Occupational nuclear medicine: Trace element analysis of living human subjects

Summary Several trace elements are toxic when present in excessive amounts. Such overloads occur most commonly in the occupational setting, although some environmental exposures are also of concern. The relationship between chronic exposure and health effects is best explored with the aid of knowledge of the quantity of element in question stored in the body. In vivo elemental analysis can provide this knowledge non-invasively for a number of elements of toxicological importance. In vivo analysis presents specific challenges, particularly the fact that the body is an extended medium, giving rise to extensive scattering and absorption. Also of primary importance, the radiation dose must be kept as low as reasonably possible and must in every case be within the range of other diagnostic procedures. Both the incident radiation and the detected signal must have an adequate mean free path in human tissue. This means that neutron activation analysis (NAA) and X-ray fluorescence (XRF) are the two most studied techniques. For some elements, analytical methods are established while others are under active development. For still others, no promising technique is currently available. The most fully developed techniques are for lead and cadmium. For lead three different XRF approaches have been put forward, although one, ¹⁰⁹Cd excited K XRF is most widely used. For cadmium, both prompt gamma NAA and XRF have been developed to the extent of full human studies. Amongst elements for which application to human studies has begun or is likely to begin shortly are aluminum and manganese, both using NAA.     

Visual spatial memory is enhanced in female rats (but inhibited in males) by dietary soy phytoestrogens

Background  

In learning and memory tasks, requiring visual spatial memory (VSM), males exhibit superior performance to females (a difference attributed to the hormonal influence of estrogen). This study examined the influence of phytoestrogens (estrogen-like plant compounds) on VSM, utilizing radial arm-maze methods to examine varying aspects of memory. Additionally, brain phytoestrogen, calbindin (CALB), and cyclooxygenase-2 (COX-2) levels were determined.     

Lead post-mortem intake in human bones of ancient populations by (109)Cd-based X-ray fluorescence and EDXRF

In this work we measured the lead concentration in human bones of Middle Age by means of a portable X-ray fluorescence system based on ¹⁰⁹Cd radioactive source. The detection system consists on a Ge hyperpure detector. This system, conceived for in vivo Pb analysis in bone, is portable, non-destructive and is based on lead K lines detection.

The analysed bones are part of two collections of bones both from the end of Middle Age and submitted for some years to a lead polluted burial environment. The bones of one collection were buried initially on the soil in a convent, in Lisbon (Portugal) and further on, kept in a lead coffin for around 100 years. The second collection contains bones buried permanently on the soil around an old church on the south of Portugal. This place became a parking car for around 20 years.

In this work we studied the distribution of Pb in cortical bone, and trabecular regions from the outside surface to the inner part of the bone and the results are compared with the obtained ones by energy dispersive X-ray fluorescence (EDXRF).

The obtained values present a strong contamination of Pb in spongy bones kept in the lead coffin with concentrations ranging from 250 to 350 μg Pb/g bone mineral, and 4 to 7 μg Pb/g bone mineral for bones buried in the soil. Good agreement was observed between the results obtained by the two techniques.     

骨铅体内测量系统最佳测量位置的选择

^109Cd K XRF骨铅体内测量系统对体重指数大的对象测量所得的结果误差较大。测量时胫骨在探测器前的位置对测量结果误差的影响很大。采用模拟重指数大的被测对象的大体模,与原来的标准体模在探测器前不同距离时进行测量的对比分析表明,体重指数大的被测对象因其胫骨周围组织层较厚,造成康普顿计数大量增加。若胫骨与探测器的距离太近,仪器不能正常工作,致使X能谱图谱形畸变,得到不正确的结果。因此,在测量时,应保持胫骨在探测器前的距离为25mm,同时,应注意相干散射峰的峰位变化,保持仪器即时显示的死时间30%左右,以保证最后测量结果的精密度和准确度。     

The application of homotopy analysis method to solve nonlinear differential equation governing Jeffery–Hamel flow

In this paper Jeffery–Hamel flow has been studied and its nonlinear ordinary differential equation has been solved through homotopy analysis method (HAM). The obtained solution in comparison with the numerical ones represents a remarkable accuracy. The results also indicate that HAM can provide us with a convenient way to control and adjust the convergence region.     

Neuromodulation by soy diets or equol: Anti-depressive &; anti-obesity-like influences,age- &; hormone-dependent effects

Background  

Soy-derived isoflavones potentially protect against obesity and depression. In five different studies we examined the influence of soy-containing diets or equol injections on depression, serotonin levels, body weight gain (BW) and white adipose tissue (WAT) deposition in female Long-Evans rats at various stages of life [rats were intact, ovariectomized or experienced natural ovarian failure (NOF)].     

原位活体骨铅X射线荧光光谱分析

报道了应用X射线荧光光谱技术在中国本土获得的普通人群原位人体活体骨铅数据,发表了中国大陆普通居民的胫骨和根骨活体骨铅浓度及其研究结果。采用Pb的K系谱线进行了原位活体分析人胫骨和根骨骨铅含量。普通人群样本中所测骨铅含量加权平均值在0.4～22.7μg.(g骨矿物质)-1之间,不确定度在7.0～12.5μg.(g骨矿物质)-1之间,平均最小检出限20.3μg.(g骨矿物质)-1。在污染调查区居民中发现骨铅最高可达73.9μg.(g骨矿物质)-1。     

Evaluation of geometries appropriate for 125I in vivo bone strontium X-ray fluorescence measurement

Summary In this study, we present a significant improvement in the minimum detection limit (MDL) for strontium measurement in bone with X-ray fluorescence using ¹²⁵I as the excitation source. The improvement was achieved thanks to a new collimator in the 90 degree geometry and a different source positioning in the 180 degree geometry. The achieved MDL in the 90 degree geometry is 0.0426±0.0006 mg Sr/g Ca, which is 5.5 times better than the one previously reported. In the 180 degree geometry, the new source positioning improved the MDL from 0.118±0.004 to 0.0446±0.0009 mg Sr/g Ca.