Thyroid Stem Cells But Not Differentiated Thyrocytes Are Sensitive to Slightly Increased Concentrations of Heavy Metals.

Thyroid cancer incidence is markedly increased in volcanic areas where residents are biocontaminated by chronic lifelong exposure to slightly increased metals in the environment. Metals can influence the biology of living cells by a variety of mechanisms, depending not only on the dose and length of exposure but also on the type and stage of differentiation of target cells. We explored the effect of five heavy metals (Cu, Hg, Pd, W and Zn) at nanomolar concentrations (the biocontamination level in residents of the volcanic area in Sicily where thyroid cancer is increased) on stimulating the proliferation of undifferentiated (thyrospheres) and differentiated human thyroid cells. Thyrosphere proliferation was significantly increased after exposure to each individual metal and a greater stimulating effect was observed when a mixture of the examined metals was used. No effect was seen in differentiated thyrocytes. For all metals, the dose-response curve followed a biphasic pattern that is typical of hormesis. Thyrosphere growth concerned the size rather than number, except with the metal mixture. An altered morphology was also observed in metal-treated thyrospheres. Metal-induced proliferation was due to activation of the ERK1/2 pathway, as confirmed by growth inhibition when ERK1/2 signaling was blocked. These studies show that stem/precursor thyroid cells are sensitive to small increases in environmental metal concentrations that are harmless for differentiated thyrocytes.

Trimetazidine Protects from Mercury-Induced Kidney Injury.

INTRODUCTION: The presence of mercury in the environment is a worldwide concern. Inorganic mercury is present in industrial materials, is employed in medical devices, is widely used in batteries, is a component of fluorescent light bulbs, and it has been associated with human poisoning in gold mining areas. The nephrotoxicity induced by inorganic mercury is a relevant health problem mainly in developing countries. The primary mechanism of mercury toxicity is oxidative stress. Trimetazidine (TMZ) is an anti-ischemic drug, which inhibits cellular oxidative stress, eliminates oxygen-free radicals, and improves lipid metabolism. The aim of this study was to evaluate whether the administration of TMZ protects against mercuric chloride (HgCl2) kidney damage. METHODS: Adult male Wistar rats received only HgCl2 (4 mg/kg bw, sc) (Hg group, n = 5) or TMZ (3 mg/kg bw, ip) 30 min before HgCl2 administration (4 mg/kg bw, sc) (TMZHg group, n = 7). Simultaneously, a control group of rats (n = 4) was studied. After 4 days of HgCl2 injection, urinary flow, urea and creatinine (Cr) plasma levels, Cr clearance, urinary glucose, and sodium-dicarboxylate cotransporter 1 (NaDC1) in urine were determined. Lipid peroxidation (MDA) and glutathione (GSH) levels were measured in kidney homogenates. RESULTS: Rats only treated with HgCl2 showed an increase in urea and Cr plasma levels, urinary flow, fractional excretion of water, glucosuria, and NaDC1 urinary excretion as compared with the control group and a decrease in Cr clearance. TMZHg group showed a decrease in urea and Cr plasma levels, urinary flow, fractional excretion of water, glucosuria, NaDC1 urinary excretion, and an increase in Cr clearance when compared to the Hg group. Moreover, MDA and GSH levels observed in Hg groups were decreased and increased, respectively, by TMZ pretreatment. CONCLUSION: TMZ exerted a renoprotective action against HgCl2-induced renal injury, which might be mediated by the reduction of oxidative stress. Considering the absence of toxicity of TMZ, its clinical application against oxidative damage due to HgCl2-induced renal injury should be considered. The fact that TMZ is commercially available should simplify and accelerate the translation of the present data "from bench to bedside." In this context, TMZ become an interesting new example of drug repurposing.

Leaf ethanolic extract of Etlingera hemesphaerica Blume mitigates defects in fetal anatomy and endochondral ossification due to mercuric chloride during the post-implantation period in Mus musculus.

