Iodine concentration in different human brain parts.

Iodine is one of the most important essential elements as demonstrated by the fact that its deficiency can cause goitre. Nevertheless, quantitative data on its concentration in biological materials, especially in the human brain, are scarce. There is therefore a demand for accurate and reliable information on iodine in these types of samples. The purpose of the present work was to determine the concentration of total iodine in some control human brain parts by rapid radiochemical neutron activation analysis. Our second goal was to determine I distribution between lipid fraction and in brain tissue without lipid by applying two types of solvent extraction methods. The results were checked by the analysis of biological standard reference materials with certified or literature values for iodine and good agreement was found.

In vitro abrasion using an air-powder polishing device and its quantification by radiotracer measurement.

OBJECTIVES: This study was conducted to examine the assessment of abrasion of two different materials after neutron activation. METHODS: A fissure sealant material (Fissurit F/VOCO with a compressive strength of 235 MPa) and a glass ionomer cement (Aqua Ionofil/VOCO with a compressive strength of 170 MPa) were activated by irradiation with neutrons. Subsequent measurements of the full-energy-peak (FEP) (1368.55 keV of 24Na) were made of the sample materials before and after abrasion via exposure to the air-powder polishing to accurately describe substance loss. RESULTS: Abrasion varied more than three-fold between the two materials. SIGNIFICANCE: Neutron activation and radiotracer measurement allows the quantification of abrasion effects in different materials. In comparison with other current methods its use may allow a superior measurement accuracy and precision in determining the abraded mass.

Cytoprotection against lipid hydroperoxides correlates with increased glutathione peroxidase activities, but not selenium uptake from different selenocompounds.

Cells cultivated under standard conditions were highly deficient in tocopherol, selenium, and glutathione peroxidase (GPx) activities. We investigated whether and to what extent the addition of different selenocompounds to growth media would alter biochemical, physiological, and pathophysiological parameters of cultured liver cells. Cellular uptake of selenium, GPx activities, and cytoprotection were measured and compared in human hepatoma cells (HepG2). Selenite and selenocystine were Se donors of high bioavailability (i.e., with these culture supplements, the increased Se uptake, induction of GPx isoenzymes, and protection of treated cells from lipid hydroperoxides were well correlated). In contrast, selenium from selenomethionine was incorporated into cellular proteins but had no effect on GPx activities or cytoprotection. The data show that not all selenium donors provide selenium, which is bioactivated to act as antioxidant. Thus, cellular selenium content, in general, did not correlate with cytoprotective activity of this trace element. However, cellular GPx activities at different times, with different concentrations, and with different Se donors always correlated with protection from lipid hydroperoxides and may, thus, represent a more reliable parameter to define adequate Se supply.

The TSH-dependent variation of the essential elements iodine, selenium and zinc within human thyroid tissues.

Instrumental Neutron Activation Analysis was used in order to measure iodine, selenium and zinc concentration in thyroid samples. A pair of samples of normal and nodular tissue were collected from the thyroid gland from 72 patients selected on the basis of pathological criteria (44 cases of multinodular goiter, 12 of chronic lymphocytic thyroiditis (CLT), 6 of thyroid adenoma (TA) and 12 of thyroid cancer (TC)). The check for tissue homogeneity and sampling error was performed by means of the coefficient of variation (CV%) of the elements in replicate samples of normal and altered tissues. High CV% values (> 15%) for iodine reflected a functional variability in thyroid follicles, while low CV% values (< 10%) for selenium and zinc indicated that the composition of selected tissues was rather homogeneous. The variation of the element's concentration was compared in normal and altered tissues. The mean element concentrations had values close to those already reported in the literature; furthermore, our patients had marginal iodine and selenium deficiency. Both normal and nodular tissues in CLT showed statistically significant lower zinc values as compared with the other thyroid diseases. To evaluate the thyroid function, thyroid stimulating hormone (TSH) and thyroxine (T4) levels were measured in the serum of patients. Two arbitrary serum-TSH threshold levels (TSH < 1.0 and > 4.0 mU/L) were introduced in order to classify, respectively, hyperthyroidism and hypothyroidism, as well as euthyroid conditions (1.0 < TSH < 4.0 mU/L), and each patient was assigned to one of these groups. The influence of TSH in the variation of the concentration of iodine, selenium and zinc in normal and altered human thyroid tissues was significant.

