Relevance, essentiality and toxicity of trace elements in human health

The metals Mn, Fe, Cu, and Zn, and the non-metal Se are considered "trace elements" (TE) because of their essentiality and very limited quantity in humans. The biological activities of Cu, Fe, Mn, and Se are strongly associated with the presence of unpaired electrons that allow their participation in redox reactions. In biological systems these metals are mostly bound to proteins, forming metalloproteins. Many of the metals in metalloproteins are part of enzymatic systems, have structural and storage functions, or use the protein to be transported to their target site in the organism. In humans Mn, Fe, Cu, Zn, and Se accomplish decisive functions to maintain human health. Deficiency in any of these TE leads to undesirable pathological conditions that can be prevented or reversed by adequate supplementation. In sufficiently nourished persons, supplementation should be carefully controlled, given the toxic effects ascribed to TE when present in quantities exceeding those required for accomplishing their biological functions. The dietary reference intakes provided by national regulatory agencies are guides to define intake, supplementation and toxicity of Mn, Fe, Cu, Zn, and Se, as well other elements considered micronutrients for humans.     

Determination of 5-fluorouracil and its main metabolites in plasma by high-performance liquid chromatography: Application to a pharmacokinetic study

This paper describes a relatively simple and sensitive high-performance liquid chromatographic assay (HPLC) with ultraviolet absorbance detection for 5-fluorouracil (5-FUra) and its two main metabolites, 5-fluorouridine (5-FUrd) and 5-fluoro-2′-deoxyuridine (5-FdUrd), in plasma. In this study, two plasma clean-up procedures involving addition of internal standard, solid-phase and liquid-liquid extractions have been developed. A reversed-phase Kromasil C₁₈ column was used. The detection was performed at 268 nm for 5-FUra and at 275 nm for the two metabolites. Linear detection responses were obtained for concentrations ranging from 25 to 1000 ng/ml. The average recovery from plasma was 35, 42 and 48% for 5-FUra, 5-FUrd and 5-FdUrd, respectively. Precision, expressed as C.V., ranged from 2.7 to 13% and the mean recovery from 94 to 105%. The limits of quantitation and detection of the three analytes were 20 and 10 ng/ml, respectively. The method was used to monitor the pharmacokinetic profile of 5-FUra and its two metabolites in patients with metastatic colorectal cancer.     

Leguminosae native nodulating bacteria from a gold mine As-contaminated soil: Multi-resistance to trace elements,and possible role in plant growth and mineral nutrition

Efficient N₂-fixing Leguminosae nodulating bacteria resistant to As may facilitate plant growth on As-contaminated sites. In order to identify bacteria holding these features, 24 strains were isolated from nodules of the trap species Crotalaria spectabilis (12) and Stizolobium aterrimum (12) growing on an As-contaminated gold mine site. 16S rRNA gene sequencing revealed that most of the strains belonged to the group of α-Proteobacteria, being representatives of the genera Bradyrhizobium, Rhizobium, Inquilinus, Labrys, Bosea, Starkeya, and Methylobacterium. Strains of the first four genera showed symbiotic efficiency with their original host, and demonstrated in vitro specific plant-growth-promoting (PGP) traits (production of organic acids, indole-3-acetic-acid and siderophores, 1-aminocyclopropane-1-carboxylate deaminase activity, and Ca₃(PO₄)₂ solubilization), and increased resistance to As, Zn, and Cd. In addition, these strains and some type and reference rhizobia strains exhibited a wide resistance spectrum to β-lactam antibiotics. Both intrinsic PGP abilities and multi-element resistance of rhizobia are promising for exploiting the symbiosis with different legume plants on trace-element-contaminated soils.     

