Simona Catalani

Loss of sight and sound. Could it be the hip

In September, 2007, a 58-year-old woman was admitted to our neurology department because of progressive visual and hearing loss which had started 9 months earlier. She had type 2 diabetes and hypertension, both of which were adequately controlled by medication. In 2001, she had a left hip arthroplasty which was revised in October, 2006 because of rupture of the ceramic head. 3 weeks before admission, investigations showed a mild hypothyroidism of unknown origin, which was treated with levothyroxine sodium. The neurological examination at admission showed impairment of cranial nerves II and VIII bilaterally and mild distal sensory-motor dis turbances. Laboratory investigations ruled out haema tological, infectious, neoplastic, metabolic, and immuno logical diseases. Concomitantly our patient underwent various investigations including brain MRI (showing hyperintensity of optic nerves and tracts), electromyography (showing mild lower limb nerve amplitude reduction), and acoustic and visual evoked potentials (positive for bilateral absence of brainstem acoustic responses and irregular cortical visual responses). A working diagnosis of axonal multi-neuropathy caused by a presumed immune-mediated vasculitis was made and the patient was given prednisone (50 mg/day) for 2 months with little improvement. By December, 2007, our patient became completely blind, severely deaf, and wheel-chair bound because of lower limb hyposthenia. Tests for immune-mediated process remained negative and the case was referred to toxicology for further investigation. Unexpectedly, raised concentrations of cobalt and chromium were found in diff erent biological samples (cobalt: 24 h urine collection 1187 μg/L [0·1–1·5], blood 549 μg/L [0·05–2·7], plasma 90 μg/L [0·1–0·6], CSF 11·4 μg [0·05–0·15]; chromium: 24 h urine collection 510 μg/L [0·05–2·2], blood 54 μg/L [0·1–0·5], plasma 210 μg/L [0·1–0·5], CSF 4·4 μg/L [0·01–0·2]). Cobalt-chromium poisoning due to metal wear debris from her hip prosthesis was proposed, although radiology, including CT, showed no sign of prosthesis loosening. In February, 2008, several metal ion chelating treatments were given with edetic acid. Although metal ion concentrations decreased, neurological improve ment was negligible. Therefore, in April, 2008, resection arthroplasty was done. During surgery infi ltration of the peri-prosthesic tissue by metallic debris was evident (fi gure A); analysis of peri-prosthetic fl uids showed high concentrations of cobalt and chromium, and the removed prosthesis showed wear of the head and neck (fi gure B), supporting the hypothesis of endogenous cobalt-chromium poisoning. During the following 8 months the patient showed progressive improvement, although vision only partially improved. Metal ion concentrations decreased but remained higher than reference values at the last follow-up in November, 2008. The role of cobalt or cobalt-chromium on human tissues has not been defi nitively established. Cobalt can produce various toxicological eff ects including local respiratory symptoms due to inhalation of cobalt containing dusts, and systemic eff ects (thyroiditis, cardiomyopathy, erythropoiesis). Neuro logical toxicity, mainly optic atrophy, nerve deafness, and limb paraesthesia, has been occasionally reported in association with exogenous exposure. Neuro logical toxicity as a reult of endogenous exposure (mainly associated with metal prostheses) has been described. Cobalt can induce a hypoxia-like eff ect, possibly targeting mitochondria; of note, our patient’s symptoms were similar to those observed in some mitochondrial cytopathies. Total hip replacement and hip resurfacing arthroplasty are widely used therapeutic procedures; longer-term follow-up would be necessary to evaluate adverse chronic systemic eff ects due to prolonged exposure to high serum cobalt concentrations. In addition to orthopaedic evaluation, careful neurological and toxicological examinations are recommended whenever a patient with a metallic prosthesis complains of visual loss, hearing disturbance, limb weakness, numbness, or paraesthesia, even in the absence of local osteoarticular symptoms.

Exhaled breath condensate as a suitable matrix to assess lung dose and effects in workers exposed to cobalt and tungsten.

The aim of the present study was to investigate whether exhaled breath condensate (EBC), a fluid formed by cooling exhaled air, can be used as a suitable matrix to assess target tissue dose and effects of inhaled cobalt and tungsten, using EBC malondialdehyde (MDA) as a biomarker of pulmonary oxidative stress. Thirty-three workers exposed to Co and W in workshops producing either diamond tools or hard-metal mechanical parts participated in this study. Two EBC and urinary samples were collected: one before and one at the end of the work shift. Controls were selected among nonexposed workers. Co, W, and MDA in EBC were analyzed with analytical methods based on mass spectrometric reference techniques. In the EBC from controls, Co was detectable at ultratrace levels, whereas W was undetectable. In exposed workers, EBC Co ranged from a few to several hundred nanomoles per liter. Corresponding W levels ranged from undetectable to several tens of nanomoles per liter. A parallel trend was observed for much higher urinary levels. Both Co and W in biological media were higher at the end of the work shift in comparison with preexposure values. In EBC, MDA levels were increased depending on Co concentration and were enhanced by coexposure to W. Such a correlation between EBC MDA and both Co and W levels was not observed with urinary concentration of either element. These results suggest the potential usefulness of EBC to complete and integrate biomonitoring and health surveillance procedures among workers exposed to mixtures of transition elements and hard metals.

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.

