Accurate determination of ¹²⁹I concentrations and ¹²⁹I/¹³⁷Cs ratios in spent nuclear resins by Accelerator Mass Spectrometry

Determining long-lived radionuclide concentrations in radioactive waste has fundamental implications for the long-term management of storage sites. This paper focuses on the measurement of low (129)I contents in ion exchange resins used for primary fluid purification in Pressurised Water Reactors (PWR). Iodine-129 concentrations were successfully determined using Accelerator Mass Spectrometry (AMS) following a chemical procedure which included (1) acid digestion of resin samples in HNO3/HClO4, (2) radioactive decontamination by selective iodine extraction using a new chromatographic resin (CL Resin), and (3) AgI precipitation. Measured (129)I concentrations ranged from 4 to 12 ng/g, i.e. from 0.03 to 0.08 Bq/g. The calculation of (129)I/(137)Cs activity ratios used for routine waste management produced values in agreement with the few available data for PWR resin samples.

Decay scheme study of 126Sn and 126Sb

To study the decay scheme of (126)Sn, two samples of a purified solution were measured by gamma-ray spectrometry and the relative photon emission intensities were determined. The (126)Sb(m) isomeric branching ratio was derived to be 18.6 (6) %. The maximum beta energy of the (126)Sn decay was checked by liquid scintillation. The Kbeta/Kalpha intensity ratio of Sb was determined being 0.226 (11). These new experimental results were used to re-examine the whole decay scheme of (126)Sn and its daughters.

Determination of 126Sn half-life from ICP-MS and gamma spectrometry measurements

A new value of 126Sn half-life was determined by combination of inductively coupled plasma-mass spectrometry (ICP-MS) and gamma spectrometry measurements on purified sample solutions collected from nuclear fuel reprocessing. 126Sn was isolated through dissolution of fission product precipitates and liquid-liquid extraction with N-benzoyl-N-phenyl-hydroxylamine (BPHA). The abundance of 126Sn atoms together with the absence of interfering species in the analysed solutions made it possible to measure both mass concentration and nuclide activity with high precision and accuracy. This led to a 126Sn half-life value of 1.980(57)×105 a.

Rhenium migration at the Maqarin natural analogue site (Jordan)

Rock analysis and study of groundwater data was combined with a short duration column experiment in order to better understand the behavior of rhenium (Re) in the site of Maqarin (Jordan). Results show that the combustion metamorphism having affected rock masses in Maqarin (Jordan), and led to the formation of “natural cements”, has strongly modified the spatial distribution of several elements, among which Re, creating a specific source term for this element leached by groundwaters. Unaltered cements are shown to contain up to 1.2 μg/g Re to be compared to 0.15 μg/g in the initial biomicrite. Re is rapidly leached from unaltered cements and can be used as a tracer of recent cement alteration episodes. Preliminary data suggest that Re, a chemical analogue of Tc, could be partially retained in fracture minerals.

A new momentum in the field of transmissible spongiform encephalopathies (TSEs)

The present work is a critical survey answering a recent paper published by Stanley Prusiner's team in Science magazine. The authors claim that they used synthetic prions, instead of which they have tailored a particular recombinant protein, produced in E. coli, and devoid of its N-terminal part, therefore mimicking a truncated protein described by another team who isolated it from an iatrogenic TSE patient. This recombinant prion was lethal in normal mice, perhaps partly because, contrarily to what happens with the whole-length normal protein, these proteins are both neurotoxic, fibrillogenic and insensitive to proteolysis. Moreover, an accompanying nucleic acid could explain the infection, because, since 1982 and until now, the protein-only hypothesis has never been supported by any positive mechanism and experimental proof, and is becoming inadequate. Therefore, we have tried to elaborate an alternative hypothesis for the specific mechanism of infection in TSE. The transfer of at least a piece of nucleic acid from the infecting subject, perhaps the mRNA coding for the truncated protein described in human patients, could then reach the corresponding gene in the infected subject, where an endogenous reverse transcriptase would be able to integrate it. Once altered and stimulated, this last gene could, in turn, participate in the generation of nucleic acids able to code the generation of the truncated forms of the prion protein.

[The gene of human prion: reassessment of its features and pathogenic role]

After a detailed examination of some features of the human prion gene, we propose a reassessment of its role in the pathogenicity of the derived neurodegenerative diseases e.g. Creutzfeldt-Jakob's disease. The particular resistance of this gene towards physico-chemical agents is related to the relative abundance of the guanine and cytosine bases. Other features such as the paucity of CpG sequences, GC box, polyadenylic tail, direct and inverted repeats, all evoke those of retroviral LTRs. Finally, the presence of polypurinic and polyadenylic sequences, as well as that of a functional AP2 element coding a superantigen are all reminiscent of a parenthood of this gene with that of the murine virus MMTV, whose pathogenicity is based on the interaction between either endogenous or exogenous mutated viral forms. A similar biological behavior between, respectively the MMTV virus and the endogenous plus exogenous infectious forms of the prion is therefore suggested. All these clues are in agreement with the prominent data of the natural history of prion diseases, but il would be necessary that the prion protein should be associated with a nucleic acid belonging to its own gene and which would play a role in the animal or human illness, together with the endogenous prion gene. Thus, some exogenous forms originating from animals, e.g. bovine or perhaps ovine ones, could recombine with the human prion gene and would be responsible for the human illnesses.

