J. J. M. de Goeij

Losses of silver, arsenic, cadmium, selenium and zinc traces from distilled water and artificial sea-water by sorption on various container surfaces

Abstract Sorption losses were studied for Ag. As, Cd, Se, and Zn at a concentration level of 10-7 M from distilled water and artificial sea-water during storage in containers made of borosilicate glass, high-pressure polyethylene, or polytetrafluoroetbylene. Apart from pH (1, 2, 4, and 8.5) and storage time (1 min to 28 days), special attention was paid to the effect of the ratio of inner container surface to sample volume. The results are compared with literature data. In addition, a survey is given of literature references on sorption of 41 elements from aqueous solutions under different experimental conditions.

A new approach to target chemistry for the iodine-123 production via the 124Te(p, 2n) reaction.

Abstract A method is described for a routine production of sizeable quantities of iodine-123 for medical diagnosis. The iodine-123 is produced via a (p, 2n) reaction on enriched tellurium-124 targets. Results are presented for relevant excitation functions. A new approach to target chemistry—comprising target preparation, separation of tellurium and carrier-free radioiodine, and target-material recovery—is presented. Irradiation techniques and chemical procedures are described in some detail.

The mechanism of interaction between cisplatin and selenite

Cisplatin is a widely used antitumor drug, highly effective in the treatment of several tumors. Cisplatin exerts its antitumor activity through an interaction with DNA, which results in the formation of bidentate adducts. An important side-effects of cisplatin is nephrotoxicity. Selenite can reduce the nephrotoxicity of cisplatin without reducing the antitumor activity of the drug. We have studied the mechanism of selenite protection against cisplatin-induced nephrotoxicity. The protection correlates with higher levels of selenium in the kidney (about eight times) and with higher levels of glutathione in the kidney, both compared to tumors. Selenite is metabolized into selenols, specifically into methylselenol and glutathionylselenol; this bioactivation of selenite into selenols is a glutathione-dependent process. HPLC with on-line radioactivity detection of 195mPt showed that methylselenol is capable of forming a complex with cisplatin in vitro. 1H-NMR gave evidence that the complex contains one or more Pt-Se-CH3 bonds. Attempts to obtain further structural information by Desorption Chemical Ionization and Fast Atom Bombardment mass-spectrometry failed. It is proposed that the formation of a cisplatin-selenol complex also takes place in vivo, especially in the kidney, thereby preventing cisplatin exerting its nephrotoxic activity.

Extended automated separation techniques in destructive neutron activation analysis; application to various biological materials, including human tissues and blood

An automated post-irradiation chemical separation scheme for the analysis of 14 trace elements in biological materials is described. The procedure consists of a destruction with sulfuric acid and hydrogen peroxide, a distillation of the volatile elements with hydrobromic acid and chromatography of both distillate and residue over Dowex 2X8 anion exchanger columns. Accuracy, precision and sensitivity are tested with reference materials (BOWEN’s kale, NBS bovine liver, IAEA materials dried animal whole blood, wheat flour, dried potatoes, powdered milk, oyster homogenate) and on a sample of pooled human blood. Blank values due to trace elements in the quartz irradiation vials are also discussed.

Problems in current procedures for establishing recommended values of trace-element levels in biological reference materials

Abstract Approaches for establishing recommended values of trace-element levels in biological reference materials are discussed. Values of manganese, copper, chromium and cobalt in IAEA Milk Powder A-11 are used as an illustration. Performances of techniques currently applied in the analysis of biological materials for elements occuring at very low levels are evaluated. It is shown that statistica procedures alone are insufficient in some cases to arrive at recommended values without consideration of the analytical parameters involved.

Large-sample neutron activation analysis: Present status and prospects

Neutron activation analysis is attractive for trace-element determinations in large samples. Facilities for reactor irradiation and γ-ray spectrometry of kilogram-size cylindrical samples are described. The thermal neutron flux is ca. 5·1012m−2·s−1 with aΦth/Φepi>104, so neutron self-thermalization can be neglected. The correction for the neutron attenuation within the sample is derived from measurement of the neutron flux depression just outside the sample. Correction for γ-attenuation in the sample is performed via linear attenuation coefficients derived via transmission measurements. Also the natural radioactivity in the sample is taken into account. Examples are given of materials to which large sample INAA has been applied successfully, and further lines of development and exploration are indicated.

Selenium levels in blood and plasma, and glutathione peroxidase activity in blood of breast cancer patients during adjuvant treatment with cyclophosphamide, methotrexate and 5-fluorouracil

Glutathione peroxidase activity in whole blood and selenium levels in whole blood and plasma from breast cancer patients, were measured during combination chemotherapy with cyclophosphamide, methotrexate and 5-fluorouracil. No significant change in either glutathione peroxidase activity or selenium levels was observed. Comparison with matched controls showed no significant differences for either parameter.

Cisplatin-induced changes of selenium levels and glutathione peroxidase activities in blood of testis tumor patients

Haematocrit and glutathione peroxidase activity in blood, as well as selenium levels in blood, erythrocytes and plasma, were determined in 15 patients during four courses of cisplatin combination treatment for testicular teratoma. The haematocrit steadily declined, necessitating frequent blood transfusions during or after treatment. For patients without blood transfusions during treatment the reduction of the haematocrit averaged 40%. Glutathione peroxidase activity in blood declined also; for patients without blood transfusion the reduction was 30%, which is fully explained by the decrease of the haematocrit. The enzyme activity per volume of erythrocytes remained constant during the treatment. Erythrocyte selenium level did not change significantly, but plasma selenium levels of all patients dropped within each course of chemotherapy, and progressively with each subsequent course. Between cycles the levels were largely restored to almost normal values. These results may be explained by a decreasing availability of selenium in the body to maintain the normal plasma level, due to increased retention of cisplatin in tissues and subsequent alteration of selenium metabolism.

A search for losses of chromium and other trace elements during lyophilization of human liver tissue

Abstract Human liver tissues were investigated for possible trace-element losses during lyophilization by comparison of concentrations in lyophilized and untreated (wet) samples. When destructive neutron activation analysis (n.a.a.) was used, no significant losses were observed for As, Br. Cd. Co. Cr, Cu. Fe, Hg, Mo, Sb, Se, and Zn. The advantages of n.a.a. over radiotracer techniques for studies of trace-element volatility are discussed.

The reactions 77Se(p, n) and 78Se(p, 2n) as production routes for 77Br

Abstract Yield curves were measured for the 77 Se( p , n ) 77 Br reaction and the 78 Se( p , 2 n ) 77 Br reaction involving isotopically enriched selenium targets. Also the contamination levels due to 76 Br and 82 Br were measured. The suitability of both reactions for production of 77 Br for use in nuclear medicine is shown. The possibility of a dry-distillation technique for both a carrier-free separation of 77 Br from irradiated enriched selenium targets and a quantitative recovery of the selenium is discussed.