CHARACTERIZATION OF LYMPHOCYTE TRANSFORMATION INDUCED BY ZINC IONS

Lymphocyte cultures from all normal human adults are stimulated by zinc ions to increase DNA and RNA synthesis and undergo blast transformation. Optimal stimulation occurs at 0.1 mM Zn⁺⁺. Examination of the effects of other divalent cations reveals that 0.01 mM Hg⁺⁺ also stimulates lymphocyte DNA synthesis. Ca⁺⁺ and Mg⁺⁺ do not affect DNA synthesis in this culture system, while Mn⁺⁺, Co⁺⁺, Cd⁺⁺, Cu⁺⁺, and Ni⁺⁺ at concentrations of 10^-7–10^-3 M are inhibitory. DNA and RNA synthesis and blast transformation begin to increase after cultures are incubated for 2–3 days with Zn⁺⁺ and these processes reach a maximum rate after 6 days. The increase in Zn⁺⁺-stimulated lymphocyte DNA synthesis is prevented by rendering cells incapable of DNA-dependent RNA synthesis with actinomycin D or by blocking protein synthesis with cycloheximide or puromycin. Zn⁺⁺-stimulated DNA synthesis is also partially inhibited by 5'-AMP and chloramphenicol. Zn⁺⁺ must be present for the entire 6-day culture period to produce maximum stimulation of DNA synthesis. In contrast to its ability to independently stimulate DNA synthesis, 0.1 mM Zn⁺⁺ inhibits DNA synthesis in phytohemagglutinin-stimulated lymphocytes and L1210 lymphoblasts.     

Primary induction of metallothionein by dexamethasone in cultured rat hepatocytes

Dexamethasone or Zn⁺⁺ increase the rate of synthesis of the metal-binding protein metallothionein in hepatocyte cultures. Dexamethasone induction of the capacity to synthesize metallothionein is not blocked by cycloheximide. In contrast, the dexamethasone stimulated increase in Zn⁺⁺ uptake is inhibited by cycloheximide. Like Zn⁺⁺, dexamethasone is a “primary inducer” of metallothionein. The glucocorticoid induction of metallothionein in primary cultures of rat hepatocytes is not mediated through elevation of Zn⁺⁺ uptake.     

Biochemical and morphological aspects of zinc deficiency in rhodotorula gracilis

Summary Cells of Rhodotorula gracilis cultured in a liquid medium containing Zn only as impurity stop growing at a density of about 5·10⁷ cells/ml. The addition of Zn during the prestationary or the stationary phase of growth reestablishes the growth rate, thus showing that Zn⁺⁺ is a limiting factor for growth. An analysis of the changes of the fine structure and of RNA, DNA and protein levels induced by the addition of Zn to Zn-deficient cultures indicates that the most notable features of Zn deficiency are: a) the decrease of net RNA synthesis, and consequently of protein synthesis; b) the appearance of several large vacuole-like structures containing degraded cytoplasmic components, membranous whorls and amorphous material; a decrease in the number of mitochondria and in the organization of cristae. The net synthesis of DNA appears to be much less affected, and lipid synthesis is somewhat stimulated in the Zn-deficient cultures. No important effect of Zn-deficiency was observed on either oxygen uptake or intracellular amino acid level. These results are interpreted as indicating that Zn⁺⁺ is an essential element for this organism, and that the area of RNA metabolism and protein synthesis is the one primarily affected by Zn⁺⁺ deficiency.     

Activation and proliferation signals in murine macrophages: stimulation of glucose uptake by hemopoietic growth factors and other agents

Purified colony-stimulating factor (CSF-1) (or macrophage colony stimulating factor [M-CSF]) stimulated the glucose uptake of murine bone marrow-derived macrophages (BMM) and resident peritoneal macrophages (RPM) as measured by 3H-2-deoxyglucose (2-DOG) uptake. Similar concentrations of CSF-1 stimulated the 2-DOG uptake and DNA synthesis in BMM. Other purified hemopoietic growth factors, granulocyte-macrophage CSF (GM-CSF) and interleukin-3 (IL-3) (or multi-CSF), and the tumor promoter, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), even though differing in their mitogenic capabilities on BMM, were also stimulators of 2-DOG uptake in BMM and RPM. The nonmitogenic agents, lipopolysaccharide (LPS) and concanavalin A (Con A), were also active. The inhibition by cytochalasin B and by high concentrations of D-glucose suggest that the basal and stimulated 2-DOG uptake occurred via a carrier-facilitated D-glucose transport system. The responses of the two macrophage populations to the hemopoietic growth factors and to the other agents were quite similar, suggesting that events that are important for the induction of DNA synthesis are not tightly coupled to the earlier rise in glucose uptake. For the BMM, the ability of a particular agent to stimulate glucose uptake did not parallel its ability to promote cell survival. However, stimulation of glucose uptake could still be a necessary but insufficient early macrophage response for cell survival and subsequent DNA synthesis.     

