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Methylmercury (MeHg) exposure during pregnancy is a concern because of its potential health risks to fetuses. Intestinal microbiota has important roles in the decomposition and fecal excretion of MeHg. We investigated the effect of nondigestible saccharides on the accumulation and excretion of Hg after MeHg exposure. Female BALB/cByJ mice were fed a basal diet or the same diet supplemented with 5% fructooligosaccharides (FOS) or 2.5% glucomannan. Six weeks after feeding, mice were administered MeHg chloride (4 mg Hg/kg, per os (p.o.)), and urine and feces were collected for 28 d. FOS-fed mice had lower total Hg levels in all tissues (including the brain) compared with that of controls. The glucomannan diet had no effect on tissue Hg levels. No differences in tissue concentrations of inorganic Hg among groups were found. Fecal Hg excretion was markedly higher in FOS-fed mice than that in controls, but urinary Hg excretion was similar. FOS-fed mice had a higher proportion of inorganic Hg in feces than that of controls, with a significant increase in fecal Hg excretion. Analysis of fecal bacterial population showed the relative abundance of Bacteroides in FOS-fed mice to be higher than that in controls. The results suggest that FOS enhanced fecal Hg excretion and decreased tissue Hg levels after MeHg administration, possibly by accelerating MeHg demethylation by intestinal bacteria (the candidate genus Bacteroides). This demethylation also reduces MeHg absorption in the large intestine. In conclusion, daily FOS intake may decrease tissue Hg levels in animals and humans exposed to MeHg.

Cadmium (Cd) is an environmental pollutant present in contaminated water, food and soil. Cd adversely affects fetal development. We exposed pregnant mice to daily oral doses of 5 and 10 mg/kg Cd and examined fetal growth. It was demonstrated that the exposure to Cd (10 mg/kg) during gestation caused fetal growth retardation (FGR). Investigation of the ubiquitin-proteasome system in fetal livers of mice exposed to gestational Cd revealed increased polyubiquitinated protein accumulation, contrasting with decreased levels of monoubiquitin protein. Moreover, the expression level of Ubc (encoding polyubiquitin C protein) was significantly decreased in 5 and 10 mg/kg Cd-treated groups in comparison with the control group. Therefore, we propose that decrease of monoubiquitin level and accumulation of polyubiquitinated protein in the fetal liver may be important factors in Cd-induced FGR.

Cadmium (Cd) is an environmental contaminant that triggers toxic effects in various tissues such as the kidney, liver, and lung. Cd can also cause abnormal iron metabolism, leading to anemia. Iron homeostasis is regulated by intestinal absorption. However, whether Cd affects the iron absorption pathway is unclear. We aimed to elucidate the relationship between the intestinal iron transporter system and Cd-induced iron deficiency anemia. C57BL/6J female and male mice, 129/Sv female mice, and DBA/2 female mice were given a single oral dose of CdCl2 by gavage. After 3 or 24 h, Cd decreased serum iron concentrations and inhibited the expression of iron transport-related genes in the duodenum. In particular, Cd decreased the levels of divalent metal transporter 1 and ferroportin 1 in the duodenum. In addition, human colon carcinoma Caco-2 cells were treated with CdCl2. After 72 h, Cd decreased the expression of iron transport-related factors in Caco-2 cells with a pattern similar to that seen in the murine duodenum. These findings suggest that Cd inhibits iron absorption through direct suppression of iron transport in duodenal enterocytes and contributes to abnormal iron metabolism.

