Hyperbaric oxygen therapy improves colorectal anastomotic healing

Purpose

Hyperbaric oxygen treatment (HBOT) has been found to improve the healing of poorly oxygenated tissues. This study aimed to investigate the influence of HBOT on the healing in ischemic colorectal anastomosis.

Methods

Forty Wistar rats were randomly divided into a treatment group that received HBOT for 10 consecutive days (7 days before and 3 days after surgery), or in a control group, which did not receive the therapy. Colectomy with an ischemic anastomosis was performed in all rats. In each group, the rats were followed for 3 or 7 days after surgery to determine the influence of HBOT on anastomotic healing.

Results

Five rats from each group died during follow-up. No anastomotic dehiscence was seen in the HBOT group, compared to 37.5 % and 28.6 % dehiscence in the control group on postoperative day (POD) 3 and 7, respectively. The HBOT group had a significantly higher bursting pressure (130.9?±?17.0 mmHg) than the control group (88.4?±?46.7 mmHg; p?=?0.03) on POD 3. On POD 3 and POD 7, the adhesion severity was significantly higher in the control groups than in the HBOT groups (p?<?0.005). Kidney function (creatinine level) of the HBOT group was significantly better than of the control group on POD 7 (p?=?0.001). Interestingly, a significantly higher number of CD206+ cells (marker for type 2 macrophages) was observed in the HBOT group at the anastomotic area on POD 3.

Conclusion

Hyperbaric oxygen enhanced the healing of ischemic anastomoses in rats and improved the postoperative kidney function.

     

Modulation of age-related biochemical changes and oxidative stress by vitamin C and glutathione supplementation in old rats

The present study sought to determine whether supplementation of dietary antioxidant ascorbic acid with glutathione (GSH) could ameliorate the age-related increased oxidative stress and changes in hormonal, lipid and copper (Cu) as well as zinc (Zn) levels in 18-month-old rats. The present study demonstrated that supplementation of vitamin C (30 mg) + GSH 100 mg/kg b.w. significantly reduced the concentration of thiobarbituric acid-reactive substances in liver and testes in old male rats as compared with nonsupplemented ones, indicating lower oxidative stress. In addition, testicular GSH was increased but not hepatic GSH. Also, cholesterol and triglycerides were decreased in the serum of supplemented rats. Furthermore, she serum testosterone level was increased in the same supplemented rats. However, the present results show that the thyroid hormones, T3 and T4, were not influenced. Lastly, the concentration of Cu in serum, liver, brain and testes was increased in supplemented old rats. Zn concentration was also increased in the same organs but not in the liver. According to the present study, the supplementation of antioxidants could play an important role in the modulation of the oxidative damage and changes associated with age.     

Esophagogastric anastomotic wound healing in rats

Esophagectomy with esophagogastric anastomosis is commonly complicated by anastomotic dehiscence. Although this is a major problem in clinical esophageal surgery, laboratory investigation of esophagogastric anastomotic wound healing has been hampered by the lack of a practical rodent model. Problems with aspiration pneumonia and anastomotic strictures hindered our previous studies in the rat. Other researchers have turned to large animal experiments, or used various upper gastrointestinal pseudoanastomotic techniques in rodents. None of these approaches has proved satisfactory. We developed a technique of side-to-side esophagogastric anastomosis in the rat, and then studied normal esophagogastric anastomotic healing in this model. Anastomoses were performed in 24 rats. Anastomotic breaking strength and hydroxyproline concentration were measured 1 and 2 weeks after surgery. Anastomotic breaking strength was 3.78 +/- 1.18 N at 1 week and 4.83 +/- 0.91 N after 2 weeks (p < 0.03). Anastomotic tissue hydroxyproline concentration was 370.6 +/- 31.2 nmol/mg at 1 week and 462.1 +/- 69.7 nmol/mg after 2 weeks (p < 0.001). Many of the problems encountered in esophagogastric anastomotic studies in the rat have been overcome using this new model.     

