Validation of reference materials for uranium radiochronometry in the frame of nuclear forensic investigations.

The results of a joint effort by expert nuclear forensic laboratories in the area of age dating of uranium, i.e. the elapsed time since the last chemical purification of the material are presented and discussed. Completely separated uranium materials of known production date were distributed among the laboratories, and the samples were dated according to routine laboratory procedures by the measurement of the (230)Th/(234)U ratio. The measurement results were in good agreement with the known production date showing that the concept for preparing uranium age dating reference material based on complete separation is valid. Detailed knowledge of the laboratory procedures used for uranium age dating allows the identification of possible improvements in the current protocols and the development of improved practice in the future. The availability of age dating reference materials as well as the evolvement of the age dating best-practice protocol will increase the relevance and applicability of age dating as part of the tool-kit available for nuclear forensic investigations.

Elemental composition in sealed plutonium-beryllium neutron sources.

Five sealed plutonium-beryllium (PuBe) neutron sources from various manufacturers were disassembled. Destructive chemical analyses for recovered PuBe materials were conducted for disposition purposes. A dissolution method for PuBe alloys was developed for quantitative plutonium (Pu) and beryllium (Be) assay. Quantitation of Be and trace elements was performed using plasma based spectroscopic instruments, namely inductively coupled plasma mass spectrometry (ICP-MS) and atomic emission spectrometry (ICP-AES). Pu assay was accomplished by an electrochemical method. Variations in trace elemental contents among the five PuBe sources are discussed.

A review of radiologically important trace elements in human bones.

The authors recently compiled and reviewed the literature for minor and trace elements in human bones and teeth as a part of an International Atomic Energy Agency (IAEA) study. Various aspects of elemental composition, analytical methodologies, quality assurance and quality control methods for hard tissue analysis were evaluated. Important data on selected radiologically important elements (Cs, Pu, Ra, Sr, Th, and U) in calcified tissue from various countries are discussed. The results of this compilation study suggest a need for new reference materials with matrix properties similar to bones including one with separated cortical and trabecular segments.

Prevalence of hypertension in schoolgoing children.

OBJECTIVE: To establish norms of blood pressure in children of different age groups, prevalence of hypertension and probable precipitating or aggravating factors. DESIGN: Cross sectional study. SETTING: Five thousand school children of Amritsar city. METHODS: Three readings of blood pressure were recorded. Norms for each year age group from 5-17 years of age were established. Persistently hypertensive children were investigated. Influencing factors like family history of hypertension and obesity were taken into account. RESULTS: The blood pressure increased with increase in age with a spurt in systolic blood pressure at the age of 12 years in both the sexes. There was no significant differences in the blood pressure of two sexes at various age groups except for systolic blood pressure at 5,6 and 16 years and for diastolic blood pressure at 9 and 13 years. Only 0.46% children were hypertensive. Children with obesity (n = 342) and family history of hypertension (n = 271) had hypertension in 3.5% (n = 12) and 5.9% (n = 16) cases, respectively as compared to other children in which the prevalence was only 0.23% and 0.14%, respectively. CONCLUSIONS: The norms for determining hypertension in this population were established and it's prevalence was 0.46%. Significant risk factors were obesity and family history of hypertension.

Neutron activation analysis of trace elements in motor neuron disease spinal cord.

Levels of 10 trace elements were analysed in autopsied lumbar spinal cords of 38 motor neuron disease patients and 22 control subjects using instrumental neutron activation analysis. Statistically significant elevations of iron, selenium and zinc, and depletions of mercury and cesium were found in the spinal cords of motor neuron disease patients compared with control subjects. No significant correlations were found between disease duration, clinical severity or lumbar motor neuron counts and iron and selenium levels, suggesting that accumulation of these elements occur early as well as late in the disease process and therefore are not a consequence of end stage pathology. Increased iron in motor neuron disease spinal cord could act to enhance formation of reactive oxygen species. Our study supports the free radical hypothesis of neuron degeneration in motor neuron disease.

Aluminum, calcium, and iron in the spinal cord of patients with sporadic amyotrophic lateral sclerosis using laser microprobe mass spectroscopy: a preliminary study.

We measured aluminum (Al), calcium (Ca), and iron (Fe) levels in neuronal cytoplasm and nucleus, capillaries, and neuropil in samples of ventral cervical spinal cord from 5 patients with sporadic amyotrophic lateral sclerosis (ALS) and 5 age-matched controls using laser microprobe mass spectrometry (LMMS). The concentration of Al was not altered in any area in the ALS samples. In contrast, Fe and Ca were increased 1.5-2-fold in the nucleus and cytoplasm of ALS neurons but not in capillaries and neuropil. These findings do not support the hypothesis that Al is enriched in spinal cord of sporadic ALS as has been reported for Guamanian ALS/Parkinson's dementia. The elevations of Fe in spinal neurons are consistent with reports of increased Fe in bulk samples of ALS spinal cord. The presence of increased Fe within spinal neurons may be significant in the pathogenesis of motor neuron degeneration by catalyzing the generation of reactive oxygen species within specific cells.

Iron, selenium and glutathione peroxidase activity are elevated in sporadic motor neuron disease.

Oxygen free radical damage is strongly implicated in the pathogenesis of familial motor neuron disease (MND) associated with mutation of the Cu/Zn superoxide dismutase gene, and may be relevant in sporadic MND. Selenium (Se) and iron (Fe) have important roles in free radical metabolism. Using neutron activation analysis we have demonstrated significant elevation of Se and Fe in lumbar spinal cord in MND cases (38) compared to controls (22). Analysis of enzymes involved in free radical scavenging showed a significant and specific increase in the activity of the selenoprotein enzyme glutathione peroxidase in MND spinal cord.