An assessment of the genotoxicity of vanadium

Oxidative damage and cell cycle delay induced by vanadium(III) in human peripheral blood cells

Vanadium (V) is a metal that can enter the environment through natural routes or anthropogenic activity. In the atmosphere, V is present as V oxides, among which vanadium(III) oxide (V2O3) stands out. Cytogenetic studies have shown that V2O3 is genotoxic and cytostatic and induces DNA damage; however, the molecular mechanisms leading to these effects have not been fully explored. Therefore, we treated human peripheral blood lymphocytes in vitro, evaluated the effects of V2O3 on the phases of the cell cycle and the expression of molecules that control the cell cycle and examined DNA damage and the induction of oxidative stress. The results revealed that V2O3 did not affect cell viability at the different concentrations (2, 4, 8 or 16 μg/mL) or exposure times (24 h) used. However, V2O3 affected the percentage of G1- and S-phase cells in the cell cycle, decreased the expression of mRNAs encoding related proteins (cyclin D, cyclin E, CDK2 and CDK4) and increased the expression of γH2AX and the levels of reactive oxygen species. The ability of V2O3 to cause a cell cycle delay in G1-S phase may be associated with a decrease in the mRNA and protein expression of the cyclins/CDKs and with intracellular oxidative stress, which may cause DNA double-strand damage and H2AX phosphorylation.

Cytogenetic damage by vanadium(IV) and vanadium(III) on the bone marrow of mice

Vanadium is a strategic metal that has many important industrial applications and is generated by the use of burning fossil fuels, which inevitably leads to their release into the environment, mainly in the form of oxides. The wastes generated by their use represent a major health hazard. Furthermore, it has attracted attention because several genotoxicity studies have shown that some vanadium compounds can affect DNA; among the most studied compounds is vanadium pentoxide, but studies in vivo with oxidation states IV and III are scarce and controversial. In this study, the genotoxic and cytotoxic potential of vanadium oxides was investigated in mouse bone marrow cells using structural chromosomal aberration (SCA) and mitotic index (MI) test systems. Three groups were administered vanadium(IV) tetraoxide (V2O4) intraperitoneally at 4.7, 9.4 or 18.8 mg/kg, and three groups were administered vanadium(III) trioxide (V2O3) at 4.22, 8.46 or 16.93 mg/kg body weight. The control group was treated with sterile water, and the positive control group was treated with cadmium(II) chloride (CdCl2). After 24 h, all doses of vanadium compounds increased the percentage of cells with SCA and decreased the MI. Our results demonstrated that under the present experimental conditions and doses, treatment with V2O4 and V2O3 induces chromosomal aberrations and alters cell division in the bone marrow of mice.

Effects of Sodium Pyruvate on Vanadyl Sulphate-Induced Reactive Species Generation and Mitochondrial Destabilisation in CHO-K1 Cells

Vanadium is ranked as one of the world’s critical metals considered important for economic growth with wide use in the steel industry. However, its production, applications, and emissions related to the combustion of vanadium-containing fuels are known to cause harm to the environment and human health. Pyruvate, i.e., a glucose metabolite, has been postulated as a compound with multiple cytoprotective properties, including antioxidant and anti-inflammatory effects. The aim of the present study was to examine the antioxidant potential of sodium pyruvate (4.5 mM) in vanadyl sulphate (VOSO₄)-exposed CHO-K1 cells. Dichloro-dihydro-fluorescein diacetate and dihydrorhodamine 123 staining were performed to measure total and mitochondrial generation of reactive oxygen species (ROS), respectively. Furthermore, mitochondrial damage was investigated using MitoTell orange and JC-10 staining assays. We demonstrated that VOSO₄ alone induced a significant rise in ROS starting from 1 h to 3 h after the treatment. Additionally, after 24 and 48 h of exposure, VOSO₄ elicited both extensive hyperpolarisation and depolarisation of the mitochondrial membrane potential (MMP). The two-way ANOVA analysis of the results showed that, through antagonistic interaction, pyruvate prevented VOSO₄-induced total ROS generation, which could be observed at the 3 h time point. In addition, through the independent action and antagonistic interaction with VOSO₄, pyruvate provided a pronounced protective effect against VOSO₄-mediated mitochondrial toxicity at 24-h exposure, i.e., prevention of VOSO₄-induced hyperpolarisation and depolarisation of MMP. In conclusion, we found that pyruvate exerted cytoprotective effects against vanadium-induced toxicity at least in part by decreasing ROS generation and preserving mitochondrial functions

