Mitochondrial involvement in genetically determined transition metal toxicity II. Copper toxicity

A naphthyl appended ninhydrin based colorimetric chemosensor for Cu2+ ion: Detection of cysteine and ATP

A ninhydrin-based colorimetric chemosensor (LH) was synthesized using 3-hydroxy-2-naphthoic hydrazide and 11H-indeno[1,2-b]quinoxalin-11-one. It was characterized by spectroscopic and single crystal X-ray diffraction techniques. In a semi-aqueous (MeOH/HEPES) system, LH displayed a characteristic chromogenic change from colorless to yellow upon adding Cu2+ ion, with the appearance of a new peak at λmax = 460 nm. A 1:1 binding stoichiometry between LH and Cu2+ ion has been found, with LOD = 2.3 μM (145 ppb) and LOQ = 8 μM (504 ppb). Based on experimental results the formula of [Cu(L)Cl(H2O)2] (1) was assigned and this in-situ generated 1 was found to exhibit a discoloration of upon gradual addition of cysteine (LOD = 60 nM) as well as ATP (LOD = 130 nM) having 1:2 and 1:1 stoichiometry respectively. The LH was useful for recognition of Cu2+ ion in real water samples and on filter paper strips. A two-input-two-output logic gate circuitry was also constructed by employing 1 and cysteine. The DFT/TDDFT calculations performed on LH and 1 were consistent with experimental findings. The binding affinity of LH towards HSA and BSA were determined with HSA having greater affinity than BSA, which was also supported by theoretical calculations.

Adverse effect propensity: A new feature of Gulf War illness predicted by environmental exposures

A third of 1990-1 Gulf-deployed personnel developed drug/chemical-induced multisymptom illness, "Gulf War illness" (GWI). Veterans with GWI (VGWI) report increased drug/exposure adverse effects (AEs). Using previously collected data from a case-control study, we evaluated whether the fraction of exposures that engendered AEs ("AE Propensity") is increased in VGWI (it was); whether AE Propensity is related to self-rated "chemical sensitivity" (it did); and whether specific exposures "predicted" AE Propensity (they did). Pesticides and radiation exposure were significant predictors, with copper significantly "protective"-in the total sample (adjusted for GWI-status) and separately in VGWI and controls, on multivariable regression. Mitochondrial impairment and oxidative stress (OS) underlie AEs from many exposures irrespective of nominal specific mechanism. We hypothesize that mitochondrial toxicity and interrelated OS from pesticides and radiation position people on the steep part of the curve of mitochondrial impairment and OS versus symptom/biological disruption, amplifying impact of new exposures. Copper, meanwhile, is involved in critical OS detoxification processes.

How heavy metal stress affects the growth and development of pulse crops: insights into germination and physiological processes

The current work is an extensive review addressing the effects of heavy metals in major pulse crops such as Chickpea (Cicer arietinum L.), Pea (Pisum sativum L.), Pigeonpea (Cajanus cajan L.), Mung bean (Vigna radiata L.), Black gram (Vigna mungo L.) and Lentil (Lens culinaris Medik.). Pulses are important contributors to the global food supply in the world, due to their vast beneficial properties in providing protein, nutritional value and health benefits to the human population. Several studies have reported that heavy metals are injurious to plants causing inhibition in plant germination, a decrease in the root and shoot length, reduction in respiration rate and photosynthesis. Properly disposing of heavy metal wastes has become an increasingly difficult task to solve in developed countries. Heavy metals pose one of the substantial constraints to pulse crops growth and productivity even at low concentrations. This article attempts to present the morphological, biochemical and various physiological changes induced on the pulse crops grown under various heavy metal stress such as As, Cd, Cr, Cu, Pb, and Ni.

Vascular Changes in Macula, Optic Disc, and Choroid in Wilson's Disease: A Cross-sectional Optical Coherence Tomography Angiography Study

PURPOSE

To evaluate the changes in the retinal and optic disc (OD) microcirculation in patients with Wilson's disease (WD) using optical coherence tomography angiography (OCTA).

MATERIALS AND METHODS

This cross-sectional comparative study included 35 eyes of 35 WD patients (study group) and 36 eyes of 36 healthy participants (control group). The patients with WD were divided into subgroups based on the presence of Kayser-Fleischer rings. All the participants underwent a comprehensive ophthalmological examination, including OCTA.

RESULTS

The inferior perifoveal deep capillary plexus vessel density (DCP-VD), inferior radial peripapillary capillary vessel density (RPC-VD), and inferior peripapillary retinal nerve fiber layer (PPRNFL) thickness were significantly lower in the WD group than in the healthy participants (p=0.041, p=0.043, and p=0.045, respectively). In addition, in the subgroup analysis, the superior RPC-VD and inferior PPRNFL were significantly lower in the subgroup with Kayser-Fleischer rings (p=0.013 and p=0.041, respectively).

CONCLUSION

We showed there to be changes in certain OCTA parameters in WD patients when compared with healthy controls. Thus, we hypothesized that OCTA could detect any retinal microvascular changes in WD patients without clinical evidence of retinal or OD involvement.

Short and long-term phytoremediation capacity of aquatic plants in Cu-polluted environments

Freshwater ecosystems face numerous threats from human populations, including heavy metal contamination. Phytoremediation, the use of plants to remediate contaminated soils and sediments, is an effective and low-cost means of removing chemical contaminants, including heavy metals, from polluted environments. However, key questions remain unanswered in the application of this technology in aquatic environments, such as the long-term fate of pollutants following plant uptake. In this study, using two common wetland plant species (duckweed and tape grass), we first examined the capacity of plants to remove copper (Cu) from polluted water. Next, we evaluated the leaching potential of plant tissues following decomposition and how it is affected by a simulated freeze-thaw cycle. Using phytoremediated water and leachates from senesced plants we assessed phytoremediation success and Cu leaching potential by conducting standard toxicity assays using pond snails (Physa acuta), a species with known Cu sensitivity. We found that duckweed outperformed tape grass as a phytoremediator at low Cu concentrations. In addition, for plants grown in low concentrations of Cu, leaching from decaying plant material did not negatively impact snail survival, while at high concentrations of Cu, leaching did result in toxicity. Lastly, we found that a simulated freeze-thaw cycle increased the release of Cu from plant tissue in the presence of high Cu concentrations only, resulting in reduced snail survival. Our results indicate that in moderately Cu-polluted environments, some aquatic plants can remove contaminants without a long-term risk of leaching. In contrast, phytoremediation in highly polluted environments will likely require removal of plant tissue to prevent leaching of previously accumulated metals. Land managers must not only consider plant species and degree of contamination, but also geographic location, as freeze-thaw cycles may enhance plant decomposition and increase the likelihood of contaminant leaching following phytoremediation efforts in aquatic ecosystems.