The effects of tacrolimus on colonic anastomotic healing in rats

Aim  

The aim of this experimental study is to investigate the effects of tacrolimus on colonic anastomotic healing after subcutaneous administration.     

The effect of bevacizumab on colon anastomotic healing in rats

Purpose

The aim of the study was to investigate the effect of angiogenesis inhibition by bevacizumab, a monoclonal anti-vascular endothelial growth factor (VEGF) antibody, on the healing process of colonic anastomoses in rats, assessing some specific involved factors. This new agent is used mainly in metastatic colorectal cancer. The angiogenesis plays an important role in both wound healing and metastatic invasion and spread of malignant cells. There has not been any evidence assessing the optimal time for its safe use in operated patients.

Materials and methods

Forty Wistar rats were randomly allocated into four equal groups. A colonic anastomosis was performed in all rats. Half of them received intraoperatively a single dose of bevacizumab 5 mg/body weight and the rest received placebo. The animals were sacrificed on the 7th (Avastin 7th, placebo 7th) and 14th (Avastin 14th, placebo1 4th) postoperative day. The anastomosis was resected and sent for histological study and for tissue biochemical assays (VEGF, endothelin-1 (ET-1), C-reactive protein (CRP), pro-oxidant–antioxidant balance (PAB), carbonylated proteins, hydroxyproline) using specific enzyme-linked immunosorbent assay kits. For statistical analysis, the Mann–Whitney U test was used (of statistical significance when P?<?0.05).

Results

No complication or anastomotic dehiscence was observed. Histology did not reveal statistically significant differences between groups concerning degree of inflammation, fibroblasts, collagen, and fibrosis. Likewise, hydroxyproline levels did not differ. However, some statistically significant differences were found in VEGF, CRP and carbonyl proteins (Avastin 7th vs placebo 7th, placebo 14th vs placebo 7th), ET-1, and PAB (Avastin 14th vs Avastin 7th), which did not finally affect the collagen synthesis marker hydroxyproline, nor did the anastomotic strength.

Conclusions

Bevacizumab, when administered intraoperatively, has no significant effect on colon anastomotic healing in rats despite a transient mild ischemia.     

Bursting pressure in anastomotic healing in experimentally induced colitis in rats

BACKGROUND: Experimental studies on healing of colonic anastomosis have been thoroughly investigated. However, clinical parameters of the healing process of anastomosis in the inflamed colon has not yet been reported. METHODS: In the present study, healing of anastomosis in trinitrobenzene-sulfonic acid-induced colitis in rats was assessed by measuring the bursting pressure and bursting wall tension. RESULTS: On postoperative day 4, bursting pressure and bursting wall tension were significantly lower (P<0.001) in rats with colitis with or without anastomosis and normal colon with anastomosis, compared with normal colon without anastomosis. On postoperative day 7, bursting pressure and bursting wall tension of normal colon with anastomosis approached that of normal colon without anastomosis. However, bursting pressure and bursting wall tension of rats with colitis with or without anastomosis remained significantly lower (P<0.001) than the latter. Furthermore, unlike rats without colitis in which perforation occurred mostly at the anastomotic line, the bursting site in colitic rats was predominantly away from the anastomotic line. CONCLUSIONS: These results suggest that in surgery for inflammatory bowel disease, it is the adjoining inflamed bowel wall that is vulnerable to be perforated in response to increasing intraluminal pressure rather than the anastomosis that is braced by the sutures.     

