Trace metals, essential

Trace metals Essential d-block elements (e g. Fe, Zn, Cu) are mostly constituents of metallo-enzymes, which act in the transport and chemistry of 02, and perform many catalytic functions... 

Therapy by trace metals, essential as well as nonessential, may be associated with problems or complications. Even it can become dangerous or fatal to the patients because of overdoses, unforeseen interactions, or toxic side effects. Therefore trace metal treatment should be done with great caution. The initial stage of the disease has to be diagnosed correctly and monitoring of trace metal levels in blood and serum, respectively, is necessary to prevent complications [57]. 

Metallomics and metalloproteomics are emerging fields addressing the role, uptake, transport, and storage of trace metals essential for protein functions. The methodologies utilized in... 

Copper is an essential trace metal for all living beings. However, although copper is indispensable for many physiological functions of human organism, the presence of excess amount of copper in the body may be toxic. One possible source of copper in human body that is scarcely investigated is dental materials. 

Trace metals can serve as essential nutrients and as toxic substances (Sunda et al, 1991 Frausto da Silva and Williams, 1991). For example, cobalt is a component of vitamin B-12. This vitamin is essential for nitrogen fixing algae. In contrast, copper is toxic to marine phytoplankton at free ion concentrations similar to those found in seawater (Sunda and... 

The medium contains subsidiary nitrogen sources and additional essential nutrients such as calcium (added in the form of chalk to counter the natural acidity of the CSL), magnesium, sulphate, phosphate, potassium and trace metals. The medium is sterilized with steam at 120°C either in the fermenter itself or in ancilliary plant, which may be worked continuously. 

The detection and quantification of one or more of the above lipid peroxidation produas (primary and/or secondary) in appropriate biofluids and tissue samples serves to provide indices of lipid peroxidation both in ntro and in vivo. However, it must be stressed that it is absolutely essential to ensure that the products monitored do not arise artifactually, a very difiScult task since parameters such as the availability of catalytic trace metal ions and O2, temperature and exposure to light are all capable of promoting the oxidative deterioration of PUFAs. Indeed, one sensible precaution involves the treatment of samples for analysis with sufficient levels of a chainbreaking antioxidant [for example, butylated hydroxy-toluene (BHT)] immediately after collection to retard or prevent peroxidation occurring during periods of storage or preparation. 

Ecologically, copper is a trace element essential to many plants and animals. However, high levels of copper in soil can be directly toxic to certain soil microorganisms and can disrupt important microbial processes in soil, such as nitrogen and phosphorus cycling. Copper is typically found in the environment as a solid metal in soils and soil sediment in surface water. There is no evidence that biotransformation processes have a significant bearing on the fate and transport of copper in water. 

Soil pH is the most important factor controlling solution speciation of trace elements in soil solution. The hydrolysis process of trace elements is an essential reaction in aqueous solution (Table 3.6). As a function of pH, trace metals undergo a series of protonation reactions to form metal hydroxide complexes. For a divalent metal cation, Me(OH)+, Me(OH)2° and Me(OH)3 are the most common species in arid soil solution with high pH. Increasing pH increases the proportion of metal hydroxide ions. Table 3.6 lists the first hydrolysis reaction constant (Kl). Metals with lower pKl may form the metal hydroxide species (Me(OH)+) at lower pH. pK serves as an indicator for examining the tendency to form metal hydroxide ions. 

For example, the industrial preparation of mineral acids, such as sulfuric, hydrochloric and nitric, inevitably leads to them containing small concentrations of metals as impurities. If the acid is to be used purely as an acid in a simple reaction, the presence of small amounts of metals is probably unimportant. If, however, the acid is to be used to digest a sample for the determination of trace metals by atomic absorption spectrometry, then clearly the presence of metallic impurities in the acid may have a significant effect on the results. For this latter application, high-purity acids that are essentially metal-free are required. 

Falandysz, J. 1993a. Some toxic and essential trace metals in cattle from the northern part of Poland. Sci. Total Environ. 136 177-191. 

Falchuk, K. 1988. Zinc deficiency and the E. gracilis chromatin. Pages 75-91 in A.S. Prasad (ed.). Essential and Toxic Trace Metals in Human Health and Disease. Alan R. Liss, NY. 

We can see from Figure 3 that the moderate deficit of I, Co, Zn, Cu, Mo, B, and Mn with optimal ratios of trace metals to I and Si, is characteristic for all links of a biogeochemical food web. These biogeochemical peculiarities favor the optimal physiological regulation of exchange processes in animal and human organisms. However, a moderate deficit of essential trace nutrients weakens the human immune... 

We can see that for iron and manganese the annual fluxes of trace metals are an order of magnitude higher than airborne input. For copper this input is sufficient to supply the annual uptake, and for zinc is even in excess. All these trace metals are essential elements and their input with deposition can be considered as positive for... 

The AE methods have been used to determine the effects of different algae as food sources in the bioaccumulation of radiolabelled essential (Co, Se, Zn) and nonessential trace metals (Ag, Am, Cd, Cr) in the mussel Mytilus edulis [94]. Assimilation of essential metals was correlated with carbon assimilation, but not nonessential metals. The distribution of the metal in the alga and the gut passage time in the mussel was found to be important. 

Among the trace metals, Hudson and Morel [7] postulated that Fe and Zn were closest to a diffusion-limited situation based upon measured cellular metal quotas and concentrations in marine systems (e.g. Zn would be diffusion limited for cells > 20 pm). Similarly, Hassler and Wilkinson [90] showed that for cells grown under conditions of Zn starvation, transport was diffusion limited for [Zn2+] < 10 12 mol dm. Fortin and Campbell [91] showed that, in the presence of chloride, the Ag transport flux to Chlamydomonas reinhardtii was close to a diffusion limitation at the lower Ag concentrations that were examined. Diffusion limitation of trace metals is most likely in systems where the concentrations are low and concentrations of competing metals are high, especially for essential metals that are taken up by passive diffusion across the membrane [8], The final point of essentiality could be especially important when transport systems are upregulated in response to lowmetal concentrations (see also Section 2.2 [90,92]). 

Of more apparent significance in the aquatic environment are redox processes induced or enhanced on absorbance of light by chromophores at metal oxide surfaces in which the metal of the oxide lattice constitutes the cationic partner. Light induced electron transfer within such a chromophore often results in disruption of the oxide lattice. The photoredox-induced dissolution of iron and manganese oxides by such a mechanism has been proposed as a possible means of supply of essential trace-metal nutrients to plants and aquatic organisms (29-31). ... 

The major anions and cations in seawater have a significant influence on most analytical protocols used to determine trace metals at low concentrations, so production of reference materials in seawater is absolutely essential. The major ions interfere strongly with metal analysis using graphite furnace atomic absorption spectroscopy (GFAAS) and inductively coupled plasma mass spectroscopy (ICP-MS) and must be eliminated. Consequently, preconcentration techniques used to lower detection limits must also exclude these elements. Techniques based on solvent extraction of hydrophobic chelates and column preconcentration using Chelex 100 achieve these objectives and have been widely used with GFAAS. 

To take advantage of these solid reference materials (and to a lesser extent the trace metal seawater-based materials), it will be essential to establish an infrastructure for the collation and redistribution of the information that is accumulated about these materials through communitywide use. 

Sedki, A., Lekouch, N., Gamon, S. and Pineau, A. (2003). Toxic and essential trace metals in muscle, liver and kidney of bovines from a polluted area of Morocco,... 

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