Experimental study of diclofenac and its biliary metabolites on anastomotic healing.

BACKGROUND: Diclofenac increases the risk of anastomotic leakage, but the underlying mechanism is unknown. As diclofenac is excreted largely as biliary metabolites, the aim of this study was to determine the effect of these metabolites on intestinal anastomoses. METHODS: This was a randomized controlled blinded experiment using 210 male Wistar rats to assess the effect of 'diclofenac bile' on the anastomotic complication score, leak rate and anastomotic strength following oral and parenteral administration of diclofenac. Bile duct and duodenal catheterization techniques were used for diversion and replacement of bile, and biliary diclofenac metabolites were determined. RESULTS: Replacement of control bile with diclofenac bile resulted in higher anastomotic complication scores (P = 0·006) and leakage in five of 18 animals, compared with one of 18 controls (P = 0·089). In turn, following oral diclofenac administration, replacement of diclofenac bile with control bile reduced anastomotic complications (P = 0·016). The leak rate was seven of 15 versus 13 of 17 without replacement (P = 0·127). After intramuscular administration of diclofenac, the reduction in anastomotic complications was not significant when bile was replaced with control bile (P = 0·283), but it was significant when bile was drained without replacement (P = 0·025). Diclofenac metabolites in bile peaked within 2 h after administration. Administration of diclofenac bile resulted in nearly undetectable plasma levels of diclofenac (mean(s.d.) 0·01(0·01) µg/ml) after 120 min. Following oral diclofenac, bile replacement with control bile did not affect the plasma concentration of diclofenac (0·12(0·08) µg/ml versus 0·10(0·05) µg/ml with diclofenac bile; P = 0·869). CONCLUSION: Altered bile composition as a result of diclofenac administration increases the ileal anastomotic complication rate in rats.

Bioinspired coupled helical coils for soft tissue engineering of tubular structures - Improved mechanical behavior of tubular collagen type I templates.

The design of constructs for tubular tissue engineering is challenging. Most biomaterials need to be reinforced with supporting structures such as knittings, meshes or electrospun material to comply with the mechanical demands of native tissues. In this study, coupled helical coils (CHCs) were manufactured to mimic collagen fiber orientation as found in nature. Monofilaments of different commercially available biodegradable polymers were wound and subsequently fused, resulting in right-handed and left-handed polymer helices fused together in joints where the filaments cross. CHCs of different polymer composition were tested to determine the tensile strength, strain recovery, hysteresis, compressive strength and degradation of CHCs of different composition. Subsequently, seamless and stable hybrid constructs consisting of PDSII® USP 2-0 CHCs embedded in porous collagen type I were produced. Compared to collagen alone, this hybrid showed superior strain recovery (93.5±0.9% vs 71.1±12.6% in longitudinal direction; 87.1±6.6% vs 57.2±4.6% in circumferential direction) and hysteresis (18.9±2.7% vs 51.1±12.0% in longitudinal direction; 11.5±4.6% vs 46.3±6.3% in circumferential direction). Furthermore, this hybrid construct showed an improved Young's modulus in both longitudinal (0.5±0.1MPavs 0.2±0.1MPa; 2.5-fold) and circumferential (1.65±0.07MPavs (2.9±0.3)×10-2MPa; 57-fold) direction, respectively, compared to templates created from collagen alone. Moreover, hybrid template characteristics could be modified by changing the CHC composition and CHCs were produced showing a mechanical behavior similar to the native ureter. CHC-enforced templates, which are easily tunable to meet different demands may be promising for tubular tissue engineering. STATEMENT OF SIGNIFICANCE: Most tubular constructs lack sufficient strength and tunability to comply with the mechanical demands of native tissues. Therefore, we embedded coupled helical coils (CHCs) produced from biodegradable polymers - to mimic collagen fiber orientation as found in nature - in collagen type I sponges. We show that the mechanical behavior of CHCs is very similar to native tissue and strengths structurally weak tubular constructs. The production procedure is relatively easy, reproducible and mechanical features can be controlled to meet different mechanical demands. This is promising in template manufacture, hence offering new opportunities in tissue engineering of tubular organs and preventing graft failure.