Fine needle aspirate cell blocks are reliable for detection of hormone receptors and HER‐2 by immunohistochemistry in breast carcinoma

S. P. Bueno Angela, R. M. Viero and C. T. Soares Fine needle aspirate cell blocks are reliable for detection of hormone receptors and HER‐2 by immunohistochemistry in breast carcinoma Aims: To evaluate the reliability of fine needle aspirate cell blocks in the assessment of oestrogen receptor (ER), progesterone receptor (PR) and HER‐2/neu proteins by immunohistochemistry in comparison with surgical specimens. Materials and methods: This is a retrospective study of 62 cases of breast carcinoma diagnosed by fine needle aspiration cytology (FNAC) and confirmed using the surgical specimen. Immunohistochemical tests were performed to assess the presence of oestrogen receptor (ER), progesterone receptor (PR) and HER‐2/neu proteins in cell blocks and the corresponding surgical specimens. The cell block method used alcohol prior to formalin fixation. Cases with 10% or more stained cells were considered positive for ER and PR. Positivity for HER‐2/neu was assessed on a scale of 0–3+. The criterion for positivity was a score of 3+. Results: Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of the cell blocks in the investigation of ER, PR and HER‐2/neu protein (3+) were (%): ER, 92.7, 85.7, 92.7, 85.7 and 90.3; PR, 92.7, 94.7, 97.4, 87.0 and 93.5; HER‐2/neu, 70.0, 100.0, 100.0, 94.5 and 95.2. Discrepancies were seen in cell blocks in the 1+ and 2+ HER‐2/neu staining scores: two of 12 cases scoring 2+ and one case of 26 scoring 1+ on cell blocks scored 3+ on surgical specimens. The correlation index between cell block and corresponding surgical specimen varied from 90% to 94%. Conclusion: Cell blocks provide a useful method of assessing ER, PR and HER‐2/neu, mainly for inoperable and recurrent cases, but consideration should be given to carrying out FISH analysis on 1+ as well as 2+ HER‐2/neu results.     

Low iron diet and parenteral cadmium exposure in pregnant rats: the effects on trace elements and fetal viability

The effects of latent iron deficiency combined with parenteral subchronic or acute cadmium exposure during pregnancy on maternal and fetal tissue distribution of cadmium, iron and zinc, and on fetal viability were evaluated. Timed-pregnant Sprague-Dawley rats were fed on semisynthetic test diets with either high iron (240 mg kg) or low iron (10 mg kg), and concomitantly exposed to 0, 3 or 5 mg cadmium (as anhydrous CdCl₂) per kilogram body weight. Animals were exposed to cadmium from gestation day 1 through 19 by subcutaneously implanted mini pumps (Subchronic exposure) or on gestation day 15 by a single subcutaneous injection (Acute exposure). All rats were killed on gestation day 19. Blood samples, selected organs and fetuses were removed and prepared for element analyses by atomic absorption spectrometry. Low iron diet caused decreases in maternal body weight, maternal and fetal liver weights, placental weights and tissue iron concentrations. By cadmium exposure, both subchronic and acute, tissue cadmium concentrations were increased and the increase was dose-related, maternal liver and kidney zinc concentrations were increased, and fetal zinc concentration was decreased. Cadmium concentration in maternal liver was additionally increased by low iron diet. Acute cadmium exposure caused lower maternal body and organ weights, high fetal mortality, and decreased fetal weights of survivors. In conclusion, parenteral cadmium exposure during pregnancy causes perturbations in essential elements in maternal and fetal compartments. Acute cadmium exposure in the last trimester of gestation poses a risk for fetal viability especially when combined with low iron in maternal diet.     

Assessment of water quality and health risks for toxic trace elements in urban Phewa and remote Gosainkunda lakes,Nepal

The concentration of 13 metals (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Pb, and Hg) and their associated health risk assessment was performed for two Himalayan lakes, urban Phewa and remote Gosainkunda, from Nepal. Water Quality Index (WQI), Metal Index (MI), Hazard Quotient (HQ), Hazard Index, and Cancer Risk were calculated in order to evaluate the water quality of these lakes. Correlation analysis revealed that Mn and Fe were derived from natural geological weathering processes and Pb, V, Cr, Co, Ni, Cu, Zn, and Cd might have originated from anthropogenic sources. The results revealed that WQI of the remote lake fell into excellent water quality and urban lake fell into poor water quality, which is also supported by the MI calculation. Moreover, the HQ of Mn in urban lake showed values greater than unity suggesting its health risk to the local inhabitants. The cancer index values indicated “high” risk due to Cr, whereas Cd possesses “very low” cancer risk on local population residing nearby areas. This study provides the useful database and suggests for the regular assessment and policy formulation for safeguarding the natural water bodies in the region.     

