Albumin as marker for susceptibility to metal ions in metal-on-metal hip prosthesis patients

Metal-on-metal (MoM) hip prostheses are known to release chromium and cobalt (Co), which negatively affect the health status, leading to prosthesis explant. Albumin (ALB) is the main serum protein-binding divalent transition metals. Its binding capacity can be affected by gene mutations or modification of the protein N-terminal region, giving the ischaemia-modified albumin (IMA). This study evaluated ALB, at gene and protein level, as marker of individual susceptibility to Co in MoM patients, to understand whether it could be responsible for the different management of this ion. Co was measured in whole blood, serum and urine of 40 MoM patients. A mutational screening of ALB was performed to detect links between mutations and metal binding. Finally, serum concentration of total ALB and IMA were measured. Serum total ALB concentration was in the normal range for all patients. None of the subjects presented mutations in the investigated gene. Whole blood, serum and urine Co did not correlate with serum total ALB or IMA, although IMA was above the normal limit in most subjects. The individual susceptibility is very important for patients’ health status. Despite the limited results of this study, we provide indications on possible future investigations on the toxicological response to Co.

Vanadium release in whole blood, serum and urine of patients implanted with a titanium alloy hip prosthesis

INTRODUCTION

Vanadium (V) is a minor constituent of the Titanium-Aluminum-Vanadium (TiAlV) alloy currently used in cementless hip prostheses. Present study aimed at verifying the correlation of vanadium levels among different matrices and assessing reference levels of the ion in a population of patients wearing a well-functioning hip prosthesis.

METHODS

Vanadium was measured using Inductive Coupled Plasma Mass Spectrometry (ICP-MS) in whole blood, serum and urine of 129 patients implanted with a TiAlV-alloy hip prosthesis.

RESULTS

The values in the serum were above the upper limit of the reference values in 42% of patients (29% in urine and 13% in whole blood). A good correlation among matrices was observed (p < 0.001). The cohort of patients (N = 32) complaining of pain or in which a loosening or damage to the prosthesis was assessed showed a significantly higher excretion of vanadium in urine as compared with the remaining asymptomatic patients (p = 0.001). The 95th percentile distribution of vanadium in the cohort of patients with a well-functioning prosthesis was 0.3 μg/L in whole blood, 0.5 μg/L in serum and 2.8 μg/L in urine, higher that in the unexposed population, especially for urine.

CONCLUSIONS

The presence of a prosthesis, even though well-functioning, may cause a possible release of vanadium into the blood and a significant urinary excretion. The reference values of vanadium of the asymptomatic patients with titanium alloy hip prostheses supplied information regarding the background exposure level of the ions and their lower and upper limits.

[Review from the scientific paper about the main respiratory diseases in metallurgical workers]

The review of main scientific investigations about the work related diseases in metallurgy shows that the most studied pathologies regards lung cancer and pneumoconiosis, other cancers and cardiovascular diseases. These evidences are not univocal and have been and are critically evaluated due to the complexity and articulated structure of metals production which makes it very difficult to compare the risks and diseases among the different metallurgical activities and, in the same activity, among the different job tasks. In addition, due to the technological and organizational evolution investigations, appear to be necessary to better define the specific hazards (for example metal species, PAH and PoPs mixtures) and to put into a correct relation these and pathologies diagnosed by health surveillance procedures or epidemiological surveys, surely different from those of past decades.

Cobalt, chromium and molybdenum ions kinetics in the human body: data gained from a total hip replacement with massive third body wear of the head and neuropathy by cobalt intoxication

INTRODUCTION

A patient with a total hip replacement developed optic, acoustic and peripheral neuropathy from metal ions intoxication, due to the wear products released from the prosthesis. Subsequently the kinetics of the metal ions was studied.

MATERIALS AND METHODS

Massive wear and acute intoxication allowed a study of the metal ions kinetics and of EDTA treatment.

RESULTS

Plasma and other organic fluids were saturated by each of the metal ions released from the exposed surface according to the solubility of each ion; a larger fraction of Co ions was bound within red cells, while the plasmatic fraction appeared more movable. In a patient with a prosthesis subjected to wear, the ions released are from the prosthetic and from the debris surface (spread in the body). The latter is a function of the number and size of particles.

