Evaluation of effects on the peritoneum after intraperitoneal α-radioimmunotherapy with (211)At

The introduction of the short-lived α-emitter (211)At to intraperitoneal radioimmunotherapy has raised the issue of the tolerance dose of the peritoneum. The short range of the α-particles (70 μm) and the short half-life (7.21 h) of the nuclide yield a dose distribution in which the peritoneum is highly irradiated compared with other normal tissues. To address this issue, mice were injected with (211)At-trastuzumab to irradiate the peritoneum to absorbed doses ranging between 0 and 50 Gy and followed for up to 34 weeks. The peritoneum-to-plasma clearance of a small tracer, (51)Cr-ethylenediamine tetraacetic acid, was measured for evaluation of the small solute transport capacity of the peritoneal membrane. The macroscopic status of the peritoneum and the mesenteric windows was documented when the mice were sacrificed. Biopsies of the peritoneum were taken for morphology and immunohistochemical staining against plasminogen activator inhibitor-1 and calprotectin. Peritoneum-to-plasma clearance measurements indicated a dose-dependent decrease in peritoneal transport capacity in irradiated mice. However, macroscopic and microscopic evaluations of the peritoneal membrane showed no difference between irradiated mice versus controls. The results imply that the peritoneal membrane tolerates absorbed doses as high as 30-50 Gy from α-particle irradiation with limited response.

Bowel obstruction after laparoscopic and open colon resection for cancer: results of 5 years of follow-up in a randomized trial

BACKGROUND

Postoperative bowel obstruction caused by intra-abdominal adhesions occurs after all types of abdominal surgery. It has been suggested that the laparoscopic technique should reduce the risk for adhesion formation and thus for postoperative bowel obstruction. This study was designed to compare the incidence of bowel obstruction in a randomized trial where laparoscopic and open resection for colon cancer was compared.

METHODS

A retrospective analysis was performed, collecting data of episodes of bowel obstruction with or without surgery. Only episodes treated in the hospital where the index surgery took place were included. Data for 786 patients were collected for the 5-year period after cancer surgery.

RESULTS

Baseline characteristics for the evaluated laparoscopic (n = 383) and open (n = 403) groups were comparable. The cumulative obstruction percentages at 5 years for the open and laparoscopic groups were 6.5 and 5.1% respectively and did not significantly differ from each other. Tumor stage seemed to influence the risk for bowel obstruction: 2.8% in stage I, 6.6% in stage II, and 7% in stage III, but the differences were not significant.

CONCLUSIONS

This analysis does not support the hypothesis that laparoscopy leads to fewer episodes of bowel obstruction compared with open surgery.

Preoperative radiotherapy and extracellular matrix remodeling in rectal mucosa and tumour matrix metalloproteinases and plasminogen components

BACKGROUND. Preoperative radiotherapy reduces recurrence but increases postoperative morbidity. The aim of this study was to explore the effect of radiotherapy in rectal mucosa and rectal tumour extracellular matrix (ECM) by studying enzymes and growth factors involved in ECM remodeling. MATERIALS AND METHODS. Twenty patients with short-term preoperative radiotherapy and 12 control patients without radiotherapy were studied. Biopsies from rectal mucosa and tumour were collected prior to radiotherapy and at surgery. Tissue MMP-1, -2, -9, TIMP-1, uPA, PAI-1, TGF-beta1 and calprotectin were determined by ELISA. Biopsies from irradiated and non-irradiated peritoneal areas were also analysed. RESULTS. Radiotherapy increased the tissue levels of MMP-2 and PAI-1 in both the rectal mucosa and tumours while calprotectin and uPA showed an increase only in the mucosa after irradiation. The increase of calprotectin was due to an influx of inflammatory cells as revealed by immunohistochemistry. Prior to irradiation, the tumour tissues had increased levels of MMP-1, -2, -9, total TGF-beta1, uPA, PAI-1 and calprotectin compared to mucosa, while TIMP-1 and the active TGF-beta1 fraction showed no statistical difference. CONCLUSIONS. This study indicates a radiation-induced effect on selected ECM remodeling proteases. This reaction may be responsible for early and late morbidity. Interference of this response might reduce these consequences.

