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Item does not contain fulltext 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.

Contains fulltext : 177936.pdf (Publisher’s version ) (Closed access) BACKGROUND: For any anti-adhesive barrier developed for abdominal surgery, the use under conditions in which anastomotic healing is compromised needs to be investigated. The current study evaluates the effect of a new ultrapure alginate gel on early healing of high-risk anastomoses in the ileum and compares this with the gold standard used in clinical practice. MATERIALS AND METHODS: In 75 adult male Wistar rats, a 5 mm ileal segment was resected and continuity was restored by construction of an inverted anastomosis. Rats were divided randomly into a control group and groups receiving either alginate gel or a sodium hyaluronate carboxymethylcellulose (HA/CMC) film around the anastomosis (n = 25 each). Carprofen, given in a daily dose of 1.25 mg/kg, was used to compromise anastomotic healing. At day three, animals were killed and scored for signs of anastomotic leakage and the presence of adhesions. RESULTS: The incidence of adhesion formation was 95% in the HA/CMC film group, which was significantly higher than in the controls (64%, p = 0.010) and the alginate gel group (52%, p = 0.004). The adhesion score was nearly 40% lower in the alginate gel group compared with the HA/CMC film group. The incidence of ileal leakage in the HA/CMC film group (92%) was significantly higher than in the controls (68%, p = 0.016). Leakage rate did not differ between the alginate gel and control groups. There was no significant difference between groups in either incision bursting pressure or incision breaking strength. CONCLUSION: Ultrapure alginate gel does not interfere with repair of ileal anastomoses constructed under conditions in which chances of anastomotic dehiscence are high. The alginate gel performs better than the HA/CMC film.

Background Ultrapure alginate gel is promising in terms of adhesion prevention. Because anti-adhesive barriers have been shown to disturb healing of bowel anastomoses, the effect of ultrapure alginate gel on the repair of colon anastomoses was studied. Materials and methods In 102 male Wistar rats, a 0.5-cm segment was resected from the descending colon and continuity was restored by an inverted single-layer end-to-end anastomosis. Animals were randomized into a control, an alginate gel, and a sodium hyaluronate carboxymethyl cellulose film group, each n = 34. Half of each group was sacrificed at day 3 and 7 postoperatively. Anastomotic strength was assessed by measuring both bursting pressure and breaking strength. Hydroxyproline content was measured and histologic analysis was performed. The incidence of adhesion and abscess formation was scored at sacrifice. Results No difference in either anastomotic-bursting pressure or breaking strength was found between experimental groups and the controls at any time point. Both the incidence of adhesion formation (35% versus 71%, P = 0.007) and the adhesion score (0.38 versus 0.79, P = 0.009) were significantly lower in the alginate gel group than in the controls. The abscess rate was higher (46% versus 18%, P = 0.030) in the hyaluronate carboxymethyl cellulose group than in the controls and unchanged in the alginate gel group. Conclusions While reducing adhesion formation, ultrapure alginate gel does not interfere with the development of colonic anastomotic strength during the crucial early healing period.

Item does not contain fulltext PURPOSE: Protecting the anastomotic integrity using suture or staple line reinforcement remains an important goal for ongoing research. The present comprehensive study aims to establish the effects of fibrin glue on the early phase of anastomotic healing in the rat intestine. METHODS: One hundred and eight young adult male Wistar rats underwent resection and anastomosis of both the ileum and colon. In half, fibrin glue was applied around the anastomoses. Parameters for repair included wound strength, both bursting pressure and breaking strength at days 1, 3, and 5 after operation; hydroxyproline content; and histology, the latter also after 7 days. RESULTS: A transient colonic ileus was observed in the experimental group. Anastomotic breaking strength was always similar in both the control and fibrin glue groups. Anastomotic bursting pressures remained low at days 1 and 3, without any differences between the groups. In both groups, the bursting pressure increased sharply (p < 0.001) between days 3 and 5. At day 5, the bursting pressure in the fibrin glue group remained below than that in the controls, although only significantly (p = 0.0138) so in the ileum. At day 5, but not at day 7, the wounds in the fibrin glue group contained less collagen. Other aspects of microscopic wound architecture appeared to be the same. CONCLUSIONS: There is no justification for using fibrin glue on patent anastomoses constructed under low-risk conditions. Its potential benefit under conditions where chances for anastomotic leakage are enhanced needs further investigation. 01 augustus 2012

Contains fulltext : 96613.pdf (Publisher’s version ) (Closed access) PURPOSE: Radiofrequency ablation (RFA) has shown to improve survival in patients not eligible for surgical resection of colorectal liver metastases. However, recurrences after RFA are a major problem. Adjuvant radioimmunotherapy (RIT) after surgical resection of liver metastases has shown to improve survival. The aim of the present study was to test the hypothesis that adjuvant RIT might be an effective way to prevent recurrent liver metastases after RFA in an experimental model. METHODS: Tumours in the liver were induced by intrahepatic injection of 300,000 CC531 cells in male Wag/Rij rats (n = 60). Ten days later, the intrahepatic tumours were treated with RFA. Adjuvant RIT ((177)Lu-labelled monoclonal antibody MG1 at 300 MBq/kg) was administered intravenously either at the day of RFA (day 10) or 7 days later. Control rats received no treatment. Primary endpoint was survival. RESULTS: Administration of (177)Lu-MG1 resulted in a transient decrease in body weight, compared to no adjuvant treatment. However, no other signs of clinical discomfort were registered. Log rank test showed that the survival curves of the groups treated with RIT, either at day 10 or day 17, did not differ significantly from the survival curve of the rats that did not receive adjuvant treatment (P = 0.902). CONCLUSION: This study shows that adjuvant RIT does not increase survival after RFA of colorectal liver metastases in rats.

Contains fulltext : 89798.pdf (Publisher’s version ) (Closed access) BACKGROUND: The study aimed to analyze if peritoneal cytokine levels can predict survival in an experimental model for peritonitis. Early identification of patients most at risk for adverse outcomes would facilitate the decision for aggressive therapy in order to maximally exploit their chance for survival. STUDY DESIGN: Peritonitis was induced by intraperitoneal injection of a feces/bacteria mixture in 175 rats. Surgical debridement was performed after 1 hour. Abdominal fluid samples were taken after 24 and 72 hours for the measurement of interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-alpha. Surviving animals were sacrificed after 5 days and correlations between cytokine levels and survival were analyzed. RESULTS: Altogether, 60 animals died prematurely, 12 before the first sampling of cytokines. So, 48 nonsurvivors and 115 survivors were analyzed. Peritoneal cytokine levels were much higher (p < 0.0001) in nonsurvivors than in survivors. At 24 hours there were strong correlations between cytokine levels, especially between IL-6 and IL-10 (r = 0.93). Peritoneal cytokines at 24 hours also discriminated between animals dying within the next 24 hours and those dying later. A strongly (p < 0.0001) increased mortality was observed if IL-6, IL-10, or TNF-alpha levels exceeded 2, 1, or 0.2 ng/mL, respectively. Receiver operating characteristic curves were promising for all 3, but IL-10 showed the best characteristics, with an area under the curve of 0.94 and 67% sensitivity at 95% specificity, obtained at a cut-off value of 1.26 ng/mL. CONCLUSIONS: These data should generate renewed interest to examine the peritoneal cytokines as early markers for adverse outcomes in patients with secondary peritonitis. Possibly, combinations of peritoneal cytokines with other markers can lead to much needed, reliable early prediction of disease severity. 01 augustus 2010

Contains fulltext : 89457.pdf (Publisher’s version ) (Closed access) PURPOSE: Experimental studies indicate that perioperative hypoperfusion impairs anastomotic healing. In bowel surgery, the part of bowel that will be anastomosed is often pedicled, leaving the blood supply dependent on the marginal artery only. Little is known about the blood supply in such a segment, and whether anastomotic strength is affected when flow would be reduced. This study describes oxygenation and blood flow in pedicled bowel segments in the rat and investigates whether early anastomotic strength changes with variations in blood flow. METHODS: In rats, pedicled segments were created in ileum and colon by successive ligation of the feeding arteries. Oxygenation and blood flow were measured in the distal part of this segment by use of near-infrared spectroscopy with indocyanine green as an intravascular tracer. In a second experiment, a short pedicled colonic segment was created and, after flow measurements, an anastomosis was constructed. Wound strength and hydroxyproline content were analyzed 2 and 5 days after operation. RESULTS: After creation of a pedicled segment, the concentration of oxygenated hemoglobin decreased significantly. Blood flow also significantly decreased to even less than 10% of baseline. A very large variation was observed between animals, in particular, after ligation of the first arteries. The strength of colonic anastomoses was not significantly correlated with the blood flow in the pedicled segment before anastomotic construction. CONCLUSIONS: The creation of a pedicled bowel segment greatly reduces tissue oxygenation and blood flow to its distal part. Such impaired perioperative flow does not significantly affect early wound strength after anastomotic construction. 01 januari 2010

