The effect of pentoxifylline on the healing of intestinal anastomosis in rats with experimental obstructive jaundice

Pentoxifylline decreases post-operative intra-abdominal adhesion formation in an animal model

Background

Intra-abdominal adhesions develop after nearly every abdominal surgery, commonly causing female infertility, chronic pelvic pain, and small bowel obstruction. Pentoxifylline (PTX) is a methylxanthine compound with immunomodulatory and antifibrotic properties. The aim of this study was to investigate whether PTX can reduce post-operative intra-abdominal adhesion formation via collagen deposition, tissue plasminogen activator (tPA) level, inflammation, angiogenesis, and fibrosis.

Methods

Seventy male BALB/c mice were randomized into one of three groups: (1) sham group without peritoneal adhesion model; (2) peritoneal adhesion model (PA group); (3) peritoneal adhesion model with PTX (100 mg/kg/day i.p.) administration was started on preoperative day 2 and continued daily (PA + PTX group). On postoperative day 3 and day 7, adhesions were assessed using the Lauder scoring system. Parietal peritoneum was obtained for histological evaluation with hematoxylin and eosin (HE) and picrosirius red staining. Fibrinolysis was analyzed by tPA protein levels in the peritoneum by ELISA. Immunohistological analysis was also conducted using markers for angiogenesis (ki67⁺/CD31⁺), inflammation (F4/80⁺) and fibrosis (FSP-1⁺ and α-SMA⁺). All the comparisons were made by comparing the PA group with the PTX treated PA group, and p < 0.05 was considered statistically significant.

Results

Intra-abdominal adhesions were markedly reduced by PTX treatment. Compared with the PA group, PTX treatment had lower adhesion scores than the PA group on both day 3 and day 7 (p < 0.05). Histological evaluations found that PTX treatment reduced collagen deposition and adhesion thickening. ELISA analysis showed that PTX treatment significantly increased the level of tPA in the peritoneum. In addition, in the immunohistological analysis, PTX treatment was found to significantly decrease the number of ki67⁺/CD31⁺ cells at the site of adhesion. Finally, we also observed that in the PTX treated group, there was a reduction in the expression of F4/80⁺, FSP-1⁺, and α-SMA⁺ cells at the site of adhesion.

Conclusion

PTX may decrease intra-abdominal adhesion formation via increasing peritoneal fibrinolytic activity, suppressing angiogenesis, decreasing collagen synthesis, and reducing peritoneal fibrosis. Our findings suggest that PTX can be used to decrease post-operative intra-abdominal adhesion formation.

The Effect of Infliximab on Intestinal Anastomosis Healing in Rats

Intestinal anastomosis healing is a complex physiological process in which many local and systemic factors play a role. One of the significant cytokines in this process is TNF-α. Infliximab is a chimeric monoclonal antibody which binds to TNF-α with high affinity. Although this agent is used in ulcerative colitis and Crohn’s disease, intestinal surgery may be required in these patients. In this study it was aimed to determine whether or not there was any negative effect of preoperative single dose infliximab treatment on intestinal anastomosis healing. Two groups of 10 rats were formed. One of these groups was administered with a single dose of infliximab 8 mg/kg as a 20-minute intravenous infusion from the femoral vein. Four days after the infusion, a full layer incision was made to the colon and anastomosis was applied to all the rats. At 7 days after anastomosis, the subjects were sacrificed. The anastomosis segment was removed and the bursting pressure was measured. Tissue samples were taken from this segment for hydroxyproline concentration and histopathological examination. A blood sample was taken to measure TNF-α values. No statistically significant difference was determined between the groups in terms of bursting pressure, tissue hydroxyproline concentration or histopathological scoring. A single dose of 8 mg/kg infliximab administered 4 days preoperatively was not found to have any negative effect on intestinal anastomosis healing in rats.