DISCUSSION

Revision of the prosthesis from the point of view of the metal ions kinetics corresponded to a reduction of the releasing surface because of debris washed out by irrigation and tissue excision; however, the metal particles spread by lymphatic circulation continued to release ions even though the source of wear had been removed. Early diagnosis of high metal wear can be ascertained with mass spectrometry and after revision high levels of metal ions can only be reduced with repeated chelating treatment. It is preferable not to revise fractured ceramic components with a polyethylene-metal articulation.

Neurotoxicity of cobalt

Cobalt exerts well-known and documented toxic effects on the thyroid, heart and the haematopoietic system, in addition to the occupational lung disease, allergic manifestations and a probably carcinogenic action. Cobalt neurotoxicity is reported in isolated cases, and it has never been systematically treated. Bilateral optic atrophy and retinopathy, bilateral nerve deafness and sensory-motor polyneuropathy have been described long ago as a result of chronic occupational exposure to cobal powder or during long-term treatment of anaemia with cobalt chloride. Recently, some patients with high levels of cobalt released from metal prosthesis have been referred as presenting with tinnitus, deafness, vertigo, visual changes, optic atrophy, tremor and peripheral neuropathy. The aim of this work is to group these cases and to identify a possible mechanism of cobalt neurotoxicity, focusing on hypothetic individual susceptibility such as altered metal-binding proteins, altered transport processes in target cells or polymorphic variation of genetic background.

[Neurotoxic effects of cobalt: an open question]

Increased cobalt levels have been associated with neurological diseases (hand tremor, incoordination, cognitive decline, depression, vertigo, hearing loss and visual changes) in addition to "classic" and known cardiac diseases (arrhythmias and cardiomyopathies) and allergic or endocrine symptoms. Cobalt neurotoxicity is reported in isolated cases: old occupational or iatrogenic exposures and more recent releases of metallic ions by prosthesis. The studies of these cases have revealed a typical symptomatology of cobalt probably due to its ability to induce oxidative stress and mitochondrial alterations.

[IARC revision on dioxin and some dioxin-like compounds]

Since 1997 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has classified in Group 1 carcinogens by IARC essentially on based on mechanistic considerations. In the last review of human carcinogens IARC confirmed this classification also with epidemiological evidences. Following chemical-physical and mechanistics considerations, in particular the same AhR-mediated action, for two other dioxin-like compounds, the PCB126 and the PeCDF the classification in group 1 was suggested. This note reports and comments this IARC revision.

[Polychloro biphenils (PCBS) and cancer]

A lot of studies treat the issue of PCBs and cancer. The weight of evidence in studies of environmental exposure or increased mortality in subjects professionally exposed does not support a causal association for PCBs and human cancer. The main international agencies classified PCB as probable carcinogenicity, limited evidences in humans and sufficient on the animals. The present report would to resume the principals epidemiological and experimental studies with the purpose to show its weak and/or discordant points and to underline the critical aspects of the evaluation of the exposure. Critics are the identification of the congeners more diffused and persistent and therefore more representative and the correlation with early effects or specific metabolic alterations.

[Metallic elements in 31st updating of 67/548/EEC directive]

In this paper the update of directive 67/548/EEC published in Official Journal of the European Union on 16 January 2009 proposes about carcinogenicity of metallic elements is reported and discussed. The main change is represented by the classification R49 and R40 of many species of nickel, organic and inorganic, respectively for their water solubility and particles size. Titanium oxide and 3 tin species are in addition classified as R40. Sodium dichromate moved from R49 (in the 22nd update) to R45 (classified as carcinogen, without restriction on the route of exposure). The list of the 31st updates, if combined with previous list, provides detailed and more precise information on the carcinogenicity of metallic elements in relation to different species, suggesting once again the importance of metallic element speciation.

