BioMetals (v.27, #1)
Mercury rising: response to the EPA assessment of mercury exposure by Dan R. Laks (1-4).
Pathogenetic role of magnesium deficiency in ophthalmic diseases by Renu Agarwal; lgor Iezhitsa; Puneet Agarwal (5-18).
Magnesium is one of the most important regulatory cation involved in several biological processes. It is important for maintaining the structural and functional integrity of several vital ocular tissues such as cornea, lens and retina. The magnesium content of lens, especially in its peripheral part, is higher than that in aqueous and vitreous humor. Magnesium has also been shown to play critically important role in retinal functions. Magnesium plays significant role as a cofactor for more than 350 enzymes in the body and regulates neuroexcitability and several ion channels. Membrane associated ATPase functions that are crucial in regulating the intracellular ionic environment, are magnesium-dependent. Moreover, the enzymes involved in ATP production and hydrolysis are also magnesium-dependent. Magnesium deficiency by interfering with ATPase functions causes increased intracellular calcium and sodium and decreases intracellular potassium concentration. Such ionic imbalances in turn alter the other cellular enzymatic reactions and form the basis of the association of magnesium deficiency with ophthalmic diseases such as cataract. In presence of magnesium deficiency, an imbalance between mediators of vasoconstriction and vasorelaxation may underlie the vasospasm, which is one of the pathogenic factors in primary open angle glaucoma. Furthermore, magnesium deficiency is also a contributing factor in increased oxidative stress and inducible NOS stimulation that can further contribute in the initiation and progression of ocular pathologies such as cataract, glaucoma and diabetic retinopathy. In this paper we review the association of disturbances of magnesium homeostasis with several ophthalmic diseases.
Keywords: Magnesium; Potassium; Calcium; Cataract; Glaucoma; Diabetic retinopathy; Ocular surface; Retina
New science challenges old notion that mercury dental amalgam is safe by Kristin G. Homme; Janet K. Kern; Boyd E. Haley; David A. Geier; Paul G. King; Lisa K. Sykes; Mark R. Geier (19-24).
Mercury dental amalgam has a long history of ostensibly safe use despite its continuous release of mercury vapor. Two key studies known as the Children’s Amalgam Trials are widely cited as evidence of safety. However, four recent reanalyses of one of these trials now suggest harm, particularly to boys with common genetic variants. These and other studies suggest that susceptibility to mercury toxicity differs among individuals based on multiple genes, not all of which have been identified. These studies further suggest that the levels of exposure to mercury vapor from dental amalgams may be unsafe for certain subpopulations. Moreover, a simple comparison of typical exposures versus regulatory safety standards suggests that many people receive unsafe exposures. Chronic mercury toxicity is especially insidious because symptoms are variable and nonspecific, diagnostic tests are often misunderstood, and treatments are speculative at best. Throughout the world, efforts are underway to phase down or eliminate the use of mercury dental amalgam.
Keywords: Mercury; Dental amalgam; Porphyrins; Chronic mercury toxicity
Predictive association of copper metabolism proteins with Alzheimer’s disease and Parkinson’s disease: a preliminary perspective by Amit Pal; Ashok Kumar; Rajendra Prasad (25-31).
Neurodegenerative diseases, Alzheimer’s disease (AD) and Parkinson’s disease (PD), constitute a major worldwide health problem. Several hypothesis have been put forth to elucidate the basis of onset and pathogenesis of AD and PD; however, till date, none of these seems to clearly elucidate the complex pathoetiology of these disorders. Notably, copper dyshomeostasis has been shown to underlie the pathophysiology of several neurodegenerative diseases including AD and PD. Numerous studies have concluded beyond doubt that imbalance in copper homeostatic mechanisms in conjunction with aging causes an acceleration in the copper toxicity elicited oxidative stress, which is detrimental to the central nervous system. Amyloid precursor protein and α-synuclein protein involved in AD and PD are copper binding proteins, respectively. In this review, we have discussed the possible association of copper metabolism proteins with AD and PD along with briefly outlining the expanding proportion of “copper interactome” in human biology. Using network biology, we found that copper metabolism proteins, superoxide dismutase 1 and ceruloplasmin may represent direct and indirect link with AD and PD, respectively.
