agents to reduce intra-abdominal adhesions and abscesses in abdominal surgery and sepsis is a promising new concept. Elucidating the mechanisms involved and the clinical application of hyaluronan in peritonitis are challenges for future research.

Prevention of intraperitoneal adhesion formation using beta-glucan after ileocolic anastomosis in a rat bacterial peritonitis model

BACKGROUND

To investigate the effects of beta-glucan on intraabdominal abscess and adhesion formation after ileocolic anastomosis in a rat bacterial peritonitis model.

METHODS

Sixty male Wistar rats were used in this study. Bacterial peritonitis was induced by performing a cecal ligation and puncture (CLP). On the first day, abdomen was reopened and peritoneal fluid samples were taken for microbiological examination. Thereafter, cecum was resected and ileocolic anastomosis was made. Group 1 rats were given 1 mL of normal saline as a placebo. Group 2 and group 3 rats were given beta-D-glucan 2 mg/kg by intramuscularly; 1 mg of beta-1,3-D-glucanase was administered to group 3 rats just after the use of beta-D-glucan. Half of each group were killed at day 7 and at day 21, respectively. Adhesions were scored and the presence of intraabdominal abscesses was noted.

RESULTS

One day after CLP, microbiological examination showed polymicrobial bacterial peritonitis. Five (8%) of the 60 animals died owing to sepsis. One week after CLP, in two rats in each group developed abscess formation. Three weeks after CLP, abscess formation was observed in only one rat in each group. The rats treated with the beta-glucan had significantly lower adhesion scores than did the saline-treated rats (P = 0.008 at one week; P = 0.001 at 3 weeks). Administration of beta-glucanase inhibited beta-glucan activity and resulted in more adhesions (P = 0.022 at 1 week; P = 0.006 at 3 weeks).

CONCLUSIONS

Although the use of beta-glucan after ileocolic anastomosis in rats with experimentally developed intraabdominal sepsis does not have any significantly effect on mortality and abscess formation, beta-glucan is capable of reducing the frequency of adhesion. This effect of beta-glucan has been prevented with beta-glucanase

Time course of peritoneal tissue plasminogen activator after experimental colonic surgery: effect of hyaluronan-based antiadhesive agents and bacterial peritonitis

BACKGROUND

This study assessed the peritoneal fibrinolytic response during the first week after colonic surgery in rats with and without bacterial peritonitis, and possible modulation of the response by two hyaluronan-based antiadhesive agents.

METHODS

A colonic anastomosis was constructed in 90 male Wistar rats. Peritonitis was induced in another 108 rats and a colonic anastomosis was constructed after 24 h. Rats in both groups were randomized into an untreated group or one of two groups treated with hyaluronan-based agents. One-third of each group was killed at each of days 1, 3 and 7 after operation, and tissue plasminogen activator (tPA) antigen and activity were measured in peritoneal biopsies.

RESULTS

One day after colonic surgery in normal rats, tPA antigen concentration was significantly (P < 0.005) increased, whereas tPA activity levels were normal. By day 3 after operation tPA antigen had returned to baseline values while tPA activity was significantly increased (P < 0.05). One day after inducing peritonitis tPA antigen was significantly increased (P < 0.001), while tPA activity was significantly reduced (P < 0.05). Three and seven days after colonic surgery in rats with peritonitis tPA activity was increased (P < 0.001) while tPA antigen had returned to baseline values. Neither of the hyaluronan-based agents affected peritoneal tPA antigen levels or activity after colonic surgery.

CONCLUSION

Both abdominal surgery and infection caused an early increase in peritoneal tPA antigen levels, followed by an increase in tPA activity. Peritonitis severely depressed early tPA activity. Application of hyaluronan-based agents did not affect the peritoneal fibrinolytic response to surgery and/or infection.

The effectiveness of systemic antibiotics in preventing postoperative, intraabdominal adhesions in an animal model

OBJECTIVE

Postoperative intraabdominal adhesions can be prevented by antibiotic lavage. We assessed whether systemic antibiotics could prevent adhesion formation in a rat model.

METHODS

Cecal abrasion was performed in the peritoneal cavities of 40 Wistar albino rats. Twenty rats were treated with a 5-day course of cefepim and metronidazole; the remaining animals were given saline injections. The animals were sacrificed 14 days after surgery. Adhesion severity scores and histopathologic findings were compared.

RESULTS

The median adhesion severity score was 2 (0-3) in the antibiotic group and 2.5 (1-4) in the controls (P = 0.03). In tissue specimens from controls, the adhesions were marked by mature collagen bundles. In treated rats, the adhesions were immature, characterized by early inflammatory cells, less collagen formation, and no collagen bundles.

