EMP2 is a novel therapeutic target for endometrial cancer stem cells.

Previous studies have suggested that overexpression of the oncogenic protein epithelial membrane protein-2 (EMP2) correlates with endometrial carcinoma progression and ultimately poor survival from disease. To understand the role of EMP2 in the etiology of disease, gene analysis was performed to show transcripts that are reciprocally regulated by EMP2 levels. In particular, EMP2 expression correlates with and helps regulate the expression of several cancer stem cell associated markers including aldehyde dehydrogenase 1 (ALDH1). ALDH expression significantly promotes tumor initiation and correlates with the levels of EMP2 expression in both patient samples and tumor cell lines. As therapy against cancer stem cells in endometrial cancer is lacking, the ability of anti-EMP2 IgG1 therapy to reduce primary and secondary tumor formation using xenograft HEC1A models was determined. Anti-EMP2 IgG1 reduced the expression and activity of ALDH and correspondingly reduced both primary and secondary tumor load. Our results collectively suggest that anti-EMP2 therapy may be a novel method of reducing endometrial cancer stem cells.

Whey components: millennia of evolution create functionalities for mammalian nutrition: what we know and what we may be overlooking.

Nutrition is undergoing a revolution owing to the recognition that some foods contain trophic, health-promoting factors distinct from essential nutrients. In this revolution, whey is increasingly being viewed as more than a source of proteins with a particularly nutritious composition of essential amino acids. Milk evolved under continuous Darwinian selection pressure to nourish mammalian neonates. Evolutionary pressure appears to have led to the elaboration of a complex food that contains proteins, peptides, complex lipids, and oligosaccharides that act as growth factors, toxin-binding factors, antimicrobial peptides, prebiotics, and immune regulatory factors within the mammalian intestine. Importantly, these trophic macromolecules are not essential, although the health benefits that their biological activities within the intestine provide likely contributed to neonatal survival. Human and bovine milks contain many homologous components, and bovine whey may prove to be a source for molecules capable of providing biological activities to humans when consumed as food ingredients. To approach this potential, food and nutrition research must move beyond the description of food ingredients as delivering only essential nutrients and develop a mechanistic understanding of the interactions between dietary components and the metabolic and physiological properties of the intestine.

Relationship of cytoskeletal filaments to annular gap junction expression in human adrenal cortical tumor cells in culture.

In addition to the well-characterized surface gap junctions expressed at contact sites between cells, annular gap junction profiles have been localized within the cytoplasm of some cell populations. To study and characterize these annular profiles, gap junction protein type was demonstrated with Western blot and immunocytochemistry. The distribution of annular gap junctions and the relationships to cytoskeletal elements were demonstrated with immunocytochemical, transmission electron microscopic, or image analysis with confocal microscopy techniques. SW-13 adrenal cortical tumor cells expressed alpha1 gap junctions at areas of cell to cell contact. In addition, alpha1 gap junction annular profiles were seen within the cytoplasm. Actin and myosin II were found closely associated with these annular gap junctions, while no physical association between tubulin- or vimentin-containing fibers and gap junction protein could be established. Disruption of microfilaments with cytochalasin B treatment (10 microg/ml, 1 h) resulted in a decrease in the average number and an increase in the average size of annular gap junctions compared to control populations. The results are consistent with a role for cytoskeletal elements containing actin and myosin II in annular gap junction turnover.

Biological effects of dietary arachidonic acid. Introduction.

The intent of this symposium is to assemble current knowledge of the role of arachidonic acid (AA) in the diet to provide a conceptual and mechanistic framework for future research. The principal focus is on the varied biological effects of dietary AA, including opposing effects of n-3 and n-6 polyunsaturated fatty acids (PUFA); regulation of n-6 PUFA metabolism, eicosanoid synthesis and gene expression; the importance of AA in infant nutrition and the contemporary Western diet in general; and the effects of AA on tumor promotion. Through its myriad actions and remarkably ubiquitous presence in cells, AA can be argued to affect every cell of the body. Although the varied molecular events associated with the metabolism of AA have been subjects of intense investigation, the ability of AA in the diet to alter AA levels in cellular membranes is poorly described and is thus the focus of this symposium.

Embryonic development of an endoparasitoid, Microplitis croceipes (Hymenoptera: Braconidae) in cell line-conditioned media.

