In vivo corrosion, tumor outcome, and microarray gene expression for two types of muscle-implanted tungsten alloys

Immediate and Sustained Effects of Cobalt and Zinc-Containing Pigments on Macrophages

Pigments are among the oldest nanoparticulate products known to mankind, and their use in tattoos is also very old. Nowadays, 25% of American people aged 18 to 50 are tattooed, which poses the question of the delayed effects of tattoos. In this article, we investigated three cobalt [Pigment Violet 14 (purple color)] or cobalt alloy pigments [Pigment Blue 28 (blue color), Pigment Green 14 (green color)], and one zinc pigment [Pigment White 4 (white color)] which constitute a wide range of colors found in tattoos. These pigments contain microparticles and a significant proportion of submicroparticles or nanoparticles (in either aggregate or free form). Because of the key role of macrophages in the scavenging of particulate materials, we tested the effects of cobalt- and zinc-based pigments on the J774A.1 macrophage cell line. In order to detect delayed effects, we compared two exposure schemes: acute exposure for 24 hours and an exposure for 24 hours followed by a 3-day post-exposure recovery period. The conjunction of these two schemes allowed for the investigation of the delayed or sustained effects of pigments. All pigments induced functional effects on macrophages, most of which were pigment-dependent. For example, Pigment Green 19, Pigment Blue 28, and Pigment White 4 showed a delayed alteration of the phagocytic capacity of cells. Moreover, all the pigments tested induced a slight but significant increase in tumor necrosis factor secretion. This effect, however, was transitory. Conversely, only Pigment Blue 28 induced both a short and sustained increase in interleukin 6 secretion. Results showed that in response to bacterial stimuli (LPS), the secretion of tumor necrosis factor and interleukin 6 declined after exposure to pigments followed by a recovery period. For chemoattractant cytokines (MCP-1 or MIP-1α), delayed effects were observed with a secretion decreased in presence of Pigment Blue 28 and Pigment violet 14, both with or without LPS stimuli. The pigments also induced persisting changes in some important macrophage membrane markers such as CD11b, an integrin contributing to cell adhesion and immunological tolerance. In conclusion, the pigments induced functional disorders in macrophages, which, in some cases, persist long after exposure, even at non-toxic doses.

Pulmonary toxicity, genotoxicity, and carcinogenicity evaluation of molybdenum, lithium, and tungsten: A review

Molybdenum, lithium, and tungsten are constituents of many products, and exposure to these elements potentially occurs at work. Therefore it is important to determine at what levels they are toxic, and thus we set out to review their pulmonary toxicity, genotoxicity, and carcinogenicity. After pulmonary exposure, molybdenum and tungsten are increased in multiple tissues; data on the distribution of lithium are limited. Excretion of all three elements is both via faeces and urine. Molybdenum trioxide exerted pulmonary toxicity in a 2-year inhalation study in rats and mice with a lowest-observed-adverse-effect concentration (LOAEC) of 6.6 mg Mo/m³. Lithium chloride had a LOAEC of 1.9 mg Li/m³ after subacute inhalation in rabbits. Tungsten oxide nanoparticles resulted in a no-observed-adverse-effect concentration (NOAEC) of 5 mg/m³ after inhalation in hamsters. In another study, tungsten blue oxide had a LOAEC of 63 mg W/m³ in rats. Concerning genotoxicity, for molybdenum, the in vivo genotoxicity after inhalation remains unknown; however, there was some evidence of carcinogenicity of molybdenum trioxide. The data on the genotoxicity of lithium are equivocal, and one carcinogenicity study was negative. Tungsten seems to have a genotoxic potential, but the data on carcinogenicity are equivocal. In conclusion, for all three elements, dose descriptors for inhalation toxicity were identified, and the potential for genotoxicity and carcinogenicity was assessed.

Oxidative damage in metal fragment-embedded Sprague-Dawley rat gastrocnemius muscle

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War often results in shrapnel injuries with metals whose toxicity might be unknown.

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A rodent model was used to study-eight military-relevant metals implanted in muscle.

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Creatine kinase activity, protein oxidation and antioxidant capacity were assessed.

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Data obtained were metal-dependent and not all metals showed identical results.

