Trace Element Interactions Research Articles

Interaction of trace elements in a longitudinal study of human milk from full-term and preterm mothers

Concentrations of 8 trace elements (Fe, Cu, Zn, Se, Br, Pb, Rb, and Sr) at different lactation time were measured by the PIXE multi-elemental technique. Time dependence and interelement correlations were studied. A total of 200 milk samples from 32 lactating mothers were supplied from 2 to 120 d after delivery of 26 full-term and 6 preterm infants. All elements showed a lognormal frequency-distribution. The Fe, Cu, Zn, and Se contents in preterm milk were found to be somewhat different with respect to full-term milk. Cu, Zn, Se, Br, Pb, and Rb concentrations declined with lactation time, both in pre- and full-term samples. Sr and Fe contents did not show any change with time. Detailed analysis of data by partial correlation and multiple regression methods was performed. No substantial differences between preterm and full-term samples were found in the results of partial correlation analysis. Cu and Zn were found to be correlated with lactation time, whereas the measured time dependence for the other elements has to be attributed to the effect of the existing interelement correlation. All the measured elements appeared to be correlated with at least one other element. In particular, Se was inversely correlated with Zn and directly with Cu. The zinc and copper contents in milk can therefore depend on the variation in the mother selenium intake.

Carbohydrates and dental health

Carbohydrates, together with fats and proteins, provide the necessary energy needs for humans, and constitute, therefore, an integral part of a normal diet. An etiological model for caries that considers local and host factors is presented, highlighting the interaction of bacteria, saliva, minerals, and trace elements with food residues and with other intrinsic environmental and behavioral characteristics of the host. Consideration of this complex multifactorial etiology precludes the identification of any one factor as the only one to be singled out in prevention and management of oral disease. Sugar is, unquestionably, a risk factor for caries, and, therefore, its total substitution with energetic or nonenergetic sweeteners has been found useful. However, partial substitutions of fermentable sugars may have limited practical value in controlling caries prevalence. Caries preventive programs that take into consideration not one, but several etiologic factors, will be effective and beneficial to the general population.

Effect of calcium, copper, and zinc levels in a rapeseed meal diet on mineral and trace element utilization in the rat.

Mineral and trace element interactions were studied in a balance trial with rats. Calcium, copper, and zinc were supplied to a rapeseed meal diet in a factorial design. Animals were fed ad libitum, and absorption, excretion, and retention of the elements were evaluated either as fractions of total intake or in relation to nitrogen retention to account for differences in food intake and lean body mass increment. The intrinsic content of minerals and trace elements was sufficient to support growth at a rate that could be expected from the rapeseed protein quality. However, when calcium was included in the diet, the intrinsic dietary level of zinc appeared to be limiting, despite the fact that the zinc level was twice the recommended level. Additional zinc supply reversed growth impairment. This calcium-zinc interaction is believed to be owing to the formation of phytate complexes. Calcium addition influenced the calcium, phosphorus, magnesium, zinc, and iron--but not the copper--balances. The addition of calcium reduced the availability of the intrinsic zinc, whereas no effect was seen in the zinc-fortified groups. The availability of intrinsic copper was in a similar way significantly impaired by addition of dietary zinc, whereas copper-supplied groups were unaffected by zinc addition. Intrinsic iron availability was also dependent upon zinc addition, although in a more ambiguous way. Thus, addition of extrinsic minerals to a diet high in phytate can result in significant impairments of growth and mineral utilization.

Cobalt(II) interactions with near-coastal marine sediments

Chemical speciation of trace metals in aqueous systems is determined by a variety of competitive reactions. Sediments act as sinks for many trace elements, forming surface complexes and otherwise surface-related compounds. Reactions between dissolved trace metals and functional groups at sediment surfaces can be described as coordination reactions similar to those occurring in solution. Factors inherent to both sediment and solution influence the trace metal speciation. These factors include pH, type of mineral, surface area and/or density of reactive surface sites, complexing ligands, and competing ions. The relative importance of some of these factors was studied using an isotope dilution technique. Coastal sediment samples from the Gulf of Mexico were used as the solid matrix. Models developed for pure minerals were used here to (empirically) describe the complex assemblages of minerals in the natural sediment samples. The adsorption experiments showed that cobalt uptake by marine sediment samples followed a two-step time dependency. The initial fast step lasted about five to ten days and the subsequent slow step continued after more than 100 d of equilibration. The pseudoequilibrium reached during the fast step was modeled with an equilibrium model, while the twostep behavior was modeled with a time-dependent model. The two models are related by the reaction stoichiometries. It is believed that the experimental as well as the modeling approach taken in this study, although empirical when used for natural settings, is much more powerful than the use of traditional means to describe trace element interactions with natural solid phases.