Vanadium oxides modify the expression levels of the p21, p53, and Cdc25C proteins in human lymphocytes treated in vitro

In vitro assays have demonstrated that vanadium compounds interact with biological molecules similar to protein kinases and phosphatases and have also shown that vanadium oxides decrease the proliferation of cells, including human lymphocytes; however, the mechanism, the phase in which the cell cycle is delayed and the proteins involved in this process are unknown. Therefore, we evaluated the effects of vanadium oxides (V₂ O₃ , V₂ O₄ and V₂ O₅ ) in human lymphocyte cultures (concentrations of 2, 4, 8, or 16 μg/ml) on cellular proliferation and the levels of the p53, p21 and Cdc25C proteins. After 24 h of treatment with the different concentrations of vanadium oxides, the cell cycle phases were determined by evaluating the DNA content using flow cytometry, and the levels of the p21, p53 and Cdc25C proteins were assessed by Western blot analysis. The results revealed that the DNA content remained unchanged in every phase of the cell cycle; however, only at high concentrations did protein levels increase. Although, according to previous reports, vanadium oxides induce a delay in proliferation, DNA analysis did not show this occurring in a specific cell cycle phase. Nevertheless, the increases in p53 protein levels may cause this delay.

Molecular characterization of prophenoloxidase-1 (PPO1) and the inhibitory effect of kojic acid on phenoloxidase (PO) activity and on the development of Zeugodacus tau (Walker) (Diptera: Tephritidae)

Phenoloxidase (PO) plays a key role in melanin biosynthesis during insect development. Here, we isolated the 2310-bp full-length cDNA of PPO1 from Zeugodacus tau, a destructive horticultural pest. qRT-polymerase chain reaction showed that the ZtPPO1 transcripts were highly expressed during larval-prepupal transition and in the haemolymph. When the larvae were fed a 1.66% kojic acid (KA)-containing diet, the levels of the ZtPPO1 transcripts significantly increased by 2.79- and 3.39-fold in the whole larvae and cuticles, respectively, while the corresponding PO activity was significantly reduced; in addition, the larval and pupal durations were significantly prolonged; pupal weights were lowered; and abnormal phenotypes were observed. An in vitro inhibition experiment indicated that KA was an effective competitive inhibitor of PO in Z. tau. Additionally, the functional analysis showed that 20E could significantly up-regulate the expression of ZtPPO1, induce lower pupal weight, and advance pupation. Knockdown of the ZtPPO1 gene by RNAi significantly decreased mRNA levels after 24 h and led to low pupation rates and incomplete pupae with abnormal phenotypes during the larval-pupal interim period. These results proved that PO is important for the normal growth of Z. tau and that KA can disrupt the development of this pest insect.

Comparison of five different in vitro assays for assessment of sodium metavanadate cytotoxicity in Chinese hamster ovary cells (CHO-K1 line)