Downregulation of wild-type p53 protein by HER-2／neu mediated PI3K pathway activation in human breast cancer cells： its effect on cell proliferation and implication for therapy

Overexpression and activation of HER-2/neu (also known as c-erbB-2), a proto-oncogene, was found in about 30% of human breast cancers, promoting cancer growth and making cancer cells resistant to chemo- and radio-therapy.Wild-type p53 is crucial in regulating cell growth and apoptosis and is found to be mutated or deleted in 60-70% of human cancers. And some cancers with a wild-type p53 do not have normal p53 function, suggesting that it is implicated in a complex process regulated by many factors. In the present study, we showed that the overexpression of HER-2/neu could decrease the amount of wild-type p53 protein via activating PI3K pathway, as well as inducing MDM2 nuclear translocation in MCF7 human breast cancer cells. Blockage of PI3K pathway with its specific inhibitor LY294002 caused G1-S phase arrest, decreased cell growth rate and increased chemo- and radio-therapeutic sensitivity in MCF7 cells expressing wild-type p53. However, it did not increase the sensitivity to adriamycin in MDA-MB-453 breast cancer cells containing mutant p53. Our study indicates that blocking PI3K pathway activation mediated by HER-2/neu overexpression may be useful in the treatment of breast tumors with HER-2/neu overexpression and wild-type p53.     

MAP2 IHC detection: a marker of antigenicity in CNS tissues

Immunohistochemistry (IHC) is used to detect antibody-specific antigens in tissues; the results depend on the ability of the primary antibodies to bind to their antigens. Therefore, results depend on the quality of preservation of the specimen. Many investigators have overcome the deleterious effects of over-fixation on the binding of primary antibodies to specimen antigens using IHC, but if the specimen is under-fixed or fixation is delayed, false negative results could be obtained despite certified laboratory practices. Microtubule-associated protein 2 (MAP2) is an abundant microtubule-associate protein that participates in the outgrowth of neuronal processes and synaptic plasticity; it is localized primarily in cell bodies and dendrites of neurons. MAP2 immunolabeling has been reported to be absent in areas of the entorhinal cortex and hippocampus of Alzheimer’s disease brains that were co-localized with the dense-core type of amyloid plaques. It was hypothesized that the lack of MAP2 immunolabeling in these structures was due to the degradation of the MAP2 antigen by the neuronal proteases that were released as the neurons lysed leading to the formation of these plaques. Because MAP2 is sensitive to proteolysis, we hypothesized that changes in MAP2 immunolabeling may be correlated with the degree of fixation of central nervous system (CNS) tissues. We detected normal MAP2 immunolabeling in fixed rat brain tissues, but MAP2 immunolabeling was decreased or lost in unfixed and delayed-fixed rat brain tissues. By contrast, two ubiquitous CNS-specific markers, myelin basic protein and glial fibrillary acidic protein, were unaffected by the degree of fixation in the same tissues. Our observations suggest that preservation of various CNS-specific antigens differs with the degree of fixation and that the lack of MAP2 immunolabeling in the rat brain may indicate inadequate tissue fixation. We recommend applying MAP2 IHC for all CNS tissues as a pre-screen to assess the quality of the tissue preservation and to avoid potentially false negative IHC results.     