Contains fulltext : 88879.pdf (Publisher’s version ) (Closed access) The role of the IL-17 pathway in antifungal host defense is controversial. Several studies suggested that IL-17 is crucial for the protection against Candida infection, whereas other studies reported that IL-17 may contribute to inflammatory pathology and worsening of fungal disease. To address these discrepancies, we assessed the differential role of IL-17 pathway in two models of fungal sepsis: intravenous infection with live Candida albicans, in which fungal growth is the main cause of mortality, and zymosan-induced multiple organ failure, in which the inflammatory pathology drives the mortality. First, IL-17 receptor-deficient (IL-17RA) mice showed increased mortality and higher fungal loads in the kidneys in the model of disseminated candidiasis, partly caused by lower neutrophil recruitment in the IL-17RA mice. Second, IL-17RA mice were not protected against the multiorgan failure induced by zymosan. These data demonstrate that IL-17 does not have a major contribution to the inflammatory pathology leading to organ failure in fungal sepsis and support the concept that the IL-17 pathway is protective in antifungal host defense. 01 oktober 2010

Contains fulltext : 81116.pdf (Publisher’s version ) (Closed access) Early administration of fibrinolytics after surgical treatment of peritonitis in the rat reduces abscess formation. The current study investigates the effect of various treatment protocols using intraperitoneal recombinant tissue plasminogen activator (rtPA). Peritonitis was induced in rats and surgical debridement was performed after 1 hour. Animals were treated with rtPA at different time points. Abdominal fluid samples were taken at 24, 72, and 120 hours for cytokine measurements and cell counts. After 5 days the abdomen was inspected for abscesses. Early administration of rtPA significantly reduced the number of rats with abscesses and the abscess load per rat. Delayed treatment significantly reduced abscess load but not the incidence of abscesses. No meaningful differences in the local inflammatory response were found. rtPA was most effective when applied early and continued for 72 hours, although mortality increased after prolonged treatment. rtPA consistently reduces intra-abdominal abscess formation, and a clinical study seems warranted.

Contains fulltext : 81121.pdf (Publisher’s version ) (Closed access) BACKGROUND: Intra-abdominal application of recombinant tissue-type plasminogen activator (rtPA) can decrease the rate of abscess formation in a rat peritonitis model. Before using rtPA clinically, its effects on healing of bowel anastomoses and laparotomy wounds should be investigated. METHODS: Peritonitis was induced in 148 male Wistar rats via intra-abdominal injection of a feces/bacteria mixture. Laparotomy, operative debridement and construction of a colo-colostomy after a limited colectomy or ileo-ileostomy after a limited ileal resection were performed after 1 hour. All animals received antibiotics (ceftriaxone plus metronidazole). In addition to untreated controls, other animals received rtPA in 1 of 3 dosing schemes, starting immediately after operation or 24 hour afterwards. Wound strength and hydroxyproline content of the wound were analyzed after 3 or 7 days. RESULTS: Mortality was 2% and manifestations of excessive bleeding were virtually absent. RtPA significantly decreased the rate of abscess formation. Neither bursting pressure nor breaking strength of the anastomoses was affected by any of the rtPA protocols. The same was true for wound strength in the abdominal fascia. Additionally, wound hydroxyproline content and architecture remained unchanged after rtPA administration. CONCLUSION: Intraperitoneal rtPA administration consistently and significantly decreased the rate of abscess formation, but did not affect wound healing. Clinical studies investigating its potential as an adjunct in the treatment of secondary peritonitis may be warranted.

Item does not contain fulltext We have shown in several controlled rat and human infection studies that dietary calcium improves intestinal resistance and strengthens the mucosal barrier. Reinforcement of gut barrier function may alleviate inflammatory bowel disease (IBD). Therefore, we investigated the effect of supplemental calcium on spontaneous colitis development in an experimental rat model of IBD. HLA-B27 transgenic rats were fed a purified high-fat diet containing either a low or high calcium concentration (30 and 120 mmol CaHPO4/kg diet, respectively) for almost 7 wk. Inert chromium EDTA (CrEDTA) was added to the diets to quantify intestinal permeability by measuring urinary CrEDTA excretion. Relative fecal wet weight was determined to quantify diarrhea. Colonic inflammation was determined histologically and by measuring mucosal interleukin (IL)-1beta. In addition, colonic mucosal gene expression of individual rats was analyzed using whole-genome microarrays. The calcium diet significantly inhibited the increase in intestinal permeability and diarrhea with time in HLA-B27 rats developing colitis compared with the control transgenic rats. Mucosal IL-1beta levels were lower in calcium-fed rats and histological colitis scores tended to be lower (P = 0.08). Supplemental calcium prevented the colitis-induced increase in the expression of extracellular matrix remodeling genes (e.g. matrix metalloproteinases, procollagens, and fibronectin), which was confirmed by quantitative real-time PCR and gelatin zymography. In conclusion, dietary calcium ameliorates several important aspects of colitis severity in HLA-B27 transgenic rats. Reduction of mucosal irritation by luminal components might be part of the mechanism. These results show promise for supplemental calcium as effective adjunct therapy for IBD.

Background Intra-abdominal abscesses are sources of recurrent or ongoing abdominal sepsis. They are an important target for prevention and treatment during or after surgical treatment of peritonitis. Experimental data suggest that fibrinolytic therapy may be effective when antibiotics are not. Methods Peritonitis was induced via intra-abdominal injection of a faeces and bacteria mixture in male Wistar rats. Surgical debridement was performed after 1 h. Next to untreated controls, animals were treated with antibiotics (ceftriaxone plus metronidazole), recombinant tissue plasminogen activator (rtPA) or both. Abdominal fluid samples were taken at 24, 72 and 120 h for interleukin 6, interleukin 10 and tumour necrosis factor α measurements and cell counts. After 5 days the abdomen was inspected for the presence of abscesses. Results Antibiotics did not significantly affect abscess formation. However, giving rtPA significantly reduced the number of rats with abscesses and the abscess load per rat, both in the absence and presence of concomitant antibiotic therapy. No adverse side-effects were observed and no meaningful differences in the local inflammatory response were found. Conclusion In this rat model, rtPA consistently reduced abscess formation after surgical treatment of secondary peritonitis. It therefore represents a promising adjuvant to conventional therapy.

Contains fulltext : 70763.pdf (Publisher’s version ) (Closed access) BACKGROUND: Cytoreductive surgery (CS) followed by hyperthermic intraperitoneal chemotherapy (HIPEC) results in limited survival benefit and high morbidity and mortality rates in patients with peritoneal carcinomatosis (PC). Radioimmunotherapy (RIT) after CS of experimental PC has been shown to increase survival and compare favorably to HIPEC. The effects of RIT and HIPEC on wound healing after CS need to be determined. METHODS: PC was induced by intraperitoneal inoculation of CC-531 colon carcinoma cells in Wag/Rij rats. Animals were subjected to CS and anastomotic construction only or followed by RIT or HIPEC. RIT consisted of 74 MBq (177)lutetium-labeled anti-CC531 antibody MG1. HIPEC was performed by a closed abdominal perfusion technique using mitomycin-C during 60 minutes. Anastomotic and abdominal wall strength measurements were performed 3 and 5 days after surgery. RESULTS: At day 5, bursting pressure in ileum and colon anastomoses in the CS + HIPEC group, but not in the CS + RIT group, was lower (P < .01) than in the CS group. In the CS group, the colonic bursting site was more often outside the true anastomotic area (8 of 12 animals) than in the CS + HIPEC (1 of 12) and CS + RIT (5 of 12) groups. Abdominal wall strength in the CS + HIPEC group was significantly (P < .01) lower, at both measuring points, than that in both the CS group and the CS + RIT group. There was no difference between the latter. CONCLUSION: As adjuvant to CS, HIPEC showed a decrease in anastomotic and abdominal wall wound strength in a model of PC of CRC, whereas RIT did not.

