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Analytical and Bioanalytical Chemistry (v.361, #4)
7th International Hans Wolfgang Nürnberg Memorial Symposium on “Metal Compounds in Environment and Life”Modena (Italy), 4–7 June 1997
by Mario Baraldi (pp. 331-332).
Atomic absorption spectrometric screening and gas chromatographic-mass spectrometric determination of organotin compounds in marine mussels: an application in samples from the Venetian Lagoon by G. Binato; G. Biancotto; R. Piro; R. Angeletti (pp. 333-337).
A new analytical approach for the determination of organotin compounds (OTC) in mussel samples has been developed and evaluated. A preliminary step, performed by graphite furnace atomic absorption spectrometry (GFAAS) for the total tin determination may be followed by gas chromatographic-mass spectrometric (GC/ MS) speciation only for the characterization of those samples exhibiting total tin concentration higher than 30 ng/g wet weight (GFAAS limit of detection). The GFAAS method was optimized using Pd nitrate under reducing conditions as matrix modifier to minimize NaCl interferences. Organotins were derivatized with a Grignard reagent for GC/MS analysis (TBT limit of detection = 80 ng/g). An application of this strategy was performed on mussel samples collected from the Venetian Lagoon.
Heavy metal biosorption by bacterial cells by A. Vecchio; Carlo Finoli; Damiano Di Simine; Vincenza Andreoni (pp. 338-342).
Microbial biomass provides available ligand groups on which metal ions bind by different mechanisms. Biosorption of these elements from aqueous solutions represents a remediation technology suitable for the treatment of metal-contaminated effluents. The purpose of the present investigation was the assessment of the capability of Brevibacterium sp. cells to remove bivalent ions, when present alone or in pairs, from aqueous solutions, using immobilized polyacrylamide cells of the microorganism in a flow-through system. The biosorption capacity of Brevibacterium cells was studied for lead, cadmium and copper. The metal cell binding capacity followed the order Cu > Pb > Cd, based on estimated qmax. These values, expressed as mmol metal/g dry weight cells, were 0.54 for Cu, 0.36 for Pb and 0.14 for Cd. Polyacrylamide-gel immobilized cells were effective in Pb, Cu and Cd removal. Lead removal was not affected by the presence of Cd and Cu; lead instead inhibited Cd and Cu removal. The desorption of the metal, by fluxing a chelating solution, restored the metal binding capacity of the cells, thus affording the multiple use of the same biomass in the remediation treatment.
Determination of mineral balances in sheep offered feed with added cadmium and zinc by Paul Chiy; Miguel de la Fuente; Enrique Barrado; Marisol Vega; C. Phillips (pp. 343-348).
The optimum conditions for microwave digestion of herbage and faeces to determine mineral concentrations were obtained by varying sample mass, reagent and heating programme, and it was confirmed that the resulting element concentrations were the same as for certified reference material. The effects of feeding cadmium to sheep at a level that is typical of polluted regions (1 mg/kg) for ten days were investigated, as well as the possible amelioration of cadmium effects by adding 30 mg/kg Zn to the diet. Cadmium in the feed increased the cadmium balance and produced several mineral disturbances, in particular a reduction in sodium balance which is typical of renal tubular disorders. Including zinc in the diet as well as cadmium reduced the cadmium balance to a level similar to that of sheep that did not receive cadmium or zinc, which suggests that the zinc status is critical in determining whether cadmium in feed increases the cadmium balance in sheep.
A chemometric survey of three sites in Muggia Bay (Northern Adriatic Sea): meteorological effects on heavy metal patterns in surface coastal waters by Pierluigi Barbieri; Gianpiero Adami; Andrea Favretto; E. Reisenhofer (pp. 349-352).
Within research on the quality of the waters of the Gulf of Trieste, this study on patterns of trace metal contents in the inner part of the gulf (Muggia Bay) discusses data of Cu, Pb, Cd and Zn, determined voltammetrically (DPASV), and collected in three sites with a 10-day frequency over the period of one year. Two of the sites lie inside the dam system which protects the harbour of Trieste, while the third one is situated outside for comparison purposes. Principal component analysis pointed out different metal patterns inside and outside the dam system; PC scores were related to meteorological information: rain plays a major role in conditioning the estuarine inner site: wind stirring action was detectable for the outer site. Both univariate graphics and canonical correlation analysis suggest a diffuse source for Pb, probably atmospheric deposition.
Fruits of ribes, rubus, vaccinium and prunus genus. Metal contents and genome by M. Plessi; D. Bertelli; G. Rastelli; A. Albasini; A. Monzani (pp. 353-354).
