The histogenesis of DMH-induced colonic carcinoma in rats

Twenty-one Donryu male rats of six weeks old were injected with 1,2-dimethyl-hydrazine hydrochloride (DMH), once a week, for 4 to 20 weeks, and sacrificed at intervals of two weeks since a lapse of four weeks after the commencement of the injections. The DMH induced 320 atypia lesions, from 0.03 through 20 mm in size, of grade II or higher. The rate of benign lesions was higher in the group receiving less than 20 injections than in the group of 20 injections of DMH, while in the latter group, the rates of the benign, borderline and malignant lesions were stable, suggesting that benign lesions mainly develop in the earlier period of the DMH treatment, and thereafter various grades of lesions develop at a constant rate. All the benign lesions were less than 1 mm in size, and all lesions greater than 1 mm were malignant. In addition, the size of the lesion was significantly greater when it was occupied by malignant crypts in a greater rate. These results indicate that the benign lesions become cancerous before they reach a certain size (adenoma-carcinoma sequence). Twenty-seven minute lesions (less than 1 mm) were mixed lesions of malignant and benign atypia, suggesting that the adenoma-carcinoma sequence is elicited in any size of lesion. On the other hand, there were 41 minute malignant-only lesions, which constituted 27.7% of the overall minute lesions and included three "single crypt" cancers. In addition, malignant-only lesions were smaller when compared to the malignant-dominant mixed lesions. These results indicate that about 30% of colon cancers develop de-novo.     

Angiography in colonic carcinoma

Angiography of the mesenteric arteries was performed in 17 patients with adenocarcinoma of the colon and rectum. At angiography, the marginal artery was encased in 13 patients and 10 of these were surgically unresectable while three could be resected radically. Encasement of the mesenteric arterial branches was found in seven of 11 unresectable tumors and in two of five resectable tumors. The resectability of colonic carcinoma cannot be established by means of angiography but, in two patients with recurrent colonic carcinoma, barium-enema examinations were negative, while infiltrated vessels were demonstrated by angiography and the carcinomas were verified at surgery. Four patients received intra-arterial chemotheraphy with mitomycin C. In one of these, a slight decrease in tumor size was noted, while in the others no change was noted.     

The prophylactic use of antibiotics in surgery for colonic carcinoma

Summary Evaluation of the efficacy of the neomycin-erythromycin combination as prophylaxis before operation for carcinoma of the colon (3 g of each the day preoperatively, plus mechanical cleansing) was carried out in a study of 28 patients for whom primary operations for colonic carcinoma were performed January through June 1973; 11 others received other preparation. Mean age of the 28 patients was 68 years; 20 were men. Thirteen had sigmoid carcinomas; 23 lesions were resectable, using no-touch isolation technique. There was no postoperative infectious complication. Of the other 11 patients, two had significant infections postoperatively. Although operability, age, concurrent medical problems, and surgical technique probably influence postoperative sepsis, the neomycin-erythromycin combination appears satisfactory for prevention of infection after operations for colonic carcinoma. Read at the American Cancer Society's Second National Conference on Cancer of the Colon and Rectum, Miami, Florida, September 29, 1973.     

Transplantable colonic adenocarcinomas in rats

The induction of colonic adenocarcinoma using two different regimens of dimethylhydrazine (DMH) in Fischer F344 rats is described. Rats receiving 20 mg/kg of DMH per week for 20 weeks developed primary tumors with metastases, whereas rats receiving the same weekly dose for 15 weeks developed primary tumors only. The most common route of metastases was transcelomic which often was associated with ascites. The epithelial origin of malignant ascites cells was confirmed by immunofluorescent staining with antidesmosomal antibodies and demonstration of desmosomes by electron microscopy. When transplanted into syngeneic rats, the cells of the malignant ascites resulted in the development of adenocarcinomatous metastases.     

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.     

Studies of colonic carcinoma antigens

Extracts of human colonic adenocarcinomata were made with perchloric acid and shown to contain antigens which were not present in pooled samples of normal colonic mucosa or in healthy colonic mucosa from patients providing the tumours. Antisera prepared against the tumour extracts gave two precipitin lines on immunodiffusion, and antiserum prepared in Montreal according to the methods devised by Gold and Freedman (1965a and b) also gave two lines of precipitation when tested against some of these extracts; one of these precipitin lines gave a reaction of identity with that given by the antiserum produced here. The results suggest that perchloric acid may extract two antigens from colonic carcinomata.     

Ultrasonic detection of colonic carcinoma in emergency

The role of ultrasound scanning in the diagnosis of cancer of the colon under emergency conditions such as intestinal obstruction, perforation or, more rarely, heavy colonic bleeding, is discussed. In any case, ultrasound scanning can quickly and rationally indicate choices for further assessment when possible. Characteristic ultrasonic images are described, and possible differential diagnoses are discussed briefly. The method seems significantly sensitive, although nonspecific, as it can give analogous images in cases of inflammatory pseudo-tumors, Crohn's disease, and adult intussusception.     