Influence of intraperitoneal therapy with mitomycin C adsorbed on activated carbon on anastomotic and wound healing in rats

In an effort to prevent intraperitoneal dissemination of gastric carcinoma, local chemotherapy with mitomycin C adsorbed to activated carbon (MMC-CH) has been implemented. Results of clinical studies showed improved survival and a reduced systemic toxicity after the use of prophylactic treatment with MMC-CH. A significantly higher rate of intraperitoneal septic complications following MMC-CH therapy was found. The aim of this study was to assess whether intraperitoneal MMC-CH affects wound healing or healing of intestinal anastomoses. Standardized laparotomy was performed in 77 rats. The examinations were performed in 27 animals in the control group, 24 animals in the charcoal group, and 26 animals in the MMC-CH group. The animals and groups were distributed randomly. After an ileal anastomosis was performed, MMC-CH, charcoal, or sodium chloride 0.9% was administered intraperitoneally. After 10 days, collagen content as well as bursting strength/pressure of the fasciotomy and the anastomotic site was examined. Body weight and blood parameters analyzed included hemoglobin level, white blood cell count, platelet count, and total protein. Concerning body weight and hematology, no significant changes were observed. Three of 26 animals in the MMC-CH group, 2/24 in the charcoal group and 1/27 in the control group developed an anastomotic leakage. The bursting pressure of the anastomoses and the bursting strength of the fasciotomy as well as the relative collagen content did not differ significantly after treatment with charcoal or mitomycin C compared to the control group. Local inflammation consisting of charcoal-laden granulomas was detected histologically in the MMC-CH group and to a lesser extent in the charcoal group. In conclusion, no significant influence of intraperitoneal mitomycin C adsorbed on activated charcoal, in terms of its effect systemically or its effect on wound healing, could be demonstrated as a result of slow release. Histological changes seen with the use of activated charcoal suggest that perhaps a more ideal absorbable carrier should be sought.     

Enteral and intraluminal short-chain fatty acids improves ischemic left colonic anastomotic healing in the rat

BACKGROUND AND AIMS: This study assessed the effect of short-chain fatty acids (SCFAs) on the healing of ischemic colonic anastomosis and compared the enteral and intraluminal (transrectal) forms of SCFAs in the same study. MATERIAL AND METHODS: Left colonic ischemia was induced and a 1-cm left colon resection 2-4 cm above the peritoneal reflection was performed through a midline incision. In all, 160 rats were divided into eight groups: a control group, an ischemia group, a transrectal SCFAs group, an ischemia + transrectal SCFAs group, an enteral guar gum group, an ischemia + enteral guar gum group, an ischemia + enteral sham group, and a control + enteral sham group. The animals in each group were anesthetized again on day 4 or 7 after the operation for in vivo analytic procedures. Wound complications, intestinal obstructions, and anastomotic complications were recorded. Periperitoneal adhesions were graded. The strength of each anastomosis was assessed by measuring its bursting pressure. RESULTS: There were significantly more dense intra-abdominal adhesions in the ischemic group and ischemia + enteral sham group. Five animals in the ischemia group, six in the ischemia + enteral sham group, and one in each of the control and ischemia + transrectal SCFA groups developed anastomotic dehiscence. The median bursting pressures were significantly lower in the ischemic group and in the ischemia + enteral sham group on the 4 day and 7 days. CONCLUSION: Deleterious effects of ischemia on left colonic anastomotic healing were significantly prevented by the administration of either 7 days' pretreatment with enteral guar gum or the intraluminal instillation of SCFAs. There were no significant differences between enteral and intraluminal SCFA groups.     

Effect of hypercholesterolemia on experimental colonic anastomotic wound healing in rats

AIM: To evaluate the mechanical and biochemical parameters of colonic anastomotic healing in hypercholesterolemic rats. METHODS: Sixty rats were divided into two groups of 30 each according to their dietary regimens. The test group was fed with a high cholesterol-containing diet for two months while the control group had standard diet. These two groups were further divided into three subgroups consisting of ten rats each. After hypercholesterolemia was established, left colon resection and anastomosis were performed in both groups and samples from liver and abdominal aorta were taken to evaluate the systemic effects of hypercholesterolemia. Anastomotic wound healing, blow-out pressures and tissue hydroxyproline levels were evaluated. RESULTS: The test group had a significant weight gain in two months. Microscopic examination of the abdominal aorta revealed no atherosclerotic change in none of the groups, but liver tissue specimens showed significant steatosis in the test group. Tissue hydroxyproline levels and anastomotic blow-out pressures were significantly lower in the test group than in the controls. CONCLUSION: Hypercholesterolemia not only increases hydroxyproline levels and blow-out pressures but also worsens anastomotic wound healing.     