[Measurement of the left ventricular mass using MRI with automatic determination of the endocardial and epicardial contours]

This study describes a method of automatic border detection of the left ventricular endocardium and epicardium associating three methods of segmentation (increase of region, border detection and adaptive threshold), applicable to the evaluation of ventricular mass and volume by magnetic resonance imaging. Despite slight underestimation, the spin-echo sequence used in 9 small pigs provided a value of left ventricular mass close to that observed ex vivo (r = 0.97, SEE = 6.05 g). Clinical validation using a rapid gradient-echo sequence was undertaken and compared with manual border detection carried out by three independent, trained operators. The study population included healthy subjects and patients with global or segmental left ventricular dysfunction with or without ventricular deformation. The correlations between automatic and manual detection were satisfactory both for calculation of left ventricular mass (r = 0.93, SEE = 13 g) and measurement of surfaces (r = 0.91, SEE = 1.4 cm2). The concordance of the two methods was confirmed by the Bland and Altman test. Cardiac magnetic resonance imaging may provide accurate and reproducible measurements of left ventricular mass within acceptable acquisition and image processing times for routine use. Although the clinical value of such a method is accepted both for establishing the prognosis and guiding management, studies of the cost/efficacy ratio should be undertaken to situate magnetic resonance imaging with respect to other non-invasive techniques of investigation of left ventricular function.

Plasma from patients exposed to ischemia reperfusion contains clastogenic factors and stimulates the chemiluminescence response of normal leukocytes

Clastogenic factors (CFs) are released by cells exposed to superoxide radicals and are found in various situations of oxidative stress. Certain of their components stimulate further superoxide production by competent cells, as shown with cytochrome c assay in previous work. In the present study, we report CF formation after ischemia reperfusion in patients undergoing coronary bypass surgery. Plasma ultrafiltrates, collected 20 min after reperfusion, had clastogenic properties in contrast to those collected before ischemia. We also show that the luminol-enhanced chemiluminescence response of neutrophils from healthy persons is increased when these cells are exposed to CF-containing postreperfusion samples from patients. Light emission was reduced to control values in the presence of superoxide dismutase. The burst of oxyradicals upon reperfusion is probably the initiating event of CF formation, which in turn leads to further oxyradical generation. This amplification process may explain why detectable levels of CF need a delay of at least 10 min. The activated state of neutrophils in ischemia reperfusion is at once a consequence and a source of CFs. Individual variation in the persistence of this clastogenic and leukocyte-activating material was observed. Therefore, antioxidants for prevention of ischemia reperfusion injury should be continued during the postoperative course.

A comparison of four assays detecting oxidizing species. Correlated reactivity of Fe(III)-quin2, but not Fe(III)-EDTA, with hydrogen peroxide

Quin2, a fluorescent calcium probe, has a low affinity for calcium in comparison to its affinities for transition metal ions. Chelation of ferric ion with quin2 strongly enhanced the formation of oxidizing species in the presence of bolus H2O2 as detected with four assays, electron spin resonance with the spin-trap DMPO, the deoxyribose assay, the DMSO assay, and plasmid DNA strand breakage. In comparison, Fe(III)-EDTA reacted with bolus H2O2 only as detected with electron spin resonance and deoxyribose assay, but not as detected with the two latter assays. The addition of reductants, like ascorbate or superoxide generated by hypoxanthine/xanthine oxidase, to Fe(III)-EDTA in the presence of H2O2 produced plasmid DNA strand breakage and strong reactivity in both the DMSO and the deoxyribose assays. Our findings suggest that the main oxidizing species produced in Fenton-type reactions is hydroxyl radical. However, the reaction between Fe(III)-EDTA and bolus H2O2 appears to be exceptional and dominated by a nonhydroxyl radical species.

Assessing and counteracting the prooxidant effects of anticancer drugs

The relationship between peroxide generation and respective cellular damage, triggering various biochemical consequences is first discussed. Then we review the prooxidant effects of various anticancer drugs including anthracyclines and bleomycin, platinum derivatives and the N- and S-mustards. We present and discuss some experimental results on peroxidase inhibition by drugs such as zinc salts, almitrine, deferoxamine, which had previously been tested as efficient in vivo treatment on chlormethine intoxication. In an overview we propose that not only ionizing radiations and anticancer drugs, but also promoters and initiators of cancer might all generate free radicals, in turn triggering oxidative processes generating endogenous peroxides, then probably amplifying the deleterious biological response. The possible limitations of drug therapies decreasing peroxide generation are presented.

