ABSTRACT
Understanding the effects of radiation and its possible influence on the nervous system are of great clinical interest. However, there have been few electrophysiological studies on brain activity after exposure to ionizing radiation (IR). A new methodological approach regarding the assessment of the possible effects of IR on brain activity is the use of linear and nonlinear mathematical methods in the analysis of complex time series, such as brain oscillations measured using the electrocorticogram (ECoG). The objective of this study was to use linear and nonlinear mathematical methods as biomarkers of gamma radiation regarding cortical electrical activity. Adult Wistar rats were divided into 3 groups: 1 control and 2 irradiated groups, evaluated at 24 h (IR24) and 90 days (IR90) after exposure to 18 Gy of gamma radiation from a cobalt-60 radiotherapy source. The ECoG was analyzed using power spectrum methods for the calculation of the power of delta, theta, alpha and beta rhythms and by means of the α-exponent of the detrended fluctuation analysis (DFA). Using both mathematical methods it was possible to identify changes in the ECoG, and to identify significant changes in the pattern of the recording at 24 h after irradiation. Some of these changes were persistent at 90 days after exposure to IR. In particular, the theta wave using the two methods showed higher sensitivity than other waves, suggesting that it is a possible biomarker of exposure to IR.
Subject(s)
Cerebral Cortex/radiation effects , Electrocorticography/methods , Gamma Rays/adverse effects , Radiation Injuries/diagnosis , Radiation, Ionizing , Animals , Biomarkers , Brain/radiation effects , Linear Models , Male , Nonlinear Dynamics , Rats, Wistar , Statistics, Nonparametric , TimeABSTRACT
Understanding the effects of radiation and its possible influence on the nervous system are of great clinical interest. However, there have been few electrophysiological studies on brain activity after exposure to ionizing radiation (IR). A new methodological approach regarding the assessment of the possible effects of IR on brain activity is the use of linear and nonlinear mathematical methods in the analysis of complex time series, such as brain oscillations measured using the electrocorticogram (ECoG). The objective of this study was to use linear and nonlinear mathematical methods as biomarkers of gamma radiation regarding cortical electrical activity. Adult Wistar rats were divided into 3 groups: 1 control and 2 irradiated groups, evaluated at 24 h (IR24) and 90 days (IR90) after exposure to 18 Gy of gamma radiation from a cobalt-60 radiotherapy source. The ECoG was analyzed using power spectrum methods for the calculation of the power of delta, theta, alpha and beta rhythms and by means of the α-exponent of the detrended fluctuation analysis (DFA). Using both mathematical methods it was possible to identify changes in the ECoG, and to identify significant changes in the pattern of the recording at 24 h after irradiation. Some of these changes were persistent at 90 days after exposure to IR. In particular, the theta wave using the two methods showed higher sensitivity than other waves, suggesting that it is a possible biomarker of exposure to IR.
Subject(s)
Animals , Male , Cerebral Cortex/radiation effects , Electrocorticography/methods , Gamma Rays/adverse effects , Radiation, Ionizing , Radiation Injuries/diagnosis , Biomarkers , Brain/radiation effects , Linear Models , Nonlinear Dynamics , Rats, Wistar , Statistics, Nonparametric , TimeABSTRACT
Research for radiodiagnostic agents should considerate biological critical parameters which will give own contribution on the absorbed dose. The dimercaptosuccinic acid (DMSA) labeled with (99m)Tc(V) is a radiopharmaceutical which has well established role in medullar thyroid carcinoma and has been proposed in evaluation of bone metastasis. This work studied the biokinetics and dosimetry of (99m)Tc(V)-DMSA by animal model. The (99m)Tc(V)-DMSA was prepared from a (III)DMSA kit alkalized. Mice (n=5) received (99m)Tc(V)DMSA i.v., they were sacrificed (30 min, 1h, 5h and 12h), the organs excised and the activities measured by a gamma counter. The results were evaluated based on %activity/g and the absorbed dose was estimated (MIRDOSE 3.0 program) by extrapolation of data from animal to human scale. The results showed the majority of organs reached the top uptake at 30 min, the greatest kidney uptake was (4.81 +/- 1.38)% activity/g, while the bone presented its highest uptake at 1h (5.49+/- 0.47)% activity/g, after 1h all the organs had activity exponential decrease. The biokinetic profile of (99m)Tc(V)-DMSA was well established, allowing quantifying of residence time, and the radiation dose estimates were made for this agent. About the absorbed dose, the preliminary results showed higher value to bone, being the soft tissue dose relatively low.
Subject(s)
Radiometry/methods , Technetium Tc 99m Dimercaptosuccinic Acid/chemistry , Absorption , Animals , Mice , Neoplasm Metastasis , Radiation Dosage , Radiopharmaceuticals/chemistry , Radiopharmaceuticals/pharmacokinetics , Technetium Tc 99m Dimercaptosuccinic Acid/pharmacokinetics , Time Factors , Tissue DistributionABSTRACT
Many studies have reported the occurrence of lethal acute renal failure after snakebites. The aim of the present investigation was to determine alterations in renal function produced by Crotalus durissus terrificus venom and crotoxin as well as the histological alterations induced by these venoms. Isolated kidneys from Wistar rats weighing 240 to 280 g were perfused with Krebs-Henseleit solution containing 6 g percent of previously dialyzed bovine serum albumin. The effects of Crotalus durissus terrificus venom and crotoxin were studied on glomerular filtration rate (GFR), urinary flow (UF), perfusion pressure (PP) and percentage sodium tubular transport ( percentTNa+). The infusion of Crotalus durissus terrificus venom (10 æg/ml) and crotoxin (10 æg/ml) increased GFR (control80 = 0.78 + or - 0.07, venom80 = 1.1 + or - 0.07, crotoxin80 = 2.0 + or - 0.05 ml g-1 min-1, P<0.05) and UF (control80 = 0.20 + or - 0.02, venom80 = 0.32 + or - 0.03, crotoxin80 = 0.70 + or - 0.05 ml g-1 min-1, P<0.05), and decreased percentTNa+ (control100 = 75.0 + or - 2.3, venom100 = 62.9 + or - 1.0, crotoxin80 = 69.0 + or - 1.0 ml g-1 min-1, P<0.05). The infusion of crude venom tended to reduce PP, although the effect was not significant, whereas with crotoxin PP remained stable during the 100 min of perfusion. The kidneys perfused with crude venom and crotoxin showed abundant protein material in the urinary space and tubules. We conclude that Crotalus durissus terrificus venom and crotoxin, its major component, cause acute nephrotoxicity in the isolated rat kidney. The current experiments demonstrate a direct effect of venom and crotoxin on the perfused isolated kidney