Prevention of postsurgical adhesions using an ultrapure alginate-based gel.

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.

Diclofenac causes more leakage than naproxen in anastomoses in the small intestine of the rat.

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.

Perioperative pain relief by a COX-2 inhibitor affects ileal repair and provides a model for anastomotic leakage in the intestine.

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.

Intraoperative hyperthermic intraperitoneal chemotherapy after cytoreductive surgery for peritoneal carcinomatosis in an experimental model.

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/m(2) ) and CS followed by HIPEC (mitomycin 35 mg/m(2) ). Survival was the primary outcome parameter. RESULTS: The median survival of rats treated with CS alone was 43 days. Rats receiving HIPEC 15 mg/m(2) and HIPEC 35 mg/m(2) 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.

Early anastomotic repair in the rat intestine is affected by transient preoperative mesenteric ischemia.

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.

The effects of adjuvant experimental radioimmunotherapy and hyperthermic intraperitoneal chemotherapy on intestinal and abdominal healing after cytoreductive surgery for peritoneal carcinomatosis in the rat.

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.

Circulating gelatinases and tissue inhibitor of metalloproteinase-1 in colorectal cancer metastatic liver disease.

AIMS: The degradation of the extracellular matrix is intrinsic to the invasion and progression of cancer. Matrix metalloproteinase (MMP)-2 and -9 and their natural inhibitors are involved in this process. The study aims to investigate if plasma MMP-2, -9 and tissue inhibitor of metalloproteinase-1 (TIMP-1) can be useful markers in the diagnosis and prognosis of colorectal cancer (CRC) metastatic liver disease. METHODS: Fifty-seven patients undergoing liver metastasis operation were followed prospectively. ProMMP-2, -9 and TIMP-1 plasma levels were determined by zymography and ELISA, before and after the resection of liver metastases. Data were compared with those of healthy controls (n=51) and primary CRC patients (n=94). The diagnostic and prognostic potential was investigated with ROC-curves and Kaplan-Meier survival analysis. RESULTS: Plasma proMMP-2 levels were lower (P<0.001), and TIMP-1 levels higher (P<0.001) in CRC metastatic liver disease than in healthy controls. If compared to those in primary CRC patients, no differences were found. In ROC-curves, the area under the curve was 0.48 and 0.61 for proMMP-2 and -9, respectively. Plasma proMMP-2, -9 and TIMP-1 levels were unsuitable to predict survival. In both diagnostic and prognostic examinations, CEA proved to be a better marker. In the postoperative follow-up, protracted low levels of proMMP-2 seemed related to disease recurrence. CONCLUSION: The preoperative plasma proMMP-2, -9 and TIMP-1 levels have no potential value as diagnostic or prognostic markers in CRC liver metastatic disease.

Selective cyclo-oxygenase 2 inhibition affects ileal but not colonic anastomotic healing in the early postoperative period.

BACKGROUND: Selective cyclo-oxygenase 2 (COX-2) inhibitors are increasingly prescribed in the perioperative period. Recent recognition of a possible role for COX-2 in wound healing has raised concerns about the safety of their use in surgical practice. Therefore, the influence of celecoxib, a selective COX-2 inhibitor, on early anastomotic healing was investigated. METHODS: Celecoxib, in doses of 15, 50 or 200 mg per kg per day, was given daily from the day before operation onwards to male Wistar rats that received both ileal and colonic anastomoses. Anastomotic strength was assessed by measuring the breaking strength and bursting pressure on the third day after operation. A second group received a dose of 50 mg per kg per day and a colonic anastomosis only, and healing was assessed on the third and fifth day after surgery. RESULTS: Expression of COX-2 protein was upregulated in the anastomotic area. Administration of celecoxib, at all doses tested, resulted in a significantly higher ileal dehiscence rate than in control rats (P = 0.002). In contrast, colonic anastomoses healed normally within the same animals. The latter was confirmed in rats with colonic anastomoses only. CONCLUSION: In this model, administration of the COX-2 inhibitor celecoxib affected ileal but not colonic anastomotic healing in the early postoperative period.

