1. The dimethylhydrazine induced colorectal tumours in rat - experimental colorectal carcinogenesisMartina Perše, Anton Cerar, 2005, review article Abstract: Animal models of colorectal carcinogenesis represent invaluable research tool for investigating colorectal cancer (CRC). Experimentally induced tumours in laboratory animals provide opportunity for studying certain aspects of tumoursthat cannot be effectively studied in humans. Significant information on human CRC aetiology or factors influencing it has derived from studies using dimethylhydrazine (DMH) model that is one of the experimental models appreciated for its morphological similarity to human CRC. Today, DMH model represents useful research tool for the studies of colon carcinogens and chemopreventive agents. The review offers insight into morphogenesis and genetic alterations of DMH induced colorectal epithelial tumours in rats.
Published in DiRROS: 14.02.2024; Views: 113; Downloads: 28
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2. Comparison of Wistar vs. Fischer rat in the incidence of 1,2-dimethylhydrazine induced intestinal tumorsŽeljka Večerić-Haler, Anton Cerar, 2004, original scientific article Abstract: Background. Many investigators have observed differences in the susceptibilityto induce intestinal tumors by 1,2-dimethylhydrazine (DMH) between various strains of rodents. The results are difficult to compare because of the different regimes used for induction. The purpose of our study was to evaluate the influence of strain on DMH-induced intestinal tumors between Wistar and Fischer rats. Materials and rreethods. We used 29 Fischer and 30 Wistar male rats that were injected subcutaneously DMH, weekly, at a dosage of 25 mg/kg-body weight for 20 weeks. After 25 weeks from the beginningof the experiment, the animals were sacrificed and autopsied. The complete length of colorectum and all macroscopic changes were examined histologically. Results. The induction of intestinal tumors was 97% in Fischerrats and 100% in Wistar rats. In Wistar rats 184 tumors were found: 133adenomas, 50 tubular adenocarcinomas and 1 signet-cell carcinoma. 77% of careinamas were found in colorectum and 23% in the small intestine. In Fiseherrats, 126 tumors were found: 94 adenomas, 26 tubular adenocarcinomas, 5signet-cell carcinomas and 1 mucinous carcinoma; 42% of carcinomas were foundin the colorectum and 58% in the small intestine. The strain difference in the incidence of all induced tumors was statistically significant (P=0.001). The differences in the occurrence of the malignant and benign tumors was also significant (P<0.001; P=0.011). Extra intestinal tumors were not found. Conclusions. Wistar rats showed greater percentage of colorectal tumors, and also the distribution of tumors in colorectum resembled more the distribution found in human pathology. That is why we reeommend Wistar rat rather than Fischer rat for the research work on the colorectal tumors.
Published in DiRROS: 13.02.2024; Views: 112; Downloads: 28
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3. A role of gender in the occurrence of dimethylhydrazine induced colorectal tumors in Wistar ratsLjubo Breskvar, Anton Cerar, 1997, original scientific article Abstract: Human colorectal carcinoma appears more frequently in males. The aim of our study was to evaluate the influence of gender on the induction of colorectal carcinoma by 1,2-dimethylhydrazine (DMH) in Wistar rats. Sixty Wistar rats (30males, 30 females) were subjected to weekly subcutanous injections of DMH (20 mg/kg) for 15 weeks. After 25 weeks from the beginning of the experiment the animals were sacrificed and autopsied. All macroscopical lesions were evaluated histologicaly. Induction of colorectal tumors succeeded in 37% of males and 17% of females. There were 21 tumors of the large bowel found, of these 15 in males and 6 in females. Histologically, males had 11 adenomas, 2 signet-cell carcinomas and 2 adenocarcinomas, while females had 4 signet-cell carcinomas and 2 adenomas. We also found extracolonic tumors, mainly those of the small intestine and of the Zymbal glands. Wistar rats showed lower incidence of DMH-induced colorectal tumors in comparison with other strains ofrats. The gender-dependent difference in the incidence of colorectal tumors was found to be statistically marginally significant (p<0.08), whereas the difference in the incidence of all induced tumors between genders was significant (p<0.02). Males showed a greater incidence of coloreactal tumors and also a greater histological resemblance to human colorectal tumors than females. That is why we recommend Wistar males rather than females for research on colorectal tumors.
Published in DiRROS: 18.01.2024; Views: 157; Downloads: 32
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4. Effect of the type of application of Newcastle disease virus on the Ehrlich ascites tumorTomaž Milanez, Robert Košak, Anton Cerar, 1996, original scientific article Abstract: Newcastle disease virus (NDV) has been shown to have an inhibitory effect on the tumours. Most authors use peritumoral application of virus. The purpose of our studz was to compare the effects of the ip in contrast to sc application of the virus on the ip and sc transplanted Ehrlich ascites tumor (EAT) in CBA/H mouse. We measured the length of survival, the tumor cure rates, the metastatic rate, and the frequencz of ascites and sc tumors in the site of ip EAT injection. Prolongation of survival after the therapy with NDV in ip transplanted EAT average time of survival in control group was 70.5 days, and 107 and 79.9 days with ip and sc NDV virus therapy respectively. The differences were significant only between control group and the group treated with ip application of NDV. Tumor cure rates were: ipNDV group 30%, scNDV group 20% and control group 5%. NDV therapy in sc transplanted EAT prolonged the time of survival; in control group it was 63.3 days, and 75.2 and 65.9 days with ip and sc NDV therapy respectively. NDV therapy inhibited metastatic rate of ip transplanted EAT. Inhibition was more effective with ip application of NDV. VIrus therapz also lowered the frequencz of appearance of ascites and sc tumour in the site of ip EAT injevtion. In sc transplanted EAT ip application of NDV inhibited the metastatic rate while in sc applied NDV some stimulation of metastasation was found. Ip application of NDV was found to be superior in contrast to sc application in all its therapeutic effects against EAT. Our results show that the tumor inhibition of NDV, in the system we used, has the characteristics of the biological response modifiers.
Published in DiRROS: 16.01.2024; Views: 149; Downloads: 40
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5. Gastric emptying in rats with gastroduodenal disease induced by N-methyl-N-nitro-N-nitrosoguanidine and alcoholDražigost Pokorn, Anton Cerar, 1996, original scientific article Abstract: The rate of gastric emptying was measured with a dye dilution technique in rats treated with N-methyl-N-nitro-N-nitrosoguanidine and alcohol. Gastric emptying was compared in rats with gastroduodenal inflamatory diseases and gastroduodenal neoplasms, and in those without gastroduodenal disease. Gasttric emptying was found to be significantly increased following the intragastric injection of liquid meal in rats with gastroduodenal diseases as opposed to the control group of healthy rats. These findings suggest than an increased gastric emptying of liquids can be explained by abolition on the relaxation of the gastric wall in rats with gastroduodenal diseases.
Published in DiRROS: 16.01.2024; Views: 132; Downloads: 42
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