The production of fruits of genus Ribes, Rubus, Vaccinium and Prunus is particularly important in mountain communities. The contents of macro- and microelements in fruits from different cultivars of blueberry (Vaccinium corimbosus L.), red currant (Ribes rubrum L.), raspberry (Rubus idaeus L.) and cherry (Prunus avium L.) were determined. The anthocyanin and total polyphenol contents of the fruits were also determined. The results were analyzed with statistical methods. By using the one-way analysis of variance (ANOVA) the various genera of the fruits were found to be differentiable on the basis of their metal contents. Multivariate statistical analysis, performed using principal component analysis (PCA), confirms that the different fruits can also be well discriminated by their contents of metals, total anthocyanins, and polyphenols.
Evaluation of lead(II) and nickel(II) toxicity in NaCl and NaClO4 solutions by using MicrotoxR bioassay by I. Villaescusa; C. Matas; C. Hosta; M. Martinez; J. C. Murat (pp. 355-358).
The toxicity of nickel and lead compounds has been evaluated in NaCl and NaClO4 solutions by using the MicrotoxR bioassay. The aim of this work was to assess the toxicity of the different species in solution when varying the concentration of the medium. A modified Microtox protocol which enables the pH to be constant in all the cuvettes during analysis has been used. The positively charged species (Ni2+, Pb2+, PbCl+) were found to contribute more to the toxicity of Ni and Pb in NaCl while in NaClO4 solutions free metal was the responsible species. In all media studied, Pb compounds were the most toxic and provoked a quick response of the bacteria.
Vermiculite clay mineral as an effective carbon paste electrode modifier for the preconcentration and voltammetric determination of Hg(II) and Ag(I) ions by Irena Grabec Švegl; Mitja Kolar; Božidar Ogorevc; Boris Pihlar (pp. 358-362).
A vermiculite modified carbon paste electrode (VMCPE) was employed for the in situ preconcentration of traces of Hg(II) and Ag(I) via an ion-exchange route. Heavy metal ions were accumulated in Britton-Robinson (BR) buffer pH 7 for Hg(II) and pH 6 for Ag(I), and afterwards reduced at –0.7 V vs. Ag/AgCl in the separate measurement solution (BR buffer pH 5 + 0.05 mol/L NaNO3) prior to the anodic stripping square-wave voltammetric (ASSWV) detection. For Hg(II) ions, at 15 min accumulation, a linear range from 1.0 × 10–7 to 8.0 × 10–6 mol/L was obtained, with a 5.7 × 10–8 mol/L limit of detection. The VMCPE response was linear for Ag(I) ions in the concentration range from 2.0 × 10–7 to 8.0 × 10–6 mol/L, at 10 min accumulation with a corresponding limit of detection of 6.3 × 10–8 mol/L. The relative standard deviation of the analytical procedure including accumulation from a 5 × 10–7 mol/L solution of Hg (15 min) or Ag(I) (10 min), electrolysis, ASSWV detection, regeneration and activation of the VMCPE, was 4% (n = 6). The optimisation of the parameters for the application of the VMCPE in combination with ASSWV detection is presented and discussed.
Contents and localization of heavy metals in human placentae by E. Reichrtova; M. Ursinyova; L. Palkovicova; L. Wsolova (pp. 362-364).
The placenta was used as an exposure index for the risk evaluation of prenatal fetal chemical exposure. Full-term placenta samples collected at maternity hospitals in 4 regions of different environmental pollutants and traffic density were examined for lead and cadmium contents using atomic absorption spectrometry (AAS). The results showed similar lead contents in placental samples from all selected regions, except for a small town with a lower traffic density. The findings may implicate traffic-related environmental lead pollution, rather than industrial sources. The highest concentration of cadmium was shown to be in the samples collected from the region with the highest proportion of smoking mothers (including passive smoking). Simultaneously, the placental samples were processed histochemically to determine the location of lead in the placental tissue (using light microscopy). The degree of placental metal contamination was done semiquantitatively, and the difference between the rural and industrial region was statistically compared. Parallel quantitative AAS analyses and semiquantitative histochemical lead analyses of human placental samples revealed analogous results regarding the level of placental contamination with metals.
Influence of heavy metals, especially lead, on lipid metabolism, serum alpha-tocopherol level, total antioxidant status, and erythrocyte redox status of copper smelter workers by Jolanta Antonowicz; R. Andrzejak; Tomasz Lepetow (pp. 365-367).
