Background: Adhesions induced by biomaterials experimentally implanted in the abdominal cavity are basically studied by primary repair of different abdominal wall defects or by the correction of incisional hernias previously performed with no precise definition of the most appropriate model. Aim: To describe the adhesions which occur after the development of incisional hernias, before the prosthesis implantation, in an experimental model to study the changes induced by different meshes. Methods: Incisional hernias were performed in 10 rats with hernia orifices of standardized dimensions, obtained by the median incision of the abdominal wall and eversion of the defect edges. Ten days after the procedure adhesions of abdominal structures were found when hernias were repaired with different meshes. Results: The results showed hernia sac well defined in all rats ten days after the initial procedure. Adhesions of the greater omentum occurred in five animals of which two also showed adhesions of small bowel loops besides the omentum, and another two showed liver adhesions as well as the greater omentum, numbers with statistical significance by Student's t test (p<0.05). Conclusion: Although it reproduces the real clinical situation, the choice of experimental model of incisional hernia repair previously induced implies important adhesions, with possible repercussions in the evaluation of the second operation, when different implants of synthetic materials are used.

There was no statistically significant increase in the spleen volume after partial ligation of the portal vein when comparing the calculated volume in the first operation to the volume found at reoperation. There was no difference when comparing the spleen volumes of the animals reoperated after 15 days and the ones reoperated after 30 days.

BackgroundPartial portal vein ligation causes an increase in portal pressure that remains stable even after the appearance of collateral circulation, with functional adaptation to prolonged decrease in portal blood flow.AimTo assess whether different constriction rates produced by partial ligation of the vein interfere with the results of this experimental model in rats.MethodsThree groups of five rats each were used; in group 1 (sham-operated), dissection and measurement of portal vein diameters were performed. Portal hypertension was induced by partial portal vein ligation, reducing its size to 0.9 mm in the remaining 10 animals, regardless of the initial diameter of the veins. Five animals with portal hypertension (group 2) underwent reoperation after 15 days and the rats in group 3 after 30 days. The calculation of the constriction rate was performed using a specific mathematical formula (1 - π r 2 / π R2) x 100% and the statistical analysis with the Student t test.ResultsThe initial diameter of the animal's portal vein was 2.06 mm, with an average constriction rate of the 55.88%; although the diameter of the veins and the constriction rate in group 2 were lower than in group 3 (2.06 mm - 55,25% and 2.08 mm - 56.51%, respectively), portal hypertension was induced in all rats and no significant macroscopic differences were found between the animals that were reoperated after 15 days and after 30 days respectively, being the shorter period considered enough for the evaluation. Comparing the initial diameter of the vein and the rate of constriction performed in groups 2 and 3, no statistic significance was found (p>0.05).ConclusionPre-hepatic portal hypertension in rat can be induced by the reduction of the portal vein diameter to 0.9 mm, regardless the initial diameter of the vein and the vessel constriction rate.

BackgroundThe calculation of the volume ratio between the hernia sac and the abdominal cavity of incisional hernias is based on tomographic sections as well as the mathematical formula of the volume of the ellipsoid, which allows determining whether this is a giant hernia or there is a "loss of domain". As the images used are not exact geometric figures, the study of the volume of two solid organs of Wistar rats was performed to validate these calculations.AimTo correlate two methods for determining the volume of the kidney and spleen of rats, comparing a direct method of observation of the volume with the mathematical calculation of this value.MethodsThe volume of left kidney, geometrically more regular, and spleen, with its peculiar shape, of ten animals was established in cubic centimeters after complete immersion in water with the aid of a beaker graduated in millimeters. These values ​​were compared with those obtained by calculating the same volume with a specific mathematical formula: V = 4/3 × π × (r1 x r2 x r3). Data were compared and statistically analyzed by Student's t test. RESULTS: Although the average volume obtained was higher through the direct method (1.13 cm3 for the left kidney and 0.71 cm3 for the spleen) than the values ​​calculated with the mathematical formula (0.81 cm3 and 0.54 cm3), there were no statistically significant differences between the values ​​found for the two organs (p>0.05).ConclusionThere was adequate correlation between the direct calculation of the volume of the kidney and spleen with the result of mathematical calculation of these values ​​in the animals' studies.

BackgroundThe negative result of a research does not always indicate failure, and when the data do not permit a proper conclusion, or are contrary to the initial project, should not simply be discarded and archived.AimTo report failure after performing experimental model of liver ischemia and reperfusion normothermic, continuous or intermittent, in small animals aiming at the study of biochemical and histological parameters after postoperative recovery.MethodsFifteen Wistar rats were divided into three groups of five animals each; all underwent surgery, the abdomen was sutured after the proposed procedures for each group and the animals were observed for 6 h or until they died, and then were reoperated. In Group 1, control (sham-operated): dissection of the hepatic hilum was performed; in Group 2: clamping of the hepatic hilum for 30 m; in Group 3: clamping of the hepatic hilum for 15 m, reperfusion for 5 m and another 15 m of clamping. Data from Groups 2 and 3 were compared with Student's t test.ResultsAll animals of Group 1 survived for 6 h. Two animals in Group 2 died before the 6 h needed to validate the experiment; two did not recover from anesthesia and one survived until the end. In Group 3, four animals died before the 6 h established and one of them survived the required time. Only one animal in Group 2 and one in Group 3 survived and were able to accomplish the study. There was no statistical significance when the results of Groups 2 and 3 were compared (p>0.05).ConclusionThe death of six animals before the necessary period of observation turned the initial proposal of the experiment unfeasible.