MEDICAL BIOLOGY, ANATOMY, HUMAN PHYSIOLOGY AND PATHOLOGY - Ya.I. Fedoniuk 2010

BIOLOGY

SECTION 1. BIOLOGICAL BASES OF HUMAN VITAL ACTIVITY

1.4. ONTOGENETIC LEVEL OF LIFE ORGANIZATION

1.4.2. Basics of Human Genetics

Mutagens

Mutagens (mutagenic factors) are agents that induce Mutations. Many of them are also carcinogens, meaning they are capable of causing malignant tumors. Mutagens are generally classified into three types: physical, chemical, and biological.

Physical Mutagens include all Types of ionizing radiation (gamma and X-rays, electrons, positrons, protons, neutrons), ultraviolet radiation, as well as high and low temperatures. Ionizing radiation is the most hazardous. All types of ionizing radiation possess high penetrative power and distinctive biological effects. As they penetrate human Tissues, they transfer their energy to the atoms of these tissues, causing excitation and ionization. Proliferating tissues, such as lymphoid and hematopoietic tissues, are particularly sensitive. Ionizing radiation affects all cellular components, but the nuclear Chromosomes are especially vulnerable. It induces breaks in DNA molecules, resulting in Chromosomal aberrations and point mutations. Mutation induction occurs at any dosage, and the number of mutations increases in direct proportion to the dose. The Genetic Effects of low doses are cumulative. Any use of ionizing radiation requires strict adherence to radiation safety regulations and radiation protection measures for both patients and medical staff.

Ultraviolet rays do not cause ionization; instead, they excite the electron shells of atoms, increasing their chemical reactivity and potentially leading to mutations. UV rays with a wavelength of approximately 260 nm exhibit the highest mutagenic activity because this specific region of the spectrum is readily absorbed by DNA.

Chemical Mutagens encompass A wide variety of chemical compounds used in agriculture as herbicides (maleic hydrazide) and pesticides (DDT), in medicine as Pharmaceuticals (cytostatic and antimitotic agents), in industry (benzene, heavy metals such as cadmium, mercury, lead, and nickel), including the food industry (food additives), and in everyday life (varnishes, paints). To prevent mutagenesis, any chemical compound intended for practical use must undergo rigorous testing for mutagenicity.

The most potent mutagens (supermutagens) include ethyleneimine, diethyl sulfate, nitrosoethylurea, nitrosomethylurea, hydrogen peroxide, and mustard gas. The second group comprises substances structurally similar to the nitrogenous bases of Nucleic Acids that directly interact with them: 5-bromouracil, 5-fluorodeoxyuridine, and 5-bromodeoxyuridine. The third group includes acridines and their derivatives, such as acridine yellow and ethidium bromide. The fourth group features nitrous acid, formaldehyde, and hydroxylamine.

Biological Mutagens include Viruses, live Vaccines, and toxins produced by certain organisms, particularly mold Fungi. Live vaccines are biological preparations derived from Bacteria or viruses with attenuated virulence.