Differential prognostic impact of uPA and PAI-1 in colon and rectal cancer

BACKGROUND AND OBJECTIVES

Degradation of extracellular matrix is important for tumour growth and invasion, which in part is regulated by the plasminogen activation system. The aim of the study was to evaluate the protein expression of urokinase plasminogen activator (uPA) and plasminogen-activating inhibitor-1 (PAI-1) in plasma, tumour-free mucosa and tumour tissue regarding their prognostic value in colon and rectal cancer.

METHODS

Patients (n = 221) undergoing surgery for colorectal cancer were prospectively included. Samples were assayed by ELISA technique.

RESULTS

PAI-1 in tumour tissue (p = 0.006), plasma (<0.0001) and uPA in tumour-free mucosa (p = 0.006) were associated with survival in rectal cancer in univariate analysis. An uPA expression level below 1.1 ng/mg (log rank test, p < 0.0001) in tumour-free mucosa was associated with poor survival in rectal cancer. This was true also for patients without disseminated disease (M(0), p = 0.02). PAI-1 in plasma correlated with metastatic disease (p < 0.0001). uPA and PAI-1 were not associated with survival in either tumour tissue, mucosa or plasma in patients with colon cancer.

CONCLUSIONS

uPA and PAI-1 have a differential prognostic impact in colon and rectal cancer. Preoperative mucosal uPA and plasma PAI-1 protein expression could possibly be used as prognostic factors in rectal cancer.

Progress of tissue injury in appendicitis involves the serine proteases uPA and PAI-1

OBJECTIVE

Serine proteases and the matrix metalloproteinases (MMPs) are key factors in the proteolytic cascade and participate in extracellular matrix (ECM) degradation. Fibrinolytic activators and inhibitors may have an effect on inflammatory cells, thereby modulating the inflammatory response. It is reasonable to assume that they may be implicated in the tissue injury in acute appendicitis that subsequently leads to appendix perforation. The purpose of this study was to investigate the expression and distribution of urokinase-type plasminogen activator (uPA) and plasminogen-activator inhibitor type 1 (PAI-1) in appendicitis.

MATERIAL AND METHODS

Expression of uPA and expression of PAI-1 were measured in tissue specimens from patients with appendicitis (n=30) and in control specimens (n=9), using the quantitative ELISA technique. Distribution of enzymes was studied with immunohistochemistry. The uPA and PAI-1 levels in the subgroups of appendicitis and controls were compared.

RESULTS

The overall expressions of uPA and PAI-1 were greater in appendicitis than in control specimens (p <0.001 and p<0.0001, respectively). Expressions of uPA and PAI-1 in phlegmonous (n=15), gangrenous (n=6) and perforated appendicitis (n=9) were all higher than those in controls (n=9), (p<0.01). Moreover, the PAI-1 level was elevated in perforated appendicitis compared with phlegmonous appendicitis (p<0.01). uPA staining was observed in connection with vascular endothelial cells and the serosa stained intensely in specimens from perforated appendicitis.

CONCLUSIONS

The expression of uPA and especially the over-expression of PAI-1 seem to correlate to the progression of local inflammatory response in acute appendicitis.

Increased TGF-beta 1 protein expression in patients with advanced colorectal cancer

INTRODUCTION

There is evidence that TGF-beta 1 plays a role as a tumor suppressor in early disease and has pro-oncogenic effects in advanced tumor stage. The aim of the study was to correlate TGF-beta 1 in plasma and tissue to clinical and pathological parameters in patients with various stages of disease progression.

METHODS

One hundred sixty-nine patients who underwent surgery for a colorectal carcinoma were prospectively included. Blood samples, tumor free mucosa and tumor biopsies were assayed.

RESULTS

TGF-beta 1 protein expression in tumors increased with increasing T-stage regardless of whether patients with metastatic disease were included or not (P = 0.0006). Patients with metastatic disease showed elevated TGF-beta 1 protein expression in both tumor tissue (P = 0.004) and plasma (P = 0.001) compared to those without metastatic disease. TGF-beta 1 protein expression was higher in the colon compared with the rectum in both tumor tissue and tumor-free bowel (P = 0.03), regardless of whether patients with metastatic disease were included or not. This difference was mainly attributable to a higher TGF-beta 1 protein expression in non-metastatic patients with lymph node positivity (P = 0.005).