Integrated approach to colorectal anastomotic leakage: Communication,infection and healing disturbances

Colorectal anastomotic leakage(CAL) remains a major complication after colorectal surgery. Despite all efforts during the last decades, the incidence of CAL has not decreased. In this review, we summarize the available strategies regarding prevention, prediction and intervention of CAL and categorize them into three categories: communication, infection and healing disturbances. These three major factors actively interact during the onset of CAL. We aim to provide an integrated approach to CAL based on its etiology. The intraoperative air leak test, intraoperative endoscopy, radiological examinations and stoma construction mainly aim to detect and to prevent communication between the intra- and extra-luminal content. Other strategies including postoperative drainage, antibiotics, and infectious-parameter evaluation are intended to detect and prevent anastomotic or peritoneal infection. Most currently available interventions for CAL focus on the control of communication and infection, while strategies targeting the healing disturbances such as lifestyle changes, oxygen therapy and evaluation of metabolic biomarkers still lack wide clinical application. This simplified categorization may contribute to an integrated understanding of CAL. We strongly believe that this integrated approach should be taken into consideration during clinical practice. An integrated approach to CAL could contribute to a better understanding of the etiology of CAL and eventually better patient outcome.     

Microscopic analysis of anastomotic healing in the intestine of normal and diabetic rats

PURPOSE: The mechanisms that cause diabetes to impair the development of anastomotic strength in the intestine are poorly understood. We investigated whether short-term uncontrolled diabetes causes alterations in microscopic aspects of anastomoses from the ileum and colon. METHODS: Eighteen Wistar rats were rendered diabetic one week before operation by intravenous streptozotocin injection (50 mg/kg), resulting in nonfasting blood glucose levels of approximately 20 mmol/l. Another 18 age-matched rats were used as controls with a normal blood glucose range of 5 to 7 mmol/l. All rats underwent resection and anastomosis of both the ileum and colon. Animals were killed at one, three, or seven days after operation. Cellular and architectural parameters of anastomotic healing were scored in hematoxylin and eosin-stained sections. Anastomotic collagen content was analyzed by image analysis in picrosirius red-stained sections. RESULTS: Anastomotic necrosis, edema, and epithelial recovery were not affected by diabetes. In diabetic rats, the number of polymorphonuclear cells and macrophages was significantly (P = 0.025 and 0.0002, respectively) increased in ileal anastomoses one and three days after operation. In colonic anastomoses, the number of polymorphonuclear cells was increased at one (P = 0.001) and seven (P = 0.014) days after operation. Repair of the submucosal-muscular layer in colonic anastomoses from diabetic rats was impaired seven days after surgery (P = 0.0071), but in ileal anastomoses no difference was found. In the anastomotic area, collagen deposition at postoperative Days 1, 3, and 7 remained unaffected by diabetes. CONCLUSION: Experimental diabetes leads to alterations in cellular components involved in the early phase of repair of intestinal anastomoses but not to a reduced accumulation of wound collagen.     

