Comparative evaluation of NASBA HIV-1 RNA QT, AMPLICOR-HIV monitor, and QUANTIPLEX HIV RNA assay, three methods for quantification of human immunodeficiency virus type 1 RNA in plasma.

Three commercial assays for quantifying plasma human immunodeficiency virus type 1 (HIV-1) RNA were evaluated. The assays differed in their sample volumes, the means of preparing samples, and methods of amplification and detection. Plasma samples were obtained from 36 HIV-1-infected patients representing all stages of HIV-1 infection and were analyzed as coded specimens. Measurement of HIV-1 RNA baseline levels revealed no significant difference in sensitivity between the three assays. The assays were also applied to the quantitation of HIV-1 RNA levels in the plasma of patients who were changing their antiretroviral therapy. The changes measured in HIV-1 RNA levels in plasma in response to therapy were comparable by the three assays. No close correlation was found between the amount of HIV-1 RNA and the CD4 T-cell count; HIV-1 RNA assays were more sensitive than p24 antigen assays as an indicator of plasma viremia. Overall, the study demonstrates that all three quantitative assays for HIV-1 RNA can be used to measure the HIV-1 RNA copy number representing the HIV-1 viremia status in patients with HIV-1 infection. Since this copy number is likely to be useful in monitoring the effectiveness of antiviral therapy, these quantitative assays for HIV-1 RNA are ready to be built into clinical trials

Low-Level Gamma-Ray Spectrometry for Analysing Fusion Plasma Conditions

A new method, combining activation by neutrons and charged particles with ultra low-level gamma-ray spectrometry, aimed at obtaining a better understanding and more adequate measurements of MeV particle leaks in magnetic fusion devices was studied here. A total of 36 samples containing Ti, LiF, B4C and W were placed in a boron nitride holder mounted on the ceiling of the JET Tokamak. The samples were activated by 63 pulses from a D-3He plasma and were later measured using underground gamma-ray spectrometry. The radionuclides 7Be, 46Sc, 54Mn, 56Co, 57Co, 58Co, 124Sb, 181Hf, 182Ta, 181W and 185W were detected in several of the samples, very low levels of activity of 47Sc and 48V being found in a few of the samples. The various production channels for the radionuclides in question are discussed.JRC.D.4-Isotope measurement

Measurements of 60Co in massive steel samples exposed to the Hiroshima atomic bomb explosion

To study discrepancies in retrospective Hiroshima dosimetry, the specific activity of 60Co in 16 steel samples from Hiroshima was measured using gamma-ray spectrometry in underground laboratories. There is general agreement between these new activity measurements and the specific activities derived from previously calculated dose values on the one hand and former measurements of samples gathered at distances less than 1,000 m from the center of the explosion (less tahn 1,000 m slant range) on the other. It was found that activities at long range (more than 1,300 m slant range) were mainly cosmogenically induced. Furthermore, at long range, these results are in disagreement with older measurements whose specific activity values were 10 to 100 times higher than predicted by computer model calculations in DS86 and DS02. As a consequence, the previously reported discrepancy is not confirmed.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Isolation of HIV-1 RNA from plasma; evaluation of eight different extraction methods

The efficacy of eight different methods for the extraction of HIV-1 RNA from plasma was compared. The RNA preparation method that gave the best results by RT-PCR was the one described by Chomczynski and Sacchi (1987, Anal. Biochem. 162, 156-159). This method consists of a guanidine thiocyanate treatment followed by three phenol-chloroform-isoamylalcohol extractions and an ethanol precipitation. The disadvantage of this method is that it is time consuming and less suitable for the extraction of large series of samples. Moreover, due to the large number of procedural steps, there is a greater risk of sample mix-up or contamination. Of the single-step RNA purification methods, good results were obtained with the TRIzol method (Gibco Life Technologies, Paisley, UK) and with the extraction method offered by the NASBA kit (Organon Teknika, Turnhout, Belgium). The above single-step methods are recommended since both are sensitive enough to detect low copy numbers of HIV-RNA in the plasma of asymptomatic patients, and require only 2 h for completion. For most of the methods evaluated the inter-test variablity was acceptable (mean variation coefficient between duplicate extraction varied between 17.3 and 47.3%). Inter-laboratory reproducibility was evaluated only for the TRIzol-method and found to be low (mean variation coefficient 63.4)

Mega-Electron-Volt Ion Loss Measurements in JET D-3He Plasmas Using Activation Technique

Sample activation measurements in JET tokamak by nuclear reactions from MeV ions are reported. Charged particle losses were observed for the first time using an activation technique. Remarkably, these particle leaks were measured in the JET ceiling in D-3He plasmas (Bt 3.35T, Ip 2.1MA and ion velocity drift direction pointing downwards). In collaboration with three underground European laboratories, a detailed gamma-ray spectroscopy analysis was performed. Absolutely calibrated measurements of charged particle losses were obtained for the first time as function of pitch angle and distance to plasma edge. Modelling work to compare measurements and charged particle losses prediction from theory is described.JRC.D.4-Isotope measurement