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Results suggest that subtle damage occurs in muscle surrounding metal shrapnel.

Injuries suffered in armed conflicts often result in wounds with embedded metal fragments. Standard surgical guidance has been to leave fragments in place except under certain circumstances; meaning that individuals may carry these retained fragments for their lifetime. Because of advancements in weapon design and the use of improvised explosive devices, the list of metals that could be found in a wound is extensive. In most cases the toxicological properties of these metals when embedded in the body are not known. To assess the potential damage embedded metals may cause to surrounding tissue, we utilized a rodent model to investigate the effect of a variety of military-relevant metals on markers of oxidative damage. The metals tested included tungsten, nickel, cobalt, iron, copper, aluminum, lead, and depleted uranium. Herein we report our findings on creatine kinase activity, lipid and protein oxidation, total antioxidant capacity, and glutathione levels in gastrocnemius homogenates from Sprague-Dawley rats surgically implanted with metal pellets for periods up to 12 months. Not all embedded metals affected the measured markers equally. However, metal-associated effects were seen at various times for muscle and serum creatinine levels, protein oxidation, total antioxidant capacity, and glutathione levels. No metal-induced effects on lipid peroxidation were observed. Taken together, these data suggest that subtle oxidative damage may be occurring in the muscle surrounding an embedded metal and indicates the need for medical surveillance of those individuals wounded by metal shrapnel.

Protein Expression in the Gastrocnemius Muscle of a Rodent Shrapnel-Injury Model

With shrapnel injuries, the metal fragment is usually left in place to reduce the risk of morbidity extensive surgery might bring. This means the individual may retain those metals for the remainder of their life. Often the long-term health effects of the embedded metal are not known, especially with respect to protein damage and perturbations of muscle repair pathways. In this study, using homogenates of rat gastrocnemius muscle implanted with pellets of military-relevant metals, we investigated expression of iNOS and eNOS, enzymes involved in nitric oxide production, as well as MMP-2 and MMP-9, matrix metalloproteinases associated with muscle repair. In addition, hydroxynonenal-modified proteins were investigated to assess metal-induced oxidative damage and metal levels in the gastrocnemius determined. Metals were implanted for up to 12 months in order to determine the long-term effects on the expression of muscle-associated proteins. With the exception of iron and cobalt at 1-month post-implantation, there were no significant differences in metal levels in the gastrocnemius in any of the cohorts. Protein expression analysis showed significant decreases in iNOS and eNOS in the 6-month and 12-month lead and depleted uranium groups. Hydroxynonenal-modified proteins were also significantly increased in the iron, copper, lead, and depleted uranium groups. These results suggest that some embedded metals can induce long-term oxidative damage, as well as affect enzyme systems involved in signal transduction.

Urine miRNAs as potential biomarkers for systemic reactions induced by exposure to embedded metal

Aim: Explore the potential of urine microRNAs as biomarkers that may reflect the biological responses to pure metals embedded in skeletal muscle over time. Materials & methods: We tested a panel of military-relevant metals embedded in the gastrocnemius muscles of 3-month-old, male, Sprague-Dawley rats (n = 8/group) for a duration of 1, 3, 6 and 12 months, and performed small RNA-sequencing on the urine samples. Results: Results provide potential tissue targets affected by metal exposure and a list of unique or common urine microRNA biomarkers indicative of exposure to various metals, highlighting a complex systemic response. Conclusion: We have identified a panel of miRNAs as potential urine biomarkers to reflect the complex systemic response to embedded metal exposure.

Spectroscopic and Spectrometric Approaches for Assessing the Composition of Embedded Metals in Tissues

Many medical devices contain metals that interface with the body. Additionally, embedded metal fragments from military wounds are typically not removed, to avoid the risk of morbidity associated with invasive surgery. The long-term health consequences of many of these materials are not thoroughly understood. To this end, we have exposed rats for up to one year to implanted single-element metal pellets of any one of Al, Co, Cu, Fe, Ni, Pb, Ta, or W. Various tissues were harvested and flash frozen for analysis of their metal distribution. We discuss approaches to most thoroughly and reliably evaluate the distribution of metal in these tissues. The path to the most appropriate analytical technique took us through extensive examination of the tissues using scanning electron microscopy with energy dispersive X-ray spectroscopy (XPS), X-ray photoelectron spectroscopy (XPS), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Though any one of these methods is highly relied upon in surface chemistry analysis, LA-ICP-MS alone showed presence of metal in the tissue. This information will help build robust methods to bridge the gap in our understanding of biosolubility and distribution of embedded metal throughout the body.

