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1.
A new ligand N-salicyloyl-N'-o-hydroxythiobenzhydrazide (H2Sotbh) forms complexes [Mn(HSotbh)2], [Fe(Sotbh-H)(H2O)2], [M(Sotbh)] [M=Co(II), Cu(II) and Zn(II)] and [Ni(Sotbh)(H(2)O)2], which were characterized by various physico-chemical techniques. M?ssbauer spectrum of [Fe(Sotbh-H)(H2O)2] reveals the quantum admixture of 5/2 and 3/2 spin-states. Mn(II), Cu(II) and Ni(II) complexes were observed to inhibit the growth of tumor in vitro, whereas, Fe(III), Co(II), Zn(II) complexes did not. In vivo administration of Mn(II), Cu(II) and Ni(II) resulted in prolongation of survival of tumor bearing mice. Tumor bearing mice administered with Mn(II), Cu(II) and Ni(II) complexes showed reversal of tumor growth associated induction of apoptosis in lymphocytes. The paper discusses the possible mechanisms and therapeutic implication of the H2Sotbh and its metal complexes in tumor regression and tumor growth associated immunosuppression.  相似文献   

2.
A simple, rapid, sensitive and inexpensive approach is described in this work based on a combination of solid-phase extraction of 8-hydroxyquinoline (8HQ), for speciation and preconcentration of Cr(III) and Cr(VI) in river water, and the direct determination of these species using a flow injection system with chemiluminescence detection (FI–CL) and a 4-diethylamino phenyl hydrazine (DEAPH)–hydrogen peroxide system. At different pH, the two forms of chromium [Cr(III) and Cr(VI)] have different exchange capacities for 8HQ, therefore two columns were constructed; the pH of column 1 was adjusted to pH 3 for retaining Cr(III) and column 2 was adjusted to pH 1 for retaining of Cr(VI). The sorbed Cr(III) and Cr(VI) species were eluted from columns using 3.0 ml of 0.1 N of HCl and 3.0 ml of 0.1 N of NaOH, respectively. The flow injection–chemiluminescence (FI–CL) method is based on light emitted due to the oxidation of DEAPH by the H2O2 in the presence of Cr(III), which catalyzes the reaction. The flow cell is a transparent coiled tube made from glass (2.0 × 4.0, inner and outer diameter) and located close to the photodetector. The flow parameters: flow rate, sample volume, flow cell length, and distance to the CL detector were studied and optimized. Under optimum flow conditions, the Cr(III) concentration can be determined over the range 5–350 μg L−1 with a limit of detection of 1.2 μg L−1, as the Cr(III) concentration is proportional to the intensity of the CL signal. The relative standard deviations (%) for 10 and 50 μg L−1 Cr(III) were 1.2% and 3.2%, respectively. The effects of Al(III), Cd(II), Zn(II), Hg(II), Pb(II), Co(II), Cu(II), Ni(II), Mn(II), Ca(II), and Fe(III) were investigated. The proposed method is highly selective and sensitive, enabling a rapid determination of the Cr(III) amount in the presence of other interfering metals. Finally, the FI–CL method was examined in five river water samples with excellent recoveries.  相似文献   

3.
Hexavalent chromium (Cr[VI]) is an industrial waste product known to cause nasal and lung cancer in exposed workers. Intracellularly, Cr[VI] undergoes a series of enzymatic reductions resulting in the formation of reactive chromate intermediates and oxygen free radicals. These metabolites react with DNA to cause numerous types of genomic lesions, but the cellular response to these genotoxic insults is poorly understood. Recently, we demonstrated that in response to DNA damage induced by Cr[VI], an ataxia-telangiectasia mutated (ATM) and structural maintenance of chromosomal protein 1 (SMC1)-dependent S-phase checkpoint is activated. Interestingly, this checkpoint response was only ATM-dependent in cells exposed to low doses of Cr[VI], we demonstrate that the ATM and Rad3 related kinase, ATR, is required to activate the S-phase checkpoint. In response to all doses of Cr[VI], ATR is activated and phosphorylates SMC1 to facilitate the checkpoint. Further, chromatin binding ability of Rad17 is required for this process. Taken together, these results indicate that the Rad17-ATR-SMC1 pathway is essential for Cr[VI]-induced S-phase checkpoint activation.  相似文献   