Chelation of divalent cations by lomofungin: role in inhibition of nucleic acid synthesis

Lomofungin inhibition of yeast growth and RNA synthesis is prevented by Cu⁺⁺ or Zn⁺⁺ ions which chelate with the antibiotic and prevent its uptake by the cells. EDTA potentiates the inhibition. Mg⁺⁺ ions do not protect $\text{in vivo}$ or against the inhibition of purified bacterial RNA and DNA polymerases. Lomofungin prevents formation of the RNA polymerase. DNA initiation complex, probably by chelation with the firmly bound Zn⁺⁺ of the enzyme.     

Studies on the mechanism of hrmonal stimulation of zinc uptake in human cell cultures: hormone-cell interactions and characteristics of zinc accumulation

Adrenal steroid hormones with glucocorticoid activity increase the uptake of Zn⁺⁺ in HeLa cell cultures. On the basis of the level of Zn⁺⁺ accumulation induced, steroid hormones can be classified into four groups: (a) optimal inducers (e.g., hydrocortisone and prednisolone); (b) suboptimal inducers (e.g., aldosterone and corticosterone); (c) anti-inducers (e.g., progesterone and 17 α-methyl testosterone) which competitively inhibit induction by optimal inducers; and (d) non-inducers (e.g., cortisone and pregnenolone) which neither induce nor inhibit the steroid-mediated increase in Zn⁺⁺ uptake. The ability of an anti-inducer to block the effects of optimal inducers is not the result of inhibition of steroid uptake or an effect on general protein synthesis. Optimal inducers do not increase adenyl cyclase activity of HeLa cells nor can the hormone effects on Zn⁺⁺ uptake be reproduced by 3'-5' cyclic AMP. The prednisolone-induced enhancement of Zn⁺⁺ uptake is gradually lost over two or three days following removal of the hormone. Uptake of Zn⁺⁺ by HeLa cells is not altered by a decrease of sodium concentration in the medium nor by changes in medium osmolarity. The uptake mechanism is not affected by subjecting intact cells to proteolytic enzymes; however, if cells are disrupted the hormone-mediated increase in Zn⁺⁺ accumulation is lost. The Zn⁺⁺ taken up by HeLa cells in the presence or absence of hormone is primarily cytoplasmic in localization and appears to be distributed in a multicompartmental system.     

pH, serum and Zn++ in the regulation of DNA synthesis in cultures of chick embryo cells

Variations in pH, serum concentration and the availability of Zn⁺⁺ in the medium markedly influence the initiation of DNA synthesis in cultured chick embryo cells. This report considers the interplay of these factors with one another and with other factors such as type of medium, cell population density and the malignaut transformation in an attempt to better define the variables of the growth control system. Conditioned medium seems to protect the cells against the inhibitory effects of lowered pH. Increased serum concentration has a similar, but more striking effect. Increased serum concentration and pH, as well as decreased population density, which stimulate DNA synthesis, also lower the sensitivity of DNA synthesis to inhibition by Zn⁺⁺ deprivation. Likewise, cell transformation by infection with Rous sarcoma virus lowers the sensitivity of DNA synthesis to inhibition by Zn⁺⁺ deprivation and by pH reduction. The response of DNA synthesis to pH varies with the type and concentration of buffer used. It is concluded that there are a number of mutually interacting variables involved in the regulation of animal cell multiplication.     

