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The essential trace elements.

Essential trace elements are required by man in amounts ranging from 50 micrograms to 18 milligrams per day. Acting as catalytic or structural components of larger molecules, they have specific functions and are indispensable for life. Research during the past quarter of a century has identified as essential six trace elements whose functions were previously unknown. In addition to the long-known deficiencies of iron and iodine, signs of deficiency for chromium, copper, zinc, and selenium have been identified in free-living populations. Four trace elements were proved to be essential for two or more animal species during the past decade alone. Marginal or severe trace element imbalances can be considered risk factors for several diseases of public health importance, but proof of cause and effect relationships will depend on a more complete understanding of basic mechanisms of action and on better analytical procedures and functional tests to determine marginal trace element status in man.

Animals↗

Analytical procedures for diagnosis of trace element disorders.

Trace elements levels in tissues show changes in various diseases including inborn errors of metabolism. Such changes may be primary or secondary due to stress or diseases of the liver and gastrointestinal tract. Measurement of trace elements in these cases may be essential both for diagnostic and therapeutic purposes. Trace element measurements can also be useful in other areas of clinical interest including nutrition, toxicity and therapy with inorganic pharmaceutical agents. The available techniques for measuring trace elements in tissues are summarized and the various problems of each are discussed.

Electron Probe Microanalysis↗

Trace element absorption in infants as a foundation to setting upper limits for trace elements in infant formulas.

The bioavailability of the trace elements iron, zinc, copper and manganese from human milk is high compared to cow's milk and infant formulas. This high bioavailability may be explained by the presence of lactoferrin in human milk, which may facilitate iron and manganese uptake via an intestinal receptor for this protein. High concentrations of ascorbate and citrate may also facilitate uptake of trace elements from human milk and milk formulas, while a high concentration of casein in cow's milk and cow's milk formulas may limit trace element absorption from these diets. Trace element absorption from soy formula is low, mostly due to the presence of phytate but possibly also due to some protein fraction. Trace elements sharing absorptive pathways compete for uptake, and imbalances in the ratios between trace elements (Fe/Zn, Zn/Cu, Fe/Mn) in formulas may impair trace element absorption. These factors need to be taken into consideration when setting upper limits for trace elements in formulas. With our present knowledge, an upper limit for iron of 14 mg/l, for zinc, 12 mg/l, copper, 1.2 mg/l, and manganese, 0.6 mg/l are suggested. The capacity of infants to homeostatically adapt to varying intakes of trace elements needs to be further evaluated.

Female↗

Antioxidant enzyme activities of human peripheral blood mononuclear cells exposed to trace elements.

The trace elements copper, zinc, and selenium are important immune modulators and essential cofactors of the antioxidant enzymes. In the present study, the proliferative effect of human peripheral mononuclear cells (PBMCs) that have been exposed to copper, zinc, and selenium and the corresponding activities of antioxidant enzymes, namely superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase, were determined. Zinc and copper stimulated the PBMC proliferation in a dose-dependent manner within the dose range 25-200 micromol/L. SOD and GPx activities in PBMCs exposed to zinc were inhibited, whereas catalase activity was unaffected. All the three antioxidant enzymes in the cells exposed to copper were inhibited. Selenium exerted more potent inhibition of the cell proliferation while causing stimulation of the antioxidant enzymes at the lowest dose (25 micromol/L) than at the highest dose (200 micromol/L) tested. A significant negative correlation was observed between proliferation and antioxidant enzyme (SOD and GPx) activities in trace-element-exposed PBMC. The present findings substantiate the importance of trace elements as immune modulators and the involvement of enzymatic antioxidant system in the immune cell regulation.

Antioxidants↗

A survey of mineral status of soil, feeds and cattle in the Selale Ethiopian highlands. II. Trace elements.