CONCLUSIONS

Higher TGF-beta 1 protein expression is associated with increasing T-stage and metastatic disease, indicating that TGF-beta 1 is of importance in tumor progression. The localization of the tumor seems to influence the TGF-beta 1 protein expression in patients with tumor cell-positive lymph nodes.

A local imbalance between MMP and TIMP may have an implication on the severity and course of appendicitis

BACKGROUND

Matrix metalloproteinases (MMPs) and the tissue inhibitors of MMPs (TIMPs) have been demonstrated to be involved in inflammatory conditions in the intestine. The purpose of this study was to investigate whether the alterations of the MMP/TIMP balance might reflect the course of the inflammatory process in acute appendicitis and if the expression and localisation of MMPs and TIMP is variable in the various clinical manifestations of appendicitis.

MATERIALS AND METHODS

The study comprises 40 patients (26 men and 14 women) having emergency appendectomy and a control group constituting of 10 patients (5 men and 5 women) having a hemicolectomy for other reasons. MMP and TIMP expressions were assessed and compared in tissue specimens from phlegmonous (n = 15), gangrenous (n = 7), perforated appendicitis (n = 11) and controls with noninflamed appendices (n = 10) by means of enzyme-linked immunosorbent assay technique. Localisation of the enzymes was performed by immunohistochemistry.

RESULTS

MMP-1 was significantly higher in gangrenous and perforated appendicitis compared with phlegmonous appendicitis and controls (p < 0.05) while MMP-2 was significantly lower in gangrenous appendicitis compared with phlegmonous appendicitis and controls. MMP-2 was also lower in perforated appendicitis when compared with controls (p < 0.01). Elevated expression of MMP-9 was demonstrated in all groups of appendicitis compared with the controls (p < 0.001).

CONCLUSIONS

MMP-9 is the most abundantly expressed MMP of those investigated in inflamed appendix. We postulate that a local imbalance between MMP-9 and TIMP-1 may trigger a perforation. These results suggest that MMPs might be useful as biomarkers of appendices prone to perforation.

uPA and PAI-1 in rectal cancer--relationship to radiotherapy and clinical outcome

BACKGROUND

It is well known that the fibrinolytic system is of importance in inflammation, wound healing, and fibrosis development. However, it is also important in the process of tumor invasion and metastasis. We have investigated protein levels of urokinase plasminogen activator (uPA) and plasminogen activator inhibitor-1 (PAI-1) in rectal cancer and effects of radiotherapy, links to clinical outcome, and potential use as prognostic factors.

MATERIALS AND METHODS

Ninety-one patients with rectal cancer were studied. Blood samples and biopsies were taken during surgery and assayed with enzyme-linked immunosorbent assay for uPA and PAI-1, and patients were followed prospectively (0-96 mo).

RESULTS

Higher levels of uPA (P < 0.0001) and PAI-1 (P < 0.0001) were found in tumor compared with mucosa. Mucosa exposed to radiotherapy had higher levels of uPA (P < 0.0001) and of PAI-1 (P < 0.0001). Irradiated tumor tissue had higher levels of PAI-1 (P < 0.001). PAI-1 in tumor was correlated with T stage (P < 0.001) and N stage (P < 0.01). PAI-1 in plasma was higher in patients with synchronous distant metastases (P < 0.001). Cox regression was used to identify high levels of PAI-1 in tumor as an independent factor related to short disease-free survival (P < 0.01) and the ratio of uPA/PAI-1 to development of metastases (P < 0.01).

CONCLUSIONS

There is a relationship between PAI-1 in plasma and rectal cancer metastases. PAI-1 in tumor tissue is correlated to histopathological data and to outcome of rectal cancer. If these findings can be confirmed in larger trials, there will be a possibility to use PAI-1 as a prognostic factor.

Transforming growth factor beta-1 in rectal tumour, mucosa and plasma in relation to radiotherapy and clinical outcome in rectal cancer patients

BACKGROUND

Rectal cancer patients are treated with surgery and sometimes radiotherapy. Transforming growth factor-beta1 (TGF-beta1) acts both as an inhibitor of tumour growth and as a promoter of tumour progression. The aim of this study was to determine the levels of TGF-beta1 in tumour tissue, adjacent mucosa and plasma in rectal cancer patients and relate these to the effect of radiotherapy and clinical outcome.