Metabolic interactions of trace elements

Metabolic interactions of trace elements

Toxic Effects of Trace Element Excess

Excesses of many trace elements can cause direct toxic effects to cattle as well as indirect effects that can cause a secondary deficiency of other trace elements. Clinical signs may vary from poor growth and feed utilization to neurologic disorders. Toxic effects vary with the specific trace element in question, the total amount of that element in the diet, the age and condition of the animal, and the presence or absence of certain other dietary components. A diagnosis of toxic trace element interaction is based upon compatible clinical signs in affected animals as well as supporting chemical analyses.

Mineral Interactions Relevant to Nutrient Requirements

The negative interaction of metal ions is one of the major dietary factors that causes low bioavailability of these nutrients. Interactions of nutritional significance include sodium-potassium, calcium-magnesium, manganese-iron, iron-copper, and zinc-copper. These interactions reach potential importance when the first metal of each pair listed above is in excess and the other is at the lower limit of requirement. The trace element interaction of highest practical significance in human nutrition is the negative effect of excess zinc on copper bioavailability.

Mineral Interactions Relevant to Nutrient Requirements

The negative interaction of metal ions is one of the major dietary factors that causes low bioavailability of these nutrients. Interactions of nutritional significance include sodium-potassium, calcium-magnesium, manganese-iron, iron-copper, and zinc-copper. These interactions reach potential importance when the first metal of each pair listed above is in excess and the other is at the lower limit of requirement. The trace element interaction of highest practical significance in human nutrition is the negative effect of excess zinc on copper bioavailability.

Trace metal interactions involving the intestinal absorption mechanisms of iron and zinc.

The basis for absorptive trace element interactions is given by the statement of Hill & Matrone (1970) that “those elements whose physical and chemical properties are similar will act antagonistically to each other biologically”. Although the direct antagonistic competition of chemically-alike metals is a straightforward concept, an important associated view is that dietary preconditioning with an excess or deficiency of an element may reveal interactions with the metabolism of chemically-similar metals.

Some Recent Developments in the Characterization of Estuarine Particulates

Estuaries and coastal zones are characterised by very varied chemical and physical environments. As a result, heterogenous reactions predominate between dissolved and mineral phases, and with the biota. These reactions primarily affect elements and compounds located at the particulate surface. Thus the determination of surface properties of particles is an important key to understanding interactions of trace elements and organic compounds between particulate and dissolved phases in estuarine and coastal systems. Specific surface area (SSA), cationic exchange capacity (CEC) and heat of immersion (∆H) have been measured on native untreated suspended sediment and after oxidation with 15% H2O2. SSA and ∆H have also been measured on samples Leached with NaOH and Na-dithionite in order to remove amorphous aluminosilicates. Results indicated that SSA is controlled by amorphous oxides and is related to the Al content of samples and their granulometry, suggesting an almost uniform coating of the detrital core by amorphous oxides. On the other hand, CEC and ∆H, which appear to be highly correlated, are controlled by both organic matter and amorphous oxides. Studies on electrophoretic mobility have provided additional data on the excess of charge at the interface between suspended matter and electrolytic medium. Particles in suspension in fresh, sea, and estuarine waters appear ubiquitously to exhibit a small range of negative surface charge. This uniformity is attributed to the presence of organic surface coatings on the particles (Loder and Liss, 1985). Finally, the significance of organic and oxide coatings as carriers of trace metal pollutants is discussed. It is shown that their importance in terms of flux is usually Low despite their major role in controlling solid-liquid interactions.

Interactions of trace elements: clinical significance.

We examined interaction of the trace element zinc with copper and lead. In sickle cell anemia, the usual situation is one of mild to moderate zinc deficiency owing to renal loss of zinc. Zinc deficiency seems to produce a mild overburden of copper and an increased ceruloplasmin level, probably by enhancing copper absorption. With zinc therapy, this process is reversed. Pharmacological doses of zinc, when administered in a way to ensure effectiveness (without food) will usually lead to copper deficiency. We have taken advantage of the copper-depleting effect of zinc to design a new therapy for Wilson's disease. Zinc, by inducing intestinal metallothionein, inhibits absorption of copper from food, and inhibits reabsorption of endogenously secreted copper, thereby producing a negative copper balance in Wilson's disease. Once we are certain that zinc blocks accumulation of copper in the liver of Wilson's disease patients, zinc therapy will be available as one approach for treating this fatal disease. The animal literature indicates that zinc protects against lead toxicity when both elements are given orally, no doubt through the intestinal metallothionein mechanism. In preliminary experiments in rats, we have not been able to show that toxicity from lead that arrives into the body through a nonoral route is affected by oral zinc supplements.