Subcellular redox responses reveal different Cu-dependent antioxidant defenses between mitochondria and cytosol

Excess intracellular Cu perturbs cellular redox balance and thus causes diseases. However, the relationship between cellular redox status and Cu homeostasis and how such an interplay is coordinated within cellular compartments has not yet been well established. Using combined approaches of organelle-specific redox sensor Grx1-roGFP2 and non-targeted proteomics, we investigate the real-time Cu-dependent antioxidant defenses of mitochondria and cytosol in live HEK293 cells. The Cu-dependent real-time imaging experiments show that CuCl2 treatment results in increased oxidative stress in both cytosol and mitochondria. In contrast, subsequent excess Cu removal by bathocuproine sulfonate, a Cu chelating reagent, lowers oxidative stress in mitochondria but causes even higher oxidative stress in the cytosol. The proteomic data reveal that several mitochondrial proteins, but not cytosolic ones, undergo significant abundance change under Cu treatments. The proteomic analysis also shows that proteins with significant changes are related to mitochondrial oxidative phosphorylation and glutathione synthesis. The differences in redox behaviors and protein profiles in different cellular compartments reveal distinct mitochondrial and cytosolic response mechanisms upon Cu-induced oxidative stress. These findings provide insights into how redox and Cu homeostasis interplay by modulating specific protein expressions at the subcellular levels, shedding light on understanding the effects of Cu-induced redox misregulation on the diseases.

Application of 2,4,5-Tris(2-pyridyl)imidazole as "Turn-Off" Fluorescence Sensor for Cu (II) and Hg (II) ions and in vitro Cell Imaging

The 2,4,5-tris(2-pyridyl)imidazole (L) molecule has been evaluated as a probe for dual sensing of Hg²⁺ and Cu²⁺ ions in EtOH/HEPES buffer medium (5mM, pH=7.34, 1:1, v/v). Probe L shows a good sensitive and selective turn-off response in the presence of both Hg²⁺ and Cu²⁺ ions, which is comprehensible under long UV light. The probe can detect Cu²⁺ ion in the pH range of 3-11 and Hg²⁺ ion in 6-8. The limit of detection for Cu²⁺ (0.77 μM) is well under the allowable limit prescribed by the United States Environmental Protection Agency. Two metal (Cu²⁺ /Hg²⁺ ) ions are needed per L for complete fluorescence quenching. The probe shows remarkable reversibility on treatment with Na₂ EDTA, making the protocol more economical for practical purposes. Paper strip coated with the L solution of EtOH can detect the presence of Cu²⁺ and Hg²⁺ ions in the sample by visible quenching of the fluorescence intensity. DFT-TDDFT calculations support experimental observations, and d-orbitals of Cu²⁺ /Hg²⁺ provide a non-radiative decay pathway. Cell imaging study using HDF and MDA-MB-231 cells also supported the viability of L in detecting Cu²⁺ and Hg²⁺ ions in living cells.

A new fluorescence probe for detection of Cu+2 in blood samples: Circuit logic gate

A Fluorescence probe was designed based on 8-hydroxyquinoline chitosan silica precursor (HQCS) for selective detection of Al³⁺, Cu²⁺. The HQCS has no observable fluorescence signal, but after the addition of Al³⁺, a huge fluorescence signal appeared, and the selective quenching was absorbed after the addition of Cu²⁺. The effect of other different cations, including Cu²⁺, Mg²⁺, Ca²⁺, Pb²⁺, Zn²⁺, Hg²⁺, Ag⁺, Fe^3+, and K⁺ was studied. The addition of Cu²⁺ to the probe (HQCSAL) decreased the fluorescence very repeatable, and the variation of the fluorescence vs. Cu²⁺ was monotonic and linear. Therefore, the prepared probe was used to determine Cu²⁺ ions in real samples. The mechanism of fluorescence variation by adding cations to the probe solution was studied using the Stern-Volmer equation. Under the optimum conditions, the linear range and detection limit were 3.5-31 μM and 1 μM, respectively. The probe accuracy on the copper determination in the blood and tap waters was comparable to the ICP-OES results. The circuit logic gate mimic was designed for the fluorescence behavior of the probe constituents.

Assessment of Trace Elements Supply in Canned Tuna Fish Commercialized for Human Consumption in Brazil

This study evaluates the elemental content in 4 types of canned tuna fish groups, each with 4 brands that are commercialized for human consumption in Brazil. The results are based on trace elements in canned tuna fish quantified by ICP OES and a comparison to limit levels set by the FAO/WHO. We also checked the carcinogenic risk (CR), non-carcinogenic risk (Hazard Index (HI) and Hazard Quotient (HQ)), and pollution index (PI) for the studied canned tuna samples. As and Se concentrations in all groups are above the intake values set by FAO/WHO considering specific groups. The carcinogenic risk values for arsenic (As) in groups are considerably unacceptable (≥10-4). Hazard quotients (HQ) were >1 for As in all groups, while no sample was below 1 for HI. The pollution index (PI) results show that the main canned tuna fish contaminant is aluminum, then selenium and arsenic, respectively. Only half of the samples did not present elemental contaminant levels. All studied brands of canned tuna presented elemental concentrations that could pose a health risk to human consumption, that could be from CR, HQ, HI, or PI. The contaminant levels are alarming and should raise a red flag for the intake of these products, especially a long-term one. These results urge the authorities to supervise and enforce better practices for this type of food, protecting their population from health hazards.

Intensive removal of PAHs in constructed wetland filled with copper biochar

In this study, biochar-loading copper ions (Cu-BC), a novel composite for removing phenanthrene very efficiently from water, was prepared using the impregnation method. The performance of constructed wetlands (CWs) with these modified and original biochar as substrates was analyzed. CW with Cu-BC removed a large amount of phenanthrene (94.09 ± 3.02%). According to the surface characteristics analysis, Cu-BC can promote the removal of pollutants via complex absorption, hydrophobic adsorption, increasing the Lewis Pair and electrostatic attraction. Furthermore the higher nitrate removal rate in the treated system (91.11 ± 1.17%) was observed to have higher levels of bacterial metabolic diversity and denitrifier types. The phenanthrene accumulated in plants with this treatment system was enhanced by the role of copper in photosynthesis. It is able to boost the plant extraction of organic matter.

Tetrahymena Glutathione Peroxidase Family: A Comparative Analysis of These Antioxidant Enzymes and Differential Gene Expression to Metals and Oxidizing Agents

In the present work, an extensive analysis of the putative glutathione peroxidases (GPx) of the eukaryotic microorganism model Tetrahymena thermophila is carried out. A comparative analysis with GPx present in other Tetrahymena species and other very taxonomically diverse ciliates is also performed. A majority of ciliate GPx have replaced the selenocysteine (Sec) by Cys in its catalytic center, so they can be considered as phospholipid hydroperoxide glutathione peroxidases (PHGPx). Selenocysteine insertion sequence (SECIS) elements have been detected in several ciliate GPx that do not incorporate Sec in their amino acid sequences, and conversely, in other ciliate GPx with Sec, no SECIS elements are detected. These anomalies are analyzed and discussed. From the phylogenetic analysis using the ciliate GPx amino acid sequences, the existence of extensive intra- and interspecific gene duplications that produced multiple GPx isoforms in each species is inferred. The ancestral character of the selenoproteins is also corroborated. The analysis by qRT-PCR of six selected T. thermophila GPx genes has shown a quantitative differential expression between them, depending on the stressor (oxidizing agents, apoptotic inducer or metals) and the time of exposure.