ZINC REQUIREMENT FOR DNA REPLICATION IN STIMULATED HUMAN LYMPHOCYTES

The requirement for Zn⁺⁺ in DNA replication by phytohemagglutinin-stimulated human lymphocytes was studied. When 6 µM o-phenanthroline, a chelator with a high affinity for Zn⁺⁺, is added to cultures of stimulated lymphocytes a nearly complete inhibition of thymidine incorporation results within a few hours. In contrast, the incorporation of uridine is only slightly reduced and the incorporation of leucine is unaffected. m-Phenanthroline, a nonchelating analogue, does not alter the rate of thymidine incorporation even when present in 10-fold greater amounts than o-phenanthroline. The inhibition of thymidine incorporation by o-phenanthroline could be entirely reversed by the addition of Zn⁺⁺ to the cultures, or could be prevented by the prior addition of either Zn⁺⁺ or Ni⁺⁺. All other divalent cations tested were incapable of reversing the o-phenanthroline inhibition of thymidine incorporation.     

Inhibition by metals of X-ray and ultraviolet-induced DNA repair in human cells

A number of metals have been shown to be involved in the etiology of animal and human neoplasms. The molecular mechanisms have not yet been determined, but the observed plethora of genetic effects observed following treatment of mammalian cells with metals clearly indicates the possibility that metals can exert their effects at least partially at the level of DNA metabolism. Several studies have suggested that metal treatment may inhibit normal DNA repair processes in procaryotic and eucaryotic cells but a systematic study of this question has not previously been conducted. The present study surveyed the ability of 15 metal salts to interfere with repair of X-ray or UV-induced DNA damage in HeLa cells. Hg⁺⁺, As⁺⁺⁺, Cu⁺⁺, Ni⁺⁺, Co⁺⁺, and Cd⁺⁺ were shown to inhibit the excision of pyrimidine dimers from DNA and to do so in a dose-dependent fashion. Inhibition of repair by only Ni⁺⁺ and Co⁺⁺ resulted in the accumulation of long-lived DNA strand breaks suggestive of a block in the gap-filling stage of repair. Ability to inhibit repair was not correlated with cytotoxicity. X-ray repair was sensitive to Hg⁺⁺, Ni⁺⁺, As⁺⁺⁺, Ga⁺⁺, Zn⁺⁺, and Mo(VI). All inhibitory metals inhibited closure of single strand DNA breaks. Ga⁺⁺ appeared, in addition, to inhibit a later step involving chromatin reconstitution. These findings support the notion that interference of DNA repair processes may be a consequence of exposure of mammalian cells to certain metals. This may be a factor in the etiology of metal-associated carcinogenesis.     

The SbMT-2 Gene from a Halophyte Confers Abiotic Stress Tolerance and Modulates ROS Scavenging in Transgenic Tobacco

Heavy metals are common pollutants of the coastal saline area and Salicornia brachiata an extreme halophyte is frequently exposed to various abiotic stresses including heavy metals. The SbMT-2 gene was cloned and transformed to tobacco for the functional validation. Transgenic tobacco lines (L2, L4, L6 and L13) showed significantly enhanced salt (NaCl), osmotic (PEG) and metals (Zn⁺⁺, Cu⁺⁺ and Cd⁺⁺) tolerance compared to WT plants. Transgenic lines did not show any morphological variation and had enhanced growth parameters viz. shoot length, root length, fresh weight and dry weight. High seed germination percentage, chlorophyll content, relative water content, electrolytic leakage and membrane stability index confirmed that transgenic lines performed better under salt (NaCl), osmotic (PEG) and metals (Zn⁺⁺, Cu⁺⁺ and Cd⁺⁺) stress conditions compared to WT plants. Proline, H₂O₂ and lipid peroxidation (MDA) analyses suggested the role of SbMT-2 in cellular homeostasis and H₂O₂ detoxification. Furthermore in vivo localization of H₂O₂ and O₂ ⁻; and elevated expression of key antioxidant enzyme encoding genes, SOD, POD and APX evident the possible role of SbMT-2 in ROS scavenging/detoxification mechanism. Transgenic lines showed accumulation of Cu⁺⁺ and Cd⁺⁺ in root while Zn⁺⁺ in stem under stress condition. Under control (unstressed) condition, Zn⁺⁺ was accumulated more in root but accumulation of Zn⁺⁺ in stem under stress condition suggested that SbMT-2 may involve in the selective translocation of Zn⁺⁺ from root to stem. This observation was further supported by the up-regulation of zinc transporter encoding genes NtZIP1 and NtHMA-A under metal ion stress condition. The study suggested that SbMT-2 modulates ROS scavenging and is a potential candidate to be used for phytoremediation and imparting stress tolerance.     