Contains fulltext : 52894.pdf (Publisher’s version ) (Closed access) BACKGROUND: Cytoreductive surgery (CS) followed by heated intraperitoneal chemotherapy (HIPEC) is considered the standard of care for the treatment of patients with peritoneal carcinomatosis (PC) of colorectal cancer (CRC). These surgical procedures result in a median survival of 2 years at the cost of considerable morbidity and mortality. In preclinical studies, radioimmunotherapy (RIT) improved survival after CS in a model of induced PC of colonic origin. In the present studies we aimed to compare the efficacy and toxicity of CS followed by adjuvant RIT in experimental PC to the standard of care, HIPEC. METHODS: PC was induced by intraperitoneal inoculation of CC-531 colon carcinoma cells in three groups of Wag/Rij rats. Treatment comprised CS only, CS + RIT or CS + HIPEC, immediately after surgery. RIT consisted of intraperitoneal administration of 74 MBq Lutetium-177 labeled MG1. HIPEC was performed by a closed abdomen perfusion technique using mitomycin C (16 mg/L during 60 minutes). The primary endpoint was survival. RESULTS: CS only or combined with RIT was well tolerated. Rats receiving CS + HIPEC were lethargic, suffered from diarrhea, and lost significantly more weight in the first postoperative week. Median survival of rats treated with CS + RIT was significantly longer than after CS alone (97 and 57 days, respectively, P < .004), whereas survival after CS + HIPEC or CS alone were not significantly different (76 and 57 days, respectively, P = .17). CONCLUSION: Survival after CS was significantly improved by RIT with Lutetium-177-MG1 in rats with PC of colorectal origin. Adjuvant HIPEC did not improve survival and was more toxic than adjuvant RIT.

Item does not contain fulltext BACKGROUND: Nonsteroidal anti-inflammatory drugs have been associated with anastomotic leakage. It was studied if diclofenac affects anastomoses differently depending on the location in the gut. METHODS: Ninety-five rats were randomized to 6 groups with an anastomosis in either ileum (IL), proximal colon (PC), or distal colon (DC). Groups IL+ (n = 10), PC+ (n = 30), and DC+ (n = 10) received diclofenac (3 mg/kg/day) from day 0 until sacrifice on day 3. Group PC- (n = 15) did not receive diclofenac. Groups PC1+ and PC2+ (n = 15 each) were given diclofenac from day 1 to 4 and from day 2 to 5. RESULTS: Leak rates were 10/10 in group IL+, 22/30 in PC+, 1/10 in DC+, and 1/15 in PC-. Delayed administration of diclofenac by 1 or 2 days (6/15, P = .05) resulted in reduced leakage rates. Mechanical strength results corresponded with leak rates. CONCLUSIONS: Diclofenac causes leakage of anastomoses in rat IL and PC, but not in the DC. This suggests a role for the ileal and proximal colonic content in diclofenac-induced leakage.

Contains fulltext : 152926.pdf (Publisher’s version ) (Closed access) A persistent clinical demand exists for a suitable arterial prosthesis. In this study, a vascular conduit mimicking the native 3-layered artery, and constructed from the extracellular matrix proteins type I collagen and elastin, was evaluated for its performance as a blood vessel equivalent. A tubular 3-layered graft (elastin-collagen-collagen) was prepared using highly purified type I collagen fibrils and elastin fibers, resembling the 3-layered native blood vessel architecture. The vascular graft was crosslinked and heparinised (37 +/- 4 mug heparin/mg graft), and evaluated as a vascular graft using a porcine bilateral iliac artery model. An intra-animal comparison with clinically-used heparinised ePTFE (Propaten(R)) was made. Analyses included biochemical characterization, duplex scanning, (immuno)histochemistry and scanning electron microscopy. The tubular graft was easy to handle with adequate suturability. Implantation resulted in pulsating grafts without leakage. One week after implantation, both ePTFE and the natural acellular graft had 100% patencies on duplex scanning. Grafts were partially endothelialised (Von Willebrand-positive endothelium with a laminin-positive basal membrane layer). After one month, layered thrombi were found in the natural (4/4) and ePTFE graft (1/4), resulting in occlusion which in case of the natural graft is likely due to the porosity of the inner elastin layer. In vivo application of a molecularly-defined tubular graft, based on nature's matrix proteins, for vascular surgery is feasible.

Contains fulltext : 52657.pdf (Publisher’s version ) (Closed access) BACKGROUND: Treatment of patients with peritoneal carcinomatosis (PC) of colorectal cancer (CRC) includes cytoreductive surgery (CS) in combination with (hyperthermic) intraperitoneal chemotherapy (HIPEC), resulting in a limited survival benefit with high morbidity and mortality rates. Radioimmunotherapy (RIT) as adjuvant therapy after CS of CRC has been shown to prolong survival in preclinical studies. However, the optimal setting of RIT remains to be determined. METHODS: PC was induced by intraperitoneal inoculation of CC-531 colon carcinoma cells in Wag/Rij rats. Animals were subjected to exploratory laparotomy (Sham), CS only or CS + RIT at different time points after surgery. RIT consisted of 55 MBq lutetium-177-labelled anti-CC531 antibody MG1 (183 mug). The primary endpoint was survival. RESULTS: Cytoreductive surgery with or without RIT was well tolerated. Median survival of animals in the Sham and CS group was 29 days and 39 days, respectively (P < 0.04). Compared to CS alone, median survival of rats after adjuvant RIT was 77 days (P < 0.0001), 52 days (P < 0.0001) and 45 days (P < 0.0001) when given directly, 4 and 14 days after surgery, respectively. CONCLUSION: The efficacy of adjuvant RIT after CS for the treatment of PC of colonic origin decreases when the administration of the radiolabelled MAbs is postponed. This study shows that adjuvant RIT should be given as early as possible after surgery.

Contains fulltext : 50770.pdf (Publisher’s version ) (Closed access) BACKGROUND: Under certain conditions, transient intestinal ischemia can reduce anastomotic strength. Preliminary findings suggest that prolonged reperfusion time, before anastomotic construction, results in reduced wound strength. The purpose of this study is to determine if wound strength indeed decreases with increasing duration of the interval between an ischemic period and construction of an anastomosis. METHODS: In male Wistar rats, ischemia was induced by crossclamping the superior mesenteric artery (SMA) for 40 minutes. In control groups, the SMA was exposed but not clamped. Resection and anastomosis in both ileum and colon were performed immediately after release of the clamp or after 90 minutes or 24 hours. Both the anastomotic bursting pressure and breaking strength were measured after 3 or 5 days, together with hydroxyproline levels. RESULTS: Neither bursting pressure nor breaking strength, either in ileum or in colon, changed significantly when the time between the end of ischemia and anastomotic construction increased. Similar values were obtained in all experimental and corresponding control groups. In the group in which anastomoses were constructed after 24-hour reperfusion, mechanical strength increased significantly from day 3 to day 5 and at the same rate as in the control group. No differences in anastomotic hydroxyproline levels were found between experimental and control groups analyzed at day 5. CONCLUSIONS: A prolonged interval between intestinal ischemia and anastomotic construction does not affect development of early wound strength. Therefore, delayed anastomosis after transient ischemia is not likely to increase the risk of anastomotic complications.

Contains fulltext : 48595.pdf (Publisher’s version ) (Closed access) PURPOSE: The strength of the uninjured and anastomosed intestinal wall is determined by its submucosal connective tissue. Matrix degradation by matrix metalloproteinases may result in loss of strength. It is known that anastomotic construction leads to up-regulation of matrix metalloproteinase activity in the wound area, but no quantitative data are available as to the extent of this effect throughout the intestinal wall. This study was designed to quantitate changes in gelatinolytic activity in the intestine after anastomotic construction in the ileum or colon. METHODS: An anastomosis was constructed in the distal ileum or distal colon of rats, and animals were killed after one or three days. Tissue samples (5 mm) were collected containing the suture line, its adjacent segments (2- x 5-mm in both directions) and at nine other, more distant, sites throughout the gastrointestinal tract. Similar samples were collected from nonoperated control rats. All samples were analyzed by quantitative gelatin zymography. RESULTS: In control rats, the most prominent gelatinolytic activities were found at 80 kDa, thought to represent a nonspecific proteolytic activity, 60 kDa and 50 kDa, representing the proform and active form of matrix metalloproteinase-2, respectively. Activities were higher in the small bowel than in the large bowel. Anastomotic construction led to massive up-regulation of an activity at 105 kDa, and its dimer, believed to represent promatrix metalloproteinase-9. Matrix metalloproteinase-2 remained unaffected, whereas the activity of the 80 kDa protein was significantly (P < 0.05) reduced. Significantly increased matrix metalloproteinase-9 activity was found in the actual anastomotic segments and in the immediately adjacent tissue. Matrix metalloproteinase-9 activities in the anastomotic segments were highest at Day 1 in the ileum and at Day 3 in the colon. Anastomotic construction in the ileum or colon did not lead to any significant changes of any gelatinolytic activity at the more distant sites in the bowel wall. CONCLUSIONS: Up-regulation of gelatinase activity after anastomotic construction in the intestine is caused by matrix metalloproteinase-9. Because the effect is local and not systemic, unwanted matrix degradation at distant sites seems unlikely.