Exposure to Environmental Pollutants and Their Association with Biomarkers of Aging: A Multipollutant Approach

Mitochondrial DNA (mtDNA) content and telomere length are putative aging biomarkers and are sensitive to environmental stressors, including pollutants. Our objective was to identify, from a set of environmental exposures, which exposure is associated with leukocyte mtDNA content and telomere length in adults. This study includes 175 adults from 50 to 65 years old from the cross-sectional Flemish Environment and Health study, of whom leukocyte telomere length and mtDNA content were determined using qPCR. The levels of exposure of seven metals, 11 organohalogens, and four perfluorinated compounds (PFHxS, PFNA, PFOA, PFOS) were measured. We performed sparse partial least-squares regression analyses followed by ordinary least-squares regression to assess the multipollutant associations. While accounting for possible confounders and coexposures, we identified that urinary cadmium (6.52%, 95% confidence interval, 1.06, 12.28), serum hexachlorobenzene (2.89%, 018, 5.68), and perfluorooctanesulfonic acid (11.38%, 5.97, 17.08) exposure were positively associated ( p < 0.05) with mtDNA content, while urinary copper (-9.88%, -14.82, -4.66) and serum perfluorohexanesulfonic acid (-4.75%, -8.79, -0.54) exposure were inversely associated with mtDNA content. Urinary antimony (2.69%, 0.45, 4.99) and mercury (1.91%, 0.42, 3.43) exposure were positively associated with leukocyte telomere length, while urinary copper (-3.52%, -6.60, -0.34) and serum perfluorooctanesulfonic acid (-3.64%, -6.60, -0.60) showed an inverse association. Our findings support the hypothesis that environmental pollutants interact with molecular hallmarks of aging.

Oxidative damage induced by copper in testis of the red swamp crayfish Procambarus clarkii and its underlying mechanisms

Copper (Cu) is one of the most widespread environmental pollutants and is known to exert multiple toxic effects including reproductive toxicity. In this study, we investigated the toxic effect of Cu on reproduction of the red swamp crayfish (Procambarus clarkii), an economic crustacean species, by exposing adult male crayfish to 0.03 and 3.00 mg/L Cu²⁺ for 7 days. The results showed that Cu²⁺ exposure induced oxidative stress accompanied by elevated reactive oxygen species (ROS) and malondialdehyde (MDA) levels in testes, and resulted in decreased sperm quality and abnormal testicular structures with apoptotic germ cells and vacuolisation in Sertoli cells. To reveal the molecular mechanism of Cu²⁺-induced oxidative damage in crayfish testes, we sequenced, assembled and annotated the transcriptome for crayfish testes, using the Illumina sequencing approach. After the 3.00 mg/L Cu²⁺ treatment, 6745 genes with differentially expressed profile were identified, of which many genes were involved in cellular response to ROS based on Gene Ontology enrichment analysis. Further, KEGG analysis demonstrated that genes with up-regulated expression levels significantly enriched in mitochondria oxidative phosphorylation pathway, suggesting disturbed mitochondrial electron transport chain was probably a main source of Cu²⁺-induced ROS production in testes. This study represented the first use of transcriptome to investigate the toxic effect of Cu²⁺ on male crayfish reproduction, and the pathways identified underlying Cu²⁺ toxicity at molecular level provide a novel insight into the reproductive toxicity of Cu in crustaceans.

Potentiating role of copper on spatial memory deficit induced by beta amyloid and evaluation of mitochondrial function markers in the hippocampus of rats

Mounting evidence suggests that copper, a crucial element in normal brain function, plays an important role in the etiology of Alzheimer's disease, which is known as a neurodegenerative mitochondrial disorder. However, the precise mechanisms of its effects on cognitive and mitochondrial functions through the CNS have not been thoroughly recognized yet. In this study, we aimed to investigate the long-term (3-week) effects of copper sulfate (50, 100 and 200 mg kg^-1 day^-1) exposure on learning and memory as well as on mitochondrial function in the hippocampus of rats in the presence and absence of beta amyloid (1 μg μl^-1 per side) intrahippocampally (IH). After three weeks of copper exposure through drinking water, acquisition and retention of spatial memory were measured by the Morris water maze (MWM) test. Various parameters of mitochondrial function were also evaluated. Our data show that copper damaged the spatial learning and memory and also exacerbated the memory deficit induced by Aβ injection in rats in a dose-dependent manner. Mitochondria isolated from the hippocampus of rats treated with copper showed significant increases in ROS formation, mitochondrial swelling, lipid peroxidation, glutathione oxidation, outer membrane damage, and collapse of MMP, decreased cytochrome c oxidase activity, and finally increased ADP/ATP ratios. Our results indicate that copper overloading in the hippocampus of rats causes mitochondrial dysfunction and subsequent oxidative stress leading to cognitive impairment. This study also reveals that copper can potentiate Aβ deleterious effects on spatial memory and brain mitochondrial function.

Effects of copper on the survival, hatching, and reproduction of a pulmonate snail (Physa acuta)

Acute and chronic bioassays provide essential basis for establishment of environmental quality standards. The effects of Cu on a pulmonate snail, Physa acuta, were investigated at a number of sublethal and lethal endpoints. Cu exposure suppressed movement and triggered an escape response in P. acuta at low and high concentrations, respectively, exerting acute toxic effects on adult snails exposed to a 96 h LC₅₀ of 23.8 μg L^-1. Following 16 d exposure of Cu to the egg masses, successful hatching decreased with increasing Cu concentration. High Cu concentrations (12.5 and 25 μg L^-1) resulted in inhibition of eye and shell development at the veliger stage, and a deformed shell, abnormal eyes, and different morphological shapes with lesions and hemorrhages were observed after 9 days of exposure. A large number of eggs exposed to 2.5-25 μg L^-1 Cu remained in the veliger and hippo stages for 2-7 days, with no further development. Results from reproduction tests showed that adult snails exposed to various Cu treatments produced more than three broods, with the total number of eggs ranging from 770 to 1,289, revealing little difference between the control and Cu-treated groups (p > 0.05). However, snails exposed to 12.5 and 25 μg L^-1 Cu produced polynuclear eggs in one egg capsule. The hatching success rate and shell length of the filial generation were significantly reduced in a dose-dependent manner (p < 0.05). The shell length of newly hatched snails was shorter in the reproduction test than in the hatching test, indicating inherent Cu toxicity in the filial generation from the exposed parent strain. The present study provides essential data regarding Cu toxicity in pulmonate snail P. acuta.

Transcriptional response of yellow perch to changes in ambient metal concentrations-A reciprocal field transplantation experiment

Recent local adaptation to pollution has been evidenced in several organisms inhabiting environments heavily contaminated by metals. Nevertheless, the molecular mechanisms underlying adaptation to high metal concentrations are poorly understood, especially in fishes. Yellow perch (Perca flavescens) populations from lakes in the mining area of Rouyn-Noranda (QC, Canada) have been faced with metal contamination for about 90 years. Here, we examine gene transcription patterns of fish reciprocally transplanted between a reference and a metal-contaminated lake and also fish caged in their native lake. After four weeks, 111 genes were differentially transcribed in metal-naïve fish transferred to the metal-contaminated lake, revealing a plastic response to metal exposure. Genes involved in the citric cycle and beta-oxidation pathways were under-transcribed, suggesting a potential strategy to mitigate the effects of metal stress by reducing energy turnover. However, metal-contaminated fish transplanted to the reference lake did not show any transcriptomic response, indicating a reduced plastic response capability to sudden reduction in metal concentrations. Moreover, the transcription of other genes, especially ones involved in energy metabolism, was affected by caging. Overall, our results highlight environmental stress response mechanisms in yellow perch at the transcriptomic level and support a rapid adaptive response to metal exposure through genetic assimilation.