Effect of embedded metal fragments on urinary metal levels and kidney biomarkers in the Sprague-Dawley rat

BACKGROUND

Wounds with embedded metal fragments are an unfortunate consequence of armed conflicts. In many cases the exact identity of the metal(s) and their long-term health effects, especially on the kidney, are not known.

AIM OF STUDY

The aim of this study was to quantitate the urinary levels of metals solubilized from surgically implanted metal pellets and to assess the effect of these metals on the kidney using a battery of biomarker assays.

MATERIALS AND METHODS

Using a rodent model system developed in our Institute to simulate embedded fragment injuries, eight metals considered likely components of an embedded fragment wound were individually implanted into the gastrocnemius muscle of male Sprague-Dawley rats. The rats were followed for 12 months post-implantation with urine collected prior to surgery then at 1-, 3-, 6-, 9-, and 12-months post-implantation to provide a within-subjects cohort for examination. Urinary metal levels were determined using inductively coupled plasma-mass spectrometry and urinary biomarkers assessed using commercially available kits to determine metal-induced kidney effects.

RESULTS

With few exceptions, most of the implanted metals rapidly solubilized and were found in the urine at significantly higher levels than in control animals as early as 1-month post-implantation. Surprisingly, many of the biomarkers measured were decreased compared to control at 1-month post-implantation before returning to normal at the later time points. However, two metals, iron and depleted uranium, showed increased levels of several markers at later time points, yet these levels also returned to normal as time progressed.

CONCLUSION

This study showed that metal pellets surgically implanted into the leg muscle of Sprague-Dawley rats rapidly solubilized with significant levels of the implanted metal found in the urine. Although kidney biomarker results were inconsistent, the changes observed along with the relatively low amounts of metal implanted, suggest that metal-induced renal effects need to be considered when caring for individuals with embedded metal fragment wounds.

Brain region- and metal-specific effects of embedded metals in a shrapnel wound model in the rat

The health effects of prolonged exposure to embedded metal fragments, such as those found in shrapnel wounds sustained by an increasing number of military personnel, are not well known. As part of a large collaborative effort to expand this knowledge, we use an animal model of shrapnel wounds originally developed to investigate effects of embedded depleted uranium to investigate effects of military-relevant metals tungsten, nickel, cobalt, iron, copper, aluminum, lead, and depleted uranium compared to an inert control, tantalum. Rats are surgically implanted with pellets of one of the metals of interest in the gastrocnemius (leg) muscle and tracked until 1 month, 3 months, 6 months, or 12 months from the time of implant, at which point they are euthanized and multiple organs and tissue samples are collected for inspection. Here we focus on four regions of the brain: frontal cortex, hippocampus, amygdala, and cerebellum. We examined changes in accumulated metal concentration in each region as well as changes in expression of proteins related to blood brain barrier tight junction formation, occludin and ZO-1, and synapse function, PSD95, spinophilin, and synaptotagmin. We report few changes in metal accumulation or blood brain barrier protein expression, but a large number of synapse proteins have reduced expression levels, particularly within the first 6 months of exposure, but there are regional and metal-specific differences in effects.

Time-course analysis of the effect of embedded metal on skeletal muscle gene expression

As a consequence of military operations, many veterans suffer from penetrating wounds and long-term retention of military-grade heavy metal fragments. Fragments vary in size and location, and complete surgical removal may not be feasible or beneficial in all cases. Increasing evidence suggests retention of heavy metal fragments may have serious biological implications, including increased risks for malignant transformation. Previous studies assessed the tumorigenic effects of metal alloys in rats, demonstrating combinations of metals are sufficient to induce tumor formation after prolonged retention in skeletal muscle tissue. In this study, we analyzed transcriptional changes in skeletal muscle tissue in response to eight different military-relevant pure metals over 12 mo. We found that most transcriptional changes occur at 1 and 3 mo after metal pellets are embedded in skeletal muscle and these effects resolve at 6 and 12 mo. We also report significant immunogenic effects of nickel and cobalt and suppressive effects of lead and depleted uranium on gene expression. Overall, skeletal muscle exhibits a remarkable capacity to adapt to and recover from internalized metal fragments; however, the cellular response to chronic exposure may be restricted to the metal-tissue interface. These data suggest that unless affected regions are specifically captured by biopsy, it would be difficult to reliably detect changes in muscle gene expression that would be indicative of long-term adverse health outcomes.

