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Exposure to heavy metals may have toxic effects on several human organs causing morbidity and mortality. Metals may trigger or exacerbate autoimmunity in humans. Inbred mouse strains with certain H-2 haplotypes are susceptible to xenobiotic-induced autoimmunity; and their immune response to metals such as mercury, gold, and silver have been explored. Serum antinuclear antibodies (ANA), polyclonal B-cell activation, hypergammaglobulinemia and tissue immune complex deposition are the main features of metal-induced autoimmunity in inbred mice. However, inbred mouse strains do not represent the genetic heterogeneity in humans. In this study, outbred Swiss Webster (SW) mice exposed to gold or mercury salts showed immune and autoimmune responses. Intramuscular injection of 22.5 mg/kg.bw aurothiomalate (AuTM) induced IgG ANA in SW mice starting after 5 weeks that persisted until week 15 although with a lower intensity. This was accompanied by elevated serum levels of total IgG antibodies against chromatin and total histones. Exposure to gold led to development of serum IgG autoantibodies corresponding to H1 and H2A histones, and dsDNA. Both gold and mercury induced polyclonal B-cell activation. Eight mg/L mercuric chloride (HgCl 2 ) in drinking water, caused IgG antinucleolar antibodies (ANoA) after 5 weeks in SW mice accompanied by immune complex deposition in kidneys and spleen. Serum IgG antibodies corresponding to anti-fibrillarin, and anti-PM/Scl-100 antibodies, were observed in mercury-exposed SW mice. Gold and mercury trigger systemic autoimmune response in genetically heterogeneous outbred SW mice and suggest them as an appropriate model to study xenobiotic-induced autoimmunity., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Gold(I) complexes are an important tool in the arsenal of established approaches for treating rheumatoid arthritis (RA), while some recent studies have suggested that gold nanoparticles (Au NPs) may also be therapeutically efficacious. These observations prompted the current biological studies involving gold(I) anti-RA agents and Au NPs, which are aimed towards improving our knowledge of how they work. The cytotoxicity of auranofin, aurothiomalate, aurothiosulfate and Au NPs towards RAW264.7 macrophages was evaluated using the MTT assay, with the former compound proving to be the most toxic. The extent of cellular uptake of the various gold agents was determined using graphite furnace atomic absorption spectrometry, while their distribution within macrophages was examined using microprobe synchrotron radiation X-ray fluorescence spectroscopy. The latter technique showed accumulation of gold in discrete regions of the cell, and co-localisation with sulfur in the case of cells treated with aurothiomalate or auranofin. Electrospray ionization mass spectrometry was used to characterize thioredoxin reductase (TrxR) in which the penultimate selenocysteine residue was replaced by cysteine. Mass spectra of solutions of TrxR and aurothiomalate, aurothiosulfate or auranofin showed complexes containing bare gold atoms bound to the protein, or protein adducts containing gold atoms retaining some of their initial ligands. These results support TrxR being an important target of gold(I) drugs used to treat RA, while the finding that Au NPs are incorporated into macrophages, but elicit little toxicity, indicates further exploration of their potential for treatment of RA is warranted., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Protein kinase C iota (PKCι) is overexpressed in non-small-cell lung cancer, ovarian, and pancreatic cancers, where it plays a critical role in oncogenesis. The gold compound aurothiomalate (ATM) has been shown to inhibit PKCι signaling and exerts potent antitumor activity in preclinical models. We sought to determine the maximum tolerated dose (MTD) of ATM. We conducted a phase I dose escalation trial of ATM in patients with non-small-cell lung cancer, ovarian or pancreatic cancer. Patients received ATM intramuscularly weekly for three cycles (cycle duration 4 weeks) at 25, 50, or 75 mg in a 3+3 design. The dose was not escalated for individual patients. Blood samples were analyzed for elemental gold levels. Patients were evaluated every 4 weeks for toxicity and every 8 weeks for response. Fifteen patients were enrolled in this study. Six patients were treated at 25 mg, seven at 50 mg, and two at 75 mg. There was one dose-limiting toxicity at 25 mg (hypokalemia), one at 50 mg (urinary tract infection), and none at 75 mg. There were three grade 3 hematologic toxicities. The recommended MTD of ATM is 50 mg. Patients received treatment for a median of two cycles (range 1-3). There appeared to be a dose-related accumulation of steady-state plasma concentrations of gold consistent with linear pharmacokinetics. In summary, this phase I study was successful in identifying ATM 50 mg intramuscularly weekly as the MTD. Future clinical investigations targeting PKCι are currently in progress.