Effect of zinc sulphate on the growth of mono- and multispecies cultures of some marine plankton algae

The effect of zinc sulphate has been investigated in mono- and multispecies cultures of the dinoflagellatesScrippsiella faeroense, Prorocentrum micans andGymnodinium splendens and of the diatomsSchroederella schroederi andThalassiosira rotula. Multiplication rate, in vivo chlorophyll fluorescence, maximum cell densities and Zn-conditioned disturbance of the species equilibrium of the multispecies cultures were used as criteria of sublethal toxic inhibition. In monocultures, the first effect became manifest after addition of 0.01 to 0.1 mg Zn⁺⁺ · l^–1. Diatoms proved to be more sensitive than dinoflagellates. In multispecies cultures, the growth of each species depended on the ratio of the inocula. Interrelation between interspecific competition and Zn-caused decrease in the number of algal cells regulated further growth of the cultures. Algal sensitivity to zinc increased with the number of species combined in the test medium: in a 5-species culture sublethal changes appeared already after addition of 0.005 to 0.01 mg Zn⁺⁺ · l^–1. In a few cases, interspecific competition depressed the growth of some species to an appreciable extent, even in the control cultures. At the resulting low cell numbers, the effect of zinc became apparent only in higher concentrations from 5 to 10 mg Zn⁺⁺ · l^–1. Morphological aberrations became manifest inScrippsiella faeroense and in the diatoms in concentrations from 1 and 0.01 mg Zn⁺⁺ · l^–1 respectively. The results show that multispecies experiments are a more sensitive test method for investigating the influence of zinc on plankton algae than are monoculture experiments. In natural plankton communities, however, the toxicity of heavy metals may become effective at considerably lower limit concentrations; this is suggested by the simplified model investigations in the laboratory.     

Metal ion binding byPithomyces chartarum conidia

Summary The binding of metals (Cu, Fe, Mn and Zn) commonly found in soil and decomposing plant material was studied in the saprophytic fungus,Pithomyces chartarum. Binding of metallic divalent cations was pH-dependent and temperature-independent; equilibrium occurred within 10 min in stirred suspensions of conidia, but mycelia had no detectable affinity for the metals. Germ tube emergence and elongation were stimulated by high concentrations of Mn⁺⁺ and Zn⁺⁺, byt not by Cu⁺⁺ or Fe⁺⁺. Metal binding did not obey a simple adsorption isotherm; Scatchard plot analysis indicated two classes of binding sites on the conidial surfaces, one class having association constants about 35-fold greater than those of the other. Calculations based on the conidial surface area as a smooth ellipsoid and the radii of the divalent cations indicated a multilayered coverage of the conidia by the metals at saturation concentrations. Binding sites were stable to boiling, dilute acid and base and lipid solvent extraction. The metals competed with the fungicide, thiabendazole, for binding sites on conidial surfaces.     

Tumor necrosis factor alpha,a cytokine coregulating sugar uptake by cultured human synovial cells.

Confluent cultures of osteoarthritic and rheumatoid human synovial cells were treated with human recombinant tumor necrosis factor alpha (TNF-α) The cytokine increased uptake of 2-deoxy-D-[1-³H]glucose (2-DOG) in a time- and concentrations-dependent manner. In synovial cells obtained from osteoarthritic patients (OA cells), the stimulation of 2-DOG uptake occurred 3 hours following addition of TNF-α (1 ng/ml) and was maximal by 24 hours Rheumatoid synovial cells (RA cells) appeared less sensitive to the cytokine: 2-DOG uptake stimulation was only significant after 6 hours of incubation. In both OA and RA cells, the effect was protein synthesis-dependent, and was not secondary to prostaglandin E2 synthesis or cell growth. Interteukin-1β was more efficient than TNF-α for 2-DOG uptake stimulation The two cytokines seemed to act in an additive manner.     