This investigation was undertaken to compare five different in vitro cytotoxicity assays for their power in revealing vanadium-mediated toxicity in Chinese hamster ovary (CHO)-K1 cells. The cells were exposed to sodium metavanadate (NaVO3) in the range of 10–1000 µM for 24 h and thereafter the cytotoxic effects of NaVO3 were measured by colorimetric in vitro assays: the neutral red (NR) test, the 2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxyanilide inner salt (XTT) assay, the resazurin assay, the sulforhodamine B (SR-B) assay, and by microscopic assessment of cell viability using the trypan blue (TB) staining method. Among the assays used, the NR test was the most sensitive, since it revealed metavanadate cytotoxicity at the lowest NaVO3 dose (=50 µM). Also, NaVO3 cytotoxicity expressed as inhibitory concentration (IC) showed the lowest values for the NR test. Three other tests XTT, resazurin, and SR-B assays showed intermediate sensitivity revealing the cytotoxicity of NaVO3 at 100 µM. The corresponding IC10 and IC50 values calculated for the XTT, resazurin, and SR-B tests were similar. The TB staining method was the least sensitive, since it recorded metavanadate cytotoxicity at the highest NaVO3 concentration tested (=600 µM). Based on the cytotoxicity end points measured with the above assays, it can be concluded that lysosomal/Golgi apparatus damage (measured by NR assay) may be the primary effect of NaVO3 on CHO-K1 cells. The disintegration of mitochondria (assessed with the XTT and resazurin assays) probably follows lysosomal impairment. Plasma membrane permeability (staining with TB) occurs at a late stage of NaVO3-induced cytotoxicity on CHO-K1 cells. The results obtained in this research work show that the NR test can be recommended as a very sensitive assay for the assessment of NaVO3 cytotoxicity in the CHO-K1 cell culture model. Considering the convenience of assay performance along with adequate sensitivity, the XTT and resazurin assays can also be advocated for NaVO3 cytotoxicity assessment.

Assessment of the genetic risks of a metallic alloy used in medical implants

The use of artificial implants provides a palliative or permanent solution for individuals who have lost some bodily function through disease, an accident or natural wear. This functional loss can be compensated for by the use of medical devices produced from special biomaterials. Titanium alloy (Ti-6Al-4V) is a well-established primary metallic biomaterial for orthopedic implants, but the toxicity of the chemical components of this alloy has become an issue of concern. In this work, we used the MTT assay and micronucleus assay to examine the cytotoxicity and genotoxicity, respectively, of an extract obtained from this alloy. The MTT assay indicated that the mitochondrial activity and cell viability of CHO-K1 cells were unaffected by exposure to the extract. However, the micronucleus assay revealed DNA damage and an increase in micronucleus frequency at all of the concentrations tested. These results show that ions released from Ti-6Al-4V alloy can cause DNA and nuclear damage and reinforce the importance of assessing the safety of metallic medical devices constructed from biomaterials.

A core in vitro genotoxicity battery comprising the Ames test plus the in vitro micronucleus test is sufficient to detect rodent carcinogens and in vivo genotoxins

In vitro genotoxicity testing needs to include tests in both bacterial and mammalian cells, and be able to detect gene mutations, chromosomal damage and aneuploidy. This may be achieved by a combination of the Ames test (detects gene mutations) and the in vitro micronucleus test (MNvit), since the latter detects both chromosomal aberrations and aneuploidy. In this paper we therefore present an analysis of an existing database of rodent carcinogens and a new database of in vivo genotoxins in terms of the in vitro genotoxicity tests needed to detect their in vivo activity. Published in vitro data from at least one test system (most were from the Ames test) were available for 557 carcinogens and 405 in vivo genotoxins. Because there are fewer publications on the MNvit than for other mammalian cell tests, and because the concordance between the MNvit and the in vitro chromosomal aberration (CAvit) test is so high for clastogenic activity, positive results in the CAvit test were taken as indicative of a positive result in the MNvit where there were no, or only inadequate data for the latter. Also, because Hprt and Tk loci both detect gene-mutation activity, a positive Hprt test was taken as indicative of a mouse-lymphoma Tk assay (MLA)-positive, where there were no data for the latter. Almost all of the 962 rodent carcinogens and in vivo genotoxins were detected by an in vitro battery comprising Ames+MNvit. An additional 11 carcinogens and six in vivo genotoxins would apparently be detected by the MLA, but many of these had not been tested in the MNvit or CAvit tests. Only four chemicals emerge as potentially being more readily detected in MLA than in Ames+MNvit--benzyl acetate, toluene, morphine and thiabendazole--and none of these are convincing cases to argue for the inclusion of the MLA in addition to Ames+MNvit. Thus, there is no convincing evidence that any genotoxic rodent carcinogens or in vivo genotoxins would remain undetected in an in vitro test battery consisting of Ames+MNvit.

