Leonardo C. Duraes

Effects of carbon dioxide pneumoperitoneum on hepatic and renal morphology of rats after segmental colectomy and colonic anastomosis

PURPOSE To evaluate the effects of increased intraperitoneal pressure caused by carbon dioxide pneumoperitoneum on the hepatic and renal morphology of rats. METHODS Fifty-four adult male rats were randomly divided into three groups (P, PP and C) after anesthesia: P - in 18 animals, pneumoperitoneum was established for 30 minutes immediately before laparotomy; PP - in 18 animals, pneumoperitoneum was established for 60 minutes divided into 30 immediately before laparotomy and 30 after abdominal closure; control group (C) - 18 animals underwent laparotomy without pneumoperitoneum induction. The pneumoperitoneum was maintained at a pressure of 5 mm Hg. Nine animals in each group were killed on the 3(rd) and 7(th) postoperative days, when kidney and liver samples were collected for morphological analysis. The liver specimens were stained with hematoxylin and eosin (HE), and the kidney specimens, with HE and von Kossa. Blinded examiners analyzed the slides. RESULTS No changes in renal morphology were found. Liver samples showed histological signs of degeneration in animals in the pneumoperitoneum groups killed on the 7(th) postoperative day (p=0.029). CONCLUSION The CO(2) pneumoperitoneum did not affect renal morphology but caused hydropic degeneration in the liver of animals killed on the 7(th) postoperative day.

NPTX2 is associated with neoadjuvant therapy response in rectal cancer

BACKGROUND Neoadjuvant chemoradiation (CRT) is recommended for locally advanced rectal cancer. Tumor response varies from pathologic complete response (pCR) to no tumor regression. The mechanisms behind CRT resistance remain undefined. In our previously generated complementary DNA microarrays of pretreatment biopsies from rectal cancer patients, neuronal pentraxin 2 (NPTX2) expression discriminated patients with pCR from those with residual tumor. As tumor response is prognostic for survival, we sought to evaluate the clinical relevance of NPTX2 in rectal cancer. MATERIALS AND METHODS Real-time quantitative polymerase chain reaction was used to evaluate NPTX2 messenger RNA expression in individual rectal cancers before CRT. Tumors with NPTX2 expression <50% of normal rectum were defined as NPTX2-low and those with >50% were defined as NPTX2-high. NPTX2 levels were compared to response to therapy and oncologic outcomes using Mann-Whitney, Kruskal-Wallis, chi-square, and Mantel-Cox (log-rank) tests, as appropriate. RESULTS Rectal cancers from 40 patients were included. The mean patient age was 56.8 years, and 30% were female. pCR was achieved in eight of 40 patients (20%). In these patients, messenger RNA NPTX2 levels were significantly decreased compared to those with residual cancer (fold change 30.4, P = 0.017). Patients with NPTX2-low tumors (n = 13) achieved improved response to treatment (P = 0.012 versus NPXT2-high tumors), with 38.5% and 46.1% of patients achieving complete or moderate response, respectively. Of patients with NPTX2-high tumors (n = 27), 11.1% and 18.5% achieved complete or moderate response, respectively. No recurrence or death was recorded in patients with NPTX2-low tumors, reflecting more favorable disease-free survival (P = 0.045). CONCLUSIONS Decreased NPTX2 expression in rectal adenocarcinomas is associated with improved response to CRT and improved prognosis. Further studies to validate these results and elucidate the biological role of NPTX2 in rectal cancer are needed.

Correlation between bursting pressure and breaking strength in colonic anastomosis

PURPOSE To investigate the correlation between bursting pressure and breaking strength on the 7th postoperative day following left colonic anastomosis in rats. METHODS Seventy rats were randomly divided into seven groups of ten animals each. All of the animals underwent segmental resection of the left colon and end-to-end anastomosis. The animals in groups I to VI underwent surgical laparoscopies with pneumoperitoneums using carbon dioxide or helium at pressures of 5, 12 or 20 mmHg. In Group VII, open laparotomy was performed. The animals were reoperated on postoperative day 7 to measure the bursting pressure and the breaking strength of the anastomosis. RESULTS The anastomosis bursting pressure in 70 animals was 193.10±55.56 mmHg. There was no significant difference between the groups (p=0.786). The breaking strength of the anastomosis was 0.26±0.12 N. There was no significant difference between the groups (p=0.356). Pearsons correlation test showed a low correlation (r=0.231) lacking statistical significance (p=0.054). CONCLUSION There was no correlation between the bursting pressure and breaking strength of left colonic anastomoses in rats on the 7th postoperative day.