We compared the cadmium (Cd) concentration in the liver and kidney of different strains of mice after exposure to 50 ppm Cd for 30 days via drinking water. Cd concentration in the liver and kidney of C57BL/6J mice were higher than those of 129/Sv and DBA/2 mice. Since orally ingested heavy metals are absorbed in the small intestine and then widely distributed to target tissues, microarray analyses were performed to compare the expression levels of transport-related genes in the duodenum between C57BL/6J mice and 129/Sv or DBA/2 mice. The expression levels of 9 and 11 genes were elevated more than 2.0-fold and 13 and 12 genes were reduced less than 0.5-fold in 129/Sv mice and DBA/2 mice, respectively. Among these low expressed genes, 10 genes (Slc2a2, Slc5a1, Slc16a2, Slc22a13, Slc22a18, Slc25a11, Slc36a1, Slco6c1, Abca3 and Abcd1) were common between the two types of strains. These results suggest that some of those genes might be involved in Cd absorption and its toxicity.

This study investigated the influence of forest walking on blood pressure (BP), profile of mood states (POMS) and salivary cortisol in both young and aged people. Twenty-three young people (Men=11, Women=12) with a mean age of 22 yrs and twenty-five aged people (M=10, W=15) with a mean age of 59 yrs participated in this study voluntarily. Each participant walked about three hours in the forest according to their comfortable walking pace. After forest walking, systolic BP (SBP) and mean BP (MAP) had significantly decreased in aged people (-10±3 mmHg in SBP, and -5±2 mmHg in MBP, P

The role of intestinal flora in the decomposition and faecal excretion of methyl mercury was studied in mice treated with antibiotics. The antibiotics, neomycin sulfate and chloramphenicol, were given to mice in drinking water for six days before intraperitoneal administration of methyl mercuric chloride (MMC), and intestinal microorganisms were thereby reduced. Inorganic and organic mercury were determined separately for faeces, intestinal contents and organs. On the fourth day after the mercury administration, the percentage ratios of inorganic mercury to total mercury in the contents of the caecum and large intestine were less in the mice treated with antibiotics, at 37% and 39%, respectively, than in the control mice (66% and 65%, respectively). Administration of the antibiotics reduced the excretion of inorganic mercury in the faeces to 26% of that of control mice and also reduced the excretion of total mercury to 60%. Reduction of intestinal microorganisms by the antibiotics was assumed to have caused the reduced decomposition of methyl mercury in the caecal contents and the reduced excretion of total mercury in the faeces.

Metallothionein (MT) is a low-molecular-weight cysteine-rich protein which has a high affinity for metals and plays important roles in the protection against metal toxicity. As little information is available concerning the mechanism of MT induction by lead (Pb) compounds, we investigated the induction of MT by Pb acetate both at mRNA and protein levels in mice. Administration of Pb increased the levels of MT-I mRNA in the liver and kidney in six strains of mice. However, MT protein was detected only in the liver, and little or no increases in MT protein were detected in the kidney of any strains of mice. Speciation of metals in the liver cytosol showed that the major metal bound to MT was zinc but not Pb. The increases in plasma concentrations of interleukin-6 suggest that the production of interleukin-6 by Pb administration is involved in the induction of MT in the liver. Treatment of renal cells with Pb in vitro also resulted in the increase in MT mRNA but little increase in MT protein. These data suggest that Pb exerts a dual effect on MT expression; enhancement of MT gene transcription both in the liver and kidney and suppression of MT mRNA translation in the kidney.

Hepatic stellate (HS) cells were isolated from the livers of metallothionein (MT)-null and control mice and used to establish IMS/MT(-) and IMS/N cell lines, respectively, using SV40 virus transformation. Cellular morphology, incorporation of vitamin A and expression of alpha-SMA, desmin and SV40 T-antigen were used to confirm that both cell lines were immortal HS cells. The growth rates of both cell lines were similar and there was little difference between cell line sensitivity to zinc. MT-null IMS/MT(-) cells were more sensitive to cadmium and mercury, although both cell lines accumulated almost equal amounts of cadmium during a 24-hr culture period. As HS cells play an important role in hepatic fibrosis and are activated by heavy metals such as cadmium or reactive oxygen, the MT-null HS cell line derived in this study should be a useful experimental model for examination of the role of MT in HS cell activation.