Antioxidant enzyme activity and lipid peroxidation in the blood of rats co-treated with vanadium (V(+5)) and chromium (Cr (+3))

Selected biochemical parameters were studied in the blood of outbred, male Wistar rats which daily received to drink deionized water (Group I, control) or solutions of: sodium metavanadate (SMV; 0.100 mg V/mL)-Group II; chromium chloride (CC; 0.004 mg Cr/mL)-Group III; and SMV-CC (0.100 mg V and 0.004 mg Cr/mL)-Group IV for a 12-week period. The diet and fluid intake, body weight gain, and food efficiency ratio (FER) diminished significantly in the rats of Groups II and IV, compared with Groups I and III. The plasma total antioxidant status (TAS) as well as the MDA and the L: -ascorbic acid level in the erythrocytes (RBCs) remained unchanged in all the groups, whereas the plasma L: -ascorbic acid concentration decreased markedly in Group II, compared with Group III. The activities of Cu,Zn-superoxide dismutase (Cu,Zn-SOD), catalase (CAT), cellular glutathione peroxidase (cGSH-Px), and glutathione reductase (GR) in RBCs remained unaltered in all the treated rats. However, the activity of glutathione S-transferase (GST) and the content of reduced glutathione (GSH) in RBCs decreased and increased, respectively, in Groups II, III, and IV, compared with Group I. A vanadium-chromium interaction which affected the GST activity was also found. To summarize, SMV and CC administered separately or in combination in drinking water for 12 weeks did not alter either lipid peroxidation (LPO) or the activities of Cu,Zn-SOD, CAT, cGSH-Px, and GR, which allows a conclusion that both metals in the doses ingested did not reveal their pro-oxidant potential on RBCs.

Evaluation of genotoxicity of oral exposure to tetravalent vanadium in vivo

The trace element vanadium interacts with living cells, in which it exerts a variety of biological effects depending on its chemical form and oxidation state. Tetravalent vanadium was shown to affect several genotoxicity end-points in vitro, but its genotoxic potential in vivo is not elucidated. In this study, the genotoxic effects induced in vivo by subacute oral exposure to vanadyl sulphate (VOSO4), a tetravalent vanadium salt, were investigated. To this aim male CD1 mice were administered with VOSO4 in drinking water over the dose range 2-1000 mg/l for 5 weeks. The incidence of micronucleated blood reticulocytes was measured along treatment period. At the end of treatment, micronuclei in both blood reticulocytes and bone marrow polychromatic erythrocytes were determined; in addition, DNA lesions detectable by comet assay were assessed in marrow and testicular cells. Tissue distribution of vanadium at sacrifice was determined by atomic absorption spectrometry. Comet assays and the analysis of micronuclei in polychromatic erythrocytes did not reveal treatment related effects. A slight increase in micronucleated reticulocytes, with no relationship with the administered dose, was observed in some treated groups. The determination of vanadium content in kidney, liver, spleen, bone, stomach, small intestine and testis highlighted low internal exposure, especially in soft tissues. Overall, data indicate scarce bioavailability for orally administered tetravalent vanadium, and lack of significant genotoxic potential in vivo.