Contains fulltext : 47937.pdf (Publisher’s version ) (Closed access) AIM: To investigate whether the inflammatory response of cultured endothelial cells, as induced by conditioned plasma, depends on the bacterial species or type of antibiotic used for incubation with whole blood. MATERIALS AND METHODS: Blood from healthy volunteers was stimulated ex vivo with different microorganisms, and with bacteria killed with different antibiotics. The resultant plasmas were incubated on monolayers of cultured human endothelial cells, followed by measurement of their permeability to albumin and expression of E-selectin and intercellular adhesion molecule-1. RESULTS: Incubation of Escherichia coli in blood yielded plasmas that induced a marked increase in endothelial permeability and E-selectin expression. The response to Bacteroides fragilis or Enterococcus faecalis was generally weaker. Similar effects were observed after incubation of whole blood with lipopolysaccharide (LPS). Much of the permeability and adhesion molecule response to E. coli remained after removal of intact microorganisms from the culture. Whereas antibiotic treatment of E. coli with imipenem or cefuroxime resulted in a divergent production of tumour necrosis factor-alpha (TNF-alpha) in blood, no significant differences between these treatments were observed with respect to the plasma-induced endothelial response. CONCLUSION: Bacteria differ in their capacity to generate a whole blood-mediated increase of endothelial permeability and adhesion molecule expression; this response depends, at least in part, on the presence of soluble bacterial components, such as LPS. Whereas treatment with various antibiotics may generate varying amounts of TNF-alpha, these differences are not translated into differences in endothelial permeability or adhesion molecule expression.

Contains fulltext : 48975.pdf (Publisher’s version ) (Closed access) BACKGROUND: Little is known about the impact of repeated laparotomies on intestinal anastomotic healing. While experimental data are completely lacking, the sparse data available from clinical studies report high anastomotic failure rates, suggesting a negative effect in this respect. Since the unequivocal determination of such an effect may have important consequences for choosing the optimal treatment strategy for patients suffering from intra-abdominal infection, an experimental study has been performed in an established rodent model. METHODS: Intestinal anastomoses were constructed in healthy Wistar rats (ileal and colonic anastomoses) or 24 h after peritonitis was induced by caecal ligation and puncture (colonic anastomosis only). Rats were then scheduled to undergo no, one (after 24 h) or two relaparotomies (after 24 and 48 h). Anastomotic strength was assessed 3 and 5 days after anastomotic construction. On the third post-operative day anastomotic hydroxyproline levels, matrix metalloproteinase activity and myeloperoxidase activity were measured. RESULTS: No negative impact of repeated laparotomies was measured on any of the parameters measured. Under non-infectious conditions even an improvement in breaking strength (+48%, p=0.017) but not bursting pressure was found after two relaparotomies, but only in the ileum on the third post-operative day. CONCLUSIONS: In this experimental setting, early anastomotic healing is not adversely affected by repeated laparotomies.

Item does not contain fulltext OBJECTIVE: To investigate the effects of pentoxifylline (PTX) administration in a murine model for the multiple-organ dysfunction syndrome (MODS). DESIGN AND SETTING: Prospective double-blind randomized animal study in a university research laboratory. INTERVENTIONS AND MEASUREMENTS: Sixty C57BL/6 mice were given an aseptic intraperitoneal injection of lipopolysaccharide followed after 6 days by zymosan (day 0) at a dose of either 0.9 or 1.0 mg/g body weight. Starting on day 0 mice were administered PTX at a dose of 80 mg/kg body weight or saline per os every 8 h. On day 17 surviving animals were killed, and their liver, lungs, spleen, and kidneys were collected. RESULTS: Mortality, course of body temperature, body weight, and macroscopic lung damage were similar between zymosan-treated groups. Administration of PTX did not significantly alter survival, body temperature, body weight, or macroscopic lung damage. In addition, there were no significant differences in organ weights between mice that received PTX and mice that received PBS. Although PTX inhibited the lipopolysaccharide-induced increase in tumor necrosis factor alpha and interleukin 6 expression (but not interleukin 1beta expression) at both mRNA and protein level in a murine macrophage cell line, tumor necrosis factor alpha mRNA expression in the livers of PTX-treated mice was not significantly inhibited. CONCLUSIONS: The results reported here do not support the hypothesis that PTX improves outcome in zymosan-induced multiple-organ dysfunction in mice.

Contains fulltext : 59237.pdf (Publisher’s version ) (Closed access) OBJECTIVE: We sought to quantitate the course of specific cytokine mRNA expression in tissues that exhibit increasing histopathological changes in time in an animal model for the multiple organ dysfunction syndrome (MODS). SUMMARY BACKGROUND DATA: The development of treatment protocols for MODS requires elucidation of the mechanisms and mediators involved. To devise logical interventions, it is necessary to collect data on cytokine expression at tissue level during the development of MODS. METHODS: Ninety-four C57BL/6 mice were given an intraperitoneal injection of 40 microg of lipopolysaccharide (LPS), followed by zymosan at a dose of 0.8 mg/g body weight 6 days later (day 0). Six additional animals did not receive zymosan and acted as controls. At several time points after zymosan injection, 6 randomly assigned, zymosan-treated animals were killed, and their livers, lungs, spleens, and kidneys were collected. mRNA expression of tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-6, macrophage migration inhibiting factor, IL-12, interferon-gamma, and IL-10 was measured using a real-time reverse transcription-polymerase chain reaction assay. RESULTS: The injection of zymosan induced an acute peritonitis, followed by an apparent recovery. From approximately day 6 onwards, animals started to display MODS-like symptoms. During the peritonitis phase, up-regulation of cytokine mRNA was limited. During the period of apparent recovery, cytokine mRNA expression strongly increased, mostly reaching its maximum at day 9 when deterioration of the clinical condition had already set in. The up-regulation of tumor necrosis factor-alpha mRNA was most pronounced, especially in the lungs and liver. CONCLUSIONS: Interventions should preferentially be targeted against multiple cytokines and, at least in this model, there may be a treatment window well after the initial challenge.

Background Clinical studies report conflicting results on the safety of primary intestinal anastomoses in the presence of peritonitis, and comprehensive experimental data are lacking. The present study investigated whether the strength of experimental colonic anastomoses is affected if surgery is performed in the presence of pre-existing bacterial peritonitis. Methods Colonic anastomoses were constructed in Wistar rats 24 h after caecal ligation and puncture or a sham procedure. Anastomotic strength was assessed by measuring breaking strength and bursting pressure during the first 5 days after operation. Anastomotic hydroxyproline levels were measured and matrix metalloproteinase (MMP) activity was analysed by quantitative gelatin zymography. Results Anastomotic strength was lowered in the presence of bacterial peritonitis but in a minor and transient way. The breaking strength was lower only immediately after construction of the anastomosis (− 15 per cent, P = 0·011) and the bursting pressure only on the third postoperative day (− 33 per cent, P = 0·038); no anastomotic dehiscence was observed. At 3 days after operation increased levels of MMP activity were observed but anastomotic hydroxyproline content was not affected by bacterial peritonitis. Conclusion The influence of bacterial peritonitis on the development of anastomotic strength is limited. This experimental finding lends support to recent clinical studies that have demonstrated the feasibility of constructing a primary anastomosis under these conditions.

Background and aims. The strength of intestinal anastomoses is relatively low in the first days after operation, possibly as a result of localized degradation of the supporting matrix by enzymes from the matrix metalloproteinase (MMP) family. This study examined whether BB-94, a broad spectrum inhibitor of MMP activity, could enhance anastomotic strength. Materials and methods. Male Wistar rats received anastomoses in both ileum and colon. From the day before operation onwards, animals were treated daily with BB-94 intraperitoneally at a dose of 30 mg/kg or with saline only. Rats were killed 1, 3, or 7 days after operation, and anastomotic bursting pressure and breaking strength were measured. On day 3 anastomotic hydroxyproline levels were measured, and MMP (gelatinase) activity was analyzed by gelatin zymography. Results. BB-94 strongly enhanced wound strength, but only on day 3, when it was at its lowest. Daily administration increased median colonic and ileal breaking strength by 27% and 108%, respectively; colonic and ileal bursting pressure were increased by 54% and 58%, respectively. MMP activities were significantly lowered in anastomotic extracts from the rats treated with BB-94. Conclusion. Administration of BB-94 enhances anastomotic strength. Specific inhibition of MMP activity should be investigated further as a means to preserve anastomotic integrity.