[Mechanisms of action for metallic elements and their species classified as R40 by EU]

In this part of our survey we dealt with other metallic elements and species (antimony, lead and vanadium) classified by EU as R40 and not with the risk phrases R45 and R49. They are also differently considered by different Agency and Scientific Societies in respect to their carcinogenicity. Also for Pb, Sb, V and related species the carcinogenic effect is related with oxidation state, charge, the solubility, type of binding, stereochemistry. Some common mechanisms of carcinogenesis are the induction of oxidative stress, to inhibition of DNA repair, from activation of mitogenic signalling, to epigenetic modification of gene expression and each species lead to specific molecular interactions and were subject to different bioavailability. We focused in particular the mechanisms of action for lead, element moved in last IARC examination from group 2B to group 2A, with important potential consequences for EU classification In general for metallic elements even differently classified in respect to their carcinogenicity, knowledge of action mechanisms would give additional tools to reach more adequate risk assessment procedures and the preventive-health surveillance measures.

Xenobiotic action on steroid hormone synthesis and sulfonation the example of lead and polychlorinated biphenyls

OBJECTIVES

In the present study, the metabolism of steroid hormones has been investigated to determine whether and how xenobiotics like lead (Pb) and polychlorinated biphenyls (PCBs) interfere with steroid hormone biotransformation in humans.

METHODS

Three groups of subjects were tested for concentration of urinary total steroids, 17-ketosteroids (n = 5), pregnane derivates (n = 6), 17-hydroxycorticosteroids (n = 11) and their sulfonated compounds: 14 workers exposed to lead, with a mean Pb blood concentration (PbB) of 29.21 microg/dl; 15 subjects exposed to PCBs, with a mean PCB blood concentration (PCBB) of 61.69 microg/l; a control group (n = 25).

RESULTS

The urinary concentrations of 17-ketosteroids and 17-hydroxycorticosteroids were significantly lower in the PCB-exposed groups. There were significantly fewer sulfonated 17-hydroxycorticosteroids in the subjects exposed to PCBs as compared to the controls, while the percentage of sulfonated steroids was lower for both 17-ketosteroids and 17-hydroxycorticosteroids in the PCB-exposed subjects, but only for the 17-hydroxycorticosteroids in the group of subjects exposed to Pb (P < 0.05). Pregnane derivate urinary concentrations did not differ between the three groups.

CONCLUSION

Our results suggest that PCBs and Pb act on steroid hormone metabolism with different effects and only partially using the same hormone pathways; they may cause changes in endogenous hormone homeostasis and interfere with the xenobiotic phase II of detoxification. PCBs interfere on a larger number of steroids and cause more significant effects than Pb. It is likely that different mechanisms are involved in steroid hormone metabolism interference.

[Mechanisms of action for metallic elements and their species classified carcinogen R 45 and R 49 by EU]

In this paper we will deal with mechanism of carcinogenic action of metallic elements and their species (arsenic, beryllium, cadmium, cobalt, chromium, nickel) identified by EU as carcinogen R 45 or R 49. The carcinogenic effect depended on the ability of to penetrate the cell and interacted with the target sites, therefore the state of oxidation, charging, the solubility, type of binding, stereochemistry and the ability to interact with other xenobiotics were crucial. The carcinogenic metallic elements classified R45 or R49 are essentially weak mutagen and do not form adducts with the DNA as initial step of their carcinogenicity In spite of the wide range of metallic elements physicochemical properties, some common general mechanisms of carcinogenesis emerge:from the induction of oxidative stress, to inhibition of DNA repair, from activation of mitogenic signalling, to epigenetic modification of gene expression. However, each species lead to specific molecular interactions and were subject to different bioavailability. It has been also strongly supported the hypothesis that the metallic elements may act as a co-carcinogen with other organic compounds, for example with PAH.

[Instruments for updating the occupational physician activities]

In this article the SIMLII (Italian Society of Industrial Medicine and Industrial Hygiene) experience about the production of Guide Lines during the last 5 years is evaluated at the light of the new Framework Act for the occupational safety and health "Decreto legislativo 81/08" signed by the President of the Italian Republic on April 9, 2008. This legislative act for the first time includes and defines in a legislative act the different possible instruments (technical normative, good practices, guide lines) for updating the activities of occupational physician. Some aspects related to definitions, significance, production of guide lines, consensus conference reports, good practices statements are presented and discussed.