Orthovanadate increased the frequency of aneuploid mouse sperm without micronucleus induction in mouse bone marrow erythrocytes at the same dose level

The objective of the current study was to investigate the ability of orthovanadate to induce aneuploidy in mouse sperm and micronuclei in mouse bone marrow cells at the same dose levels. The BrdU-incorporation assay was performed to test if the chemical treatment altered the duration of the meiotic divisions. It was found that orthovanadate (25mg/kg bw) treatment did not cause meiotic delay. To determine the frequencies of hyperhaploid and diploid sperm, male mice were treated by intraperitoneal (i.p.) injection with 5, 15 or 25mg/kg bw orthovanadate and sperm were sampled from the Caudae epididymes 22 days later. Fluorescence in situ hybridization (FISH) was performed with DNA-probes for chromosomes 8, X or Y. Significant increases in the frequencies of total hyperhaploid sperm (p<0.01) were found with 15 and 25mg/kg bw orthovanadate, indicating induced non-disjunction during male meiosis. The dose-response was described best by a linear equation. Orthovanadate did not significantly increase the frequencies of diploid sperm at any of the three doses tested, indicating that no complete meiotic arrest occurred. Orthovanadate was investigated also by the micronucleus test at i.p. doses of 1, 5, 15 or 25mg/kg bw, followed by bone marrow sampling 24h after treatment. None of the orthovanadate doses caused a significant increase in the rates of micronuclei (MN). Since the results show that orthovanadate induced non-disjunction during male meiosis without an accompanying induction of MN in bone marrow erythrocytes under the present experimental conditions and doses, it is concluded that male germ cells (meiosis) are more sensitive to the aneugenic effects of orthovanadate than somatic cells (mitosis). However, induction of micronuclei was reported in the literature with orthovanadate, vanadylsulfate and ammonium metavanadate, which contradicts the notion that vanadium compounds might be unique germ cell aneugens.

Vanadate induces DNA strand breaks in cultured human fibroblasts at doses relevant to occupational exposure

To study possible genotoxic effects of occupational exposure to vanadium pentoxide, we determined DNA strand breaks (with alkaline comet assay), 8-hydroxy-2'deoxyguanosine (8-OHdG) and the frequency of sister chromatid exchange (SCE) in whole blood leukocytes or lymphocytes of 49 male workers employed in a vanadium factory in comparison to 12 non-exposed controls. In addition, vanadate has been tested in vitro to induce DNA strand breaks in whole blood cells, isolated lymphocytes and cultured human fibroblasts of healthy donors at concentrations comparable to the observed levels of vanadium in vivo. To investigate the impact of vanadate on the repair of damaged DNA, co-exposure to UV or bleomycin was used in fibroblasts, and DNA migration in the alkaline and neutral comet assay was determined. Although, exposed workers showed a significant vanadium uptake (serum: median 5.38microg/l, range 2.18-46.35microg/l) no increase in cytogenetic effects or oxidative DNA damage in leukocytes could be demonstrated. This was consistent with the observation that in vitro exposure of whole blood leukocytes and lymphocytes to vanadate caused no significant changes in DNA strand breaks below concentrations of 1microM (50microg/l). In contrast, vanadate clearly induced DNA fragmentation in cultured fibroblasts at relevant concentrations. Combined exposure of fibroblasts to vanadate/UV or vanadate/bleomycin resulted in non-repairable DNA double strand breaks (DSBs) as seen in the neutral comet assay. We conclude that exposure of human fibroblasts to vanadate effectively causes DNA strand breaks, and co-exposure of cells to other genotoxic agents may result in persistent DNA damage.

Metal accumulation and vanadium-induced multidrug resistance by environmental isolates of Escherichia hermannii and Enterobacter cloacae

Contaminated soils from an oil refinery were screened for the presence of microorganisms capable of accumulating either nickel, vanadium, or both metals. Three strains of bacteria that belonged to the family Enterobacteriaceae were selected. Two of them were Escherichia hermannii strains, and outer membrane profile (OMP) analysis showed that they were similar to a strain of clinical origin; the other one was an Enterobacter cloacae strain that differed from clinical isolates. The selected bacteria accumulated both nickel and vanadium. Growth in the presence of vanadium induced multidrug resistance phenotypes in E. hermannii and E. cloacae. Incubation with this metal changed the OMP profile of E. hermannii but did not produce variations in the expression of the major OMPs of E. cloacae.

