Immuno-biochemical findings in groups of individuals occupationally and non-occupationally exposed to emissions containing nickel and cobalt

Immune reactions elicited in the sera of individuals exposed to nickel and cobalt were assessed by changes in the concentration of serum immunoglobulins IgG, IgA and IgM and serum proteins alpha 2 macroglobulin (A2M), transferrin (TRF), alpha 1-antitrypsin (A1AT), ceruloplasmin (CPL) and lysozyme (LYS). Examinations were carried out in workers occupationally exposed to Ni (38 individuals) or Co (35 individuals) and in groups of non-occupationally exposed children living in areas with a different degree of air pollution from a nearby source of Ni and Co emissions (one group was made up of 54 exposed children, the other one of 64 "less exposed" children of the same age). Groups of non-exposed controls were represented by a group of 42 male adults matched by age and by a group of 48 children from a non-polluted area. Significantly increased average values were obtained for IgG, IgA and IgM in group of workers exposed to Ni, for IgA in workers exposed to Co and for A1AT, A2M, CPL and LYS in both groups of occupationally exposed adults (p less than 0.001 - p less than 0.005). Among non-occupationally exposed children the group of the most exposed had significantly elevated average values for A2M and A1AT which were higher than those recorded in groups of "less exposed" and control children (p less than 0.02 and p less than 0.05, respectively). The biomedical importance of these findings is discussed in detail.     

Assessment of cytogenetic damage in lymphocytes and in exfoliated nasal cells of dental laboratory technicians exposed to chromium, cobalt, and nickel

Dental laboratory technicians may be exposed to metal alloys that are used in the production of crowns, bridges and removable partial dentures. These alloys consist of 35–65% cobalt, 20–30% chromium, 0–30% nickel, and small amounts of molybdenum, silica, beryllium, boron and carbon. The aim of this study was to assess whether dental technicians are occupationally exposed to chromium, cobalt and nickel, by analyzing urinary excretion levels of these metals and to investigate the genotoxic effects of occupational exposure associated with dental prostheses production operations by analyzing cytokinesis-blocked micronucleus (CB-MN) frequencies in peripheral lymphocytes and micronucleus (MN) frequencies in exfoliated nasal cells from 27 dental laboratory technicians and 15 control subjects. The differences in the urinary excretion of metals between technicians and controls were statistically significant. The mean (±S.D.) CB-MN frequencies (‰) in peripheral lymphocytes were 4.00 (±2.98) among the dental technicians and 1.40 (±1.30) among the controls, a statistically significant difference (P<0.005). The mean (±S.D.) MN frequencies (‰) in nasal cells were 3.50 (±1.80) among the dental technicians and 1.19 (±0.53) among the controls, which was also a statistically significant difference (P<0.005). There was a significant correlation between duration of exposure and MN frequencies in lymphocytes (r=0.642, P<0.01), but not in nasal cells of technicians. Our data reveal that in vivo exposure to chromium, nickel and cobalt metals is evident and that this occupational exposure may contribute to the observed genotoxic damage in two types of cells, e.g. lymphocytes and exfoliated nasal cells. However, it cannot be determined which compound(s) are responsible for the genotoxic damage observed in this study.     

Assessment of cytogenetic damage in lymphocytes and in exfoliated nasal cells of dental laboratory technicians exposed to chromium,cobalt, and nickel

The alkaline comet assay is able to identify in individual cells DNA strand breaks associated with different processes. Topoisomerase inhibitors, some of which are used as chemotherapeutic agents, stabilise topoisomerase-DNA cleavable complexes by stimulating DNA strand cleavage and inhibiting religation. This can result in the activation of stress-associated signalling pathways, inducing cell cycle arrest and activation of the biochemical cascade of apoptosis. The aim of our study was to assess the ability of the comet assay to detect stabilisation of cleavable complexes and induction of apoptosis by two topoisomerase II inhibitors, etoposide and ellipticine, and two topoisomerase I inhibitors, camptothecin and topotecan. The study was carried out on Chinese hamster ovary (CHO) cells, DC3F cells and DC3F/C-10, its camptothecin-resistant counterpart. The comet assay was able to identify stabilised cleavable complexes through the presence of DNA strand breaks after 1h treatment that disappeared within 24h after drug removal. Kinetics studies allowed to discriminate between these early DNA damages and DNA fragmentation related to apoptosis characterised by reappearance of DNA strand breaks 48h after treatment.     

