Investigations on the quantitative determination of nickel and chromium in human lung tissue. Industrial medical, toxicological, and occupational medical expertise aspects

Nickel Content in Human Internal Organs

With the growing interest in new applications of metals in modern technologies, an increase in their concentration in the environment can be observed, which, in consequence, may constitute a hazard to human health. That is why it is of a great importance to establish "reference" levels of particular elements (essential or toxic) in human biological samples.The aim of this paper was to determine nickel in autopsy tissues of non-occupationally exposed subjects in Southern Poland (n = 60). Measurements were performed by means of electrothermal atomic absorption spectrometry after microwave-assisted acid digestion according to previously optimized and validated procedure. The results obtained indicate that data cover the wide range of concentrations and generally are consistent with other published findings. Nickel levels in the brain, stomach, liver, kidneys, lungs and heart (wet weight) were between 2.15-79.4 ng/g, 0.5-44.2 ng/g,7.85-519 ng/g, 12.8-725 ng/g, 8.47-333 ng/g and 2.3-97.7 ng/g, respectively. Females had generally lower levels of nickel in tissues than males (statistically significant relationships were found for the liver, kidneys and lungs), and median nickel concentrations in all studied material within all age groups had very similar values, with the exception of stomach.

Peptide bond cleavage in the presence of Ni-containing particles

NiO nanoparticles and non-stoichiometric black NiO were shown to be effective sources of Ni2+ ions causing sequence-selective peptide bond hydrolysis. NiO nanoparticles were as effective in this reaction as their molar equivalent of soluble Ni(ii) salt. These findings highlight the efficacy of delivery of toxic Ni2+ by these environmentally available particles.

Nickel reduces calcium dependent dimerization in neural cadherin

Cadherins are the transmembrane component in adherens junctions, structures that link the actin cytoskeletons in adjacent cells within solid tissues including neurological synapses, epithelium and endothelium. Cell-cell adhesion by cadherins requires the binding of calcium ions to specific sites in the extracellular region. Given the complexity of the cell adhesion microenvironment, we are investigating whether other divalent cations might affect calcium-dependent dimerization of neural (N) cadherin. The studies reported herein characterize the impact of binding physiological magnesium(ii) or neurotoxic nickel(ii) on calcium-dependent N-cadherin function. Physiological levels of magnesium have only a small effect on the calcium-binding affinity and calcium-induced dimerization of N-cadherin. However, a tenfold lower concentration of nickel decreases the apparent calcium-binding affinity and calcium-induced dimerization of N-cadherin. Competitive binding studies indicate that the apparent dissociation constants for nickel and magnesium are 0.2 mM and 2.5 mM, respectively. These Kd values are consistent with concentrations observed for a range of divalent cations in the extracellular space. Results from these studies indicate that calcium-induced dimerization by N-cadherin is attenuated by natural and non-physiological divalent cations in the extracellular microenvironment.

Peptide Bond Cleavage by Ni(II) Ions within the Nuclear Localization Signal Sequence

Nickel is harmful to humans, being both carcinogenic and allergenic. However, the mechanisms of this toxicity are still unresolved. We propose that Ni(II) ions disintegrate proteins by hydrolysis of peptide bonds preceding the Ser/Thr-Xaa-His sequences. Such sequences occur in nuclear localization signals (NLSs) of human phospholipid scramblase 1, Sam68-like mammalian protein 2, and CLK3 kinase. We performed spectroscopic experiments showing that model nonapeptides derived from these NLSs bind Ni(II) at physiological pH. We also proved that these sequences are prone to Ni(II) hydrolysis. Thus, the aforementioned NLSs may be targets for nickel toxicity. This implies that Ni(II) ions disrupt the transport of some proteins from cytoplasm to cell nucleus.

Multi-elemental analysis of human lung samples using inductively coupled plasma mass spectrometry

