Myofibroblasts and colonic anastomosis healing in Wistar rats

Background

Mesh repair of incisional hernia is superior to the conventional technique. From all available materials for open surgery polypropylene (PP) is the most widely used. Development resulted in meshes with larger pore size, decreased mesh surface and lower weight. The aim of this retrospective non randomized study was to compare the quality of life in the long term follow up (> 72 month) after incisional hernia repair with "light weight"(LW) and "heavy weight"(HW) PP meshes.

Methods

12 patients who underwent midline open incisional hernia repair with a HW-PP mesh (Prolene^® 109 g/m² pore size 1.6 mm) between January 1996 and December 1997 were compared with 12 consecutive patients who underwent the same procedure with a LW-PP mesh (Vypro^® 54 g/m², pore size 4-5 mm) from January 1998. The standard technique was the sublay mesh-plasty with the retromuscular positioning of the mesh. The two groups were equal in BMI, age, gender and hernia size. Patients were routinely seen back in the clinic.

Results

In the long term run (mean follow up 112 ± 22 months) patients of the HW mesh group revealed no significant difference in the SF-36 Health Survey domains compared to the LW group (mean follow up 75 ± 16 months).

Conclusions

In this study the health related quality of life based on the SF 36 survey after open incisional hernia repair with light or heavy weight meshes is not related to the mesh type in the long term follow up.     

Myofibroblasts and colonic anastomosis healing in Wistar rats

Background  

The myofibroblasts play a central role in wound healing throughout the body. The process of wound healing in the colon was evaluated with emphasis on the role of myofibroblasts.     

The effect of rapamycin on the healing of the ureteric anastomosis and wound healing

Rapamycin is a potent immunosuppressive agent that also inhibits fibroblastic activity and therefore may affect the healing of various tissues. The aim of this study was to investigate the effect of rapamycin on wound healing and the healing of the ureteric anastomosis. Large White/Landrace pigs were subjected to a laparotomy and division and immediate anastomosis of the ureter. The animals were randomly allocated to receive either rapamycin or placebo. The animals were sacrificed on postoperative day 5, and strips of the skin and fascia closure and the ureteric anastomosis excised and used to determine the tensile strength, hydroxyproline levels, and histological changes. The tensile strength and the hydroxyproline levels in the ureter and fascia were lower in the rapamycin-treated animals. There was no difference in the tensile strength in the skin, although the hydroxyproline levels were lower. This study shows that healing of the ureteric anastomosis and fascia and skin closure may be impaired by rapamycin.     

Effect of fibrin sealant on the healing colonic anastomosis in the rat

Fibrin adhesives have been advocated as a protective seal in colonic anastomosis to prevent leakage. In order to assess the effect of fibrin glue sealing we compared the healing of sutured colonic anastomosis in the rat (group 1) with the addition of human-derived fibrin sealant (group 2). As a control for a possible reaction to foreign protein, in group 3 the sutured anastomosis was sealed with specially prepared rat fibrin adhesive. On days 2, 4 and 7, ten animals in each group were killed. Adhesion formation was scored and the in situ bursting pressure was measured. The collagen concentration and degradation were estimated by measuring hydroxyproline. Adhesion formation was significantly increased in groups 2 and 3 compared with the control group. On days 2 and 7 the bursting pressure was not different between the groups. On day 4 the bursting pressure in groups 2 and 3 was significantly lower than in group 1 (P less than 0.001). These findings correspond with the results of collagen measurements. On day 4 the concentration of hydroxyproline was significantly reduced in groups 2 and 3. Histological examination showed infiltration of neutrophilic granulocytes into the sealant on days 2 and 4; on day 7 the sealant had vanished. From these results it is concluded that fibrin sealing of the colonic anastomosis in the rat does not improve healing, as demonstrated by bursting pressure and hydroxyproline concentration. On the contrary, it seems to have a negative influence.     