Effects on bacterial translocation of high-fat enteral nutrition in bile duct ligated rats

OBJECTIVE

Bacterial Translocation (BT) from the gastrointestinal system is at the center of current sepsis theories. In patients with obstructive jaundice, the absence of intraluminal bile flow causes some alterations and mucosal damage in the gut. In the present study, it was aimed to investigate the effects on BT of high-fat enteral nutrition in bile duct ligated rats.

MATERIAL AND METHODS

In this study, a total of 28 healthy Spraque-Dawley rats, weighing 230-300 gr, were grouped into four as sham group, control group, high-fat enteral nutrition group and low-fat enteral nutrition group. The rats in all the groups were sacrificed on the seventh postoperative day The values of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), total and direct bilirubin were measured for biochemical evaluation. Also, samples were taken from the blood, lung, liver, spleen and mesenteric lymph nodes for microbiological evaluation. The results were calculated as CFU/gr and evaluated statistically.

RESULTS

In all bile duct ligated rats, all findings of obstructive jaundice were observed clinically (in postoperatively third day) and in the laboratory. It was determined that the lymphatic system is an essential pathway for BT, as reported by similar studies. However, it was observed in this study that the high-fat enteral nutrition may be not severely effective in reducing BT in bile duct ligated rats. The results were supported by statistical analyses.

CONCLUSION

It was observed that high-fat enteral nutrition has no meaningful effects on reducing BT in bile duct ligated rats.

Effect of thalidomide on the healing of colonic anastomosis, in rats

PURPOSE: Thalidomide, because of its anti-inflammatory properties, as re-emerged as an option for the treatment of Crohn's disease refractory to standard therapy. We studied the effect of thalidomide on the healing of colonic anastomosis. METHODS: Sixty male rats (Rattus norvegicus), were divided into 3 groups of 20 animals each, respectively receiving 0.5 or 1.0 mg/kg thalidomide by the oral route for 7 days, or saline solution (control). All animals were submitted to continuous end-to-end anastomosis with 6-0 Prolene sutures. After sacrifice the anastomoses were analyzed macroscopically and submitted to determination of hydroxyproline, to histology and to immunohistochemistry for metalloproteinase 1, metalloproteinase 1 inhibitor and vascular endothelial growth factor (VEGF). RESULTS: Statistical analysis of the data showed no significant difference in macroscopic aspect or hydroxyproline determination (p= 0.5403). In the immunohistochemical analysis, the following p values were obtained: p = 0.5817 for VEGF, p = 0.1854 for metalloproteinase 1, and p = 0.0023 for metalloproteinase 1 inhibitor, with this last value being considered statistically significant. CONCLUSION: We conclude that thalidomide influenced collagen maturation. There was a stronger action of metalloproteinases, possibly indicating a negative tendency for the healing process.

The effect of purified micronized flavonoid fraction on the healing of anastomoses in the colon in rats

PURPOSE

Anastomotic leakage of colonic and rectal anastomoses is a major complication after large intestine surgery. Many factors influence the healing of colon anastomoses. Flavonoids have been recognized for centuries as physiologically active constituents that are used to treat human diseases. We studied the effects of a clinically used, micronized, purified flavonoid fraction on the healing of colonic anastomosis in rats.

METHODS

Male Sprague-Dawley rats were used. The flavonoid group of rats received 100 mg/kg per day of Daflon for 14 days until surgery. Thereafter, a resection and anastomosis were performed. The bursting pressure of the anastomoses and the hydroxyproline levels of the perianastomotic tissue were determined to evaluate the healing on the third and seventh days of surgery for both flavonoid and control groups.

RESULTS

The bursting pressure of the flavonoid group was higher on the seventh day. The hydroxyproline levels of the flavonoid group were significantly higher than in the control group on both the third and seventh days after surgery.

CONCLUSIONS

Although the micronized purified flavonoid fraction has some inhibitory properties on the healing of the anastomosis, its net effect was to obtain a better anastomotic healing of the colon in rats.

