Chromosome aberrations in peripheral lymphocytes of workers employed in the plywood industry

The Interplay between Zinc, Vitamin D and, IL-17 in Patients with Chronic Hepatitis C Liver Disease

Objectives. To assess zinc (Zn) and vitamin D (Vit. D) status in chronic Hepatitis C virus- (HCV) infected patients and their relationship to interleukin- (IL-) 17 and disease severity and then investigate whether Zn and Vit. D3 modulate IL-17 expression in chronic HCV patients. Methods. Seventy patients and fifty healthy subjects were investigated. Serum levels of Zn, Vit. D, and IL-17 were assessed in the patients group and subgroups. Patients lymphocytes were activated in vitro in the presence or absence of Zn or Vit. D3 and then intracellular IL-17 production was assessed using flow cytometry. Results. Zn and Vit. D were significantly decreased in HCV patients. Increasing disease severity leads to more reduction in Zn level opposed by increasing IL-17 level. Zn potently reduced IL-17 production in a dose-related fashion; however it did not exert any toxic effects. Although Vit. D apparently increases IL17 expression, it is unclear whether it is due to its toxic effect on cell count or lack of definite association between Vit. D and both IL-17 and disease severity. Conclusions. This study demonstrates that Zn modulates IL-17 expression and provides a rationale for evaluating this compound as a supplementary agent in the treatment of chronic HCV.

Impact of exposure to wood dust on genotoxicity and cytotoxicity in exfoliated buccal and nasal cells

Wood dust was classified by the IARC as a human carcinogen which causes sinonasal tumours. However, the exposure in different industries varies strongly and the risks of workers depend on the specific situation which can be assessed by the use of biomonitoring methods. The aim of this study was to investigate the workers who are exposed to low dust levels (below the permitted concentrations) with cytogenetic and biochemical methods. Micronuclei (MNi) which are indicative for genomic damage, nuclear buds which reflect gene amplification, binucleated cells which are caused by mitotic disturbances and acute cytotoxicity parameters (pyknosis, karyorrhexis, condensed chromatin, karyolysis) were monitored in buccal and nasal cells of workers of a veneer factory (n = 51) who are exposed to volatile wood-derived compounds, in carpenters of a furniture factory which use no synthetic chemicals (n=38) and in a control group (n = 65). Additionally, markers were measured in blood plasma which reflect inflammations (C-reactive protein, CRP) and the redox status, namely malondialdehyde (MDA) and oxidised low density proteins (oxLDL). No induction of micronucleated cells was observed in both epithelia in the two exposure groups while all other nuclear anomalies except pyknosis were increased; also one health-related biochemical marker (MDA) was significantly elevated in the workers. Taken together, the results of our study show that exposure to low levels of wood dust does not cause formation of MNi indicating that the cancer risks of the workers are not increased as a consequence of genetic damage while positive results were obtained in earlier studies with workers who are exposed to high dust levels. However, our findings indicate that wood dust causes cytotoxic effects which may lead to inflammations.

Workers exposed to wood dust have an increased micronucleus frequency in nasal and buccal cells: results from a pilot study

Wood dust is recognised as a human carcinogen, based on the strong association of wood dust exposure and the elevated risk of malignant tumours of the nasal cavity and paranasal sinuses [sino-nasal cancer (SNC)]. The study aimed to assess genetic damage in workers exposed to wood dust using biomarkers in both buccal and nasal cells that reflect genome instability events, cellular proliferation and cell death frequencies. Nasal and buccal epithelial cells were collected from 31 parquet layers, installers, carpenters and furniture workers (exposed group) and 19 non-exposed workers located in Switzerland. Micronucleus (MN) frequencies were scored in nasal and buccal cells collected among woodworkers. Other nuclear anomalies in buccal cells were measured through the use of the buccal micronucleus cytome assay. MN frequencies in nasal and buccal cells were significantly higher in the exposed group compared to the non-exposed group; odds ratio for nasal cells 3.1 [95% confidence interval (CI) 1.8-5.1] and buccal cells 1.8 (95% CI 1.3-2.4). The exposed group had higher frequencies of cells with nuclear buds, karyorrhectic, pyknotic, karyolytic cells and a decrease in the frequency of basal, binucleated and condensed cells compared to the non-exposed group. Our study confirms that woodworkers have an elevated risk for chromosomal instability in cells of the aerodigestive tract. The MN assay in nasal cells may become a relevant biomonitoring tool in the future for early detection of SNC risk. Future studies should seek to standardise the protocol for MN frequency in nasal cells similar to that for MN in buccal cells.