Colonic anastomosis healing. The effect of topical povidone-iodine

The effect of povidone-iodine (0.1% available iodine) irrigation on colonic anastomosis healing was investigated in 196 Sprague-Dawley rats. Each end of the divided colon was irrigated with 5 ml of povidone-iodine solution or with an equal volume of normal saline before anastomosis and again after the anastomosis had been completed. Healing was assessed at 2, 4, 6, 8, 10, and 14 days after operation: macroscopically, mechanically, histologically and angiigraphically. Povidone-iodine irrigation did not impair healing in any way.     

The effect of remote ischemic preconditioning on healing of colonic anastomoses

BACKGROUND: We aimed to investigate the potential protective effect of remote ischemic preconditioning (IPC) on delayed colonic anastomotic healing induced by remote ischemia and reperfusion (I/R) injury. MATERIALS AND METHODS: Forty male Wistar rats were randomly assigned into four groups, each consisting of 10 rats: the control group (C), the remote I/R group [I/R, 40 min of superior mesenteric artery (SMA) occlusion], the preconditioned I/R group (IPC, two cycles of 5 min temporary occlusion of SMA before an ischemic insult of 40 min), and the preconditioned group (PC, two cycles of 5 min temporary occlusion of SMA). Colonic anastomosis was performed immediately after the ischemic insult. Anastomotic healing was assessed on postoperative day 7 by determining anastomotic bursting pressure (ABP), tissue hydroxyproline content, histopathological examination, malondialdehyde (MDA), and nitric oxide levels. RESULTS: Remote I/R injury resulted with significant impairment in anastomotic healing in terms of mean ABP (P = 0.004), hydroxyproline content (P = 0.002), histopathological healing score (P = 0.001), nitric oxide level (P = 0.010), and MDA levels (P = 0.0001) when compared with the control group, but remote IPC did not improve all above mentioned parameters (P = NS for all), except MDA level (P = 0.011) when compared with I/R group. PC alone impaired the ABP (P = 0.0001), but it did not significantly change the other parameters measured (P = NS). CONCLUSIONS: The results of this study showed that remote IPC did not prevent I/R-induced delaying in colonic anastomotic healing.     

Effect of melatonin on healing of colonic anastomosis in a rat model of peritonitis

BACKGROUND: The aim of this study is to determine the effect of melatonin on intestinal anastomosis in the presence of peritonitis. MATERIAL AND METHODS: 32 Wistar albino rats were randomized into four groups (n = 8): A (sham), B (control), C (melatonin 5 mg/kg), and D (melatonin 10 mg/kg). In group A, only cecal dissection was carried out. In the other groups, cecal ligation and puncture (CLP) followed cecal dissection in order to induce bacterial peritonitis. 24 h after the previous operation, cecal resection and ileocolic anastomosis were performed in the rats of all groups. In group C (5 mg/kg) and group D (10 mg/kg), melatonin was injected for 5 consecutive days starting after CLP. At the 48th hour of the CLP procedure, blood was drawn via the tail vein for tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) analysis, and on the 4th day of the experiment relaparotomy was carried out for bursting pressure (BP) measurements. The intestinal tissue containing the anastomotic line was then snap-frozen in liquid nitrogen and stored at -80 degrees C for determination of tissue levels of malondialdehyde (MDA) and glutathione (GSH). RESULTS: The tissue MDA level, blood TNF-alpha and IL-6 levels of group B were significantly higher than in the other groups, whereas the BP results and GSH levels of group B were found to be significantly lower than in the other groups. The results of groups C and D are statistically different from those of group B. When we compared the results of groups C and D, we found significantly higher results in terms of BP and GSH levels in group D and also significantly lower results in terms of MDA, blood TNF-alpha and IL-6 levels in group D. CONCLUSION: The findings of this experiment suggest that melatonin has a dose-independent positive effect on wound healing of colonic anastomosis.     

The effect of methionine on colonic wound healing in malnourished rats.