PURPOSE: Early postoperative strength in intestinal anastomoses is reduced in diabetic rats, whereas collagen deposition is essentially unchanged, suggesting that increased matrix degradation may be the cause of diminished wound strength. The aim of this study was to investigate whether (gelatin-degrading) matrix metalloproteinase activity is enhanced in intestinal anastomoses from diabetic rats. METHODS: Sixty male young adult Wistar rats underwent resection and anastomosis of both ileum and colon. In half the animals diabetes was induced seven days before operation by streptozotocin injection (50 mg/kg intravenously). Gelatinase activities in extracts from uninjured intestine and anastomoses at one, three, or seven days after surgery were measured by quantitative gelatin zymography. RESULTS: After surgery, profound changes were observed with time for gelatinase activities with molecular weights of 50 and 60 kDa, thought to represent matrix metalloproteinase-2, and of 66, 80, 105, 140, 220, and 260 kDa, thought to represent various forms of matrix metalloproteinase-9. In many cases, specific activities were significantly (P < 0.05) higher in the anastomotic extracts from diabetic rats. Total anastomotic activities present at Day 7 were strongly elevated for most matrix metalloproteinase forms in ileum and colon from diabetic animals. CONCLUSION: Experimental diabetes leads to a sustained and elevated presence of gelatinase activity in intestinal anastomoses. Increased local matrix degradation may contribute significantly to impaired anastomotic strength in the intestine observed under this condition.

Item does not contain fulltext The purpose of the study was to investigate the course of the zymosan-induced multiple organ dysfunction syndrome (MODS) in the absence of tumor necrosis factor (TNF) in a murine model. Tumor Necrosis Factor-alpha-lymphotoxin-a knockout (TNF/LT-/-) mice (n = 36) and wild-type (TNF/LT+/+) mice (n = 36) received 40 microg of lipopolysaccharide (LPS) intraperitoneally followed by zymosan at a dose of 1 mg/g body weight 6 days later (day 0). Animals were monitored daily for body weight and temperature and clinical symptoms. At day 22, most of the surviving mice were killed to examine organ weight and histology. A small number of animals were followed until day 48. In all animals, zymosan induced an acute sterile peritonitis phase followed by an apparent recovery. From day 8 onwards the TNF/LT+/+ mice entered a third-MODS-like-phase, characterized by loss of body weight, decreased body temperature, and significant mortality. At day 22, survival in the TNF/LT-/- mice (92%) was significantly (P = 0.01) higher than in the TNF/LT+/+ mice (60%). In addition, average body temperature and average relative (vs. weight at day 0) body weight were higher in the TNF/LT-/- mice than in the TNF/LT+/+ mice (35.9 degrees C and 100% vs. 33.3 degrees C and 84%, respectively). However, at this time point, surviving animals from both groups showed similar and significant organ damage, indicated by an increase in absolute and relative (vs body weight) weight of lung, spleen, and liver (liver only in the TNF/LT-/- mice). Moreover, histopathological examination of organs from the surviving animals showed a similar degree of microscopic damage in both groups. Interestingly, besides mononuclear cells, inflammatory infiltrates in lungs and livers of TNF/LT+/+ but not of TNF-/- mice contained neutrophils. In conclusion, TNF-deficient mice exhibit significantly improved morbidity and mortality during zymosan-induced MODS. However, the absence of TNF does not completely protect against MODS in this murine model.

Item does not contain fulltext The authors examined the potential of the cyclooxygenase 2 (COX-2) inhibitor carprofen to reproducibly induce anastomotic leakage. In experiment 1, an anastomosis was constructed in both ileum and colon of 20 rats, and they were given carprofen (5 mg/kg subcutaneously every 24 hours) or buprenorphine (0.02 mg/kg subcutaneously every 12 hours). In another 20 rats an anastomosis was constructed in either ileum or colon, and all received carprofen (experiment 2). Animals were sacrificed after 3 days. In experiment 1, the ileal dehiscence rate was 60% in the carprofen group and 0% in the buprenorphine group (P = .0108). Colonic anastomoses in both groups remained patent. In experiment 2, the anastomotic leakage rate was 80% in ileum and 0% in colon. Thus, COX-2 inhibitors can severely interfere with intestinal healing, particularly in the ileum. Perioperative administration of carprofen yields a unique model for anastomotic leakage, which allows translational research on the effectiveness of perisuture line reinforcement.

Item does not contain fulltext BACKGROUND: Non-steroid anti-inflammatory drugs such as the cyclooxygenase isoenzyme inhibitors diclofenac and naproxen are increasingly used for perioperative pain relief, while their potential effects on wound healing are scarcely investigated. METHODS: In 104 male Wistar rats, an anastomosis was constructed in both colon and ileum. The rats were divided into groups who received diclofenac (4 mg kg(-1) day(-1)) or naproxen (10 mg kg(-1) day(-1)) daily from the day of surgery or from day 3 after surgery. Animals were killed on day 3 or 7 and analysed for signs of anastomotic dehiscence and wound strength of anastomoses and abdominal fascia. RESULTS: Anastomotic leakage in the ileum (p < 0.0001) and mortality rates (p = 0.001) were significantly increased in the diclofenac group. On day 7, the anastomotic bursting pressure in the ileum remained below that of the controls in the diclofenac- and naproxen-treated rats. When administration of diclofenac was postponed to day 3 after surgery, anastomotic dehiscence was almost absent. The colonic anastomosis and abdominal wall always remained unaffected. CONCLUSIONS: This study implies that immediate postoperative administration of diclofenac and, to a far lesser extent, naproxen can affect healing in the ileal anastomosis in the rat. This negative effect can be prevented by a short postoperative delay in administration. On steroid anti-inflammatory drugs such as the cyclooxygenase isoenzyme inhibitors diclofenac and naproxen are increasingly used for perioperative pain relief, while their potential effects on wound healing are scarcely investigated.

Background Postoperative adhesion formation is a common consequence of abdominal surgery, and constitutes a major source of morbidity and mortality. This study evaluated an ultrapure alginate-based antiadhesive barrier gel. Methods Experiments were performed in a rat model with caecal abrasion and peritoneal side wall excision. The primary endpoint was the incidence of adhesions at 14 days after surgery. In experiment 1 (24 rats), animals treated with alginate gel were compared with controls that had no antiadhesive barrier. In experiment 2 (42 rats), alginate gel was compared with sodium hyaluronate carboxymethyl cellulose (HA/CMC) membrane and with no antiadhesive barrier. To check for any remote action of the gel, in experiment 3 (45 rats) application of alginate gel to the ipsilateral versus contralateral side of injury was compared with no antiadhesive barrier. Results In experiment 1, ultrapure alginate gel reduced the incidence of adhesions from eight of 12 in control animals to one in 12 (P = 0·009). Tissue healing assessed by histology was similar in both groups. In experiment 2, ultrapure alginate gel and HA/CMC membrane showed similar antiadhesive effectiveness, reducing the incidence of adhesions from ten of 14 rats in the control group to three of 14 (P = 0·021) and two of 14 (P = 0·006) respectively. In experiment 3, ultrapure alginate gel reduced the incidence of adhesions at the site of direct application (1 of 15) compared with controls (13 of 15; P = 0·001), but not if applied remotely (9 of 15; P = 0·214). Conclusion Ultrapure alginate gel decreased the incidence of postoperative adhesion formation in this rat model.