MATERIALS AND METHODS

One hundred and ten patients scheduled for rectal cancer surgery were included, 49% received pre-operative radiotherapy three-field treatment 5 x 5 Gy. Blood samples and biopsies were taken during surgery and later assayed with enzyme-linked immunosorbent assay for total TGF-beta1 and active TGF-beta1. Patients were then followed for 3 years.

RESULTS

Total and active TGF-beta1 was higher in tumour tissue compared with rectal mucosa (p < 0.0001). Active TGF-beta1 in tumour tissue and rectal mucosa was lower in the irradiated group (p = 0.007; p < 0.0001). Total TGF-beta1 was higher in patients with metastases at primary diagnosis (p = 0.005) compared to patients without. In patients who later developed metastases, the levels of active TGF-beta1 in plasma were lower (p = 0.004). Local recurrence was associated with lower levels of total TGF-beta1 in the rectal mucosa (p = 0.038).

CONCLUSIONS

Higher levels of total TGF-beta1 in tumour tissue at surgery may be indicative of distant metastases, and low levels of active TGF-beta1 in plasma may indicate a risk of developing secondary metastases. Lower levels of total TGF-beta1 in rectal mucosa may influence risk of local recurrence. Measurement of TGF-beta1 in rectal cancer patients may be of clinical use in the future.

Matrix metalloproteinases in rectal mucosa, tumour and plasma: response after preoperative irradiation

BACKGROUND

In rectal cancer treatment, preoperative radiotherapy has led to reduction of local recurrence, but it is associated with morbidity and increased risk for secondary tumours. Matrix metalloproteinases (MMPs) are associated with tumour progression through tissue remodeling. The aim of this study was to investigate tissue remodeling after preoperative radiotherapy and to explore possible correlations with clinical outcome.

MATERIALS AND METHODS

Ninety-one patients scheduled for rectal cancer surgery were included; 49% received preoperative radiotherapy three-field treatment, 5 x 5 Gy. Blood samples and biopsies from tumour and adjacent mucosa were taken during surgery. Biopsies and plasma were assayed with ELISA for MMP-1, MMP-2 and MMP-9. Clinical outcome was reviewed focusing on infections, perineal healing, fistula formation, anastomotic dehiscence, small bowel obstruction, local recurrence and distant metastases.

RESULTS

Compared to non-irradiated mucosa, MMP-2 (p < 0.0001), MMP-1 (p = 0.03) and MMP-9 (p = 0.04) were significantly higher in irradiated normal mucosa. Tumour tissue had higher levels of MMP-2 if irradiated (p < 0.0001). A correlation between MMP-2 levels and wound infection (p = 0.02) as well as fistula formation (p = 0.04) was found. MMP-1 in mucosa (p = 0.02) and tumour (p = 0.04) were higher in patients developing distant metastases. Plasma levels were not influenced by irradiation, but MMP-2 was higher in patients who were later developing distant metastases (p = 0.007).

CONCLUSIONS

Extracellular matrix remodeling after radiotherapy seems to be correlated to postoperative morbidity; MMP-2 is associated with both wound infections and fistula formation. High levels of MMP-1 in tumour and mucosa as well as MMP-2 in plasma may be correlated to risk of developing distant metastases.

Increased concentration of tissue-degrading matrix metalloproteinases and their inhibitor in complicated diverticular disease

OBJECTIVE

Complicated diverticular disease is associated with extensive structural changes of the colonic wall. Turnover of extracellular matrix (ECM) plays a pivotal role in this process. Proteolytic enzymes, including matrix metalloproteinases (MMPs), are capable of degrading most components of ECM. Their activity is regulated by inhibitors, tissue inhibitors of metalloproteinases (TIMPs). Disturbances of the MMP-TIMP balance can cause tissue degradation or fibrosis. The aim of this study was to assess the concentration and distribution of MMPs and TIMPs in colonic biopsies.