Recent studies have suggested that the healing of colonic anastomoses is impaired in malnourished subjects. It has been claimed that the healing of skin and abdominal wounds in experimental animals is improved by the administration of the essential amino acid methionine, and in the present study the effects of methionine on colonic wound healing were studied in malnourished rats. Test animals were fed a protein-free diet for 7 weeks before surgery. Methionine-treated animals received the amino acid by subcutaneous injection during the seventh week of protein deprivation and throughout the postoperative period. Anastomoses were made in the left colon, and colonic wound healing was assessed by measurements of the bursting wall tension and collagen content of anastomoses. The results were compared with those of control animals fed a normal rat diet. Protein deprivation for 7 weeks resulted in a 34% reduction in body weight, and a significant reduction in the tensile strength and collagen content of colonic anastomoses was observed. Methionine supplements had no apparent effect on these parameters of wound healing. The concept of single amino acid supplementation in cachetic patients undergoing surgery is an attractive one, but it has yet to be established that methionine supplements alone can alter the course of wound healing in such cases.     

The effect of relative bowel rest on healing of colonic anastomoses. Breaking strength and collagen in the colonic wall following left colon resection and anastomosis in the rat

The breaking strength of anastomoses in the left colon in the early phase of healing was studied in rats fed low residue diet (Biosorbin MCT) and the results were compared to those from rats fed standard laboratory diet. Further, eventual correlation between mechanical strength development and collagen content in the colonic wall around the anastomosis was evaluated. The anastomotic strength with sutures in place decreased by approximately 30% of the immediate postoperative value during the first two days in both groups of animals. There was no correlation between changes in anastomotic strength and collagen content at that time. After the second day there was a gradual increase of anastomotic strength, reaching the strength at day 0 after 7 days. The regain of strength was mainly due to collagen deposition in the anastomosis. Despite more collagen deposition in animals on standard laboratory diet the anastomoses had comparable strength development in the two groups. It was concluded that low residue diet does not impair the suture holding capacity or the anastomotic strength. Instead there was some evidence for a more uncomplicated healing when the bowel content was diminished.     

The effect of relative bowel rest on healing of colonic anastomoses. Collagen synthesis and content in the colonic wall after left colon resection and anastomosis in the rat

Collagen metabolism was studied in the colonic wall of rats after standardized resection and anastomosis. Diminished faecal loading was obtained by feeding rats low-residue diet (Bisorbin MCT). The postoperative increase of collagen synthesis and collagen content was on a lower level in these rats than in rats on standard laboratory diet. The increase was confined to the immediate anastomotic region and presumably represented changes in collagen caused by the operative trauma per se. It was concluded that the intraluminal content is an important factor in stimulating collagen turnover. The findings of lower collagen turnover in the anastomotic area in animals on low-residue diet may have positive significance, but could also imply impairment of healing. For elucidation of this question, studies on mechanical strength of the anastomosis are necessary.     

Influence of the stable prostacyclin analog iloprost on the healing of colonic anastomosis in rats

AIM: The aim of this study was to investigate whether iloprost injected intraperitoneally immediately after colon resection can improve anastomotic healing on the fifth and eighth postoperative days. METHODS: Forty Wistar rats were randomised into 2 equal groups. After the resection of a 1 cm segment of transverse colon, an end to end sutured anastomosis was generated. From the day of the operation, group 1 (control) received intraperitoneal 3 cc saline solution once daily until sacrifice, while group 2 (iloprost) received iloprost in a dose of 2 mg/kg body weight intraperitoneally once daily until sacrifice. Each group was further randomly divided into 2 equal subgroups and animals were sacrificed on the fifth (subgroup A), and eighth (subgroup B) postoperative days. After sacrifice, anastomoses were examined macroscopically and were measured for bursting pressures and tissue hydroxyproline levels while anastomotic healing process was evaluated histopathologically. RESULTS: None of the rats exhibited any clinical evidence of leakage and there were no instances of peri-anastomotic abscess or peritonitis. Bursting pressure on the fifth postoperative day was significantly higher in the iloprost group than in the control group (P<0.001), while on the eighth postoperative day, bursting pressure was higher in the iloprost group but not significantly different (P=0.165). On both the fifth and eighth postoperative days rats in the iloprost group developed significantly more marked neo-angiogenesis and, in parallel with this, there was a trend showing a higher inflammatory cell infiltration. CONCLUSION: The intraperitoneal administration of iloprost promoted neo-angiogenesis and enhanced colonic healing on the fifth postoperative day.     