Gene expression in mouse muscle over time after nickel pellet implantation

The transition metal nickel is used in a wide variety of alloys and medical devices. Nickel can cause a range of toxicities from allergy in humans to tumors when implanted in animals. Several microarray studies have examined nickel toxicity, but so far none have comprehensively profiled expression over an extended period. In this work, male mice were implanted with a single nickel pellet in the muscle of the right leg with the left leg used as a control. At 3 week intervals up to 12 months, nickel concentrations in bioflulids and microarrays of surrounding tissue were used to track gene expression patterns. Pellet biocorrosion resulted in varying levels of systemic nickel over time, with peaks of 600 μg L-1 in serum, while global gene expression was cyclical in nature with immune related genes topping the list of overexpressed genes. IPA and KEGG pathway analyses was used to attribute overall biological function to changes in gene expression levels, supported by GO enrichment analysis. IPA pathways identified sirtuin, mitochondria, and oxidative phosphorylation as top pathways, based predominantly on downregulated genes, whereas immune processes were associated with upregulated genes. Top KEGG pathways identified were lysosome, osteoclast differentiation, and phasgosome. Both pathway approaches identified common immune responses, as well as hypoxia, toll like receptor, and matrix metalloproteinases. Overall, pathway analysis identified a negative impact on energy metabolism, and a positive impact on immune function, in particular the acute phase response. Inside the cell the impacts were on mitochondria and lysosome. New pathways and genes responsive to nickel were identified from the large dataset in this study which represents the first long-term analysis of the effects of chronic nickel exposure on global gene expression.

Comparative Assessment of Tungsten Toxicity in the Absence or Presence of Other Metals

Tungsten is a refractory metal that is used in a wide range of applications. It was initially perceived that tungsten was immobile in the environment, supporting tungsten as an alternative for lead and uranium in munition and military applications. Recent studies report movement and detection of tungsten in soil and potable water sources, increasing the risk of human exposure. In addition, experimental research studies observed adverse health effects associated with exposure to tungsten alloys, raising concerns on tungsten toxicity with questions surrounding the safety of exposure to tungsten alone or in mixtures with other metals. Tungsten is commonly used as an alloy with nickel and cobalt in many applications to adjust hardness and thermal and electrical conductivity. This review addresses the current state of knowledge in regard to the mechanisms of toxicity of tungsten in the absence or presence of other metals with a specific focus on mixtures containing nickel and cobalt, the most common components of tungsten alloy.

Hydrophobic Sand Is a Non-Toxic Method of Urine Collection, Appropriate for Urinary Metal Analysis in the Rat

Hydrophobic sand is a relatively new method of urine collection in the rodent, comparable to the established method using a metabolic cage. Urine samples are often used in rodent research, especially for biomarkers of health changes after internal contamination from embedded metals, such as in a model of a military shrapnel wound. However, little research has been done on the potential interference of hydrophobic sand with urine metal concentrations either by contamination from the sand particulate, or adsorption of metals from the urine. We compare urine collected from rats using the metabolic cage method and the hydrophobic sand method for differences in metal concentration of common urinary metals, and examine physical properties of the sand material for potential sources of contamination. We found minimal risk of internal contamination of the rat by hydrophobic sand, and no interference of the sand with several common metals of interest (cobalt, strontium, copper, and manganese), although we advise caution in studies of aluminum in urine.