4.
Park D  Yun YS  Yim KH  Park JM 《Bioresource technology》2006,97(14):1592-1598
In this study, the removal of Cr(VI) was examined in a binary aqueous system containing Ni(II), and the competitive interaction between them was successfully modeled. The removal rate of Cr(VI) was unaffected by the presence of Ni(II). However, in an equilibrium state, the uptake of total Cr or Ni(II) was decreased in the presence of the other metal. The mono- and multi-component Langmuir adsorption models clearly represented the uptake behavior of these metals.  相似文献   

5.
Chromate-resistant Chlorella spp. isolated from effluents of electroplating industry could grow in the presence of 30 μM K2Cr2O7. Since photosynthesis is sensitive to oxidative stress, chromate toxicity to photosynthesis was examined in this algal isolate. Chromate [Cr(VI)] up to 100 μM was found to stimulate photosynthesis, while 90% inhibition was found, when the cells were incubated with 1 mM Cr(VI) for 4 h. Photosystem (PS) II was inhibited by 80% and PSI by 40% after such Cr(VI) treatment. Thermoluminescence studies on cells treated with 1 mM Cr(VI) for 4 h showed that S2QA ? recombination peak (Q) was shifted to higher temperature, whereas S2/S3QB ? recombination peak (B) was shifted to lower temperature. These shifts indicated alga stress response in order to overcome an excitation stress resulting from the inhibition of photosynthesis by Cr(VI). The nontreated Chlorella cells kept in the dark showed periodicity of four for the Q peak (4–8°C) and B peak (34–38°C) after exposure to series of single, turnover, saturating flashes. This periodicity was lost in Cr(VI)-treated cells. Higher concentrations of Cr(VI) inhibited mainly the electron flow in the electron transport chain, inactivated oxygen evolving complex, and affected also Calvin cycle enzymes in the Cr(VI)-resistant isolates of Chlorella.  相似文献   

6.
7.
The possible mechanisms by which various metals exert their mutagenic effects were investigated using both chemical and biochemical techniques. Ions of Cu, Ni and Cr enhanced the release of either adenine [Cu(II) and Ni(II)] or guanine [Cr(VI)] from DNA as measured in a chromatography assay, suggesting the possible importance of depurination in metal-induced mutagenesis. Transfection experiments with single-stranded bacteriophage phi X174 DNA indicated that micromolar levels of Cu(II), Cr(III), Cr(VI) and Pt(IV) are capable of causing extensive lethal damage to the phage DNA. In case of Cu(II) and Pt(IV) this damage proved mutagenic for phi X174 am3 after transfection of DNA into SOS-induced spheroplasts. For Cu(II) mutagenesis is likely due to the release of adenine residues from the phage DNA based on the abolishment of mutagenesis by alkali and the observed specificity of the phage revertants. The enhancement of the adenine depurination rate by Cu(II) was estimated to be as high as 10,000-fold.  相似文献   