Embryos of the parasitoid Microplitis croceipes develop from pregerm band stage to first larval instar in cell culture medium conditioned by a cell line (IPLB-LdFB) derived from fat body from an atypical host Lymantria dispar. However, the percentage of eggs that develop normally to the first larval instar stage is significantly less than for those maintained in IPL-52B medium conditioned with host fat body tissue. Therefore, we examined the capacity of five insect cell lines to promote growth and development of pregerm band eggs in five media, IPL-52B, TC-199, TC-100, Grace's, and ExCell 400. The developmental response of M. croceipes was dependent both on the cell line and the cell culture medium used. TC-100, TC-199, and Grace's media promoted development to the germ band stage without the need for conditioning with host tissue. IPL-52B supported development to the germ band stage when a defined lipid concentrate was added. In IPL-52B medium, the IPLB-LdFB cell line promoted a significantly higher number of eggs developing to germ band relative to the other cell lines; however, none of the cell line-conditioned IPL-52B medium significantly stimulated egg hatch relative to the control medium. None of the cell line-conditioned Grace's media had a significant effect on eggs attaining germ band stage compared with the Grace's control medium. However, Grace's medium conditioned with the IAL-TND1 and IPLB-LdFB cell lines promoted development beyond germ band, resulting in a significantly higher percentage of hatching eggs than the Grace's control medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Stimulation of embryonic development in Microplitis croceipes (Braconidae) in cell culture media preconditioned with a fat body cell line derived from a nonpermissive host, gypsy moth, Lymantria dispar.

A cell culture medium, IPL-52B, was preconditioned with host fat body and two insect cell lines to determine if they would support embryonic development of Microplitis croceipes in vitro. The medium was preconditioned with the cell line IPL-LdFB, derived from fat body of the gypsy moth, Lymantria dispar, cell line IAL-TND1, derived from imaginal discs of the cabbage looper, Trichoplusia ni, and whole fat body tissue from host Helicoverpa zea. A second cell culture medium, Excell 400, was preconditioned with only the cell line, IPL-LdFB. Pregerm band eggs were dissected from third instar host larvae and incubated in the conditioned medium for 20 h. Newly laid parasitoid eggs did not develop in unconditioned IPL-52B, but did develop to germ band stage in unconditioned Excell 400. The IPL-52B medium conditioned with both cell lines induced germ band formation, but only the L. dispar cell line (IPL-LdFB) promoted significant development to eclosion comparable to host far body tissue. Excell 400 medium preconditioned with the cell line, IPL-LdFB also supported development to eclosion.

Vitamin E, diethylmaleate and bromotrichloromethane interactions in oxidative damage in vivo.

In vivo interactions of vitamin E with diethylmaleate (DEM) and bromotrichloromethane (CBrCl3) were examined in rats fed a diet either without vitamin E or supplemented with 30 IU dl-alpha-tocopheryl acetate/kg. Groups of rats within each dietary group were given two injections 30 min apart. One group received two injections of the mineral oil carrier. The other groups were injected with either DEM and mineral oil, mineral oil and CBrCl3, or DEM and CBrCl3. The rats were killed 10 min after the second injection. Measurements were made of hepatic GSH, thiobarbituric acid-reactive substances (TBARS) as a lipid peroxidation index, and 11 enzymes as potential markers of oxidant damage. Special focus was placed on reactive cysteine-containing aldehyde dehydrogenase (ALDH). Although dietary vitamin E protected ALDH, the enzyme was highly susceptible to oxidant damage. ALDH activity was correlated with GSH (r = 0.83, p less than 0.001) and there was an inverse relationship between the logarithmic values of ALDH activity and TBARS (r = 0.78, p less than 0.001). Similar results were observed for a number of other enzymes when GSH depletion preceded oxidant treatment. Two-way analysis of variance revealed significant effects of vitamin E and of injection treatments on hepatic GSH. There was a significant interaction between vitamin E and the injection treatments on the activities of five enzymes. The results suggested that vitamin E and GSH functioned together to protect sensitive enzymes against oxidant stress. The sensitive enzymes may be useful markers of hepatic damage in vivo.

Can serum bilirubin be an index of in vivo oxidative stress?