‘Reduced malignancy as a mechanism for longevity in mice with adenylyl cyclase type 5 disruption’

Disruption of adenylyl cyclase type 5 (AC5) knockout (KO) is a novel model for longevity. Because malignancy is a major cause of death and reduced lifespan in mice, the goal of this investigation was to examine the role of AC5KO in protecting against cancer. There have been numerous discoveries in genetically engineered mice over the past several decades, but few have been translated to the bedside. One major reason is that it is difficult to alter a gene in patients, but rather a pharmacological approach is more appropriate. The current investigation employs a parallel construction to examine the extent to which inhibiting AC5, either in a genetic knockout (KO) or by a specific pharmacological inhibitor protects against cancer. This study is unique, not only because a combined genetic and pharmacological approach is rare, but also there are no prior studies on the extent to which AC5 affects cancer. We found that AC5KO delayed age‐related tumor incidence significantly, as well as protecting against mammary tumor development in AC5KO × MMTV‐HER‐2 neu mice, and B16F10 melanoma tumor growth, which can explain why AC5KO is a model of longevity. In addition, a Food and Drug Administration approved antiviral agent, adenine 9‐β‐D‐arabinofuranoside (Vidarabine or AraAde), which specifically inhibits AC5, reduces LP07 lung and B16F10 melanoma tumor growth in syngeneic mice. Thus, inhibition of AC5 is a previously unreported mechanism for prevention of cancers associated with aging and that can be targeted by an available pharmacologic inhibitor, with potential consequent extension of lifespan.     

Effect of purple loosestrife (Lythrum salicaria) diet supplementation in rabbit nutrition on performance,digestibility, health and meat quality

In this study, 160 Hycole weaned rabbits (35 days old) were randomly divided into four groups of 40. The rabbits were studied throughout a 54-day experimentation period in order to determine the impact of dietary supplementation from herbs composed of 0.2%, 0.4% dry ground Lythrum salicaria leaves (LS) and 0.3% Cunirel® (CR; a commercial herb mixture containing LS as the main ingredient) on performance, digestibility, health and meat quality. The basal diet was given to the control group. No significant differences were found in performance, 10 rabbits from each group were selected for evaluation regarding apparent digestibility. The rabbits fed the control diet and the diet with the low level of LS had a higher level of CP digestibility than did the animals that were supplemented with the high LS levels and CR (85.7% and 84.9% v. 84.0% and 84.0%, respectively; P<0.05). The ether extract digestibility was lower in the treatment group with 0.4%LS addition and CR as compared with the control group (52.2% and 54.5% v. 62.6%, respectively; P<0.05). The slaughter process was performed on 89-day-old rabbits to study the carcass characteristics, meat quality, blood parameters, caecal contents and gut histology. The total leukocyte counts in the control animals were lower than they were in the rabbits fed 0.2%, 0.4%LS and CR (4.06 v. 8.25, 8.63 and 8.21×10⁹/l, respectively; P<0.05). For caecal fermentation, the caecal contents of the rabbits fed 0.4% of LS, showed higher concentrations of total volatile fatty acid (VFA; 24.1 v. 18.9 mg/kg dry matter (DM); P<0.05) and acetic acid (18.3 v. 14.4 mg/kg DM; P<0.05), but lower ammonia levels (594 v. 892 mg/kg DM; P<0.05) as compared with the control group. PCR-denaturing gradient gel electrophoresis analyses were performed to evaluate the microbial community in hard faeces, collected at days 35, 42, 49, 56, 70 and 89, whereas the caecal contents were taken after slaughtering. The results demonstrated that between the treatment groups, the similarity of the microbial communities was higher as compared with the control group. Moreover, only age was shown to influence microbiota diversity. In conclusion, the results of this study indicated that supplementation of LS in rabbit diets leads to an increase in the total white blood cells, total VFA and acetic acid concentration, and a decrease in the ammonia levels, as well as the digestibility when CR and high level of LS were supplemented, without causing any adverse effects on other parameters.     