Keywords: Copper dyshomeostasis; Wilson’s disease; Alzheimer’s disease; Parkinson’s disease; Network biology
The effect of Se-deficient diet on gene expression of inflammatory cytokines in chicken brain by Peng-fei Sheng; Yue Jiang; Zi-wei Zhang; Jiu-li Zhang; Shu Li; Zi-qun Zhang; Shi-wen Xu (33-43).
Selenium (Se) plays an important role in the brain development, function, and degeneration, nutritional encephalomalacia is closely related with dietary Se in avian. However, there is little evidence on the relationship between inflammation and encephalomalacia in avian and the mechanism which Se regulates the inflammatory response in brain tissues remains to be unclear. The present paper describes the effects of Se-deficient granulated diet on one transcription factor-nuclear factor kappaB and four pro-inflammatory cytokines-tumor necrosis factor, cyclooxygenase2, inducible nitric oxide synthase and Prostaglandin E synthase mRNA expression in the chicken brain tissues associated encephalomalacia. One hundred male chickens (1 day old; Weiwei Co. Ltd., Harbin, China) were divided into two groups (50 chickens per group). The expression levels in the brain tissues (cerebral gray matter, cerebral white matter, marrowbrain, cerebellum, thalamus and brain stem) were determined by real-time PCR on days 15, 25, 35, 45, and 55, respectively. The results showed the productions of pro-inflammatory mediators were increased following Se-deficiency. These data indicate the correlations between nutritional encephalomalacia and inflammatory response and the activity of inflammatory response in chicken brain may be induced by Se-deficiency.
Keywords: Chicken; Brain tissues; Selenium; NF-κB; COX-2; PTGES
Micromolar copper modifies electrical properties and spontaneous discharges of nodose ganglion neurons in vitro by Fernando C. Ortiz; Cecilia Vergara; Julio Alcayaga (45-52).
Copper plays a key role in aerobic cell physiology mainly related to mitochondrial metabolism. This element is also present at higher than basal levels in some central nuclei and indeed, current evidence support copper’s role as a neuromodulator in the central nervous system. More recent data indicate that copper may also affect peripheral neuronal activity, but so far, there are not detailed descriptions of what peripheral neuronal characteristics are targeted by copper. Here, we studied the effect of physiological concentration of CuCl2 (μM range) on the activity of peripheral neurons using a preparation of nodose ganglion in vitro. By mean of conventional intracellular recordings passive and active electrical membrane properties were studied. Extracellular copper modified (in a redox-independent manner) the resting membrane potential and the input resistance of the nodose ganglion neurons, increasing the excitability in most of the tested neurons. These results suggest that Cu2+ modulates the activity of nodose ganglion neurons and support nodose ganglion in vitro preparation as a simple model to study the subcellular mechanisms involved in the Cu2+ effects on neuron electrical properties.
Keywords: Copper; Excitability; Primary sensory neurons; Nodose ganglion; Vagal afferents
In silico investigation of the ATP7B gene: insights from functional prediction of non-synonymous substitution to protein structure by Rosanna Squitti; Mariacristina Siotto; Serena Bucossi; Renato Polimanti (53-64).
ATP7B is a copper-transporting ATPase that plays a key role in the regulation of copper homeostasis. Mutations in the ATP7B gene are causative for Wilson’s disease, and recent reports have suggested that genetic variants are associated with susceptibility to Alzheimer’s disease. Unfortunately, it is difficult to profile experimentally novel genetic variants in the ATP7B gene, because the human protein X-ray structure is not yet entirely understood. In order to investigate ATP7B non-synonymous substitutions, we used an in silico amino acid sequence-based approach. Specifically, we analyzed 337 ATP7B non-synonymous substitutions, which included Wilson’s disease-causing mutations (DVs) and non Wilson’s disease-causing variants (NDVs), with an algorithm that estimated a combined probability (cPdel) of an amino acidic change to be deleterious for the protein function. This approach appeared to reliably indentify the probability of DVs and NDVs to be deleterious and to profile still unknown gene variants. Specifically, after analyzing ATP7B protein domains with the cPdel method, we found results in line with the predicted–modeled domains and some new suggestions. In conclusion, a functional survey of amino acid changes in the ATP7B protein is provided herein, and we suggest that this bioinformatic method can furnish information about novel ATP7B mutations. Furthermore, the same approach can be applied to other uncharacterized proteins.