Bilirubin has been suggested as a physiological antioxidant, and recent studies suggest that its synthesis is induced in response to oxidative stress. Numerous reports in the literature show increases in serum bilirubin when using halogenated hydrocarbons as oxidative stress inducers. Analogously, these increases should also be expected for other inducers. On the other hand, bilirubin is destroyed by the same molecules that induce its production. The measurement of bilirubin may be a useful index of in vivo oxidative stress, although no big differences in bilirubin levels should be expected.

Effects of female wasp accessory secretions, host fat body, and host hemolymph on protein synthesis and egg viability in Microplitis croceipes (Braconidae).

Effects of female wasp reproductive gland secretions, host fat body and hemolymph, and mechanical constriction of the parasitoid egg on protein synthesis were studied in eggs of Microplitis croceipes (Braconidae) dissected from the wasp ovary. Protein synthesis was measured by 35S-methionine incorporation in eggs held in tissue culture medium for 16 h after treatment. Synthesis was stimulated in oocytes obtained from three regions of the ovary (egg tube, reservoir, and calyx) by fat body and venom gland but not by calyx fluid. A combination of fat body, venom gland, and calyx fluid did not enhance the level of synthesis relative to that of fat body or venom gland alone. Host hemolymph inhibited protein synthesis when incubated directly with the dissected eggs but not when the eggs were collected from an artificial oviposition substrate (AOS) containing hemolymph. The inhibitory effect of the hemolymph is thought to be due to the occurrence of melanization. Mechanical constriction did not alter the rate of synthesis, confirming an earlier report that synthesis in newly deposited eggs in ongoing and is not dependent on mechanical activation during the act of oviposition. Mechanisms responsible for sustaining protein synthesis in eggs for 16 h in vitro after their exposure to host hemolymph in the AOSs or fat body and venom gland are not known. Only a small percentage (less than 2%) of dissected ovarial reservoir oocytes that were mechanically constricted and exposed to the venom gland, calyx fluid, and host fat body hatched in vitro. In contrast, an earlier study demonstrated that 38% of eggs oviposited by female wasps into AOSs developed and hatched.

Lipid peroxidation products in biological tissues.

Over the past twenty-years of lipid peroxidation research in this laboratory, considerable effort has gone into development of new methods, with emphasis on measurement of lipid-soluble fluorophores and the volatile hydrocarbons ethane and pentane. Application of these and other methods has been made to biological materials and living animals. Although the various methodologies used in lipid peroxidation research do not necessarily measure the same class of products, and although agreement of results is not always 100%, there is substantial documentation of good correlations between measurements; for example, of trace volatile hydrocarbons with thiobarbituric acid-reacting substances, of pentane production with dietary and/or tissue vitamin E content, and of pentane production with lipid-soluble fluorophores accumulated in spleen as a function of oxidant stress. Individual methodologies do have their inherent limitations. However, measurements of multiple products and their correlations have added significantly to the base of information on biological damage and protection by dietary antioxidants against nutritional and toxicological insults to tissues, cells, and macromolecules as a result of peroxidative and oxidative reactions.

In vivo effects of aurothioglucose and sodium thioglucose on rat tissue sulfhydryl levels and plasma sulfhydryl reactivity.

The active component of aurothioglucose (ATG) in effecting changes in plasma sulfhydryl (SH) levels and plasma SH reactivity with 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) was determined. These two measurements are applied clinically to rheumatoid arthritis patients undergoing chrysotherapy. Normal rats were injected intramuscularly daily for seven days with 30 mumol of either ATG or sodium thioglucose (STG)/kg body wt or with an equivalent volume of the carrier, 0.05% benzyl alcohol. ATG but not STG significantly increased total SH levels in plasma, liver, and kidney. The seven-day treatment with ATG significantly increased glutathione levels in kidney but not in liver or plasma. Thus, gold(I) rather than thioglucose was the active moiety that affected SH levels in ATG-injected rats. In vivo, gold(I) was also the active moiety that stimulated plasma SH reactions with DTNB at pH 7.4, since injection of ATG but not STG stimulated the SH reactivity in fresh plasma. In vitro, ATG increased the rate of plasma reaction with DTNB at pH 7.4, thus, gold(I) ions acted as a catalyst in the SH-disulfide exchange reaction. This study demonstrates that gold(I) but not its thiol ligand strongly interacts with protein SH groups in the rat tissues. Such an interaction may play an important role in the biological actions of gold.