Genotoxicity of vanadium pentoxide evaluate by the single cell gel electrophoresis assay in human lymphocytes

Vanadium compounds are extensively used in modern industry and occupational exposure to high doses of Vanadium is quite common. In this study, the genotoxicity of vanadium pentoxide (V2O5) was evaluated directly in whole blood leukocytes and in human lymphocyte cultures using the single-cell gel electrophoresis assay (Comet Assay) to detect DNA damage expressed as DNA strand breaks and alkali labile sites. This chemical produces a clear dose-response in DNA migration in whole blood leukocytes and a significative positive effect only with the highest tested concentration in human lymphocyte cultures. After different recovery times the level of DNA damage returned to the control values. These results indicate that V2O5 is capable to induce DNA single-strand breaks and/or alkali-labile damage.

Oral vanadyl sulfate improves hepatic and peripheral insulin sensitivity in patients with non-insulin-dependent diabetes mellitus

We examined the in vivo metabolic effects of vanadyl sulfate (VS) in non-insulin-dependent diabetes mellitus (NIDDM). Six NIDDM subjects treated with diet and/or sulfonylureas were examined at the end of three consecutive periods: placebo for 2 wk, VS (100 mg/d) for 3 wk, and placebo for 2 wk. Euglycemic hyperinsulinemic (30 mU/m2.min) clamps and oral glucose tolerance tests were performed at the end of each study period. Glycemic control at baseline was poor (fasting plasma glucose 210 +/- 19 mg/dl; HbA1c 9.6 +/- 0.6%) and improved after treatment (181 +/- 14 mg/dl [P < 0.05], 8.8 +/- 0.6%, [P < 0.002]); fasting and post-glucose tolerance test plasma insulin concentrations were unchanged. After VS, the glucose infusion rate during the clamp was increased (by approximately 88%, from 1.80 to 3.38 mg/kg.min, P < 0.0001). This improvement was due to both enhanced insulin-mediated stimulation of glucose uptake (rate of glucose disposal [Rd], +0.89 mg/kg.min) and increased inhibition of HGP (-0.74 mg/kg.min) (P < 0.0001 for both). Increased insulin-stimulated glycogen synthesis (+0.74 mg/kg.min, P < 0.0003) accounted for > 80% of the increased Rd after VS, and the improvement in insulin sensitivity was maintained after the second placebo period. The Km of skeletal muscle glycogen synthase was lowered by approximately 30% after VS treatment (P < 0.05). These results indicate that 3 wk of treatment with VS improves hepatic and peripheral insulin sensitivity in insulin-resistant NIDDM humans. These effects were sustained for up to 2 wk after discontinuation of VS.

Vanadium salts induce cytogenetic effects in in vivo treated mice

Three vanadium salts, vanadyl sulfate (SVO5), sodium orthovanadate (Na3VO4) and ammonium metavanadate (NH4VO3), were tested for induction of genotoxic effects in bone marrow of mice following intragastric treatment. Micronucleus (MN) induction in polychromatic erythrocytes (PCEs), structural (sCA) and numerical (nCA) chromosome aberrations in bone marrow cells were evaluated. The micronucleus test, performed at different harvesting times (0-72 h), was found to be positive for all compounds tested. In contrast, except for vanadyl sulfate, no difference was found between controls and treated animals in the sCA test performed 24 and 36 h after treatment. At the same sampling intervals, second metaphases (M II) were positively scored for nCA induction for all three vanadium salts. In addition, the frequency of hypoploid and hyperploid cells was shown to be statistically different from the control value. Polyploid cells were also induced by all compounds, but their frequency was not statistically significant. The positive results obtained by nCA analysis support the finding of a significant presence of types of micronuclei that are probably aneuploidy-related. This finding was further supported by the successful classification of such micronuclei on the basis of shape and size according to Tinwell and Ashby (1991) during microscope analysis.