Shift in threshold toxicity levels in plants when more than one trace metal contaminates simultaneously

Trace metal contamination in the environment usually involves more than one metal simultaneously. Levels of some of the contaminants, even though considered to be at safe levels, may not be so because of their interactions with other trace metals. Accurate assessment demands that additive, protective, and synergic effects also be considered. Multiple trace metal toxicities can result in a shift of threshold toxicity. Experimental verification of these effects has been shown for some combinations and concentrations of cadmium, cobalt, nickel, zinc, copper and lithium, but not enough information is presently available to fully evaluate such a problem. Multiple trace element interactions often result in synergic effects on uptake and partitioning as well as on yields. A theoretical basis for explanation of various interacting-synergic, additive, antagonistic-effects is presented.

Physico-chemical processes of humic acid-trace element interactions

Experiments were carried out under various pH conditions since this factor may strongly influence the equilibrium of various physico-chemical forms in which a certain trace element may occur in the aquatic environment. Pick-up processes were investigated for iron, cobalt, zinc, ruthenium and mercury under various experimental conditions. The rate and type of bonding or association of trace metals in humic acids was investigated by means of their replacement with other ions. For this reason the pick-up of a radionuclide of a certain trace metal by humic acid was performed, and when equilibrium was reached, the humic acids were transferred to another system where a known concentration of another ion was present. Replacement reactions took place and their yields were followed by radioactivity measurements in the liquid phase. The shape of each curve indicates the specific kinetics of the interaction of a particular trace element with humic acids under experimental conditions. Speed, total yield and time needed to reach equilibrium are specific for each particular case. The purpose of our work is to investigate the nature of trace-element interactions with humic acids. Having in mind the large variations that may occur in the constitution of humic acids, our attention focussed primarily on the search for the role these chemical variations and the different processes of their formation play on the ability of humic acids to bind trace elements.

The role of wildlife species in the assessment of biological impact from chronic exposure to persistent chemicals

Assessments of chemical toxicity have regularly placed reliance upon experimental studies which employ environmentally unrealistic exposure regimes. This approach ignores the long-term low-level nature of environmental exposure which facilitates the development of factors which modify the toxicity of such chemicals. Examples of such adaptive mechanisms will be taken from the author's own studies. Factors discussed include the development of protective trace element interactions in target organs, the induction of specific metal-binding proteins, and the alteration of the distribution of chemicals at the organ and organelle level. Exposure-response investigations in wildlife are not restricted to the organism level and the impact of an environmentally released chemical upon breeding success and population dynamics can also be investigated. Disadvantages and problems associated with this kind of study, such as multiple pollutant exposure and variability in response, will also be considered.

Interactions of major, minor and trace elements on the carbon rod atomic-absorption spectrophotometric determination of micro-amounts of ytterbium, holmium, dysprosium and thulium

The electrothermal atomisation of trace amounts of some heavy rare earth elements has been investigated using a carbon rod atomiser. The interferences due to the components (major, minor and trace) of a common silicate matrix have been studied in order to obtain the best analytical conditions for future determinations. The detection limits (using uncoated graphite rods) are 5 pg of dysprosium, 3 pg of holmium and thulium and 0.4 pg of ytterbium.

Determination of trace elements in human serum by energy dispersive X-ray fluorescence

A system of energy dispersive X-ray fluorescence spectrometry (EDXRF) has been described to measure the concentrations of iron, copper, zinc, bromine, selenium and arsenic in human serum of healthy adults. Methods of sample preparations, standardization, and analysis have been presented. Data have been presented to show the accuracy, precision and sensitivity of the EDXRF system. The major advantages of using this system for the determination of trace elements in biological tissues are the relatively small sample size, ease of sample preparation, and the ability to perform rapid multi-element analysis on a single sample. The need for multi-element analysis has become apparent from the increased knowledge of trace element interactions in biological systems. The EDXRF system provides a solution for this need. Although the present system was applied only to the measurement of six elements, in principle the concentrations of V, Cr, Mn, Ni and Ti could also be routinely determined with improvements in technology and sensitivity.