Keywords: Wilson’s disease; Gene mutation; Amino acidic substitution; Protein domain; Copper
The lipidome of the photosynthetic bacterium Rhodobacter sphaeroides R26 is affected by cobalt and chromate ions stress by Cosima Damiana Calvano; Francesca Italiano; Lucia Catucci; Angela Agostiano; Tommaso R. I. Cataldi; Francesco Palmisano; Massimo Trotta (65-73).
A detailed characterization of membrane lipids of the photosynthetic bacterium Rhodobacter (R.) sphaeroides was accomplished by thin-layer chromatography coupled with matrix-assisted laser desorption ionization mass spectrometry. Such an approach allowed the identification of the main membrane lipids belonging to different classes, namely cardiolipins (CLs), phosphatidylethanolamines, phosphatidylglycerols (PGs), phosphatidylcholines, and sulfoquinovosyldiacylglycerols (SQDGs). Thus, the lipidomic profile of R. sphaeroides R26 grown in abiotic stressed conditions by exposure to bivalent cobalt cation and chromate oxyanion, was investigated. Compared to bacteria grown under control conditions, significant lipid alterations take place under both stress conditions; cobalt exposure stress results in the relative content increase of CLs and SQDGs, most likely compensating the decrease in PGs content, whereas chromate stress conditions result in the relative content decrease of both PGs and SQDGs, leaving CLs unaltered. For the first time, the response of R. sphaeroides to heavy metals as Co2+ and CrO4 2− is reported and changes in membrane lipid profiles were rationalised.
Keywords: Lipidomics; Metal stress; Rhodobacter sphaeroides; Photosynthesis; Mass spectrometry
Different iron sources to study the physiology and biochemistry of iron metabolism in marine micro-algae by Hugo Botebol; Robert Sutak; Ivo F. Scheiber; Pierre-Louis Blaiseau; François-Yves Bouget; Jean-Michel Camadro; Emmanuel Lesuisse (75-88).
We compared ferric EDTA, ferric citrate and ferrous ascorbate as iron sources to study iron metabolism in Ostreococcus tauri, Phaeodactlylum tricornutum and Emiliania huxleyi. Ferric EDTA was a better iron source than ferric citrate for growth and chlorophyll levels. Direct and indirect experiments showed that iron was much more available to the cells when provided as ferric citrate as compared to ferric EDTA. As a consequence, growth media with iron concentration in the range 1–100 nM were rapidly iron-depleted when ferric citrate—but not ferric EDTA was the iron source. When cultured together, P. tricornutum cells overgrew the two other species in iron-sufficient conditions, but E. huxleyi was able to compete other species in iron-deficient conditions, and when iron was provided as ferric citrate instead of ferric EDTA, which points out the critical influence of the chemical form of iron on the blooms of some phytoplankton species. The use of ferric citrate and ferrous ascorbate allowed us to unravel a kind of regulation of iron uptake that was dependent on the day/night cycles and to evidence independent uptake systems for ferrous and ferric iron, which can be regulated independently and be copper-dependent or independent. The same iron sources also allowed one to identify molecular components involved in iron uptake and storage in marine micro-algae. Characterizing the mechanisms of iron metabolism in the phytoplankton constitutes a big challenge; we show here that the use of iron sources more readily available to the cells than ferric EDTA is critical for this task.
Keywords: Iron; Marine micro-algae; Ferric citrate; Ferric EDTA; Ostreococcus ; Phaeodactylum ; Emiliania
Combined chelation of lead (II) by deferasirox and deferiprone in rats as biological model by F. Dahooee Balooch; S. J. Fatemi; M. Iranmanesh (89-95).
In order to investigate the capability of two chelators deferasirox (DFX or ICL670) and deferiprone (L1) in removing lead from the body, the present research was performed. Two does levels of 40 and 80 mg/kg body weight of lead (II) chloride was given to rats as biological model for 45 days. After 45 days, some toxicity symptoms were observed in rats such as loss of hair and weight, appearance of red dots around eyes, weakness and irritability. After lead application, chelation therapy with DFX and L1 as mono and combined (DFX, L1 and DFX + L1) was done for 10 days. After chelation therapy, lead level in different tissues reduced. The combined chelation therapy results showed that these chelators are able to remove lead from the body and toxicity symptoms decreased. The combined therapy results (DFX + L1) show higher efficacy and lower toxicity compared to single therapies.
Keywords: Lead toxicity; Chelation therapy; Deferasirox; Deferiprone; Rats
Plants fabricate Fe-nanocomplexes at root surface to counter and phytostabilize excess ionic Fe by P. Pardha-Saradhi; G. Yamal; Tanuj Peddisetty; P. Sharmila; Jyoti Singh; Rajamani Nagarajan; K. S. Rao (97-114).