8.
Mechanistic insights into Cr(VI)-induced carcinogenicity and possible implication of Cr(V) species formed by the redox reactions of chromium-bearing species have attracted interest. We have previously demonstrated that when human peripheral blood lymphocytes are exposed to the Cr(V) complexes, viz., sodium bis(2-ethyl-2-hydroxybutyrato)oxochromate(V), Na[Cr(V)O(ehba)(2)] and sodium bis(2-hydroxy-2-methylbutyrato)oxochromate(V), Na[Cr(V)O(hmba)(2)], apoptosis and formation of reactive oxygen species (ROS) are observed. The molecular mechanisms involving cellular signaling pathways leading to apoptosis are addressed in the present study. Treatment of lymphocytes with Na[Cr(V)O(ehba)(2)] and K(2)Cr(2)O(7) leads to the activation of the Src-family protein tyrosine kinases namely, p56(lck), p59(fyn), and p56/53(lyn), which then activates caspase-3, both of which are under the partial influence of ROS. Inhibition of the Src-family tyrosine kinases activity by PP2 and of caspase-3 by Z-DEVD-FMK reverses apoptosis, thereby suggesting their importance. Antioxidants only partially reverse the apoptosis induced by Cr(VI/V), suggesting that pathways other than those induced by ROS cannot be ruled out. Although the complex, Na[Cr(V)O(ehba)(2)] is known to be relatively stable in aqueous solutions, previous studies have shown that the Cr(V) complex, Na[Cr(V)O(ehba)(2)] disproportionates to Cr(VI) and Cr(III) forms at pH 7.4 through complex mechanistic processes. Dynamics studies employing EPR data show that the Cr(V) state in Na[Cr(V)O(ehba)(2)] is relatively more stable in RPMI-1640 medium containing plasma. Formation of ROS during the reaction of redox partners with Na[Cr(V)O(ehba)(2)] is an early event and compares favorably in kinetic terms with the reported rate processes for disproportionation. This investigation presents evidence for the direct implication of Cr(V) in Cr(VI)-induced apoptosis of lymphocytes.  相似文献   

9.
Cr(VI) compounds have been declared as a potent occupational carcinogen by IARC (1990) through epidemiological studies among workers in chrome plating, stainless-steel, and pigment industries. Studies relating to the role of intermediate oxidation states such as Cr(V) and Cr(IV) in Cr(VI)-induced carcinogenicity are gaining importance. In this study, issues relating to toxicity elicited by Cr(V) have been addressed and comparisons made with those relating to Cr(VI) employing human peripheral blood lymphocytes. Lymphocytes have been isolated from heparinized blood by Ficoll-Hypaque density gradient centrifugation and exposed to Cr(V) complexes viz. sodium bis(2-ethyl-2-hydroxybutyrato)oxochromate(V), Na[Cr(V)O(ehba)(2)], 1 and sodium bis(2-hydroxy-2-methylbutyrato)oxochromate(V), Na[Cr(V)O(hmba)(2)], 2 and Cr(VI). The phytohemagglutinin (PHA)-induced proliferation of lymphocytes has been found to be inhibited by the two complexes of Cr(V) and chromate Cr(VI) in a time- and concentration-dependent manner. Viability of cells decreases in the presence of Cr(V). Apoptosis appears to be the mode of cell death in the presence of both Cr(V) and Cr(VI). Pretreatment of cells with antioxidants before exposure to chromium(V) complexes reverse apoptosis partially. Possibility for the formation and implication of reactive oxygen species in Cr(V)-induced apoptosis of human lymphocyte cells has been indicated in this investigation. The intermediates of Cr(V) and radical species in the biotoxic pathways elicited by Cr(VI) seems feasible.  相似文献   

10.
Heavy metal contamination of water bodies has been a cause of grave concern around the globe. Analysis of various industrial effluents has revealed a perilous level of Cr (VI) and Ni (II). Pseudomonas aeruginosa is an extracellular polymeric substances (EPSs) producing bacterium. EPS has a great potential in the sequestration of heavy metal ions. In the present study efforts have been made to understand the effect of time, pH, and temperature on production of EPS by P. aeruginosa (MTCC 1688). The extracted EPS has been applied for removal of Ni (II) and Cr (VI) ions from aqueous system. The results revealed that highest EPS yield (26 mg/50 mL) can be obtained after 96 h of incubation at pH 6 and 32 °C temperature in 50 mL of culture. Treatment of 10 mg/L Cr (VI) and Ni (II) with 30 mg/L EPS resulted in the removal of 26% and 9% of Cr (VI) and Ni (II), respectively. Fourier-transform infrared spectral analysis revealed the involvement of –OH, –NH, C–O, diketone, and ester functional groups of EPS in the attachment of Cr (VI) ion while involvement of amide and –CO groups in Ni (II) binding with EPS. Scaling-up the production of EPS using bioreactor may further help in developing an efficient process for treatment of water polluted with Cr and Ni.  相似文献   