This study aimed to investigate the effectiveness of leaf ethanolic extract of Etlingera hemisphaerica (LE3H) in reducing defects in fetal anatomy and endochondral ossification in mice induced by HgCl2 during the post-implantation period. Pregnant mice were divided into four groups, each consisting of 10 dams, and received drink and food ad libitum. The first group was administered LE3H (E1), the second one HgCl2 (E2), the third one HgCl2+LE3H (E3), and the fourth was control (E0), administered double-distilled water only. HgCl2 (5 mg/kg bw) was administrated by injection intraperitoneally on gestation day (GD)9 and LE3H (0.39 mg/g bw) was administered by gavage on GD10. The treated and control animals were killed by cervical dislocation on GD18, dissected, and the morphologically normal living fetuses (MNLF) were collected. The MNLF of E0, E1, E2, and E3 from 5 dams were fixed with Bouin solution, and observed using the free hand razor blade technique for soft tissue examination. The remaining MNLF were fixed with 96% ethanol, and then stained with Alizarin Red S and Alcian Blue for ossification examination. Index of length of ossified part (ILOP) of humerus, index of width of ossified part (IWOP) of humerus, ILOP of femur, and IWOP of femur were calculated. E2 had higher cases of anatomical defects (74,6%) than E3 (48.9%), E1 (15.0%), and E0 (0%). E2 had humerus IWOP of 0.82±0.03, which was significantly lower than that of E0 (0.89±0.04) and E1 (0.89±0.03), while that of E1 and E0 was not significantly different from each other. Meanwhile, IWOP in E3 (0.88±0.03) was significantly higher than that in E2, but not different from that in E1 and E0. Thus, LE3H mitigated defects in fetal anatomy and endochondral ossification induced by HgCl2 in mice.

Mercury (Hg2+) interferes with physiological adaptations to freezing in the arctic earthworm Enchytraeus albidus.

Freezing temperatures is an important stressor in the arctic regions and has a significant influence on the population dynamics and geographic distribution of terrestrial invertebrates. Toxic metals in the environment can interfere with protective cold-acclimation responses of organisms. It is therefore important to evaluate the combined effects of cold stress and environmental contaminants. Here, we aimed to investigate the effects of Hg (HgCl2) on various physiological aspects of freeze-tolerance in the earthworm (Enchytraeus albidus). We measured the levels of the cryoprotectant glucose, the glycogen content (source of glucose molecules for cryoprotection and fuel for metabolism), and changes in the composition of membrane phospholipid fatty acids (PLFA) as an indicator of lipid peroxidation. Freezing at -6 °C had no effect on survival in uncontaminated soil, however, survival of freezing in Hg contaminated soil was clearly reduced, especially at extended exposure times. Thus, the LC50 value in frozen soil decreased from 8.3 mg Hg kg-1 (when exposed for 17 days) to only 4.2 mg Hg kg-1 after 36 days' exposure indicating that combined effects of Hg and freezing became larger at prolonged exposure times. Hg caused a depletion of glycogen reserves (almost 50% at 12 mg kg-1 dry soil), but despite this effect worms were able to maintain a constant cryoprotectant level (about 0.12 mg glucose mg-1 dry weight) at all Hg concentrations. Hg had clear negative effects on the proportion of unsaturated PLFAs, which could be an indication of lipid peroxidation. Since a high proportion of unsaturated fatty acids in the membrane is important for invertebrate freeze-tolerance, our results suggest that the negative effect of Hg on freeze-tolerance in E. albidus is related to degraded membrane functionality at low temperature.

Role of α-tocopherol and Lactobacillus plantarum in the alleviation of mercuric chloride-induced testicular atrophy in rat's model: Implication of molecular mechanisms.

The present work was aimed to evaluate the protective effects of alpha-tocopherol (α-toco) and/or Lactobacillus plantarum (LCB) against testicular atrophy induced by mercuric chloride (MCH). Rats were injected with 5 mg/kg MCH for 5 days consecutively, then treated with 100 mg/kg α-toco and 6 × 1010 CFU 1.8701/kg LCB alone or together for 3 weeks. The MCH elevated serum TNF-α, IL- 6, caspase-3, and testicular malondialdehyde. However, serum testosterone, dehydroepiandrosterone, testicular messenger RNA of a steroidogenic acute regulatory protein, 17-ß-hydroxysteroid dehydrogenase, 3ß-hydroxysteroid dehydrogenase, glutathione level, and superoxide dismutase activity were decreased. Protein expression of Nrf2 was downregulated whereas that of Bax and DNA fragmentation was upregulated in the testicular tissues. Treatment with α-toco and LCB ameliorated the deviated biochemical parameters and improved tissue injury. It was concluded that the combination of LCB and α-toco achieved promising results in the amelioration of MCH-induced testicular atrophy. Nrf2, Bax expressions, and DNA fragmentation are involved in the testicular atrophy induced by MCH.