The effect of long-term supplementation of vitamin C on pulpal blood flow in streptozotocin-induced diabetic rats

To examine the effect of vitamin C on blood flow in diabetic dental pulp, the animal model of streptozotocin (STZ)-induced diabetic rats (i.v. injection of STZ 55 mg/kg BW) was used. Male Sprague-Dawley rats weighing 200-250 g were divided into 3 groups: non-diabetes (CON), diabetes (STZ), and diabetes supplemented by vitamin C (STZ+Vit C). Vitamin C was supplemented by drinking water (1 g/l). At 12 weeks (wks) and 24 wks after the STZ injection, the laser Doppler flow-meter (Model ALF 21, USA) was used to measure pulpal blood flow (PBF) while the animals were anesthetized with sodium pentobarbital (50 mg/kg BW). The experimental results showed that at 12 and 24 wks after the STZ injection, hyperglycemia hypertension and loss of body weight were significantly developed. Simultaneously, decreased plasma vitamin C level was demonstrated significantly in STZ rats. The reduction of pulpal blood flow (PBF) in the lower incisors was observed in STZ rats at both monitored time points. Interestingly, the supplementation of vitamin C for 24 wks restored PBF. In conclusion, the present study demonstrated that long-term supplementation of vitamin C, a natural antioxidant, could markedly prevent the diabetic-induced reduction in PBF.     

Dietary vitamin B6 supplementation prevents ethanol-induced hypertension in rats

BACKGROUND AND AIMS: All known pathways of ethanol metabolism result in the production of acetaldehyde, a highly reactive compound. Acetaldehyde has been shown to deplete vitamin B6 in chronic alcoholics. It also binds with sulfhydryl groups of membrane proteins, altering membrane Ca2+ channels and increasing vascular cytosolic free calcium, peripheral vascular resistance and blood pressure. The aldehyde-binding thiol compound, N-acetyl cysteine, attenuates elevated blood pressure and associated adverse changes in ethanol-induced hypertensive rats. Vitamin B6 supplementation increases the level of endogenous cysteine. Aim of this work was thus to investigate whether a dietary supplementation of vitamin B6 can prevent ethanol-induced hypertension and associated changes in Wistar-Kyoto (WKY) rats. METHODS AND RESULTS: Starting at 7 weeks of age, WKY rats were divided into three groups of six animals each. The control group received a normal vitamin B6 diet (regular chow) and normal drinking water, the ethanol group, the same diet plus 1% ethanol in the drinking water, and the ethanol + vitamin B6 group a high vitamin B6 diet (20 times normal diet) and 1% ethanol in the drinking water. After 14 weeks, systolic blood pressure, platelet [Ca2+]i and kidney and aortic aldehyde conjugate levels were significantly higher in the ethanol group. These rats also showed smooth muscle cell hyperplasia in the small arteries and arterioles of the kidneys. Dietary vitamin B6 supplementation prevented these changes. CONCLUSIONS: Dietary vitamin B6 supplementation prevented ethanol-induced hypertension and associated changes in WKY rats by normalizing tissue aldehyde conjugate levels.     

Antioxidant vitamin C improves endothelial function in obstructive sleep apnea

RATIONALE: Obstructive sleep apnea (OSA) is associated with oxidative stress, endothelial dysfunction, and increased cardiovascular morbidity and mortality. OBJECTIVE: We tested the hypothesis that endothelial dysfunction in patients with OSA is linked to oxidative stress. METHODS: In the present study, we measured flow-mediated dilation (FMD) of the brachial artery by ultrasound in 10 otherwise healthy, untreated patients with OSA and 10 age-and sex-matched control subjects without sleep-disordered breathing before and after intravenous injection of the antioxidant vitamin C. The investigator performing the FMD measurements was blinded to the status of the patients. RESULTS: When compared with control subjects, baseline FMD was significantly reduced in the patients with OSA. After intravenous injection of 0.5 g vitamin C, vasoreactivity remained unchanged in the control subjects. In the patients with OSA, ascorbate led to an increase in FMD to a level comparable to that observed in the control group. CONCLUSION: The reduced endothelial-dependent vasodilation in untreated patients with OSA acutely improves by the free radical scavenger vitamin C. These results are in favor of oxidative stress being responsible for the endothelial dysfunction in OSA. Antioxidant strategies should be explored for the treatment of OSA-related cardiovascular disease.     

