Biomedical subjects

L Verschaeve

Publications and source records attributed to L Verschaeve.

At least 19 recordsLinked to original sources

PubMed2006

Evaluation of the mutagenic and antimutagenic effects of South African plants.

Dichloromethane and 90% methanol extracts of 42 South African plants were screened for mutagenicity and antimutagenicity using the Salmonella/microsome mutagenicity assay (Ames) against Salmonella typhimurium TA98 and TA100 bacterial strains in the presence and absence of metabolic activator S9. The methanol extracts from whole plants of Helichrysum simillimum, Helichrysum herbaceum and Helichrysum rugulosum indicated mutagenicity. These are the first reported tests on the mutagenicity of Helichrysum species. Six species indicated antimutagenic properties, all in the presence of S9: methanol leaf extract of Bauhinia galpinii, and dichloromethane leaf extracts of Bauhinia galpinii, Clerodendrum myricoides, Datura stramonium, Buddleja saligna, Millettia sutherlandii and Sutherlandia frutescens.

Antimutagenic Agents↗

PubMed2006

Investigation of co-genotoxic effects of radiofrequency electromagnetic fields in vivo.

We investigated the possible combined genotoxic effects of radiofrequency (RF) electromagnetic fields (900 MHz, amplitude modulated at 217 Hz, mobile phone signal) with the drinking water mutagen and carcinogen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX). Female rats were exposed to RF fields for a period of 2 years for 2 h per day, 5 days per week at average whole-body specific absorption rates of 0.3 or 0.9 W/kg. MX was given in the drinking water at a concentration of 19 microg/ml. Blood samples were taken at 3, 6 and 24 months of exposure and brain and liver samples were taken at the end of the study (24 months). DNA damage was assessed in all samples using the alkaline comet assay, and micronuclei were determined in erythrocytes. We did not find significant genotoxic activity of MX in blood and liver cells. However, MX induced DNA damage in rat brain. Co-exposures to MX and RF radiation did not significantly increase the response of blood, liver and brain cells compared to MX exposure only. In conclusion, this 2-year animal study involving long-term exposures to RF radiation and MX did not provide any evidence for enhanced genotoxicity in rats exposed to RF radiation.

Animals↗

PubMed2005

Genetic effects of radiofrequency radiation (RFR).

The possible effects of radiofrequency (RF) exposure on the genetic material of cells are considered very important since damage to the DNA of somatic cells can be linked to cancer development or cell death whereas damage to germ cells can lead to genetic damage in next and subsequent generations. This is why the scientific literature reports many investigations on the subject. According to a number of review papers, the conclusion so far is that there is little evidence that RFR is directly mutagenic and that adverse effects that were reported in some of the papers are predominantly the result of hyperthermia. Yet, some subtle indirect effects on DNA replication and/or transcription of genes under relatively restricted exposure conditions cannot be ruled out. Furthermore, the possibility of combined effects of RFR with environmental carcinogens/mutagens merits further attention. The present paper takes into account more recent investigations but the conclusion remains the same. A majority of studies report no increased (cyto)genetic damage but yet, a considerable number of investigations do. However, many studies were not sufficiently characterized, are therefore difficult to replicate and cannot be compared to others. Experimental protocols were very different from one study to another and investigations from a single laboratory were very often limited in the sample size or number of cells investigated, preventing a robust statistical analysis. Subtle, but significant differences between RFR-exposed and sham-exposed cells cannot be found in such conditions. For the above reasons, it was concluded at a workshop in Löwenstein (November 2002) that further investigations by individual laboratories most probably will not add much to the discussion of radiofrequency radiation (RFR) genotoxicity. Large, well coordinated, international collaborative studies involving participation of several experienced scientists are considered an alternative of uttermost importance. One such study is now being planned.

Animals↗

PubMed2005

Genotoxicity of the Musi River (Hyderabad, India) investigated with the VITOTOX test.

The bacterial VITOTOX genotoxicity test was used to screen water samples collected from three different stations along the banks of the river Musi, in Hyderabad, India. Water was collected at three stations that differed from each other in the nature of the surrounding industrial and other activities. A number of different pollutants were also measured in water, soil and air samples. The three stations were found highly polluted and different with regard to the genotoxicity and toxicity of their samples. These results demonstrate the need for further biological studies in this area to generate valuable data on genomic instability, risk assessment of cancer, and to provide avenues for risk management.