11.
Sodium dichromate [Cr(VI)] and cadmium chloride [Cd(II)] are both cytotoxic and mutagenic. This study examined the toxic and apoptotic potentials of these two cations on three cell types in vitro, namely, human chronic myelogenous leukemic (CML) K562 cells, promyelocytic leukemic HL-60 cells, and normal human peripheral blood mononuclear cells. The cells were incubated with 0-100 microM concentrations of the two cations for 0, 24, or 48 hours at 37 degrees C. Both Cr(VI) and Cd(II) induced changes in intracellular oxidized states of cells, which were detected using laser scanning confocal microscopy. Cell cycle modulation and apoptosis of the K562 cells by Cr(VI) and Cd(II) were determined by flow cytometry. Significant decreases in the G2/M phase were observed in the Cr(VI) and Cd(II) treated CML cells compared with untreated cells. At 12.5 microM, Cr(VI) induced greater apoptosis in K562 cells as compared with Cd(II). In the K562 cells, 2.2- and 3.0-fold increases in DNA fragmentation were observed following incubation with 12.5 and 25 microM Cr(VI), respectively, and 1.2- and 1.7-fold increases in DNA fragmentation were observed with Cd(II). Furthermore, approximately 2.7- and 4.9-fold increases in cytochrome c reduction were observed following incubation with 12.5 and 25 microM Cr(VI), respectively, and 1.6- and 3.3-fold increases in cytochrome c reduction were observed with Cd(II), demonstrating enhanced production of superoxide anion. Approximately 3.1 to 6-fold increases in hydroxyl radical production were observed following incubation of the K562 cells with these cations at 12.5 and 25 microM concentrations. These results in K562 cells were compared with promyelocytic leukemic HL-60 cells and normal human peripheral blood mononuclear cells. More pronounced effects were observed on K562 and HL-60 cells, and much lesser effects were observed on normal human peripheral blood mononuclear cells. The results demonstrate that both cations are toxic, producing oxidative tissue damage and apoptosis. Furthermore, more drastic effects were observed on K562 and HL-60 cells as compared with normal human peripheral blood mononuclear cells.  相似文献   

12.
Apricot stones were carbonised and activated after treatment with sulphuric acid (1:1) at 200 degrees C for 24 h. The ability of the activated carbon to remove Ni(II), Co(II), Cd(II), Cu(II), Pb(II), Cr(III) and Cr(VI) ions from aqueous solutions by adsorption was investigated. Batch adsorption experiments were conducted to observe the effect of pH (1-6) on the activated carbon. The adsorptions of these metals were found to be dependent on solution pH. Highest adsorption occurred at 1-2 for Cr(VI) and 3-6 for the rest of the metal ions, respectively. Adsorption capacities for the metal ions were obtained in the descending order of Cr(VI) > Cd(II) > Co(II) > Cr(III) > Ni(II) > Cu(II) > Pb(II) for the activated carbon prepared from apricot stone (ASAC).  相似文献   