Soft-Tissue Sarcoma following Traumatic Injury: Case Report and Review of the Literature

Soft-tissue sarcomas (STSs) are a heterogeneous group of tumors, which accounts for 1–2% of adult cancers worldwide. Despite quite a few reports on traumatic events followed by STS formation, the link between the two events remains a point of controversy. In this paper, we present the case of a young patient who had a rhabdomyosarcoma in the lower extremity, which had developed in the same location where the patient was wounded by a gunshot 9 years earlier. X-ray and CT scans clearly showed metal fragments in the area of sarcoma formation. The patient underwent neoadjuvant chemotherapy treatment, to which the tumor was, unfortunately, unresponsive. Therefore, the patient was referred to below-knee amputation of the injured leg. There are several possible etiological factors for sarcoma development in this patient, including tissue damage and inflammation, as well as the presence of metal fragments in the tissue and the limb’s exposure to radiation during multiple imaging tests. Here, we will discuss the potential influence wielded by the injury itself, as well as its complications and its medical management on the formation of the sarcoma, in light of the current literature.

The Role of the Component Metals in the Toxicity of Military-Grade Tungsten Alloy

Tungsten-based composites have been recommended as a suitable replacement for depleted uranium. Unfortunately, one of these mixtures composed of tungsten (W), nickel (Ni) and cobalt (Co) induced rhabdomyosarcomas when implanted into the leg muscle of laboratory rats and mice to simulate a shrapnel wound. The question arose as to whether the neoplastic effect of the mixture could be solely attributed to one or more of the metal components. To investigate this possibility, pellets with one or two of the component metals replaced with an identical amount of the biologically-inert metal tantalum (Ta) were manufactured and implanted into the quadriceps of B6C3F₁ mice. The mice were followed for two years to assess potential adverse health effects. Implantation with WTa, CoTa or WNiTa resulted in decreased survival, but not to the level reported for WNiCo. Sarcomas in the implanted muscle were found in 20% of the CoTa-implanted mice and 5% of the WTa- and WCoTa-implanted rats and mice, far below the 80% reported for WNiCo-implanted mice. The data obtained from this study suggested that no single metal is solely responsible for the neoplastic effects of WNiCo and that a synergistic effect of the three metals in tumor development was likely.

Toxic and transcriptional responses of PC12 cells to soluble tungsten alloy surrogates

There is increasing evidence that metals have a role in the etiology of diverse neurological diseases. This study used PC12 cells as an in vitro model to examine the toxicity of tungsten alloys that have important military applications. Initially, the relative concentrations of tungsten (W), nickel (Ni), and cobalt (Co) mobilized from pellets of a weapons-grade tungsten alloy incubated in physiologically relevant solutions were determined. Dosing solutions of soluble metal salts that were equivalent in ratio to those mobilized from these alloy pellets were used to treat nerve growth factor (NGF) differentiated PC12 cells. Treatments consisted of single (W, Ni or Co), paired (W/Ni, W/Co or Ni/Co) or complete (W/Ni/Co) metal exposures for 24 h followed by measurement of cytotoxicity, viability, and microarray analysis to examine their impact on survival and viability, global gene expression, and biological processes. Gene expression changed dramatically with addition of NGF. Addition of Ni or Co either singly or in combination further impacted gene expression. An observed additive effect of Ni and Co on gene expression was unaffected by the addition of W. The work showed that tungsten, as found in this tungsten alloy, had minimal relative toxicity as compared to the other alloy components when used either alone or in combination.

An update to the toxicological profile for water-soluble and sparingly soluble tungsten substances

Tungsten is a relatively rare metal with numerous applications, most notably in machine tools, catalysts, and superalloys. In 2003, tungsten was nominated for study under the National Toxicology Program, and in 2011, it was nominated for human health assessment under the US Environmental Protection Agency's (EPA) Integrated Risk Information System. In 2005, the Agency for Toxic Substances and Disease Registry (ATSDR) issued a toxicological profile for tungsten, identifying several data gaps in the hazard assessment of tungsten. By filling the data gaps identified by the ATSDR, this review serves as an update to the toxicological profile for tungsten and tungsten substances. A PubMed literature search was conducted to identify reports published during the period 2004-2014, in order to gather relevant information related to tungsten toxicity. Additional information was also obtained directly from unpublished studies from within the tungsten industry. A systematic approach to evaluate the quality of data was conducted according to published criteria. This comprehensive review has gathered new toxicokinetic information and summarizes the details of acute and repeated-exposure studies that include reproductive, developmental, neurotoxicological, and immunotoxicological endpoints. Such new evidence involves several relevant studies that must be considered when regulators estimate and propose a tungsten reference or concentration dose.