MATERIAL AND METHODS

Twenty-seven patients who had undergone sigmoid colectomy were included in the study. Full-thickness biopsies from affected and non-affected parts of each resected specimen were collected. Expressions of the proteins MMP-1, -2, -3, -9, TIMP-1 and TIMP-2 were quantified by ELISA and localized by immunohistochemistry.

RESULTS

The concentrations of MMP-1, MMP-2 and TIMP-1 were significantly higher in affected tissue than concentrations in non-affected tissue (MMP-1 p=0.005, MMP-2 p=0.0003 and TIMP-1 p<0.0001). In affected segments in general, there was an increased expression in the entire bowel wall, predominantly for MMP-2, MMP-3 and TIMP-1.

CONCLUSIONS

Concentrations of MMP-1, MMP-2 and TIMP-1 were increased in intestinal segments affected by complicated diverticular disease and distributed throughout the entire bowel wall, which may explain the structural changes.

Increased plasma MMP-2 protein expression in lymph node-positive patients with colorectal cancer

BACKGROUND

Degradation of the extracellular matrix plays an important part during the invasion of cancer cells into the surrounding tissue. The matrix metalloproteinases (MMPs) have a central role in this process as demonstrated in different malignancies. The aim of this study was to investigate the presence of several MMPs from tumour, adjacent tumour-free colon segment and from plasma, in order to evaluate how these factors might be used as predictors in colorectal malignancy.

METHODS

Seventy-two patients who underwent surgery because of a colorectal carcinoma were included. Biopsies from the tumour, macroscopically tumour-free bowel and plasma samples were analysed with enzyme-linked immunosorbent assay tests (ELISAs) quantifying protein expression of several MMPs.

RESULTS

We found highly elevated concentrations of MMP-1, MMP-2, MMP-3 and MMP-9 protein expression in tumour tissue compared with tumour-free tissue (p<0.0001). Elevated MMP-1 tumour levels were found in patients with Dukes' C cancers (p=0.02). Lymph node status correlated with the expression of MMP-2 in plasma, which was significantly increased in patients with lymph node metastasis compared with those without (p=0.002). MMP-2 in plasma was higher in T3 and T2 tumours than in T4 tumours (p=0.0083).

CONCLUSION

The MMPs we investigated were strongly elevated in tumour tissue compared with tumour-free bowel wall. Our results indicate that MMP-2 in plasma may possibly be used as a predictor in colorectal malignancy. The use of MMP-2 as a predicting tool in combination with different imaging techniques may give important preoperative information in patients with colorectal cancer.

Antifibrinolytic proCPU is present in the peritoneal cavity during surgery

The fibrinolytic capacity of the peritoneum plays a pivotal role in peritoneal wound healing. During surgery the balance between fibrin deposition and degradation is tilted towards deposition, leading to the formation of adhesions. In blood, carboxypeptidase U (CPU) stabilizes clots by retarding fibrinolysis. The purpose of this study was to investigate whether the more stable zymogen, proCPU, is also present in the peritoneal cavity and, if so, to examine its origin. Levels of proCPU were measured in plasma and serosal peritoneal fluid collected during surgery. Peritoneal biopsies were stained for proCPU. Two-dimensional gel electrophoresis was performed to study the protein composition of the serosal fluid compared to plasma and Western blotting to identify differences in glycosylation of proCPU, indicating possible different cellular origin. Cultured human mesothelial cells were examined for proCPU production under normal conditions and conditions mimicking surgery. We found comparable and correlating levels of proCPU in serosal fluid and plasma. ProCPU was also found where fibrin covered the injured peritoneal surface. A protein composition very similar in serosal fluid and plasma was shown by two-dimensional gel electrophoresis, and the proCPU pattern did not indicate a different origin. No proCPU production was found in cultured mesothelial cells. This is the first study to report on the presence of proCPU in the peritoneal cavity, which seems to be the result of plasma oozing out during the inflammatory reaction to the surgical trauma. This is likely to be important for the balance between fibrin deposition and degradation and thereby in the formation of postoperative adhesions.