We have made the unexpected discovery that copper sulfate protects Saccharomyces cerevisiae from the toxic effects of cisplatin. Addition of copper to the culture medium of yeast cells at concentrations above 0.1 microM significantly reduced the toxicity of cisplatin. Since a high-affinity copper transporter, Ctr1, has been reported to play a major role in the uptake of cisplatin, we examined the effects of copper on the cellular uptake of cisplatin. We found that the cellular concentration of platinum was not significantly affected by treatment of cells with 1 microM copper. It is known that mammalian metallothionein is induced by copper and is involved in acquired resistance to cisplatin. Copper significantly increased the level of mRNA for yeast metallothionein at a concentration that has effectively reduced the toxicity of cisplatin. However, the toxicity of cisplatin in cells with a disrupted gene for ACE1, a factor that regulates transcription of the yeast gene for metallothionein, was also significantly reduced by treatment with copper. These results suggest that copper protects yeast cells from cisplatin toxicity independently of induction of the synthesis of metallothionein and of the inhibition of platinum uptake. Since copper is one of the trace elements that are essential for cell function and since a relatively low concentration of copper (0.1 microM) significantly reduced cisplatin toxicity, it is possible that copper might play an important role in the expression of cisplatin toxicity.

Summary Cytotoxicity of tellurite to cultured HeLa cells was examined by cell viability, lactate dehydrogenase (LDH) assay, and tellurite uptake. The experimental results show that the toxicity of tellurite depends on its concentrations and exposure time. HeLa cells exposed to tellurite for 2 h at 9.1 × 10 −4 to 4.5 × 10 −3 mmol/L did not exhibit cytotoxic effects as measured by cell viability. Exposure to tellurite for 24 h at the same concentrations markedly reduced the cell viability to 57% of the control during the first 5 minutes. Additionally, HeLa cells incubated at 2.7 × 10 −2 to 0.27 mmol/L of tellurite for 2 h retained 53% to 67% of cell viability. Even after 24 h exposure, the HeLa cells incubated at 9.1 × 10 −4 to 4.5 × 10 −2 mmol/L of tellurite still retained 57% to 66% of cell viability. Furthermore, tellurite toxicity was also demonstrated in supernatant of the culture at 37 °C by LDH assay. It was found that exposure to tellurite for 90 minutes did not stimulate LDH activity. However, tellurite uptake seems to be more sensitive than the cell viability and LDH activity release tests, as it significantly increases with the increasing of exposure time.

Metallothionein (MT) is known to play an important role in the resistance of tumor cells to cisdiamminedichloroplatinum (II) (CDDP, cisplatin). To identify non-MT factors that play important roles in CDDP resistance, we established CDDP-resistant cell lines from simian virus 40-transformed MT null cells. Subclones of CDDP-resistant MT null cells, designated as MKCr-3, -12, and -18, exhibited 24- to 62-fold resistance to CDDP compared with parental cells. The contents of glutathione (GSH) and the activities of GSH-related enzymes and antioxidant enzymes in MKCr-12 and -18 were higher than those in parental cells. However, MKCr-3 cells did not show any significant increase in the levels of GSH nor in enzyme activities except for superoxide dismutase. Accumulation of platinum in CDDP-resistant subclones was 15-26% of that in parental cells 24 h after administration of CDDP. Eleven other subclones of CDDP-resistant MT null cells also exhibited low accumulation of platinum. These results suggest that the decreased accumulation of CDDP may be a predominant factor in the resistance to CDDP in the absence of MT, an intracellular metal- and free radical-scavenger.