The chemical speciation, spatial distribution and toxicity of mercury from Tibetan medicine Zuotai，ß-HgS and HgCl2 in mouse kidney.

Zuotai, a famous Tibetan medicinal mixture containing ß-HgS, has been used to combine with herbal remedies for treating diseases for more than 1 300 years. The target organ for inorganic mercury toxicity is generally considered to be the kidney. Therefore, it is crucial to reveal the chemical speciation, spatial distribution and potential nephrotoxicity of mercury from Zuotai in kidney. To date, this remains poorly understood. We used X-ray absorption spectroscopy (XAS) and micro X-ray fluorescence (µ-XRF) imaging based on synchrotron radiation to study mercury chemical forms and mercury special distribution in kidney after mice were treated orally with Zuotai, ß-HgS or HgCl2. Meanwhile, the histopathology of kidney was observed. Mice exposed with Zuotai showed kidney with significant proportion of mercury ions bound to sulfydryl biomolecules (e.g. Cys-S-Hg-S-Cys) plus some of unknown species, but without methylmercury cysteine, which is the same as ß-HgS and HgCl2. The mercury is mainly deposited in renal cortex in mouse treated with Zuotai, ß-HgS or HgCl2, but with a low level of mercury in medulla. The total mercury in kidney of mice treated with HgCl2 was much higher than that of ß-HgS, and the later was higher than that of Zuotai. And, HgCl2 cause severe impairments in mouse kidney, but that was not observed in the Zuotai and ß-HgS groups. Meanwhile, the bio-metals (Ca, Zn, Fe and Cu) micro-distributions in kidney were also revealed. These findings elucidated the chemical nature, spatial distribution and toxicity difference of mercury from Zuotai, ß-HgS and HgCl2 in mouse kidney, and provide new insights into the appropriate methods for biological monitoring.

Chronic mercury exposure at different concentrations produces opposed vascular responses in rat aorta.

Mercury chloride exposure for 30 days decreases NO bioavailability and increases oxidative stress. However, the mechanisms underlying the effects of mercury on the cardiovascular system are not completely understood, and it is not known if they are dose-dependent or if some concentrations have no harmful effects. Thus, we investigated the effects of chronic exposure to doses low (half) and high (2.5-fold higher) than that needed to obtain 29 nmol/L of HgCl2 on the vascular function. Three-month-old male Wistar rats received intramuscular (i.m.) HgCl2 for 30 days and were divided in three groups: lower (Low Hg); higher (High Hg); and saline was used as the control. High Hg exposure increased the contractile response to phenylephrine (PHE) in aortic rings, but Low Hg reduced it. The hyporesponsiveness in the Low Hg rats was blunted by endothelial denudation and NOS inhibition with l-NAME (100 µmol/L). The phosphorylated-eNOS/eNOS protein ratio increased in the aortas of Low Hg rats. In the High Hg group, endothelial denudation increased the PHE-induced contractions, while l-NAME had no effects and indomethacin (10 µmol/L), losartan (10 µmol/L) and apocynin (30 µmol/L) reduced this response. In the High Hg group, protein levels of the NADPH oxidase subunit gp91phox and cyclooxygenase-2 increased. Our results support previous suggestions that High Hg increases oxidative stress that might activate an inflammatory cascade and the renin-angiotensin system. However, very low Hg concentrations below the level considered safe still reduced vascular reactivity, suggesting the need for special attention to continuous exposure as a putative cause of increased cardiovascular risk.

Epidermal growth factor attenuates tubular necrosis following mercuric chloride damage by regeneration of indigenous, not bone marrow-derived cells.

To assess effects of epidermal growth factor (EGF) and pegylated granulocyte colony-stimulating factor (P-GCSF; pegfilgrastim) administration on the cellular origin of renal tubular epithelium regenerating after acute kidney injury initiated by mercuric chloride (HgCl2 ). Female mice were irradiated and male whole bone marrow (BM) was transplanted into them. Six weeks later recipient mice were assigned to one of eight groups: control, P-GCSF+, EGF+, P-GCSF+EGF+, HgCl2 , HgCl2 +P-GCSF+, HgCl2 +EGF+ and HgCl2 +P-GCSF+EGF+. Following HgCl2 , injection tubular injury scores increased and serum urea nitrogen levels reached uraemia after 3 days, but EGF-treated groups were resistant to this acute kidney injury. A four-in-one analytical technique for identification of cellular origin, tubular phenotype, basement membrane and S-phase status revealed that BM contributed 1% of proximal tubular epithelium in undamaged kidneys and 3% after HgCl2 damage, with no effects of exogenous EGF or P-GCSF. Only 0.5% proximal tubular cells were seen in S-phase in the undamaged group kidneys; this increased to 7-8% after HgCl2 damage and to 15% after addition of EGF. Most of the regenerating tubular epithelium originated from the indigenous pool. BM contributed up to 6.6% of the proximal tubular cells in S-phase after HgCl2 damage, but only to 3.3% after additional EGF. EGF administration attenuated tubular necrosis following HgCl2 damage, and the major cause of this protective effect was division of indigenous cells, whereas BM-derived cells were less responsive. P-GCSF did not influence damage or regeneration.