Characteristics of the development of radiation sickness in guinea pigs exposed to non-uniform irradiation in highly lethal doses

Certain peculiarities have been revealed in the development of radiation sickness in guinea pigs subjected to nonuniform irradiation with superlethal doses. With electron and gamma-neutron radiation LD50/1.5 was 116.11 and 114.48 Gy respectively, when delivered to whole body, and 133.40 and 111.72 Gy when delivered to the posterior part of the body.     

Acquisition of lethal doses of Beauveria bassiana conidia by western flower thrips, Frankliniella occidentalis, exposed to foliar spray residues of formulated and unformulated conidia

Secondary acquisition of Beauveria bassiana conidia was recorded on the whole bodies and selected body parts of second-instar nymphs and adult female western flower thrips exposed to foliar spray residues of three differently formulated conidial preparations, for 24 h. Conidia were formulated in emulsifiable oil or with clay (wettable powder), or were essentially unformulated conidia (technical grade powder suspended in water with a surfactant). Formulation had no significant effect on dose acquisition and no effect on virulence of acquired conidia. The mean nymphal LC50/LD50 was 116 conidia/mm2 and 52conidia/insect, respectively; the values for adults were 19 conidia/mm2 and 5conidia/insect. Greatest numbers of conidia were recorded on the legs and abdomens of nymphs and on the legs, wings, and thoraces of adults. As would be expected, numbers of conidia acquired increased with residue concentration (application rate). However, an inverse relationship was noted between acquisition rate (conidia acquired/total conidia applied) and residue concentration. The mechanism underlying this response was not determined. However, there was no indication that any body parts (e.g., tarsi) became saturated with spores, which suggests that either the thrips were repelled by the conidial residues or that as the concentrations of conidia on the substrate increased, conidia somehow became more difficult to acquire. Slopes of the LC probit regressions were lower than those of the LD regressions (mean 1.14 vs 1.78), suggesting that the low slopes often obtained in fungal pathogen assays could be partly an artifact of unequal rates of dose acquisition at low vs high application rates.     

Studies of Zn, Mg, Cu, Ca and Fe in cadmium poisoned toads before and after treatment with EDTA

Zn, Mg, Cu, Ca and Fe were determined spectrophotometrically in liver, kidneys, muscle, spleen and blood of Bufo regularis after a single i.m. injection of 6.2 mg Cd/kg (which represents the 96 hr LD50) alone or in combination with 40 mg EDTA/kg (the minimal EDTA concentration causing 100% survival over that period). Cadmium administration caused recognizable effects on the essential metals levels in different tissues and organs. In the majority of the tissues and organs studied, zinc and copper concentrations returned to their normal ranges in animals that received both cadmium and EDTA. In contrast, magnesium, calcium and iron contents not only returned back to their control values but also exceeded them.     

Redistribution of cobalt and nickel in detached wheat shoots: effects of steam-girdling and of cobalt and nickel supply

Detached wheat shoots (ear with peduncle and flag leaf) were incubated for 4 d in a solution containing 1 mM RbCl and 1 mM SrCl2 as well as 10, 40 or 160 μM NiCl2 and CoCl2. The phloem of some plants was interrupted by steam-girdling the stem below the ear to distinguish between xylem and phloem transport. The phloem-immobile Sr flowed mainly to the leaf lamina and to the glumes via the xylem. The Sr transport was not sensitive to steam-girdling. In contrast, the phloem-mobile Rb accumulated during the incubation time mainly in the stem and the leaf sheath. The Rb transport to the grains was impaired by steam-girdling as well as by elevated Ni and Co concentrations in the incubation solution indicating that Rb was transported via the phloem to the maturing grains and that this transport was affected by the heavy metals. Ni was removed more efficiently from the xylem in the peduncle than Co (but far less efficiently than Rb). It became evident that the two heavy metals can also be transferred from the xylem to the phloem in the stem of wheat and reach the maturing grains via the phloem. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cytogenetic analysis in workers occupationally exposed to nickel carbonyl