While evaluating the impact of iron nanoparticles (NPs) on terrestrial plants we realized potential of root system of intact plants to form orange–brown complexes constituted of NPs around their roots and at bottom/side of tubes when exposed to FeCl3. These orange–brown complexes/plaques seen around roots were similar to that reported in wetland plants under iron toxicity. Transmission electron microscopy coupled with energy dispersive X-ray analysis revealed that orange–brown complexes/plaques, formed by root system of all 16 plant species from 11 distinct families tested, were constituted of NPs containing Fe. Selected area electron diffraction and powder X-ray diffraction spectra showed their amorphous nature. Thermogravimetric and fourier transform infra-red analysis showed that these Fe-NPs/nanocomplexes were composed of iron-oxyhydroxide. These plant species generated orange–brown Fe-NPs/nanocomplexes even under strict sterile conditions establishing inbuilt and independent potential of their root system to generate Fe-NPs. Root system of intact plants showed ferric chelate reductase activity responsible for reduction of Fe3+ to Fe2+. Reduction of potassium ferricyanide by root system of intact plants confirmed that root surface possess strong reducing strength, which could have played critical role in reduction of Fe3+ and formation of Fe-NPs/nanocomplexes. Atomic absorption spectrophotometric analysis revealed that majority of iron was retained in Fe-nanocomplexes/plaques, while only 2–3 % was transferred to shoots, indicating formation of nanocomplexes is a phytostabilization mechanism evolved by plants to restrict uptake of iron above threshold levels. We believe that formation of Fe-NPs/nanocomplexes is an ideal homeostasis mechanism evolved by plants to modulate uptake of desired levels of ionic Fe.
Keywords: Fe-nanoparticles; Homeostasis; Iron-oxyhydroxide; Iron-plaques; Reductases/dehydrogenases; Phytostabilization
Mouse divalent metal transporter 1 is a copper transporter in HEK293 cells by Miguel Arredondo; María José Mendiburo; Sebastián Flores; Steven T. Singleton; Michael D. Garrick (115-123).
Divalent Metal Transporter 1 (DMT1) is an apical Fe transporter in the duodenum and is involved in endosomal Fe export. Four protein isoforms have been described for DMT1, two from mRNA with an iron responsive element (IRE) and two from mRNA without it. The sets of two begin in exon 1A or 2. We have characterized copper transport using mouse 2/−IRE DMT1 during regulated ectopic expression. HEK293 cells carrying a TetR:Hyg element were stably transfected with pDEST31 containing a 2/−IRE construct. 64Cu1+ incorporation in doxycycline treated cells exhibited 18.6 and 30.0-fold increases in Cu content, respectively when were exposed to 10 and 100 μM of extracellular Cu. Cu content was ~4-fold above that of parent cells or cells carrying just the vector. 64Cu uptake in transfected cells pre-incubated with 5 μM of Cu-His revealed a Vmax and Km of 11.98 ± 0.52 pmol mg protein−1 min−1 and 2.03 ± 0.03 μM, respectively. Doxycycline-stimulated Cu uptake was linear with time. The rates of apical Cu uptake decreased and transepithelial transport increased when intracellular Cu increased. The optimal pH for Cu transport was 6.5; uptake of Cu was temperature dependent. Silver does not inhibit Cu uptake in cells carrying the vector. In conclusion, Cu uptake in HEK293 cells that over-expressed the 2/−IRE isoform of DMT1 transporter supports our earlier contention that DMT1 transports Cu as Cu1+.
Keywords: Copper; DMT1; Transport; HEK293 cells; Tetracycline regulation
Cellular localization and developmental changes of the different isoforms of divalent metal transporter 1 (DMT1) in the inner ear of rats by Dalian Ding; Richard Salvi; Jerome A. Roth (125-134).
