No abstract

The popularity of cocaine boomed in the 1980s when freebase cocaine (crack) became widely known. The drug can be consumed as both salt and freebase either by sniffing or smoking.1) The ability to achieve rapid, high brain levels of cocaine by smoking crack has greatly increased its abuse potential and also its toxicity.2) Cocaine in the form of freebase is preferred by drug misusers because it is much more socially acceptable, particularly among habitual smokers of marihuana.3) At the same time, freebase appears to be much cheaper than cocaine hydrochloride. 4,5) The toxic effects of cocaine in humans are similar to those of crack, 6) although the signs and symptoms caused by crack are more intense and short-lasting. 7,8) The protozoan Tetrahymena pyriformis, a monocellular organism, is a suitable experimental model for functional, pharmacological, toxicological or immunotoxic studies. [9][10][11][12] Our experience with this protozoan has led us to consider its DNA content as a parameter that we could examine for the detection of toxic responses to cocaine. This protozoan contains a macronucleus which participates in the conjugation and division of the cell and contains deoxyribonucleic acid. In most strains of Tetrahymena, a micronucleus is also present.13) Macronucleus of the protozoan Tetrahymena pyriformis contains 12-24 times as much DNA as does micronucleus and practically represents the total DNA content of the cell. Macro-and micronuclei both give strongly positive cytochemical reactions for DNA (Feulgen). 14,15) The aim of this study was to investigate the possible toxic effects of cocaine salt and cocaine freebase (crack) on the DNA content of the macronuclei of the protozoan Tetrahymena pyriformis, in an effort to explain the underlying mechanisms for the immunodeficiency which cocaine addicts develop, since our daily practice concerns drug addicts. MATERIALS AND METHODSA computerized image analysis system (CIAS), based on high-resolution scanning, has proved to be an effective approach to examine and classify stained cells spread on a glass slide in the form of smears. 16,17) This technique is based on a conversion of optical images of cells into arbitrary numerical values (digitization) based on light absorbance or transmission.The CIAS was used to study the macronuclei of the cell. Relevant procedures with the protozoan Tetrahymena pyriformis have been established for years. 18,19) This protozoan was grown axenically in a proteose-peptone broth at 25°C, without stirring the cultures, until reaching late log phase, generally 4-5 d after inoculation. 12)Cocaine hydrochloride or crack was added to the 100-ml cultures as aqueous solution in doses 1 and 2 mg of substance per 100 ml of culture respectively. These doses were selected based on previous studies carried out in our laboratory with doses ranging from 0.15 to 0.60 mg of both cocaine and crack per ml of protozoan culture, which did not produce any effects.12) The toxic effects of cocaine in humans have been noted with blood concentrations rangi...

may reveal the burden of disease. Br J Dermatol. 2009;160:729-735. 8. Thyssen JP, Johansen JD, Menné T, Nielsen NH, Linneberg A. Nickel allergy in Danish women before and after nickel regulation. N Engl J Med. 2009;360:2259-2260. 9. Thyssen JP, Menné T, Johansen JD. Nickel release from inexpensive jewelry and hair clasps purchased in an EU country -are consumers sufficiently protected from nickel exposure? Sci Total Environ. 2009; 407:5315-5318. 10. Thyssen JP, Menné T, Schnuch A, et al. Acceptable risk of contact allergy in the general population assessed by CE-DUR--a method to detect and categorize contact allergy epidemics based on patient data.