Metastatic potential of cloned murine melanoma cells transfected with activated c-Ha-ras

We sought to determine whether the transfection of tumorigenic but not metastatic cells with the activated c-Ha-ras oncogene was invariably associated with acquisition of the metastatic phenotype. Three clonally derived lines of the K-1735 murine melanoma, characterized as nonmetastatic or poorly metastatic, were transfected with plasmids containing the 6.6-kilobase BamHI fragment of the mutant human c-Ha-ras gene and the neo gene, that confers resistance to neomycin (pSV2neoEJ). Cells transfected with pSV2neo, a plasmid containing the neo gene, served as controls for the procedure of Polybrene-mediated transfection. All cell lines were injected into syngeneic C3H/HeN and into athymic mice, and the results were compared with those produced by highly metastatic K-1735 M-2 cells. Although the pSV2neoEJ-transfected cells produced more rapidly growing s.c. tumors than the control cell lines did, the incidence of spontaneous metastasis was not increased. Following i.v. inoculation, the c-Ha-ras transfectants were retained in lung vasculature in greater proportions than pSV2neo counterpart transfectants were. The c-Ha-ras transfectants also produced significantly more lung tumor colonies, which grew faster than the few lung tumor colonies in mice given injections of control melanoma cells. We concluded that transfection of the activated c-Ha-ras oncogene into nonmetastatic K-1735 melanoma cells leads to accelerated tumor growth in vivo and can confer the ability to form lung colonies after i.v. injection but not the ability to metastasize from a primary s.c. tumor.

Development of an animal model to study the biology of recurrent colorectal cancer originating from mesenteric lymph system metastases

We developed an animal model to study the biology and therapy of local-regional recurrent colorectal cancer. Syngeneic tumor cells or human colon carcinoma cells, respectively, were injected into the lymphoid follicle of the cecum of conventional mice or athymic nude mice. The cecum was resected (at a distant site) at various time points after the injection. Recurrent disease at the site of resection and in regional mesenteric lymph nodes was found in most of the injected mice, even in those whose cecum was resected 10 min after injection. The injection of tumor cells into the lymphoid follicle of the cecum introduces tumor cells into the lymph system of the cecum and the draining mesenteric lymph nodes, and these few cells, which cannot be detected at the time of operation, are the source of recurrent disease. This new animal model should allow us to study the biology and therapy of local and regional colorectal cancer.

Systemic immunity against a murine colon tumor (CT-26) produced by immunization with syngeneic cells expressing a transfected viral gene product

We have previously shown that CT-26 tumor cells expressing the transfected hemagglutination antigen of influenza virus elicit an immune response in syngeneic hosts that is cross-protective against an s.c. challenge with non-transfected parental cells. Since CT-26 is a murine colorectal carcinoma we sought to determine whether the same immuno-protective effect could be achieved after a challenge with parent tumor cells injected into the usual sites of colon tumor growth and metastasis. We now show that the protection afforded by this immunization protocol is systemic and that animals can be protected against tumor growth in the cecum, lymphatics of the mesentery, liver and lung.

The predictive role of delayed cutaneous hypersensitivity testing in postoperative complications

Ten parameters, including delayed cutaneous hypersensitivity testing (DCH), were evaluated with regard to their predictive value in instances of postoperative septic complications. In 302 patients undergoing surgical treatment, 45 complications, including wound infection, abscess, pneumonia and sepsis, were seen postoperatively in 42 patients. When these patients were compared with 260 patients without complications, hemoglobin, leukocyte count, serum albumin, total protein, blood sedimentation rate, age and sex were found not to contribute to the prediction of postoperative complications. In DCH testing, the complication rate increased from 7.5 per cent in normergic patients to 20.6 per cent in anergic patients. With increasing length and severity of operation, the complication rate increased from 6.5 to 26.4 per cent and from 6.5 to 31.8 per cent, respectively. Only in severe, long lasting operations could DCH testing differentiate the complication risk. Normergic patients had a 8.6 per cent complication rate; hypoergic patients, 36.6 per cent, and anergic patients, 37.5 per cent. The results of DCH testing did not correlate with the complication rate in any of the other operative groups. In conclusion, the predictive value of DCH testing is clearly greater in groups of patients highly affected by the operative trauma. The results of this study show that it is important to consider both host defense mechanisms and environmental factors in the assessment of operative risks.

Pancreatic surgery, gastric secretion and ulcers in the rat. Increased ulcer development following pancreatic half resection or duct occlusion

In the rat, both partial resection of the pancreas and occlusion of the side branches of the biliodigestive duct were investigated with respect to their influence on gastric secretion (acid, pepsin, sodium), gastric mucosal blood flow (MBF), development of gastric ulcers, and gastrin and somatostatin in the blood. On the 14th postoperative day the exocrine pancreatic function is reduced and ulcer index and severity are significantly enhanced. There are no simultaneous changes in gastric secretion or MBF. Aortal gastrin was decreased and somatostatin was unchanged. We conclude that: in the rat, reduction of exocrine pancreatic function should be considered an ulcerogenic factor; factors others than gastric hypersecretion or reduced MBF are responsible for ulcer formation, and an etiological role of either circulating gastrin or somatostatin is doubtful.