Intestinal flora plays an important role in the decomposition and fecal excretion of methylmercury. The assumed mechanism is that decomposition of organic mercury (o-Hg) to inorganic mercury (i-Hg) by intestinal flora in cecum decreases the reabsorption of mercury in large intestines. To confirm this hypothesis, we examined the large intestinal mercury absorption in vitro from intestinal contents of methylmercury administered mice. Methylmercury (2 mg Hg/kg) was administered intraperitoneally to adult female mice, and the contents of small intestine (ileum) and cecum were taken out 24 hr after the administration. Ratios of organic mercury to total mercury in small intestinal content and cecal content were 86% and 49%, respectively. Contents fo both samall intestine and cecum were packed into cecum and colon of normal mice, respectively, and were incubated in a medium (Tyrode’s solution) at 37°C for 2 hr. 73% of total mercury (t-Hg) was absorbed from small intestinal content into the cecum and medium after the incubation. On the other hand, only 34% of t-Hg was absorbed from cecal content; most i-Hg remained unabsorbed. However, the absorption rate of t-Hg increased to 57% when the cecal content from antibiotics treated mice was used, because of the high percentage (90%) of o-Hg contained. These results suggest that o-Hg in small intestinal and cecal contents can be reabsorbed by cecum and colon in vivo, and that the decomposition of o-Hg to i-Hg by intestinal flora decreases the intestinal reabsorption rate of t-Hg in methylmercury exposed mice.

HeLa cells were stably transformed with plasmid constructs that allowed constitutive expression of antioxidant enzymes such as catalase, glutathione peroxidase (GSH-Px), Cu.Zn-superoxide dismutase (Cu,Zn-SOD) or Mn-superoxide dismutase (Mn-SOD) to examine the involvement of reactive oxygen generation in methylmercury toxicity. Overexpression of catalase, GSH-Px or Cu,Zn-SOD did not affect the sensitivity of HeLa cells against methylmercury. However, the sensitivity of HeLa cells against methylmercury was decreased by overexpression of Mn-SOD, an enzyme localized in matrix of mitochondria and which decomposes superoxide anions. These results suggest that formation of superoxide anions in the mitochondria might be involved in the mechanism of the cytotoxicity of methylmercury.

Because precise information as to the toxicity of vanadium is required for practical use of vanadium compounds as antidiabetic drugs, we examined vanadium toxicity in mice fed normal diet or high-fat diet (C57BL/6N, male, 7 weeks) by oral administration of ammonium metavanadate (AMV) with a maximum dose of 20 mgV/kg/day. Marked lipid accumulation in hepatocytes, renal epithelial cells, and mucosal epithelial cells of the small and large intestines and severe degeneration, necrosis, and loss of mucosal epithelial cells in the small intestine were observed. These pathological changes were more severe in mice fed high-fat diet than mice fed normal diet, and the intensity of the changes increased with increase in the administered dose of AMV. By electron microscopy, the number and size of lipid droplets in hepatocytes were increased. In the small intestine, a TUNEL assay showed a decreased number of positive cells, and positive cells for acrolein immunohistochemistry were observed specifically in the mucosal epithelial cells indicating degeneration and necrosis in the AMV-treated group, suggesting that a possible factor responsible for cell necrosis in the small intestine could be oxidative stress. In conclusion, AMV may impair cellular lipid metabolism, resulting in lipid accumulation, and induce mucosal epithelial cell necrosis in the small intestine.

The purpose of this study was to investigate a possible translocation pathway of intratracheally instilled gold nanoparticles after the induction of acute pulmonary injury by Asian sand dust. ICR mice were intratracheally instilled with 800 μg Asian sand particles (CJ-2 particles) 24 h before instillation of 50-nm gold nanoparticles. Lungs from mice treated with Asian sand particles and gold nanoparticles showed an acute focal inflammation with an increased expression of proinflammatory cytokines (IL-6 and TNF-α) and oxidative stress markers (Cu/Zn SOD and iNOS) in alveolar macrophages, type I alveolar epithelial cells, and endothelial cells at the alveolar walls. Electron microscopy revealed a destruction of the alveolar walls with an increased number of endocytic vesicles in the cytoplasm of both type I epithelial cells and endothelial cells; gold nanoparticles were demonstrated in these endocytic vesicles. These findings suggest that translocation of the exposed nanoparticles may be enhanced in the lung tissues with acute inflammatory changes.