The effects of intestinal ischemia on colonic motility in conscious rats

Background  The present study aimed to examine whether and how colonic motility is affected by mild ischemia-induced intestinal injury in conscious rats through in vivo monitoring of colonic contractions, specifically with regard to the interstitial cells of Cajal (ICC) and the effect of nitric oxide (NO). Methods  Using miniature strain-gauge transducers, colonic motility with or without ischemia was recorded in conscious rats on the 4th, 7th, and 14th days after surgery. Histological examination for c-kit-positive cells was performed. Results  In control nonischemic rats, the number and duration of contractions (NC and DC, respectively) decreased gradually, but the mean amplitude of contractions (MC) and motility index (MI) did not change. On the 7th day, the NC in the ischemic group increased significantly when compared with that in the control group (P = 0.037). The DC in the ischemic group was lower than that in the control group; the difference was significant on the 4th day (P = 0.008). The MIs in the ischemic group were lower than those in the control group. In both groups, administration of NGnitro-l-arginine methyl ester on the 7th day increased only the resting cecal motility. Pathological examinations revealed c-kit-positive cells in both groups. Conclusions  Changes such as increased NC with shortened DC accompanied with decreased MI must have occurred at the ischemic site and might have been induced by an ischemic event. However, there exists a possibility that ICC and NO do not play a role in mild ischemia-induced dysmotility.     

Effects of partial colonic resection in rats

In order to study the effects of partial colectomy, 30 rats Wistar were divided into three groups: GI and GII had the cecun and the ileo cecal valve resected and proximal colectomy was performed in GI and distal in GII. GIII had distal colectomy without cecum resection. The length of the remain colon was of 5 cm in all groups. Colostomy was performed in GI, GII and GIII. Parameters evaluated: body weight, fecal composition concerning to water, lipids and proteins on preoperative time and on the 10th, 20th, 30th, 40th, 50th and 60th days of postoperative time. All statistical tests were conducted at a 5% two-sided risk level. The evaluation was made by analysis of variance techniques. CONCLUSIONS: Concerning to body weight, there is no significant difference on the late postoperative time in any group or when comparing the three groups on this same period. On late postoperative time, GI and GII had a large amount of fecal water, lipids and proteins when compared to the preoperative time and to GIII. On the 60th day there's no significant difference on the quantity of fecal water when comparing the three groups and the same occurs on the 50th day when considering the quantity of fecal proteins.     

Laparoscopic colectomy for colonic carcinoma

Aim

The aim of this study is to present our experience with the laparoscopic treatment approach for colonic carcinoma.

Patients and methods

Between 2005 and 2010, laparoscopic colectomy was performed in 13 patients; 9 patients underwent laparoscopic right hemicolectomy, 3 sigmoidectomy and 1 patient underwent laparoscopic caecectomy.

Results

With regards to the right hemicolectomies, the average operative time was 168 min and the average hospital stay 5.3 days. In patients who underwent laparoscopic sigmoidectomy, the average operative time was 176 min, while the average hospital stay was 10.2 days. Finally, the laparoscopic caecectomy was performed in 85 min. There was one conversion (7.7%) to an open procedure, as well as one case (7.7%) of anastomotic leakage, which was treated with re-laparotomy and a Hartmann’s procedure. Up to today, all patients remain healthy with no signs of tumor recurrence.

Conclusion

Laparoscopic colectomy for cancer, in the hands of an experienced laparoscopic surgeon, is a safe and efficient procedure.

     

Aldosterone in colonic potassium adaptation in rats

The influence of adrenalectomy and administration of aldosterone on potassium secretion by colonic epithelium was studied in vivo in rats, particularly in relation to potassium adaptation (induced by feeding a potassium-rich diet) and the response to acute i.v. administration of a potassium load. Adrenalectomy (rats maintained on dexamethasone and saline) impaired the development of potassium adaptation or considerably reduced it if the rats had been previously adapted. The partial adaptation observed in the adrenalectomized rats may be related to the increased plasma potassium concentration developed when these rats received the potassium-rich diet. Within 2 h of acute aldosterone administration, the response of the potassium secretion rate to acute potassium loading in adrenalectomized rats was significantly improved. When aldosterone (2 micrograms/day per 100 g body weight, given by osmotic minipump) was added to the replacement treatment, the plasma concentration of potassium was similar to that of the intact rats, and both potassium adaptation and the response to the acute potassium load were completely restored. Transepithelial potential difference and sodium transport were not stimulated, being similar to the values in intact rats. Considerable changes in potassium secretion induced by acute potassium loading did not significantly affect sodium transport. The findings suggest that the sodium and potassium epithelial pathways are, to a large extent, independently influenced by aldosterone. Aldosterone appears to be essential for complete adaptation and, in a relatively low dose, can completely restore potassium adaptation and the response to acute potassium loads in adrenalectomized rats.     

Surveillance for colonic carcinoma in ulcerative colitis

To evaluate the efficacy of surveillance colonoscopy with biopsy for the detection of high-grade dysplasia (HGD) or colonic carcinoma in patients with chronic ulcerative colitis, we undertook a retrospective review of 248 patients who underwent 370 examinations (mean duration of disease 12 yr). High-grade dysplasia or carcinoma was found in 24 examinations in 16 patients, with a mean duration of disease of 16 yr. There were 15 patients with HGD. Nine patients had HGD alone, 6 had HGD and carcinoma, and 1 had carcinoma without HGD. The overall incidence of HGD was 6%. Dysplasia-associated lesions or mass were the most consistent indicators of carcinoma, the combination being present in four instances. Of the 7 patients with cancer, 6 were recognized by colonoscopy, and 1 patient with negative visual endoscopic findings was discovered using surveillance biopsies. The conclusions of this study are that dysplasia is a reliable histopathologic marker and correlates with the presence of cancer in chronic ulcerative colitis; the absence of dysplasia correlates with the absence of cancer. The presence of dysplasia-associated lesions or mass with HGD is the strongest indication for operation. This study supports the use of surveillance colonoscopy in managing high-risk ulcerative colitis patients.