Toxicity of copper on isolated liver mitochondria: impairment at complexes I, II, and IV leads to increased ROS production

Oxidative damage has been implicated in disorders associated with abnormal copper metabolism and also Cu(2+) overloading states. Besides, mitochondria are one of the most important targets for Cu(2+), an essential redox transition metal, induced hepatotoxicity. In this study, we aimed to investigate the mitochondrial toxicity mechanisms on isolated rat liver mitochondria. Rat liver mitochondria in both in vivo and in vitro experiments were obtained by differential ultracentrifugation and the isolated liver mitochondria were then incubated with different concentrations of Cu(2+). Our results showed that Cu(2+) induced a concentration and time-dependent rise in mitochondrial ROS formation, lipid peroxidation, and mitochondrial membrane potential collapse before mitochondrial swelling ensued. Increased disturbance in oxidative phosphorylation was also shown by decreased ATP concentration and decreased ATP/ADP ratio in Cu(2+)-treated isolated mitochondria. In addition, collapse of mitochondrial membrane potential (MMP), mitochondrial swelling, and release of cytochrome c following of Cu(2+) treatment were well inhibited by pretreatment of mitochondria with CsA and BHT. Our results showed that Cu(2+) could interact with respiratory complexes (I, II, and IV). This suggests that Cu(2+)-induced liver toxicity is the result of metal's disruptive effect on liver hepatocyte mitochondrial respiratory chain that is the obvious cause of Cu(2+)-induced ROS formation, lipid peroxidation, mitochondrial membrane potential decline, and cytochrome c expulsion which start cell death signaling.

Wilson's disease: a comprehensive review of the molecular mechanisms

Wilson’s disease (WD), also known as hepatolenticular degeneration, is an autosomal recessive inherited disorder resulting from abnormal copper metabolism. Reduced copper excretion causes an excessive deposition of the copper in many organs such as the liver, central nervous system (CNS), cornea, kidney, joints, and cardiac muscle where the physiological functions of the affected organs are impaired. The underlying molecular mechanisms for WD have been extensively studied. It is now believed that a defect in P-type adenosine triphosphatase (ATP7B), the gene encoding the copper transporting P-type ATPase, is responsible for hepatic copper accumulation. Deposited copper in the liver produces toxic effects via modulating several molecular pathways. WD can be a lethal disease if left untreated. A better understanding of the molecular mechanisms causing the aberrant copper deposition and organ damage is the key to developing effective management approaches.

Hepatic Copper Accumulation: A Novel Feature in Transient Infantile Liver Failure Due to TRMU Mutations?

Defects in the mitochondrial respiratory chain can induce a heterogeneous range of clinical and biochemical manifestations. Hepatic involvement includes acute fulminant hepatic failure, microvesicular steatosis, neonatal non-alloimmune haemochromatosis and cirrhosis. Recently pathogenic mutations in tRNA 5-methylaminomethyl-2-thiouridylate methyltransferase (TRMU) gene (OMIM 610230) have been demonstrated to cause transient infantile liver failure (OMIM 613070). The human TRMU gene encodes a mitochondrial protein, 5-methylaminomethyl-2-thiouridylate methyltransferase, whose molecular function is that of mitochondrial tRNA modification.We report an infant who presented with acute liver failure, in whom we observed hepatic copper intoxication and cirrhosis on liver biopsy. We postulate that the hepatic copper intoxication observed in our patient is most likely a secondary event associated with cholangiopathy. Periportal copper accumulation has been implicated in causing secondary mitochondrial dysfunction; the impact of copper accumulation in patients with TRMU mutations is unclear and warrants long-term clinical follow-up.

Cadmium and copper toxicity in three marine macroalgae: evaluation of the biochemical responses and DNA damage

Marine macroalgae have evolved a different mechanism to maintain physiological concentrations of essential metal ions and non-essential metals. The objective of the present work was to evaluate the antioxidant response and DNA damage of copper and cadmium ions in three halophytes, namely, Acanthophora spicifera, Chaetomorpha antennina, and Ulva reticulata. Accumulation of copper was significantly higher (P < 0.05) than that of cadmium. Biochemical responses showed that copper was considerably more toxic than cadmium (P < 0.05). Decreases in glutathione content and fluctuations of super oxide dismutase, catalase, and glutathione peroxidase activities were observed corresponding to time and concentration of exposure. Interestingly, it was also observed that antioxidant levels decreased as a result of metal accumulation, which may be due to free radicals generated by copper and cadmium in seaweeds. The present study also showed that copper and cadmium increased oxidative stress and induced antioxidant defense systems against reactive oxygen species. The order of toxicity for metals in the studied seaweeds was U. reticulata > A. spicifera > C. antennina. DNA damage index analysis supported that copper was significantly (P < 0.05) more toxic than cadmium. Bioaccumulation, biochemical responses, and DNA damage observed in the here analyzed marine macroalgae after exposure to selected metals indicate that these marine organisms represent useful bioindicators of marine pollution.

Chemical composition, antioxidant, antimicrobial and cytotoxic activities of Tagetes minuta and Ocimum basilicum essential oils

Chemical composition, antioxidant, antimicrobial and cytotoxic activities of Tagetes minuta (TM) essential oil (TMO) and Ocimum basilicum (OB) essential oil (OBO) were examined. The main components for TMO were dihydrotagetone (33.9%), E-ocimene (19.9%), tagetone (16.1%), cis-β-ocimene (7.9%), Z-ocimene (5.3%), limonene (3.1%) and epoxyocimene (2.03%). The main components for OBO were methylchavicol (46.9%), geranial (19.1%), neral (15.15%), geraniol (3.0%), nerol (3.0%), caryophyllene (2.4%). Inhibitory concentrations (IC₅₀) for reactive oxygen species (ROS) and reactive nitrogen species (RNS) scavenging were 12–17 and 200–250 μg/mL of TMO and OBO, respectively. Minimal inhibitory concentration (MIC) against Salmonella typhi,Escherichia coli,Staphylococcus aureus,Bacillus subtilis,Aspergillus niger, and Candida albicans were 150 ± 8, 165 ± 9, 67 ± 8, 75 ± 7, 135 ± 15, and 115 ± 8 μg/mL of TMO, respectively. MIC for S. typhi,E. coli,S. aureus,B. subtilis,A. niger, and C. albicans were 145 ± 8, 160 ± 7, 45 ± 4, 40 ± 3, 80 ± 9, and 95 ± 7 μg/mL of OBO, respectively. IC₅₀ for nasopharyngeal cancer cell line (KB) and liver hepatocellular carcinoma cell line (HepG2) were 75 ± 5 and 70 ± 4 μg/mL of TMO, respectively. IC₅₀ for KB and HepG2 were 45 ± 4 and 40 ± 3 μg/mL of OBO, respectively. Thus, they could be used as an effective source of natural antioxidant and antibacterial additive to protect foods from oxidative damages and foodborne pathogens. Furthermore, they could be promising candidate for antitumor drug design.