Phases of the cell cycle sensitive to endoreduplication induction in CHO-K1 cells

We investigated the sensitive phase of the cell cycle for endoreduplication induction by colchicine, vanadate, 4-nitroquinoline 1-oxide (4NQO), and hydrazine in Chinese hamster CHO-K1 cells, compared to the metaphase endoreduplication inducer rotenone. Treatment of asynchronous cultures and 5-bromodeoxyuridine (BrdU) labeling analysis showed that the detected endoreduplications originated from cells which had been treated with these inducers in S, G2, or metaphase. Exposure to synchronized metaphase cells revealed that the inducers did not lead metaphase cells to endoreduplicate. These results were markedly different from that of rotenone and suggested that the target for the induction of endoreduplication by the tested compounds existed between at least S and G2 phases.

Chemical induction of quadruple and octuple chromosomes in Chinese hamster CHO-K1 cells and relationship between their three-dimensional structure and spatial distribution of BrdU-labeled chromatids

Double endoreduplication of Chinese hamster CHO-K1 cells that exhibited quadruple chromosomes at metaphase was induced by a combination of rotenone and ammonium vanadate treatments. Analysis of sister chromatid differential staining patterns (using 5-bromo-2'-deoxyuridine) revealed that approximately 50% of the quadruple chromosomes did not keep the scheme of "outside replication" of DNA. Based on the ratio of the staining patterns observed, we suggest that the two diplochromosomes forming a quadruple chromosome are held together by a physical link connecting the two original chromatids. Metaphases with octuple chromosomes were also produced by the same treatment. Each chromosome constituting an octuple chromosome was longer and thinner than ordinary metaphase chromosomes. This suggests incomplete chromosome condensation at metaphase. The majority of octuple chromosomes showed the eight constituent chromosomes to be so enmeshed that a planar alignment could not be observed in air-dried preparations.

Genotoxicity of vanadium pentoxide in Chinese hamster V79 cells

Workers in many mining and manufacturing industries are potentially exposed to vanadium. Inhalation of dust containing vanadium pentoxide (V2O5), a pentavalent compound of vanadium, has been reported to cause lung diseases. Information related to the genotoxicity and potential carcinogenicity of V2O5, however, is still limited. In this study, the effect of V2O5 on mitosis, sister-chromatid exchange (SCE), micronucleus formation (MN), and gene mutation in Chinese hamster V79 cells was determined. Cells were treated with varying concentrations of V2O5 for 24 h. The results showed that no significant increases in the frequencies of SCE or gene mutation occurred in V2O5-treated cultures. However, dose-related increases were noted for micronucleated cells in cultures exposed to this compound, and the number of binucleated cells in the presence of cytochalasin B was found to decrease with increasing V2O5 concentrations. Since the micronucleated cells induced by V2O5 contained kinetochore-positive micronuclei, their induction appears to be due to damage to the spindle apparatus. These results indicate that V2O5 is cytotoxic and aneuploidogenic to V79 cells.

Mutagenicity, carcinogenicity and teratogenicity of vanadium compounds

The mutagenic, carcinogenic and teratogenic effects of vanadium and its compounds are reviewed. It is concluded that vanadium is not clastogenic and only weakly mutagenic; it has marked mitogenic activity affecting the distribution of chromosomes during mitosis and possibly causing aneuploidy. The few positive data on effects of vanadium during development leave it open whether direct effects on the embryo of fetus or physiological disturbances in the mother are responsible. No data exist indicating that vanadium is carcinogenic in animals or man, but since it interferes with mitosis and chromosome distribution, the possibility that vanadium might be carcinogenic under certain conditions cannot be dismissed offhand.