Divalent metal transporter 1 (DMT1) is generally considered to be the major transmembrane protein responsible for the uptake of a variety of divalent cations. Four isoforms of DMT1 have been identified in mammalian cells encoded by a single gene that differ both in their N- and C-terminal sequences with two mRNA isoforms possessing an iron response element (IRE) motif downstream from the stop codon on the message. Two distinct promoter sites regulate production of the 1A or 1B isoforms (translation starts at exon 2) for both the +IRE or –IRE species of the transporter resulting in the generation of four distinct configurations of this protein. Prior studies from our laboratory using cochlear organotypic cultures isolated from postnatal day three rats (P3) have demonstrated that Mn causes significant and selective damage to sensory hair cells and auditory nerve fibers and spiral ganglion neurons in a time and concentration dependent manner. Since DMT1 plays a critical role in controlling the uptake of a variety of essential and toxic metals into the cochlea, we compared the distribution and developmental changes of the 1A, +IRE and −IRE isoforms in rat inner ear. Results reveal that all three isoforms of DMT1 are selectively expressed in different cell populations within the cochlea and, additionally, demonstrate their cellular and subcellular distribution changes with development.
Keywords: Divalent metal transporter 1 (DMT1); Cochlea; Inner ear; Hair cells; Iron; Manganese
Elevated transferrin saturation, health-related quality of life and telomere length by Arch G. Mainous III; Robert U. Wright; Mary M. Hulihan; Waleed O. Twal; Christine E. McLaren; Vanessa A. Diaz; Gordon D. McLaren; W. Scott Argraves; Althea M. Grant (135-141).
We sought to examine the relationship between elevated transferrin saturation (TS) and measures of health status (telomere length and patient-reported health-related quality of life) to assess whether elevated TS is associated with negative patient outcomes beyond increased risk for morbidity and mortality, using a cross-sectional analysis of the Hemochromatosis and Iron Overload Screening Study supplemented with assays for leukocyte telomere length in adults ≥25 years old (n = 669). Among individuals with elevated TS (≥45 % for women and ≥50 % for men), who also had a usual source of care, only 5.2 % reported ever being told by a doctor that they had an elevated iron condition. In a fully adjusted general linear regression model controlling for demographic characteristics as well as health conditions associated with iron overload, elevated TS versus non-elevated TS was associated with worse general health status (60.4 vs. 63.8, P < 0.05), mental health status (76.5 vs. 82.2, P < 0.0001) and shorter telomere length (241.4 vs. 261.3, P < 0.05). Increased surveillance of elevated TS may be in order as elevated TS is associated with decreased health status and very few patients with elevated TS are aware of their condition.
Keywords: Iron; Telomere length; Quality of life; Functional status; Health status
Demonstration of the functional role of conserved Glu-Arg residues in the Staphylococcus aureus ferrichrome transporter by Enrique D. Vinés; Craig D. Speziali; David E. Heinrichs (143-153).
The features that govern the interaction of ligand binding proteins with membrane permeases of cognate ABC transporters are largely unknown. Using sequence alignments and structural modeling based on the structure of the Escherichia coli BtuCD vitamin B12 transporter, we identified six conserved basic residues in the permease, comprised of FhuB and FhuG proteins, in the ferrichrome transporter of Staphylococcus aureus. Using alanine-scanning mutagenesis we demonstrate that two of these residues, FhuB Arg-71 and FhuG Arg-61, play a more dominant role in transporter function than FhuB Arg-74 and Arg-311, and FhuG Arg-64 and Lys-306. Moreover, we show that at positions 71 and 61 in FhuB and FhuG, respectively, arginine cannot be substituted for lysine without loss of transporter function. Previously, our laboratory demonstrated the importance of conserved acidic residues in the ferrichrome binding protein, FhuD2. Taken together, these results support the hypothesis that Glu-Arg salt bridges are critical for the interaction of the ligand binding protein with the transmembrane domains FhuB and FhuG. This hypothesis was further studied by “charge swapping” experiments whereby we constructed a S. aureus strain expressing FhuD2 with conserved residues Glu-97 and Glu-231 replaced by Arg and FhuB and FhuG with conserved basic residues Arg-71 and Arg-61, respectively, replaced by Glu. A strain containing this combination of substitutions restored partial function to the ferrichrome transporter. The results provide a direct demonstration of the functional importance of conserved basic residues on the extracellular surface of the ferrichrome permease in the Gram-positive bacterium S. aureus.
Keywords: ABC transporter; Iron-siderophore; Fhu; Protein interaction; Salt bridge
Biological evaluation of a cytotoxic 2-substituted benzimidazole copper(II) complex: DNA damage, antiproliferation and apoptotic induction activity in human cervical cancer cells by Xin Qiao; Zhong-Ying Ma; Jia Shao; Wei-Guo Bao; Jing-Yuan Xu; Zhao-Yan Qiang; Jian-Shi Lou (155-172).
