- •16. Neoplasia
- •16.1. Name the basic kinds of tissue growth changes.
- •16.3. Why tumoral process is considered to be the general biological phenomenon?
- •16.4. Are there features in character of tumoral process in humans and different kinds of animals?
- •16.5. What are the basic distinctions between benign and malignant tumours?
- •16.6. What are methods of experimental studying of tumours?
- •16.7. Name principal causes of malignant tumours occurrence.
- •16.8. Who and how for the first time has proved a role of chemical factors in occurrence of malignant tumours?
- •16.9. How are chemical carcinogens classified?
- •16.10. Give the examples of carcinogens of a natural and artificial origin.
- •16.11. Characterize carcinogenic action of polycyclic aromatic hydrocarbons (pah).
- •16.12. What is the feature of carcinogenic action of aromatic amines?
- •16.13. What is carcinogenic influence of nitrozo-compaunds characterized by?
- •16.14.Give examples of carcinogenic action of products of mushrooms life.
- •16.15. What meaning is put in concept "endogenous carcinogens"?
- •16.16. In what experiences possible participation of hormones in occurrence of malignant tumoral growth is proved?
- •16.17. What are chemical carcinogens of direct and indirect action? Give their comparative characteristic.
- •16.18. What properties of chemical substances cause their carcinogenic action?
- •16.19. What stages passes chemical carcinogenesis? What is their essence?
- •16.20. What is an explanation of the phenomenon of a tumoral progression?
- •16.21. What physical factors can matter in occurrence of malignant tumours?
- •16.22. Name the basic laws of carcinogenic action of an ionizing radiation.
- •16.23. What is "plastic" carcinogenesis? What are its features?
- •16.24. Who proved a role of viruses in occurrence of tumours and in what experiments?
- •16.25. What dna-containing viruses are oncogenic for animals and human?
- •16.26. What rna-containing viruses are oncogenic for animals and human?
- •16.27. Name stages of virus oncogenesis.
- •16.28. Name factors on which transforming action of viruses on a cell depends.
- •16.29. What are the viral oncogenes?
- •16.30. What are protooncogenes?
- •16.31 How are virus oncogenes and protooncogens classified?
- •16.32. What are cellular oncogenes? Name the basic mechanisms of transformation of protooncogenes into cellular oncogenes.
- •16.33. What are antioncogens?
- •16.34. What molecular mechanisms can underlie in virus oncogenesis?
- •16.35. What molecular mechanisms can be connected carcinogenesis, caused by action of chemical and physical factors?
- •16.36. Name features of growth of malignant tumoral cells in vitro conditions.
- •16.37. Name the basic features of growth of malignant tumours in vivo.
- •16.38. With what speed do malignant tumours grow? What factors is it defined by?
- •16.39. What violations of metabolism characterize malignant tumours?
- •16.40. What is invasiveness of tumours? How do malignant cells sprout in surrounding tissue?
- •16.41. What is metastasing? How is it carried out?
- •16.42. How do the tumours influence on an organism as a whole? Why cancer cachexy do develops?
- •16.43. What factors of an organism influence development of malignant tumours?
- •16.44. What mechanisms of antineoplastic protection exist in an organism?
- •16.45. Name the basic pathogenetic approaches to treatment of tumours.
16.12. What is the feature of carcinogenic action of aromatic amines?
Aromatic amines - are the substances containing in the structure benzol rings and amino groups. Carcinogenic properties has aniline and its derivatives, in particular, 2-naphtylamine, dimethylaminobenzol (DAB) possess. These substances are widely used in the industry as a basis of dyes, initial substances for synthesis of medical products and manufactures of explosives.
Prominent feature of carcinogenic action aromatic amines is their organotropicness. Irrespective of a way of receipt of substance introduction a tumour arise in the certain bodies. So, at injection 2-naphthylamine the cancer of a bladder develops, and at introduction DAB given - a cancer of a liver.
16.13. What is carcinogenic influence of nitrozo-compaunds characterized by?
To nitrozo-compaunds concern nitrozamines and nitrozamides. In experiences on animals it is shown, that 90 % of all studied nitrozo-compaunds possess carcinogenic action. Many substances of this class cause formation of tumours after unitary introduction in rather small dozes. It is not revealed any kind of animals (40 kinds from fishes up to primates were studied) which would be steady against carcinogenic action of nitrozo-compaunds. The human organism is also very sensitive to their influence.
Nitrozamides can be formed in a stomach of the person from not carcinogenic predecessors (nitrites, amino acids, amydopirine) at presence of a hydrochloric acid.
For carcinogenic action of nitrozo-compaunds is characteristic organotropicness. There are substances which selectively cause development of tumours of a brain, kidneys, liver, a stomach, etc.
16.14.Give examples of carcinogenic action of products of mushrooms life.
Among products of the mushrooms (mould) metabolism with carcinogenic action, it is most studied aflatoxine B. This mycotoxyne is heterocyclic substance and it is produced by mould Aspergillus fiavum, Carcinogenic action of aflatoxine is shown in very small dozes - 0,02 mg/kg of body weight. For comparison, toxic action of potassium cyanide is shown in the dozes exceeding specified in some tens of time.
With influence of mycotoxynes link development of a primary cancer of a liver in representatives of a tribe Bontu in Africa. A climate of territory on which lives this tribe, is very damp, therefore food is cooked quickly become covered by a mould. By tradition existing in those places such products are suitable to use. Analyses have shown, that in consumed food contains aflatoxine B
16.15. What meaning is put in concept "endogenous carcinogens"?
Endogenous are carcinogens which are formed in an organism from its normal components.
Finally it is not proved, however there are bases to believe, that in an organism during violation of a metabolism can appear carcinogenic polycyclic aromatic hydrocarbons. Their sources can be cholesterol, bilious acids, steroid hormones. In particular, it is shown, that processing of bilious acids in vitro leads to occurrence of methylcholantren - example of PAH possessing strong carcinogenic action.
Besides endogenous carcinogens can appear at violation of an exchange of some amino acids, in particular, trypthophane.