This article discusses the bizarre and contrary effects of thiocyanate, the major detoxication product of hydrogen cyanide inhaled from tobacco smoke or liberated from cyanogenic foods, e.g. cassava. Thiocyanate both (1) promotes inflammatory disease in rats and (2) facilitates the anti-inflammatory action of historic metal therapies based on gold (Au) or silver (Ag) in three models of chronic polyarthritis in rats. Low doses of nanoparticulate metallic silver (NMS) preparations, i.e. zerovalent silver (Ag°) administered orally, suppressed the mycobacterial ('adjuvant')-induced arthritis (MIA) in rats. Similar doses of cationic silver, Ag(I), administered orally as silver oxide or soluble silver salts were inactive. By contrast, NMS only inhibited the development of the collagen-induced arthritis (CIA) and pristane-induced arthritis (PIA) in rats when thiocyanate was also co-administered in drinking water. These (a) arthritis-selective and (b) thiocyanate-inducible effects of Ag° were also observed in some previous, and now extended, studies with the classic anti-arthritic drug, sodium aurothiomalate (ATM, Myocrisin(®)) and its silver analogue (STM), administered subcutaneously to rats developing the same three forms of polyarthritis. In the absence of either Ag° or ATM, thiocyanate considerably increased the severity of the MIA, CIA and PIA, i.e. acting as a pro-pathogen. Hitherto, thiocyanate was considered relatively harmless. This may not be true in rats/people with immuno-inflammatory stress and concomitant leukocyte activation. Collectively, these findings show how the drug action of a xenobiotic might be determined by the nature (and severity) of the experimental inflammation, as an example of conditional pharmacology. They also suggest that an incipient toxicity, even of normobiotics such as thiocyanate, might likewise be modulated beneficially by well-chosen xenobiotics (drugs, nutritional supplements, etc.), i.e. conditional toxicology (Powanda 1995). Thus, both the disease and the environment may determine (1) the therapeutic action and/or (2) adverse effect(s) of xenobiotics--and even some normobiotics.

The suicidal death of erythrocytes, eryptosis, is characterized by cell shrinkage and cell membrane scrambling leading to phosphatidylserine exposure at the erythrocyte surface. Erythrocyte cell membrane scrambling is stimulated by increase of cytosolic Ca2+ concentration ([Ca2+](i)) and formation of ceramide. Phosphatidylserine (PS) exposing cells are rapidly cleared from circulating blood. Ca2+ entry and/or ceramide formation and thus eryptosis are triggered by lead, mercury, aluminium, and copper ions. The present study explored whether eryptosis could be similarly triggered by exposure to gold. To this end, erythrocytes from healthy volunteers were exposed to AuCl and phosphatidylserine exposure (annexin V binding), cell volume (forward scatter), [Ca2+](i) (Fluo3-dependent fluorescence), and ceramide formation (anti-ceramide-FITC fluorescence) were determined by flow cytometry. Exposure of erythrocytes to low concentrations of AuCl (> or =0.75microg/ml) increased [Ca2+](i) but did not affect ceramide formation. AuCl at concentrations > or =0.5microg/ml significantly increased the number of PS exposing erythrocytes and decreased forward scatter at low concentrations of AuCl pointing to cell shrinkage. Aurothiomalate (> or =1microg/ml), a gold containing drug effective against rheumatoid arthritis, similarly triggered PS exposure of erythrocytes. The present observations disclose a novel action of gold, which may well contribute to side effects during treatment with gold preparations.

Unlabelled: Thioredoxin reductase (TrxR) reduces thioredoxin (Trx), thereby contributing to cellular redox balance, facilitating the synthesis of deoxy-ribose sugars for DNA synthesis, and regulating redox-sensitive gene expression. Auranofin is a gold compound that potently inhibits TrxR. This inhibition is one suspected mechanism of auranofin's therapeutic benefit in the treatment of rheumatoid arthritis. The use of other gold compounds to treat cancer or inflammatory disease may rely on their ability to inhibit TrxR. In the current study, we tested the hypothesis that a variety of gold compounds may inhibit TrxR., Methods: We exposed rat-TrxR1 to auranofin, gold sodium thiomalate, sodium aurothiosulfate, triphenyl phosphine gold chloride, or gold acetate, and measured TrxR activity ex vivo. We then compared TrxR1 inhibitory levels of gold compounds to those that inhibited mitochondrial activity of THP1 monocytes and OSC2 epithelial cells, estimated by succinate dehydrogenase activity., Results: All gold compounds inhibited TrxR1 at concentrations ranging from 5 to 4000 nM (50% inhibitory concentration). The oxidation state of gold did not correlate with inhibitory potency, but ligand configuration was important. Au(I)-phosphine compounds (triphenyl phosphine gold chloride and auranofin) were the most potent inhibitors of TrxR. All TrxR1 inhibitory concentrations were sublethal to mitochondrial activity in both THP1 and OSC2 cells., Conclusions: Diverse types of gold compounds may be effective inhibitors of TrxR1 at concentrations that do not suppress cellular mitochondrial function. Inhibition may be optimized to some degree by altering the ligand configuration of the compounds. These results support future study of a variety of Au compounds for therapeutic development as inhibitors of TrxR1.