Helminths of wintering geese in Texas.

Ten Canada geese (Branta canadensis), 24 snow geese (Chen caerulescens) and 22 white-fronted geese (Anser albifrons) from coastal Texas (USA) were examined for helminths. Three cestode, seven nematode, and three trematode species were collected. Gizzard nematodes (Amidostomum anseris, A. spatulatum and Epomidiostomum crami) infected 53 of 54 birds. Gross lesions were not attributed to helminth infections and the host population does not appear to be impaired by them.

Protein-bound selenium in the seeds of coco de mono (Lecythis ollaria).

High selenium concentrations (7-12 g/kg dry mass) were found in the seeds of the selenium-accumulator plant coco de mono (Lecythis ollaria). In order to obtain information on the protein-bound part of selenium in extracts of these seeds, dialysis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were used combined with neutron activation analysis. Extractions were carried out at pH 4.5 and 7.5. In both cases about 90% of the element was dissolved. Of the extracted selenium only 9% was shown to be firmly bound to proteins at pH 4.5 and 29% at pH 7.5. For the protein-bound selenium, concentrations of 0.7 g and 2.4 g per kg of seeds and 40 and 25 g per kg of extractable protein were determined at pH 4.5 and 7.5, respectively. By analyzing the protein fractions separated by SDS-PAGE the element was found to be present in extremely selenium-rich proteins with molecular masses below 20 kDa.

A selenium-containing phospholipid-hydroperoxide glutathione peroxidase in Schistosoma mansoni.

The 100000Xg supernatant parasite platyhelminth Schistosoma mansoni exhibits a glutathione peroxidase activity with the substrate phosphatidylcholine hydroperoxide. Purification yielded a protein of 20 kDa molecular mass both on gel filtration column chromatography and SDS/PAGE, thus suggesting that S. mansoni expresses a protein similar to the mammalian selenoenzynic phospholipid-hydroperoxide glutathione peroxidase. Kinetic analysis and substrate specificity corroborated this assumption, the second-order rate constants for the oxidation of the ground-state enzyme (k+1) being higher with phosphatidylcholine hydroperoxide than with other peroxide substrates, such as cumene liydroperoxide or H2O2, and quantitatively similar to those of mammalian phospholipid-hydroperoxide glutathione peroxidase. Partial sequencing of the protein and selenium measurement by neutron activation analysis established that the purified peroxidase corresponded to the product of the S. mansoni gene previously reported and supposed to encode a selenium-containing glutathione peroxidase [Roche, C., Williams, D. L., Khalife, J., LePresle, T., Capron, A. & Pierce, R. J. (1994) Cloning and characterization of gene encoding Schistosoma mansoni glutathione peroxidase, Gene 138, 149 - 152]. S. mansoni thus contains a scienoperoxidase sharing molecular mass, catalytic efficiency and substrate specificity with phospholipid-hydroperoxide glutathione peroxidase, dismantling the concept that those enzymes are unique to vertebrate organisms.

Speciation of Se, Fe and Zn in Human Milk Whey: The use of Instrumental Neutron Activation Analysis (INAA) to corroborate element profiles measured with Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES).

In human milk trace elements normally exist in a form which can easily be absorbed by the newborn infant. For investigations of the bioavailability of trace elements it is necessary to carry out a speciation analysis of the elements of interest. An independent analytical method has been used for the quality control of the shape of the element profiles obtained from the speciation analysis of Se, Fe and Zn in individual samples of human milk whey after chromatographic separation. For the element detection in the untreated milk fractions Instrumental Neutron Activation Analysis (INAA) was chosen as the reference method. Element distribution patterns have been obtained with Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) using on-line digestion of the fraction, reduction and hydride formation of Se ("T"-mode). Prior results are compared with those obtained by means of element detection in the untreated fractions ("U"-mode) with ICP-AES. The elution profiles of Se, Fe and Zn in human milk whey obtained by means of ICP-AES detection using the "T"-mode show good agreement with the distribution patterns obtained with INAA. Recoveries of 103% for Fe, 86% for Zn and 87% for Se were obtained. The element distribution patterns of Fe and Zn obtained with ICP-AES speciation using the "T"-mode also show good agreement with those obtained by means of ICP-AES using the "U"-mode.