Exploring novel chemotherapeutic agents is a great challenge in cancer medicine. To that end, 2-substituted benzimidazole copper(II) complex, [Cu(BMA)Cl2]·(CH3OH) (1) [BMA = N,N′-bis(benzimidazol-2-yl-methyl)amine], was synthesized and its cytotoxicity was characterized. The interaction between complex 1 and calf thymus DNA was detected by spectroscopy methods. The binding constant (K b = 1.24 × 104 M−1) and the apparent binding constant (K app = 6.67 × 106 M−1) of 1 indicated its moderate DNA affinity. Complex 1 induced single strand breaks of pUC19 plasmid DNA in the presence of H2O2 through an oxidative pathway. Cytotoxicity studies proved that complex 1 could inhibit the proliferation of human cervical carcinoma cell line HeLa in both time- and dose-dependent manners. The results of nuclei staining by Hoechst 33342 and alkaline single-cell gel electrophoresis proved that complex 1 caused cellular DNA damage in HeLa cells. Furthermore, treatment of HeLa cells with 1 resulted in S-phase arrest, loss of mitochondrial potential, and up-regulation of caspase-3 and -9 in HeLa cells, suggesting that complex 1 was capable of inducing apoptosis in cancer cells through the intrinsic mitochondrial pathway.
Keywords: Benzimidazole copper(II) complex; Single strand breaks; Reactive oxygen species; Apoptosis; Mitochondrial apoptotic pathway
Lead (Pb) and copper (Cu) share a common uptake transporter in the unicellular alga Chlamydomonas reinhardtii by Paula Sánchez-Marín; Claude Fortin; Peter G. C. Campbell (173-181).
The unicellular alga Chlamydomonas reinhardtii has a very high rate of lead (Pb) internalization and is known to be highly sensitive to dissolved Pb. However, the transport pathway that this metal uses to cross cellular membranes in microalgae is still unknown. To identify the Pb2+ transport pathway in C. reinhartdii, we performed several competition experiments with environmentally relevant concentrations of Pb2+ (~10 nM) and a variety of divalent cations. Among the essential trace metals tested, cobalt, manganese, nickel and zinc had no effect on Pb internalization. A greater than tenfold increase in the concentrations of the major ions calcium and magnesium led to a slight decrease (~34 %) in short-term Pb internalization by the algae. Copper (Cu) was even more effective: at a Cu concentration 50 times higher than that of Pb, Pb internalization by the algae decreased by 87 %. Pre-exposure of the algae to Cu showed that the effect was not due to a physiological effect of Cu on the algae, but rather to competition for the same transporter. A reciprocal effect of Pb on Cu internalization was also observed. These results suggest that Cu and Pb share a common transport pathway in C. reinhardtii at environmentally relevant metal concentrations.
Keywords: Trace metals; Microalgae; Transmembrane transport; Competition
Gold complexes with benzimidazole derivatives: synthesis, characterization and biological studies by Vinicius Zamprogno Mota; Gustavo Senra Gonçalves de Carvalho; Adilson David da Silva; Luiz Antônio Sodré Costa; Patrícia de Almeida Machado; Elaine Soares Coimbra; Carmen Veríssima Ferreira; Silvia Mika Shishido; Alexandre Cuin (183-194).
Synthesis, characterization, DFT studies and biological assays of new gold(I) and gold(III) complexes of benzimidazole are reported. Molecular and structural characterizations of the compounds were based on elemental (C, H and N) and thermal (TG–DTA) analyses, and FT-IR and UV–Visible spectroscopic measurements. The structures of complexes were proposed based DFT calculations. The benzimidazole compounds (Lig1 and Lig2) and the gold complexes were tested against three Leishmania species related to cutaneous manifestations of leishmaniasis. The free benzimidazole compounds showed no leishmanicidal activity. On the other hand, the gold(I and III) complexes have shown to possess significant activity against Leishmania in both stages of parasite, and the gold(III) complex with Lig2 exhibited expressive leishmanicidal activity with IC50 values below 5.7 μM. Also, the gold complexes showed high leishmania selectivity. The gold(I) complex with Lig1, for example, is almost 50 times more toxic for the parasite than for macrophages. Besides the leishmanicidal activity, all complexes exhibited toxic effect against SK-Mel 103 and Balb/c 3T3, cancer cells.