Loss of TRPML1 promotes production of reactive oxygen species: is oxidative damage a factor in mucolipidosis type IV?

TRPML1 is a lysosomal ion channel permeable to cations, including Fe2+. Our data suggest that TRPML1 redistributes Fe2+ between the lysosomes and the cytoplasm. Loss of TRPML1 leads to production of reactive oxygen species, and to mitochondrial deterioration.

Induction of reactive oxygen species in chlamydomonas reinhardtii in response to contrasting trace metal exposures

The toxicity of metals to organisms is, in-part, related to the formation of reactive oxygen species (ROS) in cells and subsequent oxidative stress. ROS are by-products of normal respiration and photosynthesis processes in organisms, but environmental factors, like metal exposure, can stimulate excess production. Metals involved in several different mechanisms such as Haber-Weiss cycling and Fenton-type reactions can produce ROS. Some metals, such as Cd, may contribute to oxidative stress indirectly by depleting cellular antioxidants. We investigated the measurement of ROS as a sensitive biomarker of metal toxicity (that could possibly be implemented in a biotic ligand model for algae) and we compared ROS induction in response to several contrasting transition metals (Cu, V, Ni, Zn, and Cd). We also compared the ROS response to glutathione and growth toxicity endpoints measured in a previous study. The cell-permeable dye, 2'7'dichlorodihydrofluorescein diacetate, was used as a probe to detect formation of ROS in Chlamydomonas reinhardtii cells. Metal-exposed cells were incubated with the fluorescent dye in a 96-well plate and monitored over 5.5 h. A dose-response of ROS formation was observed with Cu exposure in the range of 20-500 nM. Cu produced more ROS compared with either Zn or Cd (both nonredox active metals). The redox-active metal V produced increased ROS with increased concentration. The measurement of ROS may be a useful indicator of Cu toxicity, but the signal to noise ratio was better for the glutathione endpoint assay.

The acute toxicity of iron and copper: biomolecule oxidation and oxidative damage in rat liver

The transition metals iron (Fe) and copper (Cu) are needed at low levels for normal health and at higher levels they become toxic for humans and animals. The acute liver toxicity of Fe and Cu was studied in Sprague Dawley male rats (200 g) that received ip 0-60 mg/kg FeCl(2) or 0-30 mg/kg CuSO(4). Dose and time-responses were determined for spontaneous in situ liver chemiluminescence, phospholipid lipoperoxidation, protein oxidation and lipid soluble antioxidants. The doses linearly defined the tissue content of both metals. Liver chemiluminescence increased 4 times and 2 times after Fe and Cu overloads, with half maximal responses at contents (C(50%)) of 110 μgFe/g and 42 μgCu/g liver, and with half maximal time responses (t(1/2)) of 4h for both metals. Phospholipid peroxidation increased 4 and 1.8 times with C(50%) of 118 μg Fe/g and 45 μg Cu/g and with t(1/2) of 7h and 8h. Protein oxidation increased 1.6 times for Fe with C(50%) at 113 μg Fe/g and 1.2 times for Cu with 50 μg Cu/g and t(1/2) of 4h and 5h respectively. The accumulation of Fe and Cu in liver enhanced the rate of free radical reactions and produced oxidative damage. A similar free radical-mediated process, through the formation HO(•) and RO(•) by a Fenton-like homolytic scission of H(2)O(2) and ROOH, seems to operate as the chemical mechanism for the liver toxicity of both metals.

Electronic microscopy evidence for mitochondria as targets for Cd/Se/Te-based quantum dot 705 toxicity in vivo

The safety of quantum dots (QDs) 705 was evaluated in this study. Mice were treated with QD705 (intravenous) at a single dose of (40 pmol) for 4, 12, 16, and 24 weeks. Effects of QD705 on kidneys were examined. While there was a lack of histopathology, reduction in renal functions was detected at 16 weeks. Electron microscopic examination revealed alterations in proximal convoluted tubule (PCT) cell mitochondria at even much earlier time, including disorientation and reduction of mitochondrial number (early change), mitochondrial swelling, and later compensatory mitochondrial hypertrophy (enlargement mitochondria: giant mitochondria with hyperplastic inner cristae) as well as mitochondrial hyperplasia (increase in mitochondrial biogenesis and numbers) were observed. Such changes probably represent compensatory attempts of the mitochondria for functional loss or reduction of mitochondria in QD705 treated animals. Moreover, degeneration of mitochondria (myelin-figure and cytoplasmic membranous body formation) and degradation of cytoplasmic materials (isolated cytoplasmic pockets of degenerated materials and focal cytoplasmic degradation) also occurred in later time points (16-24 weeks). Such mitochondrial changes were not identical with those induced by pure cadmium. Taken together, we suggest that mitochondria appeared to be the target of QD705 toxicity and specific mitochondrial markers may be useful parameters for toxicity assessments of QDs or other metal-based nanomaterials.

The use of multiple endpoints to assess cellular responses to environmental contaminants in the interstitial marine ciliate Euplotes crassus

This paper presents the results of investigations on the suitability of Euplotes crassus, an interstitial marine ciliate, to be used as model organism in ecotoxicology and thereafter to evaluate the toxicity of estuarine and coastal sediments upon laboratory exposure. Nowadays, anthropogenic activities have resulted in accumulation of metals and organic pollutants in the environment as well as in the food chain hence leading to serious ecological and human health problems. This may pose a risk to benthic and epibenthic organisms and it is crucial to discover toxicity tests that will identify adverse effects of sediment-associated chemicals on benthic organisms. Due to their nature as a eukaryotic cell/organism and their position in the food web, ciliated protozoa are suitable models for evaluating the effects of pollution on aquatic communities. Lethal and sublethal effects of exposure to inorganic and organic pollutants were tested on the cell mortality, replication rate, lysosomal membrane stability and endocytosis rate of E. crassus. Increasing nominal concentrations of individual and mixtures of mercury, copper, and benzo(a)pyrene were investigated in this study as they might be bioavailable in naturally occurring polluted sites. A significant decrease in the mean replication rate (p<0.05) was found after 24h exposures to m/μM concentrations of all tested pollutants. At the same time, significant decreases of lysosomal membrane stability (p<0.05) were observed for Cu (5 μM), Hg (10 nM), and B(a)P (200 nM). Among the entire suite of tests, endocytosis rate test demonstrated the highest sensitivity. Exposures to binary mixtures of all studied pollutants were performed showing both inorganic-organic and inorganic-inorganic additive and/or antagonist effects. Moreover, medium salinity was also varied to mimic estuarine-like environmental conditions linking biological response to ionic strengths. Under these conditions significant increases of both endocytosis rate and lysosomal membrane stability were observed and related to the increment of some Hg- and Cu-related toxic complexes. The studied biomarkers were always able to discriminate between the effects of organic and inorganic pollutants. Together with the short time and simplicity of the test procedures, results obtained in this study indicate that E. crassus is a promising and convenient bioindicator for evaluating the toxicity of different environmental matrixes like pore water, sediments and wastewaters--polluted by metals and organic pollutants.