The aim of this study was to establish concentrations of a wide range of elements in human lung samples to allow better identification of potential exposures in subsequent cases. This study reports concentrations of 48 elements (Al, As, Au, B, Ba, Be, Bi, Br, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, Gd, Ge, Hf, Hg, In, Li, Mn, Mo, Nb, Ni, Os, Pb, Pd, Pt, Rb, Re, Ru, Sb, Se, Sm, Sn, Sr, Ta, Te, Ti, Tl, Tm, V, W, Y, Zn and Zr) in fresh lung tissue samples from 54 hospital patients, of which 93% exhibited various forms of neoplasia. The lung samples were taken from unaffected, background tissue. The samples were stored as fresh tissue in alcohol, dried and microwave digested before analysis by inductively coupled mass spectrometry (ICP-MS). It was possible to establish 95th percentiles for all elements except for rhenium and for 40 elements mixed effects modelling was undertaken. Overall, the levels reported are commensurate with ranges for those elements that had been reported previously. The data were examined for gender, smoking and occupational exposures to metals. The results show that males have higher lung concentrations of Ni, Cr, Gd, Au and Be than females, but significantly lower lung concentrations of Co, Sn, W and In. Cadmium lung concentrations were significantly higher in smokers. Platinum lung concentrations were higher in those who had undergone chemotherapy and gadolinium concentrations were predictably high in those who had undergone imaging scans. More essential elements such as Cu, Br, Fe and also Ge varied the least within lung samples from individuals whilst Be, Hf and Pt had the greatest variances. Between individuals V and Li lung concentrations varied the most, whilst Cu varied least. Analysis of the data for those who reported as having previously worked with metals showed 24 of the 48 elements determined were higher than those from those who had not reported working with metals.

Nickel(II)-induced nasal epithelial toxicity and oxidative mitochondrial damage

In probing the underlying mechanisms of nickel(II)-induced cytotoxicity on nasal epithelium, we investigated the effects of nickel(II) acetate on nasal epithelial RPMI-2650 cells. Nickel(II) elicited apoptosis, as signified by pyknotic and fragmented nuclei, increased caspase-3/7 activity, and an increase in annexin V binding, hypodiploid DNA, and Bax/Bcl-2 protein ratio. Nickel(II)-induced G2/M arrest was associated with up-regulation of p21(WAF1/CIP1) expression, decrease in phosphorylation at Thr(161) of Cdc2, and down-regulation of cyclin B1. Associated with these responses, ROS generation and mitochondrial depolarization increased in a nickel(II) concentration-dependent fashion. Pretreatment with N-acetylcysteine (NAC) attenuated these changes. p53 reporter gene assay and analyses of p53, Puma, Bax, and Bcl-2 protein levels indicated that NAC inhibited nickel(II)-induced activation of p53-mediated mitochondrial apoptotic pathway. Collectively, our study provides evidences that nickel(II) may induce oxidative damage on nasal epithelium in which antioxidant NAC protects cells against nickel(II)-induced apoptosis through the prevention of oxidative stress-mediated mitochondrial damage.

Nickel nanoparticles exposure and reproductive toxicity in healthy adult rats

Nickel is associated with reproductive toxicity. However, the reproductive toxicity of nickel nanoparticles (Ni NPs) is unclear. Our goal was to determine the association between nickel nanoparticle exposure and reproductive toxicity. According to the one-generation reproductive toxicity standard, rats were exposed to nickel nanoparticles by gavage and we selected indicators including sex hormone levels, sperm motility, histopathology, and reproductive outcome etc. Experimental results showed nickel nanoparticles increased follicle stimulating hormone (FSH) and luteinizing hormone (LH), and lowered etradiol (E₂) serum levels at a dose of 15 and 45 mg/kg in female rats. Ovarian lymphocytosis, vascular dilatation and congestion, inflammatory cell infiltration, and increase in apoptotic cells were found in ovary tissues in exposure groups. For male rats, the weights decreased gradually, the ratio of epididymis weight over body weight increased, the motility of rat sperm changed, and the levels of FSH and testosterone (T) diminished. Pathological results showed the shedding of epithelial cells of raw seminiferous tubule, disordered arrangement of cells in the tube, and the appearance of cell apoptosis and death in the exposure group. At the same time, Ni NPs resulted in a change of the reproductive index and the offspring development of rats. Further research is needed to elucidate exposure to human populations and mechanism of actions.

Metals in the lungs of Ontario hardrock miners

The objective of this study was to determine the concentration of nickel, cadmium, and lead in the autopsied lungs of 29 hardrock miners. It involved chemical analysis of the lungs, where each lung was divided horizontally into 3 sections and analyzed by an atomic absorption spectrophotometer equipped with a graphite furnace. The grand mean levels of nickel, cadmium, and lead were found to be 1.84, 1.74, and 2.75 μg/g of dry tissue, respectively. The effect of smoking was also examined. The ratios using the mean values between smoker and nonsmoker for nickel, cadmium, and lead were found to be 0.7, 5.4, and 1.4, respectively. The level of cadmium in smokers was significantly higher than nonsmokers. This study provides an estimate of retained metals in the lungs of the Ontario hardrock miners as a result of occupational exposure to hardrock mining environment.