Chromosomal aberration and sister-chromatid exchange (SCE) base-line frequencies and SCE frequencies induced by 10 ng/ml mitomycin C (MMC) were analysed in cultured peripheral lymphocytes of 65 workers occupationally exposed to nickel carbonyl Ni(CO)4. The subjects were divided into 4 groups: (1) control; (2) exposed to nickel carbonyl (= exposed); (3) cigarette smokers; (4) smoking-exposed. The results show that there are no significant differences in chromosomal aberration frequencies, breaks or gaps, between the various groups. However, the SCE base-line frequency of the smoking-exposed group, with an average of 7.7/cell, was significantly higher than that of the control group, with an average of 6.5/cell (P less than 0.01), and also than that of the exposed group with an average of 5.9/cell (P less than 0.01). Similarly, the SCE frequency induced by 10 ng/ml MMC in the smoking-exposed group which averaged 15.5/cell was significantly higher than that of the control group (average of 13.2/cell (P less than 0.05], and also than that of the exposed group with an average of 12.3/cell (P less than 0.01). Under our experimental conditions, it may be that the level of exposure was not high enough to elicit an increase in chromosomal aberrations and SCE frequencies in the non-smoker exposed group. The fact that an increase in SCE frequencies was only found in the smoking-exposed group implies that the two factors, smoking and exposure to nickel carbonyl, are jointly responsible for the result.     

Comparative studies of nickel,cobalt, and copper uptake by some nickel hyperaccumulators of the genus Alyssum

The uptake of Ni, Co, and Cu by the nickel hyperaccumulator Alyssum troodii Boiss and the non-accumulator Aurinia saxatilis (L.) Desv. were studied in pot trials using artificial rooting media with varying concentrations of the metals added as soluble salts, singly and in combination. The ability of five other Ni hyperaccumulating species of Alyssum to hyperaccumulate Co was also investigated.Leaves and stems of A. troodii accumulated Ni to almost the same extent (8000–10 000 g g^-1). In roots, the highest Ni concentration was 2000 g g^-1. In leaves of Au. saxatilis, the maximum Ni concentration was only 380 g g^-1 and the level in roots was even lower.In media containing Co, the maximum concentration of this element in A. troodii (2325 g g^-1) was ten times higher than in the non-accumulator species. Slightly less Co was found in stems and roots of both species. Among the other Ni hyperaccumulators, the maximum concentration of Co in leaves ranged from about 1000–8000 g g^-1.Copper concentrations were the same in all organs of both species when they were grown in copper-rich media and were in the range 40–80 g g^-1, showing that neither plant was capable of taking up Cu at levels comparable to those of Ni and Co.When both plants were grown in media containing equal amounts of both Co and Ni, the Co concentrations in plant organs were the same as for specimens grown in media containing Co only. However, the Ni levels were lower in both species. Uptake of Co therefore appeared to suppress Ni uptake.Pot trials showed that the order of tolerance was Ni>Cu>Co for A. troodii and Ni>CoCu for Au. saxatilis, whereas the seedling tests showed the order to be Co>Ni>Cu. At metal concentrations 10 000 g g^-1, the overall tolerance of A. troodii was greater than that of Au. saxatilis which exhibited equally low tolerance to Ni and Cu.We conclude that in A. troodii, A. corsicum Duby, A. heldreichii Hausskn., A. murale Waldstein & Kitaibel, A. pintodasilvae T.R. Dudley, and A. tenium Hálácsy, Ni tolerance and hyperaccumulation conveys the same character towards Co. This behaviour should be investigated in other hyperaccumulators of Ni and/or Co.     

Metal uptake,antioxidant status and membrane potential in maize roots exposed to cadmium and nickel

Root growth of the seedlings of maize cultivars Premia and Blitz exposed to 2 μM cadmium (Cd), nickel (Ni) or both metals acting simultaneously (Cd + Ni) for 72 h was significantly reduced but not ceased. The effect was more pronounced in the seedlings of the cv. Blitz. The heavy metals (HMs) contents increased significantly in the roots. Simultaneous application of metals had an antagonistic effect on either Cd or Ni uptake in Premia but not in Blitz. In control roots the contents of ascorbic acid (AsA) and dehydroascorbic acid (DHA) were lower and gluthatione (GSH) content was higher in Premia than in Blitz. A decrease of AsA content was induced by all metal treatments in Premia but only by Cd + Ni in Blitz while an increase was induced by single metals in this cultivar. All metal treatments increased DHA contents in both cultivars. GSH content decreased significantly in Premia treated with Cd or Cd + Ni, and in Blitz treated with Ni. Unlike the contents of AsA, DHA and GSH, the increased metal concentrations in root cells did not affect the membrane potential (E _M). The changes in antioxidant contents depended on both, maize genotypes and HMs treatments. Nevertheless, the results indicated a role of antioxidative system in minimizing the effects of oxidative stress and protecting cell membranes in both maize cultivars.     