Acute responses of brown mussel (Perna perna) exposed to sub-lethal copper levels: integration of physiological and cellular responses

This study examined the effect of sub-lethal copper levels on selected physiological and cellular responses of the marine bivalve Perna perna. Animals were exposed to five environmentally relevant concentrations of 12.5, 25.0, 37.5 and 50.0 μg L⁻¹ copper and metal accumulation was found to be significantly increased at the two higher copper concentrations after 24 h of exposure. Physiological responses found to increase during acute copper exposure included mucus secretion rate (at 25 and 50 μg L⁻¹ copper), nitrogen excretion rates and oxygen consumption rates (both at 25 and 50 μg L⁻¹ copper). Perna perna changed its substrate utilisation at 25, 37.5 and 50 μg L⁻¹ copper in favour of protein-based metabolism. A higher degree of ROS induced DNA damage was observed at acute exposure to 37.5 and 50 μg L⁻¹ copper. Filtration rate was unchanged during acute copper exposure. A model is proposed that integrates cellular and physiological responses to copper during short-term acute and long-term chronic exposures.

Liver failure with coagulopathy, hyperammonemia and cyclic vomiting in a toddler revealed to have combined heterozygosity for genes involved with ornithine transcarbamylase deficiency and Wilson disease

A girl with a 2 month history of cyclic episodes of vomiting, diarrhea, and lethargy lasting 2-3 days each presented with acute hepatopathy (ALT 3,500 IU/L) with coagulopathy (PT 55 s) and hyperammonemia (207 μmol/L) at age 1½ years. Biochemical and molecular analyzes revealed ornithine transcarbamylase (OTC) deficiency. While laboratory signs of mild hepatocellular dysfunction are common in OTC deficiency, substantial liver failure with coagulopathy is generally not seen, although four others cases have been reported, three of which presented with cyclic vomiting. Further evaluation in our case revealed elevated urine (198.8 μg/g creatinine) and liver (103 μg/g dry weight) copper content, and a heterozygous mutation in the Wilson disease gene, ATP7B. Our patient, now aged 5 years, has remained in excellent health with normal growth and development on fasting avoidance, a modified vegan diet, and sodium phenylbutyrate.These five cases demonstrate that generalized liver dysfunction/failure is a potential serious complication of OTC deficiency, although not a common one, and suggests that an ALT and PT should be obtained in OTC patients during episodes of hyperammonemia. Cyclic vomiting is a known presentation of OTC deficiency; it is not known if comorbid liver failure predisposes toward this phenotype. We propose that the heterozygote state in ATP7B increases the liver copper content, thus predisposing our patient with OTC deficiency to develop liver failure during a hyperammonemic episode. Our present case is an example of the opportunity of molecular diagnostics to identify putative modifier genes in patients with atypical presentations of genetic disorders.

Fragmentation of mitochondrial cardiolipin by copper ions in the Atp7b-/- mouse model of Wilson's disease

Cellular copper overload as found in Wilson's disease may disturb mitochondrial function and integrity. Atp7b(-/-) mice accumulate copper in the liver and serve as an animal model for this inherited disease. The molecular mechanism of copper toxicity in hepatocytes is poorly understood. Total mitochondrial lipids from liver of wild-type mice were subjected to oxidative stress by the Cu(2+)/H(2)O(2)/ascorbate system. Phosphatidic acid (PA) and phosphatidylhydroxyacetone (PHA) were detected as cardiolipin fragmentation products by thin-layer chromatography combined with MALDI-TOF mass spectrometry in oxidized samples, but not in unperturbed ones. The formation of PA and PHA in copper-treated model membrane correlated well with the decrease of cardiolipin. Mitochondrial lipids from Atp7b(-/-) mice of different age were analyzed for the presence of PA. While 32-weeks old wild-type (control) and Atp7b(-/-) mice did not show any PA, there was a steady increase in the amount of this lipid in Atp7b(-/-) mice in contrast to control with increasing age. Hepatocytes from elder Atp7b(-/-)mice contained morphologically changed mitochondria unlike cells from wild-type animals of the same age. We concluded that free-radical fragmentation of cardiolipin with the formation of PA is a likely mechanism that damages mitochondria under conditions of oxidative stress due to copper overload. Our findings are relevant for better understanding of molecular mechanisms for liver damage found in Wilson's disease.

Effects of copper on the egg development and hatching of a freshwater pulmonate snail Lymnaea luteola L

A freshwater invertebrate egg development and hatching toxicity test with an Indian freshwater pulmonate snail, Lymnaea luteola, comprising the following developmental endpoints was described: mortality, development, formation of eyes and foot structure, heart rate, duration of different larval stages, and hatching time. Developmental stages were morula, and at third, fifth, and eighth days; the trochophore, veliger, and hippo larvae, respectively. At the age of about 9th to 11th days after egg laying; more than 95% young snail hatched in control laboratory conditions. To evaluate effects on embryonic development, the pulmonate snail eggs of 24-h old were exposed to a series of nominal copper concentrations. The percentage survival of embryos treated in 10-32 microg l(-1) of Cu after 240 h of exposure drops sharply at veliger and hippo stages. All embryos died at 100-320 microg l(-1) of Cu within 168 h of exposure at trochophore and early veliger stages. The detected abnormalities were malformation of foot, eyes, thinness and incomplete formation of shell, growth retardation, and slow rotation of embryo within the egg capsule as compared to control embryos. Lethal and sublethal effects in terms of mortality and significant delay in hatching could be found in the 3.2, 5.6 and 10 microg l(-1) of Cu concentrations. This species is widely distributed in the Indian subcontinent freshwater reservoirs and more sensitive to Cu than other tested aquatic test organisms; therefore, could be used as a test model of Cu and possibly other pollutants for rapid risk assessment of environmental pollutants. The snail egg embryo bioassay is simple, rapid, highly sensitive, cost-effective, and easy to test under standardized laboratory conditions.

Close encounters of the small kind: adverse effects of man-made materials interfacing with the nano-cosmos of biological systems

Engineered nanomaterials have unique physico-chemical properties that make them promising for many technological and biomedical applications, including tissue regeneration, drug and gene delivery, and in vivo monitoring of disease processes. However, with the burgeoning capabilities to manipulate structures at the nano-scale, intentional as well as unintentional human exposures to engineered nanomaterials are set to increase. Nanotoxicology is an emerging discipline focused on understanding the properties of engineered nanomaterials and their interactions with biological systems, and may be viewed as the study of the undesirable interference between man-made nanomaterials and cellular nanostructures or nanomachines. In this review, we discuss recognition of engineered nanomaterials by the immune system, our primary defense system against foreign invasion. Moreover, as oxidative stress is believed to be one of the major deleterious consequences of exposure to nanomaterials, we explore triggering of pro- and antioxidant pathways as well as biomarkers of oxidative stress. Finally, we highlight in vivo studies of the toxicological outcomes of engineered nanomaterials, including carbon nanotubes, with an emphasis on inflammation and genotoxic responses.