Probing the metal-homeostatis effects of the administration of chromium(vi) to mice by ICP MS and size-exclusion chromatography-ICP MS

Concentrations of chromium, copper, iron, manganese and zinc were determined in liver, kidney, brain, lung, heart and testis of mouse following intraperitoneal injection of hexavalent chromium [Cr(vi)] at a single dose of 8.0 mg Cr/kg. As result, chromium concentrations increased ca. 40-fold in liver and kidney and by a factor of 3-5 in all the other tissues. The homeostasis of Cu, Fe, Mn and Zn was also affected. The element molecular weight distribution was evaluated in the cytosols of the different mouse organs by size-exclusion chromatography (Superdex-75) with UV-VIS and ICP-MS detection. The administration of Cr(vi) resulted in differences in the elution profiles of Fe, Mn, Cu and Zn-protein complexes. Bioinduced Mn, Fe and Zn-binding proteins could be detected in some tissues, especially in liver and kidney. Different molecular weight fractions containing chromium were heartcut and submitted to tryptic digestion prior to MALDI MS analysis. Cr-peptide complexes could be obtained both in non-denaturing and in denaturing (in the presence of urea and DTT) conditions. They were isolated by size-exclusion chromatography with a smaller separation range (Superdex Peptide) but could not be identified by MALDI MS.

Nickel decreases cellular iron level and converts cytosolic aconitase to iron-regulatory protein 1 in A549 cells

Nickel (Ni) compounds are well-established carcinogens and are known to initiate a hypoxic response in cells via the stabilization and transactivation of hypoxia-inducible factor-1 alpha (HIF-1alpha). This change may be the consequence of nickel's interference with the function of several Fe(II)-dependent enzymes. In this study, the effects of soluble nickel exposure on cellular iron homeostasis were investigated. Nickel treatment decreased both mitochondrial and cytosolic aconitase (c-aconitase) activity in A549 cells. Cytosolic aconitase was converted to iron-regulatory protein 1, a form critical for the regulation of cellular iron homeostasis. The increased activity of iron-regulatory protein 1 after nickel exposure stabilized and increased transferrin receptor (Tfr) mRNA and antagonized the iron-induced ferritin light chain protein synthesis. The decrease of aconitase activity after nickel treatment reflected neither direct interference with aconitase function nor obstruction of [4Fe-4S] cluster reconstitution by nickel. Exposure of A549 cells to soluble nickel decreased total cellular iron by about 40%, a decrease that likely caused the observed decrease in aconitase activity and the increase of iron-regulatory protein 1 activity. Iron treatment reversed the effect of nickel on cytosolic aconitase and iron-regulatory protein 1. To assess the mechanism for the observed effects, human embryonic kidney (HEK) cells over expressing divalent metal transporter-1 (DMT1) were compared to A549 cells expressing only endogenous transporters for inhibition of iron uptake by nickel. The inhibition data suggest that nickel can enter via DMT1 and compete with iron for entry into the cell. This disturbance of cellular iron homeostasis by nickel may have a great impact on the ability of the cell to regulate a variety of cell functions, as well as create a state of hypoxia in cells under normal oxygen tension. These effects may be very important in how nickel exerts phenotypic selection pressure to convert a normal initiated cell into a cancer cell.

Nickel essentiality, toxicity, and carcinogenicity

The increasing utilization of heavy metals in modern industries leads to an increase in the environmental burden. Nickel represents a good example of a metal whose use is widening in modern technologies. As the result of accelerated consumption of nickel-containing products nickel compounds are released to the environment at all stages of production and utilization. Their accumulation in the environment may represent a serious hazard to human health. Among the known health related effects of nickel are skin allergies, lung fibrosis, variable degrees of kidney and cardiovascular system poisoning and stimulation of neoplastic transformation. The mechanism of the latter effect is not known and is the subject of detailed investigation. This review provides an analysis of the current state in the field.