Effect of chronic aurothioglucose treatment of rats on kidney catalase and cytochromes.

Catalase activity and cytochrome content were measured in kidneys of Fisher 344 rats injected with aurothioglucose (ATG) either daily for 3 days or 5 days a week for up to 8 wk. Catalase activity was decreased 39%, 59%, and 48% (all p less than 0.001) after 3 days, 2 wk, and 8 wk, respectively. Microsomal cytochrome P-450 levels decreased 71%, 86%, and 80% (all p less than 0.001) after 3 days, 2 wk, and 8 wk, respectively. In contrast, cytochrome b5 was significantly increased at 3 days and 2 wk, but not at 8 wk. Microsomal heme contents decreased 44% (p less than 0.001), 34% (p less than 0.001), and 22% (p greater than 0.05) at 3 days, 2 wk, and 8 wk, respectively. The content of mitochondrial cytochromes aa3, b, c1, and c were not affected after 8 wk of ATG treatment. In vitro inhibition of the heme-containing enzyme delta-aminolevulinic acid dehydratase by ATG was reversible in the presence of physiological concentrations of small thiols. Although the activity of this enzyme in kidneys of ATG-treated rats was not measured, its significant inhibition in vivo by ATG appears unlikely. This study demonstrates that there were differential effects of gold on the various cytochromes and that changes in catalase activity paralleled changes in cytochrome P-450 and heme contents in the kidneys of ATG-treated rats. The findings are relevant to nephrotoxicity during chrysotherapy.

Aurothioglucose effect on sulfhydryls and glutathione-metabolizing enzymes: in vivo inhibition of selenium-dependent glutathione peroxidase.

Fisher 344 rats injected with a total of 20.8 +/- 1.5 mg of gold (Au) as aurothioglucose over an 8-wk period were used to study the effect of long-term Au treatment on selenium-dependent glutathione peroxidase (SeGSHPx), other enzymes related to GSH metabolism, GSH, nonprotein sulfhydryls, and total sulfhydryls (SH) in various tissues. The indirect coupled assay for SeGSHPx revealed decreased activity in platelets of Au-treated rats but not in other tissues. Inhibition of SeGSHPx by Au is reversible upon dilution. A direct assay of GSH consumption by concentrated tissue cytosols that was developed to minimize enzyme dilution provided evidence of in vivo inhibition of SeGSHPx in kidney and liver from Au-injected rats. Kidneys of these rats had decreased (P less than 0.05) activities of GSSG reductase (36%), gamma-glutamylcysteine synthetase (19%), and gamma-glutamyl transpeptidase (26%), and increased (P less than 0.05) activities of glucose 6-phosphate dehydrogenase (90%) and GSH S-transferase (130%). The reactivity of fresh plasma SH groups with 5,5'-dithiobis-(2-nitrobenzoic acid) increased as a function of injection time. Enhanced SH reactivity suggests that Au may react with protein GSH-disulfides to release GSH. New findings were (i) decreased platelet SeGSHPx and kidney GSSG reductase in aurothioglucose-injected rats, (ii) direct in vivo inhibition of kidney and liver SeGSHPx in aurothioglucose-injected rats, and (iii) no significant correlation between the activity of GSH-metabolizing enzymes and levels of tissue GSH.

Effect of aurothioglucose on glutathione and glutathione-metabolizing and related enzymes in rat liver and kidney.