The effects of copper sulfate on liver histology and biochemical parameters of term Ross broiler chicks

Copper is an essential trace element that is extremely toxic to organisms and organs at high doses. We have investigated the histological and biochemical effects of a toxic dose of copper sulfate on the liver of term Ross broiler chicks. Fertilized eggs were divided into three groups: experimental, injected with 50 mcg/0.1 ml copper sulfate in the air chambers on day 1; sham, injected with 0.1 ml saline; and control, no injection. Term chicks were killed and their livers investigated histologically, with hematoxylin-eosin-stained sections examined under light microscopy, and biochemically, for malondialdehyde and glutathione levels. Histological examinations showed copper-treated samples with granular degeneration and necrosis of hepatocytes and impairment to the cell lining of the remark cords. The samples had a congestive appearance, with blood in the vena centralis and sinusoids, slight connective tissue increase, and lymphocyte infiltration. Control and sham group sections had normal appearances. As oxidative damage parameters, in the copper-treated group, malondialdehyde levels were increased and glutathione levels decreased. In the sham and control groups, there were no significant differences. At this toxic dose, copper sulfate shows oxidative damage according to the histology of term chick liver that are confirmed biochemically by the changes in malondialdehyde and glutathione levels.

Comparison of biosorbents with inorganic sorbents for removing copper(II) from aqueous solutions

In comparison with several other reported inorganic sorbents, Camellia tree leaf and primary sludge obtained from a settling tank as a pretreatment to the activated sludge system in a Hong Kong sewage treatment plant were evaluated for removing Cu(II) from aqueous solutions. Experimental data were modeled by the Langmuir isotherm equation to estimate the maximum sorption capacity (q(max)). Results show that, at pH 5.6, biosorbents, Camellia tree leaf and primary sludge in particular, exert higher sorption capacities (q(max)>40 mg g(-1)) than inorganic sorbents, Na-montmorillonite (q(max)=33.3 mg g(-1)), fly ash (q(max)=18.8 mg g(-1)), and goethite powder (10.3 mg g(-1)). Furthermore, a pseudo second-order kinetic model was found to properly describe the experimental data for both bio- and inorganic sorbents. Sorption of Cu(II) on the Camellia tree leaf and primary sludge were much faster than that on the inorganic sorbents. In addition, desorption tests revealed that the desorption capacities of the two biomaterials are higher than the other selected materials; and much more Cu(II) can be retrieved from the Cu(II)-loaded biosorbents. Finally, increasing solution pH was found to greatly increase q(max) and accelerate sorption processes.

Protein carbonylation in THP-1 cells induced by cigarette smoke extract via a copper-catalyzed pathway

Cigarette smoke is a mixture of chemicals that cause direct or indirect oxidative stress in different cell lines. We investigated the effect of nonfractionated cigarette smoke extract (CSE) on protein carbonylation in human THP-1 cells. Cells were exposed to various concentrations (2.5-20%) of CSE for 30 min, and protein carbonylation was assessed by use of the sensitive 2,4-dinitrophenylhydrazine immuno-dot blot assay. CSE-induced protein carbonylation exhibited a dose-response relation with CSE concentrations. However, with prolonged exposure to CSE, significant decrements were observed when compared with the 30 min exposure. Cotreatment of THP-1 cells with antioxidants (N-acetyl-cysteine, S-allyl-cysteine, and alpha-tocopherol) and copper(II) ion chelators (d-penicillamine) during CSE exposure significantly reduced protein carbonylation, whereas cotreatment with antioxidants (vitamin C and trolox) and a metal chelator (EDTA), iron chelator (1,10-phenanthroline), or copper(I) chelator (neocuprin) did not decrease CSE-induced protein carbonylation in THP-1 cells. These results suggest that protein carbonylation is induced by CSE in THP-1 cells via a copper(II)-catalyzed reaction and not an iron-catalyzed reaction. Furthermore, the copper(II) ions involved in this CSE-induced protein carbonylation are derived from the intracellular pool, not via uptake from the extracellular medium. We speculate that natural copper(II) chelators may prevent some of the health problems caused by cigarette smoking, including lung disease, renal failure, and diabetes.

Assessment of mixture toxicity of copper, cadmium, and phenanthrenequinone to the marine bacterium Vibrio fischeri

Transition metals and polycyclic aromatic hydrocarbons (PAHs) are cocontaminants at many sites. Contaminants in mixtures are known to interact with biological systems in ways that can greatly alter the toxicity of individual compounds. The toxicities (individually and as mixtures) of copper (Cu), a redox-active metal; cadmium (Cd), a nonredox active metal; and phenanthrenequinone (PHQ), a redox-active oxygenated PAH, were examined using the bioluminescent bacterium Vibrio fischeri. We found that the cotoxicity of Cu/PHQ was dependent on the ratio of concentrations of each chemical in the mixture. Different interaction types (synergism, antagonism, and additivity) were observed with different combinations of these toxicants. The interaction types changed from antagonism at a low Cu to PHQ ratio (1:4), to additive at an intermediate Cu to PHQ ratio (2:3), to synergistic at higher Cu to PHQ ratios (3:2 and 4:1). In contrast to Cu/PHQ mixtures, the cotoxicity of Cd/PHQ did not change at different mixture ratios and was found for the most part to be additive. For the individual chemicals and their mixtures, reactive oxygen species (ROS) production was observed in V. fischeri, suggesting that individual and mixture toxicity of Cu, Cd, and PHQ to V. fischeri involves ROS-related mechanisms. This study shows that mixture ratios can alter individual chemical toxicity, and should be taken into account in risk assessment.

Differential regulation of zebrafish metallothionein-II (zMT-II) gene transcription in ZFL and SJD cell lines by metal ions

Two alleles of a zebrafish metallothionein II gene (zMT-II) promoter (zMT-IIA and zMT-IIB) containing 10 MREs in the 5'-flanking region (1514bp) were identified in zebrafish. These putative MREs were confirmed via electrophoretic mobility shift assay (EMSA) to have binding activities from the cellular and nuclear extracts of a zebrafish cell line, ZFL. Transient gene expression studies using zebrafish liver (ZFL) and caudal fin (SJD) cell lines also confirmed that the most distal cluster of MREs contributed to the maximal induction of zMT-IIA activity by Zn(2+) and that this Zn(2+) induction was dose-dependent. Further transient gene expression assay of the zMT-IIA gene promoter was carried out to study the effects of various metal ions (Zn(2+), Cd(2+), Cu(2+), Hg(+), As(3+), As(5+), Cr(3+) and Cr(6+)), and Zn(2+) and Cd(2+) were found to be the most efficient MT gene inducers of zMT-II. As(3+) was a weak inducer of zMT-II in the two cell lines, and Hg(+) caused significant induction only in the SJD cells. No significant induction was found in the other metal ion exposures. EMSA also identified transcription factor(s) of two different sizes from the cytoplasmic and nuclear extracts of the ZFL cells that were able to bind with the MREs, but no increase in MRE binding was detected in the extracts of these cells after Zn(2+) or Cd(2+) treatment, compared with untreated control cells. The mechanisms of MT gene transcription induction via metal ions are discussed herein.