Mechanisms of selenite cytotoxicity were examined using isolated rat hepatocytes. When selenite was added to a suspension of rat hepatocytes, intracellular reduced glutathione (GSH) was decreased and the oxygen consumption rate was increased. Subsequently, thiobarbituric acid-reactive substances (TBA-RS) and lactate dehydrogenase (LDH) leakage were increased. A ferric iron chelator, desferrioxamine (DF), and a synthetic superoxide dismutase (SOD) mimic, desferrioxamine manganese (DFMn), reduced the selenite toxicity. These results suggest that superoxide anion and its reactive metabolites such as the hydroxyl radical may be involved in the cytotoxicity of selenite.

Aims In order to evaluate the role of metallothionein (MT)-III in cadmium (Cd)-induced testicular toxicity, we examined the sensitivity of MT-III null mice to severe testicular injury caused by Cd. Main methods Male MT-III null mice, MT-I/II null mice and wild-type mice were given a subcutaneous injection of CdCl2 (15 μmol/kg). The testis was collected from each mouse at 6, 12 and 24 h after Cd administration. Key findings Testicular hemorrhages by evaluating morphology, hemoglobin content and histological parameters in the 3 types of mice were elevated by Cd injection in a time-dependent manner. The degree of hemorrhage in Cd-injected MT-I/II null mice was similar to that in the wild-type mice. In contrast, hemorrhage in the MT-III null mice was attenuated compared with that in wild-type mice and MT-I/II null mice. Cd levels, MT-I and MT-II mRNA levels and Cd-binding molecules in the testis were similar between MT-III null mice and wild-type mice. In microarray analysis, high expression of purine-nucleoside phosphorylase 2 (Pnp2), retinal degeneration 3 (Rd3), and cadherin-like 24 (Cdh24) was revealed in the testis of MT-III null mice under normal or Cd-treated conditions. Significance MT-III null mice were found to show attenuation of Cd-induced severe testicular toxicity. These results suggest the lack of MT-III contributes to protection of testis from Cd. In addition, regulation of Pnp2, Rd3, and Cdh24 mRNA levels may involve the sensitivity of MT-III null mice to Cd.

Intestinal flora plays important roles in the decomposition and excretion of organomercurial methylmercury, and these roles in decomposition and excretion of organomercurial phenylmercury were examined in mice given antibiotics orally. Female ICR mice were given antibiotic neomycin and chloramphenicol in drinking water for 2 d before phenylmercury administration in order to decrease intestinal flora, and the antibiotics were given throughout the experiment. Phenylmercuric acetate (2mg Hg/kg body weight) was administered to mice intraperitoneally, and feces and urine were collected daily for 4 d. Mice were sacrificed 5 d after phenylmercury administration. There were no differences between the control and the antibiotic-treated mice in the percentage of inorganic mercury to total mercury in feces, urine, liver or kidney. Total mercury excreted in feces and urine did not differ between the antibiotic-treated mice and the control mice. These results suggest that intestinal flora does not play a role in the decomposition and excretion of phenylmercury in mice.