Contains fulltext : 155447.PDF (Publisher’s version ) (Open Access) BACKGROUND: Use of immunosuppressant drugs has been associated with complications in wound healing. The calcineurin inhibitor tacrolimus is thought to have a relatively low complication rate, but preclinical research has yielded contradictory data, prompting the current comprehensive study. METHODS: Three groups of 33 male Wistar rats received a daily subcutaneous dose of 0,5, 2 or 5 mg/kg tacrolimus. A control group received saline. On day 0 a resection of 1 cm ileum and 1 cm colon was performed, and end-to-end anastomoses were constructed. Ten rats of each group were killed on day 3 and day 5 and the remaining animals on day 7. Both anastomoses and the wound in the abdominal wall were analyzed. Wound strength was the primary outcome parameter. RESULTS: Mean strength of the abdominal wall increased significantly over time in all groups (p

Background and purpose : Preoperative irradiation with direct postoperative chemotherapy could benefit patients undergoing surgery for colorectal cancer. This study was designed to examine, in an experimental model, if such treatment is feasible without detrimental effects on early anastomotic healing. Material and methods : A colonic segment was irradiated (25 Gy) in 3 groups ( n = 10 each) of male Wistar rats. After 5 days, a colonic resection was performed with anastomotic construction; only the distal limb consisted of irradiated bowel. Postoperatively, animals received daily intraperitoneal 5-fluorouracil (5-FU, group I/CH: 17.5 mg/kg; group I/CL: 12.5 mg/kg) or saline (group I). Three additional groups were treated similarly, but with sham-irradiation: CH, CL, and C, respectively. All rats were killed 7 days postoperatively. Parameters measured were: weight, serum albumin and protein, and anastomotic bursting pressure, breaking strength and hydroxyproline content. Results : Body weight was diminished significantly in rats receiving chemotherapy. Serum albumin and protein was significantly lower in irradiated groups. At sacrifice, 40% of I/CH rats had functional rectal stenosis. The average bursting pressure ( P = 0.0005) and the average breaking strength ( P = 0.012) were only reduced significantly in the CH group. The anastomotic hydroxyproline content was significantly higher in the I/CH and I/CL groups vs. the control group. Conclusion : High-dose direct postoperative 5-FU leads to reduced anastomotic strength. Although the combination of preoperative irradiation (25 Gy) and direct postoperative high-dose 5-FU does not reduce early anastomotic strength, some stenosis may occur. The combination of preoperative irradiation and low-dose 5-FU has no such effect.

During the treatment of colorectal liver metastases, evaluation of treatment efficacy is of the utmost importance for decision making. The aim of the present study was to explore the ability of preclinical imaging modalities to detect experimental liver metastases. Nine male Wag/Rij rats underwent a laparotomy with intraportal injection of CC531 tumor cells. On days 7, 10, and 14 after tumor induction, sequential positron emission tomography (PET), computed tomography (CT), and magnetic resonance imaging (MRI) scans were acquired of each rat. At each time point, three rats were euthanized and the metastases in the liver were documented histologically. Topographically, the liver was divided into eight segments and the image findings were compared on a segment-by-segment basis with the histopathologic findings. Sixty-four liver segments were analyzed, 20 of which contained tumor deposits. The overall sensitivity of PET, CT, and MRI was 30%, 25%, and 20%, respectively. For the detection of tumors with a histologic diameter exceeding 1 mm (n = 8), the sensitivity of PET, CT, and MRI was 63%, 38%, and 38%, respectively. The overall specificity of PET, CT, and MRI was 98%, 100%, and 93%, respectively. This study showed encouraging detectability and sensitivity for preclinical imaging of small liver tumors and provides valuable information on the imaging techniques for designing future protocols.

Item does not contain fulltext BACKGROUND: Paracetamol is a cornerstone for perioperative pain relief. Its mechanism of action may include a local anti-inflammatory effect with inhibition of cyclooxygenase isoenzymes. The scarce literature available on its effects on wound healing consists of preclinical studies into the effect of paracetamol on healing of the musculoskeletal system. Although the drug is used abundantly for pain relief after surgery of the gastrointestinal tract, there are no published data on the influence of paracetamol on anastomotic and abdominal healing. This also holds for the crucial, early inflammatory phase of repair. The recovery of wound strength could therefore conceivably be affected by paracetamol. METHODS: In 78 male Wistar rats, we constructed an anastomosis in colon and ileum. The rats received either low- or high-dose (50 or 200 mg/kg/d, divided over 2 doses) paracetamol or vehicle (controls) until they were killed on day 3 or 7 after surgery (n = 13 each). In anastomoses, the main outcome variables were 2 independent measures for wound strength, bursting pressure, and breaking strength, the latter being the primary outcome variable. In addition, collagen levels were measured and histology was performed. In fascia, breaking strength was analyzed. RESULTS: No significant differences were found between control and paracetamol-treated groups at any time point for any of the variables. Wound strength increased significantly from day 3 to day 7 in all groups. In the colon anastomosis, the breaking strength increased from 130 +/- 9 g (mean +/- SEM) at day 3 to 232 +/- 17 g at day 7 in the control group, from 144 +/- 10 to 224 +/- 9 g in the low-dose group, and from 130 +/- 12 to 263 +/- 28 g in the high-dose group. The lower limit for the 95% confidence interval was -11 for the difference between control and low-dose groups at day 3 and -25 for the difference between control and high-dose groups. No differences in collagen levels were found between the high-dose and control groups. Histology did not indicate the presence of gross differences between groups. CONCLUSIONS: Perioperative use of paracetamol in a rat model of intestinal surgery does not significantly impede wound repair in the early postoperative period.

Perioperative intraperitoneal chemotherapy is used as an adjunct to cytoreductive surgery (CS) for peritoneal carcinomatosis (PC) in order to prolong survival. Worldwide, hyperthermic intraperitoneal chemotherapy (HIPEC), early postoperative intraperitoneal chemotherapy (EPIC), and combinations of the two are used. It remains unclear which regimen is most beneficial. The rat colon carcinoma cell line CC-531 was injected into the peritoneal cavity of 80 WAG/Rij rats to induce PC. Animals were randomized into four treatment groups (n = 20): CS only, CS followed by HIPEC (mitomycin 35 mg/m2 at 41.5°C), CS followed by EPIC during 5 days (i.p. injection of mitomycin on day 1 and 5-fluorouracil on days 2–5), and CS followed by HIPEC plus EPIC. Primary outcome was survival. In rats treated with CS only, median survival was 53 days (95% confidence interval (CI) 49–57 days). In rats treated with CS followed by HIPEC, survival was significantly (P = 0.001) increased (median survival 94 days, 95% CI 51–137 days). In the group treated with EPIC after CS, 12 out of 20 rats were still alive at the end of the experiment (P

Contains fulltext : 96614.pdf (Publisher’s version ) (Closed access) OBJECTIVE: The aim of this study was to test the hypothesis that adjuvant radioimmunotherapy (RIT) prevents recurrent liver metastases and/or results in improved survival after tumorectomy in an experimental model. BACKGROUND: Although partial hepatectomy can improve 5-year survival of patients with colorectal liver metastases up to 58%, recurrent tumor growth in the liver occurs frequently. Radioimmunotherapy using radiolabeled monoclonal antibodies directed against tumor-associated antigens is considered most suited for treating minimal residual disease and could therefore serve as an adjuvant after surgery. METHODS: Liver metastases were induced in male Wag/Rij rats by a mini-laparotomy with intrahepatic injection of 0.3 x 106 CC531 tumor cells. The biodistribution of the radiolabeled monoclonal antibody MG1, directed against a 80-kDa cell surface antigen on CC531 tumors, in this model was determined at 1, 3, and 7 days after intravenous administration. The therapeutic efficacy of 177Lu-MG1 was compared with that of a sham antibody (UPC10), labeled with the same activity dose of Lu-177, and saline only. Radioimmunotherapy was administered either at the day of the tumorectomy (day 14 after tumor cell inoculation) or 7 days later. Primary endpoint was survival. RESULTS: Radiolabeled MG1 preferentially accumulated in tumor lesions in the liver reaching a maximum 3 days postinjection (8.7 +/- 0.6% injected dose per gram). Both the administration of 177Lu-MG1 and 177Lu-UPC10 resulted in a transient decrease in body weight. No other signs of clinical discomfort were registered. The survival curves of the group that received 177Lu-UPC10 and the group that received saline only did not differ (P=0.886). Administration of RIT immediately after surgery improved survival compared to administration of the control antibody (hazard ratio [HR], 1.54; P = 0.051), which was even more pronounced when survival was adjusted for the weight of the resected tumor (HR, 1.71; P = 0.027). A therapeutic efficacy of delayed treatment seemed likely (HR, 2.34; P = 0.055). Survival after early administration did not differ from delayed administration (HR, 1.16; P = 0.763). CONCLUSION: This study provides proof of principle that RIT can be an effective adjuvant treatment modality after surgical treatment of colorectal liver metastases.