Animals↗

PubMed2005

Cytogenetic investigation of workers professionally exposed to phosphates and their derivatives.

The phosphor industry in Morocco employs a great number of workers that may be exposed to this essential but also toxic compound. In the present investigation, professionally exposed subjects from two different production lines (miners and production unit workers) were investigated for the presence of genetic damage in their peripheral blood lymphocytes. This was done with the well-known micronucleus assay. The proliferation and mitotic indices were also investigated. It was found that the micronucleus frequency was considerably increased compared to the frequency in non-exposed control subjects. Mitotic and proliferation indices were not increased, at least not in a statistically significant way. At the time being this investigation should be considered as a preliminary study in which the influence of potential confounders cannot be adequately assessed. However, our results are non-equivocal and clearly indicate a potential health risk in these workers.

Adult↗

PubMed2004

Investigation of the antimutagenic effects of selected South African medicinal plant extracts.

Dichloromethane extracts from different parts of Rhamnus prinoides, Ornithogalum longibracteatum, Gardenia volkensii, Spirostachys africana, Diospyros whyteana, Syzigium cordatum and Prunus africana were investigated for mutagenic and antimutagenic effects in Salmonella/microsome and micronucleus tests. None of the extracts tested in the Ames test were found to induce mutations or to modify the effect of the mutagen 4-nitroquinoline-oxide (4NQO). In the micronucleus test, extracts from twigs/bark of R. prinoides, twigs of D. whyteana, P. africana and S. cordatum significantly lowered the effect of the mutagen mitomycin C (MMC). Extracts from twigs/bark of G. volkensii and S. africana were genotoxic in the micronucleus test, while extracts of O. longibracteatum leaves potentiated the genotoxicity of MMC. This preliminary investigation shows that plant extracts used in traditional medicine may have particular effects with regard to mutagenicity and antimutagenicity indicating careful use in some instances and the need to isolate their active principles for further research.

4-Nitroquinoline-1-oxide↗

PubMed2003

Effect of coexposure to 50 Hz magnetic fields and an aneugen on human lymphocytes, determined by the cytokinesis block micronucleus assay.

Interference of 50 Hz extremely low frequency magnetic fields (ELF-MF) with the known aneugen vinblastine (VBL) on micronucleus formation was tested with the in vitro cytokinesis block micronucleus assay in human lymphocyte cultures. Isolated lymphocyte cultures were prepared from 18 individuals. Three groups of quadruplicate cultures from six unrelated individuals were exposed to 50 Hz ELF-MF of background (bkg), 80 and 800 microT, respectively, during the complete incubation period (72 h). Twenty-four hours after culture initiation, one replicate culture from each individual within each ELF-MF group was exposed to 0, 5, 10, or 15 ng/ml VBL. The isolated lymphocyte cultures were scored for the presence of micronuclei, the nuclear division index (NDI), and apoptosis. As expected, increased VBL concentration resulted in an increased micronucleus and apoptosis frequency and in a decreased NDI. In the presence of VBL, there was a systematic tendency for increased micronucleus and apoptosis frequency in the ELF-MF exposed groups compared to the bkg group. In the absence of VBL, we observed no statistically significant effect of ELF-MF on micronucleus induction or apoptosis frequency, but the NDI was significantly higher in the 800 microT group compared to the other groups, suggesting an effect of ELF-MF on cell proliferation. An interaction between ELF-MF and VBL on NDI was observed. This interaction reflected the drastic decrease in NDI due to coexposure to VBL.

Adult↗

PubMed2001

Renal function, cytogenetic measurements, and sexual development in adolescents in relation to environmental pollutants: a feasibility study of biomarkers.

