Tumour formation

Rubin JB, Gutmann DH (2005) Neurofibromatosis type 1 - a model for nervous system tumour formation Nat Rev Cancer 5 557-564... 

The interest in bile acids as potential carcinogens was subject to investigation as early as 1940 when Cook et al. reported in Nature that repeated injection of deoxycholic acid into the flanks of mice could induce tumour formation in mice." Furthermore, Kelsey and Pienta showed that treatment of hamster embryo cells with lithocholic acid could cause cell transformation. ... 

However, subsequent studies did not find clear evidence to support the view that bile acids could independently stimulate tumour formation utilising rat models. Rather, the findings indicated that bile acids could enhance the effect of other carcinogens in these models. An example of such a study is by McSherry et al. in which male Fischer rats were fed diets supplemented with cholic acid (0.2%) and administered the colonic carcinogen, A-Methyl-A-nitrosurea (MNU), intra-rectally. Fifty-five per cent of MNU treated rats on standard diet developed tumours, a figure that increased to eighty per cent in MNU-treated rats given dietary cholic acid. Rats fed cholic acid supplemented diet alone did not develop tumours. 

Viruses produce CPEs on cells and are the agents for many diseases in humans and other animals. In addition, many viruses (e.g. oncoma viruses, herpes type II, adenovirus and polyoma and SV40) are believed to be agents responsible for tumour formation in animals. Moreover, due to their ability to pass through bacteriological filters it is difficult to exclude viruses from uninfected cell cultures if the viruses are present in suspension in the air of the culture room. For these reasons it is recommended practice to take special precautions when using viruses. 

Growth high or indefinite saturation density, reduced serum requirement, growth in agar or Methocel (see Appendix 6), suspension tumour formation on injection into susceptible... 

Several scientific studies provide evidence of the traditional use of parsley in medicine. Food plants of the Apiaceae plant family such as parsley, carrots and celery contain a group of bioactive aliphatic C17-polyacety-lenes, which were shown to be highly toxic towards fungi, bacteria and mammalian cells and to display neurotoxic, anti-inflammatory and antiplatelet aggregatory effects and to be responsible for allergic skin reactions in a study by Christensen and Brandt (2006). The effect of these polyacetylenes towards human cancer cells, their human bioavailability and their ability to reduce tumour formation in a mammalian in vivo model indicate that they may be beneficial for health. 

Salaman MH, Roe FJC. 1956. Further tests for tumour-initiating activity N, N-di-(2-chloroethyl)-P-aminophenylbutyric acid (CB1348) as an initiator of skin tumour formation in the mouse. BrJ Cancer 10 363-378. 

An essential function of the tumour suppressor p53 is to prevent propagation of cells with damaged DNA. In that way p53 suppresses tumour formation. Cells with damaged DNA cannot enter the S phase. They are arrested in the Gi phase. This gives cells time for DNA repair. p53 may also keep them arrested permanently, preventing proliferation of damaged cells. 

The term carcinogen denotes a chemical substance or a mixture of chemical substances which induce cancer or increase its incidence. Substances which have induced benign and malignant tumours in well performed experimental studies on animals are considered also to be presumed or suspected human carcinogens unless there is strong evidence that the mechanism of tumour formation is not relevant for humans. 

Diagnosis Malignant tumour formation is accompanied by inappetence and weight loss, pain in the upper right abdominal quadrant, fever, specific laboratory findings and paraneoplastic symptoms, (see chapter 37)... 

Fig. 37.6 HCC nodiilar liver surface in cirrhosis. Tumour formation in the right lobe of hver, in parts at the margin central hypo-density with peripheral hypervascularization (CT after CM)...

Tennekes, H., van Ravenzwaay, B., and Kunz, H. W. (1985). Quantitative aspects of enhanced liver tumour formation in CF-1 mice by dieldrin. Carcinogenesis 6, 1457-1462. 

Mrowietz, U., U. Schwenk, S. Maune, J. Bartels, M. Kupper, I. Fichtner, J. M. Schroder, and D. Schadendorf. 1999. The chemokine RANTES is secreted by human melanoma cells and is associated with enhanced tumour formation in nude mice. Br J Cancer 79 1025. 

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