Molecular basis of carcinogenicity of tungsten alloy particles

The tungsten alloy of 91% tungsten, 6% nickel and 3% cobalt (WNC 91-6-3) induces rhabdomyosarcoma when implanted into a rat thigh muscle. To investigate whether this effect is species-specific human HSkMc primary muscle cells were exposed to WNC 91-6-3 particles and responses were compared with those from a rat skeletal muscle cell line (L6-C11). Toxicity was assessed by the adenylate kinase assay and microscopy, DNA damage by the Comet assay. Caspase 3 enzyme activity was measured and oligonucleotide microarrays were used for transcriptional profiling. WNC 91-6-3 particles caused toxicity in cells adjacent to the particles and also increased DNA strand breaks. Inhibition of caspase 3 by WNC 91-6-3 occurred in rat but not in human cells. In both rat and human cells, the transcriptional response to WNC 91-6-3 showed repression of transcripts encoding muscle-specific proteins with induction of glycolysis, hypoxia, stress responses and transcripts associated with DNA damage and cell death. In human cells, genes encoding metallothioneins were also induced, together with genes related to angiogenesis, dysregulation of apoptosis and proliferation consistent with pre-neoplastic changes. An alloy containing iron, WNF 97-2-1, which is non-carcinogenic in vivo in rats, did not show these transcriptional changes in vitro in either species while the corresponding cobalt-containing alloy, WNC 97-2-1 elicited similar responses to WNC 91-6-3. Tungsten alloys containing both nickel and cobalt therefore have the potential to be carcinogenic in man and in vitro assays coupled with transcriptomics can be used to identify alloys, which may lead to tumour formation, by dysregulation of biochemical processes.

Induction of Rhabdomyosarcoma by Embedded Military-Grade Tungsten/Nickel/Cobalt Not by Tungsten/Nickel/Iron in the B6C3F1 Mouse

Continued improvements in the ballistic properties of military munitions have led to metal formulations for which little are known about the long-term health effects. Previously we have shown that a military-grade tungsten alloy comprised of tungsten, nickel, and cobalt, when embedded into the leg muscle of F344 rats to simulate a fragment wound, induces highly aggressive metastatic rhabdomyosarcomas. An important follow-up when assessing a compound’s carcinogenic potential is to test it in a second rodent species. In this study, we assessed the health effects of embedded fragments of 2 military-grade tungsten alloys, tungsten/nickel/cobalt and tungsten/nickel/iron, in the B6C3F1 mouse. Implantation of tungsten/nickel/cobalt pellets into the quadriceps muscle resulted in the formation of a rhabdomyosarcoma around the pellet. Conversely, implantation of tungsten/nickel/iron did not result in tumor formation. Unlike what was seen in the rat model, the tumors induced by the tungsten/nickel/cobalt did not exhibit aggressive growth patterns and did not metastasize.

Genotoxic changes to rodent cells exposed in vitro to tungsten, nickel, cobalt and iron

Tungsten-based materials have been proposed as replacements for depleted uranium in armor-penetrating munitions and for lead in small-arms ammunition. A recent report demonstrated that a military-grade composition of tungsten, nickel, and cobalt induced a highly-aggressive, metastatic rhabdomyosarcoma when implanted into the leg muscle of laboratory rats to simulate a shrapnel wound. The early genetic changes occurring in response to embedded metal fragments are not known. In this study, we utilized two cultured rodent myoblast cell lines, exposed to soluble tungsten alloys and the individual metals comprising the alloys, to study the genotoxic effects. By profiling cell transcriptomes using microarray, we found slight, yet distinct and unique, gene expression changes in rat myoblast cells after 24 h metal exposure, and several genes were identified that correlate with impending adverse consequences of ongoing exposure to weapons-grade tungsten alloy. These changes were not as apparent in the mouse myoblast cell line. This indicates a potential species difference in the cellular response to tungsten alloy, a hypothesis supported by current findings with in vivo model systems. Studies examining genotoxic-associated gene expression changes in cells from longer exposure times are warranted.