Effects of mercury chloride (HgCl2) on betta splendens aggressive display

Mercury chloride (HgCl2) is a toxic mercury salt and a major pollutant, that can be found in soil, water and air, with influences on behavior, physiology and adaptation to the environment. In this study two experiments were designed to examine interactions and effects of HgCl2 on some behavioral patterns of Siamese fighting fish (Betta splendens). In the first experiment we tested the effect of a progressive dose (five 0.04 mg) on aggressive display with exposure to a mirror, whereas in the second experiment we tested the effect of an acute dose (0.2 mg) on the aggressive display with exposure to a mirror. The experiments were performed on 5 consecutive sessions at intervals of 18 hours between sessions. Differences of performance were shown by subjects in the acute and progressive treatments when compared with a control treatment in the majority of behaviors evaluated, namely Floating, Slow Swimming, Wavy Swimming, Emerging, Bend, Square Move and Motor Display Components. Acute treatment was different from control only on Show Body, while the progressive group differed on Resting, Horizontal Display and Appropriate Display Components. Differences between Correlate Display Components and Total were also shown. Both the acute and progressive contamination with HgCl2 decrease the motor activity in the aggressive display, mirror-image test of Betta splendens, mainly on the progressive dose. This implies an impairment on feeding behavior, predator avoidance, reproductive behavior, mate choice and territoriality. These results suggest that in this fish species, the progressive dose has a greater effect on behavior in general and that both the acute and progressive contamination with mercury chloride affect many other aspects of behavior (AU)

El cloruro de mercurio (HgCl2) es una sal de mercurio tóxica y un contaminante importante, que se puede encontrar en el suelo, agua y aire, y que influye en el comportamiento, la fisiología y la adaptación al medio ambiente. En este estudio, dos experimentos fueron diseñados para examinar las interacciones y los efectos del HgCl2 en algunos patrones de comportamiento de peces luchadores siameses (Betta splendens). En el primer experimento se evaluó el efecto de una dosis progresiva (cinco 0,04 mg) en la exhibición agresiva con exposición a un espejo, mientras que en el segundo experimento se evaluó el efecto de una dosis aguda (0,2 mg) en la exhibición agresiva con exposición a un espejo. Los experimentos se realizaron en 5 sesiones consecutivas a intervalos de 18 horas entre sesiones. Se muestran diferencias de rendimiento por los sujetos en los tratamientos agudo y progresivas en comparación con un tratamiento de control en la mayoría de las conductas evaluadas, es decir, Flotación, Nado lento, Nado ondulado, Emergente, Doblado, Movimiento cuadrado y componentes de exhibición motora. El tratamiento agudo difiere del control sólo en Mostrar cuerpo, mientras que el grupo progresivo difiere en Reposo, Exhibición horizontal y en Componentes adecuados de exhibición. También se muestran las diferencias entre Correlación entre los componentes de exhibición y Total. Tanto la contaminación aguda como progresiva con HgCl2 disminuye la actividad motora en la exhibición agresiva en la prueba de imagen-espejo de Betta splendens, principalmente de la dosis progresiva. Esto implica un deterioro en el comportamiento de alimentación, de evitación a los depredadores, en el comportamiento reproductivo, la elección de pareja y la territorialidad. Estos resultados sugieren que en esta especie de pez, la dosis progresiva tiene un efecto mayor en el comportamiento en general, y que tanto la contaminación aguda como la progresiva con cloruro de mercurio afecta a muchos otros aspectos del comportamiento (AU)

Hematotoxicity and genotoxicity of mercuric chloride following subchronic exposure through drinking water in male rats.