Intestinal anastomotic healing in the absence of suture material: an experimental study in rats

In order to investigate the influence of sutures on intestinal anastomotic healing, 48 rats underwent both ileal and colonic resection. In 24 rats all intestinal sutures were removed 30 min after anastomotic construction (group 1), while in the remaining animals (group 2) the sutures were left in place. Bursting pressures and collagen (hydroxyproline) levels in anastomotic segments were measured 1, 3, and 7 days after operation. Two lethal ileal dehiscences and 9 anastomotic abscesses (5 ileal and 4 colonic) occurred in group 1, while in group 2 there were 3 ileal anastomotic abscesses. On the first day after operation, bursting pressures were significantly lower in sutureless ileal and colonic than in sutured anastomoses. During the post-operative course, changes in collagen concentrations in ileal and colonic segments did not differ between the groups. Thus, sutures are only essential in providing anastomotic strength during the immediate post-operative period, but do not seem to affect post-operative collagen metabolism.

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Résumé Dans le but d'étudier l'influence des sutures sur la cicatrisation des anastomoses intestinales, 48 rats ont subi une résection à la fois iléale et colique. 24 rats ont eu une résection de leur suture intestinale 30 minutes après la réalisation de l'anastomose, tandis que chez les animaux restants les sutures étaient laissé en place. 3 à 7 jours après l'opération la pression de rupture et les taux de collagène dans les segments anastomotiques ont été mesurés. Des fistules iléales mortelles et 9 abcés anastomotiques (5 iléaux et 4 coliques) sont survenus dans le groupe expimental contre trois abcés anastomotiques dans le groupe de contrôle. La pression de rupture était significativement plus basse au niveau des anastomoses à la fois iléales et coliques sans suture mais seulement le premier jour après l'opération. Les modifications postopératoires des concentrations de collagène dans les segments iléaux ou coliques ne différaient pas entre les deux groupes. Ainsi les sutures ont seulement un rôle essentiel en renforçant l'anastomose durant la période post-opératoire tout à fait initiale mais ne semblent pas affecter le métabolisme post-opératoire du collagène.

     

Long-term effects of oral vitamin C supplementation on the endothelial dysfunction in the iris microvessels of diabetic rats

The current study was aimed to investigate effects of long-term supplementation of vitamin C on the iris microcirculation in streptozotocin (STZ)-induced diabetic rats. Diabetes was induced in male Wistar-Furth rats by intravenous injection of STZ (55 mg/kg b.w.). The rats were divided into three groups: control rats (CON), STZ-induced diabetic rats (STZ), and STZ rats supplemented with vitamin C (STZ-vitC). For supplementation of vitamin C, ascorbic acid (1 g/l) was added into the drinking water. The experiments were performed at different periods (8, 12, 24 and 36 weeks) after injection of STZ. Blood glucose, tissue lipid peroxidation and plasma vitamin C were measured. To examine the endothelial function, leukocyte adhesion to the venular endothelium was evaluated in the iris post-capillaries by means of counting the number of leukocytes labeled with rhodamine 6G. Blood flow perfusion in the iris was monitored using a laser Doppler flow meter. In the STZ rats, hyperglycemia was induced with an increase in HbA(1c) and lipid peroxidation but with a decrease in the plasma vitamin C level which improved by vitamin C supplementation. The number of adherent leukocytes increased significantly, associated with reduction in the iris blood flow perfusion, at 8, 12, 24 and 36 weeks after injection of STZ. In the STZ-vitC rats, the iris blood flow perfusion was significantly increased in comparison with the STZ rats, while the leukocyte adhesion was decreased at 24 and 36 weeks. The statistical analysis shows that the leukocyte adhesion decreased with increase in the iris blood flow perfusion in STZ and STZ-vitC rats. In conclusion, vitamin supplementation suppressed leukocyte adhesion and thus endothelial dysfunction, associated with increase in iris blood flow perfusion in diabetes. The antioxidant vitamin C may be a therapeutic agent for preventing diabetic retinopathy.