An assessment of influence of the occupational exposure to heavy metals, especially lead, on serum lipids (including lipid peroxides), total antioxidant status, erythrocyte redox status, and serum alpha-tocopherol level was performed in a group of 141 healthy male copper smelter workers. The following parameters were measured: blood lead and cadmium levels, serum manganese, copper, zinc, calcium and magnesium levels, free erythrocyte protoporphyrins (FEP), total cholesterol, HDL2-, HDL3-cholesterol, triglycerides and lipid peroxides in serum, erythrocyte superoxide dismutase (SODE), catalase (CatE) and glutathion peroxidase (PxGSHE) activities, erythrocyte reduced glutathione level (GSHE), serum alpha-tocopherol level, and serum total antioxidant status (TAS). Mean PbB was within the norm range (328.2 ± 141.7 μg/L), but mean MnS concentration slightly exceeded 10 μg/L (11.04 ± 3.79 μg/L). Mean cholesterol and triglycerides concentrations were near the highest borderline values. We found a significantly negative correlation between lead levels and HDL3-cholesterol (r = 0.253, P < 0.05). Erythocyte catalase activity and TAS were lowered. TAS showed significant negative correlation with PbB. A group of workers with PbB≥ 400 μg/L had significantly lower CatE, lower TAS, and lower HDL3-cholesterol, compared to the workers with Pb < 400 μg/L. We have also found positive correlation between alpha-tocopherol and total cholesterol (r = 0.267, P < 0.05) and between alpha-tocopherol and LDL-cholesterol (r = 0.207, P < 0.05).
Cadmium(II) specifically interacts with cellular signaling to induce proto-oncogenes c-fos and c-jun in rat PC12 cells by D. Beyersmann; Thorsten Schäfer (pp. 368-371).
Cadmium(II) compounds are carcinogens but only weakly mutagens. Because Cd(II) at low micromolar concentrations stimulates cell growth and induces some proto-oncogenes with several mammalian cell lines, the stimulation of cell proliferation is discussed as a major mechanism of the carcinogenicity of this metal. In the present work, the induction of the cellular proto-oncogenes c-fos and c-jun by Cd(II) was studied in rat PC12 cells. Several cellular signal transduction elements were tested as mediators of the proto-oncogene induction by cadmium. Cd(II) does not evoke mobilization of free intracellular Ca2+ in PC12 cells, and there was no impairment of the effect of Cd(II) by inhibitors of protein kinase A or of MAPK kinase. However, bisindolylmaleimide I, a specific inhibitor of protein kinase C abolished the proto-oncogene induction by Cd(II). Hence, a critical role for protein kinase C in the mitogenic effect of Cd(II) is inferred, and a substitution of structural Zn2+ ions by Cd2+ ions in this enzyme is discussed as the putative mechanism.
Lead interferes with calcium entry through membrane pores by D. Büsselberg; K. Schirrmacher; R. Domann; M. Wiemann (pp. 372-376).
Calcium is an important intracellular messenger in all cells, represented here by nerve cells and osteoblast-like (OBL) cells. In neurons the intracellular calcium signal is related, e.g., to bioelectric phenomena. In OBL cells the intracellular calcium concentration ([Ca2+]i) plays a role in the intercellular communication via gap junction channels. [Ca2+]i might be affected by lead (Pb2+). In the nervous system even low Pb2+ concentrations impair learning and memory functions. Considering long-term potentiation (LTP) as a model for learning and memory it has been proven that the generation and maintenance of LTP is reduced by Pb2+ (1–10 μM). As the induction of LTP depends on a rise of [Ca2+]i, we examined the effects of Pb2+ on [Ca2+]i and on currents through calcium permeable membrane pores in dorsal-root ganglion (DRG) neurons, using calcium measurements (Fura-2/ AM) and whole cell patch clamp techniques. To study the effects of Pb2+ on intercellular communication via gap junctions we used rat OBL cells investigating interactions of Pb2+ with electric cell coupling. Furthermore, we examined calcium release activated channel currents (CRACCs) of these cells.Lead (1–10 μM) reduced the stimulated increase of [Ca2+]i in a concentration dependent manner, by reducing both voltage-activated calcium channels (VACCs) and N-methyl-D-aspartate activated calcium channels (NACCs) in neurons. Voltage-activated calcium channel currents (VACCCs) were reduced by Pb2+ with an IC50 of 0.46 μM. The effect was quite specific as voltage activated sodium and potassium channel currents were not significantly altered in the same concentration and voltage range. Furthermore, this effect was not voltage dependent and only partly reversible. A 100-fold higher concentration of Pb2+ (IC50 of 46 μM) was found for the reduction of NACC currents. A small portion of this effect was not reversible. Other agonist activated channel currents (kainate and quisqualate) are not affected. In OBL cells, the calcium entry through calcium release activated channels (CRACs) was reduced in a concentration dependent manner by extracellular Pb2+, the concentrations were between 2 and 20 μM. Surprisingly the electric coupling through gap junction channels in OBL cells was not reduced by either extracellular or intracellular Pb2+ (5–25 μM).