Erythrocytes are a convenient model to understand the subsequent oxidative deterioration of biological macromolecules in metal toxicities. The present study examined the variation of hematoxic and genotoxic parameters following subchronic exposure of mercuric chloride via drinking water and their possible association with oxidative stress. Male rats were exposed to 50 ppm (HG1) and 100 ppm (HG2) of mercuric chloride daily for 90 days. A significant dose-dependent decrease was observed in red blood cell count, hemoglobin, hematocrit, and mean cell hemoglobin concentration in treated groups (HG1 and HG2) compared with controls. A significant dose-dependent increase was observed in lipid peroxidation; therefore, a significant variation was found in the antioxidant enzyme activities, such as superoxide dismutase, catalase, and glutathione peroxidase. Interestingly, mercuric chloride treatment showed a significant dose-dependent increase in frequency of total chromosomal aberration and in percentage of aberrant bone marrow metaphase of treated groups (p < 0.01). The oxidative stress induced by mercury treatment may be the major cause for chromosomal aberration as free radicals lead to DNA damage. These data will be useful in screening the antioxidant activities of natural products, which may be specific to the bone marrow tissue.

Trend of contact allergy to cosmetic ingredients in Thais over a period of 10 years.

BACKGROUND: Contact allergy to cosmetic ingredients is common. However, there are no recent comprehensive studies on contact allergy to cosmetic ingredients in Asia. OBJECTIVES: To identify positive patch test reactions in patients tested at Siriraj Hospital, Bangkok, Thailand to allergens present in cosmetics. METHODS: A retrospective review of medical records from the outpatient contact dermatitis clinic was conducted from January 1999 to December 2008. Patients with at least one positive patch test reaction to allergens associated with cosmetic ingredients were studied. The results were evaluated using Pearson's χ(2) -test with Yates' continuity correction or Fisher's exact test where appropriate,and a p-value <0.002 was considered to be statistically significant by Bonferroni correction. RESULTS: There were 1247 cases (239 males and 1008 females; mean age 38.5 years). Fragrance chemicals and preservatives were the most commonly recognized cosmetic allergens. Ammoniated mercury was the only allergen that showed a significantly increased frequency over the 10-year period (p = 0.0008). CONCLUSIONS: Our study showed that ammoniated mercury is an emerging cosmetic allergen, showing an increased prevalence in recent years in Thailand. A focus is required on emerging cosmetic allergens and what may account for the upward trend of cosmetic contact dermatitis.

Deaths related to chemical burns.

The authors present a series of 6 deaths due to the uncommon cause of chemical burns. Of the 6 deaths due to chemical burns, 4 deaths were due to ingestion of a chemical, 1 death was caused by chemical burns of the skin, and 1 death resulted from rectal insufflation of a chemical. Seven additional cases where chemical burns may have been a contributing factor to the death or an incidental finding are also presented. Four cases are related to an incident involving chemical exposure during an industrial explosion. Three cases involve motor fuel burns of the skin. Two cases concern a plane crash incident, and 1 case involved a vehicular collision. Cases are derived from the records of the Dallas County Medical Examiner's Office and those of the authors' consultation practices. Each of the cases is presented, followed by a discussion of the various mechanisms of chemical injury.

Deletion of multispecific organic anion transporter Oat1/Slc22a6 protects against mercury-induced kidney injury.

The primary site of mercury-induced injury is the kidney due to uptake of the reactive Hg(2+)-conjugated organic anions in the proximal tubule. Here, we investigated the in vivo role of Oat1 (organic anion transporter 1; originally NKT (Lopez-Nieto, C. E., You, G., Bush, K. T., Barros, E. J., Beier, D. R., and Nigam, S. K. (1997) J. Biol. Chem. 272, 6471-6478)) in handling of known nephrotoxic doses of HgCl(2). Oat1 (Slc22a6) is a multispecific organic anion drug transporter that is expressed on the basolateral aspects of renal proximal tubule cells and that mediates the initial steps of elimination of a broad range of endogenous metabolites and commonly prescribed pharmaceuticals. Mercury-induced nephrotoxicity was observed in a wild-type model. We then used the Oat1 knock-out to determine in vivo whether the renal injury effects of mercury are mediated by Oat1. Most of the renal injury (both histologically and biochemically as measured by blood urea nitrogen and creatinine) was abolished following HgCl(2) treatment of Oat1 knock-outs. Thus, acute kidney injury by HgCl(2) was found to be mediated mainly by Oat1. Our findings raise the possibility that pharmacological modulation of the expression and/or function of Oat1 might be an effective therapeutic strategy for reducing renal injury by mercury. This is one of the most striking phenotypes so far identified in the Oat1 knock-out. (Eraly, S. A., Vallon, V., Vaughn, D. A., Gangoiti, J. A., Richter, K., Nagle, M., Monte, J. C., Rieg, T., Truong, D. M., Long, J. M., Barshop, B. A., Kaler, G., and Nigam, S. K. (2006) J. Biol. Chem. 281, 5072-5083).

