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A letter to the editor is presented in response to the article "Effect of the Inflammatory Response on Trace Elements and Vitamin Status," by P. Galloway.

A method is described for the direct determination of selenium in serum or plasma by electrothermal atomic absorption spectrometry with deuterium-arc background correction. Samples are diluted (1 + 2) with a modifier containing palladium nitrate and Triton X-100. Samples are atomised from a L'vov platform in a pyrolytically-coated electrographite tube and peak area signals are measured. Direct determination is possible by using selenium standards matched to the physiological concentrations of sodium chloride, calcium and phosphate. The detection limit is 6 micrograms/L in the original sample. Precision at a selenium concentration of 97 micrograms/L was 2.2% RSD within batch and 3.0% RSD between batch. Accuracy is shown by (i) analysis of a Seronorm reference serum (value obtained 97 +/- 3 micrograms/L; recommended value 96 micrograms/L); (ii) recovery of added selenium (93.3 +/- 6.7% and 98.2 +/- 3.3% at additions of 30 and 60 micrograms/L, respectively) and (iii) comparison of results with mean of all laboratories in an external quality assessment scheme.

Determination of Cu, Fe, Mn and Zn in fresh bovine liver and BCR bovine liver and pig kidney reference materials, after digestion at 105 degrees C with nitric acid for various times, showed that the trace elements were completely released after heating for only 20 min. Centrifugation of the samples after digestion improved the separation from undigested fat. This partial-digestion method, based on heating about 0.2 g of sample with 2 ml of nitric acid for 20 min, was tested on a range of biological reference materials and on fresh bovine liver for the four elements. Comparison was made with results obtained after digestion by a recommended hydrogen peroxide--sulfuric acid digestion procedure. Results obtained by inductively coupled plasma atomic emission spectrometry or by flame and graphite-furnace atomic absorption spectrometry showed good agreement between the two digestion procedures, and results for the reference materials agreed well with the certified values. Between-batch precision was better than 4% for Cu, Fe and Zn at levels of 30 to 190, 210 to 320 and 100 to 140 micrograms g-1, respectively. For Mn, the precision varied between 7 and 14% for measured concentrations of 8 to 12 micrograms g-1. The partial-digestion procedure offers simplicity, speed, low cost and the ability to handle a large number of samples at the same time.

The combination of palladium/hydrogen matrix-modification and injection of samples into a graphite tube at 120 degrees has allowed the accurate determination of copper, iron, lead and nickel in biological reference materials (urine, milk powder and bovine liver). Palladium modification allowed the use of a standard ashing temperature of 1000 degrees for all four elements. Direct aqueous calibration was applied without the need for standard additions. The total heating cycle, from the start of sample injection, took 45 sec.

Two methods are described for the determination of copper in urine by graphite furnace atomic absorption spectrometry. The first, suitable for spectrometers capable of making good background correction at 325 nm, involves a direct determination against simple aqueous standards after 2 X dilution of the sample. The second requires no background correction and can be used when background correction is not available or is inadequate. The copper is extracted from the urine with ammonium tetramethylenedithiocarbamate into methylisobutylketone and the extract is analysed for copper. No significant matrix effect was observed for either method. Analysis of random urine samples from 16 normal subjects gave a mean concentration of 0.42 mumol/l with a range of 0.06--1.04 mumol/l.

Domestic water and whole blood samples were collected early in 1981 from two hundred volunteers living in the Glasgow area of Scotland, U.K. The concentration of lead in the water and blood samples, and of cadmium in the blood, was measured. The blood lead and cadmium concentrations were compared to those obtained in the Survey of 1979. There has been a fall in blood lead concentrations since the 1979 Survey. In contrast, the blood cadmium levels had remained similar. This diminution in blood lead concentration is attributed to a fall in water lead concentration caused by raising the pH of the water supply in the Glasgow area. The main determinant for cadmium in blood appears to be cigarette smoking habits, which had not changed.

The methods of provision of essential trace elements to patients receiving long-term home intravenous nutrition in the U.K. have been reviewed and their trace element status has been assessed. Over a 2 year period, 57 patients based on 15 hospitals throughout the country were studied. Although biochemical abnormalities of trace element status were frequent, related clinical complications were apparently rare. Zinc provision from commercial preparations generally required further supplementation. Copper requirements were variable. Manganese provision from trace element mixtures and chromium provision from contaminants of other parenteral nutrient solutions were excessive in many cases. Aluminium contamination is not significant in the nutrient solutions currently used in the U.K. The most common depletion state is for selenium which should probably be provided on a routine basis. The clinical consequences of long-term under- or over-provision of trace elements by the intravenous route requires further study.

A survey of nine elements of accepted clinical relevance has been performed on tissue sets comprising of kidney, liver, heart and muscle taken at autopsy from healthy individuals killed as the result of an accident. The concentrations are reported using tissue wet weight, dry weight and nitrogen content as frames of reference. This has allowed direct comparisons to be made with other studies without resort to the use of conversions, using average factors, between one frame of reference and another. Such conversions are shown to be unreliable and may generate spurious differences. The results obtained are largely consistent with those reported from studies in other parts of the world.

Data collected for the Edinburgh Lead Study have been used to investigate lead concentrations in children's naturally shed deciduous teeth. A within-child multiple-regression analysis has shown that the upper jaw has a higher concentration of lead than the lower, and that there is a gradient of decreasing concentration from the front to the back of the mouth. Even after the effects of jaw and tooth type have been allowed for, the concentration is still found to be negatively correlated with the weight of the tooth and with the age at which the tooth was shed. No statistically significant effects could be attributed to caries, fillings, or the incomplete resorption of roots. A single-valued index of tooth lead has been derived for each child, taking into account the fact that children gave different types of teeth.

In a low water aluminium area ( less than or equal to 0.4 micromoles/1) plasma aluminium levels were normal in 31 non-dialyzed and 7 peritoneally-dialyzed patients unless oral aluminium hydroxide was prescribed. Plasma aluminium levels were above normal in 26 patients on maintenance hemodialysis, but when aluminium hydroxide intake stopped there was a decrease in pre-dialysis plasma aluminium. Poor compliers (indicated by plasma phosphate levels) showed no change. Oral aluminium hydroxide can make a major contribution to plasma aluminium levels in patients with renal failure and should be treated with the same caution as high dialyzate aluminium. Post-dialysis plasma aluminium levels were always higher than pre-dialysis levels both on and off aluminium therapy despite the low dialyzate aluminium concentration. This rise may be due to tissue redistribution.

A child of 10 months with proven homocystinuria was found to be selenium depleted and we report the serial monitoring of replacement therapy. Selenium, as an enriched yeast preparation, equivalent to 50 mug on alternate days was required for maintenance. Indices of selenium status returned to normal in varying times. The child initially demonstrated an abnormality of an in vitro challenge by hydrogen peroxide to her erythrocytes, that returned to within normal limits with selenium therapy alone, the serum vitamin E concentration being normal.