Cytogenetic damage induced in human lymphocytes by four vanadium compounds and micronucleus analysis by fluorescence in situ hybridization with a centromeric probe

The genotoxicity of four vanadium compounds, sodium metavanadate (NaVO3), ammonium metavanadate (NH4VO3), sodium ortovanadate (Na3VO4) and vanadyl sulfate (SVO5), was evaluated in human lymphocyte cultures using structural and numerical chromosome aberrations, micronuclei, sister-chromatid exchanges and satellite chromosome associations as endpoints. These compounds were not found to increase the frequency of structural chromosome aberrations whereas a significant increase in numerical aberrations, micronuclei and satellite associations was found. Since these results could have been related to a possible mechanism of the action of vanadium as a mitotic spindle poison, the fluorescence in situ hybridization (FISH) technique was applied to the human lymphocyte micronucleus assay, by means of an alphoid centromere-specific DNA probe. The four vanadium salts showed a micronucleus percentage with positive signal (presence of centromere and thus of whole chromosome(s)) that was always higher than 68% at all doses tested. That confirmed the aneuploidogenic potentiality of vanadium.

Haematological results of vanadium intoxication in Wistar rats

1. Two-month-old rats of the Wistar strain of both sexes received, as sole drinking liquid, an aqueous solution of ammonium metavanadate (AMV) of 0.15 mg V/cm3 concentration for a period of 4 weeks. 2. A small decrease in the amount of food consumed and a significant reduction of the water AMV solution drunk were observed, as compared with the food and water taken up by the control group. 3. In the peripheral blood a significant decrease in the erythrocyte count and haemoglobin level and increased percentage of reticulocytes and polychromatophilic erythrocytes were noted. 4. No changes in the activity of lactate dehydrogenase (LDH) and glucose-6-phosphate dehydrogenase (G-6PD) were found in the erythrocytes of the animals tested. 5. The increase in the neutrophilic granulocyte and lymphocyte count was significant. 6. An inhibitory influence of vanadium on the phagocytic activity of granulocytes was observed.

Proliferation and morphological transformation of BALB/3T3 cells by a prolonged treatment with sodium orthovanadate

BALB/3T3 mouse embryo cells were used to study the effect of sodium orthovanadate on cell proliferation and morphological transformation. In the presence of the chemical (0.25-1.0 micrograms/ml), the cells continued to proliferate after the cultures were confluent. However, contact-inhibited growth was resumed after removal of the chemical from the culture medium. Continued exposure of the cells to the chemical for 4 wk led to the production of numerous foci consisting of morphologically transformed cells. In contrast, as in vitro transformation assay with a 48-hr treatment protocol followed by 4 wk of incubation without the chemical produced negative results. To test the stability of the transformed foci that were produced on prolonged exposure, we isolated 20 foci with distinctly transformed characteristics from treated cultures and grew them in medium without orthovanadate. 15 isolates gradually reverted to contact-inhibited growth and five maintained the transformed phenotype through ten serial subcultures. The results show that the majority of the transformed foci from the orthovanadate-treated culture failed to maintain transformed characteristics in the absence of the chemical. However, a small fraction of the foci appeared to be altered permanently and exhibited a transformed phenotype in the absence of the chemical.

Developmental toxicity evaluation of orthovanadate in the mouse

Sodium orthovanadate in deionized water was administered once daily by gavage on gestational days 6-15 to mice at doses of 0, 7.5, 15, 30, and 60 mg/kg. Dams were killed on day 18 of pregnancy, and fetuses were examined for external, visceral, and skeletal defects. Maternal toxicity was observed at the highest doses of sodium orthovanadate, as evidenced by a significant number of deaths (60 and 30 mg/kg/d) and reduced weight gain and food consumption (30 and 15 mg/kg/d). Embryolethality and teratogenicity were not observed at maternally toxic doses and below, but fetal toxicity was evidenced by a significant delay in the ossification process of some skeletal districts at 30 mg/kg/d. The no-observed-adverse-effect level (NOAEL) for maternal toxicity was 7.5 mg/kg/d, and 15 mg/kg/d represented a NOAEL for developmental toxicity in mice under the conditions of this study.