Plasma gelatinase activity does not reflect disease activity after operation for colorectal cancer.

OBJECTIVE: To investigate if plasma matrix metalloproteinase (MMP)-2 or -9 are better markers for disease activity than carcinoembryonic antigen (CEA) in the postoperative follow-up of colorectal cancer patients. METHODS: A prospective study was performed including 61 patients operated for primary colorectal cancer. The follow-up was for at least 2 years and postoperative blood samples were obtained periodically with 3-month intervals. Plasma gelatinase activity was measured with quantitative gelatin zymography and serum CEA with a specific immunoassay. RESULTS: Zymographic analysis of plasma samples revealed the presence of the proforms, but not the active forms, of both MMP-2 and -9. Prior to the detection of recurrent disease or metastasis in potentially curatively operated colorectal cancer patients, the changes in proMMP-2, -9 and CEA blood levels were determined. ProMMP-2 and -9 plasma levels changed little in this period and changes between patients with and without disease relapse were not statistically significant. In contrast, patients with disease relapse showed a significant increase (p = 0.002) in CEA in the two consecutive serum samples prior to the detection of recurrent disease or metastasis. Similarly, prior to death due to colorectal cancer, proMMP-2 and -9 plasma levels showed no significant change, whereas CEA levels increased considerably and significantly (p < 0.001) when compared to changes found in survivors. CONCLUSION: Plasma proMMP-2 and -9 activities show no potential value as prognostic markers in the follow-up of colorectal cancer.

No detrimental effects of repeated laparotomies on early healing of experimental intestinal anastomoses.

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.

Increased expression of matrix metalloproteinases in the murine zymosan-induced multiple organ dysfunction syndrome.

Matrix metalloproteinases (MMPs) have been implicated as mediators of tissue damage in several inflammatory diseases. Since the multiple organ dysfunction syndrome (MODS) is thought to result from systemic inflammation, overactivation of MMPs could contribute to the organ damage observed. The expression and activity of several MMPs were studied in a murine model for MODS. Sixty mice were given an aseptic intraperitoneal injection of lipopolysaccharide, followed, after 6 days, by zymosan. At days 2, 5, 8, 12, and 16 after the injection of zymosan, the liver, lungs, spleen, and kidneys were collected from groups of mice for either RNA extraction, gelatinase zymography and collagenase (MMP-1 and -13) assays (six mice per time point), or immunohistochemistry (three mice per time point). A group of nine mice did not receive zymosan and acted as controls. The expression of MMP-2 mRNA in zymosan-treated mice was strongly up-regulated in liver tissue only. For MMP-9, this was the case in all organs examined. Quantitative gelatin zymography demonstrated the near complete absence of any gelatinase activity in tissues from control mice. However, in the liver, lungs, and especially the spleen of zymosan-treated animals, significantly increased activity of proform and active MMP-2 and -9 was observed with time. Overall, MMP-1 and -13 activities were very low in all samples from the liver and lungs. In the spleen, however, high levels of MMP-1 and -13 were observed in zymosan-treated animals. Immunohistochemical staining for MMP-2 was detected in the liver and spleen, but not in lung and kidney tissue of zymosan-treated animals. Staining for MMP-9 could be detected in liver, lung, and spleen tissues of zymosan-treated mice. For both MMPs, staining appeared to be limited to phagocytes. In conclusion, the data suggest a role for MMPs, especially MMP-9, in the pathogenesis of MODS.

Circulating matrix metalloproteinase-9 is transiently elevated after colorectal surgery.