BACKGROUND: Human exposure to chemicals is normally monitored by measurement of environmental pollutants in external media. We investigated whether biomarkers in adolescents can show exposure to, and health effects of, common environmental pollutants. METHODS: We recruited 200 17-year-old adolescents (120 girls) from a rural control area and from two suburbs polluted by a lead smelter and two waste incinerators. We measured biomarkers of exposure and of effect in blood and urine samples, and obtained questionnaire data. School doctors measured testicular volume and staged sexual maturation. FINDINGS: Internal exposure was mostly within current standards. Concentrations of lead and cadmium in blood, PCBs (polychlorinated biphenyls) and dioxin-like compounds in serum samples, and metabolites of VOCs (volatile organic compounds) in urine were higher in one or both suburbs than in the control area. Children who lived near the waste incinerators matured sexually at an older age than others, and testicular volume was smaller in boys from the suburbs than in controls. Biomarkers of glomerular or tubular renal dysfunction in individuals were positively correlated with blood lead. Biomarkers of DNA damage were positively correlated with urinary metabolites of PAHs (polycyclic aromatic hydrocarbons) and VOCs. Interpretation Biomarkers can be used to detect environmental exposure to pollutants and measure their biological effects before overt disease develops. Our findings suggest that current environmental standards are insufficient to avoid measurable biological effects.

Adolescent↗

PubMed2001

Genotoxic effects of carbon black particles, diesel exhaust particles, and urban air particulates and their extracts on a human alveolar epithelial cell line (A549) and a human monocytic cell line (THP-1).

The possible genotoxicity of small particulate matter has been under investigation for the last 10 years. Diesel exhaust particles (DEP) are considered as "probably carcinogenic" (IARC group 2A) and a number of studies show genotoxic effects of urban particulate matter (UPM). Carbon black (CB) is carcinogenic in rats. In this study the cytotoxic and genotoxic potency of these three particle types was investigated by exposing human cells (A549 and THP-1 cell lines) in vitro to CB, DEP (SRM 1650, NIST), and UPM (SRM 1648, NIST) for 48 hr. Cytotoxicity was assessed using the Alamar Blue assay, whereas genotoxicity was assessed using the single-cell gel electrophoresis (comet assay). The particles were characterized with regard to their mean diameter in tissue culture medium (CB 100 nm, DEP 400 nm, UPM 2 microm), their total carbon content (CB 99%, DEP 85%, UPM 15%), and their acid-soluble metal composition (UPM >> CB approximately DEP). The concentrations ranged from 16 ng/ml to 16 microg/ml for cytotoxicity tests and from 16 ng/ml to 1.6 microg/ml for genotoxicity tests. In both assays, paraquat was used as a reference chemical. The CB, DEP, and UPM particles showed no significant cytotoxicity. However, all three particles were able to cause significant DNA damage, although to a different extent in the two cell lines. The genotoxicity of washed particles and dichloromethane extracts was also investigated. In THP-1 cells CB washed particles and DEP extracts caused significant DNA damage. This difference in effect may be related to differences in size, structure, and composition of the particles. These results suggest that CB, DEP, and UPM are able to cause DNA damage and, therefore, may contribute to the causation of lung cancer. More detailed studies on influence of size, structure, and composition of the particles are needed.

Air Pollutants↗

PubMed2001

The alkaline single-cell gel electrophoresis/comet assay: a way to study DNA repair in radicle cells of germinating Vicia faba.

Dry seeds are known to accumulate DNA damage with time of storage. Repair of DNA lesions during germination of Vicia faba seeds was followed in the radicles using the alkaline single-cell gel electrophoresis/comet assay. In this assay nuclei were liberated, mixed with agarose and spread out over a microscope slide. After lysis of the nuclear membrane and unwinding of the DNA duplex, DNA was stretched during electrophoresis, giving a comet-like migration pattern. The more DNA was damaged, the higher its mobility. DNA repair took place rapidly the first hours of imbibition and more slowly until ca 33 h after onset of germination. A small amount of heavily damaged cells remained present. Labelling with BrdU provided the possibility to localize repair patches and replicated sites in the comet migration pattern. At 15 h of germination, incorporation of BrdU in radicle DNA was situated at random over the entire comet. At 33 h, DNA repair was more or less accomplished and BrdU was mainly localized in the 'heads' of most comets.

Bromodeoxyuridine↗

PubMed2001

Cytogenetic effects of 900 MHz (GSM) microwaves on human lymphocytes.