The antirheumatic drug aurothioglucose is an inhibitor of the selenoenzyme GSH peroxidase. During chrysotherapy, the decreased levels of erythrocyte GSH and serum sulfhydryls of rheumatoid arthritis patients are normalized concomitant with clinical efficacy. This investigation examined the in vivo and in vitro effect of gold(I) as aurothioglucose on enzymes related to the GSH redox cycle or metabolism. The enzymes measured were GSH peroxidase, GSSG reductase, gamma-glutamyl transpeptidase, gamma-glutamylcysteine synthetase, GSH S-transferase, GSH thiotransferase, glucose-6-phosphate dehydrogenase, superoxide dismutase and catalase. Rats were injected with 30 mumol aurothioglucose/kg body wt. daily for 7 days by intramuscular injection. GSH levels in aurothioglucose-treated rats were 68% higher in erythrocytes (P less than 0.005) and 45% higher in kidney (P less than 0.001) than in control rats. Treatment with aurothioglucose did not elevate plasma or liver GSH. The enzyme activities that were changed by aurothioglucose treatment were GSH peroxidase in kidney (41% decreased, P = 0.005) and liver (13% decreased, P less than 0.05), gamma-glutamyl transpeptidase in kidney (15% decreased, P less than 0.05), and catalase in kidney (58% decreased, P less than 0.001). Kidney glucose-6-phosphate dehydrogenase activity was increased 50% (P less than 0.005) and GSH S-transferase was increased 72% (P less than 0.001). In vitro the only liver enzymes inhibited more than 50% by concentrations of less than 50 microM aurothioglucose were GSH peroxidase (50% inhibited by 25 microM aurothioglucose) and GSH thiotransferase (50% inhibited by 5 microM aurothioglucose). Studies of in vitro enzyme inhibition by aurothioglucose could not be used to predict decreased enzyme activities in vivo. Although decreased activities of two major enzymes that utilize GSH, GSH peroxidase and gamma-glutamyl transpeptidase, coincided with elevated GSH in kidneys of aurothioglucose-treated rats, a direct cause and effect relationship remains speculative.

Mercury, silver, and gold inhibition of selenium-accelerated cysteine oxidation.

In vivo, cysteine in proteins or glutathione is the major amino acid involved in sulfhydryl oxidation-reduction reactions. An in vitro model of cysteine oxidation accelerated by selenium compounds was used to study the interaction of selenocystine and sodium selenite with metal ions. The interaction of metal ions with selenium compounds inhibited cysteine oxidation. The ionic forms of three toxic soft-acid metals, mercury, silver, and gold, were the most effective inhibitors. The antiarthritic gold drugs, aurothiomalate and aurothioglucose, were of particular interest as they inhibit the activity of selenium-glutathione peroxidase. The effect of gold ligands on gold(I) inhibition of selenocystine-accelerated cysteine oxidation was tested. Sodium cyanide partially reversed inhibition and potassium iodide had no effect. Inhibition of selenium-accelerated oxidation-reduction reactions by soft-acid metal ions may be of biological relevance during toxicities or during antiarthritic gold therapy.

Are some major in vivo effects of gold related to microenvironments of decreased selenium?

Gold interacts with selenium in vivo, and the normal distribution of selenium among tissues and subcellular compartments changes. Literature evidence shows that many of the effects of gold compounds on the polymorphonuclear neutrophil, macrophage, and lymphocyte cellular components of the immune system are similar to effects observed in these cellular components in selenium-deficient animals. Affected by these two metals are immune functions related to phagocytic cell migration, phagocytosis, microbial killing, lymphocyte mitogenesis/DNA synthesis, arachidonic acid metabolism/prostaglandin synthesis, and immunoglobulin production. The interaction of gold with selenium in vivo may be responsible for some of the multiparameter-based actions of gold compounds used in the treatment of inflammatory diseases such as rheumatoid arthritis. One mechanism by which gold exerts its clinical effects may be related to its interaction with selenium to produce, in specific microenvironments, decreased levels of this essential trace element.

Effect of dietary vitamin E and Santoquin on regenerating rat liver.

The influence of dietary vitamin E and Santoquin on lipid peroxidation and liver regeneration in partially-hepatectomized rats was studied. Rats were fed either a basal 10% tocopherol-stripped corn oil diet, the basal diet plus 40 mg dl-alpha-tocopheryl acetate/kg, or the basal diet plus 2 g Santoquin (6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline)/kg. After 6 weeks, rats fed the antioxidant-deficient diet produced more of the lipid peroxidation product, pentane, than did the rats fed antioxidants. Partial hepatectomy was performed after six and one-half weeks or ten weeks of feeding the diets. At 3 and 6 days after surgery, pentane production was significantly elevated over pre-surgery levels in rats fed the antioxidant-deficient or vitamin E-supplemented diets, but not in rats fed the Santoquin-supplemented diet. Six days after surgery, there were fewer thiobarbituric acid reactants in regenerating liver of Santoquin-fed rats than of vitamin-E fed rats or antioxidant-deficient rats. There was no increase in the 6-day level of thiobarbituric acid reactants over the 3-day level in livers of rats fed Santoquin, while there was an increase in livers of the antioxidant-deficient and vitamin E-supplemented rats. Liver sulfhydryl levels were higher at 3 and 6 days post surgery in the Santoquin-fed rats than in the antioxidant-deficient or vitamin E-supplemented rats. Plasma gamma-glutamyl-transpeptidase activity was not different among the groups of rats. Between the third and sixth day following surgery, liver regeneration was significantly stimulated in Santoquin-fed, but not vitamin E-fed rats. After 11 days, a stimulatory, but not statistically significant, effect of vitamin E was found. Although DNA content of liver was higher at 6 days than at 3 days post surgery, it was not different among the dietary groups, indicating that cell proliferation rather than hypertrophy had occurred. Partial hepatectomy could have altered the ability of the liver to metabolize pentane, thus explaining part of the increased production of pentane. However, the results obtained support the interpretation that elevated levels of dietary antioxidants can be beneficial in terms of reduced lipid peroxidation and increased rates of liver regeneration following liver surgery.