Effect of calcitonin gene-related peptide on anastomotic healing in the presence of endotoxin

BACKGROUND

Intestinal anastomotic healing is a complex procedure in which several mediators, cytokines and other substances play roles, as well as calcitonin gene-related peptide (CGRP). CGRP is capable of stimulating DNA synthesis and cell proliferation in endothelial cells by increasing vasodilatation and inflammatory response and promoting epithelial, vascular and mesothelial cell proliferation. This study was undertaken to investigate whether CGRP has a beneficial effect on intestinal anastomotic healing, even in septic conditions.

METHODS

Four groups of 10 rats were administered normal saline (0.5 mL), lipopolysaccharide (LPS) (0.5 mg/kg), CGRP (0.5 mL 6.5 x 10(-10) mol/L) and LPS + CGRP (0.5 mg/kg + 0.5 mL 6.5 x 10(-10) mol/L) via intraperitoneal route, respectively, 24 h prior to operation and postoperatively. All rats underwent ileo-ileal end-to-end anastomosis. Anastomotic bursting pressure and tissue hydroxyproline levels were measured on postoperative day 7.

RESULTS

Calcitonin gene-related peptide was found to have positive effects on both parameters of healing. The LPS-injected group showed intestinal anastomotic healing disorder suggesting impaired collagen production, which showed improvement after CGRP administration.

CONCLUSIONS

Calcitonin gene-related peptide increases anastomotic wound healing in experimental intestinal anastomosis in the presence of endotoxin.

Effects of high bilirubin levels on the healing of intestinal anastomosis

PURPOSE

This article analyzes the relationship between high biluribin levels and anastomotic healing in the long term.

METHODS

Ninety rats were randomly divided into six groups. The first three groups were jaundiced while the other three were unjaundiced. In the jaundiced groups, the rats' common bile ducts were ligated for 1, 2, and 3 weeks and ileal anastomosis was performed. In unjaundiced groups, only anastomosis was performed for 1, 2, and 3 weeks. At the end of the study, the values of the bursting pressures and hydroxyproline levels were determined in all groups. The bilirubin levels were also followed in jaundiced groups.

RESULTS

In the jaundiced groups, the mean hydroxyproline contents were 7.5 +/- 4.0, 6.3 +/- 2.3, and 5.6 +/- 2.1 (microHP/mg tissue) and the mean bursting pressures were 178 +/- 38, 171 +/- 23, and 164 +/- 26 mmHg at weeks 1, 2, and 3, respectively. In the unjaundiced groups, the mean hydroxyproline contents were 7.6 +/- 3.2, 8.1 +/- 3.0, and 8.6 +/- 2.5 (microHP/mg tissue) and the mean bursting pressures were 181 +/- 28, 183 +/- 21, and 186 +/- 22 mmHg at weeks 1, 2, and 3, respectively. The bilirubin levels were 3.8 +/- 1.5, 6.5 +/- 2.3, and 11.2 +/- 2.9 mg/dl at weeks 1, 2, and 3, respectively, in the jaundiced groups and 0.6 +/- 0.06, 0.6 +/- 0.03, and 0.7 +/- 0.04 mg/dl in the unjaundiced groups.

CONCLUSION

This study showed that the bilirubin levels can lead to a deterioration depending on the magnitude of the rise in the bilirubin levels.

Effect of jaundice and its resolution on wound re-epithelization, skin collagen synthesis, and serum collagen propeptide levels in patients with neoplastic pancreaticobiliary obstruction

BACKGROUND

Wound and anastomotic healing is considered to be delayed in patients with obstructive jaundice. The study was designed to find out whether the healing of experimental suction blister wounds, skin collagen synthesis, and serum procollagen levels are affected by obstructive jaundice, and if biliary drainage may cause any alterations in these processes.