Item does not contain fulltext OBJECTIVE: Hyperthermic intraperitoneal chemotherapy (HIPEC) with mitomycin C can improve survival if used as an adjunct to cytoreductive surgery (CS) for treatment of peritoneal carcinomatosis (PC). It remains unclear if both hyperthermia and chemotherapy are essential for the reported survival benefit. METHODS: Eighty WAG/Rij rats were inoculated intraperitoneally with the rat colon carcinoma cell line CC-531. Animals were randomly assigned to 1 of the 4 treatment groups (n = 20): CS only, CS followed by HIPEC (mitomycin 35 mg/m(2) at 41 degrees C), CS followed by intraperitoneal mitomycin perfusion at 37 degrees C, CS followed by intraperitoneal saline perfusion at 41 degrees C. Survival was the primary outcome with a maximum follow up of 126 days. RESULTS: Median survival was 62 days in rats treated with CS only and 57 days in rats treated with CS followed by hyperthermic saline perfusion. Rats receiving HIPEC had a median survival of 121 days (P = 0.022 when compared with CS only). In the group treated with chemotherapy at 37 degrees C, 13 of 20 animals were still alive at the end of the experiment so median survival was not reached. (CS vs. IPEC: P = 0.002, hazard ratio 0.36, 95% CI 0.19-0.69) Rats treated with hyperthermic saline perfusion did not have an increased survival as compared with CS only. CONCLUSIONS: The effectiveness of intraoperative intraperitoneal perfusion after CS is highly dependent on the presence of chemotherapeutic agents in the perfusate but not on hyperthermia. The need to include hyperthermia in the adjuvant intraoperative treatment after CS for PC should be further investigated.

The use of mammalian target of rapamycin inhibitors coincides with an increased incidence of surgical complications. In previous experiments, serious negative effects of postoperative everolimus on anastomotic strength were found. This study aims to investigate if delayed drug administration can prevent loss of wound strength. Ten groups of Wistar rats each received daily oral doses of 1.0 or 2.0 mg/kg everolimus, starting the day of anastomotic construction in both ileum and colon, or 1, 2, 3, or 4 days later. The 11th group received saline. Seven days later, wound strength in anastomoses and in the abdominal wall and wound hydroxyproline levels were measured. Mean wound strength was significantly and dose-dependently reduced if everolimus was started on the day of operation. In ileum and colon, strength was not affected if drug administration was delayed until the third or second day, respectively. In abdominal fascia, this was the case only if everolimus was withheld until day 4. In general, changes in wound hydroxyproline content showed similarities to changes in wound strength. Thus, delaying administration of everolimus for 2-4 days after operation can prevent a serious loss of wound strength, both in the intestine and in the abdominal fascia.

Background Radioimmunotherapy (RIT) has been shown to reduce the incidence of local recurrence of colorectal cancer in an experimental model. The aim of the present study was to investigate the survival benefit of RIT compared with chemotherapy. Methods An anastomosis was constructed in male Wag/Rij rats after intraluminal injection of CC531 tumour cells. The therapeutic efficacy of 177Lu-labelled MG1 (single intravenous dose of 300 MBq/kg, n = 20) was compared with that of 5-fluorouracil-based chemotherapy (6 weekly cycles administered intraperitoneally, n = 20) and no treatment (n = 20). The primary endpoint was survival. Toxicity was monitored by bodyweight measurement. Results Both chemotherapy and RIT affected bodyweight, but the weight of animals in the RIT group remained significantly higher than in the chemotherapy group (median slope of bodyweight plot 0·48 versus 0·30 g/day; P < 0·001). Kaplan–Meier analysis showed that overall survival in the RIT and chemotherapy groups was significantly better than that in the control group (50 and 46 per cent versus 25 per cent respectively after 170 days; P = 0·024 and P = 0·029). Survival after treatment with RIT did not differ from that after chemotherapy (P = 0·911). Conclusion RIT is as effective as chemotherapy in experimental colorectal cancer.

Contains fulltext : 89759.pdf (Publisher’s version ) (Open Access) The introduction of mTOR-inhibitors in transplantation surgery has been associated with an increase in wound complications. We have previously reported a massive negative effect of everolimus on anastomotic strength in rat intestine at 7 days postoperatively. Because it is clinically important to know if this effect persists and occurs generally, repair in both intestine and abdominal wall has been investigated over a period of 4 weeks. Wistar rats received a daily dose of 1 or 2 mg/kg everolimus orally, from the operation day onwards. Controls received saline. In each rat a resection of ileum and colon was performed, and end-to-end anastomoses were constructed. On day 7, 14, and 28 the animals were killed and anastomoses and abdominal wall wounds were analyzed, wound strength being the primary parameter. Breaking strength of ileum, colon, and fascia was consistently and significantly reduced in the experimental groups at all time points. Anastomotic bursting pressures followed the same pattern. Loss of strength was accompanied by a decrease in hydroxyproline content after 7 days. Thus, the negative effect of everolimus on wound repair persists for at least 4 weeks after operation in this rodent model. This protracted effect may have clinical consequences and cause surgical morbidity.

ObjectiveDespite the efficacy of collagen in femoral artery pseudoaneurysm treatment, as reported in one patient study, its use has not yet gained wide acceptance in clinical practice. In this particular study, the collagen was not described in detail. To further investigate the potential of collagen preparations, we prepared and characterized highly purified injectable fibrillar type I collagen and evaluated its use for femoral artery pseudoaneurysm (PSA) treatment in vivo using a pig model.MethodsPurified fibrillar type I collagen was characterized using electron microscopy. The effect of three different sterilization procedures, ie, hydrogen peroxide gas plasma (H2O2), ethylene oxide gas (EtO), and gamma irradiation, was studied on both SDS-PAGE and platelet aggregation. Different collagen injectables were prepared (3%, 4%, and 5%) and tested using an injection force test applying a 21-gauge needle. To evaluate the network characteristics of the injectable collagen, the collagen was suspended in phosphate buffered saline (PBS) at 37°C and studied both macroscopically and electron microscopically. To determine whether the collagen induced hemostasis in vivo, a pig PSA model was used applying a 4% EtO sterilized collagen injectable, and evaluation by angiography and routine histology.ResultsElectron microscopy of the purified type I collagen revealed intact fibrils with a distinct striated pattern and a length

Contains fulltext : 88102.pdf (Publisher’s version ) (Closed access) PURPOSE: To prepare a porcine model for femoral artery pseudoaneurysm via a one-step surgical procedure without the need for microsurgery. MATERIALS AND METHODS: This pseudoaneurysm model involves the preparation of an arteriovenous shunt between the femoral artery and femoral vein in which approximately 2 cm of the vein is segmented by proximal and distal closure with the use of ligatures. The femoral pseudoaneurysm models were evaluated by angiography, Doppler auscultation, and histologic examination. RESULTS: In seven of eight pigs, angiography and Doppler auscultation showed that the pseudoaneurysm models were open and that there was communication between the pseudoaneurysm model and the femoral artery. The mean length (+/-SD) of the pseudoaneurysm model was 1.9 cm +/- 0.3 (n= 7), with a neck region of 4 mm. Histologic analysis confirmed that pseudoaneurysm models were open and no thrombi were observed. CONCLUSIONS: The principal advantages of this model are the location of the pseudoaneurysm model, the short period of clamping, and the controllable size. The pig pseudoaneurysm model is straightforward and reproducible, and may serve as a useful tool in the evaluation of interventional strategies for treatment of pseudoaneurysms. 01 juli 2010

Background The combination of cytoreductive surgery (CS) and hyperthermic intraperitoneal chemotherapy (HIPEC) is the treatment of choice for selected patients with peritoneal carcinomatosis (PC) of colorectal origin. However, it remains to be proven whether the addition of HIPEC to CS is essential for the reported survival benefit. Methods Sixty WAG/Rij rats were inoculated intraperitoneally with the rat colonic carcinoma cell line CC-531. Animals were randomized into three treatment groups: CS alone, CS followed by HIPEC (mitomycin 15 mg/m2) and CS followed by HIPEC (mitomycin 35 mg/m2). Survival was the primary outcome parameter. Results The median survival of rats treated with CS alone was 43 days. Rats receiving HIPEC 15 mg/m2 and HIPEC 35 mg/m2 both had a significantly longer median survival of 75 days (P = 0·003) and 97 days (P < 0·001) respectively. Rats receiving HIPEC showed a significantly lower tumour load at autopsy compared with rats treated with CS alone. Conclusion A combination of CS and HIPEC results in longer survival than CS alone in rats with PC of colorectal origin.