Th1/Th2 balance in mouse delayed-type hypersensitivity model with mercuric chloride via skin and oral mucosa.

In order to compare delayed-type hypersensitivity (DTH) among different exposure sites, we evaluated the sensitization potency of mercuric chloride (HgCl(2)) via exposure to the skin, or oral or esophageal mucosa using the mouse ear swelling test. Furthermore, we investigated in vitro splenocyte proliferation reaction and cytokine profile in HgCl(2)-exposed and control mice. Sensitization with HgCl(2) was established via the skin and oral mucosa but not via the esophageal mucosa. The splenocyte proliferation reaction was significantly enhanced to a similar degree in skin and oral mucosa-sensitized mice compared with in the control mice. IL-10 levels from cultured splenocytes were significantly increased in skin and oral mucosa-sensitized mice compared with those in control mice, whilst IFN-γ significantly increased only in splenocytes from skin-sensitized mice. These results suggest that exposure of the skin or oral mucosa to HgCl(2) can induce DTH, but that Th1/Th2 balance differs according to the site of antigen exposure.

Prevalence of contact allergy at a dermatology clinic in China from 1990-2009.

BACKGROUND: The prevalence of contact allergy varies in different regions and populations. OBJECTIVE: To describe the frequency of sensitization in patients with dermatitis or eczema referred to Peking University First Hospital and analyze the trends in the prevalence of common allergens from January 1, 1990, to December 31, 2009. METHODS: A total of 1,858 patients were patch tested with the Chinese baseline series of contact allergens. Data were collected from retrospective charts and analyzed. RESULTS: Positive reactions to one or more allergens were shown in 1,374 patients (74.0%). The most common sensitizers were nickel sulfate (25.7%), fragrance mix I (25.6%), thiuram mix (25.5%), ammoniated mercury (20.5%), and p-phenylenediamine (19.1%). A statistically significant increase of sensitization over the 20-year period was seen for nickel sulfate, fragrance mix, ammoniated mercury, colophony, ethylenediamine, and potassium dichromate. Mercapto mix showed a trend of a statistically significant decrease in sensitizations from 1990 to 2009. CONCLUSIONS: The patterns of contact allergy in patients from Peking University Hospital are different from those of patients in other regions of China, in European countries, and in the United States. Nickel and fragrance mix were the most common allergens, and the sensitization rates of these two allergens had been increasing remarkably during the 20 years from 1990 to 2009.

[Comparative toxicology study of Cinnabar, Zhusha Anshenwan, methylmercury and mercuric chloride].

OBJECTIVE: To study the toxicity of Cinnabar and Cinnabar-containing traditional medicines (Zhusha Anshenwan) comparable to common mercurials. METHOD: The toxicity of methylmercury (MeHg), mercuric chloride (HgCl2), Cinnabar and Zhusha Anshenwan was studied in cultured human liver HL-7702 cells and in mice following acute and subacute exposures. RESULT: The 50% lethal concentrations (LC50) of MeHg, HgCl2, Cinnabar and Zhusha Anshenwan in human liver HL-7702 cells were 4.4, 9.2, 2460, 4050 mg x L(-1), respectively . Oral cinnabar at a dose of 20 g x kg(-1) (clinical dosage 250 times) did not kill mouse, but no mouse could survive MeHg at a dose of 0.1 g x kg(-1) or HgCl2 at a dose of 0. 15 g x kg(-1). Subacute toxicity experiment indicated that HgCl2 retarded body weight gain with significant accumulation of Hg in the liver and kidney. In comparison, mercury accumulation after Cinnabar and Zhusha Anshenwan was insignificant. No apparent hepatic and renal dysfunctions were evident under the experimental conditions, but the metallothionein-2 mRNA levels were much higher in HgCl2 group than in other groups. CONCLUSION: Cinnabar and Zhusha Anshenwan are much less toxic than MeHg and HgCl2.