Regulation of COX-2 expression by selected trace elements and heavy metals: Health implications,and changes in neuronal plasticity. A review

Trace elements or trace metals are essential components of enzymes, proteins, hormones and play a key role in biochemical processes, cell growth and differentiation, as well as in neurotransmission, affecting human physiology. In nature there are also heavy metals that exhibit toxic effects on the human body, including the brain. The importance of trace elements has been established in neurodegenerative disorders, schizophrenia, depression among others. In parallel, an important regulatory element in the above diseases is cyclooxygenase-2 (COX-2), a modulator of the arachidonic acid (AA) pathway, and a cause of neuroinflammation, and glutamate (Glu) dysregulation, affecting calcium (Ca) metabolism in cells. This review presents the effects of major trace elements and heavy metals on COX-2 expression. Calcium (Ca), zinc (Zn), cadmium (Cd), vanadium (V), nickel (Ni), copper (Cu), and iron (Fe) can potentially increase COX-2 expression, inducing neuroinflammation and Glu excitotoxicity; while magnesium (Mg), lithium (Li), and selenium (Se) can potentially decrease COX-2 expression. The associated mechanisms are described in the article.     

Metal-based ethanolamine-derived compounds: a note on their synthesis,characterization and bioactivity

Abstract

Metal-based ethanolamines, (L¹)–(L⁴) coordinated with Co(II), Cu(II), Ni(II) and Zn(II) metals in 1:2 (metal:ligand) molar ratio to produce new compounds have been reported. These compounds were screened for their bactericidal/fungicidal activity against a number of bacterial (Escherichia coli, Shigella flexneri, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus and Bacillus subtilis) and fungal strains (Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata) alongside against a shrimp species known as Artemia salina. The screening results indicated that metal complexes have significantly higher activity than uncomplexed ligands against one or more bacterial/fungal species due to chelation. The ligand (L⁴) displayed good bacterial and fungal activity as compared to other ligands. The antibacterial results revealed that the Zn(II) complex (16) of (L⁴) was found to be the most active complex and Co(II) complex (14) of the same ligand (L⁴), demonstrated the highest antifungal activity.     

Quantification of changing Pseudomonas aeruginosa sodA, htpX and mt gene abundance in response to trace metal toxicity: a potential in situ biomarker of environmental health

Sediment-dwelling prokaryotes play a vital role in determining the fate and speciation of metals, yet are also susceptible to the biological effects of trace metals. In this article, optimized DNA extraction and purification techniques and species-specific primers are used to assess the genetic incidence and abundance of metal detoxification and general stress genes of Pseudomonas aeruginosa to complement chemical analysis in inferring the severity of metal-contaminated sites along the Clark Fork River, Montana. Results show the highest incidence of candidate genes related to bacterial stress at the most polluted site, while multiple regression analysis demonstrated significant correlations (P<0.05, r(2)=0.9) between in situ metal concentrations (As, Cu and Zn), total gene incidence, and the incidence of metal detoxification genes. Furthermore, principal components plotting the incidence of genes related to metal resistance show clear separation of sites giving clear clusters on the basis of contamination. Quantification of three genes (sodA, htpX and mt) from surveyed sites found significantly higher (anova, P<0.05) copy numbers at the more contaminated sites compared with reference sites. The development of rapid microbial biomarker tools represents a significant advance in the field of environmental biomonitoring and the prediction of metal bioavailability.     

Assay for erythrocyte superoxide dismutase activity in patients with lung cancer and effects on pollution and smoke trace elements

The antioxidative effect of CuZnSOD, which catalyzes the dismutation of Superoxide anion (O₂-), provides a defense against the oxygen toxicity. The object of the study is to evaluate the erythrocytes Superoxide dismutase (SOD) activity in two groups of persons (Group I, healthy blood donors; Group II, lung cancer patients), using the spectrophotometric assay of NADH oxidation and the indirect method (2–27). The effect of trace elements, such as A1^3-, Cr³⁺, Fe³⁺, Hg²⁺, NI²⁺, and Pb²⁺ (producing free radicals oxygen and present in pollution and smoke) is also evaluated. The results show the decrease of SOD activity in lung cancer patients with respect to healthy individuals. Likewise, in those patients the enzymatic activity is bigger in early stage (I,II) with respect to advanced one (III) (p < 0.05). The lesser activity when the samples are incubated with Ni or Pb point out that these metals play a role in neoplasm development. In short, the oxidant-antioxidant balance is altered in lung cancer patients.