Examination gloves affect secretion of matrix metalloproteinases and their inhibitors from human abdominal skin fibroblasts

Overexpression of matrix metalloproteinases (MMPs) has been observed in chronic, compared to acute, wounds and altered levels might impair healing. During treatment of wounds, examination gloves are routinely used, and the wound environment thus gets exposed to gloves. The aim of this study was to characterize secretion of MMPs and tissue inhibitors of metalloproteinases (TIMPs) in cultured fibroblasts with or without exposure to gloves. Cultures were exposed to glove washings from powdered or powder-free latex examination gloves and compared to untreated controls. MMP-1, -2, -3, -9 and their inhibitors TIMP-1 and -2 were assayed in conditioned media. Cells exposed to gloves reduced their release of MMP-1, -2, and -3 with no differences between the manufacturers of the gloves. The inhibitor TIMP-1 was reduced to 10-15% of untreated control values (p < 0.001), being less affected by the powder-free than by the powdered glove (p < 0.05). MMP-9 and TIMP-2 were not significantly altered. We therefore conclude that secretion of MMPs and TIMPs from cultured fibroblasts were affected by glove washings. Powdered and powder-free gloves had similar effects, except for a less pronounced reduction of TIMP-1 production by the powder-free glove. Examination gloves might therefore affect wound healing, with the least pronounced effect observed using the powder-free glove.

Plasminogen activator/plasminogen activator inhibitor-1 and cytokine modulation by the PROACT System

OBJECTIVE

To examine the effects of the PROACT treatment on the fibrinolytic system and inflammatory cytokines in human peritoneum.

DESIGN

Controlled clinical study.

SETTING

University hospital.

PATIENT(S)

Nine subjects undergoing laparotomy had peritoneal samples taken at the incision.

INTERVENTION(S)

The PROACT applicator was inserted through the peritoneal incision, and treatment of peritoneum was performed twice. A peritoneal sample was taken from one treated area. At closure, the second treated sample and an additional control sample were taken. All four samples were snap frozen in liquid nitrogen. Samples were homogenized and protein content extracted.

MAIN OUTCOME MEASURE(S)

Concentrations of total and active transforming growth factor-beta 1 (TGF-beta1), tumor necrosis factor-alpha (TNF-alpha), tissue-type plasminogen activator (t-PA), urokinase plasminogen activator (uPA), and plasminogen activator inhibitor 1 (PAI-1) were obtained.

RESULT(S)

Total TGF-beta1 at opening was 30% less in treated samples. At closure, active TGF-beta1 increased significantly (163%) in control samples and not in treated samples. Tumor necrosis factor alpha was detectable only in control samples at closure. During surgery, tPA levels showed a marked decrease in control samples vs. a small increase in treated samples. Levels of uPA increased significantly only in the control samples. In control samples, tPA/PAI-1 ratio was two thirds of treated sample ratio.

CONCLUSION(S)

Heating of the peritoneum with the PROACT System modulates the biologic tissue response to induce effects that would be consistent with inhibition of postoperative adhesion development.

Overproduction of transforming growth factor-beta1 (TGF-beta1) is associated with adhesion formation and peritoneal fibrinolytic impairment

BACKGROUND

Reduction in peritoneal fibrinolytic capacity and increased transforming growth factor-beta1 (TGF-beta1) production are associated with adhesion development. This study investigated the expression of TGF-beta1 in peritoneal tissue, and possible correlation with components of the fibrinolytic system locally in peritoneal tissue.

MATERIALS AND METHODS

Peritoneal samples were taken from 22 patients at relaparotomy. Samples of adhesions were collected from 10 patients. The patients were categorized into different groups depending on the quantity and the quality of adhesions. TGF-beta1 and components of the fibrinolytic system in tissue extracts were assayed using enzyme-linked immunosorbent assays.

RESULTS

The concentration of active TGF-beta1 in peritoneal samples from patients with extensive adhesions was double (P <.01) that of healthy subjects, but the total levels of TGF-beta1 were similar (P =.63). In adhesion tissue, both active (P <.003) and total (P <.008) TGF-beta1 concentrations were more than twice as high as unaffected peritoneum. There was a significant correlation between the concentration of plasminogen activator inhibitor type 1 in peritoneal samples with active TGF-beta1 (P <.03, r = 0.693) and adhesion tissue with total TGF-beta1 (P =.001, r = 0.872). The other components of the fibrinolytic system did not correlate significantly with TGF-beta1.