Metallothionein (MT) is a cysteine-rich protein that binds to and is inducible by heavy metals such as cadmium and zinc. However, the precise mechanism of MT induction by other metals remains unclear. In the present study, we investigated the mechanism of MT induction by manganese, focusing on the involvement of cytokine production. Administration of MnCl 2 to mice resulted in the induction of MT dose-dependently in the liver with little accumulation of manganese. Speciation analysis of metals in the liver cytosol showed that the major metal bound to the induced MT was zinc. Administration of MnCl 2 caused an increase in mRNA levels of interleukin-6 (IL-6) in the liver as well as an increase in serum levels of IL-6 but not those of other inflammatory cytokines. Subsequently, serum levels of serum amyloid A (SAA), an acute-phase protein induced by IL-6, increased with a peak at 24 h. However, no increase in serum alanine aminotransferase activity was observed, suggesting that manganese enhanced the production of IL-6 and SAA without causing liver injury. In response to IL-6, the expression of a zinc transporter, ZIP14, was enhanced in the liver, possibly contributing to the synthesis of hepatic zinc-MT. In IL-6-null mice, the induction of hepatic MT by treatment with MnCl 2 was completely suppressed to the control level. These results suggest that manganese is a unique metal that induces the synthesis of hepatic MT completely depending on the production of IL-6 without accompanying liver injury.

Metallothionein (MT) is a low-molecular-weight cysteine-rich protein which has a high affinity for metals. The synthesis of MT is induced by heavy metals such as cadmium and zinc. However, little is known about the induction of MT by tetravalent or pentavalent metals. We investigated the induction of MT synthesis by a pentavalent vanadium compound in mice. Hepatic MT concentrations were increased by subcutaneous injection of ammonium metavanadate (AMV) dose-dependently, and to the similar levels as those induced by zinc chloride. However, accumulation of vanadium in the liver was very low, while high concentrations of vanadium were detected in the kidney. High performance liquid chromatography/inductively coupled argon plasma-mass spectrometry (HPLC/ICP-MS) chromatogram of the liver cytosol of AMV-treated mice revealed that the major metal bound to MT was not vanadium, but zinc. The chromatogram of the liver cytosol of MT null mice demonstrated the existence of a low-molecular-weight vanadium-binding protein that is different from MT. A time-course study showed that concentrations of serum interleukin-6 (IL-6) and serum amyloid A (SAA), an acute-phase protein, increased after the AMV injection. To confirm the involvement of IL-6 in MT induction by AMV administration, IL-6 null and wild-type mice were injected with AMV. In IL-6 null mice, hepatic MT induction by AMV administration decreased significantly to about a half of wild-type mice. These data suggest that both IL-6-dependent and -independent mechanisms are involved in MT induction by vanadium compounds in mice.

Metallothionein (MT) is a small sulfydryl-rich protein that binds to and is inducible by heavy metals such as mercury, cadmium, zinc, and copper. However, little is known about the induction of MT by trivalent metals except for bismuth. In this study, we examined the induction of MT synthesis by cerium, a trivalent lanthanoid metal. Administration of cerium chloride (CeCl3) to mice resulted in accumulation of cerium and induction of MT in the liver in a dose-dependent manner. Distribution profiles of metals in the soluble fraction of the liver of CeCl3-treated mice analyzed by high performance liquid chromatography/inductively coupled argon plasma-mass spectrometry (HPLC/ICP-MS) demonstrated that the metal bound to MT-I and MT-II was zinc, but not cerium. Administration of CeCl3 caused increases in the activities of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and the levels of serum amyloid A (SAA), an acute phase protein. Among inflammatory cytokines examined, interleukin 6 (IL-6) exhibited a marked increase in the serum at 3 h after the CeCl3 administration. In order to evaluate the involvement of IL-6 in the induction of MT by cerium, we examined MT induction by CeCl3 in IL-6 null mice. Both the induction of hepatic MT and the increases in SAA levels were markedly suppressed in IL-6 null mice. These results suggest that IL-6 plays an important role in the induction of hepatic MT by cerium.