Radiation risk assessment in professionals working in dental radiology area using buccal micronucleus cytome assay

OBJECTIVE

The aim of this study was to assess the incidence of micronuclei (MN) in buccal mucosal cells of professionals working in radiology area to determine the risk of stochastic effects of radiation.

MATERIALS AND METHODS

All the professionals and students working in King Khalid University - College of Dentistry radiology area were included in the Risk Group (RG = 27). The Control Group (CG = 27) comprised of healthy individual matching the gender and age of the RG. Buccal mucosal scraping from all the 54 subjects of RG and CG were stained with Papanicolaou stain and observed under oil immersion lens (×100) for the presence of micronuclei (MN) in the exfoliated epithelial cells.

RESULTS

There was no significant difference between the incidence of MN in RG and CG (p = >0.05) using t-test.

CONCLUSION

Routine radiation protection protocol does minimize the risk of radiation induced cytotoxicity, however, screening of professionals should be carried out at regular intervals.

Zinc and liver disease

Zinc is an essential trace element required for normal cell growth, development, and differentiation. It is involved in DNA synthesis, RNA transcription, and cell division and activation. It is a critical component in many zinc protein/enzymes, including critical zinc transcription factors. Zinc deficiency/altered metabolism is observed in many types of liver disease, including alcoholic liver disease (ALD) and viral liver disease. Some of the mechanisms for zinc deficiency/altered metabolism include decreased dietary intake, increased urinary excretion, activation of certain zinc transporters, and induction of hepatic metallothionein. Zinc deficiency may manifest itself in many ways in liver disease, including skin lesions, poor wound healing/liver regeneration, altered mental status, or altered immune function. Zinc supplementation has been documented to block/attenuate experimental ALD through multiple processes, including stabilization of gut-barrier function, decreasing endotoxemia, decreasing proinflammatory cytokine production, decreasing oxidative stress, and attenuating apoptotic hepatocyte death. Clinical trials in human liver disease are limited in size and quality, but it is clear that zinc supplementation reverses clinical signs of zinc deficiency in patients with liver disease. Some studies suggest improvement in liver function in both ALD and hepatitis C following zinc supplementation, and 1 study suggested improved fibrosis markers in hepatitis C patients. The dose of zinc used for treatment of liver disease is usually 50 mg of elemental zinc taken with a meal to decrease the potential side effect of nausea.

K-ras mutations in sinonasal cancers in relation to wood dust exposure

Background

Cancer in the sinonasal tract is rare, but persons who have been occupationally exposed to wood dust have a substantially increased risk. It has been estimated that approximately 3.6 million workers are exposed to inhalable wood dust in EU. In previous small studies of this cancer, ras mutations were suggested to be related to wood dust exposure, but these studies were too limited to detect statistically significant associations.

Methods

We examined 174 cases of sinonasal cancer diagnosed in Denmark in the period from 1991 to 2001. To ensure uniformity, all histological diagnoses were carefully reviewed pathologically before inclusion. Paraffin embedded tumour samples from 58 adenocarcinomas, 109 squamous cell carcinomas and 7 other carcinomas were analysed for K-ras codon 12, 13 and 61 point mutations by restriction fragment length polymorphisms and direct sequencing. Information on occupational exposure to wood dust and to potential confounders was obtained from telephone interviews and from registry data.

Results

Among the patients in this study, exposure to wood dust was associated with a 21-fold increased risk of having an adenocarcinoma than a squamous cell carcinoma compared to unexposed [OR = 21.0, CI = 8.0–55.0]. K-ras was mutated in 13% of the adenocarcinomas (seven patients) and in 1% of squamous cell carcinomas (one patient). Of these eight mutations, five mutations were located in the codon 12. The exact sequence change of remaining three could not be identified unambiguously. Among the five identified mutations, the G→A transition was the most common, and it was present in tumour tissue from two wood dust exposed adenocarcinoma patients and one patient with unknown exposure. Previously published studies of sinonasal cancer also identify the GGT → GAT transition as the most common and often related to wood dust exposure.

Conclusion

Patients exposed to wood dust seemed more likely to develop adenocarcinoma compared to squamous cell carcinomas. K-ras mutations were detected in 13% of adenocarcinomas. In this study and previously published studies of sinonasal cancer the found K-ras mutations, were almost exclusively G → A transitions. In conclusion, our study, based on a large representative collection of human SNC tumours, indicates that K-ras mutations are relatively infrequent, and most commonly occur in adenocarcinomas. Wood dust exposure alone was not found to be explanatory for the G→A mutations, but combination of exposure to tobacco, wood dust, and possibly other occupational agents may be a more likely explanation. Overall, the study suggests a limited role for K-ras mutations in development of sinonasal cancer.

