Desenvolvimento de método para a determinação de metais no sangue e sua correlação com a leucemia linfocítica aguda

Abstract

Acute lymphocytic leukemia (ALL) is characterized as a hematological disease that originates during the development of young white blood cells, called lymphocytes. Although it is the type of cancer with the highest number of cases in children, however adults can also be diagnosed with the disease. In 2016, according to the National Cancer Institute (INCA), 10,070 new cases (5,540 men and 4,530 women) were diagnosed in Brazil. The risk of developing the disease for children has a higher incidence rate at the age of five and nine years. To treat the disease, chemotherapy is used, where several drugs are administered with the intention to destroy the tumor cells, usually by the venous route. Unfortunately, these drugs are not selective and can cause damage to healthy cells in the body. This work aims to determine the concentration levels of some elements present in whole blood of patients and to correlate it with possible collateral damages throughout the treatment, since the change in its concentrations of the same can influence directly in the performance of some organs, as well as in the homeostasis of the organism as a whole. Blood samples from patients with ALL were collected at Santa Maria University Hospital with the consent of the responsible person, reaching all different stages of the disease. In order to obtain reliable results, possible metal contaminants in the collection vials and anticoagulants were evaluated. The determinations of element concentration were performed by inductively coupled plasma mass spectrometry. In addition to determining the levels of elements present in the whole blood of patients, enzymatic activity tests for catalase were also performed in order to correlate the effect of a possible reduction in metal levels with the efficiency of the enzymes in reducing the production of reactive oxygen species (ROS). Due to the big amount of samples and reduced volume, a sample decomposition procedure was developed using only 250 mg in open system and single disposable vial. A mixture of 1: 1 HNO3 and H2O2 was used and the samples were submitted to micro-wave irradiation for a period of 20 minutes. The development of this method proved to be crucial for the decomposition of a large number of samples, fast and has a good efficiency. The determined elements were Arsenic, Cu, Mn, Rb, Sb, Sr, V and Zn were quantified. Rare earth elements were monitored, but their concentration were below the limit of quantification or contamination, while high contamination of Ca, Mg, Na and Al was observed from the collection and sample handling. Elements were performed by inductively coupled plasma mass spectrometry. In addition, enzymatic activity assays for catalase were also performed in order to correlate the effect of a possible reduction in metal levels with the efficiency of the enzymes in reducing the production of radical oxygen. It was observed that patients with ALL have very low concentrations of the metals before starting the treatment of the disease. However at the end of the treatment, the concentration of the elements is mostly very close to the concentration of the control group. The catalase enzymatic assays showed a high activity for the beginning of the treatment and reduction towards the stages near the end of the treatment, indicating a possible reduction in the generation of ROS generated before and during the treatment.