Mode of cytotoxic action of nephrotoxic agents: oxidative stress and glutathione-dependent enzyme.

OBJECTIVE: To investigate the cytotoxic action of nephrotoxic agents using an in vitro renal cell model, focusing on the cellular oxidative status and a specific glutathione (GSH)-dependent enzyme, glyoxalase I (Gly-I). MATERIALS AND METHODS: Renal proximal tubular LLC-PK(1) cells were exposed to mercuric chloride, glycerol, cisplatin, gentamicin and cyclosporin A, and cell number/viability were determined. Oxidative stress was assessed by lipid peroxidation (LPO) assay, and Gly-I activity was measured by enzymatic method on a spectrophotometer. RESULTS: Both mercuric chloride (30 microm) and glycerol (2.5%) were highly toxic to LLC-PK(1) cells, inducing >90% cell death within 24 h. The remaining agents led to slightly >50% growth inhibition at 72 h. The LPO levels at 3 h in cells exposed to mercuric chloride or glycerol were approximately 2.5 times higher than that in controls. N-acetylcysteine (NAC), a potent antioxidant and precursor for GSH, almost completely (>95%) prevented renal cell death from mercuric chloride or glycerol. Gly-I activity was dependent on NAC and closely associated with cell viability. A approximately 65% loss in Gly-I activity by mercuric chloride/glycerol led to >90% cell death, while restoring a basal activity of Gly-I with NAC was accompanied by complete cell viability. CONCLUSIONS: The cytotoxic action of nephrotoxic agents appears to be triggered by oxidative stress, leading to Gly-I inactivation. As Gly-I plays a key role in cellular detoxification, its inactivation under oxidative stress probably becomes fatal to cells. However, cytoprotection provided with NAC is significant and might have implications in preventing renal cell injury mediated through nephrotoxic agents.

[Immunometabolic activity of fluoroquinolones immobilized into cell carriers in toxic lesion of the kidneys due to staphylococcal infection].

The study of immunomodulating, antioxidant and hepatoprotective activity of some fluoroquinolones (norfloxacin, ofloxacin, levofloxacin) immobilized into erythrocyte and leukocyte carriers was made on Wistar rats with body mass about 150-180 g. It is shown that toxic action on the kidneys of mercury dichloride, especially a combined action of mercury dichloride and staphylococcal infection, raised the levels of urea and creatinine, caused immunosuppression, activated hepatotoxic, cytolytic and oxidative processes, decreased antioxidant and energetic potentials of erythrocytes. Unbound fluoroquinolones intensified the above processes. Introduction of fluoroquinolones immobilized into erythrocyte and leukocyte carriers, respectively, decreased and normalized intensity of lipid peroxidation, cholestasis, cytolysis, improved and normalized immune system functions, antioxidant and energetic potentials of erythrocytes.

Amelioration of mercury-induced autoimmunity by 4-1BB.

In certain strains of mice, subtoxic doses of HgCl2 (mercuric chloride; mercury) induce a complex autoimmune condition characterized by the production of antinucleolar IgG Abs, lymphoproliferation, increased serum levels of IgG1/IgE Abs, and deposition of renal immune complexes. 4-1BB is an important T cell costimulatory molecule that has been implicated in T cell proliferation and cytokine production, especially production of IFN-gamma. To elucidate T cell control mediated by the 4-1BB signaling pathway in this syndrome, we assessed the effect of administering agonistic anti-4-1BB mAb on mercury-induced autoimmunity. Groups of A.SW mice (H-2s) received mercury/control Ig or mercury/anti-4-1BB or PBS alone. Anti-4-1BB mAb treatment resulted in a dramatic reduction of mercury-induced antinucleolar Ab titers, serum IgG1/IgE induction, and renal Ig deposition. These effects may be related to the present finding that anti-4-1BB mAb decreases B cell numbers and function. The anti-4-1BB mAb-treated mercury group also showed a marked reduction in Th2-type cytokines but an increase in Th1-type cytokines and chemokines. Increased IFN-gamma production due to anti-4-1BB mAb treatment appears to be responsible for the observed B cell defects because neutralization of IFN-gamma in vivo substantially restored B cell numbers and partly restored IgG1/IgE. Collectively, our results indicate that 4-1BB mAb can down-regulate mercury-induced autoimmunity by affecting B cell function in an IFN-gamma-dependent manner and thus, preventing the development of autoantibody production and tissue Ig deposition.