The colonic J-pouch in colo-anal anastomosis

Anastomosis of the colon to the anal canal is now an accepted technique in the surgical management of low and mid rectal cancers. Although significant postoperative bowel disturbance is often seen with straight colo‐anal anastomosis, controversy exists over the benefit of adding a colonic pouch for low anastomoses. Several short and long‐term studies have demonstrated the early functional superiority of pouch‐anal over straight anastomosis. Pouch construction does not compromise anal physiological parameters. It is recommended the pouch be constructed from a length of descending colon and be small (5 cm) in size to adequately act as a neo‐rectum; long‐term evacuatory difficulties are encountered with the construction of large pouches (10 cm). Anastomotic complications appear to be less frequent with pouch surgery; construction of a pouch does not significantly add to operative time, patient morbidity and mortality. At present there is no compromise to long‐term oncological survival. The data supporting these statements is weak and based largely upon retrospective studies. Furthermore the impact of improved function with pouch‐anal anastomosis on overall quality of life has been poorly investigated. Further prospective randomized studies are required to ascertain whether the potential benefits of a colonic pouch are realized in the randomized setting.     

The effect of cartilage-bone marrow extract (CBME) on the healing of intestinal anastomosis

The intestinal anastomosis made under various conditions with and without treatment with cartilage-bone marrow extract were compared. The preoperative or postoperative administration of cartilage-bone marrow extract was found to increase mechanical strength of the intestinal anastomosis, even under unfavorable conditions such as hypoproteinemia, long term treatment of corticoid or reanastomosis. Formation of connective tissue and healing process were also found to be promoted by cartilage-bone marrow extract treatment.     

Effects of intraluminal infusion of short-chain fatty acids on the healing of colonic anastomosis in the rat

The effects of an intracolonic infusion of short-chain fatty acids (SCFA) on the healing of colonic anastomosis in the rat were investigated. Thirty-three Sprague-Dawley rats underwent transection and anastomosis of the descending colon and transection and diversion of the ascending colon. The proximal limb of the ascending colon was exteriorized as an end colostomy, and the distal (defunctionalized) limb was cannulated for continuous infusion. Rats received either no infusion (N = 11) or an infusion of either electrolytes (N = 11) or SCFA (acetate, propionate, and butyrate; N = 11) into the defunctionalized colonic segment. On the sixth postoperative day bursting pressure (BP) and bowel wall tension (BWT) were determined. The occurrence of spontaneous anastomotic dehiscence was significantly less for the SCFA group (0/11) compared with the no infusion group (5/11, p less than 0.01). The anastomotic suture line burst in significantly fewer colons from the SCFA group (1/11) than either the electrolyte infusion (8/11, p less than 0.003) or the no infusion (6/6, p less than 0.001) groups. BP and BWT were significantly higher for the SCFA group (BP: 147 +/- 10 mm Hg; BWT: 59 +/- 1.0 dyne 10(3)/cm) than for either the electrolyte (BP: 99 +/- 30 mm Hg, p less than 0.002; BWT: 45 +/- 19, p less than 0.03) or no infusion (BP: 111 +/- 42, p less than 0.02; BWT 36 +/- 15, p less than 0.007) groups. The results of this study indicate that intracolonic infusion of SCFA resulted in significantly stronger colonic anastomosis in the rat.