Metals in lung tissue from autopsy cases in Mexico City residents: comparison of cases from the 1950s and the 1980s

In autopsies performed on residents of Mexico City during the 1950s and 1980s (45 males and 24 females and 42 males and 42 females, respectively), concentrations of cadmium, copper, cobalt, nickel, and lead in the lungs were studied by atomic absorption spectrometry. Sharp increases were noted in samples taken in the 1980s compared to those from the 1950s. In samples from both time periods, the concentrations were influenced by gender. Smoking was not associated with higher levels of the metals. Only lead seemed to have a relation with age. The enormous differences by gender in the 1950s could be due to different patterns of exposure. The differences among samples from both periods appear to be associated with the increase of air pollutants in the metropolitan areas of Mexico City during the years under study. These results reinforce the importance of studying lung tissue to monitor air pollution by metals.

Biomonitoring of nickel and chromium in human pulmonary tissue

Nickel (Ni) and chromium (Cr) and some of its compounds may be able to induce cancer in the lungs as well as in the nose and paranasal sinuses after occupational exposure. Latency periods amount to 20 years and more. Therefore objective exposure data are not available in the most cases and expert evaluation of the causal connection is often difficult. Recent investigations have shown, that Ni and Cr can cumulate in human lung tissue after occupational exposure. For the evaluation of "normal" Ni- and Cr-values a total of 495 human lung tissue samples of 30 occupationally non-exposed persons were analysed by AAS including ZEEMAN-compensation after wet oxidative digestion. Additional samples of 10 deceased persons who have been occupationally exposed to nickel in previous times by nickel-refining and welding, especially flame spraying have been investigated. The median Ni- and Cr- concentrations in the lungs of the non-exposed persons ranged between 20-40 resp. 133-277 ng/g (wet weight). In nickel refinery workers Ni- concentrations were found which exceeded the normal range about 1,000. In welders, especially flame sprayers, also values more than 100 times higher could be analysed for Ni and Cr. Partially these concentrations were found years after the end of the inhalative exposure.

Metal concentrations in lung tissue of subjects suffering from lung cancer

Concentrations of nine metals (Fe, Ca, Mg, Zn, Cu, Co, Ni, Pb and Cr) concentrations in lung tissues from 224 lung cancer cases were compared with those in other cases to achieve an understanding of their contribution to the development of lung cancer and the varieties after the development of cancer. Comparisons of metal concentrations in each cell type of lung cancer were also performed. All cases were collected from routine autopsies in Tokyo and Saitama, Japan. The copper concentration in tissue from lung cancers was significantly higher than that in other specimens, although calcium, magnesium, zinc and cobalt concentrations in lung cancers were significantly lower than those in other cases. There were no significant differences in the 99% intervals (excluding extremely high values for occupationally exposed cases) for chromium, nickel and lead concentrations between lung cancers and other cases, although these values were lower in lung cancers. However, in comparisons of men only, the chromium concentration, the degree of lung contamination and the severity of pulmonary emphysema in lung cancer cases were significantly higher than those in other specimens. Moreover, percentages of lung cancer in men at each degree of contamination and each severity of emphysema increased with increasing grades. Thus, this finding could be evidence that the exposure to contaminants other than chromium and nickel in the air had affected the development of lung cancer, except for occupationally exposed individuals. Therefore, almost all chromium and nickel in lung tissue might not deposit in carcinogenic forms such as hexavalent chromium or nickel subsulfide.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased content of chromium and nickel in lung tissues from patients with bronchial carcinoma

Epidemiological studies have shown that occupational exposure to certain chromium and nickel compounds is followed by an increased lung cancer incidence. However, few data exist on the content of these metals in lung cancer patients in general. In the present study, central and peripheral lung tissue, bronchial tissue and hilar lymph nodes were collected from 20 patients with bronchial carcinoma and 21 control individuals, and the tissue concentration of chromium and nickel was measured by use of atomic absorption analysis. Increased levels of both metals were found in cancer patients as compared to controls. Lung tissue concentration of chromium was two-fold increased, while the bronchial wall content of nickel was three times the level in control individuals. Smokers showed a dose-related increase in the deposition of both chromium and nickel. Furthermore, in cancer patients an inverse relationship between smoking and the tissue level of chromium in regional lymph nodes was found, possibly indicating a depressive effect on pulmonary clearance mechanisms. Our results emphasize the possible role of small amounts of chromium and nickel as agents in bronchial carcinogenesis, unrelated to occupation and probably related to tobacco smoking.