The trace element status of crossbred Friesian x zebu (Boran) and local zebu cattle in the Selale highlands of Ethiopia was evaluated during the rainy and dry seasons of 1989 and 1990 in terms of the trace element content of soils, feeds, blood plasma and faeces on 25 randomly selected farms. Liver samples from animals of local breeds from a slaughter house were collected during the rainy and dry seasons of 1990 and analysed. Soil Fe and Mn were found to be high. Iron contents of all feeds were extremely high and Mn contents were higher than the dietary requirement. A large proportion of feed samples were deficient in Cu and zinc. There were wide variations in the concentrations of these elements among the soil and feed samples. Blood plasma Fe (P < 0.001) and Cu (P < 0.01) values differed significantly between the years. Plasma samples collected during 1990 contained lower mean Cu than 1989. The effect of season was statistically significant (P < 0.001) for all the trace elements. More than half of the animals were found to have low plasma Cu and Zn during the rainy season. Due to lack of any correlations between soil, pasture and blood plasma it is suggested that analyses of soils and pasture are not reliable for assessing the Fe, Cu and Zn status of grazing cattle in the highlands. Analyses of liver and blood appear to provide better indices.

Animal Feed↗

Recycling of trace elements required for humans in CELSS.

Recycle of complete nourishment necessary for human should be constructed in CELSS (Controlled Ecological Life Support Systems). Essential elements necessary for human support are categorized as major elements, semi-major elements and trace elements. Recently, trace elements have been identified from considerations of local diseases, food additive problems, pollution problems and adult diseases, consisting of Fe, Zn, Cu, Se, Co, F, Si, Mn, Cr, I, As, Mo, Ni, V, Sn, Li, Br, Cd, Pb, B. A review of the biogeochemical history of the earth's biosphere and the physiological nature of humans and plants explains some of the requirements. A possible route for intake of trace elements is considered that trace elements are dissolved in some chemical form in water, absorbed by plants through their roots and then transfered to human as foods. There may be a possibility that living things absorb some trace elements from atmosphere. Management and recycling of trace elements in CELSS is discussed.

Biological Evolution↗

Trace element content of commercial shampoos: impact on trace element levels in hair.

Popular shampoos were screened for their contents in trace elements, using ICP-MS detection in a semi-quantitative mode. Hair samples from volunteers were analyzed before and after hair washing with selected shampoos to demonstrate the effect of the contamination and the impact on occupational medicine. While some shampoos showed high levels of certain elements, the degree of contamination on the hair was found to be negligible. Only one shampoo tested, formulated with selenium sulfide, was found to seriously contaminate the hair.

Hair↗

Development of a procedure for the multi-element determination of trace elements in wine by ICP-MS.

An inductively coupled plasma mass spectrometric (ICP-MS) procedure has been developed for the determination of trace elements in wine. The procedure consists in simple 1+1 dilution of the wine and semi-quantitative analysis (without external calibration) using In as internal standard. Thirty-one elements at concentrations ranging from 0.1 mg mL(-1) to 0.5 ng mL(-1) can be determined by ICP-MS analysis with and without digestion. It was investigated whether a matrix effect observed for EtOH in the wine matrix can be overcome by application of a micro-concentric nebulizer with a membrane desolvator (MCN 6000). The results obtained for the MCN 6000 are compared with those obtained by use of a conventional Meinhard nebulizer. It is shown that the observed matrix effect can only be compensated by use of an internal standard for the Meinhard nebulizer, but not for the MCN 6000. Results for ICP-MS are compared with those obtained by total reflection X-ray fluorescence spectrometry (TXRF).

Ethanol↗

[Disorders in trace element status in cattle from the view of herd supervision. 1: Classical trace elements].

In a bipartite review the current knowledge about trace elements in cattle is described. The first part contains the classical trace elements iron, zinc, copper, manganese, molybdenum, iodine, selenium, cobalt, chromium and fluorine. For each trace element the following aspects are illustrated: physiological function, factors leading to deficiency or over-supply, symptoms of deficiency and poisoning and the diagnostic.

Animal Husbandry↗

Examination of paints by trace element analysis.

Trace element analysis using neutron activation analysis is effective and valuable, particularly in the examination of white household paint. Although physical appearance and resin composition are generally similar in these paint samples, trace element composition provides an effective way of distinguishing among them. In the case of automobile paint samples, NAA serves as an important additional technique for discrimination. The technique is important when sample sizes are very small. The technique developed takes a few minutes for sample preparation, a few hours of irradiation time (during which the examiner's presence is not required), and then a few minutes for counting and obtaining quantitative multielement concentration patterns. A technician can easily handle 30 to 50 samples per day.