Glutathione-S-transferase class Omega (GSTO 1-1) belongs to a new subfamily of GSTs, which is identical with human monomethylarsonic acid (MMA(V)) reductase, the rate limiting enzyme for biotransformation of inorganic arsenic, environmental carcinogen. Recombinant GSTO 1-1 variants (Ala140Asp and Thr217Asn) were functionally characterized using representative substrates. No significant difference was observed in GST activity towards 1-chloro-2,4-dinitrobenzene, whereas thioltransferase activity was decreased to 75% (Ala140Asp) and 40% (Thr217Asn) of the wild-type GSTO 1-1. For MMA(V) reductase activity, the Ala140Asp variant exhibited similar kinetics to wild type, while the Thr217Asn variant had lower Vmax (56%) and Km (64%) values than the wild-type enzyme. The different activities of the enzyme variants may influence both the intracellular thiol status and arsenic biotransformation. This can help explain the variation between individuals in their susceptibility to oxidative stress and inorganic arsenic.

We investigated the relationship between active oxygen species (AOS) generation and cultured vascular endothelial cellular damage caused by simultaneous exposure to selenium compounds and sulfhydryl compounds such as cysteine (Cys) or reduced glutathione (GSH). Selenium compounds, selenite, selenate or selenomethionine (SeMet), are added to total parenteral nutrition (TPN) and intravenously administered. We confirmed by luminol dependent chemiluminescence, an indicator of AOS generation, that selenite generates AOS in the presence of clinical concentrations of sulfhydryl compounds, 0.5 mM Cys or 0.5 mM GSH, and that the amount of AOS generated reaches the maximum when their mole ratio is 1:50. However, AOS generation was not observed after simultaneous administration of various concentrations of selenate or SeMet with sulfhydryl compounds. Moreover, simultaneous exposure to 10 microM selenite and sulfhydryl compounds was found to result in significant increases in the [3H]-adenine and lactate dehydrogenase (LDH) release rates from cells, a significant decrease in the amount of cellular protein, and enhancement of cellular damage as compared with after exposure to selenite alone. However, simultaneous exposure to 10 microM selenate or 10 microM SeMet together with sulfhydryl compounds did not induce cellular damage. These findings revealed that selenite generates AOS and causes cellular damage in the presence of sulfhydryl compounds. Accordingly, it seems better to choose selenate or SeMet instead of selenite when a selenium compound is to be added to TPN.

The overexpression of catalase or Cu,Zn-superoxide dismutase (Cu,Zn-SOD) did not affect the sensitivity of HeLa cells to cis-platinum. However, the cytotoxicity of cis-platinum was depressed significantly by the simultaneous overexpression of catalase and Cu,Zn-SOD. We concluded that cis-platinum accelerated the generation of superoxide anion in the cells, and the superoxide anion produced was converted into H2O by the cooperative roles of catalase and Cu,Zn-SOD.

A study was carded out in the Nathenje area in order to determine fluoride concentrations in groundwater and to investigate the occurrence of dental fluorosis in school children. From a fluoride distribution map, it was observed that the central part of Nathenje had high fluoride concentration of between 2 mg/L and 7.02 mg/L. The southern and western parts had less than 1 mg/L. About 52% of the groundwater supplies had fluoride concentrations are above the Word Health Organization maximum permissible limit of 1.5 mg/L. Fluoride concentrations for the rainy season varied from

Increased lipid peroxidation caused by selenite treatment was observed in vivo (Dougherty and Hoekstra 1982) and in vitro (Bunyan et al. 1960; Stacey and Klaassen 1981; Seko 1986). In vitro treatment of cells with selenite resulted in the decreased content of reduced glutathione and NADPH (Tsen and Collier 1960; Anundi et al. 1984), which are important in protecting cells against oxidation. However, the decrease in GSH concentration did not always relate to cell damage (Tsen and Collier 1960; Seko 1986) or lipid peroxidation (Seko 1986) in erythrocyte suspension. On the other hand, the importance of GSH (Young et al. 1981) or reactive sulfhydryls of hemoglobin (Seko 1986) have been considered to play an important role in selenite induced in vitro hemolysis. In order to estimate the relationship between GSH and the selenite-induced lipid peroxidation, we have examined the active oxygen generation in the mixture of selenite and GSH by using luminol- or lucigenin-dependent chemiluminescence (CL) as an indicator.