Selection and characterization of cadmium-resistant suspension cultures of the wild tomato Lycopersicon peruvianum

Suspension cultures of Lycopersicon peruvianum were selected for resistance to cadmium by stepwise exposure to increasing concentrations of cadmium sulfate. Resistant cells grow in 1500 micromolar Cd⁺⁺. This resistance was retained for thirty generations without selection. Both resistant and parental sensitive cultures take up Cd⁺⁺ at similar rates and to the same final levels. Exposure of sensitive or resistant cultures to Cd⁺⁺, Cu⁺⁺, or Zn⁺⁺ leads to the intracellular accumulation of a low molecular weight, cysteine-rich, cadmium-binding protein. This metallothionein is induced over fifteen fold by 100 M cadmium and builds up to about five fold higher levels in the resistant cultures.Abbreviations Cd⁺⁺ divalent cadmium ion - Cu⁺⁺ divalent copper ion - Zn⁺⁺ divalent zinc ion - BA benzyl adenine - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-acetic acid     

Antagonistic effects of insulin and cortisol on coordinate control of metabolism and growth in cultured fibroblasts

A variety of metabolic and biosynthetic pathways in chick embryo fibroblasts are stimulated coordinately by many unrelated exogenous agents. Three of the best characterized components of this coordinate response are the uptake of 2-deoxy-D-glucose (2-dGlc) and of uridine and the incorporation of thymidine into DNA. Insulin stimulates and cortisol inhibits the coordinate response. In cortisol-treated cultures, as little as 10^?3 units/ml of insulin may stimulate thymidine incorporation 4-fold and 10^?1 units/ml may stimulate as much as 40-fold. The higher concentrations of insulin completely override the inhibitory effect of cortisol. They also cause about a 5-fold stimulation of the uptake of 2-dGlc and of uridine and a 2-fold stimulation of proline incorporation into protein. The uptake rates of 2-dGlc and uridine double within 30 minutes after addition of insulin to cortisol-inhibited cultures, but the incorporation of thymidine only begins to increase markedly after a 4-hour delay. When cortisol is added to cultures in the absence of insulin, the rates of uptake of 2-dGlc and uridine begin to decrease within two hours, but the incorporation of thymidine remains constant for two hours before beginning to decrease. Deprivation of Mg²⁺ inhibits the accelerated coordinate response maintained by insulin, but does not further the inhibition induced by cortisol. Results with metabolic inhibitors indicate that the stimulation of 2-dGlc and uridine uptake by insulin do not require RNA synthesis, and also suggest that they do not require protein synthesis. These and other findings can be explained by a model for coordinate control in which insulin increases and cortisol decreases the availability of Mg²⁺ for a wide spectrum of regulatory reactions in different metabolic pathways. In this model both hormones affect only the rates of ongoing reactions and do not instruct the cell to carry out specific new reactions unless the cell was predetermined to do so.     

Resting cell studies on formation of water-soluble red pigments byMonascus sp.

Summary A resting cell system was developed for the biosynthesis of soluble red pigments byMonascus. The medium contains glucose, glycine, ZnSO₄ and MnSO₄ in pH 7.0 MOPS buffer containing cycloheximide to prevent protein synthesis. The linear production observed over a period of at least four h was due to de novo polyketide synthesis and biological methylation, as shown by inhibition with cerulenin, iodoacetamide and ethionine. Production was inhibited by carbonyl reagents and stimulated by pyridoxamine suggesting that the conversion of endogenous intracellular orange pigments to extracellular red pigments involves Schiff base intermediates and vitamin B₆ a cofactor. The resting cell system was used to study the mode of action of nutritional effectors previously pinpointed by experiments with growing cells. The negative effects of high concentrations of phosphate and Mg⁺⁺ are due to inhibition of pigment synthase action, not to repression or inactivation of these enzymes. The positive effects of trace metals, especially Zn⁺⁺, are due to stimulation of growth and enzyme action, not to induction or stabilization of the synthases.     

Effects of Metals on 3-Acetyldeoxynivalenol Production by Fusarium graminearum R2118 in Submerged Cultures

The effects of selected metals (Mg²⁺, Mn²⁺, Zn²⁺, and Fe²⁺) on 3-acetyldeoxynivalenol (3-ADN) production by Fusarium graminearum R2118 and on its mycelial growth were investigated by using a two-stage submerged-culture technique. In certain concentrations ranges, Mg²⁺ and Fe²⁺ stimulated growth but suppressed 3-ADN production; at other concentrations, Mg²⁺, Fe²⁺, and Zn²⁺ suppressed growth but stimulated 3-ADN production. In contrast, Mn²⁺ stimulated growth but totally inhibited 3-ADN production at all concentrations tested. In general, the production of 3-ADN was inversely related to the growth rate of the fungus with these metals. Mn²⁺ appears to be a crucial factor regulating the onset of 3-ADN biosynthesis.     