Neutron Activation Analysis↗

Trace element reference values in tissues from inhabitants of the European Community. V. Review of trace elements in blood, serum and urine and critical evaluation of reference values for the Danish population.

The availability of accurate trace element reference values in human tissues represents an important indicator to the health status of the general population and occupational groups exposed to trace elements. The EURO TERVIHT project (Trace Element Reference Values In Human Tissues) aims to establish and compare trace element reference values in tissues from inhabitants of the European Community as baseline values for clinical/toxicological assessment studies (Sabbioni et al., 1992, Sci. Total Environ., 120: 39-62). In this context, one of the first steps considered is the critical evaluation (state of the art) of existing literature on trace element reference values in blood, serum and urine in the general population of each EC country. This paper reviews the Danish situation.

Adolescent↗

Trace element reference values in tissues from inhabitants of the European Community. VII. Review of trace elements in blood, serum and urine of the Belgian population and critical evaluation of their possible use as reference values.

The availability of accurate trace element reference values in human tissues represents an important indicator to the health status of the general population and occupational groups exposed to trace elements. The EURO TERVIHT project (Trace Element Reference Values In Human Tissues) aims to establish and compare trace element reference values in tissues from inhabitants of the European Community as baseline values for clinical/toxicological assessment studies (Sabbioni et al., 1992a,b). In this context one of the first steps considered is the critical evaluation (state of the art) of existing literature on trace element reference values in blood, serum and urine in the general population of each EC country. This paper reviews the Belgian situation.

Adolescent↗

Simultaneous multi-element analysis of trace elements in soil samples by means of high-resolution inductively coupled plasma sector field mass spectrometry (SF-ICP-MS).

The potential of SF-ICP-MS for trace element analysis in complex environmental matrices such as soil solutions was investigated. Spectral interferences found in mass spectra of soil matrices are presented in detail. Furthermore, the influences of single components of the soil matrix on the signal intensity of selected elements were studied. Detection limits of different elements are presented with respect to the composition of the matrix. A fast and accurate method for quasi-simultaneous determination of Al, Si, P, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, As, Se, Sr, Mo, Cd, Sn, Hg and Pb in aqueous soil extracts was established.

Journal Article↗

Trace elements in animals.

Trace element deficiency and toxicity in animals induces a wide variety of clinical effects although few are sufficiently specific to permit diagnosis without supporting investigation of changes in tissue trace element content or of the activity of metabolic processes influenced by trace element supply. Study of such trace element dependent processes has shown that extensive changes often arise before overt signs of disease appear. Some of these subclinical effects have pathological consequences and thus cannot be ignored when seeking correlations between geochemical anomalies and disease incidence. Many past estimates of the quantitative requirements of animals for the essential trace elements are imprecise. Although recent work is providing clearer definition of requirements, many common dietary components have a marked influence upon the efficiency with which such elements can be utilized from the diet. Recent evidence indicates that such antagonists influence both the absorption and the subsequent fate of essential and toxic elements in body tissues and these processes have to be taken into account when investigating the aetiology of disorders believed to be attributable to anomalies in trace element supply. Their existence is not always detectable if attention is confined to the trace element analysis of body tissues or to the nature of clinical lesions. Provided the complexity of soil-plant-animal relations with respect to trace element supply is fully recognized in the interpretation of data, the geochemical approach to the initial recognition of areas associated with a high risk of anomalies in trace element supply to animals and man has considerable potential value. This is already apparent from investigations upon the incidence of trace element problems in animals. As yet, its validity for similar purposes in man is less fully established.

Animals↗

Trace element uptake by L-cells as a function of trace elements in a synthetic growth medium.

The concentration of trace elements in L-cells has been studied as a function of the trace metal content of the growth medium. Cells were cultured in synthetic media which contained varying trace amounts of the elements manganese, iron, cobalt, copper, zinc and molybdenum. The cellular concentration of the of the elements potassium, iron, copper and zinc were then determined. It was found that the cell accumulates trace metals at a different rate than they are made available. Deficiencies in zinc could be "induced" in the cell by increasing the concentration of iron, manganese and cobalt; cellular iron deficiencies were observed at larger medium concentrations of zinc, manganese, copper and cobalt. Trace metal uptake by the cell was seen to parallel the utilization by multicellular organisms.

Cobalt↗