[Problems in diagnosis of necrotic angiitis of the tongue]

Cutaneous and mucous lesions are uncommon and very often confusing in Horton's disease. In this case report, adding to this confusing aspect, the patient's medical history and clinical signs led the investigations in a totally different direction. Facing this isolated lesion of the tongue and the negative biopsy of the temporal superficial artery, the diagnosis of Horton's disease was finally confirmed by the good reaction following corticoid therapy.

Modulation of leucocyte activation in the early phase of the rabbit burn injury

Previous studies in burned patients have shown an early enhanced polymorphonuclear leucocyte (PMN) generating capacity for superoxide radical (O2.-), for the arachidonic acid (AA) lipoxygenase metabolite leukotriene B4 (LTB4) and for platelet activating factor-acether (PAF). These findings have been confirmed on a burn injury rabbit model. As we have suggested a pivotal role for an exaggerated initial (less than 36-48 h) neutrophil stimulation leading to a later (greater than 72 h) immuno-depression and anergy, we tried to modulate the early phase by drug therapy. A Ginkgo biloba extract (IPS200) injected i.v. in burned rabbits greatly reduced O2.- and LTB4 generation on A23187 challenge. IPS200 includes flavonoids and other polyphenols, inhibiting either arachidonic acid metabolism or PAF receptors, and may thus exert their modulating effect on PMN function in thermal injury.

An attempt to localize the vaccinating power of Klebsiella pneumoniae ribosomal preparations using saccharose-gradient ultracentrifugation

The study of the vaccinating power of ribosomal vaccines against Klebsiella pneumoniae led us to define the chemical nature which supports this protective activity. We tried to separate this support and the ribosomes by sucrose gradient ultracentrifugation. We isolated high protective membrane vesicles by this technique applied to salt-washed ribosomal preparations. When the ribosomal preparations were exposed to SDS, the protective activity was conserved all along the gradient, with no correlation with the ribosome concentration. The addition of bovine serum albumin to the ribosomal preparation focused the protective activity on the ribosomal peak. No correlation was observed between the response to capsular polysaccharide and the vaccinating power of the fractions.

[Antigenic similarity between polysaccharide and ribosomal vaccine extracts from Klebsiella pneumonia]

We describe in this report the vaccinating power of a polysaccharidic preparation from Klebsiella pneumoniae type I. The essential part played by this extract in the vaccinating capacities of the ribosomal preparations from the same bacterium is demonstrated.

[Isoproterenol test in coronary failure. Comparisons with exercise stress and coronary arteriography]

The results of Isoprenaline stress tests, exercise electrocardiography and coronary arteriography were compared in 90 patients suspected of having coronary insufficiency. The technique used was a continuous intravenous infusion starting with an initial dosage of 3.8 gamma/minute and increasing progressively until the heart rate was equal to or greater than 130/minute, and sustained for three minutes. The same criteria of "positivity" were used as in the exercise test but only electrical charges which persisted or appeared 3 minutes after stopping the infusion were taken into consideration. In this series the sensitivity and specifity of the Isoprenaline test was greater than the exercise test if coronary arterial narrowing equal to or greater than 50% is considered significant. The prognostic values of positive tests which are classified in three groups according to the severity of the coronary artery disease, and the value of the isoprenaline test in the diagnosis of moderate single vessel disease are emphasised.

[A gas chromatographic study of the composition of neutral and amino sugars in two neuraminidases, of bacterial and viral origin]

The neutral and aminosugar composition has been determined by gas-liquid chromatography for two neuraminidases, either bacterial, from Streptococcus pneumoniae, or viral, from Myxovirus influenzae A/Hong Kong/1/68.

[Familial myopathy with exclusively cardiac clinical expression]

A case is presented of a familial form of apparently primary cardio-myopathy with findings on investigation and histology which were in favour of a generalised subclinical muscular disorder: a raised serum creatinine phosphokinase, persistent carnosinuria on a vegetarian diet, and under the light microscope several features indicative of a myogenic dystrophic condition on deltoid biopsy. From their clinical features, these original cases may be classified somewhere between primary familial heart disease and the cardiac complications of myopathies. The value of the creatinine phosphokinase isoenzymes and of muscle biopsy in situations such as these is discussed.

[Isolation of Myxovirus influenzae surface antigens by affinity chromatography]

Surface antigens of Myxovirus influenzas A/r8/34 and A/Hong Kong/1/68 were isolated on Fetuin covalently attached to Sepharose. The amino acid composition of isolated neuraminidases was determined.