Unlabelled: The toxicity of anti-rheumatic gold compounds has limited their use and development, yet both the toxicological and therapeutic actions of these compounds remain unclear. In the current study, we tested the hypothesis that intracellular reactive oxygen species (ROS) induced by Au(I) or Au(III) compounds mediate their ability to suppress mitochondrial activity., Methods: Human THP1 monocytes were exposed to HAuCl(4) x 3H(2)O (Au(III)), or the anti-rheumatic compounds auranofin (AF) or gold sodium thiomalate (GSTM) for 6-72 h, after which mitochondrial activity (succinate dehydrogenase) was measured. To assess the role of cellular redox status as a mediator of mitochondrial suppression, monocytes were pre-treated with a pro-oxidant (t-butyl hydroquinone, t-BHQ) or antioxidant (N-acetyl cysteine, NAC ). ROS levels were measured 0-24h post-gold addition to determine their role as mediators of mitochondrial activity suppression., Results: AF was the most potent inhibitor of mitochondrial activity, followed by Au(III) and GSTM. Only Au(III) induced intracellular ROS; no ROS formation was observed in response to AF or GSTM exposure. Although anti- and pro-oxidants had some effects on mitochondrial suppression of Au compounds, collectively the data do not support redox effects or ROS formation as major mediators of Au-compound mitochondrial suppression., Conclusions: Our results do not indicate that ROS and redox effects play major roles in mediating the cytotoxicity of AF, GSTM or Au(III).

The objective of this study was to quantify the ability of sublethal concentrations of several gold compounds to differentially modulate the monocytic secretion of key cytokines that are important in the etiology of rheumatic diseases. Human THP1 monocytic cells were exposed to the anti-rheumatic drugs auranofin (AF), gold sodium thiomalate (GSTM) or HAuCl4 (Au(III)) for 24-72 h. Succinate dehydrogenase (SDH) activity of the monocytes was used to determine sublethal concentrations. Monocytes were then exposed to sublethal concentrations of gold compounds for 72 h, and the activator lipopolysaccharide (LPS) was added (or not) to cultures for the last 6h. The secretion of IL6, IL8, IL10, and TNFalpha were measured in cell supernatants using ELISA. Cytokine secretion was compared among concentrations and gold compounds. SDH experiments established a sublethal concentration range of 0-75 microM for GSTM and Au(III) and 0-0.5 microM for AF. In cytokine experiments, none of the compounds alone activated secretion of any of the cytokines, but all differentially (50-440%, p<0.05) increased LPS-induced secretion of IL6 and IL8 over TNFalpha and IL10. In conclusion, sublethal concentrations of AF, GSTM, and Au(III) all may differentially modulate activation of monocytic cells, and this differential modulation may be important in the mechanisms of action of these compounds.

To elucidate the renal injury induced by gold treatment, we administered various doses of gold sodium thiomalate (GST) to Wistar rats and investigated alterations in the urinary enzyme activity, gamma-glutamyl transpeptidase (gamma GTP) and N-acetyl-beta-glucosaminidase (NAG) activity, and histochemical change of enzymes, gamma GTP, alkaline phosphatase (ALP) and acid phosphatase (ACP) activity in the renal tissue. The single administration of a large dose of gold salts induced acute tubular necrosis and enzyme leakage was detected histochemically without damage to the glomerulus. After chronic administration of small doses of gold salts, the urinary gamma GTP activities gradually increased, but urinary NAG activities did not. These findings suggested that the change in urinary enzyme activities, which leaked from inside of brushborder or lysosome, indicated the degree or localization of tubular damage, because renal tubules were selectively injured by gold salts.