The cytogenetic effects of 900 MHz radiofrequency fields were investigated with the chromosome aberration and sister chromatid exchange frequency methods. Three different modes of exposure (continuous, pseudo-random and dummy burst) were studied for different power outputs (0, 2, 8, 15, 25, 50 W). The specific absorption rates varied between 0 and 10 W/kg. We investigated the possible effects of the 900 MHz radiation alone as well as of combined exposure to the chemical or physical mutagens mitomycin C and X-rays. Overall, no indication was found of a mutagenic, and/or co-mutagenic/synergistic effect of this kind of nonionizing radiation.

Chromosome Aberrations↗

PubMed2000

Protective effect of the bile salt hydrolase-active Lactobacillus reuteri against bile salt cytotoxicity.

Bacterial bile salt hydrolysis is considered a risk factor for the development of colon cancer because of the risk of forming harmful secondary bile salts after an initial deconjugation step. In this study, the influence of enhanced bacterial bile salt transformation by the bile salt hydrolase-active Lactobacillus reuteri was studied in batch culture using the microbial suspension of the Simulator of the Human Intestinal Microbial Ecosystem; (SHIME), which was supplemented with oxgall at 5 g/l or 30 g/l. Changes in the fermentative capacity of the microbial ecosystem and the (geno)toxic properties of the SHIME supernatants were investigated. Increasing concentrations of oxgall inhibited the fermentation. Transient cell toxicity was observed for samples supplemented with 5 g oxgall/l, while samples with 30 g oxgall/l exhibited toxicity. The results of the haemolysis test suggest that the detrimental effects were probably due to the membrane-damaging effects of bile salts. In all cases, the adverse effects could be counteracted by the addition of 7.5 +/- 0.5 log10 CFU L. reuteri/ml. Plausible mechanisms for the protective properties of L. reuteri could involve a precipitation of the deconjugated bile salts and a physical binding of bile salts by the bacterium, thereby making the harmful bile salts less bioavailable.

Amidohydrolases↗

PubMed2000

Cytogenetic investigations on microwaves emitted by a 455.7 MHz car phone.

The chromosome aberration or sister chromatid exchange frequency was determined in 455.7 MHz microwave-exposed human lymphocytes and in lymphocytes that were subsequently exposed to MMC or X-rays. The exposure was performed by placing the cells at 5 cm from the antenna of a car phone. In this way the specific absorption ratio was approximately 6.5 W/kg. The temperature and humidity was kept constant during the experiments. No statistically significant difference was found between microwave-exposed and unexposed control samples. When the microwave exposure was followed by exposure to MMC, some differences were found between the combined treatments and the MMC treatments alone. However, there was no consistency in the results. Combined treatments with X-rays did not provide any indication of a synergistic action between the RF fields and X-rays, either. Our data therefore do not support the hypothesis that RF fields act synergistically with chemical or physical mutagens.

Automobiles↗

PubMed2000

Cytogenetic effects of 50 Hz magnetic fields of different magnetic flux densities.

Cytogenetic investigations were performed in human peripheral blood lymphocytes following exposure to 50 Hz magnetic fields alone or in combination with the chemical mutagen mitomycin C or with X-rays. It was found that magnetic fields up to 2500 microT did not significantly influence the chromosome aberration and sister chromatid exchange frequency. Also, the combined treatments failed to indicate the presence of any synergistic, potentiating, or antagonistic effect between the ELF magnetic fields and the mutagens. However, there were two exceptions: Cells exposed to 504 microT magnetic fields before and during cultivation displayed a statistically significant decrease in sister chromatid exchange frequency. Also, when cells were cultivated in the presence of 88.4 microT magnetic fields following X-ray exposures there was a significant increase in chromosome aberration frequency compared to X-ray exposure alone.

Cells, Cultured↗

PubMed1999

The comet assay: a tool to study alteration of DNA integrity in developing plant leaves.