CONCLUSIONS

Postoperative systemic antibiotics slow adhesion formation and reduce the severity of the adhesions.

Extracellular accumulation of bioactive substances during preparation and storage of various platelet concentrates

BACKGROUND

Side effects of platelet transfusion may be associated with infusion of bioactive substances. We therefore studied extracellular accumulation of histamine, plasminogen activator inhibitor (PAI)-1, vascular endothelial growth factor (VEGF), and interleukin (IL)-6 during preparation and storage of various platelet concentrates.

METHODS

Twenty buffy-coat-derived platelet pools (BCPC) were prepared and stored in platelet additive solutions (PAS). Twelve apheresis platelet (APC) units were prepared using the COBE Spectra LRS, and 14 were prepared using the Fenwal Amicus Separator. After preparation half of the content was drawn from each APC unit. The normal ranges of the substances were determined in plasma from all donors, and the extracellular concentrations of the substances were determined in supernatants collected on days 0, 1, 3, 5, and 7 of storage from all platelet preparations.

RESULTS

The platelet counts were not significantly different in BCPC units and APC units. The BCPC units had a significantly higher white cell count than the APC units (P < 0.0001), but the count was significantly higher in the Amicus APC units than in the COBE APC units (P < 0.0001). The extracellular histamine concentration was significantly (P < 0.001) increased in BCPC units after preparation and without further increase during storage, while there was no accumulation of histamine in APC units. After preparation the PAI-1 concentration was significantly (P < 0.02) higher in BCPC units than in APC units, but during storage PAI-1 increased significantly (P < 0.05) more in APC units than in BCPC units. Similarly, VEGF concentration was significantly (P < 0.05) higher in BCPC units than in APC units after preparation. During storage, however, VEGF increased more in BCPC units compared with COBE Spectra APC units (P < 0.05), but compared with Amicus Separator APC units only for the first 3 days of storage. At days 5 and 7 of storage the VEGF concentration was significantly higher in the Amicus APC units than in the COBE APC units (P < 0.05). IL-6 was not detectable in any of the concentrates after preparation or during storage.

CONCLUSION

Platelet concentrates prepared by the apheresis method may contain less white cell derived bioactive substances than platelet concentrates prepared by the buffy-coat method. However, a substantial storage time dependent platelet derived bioactive substance accumulation takes place in all platelet concentrates tested, presumably due to platelet disintegration.

Expression of endothelial nitric oxide synthase in human peritoneal tissue: regulation by Escherichia coli lipopolysaccharide

Changes in the expression of endothelial nitric oxide synthase (eNOS) in the peritoneum could be involved in the peritoneal dysfunction associated with peritoneal inflammation. Demonstrated recently in bovine endothelial cells was the existence of cytosolic proteins that bind to the 3'-untranslated region (3'-UTR) of eNOS mRNA and could be implicated in eNOS mRNA stabilization. The present work demonstrates that eNOS protein is expressed in human endothelial and mesothelial peritoneal cells. Escherichia coli lipopolysaccharide shortened the half-life of eNOS message, reducing eNOS protein expression in peritoneal mesothelial and endothelial cells. Moreover, under basal conditions, human peritoneal samples expressed cytosolic proteins that bind to the 3'-UTR of eNOS mRNA. The cytosolic proteins that directly bind to 3'-UTR were identified as a 60-kD protein. After incubation of human peritoneal samples with lipopolysaccharide, the binding activity of the cytosolic 60-kD protein increased in a time-dependent manner. Studies are now necessary to determine the involvement of this 60-kD protein in the regulation of eNOS expression in peritoneal cells and particularly its involvement in the peritoneal dysfunction associated with inflammatory reactions.

The Effects of Minidose Heparin and Low Molecular Weight Heparin on Peritonitis in the Rat

Intraperitoneal bacteria, ischemic tissue, and the inflammatory response have all been implicated in the development of intra-abdominal adhesions and abscess formation. Sprague Dawley rats were subjected to a peritonitis challenge induced by fecal contamination of the peritoneum in conjunction with necrotic ileal tissue in an attempt to further elucidate the role of these stimuli and to evaluate the potential protective effect of regular heparin and of low molecular weight heparin (LMWH) Lovenox. Rats treated with a subcutaneous minidose heparin and LMWH Lovenox showed a significant decrease in adhesion and abscess formation when compared with the nontreatment control rats. There was no statistical difference between the two treatment groups. These findings confirm the efficacy of minidose heparin in reducing both the grade and incidence of adhesion and abscess formation and suggest a similar role for LMWH Lovenox. No conclusions could be reached on the effect of heparin or LMWH Lovenox on survival time due to the high survival rate noted in the nontreatment control rats, despite severe peritonitis.