Cytogenetic effects in children exposed to low doses of ionizing radiation

The obtained data indicate that frequencies of different types of cytogenetic anomalies in investigated children groups living in radionuclide contaminated territories and children irradiated in utero have complicated patterns. The frequency of chromosomal anomalies in the investigated groups of children exceeds the average population level. At the same time, no statistically significant differences in frequencies of various types aberrations between groups of children were revealed.     

Comparative genomic analyses of nickel, cobalt and vitamin B12 utilization

Background

Nickel (Ni) and cobalt (Co) are trace elements required for a variety of biological processes. Ni is directly coordinated by proteins, whereas Co is mainly used as a component of vitamin B₁₂. Although a number of Ni and Co-dependent enzymes have been characterized, systematic evolutionary analyses of utilization of these metals are limited.

Results

We carried out comparative genomic analyses to examine occurrence and evolutionary dynamics of the use of Ni and Co at the level of (i) transport systems, and (ii) metalloproteomes. Our data show that both metals are widely used in bacteria and archaea. Cbi/NikMNQO is the most common prokaryotic Ni/Co transporter, while Ni-dependent urease and Ni-Fe hydrogenase, and B₁₂-dependent methionine synthase (MetH), ribonucleotide reductase and methylmalonyl-CoA mutase are the most widespread metalloproteins for Ni and Co, respectively. Occurrence of other metalloenzymes showed a mosaic distribution and a new B₁₂-dependent protein family was predicted. Deltaproteobacteria and Methanosarcina generally have larger Ni- and Co-dependent proteomes. On the other hand, utilization of these two metals is limited in eukaryotes, and very few of these organisms utilize both of them. The Ni-utilizing eukaryotes are mostly fungi (except saccharomycotina) and plants, whereas most B₁₂-utilizing organisms are animals. The NiCoT transporter family is the most widespread eukaryotic Ni transporter, and eukaryotic urease and MetH are the most common Ni- and B₁₂-dependent enzymes, respectively. Finally, investigation of environmental and other conditions and identity of organisms that show dependence on Ni or Co revealed that host-associated organisms (particularly obligate intracellular parasites and endosymbionts) have a tendency for loss of Ni/Co utilization.

Conclusion

Our data provide information on the evolutionary dynamics of Ni and Co utilization and highlight widespread use of these metals in the three domains of life, yet only a limited number of user proteins.     

Plasma lipid peroxidation and erythrocyte antioxidants status in workers exposed to nickel

The objectives were to investigate the plasma lipid peroxidation and erythrocyte antioxidants status in workers exposed to nickel. The study groups comprised 69 nickel plating workers and 50 office workers residing in the same city, but away from the place of work of the study group subjects, considered as control group. Urinary nickel concentration was determined by graphite furnace atomic absorption spectrophotometry. The plasma lipid peroxidation and erythrocyte antioxidants were measured by spectrophotmetric methods. The plasma lipid peroxidation level was significantly increased in nickel-platers and their helpers as compared with controls. Erythrocyte antioxidants were significantly decreased in the nickel-platers compared with the controls. The level of plasma lipid peroxidation was positively and erythrocyte antioxidants were negatively and significantly correlated with the urine nickel levels. Multiple regression analysis assessed the oxidative stress associated with nickel and other potential confounding factors such as body mass index, the consumption of green vegetables, coffee, tea, smoking and alcohol consumption. Analysis showed that the lifestyle confounding factors: the consumption of green vegetables, smoking and alcohol, were not significantly associated with oxidative stress. The exposure to nickel, body mass index and coffee consumption were significantly associated with oxidative stress. The results show that the increased plasma lipid peroxidation and decreased erythrocyte antioxidants levels observed in nickel-exposed workers could be used as biomarkers of oxidative stress.     