13.
Many kinds of biomass are being tested as a biosorption material for metal removal from the contaminated waters. In the present study the biosorption capacity of an organic solvent tolerant (OST) bacterium was investigated against Cr(VI) and Ni(II). The OST strain of Pseudomonas fluorescens TEM08 was isolated from an oil contaminated soil sample and grown in normal culture conditions (type I) and in the presence of the cyclohexane (type II). Two types of cells were used in the biosorption experiments to compare the organic solvent effect on the biosorption capacity. The biosorption equilibrium was described by Langmuir and Freundlich adsorption isotherms. The value of Q(0) was higher for type I cells (40.8 for Cr(VI); 12.4 for Ni(II)) then the type II (40.7 for Cr(VI); 11.2 for Ni(II)). The adsorption capacity constants (K(F)) of Freundlich model for type I cells and for type II cells were 10.87 and 8.78 for Ni(II) and 13.60 and 10.99 for Cr(VI), respectively.  相似文献   

14.
Cell-free extracts (CFEs) of chromium-resistant bacterium Bacillus sphaericus AND 303 isolated from serpentine soil of Andaman, India reduced Cr(VI) in in vitro condition, and the reductase activity was solely localized in the soluble cell-fractions (S12, S32, and S150). The enzyme was constitutive as the CFEs from cells grown in Cr(VI)-free and Cr(VI)-containing media reduced a more or less equal amount of Cr(VI). Optimum Cr(VI) reductase activity was obtained at an enzyme (S150) concentration equivalent to 4.56 mg protein/mL, 300 μM Cr(VI) and pH 6.0 after 30 min incubation at 30°C. The enzyme was heat labile; 80% of its activity was lost when exposed at 70°C for 15 min. Kinetics of Cr(VI) reductase activity fit well with the linearized Lineweaver-Burk plot and showed a Vmax of 1.432 μmol Cr(VI)/mg protein/min and Km of 158.12 μM Cr(VI). The presence of additional electron donors accelerated Cr(VI) reductase activity of CFE, and an increase of 28% activity over control was recorded with 1.0 μM NADH. Heavy metal ions such as Ni(II), Cu(II), and Cd(II) were strong inhibitors of Cr(VI) reductase unlike that of 100 μM Co(II), which retained 93% activity over control.  相似文献   

15.
The oxidation of D-lactobionic acid by Cr(VI) yields the 2-ketoaldobionic acid and Cr(3+) as final products when a 20-times or higher excess of the aldobionic acid over Cr(VI) is used. The redox reaction takes place through a complex multistep mechanism, which involves the formation of intermediate Cr(IV) and Cr(V) species. Cr(IV) reacts with lactobionic acid much faster than Cr(V) and Cr(VI) do, and cannot be directly detected. However, the formation of CrO(2)(2+), observed by the first time for an acid saccharide/Cr(VI) system, provides indirect evidence for the intermediacy of Cr(IV) in the reaction path. Cr(VI) and the intermediate Cr(V) react with lactobionic acid at comparable rates, being the complete rate laws for the Cr(VI) and Cr(V) consumption expressed by: -d[Cr(VI)]/dt=[k(I)+k(II)[H(+)]][lactobionicacid][Cr(VI)], where k(I)=(4.1+/-0.1) x 10(-3) M(-1) s(-1) and k(II)=(2.1+/-0.1) x 10(-2) M(-2) s(-1); and -d[Cr(V)]/dt=[k(III)[H(+)]+(k(IV)+k(V)[H(+)])[lactobionicacid]] [Cr(V)], where k(III)=(1.8+/-0.1) x 10(-3) M(-1) s(-1), k(IV)=(1.1+/-0.1) x 10(-2) M(-1) s(-1) and k(V)=(1.0+/-0.1) x 10(-2) M(-2) s(-1), at 33 degrees C. The Electron Paramagnetic Resonance (EPR) spectra show that five-co-ordinate oxo-Cr(V) bischelates are formed at pH 1-5 with the aldobionic acid bound to Cr(V) through the alpha-hydroxyacid group.  相似文献   