Blood transfusions are reported to impair the cell-mediated immune response. Because both T lymphocyte and macrophage function are important for wound repair, the authors investigated the effect of blood transfusions on anastomotic repair. Lewis rats underwent resection of both ileum and colon, followed by the construction of either an everted or an inverted end-to-end anastomosis. Immediately after operation, they received either 3 mL saline intravenously, or 3 mL heparinized blood from Lewis or Brown Norway donors. The animals were killed 3 or 7 days after operation, and anastomotic strength was assessed by measuring the bursting pressure. Anastomotic abscesses and generalized peritonitis were not found in the control group. Blood transfusions, particularly allogeneic, significantly increased the incidence of these septic complications. Three days after operation, anastomotic strength was significantly reduced in both Lewis and Brown Norway transfused groups. For instance, average bursting pressures (+/- standard deviation [SD]) of inverted ileal anastomoses were 79 +/- 13 mmHg in the control group and 46 +/- 14 and 21 +/- 12 mmHg in the Lewis and Brown Norway transfused groups, respectively. Seven days after operation, the rupture site was found significantly more often within the anastomotic line in the animals that had received blood transfusions. The authors conclude that blood transfusions impair the healing of experimental intestinal anastomoses and increase susceptibility to intra-abdominal sepsis.

Contains fulltext : 80371.pdf (Publisher’s version ) (Open Access) In radioimmunotherapy (RIT), hematologic toxicity is the dose-limiting toxicity due to the long circulatory half-life of the antibody. Although intraperitoneal (i.p.) RIT results in high uptake of i.p. growing tumors, the radiolabeled antibody enters the circulation, resulting in bone marrow toxicity. Carbohydrate modification of antibodies could induce accelerated clearance of the antibody via the hepatic asialoglycoprotein receptor, thereby reducing exposure to normal tissues. In this study, we investigated whether galactosylation of an antibody in a model of peritoneal carcinomatosis (PC) of colonic origin could be used to improve targeting of i.p. growing tumors. Therefore, the biodistribution of the galactosylated and nongalactosylated anti-CC531 antibody, MG1, after i.p. injection was determined in a model of peritoneal carcinomatosis of CC-531 colon tumors in Wag/Rij rats. Uptake of the radiolabeled antibodies in the tumor and relevant organs was determined at 2, 4, 24, and 48 hours after injection. Galactosylation of the antibody did not affect the binding affinity of MG1. Remarkably, the uptake of Gal-MG1 in tumors was higher than that of MG1 at 2 and 4 hours after injection. After 24 and 48 hours, uptake of Gal-MG1 in tumor tissue was lower than that of MG1. Gal-MG1 cleared from the blood within hours after administration. At 2-24 hours after administration, tumor-to-blood ratios obtained with Gal-MG1 were significantly higher than those obtained with unmodified MG1. Antibody galactosylation resulted in improved tumor-non-tumor ratios after i.p. injection in a model of PC. This could improve the efficiency of RIT, especially in combination with short-lived nonresidualizing radionuclides.

Contains fulltext : 80885.pdf (Publisher’s version ) (Closed access) INTRODUCTION: During bowel surgery, perioperative blood loss and hypotension can lead to transient intestinal ischemia. Recent preclinical studies reveal that the strength of intestinal anastomoses can be compromised after reperfusion. So far, this phenomenon has not been investigated in the very first days of healing when wound strength is lowest. MATERIAL AND METHOD: Ischemia was induced in rats by clamping both the superior mesenteric artery and ileal branches for 30 min. Immediately after declamping, anastomoses were constructed in both terminal ileum and descending colon. The same was done in control groups after sham-ischemia. Anastomotic bursting pressure and breaking strength were measured immediately after operation (day 0) and after 1, 2, or 3 days. Anastomotic hydroxyproline content, gelatinase activity, and histology were analyzed. RESULTS AND DISCUSSION: In ileal anastomoses, at day 1, both the breaking strength and bursting pressure were significantly (p < 0.05) lower in the ischemic group, while at day 2, this was the case for the bursting pressure only. In the colon, the bursting pressure in the ischemic group was lower at day 1. Anastomotic hydroxyproline content remained unchanged. Increased presence of the various gelatinase activities was found in ileum only at day 0 and in colon at days 1 and 2. Histological mucosal damage was found in ischemia-reperfusion groups. CONCLUSION: Transient mesenteric ischemia can negatively affect anastomotic strength during the very first days of healing, even if the tissue used for anastomotic construction looks vital.

BackgroundRadioimmunotherapy (RIT) is suitable for the treatment of microscopic residual disease and might therefore have an adjuvant role after colonic cancer surgery.MethodsAn anastomosis was constructed in male Wag/Rij rats after intraluminal injection of 2 × 106 CC531 tumour cells. The biodistribution of 111In-labelled MG1 monoclonal antibody was assessed after intraperitoneal administration. The therapeutic efficacy of 177Lu-labelled MG1 (74 MBq per rat), administered on the day of surgery (D0, n = 13) or 5 days later (D5, n = 13), was compared with that of carrier only (n = 13). The primary endpoint was perianastomotic tumour growth 28 days after surgery.Results111In-labelled MG1 preferentially accumulated in perianastomotic CC531 tumours. RIT resulted in a transient reduction in bodyweight in both treatment groups compared with controls, but there were no other signs of clinical discomfort. No macroscopic or microscopic perianastomotic tumour growth was found in eight of 11 animals in the D0 group and 11 of 13 in the D5 group, whereas 11 of 13 controls had macroscopic tumour (P = 0·011 and P = 0·001 respectively).ConclusionThis study suggests that RIT may be an effective adjuvant treatment for preventing local recurrence after resection of colonic cancer.

Contains fulltext : 80074.pdf (Publisher’s version ) (Closed access) Liver metastases of colorectal carcinoma occur in about 50-60% of patients. To improve survival of these patients, there is an urgent need for new treatment strategies. For this purpose, the availability of a preclinical model to develop and test such treatments is mandatory. An ideal animal model for studying liver metastases of colorectal origin should mimic all aspects of the metastatic development in humans and be practical, predictable, and optimal in terms of ethical considerations. Thus far, no model has been developed which satisfies all these conditions. As a consequence, choosing an animal model for the study of liver metastases requires compromises and choices about the necessary characteristics that depend on the purpose of the intended experiments. This overview addresses the advantages and disadvantages of different animal models used for research on experimental liver metastases of colorectal origin. Based on data available in literature, we conclude that heterotopic injection of undifferentiated syngeneic tumor cells in immunocompetent rodents covers most of the desired characteristics. Both subcapsular as well as intraportal injection will yield suitable models and the eventual choice will depend on the aim of the study.

Contains fulltext : 69926.pdf (Publisher’s version ) (Open Access) BACKGROUND AND OBJECTIVE: Cytoreductive surgery (CS) and heated intraperitoneal chemotherapy (HIPEC) are standard treatment for peritoneal carcinomatosis (PC) of colorectal cancer. Previously, we demonstrated that preclinical radioimmunotherapy (RIT) adjuvant to surgery in PC is a good alternative for HIPEC. Now we aimed to improve the effectiveness of RIT by combining it with whole-body hyperthermia (WBH) or fibrinolytic therapy. METHODS: Rats were inoculated intraperitoneally with colon carcinoma cells. Animals underwent CS, CS + WBH (40 degrees C, 3 hours), CS + RIT (74 MBq 177Lu-labeled MG1), or CS + WBH + RIT. In the second experiment, rats underwent CS, CS + RIT, CS + recombinant tissue plasminogen activator (rtPA, twice daily, 3 days), or CS + RIT + rtPA. RESULTS: Median survival after CS and CS + WBH was 34 and 37 days. Median survival after CS + RIT or CS + RIT + WBH was 63 and 86 days (p < 0.0003, p < 0.0006 compared to CS + WBH). Median survival after CS and CS + rtPA was 50 and 42 days (p = 0.1). Median survival was 106 days after CS + RIT and 103 days after CS + RIT + rtPA (p < 0.0001 compared to CS + rtPA). No difference was found between CS + RIT and CS + RIT + rtPA (p = 0.83). CONCLUSIONS: The application of WBH or rtPA in combination with adjuvant RIT after CS for the treatment of PC of colonic was feasible but did not significantly potentiate the efficacy of RIT.

Contains fulltext : 51827.pdf (Publisher’s version ) (Closed access) INTRODUCTION: Transient intestinal ischemia can reduce anastomotic strength, which poses an increased risk of complications. The objective of this study is to establish if a prolonged interval between profound ischemia and construction of an anastomosis affects anastomotic strength. METHODS: Male Wistar rats were used: in experimental groups, profound mesenteric ischemia was induced by clamping both superior mesenteric artery and more distal arteries in the ileal mesentery. Resection and anastomosis in ileum and colon were performed immediately (IR0) or 24 h after releasing the clamps (IR24). In controls (C0 and C24), arteries were not clamped. After 5 days, anastomotic bursting pressure (BP), breaking strength (BS), and hydroxyproline were measured, and histological analysis was performed. RESULTS: Mortality and anastomotic dehiscence rates were significantly higher in IR0 compared to C0. In ileum, the BS was 34% lower (p