Prestorage leukocyte filtration may reduce leukocyte-derived bioactive substance accumulation in patients operated for burn trauma

Adverse effects of perioperative blood transfusion appear to be storage-time-dependent and may be related to extracellular accumulation of bioactive substances in blood products. In this study the clinical effects of leukofiltered and non-filtered blood products in patients undergoing surgery for burn trauma are investigated. 24 consecutive patients were randomly selected to receive transfusion with non-filtered blood components (group A, n = 12) or similar products, which were prestorage leukofiltered (group B, n = 12). The burn injury was scored using the Bull and Fischer index of age and burn surface area. Histamine, interleukin-6 (IL-6), plasminogen activator inhibitor-1 (PAI-1), eosinophil cationic protein (ECP) and myeloperoxidase (MPO) were analysed in plasma or serum collected from all patients 30 min before skin incision, at skin incision and 5, 10 and 30 min and thereafter every 30 min after skin incision until the grafts were secured by wrapping. Samples were also taken 8 h after skin incision and in the morning of postoperative days 1-5. The amount of blood products transfused from admission until day 5 postoperatively was recorded. All patients were followed until discharge or death. The Bull and Fischer index was comparable in the two groups. Prestorage leukofiltration reduced the amount of blood products required for transfusion significantly (p < 0.05) compared with non-filtered products. The levels of the various bioactive substances changed during and after the operation. In particular, ECP and MPO levels increased significantly (p < 0.05) in group A patients compared with unchanged (ECP) or decreased (MPO) levels in group B patients. IL-6 analyses showed, that the trauma had more severe impact on group B patients than on group A patients. Nevertheless, 4 patients died in group A and 2 in group B; all with a Bull and Fischer index between 1.0 and 2.0. Prestorage leukocyte filtration may reduce transfusion related accumulation of various bioactive substances and the requirement for blood in burn trauma patients.

The pathobiology of peritonitis

The peritoneum is more than a mechanical covering that allows for the easy gliding of opposed peritoneal surfaces. The peritoneal mesothelial cells facilitate the action of powerful innate immune mechanisms. In addition, the peritoneal-associated lymphoid tissues contain unique cells that may play a crucial role in the localization of intraperitoneal infection. A clearer understanding of the molecular and cellular events underlying peritoneal functions in both the unstimulated and stimulated state will aid future treatment of peritonitis.

Effect of heating on extracellular bioactive substances in stored human blood: in vitro study

BACKGROUND

We have previously shown extracellular accumulation of various leukocyte and platelet-derived bioactive substances in human blood during storage. Release of bioactive substances may be temperature-dependent, and we studied the effect of heating during in vitro transfusion on bioactive substance accumulation in stored human blood.

METHODS

Eight units of whole blood and eight units of prestorage leukofiltered whole blood were stored at 4 degrees C for 7 days. Subsequently, the blood from all 16 units was transfused via a blood-heating device, which increased the blood temperature to 37 degrees C at outlet. Samples for enzyme-linked immunosorbent assay or radioimmunoassay analyses of histamine, myeloperoxidase (MPO), eosinophil cationic protein (ECP), and plasminogen activator inhibitor-1 (PAI-1) were drawn from the units at donation, after 7 days of storage just before transfusion, and during the in vitro transfusion.

RESULTS

Extracellular concentrations of histamine, MPO, ECP, and PAI-1 were significantly (p < 0.05) increased in nonfiltered whole blood stored for 7 days compared with concentrations in fresh donated blood and in prestorage leukofiltered whole blood stored for 7 days. Heating reduced histamine, MPO, and ECP concentrations significantly (p < 0.05) in nonfiltered whole blood, whereas PAI-1 concentrations increased significantly (p < 0.05). Finally, there was no difference in concentrations of histamine, MPO, ECP, and PAI-1 in samples collected before and after heating of leukofiltered whole blood.

CONCLUSIONS

Heating reduces accumulation of extracellular leukocyte-derived bioactive substances in whole blood, whereas it increases platelet-derived substances. Prestorage leukofiltration, however, reduces the obligatory extracellular accumulation of leukocyte and platelet-derived bioactive substances, which in addition is unchanged by heating.