[Potential and usefulness of the analysis of metallic elements in blood platelets]

Platelets represent an important fraction of blood, whose composition and interactions in many physiological and pathological processes were a subject of several studies. Determination of trace elements in this component was investigated in past studies (70-80's) on small samples and by analytical techniques giving rise to not always reliable results. This study was aimed at the development of a simple method for platelet isolation and determination of trace elements by inductively coupled plasma-mass spectrometry (ICP-MS). The method was applied on blood samples from 35 healthy males with mean age of 42.5 years. The obtained results gave us the opportunity to establish a reference range of trace elements in this matrix that can be used for the interpretation of results in occupationally/environmentally exposed people or hill subjects.

[Carcinogenicity of metallic elements: general considerations about their identification and monitoring and about their main mechanisms of action. Part 1: general aspects]

Some general aspects about identification and classification for metallic elements considered carcinogenic at different degree of risk and for different species such as Nickel, Arsenic, Chromium, Cadmium, Beryllium, Cobalt, Vanadium, Lead and Molybdenum are presented in this first paper. The main mechanisms of biological and toxicological action will be presented in a second related paper. The classification suggested by IARC, ACGIH, DFG and UE are in a good agreement only for some of the above mentioned metallic elements and consequently open questions remain in selecting the most adequate environmental and biological indicators and the related reference or limit values for planning risk assessment and health surveillance. The carcinogenic metals may have different effects on cellular functions including proliferation, apoptosis, cellular differentiation and transformation. leading to different cellular effects in relation to its chemical and physical properties and interactions with biomolecules. In the identification of metallic elements to be considered and of correct indicators both environmental and biological for exposure assessment appears to be necessary to identify the species of metallic element classified as carcinogenic in order to achieve an effective preventive measures and to plan appropriate health and epidemiological surveillance programmes.

Organ-specific manganese toxicity: a comparative in vitro study on five cellular models exposed to MnCl2

Manganese (Mn) is both an essential nutrient and a toxicant, with specific effects on liver and kidney (acute exposure) and on central nervous system (CNS) (chronic exposure). Mn neurotoxicity includes neurobehavioral disorders and extra-pyramidal motor dysfunctions (manganism), possibly due to focal injuries to the basal ganglia. Even if widely investigated, the molecular mechanisms responsible for Mn toxicity remain to be clarified. Aim of this study was to identify suitable in vitro models to investigate these molecular pathways. To this purpose we compared the effect of manganese chloride on four cell lines, representative of the main target organs of Mn toxicity in vivo. HepG2 and MDCK cell lines were selected for liver and kidney, respectively; glial GL15 and neuronal SHSY5Y cells were used as models of CNS components. To complete the "motor system" model, skeletal muscle C2C12 cells were also included. Our results demonstrate that hepatic, renal, glial and neuronal cell types differently react to Mn, mirroring the specific in vivo response of the tissue they represent. This confirms their value as suitable in vitro models to study Mn-related toxic events. Interestingly, also muscle C2C12 cells showed a noticeable sensitivity to Mn, preferential targets being differentiated myotubes.

[Inorganic lead stimulates endothelin secretion in the MDCK cell line]

BACKGROUND

Lead (Pb) is an environmental toxin whose acute intoxication causes haematological, gastrointestinal and neurological dysfunctions. Moreover it is well-established that prolonged exposure to low levels of inorganic Pb compounds is closely related to hypertension in experimental animals and occupationally exposed humans. Previous reports have suggested that endothelins (ETs), a family of peptides with potent vasoconstrictive properties, might be involved in the pathogenesis of lead-induced hypertension. In vivo studies demonstrated that rats chronically exposed to Pb low levels exhibited blood pressure elevation coupled with an increase of ET-3 concentration in plasma and urine in comparison with control animals.

OBJECTIVE

Since kidney is one of the target organs of lead injury, as well as the site of production/action of ETs, we investigated the effects of an inorganic Pb compound (Pb chloride) on the synthesis and secretion of these peptides, using, as in in vitro model, a renal-derived cell line (MDCK).