Heavy metals generate reactive oxygen species in terrestrial and aquatic ciliated protozoa

Reactive oxygen species (ROS) induction by exposure to heavy metals (Cd, Cu or Zn) in diverse free-living ciliated protozoa (Tetrahymena sp. and three strains of Colpoda steinii, isolated from freshwater and soils with different level of metal pollution) has been evaluated. Using specific fluorophores, such as 2',7'-dichlorofluorescein diacetate, hydroethidine and dihydrorhodamine 123, and a fluorescence microscope with the program MetaMorph Imaging System 4.0, we have analyzed both the average fluorescence emission and the heterogeneous distribution of fluorescence in control and treated cells. This is the first time that these fluorophores are used to detect ROS production in ciliated protozoa. All metals generate ROS, mainly superoxide and peroxides, showing a remarkable inter- and intra-specific variations. Likewise, resistance against each metal was also very diverse. Cu and specially Cd, the most toxic heavy metal for these ciliates, are the best oxidative stress inducers. However, a correlation between fluorescence emission intensity and cellular metal sensitivity for each strain cannot be established. Results are discussed and compared with similar findings previously published in other unicellular and pluricellular organisms.

Formation of phosphatidic acid in stressed mitochondria

Mitochondria are an important intracellular source of ROS as well as a sensitive target for oxidative damage under certain pathological conditions such as iron or copper overload. Mitochondrial membranes are rich in the tetraacyl phospholipid cardiolipin. Its integrity is important for efficient oxidative phosphorylation. Mouse liver mitochondria were subjected to oxidative stress by the Cu(2+)(Fe(2+))/H(2)O(2)/ascorbate system. Phosphatidic acid was detected in oxidized mitochondria, but not in unperturbed mitochondria. The Cu(2+)/H(2)O(2)/and (or not) ascorbate system caused the formation of phosphatidic acid and phosphatidylhydroxyacetone in cardiolipin liposomes. These products proceed via an HO*-radical induced fragmentation taking place in the polar moiety of cardiolipin. Mass spectrometry analysis of phosphatidic acid newly formed in mitochondria revealed that it has been derived from fragmentation of cardiolipin. Thus, free-radical fragmentation of cardiolipin in its polar part with the formation of phosphatidic acid is a likely mechanism that damages mitochondria under conditions of oxidative stress.

Preventing cell death induced by carbonyl stress, oxidative stress or mitochondrial toxins with vitamin B anti-AGE agents

Carbonyls generated by autoxidation of carbohydrates or lipid peroxidation have been implicated in advanced glycation end product (AGE) formation in tissues adversely affected by diabetes complications. Tissue AGE and associated pathology have been decreased by vitamin B(1)/B(6) in trials involving diabetic animal models. To understand the molecular cytoprotective mechanisms involved, the effects of B(1)/B(6) vitamers against cytotoxicity induced by AGE/advanced lipid end product (ALE) carbonyl precursors (glyoxal/acrolein) have been compared to cytotoxicity induced by oxidative stress (hydroperoxide) or mitochondrial toxins (cyanide/copper). Thiamin was found to be best at preventing cell death induced by carbonyl stress and mitochondrial toxins but not oxidative stress cell death suggesting that thiamin pyrophosphate restored pyruvate and alpha-ketoglutarate dehydrogenases inhibited by mitochondrial toxicity. However, B(6) vitamers were most effective at preventing oxidative stress or lipid peroxidation cytotoxicity suggesting that pyridoxal or pyridoxal phosphate were antioxidants and/or Fe/Cu chelators. A therapeutic vitamin cocktail could provide maximal prevention against carbonyl stress toxicity associated with diabetic complications.

Biological effects of essential oils--a review

Since the middle ages, essential oils have been widely used for bactericidal, virucidal, fungicidal, antiparasitical, insecticidal, medicinal and cosmetic applications, especially nowadays in pharmaceutical, sanitary, cosmetic, agricultural and food industries. Because of the mode of extraction, mostly by distillation from aromatic plants, they contain a variety of volatile molecules such as terpenes and terpenoids, phenol-derived aromatic components and aliphatic components. In vitro physicochemical assays characterise most of them as antioxidants. However, recent work shows that in eukaryotic cells, essential oils can act as prooxidants affecting inner cell membranes and organelles such as mitochondria. Depending on type and concentration, they exhibit cytotoxic effects on living cells but are usually non-genotoxic. In some cases, changes in intracellular redox potential and mitochondrial dysfunction induced by essential oils can be associated with their capacity to exert antigenotoxic effects. These findings suggest that, at least in part, the encountered beneficial effects of essential oils are due to prooxidant effects on the cellular level.

Hepatic mitochondrial function and brain tumours

PURPOSE OF REVIEW

Therapeutic advances remain modest for patients with malignant brain tumours, due in part to inadequate ability of in-vitro models to mimic the consequences of tumour progression in vivo, which include profound immunosuppression, cytokine dysregulation and microvascular proliferation. This review summarizes recent findings on the wasting consequences of glioma growth, including changes in hepatic metabolism caused by the tumour.

RECENT FINDINGS

Release of proinflammatory cytokines by gliomas leads to anorexia, a sensation of tiredness and fatigue associated with sleep deprivation. The cachexia and associated decrease in relative liver mass that are observed in rats with the most aggressive gliomas may be accounted for by increased activity of the Cori cycle, with the intermediary metabolism of the glioma-influenced liver being directed toward energy utilization rather than energy storage. In these conditions, liver mitochondria exhibit abnormal biogenesis, together with modifications to water dynamics and ion content.

SUMMARY

Improved patient care will result from better understanding of the interactions between brain tumour cells and the immune system, and use of nutritional metabolic therapy to protect tumour-influenced hepatocytes and their mitochondria may improve outcomes.

Flow cytometry assessment of cytotoxicity and reactive oxygen species generation by single and binary mixtures of cadmium, zinc and copper on populations of the ciliated protozoan Tetrahymena thermophila

In the present study, we have assessed by flow cytometry, the cytotoxicity of the heavy metals Cd, Zn and Cu on populations of the ciliated protozoan Tetrahymena thermophila. The obtained LC(50) for these metals was estimated as 0.195mgCdl(-1), 3.58mgZnl(-1) and 0.47mgCul(-1), respectively. As a result, the toxicity rank for this eukaryotic microorganism is Cd>Cu>>Zn. Using the same methodology and the Concentration Addition approach, the toxicity of binary mixtures of these metals was evaluated in order to detect the type of interaction between these metals. Results indicated that antagonism is the predominant interaction but it can change to additivity or even to synergism at high metal concentrations. Besides, the concentration ratio between metals plays also a crucial role in determining the type of metallic interaction, at least in Tetrahymena. Cytotoxicity data from single and bimetallic mixtures have been compared with those from selected microalgae, other species of ciliates, fish and mammalian cell lines and metazoan. By other hand, we have detected the mitochondrial generation of peroxides induced by both single and binary treatments with Cd, Zn and Cu on populations of Tetrahymena, using the specific fluorophore dyhidrorhodamine. The nature and concentrations of metal as well as the metallic ratio were important factors in reactive oxygen species production. All results found in T. thermophila are compared with previous reports in other organisms and, some explanations and hypothesis to support results are given, including the involvement of metallothioneins as antioxidants and their role in the binding of metal cations.