Leucocyte and platelet-derived bioactive substances in stored blood: effect of prestorage leucocyte filtration

Adverse reactions to transfusion of allogeneic blood may depend on content of leucocytes and platelets and on storage-time of the erythrocyte suspensions. Therefore, we studied the efficacy of prestorage leucocyte reduction by filtration on total content and extracellular accumulation of histamine, eosinophil cationic protein (ECP), eosinophil protein X (EPX), myeloperoxidase (MPO), plasminogen activator inhibitor type-1 (PAI-1) and interleukin-6 (IL-6) in samples obtained from 5 units of SAGM blood, 7 units of plasma-reduced whole-blood and 6 units of whole-blood before and after filtration, respectively. In addition, we analysed supernatants from the same units after storage at +4 degrees C for 0, 21 and 35 d, respectively. The filtration was performed at room temperature within 2-4 h after donation. The substances were analysed by ELISA and RIA methods and we also analysed the donor plasma levels of the same bioactive substances. The total content of histamine, ECP, EPX, and MPO were 10-70-fold higher in all unfiltered erythrocyte products compared to donor plasma concentrations, while PAI-1 content was 15-20-fold higher only in plasma-reduced whole-blood and whole-blood. Prestorage leucocyte filtration significantly reduced the total histamine, ECP, EPX, MPO and PAI-1 content to levels similar to donor plasma levels in plasma-reduced whole-blood and whole-blood, while PAI-1 was still low in filtered SAGM blood. In addition, the levels of extracellular bioactive substances at d 0 after donation and filtration were within the range of concentrations in donor plasma, and there was no time-dependent accumulation during storage for 35 d at +4 degrees C. IL-6 was not detected in either plasma or samples obtained from the blood bags. These results suggest prestorage leucocyte filtration to deplete leucocyte contents to levels, which prevent the previously shown time-dependent accumulation of leucocyte derived bioactive substances in various erythrocyte suspensions. In addition, the PAI-1 results suggest leucocyte filters to reduce the obligatory platelet content in whole-blood products.

Time-dependent, spontaneous release of white cell- and platelet-derived bioactive substances from stored human blood

BACKGROUND

The mechanisms of the detrimental effects of perioperative allogeneic blood transfusion are still unclear. Previous studies have suggested a higher incidence of adverse effects after the use of blood stored for prolonged time. Therefore, a possible time-dependent release of various white cell- and platelet-derived bioactive substances in stored human red cell suspensions was studied.

STUDY DESIGN AND METHODS

Whole blood (6 units), plasma-reduced whole blood (6 units), and saline-adenine-glucose-mannitol blood (6 units) from 18 unpaid, normal blood donors were stored under standard blood bank conditions at 4 degrees C for 35 days. After refrigeration, samples were collected from all blood bags on Days 0, 2, 5, 9, 14, 21, 28, and 35 of storage. Extracellular concentrations of eosinophil cationic protein, eosinophil protein X, plasminogen activator inhibitor 1, myeloperoxidase, and interleukin 6 were analyzed by enzyme-linked immunosorbent assay and radioimmunoassay. The total intracellular and donor plasma levels of these substances also were analyzed at the time of blood donation.

RESULTS

Eosinophil cationic protein, eosinophil protein X, and myeloperoxidase increased 10- to 25-fold (p < 0.05) in a time-dependent manner in whole blood, plasma-reduced whole blood, and saline-adenine-glucose-mannitol blood during storage for 35 days. Plasminogen activator inhibitor 1 increased threefold to sixfold (p < 0.05) in whole blood and plasma-reduced whole blood, but not in saline-adenine-glucose-mannitol blood. Interleukin 6 was not detected in either plasma or samples obtained from the blood bags.

CONCLUSION

Stored whole blood, plasma-reduced whole blood, and saline-adenine-glucose-mannitol blood may release white cell- and platelet-derived bioactive substances in a time-dependent manner, which may be related to the detrimental effects of perioperative blood transfusions. Therefore, prestorage white cell reduction should be considered for further improvement of red cell suspensions.

Coagulation and fibrinolytic responses of human peritoneal fluid and plasma to bacterial peritonitis

Significantly higher (P < 0.05) thrombin-antithrombin III complex levels were found in the abdominal exudate of patients with peritonitis (median 5500 ng/ml) than in that of controls (median 89 ng/ml). In patients, peritoneal fluid concentrations of tissue and urokinase-type plasminogen activator were increased by factors of 65 and 10 respectively (P < 0.05). The concentration of plasminogen activator inhibitor (PAI) 1 was increased by a factor of about 800 (median 395 versus 0.5 ng/ml, P < 0.05). Despite markedly raised concentrations of PAI, peritoneal fluid displayed fibrinolytic activity as demonstrated by significantly increased (P < 0.05) concentrations of plasmin-alpha 2-antiplasmin complex (median 10,952 versus 57 ng/ml) and fibrin degradation products (median 40,360 versus 126 ng/ml). There was no correlation between plasma and peritoneal fluid concentrations. Intraabdominal coagulation and fibrinolysis are stimulated in the abdominal cavity of patients with bacterial peritonitis.