Preparation and evaluation of new reference materials for naturally occurring radioactive materials (NORM): Zirconium silicate, bauxite, and phosphogypsum.

New reference materials (RMs), zirconium silicate, bauxite and phosphogypsum, were produced and characterized according to an ISO guide. The homogeneity of the three RMs was evaluated using X-ray fluorescence (XRF), and characterizations of the three candidate materials were performed through a collaborative study with nine expert radioanalytical laboratories. The assigned radionuclides are 230Th, 232Th, 234U, 235U, and 238U for zirconium silicate; 230Th, 232Th, 234U, and 238U for bauxite; and 226Ra, 230Th, 234U, and 238U for phosphogypsum.

Susceptibility of oxidative stress on red blood cells exposed to gamma rays: hemorheological evaluation.

Irradiation has been shown to induce biochemical changes in stored red blood cells (RBCs) and to generate reactive oxygen species (ROS). This study evaluated the hemorheological properties, the degree of lipid peroxidation and the oxidative susceptibility of irradiated RBCs. Furthermore, we investigated the radioprotective role of N-t-butyl hydroxylamine (NtBHA) against gamma-ray exposure of RBCs. RBC concentrates were irradiated with a minimum dose of 25 Gy, and were exposed to FeSO4 to examine the oxidative susceptibility. RBC deformability was evaluated by the use of a microfluidic ektacytometer, in relation to the hematological and biochemical properties. The deformability of the irradiated RBCs was significantly lower than that of control. Exposure to gamma rays significantly increased the mean corpuscular volume (MCV) and lipid peroxidation. Changes in RBC deformability were more prominent in irradiated RBCs than in non-irradiated RBCs also under conditions of oxidative stress. The deformability of NtBHA treated RBCs prior to irradiation was not altered as compared with irradiated RBCs not treated with NtBHA. In conclusion, irradiation reduces RBC deformability during storage and the irradiated RBCs seem susceptible to oxidative stress. NtBHA may not have a protective role against the effects of gamma-ray exposure in RBCs but further evaluation of NtBHA or another radioprotective compound is required.

Inactivation and viral load quantitation of human immunodeficiency virus in blood collected into Cyto-Chex(®) BCT blood collection device.

A blood collection tube (Cyto-Chex(®) BCT), which can stabilize white blood cells and immunogenic markers in blood samples, was investigated for its ability to inactivate human immunodeficiency virus (HIV) and stabilize HIV for viral load quantitation. Laboratory-adapted HIV strains were either treated or untreated with the stabilizing reagent present in Cyto-Chex(®) BCT. A dilution of the reagent used to treat virus was 1:66, which was similar to the reagent concentration in Cyto-Chex(®) BCT device when blood was drawn into it. In another experiment, blood was drawn from HIV patients into one acid citrate dextrose (ACD) tube and one Cyto-Chex(®) BCT. At indicated time points, aliquots were taken of treated and untreated viral dilutions and from plasma of HIV-positive patient blood samples and analyzed using reverse transcriptase and TZM-bl cell assays to determine HIV inactivation. In laboratory-adapted HIV strains and HIV-positive patient plasma, HIV was completely inactivated within 2 and 3h of contact with a 1:66 dilution of Cyto-Chex reagent, respectively. Samples from HIV-positive patient plasma showed that viral load was stable in Cyto-Chex(®) BCT for 7 days at room temperature. Therefore, it is concluded that the chemical reagent present in the Cyto-Chex(®) BCT blood collection device is capable of complete inhibition of HIV infectivity in blood samples within 3h and stabilizing the viral load for 7 days at room temperature.