Two gold compounds, gold sodium thiomalate (AuTM) and auranofin, are presently in clinical use in therapy of rheumatoid arthritis. In these studies, AuTM administered to Sprague-Dawley rats and three strains of mice, Swiss-Webster, C3H/HeJ, and DBA/2J, were studied with regard to its effect on liver and renal monooxygenases, metallothionein contents, and serum levels of alanine aminotransferase and urea nitrogen. These effects of AuTM were compared to those of cadmium, since the latter metal has exhibited tissue and species differences in the induction of metallothionein. Benzo(a)pyrene hydroxylase and benzphetamine N-demethylase activities were not altered by AuTM in livers of rats and the three strains of mice. Benzo(a)pyrene hydroxylase activity was significantly decreased in rat kidney, whereas this enzyme activity was not affected in the kidneys of mice. In rats, AuTM caused a sevenfold induction in liver metallothionein, while in mice, liver metallothionein was induced twofold in Swiss-Webster mice and about fivefold in the inbred strains. AuTM caused minimal changes in renal metallothionein contents in the three strains of mice studied. Serum alanine amino-transferase, an indicator of hepatotoxicity, was not altered by AuTM in rats and mice studied. Blood urea nitrogen, an indicator of kidney dysfunction, was increased threefold in rats, but not in AuTM-treated mice. These data demonstrate that AuTM, a nephrotoxic agent in rats and humans, showed no nephrotoxic effects in the mouse strains studied here.

The effects of 2,3-dimercaptopropane sulphonate (DMPS) and N-(2-mercapto-2-methylpropanoyl)-L-cysteine (bucillamine) against the renal damage induced by gold sodium thiomalate (AuTM) in adjuvant-arthritic rats were studied. Arthritic rats induced by adjuvant using Mycobacterium butyricum were injected intraperitoneally with a chelating agent (0.6 mmol/kg) immediately after intramuscular injection of AuTM (0.066 mmol/kg) every other day for 21 days. Treatment with DMPS and bucillamine prevented increases in the urinary excretion of protein, aspartate aminotransferase, and glucose and blood urea nitrogen level after AuTM injection. AuTM prevented the increase in both adjuvant-injected and uninjected hind-feet volumes. The prevention of these inflamed lesions by AuTM was not affected by DMPS and bucillamine. These chelating agents decreased the gold concentration in the kidney and liver after AuTM administration, but did not affect the hepatic and renal concentrations of copper, zinc, iron, and calcium except the renal copper level after AuTM. These findings suggest that DMPS and bucillamine are very useful antidotes for gold toxicity.

The oxidizing capacity of phagocytic cells is suspected to play a major role in the generation of immunogenic drug metabolites, in particular those that cause extrahepatic immunopathological lesions. In the case of the antirheumatic drug gold(I) disodium thiomalate (Na2Au(I)TM), oxidation of the Au(I) ion to Au(III) appears to be responsible for the adverse immune reactions which may develop during gold therapy. Here, we show that the reactive metabolite Au(III) may be generated by mononuclear phagocytes (M phi) exposed to Au(I). The generation of Au(III) was analyzed by means of the adoptive transfer popliteal lymph node assay (PLNA) in mice, using T lymphocytes previously sensitized to Au(III) as a detection probe. Donors of the Au(III)-primed T cells were either directly sensitized to Au(III) by injection of tetrachloroauric acid (HAu(III)Cl4), or indirectly via chronic treatment with Na2Au(I)TM. As donors of peritoneal cells (PC), we used mice which had received weekly i.m. injections of Na2Au(I)TM for 12 weeks and contained increased numbers of activated B cells. The PC of these mice were found to elicit a significant secondary response when used as antigenic material for the restimulation of Au(III)-primed T cells. The immunogenicity of PC obtained from Na2Au(I)TM-treated mice paralleled the total gold content of these cells. Noteworthily, M phi exposed to Au(I) in vitro also proved capable of eliciting a specific secondary response of Au(III)-primed T cells. Hence, M phi exposed to Au(I) generate the reactive intermediate Au(III) which, apparently via oxidation of self proteins, sensitizes T cells. As M phi are constituents of many different organs and, moreover, communicate with T cells, their capacity to generate Au(III) may account for the various extrahepatic adverse immune reactions induced by Au(I) drugs.