Calcium Uptake and Catecholamine Secretion by Cultured Bovine Adrenal Medulla Cells

Abstract: The uptake of ⁴⁵Ca²⁺ and secretion of catecholamines by primary cultures of adrenal medulla cells were studied. Nicotine, veratridine, potassium, and Ionomycin stimulate both the accumulation of ⁴⁵Ca²⁺ and the secretion of catecholamines. Nicotinic antagonists block ⁴⁵Ca²⁺ uptake induced by nicotine, tetrodotoxin blocks ⁴⁵Ca²⁺ uptake induced by veratridine, and D600 blocks uptake induced by K⁺, nicotine, and veratridine, but not ⁴⁵Ca²⁺ uptake or secretion induced by Ionomycin. The EC₅₀ for nicotine is 3 μm for catecholamine secretion and 10 μm for ⁴⁵Ca²⁺ uptake, while the EC₅₀S for veratridinestimulated uptake and secretion are approximately the same (75 μm ). Kinetic studies show that the uptake of Ca²⁺ is rapid and appears to precede the secretion of catecholamines, and that the rate of uptake declines rapidly. The uptake of ⁴⁵Ca²⁺ and secretion of catecholamines stimulated by veratridine and 50 mm -K⁺ show saturation kinetics with respect to external calcium concentrations at about 2 mm . On the other hand, the uptake of ⁴⁵ Ca²⁺ stimulated by nicotine does not become saturated at external calcium concentrations of 10 mm although the secretion of catecholamines reaches a maximum at external calcium concentrations of 2 mm . The data suggest that depolarizing agents such as veratridine and 50 mm -K⁺ stimulate ⁴⁵Ca²⁺ entry through voltage-sensitive calcium channels, while nicotinic agonists stimulate calcium entry through the acetylcholine receptor ion channels as well as through voltage-sensitive calcium channels.     

Augmentation of zinc ion stimulation of lymphoid cells by calcium and lithium

Stimulation of hamster lymph node cells by optimal concentrations of ZnCl₂ (10 μM) was found to be enhanced by addition of 1–25 mM LiCl to the serum-free cultures. Maximal enhancement occurred at 10 mM Li⁺. Similar concentrations of either KCl or NaCl did not potentiate stimulation. Addition of 1 mM CaCl₂, but not 1–25 mM MgCl₂, also potentiated Zn²⁺ stimulation of lymph node cells. When the cultures were supplemented with 1 mM Ca²⁺ + 10 mM Li⁺, a synergistic potentiation of Zn²⁺ stimulation occurred. In addition, the dose response curve for Zn²⁺ was shifted such that maximal stimulation occurred at 100–250 μM Zn²⁺, a concentration of Zn²⁺ which was toxic for the unsupplemented cultures. In Ca²⁺ + Li⁺ supplemented cultures, Zn²⁺ stimulated [³H]thymidine incorporation to levels comparable to those obtained when hamster lymphoid cells were stimulated with lectins. In addition to Zn²⁺ stimulation, Ca²⁺ + Li⁺ supplemented medium also enhanced Hg²⁺ stimulation of hamster lymph node cells but did not change the dose response curve for Hg²⁺. Therefore, the observed ionic effects on Zn²⁺ stimulation of lymphocytes were unique to this mitogen, when compared to either Hg²⁺ stimulation or previously reported lectin stimulation of hamster lymphoid cells.     

Effect of vitamin on 2-deoxy-d-glucose uptake in human fibroblast cultures

Summary 2-Deoxy-d-glucose (2-DOG) uptake was tested in human fibroblast cultures in the presence and absence of vitamin E. Addition of 10 μg/ml vitamin E to the culture medium significantly reduced this uptake for 2-DOG concentrations of 0.005, to 10 mmol/liter (P≤0.01). The decrease of 2-DOG uptake was inversely proportional to the rise in 2-DOG concentration (P≤0.01). The presence of vitamin E reduced by 71% the average cellular level of lipid peroxides (expressed as thiobarbituric acid reactive substances) and caused a small but significant decrease in the cholesterol concentration (P≤0.01). These last results might explain the decrease in 2-DOG uptake observed in the presence of vitamin E.