16.
Studies on carbonic anhydrase (CA, EC 4.2.1.1) inhibitors have increased due to several therapeutic applications while there are few investigations on activators. Here we investigated CA inhibitory and activatory capacities of a series of dopaminergic compounds on human carbonic anhydrase (hCA) isozymes I, II, and VI. 2-Amino-1,2,3,4-tetrahydronaphthalene-6,7-diol hydrobromide and 2-amino-1,2,3,4-tetrahydronaphthalene-5,6-diol hydrobromide were found to show effective inhibitory action on hCA I and II whereas 2-amino-5,6-dibromoindan hydrobromide and 2-amino-5-bromoindan hydrobromide exhibited only moderate inhibition against both isoforms, being more effective inhibitors of hCA VI. Ki values of the molecules 36 were in the range of 41.12–363 μM against hCA I, of 0.381–470 μM against hCA II and of 0.578–1.152 μM against hCA VI, respectively. Compound 7 behaved as a CA activator with KA values of 27.3 μM against hCA I, of 18.4 μM against hCA II and of 8.73 μM against hCA VI, respectively.  相似文献   

17.
The present study was aimed to localize and characterize hexavalent chromate [Cr(VI)] reductase activity of the extreme alkaliphilic Amphibacillus sp. KSUCr3 (optimal growth pH 10.5). The resting cells were able to reduce about 62 % of the toxic heavy metal Cr(VI) at initial concentration of 200 μM within 30 min. Cell permeabilization resulted in decrease of Cr(VI) reduction in comparison to untreated cells. Enzymatic assays of different sub-cellular fractions of Amphibacillus sp. KSUCr3 demonstrated that the Cr(VI) reductase was mainly associated with the membranous fraction and expressed constitutively. In vitro studies of the crude enzyme indicated that copper ion was essential for Cr(VI) reductase activity. In addition, Ca2? and Mn2? slightly stimulated the chromate reductase activity. Glucose was the best external electron donor, showing enhancement of the enzyme activity by about 3.5-fold. The K (m) and V (max) determined for chromate reductase activity in the membranous fraction were 23.8 μM Cr(VI) and 72 μmol/min/mg of protein, respectively. Cr(VI) reductase activity was maximum at 40 °C and pH 7.0 and it was significantly inhibited in the presence of disulfide reducers (2-mercaptoethanol), ion chelating agent (EDTA), and respiratory inhibitors (CN and Azide). Complete reduction of 100 and 200 μM of Cr(VI) by membrane associated enzyme were observed within 40 and 180 min, respectively. However, it should be noted that biochemical characterization has been done with crude enzyme only, and that final conclusion can only be drawn with the purified enzyme.  相似文献   

18.
Chromium can be found in the environment in two main valence states: hexavalent (Cr(VI)) and trivalent (Cr(III)). Cr(VI) salts are well known human carcinogens, but the results from in vitro studies are often conflicting. Cr(VI) primarily enters the cells and undergoes metabolic reduction; however, the ultimate product of this reduction, Cr(III) predominates within the cell. In the present work, we compared the effects of tri- and hexavalent chromium on the DNA damage and repair in human lymphocytes using the alkaline single cell gel electrophoresis (comet assay). Potassium dichromate induced DNA damage in the lymphocytes, measured as the increase in comet tail moment. The effect was dose-dependent. Treated cells were able to recover within a 120-min incubation. Cr(III) caused greater DNA migration than Cr(VI). The lymphocytes did not show measurable DNA repair. Vitamin C at 50 microM reduced the extent of DNA migration. This was either due to a decrease in DNA strand breaks and/or alkali labile sites induced by Cr(VI) or to the formation of DNA crosslinks by Cr(VI) in the presence of vitamin C. Vitamin C, however, did not modify the effects of Cr(III). Catalase, an enzyme inactivating hydrogen peroxide, decreased the extent of DNA damage induced by Cr(VI) but not the one induced by Cr(III). Lymphocytes exposed to Cr(VI) and treated with endonuclease III, which recognizes oxidized pyrimidines, displayed greater extent of DNA damage than those not treated with the enzyme. Such an effect was not observed when Cr(III) was tested. The results obtained suggest that reactive oxygen species and hydrogen peroxide may be involved in the formation of DNA lesions by hexavalent chromium. The comet assay did not indicate the involvement of oxidative mechanisms in the DNA-damaging activity of trivalent chromium and we speculate that its binding to cellular ligands may play a role in its genotoxicity.  相似文献   