Following weekly i.m. injections of gold(I) disodium thiomalate (GST), mice of strains A.SW and C57BL/6 develop adverse immune reactions, whereas DBA/2 mice do not. We have studied the pharmaco-toxicokinetics of gold in these strains under chronic GST treatment. Our results indicate that the susceptible strains A.SW and C57BL/6 accumulate significantly higher gold concentrations in the liver and spleen compared to the resistant strain DBA/2. In the kidney of DBA/2 mice, gold concentrations persisted at a plateau level, whereas in A.SW and, particularly, C57BL/6 mice early peaks of gold concentrations were followed by a transient decrease, suggestive of tubular toxicity. Whereas splenic T and B cells failed to contain measurable gold concentrations in all three strains, splenic and peritoneal macrophages contained relatively high levels, more so in the susceptible strain C57BL/6 than in the resistant DBA/2 strain. This finding is consistent with the concept that macrophages play an important role in both the adverse and the beneficial effects of gold drugs.

The effects of various chelating agents, such as (2S)-1-(3-mercaptopropionyl)-L-proline (captopril), N-(2-mercaptopropionyl)-glycine (tiopronin), L-cysteine (L-Cys), D-cysteine (D-Cys), N-acetyl-L-cysteine (L-NAC), N-benzyl-D-glucamine dithiocarbamate (BGD), and ethylenediaminetetraacetate (EDTA), on the distribution, excretion, and renal toxicity of gold sodium thiomalate (AuTM) in rats were investigated. Rats were intraperitoneally injected with the chelating agents (1.2 mmol/kg each) immediately after intravenous injection of AuTM (0.026 mmol/kg). Treatment with captopril or tiopronin significantly prevented increases in the urinary excretion of protein, aspartate aminotransferase (AST), and glucose and the blood urea nitrogen (BUN) level after AuTM injection. L-NAC and D-Cys significantly prevented increases in the urinary excretion of protein, AST, and glucose after AuTM injection, but did not reduce to control levels. Treatment with BGD, EDTA, or L-Cys did not prevent AuTM-induced increases in the urinary excretion of protein, AST, and glucose and BUN level. Tiopronin significantly increased the urinary excretion of gold. Captopril slightly promoted both the urinary and fecal excretion of gold, resulting in the significant increase in the total excretion of the metal. Tiopronin and captopril significantly decreased the gold concentration in the kidney and liver. L-Cys, D-Cys, L-NAC, BGD, and EDTA had no significant effect on the excretion or distribution of gold at 7 days after AuTM injection. These results indicate that tiopronin and captopril can ameliorate the renal toxicity induced by AuTM. In addition, the comparative effects of 2,3-dimercaptopropane sulfonate (DMPS), N-(2-mercapto-2-methylpropanoyl)-L-cysteine (bucillamine), captopril, and tiopronin at various dose levels (1.2, 0.4 or 0.2 mmol/kg) on the distribution and renal toxicity of gold were studied. DMPS was effective in removing gold from the kidney and in protecting against the renal toxicity after AuTM injection at the even lower dose level (0.2 mmol/kg). Bucillamine and tiopronin protected against the renal toxicity of gold at dose levels of 0.4 and 1.2 mmol/kg and captopril ameliorated the gold toxicity only at higher dose level (1.2 mmol/kg).

The effects of the repeated administration of D-penicillamine, 2,3-dimercaptosuccinic acid, 2,3-dimercaptopropane sulphonate, and N-(2-mercapto-2-methylpropanoyl)-L-cysteine 24 h after gold sodium thiomalate (AuTM) injection on the distribution, excretion, and renal toxicity of gold in rats were investigated. Three i.p. injections of these chelating agents (1.2 mmol/kg) at 1, 3, and 5 days after AuTM injection (0.026 mmol/kg) removed gold from kidney and liver through urinary and fecal excretion, and protected against the renal damage induced by AuTM. These findings indicate that these compounds are useful antidotes for gold toxicity.

The protective effects of various chelating agents such as D-penicillamine (D-PEN), 2,3-dimercaptosuccinic acid (DMSA), 2,3-dimercaptopropane sulphonate (DMPS), and N-(2-mercapto-2-methylpropanoyl)-L-cysteine (bucillamine), on the renal damage induced by gold sodium thiomalate (AuTM) in rats were studied. Rats were injected i.v. with AuTM at doses of 0.026, 0.066, 0.132, and 0.198 mmol/kg. Urinary excretion of protein, aspartate aminotransferase (AST), and glucose in rats injected with AuTM significantly increased compared to the control levels within 1 day after the injection and thereafter decreased nearly to the control levels at 3 or 7 days. Gold was excreted rapidly during the first day after AuTM injection and excreted gradually thereafter. The concentrations of gold in the kidney and liver at 1 or 7 days after AuTM administration were approximately dose dependent. Treatment with D-PEN, DMSA, DMPS, and bucillamine (1.2 mmol/kg) significantly prevented increases in the urinary excretion of protein, AST, and glucose and the BUN level after AuTM (0.026 mmol/kg) injection. The injection of the chelating agents after AuTM administration showed that D-PEN, DMSA, and DMPS enhanced mainly the urinary excretion of gold and that bucillamine enhanced mainly the fecal excretion of the metal. These chelating agents significantly decreased the gold concentrations in the kidney and liver. The findings suggest that the chelating agents tested can ameliorate the renal damage induced by AuTM.