A new proposal for laparoscopic left colectomy in a rat model

PURPOSE To evaluate the feasibility and safety of a new technique for laparoscopic segmental colectomy and primary anastomosis in the left colon of rats. METHODS Thirty rats were randomly assigned to three groups of ten animals each. All animals underwent segmental resection of the left colon and end-to-end anastomosis. In Group I, the animals underwent laparoscopic surgery with carbon dioxide pneumoperitoneum at a pressure of 5 mmHg. In Group II, the animals underwent pneumoperitoneum with carbon dioxide at a pressure of 12 mmHg. In Group III, the control group, the animals underwent open surgery. All animals were reopened on the 7th postoperative day and were evaluated for peritonitis, abscesses, anastomotic dehiscence and bowel obstruction, and the anastomosis bursting pressure was measured. RESULTS No obstructions, peritonitis or abscesses were found in any of the animals. An animal in Group I exhibited a blocked anastomosis leakage. The average anastomosis bursting pressure in the 30 animals was 187.02 ± 68.35 mmHg. There was no significant difference in the anastomosis bursting pressure among the groups (p = 0.503) CONCLUSION The laparoscopic experimental model was feasible and safe for segmental colectomy and anastomosis of the left colon in rats.

What are the consequences of enlarging the extraction site to exteriorize a large specimen during laparoscopic surgery for Crohn's enteritis?

The implications of extraction site enlargement for the removal of large specimens during laparoscopic surgery for Crohns disease have not been clearly described; such a description is the aim of this study.

Human Papilloma Virus and Anal Cancer

The most common anal cancer is the squamous cell carcinoma. It may be keratinized or nonkeratinized. Adenocarcinoma may occur, however, it resembles the lower rectal cancer and should follow its principles of treatment. (Nivatvongs, 2006) According to the World Health Organization (WHO), approximately 80% of tumors of the anal canal are squamous cell type and these are divided in squamous cell carcinoma tumors, basaloid (cloacogenic) and mucoepidermoid. In this classification of tumors of the anal region, WHO considers the anal verge, anal canal, the anal transition zone and the rectal type mucosae of the anal canal. Therefore, other histological types of tumors can arise in the anal canal. Adenocarcinomas may originate in the rectal type mucosae in the anal canal and in the path of a long evolution anal fistula or in the epithelium of the anal glands. Other tumors may be lymphoma, melanoma, Kaposis sarcoma, Bowens disease and Pagets disease. (Table 1)

Evaluation of the effects of carbon dioxide pneumoperitoneum on abdominal wall wound healing in rats undergoing segmental resection and anastomosis of the left colon

PURPOSE To evaluate the influence of carbon dioxide pneumoperitoneum on abdominal wall wound healing in rats. METHODS Eighty rats underwent laparotomy, segmental left colon resection, and anastomosis. The animals were divided into three experimental groups and one control group: EI = pneumoperitoneum for 30 minutes before laparotomy (n=20); EII = pneumoperitoneum for 30 minutes after abdominal closure (n=20); EIII = pneumoperitoneum for 30 minutes before laparotomy and 30 minutes after abdominal closure (n=20); C = control group, without pneumoperitoneum (n=20). In each group, 10 animals were killed 7 days and 10 animals 14 days postoperatively. A segment of the abdominal wall was resected and subjected to tensile strength testing. Another segment of abdominal muscle was used for histopathological analysis; the specimens were fixed in formalin and stained with hematoxylin and eosin. RESULTS There were no differences in histopathology and tensile strength values among animals in the experimental and control groups 7 or 14 days after surgery. CONCLUSION Under the present experimental conditions, carbon dioxide pneumoperitoneum did not interfere with abdominal wall wound healing.