19.
Acquisition of death-resistance is critical in the evolution of neoplasia. Our aim was to model the early stages of carcinogenesis by examining intracellular alterations in cells that have acquired apoptosis-resistance after exposure to a complex genotoxin. We previously generated sub-populations of BJ-hTERT human diploid fibroblasts, which have acquired death-resistance following exposure to hexavalent chromium [Cr(VI)], a broad-spectrum genotoxicant. Long-term exposure to certain forms of Cr(VI) is associated with respiratory carcinogenesis. Here, we report on the death-sensitivity of subclonal populations derived from clonogenic survivors of BJ-hTERT cells treated with 5 μM Cr(VI) (DR1, DR2), or selected by dilution-based cloning without treatment (CC1). Following Cr(VI) treatment, CC1 cells downregulated expression of the anti-apoptotic protein Bcl-2 and exhibited extensive expression of cleaved caspase 3. In contrast, the DR cells exhibited no cleaved caspase 3 expression and maintained expression of Bcl-2 following recovery from 24 h Cr(VI) exposure. The DR cells also exhibited attenuated mitochondrial-membrane depolarization and mitochondrial retention of cytochrome c and SMAC/DIABLO following Cr(VI) exposure. The DR cells exhibited less basal mtDNA damage, as compared to CC1 cells, which correlates with intrinsic (non-induced) death-resistance. Notably, there was no difference in p53 protein expression before or after treatment among all cell lines. Taken together, our data suggest the presence of more resilient mitochondria in death-resistant cells, and that death-resistance can be acquired in normal human cells early after genotoxin exposure. We postulate that resistance to mitochondrial-mediated cell death and mitochondrial dysregulation may be an initial phenotypic alteration observed in early stage carcinogenesis.  相似文献   

20.
《Biomarkers》2013,18(2):86-93
Abstract

DNA-protein crosslinks were measured in peripheral blood lymphocytes of chrome-platers and controls from Bulgaria in order to evaluate a genotoxic effect of human exposure to carcinogenic Cr(VI) compounds. Chrome-platers and most of the unexposed controls were from the industrial city of Jambol; some additional controls were recruited from the seaside town of Burgas. The chrome-platers had significantly elevated levels of chromium in pre- and post-shift urine, erythrocytes and lymphocytes compared with the control subjects. The largest differences between the two groups were found in erythrocyte chromium concentrations which are considered to be indicative of Cr(VI) exposure. Despite the significant differences in internal chromium doses, levels of DNA-protein crosslinks were not significantly different between the combined controls and exposed workers. Individual DNA-protein crosslinks, however, correlated strongly with chromium in erythrocytes at low and moderate doses but at high exposures, such as among the majority of chrome-platers, these DNA adducts were saturated at maximum levels. The saturation of DNA-protein crosslinks seems to occur at 7–8 μg I-1 chromium in erythrocytes whereas a mean erythrocyte chromium among the chrome platers was as high as 22.8 μg l?1. Occupationally unexposed subjects exhibited a significant variability with respect to the erythrocyte chromium concentration, however erythrocyte chromium levels correlated closely with DNA-protein crosslinks in lymphocytes. The controls from Jambol had higher chromium concentrations in erythrocytes and elevated levels of DNA-protein crosslinks compared with Burgas controls. Occupational exposure to formaldehyde among furniture factory workers did not change levels of DNA-protein crosslinks in peripheral lymphocytes. DNA-protein crosslink measurements showed a low intraindividual variability and their levels among both controls and exposed indivduals were not affected by smoking, age or weight.  相似文献   

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