[Determination of minerals and trace elements in selenium tea from the Enschi district, People's Republic of China, and in its infusions using inductively coupled plasma-atomic emission spectrometry, graphite furnace atomic absorption spectrometry and instrumental neutron activation analysis]. / Bestimmung der Mineralstoffe und Spurenelemente in Selen-Tee aus dem Enschi-Gebiet, VR China, und in dessen Aufguss mittels ICP-AES, GFAAS und INAA.

The Enschi district in Hubei province, Peoples Republic of China is geochemically one of the two seleniferous regions, producing both selenium (Se) black tea and the Se green tea. Three samples of green tea with different Se contents and one non-Se tea were analysed. The following mineral and trace elements were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES): K, Ca, Mg, Na, P, S, Al, Mn, Fe, Ba, Sr, Co, Ni, Cu, Zn, Mo, and Cr. Except for Mo, Co, and Cr, all other elements in infusions of the samples analysed were also measured, since their concentrations are lying over their detection limits. The Se content in the tea samples and in the infusions were measured with graphite furnace atomic absorption spectrometry (GFAAS). The accuracy of Se determination was tested by measuring untreated tea samples with instrumental neutron activation analysis (INAA). The Se content in the measured samples was 1 to 8.5 micrograms/g. In addition to Se, 17 other elements were measured in the tea samples and 14 others in the infusions. With this data the extractable part of this elements in the infusion were calculated. Up to 10% of the Se was found in a first infusion.

Combination of neutron activation analysis, tracer techniques, and biochemical methods in the investigation of selenium metabolism.

In several studies on rats, the metabolism of selenium was investigated. The quantitative determination of the element was carried out by instrumental neutron activation analysis. For in vivo tracer experiments, 75Se-labeled selenium compounds were used. In addition to these methods, procedures for the measurement of the selenoenzyme glutathione peroxidase, and for the investigation of other selenoproteins, were applied. In this way, information on the specific pools and sites of action of the element, on biologically important selenoproteins and the regulation of the selenium metabolism, was obtained.

The influence of renal insufficiency on caesium metabolism in man and rat (with a note on the Cs content of some biological standard materials).

Caesium was measured by instrumental neutron activation analysis in blood plasma and erythrocytes of persons suffering from renal disorders and in age-and sex-matched controls. The disease was at an early stage of development, the patients having creatinine plasma values below 1000 mumol/l. None of them had been dialysed. In a group of 5 patients with plasma creatinine below 250 mumol/l no changes in the blood caesium contents could be observed, but in a group of 17 with plasma creatinine between 250 and 1000 mumol/l the caesium level in the plasma was increased by 70% and in the erythrocytes by 50%, compared to the controls. An effect of renal insufficiency on the caesium metabolism was also observed in rats, in which 5/6-nephrectomy led to increases in the caesium tissue levels (muscle 30%; spleen 25%; pancreas 100%). However, as in the animals the element content in blood plasma and erythrocytes remained unchanged, it is not clear to what extent the nephrectomized rat can be used as a model in the investigation of relations between chronic uraemia and caesium metabolism. It can therefore not yet be decided whether the changes in the blood caesium levels in the patients are due to a decrease in renal excretion or are only a secondary effect of unnoticed changes in dietary habits. The increase in caesium levels suggests, however, that in the first stages of the disease the patients may receive higher radiation doses from the radioisotopes of caesium than the normal population does in the case of environmental or industrial exposure.

Aluminium load in patients with analgesic nephropathy.

