Radioactivity biological effects from

The chemistry, and hence hazards, of hot, or radioactive, elements parallels that of their cold isotopes. However, the radiation poses additional toxicity hazards. A qualitative classification of selected isotopes in terms of their toxicity is given in Table 10.2. The biological effects of ionizing radiation stem mainly from damage to individual cells following ionization of the water content. Oxidizing species, e.g. hydrogen peroxide. 

Potassium iodine tablets can be used to reduce radioactive iodine exposure to the thyroid gland. According to the National Council of Radiation Protection and Measurement (NCRP), taking 130 milligrams of potassium iodine at or before exposure to radioactive iodine effectively blocks nearly 100% of radioactive iodine from reaching the thyroid (1977). See Table 3.3 for a summary of antidotes for various chemical and biological agents. 

Identification of thymine dimer is particularly easy if the irradiated DNA is obtained from an organism which has been grown on a medium containing radioactive thymine, and thus contains radioactive thymine dimer. The amount of thymine dimer isolated can then be estimated by simple counting of the eluted material. Estimation of the amount of thymine dimer can also be made by measuring the recovery of absorbance at 270 nm produced by irradiation of the aqueous eluate of the dimer spot. The amount of thymine dimer in irradiated DNA has sometimes been estimated without isolation by measuring the absorbance photorecovery of the DNA, and this quantity correlated with the biological effect this seems a potentially hazardous procedure. 

Radiation is a phenomenon characterized more by its ability to canse biological effects than where it originates. Radiation was hrst discovered by German scientist Antoine Henri Becquerel, who received the Nobel Prize of Physics in 1903 for his work. Many of the terms associated with radioactivity come from those early pioneers in radiation physics Wilhelm Conrad Roentgen (1845-1923) and Pierre (1859-1906) and Marie Curie (1867-1934), who also received the Nobel Prize in Physics in 1903 for their work on radiation. Ernest Rutherford (1871-1937) is considered the father of nuclear physics. He developed the language that describes the theoretical concepts of the atom and the phenomenon of radioactivity. Particles named and characterized by him include the alpha particle, beta particle, and proton. Rutherford won the Nobel Prize for Chemistry in 1909 for his work. 

Poly(alkyl cyanoacrylate) nanocapsules were successfully used for oral administration of insulin in diabetic rats. Insulin-loaded nanospheres (100 lU/kg of body weight) that were administered perorally in streptozotocin-induced diabetic rats provoked a 50% decrease of fasted-glycemia from the second hour up to 10-13 days. When " C-labeled nanospheres loaded with insulin were used, it was found that nanospheres increased the uptake of insulin or its metabolites in the GIT, blood, and liver, while the excretion was delayed when compared with 1 insulin nonassociated to naiiospheres in addition, C and 1 radioactivities disappeared progressively as a function of time, parallel to the biological effect. 

---