Gold compounds are used clinically in rheumatoid arthritis therapy. Acute renal toxicity is observed in some patients receiving chrysotherapy. The present study addresses morphofunctional and biochemical changes in rat kidneys during the first 8 days following a single ip injection of gold sodium thiomalate (AuTM), one of the gold compounds presently in clinical use. Compared to controls, AuTM pretreatment resulted in increased urine output and elevated serum creatinine and urea nitrogen concentrations. Also, by Day 8, treated rats had decreased body weights and increased kidney weights. Postmortem examination on Day 1 showed pale and mottled kidneys and diffusely pale inner cortex. Microscopically, there was severe coagulative necrosis of the proximal tubular epithelium. Epithelial regeneration was prominent by Day 4 and was nearly complete by Day 8. The regenerating epithelium was hyperplastic with basophilic cytoplasm and pleomorphic nuclei. Alterations in renal heme biosynthesis and drug metabolism paralleled the morphologic changes. The activity of delta-aminolevulinic acid dehydratase and benzo[a]pyrene hydroxylase were inhibited on Days 1, 2, and 4 following AuTM administration. Decreases in monooxygenase activity were accompanied by decreases in renal cytochrome P-450 levels. In contrast, renal microsomal heme oxygenase activity was elevated 9.5-fold on Day 1 and 2.5-fold on Day 2. By Day 8, all renal enzymatic activities assayed for were similar to those obtained with untreated rats.

We reviewed the records of 24 patients with rheumatoid arthritis who underwent 25 retreatments with gold salt injections given at a frequency greater than the usual monthly maintenance. Subject to the limitations of retrospective review, it was judged that every patient had improved on retreatment (5 fair, 19 good, 1 excellent), and there was only 1 instance of toxicity necessitating cessation of chrysotherapy. Repeat courses of gold salt injections of increased frequency appears to be a safe and effective therapeutic option for patients with rheumatoid arthritis who relapse after initial successful treatment.

Heavy metal nephropathy is a pathologic entity of the renal tubular epithelium of rats, evoked by lead, gold, and other heavy metals. It is characterized acutely by coagulative necrosis, subacutely by cortical fibrosis, and chronically by cytomegaly and karyomegaly. Finally, adenomas develop, some of which become malignant.

The association between sulphoxidation capacity and sodium aurothiomalate toxicity was investigated in 65 patients undergoing treatment for rheumatoid arthritis. Of those showing side-effects, 30/37 (81%) were also poor sulphoxidizers compared with only 9/28 (32%) in the group not displaying adverse reactions. A patient with poor sulphoxidation had a nine-fold greater risk of developing toxicity. The prior measurement of sulphoxidation capacity may help to identify those patients most susceptible to the deleterious effects of this drug.

Inhibition of the activity of delta-aminolevulinic acid dehydratase by heavy metals such as Cu, Cd and Au has been thought to be related to the inhibition of heme bio-synthesis in the bone marrow. This study investigates the interaction between lead and gold on porphyrin metabolism. Gold thiomalate (Au-T) was injected subcutaneously 10 times into the backs of rabbits in doses of 1, 10 and 100 mg per capita for 30 days. The latter two groups of animals showed mild anemia, but they showed neither reticulocytosis nor increase of free erythrocyte protoporphyrin (FEP). In rabbits administered lead only or lead plus gold thiomalate, however, reticulocytosis and an increase in FEP levels were observed. Therefore, the etiology of anemia may be different between rabbits administered gold thiomalate and rabbits administered lead. Rabbits injected with Au-T showed an increase in urinary coproporphyrin (CP-U) excretion. The maximum concentration of CP-U in the gold groups was about 3 times as high as that in the control group, but the increment was lower than that in the lead group. Rabbits injected with Au-T showed a higher concentration of gold in the kidneys than in other tissues. In those injected lead and Au-T together, concentration of gold in all tissues was higher than in those administered Au-T only. Proteinuria was observed in the rabbits injected Au-T. The increase in CP-U in the gold-injected rabbits was assumed to be related to the increase in gold concentration in the kidneys.