DNA integrity of Nicotiana tabacum L. and Vicia faba L. leaves in different stages of growth was analysed with the single cell gel electrophoresis (comet) assay. With this test DNA of individual cells is stretched by electrophoresis and the migration is measured, which gives an image of the nuclear DNA organisation. Nuclei were sampled when the plants had developed an apical bud, five true leaves and cotyledons. To get an idea of the kind of lesions observed, three different comet protocols were used. The neutral protocol with electrophoresis in a neutral buffer and the semi-alkaline or alkaline assay with alkaline unwinding followed by electrophoresis in neutral alkaline buffer, respectively. For V. faba there was a successive increased cellular DNA mobility with age of the leaves. The percentage DNA migration in control cells of fully developed leaves from N. tabacum almost reached the same level than after irradiation of not fully developed leaves with 50 Gy X-rays. The increased stretching of DNA with leaf age was most obvious if the DNA duplex was converted to single strands by alkali treatment before electrophoresis. Therefore, it could be concluded that with the ageing of leaves there is a decrease in DNA integrity, which could be the result of rising amounts of DNA single-strand breaks and 'alkali-vulnerable sites'.

Comet Assay↗

PubMed1999

VITOTOX bacterial genotoxicity and toxicity test for the rapid screening of chemicals.

The VITOTOX test is a new bacterial genotoxicity test that was previously shown to be very rapid and sensitive. Initially only one Salmonella typhimurium strain (TA104 recN2-4) was used in the test. In this paper we introduce a second strain (TA104pr1) that can be used as an internal control to further enhance the reliability of the test. We demonstrate the usefulness of this pr1 strain in genotoxicity and toxicity testing. We also report on the results of a study where the VITOTOX test was performed on newly synthesized pharmaceutical compounds, or intermediate products in the synthesis of drug candidates. We demonstrate that the test gives identical results when performed independently in two different laboratories and that it correlates well with either the Ames test or SOS chromotest.

Dose-Response Relationship, Drug↗

PubMed1998

Cell cycle dependent aneuploidy induction by X-rays in vitro in human lymphocytes.

Although ionising radiation mainly induces DNA strand breaks leading to chromosomal aberrations, there are indications that it also might induce numerical chromosome aberrations (aneuploidy). The existing data, however, do not provide evidence for a mechanism. To assess the relative sensitivity of the G1 vs. G2 cellular targets, whole blood cultures of lymphocytes were irradiated in vitro with different doses of X-rays (0.5, 1 and 2 Gy). The lymphocytes were harvested after cytochalasin-B blockade to allow the selective study of binucleated cells, having undergone only one division in culture. Harvesting was performed at different sampling times (70, 74, and 78 hours). To evaluate the micronuclei, regarding whole chromosomes or acentric fragments, an oligonucleotide probe that recognises the centromeric region of all human chromosomes was used. The relative percentage of centromere-positive micronuclei ranged from 5 up to 18% depending on the cell cycle stage and on the received dose. Cells exposed during the G1 phase exhibited a slightly higher frequency of centromere-positive micronuclei than cells that were in G2 at the time of exposure. G1 exposure induced a centromere-positive micronuclei dose-effect relationship that was not observed after G2 exposure. The observed difference in response of both phases on the centromere-positive micronuclei yields may be due to the involvement of different targets.

Aneuploidy↗

PubMed1998

Comparative sensitivity of 20 bioassays for soil quality.

Increasing evidence suggests that the use of a single bioassay will never provide a full picture of the quality of the environment. Only a test battery, composed of bioassays of different animal and plant species from different trophic levels will reduce uncertainty, allowing an accurate assessment of the quality of the environment. In the present study, a test battery composed of 20 bioassays of varying biological endpoints has been compared. Apart from lethality and reproductive failure in earthworms, springtails, nematoda, algae and vascular plants, these endpoints also included bioavailibility of metals (bacteria), heat-shock induction (nematodes, algae), DNA damage (bacteria, earthworm, vascular plants), beta-galactosidase (Daphnia) and esterase activity (algae) and a range of immunological parameters (earthworm). Four chemicals (cadmium, phenol, pentachlorophenol and trifluralin)--each representing a different toxic mode of action--were applied in a dilution series (from 1 mg/kg up to 1000 mg/kg) onto OECD standard soil. The tests have been performed both on these artificially contaminated soil samples and on aqueous extracts subsequently obtained from these soils. The results show that the immunological parameters and the loss of weight in the earthworms were among the most sensitive solid-phase assays. Esterase inhibition and heat-shock induction in algae were shown to be extremely sensitive when applied to soil extracts. As previously shown at the species level, no single biological endpoint was shown to be the most sensitive for all four modes of toxic action.

Animals↗