Embedded fragments from U.S. military personnel--chemical analysis and potential health implications

BACKGROUND

The majority of modern war wounds are characterized by high-energy blast injuries containing a wide range of retained foreign materials of a metallic or composite nature. Health effects of retained fragments range from local or systemic toxicities to foreign body reactions or malignancies, and dependent on the chemical composition and corrosiveness of the fragments in vivo. Information obtained by chemical analysis of excised fragments can be used to guide clinical decisions regarding the need for fragment removal, to develop therapeutic interventions, and to better anticipate future medical problems from retained fragment related injuries. In response to this need, a new U.S Department of Defense (DoD) directive has been issued requiring characterization of all removed fragments to provide a database of fragment types occurring in combat injuries.

OBJECTIVES

The objective of this study is to determine the chemical composition of retained embedded fragments removed from injured military personnel, and to relate results to histological findings in tissue adjacent to fragment material.

METHODS

We describe an approach for the chemical analysis and characterization of retained fragments and adjacent tissues, and include case examples describing fragments containing depleted uranium (DU), tungsten (W), lead (Pb), and non-metal foreign bodies composed of natural and composite materials. Fragments obtained from four patients with penetrating blast wounds to the limbs were studied employing a wide range of chemical and microscopy techniques. Available adjacent tissues from three of the cases were histologically, microscopically, and chemically examined. The physical and compositional properties of the removed foreign material surfaces were examined with energy dispersive x-ray fluorescence spectrometry (EDXRF), scanning electron microscopy (SEM), laser ablation inductively-coupled plasma mass-spectrometry (LA-ICP-MS), and confocal laser Raman microspectroscopy (CLRM). Quantitative chemical analysis of both fragments and available tissues was conducted employing ICP-MS.

RESULTS

Over 800 fragments have been characterized and included as part of the Joint Pathology Center Embedded Fragment Registry. Most fragments were obtained from penetrating wounds sustained to the extremities, particularly soft tissue injuries. The majority of the fragments were primarily composed of a single metal such as iron, copper, or aluminum with traces of antimony, titanium, uranium, and lead. One case demonstrated tungsten in both the fragment and the connected tissue, together with lead. Capsular tissue and fragments from a case from the 1991 Kuwait conflict showed evidence of uranium that was further characterized by uranium isotopic ratios analysis to contain depleted uranium.

CONCLUSIONS

The present study provides a systematic approach for obtaining a full chemical characterization of retained embedded fragments. Given the vast number of combat casualties with retained fragments, it is expected that fragment analysis will have significant implications for the optimal short and long-term care of wounded service members.

Exposure to cobalt causes transcriptomic and proteomic changes in two rat liver derived cell lines

Cobalt is a transition group metal present in trace amounts in the human diet, but in larger doses it can be acutely toxic or cause adverse health effects in chronic exposures. Its use in many industrial processes and alloys worldwide presents opportunities for occupational exposures, including military personnel. While the toxic effects of cobalt have been widely studied, the exact mechanisms of toxicity remain unclear. In order to further elucidate these mechanisms and identify potential biomarkers of exposure or effect, we exposed two rat liver-derived cell lines, H4-II-E-C3 and MH1C1, to two concentrations of cobalt chloride. We examined changes in gene expression using DNA microarrays in both cell lines and examined changes in cytoplasmic protein abundance in MH1C1 cells using mass spectrometry. We chose to closely examine differentially expressed genes and proteins changing in abundance in both cell lines in order to remove cell line specific effects. We identified enriched pathways, networks, and biological functions using commercial bioinformatic tools and manual annotation. Many of the genes, proteins, and pathways modulated by exposure to cobalt appear to be due to an induction of a hypoxic-like response and oxidative stress. Genes that may be differentially expressed due to a hypoxic-like response are involved in Hif-1α signaling, glycolysis, gluconeogenesis, and other energy metabolism related processes. Gene expression changes linked to oxidative stress are also known to be involved in the NRF2-mediated response, protein degradation, and glutathione production. Using microarray and mass spectrometry analysis, we were able to identify modulated genes and proteins, further elucidate the mechanisms of toxicity of cobalt, and identify biomarkers of exposure and effect in vitro, thus providing targets for focused in vivo studies.