The presence of gold in the kidney of a 58-year-old woman was confirmed by use of ultrastructural and microprobe examinations. A series of animal experiments were performed in which small single doses of gold were administered systemically and intraarticularly in rabbits. Both the colloidal suspension and the soluable salt gold sodium thiomalate (Myochrysine) were used. Selective lesions occurred in the proximal convoluted tubules and the mitochondria appeared to be the target organelle. They contained gold after gold sodium thiomalate but not after colloidal gold.

In mice treated with sodium aurothiomalate (myocrisin), prior to infection with Coxsackievirus B3, 90% of the animals died by the 11th day postinfection (p.i.). A mortality of 10% was noted in mice receiving myocrisin only, and no deaths occurred in animals infected with virus alone. The highest amount of virus was recovered from the pancreas of myocrisin-treated mice on day 3 p.i. This was over 500-fold higher than the virus titer found in the pancreas of mice infected with virus only. Generally the titer of virus present in different organs was higher at every point in drug-treated animals as compared to intact mice infected with the virus. A high and persistent viremia was present in myocrisin-treated mice; in contrast a low viremia followed by virus clearance from the blood was observed in intact mice infected with the virus. The antibody response was studied in intact and myocrisin-treated mice infected with the virus. In both groups, no neutralizing antibodies were detected on days 1, 2, and 3 p.i. On day 7 after infection, the titers of antibodies were 1:16 and 1:12 in intact and myocrisin-treated mice, respectively. Administration of hyperimmune anti-Coxsackievirus B3 serum 6 hours after infection protrected in myocrisin-treated group of mice against lethal disease. The results of these studies suggest that (1) antibodies alone may not be sufficient to limit the spread and persistence of virus in natural infections and (2) in the absence of any apparent histopathological differences the increased multiplication of Coxsackievirus B3 could be the cause of death in myocrisin-treated mice.

HLA typing studies were performed on 60 consecutive patients with seropositive definite or classical rheumatoid arthritis (RA). Patients were treated with gold and were followed for a minimum of 18 months for identification of adverse reactions to gold therapy. HLA-DR3 was increased significantly in patients who developed gold induced rash, proteinuria or thrombocytopenia. On the other hand, the incidence of HLA-DR4 was lower in patients with these adverse reactions. Our results demonstrate that patients with RA carrying DR3 are at a higher risk of developing adverse reactions to gold. The most interesting finding was the low incidence of DR4 in patients who developed adverse reactions to gold, suggesting that DR4 positive patients may have some degree of protection against gold toxicity.

The ultrastructural localization of gold in the ovary of rats injected intraperitoneally with sodium aurothiomalate has been demonstrated using a histochemical technique that visualizes minute traces of gold. Gold was visualized in the oocyte within the cortical granules and in lysosomes of theca interna cells and interstitial cells.

The purpose of this study is to demonstrate renal injuries by gold sodium thiomalate (G) with ultrastructual changes and gold deposition in kidney tissue using X-ray energy dispersive analysis (XEDA). Twenty-five mg of G containing 12.1 mg of Au was injected into rats intraperitoneally. The rats were divided into 5 groups. Group 1 was sacrificed 6 hours after the injection of G, and group 2 after 24 hours, group 3 after 72 hours and group 4 after 144 hours. Group 5 consisted of the control-rats which were provided with injections of saline. Gold contents in kidneys, liver, lungs and spleen were measured using the flameless atomic absorption method. XEDA was also performed in order to confirm the gold deposition in tissue. Among the organs, only the kidney showed remarkable changes with increased weight. Group 1 already showed marked azotemia which reached to the maximum level in group 3. The amount of gold content in the organs did not change significantly in spite of a marked reduction of serum gold concentration among the 4 groups. Histological examinations revealed marked degeneration and necrosis of pars recta in proximal tubules, although no prominent abnormalities of glomeruli could be observed. Using an electron microscope, many electron dense particles in lysosome were noticed, mainly in proximal tubules. We also found these particles in lysosome of glomerular epithelial cells. Using XEDA, these electron dense particles were demonstrated to be gold, since characteristic energy of gold was found. In conclusion, the kidney was shown to be the most accumulative organ of gold. G caused acute extensive necrosis of proximal tubules. Gold was demonstrated as electron dense particles in lysosomes mainly in proximal tubules, but also partly in glomeruli. Therefore, it was confirmed that a large amount of G had a strong nephrotoxic effect in rats.