BACKGROUND AND AIMS: Plasma levels of matrix metalloproteinases (MMPs) may yield important information in patients suffering from colorectal cancer but the effect of surgery, a common treatment modality in these patients, on circulating MMP levels is currently unknown. The aim of this study was to assess whether plasma MMP-2 and MMP-9 levels are affected by operative procedures. MATERIALS AND METHODS: In total 128 patients undergoing elective surgery for colorectal cancer (n = 66), liver metastases from colorectal origin (n = 50) and arthrosis of the hip (n = 12) were included in the study. Gelatinase activity was measured, using quantitative gelatin zymography, in plasma obtained before operation and 1 week, 1 month and 3 months postoperatively. RESULTS: One week after operation a significant increase in proMMP-9 activity was measured after colorectal surgery (260%, p = 0.0038), liver surgery (285%, p < 0.0001) and hip surgery (217%, p = 0.012) as compared with preoperative levels. After 1 month proMMP-9 activity had returned to preoperative levels. No effect on proMMP-2 activity was measured. CONCLUSION: Operative procedures have a profound but transient effect on plasma MMP-9 activity. If used to assess disease status, postoperative plasma MMP levels should be interpreted with caution.

Matrix metalloproteinase 2 and 9 activity in patients with colorectal cancer liver metastasis.

BACKGROUND: Matrix metalloproteinases (MMPs) have been reported to play an important role in tumour cell invasion and metastasis. The bioactivity of MMPs in liver metastasis from colorectal cancer was investigated and correlated with clinicopathological variables. METHOD: Thirty-two patients underwent resection of colorectal cancer liver metastases. Latent and active forms of MMP were measured in tissue extracts, by means of quantitative gelatin zymography and a fluorometric activity assay. RESULTS: Broad-spectrum MMP activity, and levels of both active and latent forms of MMP-2 and MMP-9, were higher in tissues containing metastatic tumour than in normal liver tissue. Median metastatic to normal tissue ratios were 15.0 and 17.6 for active and proMMP-2 respectively, and those for active and proMMP-9 were 6.2 and 2.9. The ratios of active to latent enzyme were higher in metastatic tissue than in normal tissue. Lowered MMP-2 activity was associated with large metastatic lesions and increased proMMP-9 levels with preoperative chemotherapy. Both MMP-2 and MMP-9 activity were linked unfavourably to early recurrent disease. CONCLUSION: These data suggest a role for MMPs in colorectal cancer liver metastasis, but indicate different roles for individual MMPs.

Colonic anastomotic strength and matrix metalloproteinase activity in an experimental model of bacterial peritonitis.

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.

The matrix metalloproteinase inhibitor BB-94 improves the strength of intestinal anastomoses in the rat.

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.

Tissue levels of active matrix metalloproteinase-2 and -9 in colorectal cancer.

The bioactivity of matrix metalloproteinases was studied in tissues from colorectal cancer patients by means of both quantitative gelatin zymography and a fluorometric activity assay. Next to paired samples of tumour tissue and distant normal mucosa (n=73), transitional tissue was analysed from a limited (n=33) number of patients. Broad-spectrum matrix metalloproteinase activity and both the active and latent forms of the gelatinases matrix metalloproteinase-2 and -9 were higher in tumour than in normal mucosa. The ratio's between active and latent forms of matrix metalloproteinase-2 and -9 were highest in tumour tissue and normal mucosa, respectively. Matrix metalloproteinase-2 levels, both active and latent forms, correlated inversely with stage of disease, the tumours without synchronous distant metastases containing significantly (P=0.005) more active matrix metalloproteinase-2 than the others. At much lower levels of activity, the same trend was observed in distant normal mucosa. The level of latent form of matrix metalloproteinase-9 in tumour depended on tumour location. Neither the active form of matrix metalloproteinase-9 nor broad-spectrum matrix metalloproteinase activity in tumour tissue did correlate with any of the clinicopathological parameters investigated. The results demonstrate explicit differences between the activity of matrix metalloproteinase-2 and -9, indicating different roles for both gelatinases in tumour progression. Such data are necessary in order to develop rational anti-cancer therapies based on inhibition of specific matrix metalloproteinases.