METHODS

The ETs assays in culture media of sub-confluent cell cultures exposed to different concentration of PbCl2 were performed by Enzyme linked Immunoassay (EIA), using two experimental procedures: a) cultures were exposed to 1100 and 200 microM PbCl2 for 30 min, next cells received Pb-free culture medium up to 24 h (pulse/chase experiment); b) cultures were fed continuously up to 24 h with treatment media containing the same PbCl2 concentrations (pulse experiment). Concomitantly, the Pb influence on cell viability was evaluated by different cytotoxicity assays (LDH release, DAPI staining and cell density assays). The mRNA expression of ET-1 was evaluated in pulse experiments by RT-PCR analysis before and after cell exposure to PbCl2. The Pb2+ cellular content of parallel MDCK cell cultures was assessed by AAS analysis.

RESULTS

In our experimental conditions, the administration of PbCl2 to sub-confluent MDCK cell cultures did not significantly affect cell viability. Either in pulse or in pulselchase experiments, the ETs content, evaluated in culture media of cells exposed to 100 microM PbCl2, significantly increased. On the contrary, cell treatment with 1 or 200 microM PbCl2 did not modify the ETs secretion. Because the amounts of ETs released in culture media were similar in both kinds of experiment, our results suggest that the metal induces the ETs secretion already after 30 min of cell exposure to the toxicant. Moreover, the ET-3 EIA specific assay did not reveal any immunoreactivity, excluding the involvement of this isoform in the Pb-induced secretion of ETs. Additionally, our results seem to exclude any Pb-induced up-regulation of ET-1 transcripts. The Pb2+ quantification in cell extracts demonstrated that the uptake of the metal is dose- and time-dependent and, in pulse experiments, it was maximum after six hours from the beginning of treatments, then the intracellular Pb2+ content decreased. This last phenomenon suggests the involvement of an ATP-dependent transporter in the mechanism of Pb cell excretion. Moreover, the ETs cell release in culture media of MDCK cells appears to depend on the intracellular content of Pb ions reached within 30 min of treatment.

CONCLUSION

Our results indicate that there is a range of PbCl2 doses (100 microM) at which MDCK cells enhance their ETs secretion. Lower doses (1 microM) of Pb salt seem to be ineffective to stimulate ETs release, while, doses equivalent to 200 microM seem to inhibit this phenomenon.

[Lead: indicators of dose and effects on heme]

In the present study the role of the traditional biomarkers of exposure and effect on haeme system during lead exposure was analysed: the opportunity of introducing new biomarkers such as lead and delta-aminolevulinic acid in plasma was also evaluated, especially by considering the current levels of exposure. The population in study was constituted by 371 males owning to different production fields and selected by five national units. The results suggest caution in the use of lead in plasma as a biomarker of lead exposure in the biological monitoring procedures, mainly in reason of its great variability affecting in particular the sampling time and the pre-analytical treatment of the sample. The other biomarkers were well correlated between them and with the exposure biomarkers for lead in blood >300 microg/L, suggesting the BEI to which the protection of workers exposed to lead would be guaranteed (instead the actual of 600 microg/L).

[New biomarkers of exposure]

In this paper we have defined the new biomarkers of exposure (NBE) as those biomarkers discovered in the last five years and, among previously validated biomarkers, also those applied in different ranges of doses or those determined in biological matrices which differ from matrices originally considered. We examined the results from the surveys carried out by the main Italian research units involved in biological monitoring, i.e. those from the Universities of Brescia, Milan, Naples, Padua, Parma, Pavia, Turin and Verona. The data were collected using a standardized model and included the following: type of element or organic compound, type of biomarker, analytical technique and method, their relationship with environmental monitoring data, their relationship with effect indicators or effects in general, improvement with respect to old biomarkers, reference values. Twenty two NBEs were identified: 14 elements and chemical compounds as such or as metabolites, 4 examples of mixtures, 3 of new matrices, one of speciation. Among the others, aspects such as interest in requiring NBE, quality assurance, availability, cost-benefit ratio were discussed. We conclude that development of this specific field of research appears to be a crucial point for future improvement in risk assessment and health surveillance procedures.

[Data quality and the interpretation of biological monitoring results]

Quality assurance criteria are not uniformly applied to routine biological determination, in particular with regard to the biomonitoring of exposure to organic solvents. Quality assurance is not an abstract concept but rather a flexible tool which can be adapted to different situations, such as the measurement of different exposure levels or the use of different analytical methods, for a range of purposes (routine determination, risk assessment procedures, research). The occupational health physician should be actively involved in the definition of quality objectives, as well as in checking that they have been implemented. This paper deals with some general issues regarding quality assurance, and in particular with certain requirements of analytical quality (analytical uncertainty, imprecision, bias) and its implementation (quality control, reference materials, standardization, reference values), contextualized to the biological monitoring of organic compounds and the relative metabolites.