Large‐scale Zonal Rotors in Soil Science

AbstractA large‐scale zonal rotor was developed to band isopycnically soils and sediments in nonaqueous density gradients. The major advantage of such a rotor over conventional swinging bucket rotors is that relatively large quantities may be segregated; 15 g in large‐scale zonal rotors vs. 0.25 g per centrifugal tube with swinging bucket rotors. The rotor was used to isolate and identify soil‐sediment reaction sites of 137Cs, 60Co, and 106Ru. The 137Cs was found to be associated with micaceous minerals, the 60Co with Fe‐sesquioxides, and the 106Ru with organic rich soil components. An edge‐unloading rotor containing sucrose gradients (max. density 1.3 g/cm3) was used in a rate‐zonal mode to isolate Cd and Ni enriched fractions of sediment taken near the wastewater discharge of a Cd‐Ni battery plant. In sediments enriched in carbonates, Cd was found to be largely associated with the carbonates while Ni was concentrated in the organic rich soil components. Biological availability of Cd was evaluated by growing bush bean seedlings (Phaseolus vulgaris L.) in nutrient solutions containing density fractions of a soil clay. Density gradient separations using large‐scale rotors were shown to be a valuable adjunct to chemical extraction techniques for characterizing trace element interactions with soils and sediments.

Some Biomedical Applications of Charged-Particle-Induced X-Ray Fluorescence Analysis

AbstractX-ray fluorescence induced by charged particles has been employed in trace element analysis of both animal and human blood, tissue and bone samples. Preparation techniques included microtome slicing and wet digestion in nitric acid, internal chemical standards being used in the latter case.Most of the specimens arose from a study of interactions between the toxic elements lead and zinc in growing foals; this was motivated by reports of sickness and death in foals raised near lead-zinc smelters. The cause of toxicity in animals from environmental pollution is often attributed to Single factors, whereas in reality interactions among many factors, including a variety of toxic and nutrient trace elements, should be considered.A variety of spectra are presented and elemental concentrations derived. Agreement between the X-ray data and atomic absorption spectrophotometry is encouraging. The results demonstrate the potential of particle-excited X-ray fluorescenee as a broad-range analytical technique for the study of trace element interactions.

Calibration of soil and leaf analyses for the control of sugar-cane fertilization rates in Southern Queensland

Data from a large series of trials over a number of different soil types have been studied to determine the value of leaf and soil analyses for controlling the fertilization of sugar-cane. Statistical data on the correlations obtained are presented. The response to nitrogen fertilizer could not be assessed from leaf analysis data, but the level of mineral nitrogen in incubated topsoil was well correlated with the amount of fertilizer required. The response to phosphate fertilizer could be assessed through soil, leaf, or juice phosphate analyses, the leaf analysis being the most accurate, with a critical value of 0.18% phosphorus in the dry lamina of the top visible dewlap leaf. The reliability of this assessment depended on the soil calcium/magnesium ratio being normal, and there being no trace element interaction. The response to potassium fertilizer was only poorly correlated with soil potassium. The correlation with leaf potassium was good, and was modified by the response of leaf potassium to potassium fertilizer and by the level of phosphate in the leaf. At 0.174% phosphorus, the critical level for leaf potassium was 1.69%; this fell to 1.44% at 0.22% phosphorus. Assessment of critical values in leaf tissue was complicated by difficulties in selecting sampling times due to very variable growth rates, and by associated variations in leaf analyses. The levels of calcium and magnesium have not been found to affect the critical levels of potassium.

Corrigendum - Yield depression due to phosphate fertilizer in sugar-cane

A large series of trials involving phosphate fertilizer showed that yields of cane could be reduced by the application of superphosphate at rates of up to 2 cwt/acre in four distinct areas. In these areas, the yield response to phosphate was dependent on the rate of nitrogen fertilization; yield depression only occurred where the nitrogen supply was adequate; phosphate could increase yields at low nitrogen. In most cases, the yield depression was associated with a low calcium/ magnesium (Ca/Mg) ratio in the soil (a ratio of less than 3.0 in terms of milliequivalents). On soils with high Ca/Mg ratios, regressions of yield response on soil or leaf phosphate indicated critical levels similar to those accepted elsewhere. Significant regressions could not be obtained from soils with low Ca/Mg ratios. A few trials testing a phosphate x trace element interaction indicated that the phosphate yield depression in at least one area was due to an induced deficiency of some trace element. The trace element effect is independent of the Ca/Mg ratio effect.