11:Metal Ions Affecting Reproduction and Development

Many metal ions (lead, mercury, arsenic, cadmium, chromium, nickel, vanadium, copper, lithium) exert a wide variety of adverse effects on reproduction and development, including influence on male and female subfertility or fertility, abortions, malformations, birth defects, and effects on the central nervous system. The effects produced by metal ions depend on several factors, such as timing and duration of exposure, their distribution and accumulation in various organs (e.g., the nervous system), and on the interference with specific developmental processes. Neonatal and early postnatal periods are lifespan segments during which sensitivity to metals is high; e.g., lead toxicity on the developing organism is paradigmatic of related well known and still open questions. In more recent decades, important mechanisms of action have been suggested: the endocrine disruption via impact of metal ions on reproductive hormones and the oxidative stress. While experimental data provide clear evidence of effects of many metals, human data are scant and traditionally limited to high levels of a few metal ions, like lead on male fertility. Less documented are reproductive effects for mercury, manganese, chromium, nickel, and arsenic for the same gender. More complex is the demonstration of effects on female reproduction and on pregnancy. The action of lead, arsenic, cadmium, chromium, and mercury may in fact be relevant in several stages, beginning in fetal life, during early development or maturity, and is characterized by subfertility, infertility, intrauterine growth retardation, spontaneous abortions, malformations, birth defects, postnatal death, learning and behavior deficits, and premature aging. Also, for females the evidences of specific aspects such as fertility or abortions are usually higher and clearer from animal experiments than from human studies.

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

IntroductionA 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 methodsMassive wear and acute intoxication allowed a study of the metal ions kinetics and of EDTA treatment.ResultsPlasma 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.DiscussionRevision 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.

High doses of cobalt induce optic and auditory neuropathy.

The adverse biological effects of continuous exposure to cobalt and chromium have been well defined. In the past, this toxicity was largely an industrial issue concerning workers exposed in occupational setting. Nevertheless, recent reports have described a specific toxicity mediated by the high levels of cobalt and chromium released by metallic prostheses, particularly in patients who had received hip implants. Clinical symptoms, including blindness, deafness and peripheral neuropathy, suggest a specific neurotropism. However, little is known about the neuropathological basis of this process, and experimental evidence is still lacking. We have investigated this issue in an experimental setting using New Zealand White rabbits treated with repeated intravenous injections of cobalt and chromium, alone or in combination. No evident clinical or pathological alterations were associated after chromium administration alone, despite its high levels in blood and tissue while cobalt-chromium and cobalt-treated rabbits showed clinical signs indicative of auditory and optic system toxicity. On histopathological examination, the animals showed severe retinal and cochlear ganglion cell depletion along with optic nerve damage and loss of sensory cochlear hair cells. Interestingly, the severity of the alterations was related to dosages and time of exposure. These data confirmed our previous observation of severe auditory and optic nerve toxicity in patients exposed to an abnormal release of cobalt and chromium from damaged hip prostheses. Moreover, we have identified the major element mediating neurotoxicity to be cobalt, although the molecular mechanisms mediating this toxicity still have to be defined.

Lack of Correlation Between Metallic Elements Analyzed in Hair by ICP-MS and Autism

A cross-sectional case–control study was carried out to evaluate the concentrations of metallic elements in the hair of 44 children with diagnosis of autism and 61 age-balanced controls. Unadjusted comparisons showed higher concentrations of molybdenum, lithium and selenium in autistic children. Logistic regression analysis confirmed the role of risk factor for male gender and showed a slight association with molybdenum concentrations. Unconventional chelation and vitamin-mineral supplementation were ineffective on elemental hair concentrations. A meta-analysis including the present and previous similar studies excluded any association of autism with hair concentrations of mercury, cadmium, selenium, lithium and copper. A slight association was found for lead only, but it was very weak, as strictly dependent on the worst data from one study.

The role of albumin in human toxicology of cobalt: contribution from a clinical case.

The distribution and adverse effects, especially to optic and acoustic nerves, of cobalt released from a hip arthroplasty and its association with albumin were studied. The analysis of cobalt was performed in plasma, whole blood, urine, and cerebrospinal fluid by inductively coupled plasma mass spectrometry (ICP-MS). The fraction of albumin binding the metal was determined by colorimetric assay using dithiothreitol (DTT). In all the biological matrices very high levels of cobalt were measured, but contrary to expected, a higher concentration in whole blood than in plasma was observed. The determination of altered albumin confirmed this hypothesis. This evidence might indicate an alteration in the binding of cobalt to albumin and a consequent increase in the concentration of the diffusible (free) fraction of the metal. This appears an interesting starting point for further investigations for identifying and better understanding cobalt neurotoxicity, apparently not so frequent in occupational medicine and clinical practice.

Cobalt triggers necrotic cell death and atrophy in skeletal C2C12 myotubes

Severe poisoning has recently been diagnosed in humans having hip implants composed of cobalt-chrome alloys due to the release of particulate wear debris on polyethylene and ceramic implants which stimulates macrophagic infiltration and destroys bone and soft tissue, leading to neurological, sensorial and muscular impairments. Consistent with this premise, in this study, we focused on the mechanisms underlying the toxicity of Co(II) ions on skeletal muscle using mouse skeletal C2C12 myotubes as an in vitro model. As detected using propidium iodide incorporation, increasing CoCl2 doses (from 5 to 200μM) affected the viability of C2C12 myotubes, mainly by cell necrosis, which was attenuated by necrostatin-1, an inhibitor of the necroptotic branch of the death domain receptor signaling pathway. On the other hand, apoptosis was hardly detectable as supported by the lack of caspase-3 and -8 activation, the latter resulting in only faint activation after exposure to higher CoCl2 doses for prolonged time points. Furthermore, CoCl2 treatment resulted in atrophy of the C2C12 myotubes which was characterized by the increased expression of HSP25 and GRP94 stress proteins and other typical `pro-atrophic molecular hallmarks, such as early activation of the NF-kB pathway and down-regulation of AKT phosphorylation, followed by the activation of the proteasome and autophagy systems. Overall, these results suggested that cobalt may impact skeletal muscle homeostasis as an inducer of cell necrosis and myofiber atrophy.

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

Abstract 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.