[An important variability factor in determination of urinary activity of N-acetyl-beta-D-glucosaminidase: contamination of urine with semen]

BACKGROUND

Urinary N-acetyl-beta-D-glucosaminidase (U-NAG) and its isoenzyme B (U-NAG-B) have been demonstrated useful and early markers of renal damage, although they are present in many other tissues and organs.

OBJECTIVES

To evaluate semen contamination of the urine and its role in variability of U-NAG.

METHODS

To assess control group values beta2-microglobulin, retinol-binding protein and U-NAG were measured in the urine of 30 healthy, non-smoking and non metal-exposed adults (19 females and 11 males).

RESULTS

In four urine samples U-NAG was higher than the method reference value (5 U/g creatinine), without increases in other functional markers. Microscope examination revealed the presence of sperm in these samples. U-NAG variability decreased after the exclusion of these four values. The role of contamination was confirmed by adding semen to urine: when semen to urine ratio was 1:1000, enzyme activity was more than twice the basal level.

CONCLUSIONS

U-NAG variability is strongly increased by contamination with semen, where enzyme concentration (especially NAG-B) is very high. Increased excretion of U-NAG and of its iso-form (U-NAG-B) in males, not correlated with other renal alterations or with exposure to heavy metals or other renal toxic substances, should be carefully evaluated and microscopic observation is advisable to detect the presence of sperm in urine.

Metanalytical assessment of reference values for polychlorinated biphenyl in human blood

Due to their physico-chemical characteristics, polychlorinated biphenyls (PCBs) are highly persistent in the environment and therefore easily measured in the biological matrices of more and more large groups of general population. For these reasons it would be useful to determine suitable Reference Values (RVs) for these xenobiotics. In this paper, a metanalysis to the published data on PCBs values in human blood is presented. This investigation was carried out in order to reach adequate information on their RVs and to focus some specific topics to be taken into account when producing directly RVs for PCBs. The PCBs RVs resulted between 1.2 e 8.28 microg/L for males and between 2.69 e 5.17 microg/L for females the general range varied from 0.9 to 56 microg/L. The main criticisms in the assessment of RVs for PCBs resulted: the number of examined subjects; the inclusion and stratification criteria; the analytical method adopted and their quality assurance; the type and number of congeners to be determined and their specific quantification; the calculation of blood PCBs concentration (weight/volume or weight/lipids); the statistical analysis and in particular the treatment of not detectable data.

[Indicators of pulmonary epithelial damage among workers at a foundry exposed to airborne pollutants]

Foundry ambient air contains very high concentrations of noxious substances, such as particulate matter and gaseous pollutants, which can target the respiratory epithelium. Serum concentrations of the 16-kDa Clara cell protein (CC16-S) may reflect both the integrity of the epithelial barrier and smoke-induced Clara cell toxicity. To evaluate whether CC16-S is a sensitive biomarker of early respiratory disturbances, it was determined in a group of 35 foundry male workers (aged 41.1 +/- 6.9 years) examined both prior to and at the end of their work-shift (06:00 a.m.-02:00 p.m.). Exposure to inhalable/respirable dusts and PAH was characterized; urinary excretion of 1-hydroxypyrene (1-OH-P) and naphtol was measured to assess exposure to pyrene and naphthalene, respectively. CC16 serum levels decreased at the end of the shift (10.7 +/- 3.82 micrograms/L vs. 8.39 +/- 3.05 micrograms/L; p < 0.01); such decrements were significantly larger in more exposed workers. Although smokers had lower baseline values as compared to non smokers, both subgroups showed an average decrease of 30% in CC16-S concentrations at the end of shift. CC16-S was also negatively correlated with 1-OH-P, but not with naphtol concentrations. Decreased CC16-S levels can result from citotoxicity and would represent an useful biomarker of pneumotoxicity in foundry workers exposed to complex mixtures.