Age, sex, and region adjusted concentrations of chromium and nickel in lung tissue

Chromium (Cr) and nickel (Ni) concentrations were measured in lung tissue from 110 random necropsies by means of atomic absorption spectrometry. The subjects originated from the Ruhr district (Bochum (71 cases) and Dortmund (16 cases) areas), which has been defined as a particular pollution area with locally high Cr and Ni emissions, and from Münster and vicinity (23 cases). The Cr and Ni concentrations in lung tissue of the subjects from the Ruhr district (3.09 (SD 2.99) micrograms Cr/g, 0.65 (SD 0.94) micrograms Ni/g dry weight of lung) were 4.8 and 2.8 times higher than those from Münster (0.66 (SD 0.49) micrograms Cr/g, 0.17 (SD 0.11) micrograms Ni/g dry weight of lung). Concentrations of Cr and Ni in men were twice those in women. All data showed an age dependent increase of Cr and Ni in the lung (about 2.4% a year for Cr and 3% a year for Ni) and Cr and Ni values showed a high correlation (r greater than or equal to 0.9). Thus it was possible to calculate age, sex, and region adjusted expected values of pulmonary Cr and Ni concentrations, and to identify the difference between expected and observed values. This might be helpful to interpret measurements in individual cases and in epidemiological studies. With this procedure the six cases of bronchial carcinoma in the series were shown to have pulmonary Cr and Ni concentrations that were mostly well above the predicted values, and it was possible to give a rough estimate of the degree of deviation.

Trace metal analysis of chromium and nickel in lung tissue fixed and stored in formalin

In an attempt to answer the question whether the determination of chromium and nickel concentration in lung tissue, fixed and stored in formalin is still tolerable despite the related sources of error, the entire system (tissue, tissue abrasion, formalin, plastic container) was analysed by means of flameless atomic absorption spectrometry. It appears that such a procedure can be justified for practical purposes. In order to reduce possible errors, well defined rules are to be observed during specimen collection and processing and specialities have to be taken into account.

Analyses of chromium and nickel in human pulmonary tissue. Investigations in lung cancer patients and a control population under special consideration of medical expertise aspects

After inhalative occupational exposure to certain compounds containing nickel and chromium (mostly over many years), an accumulation of these metals may occur in the lung tissue. This is of particular importance, both from a toxicological point of view and with regard to expert reports, since certain nickel and chromium compounds may induce lung cancers. In the context of this study, samples of pulmonary tissue from 34 deceased persons from the Bergen area (Norway) were analysed by atomic absorption spectrometry with regard to their content of chromium and nickel. The deceased comprised 21 men and 13 women. In 15 cases, death resulted from lung cancer; in the other 19 deceased, there was no indication of a malignant disease of the airways. The concentrations of nickel found in the lung tissue do not differ between patients with lung cancer and patients with healthy lungs. On the other hand, the concentration of chromium in the pulmonary tissue in the patients who had died of lung cancer and who had all been inhalative smokers, are higher (statistically significant) than in the nonsmokers or in those with healthy lungs. An accumulation of these two metals in the tumor matrix could not be detected. Both the average nickel and the average chromium concentrations were higher in the persons who had probably been exposed occupationally. Considering the present state of scientific knowledge, the aspects relevant to expert reports which result from the analyses of metals in the pulmonary tissue are discussed.

Determination of nickel in lung specimens of thirty-nine autopsied nickel workers

Lung specimens from 39 nickel refinery workers autopsied during the period from 1978 to 1984 were analyzed for nickel. Fifteen of the workers were employed in the Roasting and Smelting Department, where exposure to nickel was predominantly in the form of nickel-copper oxides, Ni3S2 and metallic dust. The remaining 24 men worked in the Electrolysis Department. Exposure in this group was considered to be mostly to the water-soluble compounds, NiSO4 and NiCl2, but also to a lesser degree to water-insoluble nickel compounds such as nickel-copper oxides and sulphides. The arithmetic mean +/- SD for nickel concentration in lung tissues expressed in micrograms g-1 dry wt for the 39 workers was 150 +/- 280. In the workers employed in the Roasting and Smelting Department, the average nickel concentration was 330 +/- 380; for those who worked in the Electrolysis Department it was 34 +/- 48. Lung tissue from 16 autopsied persons not connected with the refinery had an average nickel concentration of 0.76 +/- 0.39. Statistical analysis based on log-normal distributions of the measured nickel concentrations allowed three major conclusions to be formulated: (1) nickel refinery workers exhibit elevated nickel levels in lung tissues at autopsy; (2) workers of the Electrolysis Department and the Roasting Smelting Department constitute distinct groups with respect to the accumulation of nickel in lung tissue; (3) workers who were diagnosed to have lung cancer had the same lung nickel concentrations at autopsy as those who died of other causes.