The effect of iron overload on urinary excretion of immunoreactive prostaglandin E2.

The effect of in vivo lipid peroxidation on the excretion of immunoreactive prostaglandin E2 (PGE2) in the urine of rats was studied. Weanling, male Sprague-Dawley rats were fed a vitamin E-deficient diet containing 10% tocopherol-stripped corn oil (CO) or 5% cod liver oil (CLO) with or without 40 mg dl-alpha-tocopheryl acetate/kg. To induce a high, sustained level of lipid peroxidation, some rats were injected intraperitoneally with 100 mg of iron as iron dextran after 10 days of feeding. Iron overload stimulated in vivo lipid peroxidation in rats, as measured by the increase in expired ethane and pentane. Dietary vitamin E reversed this effect. Rats fed the CLO diet excreted 9.5-fold more urinary thiobarbituric acid-reactive substances (TBARS) than did rats fed the CO diet. Iron overload increased the excretion of TBARS in the urine of rats fed the CO diet, but not in urine of rats fed the CLO diet. Dietary vitamin E decreased TBARS in the urine of rats fed either the CO or the CLO diet. Iron overload decreased by 40% the urinary excretion of PGE2 by rats fed the CO diet, and dietary vitamin E did not reverse this effect. Iron overload had no statistically significant effect on urinary excretion of PGE2 by rats fed the CLO diet. A high level of lipid peroxidation occurred in iron-treated rats, as evidenced by an increase in alkane production and in TBARS in urine in this study, and by an increase in alkane production by slices of kidney from iron-treated rats in a previous study [V. C. Gavino, C. J. Dillard, and A. L. Tappel (1984) Arch. Biochem. Biophys. 233, 741-747]. Since PGE2 excretion in urine was not correlated with these effects, lipid peroxidation appears not to be a major factor in renal PGE2 flux.

Effect of dietary selenium and injected gold thioglucose on adjuvant-treated rats.

Gold (Au) thioglucose, which has been used in the treatment of rheumatoid arthritis, inhibits selenium (Se)-glutathione peroxidase. Since Au and Se play roles in inflammation, the effects of dietary Se (0, 0.2, and 2.0 ppm for 10 weeks) and injected gold thioglucose (5 mg Au/day/kg body weight for 28 days) in adjuvant-treated rats were investigated. Au toxicity was evidenced by lower body weights and higher tissue weight/body weight ratios for kidneys and spleens of Au-treated rats. Adjuvant-induced inflammation, measured by paw thickness, was not influenced by dietary Se, although Au decreased inflammation in Se-deficient rats. Liver glutathione peroxidase activity was depressed by Se deficiency and by Au. Sulfhydryl levels in liver soluble fraction and plasma were highest for Se-deficient rats. Among liver, kidney, spleen, and plasma, thiobarbituric acid reactants were highest in kidneys of Au-treated rats and lowest in plasma of rats fed 2 ppm Se. gamma-Glutamyltranspeptidase activity in plasma indicated liver damage in Se-deficient rats. Kidney PGE2 output in 24-hour urine samples was unaffected by Au, Se, or adjuvant. Au-Se interactions in vivo are complex, but decreased glutathione peroxidase activity in Au-injected rats suggests that Se nutrition of Au-treated rheumatoid arthritis patients may be a practical concern.