Keywords: Benzimidazole; Gold; Leishmania; Cancer; Cytotoxicity
Functional GFP-metallothionein fusion protein from Tetrahymena thermophila: a potential whole-cell biosensor for monitoring heavy metal pollution and a cell model to study metallothionein overproduction effects by Francisco Amaro; Aaron P. Turkewitz; Ana Martín-González; Juan Carlos Gutiérrez (195-205).
The significance of metal(oid)s as environmental pollutants has made them a priority in ecotoxicology, with the aim of minimizing exposure to animals or humans. Therefore, it is necessary to develop sensitive and inexpensive methods that can efficiently detect and monitor these pollutants in the environment. Conventional analytical techniques suffer from the disadvantages of high cost and complexity. Alternatively, prokaryotic or eukaryotic whole-cell biosensors (WCB) are one of the newest molecular tools employed in environmental monitoring that use the cell as an integrated reporter incorporating a reporter gene fused to a heavy metal responsive promoter. In the present paper, we report results from expressing, in the ciliate Tetrahymena thermophila, constructs consisting of the reporter gfp gene fused to the complete MTT1 or MTT5 protein coding regions under the transcriptional control of the MTT1 metallothionein promoter, which plays a critical role in heavy metal stress in this ciliate. When exposed to Cd2+, such cells overexpress both the GFP reporter transgene and the linked metallothionein gene. We report that, for the GFPMTT5 strain, this metallothionein overexpression results in marked resistance to cadmium toxicity (24 h LC50 ~15 μM of Cd2+), compared to wild type cells (24 h LC50 ~1.73 μM of Cd2+). These results provide the first experimental evidence that ciliate metallothioneins, like in other organisms, function to protect the cell against toxic metal ions. Because these strains may have novel advantages as WCBs, we have compared their properties to those of other previously reported Tetrahymena WCBs.
Keywords: Ciliate-metallothioneins; GFP reporter; Heavy metals; Tetrahymena thermophila ; Whole-cell biosensor
Treatment with d-penicillamine or zinc sulphate affects copper metabolism and improves but not normalizes antioxidant capacity parameters in Wilson disease by Gromadzka Grażyna; Karpińska Agata; Przybyłkowski Adam; Litwin Tomasz; Wierzchowska-Ciok Agata; Dzieżyc Karolina; Chabik Grzegorz; Członkowska Anna (207-215).
Copper accumulation in tissues due to a biallelic pathogenic mutation of the gene: ATP7B results in a clinical phenotype known as Wilson disease (WD). Aberrations in copper homeostasis can create favourable conditions for superoxide-yielding redox cycling and oxidative tissue damage. Drugs used in WD treatment aim to remove accumulated copper and normalise the free copper concentration in the blood. In the current study the effect of decoppering treatment on copper metabolism and systemic antioxidant capacity parameters was analyzed. Treatment naïve WD patients (TNWD) (n = 33), those treated with anti-copper drugs (TWD) (n = 99), and healthy controls (n = 99) were studied. Both TNWD and TWD patients characterised with decreased copper metabolism parameters, as well as decreased total antioxidant potential (AOP), glutathione (GSH) level, activity of catalase, glutathione peroxidase (GPx), and S-transferase glutathione, compared to controls. TWD patients had significantly lower copper metabolism parameters, higher total AOP and higher levels of GSH than TWD individuals; however, no difference was observed between these two patient groups with respect to the rest of the antioxidant capacity parameters. Patients who had undergone treatment with d-penicillamine or zinc sulphate did not differ with respect to copper metabolism or antioxidant capacity parameters, with the exception of GPx that was lower in d-penicillamine treated individuals. These data suggest that anti-copper treatment affects copper metabolism as well as improves, but does not normalize, natural antioxidant capacity in patients with WD. We propose to undertake studies aimed to evaluate the usefulness of antioxidants as well as selenium as a supplemental therapy in WD.
Keywords: Antioxidants; Copper; d-Penicillamine; Glutathione peroxidase; Oxidative stress; Treatment; Wilson disease; Zinc sulphate
Erratum to: Treatment with d-penicillamine or zinc sulphate affects copper metabolism and improves but not normalizes antioxidant capacity parameters in Wilson disease by Grażyna Gromadzka; Agata Karpińska; Adam Przybyłkowski; Tomasz Litwin; Agata Wierzchowska-Ciok; Karolina Dzieżyc; Grzegorz Chabik; Anna Członkowska (217-217).