Sodium aurothiomalate was given to male Wistar rats (initial body weights: 150 g) by subcutaneous (s.c.) injection at doses of up to 7.5 mg/kg (corresponding to 4.27 mg gold/kg), twice a week, for 4-5 weeks. The concentrations of Ca, Mg, Fe, Cu and Zn were measured in serum, urine, faeces and in the liver, kidney, spleen, heart, lung, testis, bone and muscle. Kidney cytosol was separated by gel chromatography and the fractions analysed for protein, copper, zinc, iron and gold concentrations. The concentration of copper was increased 5-fold in kidney while smaller increases of zinc in kidney, copper in muscle, iron in muscle and testis and calcium in spleen were found. There was a significant reduction in the concentration of copper in serum. Kidney cytosol from gold-treated but not from control animals contained a low molecular weight protein which was associated with copper, zinc and gold. The rats developed proteinuria and microscopic changes to renal tubular cell structure were also observed. It is suggested that the gold-induced accumulation of copper may follow from an increased rate of synthesis of metallothionein and could be responsible for the renal dysfunction which develops in a proportion of rheumatoid arthritis patients who are treated with gold.

Two gold compounds, gold sodium thiomalate (AuTM) and auranofin (AF) are presently in clinical use in therapy of rheumatoid arthritis. The effects of varying doses of AF administered to rats by either the p.o. or the i.p. route on heme metabolism were determined. Twenty four hours after a single dose of AF, decreases in the sulfhydryl-containing enzymes, delta-aminolevulinic acid dehydratase and ferrochelatase activities were observed in the liver and kidneys. These decreases in heme biosynthetic enzymes were accompanied by decreases in cytochrome P-450-dependent enzymic activities and increases in microsomal heme oxygenase activity. These changes were observed with AF dosages as low as 5 mg/kg, with maximal changes occurring at a p.o. dose of about 15 mg of AF per kg and an i.p. dose of 5 to 10 mg of AF per kg. Dose-response studies with AuTM showed that maximal changes in heme metabolism occur at a lower dose of AF than of AuTM, even though AF was administered p.o. and AuTM was administered parenterally. In addition, the kidneys appeared to be more susceptible to the inhibitory effects of the two chrysotherapeutic agents than did the liver. The present studies demonstrate the p.o. drug AF affects heme metabolism in a manner similar to that reported previously with the parenterally administered AuTM.

Suramin (250 mg/kg) and sodium aurothiomalate (100 mg/kg) both induced congenital malformations in the offspring following treatment of pregnant rats at either 8.5 or 9.5 days of gestation. Conceptuses from 9.5-day pregnant rats were cultured for 48 h in homologous serum to which either suramin or sodium aurothiomalate was added for the final 6 h. The presence of suramin up to 5 mg/ml had no effect on the protein content of yolk sacs at harvesting, but at 10 mg/ml caused a significant decrease. In contrast sodium aurothiomalate increased the protein content of yolk sacs at harvesting, in a concentration-dependent manner up to 100 micrograms/ml. Neither suramin nor sodium aurothiomalate significantly affected embryo protein content. When 125I-labelled polyvinylpyrrolidone was added to the culture serum for the final 6 h of culture, radioactivity was found in the yolk sac at harvesting, but not in the embryo. When suramin (2-10 mg/ml) was present for the final 6 h of culture, the quantity of radioactivity measured in the yolk sac at harvesting was significantly decreased in a concentration-dependent manner. No radioactivity was detected in the embryos. Sodium aurothiomalate had no effect on the uptake of 125I-labelled polyvinylpyrrolidone. When rat serum whose proteins were labelled with [3H]leucine was used as culture medium, radioactivity was found in the conceptus (both yolk sac and embryo) at harvesting. Suramin (5 mg/ml), present for the final or penultimate 6 h, significantly decreased the uptake of radioactivity into conceptuses and caused a significant increase in the proportion of the captured radiolabel that was associated with the yolk sac. Sodium aurothiomalate (25 or 500 micrograms/ml) had no effect on the total uptake of radio-label but caused a significant increase in the proportion of total radioactivity captured that was associated with the yolk sac. These data indicate that suramin, by interfering with both the uptake and intralysosomal digestion of protein, and sodium aurothiomalate, by inhibiting digestion of captured protein, disturb the normal pathway of yolk sac-mediated protein utilization with a consequent diminution of the supply of amino acids to the conceptus. The effects of suramin are seen only at high concentration, those of sodium aurothiomalate at much lower concentrations. It is likely that the two drugs exert their teratogenic action by their effects on the yolk sac nutritional pathway with resultant amino acid deprivation of the conceptus at a critical stage of development.