Plasma lipid peroxidation and erythrocyte antioxidants status in workers exposed to nickel

The objectives were to investigate the plasma lipid peroxidation and erythrocyte antioxidants status in workers exposed to nickel. The study groups comprised 69 nickel plating workers and 50 office workers residing in the same city, but away from the place of work of the study group subjects, considered as control group. Urinary nickel concentration was determined by graphite furnace atomic absorption spectrophotometry. The plasma lipid peroxidation and erythrocyte antioxidants were measured by spectrophotmetric methods. The plasma lipid peroxidation level was significantly increased in nickel-platers and their helpers as compared with controls. Erythrocyte antioxidants were significantly decreased in the nickel-platers compared with the controls. The level of plasma lipid peroxidation was positively and erythrocyte antioxidants were negatively and significantly correlated with the urine nickel levels. Multiple regression analysis assessed the oxidative stress associated with nickel and other potential confounding factors such as body mass index, the consumption of green vegetables, coffee, tea, smoking and alcohol consumption. Analysis showed that the lifestyle confounding factors: the consumption of green vegetables, smoking and alcohol, were not significantly associated with oxidative stress. The exposure to nickel, body mass index and coffee consumption were significantly associated with oxidative stress. The results show that the increased plasma lipid peroxidation and decreased erythrocyte antioxidants levels observed in nickel-exposed workers could be used as biomarkers of oxidative stress.     

Inhibition of ribonuclease and protease activities in germinating rice seeds exposed to nickel

When the seeds of two rice cvs. Malviya-36 and Pant-12 were germinated up to 120 h in the presence of 200 and 400 μM NiSO₄, a significant reduction in the germination of seeds occurred. Seeds germinating in the presence of 400 μM NiSO₄ showed about 12–20% decline in germination percent, about 20–53% decline in lengths and about 8–34% decline in fresh weights of roots and shoots at 120 h of germination. Ni²⁺ exposure of germinating seeds resulted in apparent increased levels of RNA, soluble proteins, and free amino acids in endosperms as well as embryo axes. A 400 μM Ni²⁺ treatment led to about 58–101% increase in the level of soluble proteins and about 39–107% increase in the level of free amino acids in embryo axes at 96 h of germination. Activities of ribonuclease and protease declined significantly with increasing levels of Ni²⁺ treatment. Isoenzyme profile of RNase as revealed by activity staining indicated decline in the intensities of 3–4 preexisting enzyme isoforms in embryo axes of both the rice cultivars and disappearance of one of the two isoforms in endosperms of cv. Pant-12 due to 400 μM Ni²⁺ treatment. Results suggest that the presence of high level of Ni²⁺ in the medium of germinating rice seeds serves as a stress factor resulting in decreased hydrolysis as well as delayed mobilization of endospermic RNA and protein reserves and causing imbalance in the level of biomolecules like RNA, proteins, and amino acids in growing embryo axes. These events would ultimately contribute to decreased germination of rice seeds in high Ni²⁺ containing environment.     

The assessment of the antibacterial and antifungal activities of aspirin, EDTA and aspirin–EDTA combination and their effectiveness as antibiofilm agents

Aims:  To evaluate the antimicrobial activities of aspirin, EDTA and an aspirin-EDTA (A-EDTA) combination against Pseudomonas aeruginosa , Escherichia coli and Candida albicans in planktonic and biofilm cultures.
Methods and Results:  Minimal inhibitory concentrations (MIC) and minimal biocidal concentrations (MBC) were determined using twofold broth microdilution and viable counting methods, respectively. Aspirin's recorded MIC values ranged from 1·2 to 2·7 mg ml⁻¹. Checkerboard assay demonstrated a synergism in antimicrobial activity upon combination. Aspirin's minimal biofilm eradication concentration values (MBEC) against the established biofilms ranged between 1·35 and 3·83 mg ml⁻¹. A complete eradication of bacterial biofilms was achieved after a 4-h treatment with the A-EDTA combination.
Conclusion:  Both aspirin and EDTA possess broad-spectrum antimicrobial activity for both planktonic and biofilm cultures. Aspirin used at the MBEC for 24 h was successful in eradicating P. aeruginosa , E. coli and C. albicans biofilms established on abiotic surfaces. Moreover, the exposure to the A-EDTA combination (4 h) effected complete bacterial biofilm eradication.
Significance and Impact of the Study:  There is a continuous need for the discovery of new antimicrobial agents. Aspirin and EDTA are 'nonantibiotic drugs', the combination of which can be used successfully to treat and eradicate biofilms established on abiotic surfaces.