PATIENTS AND METHODS

Suction blisters were induced on 24 patients with obstructive jaundice caused by neoplastic pancreaticobiliary obstruction and 17 control patients with the corresponding condition without jaundice, to compare healing parameters and collagen synthesis between the groups. A second set of suction blisters were induced on 13 formerly jaundiced patients after the resolution of jaundice and on 14 control patients, to find out whether drainage or time modifies healing or collagen synthesis. By using this model, it is possible to evaluate the re-epithelization and inflammation on wound healing and to assess the baseline skin collagen synthesis. The healing of suction blisters was followed up by measuring water evaporation and blood flow in the wound. Blister fluids and serum samples were collected to study collagen propeptides.

RESULTS

Healing of the blister wound was unaffected by obstructive jaundice. Drainage had no effect on healing. The baseline synthesis of type I and type III collagen in the skin was decreased in jaundiced patients. Biliary drainage improved the synthesis. Serum type III procollagen propeptide levels were elevated in jaundiced patients, but began to normalize after drainage.

CONCLUSION

Healing of an experimental blister wound is not disturbed by obstructive jaundice. The decreased baseline skin collagen synthesis is partly restored by the resolution of jaundice. The results indicate that cell protein synthesis is disturbed earlier than cell dynamics in obstructive jaundice. The elevated serum PIIINP levels, which are most likely to be related to early fibrosis in liver, decreased after drainage.

Experimental bile-duct ligation resulted in accumulation of oxidized low-density lipoproteins in BALB/c mice liver

BACKGROUND AND AIM

Oxidized low-density lipoproteins (LDL), which are produced during oxidative stress by the process of lipid peroxidation, have also been proposed to have complex roles in many other immuno-inflammatory mechanisms. It has been shown that bile-duct ligation results in oxidative stress in the liver of animals. The aim of this study was to investigate if oxidized LDL are produced in the liver tissues of bile-duct-ligated mice.

METHODS

Obstructive jaundice was induced in BALB/c mice by the ligation and division of the common bile duct. Liver concentrations of glutathione and malondialdehyde were measured in the sham-operated (n = 10) and bile-duct-ligated (n = 10) mice on the 10th day of obstructive jaundice. The presence of oxidized LDL in the liver tissue sections was evaluated using a special, novel immunofluorescent staining method. The final step was to explore the existence of oxidized LDL under fluorescent microscopy.

RESULTS

Compared with sham-operated mice, jaundiced mice showed significantly higher levels of malondialdehyde and lower concentrations of reduced glutathione in the liver. While there was no staining in the sham-operated group, bile-duct ligation resulted in positive oxidized LDL staining in the liver tissues of mice. The present study testifies that bile-duct ligation results in oxidative stress and enhanced lipid peroxidation in the hepatic tissues of BALB/c mice and moreover, that oxidized LDL accumulate in the liver of mice with experimental obstructive jaundice.

CONCLUSION

Oxidized LDL may be an important and direct indicator of ongoing oxidative stress and enhanced lipid peroxidation in obstructive jaundice. The potential roles of this finding were also discussed, briefly.

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Efficacy of perioperative thromboprophylactic agents in the maintenance of anastamotic patency and survival of rat microvascular free groin flaps

OBJECTIVES

We sought to determine the thromboprophylactic effects of low-molecular-weight heparin (LMWH) and pentoxifylline.

DESIGN

Randomized blinded study. Materials and methods Sixty Sprague-Dawley rats were assigned to 1 of 4 treatment groups: (1) control group (n = 15), (2) pentoxifylline group (n = 15), (3) LMWH group (n = 15), and (4) combined therapy group (n = 15). A groin/abdominal free flap was elevated in each, with division of the artery and microvascular repair The animals received therapy for 4 days preoperatively and 6 days postoperatively. Flaps were monitored visually, and on the seventh postoperative day, the flap was elevated, and the microvascular anastomosis was assessed for patency.

RESULTS

There was a statistically significant improvement in arterial patency in both pentoxifylline and LMWH groups compared with controls (P < 0.01) but no significant improvement with combined therapy (P > 0.05).

CONCLUSIONS

In this animal model, LMWH and pentoxifylline have significant thrombroprophylactic effects when used individually but not in combination.