CONCLUSIONS

These data indicate that an overexpression of TGF-beta1 is associated with adhesion formation, possibly through a mechanism involving local regulation of plasminogen activator inhibitor type 1.

Response of visceral peritoneum to abdominal surgery

BACKGROUND

Postoperative adhesion formation has been associated with a reduced capacity to degrade fibrin within the peritoneal cavity. Peritoneal fibrinolytic capacity has been shown to decrease during the course of a surgical operation. The aim of this study was to investigate whether tissue-type plasminogen activator (tPA), a key fibrinolytic enzyme, is released into the peritoneal cavity during operation.

METHODS

Fluid released from the serosal surface of the small bowel was collected in a plastic bag from 16 patients undergoing surgery. Intraoperative blood samples were also taken from seven patients. Concentrations of the fibrinolytic components tPA and urokinase plasminogen activator (uPA), tPA activity and plasminogen activator inhibitor type 1 (PAI-1) concentration were measured by enzyme-linked immunoabsorbent assay.

RESULTS

Intraoperative tPA concentrations were significantly raised in the peritoneal fluid collected compared with peripheral blood levels (P = 0.008). This resulted in a significantly higher tPA activity in the fluid compared with blood (P = 0.001). However, neither uPA (P = 0.29) nor PAI-1 (P = 0.84) concentrations differed significantly in fluid compared with blood.

CONCLUSION

These data suggest that tPA is rapidly released by the visceral peritoneum during abdominal surgery. The different concentrations in peripheral blood and peritoneum suggest that tPA is released from the peritoneum by an active process, and does not solely derive from leakage of plasma.

The role of cytokines, coagulation, and fibrinolysis in peritoneal tissue repair

Peritoneal tissue repair is a distinct entity. Regardless of the type of injury, a common series of events follows, culminating in inflammation and restoration. Molecular actors interact in a series of events in which the balance of fibrin deposition and degradation is vital. Although the complexity of the repair is illustrated by the multitude of effects and the overlap of molecular mediators involved, a framework is emerging. In this context, the overall role of cytokines is to shift the balance of fibrin deposition and degradation in favour of fibrin residues. Coagulation, as well as generating fibrin, is probably of importance in stimulating remesothelialisation, and fibrinolysis is instrumental in the degradation of fibrin deposits. As far as wound healing in concerned, we propose that the ultimate goal may not be to prevent adhesions, but rather to control their formation. To attain this, site-specific modulation of the repair process is essential. The new insights in mediators and modulators reviewed in this paper may provide means for site-specific modulation of peritoneal tissue repair as well as constituting molecular markers of the repair process.

Tissue markers as predictors of postoperative adhesions

BACKGROUND

Postoperative adhesion formation has been associated with a decreased capacity to degrade intra-abdominally deposited fibrin. Adhesions, once lysed, have a high propensity for reformation. This study tested the hypothesis that patients with a high propensity for adhesion formation as well as adhesion tissue had a reduced fibrinolytic capacity.

METHODS

Peritoneal biopsies were taken during abdominal surgery from 21 patients who had previously undergone operation; previously formed adhesion tissue was sampled from ten of these patients. Adhesion formation was scored. The fibrinolytic capacity of peritoneum was determined in tissue extracts.

RESULTS

At the time of opening of the abdominal cavity, levels of plasminogen activator inhibitor (PAI) type 1 (P = 0.009) and tissue-type plasminogen activator (tPA)/PAI complex (P = 0.008) were increased in peritoneal samples from patients with severe adhesions compared with those in samples from patients with less severe adhesions. Adhesion tissue similarly had reduced fibrinolytic capacity as judged by a decrease in tPA activity (P = 0.005) and an increase in PAI-1 level (P = 0.01), reflected in an increased level of tPA/PAI complex (P = 0.008) compared with unaffected peritoneum.

CONCLUSION

These observations demonstrate reduced fibrinolytic capacity in peritoneal tissue in patients with a greater propensity for development of adhesions and likewise in adhesion tissue. This suggests that components of the fibrinolytic system may be used as markers of an increased risk of adhesion development.