Genotoxicity of occupational exposure to wood dust: Micronucleus frequency and nuclear changes in exfoliated buccal mucosa cells

Occupational exposure to wood dust is associated with the occurrence of nasal cancer. In this study, we investigated micronuclei and nuclear changes (NCs: binucleates, karyorrhexis, karyolysis, and the "broken egg" effect) in exfoliated buccal cells of 20 workers exposed to wood dust and 20 age- and sex-matched controls. Micronucleus frequency and the frequency of each of the NCs were significantly higher for wood workers than controls (P < 0.01). Cigarette smoking was associated with increased frequencies of micronuclei and NCs in the buccal mucosa epithelium cells of both the control and exposed groups. Our findings indicate that buccal cells of wood workers display increased levels of genotoxicity and toxicity, and that these biomarker responses may be related to the increased cancer risk among wood workers.

The effects of wood dusts on the redox status and cell death in mouse macrophages (RAW 264.7) and human leukocytes in vitro

Wood dusts are classified as carcinogenic to humans and also produce other toxic, allergic, and acute effects in woodworkers. However, little is known about causative agents in wood dusts and their mechanisms of action. The effects of different tree species and particle size for biological activity were studied. The differences in the production of reactive oxygen species (ROS) and cell death (necrotic and apoptotic) between mouse macrophage (RAW 264.7) cells and human polymorphonuclear leukocytes (PMNL) for pine, birch, and beech dust exposures were investigated in vitro. The pine and birch dust exposure (1-100 microg/ml) produced concentration-dependent ROS production in both the cells, which was one order of magnitude higher with pine dust. The ROS production was faster in human PNML than murine RAW cells. The higher concentrations (500 and/or 1000 microg/ml) decreased ROS formation. With pine and birch dust exposure, this was probably due to the necrotic cell death. The pine dust concentrations of 500 and 1000 microg/ml were cytotoxic to human PMNL. The beech dust exposure activated the ROS production and decreased the cell viability only at the highest concentrations, being least potent of the three dusts. A sign of the apoptotic cell death in the murine RAW cells was observed at the pine dust concentration of 100 microg/ml. The exposure to the birch and beech dusts with a smaller particle size (<5 microm) produced greater ROS production than exposure to the corresponding dust with a wide range of particle sizes. However, changing the particle size did not affect the cell viability. The results indicate that the type of wood dust (tree species and possibly particle size) has a significant impact on the function and viability of phagocytic cells.

DNA damage detected by the comet assay in the white blood cells of workers in a wooden furniture plant

The study was aimed at the assessment of genotoxic effects in workers of a wooden furniture manufacture, based on the level of DNA damage in white blood cells (WBC). The alkaline single cell gel electrophoresis assay (known as the comet assay) in individual cells was adapted for detecting damaged DNA in WBC. The level of DNA damage was determined as the percentage of cells with comets. It was assessed in cells before and after incubation in RPMI 1640 medium and CO(2) at 37 degrees C for 1 h to repair DNA breaks. Thirty-five woodworkers and 41 control subjects were studied. In the woodworkers, significantly more cells with DNA damage (21.5%) were observed than in the control persons (9.7%). A slight but significant decrease in the level of DNA damage was found in the WBC of woodworkers after incubation (17.2%). Significantly higher levels of damaged DNA was observed in woodworkers who either smoked (22.1%) or did not smoke cigarettes (20.8%) than in smokers (13.2%) and non-smokers (7.0%) from the control group. After incubation, a slight decrease in the level of DNA damage was found in both smoking and non-smoking woodworkers compared to the respective subjects in the control group. The increased levels of DNA damage observed in the woodworkers could be associated with the occupational exposure to wood dust in the furniture manufacture.

DNA single-strand breaks and DNA repair in the lymphocytes of wooden furniture workers

DNA single-strand breaks (DNA SSB) in peripheral lymphocytes of wooden furniture workers and a control group, including smokers and nonsmokers, were detected by the microfiltration method. Our results show that cigarette smoking significantly increases the fragmentation of DNA single strands in the wooden furniture workers (by nearly two times) but not in the control group. Moreover, occupational exposure to wood dust and other wooden plant substances significantly induced DNA SSB only in the lymphocytes of smokers (by about two times). DNA repair in the lymphocytes was investigated as 3H incorporation into DNA. High 3H incorporation in the unstimulated lymphocytes of both smoking and nonsmoking workers, as compared to the references, suggests that besides DNA SSB other DNA damage can be caused by occupational exposure in the wooden plant. Since DNA repair is not always perfect, the possibility is high that the low level of DNA repair in the study group may lead to irreversible DNA damage. We think that the workers exposed to wood dust and the substances emitted by furniture coating materials in the plant may be at higher risk for mutagenesis and/or carcinogenesis than the unexposed population.