It is well-known that plasma aluminium in haemodialysis patients increases with the amount of aluminium hydroxide consumption. In a cross-sectional study at our haemodialysis centre we found that mean plasma aluminium levels are significantly higher in haemodialysis patients with analgesic-associated nephropathy (AAN) than in haemodialysis patients with other kidney diseases (controls) (logarithmic mean +/- SD = 1.93 +/- antilog 0.32 versus 1.21 +/- antilog 0.31 mumol/l; p = 0.001). AAN patients consume a significantly higher amount of aluminium-containing phosphate binders than the controls (21 +/- antilog 0.3 versus 13 +/- antilog 0.4 g/kg body weight/year; p = 0.007). These findings may be explained by the higher incidence of peptic ulcer disease in AAN patients, since hyperacidity decreases the phosphate-binding effect. Analgesic patients also need more aluminium-containing stomach medication than do patients with other kidney diseases (0.21 +/- antilog 1.15 versus 0.03 +/- antilog 0.87 g/kg body weight/year; p = 0.0001). A statistically significant correlation was obtained between bone aluminium and duration of phosphate binder consumption (r = 0.6459; n = 14; p less than 0.05). There was no correlation between plasma aluminium and bone aluminium. Anaemia was more pronounced in the AAN patients than in the others (mean haemoglobin 8.4 +/- 1.9 vs. 9.2 +/- 2.0 g%; p less than 0.02). Dialysis dementia was observed in 4 AAN patients. We conclude that the higher plasma aluminium levels in AAN patients represent a higher aluminium load which may be followed by higher aluminium toxicity.

The suitability of the iliac crest biopsy in the element analysis of bone and marrow.

Bone samples from the iliac crest were taken from 20 subjects and the content of some trace elements (iron, zinc, selenium, cobalt, strontium, aluminium, scandium, rubidium and fluorine) and of the matrix elements calcium, phosphorus and sodium was determined. The samples were taken in accordance with Burkhardt's method, which is often used in hospital for bone biopsies. The sources of errors occurring during the analysis of trace elements using this clinical procedure and the contamination of the samples by blood and the surrounding tissue are discussed. In-vivo activation analysis is also discussed as an alternative method of element analysis of the skeleton.

Non-destructive neutron activation analysis of aluminium and phosphorus in bone biopsies.

The level of aluminium and phosphorus in bone was measured by neutron activation analysis via the short lived radionuclide 28Al. The contribution of both elements to the 28Al activity could in each case by determined after the samples had been irradiated twice, once with a cadmium shield around the irradiaion position. The samples were analysed non-destructively and may later be used for further tests. Limits for the quantitative determination of aluminium and phosphorus in usual bone biopsies were calculated.

Effect of 1,25(OH)2D3 and 24,25(OH)2D3 on experimental rickets.

The vitamin D3 metabolite 1,25(OH)2D3 alone may not be able to reverse defective bone mineralization, while a combination with another metabolite, 24,25(OH)2D3 might be necessary to display the known effect of vitamin D on bone. Growing rachitic rats were treated with 25 ng vitamin D3/d, 10 ng 1,25(OH)2D3/d, 10 ng 24,25(OH)2D3/d, 5 ng 1,25(OH)2D3/d and 5 ng 24,25(OH)2D3/d in combination and 10 ng 1,25(OH)2D3/d and 10 ng 24,25(OH)2D3/d in combination. After 10 days of treatment the epiphyseal plate width of femura and the distance of tetracycline fluorescence bands were measured microscopically on undecalcified sections of the bone. The calcium content of femur epiphysis was measured by neutron activation analysis. Neither parameter showed on greater effect of the combination of 1,25(OH)2D3 and 24,25(OH)2D3 than of 1,25(OH)2D3 alone.

Non-destructive neutron activation analysis of copper in liver samples and other biological materials.

Neutron activation analysis via the short-lived radionuclide 66Cu was applied in the determination of the level of copper in tissues. With this procedure the samples are analysed non-destructively and can therefore be used for further histological tests. The applicability of the method in the analysis of biopsy samples is discussed.