Characterization and fibrinolytic properties of mesothelial cells isolated from peritoneal lavage

Human peritoneal mesothelial cells were harvested from patients undergoing open or laparoscopic surgery for non-septic conditions using three different approaches: (1) from a peritoneal biopsy, (2) from peritoneal fluid, and (3) from lavage fluid collected from peritoneal cavity. When these different methods were compared, cells derived from peritoneal fluid or lavage were more likely to result in established cultures than those obtained from biopsies. The cells displayed morphological, immunohistochemical and ultrastructural characteristics of mesothelial cells. The cultured mesothelial cells produced tissue type plasminogen activator (t-PA), urokinase plasminogen activator (uPA), and plasminogen activator inhibitor type-1 and type-2 (PAI-1 and PAI-2) during unstimulated conditions. Treatment with the proinflammatory mediators LPS and TNF-alpha resulted in an overall decreased fibrinolytic capacity with a decrease in the release of t-PA and an increase in plasminogen activator inhibitors PAI-1 and PAI-2. TNF-alpha had a more profound effect than LPS, especially on the release of t-PA. This may be an important mechanism by which inflammatory mediators disrupt the fibrin degradation. In conclusion, peritoneal lavage is a convenient and reproducible source of mesothelial cells for culture.

Cost of bowel obstruction resulting from adhesions

OBJECTIVE

To assess the direct costs associated with bowel obstruction resulting from adhesions.

DESIGN

Prospective study.

SETTING

University Hospital, Sweden.

SUBJECTS

57 patients aged 16 years or older who fulfilled the clinical and radiological criteria of bowel obstruction.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Course of, and direct costs associated with, the illness.

RESULTS

In 34 of the 57 patients (60%) bowel obstruction was caused by adhesions, and in all 34 the small bowel was obstructed (85% of all cases of small bowel obstruction). 22 of the 42 patients who required a hospital stay of more than 24 hours (52%) had adhesive obstruction, and 10 of these (45%) had to be operated on, 2 of them twice. Major complications occurred in 6 (60%) and one died. In a national perspective, adhesive bowel obstruction may cause 2330 hospital admissions annually, which is associated with an estimated direct cost of about US$13 million.

CONCLUSIONS

Adhesions are a serious, common, and costly complication of surgery. Efforts have to be undertaken to control their formation.

Plasminogen activators and inhibitors in peritoneal tissue

Serosal trauma elicits an inflammatory response which leads to the deposition of fibrin at injured sites, the residuals of which appear to be essential in excessive tissue repair and formation of intraabdominal adhesions. Local plasminogen activity may modulate this early phase of tissue repair. The present study was undertaken to investigate the distribution and cellular expression of plasminogen activators and their inhibitors in human peritoneal normal and inflamed tissue. Tissue-type plasminogen activator (t-PA) was expressed in subserosal capillary walls, and in normal mesothelium, but not in inflammation. Immunoreactivity for the plasminogen activator inhibitor type 1 (PAI-1) was present in normal mesothelium, and substantially increased in inflammation, where, in addition, immunoreactivity was found throughout the submesothelial tissue. This PAI-1 was partly co-localized with macrophages, as was the urokinase plasminogen activator (u-PA), suggesting an involvement of these cells in peritoneal tissue fibrinolysis. Inflammation or abrasion of the mesothelium during surgery is likely to cause a depletion of the local t-PA source and expose the potentially PAI-1-containing submesothelial tissue, thus promoting persistence of fibrin and formation of adhesions.

Vertical field MR imaging of upper thorax and spine in small children. Evaluation of a new surface coil

To improve image quality in a vertical field MR imaging unit, operating at low field strength (0.3 T), we have designed a half-elliptical coil for use in the upper thoracic region of small children. Our intention was also to shorten the examination time, which until now has been long, because several scans with different coils have been necessary to cover the thoracic region. The experimental coil is designed so that a child's shoulders fit into the central region. The coil consists of 2 serially connected cable-loops, mounted on a foam rubber vest. The coil performance was tested in a phantom and improvements relative to standard coils were demonstrated in in vivo studies. The results indicate that by using the half-elliptical coil, the signal-to-noise (S/N) ratio can be improved by a factor of 2 to 3 in the thoracic region of a child.