Disruption of DNA repair processes by carcinogenic metal compounds by Andrea Hartwig; Leon Mullenders; Monika Asmuß; Heike Dally; M. Hartmann (pp. 377-380).
Based on pronounced enhancing effects in combination with other DNA-damaging agents the potentials of Ni(II), Cd(II) and As(III) to interfere with DNA repair processes in HeLa cells was investigated. With respect to oxidative DNA damage, Ni(II) and Cd(II) induced DNA strand breaks starting at concentrations of 250 μM and 5 μM, respectively. The induction of oxidative DNA base modifications like 8-hydroxyguanine was restricted to the cytotoxic concentration of 750 μM Ni(II) and not observed after treatment with Cd(II). In contrast, the removal of oxidative DNA base modifications was inhibited at concentrations as low as 50 μM Ni(II) and 0.5 μM Cd(II). Regarding nucleotide excision repair, Ni(II) and Cd(II) disturbed the DNA-protein interactions involved in the damage recognition step when applying HeLa nuclear protein extracts and a UV-damaged oligonucleotide, while As(III) inhibited the actual incision event. In the case of Ni(II) and Cd(II), this effect was reversible by the addition of Mg(II) and Zn(II), respectively. Furthermore, Cd(II) inactivated the isolated bacterial Fpg protein, most likely by the displacement of Zn(II) from its zinc finger structure. Since DNA is continuously damaged by exogenous and endogenous sources, an impaired repair capacity might well account for the carcinogenic action of the metal compounds.
Molecular biology of nickel carcinogenesis by Max Costa (pp. 381-385).
The molecular mechanisms of nickel carcinogenesis are discussed and reviewed with emphasis on work done in my laboratory. The most important determinant of nickel carcinogenesis is the ability of the nickel ion to reach relevant targets for carcinogenesis, which involves chromatin and depends on the ability of the nickel compound to enter cells. The mechanisms that regulate the phagocytosis and intracellular dissolution of the highly carcinogenic particulate nickel compounds are discussed, as is the ability of these nickel compounds to enhance the DNA methylation pattern and turn off the expression of critical tumor suppressor genes. These findings show these nickel compounds to be a somewhat unique class of carcinogens.
Dose-dependent induction of apoptosis or necrosis in human cells by organotin compounds by F. Zaucke; H. Zöltzer; H. F. Krug (pp. 386-392).
In the present study, the mode of cell death induced by highly toxic trialkylated tin compounds has been evaluated. Treatment of undifferentiated HL-60 cells with submicromolar to micromolar concentrations of tri-n-butyltin (TBT) led only to a slight decrease in cell viability measured with trypan blue exclusion. Nevertheless, cell membrane blebbing was observed by means of light microscopy and condensation of nuclear chromatin and formation of apoptotic bodies was demonstrated in Hoechst 33342 stained cells. The nuclear chromatin condensation was associated with an extensive DNA fragmentation. Visualized by agarose gel electrophoresis, genomic DNA appeared as a characteristic ladder-like pattern of DNA fragments which is the biochemical hallmark of apoptosis. The typical internucleosomal DNA digestion was concentration-dependent and began within 2 to 3 h of incubation. During the incubation period a persistent and steady elevation of intracellular free calcium concentration ([Ca2+]i) could be detected. Furthermore, the chromatin condensation and DNA fragmentation could be blocked by supplementation of the incubation medium with zinc pointing to an activation of a zinc-sensitive and calcium-dependent endogenous endonuclease. Higher concentrations of tributyltin (≥ 5 μmol/L TBT) led within hours to a cell killing with degenerative changes indicative of necrosis, demonstrated by plasma membrane disruption which was accompanied by random DNA breakdown. Furthermore, these concentrations also provoked a persistent elevation in [Ca2+]i which reached, even after 10 min, higher levels in comparison with apoptosis-inducing concentrations. The loss in membrane integrity observed at these concentrations of TBT could be due to an activation of calcium-dependent phospholipases. Here it is shown that activation of cytosolic phospholipase A2 (cPLA2) leads to liberation of arachidonic acid (AA) out of the phospholipid membrane. The results presented here demonstrate that organometals are able to induce different cell death pathways depending on the applied concentration: low concentrations led to apoptosis whereas high concentrations stimulate necrosis. We suggest that there exists a direct correlation between the intracellular free calcium concentration and the mode of cell death.